Effects of early afterdepolarizations on ventricular tachycardia in human heart

Experimental studies suggest EADs may occur at rapid heart rates as a consequence of tachyarrhythmias. The aim of this study was to investigate the interaction between EAD and rapid reentrant excitation waves and assess its effects with electrocardiogram (ECG).The simulation results indicated that, at the cellular level, reduced repolarization reserve contributed to action potential duration (APD) prolongation (ENDO: 302ms vs. 402ms, MIDDLE: 414ms vs.>1000ms, EPI: 298ms vs. 397ms) and genesis of EADs only in MIDDLE cells. In the 3D model, EADs caused drift of rapid rotors. Multiple focal excitations arising from EADs kept regeneration of reentrant excitation waves by breaking excitation wave fronts. ECGs presented periodic features with stable reentry in control condition, but degenerated into irregular and complex patterns in EADs condition. The simulation results demonstrate that MIDDLE cells are prone to genesis of EADs at rapid heart rates, which plays an important role in degenerating ventricular tachycardia into ventricular fibrillation.