In this paper, we evaluate computationally the influence of blood flow eccentricity and valve phenotype (bicuspid (BAV) and tricuspid (TAV) aortic valve) on hemodynamics in ascending thoracic aortic aneurysm (ATAA) patients. 5 TAV ATAA, 5 BAV ATAA (ascending aorta diameter $>$35 mm) and 2 healthy subjects underwent 4D flow MRI. The 3D velocity profiles obtained from 4D flow MRI were given as input boundary conditions to a computational fluid dynamics analysis (CFD) model. After performing the CFD analyses, we verified that the obtained time-averaged velocity profiles and flow eccentricity were in good agreement with 4D flow MRI. Then we used the CFD analyses to evaluate the time-averaged wall shear stress (TAWSS) and the local normalized helicity (LNH). We found that the flow eccentricities at the aortic root were not significantly different (p $>$ 0.05) between TAV and BAV phenotypes. TAWSS (R² = 0.697, p = 0.025) and absolute LNH (R² = 0.964, p $<$ 0.001) are in good correlation with flow eccentricity. We conclude that eccentricity at the aortic root is a major determinant of hemodynamics patterns in ATAA patients regardless of the aortic valve phenotype.

在本文中，我们通过计算评估了血流偏心率和瓣表型（二尖瓣（BAV）和三尖瓣（TAV）主动脉瓣）对升主动脉瘤（ATAA）患者血液动力学的影响。5 TAV ATAA，5 BAV ATAA（升主动脉直径$>$35毫米）和2名健康受试者进行了4D流MRI检查。从4D流MRI获得的3D速度分布作为输入边界条件提供给计算流体动力学分析（CFD）模型。进行CFD分析后，我们验证了所获得的时间平均速度曲线和流偏心度与4D流MRI吻合良好。然后，我们使用CFD分析来评估时间平均壁面剪应力（TAWSS）和局部归一化螺旋度（LNH）。我们发现主动脉根部的血流偏心率没有显着差异（p$>$TAV和BAV表型之间的差异为0.05）。TAWSS（R ² = 0.697，p = 0.025）和绝对LNH（R ² = 0.964，p$<$0.001）与流量偏心率有很好的相关性。我们得出的结论是，不管主动脉瓣表型如何，在ATAA患者中主动脉根部的离心率都是血流动力学模式的主要决定因素。