Evaluation of Myocardial Damage in Patients Undergoing Coronary-Artery Bypass Procedures with Halothane-N2O Anesthesia and Adjuvants

Abstract

During a 6-month period in 1975, 102 patients undergoing scheduled coronary-artery bypass grafting were studied by both conventional ECG and heart-specific enzymatic methods to evaluate the incidence and estimate the extent of myocardial damage associated with an anesthetic management protocol using halothane as a primary agent with adjuvant agents. Anesthetic interventions were made to maintain heart rate and systolic pressure at resting levels or below the heart rate systolic pressure product documented during exercise-induced angina. These interventions included adjustment of halothane concentration in all patients, the use of adjuvant agents in 88.2 percent, vasodilators in 26.5 percent, and the precardiopulmonary bypass use of vasoconstrictor or cardiostimulants in 9.8 percent. There were 2 early postoperative deaths. ECG evidence of infarction was observed in 4 surviving patients. Sustained release of heart-specific CPK-MB isoenzyme occurred in 78 percent of surviving patients. Isoenzyme activity was detected in only 1 patients prior to cardiopulmonary bypass (CPB), in 1 patient during CPB, and in all others after termination of CPB. The extent of myocardial damage as estimated by integrating CPK-MB values over time was directly related to number of vessels grafted and to aortic cross-clamp and CPB times. The ECG and enzymatic data both document a low level of myocardial damage associated with this anesthetic management protocol.