J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA.
Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA.
Int J Numer Method Biomed Eng. 2022 Feb;38(2):e3555. doi: 10.1002/cnm.3555. Epub 2021 Dec 12.
The intraluminal thrombus (ILT) has been shown to negatively impact the progression of the abdominal aortic aneurysms (AAAs). The formation of this thrombus layer has been connected to the local flow environment within AAAs, but the specific mechanisms leading to thrombus formation are still not fully understood. Our study investigated the association between vortical structures, near-wall hemodynamic metrics (e.g., time averaged wall shear stress (TAWSS) and oscillatory shear index (OSI)), and ILT accumulation in a longitudinal cohort of 14 AAAs (53 scans total). Vortices and hemodynamic parameters were estimated using hemodynamic simulations performed to each scan of each patient and compared to local 3D changes of ILT thickness between two consecutive scans (ΔILT). Results showed that vortices formed and remained strong and close to the lumen surface in AAAs without an ILT, while in AAAs with ILTs these detached from the lumen surface and dissipated nearby wall region where an increase in ILT thickness was observed. Although low TAWSS was observed in regions with and without ILT accumulation, an inverse correlation between and TAWSS was observed within the regions that experienced a thrombus growth. Our results support the idea that vortical structures might be playing a role modulating ILT accumulation into specific wall regions. Also, it submits the idea that the low TAWSS will be modulating the growth of thrombus within these preferred ILT accumulated regions.
腔内血栓（ILT）已被证明对腹主动脉瘤（AAA）的进展有负面影响。血栓层的形成与 AAA 内的局部流动环境有关，但导致血栓形成的具体机制仍不完全清楚。我们的研究调查了涡结构、近壁血液动力学指标（例如，时均壁切应力（TAWSS）和振荡剪切指数（OSI））与 14 个 AAA （共 53 个扫描）中 ILT 堆积之间的关联。使用对每个患者的每个扫描执行的血流动力学模拟来估计涡和血液动力学参数，并将其与两次连续扫描之间 ILT 厚度的局部 3D 变化（ΔILT）进行比较。结果表明，在没有 ILT 的 AAA 中，涡形成并保持强烈且靠近管腔表面，而在有 ILT 的 AAA 中，涡从管腔表面分离并在附近的壁区域消散，在该区域观察到 ILT 厚度增加。尽管在有和没有 ILT 堆积的区域都观察到低 TAWSS，但在经历血栓生长的区域中观察到与 TAWSS 的反相关。我们的结果支持这样一种观点，即涡结构可能在调节 ILT 堆积到特定壁区域方面发挥作用。此外，它提出了低 TAWSS 将调节这些首选 ILT 堆积区域内血栓生长的观点。
