EFFECTS OF PRENYLAMINE AND AQ-A 39 ON REENTRANT VENTRICULAR ARRHYTHMIAS INDUCED DURING THE LATE MYOCARDIAL-INFARCTION PERIOD IN CONSCIOUS DOGS

The effects of prenylamine (PNL) and AQ-A 39 on sustained ventricular tachycardia (SVT) were studied by programmed stimulation in conscious dogs 4-10 days after ligation of the left anterior descending (LAD) co ronary artery. In 8 of 16 dogs developing SVT in the control, PNL (3 m g/kg intravenously, i.v.) suppressed inducibility of SVT and slowed th e rate of tachycardia in 6 other animals. In a separate group of 10 do gs with inducible SVT, AQ-A 39 (4 mg/kg i.v.) abolished elicitation of tachycardia in 3 dogs and decreased its rate in 6 other dogs. Neither drug affected normal conduction significantly, but PNL impaired slow conduction in the infarct zone, as indicated by prolongation of late p otentials. Both agents increased the effective refractory period (ERP) of infarcted and normal ventricular myocardium and prolonged the corr ected QT interval. PNL and AQ-A 39 exert notable efficacy in preventin g infarcted heart from severe ventricular arrhythmias. Prolongation of ventricular refractoriness and repolarization, as well as decreased s low conduction in ischemically damaged myocardium. are major mechanism s accounting for the effectiveness of these drugs against ventricular arrhythmias.