BACKGROUND In patients with Brugada syndrome (BS), ventricular fibrillation (VF) occurs mainly during sleep; therefore, not only vagal activity but also bradycardia dependent changes in ECG may relate to the nighttime occurrence of VF. The present study aimed to examine the difference in bradycardia-dependent changes in the ECG of symptomatic and asymptomatic BS patients. METHODS AND RESULTS ...

A single 400 mg dose of moxifloxacin has been the standard positive control for thorough QT (TQT) studies. However, it is not clearly known whether a 400 mg dose is also applicable to TQT studies in Asian subjects, including Koreans. Thus, we aimed to develop a pharmacokinetic (PK)-pharmacodynamic (PD) model for moxifloxacin, to evaluate the time course of its effect on QT intervals in Koreans....

Autonomic activity affects beat-to-beat variability of heart rate and QT interval. The aim of this study was to explore whether entropy measures are suitable to detect changes in neural outflow to the heart elicited by two different stress paradigms. We recorded short-term ECG in 11 normal subjects during an experimental protocol that involved head-up tilt and mental arithmetic stress and compu...

AIM Pediatric surgeons frequently encounter children presenting with voiding dysfunction symptoms, including urgency, frequency, and incontinence. Antimuscarinic agents Oxybutynin) are the main drugs used to treat patients with overactive bladder (OAB) syndrome, defined as urgency, with or without urgency incontinence, usually with increased daytime frequency and nocturia. Increased QT dispersi...

While the QT/QTc interval is currently the best available clinical surrogate for the development of drug-induced torsades de pointes, it is overall an imperfect biomarker. In addition to low specificity for predicting arrhythmias, other issues relevant to using QT as a biomarker include (1) an apparent dissociation, for some drugs (for example, amiodarone, sodium pentobarbital, ranolazine) betw...

Drug-induced torsades de pointes (TdP), a life-threatening arrhythmia associated with prolongation of the QT interval, has been a significant reason for withdrawal of several medicines from the market. Prolongation of the QT interval is considered as the best biomarker for predicting the torsadogenic risk of a new chemical entity. Because of the difficulty assessing the risk for TdP during drug...

Long QT syndrome type 3 (LQT3) is caused by mutations in the SCN5A-encoded Nav1.5 channel. LQT3 patients exhibit time of day-associated abnormal increases in their heart rate-corrected QT (QTc) intervals and risk for life-threatening episodes. This study determines the effects of uncoupling environmental time cues that entrain circadian rhythms (time of light and time of feeding) on heart rate ...

A possible function for the alternative (nonphosphorylating) pathway is to stabilize the reduction state of the ubiquinone pool (Qr/Qt), thereby avoiding an increase in free radical production. If the Qr/Qt were stabilized by the alternative pathway, then Qr/Qt should be less stable when the alternative pathway is blocked. Qr/Qt increased when we exposed roots of Poa annua (L.) to increasing co...

BACKGROUND Bile acids can induce arrhythmia by altering cardiomyocyte contractility or electrical conduction. The aim of this study was to investigate, by means of QT dispersion parameter detected by simple standard electrocardiogram (ECG), ventricular repolarization changes in pregnant women with and without intrahepatic cholestasis of pregnancy (ICP). METHODS In this case-control study incl...