Computational Simulation of Respiration-Induced Deformation of Renal Arteries After EVAR.

Purpose: Fenestrated endovascular aneurysm repair (fEVAR) is widely used to treat complex abdominal aortic aneurysms, requiring renal artery stenting. However, complications such as occlusion can occur within the renal arteries. This study examines the effect of respiration-induced deformations, using patient-specific models and computational simulations. By investigating the impact of stenting and breathing, this research aims to improve surgical pre-planning and minimize EVAR complications.

Methods: Pre-EVAR geometries from CT scans were segmented and meshed. Respiratory-induced displacements were applied to the segmented ends of the renal arteries to simulate breathing. The deployment process was achieved via balloon expansion, testing bridging stent-grafts with different lengths. To evaluate the accuracy of the workflow, simulated results and post-op CT scans were compared using centerline analysis, measuring morphological differences between the patient-specific models and the actual patients.

Results: Numerical simulations accurately predicted renal artery movement during respiration, aligning with in vivo measurements. Simulated stent-graft configurations closely matched post-EVAR CT scans. Stent-graft protrusions into the aortic lumen were within the expected range, indicating correct positioning. Longer stent-grafts constrained renal artery movement, affecting branching angle changes, while shorter grafts had a less pronounced impact.

Conclusions: Our novel digital twin model accurately simulates fEVAR procedures, including the deployment of renal bridging stent-grafts. Numerical simulations capture the bending of the renal arteries during breathing and their morphological changes following stenting in the post-operative configurations. Future research aims to expand the patient cohort and combine the solid mechanics simulations with CFD analysis.