Present Status of Electroversion in the Management of Cardiac Dysrhythmias

Abstract

The theoretical and practical considerations of electrical reversion of cardiac dysrhythmias are reviewed and a comparison made between AC and DC defibrillation, indicating the superiority of DC under all circumstances. The indications for, immediate and late results of DC shock for atrial and ventricular dysrhythmias are presented, the complication of such treatment reviewed, and the need for anticoagulant cover, anesthesia, and drug therapy preceding and following the electrical treatment discussed. Each patient requires individual assessment, particularly those with chronic rhythm disturbances, especially atrial fibrillation, in whom electrical energy settings in excess of 300 joules are rarely indicated for the risk of complications becomes progressively higher as the energy setting is increased and the length of time sinus rhythm persists in this group of patients may be short. Patients with acute rhythm disturbances, however, with potentially serious hemodynamic consequences should be treated with maximum electric energies if needed. Caution is also advised in patients with coronary heart disease, atrial fibrillation, and a slow ventricular rate, even in the absence of digoxin, patients with rapidly changing rhythm disturbances, those who cannot maintain sinus rhythm for a significant period of time despite drug therapy, patients with the "sick sinus syndrome," those with atrial fibrillation of more than 5 years standing with a cardiothoracic ratio exceeding 55%, and patients in lone atrial fibrillation. Heavily digitalized patients in general should have their electroversion postponed if possible, but if not, they should be protected against serious ventricular rhythm disturbances immediately after the shock by an intravenous dose of lidocaine, phenylhydantoin, or procaine amide immediately before and the initial energy setting should be reduced to 5 joules. Quinidine or some other antidysrhythmic drug may be needed in an attempt to maintain sinus rhythm after successful electroversion, but even when controlled with adequate blood levels, results are poor.