Anesthetics influence myocardial infarct size

This study compares the effect of three anesthetics on infarct size and regional myocardial blood flow. The anesthetics--fentanyl, Na-pentobarbital, and halothane--differ in their effects on such hemodynamic parameters as blood pressure and heart rate. The mean blood pressure during ligation was 144/91 mm Hg with fentanyl, 141/104 mm Hg with Na-pentobarbital, and 113/82 mm Hg with halothane. The heart rate was 98, 146, and 135 beats/min, respectively. The most significant finding of our study following 90 min of reflow was the infarct size of 26 +/- 8% of the occluded vascular bed under the influence of fentanyl; infarct size under Na-pentobarbital and halothane was 32 +/- 5 and 47 +/- 7%, respectively. The regional flow in relation to the zones of the infarction also differed among the groups. Regional flow under Na-pentobarbital was 24 +/- 6% of normal flow at 90 min of occlusion in the infarcted tissue; regional flow under fentanyl and halothane was 9 +/- 2 and 5 +/- 1%, respectively. The flow in the nitroblue-tetrazolium-staining zone of the occluded vascular bed was 69 +/- 11% (fentanyl), 77 +/- 11% (Na-pentobarbital), and 83 +/- 25% (halothane). It is concluded that anesthetics may well influence infarct size and the outcome of a myocardial infarction following a 90-min ischemia. Hemodynamic effects induced by these anesthetics may well be responsible for this outcome and could be determinants of infarct size, possibly by influencing collateral flow.