心电激励下的人体左心室力学响应分析

Analysis of the mechanical response of human left ventricls subjected to the active force

人体心脏通过电兴奋引起的心肌收缩实现泵血功能 ,而心肌的力学特性高度依赖于肌纤维结构。本文根据肌纤维旋向和复合材料理论以及电生理心脏模型建立了左心室的有限元机械模型 ,仿真研究了左心室在心电兴奋力作用下的力学响应。结果表明左心室的收缩过程是十分复杂的 ,包括轴向和径向的收缩及绕长轴的不同程度的旋转扭曲。从总体趋势上看 ,心尖处变形最为严重。此外 ,仿真结果还表明 ,心壁应力分布不均匀 ,从内壁到外壁有所减少 ;在心尖和心底部应力较大 ,其中内壁心尖处应力最大。这些结果说明了心脏的力学特性与心肌纤维结构、左心室的几何形状以及电兴奋刺激密切相关。作者将本文的仿真结果与医学图像及其它模型进行了对比分析 。

The human heart pumps blood via contraction of myocardial muscleand the mechanical properties of the muscle depend highly on its fibrous structure. Considering the fiber orientation, a three-dimensional finite element mechanical model of left ventricle is constructed, based on composite theory and an electric model of human heart. The mechanical response of the left ventricle subjected to the active force is simulated. The simulation results show that the left ventricle contraction is very complicated, it includes axial shortening, radial contraction, basal contraction and twisting around the long axis at different degree, and among these deformations, the apical contraction is the strongest. In addition, the stress distribution on the left ventricle wall is not uniform, and it reduces from the endocardium to the epicardium. The stress on the apex and base of left ventricle is much greater, and the greatest exists on the apex of endocardium. These results show that the cardiomechanics is sensitive to the myocardial fibrous structure, the left ventricle geometric shape and electric active stimulus. The simulation results are compared with the solutions obtained from corresponding medical images and those comes from other models,it proves that the given model can be used to study the mechanical function of the left ventricle.