Construction of a Computer Model to Investigate Sawtooth Effects in the Purkinje System
Construction of a Computer Model to Investigate Sawtooth Effects in the Purkinje System
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DOI：
10.1109/tbme.2006.888817
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发表时间：
2007-02
影响因子：
4.6
通讯作者：
E. Vigmond;C. Clements
中科院分区：
文献类型：
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作者：
E. Vigmond;C. Clements
锯齿效应是指暴露于外源电场时，心肌细胞的一端如何去极化，而另一端如何超极化。尽管是假设，但尚未在组织中观察到。浦肯野系统是位于心脏心内膜表面的一维 (1-D) 电缆状系统，是这种现象表现的最明显的候选者。本文描述了电场对浦肯野系统影响的计算机建模研究。从三维几何现实、有限元、心室描述开始，构建了遵循一般生理原理的浦肯野系统。浦肯野的电活动是通过使用一维立方 Hermite 有限元来描述的。这样的公式允许对浦肯野肌细胞连接处的负载效应进行精确建模，并保持系统的离散性质。在多种条件下计算了一条浦肯野细胞对除颤强度冲击的反应。此外，还说明了孤立浦肯野网络的响应。结果表明，浦肯野系统的几何形状是系统远场激励的最大决定因素。给定合理生理范围内的参数，浦肯野系统的一维性质可能会导致锯齿电位，该锯齿电位足够大以影响激发。因此，浦肯野系统能够影响除颤过程，并需要进一步的实验来阐明其作用
The sawtooth effect refers to how one end of a cardiac cell is depolarized, while the opposite end is hyperpolarized, upon exposure to an exogenous electric field. Although hypothesized, it has not been observed in tissue. The Purkinje system is a one-dimensional (1-D) cable-like system residing on the endocardial surface of the heart and is the most obvious candidate for the manifestation of this phenomenon. This paper describes a computer modeling study of the effect of electric fields on the Purkinje system. Starting with a three-dimensional geometrically realistic, finite element, ventricular description, a Purkinje system is constructed which adheres to general physiological principles. Electrical activity in the Purkinje is described by use of 1-D cubic Hermite finite elements. Such a formulation allows for accurate modeling of loading effects at the Purkinje-myocyte junctions, and for preserving the discrete nature of the system. The response of a strand of Purkinje cells to defibrillation strength shocks is computed under several conditions. Also, the response of the isolated Purkinje network is illustrated. Results indicate that the geometry of the Purkinje system is the greatest determinant for far field excitation of the system. Given parameters within the plausible physiological range, the 1-D nature of the Purkinje system may lead to sawtooth potentials which are large enough to affect excitation. Thus, the Purkinje system is capable of affecting the defibrillation process, and warrants further experimentation to elucidate its role