COMPARATIVE ELECTROPHYSIOLOGICAL EFFECTS OF THE ANTIDEPRESSANTS FLUVOXAMINE AND AMITRIPTYLINE IN THE CANINE HEART AFTER MYOCARDIAL-INFARCTION

We studied the effects of fluvoxamine and amitriptyline on epicardial activation delay of premature excitations, the effective refractory pe riod, and the incidence of ventricular arrhythmias by programmed elect rical ventricular stimulation in the canine heart after myocardial inf arction. Additionally, we investigated whether the inhibition of norep inephrine reuptake by amitriptyline contributes to epicardial activati on delay or arrhythmias by combination with propranolol pretreatment. Amitriptyline, at a dose of 3 mg/kg, significantly prolonged epicardia l activation delay of premature excitations in the infarcted zone in a frequency-dependent manner (n = 10). Amitriptyline also prolonged epi cardial activation delay of premature excitations in the normal zone ( n = 10). The effective refractory period in the infarcted zone was sig nificantly prolonged by amitriptyline at a dose of 3 mg/kg (n = 8). Am itriptyline increased the incidence of ventricular arrhythmias induced by programmed electrical ventricular stimulation (n = 8). Propranolol did not affect the epicardial activation delay caused by amitriptylin e or the incidence of ventricular arrhythmias induced by programmed el ectrical ventricular stimulation (n = 6). Fluvoxamine, on the other ha nd, had no significant effect on epicardial activation delay of premat ure excitations (n = 10) or the effective refractory period(n = 8) in both the infarcted and normal zones. Fluvoxamine did not increase the incidence of ventricular arrhythmias induced by programmed electrical ventricular stimulation (n = 8).