Atrioventricular Node: 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.Tachycardia, Atrioventricular Nodal Reentry: 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.Bundle of His: 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.Heart Conduction System: 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.Sinoatrial Node: 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).Heart Block: 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.Catheter Ablation: 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.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Tachycardia, Paroxysmal: Abnormally rapid heartbeats with sudden onset and cessation.Electrocardiography: 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.Lymph Nodes: They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.Tachycardia: 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.Wolff-Parkinson-White Syndrome: 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.Tachycardia, Supraventricular: A generic expression for any tachycardia that originates above the BUNDLE OF HIS.Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Tachycardia, Ectopic Junctional: A rare form of supraventricular tachycardia caused by automatic, not reentrant, conduction initiated from sites at the atrioventricular junction, but not the ATRIOVENTRICULAR NODE. It usually occurs during myocardial infarction, after heart surgery, or in digitalis intoxication with a HEART RATE ranging from 140 to 250 beats per minute.Atrial Fibrillation: 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.Atrial Function: The hemodynamic and electrophysiological action of the HEART ATRIA.Electrocoagulation: Procedures using an electrically heated wire or scalpel to treat hemorrhage (e.g., bleeding ulcers) and to ablate tumors, mucosal lesions, and refractory arrhythmias. It is different from ELECTROSURGERY which is used more for cutting tissue than destroying and in which the patient is part of the electric circuit.Sick Sinus Syndrome: A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.Atrial Flutter: 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).Refractory Period, Electrophysiological: 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.Ultimobranchial Body: A diverticulum from the fourth pharyngeal pouch of an embryo, regarded by some as a rudimentary fifth pharyngeal pouch and by others as a lateral thyroid primordium. The ultimobranchial bodies of lower vertebrates contain large amounts of calcitonin. In mammals the bodies fuse with the thyroid gland and are thought to develop into the parafollicular cells. (Stedman, 25th ed)Heart Septum: This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.Tachycardia, Ectopic Atrial: Abnormally rapid heartbeats originating from one or more automatic foci (nonsinus pacemakers) in the HEART ATRIUM but away from the SINOATRIAL NODE. Unlike the reentry mechanism, automatic tachycardia speeds up and slows down gradually. The episode is characterized by a HEART RATE between 135 to less than 200 beats per minute and lasting 30 seconds or longer.Rabbits: 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.Electrophysiology: 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.Pacemaker, Artificial: A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).Vagus Nerve: The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).Radio Waves: Electromagnetic waves with frequencies between about 3 kilohertz (very low frequency - VLF) and 300,000 megahertz (extremely high frequency - EHF). They are used in television and radio broadcasting, land and satellite communications systems, radionavigation, radiolocation, and DIATHERMY. The highest frequency radio waves are MICROWAVES.Atrioventricular Block: Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.Anti-Arrhythmia Agents: 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.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Dogs: 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)Arrhythmias, Cardiac: 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.Heart Ventricles: 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.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Connexins: 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.Body Surface Potential Mapping: 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)Lymph Node Excision: Surgical excision of one or more lymph nodes. Its most common use is in cancer surgery. (From Dorland, 28th ed, p966)Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Heart Neoplasms: Tumors in any part of the heart. They include primary cardiac tumors and metastatic tumors to the heart. Their interference with normal cardiac functions can cause a wide variety of symptoms including HEART FAILURE; CARDIAC ARRHYTHMIAS; or EMBOLISM.Microelectrodes: Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)Models, Cardiovascular: 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.Tricuspid Valve: The valve consisting of three cusps situated between the right atrium and right ventricle of the heart.Heart: The hollow, muscular organ that maintains the circulation of the blood.Sentinel Lymph Node Biopsy: A diagnostic procedure used to determine whether LYMPHATIC METASTASIS has occurred. The sentinel lymph node is the first lymph node to receive drainage from a neoplasm.Myocardium: 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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Adenosine: A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.Lyme Disease: An infectious disease caused by a spirochete, BORRELIA BURGDORFERI, which is transmitted chiefly by Ixodes dammini (see IXODES) and pacificus ticks in the United States and Ixodes ricinis (see IXODES) in Europe. It is a disease with early and late cutaneous manifestations plus involvement of the nervous system, heart, eye, and joints in variable combinations. The disease was formerly known as Lyme arthritis and first discovered at Old Lyme, Connecticut.Myocarditis: Inflammatory processes of the muscular walls of the heart (MYOCARDIUM) which result in injury to the cardiac muscle cells (MYOCYTES, CARDIAC). Manifestations range from subclinical to sudden death (DEATH, SUDDEN). Myocarditis in association with cardiac dysfunction is classified as inflammatory CARDIOMYOPATHY usually caused by INFECTION, autoimmune diseases, or responses to toxic substances. Myocarditis is also a common cause of DILATED CARDIOMYOPATHY and other cardiomyopathies.Torsades de Pointes: A malignant form of polymorphic ventricular tachycardia that is characterized by HEART RATE between 200 and 250 beats per minute, and QRS complexes with changing amplitude and twisting of the points. The term also describes the syndrome of tachycardia with prolonged ventricular repolarization, long QT intervals exceeding 500 milliseconds or BRADYCARDIA. Torsades de pointes may be self-limited or may progress to VENTRICULAR FIBRILLATION.Phenethylamines: A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed)Radiosurgery: A radiological stereotactic technique developed for cutting or destroying tissue by high doses of radiation in place of surgical incisions. It was originally developed for neurosurgery on structures in the brain and its use gradually spread to radiation surgery on extracranial structures as well. The usual rigid needles or probes of stereotactic surgery are replaced with beams of ionizing radiation directed toward a target so as to achieve local tissue destruction.Pindolol: A moderately lipophilic beta blocker (ADRENERGIC BETA-ANTAGONISTS). It is non-cardioselective and has intrinsic sympathomimetic actions, but little membrane-stabilizing activity. (From Martindale, The Extra Pharmocopoeia, 30th ed, p638)Sinoatrial Block: Disturbance in the atrial activation that is caused by transient failure of impulse conduction from the SINOATRIAL NODE to the HEART ATRIA. It is characterized by a delayed in heartbeat and pauses between P waves in an ELECTROCARDIOGRAM.Rheumatic Heart Disease: Cardiac manifestation of systemic rheumatological conditions, such as RHEUMATIC FEVER. Rheumatic heart disease can involve any part the heart, most often the HEART VALVES and the ENDOCARDIUM.Rheumatic Fever: A febrile disease occurring as a delayed sequela of infections with STREPTOCOCCUS PYOGENES. It is characterized by multiple focal inflammatory lesions of the connective tissue structures, such as the heart, blood vessels, and joints (POLYARTHRITIS) and brain, and by the presence of ASCHOFF BODIES in the myocardium and skin.Hyperthyroidism: Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.Dictionaries, MedicalDictionaries as Topic: Lists of words, usually in alphabetical order, giving information about form, pronunciation, etymology, grammar, and meaning.Dictionaries, ChemicalTerminology as Topic: The terms, expressions, designations, or symbols used in a particular science, discipline, or specialized subject area.Solute Carrier Family 12, Member 4: K-Cl cotransporter ubiquitously expressed with higher expression levels in ERYTHROCYTES of ANEMIA, SICKLE CELL. It mediates active potassium and chloride cotransport across the plasma membrane and contributes to cell volume homeostasisSearch Engine: Software used to locate data or information stored in machine-readable form locally or at a distance such as an INTERNET site.Solute Carrier Family 12, Member 3: Na-Cl cotransporter in the convoluted segments of the DISTAL KIDNEY TUBULE. It mediates active reabsorption of sodium and chloride and is inhibited by THIAZIDE DIURETICS.Databases, Genetic: Databases devoted to knowledge about specific genes and gene products.Genome, Human: The complete genetic complement contained in the DNA of a set of CHROMOSOMES in a HUMAN. The length of the human genome is about 3 billion base pairs.Nuclear Receptor Subfamily 4, Group A, Member 3: An orphan nuclear receptor that is closely related to members of the thyroid-steroid receptor family. It was originally identified in NERVE CELLS, however it may play regulatory roles in a variety of other tissues.Nuclear Receptor Subfamily 2, Group C, Member 2: An orphan nuclear receptor that has specificity for hormone response elements found in the promoters of target genes. It binds DNA either as a homodimer or as heterodimer with the closely-related orphan nuclear receptor NUCLEAR RECEPTOR SUBFAMILY 2, GROUP C, MEMBER 1. The protein was originally identified as a TESTES-specific protein and is involved in the regulation of variety of cellular processes, including CELL DIFFERENTIATION; CELL PROLIFERATION; and APOPTOSIS.Nuclear Receptor Subfamily 4, Group A, Member 1: An orphan nuclear receptor that is closely related to members of the thyroid-steroid receptor gene family. It was originally identified in NERVE CELLS and may play a role in mediation of NERVE GROWTH FACTOR-induced CELL DIFFERENTIATION. However, several other functions have been attributed to this protein including the positive and negative regulation of APOPTOSIS.Nuclear Receptor Subfamily 4, Group A, Member 2: An orphan nuclear receptor that is found at high levels in BRAIN tissue. The protein is believed to play a role in development and maintenance of NEURONS, particularly dopaminergic neurons.Abbreviations as Topic: Shortened forms of written words or phrases used for brevity.AxisTeaching Materials: Instructional materials used in teaching.Pharmacology, Clinical: The branch of pharmacology that deals directly with the effectiveness and safety of drugs in humans.Competitive Behavior: The direct struggle between individuals for environmental necessities or for a common goal.5-alpha Reductase Inhibitors: Drugs that inhibit 3-OXO-5-ALPHA-STEROID 4-DEHYDROGENASE. They are commonly used to reduce the production of DIHYDROTESTOSTERONE.Azasteroids: Steroidal compounds in which one or more carbon atoms in the steroid ring system have been substituted with nitrogen atoms.Calcium Channels, T-Type: A heterogenous group of transient or low voltage activated type CALCIUM CHANNELS. They are found in cardiac myocyte membranes, the sinoatrial node, Purkinje cells of the heart and the central nervous system.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Reference Books, Medical: Books in the field of medicine intended primarily for consultation.Textbooks as Topic: Books used in the study of a subject that contain a systematic presentation of the principles and vocabulary of a subject.BooksTissue Array Analysis: The simultaneous analysis of multiple samples of TISSUES or CELLS from BIOPSY or in vitro culture that have been arranged in an array format on slides or microchips.Electric Countershock: An electrical current applied to the HEART to terminate a disturbance of its rhythm, ARRHYTHMIAS, CARDIAC. (Stedman, 25th ed)Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.Defibrillators: Cardiac electrical stimulators that apply brief high-voltage electroshocks to the HEART. These stimulators are used to restore normal rhythm and contractile function in hearts of patients who are experiencing VENTRICULAR FIBRILLATION or ventricular tachycardia (TACHYCARDIA, VENTRICULAR) that is not accompanied by a palpable PULSE. Some defibrillators may also be used to correct certain noncritical dysrhythmias (called synchronized defibrillation or CARDIOVERSION), using relatively low-level discharges synchronized to the patient's ECG waveform. (UMDNS, 2003)Heart Arrest: Cessation of heart beat or MYOCARDIAL CONTRACTION. If it is treated within a few minutes, heart arrest can be reversed in most cases to normal cardiac rhythm and effective circulation.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Information Centers: Facilities for collecting and organizing information. They may be specialized by subject field, type of source material, persons served, location, or type of services.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Rare Diseases: A large group of diseases which are characterized by a low prevalence in the population. They frequently are associated with problems in diagnosis and treatment.National Health Planning Information Center (U.S.): A center in the HEALTH RESOURCES ADMINISTRATION Division of Planning Methods and Technology which provides access to current information on health planning and resources development.Atrial Natriuretic Factor: A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight PEPTIDES derived from a common precursor and secreted mainly by the HEART ATRIUM. All these peptides share a sequence of about 20 AMINO ACIDS.Body Patterning: The processes occurring in early development that direct morphogenesis. They specify the body plan ensuring that cells will proceed to differentiate, grow, and diversify in size and shape at the correct relative positions. Included are axial patterning, segmentation, compartment specification, limb position, organ boundary patterning, blood vessel patterning, etc.Receptors, Atrial Natriuretic Factor: Cell surface proteins that bind ATRIAL NATRIURETIC FACTOR with high affinity and trigger intracellular changes influencing the behavior of cells. They contain intrinsic guanylyl cyclase activity.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

