PROPAGATION OF EXCITATION IN IDEALIZED ANISOTROPIC TWO-DIMENSIONAL TISSUE
PROPAGATION OF EXCITATION IN IDEALIZED ANISOTROPIC TWO-DIMENSIONAL TISSUE
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DOI：
10.1016/s0006-3495(84)84268-x
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发表时间：
1984-01-01
影响因子：
3.4
通讯作者：
PLONSEY, R
中科院分区：
文献类型：
--
作者：
BARR, RC;PLONSEY, R
本文对二维各向异性心脏组织的传播过程进行了模拟，假设组织结构为Hodgin-Huxley膜，在各向异性介质的内部和外部都服从欧姆定律。膜电流被发现的积分表达式，涉及Vm [跨膜电压]加权的函数的距离的部分空间导数。使用仅检查在每个时刻经历激励的组织部分的算法来计算在单个中心部位处激励后作为时间的函数的Vm的数值解;因此，所需的计算的数量减少到大的但可实现的数量。显示了4个电导率值的几种组合的结果：对于各向同性组织，如预期的那样，激励以圆形传播。对于具有标称正常心室传导率的组织，兴奋以接近椭圆的模式传播。在电导率倒数的情况下，等时线近似于菱形，与穆勒和马尔金的理论预测相冲突;计算得出的动作电位脚的时间常数在沿着轴的位置与沿沿着对角线的位置之间不同，尽管膜的性质在任何地方都是相同的。在刺激之后，传播速度改变了几毫秒。从一维的知名研究中预期的模式并不总是发生在二维中，差异的大小从各向同性电导率的零到倒数电导率的相当大。
A simulation of propagation for anisotropic 2-dimensional cardiac tissue is reported on. The tissue structure assumed was that of a Hodgin-Huxley membrane separating inside and outside anisotropic media, obeying Ohm''s law in each case. Membrane current was found by an integral expression involving partial spatial derivatives of Vm [transmembrane voltage] weighted by a function of distance. Numerical solutions for Vm as a function of time following excitation at a single central site were computed using an algorithm that examined only the portion of the tissue undergoing excitation at each moment; thereby, the number of calculations required was reduced to a large but achievable number. Results are shown for several combinations of the 4 conductivity values: with isotropic tissue, excitation spread in circles, as expected. With tissue having nominally normal ventricular conductivities, excitation spread in patterns close to ellipses. With reciprocal conductivities, isochrones approximated a diamond shape, and were in conflict with the theoretical predictions of Muler and Markin; the time constant of the foot of the action potentials, as computed, varied between sites along axes as compared with sites along the diagonals, even though membrane properties were identical everywhere. Velocity of propagation changed for several milliseconds following the stimulus. Patterns that would have been expected from well-known studies in 1 dimension did not always occur in 2 dimensions, with the magnitude of the difference varying from nil for isotropic conductivities to quite large for reciprocal conductivities.