CIRCULATING ENDOTHELIN IN PATIENTS UNDERGOING CORONARY-ARTERY BYPASS-GRAFTING

Increased synthesis of endothelin, (a powerful physiological vasoconst rictor), is a uniform response to endothelial injury and has been asso ciated with myocardial ischemia and reperfusion. This study tests the hypothesis that coronary artery bypass grafting (CABG) affects endothe lin plasma concentrations in various vascular beds. Twenty-four CABG p atients were included in this study. Endothelin was determined in mult iple plasma specimens obtained from superior vena cava, aortic root an d coronary sinus (CS). Venous endothelin plasma concentrations collect ed in CABG patients before surgery were 1.16 +/- 0.18 pg/ml. They incr eased after sternotomy (1.71 +/- 0.12 pg/ml) and during (2.97 +/- 0.27 pg/ml) and after cardiopulmonary bypass (CPB, 2.72 +/- 0.21 pg/ml). T here is no net release of endothelin from the coronary circulation bef ore (aorta 2.26 +/- 0.13 pg/ml vs CS 2.44 +/- 0.17 pg/ml, not signific ant (n.s.), during (cardioplegia 2.55 +/- 0.17 pg/ml vs CS 2.45 +/- 0. 15 pg/ml, n.s.), and after aortic cross-clamping (aorta 2.95 +/- 0.23 pg/ml vs coronary sinus 2.71 +/- 0.18 pg/ml, n.s.). Pulmonary endothel in clearance is preserved on partial bypass (aorta 2.26 +/- 0.13 pg/ml vs vena cava 2.86 +/- 0.18 pg/ml, P < 0.003), but remains inhibited e ven 10-30 min after release of the aortic cross-clamp (aorta 2.95 +/- 0.23 pg/ml vs vena cava 2.97 +/- 0.27 pg/ml, n.s.). Two out of 24 pati ents had severe myocardial ischemia. These patients showed particularl y high endothelin concentrations. We conclude that (1) anesthesia and sternotomy and, to a greater extent, CPB increase endothelin concentra tions, (2) the absence of pulmonary endothelin clearance after total b ypass may indicate pulmonary endothelial dysfunction or damage, (3) th ere is no coronary net release of endothelin before, during and after aortic cross-clamping, and (4) severe myocardial ischemia may be assoc iated with increased endothelin concentrations.