An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.
A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.
The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.
The hollow, muscular organ that maintains the circulation of the blood.
Small band of specialized CARDIAC MUSCLE fibers that originates in the ATRIOVENTRICULAR NODE and extends into the membranous part of the interventricular septum. The bundle of His, consisting of the left and the right bundle branches, conducts the electrical impulses to the HEART VENTRICLES in generation of MYOCARDIAL CONTRACTION.
Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.
Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.
The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.
Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.
Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.
The chambers of the heart, to which the BLOOD returns from the circulation.
The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.
Proteins containing a region of conserved sequence, about 200 amino acids long, which encodes a particular sequence specific DNA binding domain (the T-box domain). These proteins are transcription factors that control developmental pathways. The prototype of this family is the mouse Brachyury (or T) gene product.
Abnormal thoracoabdominal VISCERA arrangement (visceral heterotaxy) or malformation that involves additional CONGENITAL HEART DEFECTS (e.g., heart isomerism; DEXTROCARDIA) and/or abnormal SPLEEN (e.g., asplenia and polysplenia). Irregularities with the central nervous system, the skeleton and urinary tract are often associated with the syndrome.
The hemodynamic and electrophysiological action of the HEART VENTRICLES.
Pathological conditions involving the HEART including its structural and functional abnormalities.
A specificity protein transcription factor that is expressed primarily in the CENTRAL NERVOUS SYSTEM.
A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulses are abnormally conducted to the HEART VENTRICLES via an ACCESSORY CONDUCTING PATHWAY that is located between the wall of the right or left atria and the ventricles, also known as a BUNDLE OF KENT. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.
Developmental abnormalities involving structures of the heart. These defects are present at birth but may be discovered later in life.
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
A 43-kDa peptide which is a member of the connexin family of gap junction proteins. Connexin 43 is a product of a gene in the alpha class of connexin genes (the alpha-1 gene). It was first isolated from mammalian heart, but is widespread in the body including the brain.
A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (VENTRICULAR DYSFUNCTION), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as MYOCARDIAL INFARCTION.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
An agent used as a substrate in assays for cholinesterases, especially to discriminate among enzyme types.
The study of the electrical activity and characteristics of the HEART; MYOCARDIUM; and CARDIOMYOCYTES.
Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.
The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.
A GATA transcription factor that is expressed predominately in SMOOTH MUSCLE CELLS and regulates vascular smooth muscle CELL DIFFERENTIATION.
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
A congenital defect in which the heart is located on the right side of the THORAX instead of on the left side (levocardia, the normal position). When dextrocardia is accompanied with inverted HEART ATRIA, a right-sided STOMACH, and a left-sided LIVER, the combination is called dextrocardia with SITUS INVERSUS. Dextrocardia may adversely affect other thoracic organs.
Thiolester hydrolases are enzymes that catalyze the hydrolysis of thioester bonds, commonly found in acetyl-CoA and other coenzyme A derivatives, to produce free carboxylic acids and CoASH.
A voltage-gated sodium channel subtype that mediates the sodium ion PERMEABILITY of CARDIOMYOCYTES. Defects in the SCN5A gene, which codes for the alpha subunit of this sodium channel, are associated with a variety of CARDIAC DISEASES that result from loss of sodium channel function.
A form of heart block in which the electrical stimulation of HEART VENTRICLES is interrupted at either one of the branches of BUNDLE OF HIS thus preventing the simultaneous depolarization of the two ventricles.
The genetic unit consisting of three structural genes, an operator and a regulatory gene. The regulatory gene controls the synthesis of the three structural genes: BETA-GALACTOSIDASE and beta-galactoside permease (involved with the metabolism of lactose), and beta-thiogalactoside acetyltransferase.
A phylum of radially symmetrical invertebrates characterized by possession of stinging cells called nematocysts. It includes the classes ANTHOZOA; CUBOZOA; HYDROZOA, and SCYPHOZOA. Members carry CNIDARIAN VENOMS.
This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.
Oligosaccharide antigenic determinants found principally on NK cells and T-cells. Their role in the immune response is poorly understood.
The transference of a heart from one human or animal to another.
Contractile activity of the MYOCARDIUM.
Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.
A subclass of developmentally regulated lamins having a neutral isoelectric point. They are found to disassociate from nuclear membranes during mitosis.
A group of diseases in which the dominant feature is the involvement of the CARDIAC MUSCLE itself. Cardiomyopathies are classified according to their predominant pathophysiological features (DILATED CARDIOMYOPATHY; HYPERTROPHIC CARDIOMYOPATHY; RESTRICTIVE CARDIOMYOPATHY) or their etiological/pathological factors (CARDIOMYOPATHY, ALCOHOLIC; ENDOCARDIAL FIBROELASTOSIS).
Abnormally rapid heartbeats caused by reentry of atrial impulse into the dual (fast and slow) pathways of ATRIOVENTRICULAR NODE. The common type involves a blocked atrial impulse in the slow pathway which reenters the fast pathway in a retrograde direction and simultaneously conducts to the atria and the ventricles leading to rapid HEART RATE of 150-250 beats per minute.
A congenital abnormality in which organs in the THORAX and the ABDOMEN are opposite to their normal positions (situs solitus) due to lateral transposition. Normally the STOMACH and SPLEEN are on the left, LIVER on the right, the three-lobed right lung is on the right, and the two-lobed left lung on the left. Situs inversus has a familial pattern and has been associated with a number of genes related to microtubule-associated proteins.
The functions and activities of living organisms or their parts involved in generating and responding to electrical charges .
A thioester hydrolase which acts on esters formed between thiols such as DITHIOTHREITOL or GLUTATHIONE and the C-terminal glycine residue of UBIQUITIN.
Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.
Recording of the moment-to-moment electromotive forces of the heart on a plane of the body surface delineated as a vector function of time.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Unexpected rapid natural death due to cardiovascular collapse within one hour of initial symptoms. It is usually caused by the worsening of existing heart diseases. The sudden onset of symptoms, such as CHEST PAIN and CARDIAC ARRHYTHMIAS, particularly VENTRICULAR TACHYCARDIA, can lead to the loss of consciousness and cardiac arrest followed by biological death. (from Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005)
Dibenzoquinolines derived in plants from (S)-reticuline (BENZYLISOQUINOLINES).
Transmission of sound waves through vibration of bones in the SKULL to the inner ear (COCHLEA). By using bone conduction stimulation and by bypassing any OUTER EAR or MIDDLE EAR abnormalities, hearing thresholds of the cochlea can be determined. Bone conduction hearing differs from normal hearing which is based on air conduction stimulation via the EAR CANAL and the TYMPANIC MEMBRANE.
Elements of limited time intervals, contributing to particular results or situations.
Transmission of the readings of instruments to a remote location by means of wires, radio waves, or other means. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A form of CARDIAC MUSCLE disease that is characterized by ventricular dilation, VENTRICULAR DYSFUNCTION, and HEART FAILURE. Risk factors include SMOKING; ALCOHOL DRINKING; HYPERTENSION; INFECTION; PREGNANCY; and mutations in the LMNA gene encoding LAMIN TYPE A, a NUCLEAR LAMINA protein.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
A major nerve of the upper extremity. In humans, the fibers of the median nerve originate in the lower cervical and upper thoracic spinal cord (usually C6 to T1), travel via the brachial plexus, and supply sensory and motor innervation to parts of the forearm and hand.
The heart of the fetus of any viviparous animal. It refers to the heart in the postembryonic period and is differentiated from the embryonic heart (HEART/embryology) only on the basis of time.
Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.
The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.
A conical fibro-serous sac surrounding the HEART and the roots of the great vessels (AORTA; VENAE CAVAE; PULMONARY ARTERY). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers.
Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.
A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).
Proteins encoded by homeobox genes (GENES, HOMEOBOX) that exhibit structural similarity to certain prokaryotic and eukaryotic DNA-binding proteins. Homeodomain proteins are involved in the control of gene expression during morphogenesis and development (GENE EXPRESSION REGULATION, DEVELOPMENTAL).
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
An intermediate filament protein found predominantly in smooth, skeletal, and cardiac muscle cells. Localized at the Z line. MW 50,000 to 55,000 is species dependent.
Flaps of tissue that prevent regurgitation of BLOOD from the HEART VENTRICLES to the HEART ATRIA or from the PULMONARY ARTERIES or AORTA to the ventricles.
Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.
A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.
A subgroup of cyclic nucleotide-regulated ION CHANNELS of the superfamily of pore-loop cation channels that are opened by hyperpolarization rather than depolarization. The ion conducting pore passes SODIUM, CALCIUM, and POTASSIUM cations with a preference for potassium.
The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the embryo.
The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioral phenomena.
The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.
Type III intermediate filament proteins that assemble into neurofilaments, the major cytoskeletal element in nerve axons and dendrites. They consist of three distinct polypeptides, the neurofilament triplet. Types I, II, and IV intermediate filament proteins form other cytoskeletal elements such as keratins and lamins. It appears that the metabolism of neurofilaments is disturbed in Alzheimer's disease, as indicated by the presence of neurofilament epitopes in the neurofibrillary tangles, as well as by the severe reduction of the expression of the gene for the light neurofilament subunit of the neurofilament triplet in brains of Alzheimer's patients. (Can J Neurol Sci 1990 Aug;17(3):302)
Formation of differentiated cells and complicated tissue organization to provide specialized functions.
Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.
The medial terminal branch of the sciatic nerve. The tibial nerve fibers originate in lumbar and sacral spinal segments (L4 to S2). They supply motor and sensory innervation to parts of the calf and foot.
Histochemical localization of immunoreactive substances using labeled antibodies as reagents.
Genetic diseases that are linked to gene mutations on the X CHROMOSOME in humans (X CHROMOSOME, HUMAN) or the X CHROMOSOME in other species. Included here are animal models of human X-linked diseases.
A type of fluent aphasia characterized by an impaired ability to repeat one and two word phrases, despite retained comprehension. This condition is associated with dominant hemisphere lesions involving the arcuate fasciculus (a white matter projection between Broca's and Wernicke's areas) and adjacent structures. Like patients with Wernicke aphasia (APHASIA, WERNICKE), patients with conduction aphasia are fluent but commit paraphasic errors during attempts at written and oral forms of communication. (From Adams et al., Principles of Neurology, 6th ed, p482; Brain & Bannister, Clinical Neurology, 7th ed, p142; Kandel et al., Principles of Neural Science, 3d ed, p848)
Rapid, irregular atrial contractions caused by a block of electrical impulse conduction in the right atrium and a reentrant wave front traveling up the inter-atrial septum and down the right atrial free wall or vice versa. Unlike ATRIAL FIBRILLATION which is caused by abnormal impulse generation, typical atrial flutter is caused by abnormal impulse conduction. As in atrial fibrillation, patients with atrial flutter cannot effectively pump blood into the lower chambers of the heart (HEART VENTRICLES).
Diagnosis of disease states by recording the spontaneous electrical activity of tissues or organs or by the response to stimulation of electrically excitable tissue.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.
Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.
Use of electric potential or currents to elicit biological responses.
The hemodynamic and electrophysiological action of the HEART ATRIA.
Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.
Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.
A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.
Morphological and physiological development of EMBRYOS or FETUSES.
Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.
An enzyme that catalyzes the hydrolysis of ACETYLCHOLINE to CHOLINE and acetate. In the CNS, this enzyme plays a role in the function of peripheral neuromuscular junctions. EC 3.1.1.7.
Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Diseases of the peripheral nerves external to the brain and spinal cord, which includes diseases of the nerve roots, ganglia, plexi, autonomic nerves, sensory nerves, and motor nerves.
The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.
The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.
Peripheral, autonomic, and cranial nerve disorders that are associated with DIABETES MELLITUS. These conditions usually result from diabetic microvascular injury involving small blood vessels that supply nerves (VASA NERVORUM). Relatively common conditions which may be associated with diabetic neuropathy include third nerve palsy (see OCULOMOTOR NERVE DISEASES); MONONEUROPATHY; mononeuropathy multiplex; diabetic amyotrophy; a painful POLYNEUROPATHY; autonomic neuropathy; and thoracoabdominal neuropathy. (From Adams et al., Principles of Neurology, 6th ed, p1325)
The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.
Neurons which activate MUSCLE CELLS.
Examinations used to diagnose and treat heart conditions.
A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.
The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot.
The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.
The two longitudinal ridges along the PRIMITIVE STREAK appearing near the end of GASTRULATION during development of nervous system (NEURULATION). The ridges are formed by folding of NEURAL PLATE. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the NEURAL TUBE.
A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (CORONARY ARTERY DISEASE), to obstruction by a thrombus (CORONARY THROMBOSIS), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (MYOCARDIAL INFARCTION).
Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.
A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.
A procedure to stop the contraction of MYOCARDIUM during HEART SURGERY. It is usually achieved with the use of chemicals (CARDIOPLEGIC SOLUTIONS) or cold temperature (such as chilled perfusate).
Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.
An exotic species of the family CYPRINIDAE, originally from Asia, that has been introduced in North America. They are used in embryological studies and to study the effects of certain chemicals on development.
Entrapment of the MEDIAN NERVE in the carpal tunnel, which is formed by the flexor retinaculum and the CARPAL BONES. This syndrome may be associated with repetitive occupational trauma (CUMULATIVE TRAUMA DISORDERS); wrist injuries; AMYLOID NEUROPATHIES; rheumatoid arthritis (see ARTHRITIS, RHEUMATOID); ACROMEGALY; PREGNANCY; and other conditions. Symptoms include burning pain and paresthesias involving the ventral surface of the hand and fingers which may radiate proximally. Impairment of sensation in the distribution of the median nerve and thenar muscle atrophy may occur. (Joynt, Clinical Neurology, 1995, Ch51, p45)
The innermost layer of the heart, comprised of endothelial cells.
Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.
Recording of regional electrophysiological information by analysis of surface potentials to give a complete picture of the effects of the currents from the heart on the body surface. It has been applied to the diagnosis of old inferior myocardial infarction, localization of the bypass pathway in Wolff-Parkinson-White syndrome, recognition of ventricular hypertrophy, estimation of the size of a myocardial infarct, and the effects of different interventions designed to reduce infarct size. The limiting factor at present is the complexity of the recording and analysis, which requires 100 or more electrodes, sophisticated instrumentation, and dedicated personnel. (Braunwald, Heart Disease, 4th ed)
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
Recording of the changes in electric potential of muscle by means of surface or needle electrodes.
A generic expression for any tachycardia that originates above the BUNDLE OF HIS.
The hemodynamic and electrophysiological action of the left HEART VENTRICLE. Its measurement is an important aspect of the clinical evaluation of patients with heart disease to determine the effects of the disease on cardiac performance.
Connections between cells which allow passage of small molecules and electric current. Gap junctions were first described anatomically as regions of close apposition between cells with a narrow (1-2 nm) gap between cell membranes. The variety in the properties of gap junctions is reflected in the number of CONNEXINS, the family of proteins which form the junctions.
Treatment process involving the injection of fluid into an organ or tissue.
A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.
The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.

Effect of electrotonic potentials on pacemaker activity of canine Purkinje fibers in relation to parasystole. (1/3691)

Isolated false tendons excised form dog hearts were mounted in a three-chamber tissue bath. Isotonic sucrose solution was perfused in the central chamber to provide a region of depressed conductivity between the fiber segments in chambers 1 and 3, which were perfused with Tyrode's solution. The electrotonic influence of spontaneous or driven responses evoked in chamber 3 during the first half of the spontaneous cycle of a chamber 1 peacemaker delayed the next spontaneous discharge. This effect changed to acceleration when the chamber 3 segment fired during the second half of the spontaneous cycle. We found that subthreshold depolarizing current pulses 50-300 msec applied across the sucrose gap caused similar degrees of delay or acceleration. Furthermore, hyperpolarizing currents caused the reverse pattern. The results indicate that the discharge pattern of a parasystolic focus may be altered by the electrotonic influence of activity in the surrounding tissue. The significance of these findings is considered in relation to the mechanism of production of parasystolic rhythms.  (+info)

Hierarchy of ventricular pacemakers. (2/3691)

To characterize the pattern of pacemaker dominance in the ventricular specialized conduction system (VSCS), escape ventricular pacemakers were localized and quantified in vivo and in virto, in normal hearts and in hearts 24 hours after myocardial infarction. Excape pacemaker foci were localized in vivo during vagally induced atrial arrest by means of electrograms recorded from the His bundle and proximal bundle branches and standard electrocardiographic limb leads. The VSCS was isolated using a modified Elizari preparation or preparations of each bundle branch. Peacemakers were located by extra- and intracellular recordings. Escape pacemaker foci in vivo were always in the proximal conduction system, usually the left bundle branch. The rate was 43+/-11 (mean+/-SD) beats/min. After beta-adrenergic blockade, the mean rate fell to 31+/-10 beats/min, but there were no shifts in pacemaker location. In the infarcted hearts, pacemakers were located in the peripheral left bundle branch. The mean rate was 146+/-20 beats/min. In isolated normal preparations, the dominant pacemakers usually were in the His bundle, firing at a mean rate of 43+/-10 beats/min. The rates of pacemakers diminished with distal progression. In infarcted hearts, the pacemakers invariably were in the infarct zone. The mean firing rates were not influenced by beta-adrenergic blockade. The results indicate that the dominant pacemakers are normally in the very proximal VSCS, but after myocardial infarction pacemaker dominance is shifted into the infarct. Distribution of pacemaker dominance is independent of sympathetic influence.  (+info)

Localization of sympathetic, parasympathetic and sensory neurons innervating the heart of the Beijing duck by means of the retrograde transport of horseradish peroxidase. (3/3691)

Sympathetic, parasympathetic and sensory neurons were labeled by injections of horseradish peroxidase into various regions of the heart in 33 Beijing ducks. Sympathetic postganglionic neurons innervating the heart were located in the paravertebral ganglia C15 (C16 is the last cervical segment in the duck) to T3, especially in the ganglion T1. The coronary sulcus and ventricle were more abundantly innervated by sympathetic neurons than the atrium. The left side of the heart was preferentially innervated by sympathetic postganglionic neurons in the left side of paravertebral ganglia but the right side of the heart were equally supplied from the right and left ganglia. Within the medulla oblongata, the number of labeled vagal preganglionic neurons in the nucleus ambiguus was much greater than that in the dorsal motor nucleus of the vagus nerve. Labeled neurons of the nucleus ambiguus were found in many ducks injected into the coronary sulcus. Cardiac sensory neurons were observed in the dorsal root ganglia C15 to T2 (highest in the ganglion T1) and in the nodose and jugular ganglia of the vagus nerve. These labeled neurons probably form the afferent and efferent limbs of cardiac reflexes and control circulation in the Beijing duck.  (+info)

Differential effects of a segment of slow conduction on reentrant ventricular tachycardia in the rabbit heart. (4/3691)

BACKGROUND: The purpose of this study was to compare differential effects of a segment of slow conduction during ventricular tachycardia (VT) due to depression of the action potential and electrical uncoupling. METHODS AND RESULTS: In 33 Langendorff-perfused rabbit hearts, a ring of anisotropic left ventricular subepicardium was created by a cryoprocedure. Reentrant VT was produced by incremental pacing. Slow conduction in a segment of the ring was created by selective perfusion of the LAD with 10 mmol/L potassium or 0.75 mmol/L heptanol. As a result, VT cycle length increased from 193+/-34 to 235+/-37 ms (potassium) and 227+/-42 ms (heptanol). Reset curves were made by applying premature stimuli proximal to the area of depressed conduction. In a ring of uniform anisotropic tissue, the reset curve was almost completely flat. Electrical uncoupling of part of the ring (nonuniform anisotropy) resulted in a mixed reset curve. In both substrates, early premature beats failed to terminate VT. Depression of part of the ring by increasing K+ resulted in a completely sloped reset curve, indicating a gap of partial excitability. Under these conditions, in 19 of 24 hearts, premature beats terminated VT by conduction block in the high K+ area. CONCLUSIONS: The nature of the area of slow conduction determines the type of reset response and the ability to terminate VT.  (+info)

A method for determining baroreflex-mediated sympathetic and parasympathetic control of the heart in pregnant and non-pregnant sheep. (5/3691)

1. The cardiac baroreflex was measured in four non-pregnant and six pregnant ewes before and during beta-adrenoreceptor blockade with propranolol and before and during vagal blockade with atropine. Arterial pressure was raised by phenylephrine and lowered by sodium nitroprusside. The relationships between mean arterial pressure (MAP) and heart rate (HR), between MAP and heart rate variability (HRV) measured as the coefficient of variation (c.v.) of the mean pulse interval (PI), and between MAP and HRV measured by power spectral analysis were determined. 2. The MAP-HR relationship showed that in pregnant ewes the gain of the cardiac baroreflex was reduced when compared with non-pregnant ewes. Threshold and saturation pressures were higher, maximum achievable HR was lower and there was a decrease in the operating range. 3. V-shaped relationships were obtained between MAP and HRV (measured as the c.v. of PI) and between MAP and power spectral density in the frequency range 0.04-0. 08 Hz. Using selective autonomic blockade the negative, or downward, slope of the V shape was shown to be a measure of baroreceptor-induced, sympathetically mediated effects on HRV. The upward, or positive, slope of the V shape was a measure of baroreceptor-induced, vagally mediated effects. Similar results were also obtained from the cardiac power spectrum, but it was less sensitive. The MAP at which the two slopes intersected was the same as the resting MAP. 4. In pregnant ewes, the slope of the downward limb of the V-shaped relationship between HRV (when measured as the c.v. of PI) and MAP was less than in non-pregnant ewes. 5. The relationship between MAP and the coefficient of variation of the mean pulse interval can therefore be used to measure the degree to which baroreceptor-induced sympathetic and parasympathetic activity affects the heart. 6. The resting MAP is the pressure at which the net effect of these sympathetic and parasympathetic influences on the heart is at a minimum. Studies of both the MAP-HR and MAP-HRV relationships in pregnant and non-pregnant sheep show that in pregnant sheep, there is attenuation of baroreceptor-mediated sympathetic effects on the heart.  (+info)

A comparison of an A1 adenosine receptor agonist (CVT-510) with diltiazem for slowing of AV nodal conduction in guinea-pig. (6/3691)

1. The purpose of this study was to compare the pharmacological properties (i.e. the AV nodal depressant, vasodilator, and inotropic effects) of two AV nodal blocking agents belonging to different drug classes; a novel A1 adenosine receptor (A1 receptor) agonist, N-(3(R)-tetrahydrofuranyl)-6-aminopurine riboside (CVT-510), and the prototypical calcium channel blocker diltiazem. 2. In the atrial-paced isolated heart, CVT-510 was approximately 5 fold more potent to prolong the stimulus-to-His bundle (S-H interval), a measure of slowing AV nodal conduction (EC50 = 41 nM) than to increase coronary conductance (EC50 = 200 nM). At concentrations of CVT-510 (40 nM) and diltiazem (1 microM) that caused equal prolongation of S-H interval (approximately 10 ms), diltiazem, but not CVT-510, significantly reduced left ventricular developed pressure (LVP) and markedly increased coronary conductance. CVT-510 shortened atrial (EC50 = 73 nM) but not the ventricular monophasic action potentials (MAP). 3. In atrial-paced anaesthetized guinea-pigs, intravenous infusions of CVT-510 and diltiazem caused nearly equal prolongations of P-R interval. However, diltiazem, but not CVT-510, significantly reduced mean arterial blood pressure. 4. Both CVT-510 and diltiazem prolonged S-H interval, i.e., slowed AV nodal conduction. However, the A1 receptor-selective agonist CVT-510 did so without causing the negative inotropic, vasodilator, and hypotensive effects associated with diltiazem. Because CVT-510 did not affect the ventricular action potential, it is unlikely that this agonist will have a proarrythmic action in ventricular myocardium.  (+info)