A comparison of an A1 adenosine receptor agonist (CVT-510) with diltiazem for slowing of AV nodal conduction in guinea-pig. (1/783)

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)

Modulation of AV nodal and Hisian conduction by changes in extracellular space. (2/783)

Previous studies have demonstrated that the extracellular space (ECS) component of the atrioventricular (AV) node and His bundle region is larger than the ECS in adjacent contractile myocardium. The potential physiological significance of this observation was examined in a canine blood-perfused AV nodal preparation. Mannitol, an ECS osmotic expander, was infused directly into either the AV node or His bundle region. This resulted in a significant dose-dependent increase in the AV nodal or His-ventricular conduction time and in the AV nodal effective refractory period. Mannitol infusion eventually resulted in Wenckebach block (n = 6), which reversed with mannitol washout. The ratio of AV nodal to left ventricular ECS in tissue frozen immediately on the development of heart block (n = 8) was significantly higher in the region of block (4.53 +/- 0.61) compared with that in control preparations (2.23 +/- 0.35, n = 6, P < 0.01) and donor dog hearts (2.45 +/- 0.18, n = 11, P < 0.01) not exposed to mannitol. With lower mannitol rates (10% of total blood flow), AV nodal conduction times increased by 5-10% and the AV node became supersensitive to adenosine, acetylcholine, and carbachol, but not to norepinephrine. We conclude that mannitol-induced changes in AV node and His bundle ECS markedly alter conduction system electrophysiology and the sensitivity of conductive tissues to purinergic and cholinergic agonists.  (+info)

Ventricular excitation maps using tissue Doppler acceleration imaging: potential clinical application. (3/783)

OBJECTIVES: The purpose of this study is to validate the use of tissue Doppler acceleration imaging (TDAI) for evaluation of the onset of ventricular contraction in humans. BACKGROUND: Tissue Doppler acceleration imaging can display the distribution, direction and value of ventricular acceleration responses to myocardial contraction and electrical excitation. METHODS: Twenty normal volunteers underwent TDAI testing to determine the normal onset of ventricular acceleration. Two patients with paroxysmal supraventricular tachycardia and 30 patients with permanent pacemakers underwent introduction of esophageal and right ventricular pacing electrodes, respectively, and were studied to visualize the onset of pacer-induced ventricular acceleration. Eight patients with dual atrioventricular (AV) node and 20 patients with Wolff-Parkinson-White (WPW) syndrome underwent TDAI testing to localize the abnormal onset of ventricular acceleration, and the results were compared with those of intracardiac electrophysiology (ICEP) tests. RESULTS: The normal onset and the onset of dual AV node were localized at the upper interventricular septum (IVS) under the right coronary cusp within 25 ms before the beginning of the R wave in the electrocardiogram (ECG). In all patients in the pacing group, the location and timing of the onset conformed to the positions and timing of electrodes (100%). In patients with WPW syndrome, abnormal onset was localized to portions of the ventricular wall other than the upper IVS at the delta wave or within 25 ms after the delta wave in the ECG. The agreement was 90% (18 of 20) between the abnormal onset and the position of the accessory pathways determined by ICEP testing. CONCLUSIONS: These results suggest that TDAI is a useful noninvasive method that frequently is successful in visualizing the intramural site of origin of ventricular mechanical contraction.  (+info)

Anatomical study of truncus arteriousus communis with embryological and surgical considerations. (4/783)

Twelve specimens of truncus arteriosus communis have been studied anatomically, with special reference to the conal anatomy and to the associated cardiac anomalies which can create additional problems if surgical repair is planned. A wide spectrum of conal morphology has been observed, suggesting that differential conal absorption is a developmental characteristic of truncus arteriousus as well as of transposition complexes. The invariable absence of septation of the ventricular infundibula and semilunar valves, in spite of the variable anatomy of the free wall of the conus, indicates that all types of truncus arteriosus, ontogenetically, should be considered as a single undivided conotruncus. Various types of ventircular septal defect were found: (a) ventricular septal defect with absent crista, in which no remnants of conal septum are present; (b) supracristal ventricular septal defect, in which vestigial conal septum is seen in front of the membranous septum; (c) bulloventricular foramen, associated with univentricular origin of the truncus from the right ventricle. Frequent associated anomalies are underdevelopment of the aortic arch, truncal valve malformations, and obstructive ventricular septal defect. The AV conduction system studied in one case showed an arrangement similar to Fallot's tetralogy with the His bundle and the left bundle-branch in a safe position behind the posteroinferior rim of the defect. The postoperative fate of the frequently abnormal truncal valve and the theoretical indications for total repair for Type IV truncus are also discussed.  (+info)

Electrophysiological effects of mexiletine in man. (5/783)

The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node.  (+info)

Monophasic action potentials of right atrium and electrophysiological properties of AV conducting system in patients with hypothyroidism. (6/783)

In 12 patients with manifest hypothyroidism right atrial monophasic action potentials showed a significant prolongation in comparison with data from normal or euthyroid patients. Atrial effective refractory periods were also significantly prolonged. After thyroid treatment the monophasic action potential duration and the effective refractory period of the right atrium were within normal ranges. In 6 hypothyroid patients studies of AV conduction with the aid of His bundle electrography and atrial pacing showed a supraHisian conduction delay which was manifest in one case and latent in another two. InfraHisian conduction delay was encountered in 2 cases.  (+info)

The nerve supply and conducting system of the human heart at the end of the embryonic period proper. (7/783)

The nerve supply and conducting system were studied in a stage 23 human embryo of exceptional histological quality. The nerves on the right side arose from cervical sympathetic and from cervical and thoracic vagal filaments. Out of their interconnexions vagoxympathetic nerves emerged, which (1) sent a branch in front of the trachea to the aorticopulmonary ganglion, thereby supplying arterial and venous structures, and (2) formed the right sinal nerve, which supplied the sinu-atrial node, and gave filaments to the interatrial septum which could be traced to the atrioventricular node and pulmonary veins. The nerves on the left side arose similarly from cervical sympathetic and from cervical and thoracic vagal filaments. These formed several descending, ganglionated, vagosympathetic filaments that descended to the right of the arch of the aorta and entered the aorticopulmonary ganglion. Filaments leaving the ganglion supplied the pulmonary trunk, ascending aorta, interatrial septum, pulmonary veins, and, as the left sinal nerve, the fold of the left vena cava. The thoracic vagal filaments descended to the left of the arch of the aorta and supplied chiefly the arterial end of the heart. No thoracic sympathetic cardiac filaments were found. The sinu-atrial node began as a crescentic mass in front of the lower part of the superior vena cava. It gradually extended on each side of the superior vena cava and came to form its posterior wall at a more caudal level. The atrial myocardium that formed the septum spurium, venous valves, and interatrial septum could be traced from the sinu-atrial to the atrioventricular node. Myocardium also encircled the atrial aspects of the atrioventricular orifices, and could be traced caudally to the atrioventricular nde. The atrioventricular node was a conspicuous mass in the anterior and lower part of the interatrial septum, from which a clearly defined bundle left to enter the interventricular septum. Right and left limbs were observed, the former being a rounded bundle that passed immediately in front of the root of the aorta.  (+info)

Atrioventricular nodal conduction during atrial fibrillation: role of atrial input modification. (8/783)

BACKGROUND: Posteroseptal ablation of the atrioventricular node (AVN) has been proposed as a means to slow the ventricular rate during atrial fibrillation (AF). The suggested mechanism is elimination of the AVN "slow pathway." On the basis of the unpredictable success of the procedure, we hypothesize that, in fact, the slow pathway is preserved. Therefore, the slowing of the ventricular rate results from reduced bombardment of the AVN. METHODS AND RESULTS: In 8 rabbit heart atrial-AVN preparations, cooling of the posterior and/or the anterior AVN approaches revealed nonspecific effects on the slow and fast pathway portions of the AVN conduction curve. In 13 other preparations, simulated AF during posterior cooling (n=6) prolonged the His-His (H-H) intervals but did not reveal specific slow pathway injury. In the remaining 7 preparations, AF was applied before and after posteroseptal surgical cuts. During AF with posterior origin, the cuts resulted in longer mean H-H along with slowing of the AVN bombardment rate. However, there was no change in the minimum observed H-H, suggesting an intact slow pathway. During AF with anterior origin, the mean and the shortest H-H remained unchanged before and after the cuts in all preparations. This was associated with the maintenance of high-rate AVN bombardment. CONCLUSIONS: Posteroseptal ablation does not eliminate the slow pathway. Ventricular rate slowing can be obtained if the ablation procedure results in a posteroanterior intra-atrial block leading to a reduction of the rate of AV nodal bombardment.  (+info)

*Atrioventricular node

The atrioventricular node, or AV node is a part of the electrical conduction system of the heart that coordinates the top of ... This activates the AV node. The atrioventricular node delays impulses by approximately 0.12s. This delay in the cardiac pulse ... November 2007). "Abnormal Conduction and Morphology in the Atrioventricular Node of Mice With Atrioventricular Canal-Targeted ... The AV node is quite compact (~1 x 3 x 5 mm). The AV node lies at the lower back section of the interatrial septum near the ...

