Ma Xinrui, Gao Bin, Tao Liang, Ding Jinli, Li Shu, Qiao Aike, Chang Yu
Faculty of Environment and Life, Beijing University of Technology, Beijing, China.
Department of Cardiovascular Surgery, Wuhan Asia Heart Hospital, Wuhan, China.
J Thorac Dis. 2022 May;14(5):1515-1525. doi: 10.21037/jtd-22-425.
Although aortic valve reconstruction has become an alternative treatment for aortic valve disease, the design of the geometric parameters of the reconstructed leaflet still mainly depends on the experience of doctors. The present study investigates the effects of the height of the leaflets on the performance and biomechanical states of the reconstructed aortic valve.
This numerical study was carried out using the finite element approach and the lattice Boltzmann method. The dynamic and biomechanical characteristics of the leaflets were evaluated by using the finite element approach, while the blood flow in the aortic sinus was evaluated by applying the lattice Boltzmann method. Three types of leaflets with different heights were designed. Then the dynamic characteristics, stress distribution, and effective orifice area (EOA) of the aortic valve and flow pattern were calculated as the indicators.
The results demonstrated that the height of the leaflets could indeed regulate the performance and the biomechanical states of the aortic valve. The rapid valve opening times of the 3 types of leaflets gradually reduced along with the decrease of the height ratio (HR_0.8: 120 ms HR_1.0: 68 ms HR_1.2: 31 ms), while the rapid valve closing times (RVCTs) of the 3 types of leaflets were similar to each other (approximately 75 ms). Moreover, the radial displacement of the leaflet at the fully open time increased along with the decrease of the HR of the leaflets (HR_0.8: 8 mm HR_1.0: 6 mm HR_1.2: 4 mm). In addition, the stress level of the leaflets also increased with the increase of the height of the leaflets (max stress, HR_0.8: 0.5 MPa, HR_1.0: 1.1 MPa, HR_1.2: 1.8 MPa). Similarly, the low velocity region near the ascending aortic wall and the wall shear stress (WSS) level on the ventricular side of the leaflets also increased along with the increase of the HR of the leaflets.
In short, the height of the leaflets mainly affects the opening performance of the reconstructed aortic leaflets. The HR of the reconstructed leaflets for adults should be less than 1.0 to balance the opening and closing performance of aortic leaflets.
尽管主动脉瓣重建已成为主动脉瓣疾病的一种替代治疗方法，但重建瓣叶几何参数的设计仍主要依赖医生的经验。本研究探讨瓣叶高度对重建主动脉瓣性能和生物力学状态的影响。
本数值研究采用有限元方法和格子玻尔兹曼方法进行。利用有限元方法评估瓣叶的动态和生物力学特性，同时应用格子玻尔兹曼方法评估主动脉窦内的血流。设计了三种不同高度的瓣叶。然后计算主动脉瓣的动态特性、应力分布、有效瓣口面积（EOA）和血流模式作为指标。
结果表明，瓣叶高度确实可以调节主动脉瓣的性能和生物力学状态。三种瓣叶的快速瓣膜开启时间随着高度比（HR_0.8：120毫秒，HR_1.0：68毫秒，HR_1.2：31毫秒）的降低而逐渐减少，而三种瓣叶的快速瓣膜关闭时间（RVCTs）彼此相似（约75毫秒）。此外，瓣叶在完全打开时的径向位移随着瓣叶高度比的降低而增加（HR_0.8：8毫米，HR_1.0：6毫米，HR_1.2：4毫米）。此外，瓣叶的应力水平也随着瓣叶高度的增加而增加（最大应力，HR_0.8：0.5兆帕，HR_1.0：1.1兆帕，HR_1.2：1.8兆帕）。同样，升主动脉壁附近的低速区域和瓣叶心室侧的壁面剪应力（WSS）水平也随着瓣叶高度比的增加而增加。
简而言之，瓣叶高度主要影响重建主动脉瓣叶的开启性能。成人重建瓣叶的高度比应小于1.0，以平衡主动脉瓣叶的开闭性能。
