Cardiac Electrophysiologic Effects of Lidocaine and Bupivacaine

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Abstract
The cardiac electrophysiologic effects of bupivacaine (B) and lidocaine (L) were evaluated in an isolated rabbit Purkinje fiber-ventricular muscle model to determine the effects of a) progressively increasing and b) decreasing concentrations of B and L on transmembrane action potentials. Bupivacaine (3 and 5 μg/ml) signifcantly decreased diastolic resting potential, maximum rate of depolarization, and action potential amplitude. Lidocaine (10–20μg/ml) also decreased maximum rate of depolarization and action potential amplitude, but the decreases were significantly different from those produced by B. High concentrations of B (30μg/ml) and L (100μg/ml) resulted in delayed conduction between Purkinje fibers and ventricular muscle cells and, ultimately, conduction blockade. The duration of conduction blockade was significantly longer with B than with L. The results of this study indicate that B produces electrophysiologic changes in cardiac tissue that may produce ventricular arrhythmias of a reentrant type.