Integrated Assessment of Wall Shear Stress-Related Hemodynamic Parameters in Abdominal Aortic Aneurysms: A Retrospective Cross-Sectional Study on Ruptured Cases

Abstract

Abdominal aortic aneurysms (AAAs) are a serious medical condition that may culminate in internal bleeding and death. Clinicians are expected to assess the rupture risk of AAAs accurately to determine the mode and timing of intervention. In general practice, AAA diameter and growth rate are used as rupture risk indicators. However, numerous cases have been reported where relying solely on these two AAA characteristics has proven insufficient, suggesting that other biomechanical factors deserve further consideration. This paper aims to investigate the involvement of disturbed hemodynamics in AAA rupture. Twenty-two AAA cases that had progressed to the point where surgical intervention was necessitated were assessed to examine the flow dynamics around the rupture sites. Using computational fluid dynamics (CFD), four key wall shear stress (WSS)-related hemodynamic parameters were calculated for each studied case, namely the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT). CFD geometries were developed exclusively using patient computed tomography images, and simulations were run with general physiological boundary conditions to demonstrate a clinically practical, low-input CFD pipeline. The study found that analyzing the spatial distribution of the WSS-related hemodynamic parameters can be a powerful approach for predicting the site of rupture in AAAs. Low TAWSS and high OSI/ECAP/RRT regions (specifically within the ranges: TAWSS 0–0.5 Pa, OSI 0.35–0.5, ECAP 1.6–2.0 Pa⁻¹, RRT 24–30) were found to be high-risk locations for rupture. Additionally, the simultaneous analysis of all four parameters was critical for rupture risk assessment.