Application of Fluid-Structure Interaction Methods to Estimate the Mechanics of Rupture in Asian Abdominal Aortic Aneurysms

摘要

Abdominal aortic aneurysms (AAAs) occur because of dilation of the infra-renal aorta to more than 150% of its initial diameter. Progression to rupture is aided by several pathophysiological and biomechanical factors. Surgical intervention is recommended when the aneurysm maximum transverse diameter (DAAA) exceeds 55 mm. A system model that incorporates biomechanical parameters will improve prognosis and establish a relationship between AAA geometry and rupture risk. Two Asian patient-specific AAA geometries were obtained from an IRB-approved vascular database. A biomechanical model based on the fluid-structure interaction (FSI) method was developed for a small aneurysm with DAAA of 35 mm and a large aneurysm with a corresponding diameter of 75 mm. The small aneurysm (patient 1) developed a maximum principal stress (PS1) of 3.16e5 Pa and the large aneurysm (patient 2) developed a PS1 of 2.32e5 Pa. Maximum deformation of arterial wall was 0.0020 m and 0.0022 m for patients 1 and 2 respectively. Location of maximum integral wall shear stress (WSS) (fluid) was different from that of PS1. Induced WSS was also higher in patient 1 (18.74 Pa vs 12.88 Pa). An FSI model incorporating the effect of both the structural and fluid domains aids in better understanding of the mechanics of AAA rupture. Patient 1, having a lower DAAA than patient 2, developed a larger PS1 and WSS. It may be concluded that DAAA may not be the sole determinant of AAA rupture risk.