Effects of Phase 2 Early Afterdepolarization on the Stabilities of Electrical Reentry
1 School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2 Cardiology Department, the First Hospital, Xi’an Jiaotong University, Xi’an 710061, China
3 School of Science, Xi’an Jiaotong University, Xi’an 710049, China
Abstract The voltage oscillations at the phase 2 repolarization of an action potential are called the phase2 early afterdepolarizations (EADs). Most isolated myocyte studies have recorded phase2 EADs, but their characteristics in the tissue and whether they affect the electrical stability and behaviors of the ventricular tachycardia (VT) and ventricular fibrillation (VF) are still not clear. In this paper, based on the single cell LuoRudy ionic mathematical model, the phase2 EADs were produced by properly matching the maximum conductance of Ca2+ ionic channel and the time constant of K+ gating. A two dimensional inhomogeneous tissue model including 400×400 cells was then developed by putting the local EAD regions inside. The operator splitting technique was used to integrate the tissue model. The cross field method was utilized to induce a reentry and formed a spiral wave. The effects of EAD on the dynamics of spiral wave patterns were observed. Results showed that phase-2 EAD could promote the destabilization of the spiral wave and its breakup, but whether this transition occurred was dependent on the size and location of the EADs. A 20×20 EAD zone in the center was easy to result in breakup of the spiral wave. Multiple EAD regions could aggravate the destabilization, leading to the more chaotic wave patterns. The refractory period dispersion was suggested to be the main mechanism of the wave breakup. Therefore, phase2 EAD could promote the degeneration of VT to VF. In the clinic setting, the inhibition of phase2 EADs was necessary for the prevention and suppression of the occurrence of VF.
Zhang Hong1* Zhao Dan1 He Ruirui1 Huang Xin2 Fan Yaping3. Effects of Phase 2 Early Afterdepolarization on the Stabilities of Electrical Reentry[J]. journal1, 2015, 34(1): 24-29.
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