急性心肌缺血犬心室颤动时的左室心内膜电图

目的　探讨急性心肌缺血心室颤动 (室颤 )的形成机理。方法　经开胸结扎冠状动脉前降支或经皮腔内冠状动脉成形术球囊堵塞前降支 ,造成 4只犬心肌缺血室颤模型。经股动脉插入4极电极导管 ,顶端置于左室心尖部 ,同步记录体表心电图、左室心尖部单极和双极心内膜电图。结果　 4只犬均发生室颤。其中 2只犬在室颤发生 1～ 3min时 ,双极心内膜电图显示幅度、形状、频率规则的R波 ;另 2只犬也显示相当规律的R波。随着室颤持续时间的延长 ,心内膜电图的规律性逐渐消失。结论　研究提示 ,心室内存在多个相对独立而性质和形状不一的折返环是室颤形成的机理之一。

The endocardial electrogram at ventricular fibrillation induced by acute myocardial ischemia

Objective To investigate the mechanism of ventricular fibrillation (VF) induced by acute ischemia with endocardial electrography. Methods Acute myocardial ischemia in 4 dogs was set by clipping left anterior descending coronary artery (LAD) or occluding by PTCA balloon. The unipolar and bipolar endocardial electrogram (EE) of left ventricular apex, and 3 body surface electrocardiography (ECG) were simultaneously recorded. Results The VF was induced in 4 dogs. During the first 3 min of the typical VF demonstrated on surface ECGs, regular QRS wave in amplitate,shope and frequency was showed in bipolar EE recordings in 2 dogs and quite regular QRS wave in other 2 dogs, which indicated organized electric activity at the local ventricular myocardium. As persistence of VF, the QRS wave in bipolar EE was becoming less regular. Conclusion Several independent reentry circuits existed in ventricle may contribute to VF development.