目的:使用计算流体动力学(CFD)对经导管主动脉瓣(TAV)进行的患者特异性模拟通常依赖于有关近端和远端解剖结构的假设,因为远离TAV部位的高分辨率成像的可用性有限,主要研究重点是在TAV附近。然而,这些解剖学假设对计算效率和由此产生的流动特性的影响仍然不确定。本研究旨在使用大涡模拟(LES)研究不同远端主动脉弓解剖结构对TAV附近血流和血流动力学的影响,其中一些在文献中常用。
方法:本研究考虑了三种主动脉根部解剖结构和四种有代表性的远端主动脉弓类型。拱形类型包括90度弯曲,理想化的远端主动脉弓解剖结构,理想化远端主动脉弓的夹闭版本,和沿着分段解剖边界的法线挤出的解剖结构。瞬时和时间平均的血流动力学参数,例如壁剪切应力(WSS),和振荡剪切指数(OSI)从高保真CFD数据中得出并比较。
结果:虽然在所检查的配置中流量和血流动力学有微小差异,它们在我们感兴趣的区域内通常不重要,即,主动脉根部.延伸类型的选择对TAV血流动力学有适度影响,特别是在TAV附近,在TAV附近观察到局部流动模式和参数的变化。然而,这些差异不足以导致总血流和血流动力学特征的显著偏差.
结论:结果表明,在给定的配置和边界条件下,流出延伸类型对TAV近端血流动力学影响不大.这些发现有助于更好地理解TAV配置中的流动动力学,为TAV相关实验和数值模拟的未来研究提供见解。此外,它们有助于减轻与患者特定几何形状相关的不确定性,在计算建模中提供更大的灵活性。
OBJECTIVE: Patient-specific simulations of transcatheter aortic valve (TAV) using computational fluid dynamics (
CFD) often rely on assumptions regarding proximal and distal anatomy due to the limited availability of high-resolution imaging away from the TAV site and the primary research focus being near the TAV. However, the influence of these anatomical assumptions on computational efficiency and resulting flow characteristics remains uncertain. This
study aimed to investigate the impact of different distal aortic arch anatomies-some of them commonly used in literature-on flow and hemodynamics in the vicinity of the TAV using large eddy simulations (LES).
METHODS: Three aortic root anatomical configurations with four representative distal aortic arch types were considered in this
study. The arch types included a 90-degree bend, an idealized distal aortic arch anatomy, a clipped version of the idealized distal aortic arch, and an anatomy extruded along the normal of segmented anatomical boundary. Hemodynamic parameters both instantaneous and time-averaged such as Wall Shear Stress (WSS), and Oscillatory Shear Index (OSI) were derived and compared from high-fidelity
CFD data.
RESULTS: While there were minor differences in flow and hemodynamics across the configurations examined, they were generally not significant within our region of interest i.e., the aortic root. The choice of extension type had a modest impact on TAV hemodynamics, especially in the vicinity of the TAV with variations observed in local flow patterns and parameters near the TAV. However, these differences were not substantial enough to cause significant deviations in the overall flow and hemodynamic characteristics.
CONCLUSIONS: The results suggest that under the given configuration and boundary conditions, the type of outflow extension had a modest impact on hemodynamics proximal to the TAV. The findings contribute to a better understanding of flow dynamics in TAV configurations, providing insights for future studies in TAV-related experiments as well as numerical simulations. Additionally, they help mitigate the uncertainties associated with patient-specific geometries, offering increased flexibility in computational modeling.