跨壁复极离散在多形性折返性室性心动过速发生中的作用

目的探讨跨壁复极离散与室性心律失常发生的关系。方法以冠状动脉灌注兔左室楔形组织块为研究对象,对标本施加刺激基础周长分别为500,1000,2000ms的S1刺激,记录内、外膜侧心肌细胞动作电位和跨壁心电图,测量QT间期、时间易损窗及Tp-e/QT值。每10个S1刺激后施加期前S2刺激,S1S2耦联间期以1ms递增,以测量引起单向传导阻滞的时间易损窗。结果时间易损窗与QT间期呈正相关;Tp-e/QT比值在0.10～0.14之间无多形性室性心动过速(PVT)发生,当Tp-e/QT比值大于0.15,可引起PVT发生,而该比值在0.18～0.21时,无论S2刺激施加于内膜侧还是外膜侧,均可引起PVT。结论随着QT间期的延长时间易损窗增大;Tp-e/QT比值越大,室性心律失常越易发生。

Role of transmural dispersion of repolarization in the genesis of polymorphic reentrant ventricular arrhythmias

Objective To explore the relationship between transmural dispersion of repolarization and ventricular arrhythmias.Methods The arterially perfused rabbit left ventricular wedge preparations were used in this experiment.Double threshold current were delivered with basic cycle length 500,1000,and 2000ms(S1).The transmembrane action potentials from epicardial and endocardial sites as well as transmural electrocardiogram(ECG) were recorded simultaneously.Then,the QT interval,the time vulnerable-window(VWtime) and the Tp-e/QT ratio were measured.Each driving train of S1 consisted of 10 beats.In order to test the VWtime for unidirectional conduction block,the S1S2 coupling interval was progressively increased with 1ms increment.Results The VWtime was positively proportional to QT interval.And polymorphic ventricular tachycardia(PVT) could not be induced when the Tp-e/QT ratio was 0.10～0.14.However,as the ratio was above 0.15,PVT could be initiated.If the ratio was above 0.18～0.21,no matter the S2 delivered from endocardial or epicardial myocytes,PVT could be induced very easily.Conclusion The VWtime is increased markedly with the QT interval prolongation and the incidence of ventricular arrhythmias increased as the Tp-e/QT ratio enhanced.