Critical evaluation of indications for external electric countershock in the treatment of ventricular tachycardia

Abstract

External electric countershock has been recently employed and recommended for the treatment of ventricular tachycardia and other serious arrhythmias, when drug therapy is ineffective and the patient's condition desperate or intolerable. Two cases of ventricular tachycardia are reported in which the use of external countershock was regarded as indicated. In one case, in which other drugs had failed and procaine amide was regarded as contraindicated because of periods of heart block, external countershock was considered urgently necessary because of a deteriorating clinical state. Nevertheless, the tachycardia disappeared spontaneously after withholding all drugs while the patient was carefully observed. In the second case in which drug therapy was considered ineffective after 5 gm. of procaine amide intravenously had caused a widening of the QRS to 0.18 second without conversion, a subsequent, much more rapid infusion of the same drug in a total dose of 1 gm. restored sinus rhythm. An analysis of the cases reported in the literature in which details are presented indicates that procaine amide had been given too slowly or too briefly to regard the drug as ineffective and the urgent need for electric countershock appears questionable. In view of the drastic nature of external electric countershock in the conscious patient and the need for an anesthetic, the requirement of this procedure many different times in some patients, the occurrence of ventricular fibrillation or standstill after counter-shock with the need for further defibrillation or external stimulation, the prompt recurrence of the ventricular tachycardia in some cases, and because of possible fatalities, the indications for such procedure must be most critically assayed in the light of our experience in the two reported cases.