Numerical models for assessing the risk of leaflet thrombosis post-transcatheter aortic valve-in-valve implantation

Leaflet thrombosis has been suggested as the reason for the reduced leaflet motion in cases of hypoattenuated leaflet thickening of bioprosthetic aortic valves. This work aimed to estimate the risk of leaflet thrombosis in two post-ViV configurations, using five different numerical approaches. Realistic ViV configurations were calculated by modeling the deployments of the latest version of transcatheter aortic valve devices (Medtronic Evolut PRO, Edwards SAPIEN 3) in the surgical Sorin Mitroflow. Computational fluid dynamics simulations of blood flow followed the dry models. Lagrangian and Eulerian measures of near-wall stagnation were implemented by particle and concentration tracking, respectively, to estimate the thrombogenicity and to predict the risk locations. Most of the numerical approaches indicate on a higher leaflet thrombosis risk in the Edwards SAPIEN 3 device because of its intra-annular implantation. The Eulerian approaches estimated high-risk locations in agreement with ..., The results were exported from ANSYS Fluent and processed in Matlab and Paraview.
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已有研究表明，生物人工主动脉瓣出现瓣叶衰减减低性增厚（hypoattenuated leaflet thickening）时，瓣叶活动度降低的诱因是瓣叶血栓形成（leaflet thrombosis）。本研究旨在采用五种不同的数值分析方法，评估两种瓣中瓣（valve-in-valve, ViV）配置场景下的瓣叶血栓形成风险。我们通过在外科植入的Sorin Mitroflow瓣膜支架内，建模经导管主动脉瓣装置的最新版本——美敦力（Medtronic）Evolut PRO、爱德华兹（Edwards）SAPIEN 3——的释放过程，构建得到符合临床实际的ViV配置模型。基于上述干式模型开展血流计算流体动力学（computational fluid dynamics, CFD）仿真。分别通过粒子追踪法与浓度追踪法，实现近壁停滞流的拉格朗日（Lagrangian）与欧拉（Eulerian）量化表征，以此评估血栓形成风险并预测高危部位。多数数值分析方法均显示，爱德华兹SAPIEN 3装置因采用瓣环内植入方式，其瓣叶血栓形成风险更高。欧拉法预测的高危部位与……相符。本研究结果由ANSYS Fluent导出，并借助Matlab与Paraview完成后处理。