缺血预处理对缺血再灌注心室肌有效不应期的影响

Effect of Effective Refractory Period in Ischemia Reperfusion Myocardium Produced by Preconditioning

目的探讨缺血预处理（ＰＣ）抗缺血再灌注（ＩＲ）心律失常的部分电生理机制。方法以单纯的心肌缺血（阻闭家兔左冠脉前降支）３０ｍｉｎ、再灌注３０ｍｉｎ为对照，采用心外膜程控期前刺激的方法，观测ＰＣ（缺血５ｍｉｎ，再灌注１０ｍｉｎ）后正常与缺血中心区心室肌于缺血前、缺血５，１５，３０ｍｉｎ以及再灌注５，１５，３０ｍｉｎ时的有效不应期（ＥＲＰ）。结果ＩＲ过程中两组正常心室肌ＥＲＰ于缺血３０ｍｉｎ时均较缺血前明显延长（Ｐ＜０．０５或Ｐ＜０．０１），但组间差别不显著（Ｐ＞０．０５）；在缺血５，１５，３０ｍｉｎ及再灌注５ｍｉｎ时两组缺血心室肌ＥＲＰ的变化趋势相似，而ＰＣ组ＥＲＰ的延长或缩短程度均比对照组小（Ｐ＜０．０５或Ｐ＜０．０１）。结论ＰＣ能降低缺血与再灌注早期心室肌ＥＲＰ空间分布的离散度，这可能是ＰＣ抗ＩＲ心律失常的部分电生理机制。

Objective\ To study a part of the electrophysiological mechanism by which preconditioning(PC) protect against arrhythmias induced by ischemia reperfusion(IR).\ Methods\ The control group(n=12) received a single IR(30 min LAD occlusion and 30 min reperfusion).\ The PC group(n =12) was preconditioned with 5 min occlusion and 10 min reperfusion followed by a sustained 30 min occlusion and 30 min reperfusion.\ Alteration of effective refractory period(ERP) at the center of ischemic myocardium and normal myocardium was examined at ischemia(I) 5, 15,30 min,and reperfusion(R) 5,15,30 min and before ischemia by programmed extrastimulation.\ Results\ The alteration of ERP in normal myocardium was not significantly different between two groups(P>0 05).\ The alliterative range of ERP in ischemic myocardium was less in the PC group at I 5,15,30 min and R 5 min(P<0 05 or P<0 01),although their variation was similar.\ Conclusion\ To lesson the dispersion of ERP may be a part of the electrophysiological mechanism by which PC protects against the arrhythmias induced by IR.