*Concealed conduction

Atrioventricular node Electrocardiogram. ... However, this AV node stimulation (which is not visible on EKG ... As a result of the rapid atrial rate, some of the atrial activity fails to get through the AV node in an antegrade direction ... because the retrograde impulse from the PVC does not completely penetrate the AV node. ... by itself, hence "concealed") can cause a delay in subsequent AV conduction by modifying the AV node's subsequent conduction ...

*Common ostrich

The atrioventricular node position differs from other fowl. It is located in the endocardium of the atrial surface of the right ... 10 (1): 21-7. Parto P. (2012). "The Structure of the Atrioventricular Node in the Heart of the Female Laying Ostrich (Struthio ... The AV node connects the atrial and ventricular chambers. It functions to carry the electrical impulse from the atria to the ... The sinoatrial node shows a small concentration of purkinje fibers, however, continuing through the conducting pathway of the ...

*Chronotropic

A dromotrope affects atrioventricular node (AV node) conduction. A positive dromotrope increases AV nodal conduction, and a ... such as by changing the rhythm produced by the sinoatrial node. Positive chronotropes increase heart rate; negative ...

*Heart

The signal then travels to the atrioventricular node. This is found at the bottom of the right atrium in the atrioventricular ... The right coronary artery also supplies blood to the atrioventricular node (in about 90% of people) and the sinoatrial node (in ... Tawara's discovery of the atrioventricular node prompted Arthur Keith and Martin Flack to look for similar structures in the ... These generate a current that causes contraction of the heart, traveling through the atrioventricular node and along the ...

*Supraventricular tachycardia

They start from either the atria or atrioventricular node. They are generally due to one of two mechanisms: re-entry or ... Sinoatrial node reentrant tachycardia (SANRT) is caused by a reentry circuit localised to the SA node, resulting in a P-wave of ... Cryoablation is a newer treatment for SVT involving the AV node directly. SVT involving the AV node is often a contraindication ... at the atrioventricular node, which allows only a proportion of the fast impulses to pass through to the ventricles. In Wolff- ...

*Right axis deviation

It is measured using an electrocardiogram (ECG). Normally, this begins at the atrioventricular node (AV node); from here the ... Pre-excitation refers to early activation of the ventricles due to impulses bypassing the AV node via an accessory pathway. ...

*Lyme disease

"Fatal Lyme carditis and endodermal heterotopia of the atrioventricular node". Postgrad. Med. J. 66 (772): 134-36. doi:10.1136/ ... may adversely impact the heart's electrical conduction system and can cause abnormal heart rhythms such as atrioventricular ...

*Cystic tumour of the atrioventricular nodal region

It is also known as mesothelioma of the atrioventricular node. It may present as a cardiac arrhythmia or as sudden cardiac ... tumour of the atrioventricular nodal region is a very rare tumour of the heart in the region of the atrioventricular node. ... Cystic tumours of the atrioventricular nodal region, true to their name, have cystic spaces, which are lined by a single layer ... Apr 2000). "Cystic tumour of the atrioventricular nodal region: report of a case successfully treated with surgery". Heart. 83 ...

*List of pathologists

Ludwig Aschoff (1866-1942), German pathologist, discoverer of the Aschoff body and the Atrioventricular node in the heart. Max ... discoverer of the Atrioventricular node. Donald Teare (1911-1979), British pathologist. Jacques-René Tenon (1724-1816), French ...

*Junctional rhythm

Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along ... When this happens, the heart's atrioventricular node takes over as the pacemaker. In the case of a junctional rhythm, the atria ... Retrograde P waves refers to the depolarization from the AV node back towards the SA node. Junctional tachycardia Junctional ... an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node, the " ...

*Muscarinic antagonist

In the atrioventricular node, the resting potential is abbreviated, which facilitates conduction. This is seen as a shortened ... It causes tachycardia by blocking vagal effects on the sinoatrial node. Acetylcholine hyperpolarizes the sinoatrial node, which ...

*Nav1.5

In contrast, expression is low in the sinoatrial node and atrioventricular node. Within the heart, a transmural expression ...

*Atrial septal defect

Clark E, Kugler J (1982). "Preoperative secundum atrial septal defect with coexisting sinus node and atrioventricular node ... Both of these can cause an increased distance of internodal conduction from the SA node to the AV node. In addition to the PR ... but it is more commonly classified as an atrioventricular septal defect. Ostium primum defects are less common than ostium ...

*Koch's triangle

Variations in the size of Koch's triangle are common among people with different age and gender.The Atrioventricular node or ... tendon of Todaro and atrioventricular node. Also the elements anatomically near to it, are the insertion of the tricuspid valve ... "Koch's Triangle and the Atrioventricular Node in Ebstein's Anomaly: Implications for Catheter Ablation". Revista Española de ... the AV node is located at the apex of this triangle which depicts its anatomical importance . Sumitomo, Naokata; Tateno, ...

*Ludwig Aschoff

Together they discovered and described the atrioventricular node (AV node, Aschoff-Tawara node). Numerous travels abroad, to ...

*Atrioventricular nodal branch

The atrioventricular nodal branch is a cardiac artery that is crucial because it feeds the atrioventricular node, necessary for ... Very rarely, in approximately 2% of people, the vascular supply to the atrioventricular node arises from both the right ... In some people, the atrioventricular node instead receives blood from the circumflex branch of the left coronary artery, ... The artery of the atrioventricular node: an anatomic study based on 38 injection-dissections. Surg Radiol Anat 1996;18:183-187 ...

*Chordae tendineae

The apex of the triangle of Koch is the location of the atrioventricular node. During atrial systole, blood flows from the ... Chordae tendineae are relaxed because the atrioventricular valves are forced open. When the ventricles of the heart contract in ...

*Atrium (heart)

The atrioventricular node (AV node) is another node in the cardiac electrical conduction system. This is located between the ... node is located in posterior aspect of the right atrium, next to the superior vena cava. This is a group of pacemaker cells ...

*Systole

These electrical pathways contain the sinoatrial node, the atrioventricular node, and the Purkinje fibers. (Exceptions such as ... The electrical activity of ventricular systole is coordinated by the atrioventricular node, which is a discrete collection of ... the signals of which then coalesce at the atrioventricular node, there to be organized to provide a rhythmic electrical pulse ... The atrioventricular valves remain open while the aortic and pulmonary valves remain closed because the pressure gradient ...

*Bundle branches

Widran J, Lev M (December 1951). "The dissection of the atrioventricular node, bundle and bundle branches in the human heart". ...

*Beta-1 adrenergic receptor

Increases conduction and automaticity of atrioventricular node (AV node) Renin release from juxtaglomerular cells. Lipolysis in ... amylase-filled secretions from salivary glands Increase cardiac output Increase heart rate in sinoatrial node (SA node) ( ...

*Das Reizleitungssystem des Säugetierherzens

... "atrioventricular connecting system". The atrioventricular connecting system starts in the atrioventricular node, moves into the ... The monograph revealed the existence of the atrioventricular node and the function of Purkinje cells. It was used by Arthur ... Encouraged by their initial success and inspired by Tawara's discovery of the atrioventricular node, Keith and Flack extended ... Silverman, M. E.; Hollman, A. (1 October 2007). "Discovery of the sinus node by Keith and Flack: on the centennial of their ...

*AV nodal reentrant tachycardia

AVNRT occurs when a reentrant circuit forms within or just next to the atrioventricular node. The circuit usually involves two ... specifically on the atrioventricular node. These maneuvers include carotid sinus massage (pressure on the carotid sinus in the ... These pathways are formed from tissue that behaves very much like the AV node, and some authors regard them as part of the AV ... The slow pathway (which is usually targeted for ablation) is located inferior and slightly posterior to the AV node, often ...

*Premature atrial contraction

... node and propagating to the atrioventricular (AV) node, the signal is conducted both to the ventricle and back to the SA node ... However, if the atrial beat is premature enough, it may reach the atrioventricular node during its refractory period, in which ... This can be either a premature atrial contraction or a premature impulse from the atrioventricular node. SVES should be viewed ... Typically, the atrial impulse propagates normally through the atrioventricular node and into the cardiac ventricles, resulting ...

