Effect of bupivacaine on electrophysiologic responses to acute myocardial ischemia: Bupivacaine reduces myocardial excitability. (A) Representative polar activation recovery interval maps comparing the effect of bupivacaine on ventricular activation recovery interval and dispersion of repolarization changes during the left anterior descending (LAD) occlusion. (B and C) The global ventricular activation recovery interval was reduced during acute ischemia in both control and spinal anesthesia due to cardiac sympathoexcitation; however, the magnitude of activation recovery interval reduction was attenuated with thoracic intrathecal anesthesia (n = 7). (D and E) Global dispersion of repolarization increased during acute ischemia in both control and thoracic spinal anesthesia; however, the magnitude of dispersion of repolarization increase was greater with the control treatment (n = 7). (F) Number of premature ventricular contractions during ischemia was decreased after bupivacaine application (n = 7), *P < 0.01 versus baseline, #P < 0.05 versus control. For B–D, the boxes show the 25th to 75th percentiles and the median, and the whiskers show 5th and 95th percentiles. For F, mean with 95% CI is shown.