Twenty-nine patients with various tachyarrhythmias were treated with intravenous aprindine, a new antiarrhythmic drug. Three patients also exhibited Wolff-Parkinson -White syndrome. Aprindine was significantly effective on ventricular premature beats (7/10) and paroxismal supraventricular tachycardia (5/6), but not effective on ventricular tachy cardia (1/4), atrial fibrillation (0/7), and atrial flutter (0/2) . In all patients with WolffParkfnson-White syndrome, delta waves disappeared with

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... indine injection. Electrophysiological study revealed that aprindine lengthened the conduction time significantly, but no significant prolongation of the effective refractory period was observed. The average half-life of elimination for 2 mg/kg intravenous aprindine was about 17. 5 hrs and was much longer in the patients with liver dysfunction. No severe