Chello M, Mastroroberto P, De Amicis V, Pantaleo D, Ascione R, Spampinato N
Department of Cardiac Surgery, Medical School of Catanzaro, Italy.
Ann Thorac Surg. 1997 Mar;63(3):683-8. doi: 10.1016/s0003-4975(96)01367-7.
Left ventricular dysfunction is frequently observed in patients after hypothermic cardioplegic arrest, and often inotropic intervention is necessary for patients to be successfully weaned from cardiopulmonary bypass (CPB). A myocardial beta-adrenergic receptor (beta AR) desensitization has been noted to occur after hypothermic CPB in patients undergoing coronary artery bypass grafting. This randomized study was undertaken to determine the effect of cardioplegic solution temperature on cardiac beta ARs.
Two groups of patients (20 patients in each) scheduled for elective coronary artery bypass grafting underwent CPB with either intermittent warm or cold blood cardioplegia. The density of the beta ARs, the proportion of beta 1- to beta 2-adrenergic receptors, and the beta AR coupling capacity to adenylate cyclase were determined in specimens of the right atrial tissue at baseline, during CPB, and after discontinuation of CPB. Plasma concentrations of catecholamines were also measured in both arterial and coronary sinus samples.
In both cardioplegia groups, no significant modification in either the beta AR density or the proportion of beta 1- to beta 2-adrenergic receptors was detected. However, a significant decrease in adenylate cyclase activity after stimulation with isoproterenol was observed in the cold blood cardioplegia group during CPB (p < 0.01) and 30 minutes after its discontinuation (p < 0.05). Moreover, a significant decrease in adenylate cyclase activity during CPB was detected in this group after stimulation with sodium fluoride (p < 0.05), but this pattern was found to be completely reversed by 30 minutes after discontinuation of CPB. No modification in the basal or stimulated adenylate cyclase activity was observed in the warm blood cardioplegia group during or after CPB.
Our results confirm the finding from previous studies of a cardiac beta AR desensitization after hypothermic cardioplegic arrest, and provide evidence of the advantages of intermittent warm blood cardioplegia in preserving the autonomic sympathetic function of the heart.
低温心脏停搏后患者常出现左心室功能障碍，且患者成功脱离体外循环（CPB）通常需要进行变力性干预。在接受冠状动脉旁路移植术的患者中，低温CPB后已发现心肌β-肾上腺素能受体（βAR）脱敏现象。本随机研究旨在确定心脏停搏液温度对心脏βAR的影响。
两组患者（每组20例）计划进行择期冠状动脉旁路移植术，分别接受间歇性温血或冷血心脏停搏液的CPB。在基线、CPB期间和CPB停止后，测定右心房组织标本中βAR的密度、β1-与β2-肾上腺素能受体的比例以及βAR与腺苷酸环化酶的偶联能力。同时还测定了动脉和冠状窦样本中的血浆儿茶酚胺浓度。
在两个心脏停搏液组中，均未检测到βAR密度或β1-与β2-肾上腺素能受体比例的显著变化。然而，冷血心脏停搏液组在CPB期间（p < 0.01）及其停止后30分钟（p < 0.05），异丙肾上腺素刺激后腺苷酸环化酶活性显著降低。此外，该组在氟化钠刺激后CPB期间腺苷酸环化酶活性显著降低（p <
