Hou Qianwen, Tao Keyi, Du Tianming, Wei Hongge, Zhang Honghui, Chen Shiliang, Pan Youlian, Qiao Aike
Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
Comput Methods Programs Biomed. 2022 Jun;220:106811. doi: 10.1016/j.cmpb.2022.106811. Epub 2022 Apr 11.
The bicuspid aortic valve (BAV) is a major risk factor for the progression of aortic dilation (AD) because of the induced abnormal blood flow environment in aorta. The differences in the development of AD induced by BAV phenotypes remains unclear. Therefore, the objective of this study was to assess the potential locations of AD induced by different phenotypes of BAV. The different effects of opening orifice area and leaflet orientation on ascending aortic hemodynamics in Type-1 BAV was investigated by means of numerical simulation.
Finite element dynamic analysis was performed on tricuspid aortic valve (TAV) and BAV models to simulate the motion of the leaflets and obtain the geometrical characteristics of AV at peak systole as a reference, which were used for aortic models. Then, four sets of aortic fluid models were designed according to the leaflet fusion types [TAV; BAV (left-right-coronary cusp fusion, LR; right-non-coronary cusp fusion, RN; left-non-coronary cusp fusion, LN)], and the computational fluid dynamics method was applied to compare the hemodynamic differences within the aorta at peak systole.
The maximum opening area of BAV was significantly reduced, resulting in alterations in aortic hemodynamics compared with TAV. The velocity streamlines were essentially parallel to the aortic wall in TAV. The average pressure and wall shear stress in aorta tend to be stable. In contrary, the eccentricity of BAV orifice jet resulted in high-velocity flow directed toward the ascending aorta (AA) wall and aortic arch for LR and LN; RN features an asymmetrical velocity distribution toward the outer bend of the middle AA, and eccentric flow tends to impact the distal AA. As the flow angle is associated with distinct flow impingement locations, different degrees of WSS and pressure concentration occur along the aortic wall from the AA to the aortic arch in three BAV types.
The BAV morphotype affects the aortic hemodynamics, and the abnormal blood flow associated with BAV may play a role in AD. The different BAV phenotypes determine the direction of blood flow jet and change the expression of dilation. LR is likely to cause dilation of the tubular AA; RN results in dilation of the middle AA to proximal aortic arch; and LN causes an increased incidence of the tubular AA and the proximal aortic arch.
二叶式主动脉瓣（BAV）由于在主动脉中诱导产生异常血流环境，是主动脉扩张（AD）进展的主要危险因素。BAV不同表型所诱导的AD发展差异尚不清楚。因此，本研究的目的是评估不同表型BAV所诱导的AD的潜在位置。通过数值模拟研究了1型BAV中开口面积和瓣叶方向对升主动脉血流动力学的不同影响。
对三尖瓣主动脉瓣（TAV）和BAV模型进行有限元动态分析，以模拟瓣叶运动，并获取收缩期末期主动脉瓣的几何特征作为参考，用于构建主动脉模型。然后，根据瓣叶融合类型设计了四组主动脉流体模型[TAV；BAV（左右冠状动脉瓣叶融合，LR；右无冠状动脉瓣叶融合，RN；左无冠状动脉瓣叶融合，LN）]，并应用计算流体动力学方法比较收缩期末期主动脉内的血流动力学差异。
与TAV相比，BAV的最大开口面积显著减小，导致主动脉血流动力学改变。TAV中的速度流线基本与主动脉壁平行。主动脉内的平均压力和壁面剪应力趋于稳定。相反，BAV瓣口射流的偏心导致LR和LN类型中高速血流指向升主动脉（AA）壁和主动脉弓；RN的特征是向中AA外弯处的不对称速度分布，偏心血流倾向于冲击远端AA。由于流动角度与不同的流动冲击位置相关，三种BAV类型中从AA到主动脉弓的主动脉壁上会出现不同程度的壁面剪应力（WSS）和压力集中。
BAV形态类型影响主动脉血流动力学，与BAV相关的异常血流可能在AD中起作用。不同的BAV表型决定血流喷射方向并改变扩张的表现。LR可能导致管状AA扩张；RN导致中AA至近端主动脉弓扩张；LN导致管状AA和近端主动脉弓的发病率增加。