A subpopulation of apoptosis-prone cardiac neural crest cells targets to the venous pole: multiple functions in heart development? (7/3691)

A well-described population of cardiac neural crest (NC) cells migrates toward the arterial pole of the embryonic heart and differentiates into various cell types, including smooth muscle cells of the pharyngeal arch arteries (but not the coronary arteries), cardiac ganglionic cells, and mesenchymal cells of the aortopulmonary septum. Using a replication-incompetent retrovirus containing the reporter gene LacZ, administered to the migratory neural crest of chicken embryos, we demonstrated another population of cardiac neural crest cells that employs the venous pole as entrance to the heart. On the basis of our present data we cannot exclude the possibility that precursors of these cells might not only originate from the dorsal part of the posterior rhombencephalon, but also from the ventral part. These NC cells migrate to locations surrounding the prospective conduction system as well as to the atrioventricular (AV) cushions. Concerning the prospective conduction system, the tagged neural crest cells can be found in regions where the atrioventricular node area, the retroaortic root bundle, the bundle of His, the left and right bundle branches, and the right atrioventricular ring bundle are positioned. The last area connects the posteriorly located AV node area with the retroaortic root bundle, which receives its neural crest cells through the arterial pole in concert with the cells giving rise to the aortopulmonary septum. The NC cells most probably do not form the conduction system proper, as they enter an apoptotic pathway as determined by concomitant TUNEL detection. It is possible that the NC cells in the heart become anoikic and, as a consequence, fail to differentiate further and merely die. However, because of the perfect timing of the arrival of crest cells, their apoptosis, and a change in electrophysiological behavior of the heart, we postulate that neural crest cells play a role in the last phase of differentiation of the cardiac conduction system. Alternatively, the separation of the central conduction system from the surrounding working myocardium is mediated by apoptotic neural crest cells. As for the presence of NC cells in both the outflow tract and the AV cushions, followed by apoptosis, a function is assigned in the muscularization of both areas, resulting in proper septation of the outflow tract and of the AV region. Failure of normal neural crest development may not only play a role in cardiac outflow tract anomalies but also in inflow tract abnormalities, such as atrioventricular septal defects.  (+info)

Regional differences in the recovery course of tachycardia-induced changes of atrial electrophysiological properties. (8/3691)

BACKGROUND: Regional differences in recovery of tachycardia-induced changes of atrial electrophysiological properties have not been well studied. METHODS AND RESULTS: In the control group (5 dogs), atrial effective refractory period (AERP) and inducibility of atrial fibrillation (AF) were assessed before and every 4 hours for 48 hours after complete atrioventricular junction (AVJ) ablation with 8-week VVI pacing. In experimental group 1 (15 dogs), AERP and inducibility of AF were assessed before and after complete AVJ ablation with 8-week rapid right atrial (RA) pacing (780 bpm) and VVI pacing. In experimental group 2 (7 dogs), AERP and inducibility of AF were assessed before and after 8-week rapid left atrial (LA) pacing and VVI pacing. AERP and inducibility and duration of AF were obtained from 7 epicardial sites. In the control group, atrial electrophysiological properties obtained immediately and during 48-hour measurements after pacing did not show any change. In the 2 experimental groups, recovery of atrial electrophysiological properties included a progressive recovery of AERP shortening, recovery of AERP maladaptation, and decrease of duration and episodes of reinduced AF. However, recovery of shortening and maladaptation of AERP and inducibility of AF was slower at the LA than at the RA and Bachmann's bundle. CONCLUSIONS: The LA had a slower recovery of tachycardia-induced changes of atrial electrophysiological properties, and this might play a critical role in initiation of AF.  (+info)

The heart conduction system is a group of specialized cardiac muscle cells that generate and conduct electrical impulses to coordinate the contraction of the heart chambers. The main components of the heart conduction system include:

1. Sinoatrial (SA) node: Also known as the sinus node, it is located in the right atrium near the entrance of the superior vena cava and functions as the primary pacemaker of the heart. It sets the heart rate by generating electrical impulses at regular intervals.
2. Atrioventricular (AV) node: Located in the interatrial septum, near the opening of the coronary sinus, it serves as a relay station for electrical signals between the atria and ventricles. The AV node delays the transmission of impulses to allow the atria to contract before the ventricles.
3. Bundle of His: A bundle of specialized cardiac muscle fibers that conducts electrical impulses from the AV node to the ventricles. It divides into two main branches, the right and left bundle branches, which further divide into smaller Purkinje fibers.
4. Right and left bundle branches: These are extensions of the Bundle of His that transmit electrical impulses to the respective right and left ventricular myocardium. They consist of specialized conducting tissue with large diameters and minimal resistance, allowing for rapid conduction of electrical signals.
5. Purkinje fibers: Fine, branching fibers that arise from the bundle branches and spread throughout the ventricular myocardium. They are responsible for transmitting electrical impulses to the working cardiac muscle cells, triggering coordinated ventricular contraction.

In summary, the heart conduction system is a complex network of specialized muscle cells responsible for generating and conducting electrical signals that coordinate the contraction of the atria and ventricles, ensuring efficient blood flow throughout the body.

The atrioventricular (AV) node is a critical part of the electrical conduction system of the heart. It is a small cluster of specialized cardiac muscle cells located in the lower interatrial septum, near the opening of the coronary sinus. The AV node receives electrical impulses from the sinoatrial node (the heart's natural pacemaker) via the internodal pathways and delays their transmission for a brief period before transmitting them to the bundle of His and then to the ventricles. This delay allows the atria to contract and empty their contents into the ventricles before the ventricles themselves contract, ensuring efficient pumping of blood throughout the body.

The AV node plays an essential role in maintaining a normal heart rhythm, as it can also function as a backup pacemaker if the sinoatrial node fails to generate impulses. However, certain heart conditions or medications can affect the AV node's function and lead to abnormal heart rhythms, such as atrioventricular block or atrial tachycardia.

Neural conduction is the process by which electrical signals, known as action potentials, are transmitted along the axon of a neuron (nerve cell) to transmit information between different parts of the nervous system. This electrical impulse is generated by the movement of ions across the neuronal membrane, and it propagates down the length of the axon until it reaches the synapse, where it can then stimulate the release of neurotransmitters to communicate with other neurons or target cells. The speed of neural conduction can vary depending on factors such as the diameter of the axon, the presence of myelin sheaths (which act as insulation and allow for faster conduction), and the temperature of the environment.

In medical terms, the heart is a muscular organ located in the thoracic cavity that functions as a pump to circulate blood throughout the body. It's responsible for delivering oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body. The heart's rhythmic contractions and relaxations are regulated by a complex electrical conduction system.

The Bundle of His is a bundle of specialized cardiac muscle fibers that conduct electrical impulses to the Purkinje fibers, which then stimulate contraction of the ventricles in the heart. It is named after Wilhelm His, Jr., who first described it in 1893.

The Bundle of His is a part of the electrical conduction system of the heart that helps coordinate the contraction of the atria and ventricles to ensure efficient pumping of blood. The bundle originates from the atrioventricular node, which receives electrical impulses from the sinoatrial node (the heart's natural pacemaker) and transmits them through the Bundle of His to the Purkinje fibers.

The Bundle of His is divided into two main branches, known as the right and left bundle branches, which further divide into smaller fascicles that spread throughout the ventricular myocardium. This ensures a coordinated contraction of the ventricles, allowing for efficient pumping of blood to the rest of the body.

Purkinje fibers are specialized cardiac muscle fibers that are located in the subendocardial region of the inner ventricular walls of the heart. They play a crucial role in the electrical conduction system of the heart, transmitting electrical impulses from the bundle branches to the ventricular myocardium, which enables the coordinated contraction of the ventricles during each heartbeat.

These fibers have a unique structure that allows for rapid and efficient conduction of electrical signals. They are larger in diameter than regular cardiac muscle fibers, have fewer branching points, and possess more numerous mitochondria and a richer blood supply. These features enable Purkinje fibers to conduct electrical impulses at faster speeds, ensuring that the ventricles contract simultaneously and forcefully, promoting efficient pumping of blood throughout the body.

Heart block is a cardiac condition characterized by the interruption of electrical impulse transmission from the atria (the upper chambers of the heart) to the ventricles (the lower chambers of the heart). This disruption can lead to abnormal heart rhythms, including bradycardia (a slower-than-normal heart rate), and in severe cases, can cause the heart to stop beating altogether. Heart block is typically caused by damage to the heart's electrical conduction system due to various factors such as aging, heart disease, or certain medications.

There are three types of heart block: first-degree, second-degree, and third-degree (also known as complete heart block). Each type has distinct electrocardiogram (ECG) findings and symptoms. Treatment for heart block depends on the severity of the condition and may include monitoring, medication, or implantation of a pacemaker to regulate the heart's electrical activity.

The sinoatrial (SA) node, also known as the sinus node, is the primary pacemaker of the heart. It is a small bundle of specialized cardiac conduction tissue located in the upper part of the right atrium, near the entrance of the superior vena cava. The SA node generates electrical impulses that initiate each heartbeat, causing the atria to contract and pump blood into the ventricles. This process is called sinus rhythm.

The SA node's electrical activity is regulated by the autonomic nervous system, which can adjust the heart rate in response to changes in the body's needs, such as during exercise or rest. The SA node's rate of firing determines the heart rate, with a normal resting heart rate ranging from 60 to 100 beats per minute.

If the SA node fails to function properly or its electrical impulses are blocked, other secondary pacemakers in the heart may take over, resulting in abnormal heart rhythms called arrhythmias.

Heart rate is the number of heartbeats per unit of time, often expressed as beats per minute (bpm). It can vary significantly depending on factors such as age, physical fitness, emotions, and overall health status. A resting heart rate between 60-100 bpm is generally considered normal for adults, but athletes and individuals with high levels of physical fitness may have a resting heart rate below 60 bpm due to their enhanced cardiovascular efficiency. Monitoring heart rate can provide valuable insights into an individual's health status, exercise intensity, and response to various treatments or interventions.

Connexins are a family of proteins that form the structural units of gap junctions, which are specialized channels that allow for the direct exchange of small molecules and ions between adjacent cells. These channels play crucial roles in maintaining tissue homeostasis, coordinating cellular activities, and enabling communication between cells. In humans, there are 21 different connexin genes that encode for these proteins, with each isoform having unique properties and distributions within the body. Mutations in connexin genes have been linked to a variety of human diseases, including hearing loss, skin disorders, and heart conditions.

Electrocardiography (ECG or EKG) is a medical procedure that records the electrical activity of the heart. It provides a graphic representation of the electrical changes that occur during each heartbeat. The resulting tracing, called an electrocardiogram, can reveal information about the heart's rate and rhythm, as well as any damage to its cells or abnormalities in its conduction system.

During an ECG, small electrodes are placed on the skin of the chest, arms, and legs. These electrodes detect the electrical signals produced by the heart and transmit them to a machine that amplifies and records them. The procedure is non-invasive, painless, and quick, usually taking only a few minutes.

ECGs are commonly used to diagnose and monitor various heart conditions, including arrhythmias, coronary artery disease, heart attacks, and electrolyte imbalances. They can also be used to evaluate the effectiveness of certain medications or treatments.

Atrioventricular (AV) block is a disorder of the electrical conduction system of the heart that causes a delay or interruption in the transmission of electrical signals from the atria (the upper chambers of the heart) to the ventricles (the lower chambers of the heart). This results in an abnormal heart rhythm, also known as an arrhythmia.

There are three degrees of AV block:

1. First-degree AV block: In this type of AV block, there is a delay in the conduction of electrical signals from the atria to the ventricles, but all signals are eventually conducted. This condition may not cause any symptoms and is often discovered during a routine electrocardiogram (ECG).
2. Second-degree AV block: In this type of AV block, some electrical signals from the atria are not conducted to the ventricles. There are two types of second-degree AV block: Mobitz type I and Mobitz type II. Mobitz type I is characterized by a progressive prolongation of the PR interval (the time between the electrical activation of the atria and ventricles) until a QRS complex (which represents the electrical activation of the ventricles) is dropped. Mobitz type II is characterized by a constant PR interval with occasional non-conducted P waves.
3. Third-degree AV block: In this type of AV block, no electrical signals are conducted from the atria to the ventricles. The atria and ventricles beat independently of each other, resulting in a slow heart rate (bradycardia) and an irregular rhythm. This condition can be life-threatening if not treated promptly.

The causes of AV block include aging, heart disease, medications, and certain medical conditions such as hypothyroidism and Lyme disease. Treatment depends on the severity of the condition and may include medication, a pacemaker, or surgery.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

Cardiac arrhythmias are abnormal heart rhythms that result from disturbances in the electrical conduction system of the heart. The heart's normal rhythm is controlled by an electrical signal that originates in the sinoatrial (SA) node, located in the right atrium. This signal travels through the atrioventricular (AV) node and into the ventricles, causing them to contract and pump blood throughout the body.

An arrhythmia occurs when there is a disruption in this electrical pathway or when the heart's natural pacemaker produces an abnormal rhythm. This can cause the heart to beat too fast (tachycardia), too slow (bradycardia), or irregularly.

There are several types of cardiac arrhythmias, including:

1. Atrial fibrillation: A rapid and irregular heartbeat that starts in the atria (the upper chambers of the heart).
2. Atrial flutter: A rapid but regular heartbeat that starts in the atria.
3. Supraventricular tachycardia (SVT): A rapid heartbeat that starts above the ventricles, usually in the atria or AV node.
4. Ventricular tachycardia: A rapid and potentially life-threatening heart rhythm that originates in the ventricles.
5. Ventricular fibrillation: A chaotic and disorganized electrical activity in the ventricles, which can be fatal if not treated immediately.
6. Heart block: A delay or interruption in the conduction of electrical signals from the atria to the ventricles.

Cardiac arrhythmias can cause various symptoms, such as palpitations, dizziness, shortness of breath, chest pain, and fatigue. In some cases, they may not cause any symptoms and go unnoticed. However, if left untreated, certain types of arrhythmias can lead to serious complications, including stroke, heart failure, or even sudden cardiac death.

Treatment for cardiac arrhythmias depends on the type, severity, and underlying causes. Options may include lifestyle changes, medications, cardioversion (electrical shock therapy), catheter ablation, implantable devices such as pacemakers or defibrillators, and surgery. It is essential to consult a healthcare professional for proper evaluation and management of cardiac arrhythmias.

The heart atria are the upper chambers of the heart that receive blood from the veins and deliver it to the lower chambers, or ventricles. There are two atria in the heart: the right atrium receives oxygen-poor blood from the body and pumps it into the right ventricle, which then sends it to the lungs to be oxygenated; and the left atrium receives oxygen-rich blood from the lungs and pumps it into the left ventricle, which then sends it out to the rest of the body. The atria contract before the ventricles during each heartbeat, helping to fill the ventricles with blood and prepare them for contraction.

The heart ventricles are the two lower chambers of the heart that receive blood from the atria and pump it to the lungs or the rest of the body. The right ventricle pumps deoxygenated blood to the lungs, while the left ventricle pumps oxygenated blood to the rest of the body. Both ventricles have thick, muscular walls to generate the pressure necessary to pump blood through the circulatory system.

T-box domain proteins are a family of transcription factors that share a highly conserved DNA-binding domain, known as the T-box. The T-box domain is a DNA-binding motif that specifically recognizes and binds to T-box binding elements (TBEs) in the regulatory regions of target genes. These proteins play crucial roles during embryonic development, particularly in the formation of specific tissues and organs, such as the heart, limbs, and brain. Mutations in T-box domain proteins can lead to various congenital defects and developmental disorders. Some examples of T-box domain proteins include TBX1, TBX5, and TBX20.

Heterotaxy syndrome is a rare and complex congenital disorder characterized by the abnormal lateralization or arrangement of internal organs in the chest and abdomen. In this condition, the normal left-right (LR) asymmetry of the thoracic and abdominal organs is disrupted, resulting in either complete or partial reversal of the usual LR orientation. The term "heterotaxy" literally means "different arrangement."

Heterotaxy syndrome can be further classified into two main types:

1. **Ivemark's syndrome** (or left atrial isomerism): In this type, there is a mirror-image reversal of the normal LR organization of the thoracic and abdominal organs. This results in both sides of the body having structures that are typically found on the left side (left atrial isomerism). Common features include:
* Complete heart block or complex congenital heart defects, such as transposition of the great arteries, double outlet right ventricle, and total anomalous pulmonary venous return.
* Bilateral bilobed lungs with a central location of the liver (situs ambiguus).
* Bronchial malformations, including bilateral eparterial bronchi.
* Gastrointestinal tract abnormalities, such as intestinal malrotation and biliary atresia.
* Increased incidence of situs inversus totalis (complete mirror-image reversal of the normal LR arrangement).

2. **Right atrial isomerism** (or asplenia syndrome): In this type, there is a lack of normal LR organization, and both sides of the body have structures that are typically found on the right side (right atrial isomerism). Common features include:
* Complex congenital heart defects, such as single ventricle, double outlet right ventricle, pulmonary stenosis or atresia, and total anomalous pulmonary venous return.
* Absent or multiple spleens (polysplenia) with varying degrees of functional asplenia.
* Bilateral trilobed lungs with a right-sided location of the liver (situs ambiguus).
* Bronchial malformations, including bilateral hyperarterial bronchi.
* Gastrointestinal tract abnormalities, such as intestinal malrotation and biliary atresia.
* Increased incidence of congenital diaphragmatic hernia.

Both situs ambiguus and heterotaxy syndrome are associated with increased morbidity and mortality due to the complex congenital heart defects, gastrointestinal tract abnormalities, and immunological dysfunction in cases of asplenia or hyposplenia. Early diagnosis and management by a multidisciplinary team are crucial for improving outcomes in these patients.

Ventricular function, in the context of cardiac medicine, refers to the ability of the heart's ventricles (the lower chambers) to fill with blood during the diastole phase and eject blood during the systole phase. The ventricles are primarily responsible for pumping oxygenated blood out to the body (left ventricle) and deoxygenated blood to the lungs (right ventricle).

There are several ways to assess ventricular function, including:

1. Ejection Fraction (EF): This is the most commonly used measure of ventricular function. It represents the percentage of blood that is ejected from the ventricle during each heartbeat. A normal left ventricular ejection fraction is typically between 55% and 70%.
2. Fractional Shortening (FS): This is another measure of ventricular function, which calculates the change in size of the ventricle during contraction as a percentage of the original size. A normal FS for the left ventricle is typically between 25% and 45%.
3. Stroke Volume (SV): This refers to the amount of blood that is pumped out of the ventricle with each heartbeat. SV is calculated by multiplying the ejection fraction by the end-diastolic volume (the amount of blood in the ventricle at the end of diastole).
4. Cardiac Output (CO): This is the total amount of blood that the heart pumps in one minute. It is calculated by multiplying the stroke volume by the heart rate.

Impaired ventricular function can lead to various cardiovascular conditions, such as heart failure, cardiomyopathy, and valvular heart disease. Assessing ventricular function is crucial for diagnosing these conditions, monitoring treatment response, and guiding clinical decision-making.

Heart disease is a broad term for a class of diseases that involve the heart or blood vessels. It's often used to refer to conditions that include:

1. Coronary artery disease (CAD): This is the most common type of heart disease. It occurs when the arteries that supply blood to the heart become hardened and narrowed due to the buildup of cholesterol and other substances, which can lead to chest pain (angina), shortness of breath, or a heart attack.

2. Heart failure: This condition occurs when the heart is unable to pump blood efficiently to meet the body's needs. It can be caused by various conditions, including coronary artery disease, high blood pressure, and cardiomyopathy.

3. Arrhythmias: These are abnormal heart rhythms, which can be too fast, too slow, or irregular. They can lead to symptoms such as palpitations, dizziness, and fainting.

4. Valvular heart disease: This involves damage to one or more of the heart's four valves, which control blood flow through the heart. Damage can be caused by various conditions, including infection, rheumatic fever, and aging.

5. Cardiomyopathy: This is a disease of the heart muscle that makes it harder for the heart to pump blood efficiently. It can be caused by various factors, including genetics, viral infections, and drug abuse.

6. Pericardial disease: This involves inflammation or other problems with the sac surrounding the heart (pericardium). It can cause chest pain and other symptoms.

7. Congenital heart defects: These are heart conditions that are present at birth, such as a hole in the heart or abnormal blood vessels. They can range from mild to severe and may require medical intervention.

8. Heart infections: The heart can become infected by bacteria, viruses, or parasites, leading to various symptoms and complications.

It's important to note that many factors can contribute to the development of heart disease, including genetics, lifestyle choices, and certain medical conditions. Regular check-ups and a healthy lifestyle can help reduce the risk of developing heart disease.

SP4 transcription factor is a member of the Sp1 (Specificity Protein 1) family of transcription factors that bind to GC-rich DNA sequences through their zinc finger domains. SP4, specifically, is a protein encoded by the SP4 gene in humans and is involved in the regulation of gene expression during various biological processes such as cell growth, differentiation, and survival.

SP4 can function both as an activator and repressor of transcription depending on the context, interacting with other transcription factors and co-regulators to modulate chromatin structure and accessibility at target gene promoters. Dysregulation of SP4 has been implicated in several human diseases, including cancer, neurological disorders, and cardiovascular disease.

Therefore, the SP4 transcription factor plays a crucial role in regulating gene expression programs that are critical for normal development and homeostasis, as well as in the pathogenesis of various diseases.

Wolff-Parkinson-White (WPW) Syndrome is a heart condition characterized by the presence of an accessory pathway or abnormal electrical connection between the atria (the upper chambers of the heart) and ventricles (the lower chambers of the heart). This accessory pathway allows electrical impulses to bypass the normal conduction system, leading to a shorter PR interval and a "delta wave" on the electrocardiogram (ECG), which is the hallmark of WPW Syndrome.

Individuals with WPW Syndrome may experience no symptoms or may have palpitations, rapid heartbeat (tachycardia), or episodes of atrial fibrillation. In some cases, WPW Syndrome can lead to more serious heart rhythm disturbances and may require treatment, such as medication, catheter ablation, or in rare cases, surgery.

It is important to note that not all individuals with WPW Syndrome will experience symptoms or complications, and many people with this condition can lead normal, active lives with appropriate monitoring and management.

Congenital heart defects (CHDs) are structural abnormalities in the heart that are present at birth. They can affect any part of the heart's structure, including the walls of the heart, the valves inside the heart, and the major blood vessels that lead to and from the heart.

Congenital heart defects can range from mild to severe and can cause various symptoms depending on the type and severity of the defect. Some common symptoms of CHDs include cyanosis (a bluish tint to the skin, lips, and fingernails), shortness of breath, fatigue, poor feeding, and slow growth in infants and children.

