Arterial and coronary sinus blood will be sampled simultaneously before initiation of CPB and at 5 min reperfusion for Troponin I, 15-F2t-isoP, nitrotyrosine and tyrosine, ET-1, and TNF-alpha. An index of myocardial derived 15-F2t-isoP and peroxynitrite will be determined from the Cs-Ao difference in percentage ratio of plasma free 15-F2t-isoP and nitrotyrosine to tyrosine, respectively.