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Abstract：
We investigate the flow past two transcatheter aortic valves (TAVs) and one severely calcified valve in an anatomically realistic aorta geometry to evaluate the ability of the TAVs to establish a healthier aortic flow compared to a diseased case. Velocity measurements of pulsatile flow are carried out using the 3D-particle tracking velocimetry technique. We present a novel approach based on the Smagorinsky model to assess the important subvoxel-scale (here smaller than 750 [Formula: see text]m) shear stress contribution that is usually unavailable in experiments. Both TAV models feature a small retrograde flow of about 5% of the stroke volume and a lower number of coherent vortical structures. Turbulence past the TAVs is strongly suppressed as evidenced by the lower levels of turbulent kinetic energy even though the newer generation TAV performs better than the old one. Also lysis indices are substantially reduced in both models. The new generation TAV displays a slightly higher risk for thrombogenicity due to longer exposure times. We anticipate that our new approach to include turbulence and shear stress related quantities may help to validate the design of cardiovascular devices.
摘要：
我们在解剖学上真实的主动脉几何结构中研究了两个经导管主动脉瓣（TAV）和一个严重钙化的瓣膜的流量，以评估TAV与患病病例相比建立更健康的主动脉流量的能力。使用3D粒子跟踪测速技术进行脉动流的速度测量。我们提出了一种基于Smagorinsky模型的新方法，以评估实验中通常无法获得的重要亚体素尺度（此处小于750[公式：见文本]m）剪切应力贡献。两种TAV模型的特征都是小的逆行流量，约占冲程量的5％，并且相干涡旋结构的数量较少。通过TAV的湍流受到强烈抑制，这一点可以通过较低的湍流动能来证明，尽管新一代TAV的性能比旧TAV更好。在两种模型中裂解指数也显著降低。由于暴露时间较长，新一代TAV显示出较高的血栓形成风险。我们预计，包括湍流和剪切应力相关量的新方法可能有助于验证心血管设备的设计。