*List of ICD-9 codes 390-459: diseases of the circulatory system

Atrioventricular block, third degree (426.11) Atrioventricular block, first degree (426.12) Atrioventricular block, Mobitz II ( ... Acute febrile mucocutaneous lymph node syndrome (446.5) Giant Cell arteritis(Temporal Arteritis) (447) Other disorders of ... 426.13) Atrioventricular block, Wenckebach's (426.3) Bundle branch block, left (426.4) Bundle branch block, right (426.6) ... Sinoatrial heart block (426.7) Atrioventricular excitation, anomalous Wolff-Parkinson-White syndrome (427) Cardiac dysrhythmias ...
Several features remained to be clarified concerning the developmental origin of the atrioventricular conduction axis. For example, is the embryonic atrioventricular canal the major source of the atrial part of the conduction axis,10,11,13 or are major contributions made by adjacent tissues, such as the atrial chamber myocardium, the left sinus horn, the dorsal mesenchymal protrusion, or the atrioventricular bundle?15,17,-,20 What are the lineage origins of the atrial and ventricular parts of the axis, respectively?19,20 By our use of genetic lineage tracing, we have excluded the notion that contributions to the atrial part of the axis are made from the sinus horns or the epicardium (Tbx18+), from the ventricular myocardium, including the atrioventricular bundle, or from the dorsal mesenchymal protrusion (Mef2c-AHF-Cre+). The majority of the atrial components is derived from the embryonic atrioventricular canal, except for the lower nodal cells, which are derived from the embryonic ventricular ...
In this study we have demonstrated the feasibility of SRS for AV node ablation in an intact porcine model, and, to our knowledge, we are the third group to use radiation therapy for AV node ablation.4 Sharma et al attempted AV node ablation in 2 pigs: 1 procedure was successful with 70‐Gy ablation, whereas the other failed due to pacemaker infection.4 In our study we used doses of 35 to 40 Gy to successfully achieve complete heart blocks in 5 pigs. The pig in the Sharma et al study had AV node conduction changes earlier than 35 days after the procedure, which is likely related to the higher dose of radiation used. Our study is significant in that we demonstrated complete heart block in 5 pigs with a lower dose of radiation. Another group from the Mayo Clinic published their data recently in April 2017 on the external arrhythmia ablation using photon beams and achieved 86% success in achieving complete heart block in an intact animal model with a dose deescalation from 55 to 25 Gy.5 Our study ...
Intraoperative mapping of the specialized atrioventricular conduction system was performed in 47 patients during cardiac surgery. Specialized conduction tissue electrograms were identified in 37, and atrioventricular conduction preserved in 92%. Specialized conduction tissue was identified in 27 patients with atrioventricular canal defect: complete heart block was avoided in 25. Conduction tissue was located in six of 12 patients with complex transpositions; atrioventricular conduction was preserved in all six. Other lesions in which the technique was useful were Ebsteins anomaly and single atrium. Limitations to the technique are 1) deep hypothermia and circulatory arrest; 2) interruption in atrioventricular conduction during mapping; 3) inadequate exposure and access to probable sites of conduction tissue; 4) variation of size and spatial relations of individual malformations; and 5) limited time for identification of unusually located conduction tissue. Indications for use of this technique ...
In the present study, fibroblasts could be strategically injected into the atrium through the use of a percutaneous approach. These cells, identified 4 weeks later, were localized within injection lines in the expected anatomic targets. Fibroblast injections, with or without TGF-β1, modified cardiac electrophysiological properties of the AV node without creation of high-grade block. Although TGF-β1 alone did not significantly affect AV node conduction, pretreatment of fibroblasts with TGF-β1 significantly decrease AV nodal conduction, suggesting that this growth factor works through the fibroblast cell line.. The use of fibroblasts as a cell-based therapy in the treatment of burns, skin diseases, and head and neck tumors is well established.21-23 In these cases, the cells are used to replace damaged or injured tissue or to occupy space after tumor resection. In general, fibroblasts engraft well after implantation in noncardiac tissue, with minimal toxic degradation or inflammatory reactions. ...
TY - JOUR. T1 - Low-energy transvenous ablation of the canine atrioventricular conduction system with a suction electrode catheter. AU - Saksena, S.. AU - Tarjan, P. P.. AU - Bharati, S.. AU - Boveja, B.. AU - Cohen, D.. AU - Joubert, T.. AU - Lev, M.. PY - 1987/11/4. Y1 - 1987/11/4. N2 - A single suction electrode catheter was used for His bundle electrogram recording, His bundle pacing, and low-energy (20 or 30 J) His bundle ablation in seven dogs. The suction electrode catheter was actively fixed to the atrial endocardium at the His bundle level. Electrophysologic studies were performed in the control state, immediately after, and late (, 40 days) after His bundle ablation and results were correlated with histologic findings in the conduction system. Unipolar His bundle recording and pacing were successfully performed in all dogs with the suction electrode catheter before and after ablation. Complete heart block developed after a single 20 J shock delivered via the suction electrode catheter ...
The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.[1] 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. 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. The atrioventricular node delays impulses for ~0.1 second before allowing impulses through to the His-Purkinje conduction system, which spreads impulses to the ventricular walls. The reason it is important to delay the cardiac impulse is to ensure that the atria have ejected their blood into the ventricles before the ventricles contract.[2] ...
A fatal case of Lyme carditis occurring in a Suffolk farmworker is reported. Post-mortem examination of the heart showed pericarditis, focal myocarditis and prominent endocardial and interstitial fibrosis. The additional finding of endodermal heterotopia (mesothelioma) of the atrioventricular node raises the possibility that this could also be related to Lyme infection and account for the relatively frequent occurrence of atrioventricular block in this condition. Lyme disease should always be considered in a case of atrioventricular block, particularly in a young patient from a rural area. The heart block tends to improve and therefore only temporary pacing may be required.
Dromotropic derives from the Greek word "dromos", meaning running, a course, a race. A dromotropic agent is one which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart. Agents that are dromotropic are often (but not always) inotropic and chronotropic. For instance, parasympathetic stimulation is usually negatively chronotropic and dromotropic, but because the vagus nerve does not innervate ventricular myocardium has no effect on inotropy. Non-dihydropyridine calcium channel blockers such as verapamil block the slow inward calcium current in cardiac tissues, thereby having a negatively dromotropic, chronotropic and inotropic effect. This (and other) pharmacological effect makes these drugs useful in the treatment of angina pectoris. Conversely, they can lead to symptomatic disturbances in cardiac conduction and bradyarrhythmias, and may aggravate left ventricular failure. Bathmotropic Chronotropic Inotrope Furukawa, Y.; Wallick, D. W.; ...
(KudoZ) Spanish to English translation of el intervalo auricular a Hiss (A-H): A-H interval [Investigators/researchers brochure - Medical: Pharmaceuticals (Medical)].
One of the intriguing aspects of cardiac development is the manner in which the tubular embryonic myocardium, functioning initially as a fingerpump without one-way valves, eventually transforms into the complex adult four-chambered pump with a well-developed valvar apparatus and fibrous skeleton, capable of supporting two separate blood circulations after birth. In earlier studies, we have demonstrated how the processes responsible for this transformation-such as ventricular septation, the development of the atrioventricular valves, and the development of the atrioventricular conduction system-are closely related to one another.1 2 3 4 5 In this contribution, we focus on the morphological events producing the necessary insulation of the atrial from the ventricular myocardium. It is well established that during early cardiac development the ordinary atrial myocardium is continuous with myocardium of the ventricles throughout the atrioventricular junction.2 6 7 At these stages, the physical ...
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patients clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician ...
Junctional rhythm is an abnormal heart rhythm in the atrioventricular node. Though its not always dangerous, it can be a sign of...
Aortic stenosis (AS) is the most common type of valvular heart disease and its prevalence increases exponentially with age. Degenerative changes continue to be the most common pathologic causes. In terms of pathologic AS phenotypes, there are two main courses, fibrosis and calcification.
Looking for atrioventricular (AV) junctional rhythm? Find out information about atrioventricular (AV) junctional rhythm. the basic temporal element of music, concerned with duration and with stresses or accents whether irregular or organized into regular patternings. Explanation of atrioventricular (AV) junctional rhythm
I have continuous pacing following AV node ablation two years ago and have recently developed symptoms suggesting perhaps reduced left ventricular function. I have read some literature which gives com...
Ive tried all of the control medications and none have worked and all have side effects. Failed attempt at curing AF with an ablation. Considering an AV node ablation with pacemaker but Im not sure that it will work for ...
To demonstrate this potential, clusters of contracting cardiomyocytes isolated from the differentiation cultures were transplanted into the left ventricle of pigs that had their atrioventricular node ablated. The recipient hearts had spontaneous rhythms that appeared to originate from the transplanted cells as assessed by high-resolution electroanatomical mapping. Though promising, these results also raise the concern that transplanted cells could serve as a nidus for arrhythmia. Other mesoderm-derived lineages. While the hematopoietic, vascular, and cardiac lineages have been studied in most detail, the ES cell system does offer the potential to develop many other mesoderm lineages. To date, cell populations representing the skeletal muscle (Rohwedel et al. 1994 ...
AV nodal tissue is a not compact structure as we would be believe . But it is a fact , AV node do attempt to compact after birth. It is never complete. All specialised cells should coalesce to form the compact zone .This fails to happen in many . Failure of AV nodal compaction results …
Although power spectra of R-R and P-R intervals in response to random respiration show similar frequency distributions, the way in which dynamic sympathetic regulation contributes to such similarity remains unknown. We estimated the transfer function from sympathetic stimulation to the atrioventricular interval (AV conduction time; T(AV)) with and without constant ...
In previous posts we looked at a review by Dose J, Huebbe P, Nebel A and Rimbach G titled APOE4 genotype and stress response - a mini review. APOE4 is referenced as an upstream regulator of Tau and Amyloid pathology in Small and Duffs Dual Pathway Hypothesis. In their paper, Dose and colleagues note several…
An ADI/R mode is implemented using an intelligent pacing system to continually monitor ventricular response. This ensures AV conduction whenever possible so as to gain all the benefits of cardiac contractile properties resulting from native R-waves. In the event where AV conduction is blocked, the pacing mode is switched to a DDD/R mode to ensure a paced R-wave. Thereafter, subsequent to a completed interval of a P-wave, ADI/R pacing resumes to monitor ventricular response.
Accelerated junctional rhythm (AJR) occurs when the rate of an AV junctional pacemaker exceeds that of the sinus node. ECG Library LITFL
