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The Purkinje fibers are located in the ventricular walls of the heart, just beneath the endocardium and conduct excitation from the right and left bundle branches to the ventricular myocardium. Recently, anatomists succeeded in photographing the Purkinje fibers of a sheep, which clearly showed the mesh structure of the Purkinje fibers. In this study, we(More)
BACKGROUND Drugs with I(Kr)-blocking action cause secondary long-QT syndrome. Several cases have been associated with mutations of genes coding cardiac ion channels, but their frequency among patients affected by drug-induced long-QT syndrome (dLQTS) and the resultant molecular effects remain unknown. METHODS AND RESULTS Genetic testing was carried out(More)
BACKGROUND After near-defibrillation threshold (DFT) shocks from an implantable cardioverter-defibrillator (ICD), the first postshock activation that leads to defibrillation failure arises focally after an isoelectric window (IW). The mechanisms underlying the IW remain incompletely understood. OBJECTIVE The goal of this study was to provide mechanistic(More)
BACKGROUND Short QT syndrome (SQTS) is a rare inheritable arrhythmia, associated with atrial and ventricular fibrillations, caused by mutations in six cardiac ion channel genes with high penetrance. However, genotype-specific clinical differences between SQTS patients remain to be elucidated. METHODS AND RESULTS We screened five unrelated Japanese SQTS(More)
In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33 degrees C) has been shown to improve defibrillation success compared with normothermia (NR, 37 degrees C) and severe hypothermia (SH, 30 degrees C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around(More)
Bepridil is effective for conversion of atrial fibrillation to sinus rhythm and in the treatment of drug-refractory ventricular tachyarrhythmias. We investigated the effects of bepridil on electrophysiological properties and spiral-wave (SW) reentry in a 2-dimensional ventricular muscle layer of isolated rabbit hearts by optical mapping. Ventricular(More)
RATIONALE Electrogram-based catheter ablation, targeting complex fractionated atrial electrograms (CFAEs), is empirically known to be effective in halting persistent/permanent atrial fibrillation (AF). However, the mechanisms underlying CFAEs and electrogram-based ablation remain unclear. OBJECTIVE Because atrial fibrosis is associated with(More)
BACKGROUND In the LQT2 form of long QT syndrome (LQTS), mutation sites are reported to correlate with clinical phenotypes in Caucasians, but the relationship in Asian patients remains unknown. The present study was designed to determine whether the location of KCNH2 mutations would influence the arrhythmic risk in LQT2 patients. METHODS AND RESULTS In 118(More)
QT prolongation, a risk factor for arrhythmias, can result from genetic variants in one (or more) of the genes governing cardiac repolarization as well as intake of drugs known to affect a cardiac K(+) channel encoded by human ether-a-go-go-related gene (HERG). In this paper, we will report a case of drug-induced long QT syndrome associated with an(More)
BACKGROUND The KCNQ1 single nucleotide polymorphism (SNP), G643S, is known to be associated with secondary long QT syndrome (LQTS) and to cause a mild reduction in KCNQ1 current. However, the precise incidence and its association with QT intervals remain unknown in the greater cohort of the population in Japan. METHODS AND RESULTS The genotype was(More)