Influence of normothermic systemic perfusion temperature on cold myocardial protection during coronary artery bypass surgery

Objective: To determine the effect of normothermic systemic perfusion on my ocardial injury when using cold cardioplegic techniques in patients undergo ing coronary artery bypass surgery, Method: Sixty six patients with stable angina pectoris were prospectively randomized into three groups according t o cardiopulmonary bypass temperature: hypothermia (28 degrees C, n = 22), m oderate hypothermia (32 degrees C, n = 22) and normothermia (37 degrees C, n = 22), All patients received cold antegrade crystalloid cardioplegia and topical cooling with saline at 4 degrees C, Serum samples were collected fo r troponin T and I estimation preoperatively, 4 hours after removal of the aortic cross clamp, and 12, 24, 36 and 48 hours postoperatively, In additio n, serial electrocardiographic studies were undertaken on days 1, 3 and 5. Results: Patients were similar with regard to preoperative and intraoperati ve characteristics Four patients showed ECG changes typical of perioperativ e myocardial infarction but remained clinically well (28 degrees C, one; 32 degrees C, one; 37 degrees C, two). In the remaining 62 patients, serum tr oponin T increased significantly from a mean baseline value of 0.02 ng/ml t o 1.5 +/- 0.9 ng/ml 4 hours after removal of the aortic cross-clamp (P < 0. 0001). Similarly, troponin I increased from 0.06 ng/ml to 0.63 +/- 0.47 ng/ ml 12 hours after reperfusion (P < 0.0001). Serum concentrations of both ma rkers subsequently declined with time but remained higher than preoperative values at 48 hours. There were no differences between the three groups wit h respect to peak and cumulative serum troponin release, Normothermic cardi opulmonary bypass did not compromise the efficacy of cold myocardial protec tion when assessed by serum troponin concentrations in low risk patients un dergoing coronary revascularization. (C) 1999 The International Society for Cardiovascular Surgery, Published by Elsevier Science Ltd. All rights rese rved.