A condition that is characterized by episodes of fainting (SYNCOPE) and varying degree of ventricular arrhythmia as indicated by the prolonged QT interval. The inherited forms are caused by mutation of genes encoding cardiac ion channel proteins. The two major forms are ROMANO-WARD SYNDROME and JERVELL-LANGE NIELSEN SYNDROME.
A voltage-gated potassium channel that is expressed primarily in the HEART.
A family of voltage-gated potassium channels that are characterized by long N-terminal and C-terminal intracellular tails. They are named from the Drosophila protein whose mutation causes abnormal leg shaking under ether anesthesia. Their activation kinetics are dependent on extracellular MAGNESIUM and PROTON concentration.
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.
Potassium channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. The opening of these channels is induced by the membrane depolarization of the ACTION POTENTIAL.
A family of delayed rectifier voltage-gated potassium channels that share homology with their founding member, KCNQ1 PROTEIN. KCNQ potassium channels have been implicated in a variety of diseases including LONG QT SYNDROME; DEAFNESS; and EPILEPSY.
A voltage-gated sodium channel subtype that mediates the sodium ion PERMEABILITY of CARDIOMYOCYTES. Defects in the SCN5A gene, which codes for the alpha subunit of this sodium channel, are associated with a variety of CARDIAC DISEASES that result from loss of sodium channel function.
A form of long QT syndrome that is without congenital deafness. It is caused by mutation of the KCNQ1 gene which encodes a protein in the VOLTAGE-GATED POTASSIUM CHANNEL.
A characteristic symptom complex.
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.
Antiarrhythmic agent pharmacologically similar to LIDOCAINE. It may have some anticonvulsant properties.
A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9)
Unexpected rapid natural death due to cardiovascular collapse within one hour of initial symptoms. It is usually caused by the worsening of existing heart diseases. The sudden onset of symptoms, such as CHEST PAIN and CARDIAC ARRHYTHMIAS, particularly VENTRICULAR TACHYCARDIA, can lead to the loss of consciousness and cardiac arrest followed by biological death. (from Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005)
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.
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.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
A form of long QT syndrome that is associated with congenital deafness. It is characterized by abnormal cardioelectrophysiology involving the VOLTAGE-GATED POTASSIUM CHANNEL. It results from mutation of KCNQ1 gene (Subtype 1 or JLN1) or the KCNE1 gene (Subtype 2 or JLN2).
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
Membrane proteins whose primary function is to facilitate the transport of positively charged molecules (cations) across a biological membrane.
An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.
A variety of neuromuscular conditions resulting from MUTATIONS in ION CHANNELS manifesting as episodes of EPILEPSY; HEADACHE DISORDERS; and DYSKINESIAS.
An autosomal dominant defect of cardiac conduction that is characterized by an abnormal ST-segment in leads V1-V3 on the ELECTROCARDIOGRAM resembling a right BUNDLE-BRANCH BLOCK; high risk of VENTRICULAR TACHYCARDIA; or VENTRICULAR FIBRILLATION; SYNCOPAL EPISODE; and possible sudden death. This syndrome is linked to mutations of gene encoding the cardiac SODIUM CHANNEL alpha subunit.
A mutation in which a codon is mutated to one directing the incorporation of a different amino acid. This substitution may result in an inactive or unstable product. (From A Dictionary of Genetics, King & Stansfield, 5th ed)
Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety.
A substituted benzamide used for its prokinetic properties. It is used in the management of gastroesophageal reflux disease, functional dyspepsia, and other disorders associated with impaired gastrointestinal motility. (Martindale The Extra Pharmacopoeia, 31st ed)
Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.
The removal or interruption of some part of the sympathetic nervous system for therapeutic or research purposes.
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.
Antihistamine drug now withdrawn from the market in many countries because of rare but potentially fatal side effects.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.
A potent anti-arrhythmia agent, effective in a wide range of ventricular and atrial ARRHYTHMIAS and TACHYCARDIAS.
A congenital anomaly of the hand or foot, marked by the webbing between adjacent fingers or toes. Syndactylies are classified as complete or incomplete by the degree of joining. Syndactylies can also be simple or complex. Simple syndactyly indicates joining of only skin or soft tissue; complex syndactyly marks joining of bony elements.
Detection of a MUTATION; GENOTYPE; KARYOTYPE; or specific ALLELES associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing.
A non-selective beta-adrenergic antagonist with a long half-life, used in cardiovascular disease to treat arrhythmias, angina pectoris, and hypertension. Nadolol is also used for MIGRAINE DISORDERS and for tremor.
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
A type of cardiac arrhythmia with premature contractions of the HEART VENTRICLES. It is characterized by the premature QRS complex on ECG that is of abnormal shape and great duration (generally >129 msec). It is the most common form of all cardiac arrhythmias. Premature ventricular complexes have no clinical significance except in concurrence with heart diseases.
An abnormally rapid ventricular rhythm usually in excess of 150 beats per minute. It is generated within the ventricle below the BUNDLE OF HIS, either as autonomic impulse formation or reentrant impulse conduction. Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide QRS complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (AV dissociation).
The hollow, muscular organ that maintains the circulation of the blood.
Compounds based on N-phenylacetamide, that are similar in structure to 2-PHENYLACETAMIDES. They are precursors of many other compounds. They were formerly used as ANALGESICS and ANTIPYRETICS, but often caused lethal METHEMOGLOBINEMIA.
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.
Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.
Method in which prolonged electrocardiographic recordings are made on a portable tape recorder (Holter-type system) or solid-state device ("real-time" system), while the patient undergoes normal daily activities. It is useful in the diagnosis and management of intermittent cardiac arrhythmias and transient myocardial ischemia.
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
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.
The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.
Implantable devices which continuously monitor the electrical activity of the heart and automatically detect and terminate ventricular tachycardia (TACHYCARDIA, VENTRICULAR) and VENTRICULAR FIBRILLATION. They consist of an impulse generator, batteries, and electrodes.
A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.
Biochemical identification of mutational changes in a nucleotide sequence.
A chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21. Clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, Brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, Simian crease, and moderate to severe INTELLECTUAL DISABILITY. Cardiac and gastrointestinal malformations, a marked increase in the incidence of LEUKEMIA, and the early onset of ALZHEIMER DISEASE are also associated with this condition. Pathologic features include the development of NEUROFIBRILLARY TANGLES in neurons and the deposition of AMYLOID BETA-PROTEIN, similar to the pathology of ALZHEIMER DISEASE. (Menkes, Textbook of Child Neurology, 5th ed, p213)
A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.
A cluster of metabolic risk factors for CARDIOVASCULAR DISEASES and TYPE 2 DIABETES MELLITUS. The major components of metabolic syndrome X include excess ABDOMINAL FAT; atherogenic DYSLIPIDEMIA; HYPERTENSION; HYPERGLYCEMIA; INSULIN RESISTANCE; a proinflammatory state; and a prothrombotic (THROMBOSIS) state. (from AHA/NHLBI/ADA Conference Proceedings, Circulation 2004; 109:551-556)
A long-acting calcium-blocking agent with significant anti-anginal activity. The drug produces significant coronary vasodilation and modest peripheral effects. It has antihypertensive and selective anti-arrhythmia activities and acts as a calmodulin antagonist.
The abrupt cessation of all vital bodily functions, manifested by the permanent loss of total cerebral, respiratory, and cardiovascular functions.
A cell line generated from human embryonic kidney cells that were transformed with human adenovirus type 5.
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
A group of slow opening and closing voltage-gated potassium channels. Because of their delayed activation kinetics they play an important role in controlling ACTION POTENTIAL duration.
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.
An individual having different alleles at one or more loci regarding a specific character.
A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.
A derivative of the NIACINAMIDE that is structurally combined with an organic nitrate. It is a potassium-channel opener that causes vasodilatation of arterioles and large coronary arteries. Its nitrate-like properties produce venous vasodilation through stimulation of guanylate cyclase.
An alpha-1 adrenergic agonist that causes prolonged peripheral VASOCONSTRICTION.
An adrenergic beta-antagonist that is used in the treatment of life-threatening arrhythmias.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.
Venoms from jellyfish; CORALS; SEA ANEMONES; etc. They contain hemo-, cardio-, dermo- , and neuro-toxic substances and probably ENZYMES. They include palytoxin, sarcophine, and anthopleurine.
The health status of the family as a unit including the impact of the health of one member of the family on the family as a unit and on individual family members; also, the impact of family organization or disorganization on the health status of its members.
A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.
Variation in a population's DNA sequence that is detected by determining alterations in the conformation of denatured DNA fragments. Denatured DNA fragments are allowed to renature under conditions that prevent the formation of double-stranded DNA and allow secondary structure to form in single stranded fragments. These fragments are then run through polyacrylamide gels to detect variations in the secondary structure that is manifested as an alteration in migration through the gels.
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.
Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.
Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.
The abrupt and unexplained death of an apparently healthy infant under one year of age, remaining unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history. (Pediatr Pathol 1991 Sep-Oct;11(5):677-84)
The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.
An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.
The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)
Any one of five terminal digits of the vertebrate FOOT.
An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.
I'm sorry for any confusion, but "Utah" is a proper noun and refers to a state in the United States, it does not have a medical definition. If you have any medical questions or need information on specific medical conditions or terms, I would be happy to help!
Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.
The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.
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.
An infant during the first month after birth.
A phenomenon that is observed when a small subgroup of a larger POPULATION establishes itself as a separate and isolated entity. The subgroup's GENE POOL carries only a fraction of the genetic diversity of the parental population resulting in an increased frequency of certain diseases in the subgroup, especially those diseases known to be autosomal recessive.
A family of hexahydropyridines.
The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.
A condition characterized by severe PROTEINURIA, greater than 3.5 g/day in an average adult. The substantial loss of protein in the urine results in complications such as HYPOPROTEINEMIA; generalized EDEMA; HYPERTENSION; and HYPERLIPIDEMIAS. Diseases associated with nephrotic syndrome generally cause chronic kidney dysfunction.
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).
Abnormally low potassium concentration in the blood. It may result from potassium loss by renal secretion or by the gastrointestinal route, as by vomiting or diarrhea. It may be manifested clinically by neuromuscular disorders ranging from weakness to paralysis, by electrocardiographic abnormalities (depression of the T wave and elevation of the U wave), by renal disease, and by gastrointestinal disorders. (Dorland, 27th ed)
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.

Genomic organization of the KCNQ1 K+ channel gene and identification of C-terminal mutations in the long-QT syndrome. (1/1293)

The voltage-gated K+ channel KVLQT1 is essential for the repolarization phase of the cardiac action potential and for K+ homeostasis in the inner ear. Mutations in the human KCNQ1 gene encoding the alpha subunit of the KVLQT1 channel cause the long-QT syndrome (LQTS). The autosomal dominant form of this cardiac disease, the Romano-Ward syndrome, is characterized by a prolongation of the QT interval, ventricular arrhythmias, and sudden death. The autosomal recessive form, the Jervell and Lange-Nielsen syndrome, also includes bilateral deafness. In the present study, we report the entire genomic structure of KCNQ1, which consists of 19 exons spanning 400 kb on chromosome 11p15.5. We describe the sequences of exon-intron boundaries and oligonucleotide primers that allow polymerase chain reaction (PCR) amplification of exons from genomic DNA. Two new (CA)n repeat microsatellites were found in introns 10 and 14. The present study provides helpful tools for the linkage analysis and mutation screening of the complete KCNQ1 gene. By use of these tools, five novel mutations were identified in LQTS patients by PCR-single-strand conformational polymorphism (SSCP) analysis in the C-terminal part of KCNQ1: two missense mutations, a 20-bp and 1-bp deletions, and a 1-bp insertion. Such mutations in the C-terminal domain of the gene may be more frequent than previously expected, because this region has not been analyzed so far. This could explain the low percentage of mutations found in large LQTS cohorts.  (+info)

Ion channels: structure of a molecular brake. (2/1293)

A combination of crystallographic and mutagenesis studies on the HERG K+ channel, a key determinant of cardiac excitability, has suggested how the protein's extramembraneous amino-terminal domain might act as a 'molecular brake' that slows down channel deactivation.  (+info)

Homozygous deletion in KVLQT1 associated with Jervell and Lange-Nielsen syndrome. (3/1293)

BACKGROUND: Long-QT (LQT) syndrome is a cardiac disorder that causes syncope, seizures, and sudden death from ventricular arrhythmias, specifically torsade de pointes. Both autosomal dominant LQT (Romano-Ward syndrome) and autosomal recessive LQT (Jervell and Lange-Nielsen syndrome, JLNS) have been reported. Heterozygous mutations in 3 potassium channel genes, KVLQT1, KCNE1 (minK), and HERG, and the cardiac sodium channel gene SCN5A cause autosomal dominant LQT. Autosomal recessive LQT, which is associated with deafness, has been found to occur with homozygous mutations in KVLQT1 and KCNE1 in JLNS families in which QTc prolongation was inherited as a dominant trait. METHODS AND RESULTS: An Amish family with clinical evidence of JLNS was analyzed for mutations by use of single-strand conformation polymorphism and DNA sequencing analyses for mutations in all known LQT genes. A novel homozygous 2-bp deletion in the S2 transmembrane segment of KVLQT1 was identified in affected members of this Amish family in which both QTc prolongation and deafness were inherited as recessive traits. This deletion represents a new JLNS-associated mutation in KVLQT1 and has deleterious effects on the KVLQT1 potassium channel, causing a frameshift and the truncation of the KVLQT1 protein. In contrast to previous reports in which LQT was inherited as a clear dominant trait, 2 parents in the JLNS family described here have normal QTc intervals (0.43 and 0.44 seconds, respectively). CONCLUSIONS: A novel homozygous KVLQT1 mutation causes JLNS in an Amish family with deafness that is inherited as an autosomal recessive trait.  (+info)

C-terminal HERG mutations: the role of hypokalemia and a KCNQ1-associated mutation in cardiac event occurrence. (4/1293)

BACKGROUND: The long-QT syndrome (LQTS) is a genetically heterogeneous disease in which 4 genes encoding ion-channel subunits have been identified. Most of the mutations have been determined in the transmembrane domains of the cardiac potassium channel genes KCNQ1 and HERG. In this study, we investigated the 3' part of HERG for mutations. METHODS AND RESULTS: New specific primers allowed the amplification of the 3' part of HERG, the identification of 2 missense mutations, S818L and V822 M, in the putative cyclic nucleotide binding domain, and a 1-bp insertion, 3108+1G. Hypokalemia was a triggering factor for torsade de pointes in 2 of the probands of these families. Lastly, in a large family, a maternally inherited G to A transition was found in the splicing donor consensus site of HERG, 2592+1G-A, and a paternally inherited mutation, A341E, was identified in KCNQ1. The 2 more severely affected sisters bore both mutations. CONCLUSIONS: The discovery of mutations in the C-terminal part of HERG emphasizes that this region plays a significant role in cardiac repolarization. Clinical data suggests that these mutations may be less malignant than mutations occurring in the pore region, but they can become clinically significant in cases of hypokalemia. The first description of 2 patients with double heterozygosity associated with a dramatic malignant phenotype implies that genetic analysis of severely affected young patients should include an investigation for >1 mutation in the LQT genes.  (+info)

Cellular and ionic basis for T-wave alternans under long-QT conditions. (5/1293)

