CURRENT FLOW PATTERNS IN TWO-DIMENSIONAL ANISOTROPIC BISYNCYTIA WITH NORMAL AND EXTREME CONDUCTIVITIES
CURRENT FLOW PATTERNS IN TWO-DIMENSIONAL ANISOTROPIC BISYNCYTIA WITH NORMAL AND EXTREME CONDUCTIVITIES
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DOI：
10.1016/s0006-3495(84)84193-4
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发表时间：
1984-01-01
影响因子：
3.4
通讯作者：
BARR, RC
中科院分区：
文献类型：
--
作者：
PLONSEY, R;BARR, RC
心脏组织已被证明在细胞内和细胞外（间质）域中起电合胞体的作用。现有的实验证据和定性直觉的复杂的解剖结构支持的观点，不同的（平均）电导率的特点是沿着纤维轴的方向，与跨纤维方向相比，在细胞内以及细胞外空间。本报告分析了2维各向异性的心脏组织，并实现了积分方程，直接从给定的跨膜电压的描述中找到细胞内和细胞外电位，纵向电流和膜电流。这些数学结果被用作现实（虽然理想化）的二维心脏组织的数值模型的基础。基于数值模型的计算机模拟被执行的电导率模式，包括标称正常的心室肌电导率和具有沿着x的细胞内或细胞外电导率比的模式，沿着y的倒数。计算结果是基于假设一个简单的空间分布的Vn，通常是一个圆形的等时线，隔离的影响，电流和电位的电导率的变化，而不混淆传播差异。这些结果与许多明确或隐含地假设各向同性电导率或沿沿着x和y的相等电导率比的报告相反。具体地，利用倒数电导率，大多数电流在包含几毫米的大回路中流动，但仅在组织的静止（极化）区域中流动;此外，给定的电流流动路径通常包括4个或更多个而不是2个跨膜偏移。名义上正常的结果显示局部电流主要只有2个跨膜通道;然而，二维各向异性双胞体中的大部分电流流动模式可能具有与一维链完全不同的定性和定量特性。
Cardiac tissue has been shown to function as an electrical syncytium in both intracellular and extracellular (interstitial) domains. Available experimental evidence and qualitative intuition about the complex anatomical structure support the viewpoint that different (average) conductivities are characteristic of the direction along the fiber axis, as compared with the cross-fiber direction, in intracellular as well as extracellular space. This report analyzes 2-dimensional anisotropic cardiac tissue and achieves integral equations for finding intracellular and extracellular potentials, longitudinal currents and membrane currents directly from a given description of the transmembrane voltage. These mathematical results are used as a basis for a numerical model of realistic (though idealized) 2-dimensional cardiac tissue. A computer simulation based on the numerical model was executed for conductivity patterns including nominally normal ventricular muscle conductivities and a pattern having the intracellular or extracellular conductivity ratio along x, the reciprocal of that along y. The computed results are based on assuming a simple spatial distribution for Vn, usually a circular isochrone, to isolate the effects on currents and potentials of variations in conductivities without confounding propagation differences. The results are in contrast to the many reports that explicitly or implicitly assume isotropic conductivity or equal conductivity ratios along x and y. Specifically, with reciprocal conductivities, most current flows in large loops encompassing several millimeters, but only in the resting (polarized) region of the tissue; further, a given current flow path often includes 4 or more rather than 2 transmembrane excursions. The nominally normal results showed local currents predominantly with only 2 transmembrane passages; however, a substantial part of the current flow patterns in 2-dimensional anisotropic bisyncytia may have qualitative as well as quantitative properties entirely different from those of 1-dimensional strands.