Also, notice the change in BP between the two panels. (Time display at the right lower corner indicates that the two panels were recorded 1 minute apart from each other). Explain the 2 reasons for the lower BP while in junctional rhythm ...
I will now investigate how the area increases with each shape. Instead of working out the area of each shape in cm³, I will count the number of triangles in each shape, as this is more efficient. In the first snowflake (see back of project) there were 81 triangles. The sides of the whole triangular shape are each 9 centimetres long, the area of one of the triangles can be found by squaring the length of one side ( 9 ² = 81).. I will calculate the area of each snowflake by breaking it down into individual triangle shapes. For example, shape 2 consists of one large triangle, from shape 1, and three new, smaller triangles:. The area of shape 2 can therefore be calculated by: area of large triangle + ( 3 × area of small triangle).. In order to work out the area in this manner, I will have to first work out the area of each triangle added on and the amount of triangles added on with each shape.. This table shows how the area of each small triangle decreases with each shape: ...
Trying to create perfect half square or quarter square fabric triangles for a quilt? Get the No Hassle Triangles Gauge. No geometry required with this triangle ruler.
Side 1 av 13 Produktet er ikke klassifisert som farlig og inneholder ingen substans klassifisert som farlig. Derfor er det ingen plikt til å opprette et sikkerhetsdatablad etter REACH artikkel 31 Dette
Hoteller i nærheten av SantAngelo In Pontano: Se anmeldelser fra reisende, bilder og gode tilbud på hotell i nærheten av SantAngelo In Pontano, Italia på TripAdvisor.
இதயம் சீராக சுருங்கி விரிவது இதயத்தின் மின்னோட்ட ஒழுங்கு முறைமையில் தான். இதய மேலறைகள் சுருங்கும் போது கீழறைகள் விரிவடைய வேண்டும். இதயத் துடிப்பு இதயத்தில் SA முடிச்சு எனும் இடத்தில் பிறக்கிறது. இது AV முடிச்சை அடையும் போது அதன் ஓட்டத்தில் சிறிது தாமதம் ஏற்படுத்தப்படுகிறது. இதுவே இதய மேலறைகள் சுருங்கும் போது கீழறைகள் விரிவடைய உதவுகிறது.. இதய அடைப்பை மூன்று நிலைகளாய்ப் ...
TY - JOUR. T1 - Late onset of accessory pathway conduction in a patient with complete AV block. AU - Erickson, Christopher C.. AU - Yetman, Anji T.. AU - Jones, Connie S.. AU - Dungan, W. Thompson. PY - 2000/1/1. Y1 - 2000/1/1. N2 - This case report discusses a patient with complete AV block in early childhood. The patient required a permanent pacemaker. At 6 years of age, intermittent preexcited beats were noted on telephonic transmissions. At 7 years of age, 1:1 preexcitation was noted in sinus rhythm. Therefore, late onset of antegrade accessory pathway function is demonstrated. This case provides evidence of developmental changes in accessory pathways. This may explain age related differences in the onset of narrow complex tachycardia in the school age years.. AB - This case report discusses a patient with complete AV block in early childhood. The patient required a permanent pacemaker. At 6 years of age, intermittent preexcited beats were noted on telephonic transmissions. At 7 years of ...
Posted By Ann Ibrahim on May 28, 1999 at 09:47:26 Thank you for your reply to my question relating to AV Node ablation and implantation of pacemaker for inappropriate sinus tachycardia. Your comments ...
Looking for online definition of atrioventricular conduction in the Medical Dictionary? atrioventricular conduction explanation free. What is atrioventricular conduction? Meaning of atrioventricular conduction medical term. What does atrioventricular conduction mean?
The cause of the electrocardiographic abnormalities in amyloidosis is a matter of controversy despite attempts of clinicopathological correlation. Detailed correlative studies of the involvement of cardiac conduction system in amyloidosis are few and have produced conflicting results. Some authors favour the hypothesis that infiltration of the conducting system by amyloid deposits is the main reason for the disturbances of conduction [19]. In familial amyloidosis with polyneuropathy, amyloid infiltration of the sinus node and atrioventricular conduction system is now well documented, and this seems to account for the majority of the electrophysiological disturbances of these regions [20, 21, 22].The distribution and extent of heart infiltration by amyloid are not, however, uniform. On the other hand, other authors have concluded that direct infiltration by amyloid is of lesser importance [14]. Autonomous neuropathy due to amyloid may also contribute to the electrophysiological disturbances. In ...
We describe a case of an otherwise healthy 50-year-old man with frequent attacks of heart palpitations. During electrophysiological study two episodes of atrial fibrillation (AF) were induced. In both cases AF was preceded by a few seconds of atrioventricular nodal reentrant tachycardia (AVNRT). Ablation of atrioventricular node slow pathway successfully eliminated both tachyarrhythmias during 6 months follow-up. Since during AVNRT a few short coupled atrial ectopic beats appeared, we hypothesized that AVNRT did not trigger AF directly but by inducing ectopic beats form a pulmonary vein or an atrial focus that became a direct trigger of AF ...
Electroanatomically estimated length of slow pathway in atrioventricular nodal reentrant tachycardia. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
The cardiac conduction system is a complex network of cells that together orchestrate the rhythmic and coordinated depolarization of the heart. The molecular mechanisms regulating the specification and patterning of cells that form this conductive network are largely unknown. Studies in avian models have suggested that components of the cardiac conduction system arise from progressive recruitment of cardiomyogenic progenitors, potentially influenced by inductive effects from the neighboring coronary vasculature. However, relatively little is known about the process of conduction system development in mammalian species, especially in the mouse, where even the histological identification of the conductive network remains problematic. We have identified a line of transgenic mice where lacZ reporter gene expression delineates the developing and mature murine cardiac conduction system, extending proximally from the sinoatrial node to the distal Purkinje fibers. Optical mapping of cardiac electrical ...
BioAssay record AID 55773 submitted by ChEMBL: Concentration required for 20% increase in the functional refractory period of canine ventricular muscle (extracellular electrophysiology) in vitro was reported. Range is between 9-4000.
Transient complete heart block - What is complete heart block? Heart block. Third-degree atrioventricular block or complete heart block, is a disorder of the cardiac conduction system where there is no conduction through the atrioventricular node. Therefore, complete dissociation of the atrial and ventricular activity exists. It results from various pathologic states causing infiltration, fibrosis, or loss of connection in portions of the healthy conduction system.
Looking for online definition of anterograde conduction in the Medical Dictionary? anterograde conduction explanation free. What is anterograde conduction? Meaning of anterograde conduction medical term. What does anterograde conduction mean?
Here we apply noninvasive electrocardiographic imaging (ECGI)3 to image ventricular epicardial activation during bigeminy in a patient with atrial fibrillation who underwent atrioventricular node ablation and pacemaker implantation in the right ventricular apex (asterisk in anterior view). ECGI is a functional imaging modality that combines 250 body-surface ECGs with thoracic computed tomography.3,4 By using inverse reconstruction algorithms, ECGI noninvasively generates electroanatomic maps on the epicardial surface of the heart. After extensive validation, it has been applied in human subjects with various cardiac electrophysiological conditions.5-8. The Figure (A) shows the sequence of ventricular activation during bigeminy. The top row demonstrates the regular paced beat, with wavefront propagation from the pacing site to the rest of the heart over a duration of 160 ms because of slow activation in the absence of conduction system participation. The bottom row shows activation during the ...
AbstractAlthough atrial fibrillation is well tolerated by most patients, in some patients the consequences may be severe. The Maze procedure is a new open-heart operation that creates a carefully designed maze of incisions in the atrial myocardium; this maze then acts as an electrical conduit to channel atrial impulses from the sinoatrial node to the atrioventricular node. The Maze procedure has been shown to restore sinus rhythm and atrial systole (thus reducing the risk of thromboembolism), improve hemodynamics, alleviate palpitations, and eliminate the need for antiarrhythmic and anticoagulant drugs. We describe our first patient to undergo this operation.
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Looking for nodal artery? Find out information about nodal artery. blood vessel that conveys blood away from the heart heart, muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a... Explanation of nodal artery
Organ-specific functions of tissue-resident macrophages in the steady-state heart are unknown. Here, we show that cardiac macrophages facilitate electrical conduction through the distal atrioventricular node, where conducting cells densely intersperse with elongated macrophages expressing connexin 43. When coupled to spontaneously beating cardiomyocytes via connexin-43-containing gap junctions, cardiac macrophages have a negative resting membrane potential and depolarize in synchrony with cardiomyocytes. Conversely, macrophages render the resting membrane potential of cardiomyocytes more positive and, according to computational modeling, accelerate their repolarization. Photostimulation of channelrhodopsin-2-expressing macrophages improves atrioventricular conduction, whereas conditional deletion of connexin 43 in macrophages and congenital lack of macrophages delay atrioventricular conduction. In the Cd11b(DTR) mouse, macrophage ablation induces progressive atrioventricular block. These ...
Despite remarkable progress in the past few years, the gene regulatory networks underlying formation and function of the cardiac conduction system (CCS) remain incompletely understood. Transcription factors such as NXK2.5 and TBX2/3/5 that control various aspects of heart development have emerged as key regulators of cardiac conduction gene expression and function. By showing alterations in the structure of the atrioventricular node (AVN) and the electrophysiological parameters of mice harboring a mutated GATA-binding factor 6 (GATA6) protein, Liu et al1 add a new player to the growing list of transcription factors involved in cardiac rhythm regulation. This finding provides insight that will help advance efforts to elucidate the pathogenesis of cardiac rhythm disturbances.. Article see p 284. In human, cardiac rhythm disturbances are a major cause of mortality and morbidity from fetal to adult life. They can develop in response to numerous conditions, such as electrolyte imbalance, ...
The development and structure of the cardiac conduction system, including the known molecular and cellular factors that regulate development of the conduction system are outlined. Part II includes...
OBJECTIVE.: To compile a database of disc height, vertebral height and sagittal plane displacement from lateral radiographic views of the lumbar spine, valid for male and female subjects in the age range 16-57 years. The protocols used to measure these parameters compensate for distortion in central projection, off-centre position, axial rotation and lateral tilt of the spine as well as for variation in radiographic magnification and stature. STUDY DESIGN.: The study comprised designing and testing of measurement protocols, together with subsequent data collection from archive radiographs. BACKGROUND.: Attempts to quantify primary mechanical damage to lumbar vertebrae and discs have been limited due to imprecision when measuring disc height, vertebral height and sagittal plane displacement. Age-related, normative values for these parameters were not previously available. Consequently, important issues like the effectiveness of past and present guidelines for safe manual handling with respect to
