Electrical Conversion of Ventricular Tachycardia

Abstract

Termination of ventricular tachycardia using an external countershock was electively attempted in 21 episodes of ventricular tachycardia occurring in 12 patients. In all cases, myocardial depressant drugs had been tried unsuccessfully prior to attempted electrical conversion. The tachyardia was successfully converted in 20 of the 21 episodes. In six cases, an alternating-current (ac) discharge was used, with successful conversion five times. In 15 cases, a synchronized direct-current (dc) discharge was employed with 14 successful conversions. The only failure in both series occurred in the same patient, who could not be successfully converted with either ac or dc. Ventricular fibrillation was precipitated by the shock once in each group of patients, and was controlled by the application of further countershock. The use of an externally applied shock, either ac or dc, proved to be a safe and effective method of treating ventricular tachycardia when the use of conventional drugs was either unsuccessful or deemed hazardous.