Improvement in aerobic and hemodynamic responses to exercise following aorta-coronary bypass grafting.

Preoperative and postoperative hemodynamic studies were performed during exercise in 70 patients having aorta-coronary bypass grafting for the treatment of angina. There was significant symptomatic improvement with 88% of patients free of angina postoperatively. In patients with complete revascularization there was a marked improvement during exercise in maximal oxygen consumption, cardiac index, and maximal pressure-rate product. In addition, there was a fall in pulmonary arterial pressure postoperatively. In contrast, patients with incomplete revascularization showed a small but insignificant rise in maximal oxygen consumption and cardiac index. The major reason for the increase in cardiac index was a marked increase in heart rate rather than a change in stroke index. In patients with complete revascularization there was a significant increase in stroke work index at maximal exercise.