Long QT syndrome
Classification & external resources

Schematic representation of normal ECG trace (sinus rhythm), with waves, segments, and intervals labeled.
ICD-10	I45.8
ICD-9	426.82
DiseasesDB	11104
eMedicine	med/1983
MeSH	D008133

The long QT syndrome (LQTS) is a heart disease in which there is an abnormally long delay between the electrical excitation (or depolarization) and relaxation (repolarization) of the ventricles of the heart. It is associated with syncope (fainting) and with sudden death due to ventricular arrhythmias. Arrhythmias in individuals with LQTS are often associated with exercise or excitement. The cause of sudden cardiac death in individuals with LQTS is ventricular fibrillation. Image File history File links SinusRhythmLabels. ... Sinus rhythm is indicative of normal electrical conductance of the heart. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // I00-I99 - Diseases of the circulatory system (I00-I02) Acute rheumatic fever (I00) Rheumatic fever without mention of heart involvement (I01) Rheumatic fever with heart involvement (I02) Rheumatic chorea (I05-I09) Chronic rheumatic heart diseases (I05) Rheumatic mitral valve diseases (I050) Mitral stenosis (I051) Rheumatic mitral insufficiency (I06) Rheumatic aortic... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... The heart and lungs, from an older edition of Grays Anatomy. ... In biology, depolarization is the event a cell undergoes when its membrane potential grows more positive with respect to the extracellular solution. ... In the heart, a ventricle is a heart chamber which collects blood from an atrium (another heart chamber that is smaller than ventricle) and pumps it out of the heart. ... The term Faint redirects here. ... Sudden death is a way of providing a winner for a sports contest which would otherwise end in a tie. ... In the heart, a ventricle is a chamber which collects blood from an atrium (another heart chamber) and pumps it out of the heart. ... Cardiac arrhythmia is a group of conditions in which the muscle contraction of the heart is irregular or is faster or slower than normal. ... Ventricular fibrillation (V-fib or VF) is a cardiac condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart that eventually leads to the heart stopping altogether. ...

Individuals with LQTS have a prolongation of the QT interval on the ECG. The Q wave on the ECG corresponds to ventricular depolarization while the T wave corresponds to ventricular repolarization. The QT interval is measured from the Q point to the end of the T wave. While many individuals with LQTS have persistent prolongation of the QT interval, some individuals do not always show the QT prolongation; in these individuals, the QT interval may prolong with the administration of certain medications. Schematic representation of normal ECG trace (sinus rhythm), with waves, segments, and intervals labeled. ... Lead II An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. ... Lead II An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. ... Lead II An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. ...

Genetics

The two most common types of LQTS are genetic and drug-induced. Genetic LQTS can arise from mutation to one of several genes. These mutations tend to prolong the duration of the ventricular action potential (APD), thus lengthening the QT interval. LQTS can be inherited in an autosomal dominant or an autosomal recessive fashion. The autosomal recessive forms of LQTS tend to have a more severe phenotype, with some variants having associated syndactyly (LQT8) or congenital neural deafness (LQT1). A number of specific genes loci have been identified that are associated with LQTS. Following is a list of the most common mutations: At rest, the ventricular myocyte membrane potential is about -80 mV, which is close to the potassium reversal potential. ... It has been suggested that this article or section be merged into Dominance relationship. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ... In zoology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of an animal. ...

