Kuan Yee Han, Nguyen Vinh-Tan, Kabinejadian Foad, Leo Hwa Liang
J Heart Valve Dis. 2015 May;24(3):393-403.
The trileaflet heart valve is a more desirable mechanical heart valve due to its similarity to native heart valves, which produce a central blood flow with decreased blood flow disturbance. There are, however, many challenges and difficulties in designing a trileaflet valve, mainly due to a greater number of moving mechanical parts.
The flow profiles through a bileaflet mechanical heart valve (BMHV) and a trileaflet mechanical heart valve (TMHV) were compared at downstream regions. Geometric models of a 29 mm St. Jude Medical BMHV and a TMHV were used and positioned at the anatomic position in a curved aortic downstream geometry. Three-dimensional numerical simulations for both types of mechanical heart valve were performed under normal physiological pulsatile flow conditions. Flow profiles were studied under three different implantation locations at Z = 1D (D = 29 mm inlet diameter), 2D and 4D along the aorta centerline during peak systole.
The simulation results showed different flow fields at the downstream positions at Z = 1D and 2D. The leaflets of the BMHV obstructed the flow, while the TMHV allowed a central orifice flow which resulted in a more physiological flow profile. Further downstream, at Z = 4D, the flow fields shared similarities in terms of the flow profile and velocity magnitude.
The findings of this study may help to further improve the development of the TMHV.
三叶式心脏瓣膜因其与天然心脏瓣膜相似，能产生中心血流且血流紊乱减少，是一种更理想的机械心脏瓣膜。然而，设计三叶式瓣膜存在诸多挑战和困难，主要原因是其运动的机械部件数量更多。
在下游区域比较双叶式机械心脏瓣膜（BMHV）和三叶式机械心脏瓣膜（TMHV）的血流剖面。使用29毫米圣犹达医疗双叶式机械心脏瓣膜和三叶式机械心脏瓣膜的几何模型，并将其置于弯曲主动脉下游几何结构的解剖位置。在正常生理脉动流条件下对两种类型的机械心脏瓣膜进行三维数值模拟。在收缩期峰值时，沿着主动脉中心线在Z = 1D（D = 29毫米入口直径）、2D和4D三个不同植入位置研究血流剖面。
模拟结果显示在Z = 1D和2D的下游位置存在不同的流场。双叶式机械心脏瓣膜的瓣叶阻碍血流，而三叶式机械心脏瓣膜允许中心孔口血流，从而产生更符合生理的血流剖面。在更下游的Z = 4D处，流场在血流剖面和速度大小方面具有相似性。
本研究结果可能有助于进一步改进三叶式机械心脏瓣膜的研发。