What is the difference between SA node and AV node? SA node generates cardiac action potential while AV node receives the action potential from the SA node...
An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node), which is a small mass of specialized tissue located in the right atrium (right upper chamber) of the heart.. The sinus node generates an electrical stimulus regularly at 60 to 100 times per minute under normal conditions. This electrical stimulus travels down through the conduction pathways (similar to the way electricity flows through power lines from the power plant to your house) and causes the hearts lower chambers to contract and pump out blood. The right and left atria (the two upper chambers of the heart) are stimulated first and contract a short period of time before the right and left ventricles (the two lower chambers of the heart).. The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node), where impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles. The bundle ...
An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node), which is a small mass of specialized tissue located in the right atrium (right upper chamber) of the heart.. The sinus node generates an electrical stimulus regularly at 60 to 100 times per minute under normal conditions. This electrical stimulus travels down through the conduction pathways (similar to the way electricity flows through power lines from the power plant to your house) and causes the hearts lower chambers to contract and pump out blood. The right and left atria (the two upper chambers of the heart) are stimulated first and contract a short period of time before the right and left ventricles (the two lower chambers of the heart).. The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node), where impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles. The bundle ...
Radiation dose to the nodal regions during prone versus supine breast irradiation Melinda Csenki, Dóra Újhidy, Adrienn Cserháti, Zsuzsanna Kahán, Zoltán Varga Department of Oncotherapy, University of Szeged, Szeged, Hungary Background: Prone positioning for breast radiotherapy is preferable when the aim is a reduction of the dose to the ipsilateral lung or the heart in certain left-sided cases. Materials and methods: In 100 breast cancer cases awaiting postoperative whole-breast radiotherapy, conformal radiotherapy plans were prospectively generated in both prone and supine positions. The axillary nodal region (levels I–III) and internal mammary (IM) lymph-node region in the upper three intercostal spaces were retrospectively contoured. The mean doses to the nodal regions and the volume receiving 25 Gy (V25Gy), V45Gy, and V47.5Gy were compared between the two treatment positions. Results: In most cases, the doses to axillary levels I–III and the IM lymph
Solution for question: What is the Significance of Atrio-ventricular Node and Atrio-ventricular Bundle in the Functioning of Heart concept: Circulatory Pathways - Human Circulatory System. For the courses CBSE (Arts), CBSE (Commerce), CBSE (Science)
Few diseases exemplify the integration of research from bench to bedside as well as neonatal lupus, often referred to as a model of passively acquired autoimmunity. In essence, this disease encompasses two patients, both the mother and her child. The signature histologic lesion of autoimmune-associated congenital heart block is fibrosis of the conducting tissue, and in some cases the surrounding myocardium. It is astounding how rapid and, in most cases, irreversible is the fibrotic response to injury. The mechanism by which maternal anti-SSA/Ro-SSB/La antibodies initiate and perpetuate inflammation, and eventuate in scarring of the atrioventricular node, is not yet defined. In vitro and in vivo studies suggest that one pathologic cascade leading to scarring may be initiated via apoptosis, resulting in translocation of SSA/Ro-SSB/La antigens and subsequent surface binding by maternal autoantibodies. These opsonized cardiocytes are phagocytosed by macrophages, which secrete factors that transdifferentiate
The median percentage of ventricular beats paced was lower in the dual-chamber minimal ventricular pacing group compared with the conventional dual-chamber pacing group (9.1% vs. 99.0%, p < 0.001). There was no difference in the percentage of atrial beats paced between the two groups (71.4% vs. 70.4%, p = 0.96). The primary endpoint of persistent atrial fibrillation occurred in significantly fewer patients in the dual-chamber minimal ventricular pacing group (7.9%) compared with the conventional dual-chamber pacing (12.7%; hazard ratio 0.60, 95% confidence interval 0.41-0.88; p = 0.009 ...
A pacing system for providing optimal hemodynamic cardiac function for parameters such as contractility (peak left ventricle pressure change during systole or LV+dp/dt), or stroke volume (aortic pulse pressure) using system for calculating atrio-ventricular delays for optimal timing of a ventricular pacing pulse. The system providing an option for near optimal pacing of multiple hemodynamic parameters. The system deriving the proper timing using electrical or mechanical events having a predictable relationship with an optimal ventricular pacing timing signal.
The aim of this multi-center research study is to evaluate the performance (primary purpose) and safety of a new algorithm aimed at controlling ventricular rate (VR) during rapidly conducted atrial fibrillation (AF) by delivering AV node stimulation (AVNS) from the atrial lead placed at a septal position, and designed with the purpose of reducing inappropriate shocks. Additional purposes include the assessment of a possible application of AVNS aimed at allowing prolonged control of VR during AF and reducing AF symptoms, and evaluation of implantation data on selective placement of the atrial lead in postero-septal right atrium. About 37 patients will be followed for half a year ...
PR segment: This is a time of electrical quiescence during which the wave of electrical excitation (depolarization) passes through mainly the AV node. In addition the wave of depolarization moves through the bundle of HIS, bundle branches and purkinje fibers. Since the wave of depolarization moves through the AV node at a speed of about 1/100th the speed the wave moves through the bundle of HIS, bundle branches and purkinje fibers, most of the PR segment is associated with the passage of the wave of depolarization through the AV node ...
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13. Junctional Dysrhythmias. Fast & Easy ECGs, 2nd E - A Self-Paced Learning Program. Junctional Dysrhythmias. Originate in AV junction (area around AV node and bundle of His) Slideshow 3359517 by ganya
Because the junctional beat rate is so close to this 850 msec interval, the ventricular sensed event occasionally occurs in the atrial-paced blanking period so it is not detected by the device. As such, no ventricular safety pacing occurs. (Recall that ventricular safety pacing occurs when a ventricular-sensed signal is detected in the paced AV interval and occurs 110 milliseconds after the atrial pacing spike). Because the ventricular event was not sensed at the time the atrial pacing occurs, the pacemaker waits the programmed paced AV delay (180 msec) and delivers the pacing spike when the right ventricle is absolutely refractory (hence no pacing spike "capture.) The next junctional beat is then sensed by the RV lead and no pacing output occurs, and the process repeats ...
there was a thread on av1 re this topic so i took the liberty of getting the info and bringing it over to here...hope nobody minds for it is done.... ...
Is there a P Wave before each QRS? Are P waves upright and uniform? occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; P wave may be inverted ...
Cardiology referral should be made for patients found to have a Wenckebach conduction for specialist opinion on management, further investigation, and PPM consideration ...
Buy ZD7288 (CAS 133059-99-1), a water soluble sino-atrial node function modulator cited in 14 publications. Join researchers using high quality ZD7288 from…
Ah, the girl-focused love triangle. For generations, male and female audiences alike have lived for watching two dudes fight over a woman, and oftentimes it can seem like a choice between the lesser of two jerks.
Noen antimikrobielle midler metaboliseres i leveren. Ved nedsatt leverperfusjon og ved shunting kan leverclearance være endret i betydelig grad. Nedsatt metabolisme og hypoalbuminemi kan gi toksisk effekt av midler som nedbrytes i leveren, og som ikke har alternativ nedbryting.. Ofte er omfanget og konsekvensene av dette vanskelige å anslå. Graden av leversvikt er vanskelig å definere, og patofysiologiske forhold varierer.. ...
Revidert 28. april 2004 FORSKNING PÅ HELSEEFFEKTER AV GENMODIFISERTE ORGANISMER Sammendrag Studier på helseeffekter av genmodifiserte organismer (GMO) omfatter først og fremst analyser av en innsatt genkonstruksjon
Cystinose er en sjelden arvelig, lysosomal avleiringssykdom som forårsakes av manglende eller redusert transport av aminosyren cystin ut av lysosomene i ce
For higher data rate transmission in the area of multiple megabit per seconds CODICOs products according HomePlug AV Standard, come to mind.
10.04.2002: Tema: Thyreoidea - Follikkelcellene i thyreoidea produserer 100 % av det tyroksin som sirkulerer i blodet, men bare 10 - 20 % av det sirkulerende trijodtyronin.
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BACKGROUND: The catheter ablation using radiofrequency(RF) energy in patients with AV nodal reentrant tachycardia(AVNRT) has been proved as a safe and effective nonpharmacologic therapeutic modality. The selective ablation of slow pathway is now becomming a standard treatment in patients with AVNRT because of its high success rate and negligible AV block risk. In our study, we demonstrated the feasibility, success rate and complications of selective radiofrequency catheter ablation of fast pathway or slow pathway for the treatment of AV nodal reentrant tachycardia. METHODS: Among patients diagnosed as AVNRT by electrophysiologic study, total 21 patients (M : F=11 :10, mean age ; 39 years old) were included in this study. Selective RF ablation of fast pathway was performed in 9 patients and selective RF ablation of slow pathway in 12 patients. The RF generator used in this study was Osypka HAT 200 model and catheters were 6F or 7F steerable catheters with 4 mm distal tip. RESULTS: The successful ...
There are still some AV nodal reentrant tachycardias with unusual AV nodal properties that need further study to understand these complexities. Accordingly, the two-dimensional model with alpha and beta pathways in the AV nodal reentrant tachycardia
Background: Radiofrequency (RF) catheter ablation is the procedure of choice for the potential cure of atrioventricular nodal reentrant tachycardia (AVNRT) with high success rates. We hypothesed that as a result of the close proximity of Kochs triangle and low inter-atrial septal fibers, the RF ablation applied at this region may result in prolongation of inter-atrial conduction time (IACT). Methods: RF ablation of AVNRT was performed by conventional technique. IACT was measured before and 20 minutes after RF ablation during sinus rhythm. Number of ablations given and duration of ablation were noted. Results: The study group was consisted of 48 patients (36 [75%] female, 12 [25%] male, mean age 43.4 ± 14. 5 years). RF ablation was successful in all patients. Mean RF time was 4. 0 ± 3. 3 minutes and mean number of RF was 11. 9 ± 9, 8. The mean IACT was 70.1 ± 9.0 ms before ablation and 84.9 ± 12.7 ms after ablation, which demonstrated a significant prolongation (p,0.001). The prolongation ...
Laser, Rf or catheter ablation to treat atrioventricular nodal reentrant tachycardia (avnrt) (3d-controlled fluoroscopy) (costs for program #159909) ✔ University Hospital Düsseldorf ✔ Department of General Pediatrics, Neonatology and Pediatric Cardiology ✔ BookingHealth.com
Laser, Rf or catheter ablation to treat atrioventricular nodal reentrant tachycardia (avnrt) (3d-controlled fluoroscopy) (costs for program #126283) ✔ University Hospital Rechts der Isar of the Munich Technical University ✔ Department of Pediatrics ✔ BookingHealth.com
Adenosine is an anti arrhythmic agent which is useful in terminating the paroxysmal supraventricular tachycardia. Adenosine has a negative chronotropic action on the sino atrial node which will slow down the atrioventricular node conduction
