THE EFFECTS OF WARM VERSUS COLD BLOOD CARDIOPLEGIA ON ENDOTHELIAL FUNCTION, MYOCARDIAL-FUNCTION, AND ENERGETICS

Background. Recent interest in the use of normothermic blood cardiople gia is based on theoretical advantages over the traditional method of hypothermic myocardial protection. This study was designed to compare the effects of warm and cold blood cardioplegia on left ventricular fu nctions and energetics and coronary responsiveness. Materials and Meth ods. Two groups of mongrel dogs (n=7 each) underwent either normotherm ic cardiopulmonary bypass (CPB) with continuous warm (37-degrees-C) bl ood cardioplegia or hypothermic (26-degrees-C) CPB with a single dose of cold (4-degrees-C) blood cardioplegia supplemented with topical coo ling during 30 minutes of aortic clamping. There was no deterioration in the endothelium-dependent and -independent coronary relaxation as t ested by the infusion of acetylcholine and nitroglycerin after cardiop legic arrest for either group. At 60 minutes of reperfusion, both grou ps had complete recovery of left ventricular contractility as measured by the preload recruitable stroke work area derived from the measurem ent of the ventricular pressure (micromanometer catheter) and volume ( conductance catheter) relation. The analysis of myocardial energetics in terms of the myocardial oxygen consumption-pressure volume area rel ation did not reveal any significant changes between the y-intercepts and the slopes of the two groups. Conclusions. For 30 minutes of aorti c cross-clamp time, continuous warm cardioplegia did not provide any b enefit over a single injection of cold cardioplegia in coronary endoth elial and smooth muscle function, myocardial function, and energetics.