人工生物瓣膜血流动力学行为的有限元分析

Finite Element Analysis for Hemodynamic Behavior of Bioprosthetic Heart Valves

使用脉动工作站检测生物瓣膜在近似生理条件下的血流动力学特性,结合有限元分析研究了生物瓣膜在心动周期过程中的微观应力和应变情况,寻求一种快速评价人工心脏瓣膜结构—力学性能间关系的方法。结果表明,生物瓣膜(Edwards #2625)在体外脉动流检测条件下的平均跨瓣压差为10.8 mmHg、有效开口面积为2.0 cm^2、返流百分比为8.4%,均符合ISO-5840国际检测标准。生物瓣膜有限元模拟结果揭示其在收缩期最大主应力达到425 kPa,应力集中在弯曲变形严重的腹部以及瓣叶缝合边;舒张期最大主应力为1.46 MPa,应力集中在瓣叶缝合边的两侧。在脉动检测的不同时间点,瓣膜有限元模型开口面积均与实验条件下样品的开口面积近似,证明了有限元模拟结果的可靠性。本文提出的体外脉动流检测实验与有限元仿真计算相结合的方法,为评价人工心脏瓣膜的结构—力学性能间关系提供一种高效可靠的途径。

The hemodynamic property in physiological saline solution of bioprosthetic heart valve was measured under the physiological considition using a pulse duplicator, accordingly, based on the above measured data, the stress and strain distribution on heart valve leaflets was analized by means of finite element analysis（FEA） at the microscopic level over a cardiac cycle, so that to assess the relationships between the structure and mechanical properties of the bioprosthetic heart valve. The measured parameters of the bioprosthetic heart valve（Edwards #2625） are as follows： the mean transvalvular pressure ~10.8 mmHg, the effective opening area ~2.0 cm^2 and the regurgitant fraction ~8.4%, which all meet the requirements of the ISO-5840 standard; The FE simulation results show that the maximum principal stresse was 425 kPa during the systolic phase, the major stress concentration was found on the belly and the suture edge of the leaflet, which underwent severe bending deformation. The maximum principal stresse was 1.46 MPa during the diastolic phase, and the major stress concentration was found on the two sides of the suture of the leaflet; The valvular open areas at different time points were close to those measured during experimental tests, indicating the relibility of the FEA method. Thus, the combination of the simulation test and and the finite element simulation calculation may be considered as an efficient and relible stratigy to evaluate the relationships between the structure and mechanical properties of bioprosthetic heat valve.