Clinical Study Of Adenosine In Cardioprotection During Cardiopulmonary Bypass In Cardiac Surgery

Objective: The purpose of this study was to observe the cardioprotective effects of adenosine-supplemented cardioplegia on clinical effects, myocardial enzymes and myocardial ultrastructure. To investigate the cardioprotection of adenosine(Ado) during cardiopulmonary bypass(CPB). Methods: Forty five patients undergoing heart valve replacement were randomly divided into three groups. Group A(n=15) received modified St. Thomas No. 2 cardioplegic solution. Group B(n=15) received modified St. Thomas No. 2 cardioplegic solution with Ado(2 mmol/L) and group C(n=15) received modified St. Thomas No. 2 cardioplegic solution with Ado (3 mmol/L) induction. Cardioplegia was administered antegrade via the aortic root or coronary ostia. The cardioprotection was evaluated by the dosage of cardioplegic solution, heart arrest, CPB time, aortic clamping time, ratio of heart auto-resuscitation, ventricular fibrillation incidence, temporary pacemaker usage, dopamine and(or) other inotropic agents dosis, mechanical ventilation time. Blood samples were drawn from the radial artery at the following time points: anesthetic stage, 30min afer aortic declamping, 6hr afer aortic declamping, 12hr afer aortic declamping and 24hr afer aortic declamping. The samples were used to measure the haematocrit(Hct) and the concentration of creatine kinase(CK), isoenzyme of creatine kinase(CK-MB), lactate dehydrogenase(LDH) and cardiac troponin I(cTn-I). Myocardial tissue was taken at following time intervals: before cardiac arrest, 15min afer cardiac arrest and 30min after aortic declamping. The changes of myocardial ultrastructure were studied. Results: Ado cardioplegia had the same good effect as modified St. Thomas No. 2 cardioplegia for arresting heart. There was no statistically significant in the dosage of cardioplegic solution among three groups(P>0.05). After aortic declamping, group B and C had higher ratio of heart auto-resuscitation, lower incidence of ventricular fibrillation and lower temporary pacemaker usage than group A(P<0.05). But there was no statistically significant between group B and C(P >0.05). There was no statistically significant in dopamine dosis among three groups(P>0.05). However, other inotropic agents dosis of group B and C were lower than group A(P <0.05). In addition, group B and C had lower leakage of myocardial enzymes than group A(P <0.05). There was no statistically significant between group B and C(P >0.05). Compared with group A, the changes of myocardial ultrastructure of group B and C were alleviative. Conclusions: Ado cardioplegia had the same good effects as modified St. Thomas No. 2 cardioplegia for cardioprotection. Ado cardioplegia has following advantages: elevated the ratio of heart auto-resuscitation; degraded the incidence of ventricular fibrilliation; improved the cardiac function recovery after CPB; decrease the need for post-operative inotropic support and the release of myocardial enzymes; attenuated the ischemia reperfusion injury.