There are many different types of congenital heart defects, including:

1. Septal defects: These are holes in the walls that separate the four chambers of the heart. The two most common septal defects are atrial septal defect (ASD) and ventricular septal defect (VSD).
2. Valve abnormalities: These include narrowed or leaky valves, which can affect blood flow through the heart.
3. Obstruction defects: These occur when blood flow is blocked or restricted due to narrowing or absence of a part of the heart's structure. Examples include pulmonary stenosis and coarctation of the aorta.
4. Cyanotic heart defects: These cause a lack of oxygen in the blood, leading to cyanosis. Examples include tetralogy of Fallot and transposition of the great arteries.

The causes of congenital heart defects are not fully understood, but genetic factors and environmental influences during pregnancy may play a role. Some CHDs can be detected before birth through prenatal testing, while others may not be diagnosed until after birth or later in childhood. Treatment for CHDs may include medication, surgery, or other interventions to improve blood flow and oxygenation of the body's tissues.

Cardiac myocytes are the muscle cells that make up the heart muscle, also known as the myocardium. These specialized cells are responsible for contracting and relaxing in a coordinated manner to pump blood throughout the body. They differ from skeletal muscle cells in several ways, including their ability to generate their own electrical impulses, which allows the heart to function as an independent rhythmical pump. Cardiac myocytes contain sarcomeres, the contractile units of the muscle, and are connected to each other by intercalated discs that help coordinate contraction and ensure the synchronous beating of the heart.

Connexin 43 is a protein that forms gap junctions, which are specialized channels that allow for the direct communication and transport of small molecules between adjacent cells. Connexin 43 is widely expressed in many tissues, including the heart, brain, and various types of epithelial and connective tissues. In the heart, connexin 43 plays a crucial role in electrical conduction and coordination of contraction between cardiac muscle cells. Mutations in the gene that encodes connexin 43 have been associated with several human diseases, including certain types of cardiac arrhythmias and skin disorders.

Heart failure is a pathophysiological state in which the heart is unable to pump sufficient blood to meet the metabolic demands of the body or do so only at the expense of elevated filling pressures. It can be caused by various cardiac disorders, including coronary artery disease, hypertension, valvular heart disease, cardiomyopathy, and arrhythmias. Symptoms may include shortness of breath, fatigue, and fluid retention. Heart failure is often classified based on the ejection fraction (EF), which is the percentage of blood that is pumped out of the left ventricle during each contraction. A reduced EF (less than 40%) is indicative of heart failure with reduced ejection fraction (HFrEF), while a preserved EF (greater than or equal to 50%) is indicative of heart failure with preserved ejection fraction (HFpEF). There is also a category of heart failure with mid-range ejection fraction (HFmrEF) for those with an EF between 40-49%.

An action potential is a brief electrical signal that travels along the membrane of a nerve cell (neuron) or muscle cell. It is initiated by a rapid, localized change in the permeability of the cell membrane to specific ions, such as sodium and potassium, resulting in a rapid influx of sodium ions and a subsequent efflux of potassium ions. This ion movement causes a brief reversal of the electrical potential across the membrane, which is known as depolarization. The action potential then propagates along the cell membrane as a wave, allowing the electrical signal to be transmitted over long distances within the body. Action potentials play a crucial role in the communication and functioning of the nervous system and muscle tissue.

Acetylthiocholine is a synthetic chemical compound that is widely used in scientific research, particularly in the field of neuroscience. It is the acetylated form of thiocholine, which is a choline ester. Acetylthiocholine is often used as a substrate for enzymes called cholinesterases, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).

When Acetylthiocholine is hydrolyzed by AChE, it produces choline and thioacetic acid. This reaction is important because it terminates the signal transduction of the neurotransmitter acetylcholine at the synapse between neurons. Inhibition of AChE can lead to an accumulation of Acetylthiocholine and acetylcholine, which can have various effects on the nervous system, depending on the dose and duration of inhibition.

Acetylthiocholine is also used as a reagent in the Ellman's assay, a colorimetric method for measuring AChE activity. In this assay, Acetylthiocholine is hydrolyzed by AChE, releasing thiocholine, which then reacts with dithiobisnitrobenzoic acid (DTNB) to produce a yellow color. The intensity of the color is proportional to the amount of thiocholine produced and can be used to quantify AChE activity.

Cardiac electrophysiology is a branch of medicine that deals with the study and understanding of the electrical activities of the heart. It involves the diagnosis and treatment of various heart rhythm disorders (arrhythmias) such as bradycardia (slow heart rate), tachycardia (fast heart rate), atrial fibrillation, atrial flutter, ventricular fibrillation, and other rhythm abnormalities.

Cardiac electrophysiologists use various diagnostic tests, including electrocardiograms (ECGs), Holter monitors, event monitors, and invasive procedures such as electrophysiology studies (EPS) and catheter ablation to evaluate and treat heart rhythm disorders. The goal of treatment is to restore a normal heart rhythm and prevent complications associated with arrhythmias, such as stroke or heart failure.

Artificial cardiac pacing is a medical procedure that involves the use of an artificial device to regulate and stimulate the contraction of the heart muscle. This is often necessary when the heart's natural pacemaker, the sinoatrial node, is not functioning properly and the heart is beating too slowly or irregularly.

The artificial pacemaker consists of a small generator that produces electrical impulses and leads that are positioned in the heart to transmit the impulses. The generator is typically implanted just under the skin in the chest, while the leads are inserted into the heart through a vein.

There are different types of artificial cardiac pacing systems, including single-chamber pacemakers, which stimulate either the right atrium or right ventricle, and dual-chamber pacemakers, which stimulate both chambers of the heart. Some pacemakers also have additional features that allow them to respond to changes in the body's needs, such as during exercise or sleep.

Artificial cardiac pacing is a safe and effective treatment for many people with abnormal heart rhythms, and it can significantly improve their quality of life and longevity.

Electrophysiology is a branch of medicine that deals with the electrical activities of the body, particularly the heart. In a medical context, electrophysiology studies (EPS) are performed to assess abnormal heart rhythms (arrhythmias) and to evaluate the effectiveness of certain treatments, such as medication or pacemakers.

During an EPS, electrode catheters are inserted into the heart through blood vessels in the groin or neck. These catheters can record the electrical activity of the heart and stimulate it to help identify the source of the arrhythmia. The information gathered during the study can help doctors determine the best course of treatment for each patient.

In addition to cardiac electrophysiology, there are also other subspecialties within electrophysiology, such as neuromuscular electrophysiology, which deals with the electrical activity of the nervous system and muscles.

Developmental gene expression regulation refers to the processes that control the activation or repression of specific genes during embryonic and fetal development. These regulatory mechanisms ensure that genes are expressed at the right time, in the right cells, and at appropriate levels to guide proper growth, differentiation, and morphogenesis of an organism.

Developmental gene expression regulation is a complex and dynamic process involving various molecular players, such as transcription factors, chromatin modifiers, non-coding RNAs, and signaling molecules. These regulators can interact with cis-regulatory elements, like enhancers and promoters, to fine-tune the spatiotemporal patterns of gene expression during development.

Dysregulation of developmental gene expression can lead to various congenital disorders and developmental abnormalities. Therefore, understanding the principles and mechanisms governing developmental gene expression regulation is crucial for uncovering the etiology of developmental diseases and devising potential therapeutic strategies.

The refractory period, electrophysiological, refers to the time interval during which a cardiac or neural cell is unable to respond to a new stimulus immediately after an action potential has been generated. This period is divided into two phases: the absolute refractory period and the relative refractory period.

During the absolute refractory period, the cell cannot be re-stimulated, regardless of the strength of the stimulus, due to the rapid inactivation of voltage-gated sodium channels that are responsible for the rapid depolarization during an action potential. This phase is crucial for maintaining the unidirectional conduction of electrical impulses and preventing the occurrence of re-entry circuits, which can lead to life-threatening arrhythmias in the heart or hyperexcitability in neural tissue.

The relative refractory period follows the absolute refractory period and is characterized by a reduced excitability of the cell. During this phase, a stronger than normal stimulus is required to elicit an action potential due to the slower recovery of voltage-gated sodium channels and the partial activation of potassium channels, which promote repolarization. The duration of both the absolute and relative refractory periods varies depending on the cell type, its physiological state, and other factors such as temperature and pH.

In summary, the electrophysiological refractory period is a fundamental property of excitable cells that ensures proper electrical signaling and prevents uncontrolled excitation or re-entry circuits.

GATA6 (GATA binding protein 6) is a transcription factor that belongs to the GATA family, which are characterized by their ability to bind to the DNA sequence (A/T)GATA(A/G). GATA6 plays crucial roles in the development and function of various tissues, particularly in the digestive system.

As a transcription factor, GATA6 regulates gene expression by binding to specific DNA sequences in the promoter or enhancer regions of target genes. This binding either activates or represses the transcription of these genes, thereby controlling cellular processes such as proliferation, differentiation, and survival.

In the context of the digestive system, GATA6 is essential for the development of the pancreas and small intestine. It promotes the differentiation of pancreatic progenitor cells into exocrine cells (such as acinar and ductal cells) and inhibits their differentiation into endocrine cells (such as β-cells). In the small intestine, GATA6 is involved in maintaining the identity and function of Paneth cells, which are specialized epithelial cells that play a role in innate immunity.

Mutations in the GATA6 gene have been associated with various human diseases, including pancreatic agenesis or hypoplasia, small intestinal atresia, and congenital diaphragmatic hernia. Additionally, altered GATA6 expression has been implicated in several types of cancer, such as pancreatic ductal adenocarcinoma and colorectal cancer.

Cardiovascular models are simplified representations or simulations of the human cardiovascular system used in medical research, education, and training. These models can be physical, computational, or mathematical and are designed to replicate various aspects of the heart, blood vessels, and blood flow. They can help researchers study the structure and function of the cardiovascular system, test new treatments and interventions, and train healthcare professionals in diagnostic and therapeutic techniques.

Physical cardiovascular models may include artificial hearts, blood vessels, or circulation systems made from materials such as plastic, rubber, or silicone. These models can be used to study the mechanics of heart valves, the effects of different surgical procedures, or the impact of various medical devices on blood flow.

Computational and mathematical cardiovascular models use algorithms and equations to simulate the behavior of the cardiovascular system. These models may range from simple representations of a single heart chamber to complex simulations of the entire circulatory system. They can be used to study the electrical activity of the heart, the biomechanics of blood flow, or the distribution of drugs in the body.

Overall, cardiovascular models play an essential role in advancing our understanding of the human body and improving patient care.

Dextrocardia is a medical condition in which the heart is positioned on the right side of the chest instead of the left side. This is a congenital condition, meaning it is present at birth. In people with dextrocardia, the heart's structure and function are usually normal, but the orientation of the heart within the chest is reversed.

There are two main types of dextrocardia:

1. Dextrocardia without visceral situs inversus: In this type, the heart is on the right side of the chest, but the other organs in the chest and abdomen are in their normal positions. This is a rare condition and can be associated with other congenital heart defects.
2. Dextrocardia with visceral situs inversus: In this type, the heart is on the right side of the chest, and the other organs in the chest and abdomen are mirrored or reversed from their normal positions. This is a less common form of dextrocardia and is often referred to as "situs inversus totalis."

It's important to note that while dextrocardia itself is not a life-threatening condition, people with this condition may have other heart defects or medical issues that require treatment. If you or someone you know has been diagnosed with dextrocardia, it's essential to consult with a healthcare professional for proper evaluation and management.

Thiol esters are chemical compounds that contain a sulfur atom (from a mercapto group, -SH) linked to a carbonyl group (a carbon double-bonded to an oxygen atom, -CO-) through an ester bond. Thiolester hydrolases are enzymes that catalyze the hydrolysis of thiol esters, breaking down these compounds into a carboxylic acid and a thiol (a compound containing a mercapto group).

In biological systems, thiolester bonds play important roles in various metabolic pathways. For example, acetyl-CoA, a crucial molecule in energy metabolism, is a thiol ester that forms between coenzyme A and an acetyl group. Thiolester hydrolases help regulate the formation and breakdown of these thiol esters, allowing cells to control various biochemical reactions.

Examples of thiolester hydrolases include:

1. CoA thioesterases (CoATEs): These enzymes hydrolyze thiol esters between coenzyme A and fatty acids, releasing free coenzyme A and a fatty acid. This process is essential for fatty acid metabolism.
2. Acetyl-CoA hydrolase: This enzyme specifically breaks down the thiol ester bond in acetyl-CoA, releasing acetic acid and coenzyme A.
3. Thioesterases involved in non-ribosomal peptide synthesis (NRPS): These enzymes hydrolyze thiol esters during the biosynthesis of complex peptides, allowing for the formation of unique amino acid sequences and structures.

Understanding the function and regulation of thiolester hydrolases can provide valuable insights into various metabolic processes and potential therapeutic targets in disease treatment.

NAV1.5, also known as SCN5A, is a specific type of voltage-gated sodium channel found in the heart muscle cells (cardiomyocytes). These channels play a crucial role in the generation and transmission of electrical signals that coordinate the contraction of the heart.

More specifically, NAV1.5 channels are responsible for the rapid influx of sodium ions into cardiomyocytes during the initial phase of the action potential, which is the electrical excitation of the cell. This rapid influx of sodium ions helps to initiate and propagate the action potential throughout the heart muscle, allowing for coordinated contraction and proper heart function.

Mutations in the SCN5A gene, which encodes the NAV1.5 channel, have been associated with various cardiac arrhythmias, including long QT syndrome, Brugada syndrome, and familial atrial fibrillation, among others. These genetic disorders can lead to abnormal heart rhythms, syncope, and in some cases, sudden cardiac death.

Bundle-branch block (BBB) is a type of conduction delay or block in the heart's electrical system that affects the way electrical impulses travel through the ventricles (the lower chambers of the heart). In BBB, one of the two main bundle branches that conduct electrical impulses to the ventricles is partially or completely blocked, causing a delay in the contraction of one of the ventricles.

There are two types of bundle-branch block: right bundle-branch block (RBBB) and left bundle-branch block (LBBB). In RBBB, the right bundle branch is affected, while in LBBB, the left bundle branch is affected. The symptoms and severity of BBB can vary depending on the underlying cause and the presence of other heart conditions.

In some cases, BBB may not cause any noticeable symptoms and may only be detected during a routine electrocardiogram (ECG). However, if BBB occurs along with other heart conditions such as coronary artery disease, heart failure, or cardiomyopathy, it can increase the risk of serious complications such as arrhythmias, syncope, and even sudden cardiac death.

Treatment for bundle-branch block depends on the underlying cause and the severity of the condition. In some cases, no treatment may be necessary, while in others, medications, pacemakers, or other treatments may be recommended to manage symptoms and prevent complications.

The lac operon is a genetic regulatory system found in the bacteria Escherichia coli that controls the expression of genes responsible for the metabolism of lactose as a source of energy. It consists of three structural genes (lacZ, lacY, and lacA) that code for enzymes involved in lactose metabolism, as well as two regulatory elements: the lac promoter and the lac operator.

The lac repressor protein, produced by the lacI gene, binds to the lac operator sequence when lactose is not present, preventing RNA polymerase from transcribing the structural genes. When lactose is available, it is converted into allolactose, which acts as an inducer and binds to the lac repressor protein, causing a conformational change that prevents it from binding to the operator sequence. This allows RNA polymerase to bind to the promoter and transcribe the structural genes, leading to the production of enzymes necessary for lactose metabolism.

In summary, the lac operon is a genetic regulatory system in E. coli that controls the expression of genes involved in lactose metabolism based on the availability of lactose as a substrate.

Cnidaria is a phylum of aquatic animals that includes jellyfish, sea anemones, hydra, and corals. They are characterized by the presence of specialized stinging cells called cnidocytes, which they use for defense and capturing prey. Cnidarians have a simple body organization with two basic forms: polyps, which are typically cylindrical and attached to a substrate; and medusae, which are free-swimming and bell-shaped. Some species can exist in both forms during their life cycle.

Cnidarians have no true organs or organ systems, but they do have a unique tissue arrangement with two main layers: an outer epidermis and an inner gastrodermis, separated by a jelly-like mesoglea. They have a digestive cavity called the coelenteron, where they absorb nutrients after capturing and digesting prey. Cnidarians reproduce both sexually and asexually, with some species exhibiting complex life cycles involving multiple forms and reproductive strategies.

The heart septum is the thick, muscular wall that divides the right and left sides of the heart. It consists of two main parts: the atrial septum, which separates the right and left atria (the upper chambers of the heart), and the ventricular septum, which separates the right and left ventricles (the lower chambers of the heart). A normal heart septum ensures that oxygen-rich blood from the lungs does not mix with oxygen-poor blood from the body. Any defect or abnormality in the heart septum is called a septal defect, which can lead to various congenital heart diseases.

CD57 is a protein found on the surface of some immune cells, specifically natural killer (NK) cells and certain T-cells. It is often used as a marker to identify these populations of cells. Antigens are substances that can stimulate an immune response, leading to the production of antibodies. In the context of CD57, antigens would refer to any substance that can bind to the CD57 protein on the surface of NK or T-cells.

It's worth noting that CD57 has been studied as a potential marker for certain diseases and conditions, such as HIV infection and some types of cancer. However, its use as a diagnostic or prognostic marker is still a subject of ongoing research and debate.

Heart transplantation is a surgical procedure where a diseased, damaged, or failing heart is removed and replaced with a healthy donor heart. This procedure is usually considered as a last resort for patients with end-stage heart failure or severe coronary artery disease who have not responded to other treatments. The donor heart typically comes from a brain-dead individual whose family has agreed to donate their loved one's organs for transplantation. Heart transplantation is a complex and highly specialized procedure that requires a multidisciplinary team of healthcare professionals, including cardiologists, cardiac surgeons, anesthesiologists, perfusionists, nurses, and other support staff. The success rates for heart transplantation have improved significantly over the past few decades, with many patients experiencing improved quality of life and increased survival rates. However, recipients of heart transplants require lifelong immunosuppressive therapy to prevent rejection of the donor heart, which can increase the risk of infections and other complications.

Myocardial contraction refers to the rhythmic and forceful shortening of heart muscle cells (myocytes) in the myocardium, which is the muscular wall of the heart. This process is initiated by electrical signals generated by the sinoatrial node, causing a wave of depolarization that spreads throughout the heart.

During myocardial contraction, calcium ions flow into the myocytes, triggering the interaction between actin and myosin filaments, which are the contractile proteins in the muscle cells. This interaction causes the myofilaments to slide past each other, resulting in the shortening of the sarcomeres (the functional units of muscle contraction) and ultimately leading to the contraction of the heart muscle.

Myocardial contraction is essential for pumping blood throughout the body and maintaining adequate circulation to vital organs. Any impairment in myocardial contractility can lead to various cardiac disorders, such as heart failure, cardiomyopathy, and arrhythmias.

Anti-arrhythmia agents are a class of medications used to treat abnormal heart rhythms or arrhythmias. These drugs work by modifying the electrical activity of the heart to restore and maintain a normal heart rhythm. There are several types of anti-arrhythmia agents, including:

1. Sodium channel blockers: These drugs slow down the conduction of electrical signals in the heart, which helps to reduce rapid or irregular heartbeats. Examples include flecainide, propafenone, and quinidine.
2. Beta-blockers: These medications work by blocking the effects of adrenaline on the heart, which helps to slow down the heart rate and reduce the force of heart contractions. Examples include metoprolol, atenolol, and esmolol.
3. Calcium channel blockers: These drugs block the entry of calcium into heart muscle cells, which helps to slow down the heart rate and reduce the force of heart contractions. Examples include verapamil and diltiazem.
4. Potassium channel blockers: These medications work by prolonging the duration of the heart's electrical cycle, which helps to prevent abnormal rhythms. Examples include amiodarone and sotalol.
5. Digoxin: This drug increases the force of heart contractions and slows down the heart rate, which can help to restore a normal rhythm in certain types of arrhythmias.

It's important to note that anti-arrhythmia agents can have significant side effects and should only be prescribed by a healthcare professional who has experience in managing arrhythmias. Close monitoring is necessary to ensure the medication is working effectively and not causing any adverse effects.

Lamin Type A, also known as LMNA, is a gene that provides instructions for making proteins called lamins. These proteins are part of the nuclear lamina, a network of fibers that lies just inside the nuclear envelope, which is the membrane that surrounds the cell's nucleus. The nuclear lamina helps maintain the shape and stability of the nucleus and plays a role in regulating gene expression and DNA replication.

Mutations in the LMNA gene can lead to various diseases collectively known as laminopathies, which affect different tissues and organs in the body. These conditions include Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy, dilated cardiomyopathy with conduction system disease, and a type of premature aging disorder called Hutchinson-Gilford progeria syndrome. The specific symptoms and severity of these disorders depend on the particular LMNA mutation and the tissues affected.

Cardiomyopathies are a group of diseases that affect the heart muscle, leading to mechanical and/or electrical dysfunction. The American Heart Association (AHA) defines cardiomyopathies as "a heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that usually (but not always) exhibit inappropriate ventricular hypertrophy or dilatation and frequently lead to heart failure."

There are several types of cardiomyopathies, including:

1. Dilated cardiomyopathy (DCM): This is the most common type of cardiomyopathy, characterized by an enlarged left ventricle and impaired systolic function, leading to heart failure.
2. Hypertrophic cardiomyopathy (HCM): In this type, there is abnormal thickening of the heart muscle, particularly in the septum between the two ventricles, which can obstruct blood flow and increase the risk of arrhythmias.
3. Restrictive cardiomyopathy (RCM): This is a rare form of cardiomyopathy characterized by stiffness of the heart muscle, impaired relaxation, and diastolic dysfunction, leading to reduced filling of the ventricles and heart failure.
4. Arrhythmogenic right ventricular cardiomyopathy (ARVC): In this type, there is replacement of the normal heart muscle with fatty or fibrous tissue, primarily affecting the right ventricle, which can lead to arrhythmias and sudden cardiac death.
5. Unclassified cardiomyopathies: These are conditions that do not fit into any of the above categories but still significantly affect the heart muscle and function.

Cardiomyopathies can be caused by genetic factors, acquired conditions (e.g., infections, toxins, or autoimmune disorders), or a combination of both. The diagnosis typically involves a comprehensive evaluation, including medical history, physical examination, electrocardiogram (ECG), echocardiography, cardiac magnetic resonance imaging (MRI), and sometimes genetic testing. Treatment depends on the type and severity of the condition but may include medications, lifestyle modifications, implantable devices, or even heart transplantation in severe cases.

Atrioventricular (AV) nodal reentrant tachycardia (AVNRT) is a type of supraventricular tachycardia (SVT), which is a rapid heart rhythm originating at or above the atrioventricular node. In AVNRT, an abnormal electrical circuit in or near the AV node creates a reentry pathway that allows for rapid heart rates, typically greater than 150-250 beats per minute.

In normal conduction, the electrical impulse travels from the atria to the ventricles through the AV node and then continues down the bundle branches to the Purkinje fibers, resulting in a coordinated contraction of the heart. In AVNRT, an extra electrical pathway exists that allows for the reentry of the electrical impulse back into the atria, creating a rapid and abnormal circuit.

AVNRT is classified based on the direction of the reentry circuit:

1. Typical or common AVNRT: The most common form, accounting for 90% of cases. In this type, the reentry circuit involves an "anterior" and a "posterior" loop in or near the AV node. The anterior loop has slower conduction velocity than the posterior loop, creating a "short" reentry circuit that is responsible for the rapid heart rate.
2. Atypical AVNRT: Less common, accounting for 10% of cases. In this type, the reentry circuit involves an "outer" and an "inner" loop around the AV node. The outer loop has slower conduction velocity than the inner loop, creating a "long" reentry circuit that is responsible for the rapid heart rate.

