Chen Chia-Yuan, Antón Raúl, Hung Ming-yang, Menon Prahlad, Finol Ender A, Pekkan Kerem
J Biomech Eng. 2014 Mar;136(3):031001. doi: 10.1115/1.4026160.
The pathology of the human abdominal aortic aneurysm (AAA) and its relationship to the later complication of intraluminal thrombus (ILT) formation remains unclear. The hemodynamics in the diseased abdominal aorta are hypothesized to be a key contributor to the formation and growth of ILT. The objective of this investigation is to establish a reliable 3D flow visualization method with corresponding validation tests with high confidence in order to provide insight into the basic hemodynamic features for a better understanding of hemodynamics in AAA pathology and seek potential treatment for AAA diseases. A stereoscopic particle image velocity (PIV) experiment was conducted using transparent patient-specific experimental AAA models (with and without ILT) at three axial planes. Results show that before ILT formation, a 3D vortex was generated in the AAA phantom. This geometry-related vortex was not observed after the formation of ILT, indicating its possible role in the subsequent appearance of ILT in this patient. It may indicate that a longer residence time of recirculated blood flow in the aortic lumen due to this vortex caused sufficient shear-induced platelet activation to develop ILT and maintain uniform flow conditions. Additionally, two computational fluid dynamics (CFD) modeling codes (Fluent and an in-house cardiovascular CFD code) were compared with the two-dimensional, three-component velocity stereoscopic PIV data. Results showed that correlation coefficients of the out-of-plane velocity data between PIV and both CFD methods are greater than 0.85, demonstrating good quantitative agreement. The stereoscopic PIV study can be utilized as test case templates for ongoing efforts in cardiovascular CFD solver development. Likewise, it is envisaged that the patient-specific data may provide a benchmark for further studying hemodynamics of actual AAA, ILT, and their convolution effects under physiological conditions for clinical applications.
人类腹主动脉瘤（AAA）的病理学及其与腔内血栓（ILT）形成这一后期并发症的关系仍不明确。据推测，病变腹主动脉中的血流动力学是ILT形成和生长的关键因素。本研究的目的是建立一种可靠的三维流动可视化方法，并进行相应的具有高可信度的验证测试，以便深入了解基本血流动力学特征，从而更好地理解AAA病理学中的血流动力学，并寻找AAA疾病的潜在治疗方法。使用透明的患者特异性实验性AAA模型（有和没有ILT）在三个轴向平面上进行了立体粒子图像测速（PIV）实验。结果表明，在ILT形成之前，AAA模型中产生了三维涡旋。ILT形成后未观察到这种与几何形状相关的涡旋，表明其在该患者后续ILT出现中可能发挥的作用。这可能表明，由于这种涡旋，主动脉腔内再循环血流的停留时间延长，导致足够的剪切诱导血小板活化，从而形成ILT并维持均匀的流动条件。此外，将两种计算流体动力学（CFD）建模代码（Fluent和内部开发的心血管CFD代码）与二维、三分量速度立体PIV数据进行了比较。结果表明，PIV与两种CFD方法的面外速度数据的相关系数均大于0.85，表明定量一致性良好。立体PIV研究可作为心血管CFD求解器开发中正在进行的工作的测试案例模板。同样，可以设想，患者特异性数据可能为进一步研究实际AAA、ILT及其在生理条件下的卷积效应的血流动力学提供基准，以用于临床应用。
