In both the asymptomatic and symptomatic groups, the QTc interval can be normal on initial presentation. However, symptomatic patients are more likely to have an abnormal QTc interval than asymptomatic patients. [geneticheartdisease.org]

The dramatic shifts in estrogen/progesterone levels in the postpartum state have resulted in the initial cardiac presentation of LQTS2 in several patients. [hindawi.com]

This is likely an underestimate as sudden death with a normal autopsy may be the first and only presentation. There are 12 genes responsible for 3 main types of c-LQTS. The presentation is one of aborted sudden death or brief arrhythmia. [epmonthly.com]

This was initially shown with the H558R polymorphism of SCN5A, present in up to 30% of the population. [revespcardiol.org]

Because of the potential severity of symptoms and outcomes, and the potentially treatable nature of the disease, it is important for the pediatrician to be aware of long QT and it's workup. [pedclerk.bsd.uchicago.edu]

• Prolongation of Corrected QT Interval

  However, an electrocardiogram (ECG) showed a prolonged QTC (corrected QT interval) of 480 ms. Her mother was healthy and had a QTC on ECG of 460 ms, but the patient’s maternal aunt had died suddenly at five months postpartum. [eplabdigest.com]

  Diagnosis General The diagnosis is by measurement of the heart rate corrected QT interval on the ECG, which can be calculated with the QTc calculator. Sometimes the QT interval can be difficult to assess. [textbookofcardiology.org]

• Late Onset T-Wave

  Sub-type Frequency Gene Mutation Effect ECG finding LQTS 1 30-35% KVLQT1 ¯ K + Efflux Broad, late-inset, T wave LQTS 2 25-30% HERG ¯ K + Efflux Widely-split, low-amplitude, T wave LQTS 3 5-10% SCN5A Prolonged Na + influx Biphasic or peaked, late-onset [geneticheartdisease.org]

  ' broad based T wave LQT2 small late T wave LQT3 prolonged QT interval with 'late onset' T wave with a normal configuration In congenital LQTS the ventricular repolarisation is prolonged. [en.ecgpedia.org]

  T wave Small late T wave Late onset T wave with normal configuration Arrhythmogenic triggers Exercise, especially swimming Adrenergic triggers, especially nightly noise Rest Number of mutation carriers with events at age 40% 20% 10% Number of mutation [textbookofcardiology.org]

• Prominent U Wave

  The electrocardiogram of these patients has a prominent U wave and a normal or modestly prolonged QT interval. Although LQT7 is currently included among the sub-types of congenital long-QT syndrome, this inclusion is controversial. [geneticheartdisease.org]

Treatment: Treatment of LQTS is guided by the individual’s risk of sudden cardiac death. Patients who have survived sudden cardiac arrest are considered to have the highest risk of a recurrent event. [geneticheartdisease.org]

Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional. [betterhealth.vic.gov.au]

Specific types of treatment Your doctor will recommend the best treatment for you based on: What type of LQTS you have How likely it is that you will faint or that your heart will suddenly stop beating What treatment you feel most comfortable taking People [daviddarling.info]

What is the treatment and who should be treated? All symptomatic patients should receive treatment. All children and young adults should be treated even if they do not have symptoms. [sads.org]

Treating Long QT Syndrome The goal of treatment for LQTS is to prevent your child’s heart from having dangerous irregular and fast heartbeats ( arrhythmias ). Treatment does not cure LQTS. LQTS can be treated with medicines, like beta-blockers. [seattlechildrens.org]

This study shows that this is not the case and that beta-blockers have either a neutral or positive effect on prognosis, depending on sex. [acc.org]

[…] 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 Prognosis [checkorphan.org]

Epinephrine challenge or exercise testing : specific to LQT1 mutation Genetic testing : negative test doesn't R/O diagnosis, but positive test can provide prognosis and guide therapeutics, also can help R/O diagnosis in other family members Treatment [pedclerk.bsd.uchicago.edu]

