ABSTRACT

In this study, numerical simulations and experiments were conducted on patient-specific normal abdominal aorta and abdominal aortic aneurysm (AAA) with intraluminal thrombus (ILT) models, which were reconstructed from computed tomography angiography (CTA) images published online. A scale-adaptive simulation (SAS) of the abdominal aortic aneurysm with a posterior eccentric thrombus was performed and the reliability of the numerical simulation was verified by 2D particle image velocimetry (PIV) experimental results. The distribution of wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT) of the normal abdominal aorta and AAA were compared and discussed systematically according to the numerical simulation results under rest and exercise conditions. Numerical results indicated that ILT deposition positions were accompanied by low WSS, high OSI, and high RRT regions and were characterized by small vortex groups, which was due to the fragmentation of large vortex structures. The distribution law of the AAA wall parameters has an obvious correlation with the nearby vortex structure formation, development, fragmentation and dissipation. It was also found that high TAWSS, low OSI, and low RRT regions present in the middle and lower aneurysm walls under exercise condition reduce the risk of ILT formation and development.

摘要

在这项研究中，对具有管腔内血栓 (ILT) 模型的患者特异性正常腹主动脉和腹主动脉瘤 (AAA) 进行了数值模拟和实验，这些模型是根据在线发布的计算机断层扫描血管造影 (CTA) 图像重建的。对腹主动脉瘤与后部偏心血栓进行了尺度自适应模拟（SAS），并通过二维粒子图像测速（PIV）实验结果验证了数值模拟的可靠性。根据静息和运动条件下的数值模拟结果，系统地比较和讨论了正常腹主动脉和AAA的管壁剪应力（WSS）、振荡剪切指数（OSI）和相对停留时间（RRT）的分布情况。数值结果表明，ILT沉积位置伴随着低WSS、高OSI和高RRT区域，并以小涡群为特征，这是由于大涡结构的破碎所致。AAA壁参数的分布规律与附近涡结构的形成、发展、破碎和消散具有明显的相关性。还发现运动条件下中下动脉瘤壁存在的高 TAWSS、低 OSI 和低 RRT 区域降低了 ILT 形成和发展的风险。发展、分裂和消散。还发现运动条件下中下动脉瘤壁存在的高 TAWSS、低 OSI 和低 RRT 区域降低了 ILT 形成和发展的风险。发展、分裂和消散。还发现运动条件下中下动脉瘤壁存在的高 TAWSS、低 OSI 和低 RRT 区域降低了 ILT 形成和发展的风险。