Electrophysiological and hemodynamic disturbances in a patients overdosed with disopyramide.

Disopyramide exerts a quinidinelike effect on the heart and is a valuable drug for treating atrial and, especially, ventricular tachyarrhythmias. The therapeutic plasma concentration of disopyramide is thought to be 2.0-4.0 (5.0) microgram/ml. We here report the cardiac effects of a high dose of disopryamide in a patient with extensive coronary artery disease complicated by ventricular extrasystoles. At plasma levels above approximately 7.0 micrograms/ml, heart rate was decreased, while PQ interval, width, and QT interval were increased. At concentrations above approximately 6.0 micrograms/ml, disopyramide exerted negative intropic effects as judged by increases in mean right atrial, pulmonary arteriolar, and pulmonary capillary venous pressures and a decrease in cardiac output.