2相早期后除极对心肌电折返稳定性的影响  

Effects of Phase-2 Early Afterdepolarization on the Stabilities of Electrical Reentry

作　　者：张虹[1] 赵丹[1] 贺锐睿 黄欣[2] 樊亚萍[3] 

机构地区：[1]西安交通大学电气工程学院,西安710049 [2]西安交通大学第一附属医院心内科,西安710061 [3]西安交通大学理学院,西安710049

出　　处：《中国生物医学工程学报》2015年第1期24-29,共6页Chinese Journal of Biomedical Engineering

基　　金：国家自然科学基金(81271661);教育部回国留学基金(第40批);中央高校基本科研业务费专项资金(xjj2011087)

摘　　要：心肌细胞在2相复极期发生的膜电位振荡称为2相早期后除极(EAD)。单细胞实验证实了2相EAD的存在,但对其在组织中的特点以及是否影响电稳定性和室速/室颤行为尚缺乏足够的认识。本研究基于Luo-Rudy单细胞离子通道数学模型,通过控制Ca2+电流最大电导和K+电流门控变量得到2相EAD。在此基础上构建具有局部EAD特征,包含400×400个细胞的二维非均质组织。采用算子分裂方法求解组织模型,利用垂直场法诱导电折返,形成螺旋波,观察EAD对螺旋波动力学斑图稳定性的影响。结果表明,2相EAD具有促使螺旋波失稳,发生断裂和破碎的作用,但是这种转化是否发生则与EAD区域面积和所在位置有关,中心处大小为20×20的EAD区域易于促使螺旋波的碎裂。多个EAD区域的存在可加剧螺旋波的失稳和破碎的程度,形成更为混沌的电压斑图。局部2相EAD引起的不应期离散性是促使螺旋波破碎的主要机制。因此,2相EAD具有促使室速向室颤转化的作用,临床上应预防2相EAD的出现,以降低由此引发的恶性心律失常。The voltage oscillations at the phase 2 repolarization of an action potential are called the phase-2 early afterdepolarizations （EADs）. Most isolated myocyte studies have recorded phase-2 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 Luo-Rudy ionic mathematical model, the phase-2 EADs were produced by properly matching the maximum conductance of Ca ionic channel and the time constant of K gating. A two-dimensional inhomogeneous tissue model including 400 x 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 x 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, phase-2 EAD could promote the degeneration of VT toVF. In the clinic setting, the inhibition of phase-2 EADs was necessary for the prevention and suppression of the occurrence of VF.

关 键 词：早期后除极 折返 螺旋波 电压斑图 动作电位模型 

分 类 号：R318.08[医药卫生—生物医学工程]