急性缺血对犬在体心肌跨心室壁复极不均一性的影响

目的：探讨急性缺血对犬在体心肌跨心室壁复极不均一性及与心律失常的关系。方法：健康家犬10只，应用单相动作电位记录技术，同步记录健康家犬在体阻断左前降支主干前后心外膜、中层及心内膜心肌单相动作电位及体表心电图，分析相关参数的变化。结果：3层心肌单相动作电位时程正常供血状态下差异无显著性意义（P＞0．05），急性缺血状态下则均明显缩短，且心外膜、心内膜的缩短程度较中层心肌更为明显，差异有显著性意义（P＜0．05）。3层心肌间跨室壁复极离散度增大。10只犬中正常供血状态下无一例出现心律失常，急性缺血30min内4只出现了室性心动过速或心室颤动死亡，恶性心律失常发生率达40％。结论：急性缺血时犬在体心肌跨心室壁复极离散度增大，可能是导致缺血性室性心律失常的原因之一。

Effects of acute ischemia on repolarization heterogeneity across ventricular wall in intact canine

Objective To investigate effects of acute ischemia on repolarization heterogeneity across ventricular wall in intact canine. Methods With MAP recording technique,MAPs of Epi, Mid and Endo were recorded simultaneously by composite plunge-needle electrode across left ventricular wall in 10 canines in vivo during acute ischemia.Monophasic action potential duration at 90% repolarization(MAPD90) in three layers were measured, and other parameters were observed at same time. Results During acute myocardial ischemia, MAPD90 shortened remarkably in Epi and Endo while modestly in Mid. Difference of MAPD90 between Mid and Epi or Endo was significant(P<0.05).TDR(transmural dispersion of repolarization)in three layers of ventricular myocardium increased. Ventricular tachycardia or ventricular fibrillation occurred in 4 dogs under condition of acute ischemia, but no malignant arrhythmia occurred in all dogs before acute ischemia. Conclusion Repolarization heterogeneity across ventricular wall increased significantly under condition of acute ischemia,it may be associated with genesis of ischemic ventricular arrhythmias.