Computational fluid hemodynamic based analyisis of the aorto iliac segment before the development of post EVAR iliac branch occlusion

Abstract

Objective

Iliac limb branch occlusion after endovascular aneurysm repair (EVAR) creates risk for limb or pelvic ischemia. This study aims to explore the hemodynamic factors associated with eventual iliac branch occlusion after EVAR for abdominal aortic aneurysm.

Methods

Six patients with different causes of iliac branch occlusion were selected between January 2013 and December 2023, and computed tomography angiography (CTA) images were acquired at the time of preoperative and postoperative occlusion of EVAR. Specific CTA images were applied for modeling and computational fluid dynamics (CFD) analysis was implemented.

Results

Pressure, velocity, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory Shear Index (OSI), and relative residence time (RRT) were calculated. Velocity, WSS, and TAWSS were elevated at the stenosis, and pressure, OSI, and RRT were decreased at the stenosis. Streamlines were reduced at stenotic sites. Iliac branch locations that eventually occluded had more disturbed flow compared to non-occluded sites. Both pressure and flow velocity gradient variations are greater on the occluded side than on the non-occluded side.

Conclusions

Computational fluid hemodynamic analysis identified consistent flow disturbances associated with eventual iliac limb occlusion following EVAR. These findings suggest that CFD-based hemodynamic assessment may help stratify patients at risk of iliac branch occlusion before clinical manifestation.