Nonuniform recovery of excitability in the left ventricle

Abstract

The purpose of this study was to determine left ventricular activation, dispersion of refractoriness, and total recovery time in patients with coronary artery disease and ventricular tachycardia and in patients with the long QT syndrome and to compare these patients with a group of normal patients. Left ventricular endocardial catheter mapping and left ventricular refractory period determination were performed in 18 patients. Group 1 consisted of seven patients with no heart disease and no arrhythmia; group 2 consisted of six patients with previous infarction and sustained ventricular tachycardia; and group 3 consisted of five patients with prolonged QT interval and previous cardiac arrest. Total left ventricular endocardial activation was significantly longer in group 2 (75 ± 23 msec, mean ± SD) compared with group 1 (34 ± 9 msec, p < 0.01) and group 3 (42 ± 5 msec, p < 0.05). Dispersion of refractoriness was significantly greater in group 3 (87 ± 27 msec) than in group 1 (40 ± 14 msec, p < 0.01) and group 2 (53 ± 14 msec, p < 0.05). Dispersion of total recovery time was significantly greater in group 2 (90 ± 30 msec) than in group 1 (52 ± 14 msec, p < 0.05) as well as group 3 (114 ± 43 msec) compared with group 1 (p < 0.01). We conclude that 1) compared with a control group, patients with long QT syndrome have greater dispersion of total left ventricular recovery time that is predominantly due to a wide dispersion of local refractory periods; 2) patients with previous infarction and ventricular tachycardia have a greater dispersion of total recovery times than the control group; however, this is due to a wide dispersion of activation times rather than refractoriness; and 3) potentially arrhythmogenic nonuniform recovery of excitability in the left ventricle may be due to dispersion of refractoriness or activation times, depending on the pathophysiological substrate.