A quasi-longitudinal study of the effect of hemodynamical parameters on the biomechanics of rupture in abdominal aortic aneurysms

Abstract

Maximum transverse diameter, routinely used as a clinical metric in abdominal aortic aneurysm (AAA) management is insufficient to accurately stratify rupture risk. In this study, a biomechanics-based approach is used to develop a relationship between maximum transverse diameter and hemodynamic parameters that are indicative of disease progression. Computational fluid dynamic (CFD) simulations are performed on six idealised, axisymmetric AAA models of increasing maximum transverse diameter indicative of disease progression. Additionally, a comparative hemo-dynamic analysis of the effect of four different inlet velocity profiles is performed. The results indicate a flow field with similar vortical structures forming in the aneurysmal sac, changing in intensity with increase in maximum transverse diameter. This is represented through elevated Time-Averaged Wall Shear Stresses (TAWSS) in the distal neck region of the aorta in the largest aneurysm (3.16 Pa). However, the elevation of TAWSS in smaller aneurysms is observed to be sharper than those in large aneurysms indicating an elevated rupture risk for smaller aneurysms even below the clinical metric of 55 mm. The plug inlet velocity profile showed the highest (8.81 Pa) TAWSS indicating jet-like flows in the aneurysmal sac. Current clinical management of AAAs will greatly benefit by bringing in additional insights through biomechanical analysis.