Treatment and outlook (prognosis) Risk can be effectively managed in LQTS, and in general, patients who follow treatment recommendations can expect to do very well. [cidg.org.nz]

A mutation in GPD1L has been shown to result in a partial reduction of I Na Knowledge thus far gained through genetic analysis suggests that identification of specific mutations may not be very helpful in formulating a diagnosis or providing a prognosis [af-ablation.org]

Enormous progress has been made in the identification of genes involved in the etiology of inherited cardiovascular diseases. [centogene.com]

Despite being found in many genes mutations, the etiology of the syndrome remains unknown in 30 to 40% of cases. [ivami.com]

It presents when the QT interval is prolonged, regardless of the etiology. It is a polymorphic ventricular tachycardia due to reentry, characterized electrocardiographically by continuous twisting of the QRS axis around an imaginary line. [revespcardiol.org]

Etiology of sudden death in an apparently normal heart (7-10) Congenital LQTS inside the genetic anomalies of the ion channels So far, there is a spectrum of inherited arrhythmia syndromes arising from genetic defects in structures involved in the genesis [romanianjournalcardiology.ro]

In our view, rapid comprehensive genetic testing (WGS or whole-exome sequencing) should be used as a primary diagnostic inquiry in infants with life-threatening illness of unclear or suspected genetic etiology. [pnas.org]

This is done with Bazett’s Formula: Epidemiology: In the United States, the incidence of congenital LQTS is estimated to be one in 7,000-10,000. There is a female preponderance, ranging from 1.6-2.0:1. [geneticheartdisease.org]

Sudden infant death syndrome and long QT syndrome: an epidemiological and genetic study. Int J Legal Med. 2006; 120 :129–37. [ PubMed : 16012827 ] Westenskow P, Splawski I, Timothy KW, Keating MT, Sanguinetti MC. [ncbi.nlm.nih.gov]

Investigative teams have published comprehensive clinical-epidemiologic reviews of both long QT syndrome as a family and several of the other channelopathies under Human Genome Epidemiology (HuGE) reviews (e.g., long QT syndrome 21 ) and GeneReviews [currents.plos.org]

[…] who are untreated, the risk of death within 15 years is around 50%. [6] With careful treatment this decreases to less than 1% over 20 years. [3] Those who exhibit symptoms before the age of 18 are more likely to experience a cardiac arrest. [18] [36] Epidemiology [en.wikipedia.org]

With the advent of reliable genetic testing and a better understanding of the pathophysiology of the various mutations, “personalized” pharmacotherapy is currently being developed. [geneticheartdisease.org]

Pathophysiology Congenital or acquired Ten genes linked to congenital LQTS, but three genes that encode a cardiac ion channel responsible for ventricular repolarization account for majority of cases (LQT1, LQT2, LQT3) LQT1 : most common, triggered by [pedclerk.bsd.uchicago.edu]

Amplification of epicardial and TDR secondary to the presence of genetic defects, pathophysiologic factors, and pharmacologic influences, leads to accentuation of the J wave and eventually to loss of the AP dome, giving rise to extrasystolic activity [af-ablation.org]

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test Long QT syndrome (LQTS) is a genetic cardiac disorder characterized by QT prolongation and T-wave abnormalities on electrocardiogram [mayomedicallaboratories.com]

Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Dyslipidemia, Prevention, Implantable Devices, EP Basic Science, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular [acc.org]

Appropriate therapy will prevent unnecessary deaths in infants, children, and young adults. [omicsonline.org]

Since LCSD is an invasive procedure, it should be used as a secondary prevention modality. [thecardiologyadvisor.com]

In these patients primary prevention with ICD (Implantable Cardioverster Defibrilator) implantation can be considered.[3] Potassium supplementation. [checkorphan.org]

Additionally calcium channel blockers and ranolazine, a novel multichannel inhibitor have been used to prevent ventricular tachyarrhythmia [ 1, 2, 7, 9, 11 ]. [link.springer.com]