Intra-stent thrombosis is one of the major failure modes of popliteal aneurysm endovascular repair, especially when the diseased arterial segment is long and requires overlapping stent-grafts having different nominal diameters in order to accommodate the native arterial tapering.

However, the interplay between stent sizing, post-operative arterial tortuosity, luminal diameter, local hemodynamics, and thrombosis onset is not elucidated, yet.

In the present study, a popliteal aneurysm was treated with endovascular deployment of two overlapped stent-grafts, showing intra-stent thrombosis at one-year follow-up examination. Patient-specific computational fluid-dynamics analyses including straight- and bent-leg position were performed.

The computational fluid-dynamics analysis showed that the overlapping of the stent-grafts induces a severe discontinuity of lumen, dividing the stented artery in two regions: the proximal part, affected by thrombosis, is characterized by larger diameter, low tortuosity, low flow velocity, low helicity, and low wall shear stress; the distal part presents higher tortuosity and smaller lumen diameter promoting higher flow velocity, higher helicity, and higher wall shear stress. Moreover, leg bending induces an overall increase of arterial tortuosity and reduces flow velocity promoting furtherly the luminal area exposed to low wall shear stress.

支架内血栓形成是腘动脉瘤血管内修复的主要失败模式之一，特别是当病变动脉段很长并且需要具有不同标称直径的重叠覆膜支架以适应天然动脉逐渐变细时。

然而，支架尺寸、术后动脉迂曲度、管腔直径、局部血流动力学和血栓形成之间的相互作用尚未阐明。

在本研究中，通过血管内部署两个重叠的覆膜支架治疗腘动脉瘤，在一年的随访检查中显示支架内血栓形成。进行了患者特定的计算流体动力学分析，包括直腿和弯曲腿位置。

计算流体动力学分析表明，支架移植物的重叠导致管腔严重不连续，将支架动脉分为两个区域：近端部分，受血栓形成影响，具有较大的直径、低曲折度、低流速，低螺旋度和低壁剪切应力；远端部分呈现更高的弯曲度和更小的管腔直径，促进更高的流速、更高的螺旋度和更高的壁剪切应力。此外，腿部弯曲会导致动脉弯曲度整体增加并降低流速，从而进一步促进暴露于低壁剪切应力的管腔区域。