Effect of bradycardia on dispersion of ventricular refractoriness

Abstract The effect of bradycardia on dispersion of ventricular refractoriness was evaluated. Refractory periods were measured at 3 right ventricular sites in 16 patients with severe bradycardia (average heart rate 39 ± 5 beats/min) and were compared with those measured in 11 control subjects, (average heart rate 72 ± 12 beats/min). Patients with bradycardia had significantly longer effective (377 ± 36 ms) and functional (421 ± 39 ms) refractory periods (ERP and FRP) than control subjects (ERP 296 ± 25 ms, FRP 346 ± 18 ms) (p 2 and S 3 ) failed to induce ventricular tachycardia in any patient during bradycardia. Bradycardia alone does not appear to be a factor in the induction of ventricular tachyarrhythmias.