缺血心肌复极离散及迷走神经的保护作用

探讨急性心肌缺血后 ,迷走神经刺激对心室肌不同部位复极时程和复极离散的影响 ,及其对缺血心肌的保护作用。结扎兔冠状动脉左室支 (LVB) ,制备急性心肌缺血模型。分离、结扎并剪断双侧颈迷走、心交感神经 ,电刺激迷走神经外周端。心室复极时程以心外膜电图 (EPG)的QT间期及采用玻璃微电极技术记录的心肌细胞动作电位时程 (APD)表示。分别测定迷走神经刺激前后及缺血前后LVB支配区 (缺血区 )及非支配区 (非缺血区 )的QT间期及APD值。结果 :迷走神经刺激使正常心室肌不同部位的QT间期、APD均有明显缩短 (P <0 .0 5 )。急性心肌缺血后 ,缺血区与非缺血区的QT间期分别是 14 8.6 7± 10 .4 4vs 15 9.5 0± 14 .71ms(P <0 .0 5 ) ;APD90 分别是 :12 8.75±17.84vs 138.0 0± 11.2 2ms(P <0 .0 5 ) ;APD50 分别是 :74 .6 7± 12 .15vs 85 .0 0± 6 .78ms(P <0 .0 5 )。迷走神经刺激后 ,缺血区与非缺血区QT间期、APD差值明显缩小 ,分别是 ,QT间期 :5 .5 8± 1.0 1vs 12 .83± 4 .34ms(P <0 .0 5 ) ;APD904 .5 0± 0 .98vs 11.2 5± 7.0 9ms(P <0 .0 5 ) ;APD50 5 .4 1± 1.2 2vs 12 .5 0± 6 .19ms(P <0 .0 5 )。心肌缺血后心室易损期(VVP)明显延长 34± 2 2 .6 1ms,迷走神经刺激后VVP明显缩短至 11.75± 7.72m

Investigation on the Effect of Vagal Nerve Stimulation on Ventricular Repolarization Dispersion With Acute Myocardial Ischemia

The purpose of study is to investigate the effect of vagal nerve stimulation (VNS) on ventricular repolarization period (VRP) and repolarization dispersion in different zone with left ventricular branch(LVB) occlusion and the influence of VNS on ischemic arrhythmia.Methods:To ligate left ventricular branch(LVB) to make acute myocardial ischemia model of rabbit.To dissociate,ligate and cut bilateral cervix vagi nerves (CVN).To stimulate peripheric part of CVN.QT interval in epicardiogram,50% and 90% action potential duration(APD 50 and APD 90 )by glass microelectrode technique as VRP,were measured in different zone with and without LVB occlusion.Ventricular vulnerable period(VVP) was tested with and without VNS and LVB occlusion.Results:QT interval,APD 90 and APD 50 were decreased with VNS ( P <0.05) in different zone of rabbit before LVB occlusion.With LVB occlusion,QT interval,APD 90 and APD 50 were different in ischemic and non ischemic zone ( P <0.05);while with VNS,the differences of QT interval,APD 90 and APD 50 reduced sigficantly.Conclusion:The ventricular repolarization dispersion decreased with VNS after myocardial ischemia so that enhances the difficulty of reentry.Therefore,VVP and chances of ischemic arrhythmia decreased.