Use of alternating current during diagnostic electrophysiologic studies

When conventional programmed electrical stimulation did not yield ventricular arrhythmias suitable for testing implanted automatic defibrillator function and for mapping the location of arrhythmogenic foci, full-wave rectified alternating current (120 Hz) was used for inducing arrhythmias. Application of alternating current resulted in ventricular tachycardias 31 times; in 27 instances, these tachycardias were similar in rate (216 ± 37 beats/min) and morphology to those previously induced in the same patient by programmed electrical stimulation (191 ± 30 beats/min). During endocardial mapping, the origin of the tachycardias induced by both methods was found in the same region. Alternating current produced ventricular fibrillation only four times, twice when it was the patient's spontaneous native arrhythmia and twice after apparently effective endocardial resection. No complications of the technique were observed. The use of alternating current was found to be simple, rapid and safe; it may be especially useful in the operating room during antiarrhythmic surgery because it markedly reduces the cardiopulmonary bypass time required for induction and may also be useful for testing the adequacy of endocardial resection.