摘要
目的 缺血预适应是指心肌短暂缺血再灌注后 ,使心肌产生适应性反应 ,对随后持续缺血的耐受能力明显增强 ,使持续缺血造成的心肌梗塞范围缩小 ,减轻缺血再灌注心律失常和心功能异常。我们用在体兔心脏缺血预适应模型 ,初步观察了预适应心脏保护的电生理基础 ,探讨其在减少恶性心律失常中的可能作用。方法 将 30只健康家兔随机分成对照组、缺血组、预适应组 ,运用Franz心外膜MAP探针记录技术 ,观察约 40分钟稳定的心电图和MAP图形 ,此后行程序期前刺激测定心室肌有效不应期。结果 缺血组缺血 1分钟内 ,即出现心肌细胞MAPA和dv dtmax明显下降 (P <0 0 1)。此后 ,随缺血时间延长 ,MAP形态逐渐变小。分别于再灌注 5、10和 2 0分钟 ,MAPD5 0 、MAPA和dv dtmax才逐渐恢复接近正常 (P >0 0 5 )。缺血组持续缺血前 5分钟和整个再灌注期 ,MAPD90 和基础值比较变化不大 (P >0 0 5 ) ,而持续缺血 5～ 2 0分钟 ,才发现MAPD90 明显缩短。持续缺血早期 ,ST段逐渐升高 ,但随缺血时间的进一步延长 ,至缺血 15分钟后 ,ST段反而下降。在上述参数动态变化过程中 ,预适应可明显减轻缺血造成的MAPA、dv dtmax下降程度 ,相对延长MAPD5 0 和MAPD90 ,减少ST段升高幅度。各实验组ERP MAPD90 分别为 :C组 1 0 5± 0 0 3;
Objective A brief coronary occlusion before a more prolonged occlusion, termed ischmic preconditioning, can induce changes in the heart that make it more resistant to subsequent ischemic exposure It can also reduce the infarct size, preserve the postischemic cardiac function and protect the heart against the appearance of subsequent arrhythmia in ischemic tissue We employed an anaesthetised open chest rabbit model of ischemic preconditioning to preliminarily observe the protective electrophysiologic basis, and approached the possible roles on reducing the appearance of lifethreatening arrhythmias Methods We randomly devided 30 rabbits into control (C) group, ischemic (IS) group and ischemic preconditioning (IPC) group With the recording techniques of monophasic action potential (MAP), we continually monitored the stable ECG and MAP for 40 minutes, and then examined the ventricular effective refractory period by programmed extrastimulation Results In 1 minute ischemic period, MAPA and dv/dt max in IS group rapidly decreased ( P <0 01) Thereafter, the form of MAP became smaller with the prolongation of ischemia MAPD 50 , MAPA and dv/dt max gradually reverted close to normal levels in 5 , 10 and 20 minute reperfusion period ( P >0 05) In IS group, the differences between MAPD 90 and its baseline were no significant during the 5 minute ischemia and the whole reperfusion period ( P >0 05) MAPD 90 did not markedly shortened until 5～20 minutes occlusion ST segment gradually elevated in early ischemia, but with the prolongation of ischemia to 15 minutes, ST segment inversely depressed During the dynamic changes of parameters as mentioned above, the preconditioning may markedly diminish the decreasing degree of MAPA and dv/dt max, relatively prolong MAPD 50 and MAPD 90 , and reduce the elevating degree of ST segment due to ischemic insult ERP/MAPD 90 in C group, IS group and IPC group was 1 05±0 03, 0 77±0 01, 0 94±0 01, respectively ERP/MAPD 90 in IS group was markedly smaller than other groups ( P <0 05) Conclusions Preconditioning relatively increased MAPA,dv/dt max and ERP/MAPD 90 ,prolonged MAPD 50 and MAPD 90 It indicated that preconditioning could improved the conductive ability of ischemic myocardium, diminish the irregular repolarization between normal myocardium and ischemic myocardium Thereby, ischemic preconditioning could reduce the incidence of reentrant arrhythmias
出处
《中国介入心脏病学杂志》
2000年第1期48-51,共4页
Chinese Journal of Interventional Cardiology
关键词
缺血预适应
单向动作电位
心肌保护
电生理学
Ischemic preconditioning Monophasic action potential Mycoardial protection Electrophysiology