AVNRT can present with symptoms such as palpitations, dizziness, lightheadedness, shortness of breath, chest discomfort, or syncope (fainting). Treatment options include observation, vagal maneuvers, medications, and catheter ablation. Catheter ablation is a curative treatment that involves the destruction of the abnormal electrical pathway using radiofrequency energy or cryotherapy.

Situs Inversus is a congenital condition in which the major visceral organs are situated in mirror-image positions to their normal locations. Instead of being on the left side, the heart and its large blood vessels are on the right side, while the liver is on the left side and the lungs are reversed. The stomach, spleen, and pancreas may also be affected. It's important to note that this condition is generally asymptomatic and often goes unnoticed unless there are complications or associated abnormalities.

There are two types of Situs Inversus: total (complete reversal of all organs) and partial (reversal of only some organs). Total Situs Inversus is also sometimes referred to as "mirror-image dextrocardia" because the heart, which is usually on the left side, is located on the right side in a mirrored position.

While Situs Inversus itself does not typically cause health problems, people with this condition may have an increased risk for certain medical conditions, such as congenital heart defects or primary ciliary dyskinesia (PCD), which can lead to chronic respiratory infections and infertility.

Electrophysiological processes refer to the electrical activities that occur within biological cells or organ systems, particularly in nerve and muscle tissues. These processes involve the generation, transmission, and reception of electrical signals that are essential for various physiological functions, such as nerve impulse transmission, muscle contraction, and hormonal regulation.

At the cellular level, electrophysiological processes are mediated by the flow of ions across the cell membrane through specialized protein channels. This ion movement generates a voltage difference across the membrane, leading to the development of action potentials, which are rapid changes in electrical potential that travel along the cell membrane and transmit signals between cells.

In clinical medicine, electrophysiological studies (EPS) are often used to diagnose and manage various cardiac arrhythmias and neurological disorders. These studies involve the recording of electrical activity from the heart or brain using specialized equipment, such as an electrocardiogram (ECG) or an electroencephalogram (EEG). By analyzing these recordings, physicians can identify abnormalities in the electrical activity of these organs and develop appropriate treatment plans.

I'm sorry for any confusion, but "Ubiquitin Thiolesterase" is not a widely recognized medical term or a well-defined concept in the field of medicine. Ubiquitination, however, is a post-translational modification that plays a crucial role in various cellular processes, including protein degradation and regulation of signaling pathways.

Ubiquitin Thiolesterase could potentially refer to an enzyme that catalyzes the hydrolysis of a thioester bond between ubiquitin and a target protein. This process would be part of the ubiquitination cascade, where ubiquitin is transferred from one protein to another through various intermediates, including thioester bonds. However, I would recommend consulting primary literature or speaking with an expert in the field for more precise information on this topic.

Tachycardia is a medical term that refers to an abnormally rapid heart rate, often defined as a heart rate greater than 100 beats per minute in adults. It can occur in either the atria (upper chambers) or ventricles (lower chambers) of the heart. Different types of tachycardia include supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, and ventricular tachycardia.

Tachycardia can cause various symptoms such as palpitations, shortness of breath, dizziness, lightheadedness, chest discomfort, or syncope (fainting). In some cases, tachycardia may not cause any symptoms and may only be detected during a routine physical examination or medical test.

The underlying causes of tachycardia can vary widely, including heart disease, electrolyte imbalances, medications, illicit drug use, alcohol abuse, smoking, stress, anxiety, and other medical conditions. In some cases, the cause may be unknown. Treatment for tachycardia depends on the underlying cause, type, severity, and duration of the arrhythmia.

Vectorcardiography (VCG) is a type of graphical recording that depicts the vector magnitude and direction of the electrical activity of the heart over time. It provides a three-dimensional view of the electrical activation pattern of the heart, as opposed to the one-dimensional view offered by a standard electrocardiogram (ECG).

In VCG, the electrical potentials are recorded using a special array of electrodes placed on the body surface. These potentials are then mathematically converted into vectors and plotted on a vector loop or a series of loops that represent different planes of the heart's electrical activity. The resulting tracing provides information about the magnitude, direction, and timing of the electrical activation of the heart, which can be helpful in diagnosing various cardiac arrhythmias, ischemic heart disease, and other cardiac conditions.

Overall, vectorcardiography offers a more detailed and comprehensive view of the heart's electrical activity than traditional ECG, making it a valuable tool in clinical cardiology.

I believe there might be a misunderstanding in your question. "Dogs" is not a medical term or condition. It is the common name for a domesticated carnivore of the family Canidae, specifically the genus Canis, which includes wolves, foxes, and other extant and extinct species of mammals. Dogs are often kept as pets and companions, and they have been bred in a wide variety of forms and sizes for different purposes, such as hunting, herding, guarding, assisting police and military forces, and providing companionship and emotional support.

If you meant to ask about a specific medical condition or term related to dogs, please provide more context so I can give you an accurate answer.

Sudden cardiac death (SCD) is a sudden, unexpected natural death caused by the cessation of cardiac activity. It is often caused by cardiac arrhythmias, particularly ventricular fibrillation, and is often associated with underlying heart disease, although it can occur in people with no known heart condition. SCD is typically defined as a natural death due to cardiac causes that occurs within one hour of the onset of symptoms, or if the individual was last seen alive in a normal state of health, it can be defined as occurring within 24 hours.

It's important to note that sudden cardiac arrest (SCA) is different from SCD, although they are related. SCA refers to the sudden cessation of cardiac activity, which if not treated immediately can lead to SCD.

Aporphine is a type of chemical compound called alkaloids, which are found in certain plants. Aporphines have a specific chemical structure and can have various pharmacological effects. They have been studied for their potential medicinal properties, including anti-inflammatory, antispasmodic, and antiasthmatic activities. Some aporphine alkaloids have also been found to have psychoactive effects and are used in traditional medicine in some cultures. However, more research is needed to fully understand the therapeutic potential and safety of aporphines.

Bone conduction is a type of hearing mechanism that involves the transmission of sound vibrations directly to the inner ear through the bones of the skull, bypassing the outer and middle ears. This occurs when sound waves cause the bones in the skull to vibrate, stimulating the cochlea (the spiral cavity of the inner ear) and its hair cells, which convert the mechanical energy of the vibrations into electrical signals that are sent to the brain and interpreted as sound.

Bone conduction is a natural part of the hearing process in humans, but it can also be used artificially through the use of bone-conduction devices, such as hearing aids or headphones, which transmit sound vibrations directly to the skull. This type of transmission can provide improved hearing for individuals with conductive hearing loss, mixed hearing loss, or single-sided deafness, as it bypasses damaged or obstructed outer and middle ears.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Telemetry is the automated measurement and wireless transmission of data from remote or inaccessible sources to receiving stations for monitoring and analysis. In a medical context, telemetry is often used to monitor patients' vital signs such as heart rate, blood pressure, oxygen levels, and other important physiological parameters continuously and remotely. This technology allows healthcare providers to track patients' conditions over time, detect any abnormalities or trends, and make informed decisions about their care, even when they are not physically present with the patient. Telemetry is commonly used in hospitals, clinics, and research settings to monitor patients during procedures, after surgery, or during extended stays in intensive care units.

Dilated cardiomyopathy (DCM) is a type of cardiomyopathy characterized by the enlargement and weakened contraction of the heart's main pumping chamber (the left ventricle). This enlargement and weakness can lead to symptoms such as shortness of breath, fatigue, and fluid retention. DCM can be caused by various factors including genetics, viral infections, alcohol and drug abuse, and other medical conditions like high blood pressure and diabetes. It is important to note that this condition can lead to heart failure if left untreated.

Sodium channels are specialized protein structures that are embedded in the membranes of excitable cells, such as nerve and muscle cells. They play a crucial role in the generation and transmission of electrical signals in these cells. Sodium channels are responsible for the rapid influx of sodium ions into the cell during the initial phase of an action potential, which is the electrical signal that travels along the membrane of a neuron or muscle fiber. This sudden influx of sodium ions causes the membrane potential to rapidly reverse, leading to the depolarization of the cell. After the action potential, the sodium channels close and become inactivated, preventing further entry of sodium ions and helping to restore the resting membrane potential.

Sodium channels are composed of a large alpha subunit and one or two smaller beta subunits. The alpha subunit forms the ion-conducting pore, while the beta subunits play a role in modulating the function and stability of the channel. Mutations in sodium channel genes have been associated with various inherited diseases, including certain forms of epilepsy, cardiac arrhythmias, and muscle disorders.

The median nerve is one of the major nerves in the human body, providing sensation and motor function to parts of the arm and hand. It originates from the brachial plexus, a network of nerves that arise from the spinal cord in the neck. The median nerve travels down the arm, passing through the cubital tunnel at the elbow, and continues into the forearm and hand.

In the hand, the median nerve supplies sensation to the palm side of the thumb, index finger, middle finger, and half of the ring finger. It also provides motor function to some of the muscles that control finger movements, allowing for flexion of the fingers and opposition of the thumb.

Damage to the median nerve can result in a condition called carpal tunnel syndrome, which is characterized by numbness, tingling, and weakness in the hand and fingers.

The fetal heart is the cardiovascular organ that develops in the growing fetus during pregnancy. It starts to form around 22 days after conception and continues to develop throughout the first trimester. By the end of the eighth week of gestation, the fetal heart has developed enough to pump blood throughout the body.

The fetal heart is similar in structure to the adult heart but has some differences. It is smaller and more compact, with a four-chambered structure that includes two atria and two ventricles. The fetal heart also has unique features such as the foramen ovale, which is a hole between the right and left atria that allows blood to bypass the lungs, and the ductus arteriosus, a blood vessel that connects the pulmonary artery to the aorta and diverts blood away from the lungs.

The fetal heart is responsible for pumping oxygenated blood from the placenta to the rest of the body and returning deoxygenated blood back to the placenta for re-oxygenation. The rate of the fetal heartbeat is faster than that of an adult, typically ranging from 120 to 160 beats per minute. Fetal heart rate monitoring is a common method used during pregnancy and childbirth to assess the health and well-being of the developing fetus.

Transgenic mice are genetically modified rodents that have incorporated foreign DNA (exogenous DNA) into their own genome. This is typically done through the use of recombinant DNA technology, where a specific gene or genetic sequence of interest is isolated and then introduced into the mouse embryo. The resulting transgenic mice can then express the protein encoded by the foreign gene, allowing researchers to study its function in a living organism.

The process of creating transgenic mice usually involves microinjecting the exogenous DNA into the pronucleus of a fertilized egg, which is then implanted into a surrogate mother. The offspring that result from this procedure are screened for the presence of the foreign DNA, and those that carry the desired genetic modification are used to establish a transgenic mouse line.

Transgenic mice have been widely used in biomedical research to model human diseases, study gene function, and test new therapies. They provide a valuable tool for understanding complex biological processes and developing new treatments for a variety of medical conditions.

A chick embryo refers to the developing organism that arises from a fertilized chicken egg. It is often used as a model system in biological research, particularly during the stages of development when many of its organs and systems are forming and can be easily observed and manipulated. The study of chick embryos has contributed significantly to our understanding of various aspects of developmental biology, including gastrulation, neurulation, organogenesis, and pattern formation. Researchers may use various techniques to observe and manipulate the chick embryo, such as surgical alterations, cell labeling, and exposure to drugs or other agents.

The pericardium is the double-walled sac that surrounds the heart. It has an outer fibrous layer and an inner serous layer, which further divides into two parts: the parietal layer lining the fibrous pericardium and the visceral layer (epicardium) closely adhering to the heart surface.

The space between these two layers is filled with a small amount of lubricating serous fluid, allowing for smooth movement of the heart within the pericardial cavity. The pericardium provides protection, support, and helps maintain the heart's normal position within the chest while reducing friction during heart contractions.

Bradycardia is a medical term that refers to an abnormally slow heart rate, typically defined as a resting heart rate of less than 60 beats per minute in adults. While some people, particularly well-trained athletes, may have a naturally low resting heart rate, bradycardia can also be a sign of an underlying health problem.

There are several potential causes of bradycardia, including:

* Damage to the heart's electrical conduction system, such as from heart disease or aging
* Certain medications, including beta blockers, calcium channel blockers, and digoxin
* Hypothyroidism (underactive thyroid gland)
* Sleep apnea
* Infection of the heart (endocarditis or myocarditis)
* Infiltrative diseases such as amyloidosis or sarcoidosis

Symptoms of bradycardia can vary depending on the severity and underlying cause. Some people with bradycardia may not experience any symptoms, while others may feel weak, fatigued, dizzy, or short of breath. In severe cases, bradycardia can lead to fainting, confusion, or even cardiac arrest.

Treatment for bradycardia depends on the underlying cause. If a medication is causing the slow heart rate, adjusting the dosage or switching to a different medication may help. In other cases, a pacemaker may be necessary to regulate the heart's rhythm. It is important to seek medical attention if you experience symptoms of bradycardia, as it can be a sign of a serious underlying condition.

An artificial pacemaker is a medical device that uses electrical impulses to regulate the beating of the heart. It is typically used when the heart's natural pacemaker, the sinoatrial node, is not functioning properly and the heart rate is too slow or irregular. The pacemaker consists of a small generator that contains a battery and electronic circuits, which are connected to one or more electrodes that are placed in the heart.

The generator sends electrical signals through the electrodes to stimulate the heart muscle and cause it to contract, thereby maintaining a regular heart rhythm. Artificial pacemakers can be programmed to deliver electrical impulses at a specific rate or in response to the body's needs. They are typically implanted in the chest during a surgical procedure and can last for many years before needing to be replaced.

Artificial pacemakers are an effective treatment for various types of bradycardia, which is a heart rhythm disorder characterized by a slow heart rate. Pacemakers can significantly improve symptoms associated with bradycardia, such as fatigue, dizziness, shortness of breath, and fainting spells.

Homeodomain proteins are a group of transcription factors that play crucial roles in the development and differentiation of cells in animals and plants. They are characterized by the presence of a highly conserved DNA-binding domain called the homeodomain, which is typically about 60 amino acids long. The homeodomain consists of three helices, with the third helix responsible for recognizing and binding to specific DNA sequences.

Homeodomain proteins are involved in regulating gene expression during embryonic development, tissue maintenance, and organismal growth. They can act as activators or repressors of transcription, depending on the context and the presence of cofactors. Mutations in homeodomain proteins have been associated with various human diseases, including cancer, congenital abnormalities, and neurological disorders.

Some examples of homeodomain proteins include PAX6, which is essential for eye development, HOX genes, which are involved in body patterning, and NANOG, which plays a role in maintaining pluripotency in stem cells.

I believe there may be some confusion in your question. "Rabbits" is a common name used to refer to the Lagomorpha species, particularly members of the family Leporidae. They are small mammals known for their long ears, strong legs, and quick reproduction.

However, if you're referring to "rabbits" in a medical context, there is a term called "rabbit syndrome," which is a rare movement disorder characterized by repetitive, involuntary movements of the fingers, resembling those of a rabbit chewing. It is also known as "finger-chewing chorea." This condition is usually associated with certain medications, particularly antipsychotics, and typically resolves when the medication is stopped or adjusted.

Desmin is a type of intermediate filament protein that is primarily found in the cardiac and skeletal muscle cells, as well as in some types of smooth muscle cells. It is an important component of the cytoskeleton, which provides structural support to the cell and helps maintain its shape. Desmin plays a crucial role in maintaining the integrity of the sarcomere, which is the basic contractile unit of the muscle fiber. Mutations in the desmin gene can lead to various forms of muscular dystrophy and other inherited muscle disorders.

Heart valves are specialized structures in the heart that ensure unidirectional flow of blood through its chambers during the cardiac cycle. There are four heart valves: the tricuspid valve and the mitral (bicuspid) valve, located between the atria and ventricles, and the pulmonic (pulmonary) valve and aortic valve, located between the ventricles and the major blood vessels leaving the heart.

The heart valves are composed of thin flaps of tissue called leaflets or cusps, which are supported by a fibrous ring. The aortic and pulmonic valves have three cusps each, while the tricuspid and mitral valves have three and two cusps, respectively.

The heart valves open and close in response to pressure differences across them, allowing blood to flow forward into the ventricles during diastole (filling phase) and preventing backflow of blood into the atria during systole (contraction phase). A properly functioning heart valve ensures efficient pumping of blood by the heart and maintains normal blood circulation throughout the body.

Electrophysiologic techniques, cardiac, refer to medical procedures used to study the electrical activities and conduction systems of the heart. These techniques involve the insertion of electrode catheters into the heart through blood vessels under fluoroscopic guidance to record and stimulate electrical signals. The information obtained from these studies can help diagnose and evaluate various cardiac arrhythmias, determine the optimal treatment strategy, and assess the effectiveness of therapies such as ablation or implantable devices.

The electrophysiologic study (EPS) is a type of cardiac electrophysiologic technique that involves the measurement of electrical signals from different regions of the heart to evaluate its conduction system's function. The procedure can help identify the location of abnormal electrical pathways responsible for arrhythmias and determine the optimal treatment strategy, such as catheter ablation or medication therapy.

Cardiac electrophysiologic techniques are also used in device implantation procedures, such as pacemaker or defibrillator implantation, to ensure proper placement and function of the devices. These techniques can help program and test the devices to optimize their settings for each patient's needs.

In summary, cardiac electrophysiologic techniques are medical procedures used to study and manipulate the electrical activities of the heart, helping diagnose and treat various arrhythmias and other cardiac conditions.

The Ulnar nerve is one of the major nerves in the forearm and hand, which provides motor function to the majority of the intrinsic muscles of the hand (except for those innervated by the median nerve) and sensory innervation to the little finger and half of the ring finger. It originates from the brachial plexus, passes through the cubital tunnel at the elbow, and continues down the forearm, where it runs close to the ulna bone. The ulnar nerve then passes through the Guyon's canal in the wrist before branching out to innervate the hand muscles and provide sensation to the skin on the little finger and half of the ring finger.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are a type of ion channel found in the membranes of excitable cells, such as neurons and cardiac myocytes. These channels are unique because they open in response to membrane hyperpolarization, meaning that they allow the flow of ions into the cell when the voltage becomes more negative.

HCN channels are permeable to both sodium (Na+) and potassium (K+) ions, but they have a stronger preference for Na+ ions. When open, HCN channels conduct a current known as the "funny" or "Ih" current, which plays important roles in regulating the electrical excitability of cells.

HCN channels are also modulated by cyclic nucleotides, such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Binding of these molecules to the intracellular domain of the channel can increase its open probability, leading to an enhancement of the funny current.

Dysfunction of HCN channels has been implicated in a variety of neurological and cardiac disorders, including epilepsy, sleep disorders, and heart rhythm abnormalities.

'Cell lineage' is a term used in biology and medicine to describe the developmental history or relationship of a cell or group of cells to other cells, tracing back to the original progenitor or stem cell. It refers to the series of cell divisions and differentiation events that give rise to specific types of cells in an organism over time.

In simpler terms, cell lineage is like a family tree for cells, showing how they are related to each other through a chain of cell division and specialization events. This concept is important in understanding the development, growth, and maintenance of tissues and organs in living beings.

"Biological clocks" refer to the internal time-keeping systems in living organisms that regulate the timing of various physiological processes and behaviors according to a daily (circadian) rhythm. These rhythms are driven by genetic mechanisms and can be influenced by environmental factors such as light and temperature.

In humans, biological clocks help regulate functions such as sleep-wake cycles, hormone release, body temperature, and metabolism. Disruptions to these internal timekeeping systems have been linked to various health problems, including sleep disorders, mood disorders, and cognitive impairment.

Peripheral nerves are nerve fibers that transmit signals between the central nervous system (CNS, consisting of the brain and spinal cord) and the rest of the body. These nerves convey motor, sensory, and autonomic information, enabling us to move, feel, and respond to changes in our environment. They form a complex network that extends from the CNS to muscles, glands, skin, and internal organs, allowing for coordinated responses and functions throughout the body. Damage or injury to peripheral nerves can result in various neurological symptoms, such as numbness, weakness, or pain, depending on the type and severity of the damage.

Neurofilament proteins (NFs) are type IV intermediate filament proteins that are specific to neurons. They are the major structural components of the neuronal cytoskeleton and play crucial roles in maintaining the structural integrity, stability, and diameter of axons. Neurofilaments are composed of three subunits: light (NFL), medium (NFM), and heavy (NFH) neurofilament proteins, which differ in their molecular weights. These subunits assemble into heteropolymers to form the neurofilament core, while the C-terminal tails of NFH and NFM extend outward from the core, interacting with other cellular components and participating in various neuronal functions. Increased levels of neurofilament proteins, particularly NFL, in cerebrospinal fluid (CSF) and blood are considered biomarkers for axonal damage and neurodegeneration in several neurological disorders, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS).

Organogenesis is the process of formation and development of organs during embryonic growth. It involves the complex interactions of cells, tissues, and signaling molecules that lead to the creation of specialized structures in the body. This process begins in the early stages of embryonic development, around week 4-8, and continues until birth. During organogenesis, the three primary germ layers (ectoderm, mesoderm, and endoderm) differentiate into various cell types and organize themselves into specific structures that will eventually form the functional organs of the body. Abnormalities in organogenesis can result in congenital disorders or birth defects.

Transcription factors are proteins that play a crucial role in regulating gene expression by controlling the transcription of DNA to messenger RNA (mRNA). They function by binding to specific DNA sequences, known as response elements, located in the promoter region or enhancer regions of target genes. This binding can either activate or repress the initiation of transcription, depending on the properties and interactions of the particular transcription factor. Transcription factors often act as part of a complex network of regulatory proteins that determine the precise spatiotemporal patterns of gene expression during development, differentiation, and homeostasis in an organism.

Computer-assisted image processing is a medical term that refers to the use of computer systems and specialized software to improve, analyze, and interpret medical images obtained through various imaging techniques such as X-ray, CT (computed tomography), MRI (magnetic resonance imaging), ultrasound, and others.

The process typically involves several steps, including image acquisition, enhancement, segmentation, restoration, and analysis. Image processing algorithms can be used to enhance the quality of medical images by adjusting contrast, brightness, and sharpness, as well as removing noise and artifacts that may interfere with accurate diagnosis. Segmentation techniques can be used to isolate specific regions or structures of interest within an image, allowing for more detailed analysis.

Computer-assisted image processing has numerous applications in medical imaging, including detection and characterization of lesions, tumors, and other abnormalities; assessment of organ function and morphology; and guidance of interventional procedures such as biopsies and surgeries. By automating and standardizing image analysis tasks, computer-assisted image processing can help to improve diagnostic accuracy, efficiency, and consistency, while reducing the potential for human error.

The Tibial nerve is a major branch of the sciatic nerve that originates in the lower back and runs through the buttock and leg. It provides motor (nerve impulses that control muscle movement) and sensory (nerve impulses that convey information about touch, temperature, and pain) innervation to several muscles and skin regions in the lower limb.

