[Effects of amiodarone on ventricular refractory period caused by subthreshold electric stimulation]

Effects of amiodarone (Ami) 25 mg.kg-1 iv on ventricular refractory period caused by subthreshold single or train stimulations were studied in rabbits. Before Ami i.v., the refractory period was prolonged by S1-St (P < 0.05, P < 0.01) and by Ss (St) which was intercalated to S1-S2 interval [S1-Ss (St)-S2 methods]. After Ami iv, the refractory period was shortened by S1-St (50 ms, 330 Hz, 6 V) (P < 0.01) and minimal inhibitory voltage of Ss was higher than that of pre-medication in different Ss-S2 intervals (20, 25 ms). These results suggested Ami may change the mode of terminating tachycardia by electric stimulation.