EFFECT OF FLECAINIDE ACETATE ON REPERFUSION-INDUCED AND BARIUM-INDUCED VENTRICULAR TACHYARRHYTHMIAS IN THE ISOLATED PERFUSED RAT-HEART

Flecainide acetate is a new antiarrhythmic drug which suppresses different kinds of experimental arrhythmias. We studied the efficacy of flecainide acetate on reperfusion- and barium-induced ventricular tachyarrhythmias in the isolated perfused rat heart by monitoring heart rate, coronary flow rate, left ventricular systolic pressure, dp/dt(max), and the voltage of the epicardial electrogram. Seventy-five male rats were randomized into 5 groups. In group I, after a 15 min period of stabilization, hearts were perfused by ischemic perfusion and then reperfused. In group II, flecainide acetate (10(-6) M) was given after stabilization and before ischaemic perfusion. In group III, barium chloride (10(-3) M) was given after stabilization. In group IV, flecainide acetate was given after stabilization and before barium chloride administration. In group V, acetylcholine chloride (10(-6) M) was given after stabilization and before barium chloride administration. In group I, we noted during ischemia a reduction in heart rate, coronary flow rate, left ventricular systolic pressure and dp/dt(max) and an increase in the voltage of the epicardial electrogram. In group II, after administration of flecainide acetate, we observed a reduction in heart rate, left ventricular systolic pressure and dp/dt(max); during the ischaemic period there was no difference in these parameters with respect to group I. Reperfusion induced ventricular arrhythmias in 12 out of 15 hearts in group I and in only 3 out of 15 in group II (p < 0.005). Barium induced ventricular arrhythmias in the 15 hearts studied in group III as well as in group IV. On the contrary, acetylcholine chloride in group V prevented the occurrence of barium-induced ventricular arrhythmias (p < 0.005 vs group III and IV). Thus, flecainide acetate is able to reduce reperfusion-induced ventricular arrhythmias but is unable to reduce barium-induced ventricular arrhythmias, presumably because of a different mechanism of these two types of arrhythmias.