BACKGROUND: T-wave alternans (TWA), an ECG phenomenon characterized by beat-to-beat alternation of the morphology, amplitude, and/or polarity of the T wave, is commonly observed in the acquired and congenital long-QT syndromes (LQTS). This study examines the cellular and ionic basis for TWA induced by rapid pacing under conditions mimicking the LQT3 form of the congenital LQTS in an arterially perfused canine left ventricular wedge preparation. METHODS AND RESULTS: Transmembrane action potentials from epicardial, M, and endocardial cells and 6 to 8 intramural unipolar electrograms were simultaneously recorded together with a transmural ECG and isometric tension development. In the presence of sea anemone toxin (ATX-II; 20 nmol/L), an increase in pacing rate (from a cycle length [CL] of 500 to 400 to 250 ms) produced a wide spectrum of T-wave and mechanical alternans. Acceleration to CLs of 400 to 300 ms produced mild to moderate TWA principally due to beat-to-beat alternation of repolarization of cells in the M region. Transmural dispersion of repolarization during alternans was exaggerated during alternate beats. Acceleration to CLs of 300 to 250 ms caused more pronounced beat-to-beat alternation of action potential duration (APD) of the M cell, resulting in a reversal of repolarization sequence across the ventricular wall, leading to alternation in the polarity of the T wave. The peak of the negative T waves coincided with repolarization of the M region, whereas the end of the negative T wave coincided with the repolarization of epicardium. In almost all cases, electrical alternans was concordant with mechanical alternans. Torsade de pointes occurred after an abrupt acceleration of CL, which was associated with marked TWA. Both ryanodine and low [Ca2+]o completely suppressed alternans of the T wave, APD, and contraction, suggesting a critical role for intracellular Ca2+ cycling in the maintenance of TWA. CONCLUSIONS: Our results suggest that TWA observed at rapid rates under long-QT conditions is largely the result of alternation of the M-cell APD, leading to exaggeration of transmural dispersion of repolarization during alternate beats, and thus the potential for development of torsade de pointes. Our data also suggest that unlike transient forms of TWA that damp out quickly and depend on electrical restitution factors, the steady-state electrical and mechanical alternans demonstrated in this study appears to be largely the result of beat-to-beat alternans of [Ca2+]i.  (+info)

Mutations in a dominant-negative isoform correlate with phenotype in inherited cardiac arrhythmias. (6/1293)

The long QT syndrome is characterized by prolonged cardiac repolarization and a high risk of sudden death. Mutations in the KCNQ1 gene, which encodes the cardiac KvLQT1 potassium ion (K+) channel, cause both the autosomal dominant Romano-Ward (RW) syndrome and the recessive Jervell and Lange-Nielsen (JLN) syndrome. JLN presents with cardiac arrhythmias and congenital deafness, and heterozygous carriers of JLN mutations exhibit a very mild cardiac phenotype. Despite the phenotypic differences between heterozygotes with RW and those with JLN mutations, both classes of variant protein fail to produce K+ currents in cultured cells. We have shown that an N-terminus-truncated KvLQT1 isoform endogenously expressed in the human heart exerts strong dominant-negative effects on the full-length KvLQT1 protein. Because RW and JLN mutations concern both truncated and full-length KvLQT1 isoforms, we investigated whether RW or JLN mutations would have different impacts on the dominant-negative properties of the truncated KvLQT1 splice variant. In a mammalian expression system, we found that JLN, but not RW, mutations suppress the dominant-negative effects of the truncated KvLQT1. Thus, in JLN heterozygous carriers, the full-length KvLQT1 protein encoded by the unaffected allele should not be subject to the negative influence of the mutated truncated isoform, leaving some cardiac K+ current available for repolarization. This is the first report of a genetic disease in which the impact of a mutation on a dominant-negative isoform correlates with the phenotype.  (+info)

Prolonged QT interval predicts cardiac and all-cause mortality in the elderly. The Rotterdam Study. (7/1293)

AIMS: To examine the association between heart-rate corrected QT prolongation and cardiac and all-cause mortality in the population-based Rotterdam Study among men and women aged 55 years or older and to compare the prognostic value of the QT interval, using different formulas to correct for heart rate. METHODS AND RESULTS: After exclusion of participants with arrhythmias or bundle branch block on the ECG, the study population consisted of 2083 men and 3158 women. The QT interval was computed by the Modular ECG Analysis System (MEANS). Data were analysed using Cox' proportional hazards model. Participants in the highest quartile of the heart-rate corrected QT interval had about a 70% age- and sex-adjusted increased risk for both all-cause mortality (hazard ratio (HR) 1.8; 95% CI:1.3-2.4) and cardiac mortality (HR 1.7; 95% CI:1.0-2.7) compared to those in the lowest quartile. In women, the increased risk associated with prolonged QT for cardiac death was more pronounced than in men. These risk estimates did not change after adjustment for potential confounders, including history of myocardial infarction, hypertension and diabetes mellitus. CONCLUSION: A prolonged heart-rate corrected QT interval is an independent predictor for cardiac and all-cause mortality in older men and women. The risk associated with prolonged QT is hardly affected by the heart-rate correction formula used.  (+info)

Long QT syndrome-associated mutations in the Per-Arnt-Sim (PAS) domain of HERG potassium channels accelerate channel deactivation. (8/1293)

Mutations in the human ether-a-go-go-related gene (HERG) cause long QT syndrome, an inherited disorder of cardiac repolarization that predisposes affected individuals to life-threatening arrhythmias. HERG encodes the cardiac rapid delayed rectifier potassium channel that mediates repolarization of ventricular action potentials. In this study, we used the oocyte expression system and voltage clamp techniques to determine the functional consequences of eight long QT syndrome-associated mutations located in the amino-terminal region of HERG (F29L, N33T, G53R, R56Q, C66G, H70R, A78P, and L86R). Mutant subunits formed functional channels with altered gating properties when expressed alone in oocytes. Deactivation was accelerated by all mutations. Some mutants shifted the voltage dependence of channel availability to more positive potentials. Voltage ramps indicated that fast deactivation of mutant channels would reduce outward current during the repolarization phase of the cardiac action potential and cause prolongation of the corrected QT interval, QTc. The amino-terminal region of HERG was recently crystallized and shown to possess a Per-Arnt-Sim (PAS) domain. The location of these mutations suggests they may disrupt the PAS domain and interfere with its interaction with the S4-S5 linker of the HERG channel.  (+info)

Long QT syndrome (LQTS) is a cardiac electrical disorder characterized by a prolonged QT interval on the electrocardiogram (ECG), which can potentially trigger rapid, chaotic heartbeats known as ventricular tachyarrhythmias, such as torsades de pointes. These arrhythmias can be life-threatening and lead to syncope (fainting) or sudden cardiac death. LQTS is often congenital but may also be acquired due to certain medications, medical conditions, or electrolyte imbalances. It's essential to identify and manage LQTS promptly to reduce the risk of severe complications.

The KCNQ1 potassium channel, also known as the Kv7.1 channel, is a voltage-gated potassium ion channel that plays a crucial role in the regulation of electrical excitability in cardiac myocytes and inner ear epithelial cells. In the heart, it helps to control the duration and frequency of action potentials, thereby contributing to the maintenance of normal cardiac rhythm. Mutations in the KCNQ1 gene can lead to various cardiac disorders, such as long QT syndrome type 1 and familial atrial fibrillation. In the inner ear, it helps regulate potassium homeostasis and is essential for hearing and balance functions. Dysfunction of this channel has been linked to deafness and balance disorders.

Ether-à-go-go (EAG) potassium channels are a type of voltage-gated potassium channel that are widely expressed in the heart, brain, and other tissues. They are named after the ethereal dance movements observed in fruit flies with mutations in these channels.

EAG potassium channels play important roles in regulating electrical excitability and signaling in excitable cells. In the heart, they help to control the duration of the action potential and the refractory period, which is critical for maintaining normal heart rhythm. In the brain, they are involved in regulating neuronal excitability and neurotransmitter release.

Mutations in EAG potassium channels have been associated with various human diseases, including cardiac arrhythmias, epilepsy, and bipolar disorder. The medical definition of "Ether-A-Go-Go Potassium Channels" refers to the genetic components that make up these channels and their role in physiological processes and disease states.

Torsades de Pointes is a type of polymorphic ventricular tachycardia, characterized by a distinct pattern on the electrocardiogram (ECG) where the QRS complexes appear to twist around the isoelectric line. This condition is often associated with a prolonged QT interval, which can be congenital or acquired due to various factors such as medications, electrolyte imbalances, or heart diseases. Torsades de Pointes can degenerate into ventricular fibrillation, leading to sudden cardiac death if not promptly treated.

Voltage-gated potassium channels are a type of ion channel found in the membrane of excitable cells such as nerve and muscle cells. They are called "voltage-gated" because their opening and closing is regulated by the voltage, or electrical potential, across the cell membrane. Specifically, these channels are activated when the membrane potential becomes more positive, a condition that occurs during the action potential of a neuron or muscle fiber.

When voltage-gated potassium channels open, they allow potassium ions (K+) to flow out of the cell down their electrochemical gradient. This outward flow of K+ ions helps to repolarize the membrane, bringing it back to its resting potential after an action potential has occurred. The precise timing and duration of the opening and closing of voltage-gated potassium channels is critical for the normal functioning of excitable cells, and abnormalities in these channels have been linked to a variety of diseases, including cardiac arrhythmias, epilepsy, and neurological disorders.

KCNQ potassium channels, also known as Kv7 channels, are a type of voltage-gated potassium channel that play important roles in regulating electrical excitability in various tissues, including the heart and nervous system. These channels are composed of several subunits, typically formed by combinations of KCNQ1 to KCNQ5 proteins, which form a pore through which potassium ions can flow in response to changes in membrane voltage.

KCNQ channels are characterized by their slow activation and deactivation kinetics, which contribute to their role in setting the resting membrane potential and modulating the frequency of action potentials in neurons. In the heart, KCNQ channels help to regulate the duration of the cardiac action potential and are therefore important for maintaining normal heart rhythm.

Mutations in KCNQ channel genes have been associated with a variety of inherited disorders, including long QT syndrome, a condition characterized by abnormalities in the electrical repolarization of the heart that can lead to life-threatening arrhythmias. Other diseases associated with KCNQ channel dysfunction include epilepsy, migraine, and various forms of hearing loss.

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

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

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

Romano-Ward syndrome, also known as Long QT syndrome type 1 or Jervell and Lange-Nielsen syndrome type 2, is a genetic disorder characterized by a prolongation of the QT interval on the electrocardiogram (ECG). The QT interval represents the time it takes for the heart muscle to electrically activate and then recover, or repolarize. A prolonged QT interval can cause chaotic and rapid heartbeats (ventricular tachycardia) that may lead to fainting, seizures, or sudden death.

Romano-Ward syndrome is typically inherited in an autosomal dominant manner, meaning that a person has a 50% chance of inheriting the gene mutation from an affected parent. In contrast, Jervell and Lange-Nielsen syndrome type 2 is inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated to cause the disorder.

Romano-Ward syndrome is caused by mutations in genes that encode for ion channels in the heart muscle cells. These channels control the flow of ions (such as sodium, potassium, and calcium) into and out of the cells, which is necessary for normal electrical activity. Mutations in these genes can disrupt the balance of ions and lead to abnormalities in the electrical activity of the heart, resulting in a prolonged QT interval.

Symptoms of Romano-Ward syndrome may include palpitations, fainting, seizures, or sudden death. The severity of the symptoms can vary widely, even among family members with the same genetic mutation. Treatment typically involves medications to help regulate the heart's electrical activity and prevent ventricular tachycardia. In some cases, an implantable cardioverter-defibrillator (ICD) may be recommended to monitor and correct abnormal heart rhythms.

A syndrome, in medical terms, is a set of symptoms that collectively indicate or characterize a disease, disorder, or underlying pathological process. It's essentially a collection of signs and/or symptoms that frequently occur together and can suggest a particular cause or condition, even though the exact physiological mechanisms might not be fully understood.

For example, Down syndrome is characterized by specific physical features, cognitive delays, and other developmental issues resulting from an extra copy of chromosome 21. Similarly, metabolic syndromes like diabetes mellitus type 2 involve a group of risk factors such as obesity, high blood pressure, high blood sugar, and abnormal cholesterol or triglyceride levels that collectively increase the risk of heart disease, stroke, and diabetes.

It's important to note that a syndrome is not a specific diagnosis; rather, it's a pattern of symptoms that can help guide further diagnostic evaluation and management.

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

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

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

Mexiletine is defined as an antiarrhythmic agent, classified as a Class IB medication. It works by blocking sodium channels in the heart, which helps to stabilize cardiac membranes and reduces the rate of firing of cardiac cells. This makes it useful for treating certain types of irregular heart rhythms (ventricular arrhythmias).

Mexiletine is also known to have analgesic properties and is sometimes used off-label for the treatment of neuropathic pain. It is available in oral form, and its use should be under the close supervision of a healthcare provider due to its potential side effects, which can include gastrointestinal symptoms, dizziness, tremors, and cardiac arrhythmias.

Syncope is a medical term defined as a transient, temporary loss of consciousness and postural tone due to reduced blood flow to the brain. It's often caused by a drop in blood pressure, which can be brought on by various factors such as dehydration, emotional stress, prolonged standing, or certain medical conditions like heart diseases, arrhythmias, or neurological disorders.

During a syncope episode, an individual may experience warning signs such as lightheadedness, dizziness, blurred vision, or nausea before losing consciousness. These episodes usually last only a few minutes and are followed by a rapid, full recovery. However, if left untreated or undiagnosed, recurrent syncope can lead to severe injuries from falls or even life-threatening conditions related to the underlying cause.

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

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

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

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

There are several types of cardiac arrhythmias, including:

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

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

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

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

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

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

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

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

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

Jervell-Lange Nielsen Syndrome (JLNS) is a rare inherited disorder characterized by the combination of congenital deafness and prolongation of the QT interval on an electrocardiogram (ECG), which can lead to life-threatening cardiac arrhythmias. It is caused by mutations in the KCNQ1 or KCNE1 genes, which are responsible for the potassium ion channels in the heart that help maintain a regular heart rhythm.

There are two types of JLNS: type 1 and type 2. Type 1 is characterized by profound congenital deafness and severe, life-threatening cardiac arrhythmias, while type 2 has less severe hearing loss and fewer cardiac complications. The syndrome can be diagnosed through genetic testing and ECG monitoring. Treatment typically involves the use of beta blockers to regulate heart rhythm, as well as the implementation of measures to manage the risk of sudden death, such as the implantation of a pacemaker or defibrillator.

Potassium channels are membrane proteins that play a crucial role in regulating the electrical excitability of cells, including cardiac, neuronal, and muscle cells. These channels facilitate the selective passage of potassium ions (K+) across the cell membrane, maintaining the resting membrane potential and shaping action potentials. They are composed of four or six subunits that assemble to form a central pore through which potassium ions move down their electrochemical gradient. Potassium channels can be modulated by various factors such as voltage, ligands, mechanical stimuli, or temperature, allowing cells to fine-tune their electrical properties and respond to different physiological demands. Dysfunction of potassium channels has been implicated in several diseases, including cardiac arrhythmias, epilepsy, and neurodegenerative disorders.

Cation transport proteins are a type of membrane protein that facilitate the movement of cations (positively charged ions) across biological membranes. These proteins play a crucial role in maintaining ion balance and electrical excitability within cells, as well as in various physiological processes such as nutrient uptake, waste elimination, and signal transduction.

There are several types of cation transport proteins, including:

1. Ion channels: These are specialized protein structures that form a pore or channel through the membrane, allowing ions to pass through rapidly and selectively. They can be either voltage-gated or ligand-gated, meaning they open in response to changes in electrical potential or binding of specific molecules, respectively.

