氯化铯所致在体家兔早期后除极及复极离散化在多形性室速中的意义

目的和方法：本文采用浮置式玻璃微电极记录心肌细胞跨膜动作电位（ＴＡＰ）技术，研究氯化铯（ＣｓＣｌ）诱发的在体家兔早期后除极（ＥＡＤ）和触发电活动（ＴＡ）以及复极离散化程度。结果：ＣｓＣｌ诱发高膜电位水平的ＥＡＤ的配对间期（ＣＩ）较长，其振幅和ＣＩ随刺激周期（ＣＬ）的增加而增加，此种ＥＡＤ及ＴＡ可导致室性早搏（ＶＰＢ）和多形性室速，ＥＡＤ的ＣＩ和ＶＰＢ的ＣＩ几乎相等（ｒ＝０．８９）。ＣｓＣｌ诱发低膜电位水平的ＥＡＤ的ＣＩ较短，其振幅和ＣＩ不随ＣＬ的改变而发生变化，此种ＥＡＤ及ＴＡ可导致短ＣＩ的插入性ＶＰＢ。ＣｓＣｌ还可增加心壁中的不同区域之间的复极离散化趋势，其原因是由于动作电位时程的差异的增加。结论：为ＣｓＣｌ导致的室性心动过速系由于心动过缓依赖性的ＥＡＤ及ＴＡ所致的学说提供了直接证据。明显的动作电位时程的差异可能在心动过速的维持过程中发挥作用。

The effect of early afterdepolarizations and dispersion of repolarization induced by cesium chloride on polymorphic ventricular tachycardia in rabbits in vivo

AIM and METHODS:Cesium chloride (CsCl) induced early afterdepolarizations (EAD), triggered activity (TA) and dispersion of repolarization in rabbit heart in vivo were studied by using floating glass microelectrode to record transmembrane action potentials (TAP).RESULTS:The coupling interval (CI) of EAD with higher membrane potentials (MP) induced by CsCl was longer the amplitude and CI of this kind EAD increased as drive cycle length increased. These EAD and TA could lead to ventricular premature beats (VPB) and polymorphic ventricular tachycardias. The EAD-CI and the VPB-CI were nearly identical ( r= 0.89). CsCl induced EAD with lower MP occured at shorter CI, the amplitude and CI of this kind EAD did not change with drive length.These EAD and TA could result in insertive VPBs with shorter CI. CsCl could also increase the dispersion of repolarization between septal area and free wall of left ventricle,which was due to increased difference in action potential durations. CONCLUSION:The present study provides evidence in support of the hypothesis that CsCl induced ventricular tachyarrhythmias are due to bradycardia dependent EAD and TA. The large action poential duration difference may play a crucial role in the process of maintenance of arrhythmia.