We have known about histamine receptors in the heart for many years (1). The human H1- and H2-histamine receptors were cloned and characterized in the early 1990s (2,3), followed closely by the human H3- and H4-histamine receptors several years later (4,5). Histamine is a natural body constituent that is found throughout the body, especially the central nervous system, mast cells, gastric mucosa parietal cells, and basophils. The H1-receptor is coupled to Gα-q11 and activates a number of intracellular signals, including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate. In the heart, histamine decreases atrioventricular node conduction time via H1-receptors. The H2-histamine receptors are also found in the heart, and couple to Gαs proteins to signal through cAMP to produce chronotropic and inotropic activity. The H2-histamine receptors also subserve hypotension, flushing, headache, increased gastric acid production, and enhanced vascular permeability. Therefore, in ...
Aims Steering soft, flexible catheters using an external magnetic field could have advantages for heart catheterization, especially for therapy of tachyarrhythmias. Our aims were to assess the feasibility of magnetic navigation to Kochs triangle and reliable ablation of atrioventricular nodal re-entry tachycardia (AVNRT) with a magnetic catheter.. Methods and results Consecutive patients with AVNRT were mapped and ablated with a magnetically enabled catheter (Helios I or II), with, respectively, one and three magnets at the tip. The catheter was remotely advanced with the Cardiodrive™ system and orientated with the Navigant™ control system. After initial positioning with the external magnets, adjustment was made in 5° steps. Success rates, procedure, and fluoroscopy times were analysed, and compared with a local contemporary series of conventional AVNRT ablations. Magnetic navigation was feasible in all 20 patients. Targets were easily reached. Catheters remained stable in position during ...
The objective of the study was to evaluate the effect of ibutilide on canine cardiac sinoatrial and atrioventricular nodes (AVNs). For this purpose, 18 mongrel dogs were injected intravenously with ibutilide and the changes in heart rate, sinus node recovery time, and AVN were measured. Our data show that ibutilide administration caused significant suppression of the sinus atrial node, the peak response time was 20-30 min, and the heart rate was restored to pre-drug administration level. After receiving ibutilide, 1 animal had a 5 s sinus pause, and after 5 min of ibutilide administration, 1 dog showed 2:1 atrioventricular conduction. Therefore, it was concluded that ibutilide had a suppressive effect on the sinoatrial node and AVN. ...
A 64-year-old woman received 29 mm Mosaic mitral bioprosthesis in 2010 after failure of valve repair attempt. Subsequently she underwent percutaneous insertion of tricuspid valve Biocor Epic 31 prosthesis, which was complicated by complete atrioventricular (AV) block requiring dual-chamber pacing with a conventional right atrial lead placement and an unfixed left ventricular lead in the coronary sinus. Six years later, she developed persistent atrial fibrillation, which was controlled with repeated cardioversion, dofetilide (250 μg twice daily) and warfarin for primary stroke prophylaxis.. Eleven months later, she presented to the emergency department with episodes of profound dyspnoea and intermittent loss of consciousness. ECG demonstrated loss of ventricular pacing capture and non-sustained, polymorphic ventricular tachycardia that represents torsade de pointes (TdP). AV block with loss of ventricular capture by a ventricular lead dysfunction yielded bradycardia, which was critical in ...
Karel Frederik Wenckebach (March 24, 1864 - November 11, 1940) was a Dutch anatomist who was a native of the Hague. He studied medicine in Utrecht, and in 1901 become a professor of medicine at the University of Groningen. Later he was a professor at the Universities of Strasbourg (1911-14) and Vienna (1914-29). Wenckebach (pronounced ven-kĕ-bak) is primarily remembered for his work in cardiology. In 1899 he provided a description of irregular pulses due to partial blockage of atrioventricular conduction, creating a progressive lengthening of conduction time in cardiac tissue. The condition was referred to as a "second degree AV block" and later named the "Wenckebach phenomenon" and reclassified as Mobitz type I block in Mobitzs 1924 paper. A similar phenomenon can also occur in the Sinoatrial node where it gives rise to Type I second degree SA block, and this is also known as a Wenckebach block; the two have distinct features on an ECG however. Wenckebach is credited for describing the ...
Under normal physiologic conditions, the dominant pacemaker cells of the heart lie within the sinoatrial node; in adults, these pacemaker cells fire at rates between 60 to 100 beats per minute (i.e., faster than cells in any other cardiac region, See Figure 3). Even at rest, modulation by the autonomic nervous system dominates, with the primary drive from the parasympathetics; at rest or during sleep, the sinoatrial nodal rate decreases to about 75 beats per minute (bpm) or even slower.. In addition to pacemaker cells of the sinoatrial node, other cells within the conduction system are capable of developing autorhythmicity, specifically those within the atrioventricular node (junction region) and His-Purkinje system. Yet, rhythms generated within these cells are in a much lower range (25 to 55 bpm), hence not altering the intrinsic atrial rates (Figure 2). These lower rate rhythms are commonly referred to as ventricular escape rhythms and are important for patient survival, since they maintain ...
Selection of approach commonly hinges on the nature of the patients AF, expected likelihood that the atrium will sustain a normal rhythm and, perhaps most importantly, the patients symptoms. Rate control. The first step in controlling the heart rate and preventing symptoms from a rapid ventricular response (as well as a possible decrease in heart function) is to administer a beta blocker (such as metoprolol or atenolol), a calcium channel blocker (such as diltiazem or verapamil), digoxin, or a combination of these drugs. In persistent AF, heart rate trends should be assessed through ambulatory monitoring to maintain good rate control (typically 60 to 80 bpm at rest or 90 to 115 bpm with activity). If adequate rate control proves difficult to achieve, AV node ablation may be done to modify or disconnect electrical conduction between the atria and ventricles and thus prevent rapid ventricular rates. In some cases, AV node modification slows AF conduction sufficiently. But some patients require ...
In normal individuals, electrical activity in the heart is initiated in the sinoatrial (SA) node (located in the right atrium), propagates to the atrioventricular (AV) node, and then through the bundle of His to the ventricles of the heart. (See electrical conduction system of the heart).. The AV node acts as a gatekeeper, limiting the electrical activity that reaches the ventricles of the heart. This function of the AV node is important, because if the signals generated in the atria of the heart were to increase in rate (as they do during atrial fibrillation or atrial flutter), the AV node will limit the electrical activity that conducts to the ventricles. For instance, if the atria are electrically activated at 300 beats per minute, half those electrical impulses are blocked by the AV node, so that the ventricles are activated at 150 beats per minute (giving a pulse of 150 beats per minute). Another important property of the AV node is that it slows down individual electrical impulses. This is ...
Wolff-Parkinson-White Syndrome (WPWS) is a disorder in which an extra electrical connection between the atria and the ventricles is present at birth. People may have episodes of a very rapid heartbeat.. People with WPWS are born with an extra connection in the heart, called an accessory pathway, that allows electrical signals to bypass the trioventricular node and move from the atria to the ventricles faster than usual. The accessory pathway may also transmit electrical impulses disrupt the coordinated movement of electrical signals through the heart, abnormally from the ventricles back to the atria. This extra connection can leading to an abnormally fast heartbeat (tachycardia) and other arrhythmias.. The heartbeat is controlled by electrical signals that move through the heart in a highly coordinated way. A specialized cluster of cells called the atrioventricular node conducts electrical impulses from the hearts upper chambers (the atria) to the lower chambers (the ventricles). Impulses move ...
Circ Arrhythm Electrophysiol. 2012 Feb;5(1):68-76. doi: 10.1161/CIRCEP.111.967810. Epub 2011 Dec 20. Meta-Analysis; Research Support, Non-U.S. Govt; Review
Background. Contraction of the heart is initiated by electrical excitation which originates in pacemaker cells situated at the base of the heart. Propagation of the electrical signal from the sinoatrial node causes contraction of the atrium followed by the ventricle causing blood to be ejected from the ventricle into the bulbus arteriosus. The propagation of the electrical signal is orchestrated by opening and closing of voltage-gated ion channels which propagate the signal from cell to cell and chamber to chamber, passing from the atrium to the ventricle via the atrioventricular node. At critically high temperature, however, there is a breakdown of cardiac contraction which could originate in either the mechanism of electrical initiation or propagation. This article explores the latter and reveals the imbalance of rectifying K+ channels and depolarizing Na+ channels in the rainbow trout heart leads to atrioventricular block and loss of ventricular contraction in the presence of an atrial ...
PREFERRED ADI/R: A PERMANENT PACING MODE TO ELIMINATE VENTRICULAR PACING WHILE MAINTAINING BACKUP SUPPORT - A preferred atrial-based pacing method and apparatus is provided using an intelligent cardiac pacing system to having the ability to continue atrial-based pacing as long as relatively reliable AV conduction is present. In the event that such relatively reliable AV conduction is not present, mode switching to a DDD/R or a DDI/R pacing mode while continually biased to mode switch back to atrial-based pacing. The standard or relatively reliable AV conduction may be changed either automatically or manually. This increases pacing that utilizes natural AV conduction however possible so as to gain all the benefits of cardiac contractile properties resulting therefrom, while tolerating the occasional missed ventricular depolarization (i.e., non-conducted P-wave). In the event where relatively reliable AV conduction is not present, the pacing mode is switched to a DDD/R mode while detecting a ...
What do I mean when I say, "rapidly conducting AF?". Explaining AF in a short blog is impossible. Massively thick books have been written, and week long symposium are routinely given on AF . That said, here is my best impression of Sal Khan, who can explain nearly anything in a 10 min video.. When in AF, the atria are beating (quivering) at 300-500 beats per min. The atria do not pump blood to the body; the ventricle accomplishes this. Ventricular rate (pulse rate) is determined by how fast the AV node conducts the AF impulses from north to south. The AV node acts as a road between the atria and ventricle. It has a certain refractory period which means it can conduct electrical impulses only so fast. The AV nodes speed of conduction varies greatly amongst individuals, and thus, so does the ventricular rate during AF. The inter-person variability of AV conduction is probably in great part genetically determined, whereas the intra-person variability is related to adrenaline levels. The AV node is ...
