The levels of 15-F2t-isoP, nitrotyrosine and tyrosine, ET-1, and TNF-alpha in blood will be determined at 2 hours postoperatively. Troponin I levels will be determined at 2, 12, and 24 hours postoperatively. Cardiac function will be assessed up to 6 hours postoperatively by pulmonary artery catheter and transesophageal echocardiography.