2. Ion pumps: These are active transport proteins that use energy from ATP hydrolysis to move ions against their electrochemical gradient, effectively pumping them from one side of the membrane to the other. Examples include the sodium-potassium pump (Na+/K+-ATPase) and calcium pumps (Ca2+ ATPase).

3. Ion exchangers: These are antiporter proteins that facilitate the exchange of one ion for another across the membrane, maintaining electroneutrality. For example, the sodium-proton exchanger (NHE) moves a proton into the cell in exchange for a sodium ion being moved out.

4. Symporters: These are cotransporter proteins that move two or more ions together in the same direction, often coupled with the transport of a solute molecule. An example is the sodium-glucose cotransporter (SGLT), which facilitates glucose uptake into cells by coupling its movement with that of sodium ions.

Collectively, cation transport proteins help maintain ion homeostasis and contribute to various cellular functions, including electrical signaling, enzyme regulation, and metabolic processes. Dysfunction in these proteins can lead to a range of diseases, such as neurological disorders, cardiovascular disease, and kidney dysfunction.

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

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

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

Channelopathies are genetic disorders that are caused by mutations in the genes that encode for ion channels. Ion channels are specialized proteins that regulate the flow of ions, such as sodium, potassium, and calcium, across cell membranes. These ion channels play a crucial role in various physiological processes, including the generation and transmission of electrical signals in the body.

Channelopathies can affect various organs and systems in the body, depending on the type of ion channel that is affected. For example, mutations in sodium channel genes can cause neuromuscular disorders such as epilepsy, migraine, and periodic paralysis. Mutations in potassium channel genes can cause cardiac arrhythmias, while mutations in calcium channel genes can cause neurological disorders such as episodic ataxia and hemiplegic migraine.

The symptoms of channelopathies can vary widely depending on the specific disorder and the severity of the mutation. Treatment typically involves managing the symptoms and may include medications, lifestyle modifications, or in some cases, surgery.

Brugada Syndrome is a genetic disorder characterized by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death. It is typically caused by a mutation in the SCN5A gene, which encodes for a sodium channel protein in the heart. This mutation can lead to abnormal ion transport in the heart cells, causing changes in the electrical activity of the heart that can trigger dangerous arrhythmias.

The ECG findings associated with Brugada Syndrome include a distinct pattern of ST-segment elevation in the right precordial leads (V1-V3), which can appear spontaneously or be induced by certain medications. The syndrome is often classified into two types based on the presence or absence of symptoms:

* Type 1 Brugada Syndrome: This type is characterized by a coved-type ST-segment elevation of at least 2 mm in height in at least one right precordial lead, with a negative T wave. This pattern must be present to make the diagnosis, and it should not be transient or induced by any medication or condition. Type 1 Brugada Syndrome is associated with a higher risk of sudden cardiac death.
* Type 2 Brugada Syndrome: This type is characterized by a saddleback-type ST-segment elevation of at least 2 mm in height in at least one right precordial lead, with a positive or biphasic T wave. The ST segment should return to the baseline level or below within 0.08 seconds after the J point (the junction between the QRS complex and the ST segment). Type 2 Brugada Syndrome is associated with a lower risk of sudden cardiac death compared to Type 1, but it can still pose a significant risk in some individuals.

Brugada Syndrome can affect people of any age, gender, or ethnicity, although it is more commonly diagnosed in middle-aged men of Asian descent. The syndrome can be inherited in an autosomal dominant manner, meaning that a child has a 50% chance of inheriting the mutation from a parent who carries the gene. However, not all individuals with the genetic mutation will develop symptoms or have abnormal ECG findings.

Treatment for Brugada Syndrome typically involves implanting a cardioverter-defibrillator (ICD) to prevent sudden cardiac death. Medications such as quinidine or isoproterenol may also be used to reduce the risk of arrhythmias. Lifestyle modifications, such as avoiding alcohol and certain medications that can trigger arrhythmias, may also be recommended.

A missense mutation is a type of point mutation in which a single nucleotide change results in the substitution of a different amino acid in the protein that is encoded by the affected gene. This occurs when the altered codon (a sequence of three nucleotides that corresponds to a specific amino acid) specifies a different amino acid than the original one. The function and/or stability of the resulting protein may be affected, depending on the type and location of the missense mutation. Missense mutations can have various effects, ranging from benign to severe, depending on the importance of the changed amino acid for the protein's structure or function.

Adrenergic beta-antagonists, also known as beta blockers, are a class of medications that block the effects of adrenaline and noradrenaline (also known as epinephrine and norepinephrine) on beta-adrenergic receptors. These receptors are found in various tissues throughout the body, including the heart, lungs, and blood vessels.

Beta blockers work by binding to these receptors and preventing the activation of certain signaling pathways that lead to increased heart rate, force of heart contractions, and relaxation of blood vessels. As a result, beta blockers can lower blood pressure, reduce heart rate, and decrease the workload on the heart.

Beta blockers are used to treat a variety of medical conditions, including hypertension (high blood pressure), angina (chest pain), heart failure, irregular heart rhythms, migraines, and certain anxiety disorders. Some common examples of beta blockers include metoprolol, atenolol, propranolol, and bisoprolol.

It is important to note that while beta blockers can have many benefits, they can also cause side effects such as fatigue, dizziness, and shortness of breath. Additionally, sudden discontinuation of beta blocker therapy can lead to rebound hypertension or worsening chest pain. Therefore, it is important to follow the dosing instructions provided by a healthcare provider carefully when taking these medications.

Cisapride is a medication that was used to treat gastrointestinal motility disorders, such as gastroparesis and constipation. It belongs to a class of drugs called "prokinetic agents" which work by increasing the contractions or movements of the muscles in the digestive tract, thereby helping to move food and waste through the system more efficiently.

Cisapride was first approved for use in the United States in 1993, but its use was later restricted due to concerns about serious side effects, including cardiac arrhythmias (irregular heartbeats) and interactions with other medications. In 2000, the U.S. Food and Drug Administration (FDA) requested that cisapride be withdrawn from the market due to these safety concerns.

While cisapride is no longer available for use in many countries, it may still be used in some cases under strict guidelines and monitoring conditions. It is important to note that the use of cisapride should only be initiated and monitored by a healthcare professional, and patients should inform their doctor about all other medications they are taking to avoid potential interactions.

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

There are several potential causes of bradycardia, including:

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

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

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

Sympathectomy is a surgical procedure that involves interrupting the sympathetic nerve pathways. These nerves are part of the autonomic nervous system, which controls involuntary bodily functions such as heart rate, blood pressure, sweating, and digestion. The goal of sympathectomy is to manage conditions like hyperhidrosis (excessive sweating), Raynaud's phenomenon, and certain types of chronic pain.

There are different types of sympathectomy, including thoracic sympathectomy (which targets the sympathetic nerves in the chest), lumbar sympathectomy (which targets the sympathetic nerves in the lower back), and cervical sympathectomy (which targets the sympathetic nerves in the neck). The specific type of procedure depends on the location of the affected nerves and the condition being treated.

Sympathectomy is usually performed using minimally invasive techniques, such as endoscopic surgery, which involves making small incisions and using specialized instruments to access the nerves. While sympathectomy can be effective in managing certain conditions, it carries risks such as nerve damage, bleeding, infection, and chronic pain.

Cardiac arrest, also known as heart arrest, is a medical condition where the heart suddenly stops beating or functioning properly. This results in the cessation of blood flow to the rest of the body, including the brain, leading to loss of consciousness and pulse. Cardiac arrest is often caused by electrical disturbances in the heart that disrupt its normal rhythm, known as arrhythmias. If not treated immediately with cardiopulmonary resuscitation (CPR) and defibrillation, it can lead to death or permanent brain damage due to lack of oxygen supply. It's important to note that a heart attack is different from cardiac arrest; a heart attack occurs when blood flow to a part of the heart is blocked, often by a clot, causing damage to the heart muscle, but the heart continues to beat. However, a heart attack can sometimes trigger a cardiac arrest.

Astemizole is a second-generation antihistamine that was previously used to treat symptoms associated with allergies, such as hay fever, hives, and other allergic skin reactions. It works by blocking the action of histamine, a substance in the body that causes allergic symptoms. However, astemizole has been withdrawn from the market in many countries due to rare but serious side effects on the heart.

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

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

Flecainide is an antiarrhythmic medication used to regularize abnormal heart rhythms, specifically certain types of irregular heartbeats called ventricular arrhythmias and paroxysmal atrial tachycardia/atrial fibrillation. It works by blocking sodium channels in the heart, which helps to slow down the conduction of electrical signals and reduces the likelihood of erratic heart rhythms.

Flecainide is available in oral forms such as tablets or capsules and is typically prescribed under the supervision of a healthcare professional experienced in managing heart rhythm disorders. It's important to note that flecainide can have serious side effects, including increasing the risk of dangerous arrhythmias in some patients, so it should only be used under close medical monitoring.

This definition is for informational purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment. If you have any questions about your medications or health conditions, please consult with your healthcare provider.

Syndactyly is a congenital condition where two or more digits (fingers or toes) are fused together. It can occur in either the hand or foot, and it can involve fingers or toes on both sides of the hand or foot. The fusion can be partial, where only the skin is connected, or complete, where the bones are also connected. Syndactyly is usually noticed at birth and can be associated with other genetic conditions or syndromes. Surgical intervention may be required to separate the digits and improve function and appearance.

Genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a genetic disorder. Genetic tests are performed on a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or other tissue. For example, a physician may recommend genetic testing to help diagnose a genetic condition, confirm the presence of a gene mutation known to increase the risk of developing certain cancers, or determine the chance for a couple to have a child with a genetic disorder.

There are several types of genetic tests, including:

* Diagnostic testing: This type of test is used to identify or confirm a suspected genetic condition in an individual. It may be performed before birth (prenatal testing) or at any time during a person's life.
* Predictive testing: This type of test is used to determine the likelihood that a person will develop a genetic disorder. It is typically offered to individuals who have a family history of a genetic condition but do not show any symptoms themselves.
* Carrier testing: This type of test is used to determine whether a person carries a gene mutation for a genetic disorder. It is often offered to couples who are planning to have children and have a family history of a genetic condition or belong to a population that has an increased risk of certain genetic disorders.
* Preimplantation genetic testing: This type of test is used in conjunction with in vitro fertilization (IVF) to identify genetic changes in embryos before they are implanted in the uterus. It can help couples who have a family history of a genetic disorder or who are at risk of having a child with a genetic condition to conceive a child who is free of the genetic change in question.
* Pharmacogenetic testing: This type of test is used to determine how an individual's genes may affect their response to certain medications. It can help healthcare providers choose the most effective medication and dosage for a patient, reducing the risk of adverse drug reactions.

It is important to note that genetic testing should be performed under the guidance of a qualified healthcare professional who can interpret the results and provide appropriate counseling and support.

Nadolol is a non-selective beta blocker medication that works by blocking the action of certain natural substances such as adrenaline (epinephrine) on the heart and blood vessels. This results in a decrease in heart rate, heart contractions strength, and lowering of blood pressure. Nadolol is used to treat high blood pressure, angina (chest pain), irregular heartbeats, and to prevent migraines. It may also be used for other conditions as determined by your doctor.

Nadolol is available in oral tablet form and is typically taken once a day. The dosage will depend on the individual's medical condition, response to treatment, and any other medications they may be taking. Common side effects of Nadolol include dizziness, lightheadedness, tiredness, and weakness. Serious side effects are rare but can occur, such as slow or irregular heartbeat, shortness of breath, swelling of the hands or feet, mental/mood changes, and unusual weight gain.

It is important to follow your doctor's instructions carefully when taking Nadolol, and to inform them of any other medications you are taking, as well as any medical conditions you may have, such as diabetes, asthma, or liver disease. Additionally, it is recommended to avoid sudden discontinuation of the medication without consulting with your healthcare provider, as this can lead to withdrawal symptoms such as increased heart rate and blood pressure.

Patch-clamp techniques are a group of electrophysiological methods used to study ion channels and other electrical properties of cells. These techniques were developed by Erwin Neher and Bert Sakmann, who were awarded the Nobel Prize in Physiology or Medicine in 1991 for their work. The basic principle of patch-clamp techniques involves creating a high resistance seal between a glass micropipette and the cell membrane, allowing for the measurement of current flowing through individual ion channels or groups of channels.

There are several different configurations of patch-clamp techniques, including:

1. Cell-attached configuration: In this configuration, the micropipette is attached to the outer surface of the cell membrane, and the current flowing across a single ion channel can be measured. This configuration allows for the study of the properties of individual channels in their native environment.
2. Whole-cell configuration: Here, the micropipette breaks through the cell membrane, creating a low resistance electrical connection between the pipette and the inside of the cell. This configuration allows for the measurement of the total current flowing across all ion channels in the cell membrane.
3. Inside-out configuration: In this configuration, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the inner surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in isolation from other cellular components.
4. Outside-out configuration: Here, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the outer surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in their native environment, but with the ability to control the composition of the extracellular solution.

Patch-clamp techniques have been instrumental in advancing our understanding of ion channel function and have contributed to numerous breakthroughs in neuroscience, pharmacology, and physiology.

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

Ventricular Premature Complexes (VPCs), also known as Ventricular Extrasystoles or Premature Ventricular Contractions (PVCs), are extra heartbeats that originate in the ventricles, the lower chambers of the heart. These premature beats disrupt the normal sequence of electrical impulses in the heart and cause the ventricles to contract earlier than they should.

VPCs can result in a noticeable "skipped" or "extra" beat sensation, often followed by a stronger beat as the heart returns to its regular rhythm. They may occur occasionally in healthy individuals with no underlying heart condition, but frequent VPCs could indicate an underlying issue such as heart disease, electrolyte imbalance, or digitalis toxicity. In some cases, VPCs can be harmless and require no treatment; however, if they are frequent or associated with structural heart problems, further evaluation and management may be necessary to prevent potential complications like reduced cardiac output or heart failure.

Ventricular Tachycardia (VT) is a rapid heart rhythm that originates from the ventricles, the lower chambers of the heart. It is defined as three or more consecutive ventricular beats at a rate of 120 beats per minute or greater in a resting adult. This abnormal heart rhythm can cause the heart to pump less effectively, leading to inadequate blood flow to the body and potentially life-threatening conditions such as hypotension, shock, or cardiac arrest.

VT can be classified into three types based on its duration, hemodynamic stability, and response to treatment:

1. Non-sustained VT (NSVT): It lasts for less than 30 seconds and is usually well tolerated without causing significant symptoms or hemodynamic instability.
2. Sustained VT (SVT): It lasts for more than 30 seconds, causes symptoms such as palpitations, dizziness, shortness of breath, or chest pain, and may lead to hemodynamic instability.
3. Pulseless VT: It is a type of sustained VT that does not produce a pulse, blood pressure, or adequate cardiac output, requiring immediate electrical cardioversion or defibrillation to restore a normal heart rhythm.

VT can occur in people with various underlying heart conditions such as coronary artery disease, cardiomyopathy, valvular heart disease, congenital heart defects, and electrolyte imbalances. It can also be triggered by certain medications, substance abuse, or electrical abnormalities in the heart. Prompt diagnosis and treatment of VT are crucial to prevent complications and improve outcomes.

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

Acetanilides are a group of chemical compounds that consist of an acetic acid molecule (CH3COO-) linked to aniline (C6H5NH2) through an amide bond (-CONH-). The most well-known member of this class is acetanilide itself (N-phenylacetamide, C8H9NO), which has been used historically as a pain reliever and fever reducer. However, its use in medicine has largely been abandoned due to the discovery of serious side effects, including the potential for causing methemoglobinemia, a condition that can lead to tissue hypoxia and even death.

