Analysis of Excitation Conduction in the Heart and the Reconstruction of Electrocardiogram Using Ionic -channel Models

心脏兴奋传导分析及离子通道模型心电图重建

基本信息

批准号：
60490011
负责人：
SUZUKI Ryoji
金额：
$ 4.61万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60490011/
关键词：
Excitation Conduction Ionic-channel Model Gap-junction Pacemaker AV conduction Reconstruction of ECG GEAR法

项目摘要

The normal excitation and conduction in the heart are maintained by the coordination between the dynamics of ionic conductance of each cell and the electrical coupling between cells.(1) Using a spatially-discrete model of conduction of excitation, we examined functional roles of these two factors. The model is one-dimensional and is composed of five kinds of myocardial cells. We first determined quantitatively the coupling coefficients from the apparent space constants, then found the conditions of cell number and the couping coefficients for the pacemaker activities of SA-node. We also investigated the very slow conduction in AV-node and revealed that the weak coupling coefficients between cells in AV-node has the strongest effect.(2) A digital computer model was constructed for the simulation of the electrocardiogram during ventricular activation and repolarization. The part of the ventricular septum and the left ventricula free wall of the heart were represented by a two dimensional array of 730 units. Ionic current models were used to determine the spatial distribution of the electric activities of these units at each instant of time during simulated cardiac cycle. In order to reconstruct the electrocardiogram, the model was expanded three dimensionally with equipotential assumption along the third axis and then the surface potentials were calculated using solid angle method. ECG for normal subject was well reconstructed. ECGs for hyper-and hypokalemia were also reconstructed by modifying the related ionic current dynamics. We used Euler-method for numerical integration through this project. However, in order to accomodate the improvement of ionic current model, we adopted GEAR method which has a power to solve so-called "stiff" differential equation.

心脏中的正常兴奋和传导是通过每个细胞的离子电导动力学和细胞之间的电耦合之间的协调来维持的。（1）使用兴奋传导的空间离散模型，我们检查了这两个细胞的功能作用因素。该模型是一维的，由五种心肌细胞组成。我们首先根据表观空间常数定量确定了耦合系数，然后找到了SA节点起搏器活动的细胞数条件和耦合系数。我们还研究了房室结中非常慢的传导，发现房室结细胞之间的弱耦合系数具有最强的影响。(2)建立了数字计算机模型来模拟心室激活和复极过程中的心电图。心脏的室间隔和左心室游离壁部分由 730 个单元的二维阵列表示。使用离子电流模型来确定这些单元在模拟心动周期期间每个时刻的电活动的空间分布。为了重建心电图，将模型沿第三轴等电位假设进行三维展开，然后使用立体角法计算表面电位。正常受试者的心电图重建良好。高钾血症和低钾血症的心电图也通过修改相关的离子电流动力学来重建。我们在这个项目中使用欧拉方法进行数值积分。然而，为了适应离子电流模型的改进，我们采用了能够求解所谓“刚性”微分方程的GEAR方法。