Drug induced LQT is usually a result of treatment by anti-arrhythmic drugs such as amiodarone or a number of other drugs that have been reported to cause this problem (e.g. cisapride). Some anti-psychotic drugs, such as Haloperidol and Ziprasidone, have a prolonged QT interval as a rare side effect. Genetic mutations may make one more prone to drug induced LQT. KvLQT1 is a potassium channel protein coded for by the gene KCNQ1. ... HERG (Human Ether-a-go-go Related Gene). ... Sodium channels are integral membrane proteins that exist in a cells plasma membrane and regulate the flow of sodium (Na+) ions into it. ... SCN5A is a sodium ion channel associated with long QT syndrome type 3 (LQT3), Brugada syndrome, and idiopathic ventricular fibrillation. ... Ankyrin is a membrane protein that mediates the attachment of the erythrocyte membrane skeleton to the plasma membrane and interacts with CD44 and inositol triphosphate. ... KCNE1 is a gene associated with Long QT syndrome type 5. ... KvLQT1 is a potassium channel protein coded for by the gene KCNQ1. ... HERG (Human Ether-a-go-go Related Gene). ... KCNJ2 is a gene encoding a inward-rectifier potassium ion channel. ... Andersen-Tawil syndrome, also called Andersen syndrome and Long QT syndrome 7 is a form of long QT syndrome. ... Ion channels are present in the membranes that surround all biological cells. ... CACNA1C is a gene which codes a L-type voltage-dependent calcium channel associated with Timothys syndrome. ... Timothy syndrome is a rare autosomal dominant disorder characterized by physiological and developmental defects, including heart QT-prolongation, heart arrhythmias, structural heart defects, syndactyly (webbing of fingers and toes) and autism spectrum disorders. ... The caveolin gene family has three members in vertebrates: CAV1, CAV2, and CAV3, coding for the proteins caveolin-1, caveolin-2 and caveolin-3, respectively. ... Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress fast rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. ... Amiodarone belongs to a class of drugs called Vaughan-Williams Class III antiarrhythmic agent. ... Cisapride is a parasympathomimetic which acts as a serotonin 5-HT4 agonist. ... The term antipsychotic is applied to a group of drugs used to treat psychosis. ... Haloperidol (sold as Aloperidin®, Bioperidolo®, Brotopon®, Dozic®, Einalon S®, Eukystol®, Haldol®, Halosten®, Keselan®, Linton®, Peluces®, Serenace®, Serenase®, Sigaperidol®) is a conventional butyrophenone antipsychotic drug. ... Ziprasidone (sold as Geodon®) was the fifth atypical antipsychotic to gain FDA approval. ...

LQT1

LQT1 is the most common type of long QT syndrome, making up about 40 to 55 percent of all cases. The LQT1 gene is KCNQ1 which has been isolated to chromosome 11p15.5. KCNQ1 codes for the voltage-gated potassium channel KvLQT1 that is highly expressed in the heart. It is believed that the product of the KCNQ1 gene produces an alpha subunit that interacts with other proteins (particularly the minK beta subunit) to create the I_Ks ion channel, which is responsible for the delayed potassium rectifier current of the cardiac action potential. For other meanings of this term, see gene (disambiguation). ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... KvLQT1 is a potassium channel protein coded for by the gene KCNQ1. ... The cardiac action potential is the electrical activity of the individual cells of the electrical conduction system of the heart. ...

Mutations to the KCNQ1 gene can be inherited in an autosomal dominant or an autosomal recessive pattern in the same family. In the autosomal recessive mutation of this gene, homozygous mutations in KVLQT1 leads to severe prolongation of the QT interval (due to near-complete loss of the I_Ks ion channel), and is associated with increased risk of ventricular arrhythmias and congenital deafness. This variant of LQT1 is known as the Jervell and Lange-Nielsen syndrome. It has been suggested that this article or section be merged into Dominance relationship. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... Homozygote cells are diploid or polyploid and have the same alleles at a locus (position) on homologous chromosomes. ... Jervell and Lange-Nielsen syndrome is a condition that causes profound hearing loss and arrhythmia, it is a type of long QT syndrome. ...

Most individuals with LQT1 show paradoxical prolongation of the QT interval with infusion of epinephrine. This can also unmark latent carriers of the LQT1 gene. Adrenaline redirects here. ...

Many missense mutations of the LQT1 gene have been identified. These are often associated with a high risk percentage of symptomatic carriers and sudden death. Missense mutations or nonsynonymous mutations are types of point mutations where a nucleotide is changed which results in a different amino acid. ...

LQT2

The LQT2 type is the second most common gene location that is affected in long QT syndrome, making up about 35 to 45 percent of all cases. This form of long QT syndrome most likely involves mutations of the human ether-a-go-go related gene (HERG) on chromosome 7. The HERG gene (also known as KCNH2) is part of the rapid component of the potassium rectifying current (I_Kr). (The I_Kr current is mainly responsible for the termination of the cardiac action potential, and therefore the length of the QT interval.) The normally functioning HERG gene allows protection against early after depolarizations (EADs). HERG (Human Ether-a-go-go Related Gene). ... HERG (Human Ether-a-go-go Related Gene). ... The cardiac action potential is the electrical activity of the individual cells of the electrical conduction system of the heart. ... HERG (Human Ether-a-go-go Related Gene). ...