Acetanilides have also been used as intermediates in the synthesis of other chemical compounds, such as dyes and pharmaceuticals. Some derivatives of acetanilide continue to be used in medicine today, including certain antipyretic and analgesic agents. However, these drugs are carefully designed and tested to minimize the risk of adverse effects associated with acetanilide itself.

Ion channel gating refers to the process by which ion channels in cell membranes open and close in response to various stimuli, allowing ions such as sodium, potassium, and calcium to flow into or out of the cell. This movement of ions is crucial for many physiological processes, including the generation and transmission of electrical signals in nerve cells, muscle contraction, and the regulation of hormone secretion.

Ion channel gating can be regulated by various factors, including voltage changes across the membrane (voltage-gated channels), ligand binding (ligand-gated channels), mechanical stress (mechanosensitive channels), or other intracellular signals (second messenger-gated channels). The opening and closing of ion channels are highly regulated and coordinated processes that play a critical role in maintaining the proper functioning of cells and organ systems.

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

There are three degrees of AV block:

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

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

Ambulatory electrocardiography, also known as ambulatory ECG or Holter monitoring, is a non-invasive method of recording the electrical activity of the heart over an extended period of time (typically 24 hours or more) while the patient goes about their daily activities. The device used to record the ECG is called a Holter monitor, which consists of a small, portable recorder that is attached to the patient's chest with electrodes.

The recorded data provides information on any abnormalities in the heart's rhythm or electrical activity during different stages of activity and rest, allowing healthcare providers to diagnose and evaluate various cardiac conditions such as arrhythmias, ischemia, and infarction. The ability to monitor the heart's activity over an extended period while the patient performs their normal activities provides valuable information that may not be captured during a standard ECG, which only records the heart's electrical activity for a few seconds.

In summary, ambulatory electrocardiography is a diagnostic tool used to evaluate the electrical activity of the heart over an extended period, allowing healthcare providers to diagnose and manage various cardiac conditions.

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

Quinidine is a Class IA antiarrhythmic medication that is primarily used to treat and prevent various types of cardiac arrhythmias (abnormal heart rhythms). It works by blocking the rapid sodium channels in the heart, which helps to slow down the conduction of electrical signals within the heart and stabilize its rhythm.

Quinidine is derived from the bark of the Cinchona tree and has been used for centuries as a treatment for malaria. However, its antiarrhythmic properties were discovered later, and it became an important medication in cardiology.

In addition to its use in treating arrhythmias, quinidine may also be used off-label for other indications such as the treatment of nocturnal leg cramps or myasthenia gravis. It is available in various forms, including tablets and injectable solutions.

It's important to note that quinidine has a narrow therapeutic index, meaning that there is only a small difference between an effective dose and a toxic one. Therefore, it must be carefully monitored to ensure that the patient is receiving a safe and effective dose. Common side effects of quinidine include gastrointestinal symptoms such as nausea, vomiting, and diarrhea, as well as visual disturbances, headache, and dizziness. More serious side effects can include QT prolongation, which can lead to dangerous arrhythmias, and hypersensitivity reactions.

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

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

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

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

Genotype, in genetics, refers to the complete heritable genetic makeup of an individual organism, including all of its genes. It is the set of instructions contained in an organism's DNA for the development and function of that organism. The genotype is the basis for an individual's inherited traits, and it can be contrasted with an individual's phenotype, which refers to the observable physical or biochemical characteristics of an organism that result from the expression of its genes in combination with environmental influences.

It is important to note that an individual's genotype is not necessarily identical to their genetic sequence. Some genes have multiple forms called alleles, and an individual may inherit different alleles for a given gene from each parent. The combination of alleles that an individual inherits for a particular gene is known as their genotype for that gene.

Understanding an individual's genotype can provide important information about their susceptibility to certain diseases, their response to drugs and other treatments, and their risk of passing on inherited genetic disorders to their offspring.

An implantable defibrillator is a medical device that is surgically placed inside the chest to continuously monitor the heart's rhythm and deliver electrical shocks to restore a normal heartbeat when it detects a life-threatening arrhythmia, such as ventricular fibrillation or ventricular tachycardia.

The device consists of a small generator that is implanted in the upper chest, along with one or more electrode leads that are threaded through veins and positioned in the heart's chambers. The generator contains a battery and a microcomputer that constantly monitors the heart's electrical activity and detects any abnormal rhythms.

When an arrhythmia is detected, the defibrillator delivers an electrical shock to the heart to restore a normal rhythm. This can be done automatically by the device or manually by a healthcare provider using an external programmer.

Implantable defibrillators are typically recommended for people who have a high risk of sudden cardiac death due to a history of heart attacks, heart failure, or inherited heart conditions that affect the heart's electrical system. They can significantly reduce the risk of sudden cardiac death and improve quality of life for those at risk.

Potassium channel blockers are a class of medications that work by blocking potassium channels, which are proteins in the cell membrane that control the movement of potassium ions into and out of cells. By blocking these channels, potassium channel blockers can help to regulate electrical activity in the heart, making them useful for treating certain types of cardiac arrhythmias (irregular heart rhythms).

There are several different types of potassium channel blockers, including:

1. Class III antiarrhythmic drugs: These medications, such as amiodarone and sotalol, are used to treat and prevent serious ventricular arrhythmias (irregular heart rhythms that originate in the lower chambers of the heart).
2. Calcium channel blockers: While not strictly potassium channel blockers, some calcium channel blockers also have effects on potassium channels. These medications, such as diltiazem and verapamil, are used to treat hypertension (high blood pressure), angina (chest pain), and certain types of arrhythmias.
3. Non-selective potassium channel blockers: These medications, such as 4-aminopyridine and tetraethylammonium, have a broader effect on potassium channels and are used primarily in research settings to study the electrical properties of cells.

It's important to note that potassium channel blockers can have serious side effects, particularly when used in high doses or in combination with other medications that affect heart rhythms. They should only be prescribed by a healthcare provider who is familiar with their use and potential risks.

DNA Mutational Analysis is a laboratory test used to identify genetic variations or changes (mutations) in the DNA sequence of a gene. This type of analysis can be used to diagnose genetic disorders, predict the risk of developing certain diseases, determine the most effective treatment for cancer, or assess the likelihood of passing on an inherited condition to offspring.

The test involves extracting DNA from a patient's sample (such as blood, saliva, or tissue), amplifying specific regions of interest using polymerase chain reaction (PCR), and then sequencing those regions to determine the precise order of nucleotide bases in the DNA molecule. The resulting sequence is then compared to reference sequences to identify any variations or mutations that may be present.

DNA Mutational Analysis can detect a wide range of genetic changes, including single-nucleotide polymorphisms (SNPs), insertions, deletions, duplications, and rearrangements. The test is often used in conjunction with other diagnostic tests and clinical evaluations to provide a comprehensive assessment of a patient's genetic profile.

It is important to note that not all mutations are pathogenic or associated with disease, and the interpretation of DNA Mutational Analysis results requires careful consideration of the patient's medical history, family history, and other relevant factors.

Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is characterized by intellectual and developmental disabilities, distinctive facial features, and sometimes physical growth delays and health problems. The condition affects approximately one in every 700 babies born in the United States.

Individuals with Down syndrome have varying degrees of cognitive impairment, ranging from mild to moderate or severe. They may also have delayed development, including late walking and talking, and may require additional support and education services throughout their lives.

People with Down syndrome are at increased risk for certain health conditions, such as congenital heart defects, respiratory infections, hearing loss, vision problems, gastrointestinal issues, and thyroid disorders. However, many individuals with Down syndrome live healthy and fulfilling lives with appropriate medical care and support.

The condition is named after John Langdon Down, an English physician who first described the syndrome in 1866.

Sodium channel blockers are a class of medications that work by blocking sodium channels in the heart, which prevents the rapid influx of sodium ions into the cells during depolarization. This action slows down the rate of impulse generation and propagation in the heart, which in turn decreases the heart rate and prolongs the refractory period.

Sodium channel blockers are primarily used to treat cardiac arrhythmias, including atrial fibrillation, atrial flutter, and ventricular tachycardia. They may also be used to treat certain types of neuropathic pain. Examples of sodium channel blockers include Class I antiarrhythmics such as flecainide, propafenone, lidocaine, and mexiletine.

It's important to note that sodium channel blockers can have potential side effects, including proarrhythmia (i.e., the development of new arrhythmias or worsening of existing ones), negative inotropy (decreased contractility of the heart muscle), and cardiac conduction abnormalities. Therefore, these medications should be used with caution and under the close supervision of a healthcare provider.

Metabolic syndrome, also known as Syndrome X, is a cluster of conditions that increase the risk of heart disease, stroke, and diabetes. It is not a single disease but a group of risk factors that often co-occur. According to the American Heart Association and the National Heart, Lung, and Blood Institute, a person has metabolic syndrome if they have any three of the following five conditions:

1. Abdominal obesity (waist circumference of 40 inches or more in men, and 35 inches or more in women)
2. Triglyceride level of 150 milligrams per deciliter of blood (mg/dL) or greater
3. HDL cholesterol level of less than 40 mg/dL in men or less than 50 mg/dL in women
4. Systolic blood pressure of 130 millimeters of mercury (mmHg) or greater, or diastolic blood pressure of 85 mmHg or greater
5. Fasting glucose level of 100 mg/dL or greater

Metabolic syndrome is thought to be caused by a combination of genetic and lifestyle factors, such as physical inactivity and a diet high in refined carbohydrates and unhealthy fats. Treatment typically involves making lifestyle changes, such as eating a healthy diet, getting regular exercise, and losing weight if necessary. In some cases, medication may also be needed to manage individual components of the syndrome, such as high blood pressure or high cholesterol.

Bepridil is a calcium channel blocker medication that is used to treat angina (chest pain) and certain types of irregular heart rhythms. It works by relaxing the blood vessels and increasing the supply of oxygen and blood to the heart.

Here is the medical definition of Bepridil:

Bepridil is a non-dihydropyridine calcium channel blocker that selectively inhibits the L-type calcium channels in cardiac and smooth muscle cells, resulting in vasodilation, negative inotropic and chronotropic effects on the heart. It is used in the management of chronic stable angina pectoris and certain types of arrhythmias. The most common side effects include dizziness, headache, nausea, and constipation. Bepridil has a negative inotropic effect and should be used with caution in patients with heart failure or reduced left ventricular function. It is also metabolized by the cytochrome P450 system and can interact with other medications that are metabolized by this pathway.

Sudden death is a term used to describe a situation where a person dies abruptly and unexpectedly, often within minutes to hours of the onset of symptoms. It is typically caused by cardiac or respiratory arrest, which can be brought on by various medical conditions such as heart disease, stroke, severe infections, drug overdose, or trauma. In some cases, the exact cause of sudden death may remain unknown even after a thorough post-mortem examination.

It is important to note that sudden death should not be confused with "sudden cardiac death," which specifically refers to deaths caused by the abrupt loss of heart function (cardiac arrest). Sudden cardiac death is often related to underlying heart conditions such as coronary artery disease, cardiomyopathy, or electrical abnormalities in the heart.

HEK293 cells, also known as human embryonic kidney 293 cells, are a line of cells used in scientific research. They were originally derived from human embryonic kidney cells and have been adapted to grow in a lab setting. HEK293 cells are widely used in molecular biology and biochemistry because they can be easily transfected (a process by which DNA is introduced into cells) and highly express foreign genes. As a result, they are often used to produce proteins for structural and functional studies. It's important to note that while HEK293 cells are derived from human tissue, they have been grown in the lab for many generations and do not retain the characteristics of the original embryonic kidney cells.

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

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

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

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

Delayed rectifier potassium channels are a type of ion channel found in the membrane of excitable cells, such as nerve and muscle cells. They are called "delayed rectifiers" because they activate and allow the flow of potassium ions (K+) out of the cell after a short delay following an action potential, or electrical signal.

These channels play a crucial role in regulating the duration and frequency of action potentials, helping to restore the resting membrane potential of the cell after it has fired. By allowing K+ to flow out of the cell, delayed rectifier potassium channels help to repolarize the membrane and bring it back to its resting state.

There are several different types of delayed rectifier potassium channels, which are classified based on their biophysical and pharmacological properties. These channels are important targets for drugs used to treat a variety of conditions, including cardiac arrhythmias, epilepsy, and psychiatric disorders.

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

A heterozygote is an individual who has inherited two different alleles (versions) of a particular gene, one from each parent. This means that the individual's genotype for that gene contains both a dominant and a recessive allele. The dominant allele will be expressed phenotypically (outwardly visible), while the recessive allele may or may not have any effect on the individual's observable traits, depending on the specific gene and its function. Heterozygotes are often represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.

Genetic predisposition to disease refers to an increased susceptibility or vulnerability to develop a particular illness or condition due to inheriting specific genetic variations or mutations from one's parents. These genetic factors can make it more likely for an individual to develop a certain disease, but it does not guarantee that the person will definitely get the disease. Environmental factors, lifestyle choices, and interactions between genes also play crucial roles in determining if a genetically predisposed person will actually develop the disease. It is essential to understand that having a genetic predisposition only implies a higher risk, not an inevitable outcome.

Nicorandil is a medication that belongs to a class of drugs known as potassium channel activators. It works by relaxing and widening blood vessels, which improves blood flow and reduces the workload on the heart. Nicorandil is primarily used to treat chronic stable angina, a type of chest pain caused by reduced blood flow to the heart muscle.

The medical definition of Nicorandil can be described as:

A synthetic derivative of nicotinamide with vasodilatory properties, acting as an opener of ATP-sensitive potassium channels in vascular smooth muscle and cardiomyocytes. It is used in the management of chronic stable angina, providing both antianginal and antiischemic effects through a dual mechanism that includes coronary and peripheral vasodilation. By reducing afterload and preload, Nicorandil decreases myocardial oxygen demand while increasing supply, leading to improved exercise tolerance and reduced frequency of anginal episodes.

Methoxamine is a synthetic, selective α1-adrenergic receptor agonist used in scientific research and for therapeutic purposes. It has the ability to stimulate the α1 adrenergic receptors, leading to vasoconstriction (constriction of blood vessels), increased blood pressure, and reduced blood flow to the skin and extremities.

In a medical context, methoxamine is primarily used as an experimental drug or in research settings due to its specific pharmacological properties. It may be employed to investigate the role of α1-adrenergic receptors in various physiological processes or to temporarily counteract the hypotensive (low blood pressure) effects of certain medications, such as vasodilators or anesthetics.

It is important to note that methoxamine is not commonly used in routine clinical practice due to its strong vasoconstrictive properties and potential adverse effects on organ function if misused or improperly dosed.

Sotalol is a non-selective beta blocker and class III antiarrhythmic drug. It works by blocking the action of certain natural substances in your body, such as adrenaline, on the heart. This helps to decrease the heart's workload, slow the heart rate, and regulate certain types of irregular heartbeats (such as atrial fibrillation).

Sotalol is used to treat various types of irregular heartbeats (atrial fibrillation/flutter, ventricular tachycardia) and may also be used to help maintain a normal heart rhythm after a heart attack. It is important to note that Sotalol should only be prescribed by a healthcare professional who has experience in treating heart rhythm disorders.

This medical definition is based on the information provided by the National Library of Medicine (NLM).

Human chromosome pair 7 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and together they contain the genetic material that is inherited from both parents. They are identical in size, shape, and banding pattern and are therefore referred to as homologous chromosomes.

