The potential distribution at the atrial surface during depolarization and repolarization was studied in intact dogs. A preparation was developed by implanting 30 to 40 miniature electrodes permanently on each atrium to record unipolar electrograms in the intact animal. Heart block was created to dissociate atrial and ventricular activity. The electrograms were recorded on magnetic tape and atr...

INTRODUCTION Over the last 40 years omega-3 polyunsaturated fatty acids (PUFAs) have been shown to be anti-arrhythmic or pro-arrhythmic depending on the method and duration of administration and model studied. We previously reported that omega-3 PUFAs do not confer anti-arrhythmic properties and are pro-arrhythmic in canine model of sudden cardiac death (SCD). Here, we evaluated the effects of ...

Background. It is currently believed that defibrillation shocks act primarily by stimulating excitable myocardium to abolish wave fronts. Recent studies have shown that shocks applied during pacing not only stimulate excitable myocardium but also prolong the depolarization and refractoriness of myocardium already in a depolarized state. This study investigates the effects of shocks on fibrillat...

BACKGROUND Population based studies showed an association of early repolarization in the electrocardiogram (ECG) and a higher rate of sudden cardiac death presumably due to ventricular fibrillation. The triggers for ventricular fibrillation in patients with early repolarization are not fully understood. CASE PRESENTATION We describe the case of a young patient with a survived ventricular fibr...

RATIONALE Hypertension associates with sudden cardiac death, its relationship with ventricular arrhythmias being demonstrated by multiple studies, an increased dispersion of repolarization being an important arrhythmogenesis mechanism. Only a small percentage of hypertensive patients presents increased blood pressure values exclusively as risk factor, most of them presenting additional risk fac...

BACKGROUND Abnormal ventricular repolarization is a predictor of cardiovascular mortality. In this study, we tested the hypothesis that glycemic control reverses abnormal ventricular repolarization in patients with type 2 diabetes. METHODS We analyzed longitudinal changes in repolarization indices of electrocardiograms in retrospectively enrolled 44 patients with type 2 diabetes and 44 age-ma...

Indapamide is a diuretic agent with direct electrophysiological effects on ionic currents involved in cardiac repolarization. In particular, indapamide blocks the slow component of delayed rectifier potassium current. In contrast, most class III antiarrhythmic agents, such as dl-sotalol, block the rapid component of delayed rectifier potassium current. Computer simulations have suggested potent...

HERG K(+) channel, the genetic counterpart of rapid delayed rectifier K(+) current in cardiac cells, is responsible for many cases of inherited and drug-induced long QT syndromes. HERG has unusual biophysical properties distinct from those of other K(+) channels. While the conventional pulse protocols in patch-clamp studies have helped us elucidate these properties, their limitations in assessi...

Unipolar electrograms from ventricular epicardium in dogs were analyzed for the timing of local excitation and repolarization with computer assistance. The most rapid decrease in voltage in the QRS (dV/dt min) was used to determine local excitation time, and the maximum rate of voltage increase (dV/dt max) near the peak of the T wave was used to time local repolarization. The difference between...

Spatial dispersion of repolarization in the form of transmural, trans-septal and apico-basal dispersion of repolarization creates voltage gradients that inscribe the J wave and T wave of the ECG. Amplification of this spatial dispersion of repolarization (SDR) underlies the development of life-threatening ventricular arrhythmias associated with inherited or acquired ion channelopathies giving r...