Abstract

The cardiovascular electrophysiologic and hemodynamic effects of bupivacaine were investigated in seven pentobarbital anesthetized dogs. Bupivacaine produced dose-dependent decreases in cardiac output and stroke volume and increases in systemic vascular resistance. Electrophysiologic effects included lengthening of the RR, PR, QRS, and QTU intervals, and enhancement of the U or “slow wave” following the T-wave. Bupivacaine serum levels of 2.1 ± 1.1 μg/ml produced a 15% increase in the QTU interval, and no animal sustained ventricular tachycardia upon ventricular pacing. Bupivacaine serum levels of 7.9 ± 3.1 μg/ml produced a 60% increase in the QTU interval duration, and six out of seven animals sustained ventricular tachycardia upon ventricular pacing. The higher dose of bupivacaine resulted in an unusual polymorphic undulating ventricular tachycardia analogous to that seen with Torsades de Pointes.