BACKGROUND Early repolarization is a common electrocardiographic finding that is generally considered to be benign. Its potential to cause cardiac arrhythmias has been hypothesized from experimental studies, but it is not known whether there is a clinical association with sudden cardiac arrest. METHODS We reviewed data from 206 case subjects at 22 centers who were resuscitated after cardiac a...

Unlike the brief action potentials (APs) in skeletal myo­ cytes or neurons, the human cardiac AP takes 100s of milliseconds to repolarize the cell. This slow repolar­ ization is essential for proper excitation–contraction coupling in cardiac muscle, and precise control of AP duration contributes to electrical stability. Under vari­ ous pathological conditions, often when the AP dura­ tion is pr...

BACKGROUND Although T-wave alternans has been closely associated with vulnerability to ventricular arrhythmias, the cellular processes underlying T-wave alternans and their role, if any, in the mechanism of reentry remain unclear. METHODS AND RESULTS -T-wave alternans on the surface ECG was elicited in 8 Langendorff-perfused guinea pig hearts during fixed-rate pacing while action potentials w...

Enhanced temporal and spatial variability in cardiac repolarization has been related to increased arrhythmic risk both clinically and experimentally. Causes and modulators of variability in repolarization and their implications in arrhythmogenesis are however not well understood. At the ionic level, the slow component of the delayed rectifier potassium current (I(Ks)) is an important determinan...

Abnormal ventricular wall motion is a strong clinical predictor of sudden, arrhythmic, cardiac death. Dispersion in repolarization is a prerequisite for the initiation of re-entrant arrhythmia. We hypothesize that regionally decreased wall motion is associated with heterogeneity of repolarization. We measured local activation times, activation-recovery intervals (ARIs, surrogate for action pote...

Late sodium current I(NaL) is an inward current participating in maintaining the plateau of the action potential. So far its role in the repolarization of canine hearts is not well known. In this paper, by taking advantage of a computer simulation method, we developed a one-dimensional transmural tissue to study the impacts of I(NaL) on rate-dependent repolarization and its ionic basis in the c...

When current clamped, skate electroreceptor epithelium produces large action potentials in response to stimuli that depolarize the lumenal faces of the receptor cells. With increasing stimulus strength these action potentials become prolonged. When the peak voltage exceeds about 140 mV the repolarizing phase is blocked until the end of the stimulus. Perfusion experiments show that the rising ph...

OBJECTIVE Gender differences in mouse cardiac repolarization have been reported to be due to the stimulatory action of androgens on the ultrarapid delayed rectifier K(+) current (I(Kur)) and its underlying Kv1.5 channel. To confirm the regulation of ventricular repolarization by androgens, the present study compared two strains of mice (CD-1 and C57BL/6) that present different androgen levels. ...