ABSTRACT
OBJECTIVES: Low wall shear stress (WSS) is predictive of aortic aneurysm growth and rupture. Yet, estimating WSS in a clinical setting is impractical whereas measuring aneurysm geometry is feasible. This study investigates the association between saccular aneurysm geometry of the infrarenal aorta and WSS. METHODS: Starting with a non- aneurysmal, patient-specific, computational fluid dynamics model of the aorta, saccular aneurysms of varying geometry were created by incrementally increasing the neck width and sac depth from 1cm to 4cm. The aspect ratio (the ratio between sac depth and neck width) varied between 0.25 and 4. The peak WSS, time- averaged WSS (TAWSS), and oscillatory shear index (OSI) were measured within the aneurysm sac. RESULTS: Decreasing the neck width from 4cm to 1cm decreased the peak WSS by 69% and the TAWSS by 83%. Increasing the sac depth from 1cm to 4cm decreased the peak WSS by 55% and OSI by 37%. The aspect ratio was negatively correlated to peak WSS (Rs -0.85, p<0.001). CONCLUSIONS: In saccular aneurysms of the infrarenal aorta, a smaller neck width, deeper aneurysm sac, and larger aspect ratio are associated with lower peak WSS.