Chromosome 7 is one of the autosomal chromosomes, meaning it is not a sex chromosome (X or Y). It is composed of double-stranded DNA that contains approximately 159 million base pairs and around 1,200 genes. Chromosome 7 contains several important genes associated with human health and disease, including those involved in the development of certain types of cancer, such as colon cancer and lung cancer, as well as genetic disorders such as Williams-Beuren syndrome and Charcot-Marie-Tooth disease.

Abnormalities in chromosome 7 have been linked to various genetic conditions, including deletions, duplications, translocations, and other structural changes. These abnormalities can lead to developmental delays, intellectual disabilities, physical abnormalities, and increased risk of certain types of cancer.

Human chromosome pair 11 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and together they contain the genetic material that is inherited from both parents. They are located on the eleventh position in the standard karyotype, which is a visual representation of the 23 pairs of human chromosomes.

Chromosome 11 is one of the largest human chromosomes and contains an estimated 135 million base pairs. It contains approximately 1,400 genes that provide instructions for making proteins, as well as many non-coding RNA molecules that play a role in regulating gene expression.

Chromosome 11 is known to contain several important genes and genetic regions associated with various human diseases and conditions. For example, it contains the Wilms' tumor 1 (WT1) gene, which is associated with kidney cancer in children, and the neurofibromatosis type 1 (NF1) gene, which is associated with a genetic disorder that causes benign tumors to grow on nerves throughout the body. Additionally, chromosome 11 contains the region where the ABO blood group genes are located, which determine a person's blood type.

It's worth noting that human chromosomes come in pairs because they contain two copies of each gene, one inherited from the mother and one from the father. This redundancy allows for genetic diversity and provides a backup copy of essential genes, ensuring their proper function and maintaining the stability of the genome.

Cnidarian venoms are toxic substances produced by members of the phylum Cnidaria, which includes jellyfish, sea anemones, corals, and hydroids. These venoms are primarily contained in specialized cells called cnidocytes or nematocysts, which are found in the tentacles of these animals. When a cnidarian comes into contact with prey or a potential threat, the cnidocytes discharge, injecting the venom into the target through a hollow tubule.

Cnidarian venoms are complex mixtures of bioactive molecules, including proteins, peptides, and small organic compounds. The composition of these venoms can vary significantly between different cnidarian species, as well as between different life stages or sexes of the same species. Some cnidarian venoms primarily serve a defensive function, causing pain or other unpleasant symptoms in potential predators, while others have a more offensive role, helping to immobilize prey before consumption.

The effects of cnidarian venoms on humans can range from mild irritation and stinging sensations to severe pain, swelling, and allergic reactions. In some cases, cnidarian envenomations can lead to more serious complications, such as respiratory distress, cardiac arrhythmias, or even death, particularly in individuals with underlying health conditions or allergies to the venom.

Research on cnidarian venoms has led to important insights into the biochemistry and molecular mechanisms of pain, inflammation, and neurotoxicity, as well as the development of new therapeutic strategies for treating various medical conditions. Additionally, understanding the structure and function of cnidarian venom components has inspired the design of novel bioactive molecules with potential applications in drug discovery, pest control, and other areas of biotechnology.

"Family Health" is not a term that has a single, widely accepted medical definition. However, in the context of healthcare and public health, "family health" often refers to the physical, mental, and social well-being of all members of a family unit. It includes the assessment, promotion, and prevention of health conditions that affect individual family members as well as the family as a whole.

Family health may also encompass interventions and programs that aim to strengthen family relationships, communication, and functioning, as these factors can have a significant impact on overall health outcomes. Additionally, family health may involve addressing social determinants of health, such as poverty, housing, and access to healthcare, which can affect the health of families and communities.

Overall, family health is a holistic approach to healthcare that recognizes the importance of considering the needs and experiences of all family members in promoting and maintaining good health.

Propranolol is a medication that belongs to a class of drugs called beta blockers. Medically, it is defined as a non-selective beta blocker, which means it blocks the effects of both epinephrine (adrenaline) and norepinephrine (noradrenaline) on the heart and other organs. These effects include reducing heart rate, contractility, and conduction velocity, leading to decreased oxygen demand by the myocardium. Propranolol is used in the management of various conditions such as hypertension, angina pectoris, arrhythmias, essential tremor, anxiety disorders, and infants with congenital heart defects. It may also be used to prevent migraines and reduce the risk of future heart attacks. As with any medication, it should be taken under the supervision of a healthcare provider due to potential side effects and contraindications.

Single-Stranded Conformational Polymorphism (SSCP) is not a medical condition but rather a laboratory technique used in molecular biology and genetics. It refers to the phenomenon where a single-stranded DNA or RNA molecule can adopt different conformations or shapes based on its nucleotide sequence, even if the difference in the sequence is as small as a single base pair change. This property is used in SSCP analysis to detect mutations or variations in DNA or RNA sequences.

In SSCP analysis, the denatured single-stranded DNA or RNA sample is subjected to electrophoresis on a non-denaturing polyacrylamide gel. The different conformations of the single-stranded molecules migrate at different rates in the gel, creating multiple bands that can be visualized by staining or other detection methods. The presence of additional bands or shifts in band patterns can indicate the presence of a sequence variant or mutation.

SSCP analysis is often used as a screening tool for genetic diseases, cancer, and infectious diseases to identify genetic variations associated with these conditions. However, it has largely been replaced by more sensitive and accurate methods such as next-generation sequencing.

Ventricular Fibrillation (VF) is a type of cardiac arrhythmia, which is an abnormal heart rhythm. In VF, the ventricles, which are the lower chambers of the heart, beat in a rapid and unorganized manner. This results in the heart being unable to pump blood effectively to the rest of the body, leading to immediate circulatory collapse and cardiac arrest if not treated promptly. It is often caused by underlying heart conditions such as coronary artery disease, structural heart problems, or electrolyte imbalances. VF is a medical emergency that requires immediate defibrillation to restore a normal heart rhythm.

Trans-activators are proteins that increase the transcriptional activity of a gene or a set of genes. They do this by binding to specific DNA sequences and interacting with the transcription machinery, thereby enhancing the recruitment and assembly of the complexes needed for transcription. In some cases, trans-activators can also modulate the chromatin structure to make the template more accessible to the transcription machinery.

In the context of HIV (Human Immunodeficiency Virus) infection, the term "trans-activator" is often used specifically to refer to the Tat protein. The Tat protein is a viral regulatory protein that plays a critical role in the replication of HIV by activating the transcription of the viral genome. It does this by binding to a specific RNA structure called the Trans-Activation Response Element (TAR) located at the 5' end of all nascent HIV transcripts, and recruiting cellular cofactors that enhance the processivity and efficiency of RNA polymerase II, leading to increased viral gene expression.

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

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

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

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

Sudden Infant Death Syndrome (SIDS) is defined by the American Academy of Pediatrics as "the sudden unexpected death of an infant

Muscle proteins are a type of protein that are found in muscle tissue and are responsible for providing structure, strength, and functionality to muscles. The two major types of muscle proteins are:

1. Contractile proteins: These include actin and myosin, which are responsible for the contraction and relaxation of muscles. They work together to cause muscle movement by sliding along each other and shortening the muscle fibers.
2. Structural proteins: These include titin, nebulin, and desmin, which provide structural support and stability to muscle fibers. Titin is the largest protein in the human body and acts as a molecular spring that helps maintain the integrity of the sarcomere (the basic unit of muscle contraction). Nebulin helps regulate the length of the sarcomere, while desmin forms a network of filaments that connects adjacent muscle fibers together.

Overall, muscle proteins play a critical role in maintaining muscle health and function, and their dysregulation can lead to various muscle-related disorders such as muscular dystrophy, myopathies, and sarcopenia.

Medical Definition:

"Risk factors" are any attribute, characteristic or exposure of an individual that increases the likelihood of developing a disease or injury. They can be divided into modifiable and non-modifiable risk factors. Modifiable risk factors are those that can be changed through lifestyle choices or medical treatment, while non-modifiable risk factors are inherent traits such as age, gender, or genetic predisposition. Examples of modifiable risk factors include smoking, alcohol consumption, physical inactivity, and unhealthy diet, while non-modifiable risk factors include age, sex, and family history. It is important to note that having a risk factor does not guarantee that a person will develop the disease, but rather indicates an increased susceptibility.

Risk assessment in the medical context refers to the process of identifying, evaluating, and prioritizing risks to patients, healthcare workers, or the community related to healthcare delivery. It involves determining the likelihood and potential impact of adverse events or hazards, such as infectious diseases, medication errors, or medical devices failures, and implementing measures to mitigate or manage those risks. The goal of risk assessment is to promote safe and high-quality care by identifying areas for improvement and taking action to minimize harm.

In medical terms, toes are the digits located at the end of the foot. Humans typically have five toes on each foot, consisting of the big toe (hallux), second toe, third toe, fourth toe, and little toe (fifth toe). The bones of the toes are called phalanges, with the exception of the big toe, which has a different bone structure and is composed of a proximal phalanx, distal phalanx, and sometimes a sesamoid bone.

Toes play an essential role in maintaining balance and assisting in locomotion by helping to push off the ground during walking or running. They also contribute to the overall stability and posture of the body. Various medical conditions can affect toes, such as ingrown toenails, bunions, hammertoes, and neuromas, which may require specific treatments or interventions to alleviate pain, restore function, or improve appearance.

"Xenopus" is not a medical term, but it is a genus of highly invasive aquatic frogs native to sub-Saharan Africa. They are often used in scientific research, particularly in developmental biology and genetics. The most commonly studied species is Xenopus laevis, also known as the African clawed frog.

In a medical context, Xenopus might be mentioned when discussing their use in research or as a model organism to study various biological processes or diseases.

I'm sorry for any confusion, but "Utah" is not a medical term or concept. It is a geographical location, being the 45th state admitted to the United States of America. If you have any questions related to medical topics, I would be happy to try and help answer those for you!

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

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

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

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

Protein transport, in the context of cellular biology, refers to the process by which proteins are actively moved from one location to another within or between cells. This is a crucial mechanism for maintaining proper cell function and regulation.

Intracellular protein transport involves the movement of proteins within a single cell. Proteins can be transported across membranes (such as the nuclear envelope, endoplasmic reticulum, Golgi apparatus, or plasma membrane) via specialized transport systems like vesicles and transport channels.

Intercellular protein transport refers to the movement of proteins from one cell to another, often facilitated by exocytosis (release of proteins in vesicles) and endocytosis (uptake of extracellular substances via membrane-bound vesicles). This is essential for communication between cells, immune response, and other physiological processes.

It's important to note that any disruption in protein transport can lead to various diseases, including neurological disorders, cancer, and metabolic conditions.

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

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

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

A newborn infant is a baby who is within the first 28 days of life. This period is also referred to as the neonatal period. Newborns require specialized care and attention due to their immature bodily systems and increased vulnerability to various health issues. They are closely monitored for signs of well-being, growth, and development during this critical time.

The Founder Effect is a concept in population genetics that refers to the loss of genetic variation that occurs when a new colony is established by a small number of individuals from a larger population. This decrease in genetic diversity can lead to an increase in homozygosity, which can in turn result in a higher frequency of certain genetic disorders or traits within the founding population and its descendants. The Founder Effect is named after the "founding" members of the new colony who carry and pass on their particular set of genes to the next generations. It is one of the mechanisms that can lead to the formation of distinct populations or even new species over time.

Piperidines are not a medical term per se, but they are a class of organic compounds that have important applications in the pharmaceutical industry. Medically relevant piperidines include various drugs such as some antihistamines, antidepressants, and muscle relaxants.

A piperidine is a heterocyclic amine with a six-membered ring containing five carbon atoms and one nitrogen atom. The structure can be described as a cyclic secondary amine. Piperidines are found in some natural alkaloids, such as those derived from the pepper plant (Piper nigrum), which gives piperidines their name.

In a medical context, it is more common to encounter specific drugs that belong to the class of piperidines rather than the term itself.

Epinephrine, also known as adrenaline, is a hormone and a neurotransmitter that is produced in the body. It is released by the adrenal glands in response to stress or excitement, and it prepares the body for the "fight or flight" response. Epinephrine works by binding to specific receptors in the body, which causes a variety of physiological effects, including increased heart rate and blood pressure, improved muscle strength and alertness, and narrowing of the blood vessels in the skin and intestines. It is also used as a medication to treat various medical conditions, such as anaphylaxis (a severe allergic reaction), cardiac arrest, and low blood pressure.

Nephrotic syndrome is a group of symptoms that indicate kidney damage, specifically damage to the glomeruli—the tiny blood vessel clusters in the kidneys that filter waste and excess fluids from the blood. The main features of nephrotic syndrome are:

1. Proteinuria (excess protein in urine): Large amounts of a protein called albumin leak into the urine due to damaged glomeruli, which can't properly filter proteins. This leads to low levels of albumin in the blood, causing fluid buildup and swelling.
2. Hypoalbuminemia (low blood albumin levels): As albumin leaks into the urine, the concentration of albumin in the blood decreases, leading to hypoalbuminemia. This can cause edema (swelling), particularly in the legs, ankles, and feet.
3. Edema (fluid retention and swelling): With low levels of albumin in the blood, fluids move into the surrounding tissues, causing swelling or puffiness. The swelling is most noticeable around the eyes, face, hands, feet, and abdomen.
4. Hyperlipidemia (high lipid/cholesterol levels): The kidneys play a role in regulating lipid metabolism. Damage to the glomeruli can lead to increased lipid production and high cholesterol levels in the blood.

Nephrotic syndrome can result from various underlying kidney diseases, such as minimal change disease, membranous nephropathy, or focal segmental glomerulosclerosis. Treatment depends on the underlying cause and may include medications to control inflammation, manage high blood pressure, and reduce proteinuria. In some cases, dietary modifications and lifestyle changes are also recommended.

Membrane potential is the electrical potential difference across a cell membrane, typically for excitable cells such as nerve and muscle cells. It is the difference in electric charge between the inside and outside of a cell, created by the selective permeability of the cell membrane to different ions. The resting membrane potential of a typical animal cell is around -70 mV, with the interior being negative relative to the exterior. This potential is generated and maintained by the active transport of ions across the membrane, primarily through the action of the sodium-potassium pump. Membrane potentials play a crucial role in many physiological processes, including the transmission of nerve impulses and the contraction of muscle cells.

Hypokalemia is a medical condition characterized by abnormally low potassium levels in the blood, specifically when the concentration falls below 3.5 milliequivalents per liter (mEq/L). Potassium is an essential electrolyte that helps regulate heart function, nerve signals, and muscle contractions.

Hypokalemia can result from various factors, including inadequate potassium intake, increased potassium loss through the urine or gastrointestinal tract, or shifts of potassium between body compartments. Common causes include diuretic use, vomiting, diarrhea, certain medications, kidney diseases, and hormonal imbalances.

Mild hypokalemia may not cause noticeable symptoms but can still affect the proper functioning of muscles and nerves. More severe cases can lead to muscle weakness, fatigue, cramps, paralysis, heart rhythm abnormalities, and in rare instances, respiratory failure or cardiac arrest. Treatment typically involves addressing the underlying cause and replenishing potassium levels through oral or intravenous (IV) supplementation, depending on the severity of the condition.

Potassium is a essential mineral and an important electrolyte that is widely distributed in the human body. The majority of potassium in the body (approximately 98%) is found within cells, with the remaining 2% present in blood serum and other bodily fluids. Potassium plays a crucial role in various physiological processes, including:

1. Regulation of fluid balance and maintenance of normal blood pressure through its effects on vascular tone and sodium excretion.
2. Facilitation of nerve impulse transmission and muscle contraction by participating in the generation and propagation of action potentials.
3. Protein synthesis, enzyme activation, and glycogen metabolism.
4. Regulation of acid-base balance through its role in buffering systems.

