目的 设计一种附起旋功能的双叶机械瓣,通过改善其血流状态预防术后并发症。 方法 基于导流片式局部起旋器结构,将瓣叶作为导流叶片,并定义瓣叶包角以探究具有较优血流动力学特性的瓣膜构型。 应用有限元分析软件,对心缩期峰值流量状态下的主动脉流场进行仿真,螺旋性、壁面切应力分布等血流动力学特征。 结果 相较于对照瓣膜,起旋瓣具有更大的有效开口面积与更小的跨瓣压差,一定瓣叶包角范围内的起旋瓣能促进右手螺旋流的生成,并使血流趋向流道中心;起旋瓣壁面切应力分布也更加均匀,具有较少的低应力区与高应力区,壁面切应力峰值也相对较小。 针对研究中的主动脉模型,具有最优血流动力学特性的瓣叶包角为 15° ~ 20°。 结论 该新型人工主动脉瓣能调节主动脉内的血流特征,降低主动脉瓣置换术引起主动脉扩张与主动脉瘤的风险,对未来机械瓣构型设计具有指导意义。

Objective To design a bileaflet mechanical valve with the function of generating helical flow, so as to prevent postoperative complications by improving its hemodynamic characteristics. Methods Based on the structure of guiding-vane type spiral flow generator, the leaflets were used as the guiding vane and the leaflet wrap angle was defined to explore the valve configuration with better hemodynamic performance. The finite element analysis software was used to simulate the aortic flow field under the state of peak systolic flow. Then the flow velocity, effective orifice area (EOA), flow asymmetry and helicity, wall shear stress (WSS) distribution and other hemodynamic characteristics in each group were compared. Results Compared with the control valve, the helical-flow generated valve had a larger EOA and a smaller pressure difference across the valve. The helical-flow generated valve with leaflets within a certain wrap angle could promote the generation of right-handed helical flow and make the blood flow approach the center of the channel. The WSS distribution was more uniform and the peak WSS was relatively smaller in the helical-flow generated valve, with fewer low-stress and high-stress areas. For the aortic model in this study, the leaflet wrap angle for optimal hemodynamic performance was 15°-20°. Conclusions This novel artificial aortic valve can adjust blood flow characteristics in the aorta, reduce the risk of aortic dilatation and aortic aneurysm caused by aortic valve replacement, and it has guiding significance for configuration design of mechanical valve in the future.

国家自然科学基金项目(32071311, 31870940, 11872096, 12172033),北京市自然科学基金项目(7222308)