A comparison of the electrocardiographic cardiotoxic effects of racemic bupivacaine, levobupivacaine, and ropivacaine in anesthetized swine

We sought, in this observer-blinded study, to determine the lethal dose for each of the local anesthetics levobupivacaine (L), racemic bupivacaine (B) , and ropivacaine (R), and to compare their respective effects on the QRS i nterval of the precordial electrocardiograph after intracoronary; injection . Anesthetized swine were instrumented with; a left anterior descending art ery coronary angiography catheter and injected with increasing doses of L, B, or R according to a randomized protocol. The doses administered were 0.3 75, 0.75, 1.5, 3.0, and 4.0 mg, with further doses increasing in 1-mg incre ments until death occurred. Plotting the mean maximum QRS interval as a fun ction of the log(10) mmol dose allowed the following cardiotoxicity potency ratios to be determined for a doubling of QRS duration-B:L: R = 2.1:1.4:1. The lethal doses in millimoles (median/range) for L and R were (0.028/0.02 4-0.031) and (0.032/0.013-0.032), respectively, and were significantly high er than for B (0.015/0.012-0.019) - (P < 0.05, n = 7 for all groups). The l ethal dose did not differ between R and L. Thus, the cardiotoxicity potency ratios for the three anesthetics based on lethal dose were: 2.1:1.2:1. If the anesthetic potencies for B and L, are similar, the latter should have l ess potential for cardiotoxicity in the clinical situation.