The simultaneous measurements of mixed venous oxygen saturation (SvO2) and right ventricular ejection fraction (RVEF) have now made it possible to precisely define and correlate the various hemodynamic changes that occur during abdominal aortic operations. Twenty-five patients undergoing infrarenal abdominal aortic aneurysm repair were examined with a pulmonary artery catheter capable of continuously measuring SvO2 and RVEF. With aortic clamping, significant reductions in cardiac index, stroke volume index, and right ventricular end-diastolic volume index (RVEDVI) were noted, while RVEF remained unchanged. Following unclamping of the aorta, a significant reduction in SvO2 occurred, accompanied by an increase in mean pulmonary artery pressure and in pulmonary vascular resistance. Despite the increase in afterload, RVEDVI and RVEF did not change after unclamping. These preliminary data suggest that right ventricular function is preserved during abdominal aortic aneurysm repair.