AMRINONE REVERSES BUPIVACAINE-INDUCED REGIONAL MYOCARDIAL DYSFUNCTION

Amrinone has been shown to have therapeutic effects on bupivacaine-ind uced cardiovascular toxicity, but its exact effects on the heart are n ot well understood. This study evaluated the regional myocardial effec t of amrinone on bupivacaine-induced cardiovascular toxicity in in sit u beating hearts in 10 dogs using a selective coronary perfusion and s onomicrometry. Ln the control group, bupivacaine was administered into the left anterior descending coronary artery (LAD) for 15 min at four steps: baseline, step 1, step 2 and step 3, (calculated LAD plasma co ncentrations; 0, 5, 5 and 10 mu g . ml(-1), respectively). In the amri none group, amrinone (5 mu g . ml(-1)) was simultaneously infused at s teps 2 and 3 in addition to bupivacaine infusions. Regional myocardial function of the LAD supplied area was evaluated by analysis of the le ft ventricular pressure-segment length loop. In the control group, sys tolic shortening decreased from the baseline (10.5+/-1.3%, mean+/-SEM) to step 3 (0.1+/-1.3%), and post-systolic shortening increased from t he baseline (18.0+/-3.7%) to step 3 (52.3+/-5.5%) dose-dependently. Ln contrast, with amrinone infusion at steps 2 and 3, both variables ret urned to near baseline values. These results indicate that amrinone re verses bupivacaine-induced regional myocardial dysfunction.