Most drugs that cause long QT syndrome do so by blocking the I_Kr current via the HERG gene. These include erythromycin, terfenadine, and ketoconazole. The HERG channel is very sensitive to unintended drug binding due to two aromatic amino acids, the tyrosine at position 652 and the phenylalanine at position 656. These amino acid residues are poised so drug binding to them will block the channel from conducting current. Other potassium channels do not have these residues in these positions and are therefore not as prone to blockage. HERG (Human Ether-a-go-go Related Gene). ... Erythromycin is a macrolide antibiotic which has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. ... Terfenadine is an antihistamine formerly used for the treatment of allergic conditions. ... Nizoral® logo Ketoconazole is a synthetic antifungal drug used to prevent and treat skin and fungal infections, especially in immunocompromised patients such as those with AIDS. Due to its side-effect profile, it has been superseded by newer antifungals, such as fluconazole and itraconazole. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Phenylalanine is one of the standard amino acids. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in cheese[1][2]), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. ... It has been suggested that DL-Phenylalanine be merged into this article or section. ...

LQT3

The LQT3 type of long QT syndrome involves mutation of the gene that encodes the alpha subunit of the Na⁺ ion channel. This gene is located on chromosome 3p21-24, and is known as SCN5A (also hH1 and Na_V1.5). The mutations involved in LQT3 slow the inactivation of the Na⁺ channel, resulting in prolongation of the Na⁺ influx during depolarization. Paradoxically, the mutant sodium channels inactivate more quickly, and may open repetitively during the action potential. General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... SCN5A is a sodium ion channel associated with long QT syndrome type 3 (LQT3), Brugada syndrome, and idiopathic ventricular fibrillation. ...

A large number of mutations have been characterized as leading to or predisposing LQT3. Calcium has been suggested as a regulator of SCN5A, and the effects of calcium on SCN5A may begin to explain the mechanism by which some these mutations cause LQT3.

LQT5

is an autosomal dominant relatively uncommon form of LQTS. It involves mutations in the gene KCNE1 which encodes for the potassium channel beta subunit MinK. In its rare homozygous forms it can lead to Jervell and Lange-Nielsen syndrome It has been suggested that this article or section be merged into Dominance relationship. ... Jervell and Lange-Nielsen syndrome is a condition that causes profound hearing loss and arrhythmia, it is a type of long QT syndrome. ...

LQT6

is an autosomal dominant relatively uncommon form of LQTS. It involves mutations in the gene KCNE2 which encodes for the potassium channel beta subunit MiRP1, constituting part of the I_Kr repolarizing K⁺ current. It has been suggested that this article or section be merged into Dominance relationship. ...

LQT7

Andersen-Tawil syndrome is an autosomal dominant form of LQTS associated with skeletal deformities. It involves mutation in the gene KCNJ2 which encodes for the potassium channel protein Kir 2.1. The syndrome is characterized by Long QT syndrome with ventricular arrhythmias, periodic paralysis and skeletal developmental abnormalities as clinodactyly, low-set ears and micrognathia. The manifestations are highly variable.^[1] Andersen-Tawil syndrome, also called Andersen syndrome and Long QT syndrome 7 is a form of long QT syndrome. ... It has been suggested that this article or section be merged into Dominance relationship. ... Micrognathia is a medical term for an unnaturally small jaw. ...

LQT8

Timothy's syndrome is due to mutations in the calcium channel Cav1.2 encoded by the gene CACNA1c. Since the Calcium channel Cav1.2 is abundant in many tissues, patients with Timothy's syndrome have many clinical manifestations including congenital heart disease, autism, syndactyly and immune deficiency.

LQT9

This newly discovered variant is caused by mutations in the membrane structural protein, caveolin-3. Caveolins form specific membrane domains called caveolae in which among others the Na_V1.5 voltage-gated sodium channel sits. Similar to LQT3, these particular mutations increase so-called 'late' sodium current which impairs cellular repolarization. The caveolin gene family has three members in vertebrates: Caveolin-1, Caveolin-2, and Caveolin-3. ... In biology, caveolae (Latin for little caves) are small invaginations of the plasma membrane in many cell types, especially in endothelial cells. ... Sodium channels (also known as voltage-gated sodium channels) are integral membrane proteins that are localized in and conduct sodium ions (Na+) through a cells plasma membrane. ... In neuroscience, repolarization refers to the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value. ...

LQT10

This novel susceptibility gene for LQT is SCN4B encoding the protein Na_Vβ4, an auxiliary subunit to the pore-forming Na_V1.5 (gene: SCN5A) subunit of the voltage-gated sodium channel of the heart. The mutation leads to a positive shift in inactivation of the sodium current, thus increasing sodium current. Only one mutation in one patient has so far been found. In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles (or coassembles) with other protein molecules to form a multimeric or oligomeric protein. ... Sodium channels (also known as voltage-gated sodium channels) are integral membrane proteins that are localized in and conduct sodium ions (Na+) through a cells plasma membrane. ...

Associated syndromes

A number of syndromes are associated with LQTS.

