Effect of breathing-induced motion on renal artery hemodynamics following abdominal aortic aneurysm stenting

Endovascular Aneurysm Repair (EVAR) is the preferred treatment for Abdominal Aortic Aneurysm. For fenestrated EVAR (fEVAR), bridging stent-grafts are deployed into branches, such as renal arteries (RA), after aortic stent-graft (SG) placement. RA complications, involving stenosis/occlusions, have been reported in 12% of fEVAR. Structural simulations quantified breathing-induced deformations post-EVAR for two patients, testing different SG lengths. This study focuses on the impact of these deformations on RA hemodynamics. CFD simulations evaluate hemodynamic changes in the RAs due to breathing, implementing dynamic mesh to simulate the respiratory-induced motion. They show a post-op reduction in RA flow, with formation of recirculation regions near the SG protrusions into the aorta. Lower time-averaged wall shear stress was observed in the stented section compared to the unstented region. Comparison between static and dynamic mesh simulations revealed that wall motion inertia is negligible compared to the flow inertia. CFD results were compared to clinical metrics to diagnose RA stenosis, aiming to predict fEVAR renal complications.