Chandran K B, Kim S H, Han G
Department of Biomedical and Mechanical Engineering, University of Iowa, Iowa City 52242.
J Biomech. 1991;24(6):385-95. doi: 10.1016/0021-9290(91)90027-k.
In this paper, a finite element analysis of the stress distribution on the cusps of a polyurethane trileaflet heart valve prosthesis in the closed position is presented. The geometry of the valve was modified from a relationship proposed by Ghista and Reul (J. Biomechanics 10, 313-324, 1977). The effects of variations in stent height, leaflet thickness and coaptation area on the stress distribution were also analyzed. Analyses were performed with both rigid and flexible stents for the trileaflet valve in order to delineate the effect of stent flexibility on the leaflet stress distribution. The results showed that regions of stress concentration were present near the commissural attachment similar to those predicted with the bioprostheses. The stresses on the leaflets were reduced by increasing the stent height with both rigid and flexible stents. Selectively increasing the leaflet thickness near the commissures and also increasing the coaptation area did not prove to reduce the leaflet stresses when the stent flexibility was taken into account. The possible effect of high stresses on the structural integrity of polyurethane leaflets and its relationship with calcification is yet to be investigated.
本文介绍了对处于关闭位置的聚氨酯三叶心脏瓣膜假体瓣尖应力分布的有限元分析。瓣膜的几何形状是根据吉斯塔和勒尔（《生物力学杂志》10，313 - 324，1977）提出的关系进行修改的。还分析了支架高度、瓣叶厚度和贴合面积变化对应力分布的影响。为了描述支架柔韧性对瓣叶应力分布的影响，对三叶瓣膜使用刚性和柔性支架进行了分析。结果表明，在连合附着附近存在应力集中区域，类似于生物假体所预测的区域。使用刚性和柔性支架时，通过增加支架高度可降低瓣叶上的应力。考虑到支架柔韧性时，选择性增加连合处附近的瓣叶厚度以及增加贴合面积并未证明可降低瓣叶应力。高应力对聚氨酯瓣叶结构完整性的可能影响及其与钙化的关系尚待研究。
