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Long QT Syndrome 10

Romano-Ward Syndrome


Presentation

  • 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]
  • D85N is a polymorphism in the KCNE1 gene, present in 0.7–1% of the general population ( 41 ).[frontiersin.org]
  • Given the characteristic features of LQTS, the typical cases present no diagnostic difficulties for physicians aware of the disease.[ojrd.biomedcentral.com]
  • Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the presentation of the disease.[rarediseases.org]
Severe Clinical Course
  • Even though the clinical diagnosis of J-LN is rather straightforward, it is important to genotype all these patients because it has been shown by Schwartz et al. [ 3 ] that the smaller group with KCNE1 mutations has a markedly less severe clinical course[ojrd.biomedcentral.com]
Exertional Syncope
  • Ventricular fibrillation can lead to loss of consciousness during exertion (exertional syncope) and sudden death. All cases were typified by marked QT prolongation of the surface ECG.[rarediseases.org]
Small Teeth
  • LQTS8 Also known as Timothy syndrome (TS), patients show severe QT prolongation on their ECGs, which is combined with syndactyly, baldness at birth, and small teeth in 100% of cases and less penetrant cardiac structural malformations, mental retardation[frontiersin.org]

Workup

  • 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]
Dyslipidemia
  • 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]
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]
Bifascicular Block
  • block I45.3 Trifascicular block I45.4 Nonspecific intraventricular block I45.5 Other specified heart block I45.6 Pre-excitation syndrome I45.8 Other specified conduction disorders I45.81 Long QT syndrome I45.89 Other specified conduction disorders I45.9[icd10data.com]
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, T wave LQTS[geneticheartdisease.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, T wave LQTS[geneticheartdisease.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]
Prominent A-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: 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]
  • Standard Therapies Treatment is aimed at preventing symptoms such as syncope or cardiac arrest.[rarediseases.org]
  • The identification of carriers of causative mutations allows early, possibly presymptomatic treatment. In this way, the risk of cardiac events in LQTS type 1 can be reduced by 62-95% and in LQTS type 2 by 74%.[medical-genetics.de]
  • Treatment to restore a normal heart rhythm may include medicines, an implantable cardioverter-defibrillator (ICD) or pacemaker, or sometimes surgery.[icdlist.com]

Prognosis

  • 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]

Etiology

  • 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]
  • Etiology Following the identification, in 1995 and 1996, of the first three LQTS genes associated with the most frequently encountered LQTS variants called respectively LQT1, LQT2, and LQT3, there has been a flourishing of identifications of genes proven[ojrd.biomedcentral.com]

Epidemiology

  • 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]
  • Epidemiology Initially considered as a very rare condition, already in 1975 [ 1 ] we suggested that LQTS "could be more unrecognized than rare".[ojrd.biomedcentral.com]
Sex distribution
Age distribution

Pathophysiology

  • 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]
  • In this review, we will describe exclusively on LQTS linked arrhythmias, its pathophysiology and presently available clinical management.[frontiersin.org]

Prevention

  • 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]
  • View Article PubMed Google Scholar Schwartz PJ, Motolese M, Pollavini G, Lotto A, Ruberti U, Trazzi R, Bartorelli C, Zanchetti A, the Italian Sudden Death Prevention Group: Prevention of sudden cardiac death after a first myocardial infarction by pharmacologic[ojrd.biomedcentral.com]
  • Standard Therapies Treatment is aimed at preventing symptoms such as syncope or cardiac arrest.[rarediseases.org]
  • Since LCSD is an invasive procedure, it should be used as a secondary prevention modality.[thecardiologyadvisor.com]

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