Effect of aspect ratios on stress and strain of a multilayer model for the left ventricle

Abstract

Abasic understanding of the heart behavior assists in the accuratediagnosis of heart disease,which is the leadingcause of death in Thailand. The mechanical behaviors of the heart can be ideally explained by strain and stress. This work numericallyand analytically describedthree layers of the heart wall ina computational model, while previous studies onlyconsidered the myocardium,which is a muscular layer.Moreover, theshape of the left ventricle (LV) varies among individuals. The influence of the LV shape, as assumed to be a truncated ellipse, was considered by varying the short-to-long-axis and wall-to-cavity-volume ratios to investigate strain and stress in the radial, circumferential and longitudinal directionsduring a passive filling with blood using a continuum approach. For verification, the model was compared to other research work by defining the wall-to-cavity-volume and short-to-long-axis ratios as well by as fiber distribution. The results showed that an increasingshort-to-long-axis ratio obviously resulted in decreasedoverall strains and stresses. Whereas, increasing thewall-to-cavity-volume ratio slightly decreased radial contraction as well ascircumferential and longitudinal expansion. The fiber strains of the linear fiber distribution corresponded well with previous work atahigh longitudinal curvature.

Keywords

• Computational model
• Endocardium
• Epicardium
• Left-ventricular shape
• Stress
• Strain