[Intravenously disopyramide phosphate administration for treatment of arrhythmias]

Disopyramide phosphate (DF) was administered intravenously to 50 patients during 55 episodes of arrhythmias. The mean dosage employed was 2 +/- 1.4 mg/kg over a period of 3 minutes to 60 minutes (mean 16 +/- 6'), followed by an infusion at a dose of 0.4 mg/kg/hr in 9 cases. Atrial premature beats were suppressed in 3 of 4 treated cases (75%). Conversion to sinus rhythm was achieved in 4 of 5 (80%) cases of paroxysmal supraventricular tachycardia, unresponsive to vagal maneuvers in 7 of 10 cases (70%) of atrial flutter of recent onset (less than 48 hours) and in 13 of 17 (76%) cases of atrial fibrillation (less than one week in duration). In 9 of 11 cases (81%) with frequent, multiform, repetitive ventricular premature beats and in 7 of 8 cases (87%) of ventricular tachycardia, DF completely suppressed the arrhythmia. The drug increased sinus rate, PR and QRS intervals, but the difference was not statistically significant: the QRS of patients with complete bundle branch block and the QTc interval were significantly prolonged. Severe hypotension was observed in 10 patients after DF i.v., in 5 of whom withdrawal of therapy was deemed to be necessary. Nine other patients had anticholinergic side effects. Our study shows that DF administered i.v. can be used successfully in 75% of supraventricular arrhythmias and in 82% of ventricular arrhythmias.