缺血预处理对体外循环缺血心肌的保护效果

Effects of ischemic preconditioning on myocardial protection during CPB

观察缺血预处理对体外循环(CPB)心脏高钾、冷停跳心肌的保护作用。方法:10只健康犬随机分为对照组(C组)与预缺血组(PC组),每组5只。CPB期间心脏高钾停跳,全心缺血60分.恢复灌注30分。PC组在CPB开始后、心脏停跳前增加预缺血5分钟、再灌注10分钟,对比观察阻断升主动脉前、后心肌超微结构、腺苷酸含量(ATP、ADP、AMP、TAN、EC)、脂质过氧化物丙二醛(MDA)以及血流动力学的变化。结果:(1)PC组在缺血30分钟、60分钟及开放升主动脉20分钟时,正常线粒体和糖原含量均接近缺血前水平,并明显高于C组(P<0.01);(2)心脏阻断前、后PC组心肌组织ATP、EC含量无显著变化,与C组同时比较差异十分显著(P<0.05或0.01);(3)缺血60分钟以及开放20分钟C组心肌MDA含量显著升高,与PC组比较差异十分显著(P<0.05或0.01);(4)开放升主动脉后,PC组血流动力学各项参数迅速恢复,其中CO、SV、CI、LVSW与C组比较差异有显著性(P<0.05或0.01)。结论:心肌缺血预处理明显增强体外循环心脏缺血再灌注期超微结构的保护效果。降低ATP的消耗,减少脂质过氧化物的形成,加速血流动力学的恢复。

Objective: To study whether ischemic preconditioning could enhance protection of myocardium from ischmia reperfusion injury during CPB. Method: Ten dogs were randomly divided into control group and ischemic preconditioning group. In both groups,after CPB and cardiac arrest with cold cardioplegia,global ischemia of the heart was sustained for 60 min and then were followed by reperfusion 30 min. In ischemic preconditioning group, the ischemia of 5 min and reperfusion of 10 min carried out before cardioplegic heart arrest. Ultrastructure,levels of adenine necleotids and lipid peroxide of the myocardium,and hemodynamics were examed and measured. Results:(1) In preconditioning group,the percentage of normal mitochandria and glycogen did not change during subsequent ischemia and reperfusion,and was higher markedly than that in control group (P<0.01) (2)Preconditioning group had much higher levels of myocardial adenosine triphosphate(ATP),EC and TAN than control group had during ischemic reperfusion (P<0.05 or 0.01). (3)MDA level of control group was obviously higher than that of preconditioning group during ischemic reperfusion (P<0.05 or 0.01). (4)The recoveries of CO、SV、CI、LVSW in preconditioning group were much better than those in control group (P<0.05 or 0.01) following reperfusion. Conclusion: Ischemic preconditoining may enhance myocardial protection during CPB.