Influence of breathing-induced motion on hemodynamics following fEVAR with renal stenting

Fenestrated EndoVascular Aneurysm Repair (fEVAR) has been demonstrated to be an excellent treatment for complex abdominal aortic aneurysms. In addition to the aortic endograft, bridging stent-grafts (SG) are deployed within the renal arteries, resulting in rare but serious renal complications. This study aims to assess renal artery hemodynamic changes post-fEVAR, including the effect of respiration-induced renal deformation.

Pre-fEVAR models were segmented from CT scans (patients involved in clinical trial NCT04724863), while post-fEVAR models were created from structural simulations that included respiratory-induced deformation. Computational Fluid Dynamics (CFD) simulations applied inflow velocity waveforms at the supraceliac aorta and Windkessel boundary conditions at the outlets. A dynamic mesh was implemented to reproduce renal deformation during breathing, and inspiration and expiration static configurations were analyzed.

Post-fEVAR reduction in renal artery flow was detected, together with recirculation regions near the SG protrusions into the aorta. Higher time-averaged wall shear stress was observed in the unstented section of the renal arteries. The comparison between static and dynamic mesh simulations reveals that renal artery motion has negligible effect on the flow. Finally, velocity fields were compared to metrics used clinically to assess renal stenosis, to build a model for the prediction of renal complications in silico.

This study evaluates the impact of renal stenting on flow, accounting for respiratory-induced deformation. It shows a minimal influence on overall hemodynamics, but significant reduction of renal flow post-fEVAR. Future studies should evaluate a patient cohort who experienced renal complications to correlate CFD metrics with post-operative clinical outcomes.