Postoperative myocardial ischemia in thoracic aortic aneurysms

Background. To determine the incidence and predictors of postoperative myoc ardial ischemia in non-coronary risk patients undergoing surgery for thorac ic aortic aneurysms. Methods. Design: a prospective, observational study. Setting: a general int ensive care unit in a university hospital. Participants: twenty patients wi thout ischemic heart disease, scheduled for elective surgical repair of tho racic or thoracoabdominal aortic aneurysms. Interventions: all patients und erwent aortic replacement with prosthetic graft and routine postoperative c are. Patients who developed myocardial ischemia received an infusion of cor onary vasodilators. Results. ECG episodes of myocardial ischemia were defined as reversible ST- segment changes of either >1 min of depression or >2 min of elevation at th e J point. All patients survived operation. Eleven patients (ischemia group ) developed myocardial ischemia, and 9 patients did not (non-ischemia group ). These episodes were transient in 8 cases, but lasted longer than 3 days in 3 cases. In univariate analysis of perioperative factors between the two groups, the use of total cardiopulmonary bypass (p<0.01), the cardiac inde x at ICU admission (P<0.05), and the incidence of preexistent hypertension (P<0.05) were significantly different. Multiple regression analysis identif ied the use of total cardiopulmonary bypass as the only predictor of myocar dial ischemia. Conclusions. The use of total cardiopulmonary bypass is predictive of perio perative myocardial ischemia in surgery for thoracic aortic aneurysms, prob ably due to the production of proinflammatory cytokines by systemic ischemi a and reperfusion. Prophylactic use of coronary vasodilators may be validat ed in these cases.