The normal serum potassium concentration ranges from 3.5 to 5.0 mEq/L (milliequivalents per liter) or mmol/L (millimoles per liter). Potassium levels outside this range can have significant clinical consequences, with both hypokalemia (low potassium levels) and hyperkalemia (high potassium levels) potentially leading to serious complications such as cardiac arrhythmias, muscle weakness, and respiratory failure.

Potassium is primarily obtained through the diet, with rich sources including fruits (e.g., bananas, oranges, and apricots), vegetables (e.g., leafy greens, potatoes, and tomatoes), legumes, nuts, dairy products, and meat. In cases of deficiency or increased needs, potassium supplements may be recommended under the guidance of a healthcare professional.

The following is a list of genes associated with Long QT syndrome: Although long QT syndrome is often a genetic condition, a ... acquired long QT syndrome).[citation needed] Inherited, or congenital long QT syndrome, is caused by genetic abnormalities. ... "25th anniversary of the International Long-QT Syndrome Registry: an ongoing quest to uncover the secrets of long-QT syndrome". ... In long QT syndrome it takes longer for this repolarisation to occur, shown in individual cells as a longer action potential ...
... of patients who experienced sudden cardiac death were also using a QT-prolonging drug. Long QT syndrome Torsades de pointes ... Khan IA (2002). "Long QT syndrome: diagnosis and management". American Heart Journal. 143 (1): 7-14. doi:10.1067/mhj. ... TdP can be acquired by inheritance of a congenital long QT syndrome, or more commonly from the ingestion of a pharmacologic ... El-Sherif N, Turitto G, Boutjdir M (2018). "Acquired long QT syndrome and torsade de pointes". Pacing and Clinical ...
... cardiac arrhythmia syndrome known as long QT syndrome, type 4, also known as ankyrin-B syndrome which can be described as an ... cardiac arrhythmia syndrome known as long QT syndrome 4 as well as sick sinus syndrome; mutations have also been associated to ... November 1995). "Mapping of a gene for long QT syndrome to chromosome 4q25-27". Am. J. Hum. Genet. 57 (5): 1114-22. PMC 1801360 ... Initially, a Glu1425Gly mutation in ANK2 was found to cause dominantly-inherited long QT syndrome type 4, cardiac arrhythmia. ...
Long QT syndrome is a familial condition that is uncommon but is a known source of sudden death in young people. It can cause ... "Long QT syndrome". Genetic and Rare Diseases Information Center (GARD) - an NCATS Program. 2017. Retrieved 2 July 2021. ... Wolff-Parkinson-White syndrome (WPW) syndrome is a known cause of arrhythmia in young people. It causes supraventricular ... Brugada syndrome is a familial condition that is also very uncommon, and also a known source of sudden death in young people. ...
Long QT syndrome is the most common form of cardiac channelopathy. Long QT Syndrome (LQTS) - Mostly hereditary. On EKG can be ... "Long QT Syndrome". NORD (National Organization for Rare Disorders). Retrieved 19 November 2022. "Catecholaminergic polymorphic ... Short QT syndrome. Catecholaminergic polymorphic ventricular tachycardia (CPVT). Progressive cardiac conduction defect (PCCD). ... Cardiac ion channelopathies may explain some of the cases of sudden death syndrome and sudden arrhythmic death syndrome. ...
JLNS, like other forms of long QT syndrome, causes the cardiac muscle to take longer than usual to recharge between beats. It ... The risk of arrhythmias is higher for those with Jervell and Lange-Nielsen syndrome than other forms of long QT syndrome. ... Jervell and Lange-Nielsen syndrome (JLNS) is a rare type of long QT syndrome associated with severe, bilateral sensorineural ... Mutations in the same genes can produce milder Romano-Ward forms of long QT syndrome if only a single copy of the genetic ...
Rossi M, Giorgi G (July 2010). "Domperidone and long QT syndrome". Current Drug Safety. 5 (3): 257-262. doi:10.2174/ ... It should no longer be used for the treatment of bloating and heartburn. Domperidone is now contraindicated in those with ... An advocate for the mother suggested the child may have had neuroleptic malignant syndrome as a side effect of domperidone due ... Djeddi D, Kongolo G, Lefaix C, Mounard J, Léké A (November 2008). "Effect of domperidone on QT interval in neonates". The ...
Fazio G, Vernuccio F, Grutta G, Re GL (26 April 2013). "Drugs to be avoided in patients with long QT syndrome: Focus on the ... Lee KW, Kayser SR, Hongo RH, Tseng ZH, Scheinman MM (May 2004). "Famotidine and long QT syndrome". The American Journal of ... Famotidine may contribute to QT prolongation, particularly when used with other QT-elongating drugs, or in people with poor ... Long B, Chavez S, Carius BM, Brady WJ, Liang SY, Koyfman A, Gottlieb M (June 2022). "Clinical update on COVID-19 for the ...
Chiang, CE (2004). "Congenital and acquired long QT syndrome. Current concepts and management". Cardiology in Review. 12 (4): ...
Khan, Ijaz A. (2002). "Long QT syndrome: Diagnosis and management". American Heart Journal. 143 (1): 7-14. doi:10.1067/mhj. ... long QT syndrome, social phobia, anxiety, and other conditions. ETS involves dissection of the main sympathetic trunk in the ... also known as Frey's syndrome). Other long-term adverse effects include: Ultrastructural changes in the cerebral artery wall ... Harlequin syndrome Cerfolio, Robert J.; De Campos, Jose Ribas Milanez; Bryant, Ayesha S.; Connery, Cliff P.; Miller, Daniel L ...
... directions and long QT syndrome which is associated with the QT interval in the electrocardiogram that is significantly longer ... As the process of whole exome sequencing was used for patients with long QT syndrome, there was a certain criteria that had to ... However, there have been few mutations that were detected in the genes of the calmodulin protein such as in long QT syndrome. ... Reed GJ, Boczek NJ, Etheridge SP, Ackerman MJ (February 2015). "CALM3 mutation associated with long QT syndrome". Heart Rhythm ...
... and Jervell Lange-Nielsens syndrome (homozygotes). Both these syndromes are characterized by Long QT syndrome, a delay in ... Mutation D76N in the KCNE1 protein can lead to long QT syndrome due to structural changes in the KvLQT1/KCNE1 complex, and ... While loss-of-function mutations in KCNE1 cause Long QT syndrome, gain-of-function KCNE1 mutations are associated with early- ... "Long QT syndrome-associated mutations in KCNQ1 and KCNE1 subunits disrupt normal endosomal recycling of IKs channels". ...
QT interval Long QT syndrome Schlesser JL (1991). Drugs Available Abroad, 1st Edition. Derwent Publications Ltd. p. 29. ISBN 0- ... November 2004). "A common antitussive drug, clobutinol, precipitates the long QT syndrome 2". Molecular Pharmacology. 66 (5): ... Studies in 2004 had indicated that clobutinol has the potential to prolong the QT interval. Clobutinol was in 2007 determined ...
Van Niekerk, Chantal; Van Deventer, Barbara Ströh; du Toit-Prinsloo, Lorraine (September 2017). "Long QT syndrome and sudden ... such as long QT syndrome 1 (LQT1), and epilepsy. Mutations in potassium channel gene KCNH2 have been identified with LQT2. ... Many of the genes are involved in long QT syndrome. Mutations in the KCNQ1 gene that codes for the voltage-gated potassium ... It is unclear if this is because of the potential cardio-respiratory adverse effects such as lengthening of the QT interval and ...
This leads to long QT syndrome and resultant arrhythmia. Because exon 8 has greater expression in the heart versus exon 8a, ... Long QT syndrome sometimes presents itself as a complication due to surgery to correct syndactyly. Other times, children ... The most striking sign of Timothy syndrome type 1 is the co-occurrence of both syndactyly (about 0.03% of births) and long QT ... Marks ML, Trippel DL, Keating MT (October 1995). "Long QT syndrome associated with syndactyly identified in females". The ...
Mitcheson JS, Chen J, Lin M, Culberson C, Sanguinetti MC (October 2000). "A structural basis for drug-induced long QT syndrome ... So far, one clinical trial has been conducted to test the effect of E-4031 on prolongation of the QT-interval. Kim I, Boyle KM ... As E-4031 can prolong the QT-interval, it can cause lethal arrhythmias. E-4031 is solely used for research purposes. ... Reducing IKr in myocardial cells prolongs the cardiac action potential and thus prolongs the QT-interval. In non-cardiac cells ...
"Does KCNE5 play a role in long QT syndrome?". Clinica Chimica Acta; International Journal of Clinical Chemistry. 345 (1-2): 49- ... "KCNE5 polymorphism rs697829 is associated with QT interval and survival in acute coronary syndromes patients". Journal of ... Brugada syndrome is a relatively rare but lethal ventricular arrhythmia most commonly linked to voltage-gated sodium channel ... This intronless gene is deleted in AMME contiguous gene syndrome and is potentially involved in the cardiac and neurologic ...
Ayad RF, Assar MD, Simpson L, Garner JB, Schussler JM (July 2010). "Causes and management of drug-induced long QT syndrome". ... Antidepressant discontinuation syndrome, also called antidepressant withdrawal syndrome, is a condition that can occur ... They have a long history of use as medications prescribed for the treatment of depression. They are particularly effective in ... Long-term efficacy remains poorly characterized. Bupropion is not recommended for the treatment of eating disorders, due to an ...
Mutations in the SCN4B are associated with long QT syndrome. SCN4B might additionally function as a cell adhesion molecule. ... "SCN4B-encoded sodium channel beta4 subunit in congenital long-QT syndrome". Circulation. 116 (2): 134-42. doi:10.1161/ ...
Short QT syndrome, and Familial Atrial Fibrillation. KvLQT1 are also expressed in the pancreas, and KvLQT1 Long QT syndrome ... "The genetic basis of long QT and short QT syndromes: a mutation update". Human Mutation. 30 (11): 1486-1511. doi:10.1002/humu. ... Mutations in the gene can lead to a defective protein and several forms of inherited arrhythmias as Long QT syndrome which is a ... Mutations in either the alpha subunit of this complex, KvLQT1 or the beta subunit, KCNE1, can lead to Long QT Syndrome or other ...
Sinus tachycardia Long QT syndrome Hafeez Y, Grossman SA (2020). "Sinus Bradycardia". StatPearls. Treasure Island (FL): ... such as sick sinus syndrome), Roemheld syndrome, sleep apnea Physiological causes: Increased vagal tone, increased intracranial ... helping them to conserve oxygen during long dives. Sinus bradycardia is a common condition found in both healthy individuals ... carotid sinus syndrome, eating disorders (such as anorexia nervosa), rhodotoxin poisoning, hypothermia, hypothyroidism, ...
She was diagnosed with long QT syndrome, and the doctors caring for her believe it is likely that Mitchell suffered from the ... Singh, Anita (21 June 2012). "Man who died laughing at Goodies had Long QT syndrome". The Telegraph. Retrieved 2 April 2015. " ...
Singh, Anita (21 June 2012). "Man who died laughing at Goodies had Long QT syndrome". The Telegraph. Archived from the original ... Long Island, New York. ISSN 0278-5587. Archived from the original on 18 January 2016. "Sewage Claims Mayor". Lawrence Journal- ... "7-meter-long python swallows Indonesian woman". Associated Press. 16 June 2018 - via National Post. Johnson, Alex (11 May 2017 ... long volume value, CS1 Italian-language sources (it), Harv and Sfn no-target errors, Pages with missing ISBNs, CS1 German- ...
Singh, Anita (21 Jun 2012). "Man who died laughing at Goodies had Long QT syndrome". The Telegraph. Retrieved 2 April 2015. "10 ... Diagnosis of his granddaughter in 2012 of having the inheritable long QT syndrome (a heart rhythm abnormality) suggests that ...
Furthermore, caveolin-3 has been associated with long QT syndrome. Caveolin-3 has been implicated in the development of certain ... "Mutant caveolin-3 induces persistent late sodium current and is associated with long-QT syndrome". Circulation. 114 (20): 2104- ...
March 2011). "Modelling the long QT syndrome with induced pluripotent stem cells". Nature. 471 (7337): 225-9. Bibcode:2011Natur ... The process took longer and was not as efficient, but the resulting chimeras did not develop cancer. Inactivation or deletion ... March 2015). "Long-term safety issues of iPSC-based cell therapy in a spinal cord injury model: oncogenic transformation with ... For instance, iPS cell lines derived from patients affected by ectodermal dysplasia syndrome (EEC), in which the p63 gene is ...
"Contribution of long-QT syndrome genetic variants in sudden infant death syndrome". Pediatric Cardiology. 30 (4): 502-9. doi: ... "Prevalence of long-QT syndrome gene variants in sudden infant death syndrome". Circulation. 115 (3): 361-7. doi:10.1161/ ... Tester DJ, Cronk LB, Carr JL, Schulz V, Salisbury BA, Judson RS, Ackerman MJ (July 2006). "Allelic dropout in long QT syndrome ... Long QT syndrome predisposes to potentially lethal ventricular cardiac arrhythmias including torsades de pointe, which can ...
... is contraindicated in people with congenital long QT syndrome. Very common (present in greater than 10% of people) ... long QT syndrome, high blood pressure, stomach pain, diarrhea, nausea, vomiting, indigestion, sensitivity to sunlight, rash, ... Other drugs that prolong the QT interval can possibly add to this side effect of vandetanib. As the drug is partly metabolised ...
El-Sherif, N (August 2001). "Mechanism of ventricular arrhythmias in the long QT syndrome: on hermeneutics". Journal of ... Khan, IA (January 2002). "Clinical and therapeutic aspects of congenital and acquired long QT syndrome". The American Journal ... However, there is agreement that the greater loss of mass with long-duration flight is most likely due to atrophy. The QT ... Thus, changes in QT duration represent alterations in ventricular repolarization. The QT interval of the surface ECG is a ...
Such tests can screen for drug-hERG channel interactions that cause acquired long QT syndrome, are essential for determining ... Sanguinetti MC, Mitcheson JS (Mar 2005). "Predicting drug-hERG channel interactions that cause acquired long QT syndrome". ... which destabilize the conductive conformation and facilitate entry into a long-lived nonconducting state that resembles the C- ...
The following is a list of genes associated with Long QT syndrome: Although long QT syndrome is often a genetic condition, a ... acquired long QT syndrome).[citation needed] Inherited, or congenital long QT syndrome, is caused by genetic abnormalities. ... "25th anniversary of the International Long-QT Syndrome Registry: an ongoing quest to uncover the secrets of long-QT syndrome". ... In long QT syndrome it takes longer for this repolarisation to occur, shown in individual cells as a longer action potential ...
Long QT syndrome affects the hearts rhythm. If it is left untreated, the condition can be fatal. Learn more about the symptoms ... and strenuous exercise may trigger long QT syndrome symptoms.. How serious is long QT syndrome?. Long QT syndrome is a ... Long QT syndrome presents as an abnormally long QT interval on an EKG, which can increase a persons risk of abnormal heart ... What triggers long QT types?. Genetic modifications can lead to inherited forms of long QT syndrome. While acquired forms ...
... is a congenital disorder characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a propensity to ... encoded search term (Long QT Syndrome) and Long QT Syndrome What to Read Next on Medscape ... Marked prolongation of QT interval in a 15-year-old male adolescent with long QT syndrome (LQTS) (R-R = 1.00 s, QT interval = ... Marked prolongation of QT interval in a 15-year-old male adolescent with long QT syndrome (LQTS) (R-R = 1.00 s, QT interval = ...
Genevie was diagnosed with Long QT Syndrome in 1997 - but because genetic testing wasnt commercially available, she didnt ... Sometimes you cant tell that you have a sudden arrythmia death syndrome (SADS) condition until you undergo genetic testing. ...
Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking. Yuri A. Kuryshev, Eckhard Ficker, Lu Wang, Peter Hawryluk, ... Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking. Yuri A. Kuryshev, Eckhard Ficker, Lu Wang, Peter Hawryluk, ... Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking. Yuri A. Kuryshev, Eckhard Ficker, Lu Wang, Peter Hawryluk, ... Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking Message Subject (Your Name) has forwarded a page to you from ...
Congenital Long QT Syndrome (LQTS) is a genetic disease and associated with significant arrhythmias and sudden cardiac death. ... the dynamics of QT or to be able to diagnose the syn- ... Congenital Long QT Syndrome (LQTS) is a genetic disease and ... 2] Jensen, B.T. (2004) Beat-to-beat QT dynamics in healthy ... Keywords: Long QT Syndrome; Discrete Wavelet Transform; Support ... time in order to constitute QT time-series data. As a re- ... Diagnosis of long QT syndrome via support vector machines ...
25th anniversary of the International Long-QT Syndrome Registry: an ongoing quest to uncover the secrets of long-QT syndrome. ... High efficacy of betablockers in long-QT syndrome type 1: contribution of noncompliance and QT-prolonging drugs to the ... Differential Effects of Beta Blockers in Patients With Congenital Long QT Syndromes. Dec 06, 2012 , Thomas F. Deering, MD, FACC ... YOU ARE HERE: Home , Latest in Cardiology , Differential Effects of Beta Blockers in Patients With Congenital Long QT Syndromes ...
The spectrum of symptoms and QT intervals in carriers of the gene for the long-QT syndrome. N Engl J Med 1992; 327:846-52 ... Volatile Anesthetics and the Long QT Syndrome Stefan Rasche, M.D.; Stefan Rasche, M.D. ... With much interest we read the article by Susan J. Kies et al. regarding patients with congenital long QT syndrome (LQTS). We ... Roden DM, Lazzara R, Rosen M, Schwartz P, Towbin J, Vincent GM: Multiple mechanisms in the long-QT-syndrome: Current knowledge ...
Long QT Interval Syndromes - Etiology, pathophysiology, symptoms, signs, diagnosis & prognosis from the MSD Manuals - Medical ... a long QT interval have congenital long QT syndrome and because not all patients with a congenital long QT syndrome have a long ... Etiology of Long QT Interval Syndromes Long QT interval syndromes are classified based on the specific gene that has mutated. ... Pathophysiology of Long QT Interval Syndromes The congenital long QT interval syndromes result from genetic disorders of ...
Abnormal action potential (AP) properties, as occurs in long or short QT syndromes (LQTS and SQTS, respectively), can cause ... Optogenetic modulation of cardiac action potential properties may prevent arrhythmogenesis in short and long QT syndromes. ... Optogenetic modulation of cardiac action potential properties may prevent arrhythmogenesis in short and long QT syndromes. ...
You are here: Home / Exposures / Clancy, Rudy, 2001 / Cellular consequences of HERG mutations in the long QT syndrome: ... Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death (Wild Type Epicardial Cell) ... Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death, Colleen E. Clancy and ... Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death (Wild Type Midmyocardial ...
Lyells Syndrome and Stevens-Johnson Syndrome), epilepsy, thyroid diseases, diabetes, Long QT and Brugada Syndromes. The role ...
... is associated with a prolonged QT interval, which may be co... ... of acquired long QT syndrome from congenital long QT syndrome. ... Long-term treatment in acquired long QT syndrome usually is not required because the QT interval returns to normal once the ... Torsade occurring in the setting of acquired long QT syndrome is preceded by pauses in almost all cases. In congenital long QT ... Women have longer QT intervals, [16] as well as have more QT prolongation secondary to drug therapy. Congenital long QT ...
Congenital long QT syndrome. Due to the risk of long QT syndrome, doctors usually wont prescribe Ingrezza if you have long QT ... Long QT syndrome. In studies, Ingrezza caused long QT syndrome. This is when the heart takes longer than usual to relax and ... If they determine you have long QT syndrome, they may have you stop taking Ingrezza. ... Neuroleptic malignant syndrome (NMS). NMS is a possible side effect of Ingrezza. If you develop NMS during Ingrezza treatment, ...
Depending on the cause there are two main categories of QT syndrome i-e congenital long QT syndrome and acquired long QT ... Long QT Syndrome. This is an arrhythmical condition of the heart that is chcharacterized by fast and chaotic heart beats. This ... This condition is usually asymptomatic but some can have clue of long QT syndrome due to ... Usually in this syndrome heart rhythms take longer than normal to recharge between the rhythms. This delay in recharge leads to ...
Short QT syndrome, Long QT syndrome. AD. 346. 925. KCNJ2. Short QT syndrome, Andersen syndrome, Long QT syndrome, Atrial ... Long QT syndrome, Hyperaldosteronism, familial. AD. 7. 15. KCNQ1. Short QT syndrome, Long QT syndrome, Atrial fibrillation, ... of long QT syndrome patients. The prevalence of LQTS is estimated to be 1:3,000 and occurs in all ethnicities. Long QT syndrome ... Long QT syndrome, arrhythmogenic right ventricular cardiomyopathy (ARVC) and Short QT syndrome. The genes on the panel have ...
We present a case of long QT syndrome that remained undiagnosed in the epilepsy clinic for 15 years until a near-fatal ... KCNQ1 p.L353L affects splicing and modifies the phenotype in a founder population with long QT syndrome type 1. Jamie D ... We hope this near miss raises awareness of long QT syndrome as a potentially fatal, rare but treatable condition that ... Return to play? Athletes with congenital long QT syndrome. Jonathan N Johnson et al., British Journal of Sports Medicine, 2012 ...
Long QT Syndrome (LQTS). Long QT syndrome (LQTS) is a heart rhythm disorder that can potentially cause fast, out of control ...
Long QT syndrome (LQTS) is a disease that can cause a dangerous rapid heart rate and irregular rhythm involving the bottom ... Important clinical traits of the inherited long QT syndrome (LQTS). Symptoms of Long QT Syndrome. Many people with long QT ... Diagnosis of Long QT Syndrome. If you have symptoms or a family history that indicates long QT syndrome, you will have tests ... Overview of Long QT Syndrome. Long QT syndrome (LQTS) is a disease that can cause a dangerous rapid heart rate and irregular ...
... familial long QT syndrome). Indeed, sudden cardiac death in the pediatric population can be the first presentation of an ... Molecular basis of long QT syndrome. Six genetic loci for long QT syndrome have been identified. Sporadic cases occur as a ... Acquired long QT syndrome. The acquired causes of long QT syndrome include drugs, electrolyte imbalance, marked bradycardia, ... The establishment of a long QT syndrome registry and the discovery of genetic mutations that cause long QT syndrome have ...
This nursing assessment lays the foundation for individualized care planning and interventions for the patient with Long QT ... Nursing Assessment for Long QT Syndrome Nursing Diagnosis For Long Qt Syndrome Nursing Interventions For Long Qt Syndrome ... Nursing Assessment for Long QT Syndrome:. 1. Diagnosis Confirmation:. *Confirm the diagnosis of Long QT syndrome through review ... 9. Risk for Complications related to Family History of Long QT Syndrome:. *Patients with a family history of Long QT syndrome ...
Patients with long QT syndrome (LQTS) should avoid drugs that prolong the QT interval or reduce their serum potassium or ... What is QTc and Long QT syndrome (LQTS)?. Dr T. July 31, 2015. Ask Doctor T, Your Heart Rhythm Leave a Comment ... Fainting. In some people with long QT syndrome, fainting spells are caused by an arrhythmia that results in your heart not ... "Long QT syndrome" (LQTS), which is a potentially dangerous arrhythmia that can result in sudden fainting spells or even ...
The long-QT syndrome (LQTS) is an inherited heart rhythm disorder characterized by a prolonged QT interval on the ... The Long-QT Syndrome and Exercise Practice: The Never-ending Debate. Giuseppe Mascia MD, PhD; Elena Arbelo MD, PhD; Francesco ... Table 2. Evolution of long-QT syndrome sport restriction guidelines Bethesda 36th conference (2005). European Society of ... Table 1. Characteristics of long-QT syndrome subtypes LQTS 1. LQTS 2. LQTS 3. ...
Dive into the research topics of Ion channel complex disease in long QT syndrome. Together they form a unique fingerprint. ...
... Long QT (LQT) syndrome is a cardiac arrhythmia diagnosis that is reflective of a description ... "The genetic basis of long QT and short QT syndromes: a mutation update". Hum. Mutat. 30 (11): 1486-511. doi:10.1002/humu.21106 ... Morita H, Wu J, Zipes DP (August 2008). "The QT syndromes: long and short". Lancet. 372 (9640): 750-63. doi:10.1016/S0140-6736( ... Wu, J., Ding, W. G., & Horie, M. (2016). Molecular pathogenesis of long QT syndrome type 1. Journal of arrhythmia, 32(5), 381- ...
5) Long QT Syndrome (LQTS). The QT interval should be measured in lead II, V3 or V5. It increases with age and female sex and ... QT interval in idiopathic ventricular fibrillation and long QT syndrome. Sugao M et al. Heart. 2006; 92(9): 201-207. 14) ... Utility of treadmill testing in identification and genotype prediction in long-QT syndrome.. Wong et al. Circ Arrhythm ... Possible causes for a long QT interval (Table 6) should be excluded and an echocardiogram performed to discount a structural ...
Elucidating the role of Cavin1 in drug-induced long QT syndrome (diLQTS). ... Metabolic treatment of an electrical disease? - Beneficial APD/QT prolongation by L-Carnitine in transgenic SQT1 rabbit models ...
  • Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval. (wikipedia.org)
  • LQTS can be diagnosed using an electrocardiogram (EKG) if a corrected QT interval of greater than 450-500 milliseconds is found, but clinical findings, other EKG features, and genetic testing may confirm the diagnosis with shorter QT intervals. (wikipedia.org)
  • While some have QT intervals that are very prolonged, others have only slight QT prolongation, or even a normal QT interval at rest (concealed LQTS). (wikipedia.org)
  • Despite this, those with only subtle QT prolongation or concealed LQTS still have some risk of arrhythmias. (wikipedia.org)
  • As the QT prolonging effects of both genetic variants and acquired causes of LQTS are additive, those with inherited LQTS are more likely to experience TdP if given QT prolonging drugs or if they experience electrolyte problems such as low blood levels of low potassium (hypokalaemia). (wikipedia.org)
  • Long QT syndrome (LQTS) is a problem with the heart's electrical conduction system that may prevent the heart from pumping properly, leading to palpitations, blackouts, seizures, and life threatening arrhythmias. (medicalnewstoday.com)
  • In LQTS, the interval lasts longer than usual, which reflects an extended duration or prolongation of the recovery phase of the ventricles. (medicalnewstoday.com)
  • Long QT syndrome (LQTS) is a congenital disorder characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. (medscape.com)
  • Marked prolongation of QT interval in a 15-year-old male adolescent with long QT syndrome (LQTS) (R-R = 1.00 s, QT interval = 0.56 s, QT interval corrected for heart rate [QTc] = 0.56 s). (medscape.com)
  • Findings on physical examination usually do not indicate a diagnosis of LQTS, although some patients may present with excessive bradycardia for their age, and some patients may have hearing loss (congenital deafness), indicating the possibility of Jervell and Lange-Nielsen syndrome. (medscape.com)
  • An increased corrected QT (QTc) interval in response to standing up ("response to standing" test), which is associated with increased sympathetic tone, can provide more diagnostic information in patients with LQTS. (medscape.com)
  • Although a number of approaches (e.g., beta blockers, permanent pacing, left cervicothoracic sympathectomy, ICD implantation) have been proposed as therapeutic options for patients with the congenital long QT syndromes (LQTS), beta blocker therapy has served as the mainstay of treatment for the majority of these patients. (acc.org)
  • regarding patients with congenital long QT syndrome (LQTS). (asahq.org)
  • It becomes increasingly apparent that the QT interval prolongation per se is not the crucial pathology in LQTS. (asahq.org)
  • Accordingly, studies that only focus on drug effects on the QT interval may produce premature conclusions regarding potential safety or risk of these drugs in LQTS. (asahq.org)
  • The long QT interval syndromes (LQTS) result from any congenital or acquired disorder of cardiac ion channel function or regulation (channelopathy) that prolongs ventricular myocyte action potential duration as reflected by prolongation of the rate-corrected QT interval on the ECG. (msdmanuals.com)
  • Abnormal action potential (AP) properties, as occurs in long or short QT syndromes (LQTS and SQTS, respectively), can cause life-threatening arrhythmias. (jci.org)
  • Long QT syndrome (LQTS) can present as unexpected fainting, ventricular arrhythmias and sudden cardiac death in patients with structurally normal hearts. (ghcgenetics.com)
  • In contrast biallelic mutations in KCNQ1 cause Jervell and Lange-Nielsen syndrome (JLNS), which is more severe LQTS phenotype with or without congenital deafness. (ghcgenetics.com)
  • Long QT syndrome (LQTS) is a heart rhythm disorder that can potentially cause fast, out of control heartbeats. (demanddeborah.org)
  • Long QT syndrome (LQTS) is a disease that can cause a dangerous rapid heart rate and irregular rhythm involving the bottom pumping chambers of the heart (ventricles). (diseasesdic.com)
  • Most people with long QT syndrome (LQTS) have the inherited form, which means that you are born with the condition. (diseasesdic.com)
  • The prevalence of congenital causes, also known as Long QT syndrome (LQTS), is difficult to estimate but may be expected in 1 in 2,500 to 1 in 10,000 individuals. (diseasesdic.com)
  • Long QT syndrome (LQTS) is a cardiac disorder characterized by a prolonged QT interval on the electrocardiogram (ECG), which can lead to life-threatening arrhythmias, particularly torsades de pointes. (madeformedical.com)
  • What is QTc and Long QT syndrome (LQTS)? (cardiachealth.org)
  • Patients with long QT syndrome (LQTS) should avoid drugs that prolong the QT interval or reduce their serum potassium or magnesium levels. (cardiachealth.org)
  • Today, understanding the true risk of adverse events in long-QT syndrome (LQTS) populations may be extremely complex and potentially dependent on many factors such as the affected gene, mutation location, degree of QTc prolongation, age, sex, and other yet unknown factors. (medscape.com)
  • The long-QT syndrome (LQTS) is an inherited heart rhythm disorder characterized by a prolonged QT interval on the electrocardiogram (ECG), due to delayed cardiac repolarization, in the absence of documented structural heart disease. (medscape.com)
  • Background: Long-QT syndrome (LQTS), an inherited cardiac repolarization disorder, is an important cause of fetal and neonatal mortality. (elsevierpure.com)
  • In this study, we assess the dynamic coupling between RR and QT intervals for subjects with long QT syndrome (LQTS) - a potentially fatal genetic cardiac disease characterized by delayed myocardial repolarization. (tuni.fi)
  • Using 24-hour Holter ECGs, we calculate TE as a function of RR and QT histories up to 50 beats and compare the results between the healthy controls and the subjects of LQTS type 1 and 2. (tuni.fi)
  • Asymmetry between TERR→ QT and TEQT RR was observed for the LQTS subjects. (tuni.fi)
  • Compared to the healthy, the LQTS subjects had significantly smaller TERR→QT at RR history lengths longer than about 18 beats, while TEQT→ RR was significantly larger at all RR and QT history lengths. (tuni.fi)
  • Aging had no significant effect on TERR→QT, but reduced TEQT→ RR for the LQTS subjects, whereas the gender and beta blocker were found to have relatively small effects on the TE. (tuni.fi)
  • In conclusion, the dynamic coupling between RR and QT intervals is altered by LQTS. (tuni.fi)
