LIPID-PEROXIDATION, ANTIOXIDANT STATUS AND TROPONIN-T FOLLOWING CARDIOPULMONARY BYPASS - A COMPARISON BETWEEN INTERMITTENT CROSS-CLAMP WITHFIBRILLATION AND CRYSTALLOID CARDIOPLEGIA

(O)bjective: Intermittent crossclamp with fibrillation affords equival ent myocardial protection to cold crystalloid cardioplegia in patients undergoing elective coronary artery surgery. This study is a direct c omparison between the two techniques with regards to free radical acti vity. Methods: The study design was part of a prospective randomised t rial, We studied 24 consecutive patients with ejection fractions of 30 % or greater undergoing elective coronary artery surgery. Patients wer e randomised into two groups. In group 1 (n = 13) the myocardium was p rotected by intermittent aortic cross clamping with fibrillation and g roup 2 (n = 11) by antegrade cold crystalloid cardioplegia. The determ inants of free radical activity were serial peripheral venous samples for lipid peroxidation and plasma antioxidant status (before and at 1, 6, 24 and 72 h after the end of cardiopulmonary bypass). The determin ant of the efficacy of myocardial protection was serial peripheral ven ous samples of cardiac troponin-T taken at the same rime intervals. Re sults: The groups were similar with respect to age, ses distribution. preoperative ventricular function, left main stem disease, number of g rafts and bypass times. Lipid peroxidation measurements al the 1 h tim e point were higher than preoperative values (7.24 +/- 1.19 vs. 4.48 /- 0.69 and 9.36 +/- 1.46 vs. 4.98 +/- 1.02 (mean +/- S.E) in groups 1 and 2, respectively (units in mmol/l)) thereafter values decreased to near preoperative values by 72 h. There was no significant difference between the groups (P = 0.42). Total plasma antioxidant status values at the 1 h time point were lower than the preoperative values for all patients (1.33 +/- 0.07 vs. 1.63 +/- 0.06 and 1.42 +/- 0.07 vs. 1.63 +/- 0.05 (mean +/- standard error) in groups 1 and 2, respectively, (u nits in mmol/l)) and thereafter at the subsequent time points increase d but never attained their preoperative value. There was no statistica lly significant difference between the two groups (P = 0.59), Troponin -T measurements showed no significant difference between the two group s at all time points (P = 0.2217). Conclusions: This study shows that lipid peroxidation is initially elevated and the defence mechanisms ag ainst oxygen free radicals-'antioxidant status'-are depressed followin g cardiopulmonary bypass. The degree of oxygen free radical activity p roduced during ischaemia and reperfusion was similar in both types of myocardial protection employed in this study. (C) 1997 Elsevier Scienc e B.V.