Many cardiac excitation problems can be diagnosed from the information in a single lead of an electrocardiogram. The lead II electrocardiogram traces at the top of Figure 5-1 and 5-2 are identified as normal sinus rhythms based on the following characteristics: (1) the frequency of QRS complexes is approximately 1 per second, indicating a normal beating rate; (2) the shape of the QRS complex is normal for lead II and its duration is less than 120 ms, indicating rapid depolarization of the ventricles via normal conduction pathways; (3) each QRS complex is preceded by a P wave of proper configuration, indicating sinoatrial (SA) nodal origin of the excitation; (4) the PR interval is less than 200 ms, indicating proper conduction delay of the impulse propagation through the atrioventricular (AV) node; (5) the QT interval is less than half of the R-to-R interval, indicating normal ventricular repolarization; and (6) there are no extra P waves, indicating that no AV nodal conduction block is present. ...
Definition: VSDs are characterized by a split in the endocardial cushion cells in the interventricular component of the membranous septum which is close to the atrioventricular node.. ...
The preface of this text indicates that it would be of value as a guide for people starting to perform His bundle electrocardiography and also useful to those established in the field. Unfortunately, it has not reached these goals. Anatomical description has been stretched out over four chapters, but it lacks such pertinent details as the dimensions of the His bundle and bundle branches, and histology of the sinus node, A-V node, and accessory pathways. Chapter four on methodology for recording His bundle electrograms fails to mention the arm approach or the left heart techniques. The methodology used by the ...
A method and system for ascertaining the condition of the hearts conduction system in a patient treated for congestive heart failure with pacing therapy. In accordance with the invention, changes in ventricular activation patterns are monitored over time in order to detect changes in the hearts conduction system that may occur due to physiological regeneration of conduction pathways. The activation patterns are reflected by electrogram signals detected from different ventricular locations. By measuring the difference in conduction times of an excitation impulse traveling from the AV node to the different ventricular locations, a parameter representative of the hearts conduction system is obtained that may be used to adjust the pacing therapy in accordance therewith.
AF is a common irregular narrow-complex supraventricular tachyarrhythmia. <BR>AF is often associated with an underlying condition which frequently can be diagnosed after a basic history and physical examination. <BR>In newly diagnosed AF without an obvious underlying cause minimum investigations include a blood count, serum electrolytes, thyroid function, chest X-ray and an echocardiogram. <BR>AF is associated with increased morbidity and mortality related to its rate-related impact on left ventricular function and its association with thromboembolism. <BR>Management of AF is determined by symptoms, ventricular rate and thromboembolic risk and is individualised to each patient. <BR>Drug therapy remains the mainstay of treatment and beta-blockers are still first-line therapy due to proven safety and efficacy. <BR>AV nodal ablation and pacemaker implant is indicated in older patients with intractable symptoms or poor rate control who have failed or are intolerant of
New research could lead to a better "map" for doctors trying to fix a rare, rapid rhythm in childrens hearts.. Doctors usually treat this condition by destroying the abnormal tissue that is disrupting the hearts electrical rhythm. But finding that tissue can be hard; its not in the same spot for every person.. The researchers made their maps using electrical recordings from inside the heart to find the locations of high- and low-voltage tissues. That enabled them to more precisely target the weaker voltage tissues.. The condition is called atrioventricular nodal reentrant tachycardia, or AVNRT.. The researchers say this is the first study to try the technique in children, and it has the potential to improve success rates in treating children with the disorder.. ###. Related Information:. ...
Aim: To investigate the interacting effects of age and sex on electrocardiographic (ECG) features of Scn5a +/- mice modelling Brugada syndrome. Methods: Recordings were performed on anaesthetized wild-type (WT) and Scn5a +/- mice and differences attributable to these risk factors statistically stratified. Results: Scn5a +/- exerted sex-dependent effects upon sino-atrial function that only became apparent with age. RR intervals were greater in old male than in old female Scn5a +/- . Atrio-ventricular (AV) conduction was slower in young female mice, whether WT and Scn5a +/- , than the corresponding young male WT and Scn5a +/- . However, PR intervals lengthened with age in male but not in female Scn5a +/- giving the greatest PR intervals in old male Scn5a +/- compared with either old male WT or young male Scn5a +/- mice. In contrast, PR intervals were similar in old female Scn5a +/- and in old female WT. QTc was prolonged in Scn5a +/- compared with WT, and female Scn5a +/- compared with female WT. Age
Properties of the cardiac muscle AUTOMATICITY CONDUCTIVITY CONTRACTILITY EXCITABILITY REFRACTORY PERIODS 1. AUTOMATICITY is the unique ability of the cells in the SA node (pacemaker cells) to generate an action potential without being stimulated.
Dose J, Huebbe P, Nebel A and Rimbach G have published an interesting review on APOE4 APOE genotype and stress response - a mini review. APOE4 is referenced as an upstream regulator of Tau and Amyloid pathology in Small and Duffs Dual Pathway Hypothesis. In this review, Dose and colleagues note that there are two…
Reciprocating tachycardias due to reentry either within the atrioventricular (AV) node or using an accessory AV pathway are a common cause of paroxysmal supraventricular tachycardia in humans. Unfortunately, although of potential therapeutic value, differentiation of these forms of reciprocating tachycardia may be difficult and require detailed electrophysiologic study. To develop diagnostic criteria that permit exclusion of participation of an accessory AV pathway in reciprocating tachycardia without extensive laboratory testing, results of electrophysiologic studies were examined in 50 patients with Wolff-Parkinson-White syndrome, 15 patients with accessory AV pathways that conducted only in the ventriculoatrial direction, and 15 patients with reentry within the AV node. The interval between onset of ventricular activation and both earliest recorded atrial activity (V-Amin) and high lateral right atrial electrogram (V-HRA) was measured during tachycardia. A V-Amin of 61 ms or less or V-HRA of ...
Results Gender exerts significant influences on the epidemiology, age at onset of various paroxysmal supraventricular tachycardia. With overall incidence, atrioventricular reentrant tachycardia (AVRT) is more common compared with atrioventricular nodal reentrant tachycardia (AVNRT) (AVRT VS AVNRT: 58.7% vs 41.3%). Compared to women, men with paroxysmal supraventricular tachycardia have a higher incidence of atrioventricular accessory pathways, a lower prevalence of atrioventricular nodal reentrant tachycardia. The average age of onset with different types of PSVT varies; it is also affected by gender. The average onset age of AVNRT group, whether in men or women are significantly greater than AVRT group (p , 0.001). The average onset age of dominant pathway-mediated AVRT occurs youger than the occult accessory pathway-mediated group, this significant differences is unaffected by gender. In addition, female onset age of the left side dominant pathway-mediated AVRT is significantly less than men ...
Physicians who treat this condition. Paroxysmal supraventricular tachycardia (PSVT) is another type of "short-circuit" arrhythmia. It may result either from atrio-ventricular nodal re-entrant tachycardia (AVNRT) or from an accessory pathway, which may occur as part of the Wolff-Parkinson-White (WPW) syndrome.. PSVT may occur at any age and commonly occurs in patients who have no other types of heart disease. Patients with PSVT typically describe a rapid, or racing, regular heartbeat (between 130 and 230 beats per minute) that starts and stops abruptly. It is commonly misdiagnosed as a panic attack. With the exception of some patients with the Wolff-Parkinson-White syndrome, PSVT generally is not a dangerous arrhythmia. However, it can result in debilitating symptoms. Treatment options include a variety of drugs or catheter ablation, which cures the problem in most patients.. In AVNRT, a small extra pathway exists in or near the AV node. If an electrical impulse enters this pathway, it may start ...
An unusual patient is described in whom electrophysiological studies strongly suggest the occurrence of Mahaim conduction. The patient whose electrocardiogram previously showed a left anterior hemiblock pattern then developed advanced atrioventricular (AV) block (AH block). Beats conducted through the atrioventricular node always had a short HV interval (20 ms) and QRS complexes of left anterior hemiblock pattern. Junctional escape beats always had a normal HV interval (50 ms) with normal intraventricular conduction. His bundle pacing showed the StV interval and QRS contour of escape beats. These findings suggest the existence of an accessory pathway (Mahaim fibres) passing from the area of block, presumably the uppermost portion of the His bundle, to the posteroinferior division of the left bundle-branch. The surface electrocardiogram did not show the characteristic delta wave of the Wolff-Parkinson-White syndrome. Our observations suggest that patients in whom there is conduction along Mahaim ...
Introduction. Assessing left ventricular (LV) systolic function in a rapid and reliable way can be challenging in the critically ill patient. The purpose of this study was to evaluate the feasibility and reliability of, as well as the association between, commonly used LV systolic parameters, by using serial transthoracic echocardiography (TTE).. Methods. Fifty patients with shock and mechanical ventilation were included. TTE examinations were performed daily for a total of 7 days. Methods used to assess LV systolic function were visually estimated, "eyeball" ejection fraction (EBEF), the Simpson single-plane method, mean atrioventricular plane displacement (AVPDm), septal tissue velocity imaging (TDIs), and velocity time integral in the left ventricular outflow tract (VTI).. Results. EBEF, AVPDm, TDIs, VTI, and the Simpson were obtained in 100%, 100%, 99%, 95% and 93%, respectively, of all possible examinations. The correlations between the Simpson and EBEF showed r values for all 7 days ...
This Class 1A drug is useful in both supraventricular and ventricular arrhythmias. It major uses are to maintain sinus rhythm after conversion of atrial flutter or fibrillation, to prevent ventricular tachycardia, and for long-term prophylaxis in patients with AV nodal reentrant tachycardia and automatic atrial tachycardia. Quinidine also has been used to prevent symptomatic premature supraventricular and ventricular complexes. Because it slows conduction and prolongs the refractory period of the accessory pathway and suppresses automaticity of ectopic pacemakers, quinidine may prevent recurrences of paroxysmal supraventricular tachycardia caused by reentry over a concealed pathway or AV reciprocating tachycardia associated with the Wolff-Parkinson-White syndrome. It also may slow the ventricular response to atrial flutter or fibrillation in the preëxcitation syndrome. Quinidine is often preferred to procainamide for long-term therapy because elevated antinuclear antibody titers and ...
Previous data on spontaneous conversion of atrial fibrillation to sinus rhythm have been derived from smaller series that focused on the utility of specific AV node blocking agents or antiarrhythmic medications for promoting cardioversion. With the possible exception of sotalol, agents such as digoxin, beta-adrenergic receptor antagonists or calcium channel blockers are effective for ventricular rate control but ineffective for converting atrial fibrillation to sinus rhythm [20-25]. Previously, Falk and colleagues [8], examining the efficacy of digoxin for converting atrial fibrillation in a study of 36 patients, reported that 44% of the patients in the placebo arm had spontaneous conversion, compared with 50% of patients randomized to digoxin. Similar results were recently reported by the Digitalis in Acute Atrial Fibrillation (DAAF) investigators [12]. In that multicenter prospective study of digoxin versus placebo for conversion of recent atrial fibrillation, there was no significant ...

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