Treatment of myocardial ischemia with halothane or nitroprusside-propranolol

An experimental animal model was used to compare the effect of the two drug interventions on myocardial ischemia. Elevation of the ST segment on epicardial electrocardiogram in response to temporary occlusion of the coronary artery was used as an index of ischemia. For multiple sites distal to the left-anterior descending coronary artery (LADCA), ST segments were obtained, measured, and totaled (sigma ST). The effects of halothane (1.1% end-tidal concentration) were compared with those of a combination of nitroprusside and propranolol. The combination was given in a dosage that produced values for systemic blood pressure, heart rate, and maximal positive left-ventricular dP/dt (LV dP/dt) that were similar to those produced by halothane. Control measurements were obtained during chloralose-urethrane anesthesia. Both drug interventions reduced systemic blood pressure, heart rate, and left-ventricular dP/dt similarly. Occlusion of the left-anterior descending coronary artery alone did not change any of these hemodynamic variables. Although both drug interventions reduced sigma ST, the reduction was statistically significantly greater with halothane than with nitroprusside-propranolol.