Electrophysiologic evaluation of antiarrhythmic drugs on supraventricular tachyarrhythmias.

The effects of the intravenous administration of three drugs, i.e., verapamil, disopyramide, and procainamide, on paroxysmal supraventricular tachycardia (PSVT), atrial fibrillation (Af) and atrial flutter (AF) were evaluated electrophysiologically. Efficacy on PSVT was 94.7% (36/38) with verapamil, 61.5% (13/18) with disopyramide and 100% (4/4) with procainamide. Efficacy on Af and AF was 9.1% (1/11) with verapamil and 80.0% (12/15) with disopyramide. PSVT termination mechanisms were as follows: 1) Verapamil: A-H block in 5 cases and H-A block in 5 cases with Type 1 A-V nodal reentrant tachycardia (AVNRT). H-A block in 6 cases with Type 2 and Type 3. A-H block in 17 of 18 cases with A-V reciprocating tachycardia (AVRT). Cycle length alternans were observed in 13 of 34 cases. 2) Disopyramide: H-A block in 2 cases with AVNRT and V-A block in 2 cases with AVRT. 3) Procainamide: V-A block in 4 cases with AVRT. These results suggest that verapamil and disopyramide are most effective on PSVT and Af, respectively.