Lipid peroxidation in open-heart surgery

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Abstract
Production of oxygen free radicals and subsequent lipid peroxidation are thought to occur during cardiopulmonary bypass (CPB) and myocardial ischaemia- reperfusion injury. Malondialdehyde (MDA), a lipid peroxidation product, was measured simultaneously in arterial and coronary sinus blood before CPB and after release of the aortic crossclamp. Additional arterial samples were drawn pre-, per-, and postoperatively. Thirteen patients scheduled for coronary artery and/or valvular surgery were studied. Cold, crystalloid, cardioplegic arrest (54 [35-120] minutes, median [range]) was induced retrogradely. Preoperatively, arterial MDA was 0.78 ± 0.4 (mean ± SD) μmol/l, and increased during CPB (highest level 3.66 ± 1.08 μmol/l, p < 0.002, 30 minutes after the start of reperfusion). Arterial MDA was still increased four hours after the end of CPB (3.17 ± 0.88 μmol/l, p < 0.003), but had returned to normal the first postoperative day. No difference was found between arterial and coronary sinus samples at any time. In conclusion, MDA increased in arterial blood during CPB, indicating that lipid peroxidation occurred. There was no intracoronary release of MDA during reperfusion of the ischaemic heart.