More specifically, the Tibial nerve supplies the following structures:

1. Motor Innervation: The Tibial nerve provides motor innervation to the muscles in the back of the leg (posterior compartment), including the calf muscles (gastrocnemius and soleus) and the small muscles in the foot (intrinsic muscles). These muscles are responsible for plantarflexion (pointing the foot downward) and inversion (turning the foot inward) of the foot.
2. Sensory Innervation: The Tibial nerve provides sensory innervation to the skin on the sole of the foot, as well as the heel and some parts of the lower leg.

The Tibial nerve travels down the leg, passing behind the knee and through the calf, where it eventually joins with the common fibular (peroneal) nerve to form the tibial-fibular trunk. This trunk then divides into several smaller nerves that innervate the foot's intrinsic muscles and skin.

Damage or injury to the Tibial nerve can result in various symptoms, such as weakness or paralysis of the calf and foot muscles, numbness or tingling sensations in the sole of the foot, and difficulty walking or standing on tiptoes.

Immunohistochemistry (IHC) is a technique used in pathology and laboratory medicine to identify specific proteins or antigens in tissue sections. It combines the principles of immunology and histology to detect the presence and location of these target molecules within cells and tissues. This technique utilizes antibodies that are specific to the protein or antigen of interest, which are then tagged with a detection system such as a chromogen or fluorophore. The stained tissue sections can be examined under a microscope, allowing for the visualization and analysis of the distribution and expression patterns of the target molecule in the context of the tissue architecture. Immunohistochemistry is widely used in diagnostic pathology to help identify various diseases, including cancer, infectious diseases, and immune-mediated disorders.

X-linked genetic diseases refer to a group of disorders caused by mutations in genes located on the X chromosome. These conditions primarily affect males since they have only one X chromosome and therefore don't have a second normal copy of the gene to compensate for the mutated one. Females, who have two X chromosomes, are typically less affected because they usually have one normal copy of the gene on their other X chromosome.

Examples of X-linked genetic diseases include Duchenne and Becker muscular dystrophy, hemophilia A and B, color blindness, and fragile X syndrome. Symptoms and severity can vary widely depending on the specific condition and the nature of the genetic mutation involved. Treatment options depend on the particular disease but may include physical therapy, medication, or in some cases, gene therapy.

Conduction aphasia is a type of aphasia that is characterized by an impairment in the ability to repeat spoken or written words, despite having intact comprehension and production abilities. It is caused by damage to specific areas of the brain, typically in the left hemisphere, that are involved in language repetition and transmission.

Individuals with conduction aphasia may have difficulty repeating sentences or phrases, but they can usually understand spoken and written language and produce speech relatively well. They may also make phonological errors (substituting, adding, or omitting sounds) when speaking, particularly in more complex words or sentences.

Conduction aphasia is often caused by stroke or other types of brain injury, and it can range from mild to severe in terms of its impact on communication abilities. Treatment typically involves speech-language therapy to help individuals improve their language skills and compensate for any remaining deficits.

Atrial flutter is a type of abnormal heart rhythm or arrhythmia that originates in the atria - the upper chambers of the heart. In atrial flutter, the atria beat too quickly, usually between 250 and 350 beats per minute, which is much faster than the normal resting rate of 60 to 100 beats per minute.

This rapid beating causes the atria to quiver or "flutter" instead of contracting effectively. As a result, blood may not be pumped efficiently into the ventricles - the lower chambers of the heart - which can lead to reduced cardiac output and symptoms such as palpitations, shortness of breath, fatigue, dizziness, or chest discomfort.

Atrial flutter is often caused by underlying heart conditions, such as coronary artery disease, hypertension, valvular heart disease, or congenital heart defects. It can also be a complication of cardiac surgery or other medical procedures. In some cases, atrial flutter may occur without any apparent underlying cause, which is known as lone atrial flutter.

Treatment for atrial flutter typically involves medications to control the heart rate and rhythm, electrical cardioversion to restore a normal heart rhythm, or catheter ablation to destroy the abnormal electrical pathways in the heart that are causing the arrhythmia. In some cases, surgical intervention may be necessary to treat atrial flutter.

Electrodiagnosis, also known as electromyography (EMG), is a medical diagnostic procedure that evaluates the health and function of muscles and nerves. It measures the electrical activity of skeletal muscles at rest and during contraction, as well as the conduction of electrical signals along nerves.

The test involves inserting a thin needle electrode into the muscle to record its electrical activity. The physician will ask the patient to contract and relax the muscle while the electrical activity is recorded. The resulting data can help diagnose various neuromuscular disorders, such as nerve damage or muscle diseases, by identifying abnormalities in the electrical signals.

Electrodiagnosis can be used to diagnose conditions such as carpal tunnel syndrome, peripheral neuropathy, muscular dystrophy, and amyotrophic lateral sclerosis (ALS), among others. It is a valuable tool in the diagnosis and management of neuromuscular disorders, helping physicians to develop appropriate treatment plans for their patients.

A phenotype is the physical or biochemical expression of an organism's genes, or the observable traits and characteristics resulting from the interaction of its genetic constitution (genotype) with environmental factors. These characteristics can include appearance, development, behavior, and resistance to disease, among others. Phenotypes can vary widely, even among individuals with identical genotypes, due to differences in environmental influences, gene expression, and genetic interactions.

An axon is a long, slender extension of a neuron (a type of nerve cell) that conducts electrical impulses (nerve impulses) away from the cell body to target cells, such as other neurons or muscle cells. Axons can vary in length from a few micrometers to over a meter long and are typically surrounded by a myelin sheath, which helps to insulate and protect the axon and allows for faster transmission of nerve impulses.

Axons play a critical role in the functioning of the nervous system, as they provide the means by which neurons communicate with one another and with other cells in the body. Damage to axons can result in serious neurological problems, such as those seen in spinal cord injuries or neurodegenerative diseases like multiple sclerosis.

Catheter ablation is a medical procedure in which specific areas of heart tissue that are causing arrhythmias (irregular heartbeats) are destroyed or ablated using heat energy (radiofrequency ablation), cold energy (cryoablation), or other methods. The procedure involves threading one or more catheters through the blood vessels to the heart, where the tip of the catheter can be used to selectively destroy the problematic tissue. Catheter ablation is often used to treat atrial fibrillation, atrial flutter, and other types of arrhythmias that originate in the heart's upper chambers (atria). It may also be used to treat certain types of arrhythmias that originate in the heart's lower chambers (ventricles), such as ventricular tachycardia.

The goal of catheter ablation is to eliminate or reduce the frequency and severity of arrhythmias, thereby improving symptoms and quality of life. In some cases, it may also help to reduce the risk of stroke and other complications associated with arrhythmias. Catheter ablation is typically performed by a specialist in heart rhythm disorders (electrophysiologist) in a hospital or outpatient setting under local anesthesia and sedation. The procedure can take several hours to complete, depending on the complexity of the arrhythmia being treated.

It's important to note that while catheter ablation is generally safe and effective, it does carry some risks, such as bleeding, infection, damage to nearby structures, and the possibility of recurrent arrhythmias. Patients should discuss the potential benefits and risks of the procedure with their healthcare provider before making a decision about treatment.

Electric stimulation, also known as electrical nerve stimulation or neuromuscular electrical stimulation, is a therapeutic treatment that uses low-voltage electrical currents to stimulate nerves and muscles. It is often used to help manage pain, promote healing, and improve muscle strength and mobility. The electrical impulses can be delivered through electrodes placed on the skin or directly implanted into the body.

In a medical context, electric stimulation may be used for various purposes such as:

1. Pain management: Electric stimulation can help to block pain signals from reaching the brain and promote the release of endorphins, which are natural painkillers produced by the body.
2. Muscle rehabilitation: Electric stimulation can help to strengthen muscles that have become weak due to injury, illness, or surgery. It can also help to prevent muscle atrophy and improve range of motion.
3. Wound healing: Electric stimulation can promote tissue growth and help to speed up the healing process in wounds, ulcers, and other types of injuries.
4. Urinary incontinence: Electric stimulation can be used to strengthen the muscles that control urination and reduce symptoms of urinary incontinence.
5. Migraine prevention: Electric stimulation can be used as a preventive treatment for migraines by applying electrical impulses to specific nerves in the head and neck.

It is important to note that electric stimulation should only be administered under the guidance of a qualified healthcare professional, as improper use can cause harm or discomfort.

Atrial function in a medical context refers to the role and performance of the two upper chambers of the heart, known as the atria. The main functions of the atria are to receive blood from the veins and help pump it into the ventricles, which are the lower pumping chambers of the heart.

The atria contract in response to electrical signals generated by the sinoatrial node, which is the heart's natural pacemaker. This contraction helps to fill the ventricles with blood before they contract and pump blood out to the rest of the body. Atrial function can be assessed through various diagnostic tests, such as echocardiograms or electrocardiograms (ECGs), which can help identify any abnormalities in atrial structure or electrical activity that may affect heart function.

A "knockout" mouse is a genetically engineered mouse in which one or more genes have been deleted or "knocked out" using molecular biology techniques. This allows researchers to study the function of specific genes and their role in various biological processes, as well as potential associations with human diseases. The mice are generated by introducing targeted DNA modifications into embryonic stem cells, which are then used to create a live animal. Knockout mice have been widely used in biomedical research to investigate gene function, disease mechanisms, and potential therapeutic targets.

Animal disease models are specialized animals, typically rodents such as mice or rats, that have been genetically engineered or exposed to certain conditions to develop symptoms and physiological changes similar to those seen in human diseases. These models are used in medical research to study the pathophysiology of diseases, identify potential therapeutic targets, test drug efficacy and safety, and understand disease mechanisms.

The genetic modifications can include knockout or knock-in mutations, transgenic expression of specific genes, or RNA interference techniques. The animals may also be exposed to environmental factors such as chemicals, radiation, or infectious agents to induce the disease state.

Examples of animal disease models include:

1. Mouse models of cancer: Genetically engineered mice that develop various types of tumors, allowing researchers to study cancer initiation, progression, and metastasis.
2. Alzheimer's disease models: Transgenic mice expressing mutant human genes associated with Alzheimer's disease, which exhibit amyloid plaque formation and cognitive decline.
3. Diabetes models: Obese and diabetic mouse strains like the NOD (non-obese diabetic) or db/db mice, used to study the development of type 1 and type 2 diabetes, respectively.
4. Cardiovascular disease models: Atherosclerosis-prone mice, such as ApoE-deficient or LDLR-deficient mice, that develop plaque buildup in their arteries when fed a high-fat diet.
5. Inflammatory bowel disease models: Mice with genetic mutations affecting intestinal barrier function and immune response, such as IL-10 knockout or SAMP1/YitFc mice, which develop colitis.

Animal disease models are essential tools in preclinical research, but it is important to recognize their limitations. Differences between species can affect the translatability of results from animal studies to human patients. Therefore, researchers must carefully consider the choice of model and interpret findings cautiously when applying them to human diseases.

The sural nerve is a purely sensory peripheral nerve in the lower leg and foot. It provides sensation to the outer ( lateral) aspect of the little toe and the adjacent side of the fourth toe, as well as a small portion of the skin on the back of the leg between the ankle and knee joints.

The sural nerve is formed by the union of branches from the tibial and common fibular nerves (branches of the sciatic nerve) in the lower leg. It runs down the calf, behind the lateral malleolus (the bony prominence on the outside of the ankle), and into the foot.

The sural nerve is often used as a donor nerve during nerve grafting procedures due to its consistent anatomy and relatively low risk for morbidity at the donor site.

Embryonic and fetal development is the process of growth and development that occurs from fertilization of the egg (conception) to birth. The terms "embryo" and "fetus" are used to describe different stages of this development:

* Embryonic development: This stage begins at fertilization and continues until the end of the 8th week of pregnancy. During this time, the fertilized egg (zygote) divides and forms a blastocyst, which implants in the uterus and begins to develop into a complex structure called an embryo. The embryo consists of three layers of cells that will eventually form all of the organs and tissues of the body. During this stage, the basic structures of the body, including the nervous system, heart, and gastrointestinal tract, begin to form.
* Fetal development: This stage begins at the end of the 8th week of pregnancy and continues until birth. During this time, the embryo is called a fetus, and it grows and develops rapidly. The organs and tissues that were formed during the embryonic stage continue to mature and become more complex. The fetus also begins to move and kick, and it can hear and respond to sounds from outside the womb.

Overall, embryonic and fetal development is a complex and highly regulated process that involves the coordinated growth and differentiation of cells and tissues. It is a critical period of development that lays the foundation for the health and well-being of the individual throughout their life.

Atrial fibrillation (A-tre-al fi-bru-la'shun) is a type of abnormal heart rhythm characterized by rapid and irregular beating of the atria, the upper chambers of the heart. In this condition, the electrical signals that coordinate heartbeats don't function properly, causing the atria to quiver instead of contracting effectively. As a result, blood may not be pumped efficiently into the ventricles, which can lead to blood clots, stroke, and other complications. Atrial fibrillation is a common type of arrhythmia and can cause symptoms such as palpitations, shortness of breath, fatigue, and dizziness. It can be caused by various factors, including heart disease, high blood pressure, age, and genetics. Treatment options include medications, electrical cardioversion, and surgical procedures to restore normal heart rhythm.

Acetylcholinesterase (AChE) is an enzyme that catalyzes the hydrolysis of acetylcholine (ACh), a neurotransmitter, into choline and acetic acid. This enzyme plays a crucial role in regulating the transmission of nerve impulses across the synapse, the junction between two neurons or between a neuron and a muscle fiber.

Acetylcholinesterase is located in the synaptic cleft, the narrow gap between the presynaptic and postsynaptic membranes. When ACh is released from the presynaptic membrane and binds to receptors on the postsynaptic membrane, it triggers a response in the target cell. Acetylcholinesterase rapidly breaks down ACh, terminating its action and allowing for rapid cycling of neurotransmission.

Inhibition of acetylcholinesterase leads to an accumulation of ACh in the synaptic cleft, prolonging its effects on the postsynaptic membrane. This can result in excessive stimulation of cholinergic receptors and overactivation of the cholinergic system, which may cause a range of symptoms, including muscle weakness, fasciculations, sweating, salivation, lacrimation, urination, defecation, bradycardia, and bronchoconstriction.

Acetylcholinesterase inhibitors are used in the treatment of various medical conditions, such as Alzheimer's disease, myasthenia gravis, and glaucoma. However, they can also be used as chemical weapons, such as nerve agents, due to their ability to disrupt the nervous system and cause severe toxicity.

The Fluorescent Antibody Technique (FAT) is a type of immunofluorescence assay used in laboratory medicine and pathology for the detection and localization of specific antigens or antibodies in tissues, cells, or microorganisms. In this technique, a fluorescein-labeled antibody is used to selectively bind to the target antigen or antibody, forming an immune complex. When excited by light of a specific wavelength, the fluorescein label emits light at a longer wavelength, typically visualized as green fluorescence under a fluorescence microscope.

The FAT is widely used in diagnostic microbiology for the identification and characterization of various bacteria, viruses, fungi, and parasites. It has also been applied in the diagnosis of autoimmune diseases and certain cancers by detecting specific antibodies or antigens in patient samples. The main advantage of FAT is its high sensitivity and specificity, allowing for accurate detection and differentiation of various pathogens and disease markers. However, it requires specialized equipment and trained personnel to perform and interpret the results.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Peripheral Nervous System (PNS) diseases, also known as Peripheral Neuropathies, refer to conditions that affect the functioning of the peripheral nervous system, which includes all the nerves outside the brain and spinal cord. These nerves transmit signals between the central nervous system (CNS) and the rest of the body, controlling sensations, movements, and automatic functions such as heart rate and digestion.

PNS diseases can be caused by various factors, including genetics, infections, toxins, metabolic disorders, trauma, or autoimmune conditions. The symptoms of PNS diseases depend on the type and extent of nerve damage but often include:

1. Numbness, tingling, or pain in the hands and feet
2. Muscle weakness or cramps
3. Loss of reflexes
4. Decreased sensation to touch, temperature, or vibration
5. Coordination problems and difficulty with balance
6. Sexual dysfunction
7. Digestive issues, such as constipation or diarrhea
8. Dizziness or fainting due to changes in blood pressure

Examples of PNS diseases include Guillain-Barre syndrome, Charcot-Marie-Tooth disease, diabetic neuropathy, and peripheral nerve injuries. Treatment for these conditions varies depending on the underlying cause but may involve medications, physical therapy, lifestyle changes, or surgery.

Morphogenesis is a term used in developmental biology and refers to the process by which cells give rise to tissues and organs with specific shapes, structures, and patterns during embryonic development. This process involves complex interactions between genes, cells, and the extracellular environment that result in the coordinated movement and differentiation of cells into specialized functional units.

Morphogenesis is a dynamic and highly regulated process that involves several mechanisms, including cell proliferation, death, migration, adhesion, and differentiation. These processes are controlled by genetic programs and signaling pathways that respond to environmental cues and regulate the behavior of individual cells within a developing tissue or organ.

The study of morphogenesis is important for understanding how complex biological structures form during development and how these processes can go awry in disease states such as cancer, birth defects, and degenerative disorders.

Myosin Heavy Chains are the large, essential components of myosin molecules, which are responsible for the molecular motility in muscle cells. These heavy chains have a molecular weight of approximately 200 kDa and form the motor domain of myosin, which binds to actin filaments and hydrolyzes ATP to generate force and movement during muscle contraction. There are several different types of myosin heavy chains, each with specific roles in various tissues and cellular functions. In skeletal and cardiac muscles, for example, myosin heavy chains have distinct isoforms that contribute to the contractile properties of these tissues.

Diabetic neuropathies refer to a group of nerve disorders that are caused by diabetes. High blood sugar levels can injure nerves throughout the body, but diabetic neuropathies most commonly affect the nerves in the legs and feet.

There are four main types of diabetic neuropathies:

1. Peripheral neuropathy: This is the most common type of diabetic neuropathy. It affects the nerves in the legs and feet, causing symptoms such as numbness, tingling, burning, or shooting pain.
2. Autonomic neuropathy: This type of neuropathy affects the autonomic nerves, which control involuntary functions such as heart rate, blood pressure, digestion, and bladder function. Symptoms may include dizziness, fainting, digestive problems, sexual dysfunction, and difficulty regulating body temperature.
3. Proximal neuropathy: Also known as diabetic amyotrophy, this type of neuropathy affects the nerves in the hips, thighs, or buttocks, causing weakness, pain, and difficulty walking.
4. Focal neuropathy: This type of neuropathy affects a single nerve or group of nerves, causing symptoms such as weakness, numbness, or pain in the affected area. Focal neuropathies can occur anywhere in the body, but they are most common in the head, torso, and legs.

The risk of developing diabetic neuropathies increases with the duration of diabetes and poor blood sugar control. Other factors that may contribute to the development of diabetic neuropathies include genetics, age, smoking, and alcohol consumption.

Gestational age is the length of time that has passed since the first day of the last menstrual period (LMP) in pregnant women. It is the standard unit used to estimate the age of a pregnancy and is typically expressed in weeks. This measure is used because the exact date of conception is often not known, but the start of the last menstrual period is usually easier to recall.

It's important to note that since ovulation typically occurs around two weeks after the start of the LMP, gestational age is approximately two weeks longer than fetal age, which is the actual time elapsed since conception. Medical professionals use both gestational and fetal age to track the development and growth of the fetus during pregnancy.

Motor neurons are specialized nerve cells in the brain and spinal cord that play a crucial role in controlling voluntary muscle movements. They transmit electrical signals from the brain to the muscles, enabling us to perform actions such as walking, talking, and swallowing. There are two types of motor neurons: upper motor neurons, which originate in the brain's motor cortex and travel down to the brainstem and spinal cord; and lower motor neurons, which extend from the brainstem and spinal cord to the muscles. Damage or degeneration of these motor neurons can lead to various neurological disorders, such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA).

Heart function tests are a group of diagnostic exams that are used to evaluate the structure and functioning of the heart. These tests help doctors assess the pumping efficiency of the heart, the flow of blood through the heart, the presence of any heart damage, and the overall effectiveness of the heart in delivering oxygenated blood to the rest of the body.

Some common heart function tests include:

1. Echocardiogram (Echo): This test uses sound waves to create detailed images of the heart's structure and functioning. It can help detect any damage to the heart muscle, valves, or sac surrounding the heart.
2. Nuclear Stress Test: This test involves injecting a small amount of radioactive substance into the patient's bloodstream and taking images of the heart while it is at rest and during exercise. The test helps evaluate blood flow to the heart and detect any areas of reduced blood flow, which could indicate coronary artery disease.
3. Cardiac Magnetic Resonance Imaging (MRI): This test uses magnetic fields and radio waves to create detailed images of the heart's structure and function. It can help detect any damage to the heart muscle, valves, or other structures of the heart.
4. Electrocardiogram (ECG): This test measures the electrical activity of the heart and helps detect any abnormalities in the heart's rhythm or conduction system.
5. Exercise Stress Test: This test involves walking on a treadmill or riding a stationary bike while being monitored for changes in heart rate, blood pressure, and ECG readings. It helps evaluate exercise capacity and detect any signs of coronary artery disease.
6. Cardiac Catheterization: This is an invasive procedure that involves inserting a catheter into the heart to measure pressures and take samples of blood from different parts of the heart. It can help diagnose various heart conditions, including heart valve problems, congenital heart defects, and coronary artery disease.

Overall, heart function tests play an essential role in diagnosing and managing various heart conditions, helping doctors provide appropriate treatment and improve patient outcomes.

The sciatic nerve is the largest and longest nerve in the human body, running from the lower back through the buttocks and down the legs to the feet. It is formed by the union of the ventral rami (branches) of the L4 to S3 spinal nerves. The sciatic nerve provides motor and sensory innervation to various muscles and skin areas in the lower limbs, including the hamstrings, calf muscles, and the sole of the foot. Sciatic nerve disorders or injuries can result in symptoms such as pain, numbness, tingling, or weakness in the lower back, hips, legs, and feet, known as sciatica.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

In situ hybridization (ISH) is a molecular biology technique used to detect and localize specific nucleic acid sequences, such as DNA or RNA, within cells or tissues. This technique involves the use of a labeled probe that is complementary to the target nucleic acid sequence. The probe can be labeled with various types of markers, including radioisotopes, fluorescent dyes, or enzymes.

During the ISH procedure, the labeled probe is hybridized to the target nucleic acid sequence in situ, meaning that the hybridization occurs within the intact cells or tissues. After washing away unbound probe, the location of the labeled probe can be visualized using various methods depending on the type of label used.

In situ hybridization has a wide range of applications in both research and diagnostic settings, including the detection of gene expression patterns, identification of viral infections, and diagnosis of genetic disorders.

The Peroneal nerve, also known as the common fibular nerve, is a branch of the sciatic nerve that supplies the muscles of the lower leg and provides sensation to the skin on the outer part of the lower leg and the top of the foot. It winds around the neck of the fibula (calf bone) and can be vulnerable to injury in this area, leading to symptoms such as weakness or numbness in the foot and leg.

Three-dimensional (3D) imaging in medicine refers to the use of technologies and techniques that generate a 3D representation of internal body structures, organs, or tissues. This is achieved by acquiring and processing data from various imaging modalities such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, or confocal microscopy. The resulting 3D images offer a more detailed visualization of the anatomy and pathology compared to traditional 2D imaging techniques, allowing for improved diagnostic accuracy, surgical planning, and minimally invasive interventions.

