[Insight into the mechanism of torsade de pointes (TDP) induced by cesium chloride]

Standard intracellular potential recording technique was used in isolated guinea pig ventricular muscle and monophasic action potential (MAP) recording technique was performed on both the epicardium and endocardium of dog hearts in vivo. The results showed that CsCl lengthened action potential durations of ventricular muscle as well as QT intervals of dog hearts. The incidence of early after depolarization (EAD) induction was 71.4%. Ventricular tachycardia induced by CsCl manifested as typical TdP in 44.4% with EAD shown on epicardial MAP recording. This suggested that EAD and triggered activity might be an important mechanism of TdP. As verapamil could depress the induction of EAD, we believe that Ca++ inward currents was responsible for the induction of EAD and TdP by CsCl.