Jervell and Lange-Nielsen syndrome

The Jervell and Lange-Nielsen syndrome (JLNS) is an autosomal recessive form of LQTS with associated congenital deafness. It is caused specifically by mutation of the KCNE1 and KCNQ1 genes. Jervell and Lange-Nielsen syndrome is a condition that causes profound hearing loss and arrhythmia, it is a type of long QT syndrome. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ...

In untreated individuals with JLNS, about 50 percent die by the age of 15 years due to ventricular arrhythmias.

Romano-Ward syndrome

Romano-Ward syndrome is an autosomal dominant form of LQTS that is not associated with deafness. Romano-Ward syndrome, is the major variant of long QT syndrome. ...

Mechanism of arrhythmia generation

All forms of the long QT syndrome involve an abnormal repolarization of the heart. The abnormal repolarization causes differences in the "refractoriness" of the myocytes. After-depolarizations (which occur more commonly in LQTS) can be propagated to neighboring cells due to the differences in the refractory periods, leading to re-entrant ventricular arrhythmias. Myocyte is the technical term for a muscle cell. ... A refractory period, in physiology, is a period of time during which an organ or cell is incapable of performing a particular action. ...

It is believed that the so-called early after-depolarizations (EADs) that are seen in LQTS are due to re-opening of L-type calcium channels during the plateau phase of the cardiac action potential. Since adrenergic stimulation can increase the activity of these channels, this is an explanation for why the risk of sudden death in individuals with LQTS is increased during increased adrenergic states (ie exercise, excitement) -- especially since repolarization is impared. Normally during adrenergic states, repolarizing currents will also be enhanced to shorten the action potential. In the absence of this shortening and the presence of increased L-type calcium current, EADs may arise. The cardiac action potential is the electrical activity of the individual cells of the electrical conduction system of the heart. ... An adrenergic is a drug, or other substance, which has effects similar to, or the same as, epinephrine (adrenaline). ...

The so-called delayed after-depolarizations (DADs) are thought to be due to an increased Ca²⁺ filling of the sarcoplasmic reticulum. This overload may cause spontaneous Ca²⁺ release during repolarization, causing the released Ca²⁺ to exit the cell through the 3Na⁺/Ca²⁺-exchanger which results in a net depolarizing current. ...

Diagnosis

The diagnosis of LQTS is not easy since 2.5% of the healthy population have prolonged QT interval, and 10% of LQTS patients have a normal QT interval. A commonly used criterion to diagnose LQTS is the LQTS "diagnostic score" ^[2]. Its based on several criteria giving points to each. With 4 or more points the probability is high for LQTS, and with 1 or less point the probability is low. Two or 3 points indicates intermediate probability.

• QTc (Defined as QT interval / square root of RR interval)
  • >= 480 msec - 3 points
  • 460-470 msec - 2 points
  • 450 msec and male gender - 1 point
• Torsades de Pointes ventricular tachycardia - 2 points
• T wave alternans - 1 point
• Notched T wave in at least 3 leads - 1 point
• Low heart rate for age (children) - 0.5 points
• Syncope (one cannot receive points both for syncope and Torsades de pointes)
  • With stress - 2 points
  • Without stress - 1 point
• Congenital deafness - 0.5 points
• Family history (the same family member cannot be counted for LQTS and sudden death)
  • Other family members with definite LQTS - 1 point
  • Sudden death in immediate family (members before the age 30) - 0.5 points

Torsades de pointes is a medical condition, the name of which means in French twisting of the points. The name is derived from a manoeuvre in ballet, similarly named. ... T-wave alternans (TWA) is a non-invasive test of the heart that is used to identify patients who are at increased risk of sudden cardiac death. ...

Treatment options

There are two treatment options in individuals with LQTS: arrhythmia prevention, and arrhythmia termination.

Arrhythmia prevention

Arrhythmia suppression involves the use of medications or surgical procedures that attack the underlying cause of the arrhythmias associated with LQTS. Since the cause of arrhythmias in LQTS is after depolarizations, and these after depolarizations are increased in states of adrenergic stimulation, steps can be taken to blunt adrenergic stimulation in these individuals. These include:

• Administration of beta receptor blocking agents which decreases the risk of stress induced arrhythmias. Beta blockers are the first choice in treating Long QT syndrome.

In 2004 it has been shown that genotype and QT interval duration are independent predictors of recurrence of life-threatening events during beta-blockers therapy. Specifically the presence of QTc >500ms and LQT2 and LQT3 genotype are associated with the highest incidence of recurrence. In these patients primary prevention with ICD (Implantable Cardioverster Defibrilator) implantaion can be considered.^[3] Beta blockers or beta-adrenergic blocking agents are a class of drugs used to treat a variety of cardiovascular conditions and some other diseases. ...

