Direct current shock and digitalis. A clinical and experimental study.

The application of direct current (DC) shock is now an established method of treatment of ectopic tachycardias.However, experience has shown that the concomitant use of certain cardiac drugs can lead to undesirable complications and create new problems in the management of the patient.Several studies have already referred to the use of digitalis (Gilbert and Cuddy, 1965; Lown, Kleiger, and Williams, 1965; Kleiger and Lown, 1966; Szekely, Wynne, and Batson, 1966b; Lown, 1967; Castellanos et al., 1967) in association with DC shock therapy.It is the purpose of this paper to evaluate clinical and experimental observations on the effects of the combined use of digitalis and DC shock.Clinical and experimental observations on the concomitant use of various antiarrhythmic drugs and DC shock will be the subject of a separate communication. METHOD, CLINICAL GROUPS, AND EXPERIMENTAL MATERIAL(A) Clinical.Five hundred consecutive episodes of ectopic tachycardia treated by DC shock have been reviewed.Of these, 414 episodes of atrial fibrillation occurring in 289 patients form the basis of the present observations.Of the 289, 218 patients had rheumatic heart disease, 30 coronary heart disease with or without hypertension, 4 congenital heart disease, 9 thyrotoxicosis, 1 had chronic pulmonary heart disease, and there were 27 patients with no firm clinical diagnosis, several of whom were suspected to have cardiomyopathy.In 369 episodes of atrial fibrillation the following drugs were used singly or in combination at the time of DC shock therapy: digitalis, quinidine, procainamide, and pro- pranolol.In the remaining 45 episodes no drugs were used at all.The method of DC shock therapy and the results of the first 200 episodes have already been re- ported in a previous paper (Szekely, Batson, and Stark, 1966a).Only the method of anaesthesia has since been modified.After abandoning pentothal, methohexitone