Hemodynamic characteristic analysis of ruptured abdominal aortic aneurysms based on computational fluid dynamics

It is less accurate to assess the risk of abdominal aortic aneurysm (AAA) rupture based solely on morphological indicators such as maximum diameter. The objective of this study is to investigate the relationship between local hemodynamic parameters and the actual rupture location. We reconstructed three-dimensional models of four AAA models based on computed tomography angiography images, including three ruptured and one unruptured model. Hemodynamic parameters, specifically wall shear stress (WSS)-based hemodynamic parameters at the AAA wall rupture sites, were analyzed through computational fluid dynamics simulations. The temporal evolution of streamlines and vortex structures was examined to elucidate the underlying mechanisms leading to AAA rupture. AAA wall regions characterized by both the lowest time-averaged WSS (TAWSS) and high oscillatory shear index, as well as regions with high TAWSS and high positive WSS gradient, are associated with a higher risk of AAA rupture. Additionally, recirculation flow dominates within the aneurysm lumen and likely serves as a significant hemodynamic driver for rupture; both the antegrade (flow impingement) and retrograde section could trigger a hemodynamic environment of high rupture risk. Furthermore, intraluminal thrombus has been shown to influence the formation and development of recirculation zones and inhibit the downstream progression of the primary horseshoe vortex that forms at the aneurysm neck; this fluid mechanism may eventually be involved in affecting the location of AAA rupture. Our findings suggest that WSS-based hemodynamic parameters are significantly associated with the risk of AAA rupture. Additionally, the evolution of recirculation zones and vortex structures within AAA influences the ultimate rupture site from a fluid dynamic perspective.