Abstract: Hemodynamics plays a crucial role in the growth of an abdominal aortic aneurysm (AAA) and its possible rupture. Due to the serious consequences that arise from the aneurysm rupture, the ability to predict its evolution and the need for surgery are of primary importance in the medical field. Furthermore, the presence of intraluminal thrombus (ILT) strongly affects the evolution of the pathology. In this study, we analyzed the influence of hemodynamics on the growth and possible rupture of AAAs. Numerical investigations of pulsatile non-Newtonian blood flow were performed in six patient-specific AAAs reconstructed from diagnostic images, having different sizes and shapes, and with or without ILT. Wall shear stress and vorticity distribution in the bulge and their evolution during the cardiac cycle were analyzed. The results indicate that blood flow dynamics acts synergistically with atherosclerotic degeneration in the development of the disease. The high surface complexity and tortuosity of the aneurysms significantly affect the blood motion, and the presence of inflection in the aneurysm centerline has a noticeable effect on the vortex dynamics. Links between regions of slow recirculating flows, low values of time-averaged wall shear stress, high values of oscillatory shear index, and zones of ILT deposition were found. In the absence of ILT, possible thrombus accumulation areas and consequent aneurysm growth were identified. The findings of this study highlight the importance of hemodynamics in assessing the vulnerability of the aortic wall and underline the crucial role of patient-specific investigations in predicting the rupture of individual aneurysms.

Key words: Hemodynamics; Computational fluid dynamics; Wall shear stress; Vortex dynamics; Abdominal aortic aneurysm (AAA); Patient-specific modelling

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