In 3D imaging, specialized software is used to reconstruct the acquired data into a volumetric model, which can be manipulated and viewed from different angles and perspectives. This enables healthcare professionals to better understand complex anatomical relationships, detect abnormalities, assess disease progression, and monitor treatment response. Common applications of 3D imaging include neuroimaging, orthopedic surgery planning, cancer staging, dental and maxillofacial reconstruction, and interventional radiology procedures.

The neural crest is a transient, multipotent embryonic cell population that originates from the ectoderm (outermost layer) of the developing neural tube (precursor to the central nervous system). These cells undergo an epithelial-to-mesenchymal transition and migrate throughout the embryo, giving rise to a diverse array of cell types and structures.

Neural crest cells differentiate into various tissues, including:

1. Peripheral nervous system (PNS) components: sensory neurons, sympathetic and parasympathetic ganglia, and glial cells (e.g., Schwann cells).
2. Facial bones and cartilage, as well as connective tissue of the skull.
3. Melanocytes, which are pigment-producing cells in the skin.
4. Smooth muscle cells in major blood vessels, heart, gastrointestinal tract, and other organs.
5. Secretory cells in endocrine glands (e.g., chromaffin cells of the adrenal medulla).
6. Parts of the eye, such as the cornea and iris stroma.
7. Dental tissues, including dentin, cementum, and dental pulp.

Due to their wide-ranging contributions to various tissues and organs, neural crest cells play a crucial role in embryonic development and organogenesis. Abnormalities in neural crest cell migration or differentiation can lead to several congenital disorders, such as neurocristopathies.

Myocardial ischemia is a condition in which the blood supply to the heart muscle (myocardium) is reduced or blocked, leading to insufficient oxygen delivery and potential damage to the heart tissue. This reduction in blood flow typically results from the buildup of fatty deposits, called plaques, in the coronary arteries that supply the heart with oxygen-rich blood. The plaques can rupture or become unstable, causing the formation of blood clots that obstruct the artery and limit blood flow.

Myocardial ischemia may manifest as chest pain (angina pectoris), shortness of breath, fatigue, or irregular heartbeats (arrhythmias). In severe cases, it can lead to myocardial infarction (heart attack) if the oxygen supply is significantly reduced or cut off completely, causing permanent damage or death of the heart muscle. Early diagnosis and treatment of myocardial ischemia are crucial for preventing further complications and improving patient outcomes.

Ranvier's nodes, also known as nodes of Ranvier, are specialized structures in the nervous system. They are gaps in the myelin sheath, a fatty insulating substance that surrounds the axons of many neurons, leaving them exposed. These nodes play a crucial role in the rapid transmission of electrical signals along the neuron. The unmyelinated sections of the axon at the nodes have a higher concentration of voltage-gated sodium channels, which generate the action potential that propagates along the neuron. The myelinated segments between the nodes, called internodes, help to speed up this process by allowing the action potential to "jump" from node to node, a mechanism known as saltatory conduction. This process significantly increases the speed of neural impulse transmission, making it more efficient. Ranvier's nodes are named after Louis-Antoine Ranvier, a French histologist and physiologist who first described them in the late 19th century.

Myosins are a large family of motor proteins that play a crucial role in various cellular processes, including muscle contraction and intracellular transport. They consist of heavy chains, which contain the motor domain responsible for generating force and motion, and light chains, which regulate the activity of the myosin. Based on their structural and functional differences, myosins are classified into over 35 classes, with classes II, V, and VI being the most well-studied.

Class II myosins, also known as conventional myosins, are responsible for muscle contraction in skeletal, cardiac, and smooth muscles. They form filaments called thick filaments, which interact with actin filaments to generate force and movement during muscle contraction.

Class V myosins, also known as unconventional myosins, are involved in intracellular transport and organelle positioning. They have a long tail that can bind to various cargoes, such as vesicles, mitochondria, and nuclei, and a motor domain that moves along actin filaments to transport the cargoes to their destinations.

Class VI myosins are also unconventional myosins involved in intracellular transport and organelle positioning. They have two heads connected by a coiled-coil tail, which can bind to various cargoes. Class VI myosins move along actin filaments in a unique hand-over-hand motion, allowing them to transport their cargoes efficiently.

Overall, myosins are essential for many cellular functions and have been implicated in various diseases, including cardiovascular diseases, neurological disorders, and cancer.

Induced heart arrest, also known as controlled cardiac arrest or planned cardiac arrest, is a deliberate medical intervention where cardiac activity is temporarily stopped through the use of medications or electrical disruption. This procedure is typically carried out during a surgical procedure, such as open-heart surgery, where the heart needs to be stilled to allow surgeons to work on it safely.

The most common method used to induce heart arrest is by administering a medication called potassium chloride, which stops the heart's electrical activity. Alternatively, an electrical shock may be delivered to the heart to achieve the same effect. Once the procedure is complete, the heart can be restarted using various resuscitation techniques, such as defibrillation or medication administration.

It's important to note that induced heart arrest is a carefully monitored and controlled medical procedure carried out by trained healthcare professionals in a hospital setting. It should not be confused with sudden cardiac arrest, which is an unexpected and often unpredictable event that occurs outside of a medical setting.

A biological marker, often referred to as a biomarker, is a measurable indicator that reflects the presence or severity of a disease state, or a response to a therapeutic intervention. Biomarkers can be found in various materials such as blood, tissues, or bodily fluids, and they can take many forms, including molecular, histologic, radiographic, or physiological measurements.

In the context of medical research and clinical practice, biomarkers are used for a variety of purposes, such as:

1. Diagnosis: Biomarkers can help diagnose a disease by indicating the presence or absence of a particular condition. For example, prostate-specific antigen (PSA) is a biomarker used to detect prostate cancer.
2. Monitoring: Biomarkers can be used to monitor the progression or regression of a disease over time. For instance, hemoglobin A1c (HbA1c) levels are monitored in diabetes patients to assess long-term blood glucose control.
3. Predicting: Biomarkers can help predict the likelihood of developing a particular disease or the risk of a negative outcome. For example, the presence of certain genetic mutations can indicate an increased risk for breast cancer.
4. Response to treatment: Biomarkers can be used to evaluate the effectiveness of a specific treatment by measuring changes in the biomarker levels before and after the intervention. This is particularly useful in personalized medicine, where treatments are tailored to individual patients based on their unique biomarker profiles.

It's important to note that for a biomarker to be considered clinically valid and useful, it must undergo rigorous validation through well-designed studies, including demonstrating sensitivity, specificity, reproducibility, and clinical relevance.

A zebrafish is a freshwater fish species belonging to the family Cyprinidae and the genus Danio. Its name is derived from its distinctive striped pattern that resembles a zebra's. Zebrafish are often used as model organisms in scientific research, particularly in developmental biology, genetics, and toxicology studies. They have a high fecundity rate, transparent embryos, and a rapid development process, making them an ideal choice for researchers. However, it is important to note that providing a medical definition for zebrafish may not be entirely accurate or relevant since they are primarily used in biological research rather than clinical medicine.

Carpal Tunnel Syndrome (CTS) is a common peripheral nerve disorder that affects the median nerve, which runs from the forearm into the hand through a narrow tunnel-like structure in the wrist called the carpal tunnel. The condition is caused by compression or pinching of the median nerve as it passes through this tunnel, leading to various symptoms such as numbness, tingling, and weakness in the hand and fingers.

The median nerve provides sensation to the thumb, index finger, middle finger, and half of the ring finger. It also controls some small muscles in the hand that allow for fine motor movements. When the median nerve is compressed or damaged due to CTS, it can result in a range of symptoms including:

1. Numbness, tingling, or burning sensations in the fingers (especially the thumb, index finger, middle finger, and half of the ring finger)
2. Pain or discomfort in the hand, wrist, or forearm
3. Weakness in the hand, leading to difficulty gripping objects or making a fist
4. A sensation of swelling or inflammation in the fingers, even if there is no visible swelling present
5. Nighttime symptoms that may disrupt sleep patterns

The exact cause of Carpal Tunnel Syndrome can vary from person to person, but some common risk factors include:

1. Repetitive hand and wrist motions (such as typing, writing, or using tools)
2. Prolonged exposure to vibrations (from machinery or power tools)
3. Wrist trauma or fractures
4. Pregnancy and hormonal changes
5. Certain medical conditions like diabetes, rheumatoid arthritis, and thyroid disorders
6. Obesity
7. Smoking

Diagnosis of Carpal Tunnel Syndrome typically involves a physical examination, medical history review, and sometimes specialized tests like nerve conduction studies or electromyography to confirm the diagnosis and assess the severity of the condition. Treatment options may include splinting, medication, corticosteroid injections, and in severe cases, surgery to relieve pressure on the median nerve.

The endocardium is the innermost layer of tissue that lines the chambers of the heart and the valves between them. It is a thin, smooth membrane that is in contact with the blood within the heart. This layer helps to maintain the heart's internal environment, facilitates the smooth movement of blood through the heart, and provides a protective barrier against infection and other harmful substances. The endocardium is composed of simple squamous epithelial cells called endothelial cells, which are supported by a thin layer of connective tissue.

Cell differentiation is the process by which a less specialized cell, or stem cell, becomes a more specialized cell type with specific functions and structures. This process involves changes in gene expression, which are regulated by various intracellular signaling pathways and transcription factors. Differentiation results in the development of distinct cell types that make up tissues and organs in multicellular organisms. It is a crucial aspect of embryonic development, tissue repair, and maintenance of homeostasis in the body.

Body Surface Potential Mapping (BSPM) is a non-invasive medical technique used to record and analyze the electrical activity of the heart from the surface of the body. It involves placing multiple electrodes on the skin of the chest, back, and limbs to measure the potential differences between these points during each heartbeat. This information is then used to create a detailed, visual representation of the electrical activation pattern of the heart, which can help in the diagnosis and evaluation of various cardiac disorders such as arrhythmias, myocardial infarction, and ventricular hypertrophy.

The BSPM technique provides high-resolution spatial and temporal information about the cardiac electrical activity, making it a valuable tool for both clinical and research purposes. It can help identify the origin and spread of abnormal electrical signals in the heart, which is crucial for determining appropriate treatment strategies. Overall, Body Surface Potential Mapping is an important diagnostic modality that offers unique insights into the electrical functioning of the heart.

Hemodynamics is the study of how blood flows through the cardiovascular system, including the heart and the vascular network. It examines various factors that affect blood flow, such as blood volume, viscosity, vessel length and diameter, and pressure differences between different parts of the circulatory system. Hemodynamics also considers the impact of various physiological and pathological conditions on these variables, and how they in turn influence the function of vital organs and systems in the body. It is a critical area of study in fields such as cardiology, anesthesiology, and critical care medicine.

Electromyography (EMG) is a medical diagnostic procedure that measures the electrical activity of skeletal muscles during contraction and at rest. It involves inserting a thin needle electrode into the muscle to record the electrical signals generated by the muscle fibers. These signals are then displayed on an oscilloscope and may be heard through a speaker.

EMG can help diagnose various neuromuscular disorders, such as muscle weakness, numbness, or pain, and can distinguish between muscle and nerve disorders. It is often used in conjunction with other diagnostic tests, such as nerve conduction studies, to provide a comprehensive evaluation of the nervous system.

EMG is typically performed by a neurologist or a physiatrist, and the procedure may cause some discomfort or pain, although this is usually minimal. The results of an EMG can help guide treatment decisions and monitor the progression of neuromuscular conditions over time.

Supraventricular tachycardia (SVT) is a rapid heart rhythm that originates above the ventricles (the lower chambers of the heart). This type of tachycardia includes atrial tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), and atrioventricular reentrant tachycardia (AVRT). SVT usually causes a rapid heartbeat that starts and stops suddenly, and may not cause any other symptoms. However, some people may experience palpitations, shortness of breath, chest discomfort, dizziness, or fainting. SVT is typically diagnosed through an electrocardiogram (ECG) or Holter monitor, and can be treated with medications, cardioversion, or catheter ablation.

Left ventricular function refers to the ability of the left ventricle (the heart's lower-left chamber) to contract and relax, thereby filling with and ejecting blood. The left ventricle is responsible for pumping oxygenated blood to the rest of the body. Its function is evaluated by measuring several parameters, including:

1. Ejection fraction (EF): This is the percentage of blood that is pumped out of the left ventricle with each heartbeat. A normal ejection fraction ranges from 55% to 70%.
2. Stroke volume (SV): The amount of blood pumped by the left ventricle in one contraction. A typical SV is about 70 mL/beat.
3. Cardiac output (CO): The total volume of blood that the left ventricle pumps per minute, calculated as the product of stroke volume and heart rate. Normal CO ranges from 4 to 8 L/minute.

Assessment of left ventricular function is crucial in diagnosing and monitoring various cardiovascular conditions such as heart failure, coronary artery disease, valvular heart diseases, and cardiomyopathies.

Gap junctions are specialized intercellular connections that allow for the direct exchange of ions, small molecules, and electrical signals between adjacent cells. They are composed of arrays of channels called connexons, which penetrate the cell membranes of two neighboring cells and create a continuous pathway for the passage of materials from one cytoplasm to the other. Each connexon is formed by the assembly of six proteins called connexins, which are encoded by different genes and vary in their biophysical properties. Gap junctions play crucial roles in many physiological processes, including the coordination of electrical activity in excitable tissues, the regulation of cell growth and differentiation, and the maintenance of tissue homeostasis. Mutations or dysfunctions in gap junction channels have been implicated in various human diseases, such as cardiovascular disorders, neurological disorders, skin disorders, and cancer.

Perfusion, in medical terms, refers to the process of circulating blood through the body's organs and tissues to deliver oxygen and nutrients and remove waste products. It is a measure of the delivery of adequate blood flow to specific areas or tissues in the body. Perfusion can be assessed using various methods, including imaging techniques like computed tomography (CT) scans, magnetic resonance imaging (MRI), and perfusion scintigraphy.

Perfusion is critical for maintaining proper organ function and overall health. When perfusion is impaired or inadequate, it can lead to tissue hypoxia, acidosis, and cell death, which can result in organ dysfunction or failure. Conditions that can affect perfusion include cardiovascular disease, shock, trauma, and certain surgical procedures.

Myelinated nerve fibers are neuronal processes that are surrounded by a myelin sheath, a fatty insulating substance that is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. This myelin sheath helps to increase the speed of electrical impulse transmission, also known as action potentials, along the nerve fiber. The myelin sheath has gaps called nodes of Ranvier where the electrical impulses can jump from one node to the next, which also contributes to the rapid conduction of signals. Myelinated nerve fibers are typically found in the peripheral nerves and the optic nerve, but not in the central nervous system (CNS) tracts that are located within the brain and spinal cord.

I must clarify that the term "pedigree" is not typically used in medical definitions. Instead, it is often employed in genetics and breeding, where it refers to the recorded ancestry of an individual or a family, tracing the inheritance of specific traits or diseases. In human genetics, a pedigree can help illustrate the pattern of genetic inheritance in families over multiple generations. However, it is not a medical term with a specific clinical definition.

