Bundle branch re-entry ventricular tachycardia in a patient with myotonic dystrophy.

Bundle branch re-entry (BBR)-ventricular tachycardia (VT) is relatively rare with an incidence of about 6% in sustained monomorphic VT series. However, physicians unexpectedly encounter it in clinical practice. BBR-VT is associated with serious hemodynamic decompensation, and the clinical presentation in approximately 75% of patients with inducible BBR-VT is syncope or cardiac sudden death. Thus, precise mapping of His-Purkinje and bundle branch potentials is necessary for an accurate diagnosis and treatment of re-entrant mechanisms especially for BBR-VT. However, simultaneous recording of both the left-bundle (LB) and right-bundle (RB), as well as His-bundle (HB), potentials is often difficult during tachycardia. Here we report the clear documentation of the activation sequence of the His-Purkinje system during BBR-VT, which could be readily and completely treated by radiofrequency catheter ablation in a myotonic dystrophy patient.

Strong linkage disequilibrium and association of -1131T>C and c.553G>T polymorphisms of the apolipoprotein A5 gene with hypertriglyceridemia in a Japanese population.

BACKGROUND: The apolipoprotein A5 gene (ApoA5) plays an important role in modulating triglyceride metabolism. Polymorphisms of ApoA5, including -1131T>C and c.553G>T (G185C), have been reported to correlate with hypertriglyceridemia (HTG). In the present study the relationships of 5 single nucleotide polymorphisms, including the -1131T>C, c.56C>G, IVS3+476G>A, c.553G>T, and c.1259T>C polymorphisms of ApoA5, with HTG were investigated. METHODS AND RESULTS: The study group comprised 95 Japanese patients with HTG and 119 unrelated normolipidemic subjects. Frequencies of the C allele of -1131T>C (0.511) and the T allele of c.553G>T (0.205) in the hypertriglyceridemic patients were significantly higher than in the normolipidemic subjects (0.315 and 0.105, respectively). The c.56C>G (S19W) polymorphism was not observed, and the other 4 polymorphic sites were in strong linkage disequilibrium. Five of the 8 detected haplotypes with the C allele of -1131T>C correlated with HTG. Promoter activities of ApoA5, including that with the -1131T>C polymorphism, were estimated using a luciferase assay. Analysis of ApoA5 promoters showed that the -1131T>C polymorphism alone had no effect. Comparison of expression of mutant G185C and wild-type ApoA5-green fluorescent protein (GFP) in HepG2 cells showed that ApoA5-GFP was abundant in punctate endosome-like structures, and ApoA5 (G185C)-GFP expression resembled that of the wild type. CONCLUSIONS: The -1131T>C and c.553G>T (G185C) polymorphisms correlated with HTG in this Japanese population, but neither polymorphism directly affected ApoA5 expression.

Genetic analysis of Brugada syndrome in Western Japan: two novel mutations.

BACKGROUND: Brugada syndrome is a form of idiopathic ventricular fibrillation characterized by right bundle-branch block pattern and ST elevation in the right precordial leads of the ECG. The SCN5A gene encodes the alpha-subunit of the human heart sodium channel, which plays a critical role in cardiac excitability, and mutations of SCN5A could underlie Brugada syndrome. METHODS AND RESULTS: To detect mutations of SCN5A, DNA samples from 12 Japanese patients with Brugada syndrome were analyzed using direct sequencing. Two patients had novel mutations, G292S and S835L, but no other mutations of SCN5A were detected in the remaining patients. The first mutation, G292S, was identified adjacent to the pore-lining region between the DIS5 and DIS6 transmembrane segments of SCN5A, and the second mutation, S835L, was in the intracellular loop connecting the DIIS4 to DIIS5. Both mutations were not detected in 100 unrelated control subjects. CONCLUSION: Two novel SCN5A mutations have been found in Japanese patients with Brugada syndrome.