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.