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Pacemaker failure Electrical conduction system of the heart Yarlagadda, Chakri. "Pacemaker Malfunction". eMedicine. Retrieved ... Crosstalk is more common in unipolar systems since they require a larger pacing spike. Crosstalk is sometimes referred to as ...
Anatomy figure: 20:06-02 at Human Anatomy Online, SUNY Downstate Medical Center - "The conduction system of the heart." ... it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of the interatrial ... The cardiac conduction system (and AV node part of it) coordinates myocyte mechanical activity. A wave of excitation spreads ... This property is important because loss of the conduction system before the AV node should still result in pacing of the ...
The electrical conduction system of the heart has been robustly established. However, newer research has been challenging some ... Ephaptic coupling is a form of communication within the nervous system and is distinct from direct communication systems like ... A number of studies have shown how inhibition among neurons in the olfactory system work to fine-tune integration of signals in ... Heart Circ. Physiol. 306 (5): H619-27. doi:10.1152/ajpheart.00760.2013. PMC 3949060. PMID 24414064. Ivanovic, Ena; Kucera, Jan ...
These cells are found in the conduction system of the heart and include the SA node, AV node, Bundle of His, and Purkinje ... Arrhythmias are due to problems with the electrical conduction system of the heart. A number of tests can help with diagnosis, ... The resting heart rate in children is much faster. In athletes, however, the resting heart rate can be as slow as 40 beats per ... A resting heart rate that is too fast - above 100 beats per minute in adults - is called tachycardia, and a resting heart rate ...
Cardiac ectopy Clinical cardiac electrophysiology Electrical conduction system of the heart Phibbs, B. (1963). "Paroxysmal ... conduction across ventricles An ectopic pacemaker can reside within a part of the electrical conduction system of the heart, or ... is an excitable group of cells that causes a premature heart beat outside the normally functioning SA node of the heart. It is ... In a normal heart beat rhythm, the SA node usually suppresses the ectopic pacemaker activity due to the higher impulse rate of ...
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A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical conduction system. During a ... Prevalence of RBBB increases with age due to changes in the heart's conduction system. It's estimated up to 11.3% of the ... As conduction through the myocardium is slower than conduction through the Bundle of His-Purkinje fibres, the QRS complex is ... However, according to the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Foundation (AHA/ ...
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It refers to the disorder in the electrical conduction system within the heart muscle, which leads to the failure in pumping ... Its existence affects the conduction system of the heart and increases the mortality rate and the need for pace-maker ... These developmental abnormalities can impair the conduction system of the heart by disrupting its anatomical structure. There ... The congenital heart block (CHB) is the heart block that is diagnosed in fetus (in utero) or within the first 28 days after ...
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This is caused by an obstruction - a block - in the electrical conduction system of the heart. Sometimes a disorder can be ... ISBN 0-397-54589-4. "Conduction Disorders". sitecoreprod.heart.org,beta.heart.org,www.heart.org,heart.org,*.azurewebsites.net, ... complete heart block) Infra-Hisian block is that of the distal conduction system. Types of infra-Hisian block include: Type 2 ... depending upon exactly where in the heart conduction is being impaired and how significantly it is affected. Heart block should ...
... is a disturbance of the cardiac rhythm frequently related to the electrical conduction system of the heart, in ... Ectopic beats often remain undetected and occur as part of minor errors in the heart conduction system. They are rarely ... or from finer branches of the electric transduction system, cause additional beats of the heart. Some medications may worsen ... "heart hiccup", while others report dropped or missed beats. Ectopic beats are more common during periods of psychological ...
... is a disease of the electrical conduction system of the heart. It is a conduction block between the atria and ventricles. The ... is almost always a disease of the distal conduction system (His-Purkinje System). Mobitz II heart block is characterized on a ... Type 1 second-degree heart block is considered more benign than type 2 second-degree heart block. The type 1 does not have ... On the partial block of impulse conduction between atrium and ventricle of human hearts]". Z Gesamte Exp Med. 41: 180-237. doi: ...
The Conduction System of the Mammalian Heart Proceedings of the 5th Tawara-Aschoff Symposium on Cardiac Conduction System, p. ... Tawara's monograph, "Das Reizleitungssystem des Säugetierherzens" (English: "The Conduction System of the Mammalian Heart") was ... B. Upshaw, Jr, Why Does the Heart Beat? The Discovery of the Electricals System of the Heart. Circulation 2006, 113, 2775-2781 ... It was here he undertook his important works on pathology and anatomy of heart. Upon returning to Japan he was appointed ...
Disorders affecting the cardiomyocytes that make up the electrical conduction system of the heart are called heart blocks. ... is a collection of heart muscle cells specialized for electrical conduction. As part of the electrical conduction system of the ... The bundle of His is an important part of the electrical conduction system of the heart, as it transmits impulses from the ... The ventricular conduction system comprises the bundle branches and the Purkinje networks. It takes about 0.03-0.04 seconds for ...
These electrical impulses coordinate contraction throughout the remaining heart muscle via the electrical conduction system of ... These systems act to increase and decrease, respectively, the rate of production of electrical impulses by the sinoatrial node ... Cardiac muscle cells form the cardiac muscle in the walls of the heart chambers, and have a single central nucleus. Cardiac ... Thus, although a common muscle patterning system has been determined, they argue that this could be due to a more ancestral ...
... and Molecular Investigation of the Cardiac Conduction System and Arrhythmogenic Atrioventricular Ring Tissue in the Rat Heart ... It is unclear from this announcement whether Empiria Studio will support acquisition for Odyssey FC imaging systems previously ... ". Journal of the American Heart Association. 2 (6): e000246. doi:10.1161/JAHA.113.000246. PMC 3886739. PMID 24356527. Lo, A. W ...
Cardiac ectopy Clinical cardiac electrophysiology Electrical conduction system of the heart Supraventricular tachycardia Lister ... Atrial ectopic tachycardia, in which the focus or foci are in the atria of the heart, is an automatic tachycardia. Atrial ... An automatic tachycardia is a cardiac arrhythmia which involves an area of the heart generating an abnormally fast rhythm, ... These tachycardias, or fast heart rhythms, differ from reentrant tachycardias (AVRT and AVNRT) in which there is an abnormal ...
... aortic valve insufficiency or disturbances of the heart's electrical conduction system. Lung involvement is characterized by ... Organs commonly affected by AS, other than the axial spine and other joints, are the heart, lungs, eyes, colon, and kidneys. ... pulmonary disease and heart valve disease may lead suspicion away from other juvenile spondyloarthropathies. The Schober's test ...
... which results in abnormalities of the electrical conduction system of the heart. Consequences related to serum concentration:: ... Abnormal heart rhythms and asystole are possible complications of hypermagnesemia related to the heart. Magnesium acts as a ... Altered atrioventricular conduction and (further) complete heart block >25.0 mEq/L - Cardiac arrest Severe hypermagnesemia ( ... As well as nausea, low blood pressure, low blood calcium, abnormal heart rhythms and asystole, dizziness, and sleepiness. ...
Electrical conduction system of the heart Silverman, M. E. (13 June 2006). "Why Does the Heart Beat?: The Discovery of the ... He credited Tawara for connecting the bundle with the Purkinje fibers and for declaring it the heart's conduction system. ... Das Reizleitungssystem des Säugetierherzens (English: "The Conduction System of the Mammalian Heart") is a scientific monograph ... "The Conduction System of the Mammalian Heart") was published in 1906. The most important discoveries are listed below: The ...
Heart block - A decrease in the ability of the conduction system to transmit action pulses in the orderly manner. Blockage of ... American College of Cardiology American Heart Association Heart Rhythm Society Indian Heart Association National Heart ... Heart cancer - Cancer of the heart is very rare and those cancers tend to be benign. Myxoma - Most common tumor of the heart. ... Heart failure - Heart failure is failure of the heart to produce sufficient blood flow to meet metabolic demands of the body, ...
The pacemaker cells make up 1% of cells and form the conduction system of the heart. They are generally much smaller than the ... In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in ... specimen of the heart Heart illustration with circulatory system Animated Heart 3d Model Rendered in Computer From the heart to ... "gill hearts" also known as branchial hearts, and one "systemic heart". The branchial hearts have two atria and one ventricle ...
Heart; conduction system (SA node labeled 1) Schematic representation of the atrioventricular bundle Cardiac pacemaker ... Anatomy figure: 20:06-01 at Human Anatomy Online, SUNY Downstate Medical Center - "The conduction system of the heart." Diagram ... an electrical impulse known as a cardiac action potential that travels through the electrical conduction system of the heart, ... Heart rate depends on the rate at which the sinoatrial node produces action potentials. At rest, heart rate is between 60 and ...
This electrical activity is recorded when the heart is in a normal rhythm (sinus rhythm) to assess the conduction system of the ... Electrocardiogram (ECG or EKG) Electrical conduction system of the heart Ventricular tachycardia Arrhythmia Antiarrhythmic ... equipment to record electrical signals from the heart, a stimulator to electrically excite the heart and control the heart rate ... The electrophysiologist begins by moving the electrodes along the conduction pathways and along the inner walls of the heart, ...
"Heart Conduction System" by people in this website by year, and whether "Heart Conduction System" was a major or minor topic of ... "Heart Conduction System" by people in Profiles.. * Dikdan SJ, Co ML, Pavri BB. Dyssynchronous Heart Failure: A Clinical Review ... "Heart Conduction System" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical ... Heart Conduction System*Heart Conduction System. *Conduction System, Heart. *Conduction Systems, Heart ...
The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated ... Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow. ... The conduction system consists of specialized heart muscle cells, situated within the myocardium. There is a skeleton of ... In order to maximize efficiency of contractions and cardiac output, the conduction system of the heart has: Substantial atrial ...
The cardiac conduction system (CCS) (also called the electrical conduction system of the heart)[1] transmits the signals ... Main article: Heart development § Pacemaker and conduction system. Embryologic evidence of generation of the cardiac conduction ... Graphical representation of the electrical conduction system of the heart that maintains the heart rate in the cardiac cycle. ... The conduction system consists of specialized heart muscle cells, situated within the myocardium.[3] There is a skeleton of ...
The hearts conduction system Enlarge image Close The hearts conduction system. The hearts conduction system. The hearts ... They tell the heart when to beat.. Changes in heart signaling may happen if the heart muscle is damaged. Heart signaling ... conduction system also is called the hearts electrical signaling system. Electrical signals start in a group of cells at the ... It stimulates the heart as needed to keep it beating regularly.. The hearts electrical system typically controls the heartbeat ...
... cardiac conduction system, cardial, cardio, cardiology, cardiovascular, coronary, heart, heartbeat, hearts, myocardial, ... cut-away view of the heart with the components of the cardiac conduction system. Labeled items include: the Sinoatrial (SA) ... Node, or pacemaker of the heart; the Atrioventricular (AV) node; and the Atrioventricular Bundle, or Bundle of HIS. ...
electrical conduction system of the heart What is a myocardial cells charge when it is depolarized? ... electrical conduction system of the heart. What is a myocardial cells charge when it is depolarized?. ...
A medical illustration showing The Conduction System of the Heart. ... Medical Legal Illustrations & Animations: Home , General Anatomy Exhibits , Heart , The Conduction System of the Heart - 406039 ... Normal conduction system of the heart and EKG tracing compared to multiple abnormal EKG tracings. ...
... that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below). They initiate ... The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) ... encoded search term (Conduction System of the Heart) and Conduction System of the Heart What to Read Next on Medscape ... Conduction System of the Heart. Updated: Nov 06, 2013 * Author: Ramin Assadi, MD; Chief Editor: Richard A Lange, MD, MBA more ...
... that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below). They initiate ... The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) ... encoded search term (Conduction System of the Heart) and Conduction System of the Heart What to Read Next on Medscape ... Conduction System of the Heart. Updated: Nov 06, 2013 * Author: Ramin Assadi, MD; Chief Editor: Richard A Lange, MD, MBA more ...
Congestive heart failure, valvular heart disease, arrhythmia, and conduction system disease. Patients with congestive heart ... Cardiovascular System. Ischemic heart disease. Patients with known coronary artery disease undergoing surgery should be ... Heart valve prostheses. For those patients with heart valve prostheses, anticoagulant management is an important component of ... Endocrine System. Diabetes. Patients with diabetes are at higher risk for perioperative complications. In a study of 1042 ...
The Conduction System of the Heart. Teach and learn all about the conduction system of the heart in fully interactive 3D with ... Primary Organs and Hormones of the Endocrine System. A 3D virtual tour of the primary organs of the endocrine system and their ...
Congestive heart failure, valvular heart disease, arrhythmia, and conduction system disease. Patients with congestive heart ... Cardiovascular System. Ischemic heart disease. Patients with known coronary artery disease undergoing surgery should be ... Heart valve prostheses. For those patients with heart valve prostheses, anticoagulant management is an important component of ... Endocrine System. Diabetes. Patients with diabetes are at higher risk for perioperative complications. In a study of 1042 ...
... the first 3-dimensional representations of the cardiac conduction system within the intact human heart. We show that ... High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling.. Login ... High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling.. en. ... By showing the precise 3-dimensional relationships between the cardiac conduction system and surrounding structures, we provide ...
Conduction System of the Heart Anatomy Coloring Page- LABELED- Digital Download Cardio Diagram Anatomy Worksheet Student Study ...
... caused by heart attack (myocardial infarction), cardiac arrest, open-heart surgery, trauma, septic shock, kidney failure, and ... decompensated heart failure. Side effects of dopamine include cardiovascular effects (chest pain [angina pectoris], high or low ... Abnormality in the heart conduction system. *Abnormal ECG readings. *Palpitations. *Irregular and rapid contraction of atria ( ... What Heart Rate Is a Heart Attack?. While no one particular heart rate qualifies as a heart attack, a rapid heart rate outside ...
Heart Conduction System / physiopathology* * Humans * Models, Theoretical * Neurons / physiology* * Polymorphism, Single ...
... you will discover diseases that affect the cardiovascular system, the treatment of these diseases, and the effects on the ... The cardiovascular system is comprised of the heart and blood vessels and is responsible for the transport of oxygen and ... nutrients to organ systems of the body. The heart is a cone-shaped organ made up of four chambers. The right side of the heart ... to link information with application and system log data. Pearson uses this information for system administration and to ...
Anatomy figure: 20:06-02 at Human Anatomy Online, SUNY Downstate Medical Center - "The conduction system of the heart." ... it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of the interatrial ... The cardiac conduction system (and AV node part of it) coordinates myocyte mechanical activity. A wave of excitation spreads ... This property is important because loss of the conduction system before the AV node should still result in pacing of the ...
... cardiac conduction-system disease, and adult-onset limb-girdle muscular dystrophy (FDC, conduction disease, and myopathy [FDC- ... show enlargement of all four chambers of the heart and develop symptoms of congestive heart failure. Inherited cardiomyopathies ... "Linkage of familial dilated cardiomyopathy with conduction defect and muscular dystrophy to chromosome 6q23." Am J Hum Genet 61 ... "Linkage of familial dilated cardiomyopathy with conduction defect and muscular dystrophy to chromosome 6q23." Am J Hum Genet, ...
... or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly. ... or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly. ... An arrhythmia is a disorder of the heart rate (pulse) ... An arrhythmia is a disorder of the heart rate (pulse) ... Arrhythmias are caused by problems with the hearts electrical conduction system. *Abnormal extra signals may occur. ...
Long QT syndrome affects the hearts rhythm. If it is left untreated, the condition can be fatal. Learn more about the symptoms ... Behind the pumping action of the heart is an electrical conduction system. Specialized muscle cells in the hearts walls send ... Long QT syndrome (LQTS) is a problem with the hearts electrical conduction system that may prevent the heart from pumping ... having a heart condition, such as congenital heart defects and cardiomyopathy. *taking certain medications that can affect the ...
Source for information on The Cardiovascular System: UXL Complete Health Resource dictionary. ... The Cardiovascular System The cardiovascular system and the lymphatic system form what is collectively called the circulatory ... This system, called the intrinsic conduction system, is located within the heart tissue. Nerve impulses sent out through the ... Congenital heart disease. Congenital heart disease (sometimes called congenital heart defect) is any defect in the heart or its ...
... stimulus-conduction systems in heart; electrocardiogram; hypertensive heart disease. ... MED202 - Cardiovascular System (6 + 2) 0 Lymphoid system; thymus; heart and pericardium anatomy; mediastinum; diaphragm; great ... valvular heart diseases; congenital heart diseases; arrhythmias; ischemic heart diseases; heart failure; cardiomyopathies, ... cardiovascular system examination, neurological system examination, endocrine system examination, gastrointestinal system ...
Anatomical study of the cardiac conduction system in swine hearts. Hanami M, Anetai H, Anetai S, Kojima R, Tokita K. Hanami M, ...
Electrical conduction system. of the heart. Heart block: AV block (First degree, Second degree, Third degree) - Bundle branch ... nervous system: Eye - Brain endocrine system: Thyroid (Papillary, Follicular, Medullary, Anaplastic) - Adrenal tumor ( ... Circulatory system pathology (I, 390-459). Hypertension. Hypertensive heart disease - Hypertensive nephropathy - Secondary ... Other heart conditions. Heart failure - Cardiovascular disease - Cardiomegaly - Ventricular hypertrophy (Left, Right). ...
A left bundle branch block is a type of disruption of the hearts electrical impulses that can signal an underlying heart ... It results from a problem with the electrical conduction system that enables the heart to beat. It may cause no symptoms, but ... a pacemaker may be an option for people who develop a heart block while having a heart attack. This can help regulate the heart ... www.heart.org/en/health-topics/heart-attack/diagnosing-a-heart-attack/electrocardiogram-ecg-or-ekg. ...
... in the heart. Many are minor and not a health threat, but some can indicate a more serious problem. ... The conduction system of the heart is similar to the wiring of a light switch to a light:. *The signal for the heart to beat ... A unique electrical conduction system in the heart causes it to beat in its regular rhythm. ... Whats a Normal Heart Rate?. Heart rate is measured by counting the number of beats per minute. Someones normal heart rate ...
2. Electrical conduction system of the heart​The normal intrinsic electrical conduction of the heart a... Read more ... The SKIP (System of Kanji Indexing by Patterns) system for ordering kanji was developed by Jack Halpern (Kanji Dictionary ... We recently switched to a new login system. Please enter the email you registered with and follow the instructions. ...
One of the ways in which the heart can malfunction involves the electrical conduction system. Some of the more commonly seen ... The cardiovascular system is one of the key players in the health and wellness of our patients. When the heart is not ... Cardioversion is one of the treatment options and comes in several forms that "convert" the heart rhythm to one that is more ... Adenosine can be a scary drug to administer as it blocks the atrial-ventricular communication, causing the heart to stop ...
  • Abnormalities seen in BMP and Alk3 are associated with some cardiovascular diseases like Ebstein's anomaly and AV conduction disease. (wikipedia.org)
  • The cardiovascular risks of radiotherapy include coronary artery disease, valvular heart disease, pericardial disease, conduction system abnormalities, and myocardial fibrosis. (ajmc.com)
  • I am a cardiologist specializing in the care of individuals with cardiac arrhythmias (irregular heartbeats) and conduction system abnormalities (a problem with the electrical system that makes your heart beat), with a focus on atrial fibrillation . (mskcc.org)
  • The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node - the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the body's circulatory system. (wikipedia.org)
  • A pacemaker is a small, battery-powered device that prevents the heart from beating too slowly. (mayoclinic.org)
  • For example, if the heart beats too slowly, the pacemaker sends electrical signals to correct the beat. (mayoclinic.org)
  • A pacemaker is a device used to control an irregular heart rhythm. (mayoclinic.org)
  • Permanent pacemaker , a device that senses when your heart is beating too slowly. (medlineplus.gov)
  • For example, a pacemaker may be an option for people who develop a heart block while having a heart attack. (medicalnewstoday.com)
  • Hyman's invented and named the very first "artificial pacemaker": it was powered by a spring-wound hand-cranked but did not become accepted as a means of re-starting a stopped heart. (understandinganimalresearch.org.uk)
  • He developed an external tabletop pacemaker that was successfully applied to the treatment of heart block. (understandinganimalresearch.org.uk)
  • It is the natural pacemaker of the heart. (microbenotes.com)
  • The impulse conducted by the pacemaker cells is transmitted to the perinodal cells from which it is transmitted over other structures of the conduction system. (microbenotes.com)
  • The activity of the SA node is regulated by the sympathetic and the parasympathetic nervous system, but the impulse is produced by the pacemaker cells. (microbenotes.com)
  • Hence, the AV node is considered the second pacemaker of the human heart. (microbenotes.com)
  • The SA node (also known as the sinus node) is your heart's natural pacemaker and generates the electrical current that makes your heart muscle squeeze. (clevelandclinic.org)
  • Special pacemaker cells in a part of the atria called the SA node (sinoatrial node) send out regular electrical signals to your heart muscle to make it contract. (merckmanuals.com)
  • The conduction system carries the pacemaker signals to the rest of your heart. (merckmanuals.com)
  • If they go faster than your normal pacemaker cells, they can take over your heart and make it beat very fast. (merckmanuals.com)
  • A pacemaker works only when it needs to signal the heart to beat, when it senses that the heartbeat is too slow or irregular. (timesofisrael.com)
  • There are special pacemaker cells in a part of your heart called the SA node. (msdmanuals.com)
  • In order to maximize efficiency of contractions and cardiac output, the conduction system of the heart has: Substantial atrial to ventricular delay. (wikipedia.org)
  • This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. (wikipedia.org)
  • Adenosine can be a scary drug to administer as it blocks the atrial-ventricular communication, causing the heart to stop briefly. (bellaonline.com)
  • AV node can spontaneously produce an electric impulse at the rate of 40 to 60 times per minute and transmit it down to compensate for the loss of impulse during the atrial conduction and contraction and to run the cardiac cycle if there is a disturbance in the SA node. (microbenotes.com)
  • Atrial Premature Beats An atrial premature beat is an extra heartbeat caused by electrical activation of the atria (upper chambers of the heart) from an abnormal site before a normal heartbeat would occur. (merckmanuals.com)
  • Like most congenital heart defects, it is unclear exactly why certain babies are born with atrial septal defects . (wikidoc.org)
  • It also affects the conduction system, leading to bradyarrhythmia and atrial or ventricular tachycardia. (medpagetoday.com)
  • BrS is associated with an increased risk of syncope, palpitations, chest pain, convulsions, difficulty in breathing (nocturnal agonal breathing) and/or Sudden Cardiac Death (SCD) secondary to PVT/VF, unexplained cardiac arrest or documented PVT/VF or Paroxysmal atrial fibrillation (AF) in the absence of apparent macroscopic or structural heart disease, electrolyte disturbance, use of certain medications or coronary heart disease and fever. (bvsalud.org)
  • this is a novel mutation, in that it is associated with a gain-of-function mechanism and is associated with paroxysmal atrial fibrillation and no structural heart disease. (medscape.com)
  • In this chapter, you will discover diseases that affect the cardiovascular system, the treatment of these diseases, and the effects on the client's general health status. (informit.com)
  • The cardiovascular system is comprised of the heart and blood vessels and is responsible for the transport of oxygen and nutrients to organ systems of the body. (informit.com)
  • The cardiovascular system and the lymphatic system form what is collectively called the circulatory system . (encyclopedia.com)
  • Cardiovascular comes from the Greek word cardia , meaning "heart," and the Latin vasculum , meaning "small vessel. (encyclopedia.com)
  • The basic components of the cardiovascular system are the heart, the blood vessels, and the blood. (encyclopedia.com)
  • The cardiovascular system is one of the key players in the health and wellness of our patients. (bellaonline.com)
  • By 2005, the total number of cardiovascular disease (CVD) deaths (mainly coronary heart disease, stroke, and rheumatic heart disease) had increased globally to 17.5 million from 14.4 million in 1990. (health.am)
  • When the body changes position, a variety of actions occur involving all parts of the cardiovascular system as well as the autonomic nervous system that helps regulate their function. (medicinenet.com)
  • The heart and blood vessels are part of your cardiovascular system. (merckmanuals.com)
  • Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. (medlineplus.gov)
  • The MGH Cardio-Oncology Program introduced in 2011 is a joint initiative between the Heart and Cancer Centers at Massachusetts General Hospital that provides comprehensive cardiovascular care to cancer patients, with the goal of improving short- and long-term outcomes ( Figure ). (ajmc.com)
  • Critically, what one also gleans from the autopsy report is that the 37-year-old female decedent was free of any serious, chronic comorbidity-certainly in all the major organ systems examined, grossly, including the cardiovascular system. (andrewbostom.org)
  • are part of your cardiovascular system. (msdmanuals.com)
  • Therefore, this work described an educational design of multiple practice stations in order to teach morphology of the cardiovascular system in the undergraduate medical education. (bvsalud.org)
  • This innovative experience integrated and energized the three areas of morphological sciences, resignifying the teaching and learning of cardiovascular system morphology. (bvsalud.org)
  • Normal conduction system of the heart and EKG tracing compared to multiple abnormal EKG tracings. (medivisuals1.com)
  • It causes an abnormal heart rhythm and is common in those who have experienced heart damage. (medicalnewstoday.com)
  • But sometimes the electrical signals are abnormal, and the heart can start beating in a different rhythm - this is an arrhythmia (also called dysrhythmia). (kidshealth.org)
  • But trained athletes have a lower resting heart rate, so a slow heart rate in them isn't considered abnormal if it causes no symptoms. (kidshealth.org)
  • it is an abnormal change in blood pressure and heart rate associated with an illness. (medicinenet.com)
  • Overview of Abnormal Heart Rhythms Your heart is a muscle that pumps blood through your body. (merckmanuals.com)
  • Abnormal heart rhythms and inadequate blood flow to the heart muscle may occur only briefly or unpredictably. (merckmanuals.com)
  • however, sometimes abnormal heart rhythms. (merckmanuals.com)
  • They include a previous heart attack (myocardial infarction), an abnormal heart rhythm (arrhythmia), an inadequate supply of blood and oxygen to the heart (ischemia), and excessive thickening (hypertrophy) of the heart's muscular walls. (merckmanuals.com)
  • If the rhythm is abnormal (too fast, too slow, or irregular), the ECG may also indicate where in the heart the abnormal rhythm starts. (merckmanuals.com)
  • Extra impulse-conducting tissue in the heart that creates abnormal impulse-conducting connections between HEART ATRIA and HEART VENTRICLES. (bvsalud.org)
  • Cardiac arrhythmias and conduction disturbances are accompanied by structural remodelling of the specialised cardiomyocytes known collectively as the cardiac conduction system. (auckland.ac.nz)
  • Arrhythmias are caused by problems with the heart's electrical conduction system. (medlineplus.gov)
  • Long QT syndrome (LQTS) is a problem with the heart's electrical conduction system that may prevent the heart from pumping properly, leading to palpitations, blackouts, seizures, and life threatening arrhythmias. (medicalnewstoday.com)