  • Long QT syndrome (LQTS) is an inherited disorder associated with life-threatening ventricular arrhythmias. (tau.ac.il)
  • Long QT syndrome (LQTS) is a heritable channelopathy characterized by an exceedingly prolonged cardiac repolarization that may trigger ventricular arrhythmias (torsade de pointes), recurrent syncopes, seizure, or sudden cardiac death (SCD) (Cerrone et al. (preventiongenetics.com)
  • Background: Unfortunately, some patients with long QT syndrome (LQTS) experience breakthrough cardiac events (BCEs) despite maximal therapy. (elsevierpure.com)
  • Inherited long QT syndrome (LQTS) is caused by mutations in ion channels that delay cardiac repolarization, increasing the risk of sudden death from ventricular arrhythmias. (johnshopkins.edu)
  • Currently, the risk of sudden death in individuals with LQTS is estimated from clinical parameters such as age, gender, and the QT interval, measured from the electrocardiogram. (johnshopkins.edu)
  • Background and purpose: Many drugs associated with acquired long QT syndrome (LQTS) directly block human ether-a-go-go-related gene (hERG) K + channels. (uky.edu)
  • We provide definitive evidence for the long-term efficacy of LCSD in LQTS. (acc.org)
  • Aims: In long QT syndrome (LQTS) patients, modifier genes modulate the arrhythmic risk associated with a disease-causing mutation. (unimib.it)
  • Similarly, those taking QT prolonging medications are more likely to experience TdP if they have a genetic tendency to a prolonged QT interval, even it this tendency is concealed. (wikipedia.org)
  • slightly prolonged QT interval s. (scirp.org)
  • Torsade de pointes, often referred to as torsade, is associated with a prolonged QT interval, which may be congenital or acquired. (medscape.com)
  • Torsades de pointes with prolonged QT interval (12-lead ECG of torsades de pointes (TdP) in a 56-year-old white female with low blood potassium (2.4 mmol/L) and low blood magnesium (1.6 mg/dL). (medscape.com)
  • The association between torsade and a prolonged QT interval has long been known, but the mechanisms involved at the cellular and ionic levels have been made clearer in approximately the last decade. (medscape.com)
  • While those with long QT syndrome have an increased risk of developing abnormal heart rhythms, the absolute risk of arrhythmias is very variable. (wikipedia.org)
  • In addition to a history of arrhythmias, the extent to which the QT is prolonged predicts risk. (wikipedia.org)
  • A longer QT interval increases the risk of life threatening arrhythmias. (medicalnewstoday.com)
  • When the interval lasts longer than it normally should, it disrupts the timing of your heartbeat and can cause dangerous arrhythmias, or irregular heart rates. (diseasesdic.com)
  • This syndrome, once diagnosed by clinical profile, has been more clearly defined by specific genetic defects that cause ion channel abnormalities, resulting in a syndrome that predisposes to lethal cardiac arrhythmias. (medscape.com)
  • Evaluate the results of Holter monitoring, if available, to identify episodes of arrhythmias or QT interval abnormalities during daily activities. (madeformedical.com)
  • Mutations in SCN5A, encoding the cardiac sodium (Na) channel, are linked to a form of the congenital long-QT syndrome (LQT3) that provokes lethal ventricular arrhythmias. (johnshopkins.edu)
  • Those with the longest QT intervals are more likely to experience TdP, and a corrected QT interval of greater than 500 ms is thought to represent those at higher risk. (wikipedia.org)
  • Overall, every 10 ms increase in the corrected QT interval is associated with a 15% increase in arrhythmic risk. (wikipedia.org)
  • The congenital long QT interval syndromes result from genetic disorders of cardiac ion channel function or regulation (channelopathies) that prolong ventricular myocyte action potential duration as reflected by prolongation of the rate-corrected QT interval on the ECG (QTc, typically calculated using Bazett's formula). (msdmanuals.com)
  • [ 1 ] The diagnosis is suggested when ventricular repolarization abnormalities result in prolongation of the corrected QT interval. (medscape.com)
  • Moss reported that LQT1 patients with transmembrane mutations and dominant-negative ion current effects had longer corrected QT interval and a higher frequency of cardiac events than individuals with mutations in other regions. (studybay.net)
  • The QT interval obtained by a 12-lead electrocardiogram is only a rough measure of the repolarization time. (asahq.org)
  • The abnormality underlying both acquired and congenital long QT syndromes is in the ionic current flow during repolarization, which affects the QT interval. (medscape.com)
  • These abnormalities are characterized by delayed myocardial repolarization that leads to varying degrees of QT prolongation and T-wave abnormalities on an EKG. (studybay.net)
  • Treatment may be accompanied by prolongation of the QT interval of the electrocardiogram and torsades de pointes tachycardias. (aspetjournals.org)
  • Some rare forms of long QT syndrome affect other parts of the body, leading to deafness in the Jervell and Lange-Nielsen form of the condition, and periodic paralysis in the Andersen-Tawil (LQT7) form. (wikipedia.org)
  • Jervell and Lang-Nielsen (JLN) syndrome is an autosomal recessive form of congenital long QT syndrome. (medscape.com)
  • All patients with symptoms suggestive of Long QT syndrome and Jervell and Lange-Nielsen syndrome are candidates for this test. (preventiongenetics.com)
  • The name, long QT, stems from a reading on the electrocardiogram (ECG) machine. (diseasesdic.com)
  • Schwartz et al suggested incorporating clinical and electrocardiogram (ECG) findings in a probability-based diagnostic criteria for long QT syndrome. (medscape.com)
  • ences in QT intervals. (scirp.org)
  • longed QT intervals. (scirp.org)
  • QT intervals, corrected for heart rate (QTc) that are longer than 440 mseconds, are generally considered abnormal, though a normal QTc can be more prolonged in females (up to 460 msec). (cardiachealth.org)
  • Healthy subjects exhibit strong information transfer from RR to QT intervals. (tuni.fi)
  • We use transfer entropy (TE) to quantify the magnitude and direction of the information exchange between the RR and QT intervals. (tuni.fi)
  • This study will investigate the effects of oral progesterone for older women and testosterone for older men on QT intervals. (nih.gov)
  • QT intervals that are increased by medicine can lead to dangerous heart rhythm problems. (nih.gov)
  • It is a relatively common cause of sudden death along with Brugada syndrome and arrhythmogenic right ventricular dysplasia. (wikipedia.org)
  • Sometimes you can't tell that you have a sudden arrythmia death syndrome (SADS) condition until you undergo genetic testing. (sads.org)
  • Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death, Colleen E. Clancy and Yoram Rudy, 2001, Cardiovascular Research , 50, 301-313. (cellml.org)
  • Sudden death is the first symptom in 10%-15% of long QT syndrome patients. (ghcgenetics.com)
  • Family history is positive for Long QT syndrome in 40%, and for sudden cardiac death in 30% of patients. (diseasesdic.com)
  • Many causes of sudden death in the pediatric population are due to genetic heart disorders, which can lead to structural abnormalities (eg, hypertrophic cardiomyopathy) and arrhythmogenic abnormalities (eg, familial long QT syndrome). (medscape.com)
  • The management of Long QT syndrome requires a comprehensive and individualized approach to reduce the risk of sudden cardiac events and improve the patient's quality of life. (madeformedical.com)
  • Explore the patient's family history for any known cases of Long QT syndrome or sudden cardiac events, as this condition can have a genetic predisposition. (madeformedical.com)
  • In patients with moderate QT prolongation (a QT interval less than 500 ms), slower activation was an independent predictor for cardiac events (syncope, aborted cardiac arrest, and sudden death) (hazard ratio = 2.10), whereas the length of the QT interval itself was not. (johnshopkins.edu)
  • Many people with long QT syndrome have no signs or symptoms. (wikipedia.org)
  • In some people with long QT syndrome, fainting spells are caused by an arrhythmia that results in your heart not pumping enough blood to your brain. (cardiachealth.org)
  • We propose that pentamidine, like arsenic trioxide, produces QT prolongation and torsades de pointes in patients by inhibition of hERG trafficking. (aspetjournals.org)
  • Furthermore, among a small group of patients who were switched from propranolol to metoprolol, the QTc on metoprolol was significantly longer than on propranolol (p=0.004). (acc.org)
  • Kies JS, Pabelick CM, Hurley HA, White RD, Ackerman MJ: Anesthesia for patients with congenital long QT syndrome. (asahq.org)
  • Torsades de Pointes Ventricular Tachycardia Torsades de pointes ventricular tachycardia is a specific form of polymorphic ventricular tachycardia in patients with a long QT interval. (msdmanuals.com)
  • Ideal for patients with a clinical suspicion or diagnosis of long QT syndrome. (ghcgenetics.com)
  • Some studies report the prevalence of QT prolongation to be as many as 30% of patients in the intensive care unit. (diseasesdic.com)
  • Our approach to caring for patients with Long QT syndrome involves close collaboration with the healthcare team, including cardiologists, electrophysiologists, and genetic counselors. (madeformedical.com)
  • We believe that informed patients and caregivers are better equipped to manage Long QT syndrome, make informed decisions, and actively participate in their care. (madeformedical.com)
  • LQT1 is is a subtype of congenital cardiac syndrome and is typically inherited in an autosomal dominant manner, as most patients have an affected parent and it is the most common type of LQT syndrome 3 . (studybay.net)
  • OBJECTIVE: To investigate the molecular pathogenesis for two novel mutations L413P and L559H of KCNH2 found in Chinese patients with long QT syndrome. (elsevierpure.com)
  • In particular, the use of group IA antidysrhythmic drugs, which tend to prolong the QT interval, can have disastrous consequences in torsade. (medscape.com)
  • This delay in recharge leads to prolong QT segment on ECG. (yesdoct.com)
  • Document the patient's current and past medications, specifically focusing on medications that may prolong the QT interval or interact with QT-prolonging medications. (madeformedical.com)
  • 120ms) is commonly found in trained athletes but care is needed not to miss underlying pathology such as an atrial septal defect, brugada syndrome or arrhythmogenic right ventricular cardiomyopathy (see below) ( 1 ). (escardio.org)
  • Any electrolyte disturbance can cause QT interval prolongation. (medicalnewstoday.com)
  • Any disturbance in these ion channels can lead to excess positive ions inside the cell, causing QT interval prolongation. (medicalnewstoday.com)
  • Per Dr. Michael J. Ackerman, he states in 'Genetics of Long QT Syndrome,' that "These genes account for approximately 75% of the disorder" 1 . (studybay.net)
  • ABSTRACT: BACKGROUND: A variety of mutations in HERG, the major subunit of the rapidly activating component of the cardiac delayed rectifier I(Kr), have been found to underlie the congenital Long-QT syndrome, LQT2. (cellml.org)
  • OBJECTIVE: We attempt to elucidate the mechanisms by which heterogeneous LQT2 genotypes can lead to prolongation of the action potential duration (APD) and consequently the QT interval on the ECG. (cellml.org)
  • The average characteristic RR history length that maximized TERR→ QT was 27 beats for the healthy subjects, which was significantly longer than 21 and 22 beats for LQTl and LQT2, respectively. (tuni.fi)
  • The establishment of a long QT syndrome registry and the discovery of genetic mutations that cause long QT syndrome have greatly contributed to the understanding of this condition. (medscape.com)
  • Since the first report in 1991 of a deoxyribonucleic acid (DNA) marker in the short arm of chromosome 11, numerous studies have reported genetic mutations and molecular descriptions of ion channel abnormalities in long QT syndrome. (medscape.com)
  • Confirm the diagnosis of Long QT syndrome through review of the patient's medical records, including electrocardiograms (ECGs), genetic testing results, and previous Holter monitor reports. (madeformedical.com)
  • Up to now, it has been thought that therapeutic compounds causing QT prolongation are associated with direct block of the cardiac potassium channel human ether a-go-go-related gene (hERG), which encodes the α subunit of cardiac I Kr currents. (aspetjournals.org)
  • Skeletal abnormalities, such as short stature and scoliosis are seen in the LQT7 type (Andersen syndrome), and congenital heart diseases, cognitive and behavioral problems, musculoskeletal diseases, and immune dysfunction may be seen in those with LQT8 type (Timothy syndrome). (medscape.com)
  • Long QT syndrome is a genetically transmitted cardiac arrhythmia caused by ion channel protein abnormalities. (medscape.com)
  • T-wave abnormalities are represented by longer time from Q wave to the T wave, allowing for longer time for the heart to repolarize. (studybay.net)
  • Epilepsy is also associated with certain types of long QT syndrome. (wikipedia.org)
  • We present a case of long QT syndrome that remained undiagnosed in the epilepsy clinic for 15 years until a near-fatal arrhythmia revealed the diagnosis and allowed effective treatment of her attacks. (bmj.com)
  • We hope this near miss raises awareness of long QT syndrome as a potentially fatal, rare but treatable condition that neurologists must consider in people with a label of refractory epilepsy. (bmj.com)
  • Long QT syndrome can be mistaken for palpitations, neurocardiogenic syncope, and epilepsy. (medscape.com)
  • Hence, the clinical and electrophysiologic presentations of the syndrome are considerably heterogeneous, and the effects of different drugs may be unpredictable. (asahq.org)
  • Sinus node disease encompasses a wide range of clinical presentations from sinus bradycardia to sinus arrest or bradycardia-tachycardia syndrome ( 4 ). (escardio.org)
  • Finally, it seems appropriate to consider the "sodium channel syndrome" (mutations in the gene of the α subunit of the sodium channel, SCN5A gene) as a single clinical entity that may manifest in a wide range of phenotypes, to thus have a better insight on these cardiac syndromes and potential outcomes for their clinical treatment. (bvsalud.org)
  • Long QT interval is a condition that affects the heart's electrical rhythm, which can lead to potentially life threatening arrhythmia. (medicalnewstoday.com)
  • The QT interval duration depends heavily on the electrical activity of the ventricles. (medicalnewstoday.com)
  • Review the most recent ECG results to assess the QT interval duration and morphology. (madeformedical.com)
  • If I have QT 380, what is the QTc duration?And what you think about overstimation of QT if U wave is present? (cardiachealth.org)
  • Only few studies have focused on QT heterogeneity or ion channel physiology, and it seems that all volatile anesthetics-including isoflurane-interact directly with cardiac delayed rectifier potassium channels. (asahq.org)
  • Romano-Ward syndrome (RWS) is the dominant form. (medscape.com)
  • LQT1 accounts for about 42% of all long QT syndrome cases and occurs due to heterozygous mutations in the KCNQ1 (KvLQT1) gene (Splawski et al. (preventiongenetics.com)
  • Usually in this syndrome heart rhythms take longer than normal to recharge between the rhythms. (yesdoct.com)
  • The 404 kb long gene codes for a 75-kDa protein containing 676 amino acids and is expressed mainly in the heart, kidneys, pancreas, and small intestine. (studybay.net)
  • Pre- and post-IPAP heart rate, heart rate-corrected QT (QTc) values, annual BCE rate, and IPAP-related complications were compared between genotypes. (elsevierpure.com)
  • Discuss the need for lifestyle modifications, including restrictions on strenuous physical activity and the avoidance of known QT-prolonging triggers. (madeformedical.com)