• Potassium supplementation. If the potassium content in the blood rises, the action potential shortens and due to this reason it is believed that increasing potassium concentration could minimize the occurrence of arrhythmias. It should work best in LQT2 since the HERG channel is especially sensible to potassium concentration, but the use is experimental and not evidence based.
• Mexiletine. A sodium channel blocker. In LQT3 the problem is that the sodium channel does not close properly. Mexiletine closes these channels and is believed to be usable when other therapies fail. It should be especially effective in LQT3 but there is no evidence based documentation.
• Amputation of the cervical sympathetic chain (left stellectomy). This may be used as an add-on therapy to beta blockers but modern therapy mostly favors ICD implantation if beta blocker therapy fails.

Mexiletine (INN, sold under the trade name Mexitil®) belongs to the Class IB anti-arrhythmic group of medicines. ... The sympathetic trunk (sympathetic chain, gangliated cord) is a bundle of nerve fibers that runs from the base of the skull to the coccyx. ... The stellate ganglion is a ganglion formed by the fusion of inferior cervical ganglion and the first paravertebral ganglion. ...

Arrhythmia termination

Arrhythmia termination involves stopping a life-threatening arrhythmia once it has already occurred. The only effective form of arrhythmia termination in individuals with LQTS is placement of an implantable cardioverter-defibrillator (ICD). ICD are commonly used in patients with syncopes despite beta blocker therapy, and in patients who have experienced a cardiac arrest. An implantable cardioverter-defibrillator (ICD) is a device that is implanted under the skin of patients that are at risk of sudden death due to ventricular fibrillation. ...

With better knowledge of the genetics underlying the long QT syndrome, more precise treatments will be readily available.^[4]

Risk stratification

The risk for untreated LQTS patients having events (syncopes or cardiac arrest) can be predicted from their genotype (LQT1-8), gender and corrected QT interval.^[5]

• High risk (>50%)

QTc>500 msec LQT1 & LQT2 & LQT3(males)

• Intermediate risk (30-50%)

QTc>500 msec LQT3(females)

QTc<500 msec LQT2(females)& LQT3

• Low risk (<30%)

QTc<500 msec LQT1 & LQT2 (males)

References

1. ^ Tristani-Firouzi M, Jensen JL, Donaldson MR, Sansone V, Meola G, Hahn A, Bendahhou S, Kwiecinski H, Fidzianska A, Plaster N, Fu YH, Ptacek LJ, Tawil R. Functional and clinical characterization of KCNJ2 mutations associated with LQT7 (Andersen syndrome). Journal of Clinical Investigation. 2002 Aug;110(3):381-8. PMID 12163457.
2. ^ Schwartz PJ, Moss AJ, Vincent GM, Crampton RS. Diagnostic criteria for the long QT syndrome. An update. Circulation. 1993 Aug;88(2):782-4. PMID 8339437.
3. ^ Priori SG, Napolitano C, Schwartz PJ, Grillo M, Bloise R, Ronchetti E, Moncalvo C, Tulipani C, Veia A, Bottelli G, Nastoli J. Association of long QT syndrome loci and cardiac events among patients treated with beta-blockers. JAMA. 2004 Sep 15;292(11):1341-4. PMID: 15367556
4. ^ Compton SJ, Lux RL, Ramsey MR, Strelich KR, Sanguinetti MC, Green LS, Keating MT, Mason JW. Genetically defined therapy of inherited long-QT syndrome. Correction of abnormal repolarization by potassium. Circulation. 1996 Sep 1;94(5):1018-22. PMID 8790040
5. ^ Risk Stratification in the Long-QT Syndrome: N Engl J Med 2003; 349:908-909, Aug 28, 2003. PMID 12944579.

See also

• Cardiac action potential
• Short QT syndrome

The cardiac action potential is the electrical activity of the individual cells of the electrical conduction system of the heart. ... Short QT syndrome is a genetic disease of the electrical system of the heart. ...

External links

• C.A.R.E. Foundation - Cardiac Arrhythmia Research and Education Foundation, Inc.
• Arizona CERT - QT Drug Lists
• The Long QT Syndrome Support Center - LQTS Info for Patients and Physicians
• Drugs that Prolong the Qt Interval and/or Induce Torsades de Pointes Ventricular Arrhythmia
• Sudden Arrhythmia Death Syndromes (SADS) Foundation
• QTsyndrome.ch. Here LQTS patients can ask questions and get answers
• Mutation database of inherited arrhythmias including Long QT syndrome