摘要
目的通过无支架心包二尖瓣与有架三叶生物瓣对比,利用有限元法计算,观察在左心室舒张期瞬时跨瓣压差作用下的瓣叶静态应力分布。方法采用八节点曲线薄壳单元,考虑大应变以及瓣叶闭合过程的接触,应用Newton-Raphson方法求解有限元非线性方程。结果瓣膜开启状态下两种瓣膜应力水平均不高。在峰值跨瓣压差15.96kPa作用下,无架心包二尖瓣第一主应力分布均匀,无明显应力集中,平均第一主应力为0.040～0.149MPa;有架三叶瓣在临床上易发生撕裂的部位明显应力集中,最大第一主应力为2.352MPa,平均第一主应力为0.223～0.724MPa,明显高于无架心包二尖瓣。结论(1)对于几何曲面形状不规则,高度接触的无支架心包二尖瓣,首次采用有限元方法进行应力计算是有效可行的;(2)本研究的有支架心包三叶瓣有限元模型得到的应力分布与临床结果一致;(3)无架心包二尖瓣较有架心包三叶瓣应力分布明显合理,有益于防止瓣叶撕裂和钙化,延长寿命。
Objective A nonlinear finite element model was used for comparing stentless？ pericardial mitral valve and stented？ pericardial three-leaflet valve to identify their static stress distribution at valve open and closed position during cardiac cycle. Methods A finite element code was developed ？ by using the 8-node super-parameter nonlinear shells and the Newton-Raphson method. The load was the mean transvalvular？ pressure gradient of the tested valves at open and closed position, and the stress was determined. Results At an internal pressure of 120mmHg in mitral valve closed position, stentless？ pericardial mitral valve showed more reasonable stress distribution than that of stented？ pericardial three-leaflet valve. The maximum first principle normal stress, of which the area corresponded with the perforation point, was 2.352MPa in stented pericardial three-leaflet valve. The average first principle normal stress of stented pericardial three-leaflet valve（0.223-0.724MPa） was higher than that of stentless pericardial mitral valve （0.040-0.149Mpa）. Conclusion A finite element analysis of the quadrileaflet？ stenUess mitral valve, whose geometry and action was nonlinear, was effective and feasible. It shows that for the stenUess pedcardial mitral valve, the absence of the stent resulted in reduced stress on the leaflets. It could bepostulated that this will lead to a decrease of tears, perforation and calcification, which may result in an improved long-term behavior.
出处
《医用生物力学》
EI
CAS
CSCD
2006年第1期43-48,共6页
Journal of Medical Biomechanics
关键词
无支架
生物瓣
心脏
应力
有限元分析
Stentless
Bioprosthetic heart valve
Stress
Finite element analysis
