ABSTRACT
Congenital long QT syndrome (LQTS) is the most common inherited arrhythmia, fatal arrhythmias are the main causes of sudden death, and often induced by the premature ventricular contractions (PVCs). Ablation of the triggering PVCs may eliminate the fatal arrhythmias and prevent the sudden death in patients with LQTS. We report a 19-year-old boy diagnosed with type 3 LQTS, frequent fatal arrhythmias induced by PVCs with the identical QRS morphology. Successful ablation of the triggering PVCs was done and a single-chamber implantable cardioverter defibrillator (ICD) was implanted. There was no fatal arrhythmia events recorded by ICD during 29-month follow-up. Catheter ablation was the effective method to eliminate the fatal arrhythmias through ablation of the triggering PVCs in the present LQT3 patient.
Subject(s)
Catheter Ablation/methods , Long QT Syndrome/therapy , Ventricular Premature Complexes/therapy , Adult , Cardiac Conduction System Disease , Death, Sudden, Cardiac/prevention & control , Defibrillators, Implantable , Electrocardiography , Follow-Up Studies , Humans , Long QT Syndrome/complications , Male , Ventricular Premature Complexes/complications , Young AdultABSTRACT
The Long QT Syndrome (LQTS) is a group of genetically heterogeneous disorders that predisposes young individuals to ventricular arrhythmias and sudden death. LQTS is mainly caused by mutations in genes encoding subunits of cardiac ion channels (KCNQ1, KCNH2,SCN5A, KCNE1, and KCNE2). Many other genes involved in LQTS have been described recently(KCNJ2, AKAP9, ANK2, CACNA1C, SCNA4B, SNTA1, and CAV3). We created an online database(http://www.genomed.org/LOVD/introduction.html) that provides information on variants in LQTS-associated genes. As of February 2010, the database contains 1738 unique variants in 12 genes. A total of 950 variants are considered pathogenic, 265 are possible pathogenic, 131 are unknown/unclassified, and 292 have no known pathogenicity. In addition to these mutations collected from published literature, we also submitted information on gene variants, including one possible novel pathogenic mutation in the KCNH2 splice site found in ten Chinese families with documented arrhythmias. The remote user is able to search the data and is encouraged to submit new mutations into the database. The LQTS database will become a powerful tool for both researchers and clinicians.
Subject(s)
Databases, Genetic , Long QT Syndrome/genetics , Mutation , Genetic Predisposition to Disease , Genetic Variation , Humans , Internet , Ion Channels/genetics , Long QT Syndrome/classificationABSTRACT
BACKGROUND: Many studies revealed that variations in cardiac ion channels would cause cardiac arrhythmias or act as genetic risk factors. We hypothesized that specific single nucleotide polymorphisms in cardiac ion channels were associated with cardiac rhythm disturbance in the Chinese population. METHOD: We analyzed 160 nonfamilial cardiac arrhythmia patients and 176 healthy individuals from which 81 individuals were selected for association study, and a total of 19 previously reported SNPs in four cardiac ion channel genes (KCNQ1, KCNH2, SCN5A, KCNE1) were genotyped. RESULTS: The frequency of KCNQ1 1638G>A, as well as the haplotype harboring KCNQ1 1638A, KCNQ1 1685 + 23G and 1732 + 43T (haplotype AGT) was significantly higher in healthy controls than in arrhythmia patients. This finding implicated that this haplotype (AGT) might be a protective factor against arrhythmias. CONCLUSIONS: Our study provided important information to elucidate the effect of SNPs of cardiac ion channel genes on channel function and susceptibility to cardiac arrhythmias in Chinese population.