  • Arrhythmias make the heart beat less effectively, interrupting blood flow to the brain and the rest of the body. (kidshealth.org)
  • Management of preexisting conditions such as hypertension, coronary artery disease, congestive heart failure, heart valve disease, and arrhythmias in cancer patients requires an approach customized to their overall care. (ajmc.com)
  • These signals are generated rhythmically, which results in the coordinated rhythmic contraction and relaxation of the heart. (wikipedia.org)
  • Ventricular contraction begins at the apex of the heart, progressing upwards to eject blood into the great arteries. (wikipedia.org)
  • In the treatment of hemodynamic imbalance, dopamine stimulates cardiac muscle contraction and increases the heart rate, which results in improved cardiac output. (medicinenet.com)
  • Systolic pressure is the pressure during the contraction phase of the heart and is evaluated as the top number of the blood pressure reading. (informit.com)
  • Contraction of heart muscle cells requires depolarization and repolarization of their cell membranes. (wikipedia.org)
  • It is the ordered, rhythmic stimulation of the myocardium during the cardiac cycle that allows efficient contraction of the heart, thereby allowing blood to be pumped throughout the body. (understandinganimalresearch.org.uk)
  • The flow of blood through the heart is controlled by the opening and closing of valves and the contraction and relaxation of the myocardium. (health.am)
  • Heart valves are controlled by pressure changes within each chamber and contraction and relaxation are controlled by the heart's conduction system. (health.am)
  • Phenotypically, patients with familial dilated cardiomyopathy (FDC) show enlargement of all four chambers of the heart and develop symptoms of congestive heart failure. (duke.edu)
  • However, overhydration can exacerbate congestive heart failure . (medicinenet.com)
  • 1,2 Similarly, there are increased risks of congestive heart failure in adults treated with anthracycline-based chemotherapy regimens, which in current practice includes patients with breast cancer, leukemia, lymphoma, sarcoma, and other cancer types. (ajmc.com)
  • Heart Rhythm. (jefferson.edu)
  • AV conduction during normal cardiac rhythm occurs through two different pathways: the first "pathway" has a slow conduction velocity but shorter refractory period the second "pathway" has a faster conduction velocity but longer refractory period. (wikipedia.org)
  • An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. (medlineplus.gov)
  • An ECG can record the heart's rhythm and indicate the type of heart block a person has. (medicalnewstoday.com)
  • The ECG produces a visual image of the heart rhythm. (medicalnewstoday.com)
  • It can record the heart rhythm for up to 3 years . (medicalnewstoday.com)
  • This can help regulate the heart rhythm, as a bundle branch block can cause bradycardia and the heart to become fragile. (medicalnewstoday.com)
  • The heart normally beats in a regular rhythm, but an arrhythmia (ay-RITH-mee-uh) can make it beat too slowly, too quickly, or irregularly. (kidshealth.org)
  • A unique electrical conduction system in the heart causes it to beat in its regular rhythm. (kidshealth.org)
  • Cardioversion is one of the treatment options and comes in several forms that "convert" the heart rhythm to one that is more optimal for health. (bellaonline.com)
  • The normal sequence of electrical activation of the chambers of the heart is called sinus rhythm. (health.am)
  • Sinus bradycardia is a heart rhythm where your heart beats slower than expected (under 60 beats per minute for adults) but otherwise works normally. (clevelandclinic.org)
  • Sinus bradycardia is a heart rhythm that's slower than expected (fewer than 60 beats per minute in an adult) but is otherwise normal. (clevelandclinic.org)
  • Sinus bradycardia means your heart is beating slowly but still using a sinus rhythm. (clevelandclinic.org)
  • During sinus rhythm, every heartbeat you have starts in the sinoatrial (SA) node, a cluster of electrically active cells near the top of your heart. (clevelandclinic.org)
  • in a row, and then your heart returns to a normal rate and rhythm. (merckmanuals.com)
  • The prime minister came to Sheba Medical Center last week because he had a fainting episode… And since he had a conduction disorder that we've know about many years, we decided to perform an electrophysiological study, which is a kind of catheterization that assesses the conduction system," Prof. Roy Beinart, director of the Davidai Center for Rhythm Disturbances and Pacing at Sheba Medical Center, said Sunday. (timesofisrael.com)
  • The study shows "that conduction system pacing is a viable first-line option for patients needing cardiac resynchronization therapy," said Vijayaraman, who also presented the findings earlier this year at Heart Rhythm 2023. (tctmd.com)
  • back in April, the European Heart Rhythm Association released a consensus statement to provide guidance to physicians on how to do it. (tctmd.com)
  • In fact, Vijayaraman presented the results of an observational study with about 1,800 patients at Heart Rhythm 2023 demonstrating the benefits of LBBAP over biventricular pacing. (tctmd.com)
  • There were no significant differences between the groups in the percentage of patients free of arrhythmic death or the number of hospitalizations secondary to rhythm and/or conduction disturbances ( P = .053). (medpagetoday.com)
  • he has served on the Ethics and Disciplinary Committee of the American College of Cardiology, and currently serves as Chair of the Health Policy and Regulatory Affairs Committee at the Heart Rhythm Society - where he leads interactions between medical experts and the FDA and other regulatory agencies. (weillcornell.org)
  • John Ho , MD, a cardiologist at Cooper Clinic, explains it's useful for assessing not only your heart health, but also your fitness level and autonomic tone-the ability of your nervous system to respond to stress by making appropriate adjustments in bodily functions, including heart rate and rhythm. (cooperaerobics.com)
  • He was found unconscious hunched by the bedside at 8:00 AM. Rushed to the emergency department, his electrocardiogram (ECG) showed ventricular fibrillation (a chaotic and lethal heart rhythm if not corrected), and despite 2-hours of cardiopulmonary resuscitation efforts, he could not be resuscitated. (andrewbostom.org)
  • Heart rhythm : the official journal of the Heart Rhythm Society 2007 Feb 4 (2): 170-4. (cdc.gov)
  • Heart rhythm : the official journal of the Heart Rhythm Society 2012 Mar 9 (3): 399-404. (cdc.gov)
  • Electrical signals start in a group of cells at the top of the heart called the sinus node. (mayoclinic.org)
  • The artery supplying the sinus node branches from the right coronary artery in 55-60% of hearts or the left circumflex artery in 40-45% of hearts. (medscape.com)
  • The cardiac conduction system (and AV node part of it) coordinates myocyte mechanical activity. (wikipedia.org)
  • A wave of excitation spreads out from the sinoatrial node through the atria along specialized conduction channels. (wikipedia.org)
  • An important property that is unique to the AV node is decremental conduction, in which the more frequently the node is stimulated the slower it conducts. (wikipedia.org)
  • This property is important because loss of the conduction system before the AV node should still result in pacing of the ventricles by the slower pacemaking ability of the AV node. (wikipedia.org)
  • Inherited cardiomyopathies may also be accompanied by cardiac conduction-system defects that affect the atrioventricular node, resulting in bradycardia. (duke.edu)
  • The electrical impulse that signals your heart to contract begins in an area of the heart called the sinoatrial node (also called the sinus node or SA node). (medlineplus.gov)
  • The signal leaves the SA node and travels through the heart along a set electrical pathway. (medlineplus.gov)
  • The sinus node controls how quickly or slowly the heart beats. (kidshealth.org)
  • The sinus node normally speeds up the heart rate in response to things like exercise, emotions, and stress, and slows the heart rate during sleep. (kidshealth.org)
  • Supraventricular tachycardia (SVT) is characterized by bursts of fast heartbeats that start in the upper chambers of the heart, closer to the sinus node. (kidshealth.org)
  • The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to, and stimulate, the cardiac muscle (myocardium). (understandinganimalresearch.org.uk)
  • The heart's "spark plug" is an area of specialized heart tissue called the sinoatrial node (SA node), which is located in the right atrium. (health.am)
  • The impulse then travels into another area of specialized heart tissue called the atrioventricular node (AV node), which is located between the atria and the ventricles. (health.am)
  • The major components of the human heart conduction system include the sinoatrial node, atrioventricular node, Bundle of His, and Purkinje fibers. (microbenotes.com)
  • Bundle of His, also known as the atrioventricular (AV) bundle , is a collection of special myocytes that conducts the cardiac impulse from the AV node to the Purkinje Fiber for conduction across the ventricles. (microbenotes.com)
  • The conduction system includes a gateway called the AV node. (msdmanuals.com)
  • The AV node controls how signals pass from the upper chambers of your heart (atria) to the lower chambers (ventricles). (msdmanuals.com)
  • The heart's conduction system also is called the heart's electrical signaling system. (mayoclinic.org)
  • An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart. (jefferson.edu)
  • It represents the time it takes the ventricles or lower heart chambers to relax or the time it takes for the heart's electrical system to send an impulse through the ventricles. (medicalnewstoday.com)
  • An electrical impulse travels through the heart and initiates contractions of the chambers. (health.am)
  • Also called the cardiac conduction system or the intrinsic conduction system of the heart or electrical conduction system of the heart , is a group of specialized cells and tissues that spontaneously generate and transmit the electrical impulse across the heart for regulation of the pumping action of the heart. (microbenotes.com)
  • This conduction system of the human heart is intrinsic i.e. the myocytes produce the impulse themselves without the involvement of neurons. (microbenotes.com)
  • Purkinje fiber is the network of specialized impulse-conducting myocytes that transmit the cardiac electric impulse to every part of the heart ventricles. (microbenotes.com)
  • This rate of the generation and transmission of the cardiac impulse is called cardiac conduction. (microbenotes.com)
  • This impulse activates the upper chambers of the heart (atria). (merckmanuals.com)
  • Autopsy examination revealed diffuse inflammation within his heart muscle (myocardium), and particularly in the hearts unique cardiac impulse conduction system (around the sinoatrial and atrioventricular nodes). (andrewbostom.org)
  • Ventricular septal defect is one of the most common congenital (present from birth) heart defects. (wikidoc.org)
  • This defect often occurs along with other congenital heart defects. (wikidoc.org)
  • In adults, ventricular septal defects are a rare but serious complication of heart attacks . (wikidoc.org)
  • To treat these conduction defects, pacing device implants (PDIs) or implantable cardioverter-defibrillators (ICDs) may be placed. (medpagetoday.com)
  • It's for people who have heart failure and a slow heartbeat. (mayoclinic.org)
  • The heart's electrical system typically controls the heartbeat. (mayoclinic.org)
  • Series of events that occur in the heart during one complete heartbeat. (encyclopedia.com)
  • A person should also consider seeing a doctor if they have an irregular heartbeat, high blood pressure , or a family history of heart disease. (medicalnewstoday.com)
  • Heart palpitations (the unpleasant feeling of your own heartbeat without feeling for your pulse). (clevelandclinic.org)
  • In ventricular tachycardia, a very fast heartbeat starts in the ventricles of your heart. (merckmanuals.com)
  • A change in the heart's normal electrical conduction system can result in an arrhythmia, or irregular heartbeat. (medlineplus.gov)
  • These electrodes measure the magnitude and direction of electrical currents in the heart during each heartbeat. (merckmanuals.com)
  • An electrocardiogram (ECG) represents the electrical current moving through the heart during a heartbeat. (merckmanuals.com)
  • When you put your head on someone's chest and listen to their heartbeat, you're hearing the sound of the heart valves opening and closing. (msdmanuals.com)
  • Electrocardiography, Heart, Heart Conduction System. (bvsalud.org)
  • The system can be compared to a large muscular pump (the heart) that sends a fluid (blood) through a series of large and small tubes (blood vessels). (encyclopedia.com)
  • Almost immediately, the sympathetic system is stimulated, causing the heart rate to increase, the heart muscle to contract or squeeze more forcefully, and blood vessels to constrict or narrow. (medicinenet.com)
  • Your heart pumps blood through your blood vessels Blood carries oxygen and nutrients. (merckmanuals.com)
  • or that the heart is not receiving enough oxygen due to a blockage in one of the blood vessels that supply the heart (the coronary arteries). (merckmanuals.com)
  • Four anatomy stations and four embryology and histology stations of heart and blood vessels were drawn up. (bvsalud.org)
  • Scholars@Duke publication: Linkage of familial dilated cardiomyopathy with conduction defect and muscular dystrophy to chromosome 6q23. (duke.edu)
  • This type sends electrical signals to the upper and lower right heart chambers. (mayoclinic.org)
  • The device stimulates both lower heart chambers. (mayoclinic.org)
  • Electrical signals, called impulses, move through the heart chambers. (mayoclinic.org)
  • The wires are placed in one or more chambers of the heart. (mayoclinic.org)
  • The heart is a cone-shaped organ made up of four chambers. (informit.com)
  • Upper chambers of the heart that receive blood from the veins. (encyclopedia.com)
  • Period of relaxation and expansion of the heart when its chambers fill with blood. (encyclopedia.com)
  • It causes the heart chambers to enlarge so they can no longer contract effectively. (medicalnewstoday.com)
  • When the heart beats too fast, its chambers can't fill with enough blood. (kidshealth.org)
  • All four chambers of the heart responded. (understandinganimalresearch.org.uk)
  • The left ventricle, the largest and most muscular of the four chambers, is the main pumping chamber of the heart. (health.am)
  • Your heart has four chambers. (merckmanuals.com)
  • The atria are the two upper chambers in your heart. (merckmanuals.com)
  • The ventricles are the two lower chambers in your heart. (merckmanuals.com)
  • Ventricular Fibrillation Ventricular fibrillation is a potentially fatal, uncoordinated series of very rapid, ineffective contractions of the ventricles (lower chambers of the heart) caused by many chaotic electrical. (merckmanuals.com)
  • Next, the electrical current flows down to the lower chambers of the heart (ventricles). (merckmanuals.com)
  • What are the heart chambers? (msdmanuals.com)
  • The heart has 4 compartments (chambers), two on the right and two on the left. (msdmanuals.com)
  • The chambers of your heart relax, fill with blood, and then contract to pump the blood out. (msdmanuals.com)
  • An arrhythmia can be harmless, a sign of other heart problems, or an immediate danger to your health. (medlineplus.gov)
  • Sometimes, better treatment for your angina or heart failure will lower your chance of having an arrhythmia. (medlineplus.gov)
  • In these cases, the arrhythmia is only found during a physical exam or a heart function test. (kidshealth.org)
  • Cardiac arrhythmia: Heart p. (adam.com)
  • Christopher F. Liu, MD, FACC, FHRS is Director of Complex Arrhythmia Ablation and Structural Heart Electrophysiology, and Assistant Director of the Cardiac Electrophysiology Laboratory, at New York-Presbyterian Hospital / Weill Cornell Medical Center. (weillcornell.org)
  • This tragic case was analyzed in the October 2021 issue of the Journal of Korean Medical Sciences , and the authors concluded the recruit's sudden cardiac death was caused by a covid-19 vaccine-induced myocarditis (heart inflammation), which triggered a paroxysmal, fatal arrhythmia. (andrewbostom.org)
  • Fire fighter suffers heart arrhythmia and dies at wildland fire - Washington. (cdc.gov)
  • Pacemakers are prescribed when the electrical conduction system of a person's heart causes slow or irregular heartbeats, or if a person has heart failure. (timesofisrael.com)
  • Dyssynchronous Heart Failure: A Clinical Review. (jefferson.edu)
  • You have heart failure. (mayoclinic.org)
  • Hemodynamic imbalance can be caused by conditions such as heart attack ( myocardial infarction ), cardiac arrest , open- heart surgery, trauma , septic shock , kidney failure , and decompensated heart failure . (medicinenet.com)
  • For patients with heart failure, a reduced ejection fraction, and an indication for cardiac resynchronization therapy (CRT), using His-Purkinje conduction system pacing (HPCSP) is safe and feasible and provides a bigger boost to LV function than does using biventricular pacing, according to the pilot HOT-CRT study. (tctmd.com)
  • 31% women) who had heart failure with reduced ejection fraction and an indication for CRT. (tctmd.com)
  • Whether this benefit translates into reduction of heart failure hospitalization or mortality needs to be evaluated in large randomized clinical trials. (tctmd.com)
  • However, if the hole is large, the baby often has symptoms related to heart failure. (wikidoc.org)
  • If the hole is large, too much blood will be pumped to the lungs, leading to heart failure. (wikidoc.org)
  • However, the baby should be closely monitored by a health care provider to make sure that the hole eventually closes properly and signs of heart failure do not occur. (wikidoc.org)
  • Babies with a large VSD who have symptoms related to heart failure may need medicine to control the symptoms and surgery to close the hole. (wikidoc.org)
  • The accumulation of amyloid leads to restrictive cardiomyopathy and heart failure. (medpagetoday.com)
  • Serious' effects are those that evoke failure in a biological system and can lead to morbidity or mortality (e.g., acute respiratory distress or death). (cdc.gov)
  • Eosinophilic infiltration affects the cardiac electrical conduction system in addition to causing heart failure . (medscape.com)
  • Eosinophilic myocarditis can also present as acute heart failure. (medscape.com)
  • Additionally, in patients with ATTRv-CM who had a valine to methionine substitution (mutation) and a conduction disturbance, it was found that the BNP levels ( P = .006), IVS thickness ( P = .003), and bifascicular block ( P = .044) were associated with future PDI. (medpagetoday.com)
  • His son presented with cardiac conduction disturbance with no congenital heart or skeletal defect. (medscape.com)
  • Usually, an ECG is obtained if a heart disorder is suspected. (merckmanuals.com)
  • It is sometimes also obtained as part of a routine physical examination for middle-aged and older people, even if they have no evidence of a heart disorder. (merckmanuals.com)
  • It can be used as a basis of comparison with later ECGs if a heart disorder develops. (merckmanuals.com)
  • In this case, the heart doesn't skip a beat - an extra beat comes sooner than normal. (kidshealth.org)
  • Atrioventricular conduction disease (AV block) describes impairment of the electrical continuity between the atria and ventricles. (wikipedia.org)
  • It is located near the center of the heart at the lower right end of the interatrial septum in close proximity to the ventricles. (microbenotes.com)
  • Ventricular septal defect describes one or more holes in the wall that separates the right and left ventricles of the heart. (wikidoc.org)
  • Before a baby is born, the right and left ventricles of its heart are not separate. (wikidoc.org)
  • This 3D medical animation begins with an anterior view of the heart which dissolves away to show the ventricles, atria and valves. (smartimagebase.com)
  • Just like the heart, the stomach is controlled by an electrical conduction system that drives contractions. (cambridgeconsultants.com)
  • Blood that has traveled through the body returns to the heart and enters the right atrium. (health.am)
  • The vena cava is the major vein that returns blood to the right atrium of the heart. (health.am)
  • The conduction system consists of specialized heart muscle cells, situated within the myocardium. (wikipedia.org)
  • The heart wall consists of the epicardium (inner layer), the myocardium (middle layer comprised of cardiac muscle tissue), and the endocardium (lining of the myocardium that covers the heart valves). (health.am)
  • This is especially true for people who're very physically active and have sinus bradycardia because their hearts are more efficient. (clevelandclinic.org)
  • The third order of electrical influence of the heart is derived from the vagus nerve as the other peripheral organs form. (wikipedia.org)
  • Different nerve messages signal your heart to beat slower or faster. (medlineplus.gov)
  • This nerve, which has a direct connection to your brain, is part of your autonomic nervous system. (clevelandclinic.org)
  • The better your vagus nerve works, the lower your resting heart rate. (clevelandclinic.org)
  • Vijayaraman explained that conduction system pacing provides a greater improvement in LVEF because it's correcting the underlying electrical abnormality by using the heart's natural conduction system, whereas biventricular pacing is an artificial solution to the problem. (tctmd.com)
  • Holt-Oram syndrome (HOS) (OMIM 142900) is a heart-upper limb malformation complex with an autosomal dominant inheritance and near-complete penetrance but variable expression. (medscape.com)
  • A newly identified missense mutation in CLCA2 is associated with autosomal dominant cardiac conduction block. (cdc.gov)
  • The pericardial cavity, the potential space between the pericardium and the heart, contains the watery pericardial fluid. (health.am)
  • This includes inflammation of your heart's inner lining ( endocarditis ), your heart muscle itself (myocarditis) or the pericardial sac that holds and cushions your heart ( pericarditis ). (clevelandclinic.org)
  • Electrical signals travel in new or different pathways through the heart. (medlineplus.gov)
  • See also Heart Anatomy, Aortic Valve Anatomy, Mitral Valve Anatomy, Pulmonic Valve Anatomy, Tricuspid Valve Anatomy, Anatomy of the Nerves of the Heart, and Anatomy of the Autonomic Nervous System. (medscape.com)
  • The outcomes of the study were the parameters associated with future PDI in patients with ATTRwt-CM and ATTRv-CM, the incidence of unplanned PDI due to ATTRwt-CM and ATTRv-CM associated conduction disturbances, and the incidence of appropriate device therapy in subgroups with implantation of an ICD. (medpagetoday.com)
  • The investigators evaluated the incidence of PDI associated with various conduction disturbances. (medpagetoday.com)
  • These gap junctions can close to isolate damaged or dying tissue, as in a myocardial infarction (heart attack). (wikipedia.org)
  • The autonomic nervous system makes changes in blood pressure and heart rate to allow the body to provide adequate blood supply to the brain when the body changes position. (medicinenet.com)
  • The autonomic nervous system can be considered to 'run in the background' of the body, regulating body processes that we take for granted. (medicinenet.com)
  • Heart Conduction System" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (jefferson.edu)
  • An electrocardiogram (EKG) is a device that maps the electrical signals that move through the heart as it beats and relaxes. (medicalnewstoday.com)
  • The ability to record the human (or animal) heart-beat on an electrocardiogram (ECG) developed rapidly and by 1942 the 12 lead electrocardiogram as we know it today had emerged. (understandinganimalresearch.org.uk)
  • Electrocardiogram (EKG): Before, during and after the stress test, an EKG is taken to assess the heart's conduction system and function. (cooperaerobics.com)
  • From there, the signal travels through the heart ("the light") to tell it to pump. (kidshealth.org)
  • There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. (wikipedia.org)
  • The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below). (medscape.com)
  • Your heart's conduction system has tiny strips of tissue sort of like electrical wires. (merckmanuals.com)
  • In rare cases , people may have congenital heart block , meaning they are born with this condition. (medicalnewstoday.com)
  • There is evidence to suggest that families with a history of genetic problems and other congenital heart disease may be at an increased risk for carrying and expressing the trait. (wikidoc.org)
  • Ventricular septal defect is the most common congenital heart defect. (sbir.gov)
  • [ 10 ] The grandfather presented with phocomelia of arms, with three digits on each hand, congenital heart defect, and narrow shoulders. (medscape.com)
  • Not getting enough of certain electrolytes like calcium, magnesium and potassium can impact your heart rate. (clevelandclinic.org)
  • Calcium channel blockers, NOS1AP, and heart-rate-corrected QT prolongation. (cdc.gov)
  • To help this happen, your heart has an electrical system that makes sure it contracts (squeezes) in an orderly way. (medlineplus.gov)
  • A special test, called an electrophysiology study (EPS), is sometimes done to take a closer look at the heart's electrical system. (medlineplus.gov)
  • What is the heart's electrical system? (msdmanuals.com)
  • Once again, an autopsy showed extensive inflammation of the heart, "which led to the diagnosis of…fulminant myocarditis," resulting in fatal arrhythmogenic SCD. (andrewbostom.org)
  • Specialized muscle cells in the heart's walls send signals to the rest of the heart to ensure that the heart beats at a steady, consistent rate. (medicalnewstoday.com)
  • Heart rate is measured by counting the number of beats per minute. (kidshealth.org)
  • An older child or adult with a slow heart rate, for example, might have symptoms when the heart rate drops below 50 beats per minute. (kidshealth.org)
  • Occasional premature beats are common and considered normal, but sometimes they can be a sign of an underlying medical problem or heart condition. (kidshealth.org)
  • It occurs each time the heart beats, usually about 60 to 80 times every minute. (health.am)
  • Many people may not even know their heart rate is under 60 beats per minute unless they have a reason to check their pulse. (clevelandclinic.org)
  • your heart beats faster, your palms get sweaty, your eyes dilate, and your hair stands on end. (medicinenet.com)
  • Your heart rate is how fast your heart beats. (merckmanuals.com)
  • As the heart beats, the action of the valves opening and closing can be clearly seen. (smartimagebase.com)
  • Resting heart rate: The number of times your heart beats per minute. (cooperaerobics.com)
  • Every minute, your heart beats about 70 times and pumps about 1 gallon (4 liters) of blood. (msdmanuals.com)
  • Your heart beats faster and pumps harder during exercise, when your body needs more oxygen. (msdmanuals.com)
  • When you check your pulse, you're measuring your heart rate, or the number of beats per minute. (msdmanuals.com)
  • Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow. (wikipedia.org)
  • In the U.S., 1 in every 4 deaths is caused by heart disease. (medicinenet.com)
  • Heart disease is one possible cause. (medicalnewstoday.com)
  • The Centers for Disease Control and Prevention (CDC) recommend exercising, eating a balanced diet, and avoiding smoking to help improve heart health. (medicalnewstoday.com)
  • This can happen after surgery or with heart disease. (understandinganimalresearch.org.uk)
  • Of these, 7.6 million were attributed to coronary heart disease and 5.7 million to stroke. (health.am)
  • Rheumatic fever also causes rheumatic heart disease several years later. (clevelandclinic.org)
  • 4 A recent analysis by Darby et al suggested a linear increase in the incidence of ischemic heart disease with higher estimated radiation doses to the heart. (ajmc.com)
  • Commercial development of catheter-based devices to treat structural heart disease in children is limited by the relatively small market size and the relatively large upfront costs. (sbir.gov)
  • Valvular heart disease (VHD. (adam.com)
  • Dr. Ho conducted a study including more than 25,000 men and women who were free of known heart disease at the outset. (cooperaerobics.com)
  • Yet the other factors still predicted death from all causes and from heart disease over the next seven years. (cooperaerobics.com)
  • Concerns also have been raised about the accuracy of treadmill stress testing when used to look for heart disease in people without symptoms, especially women. (cooperaerobics.com)
  • Also, not only is it useful as a determinar el eje diagnostic criterion for heart disease but also as a marker of prognosis and mortality in other diseases. (bvsalud.org)
  • for some diseases, including ischemic the first one is between 0 and -30 degrees, heart disease, hypertensive heart disease, and the second one is between the values and blockages, among others,3 but also of 90 and 110 degrees3. (bvsalud.org)
  • These holes are related to heart attacks and do not result from a birth defect. (wikidoc.org)
  • High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling. (auckland.ac.nz)
  • Still, it's been mostly observational studies that have compared conduction system pacing with biventricular pacing. (tctmd.com)
  • An ECG measures the heart's electrical impulses at rest or during exercise and can indicate the type of heart block present. (medicalnewstoday.com)
  • During the 1940's and early 50's the principle device available to generate a variety of electrical impulses, potentially capable of stimulating the heart was an external physiological stimulator manufactured by Grass Manufacturing Co for clinical and physiology lab application. (understandinganimalresearch.org.uk)
  • It delivered periodic electric impulses at 2 ms pulse width and 50 to 150 volts alternating current pulse amplitude through a pair of 3 cm 2 metal electrodes strapped to the patient's chest directly over the heart. (understandinganimalresearch.org.uk)
  • A pulse generator is a small metal case that contains electronic circuitry with a small computer and a battery that regulate the impulses sent to the heart. (timesofisrael.com)
  • The electrode on the end of the lead touches the heart wall and delivers electrical impulses to the heart. (timesofisrael.com)
  • This section also explains how electrical impulses control and influence muscle cells throughout the body as well as the pumping of blood throughout the heart. (lawyersandjudges.com)
  • Each side has a relatively thin-walled chamber that receives blood returning to the heart (atrium) and a muscular chamber that pumps blood out of the heart (ventricle). (health.am)
  • The coronary arteries supply oxygen-rich blood to the tissues of the heart. (health.am)
  • 2. Electrical conduction system of the heart ​ The normal intrinsic electrical conduction of the heart a. (jisho.org)