急性心肌缺血家兔心室易损期和心室颤动阈的变化

Changes in ventricular vulnerable period and ventricular fibrillation threshold during acute myocardial ischemia in rabbits

目的观察急性心肌缺血对心肌易损性的影响。方法采用程序电刺激方法测定家兔心室颤动阈(VFT)、心室易损期(VVP)和有效不应期(ERP)。结果 急性心肌缺血时VFT降低,VVP延长,ERP缩短。VFT的迅速降低发生于冠状动脉结扎1分钟左右,结扎5分钟VFT降低幅度最大,由对照值10.55±1.54V降为6.39±1.19V(P<O.01;VVP延长和ERP的缩短最大位发生于冠状动脉结扎20分钟,VVP由对照值11.26±1.80ms延长为48.25±5.71ms(P<O.01),ERP由161.38±14.47ms缩短为136.70±11.84ms(P〈0.05)。结论 急性心肌缺血时VFT降低,VVP延长,ERP缩短均可增加心肌的易损性。VFT降低发生于急性心肌缺血早期,VVP延长和ERP缩短发生于急性心肌缺血后期。这提示VFT的降低与VVP的延长和ERP缩短具有不同的病理生理意义。采用程序电刺激方法检查心肌易损性时,应同时测定VFT、VVP和ERP。

Objective Observe effects of myocardial vulnerability during acute myocardial ischemia Methods ventricular fibrillation threshold (VFT), ventricular volnerable period (VVP) and effective refractory period (ERP) were determined by programmed electrical stimulation (PES). Results VFT was decreased, VVP was plolonged and ERP was shortened during acute myocardial ischemia, acute myocardial ischemia Maxial change of VFT occurred within the first 5min (P<0. 01), and maxial change of VVP and ERP occurred 20min after coronary artery ligation (P<0. 01 and P<0. 05). Conclusion myocardial vulnerability was increased by changes of VFT.VVP and ERP, decreasing of VFT is earlier than prolonging of VVP and shortening of ERP during acute myocardial ischemia. It suggests that changes of VFT, VVP and ERP represent different pathophysiological significance. VFT,VVP and ERP should be determined together when myocardial vulnerability is checked by PES.