Comparison Of Hemodynamic Changes Associated With Two Versus Four Vessel Fenestrated Endovascular Aneurysm Repair Using Patient-specific Computational Flow Modeling
Kenneth Tran, MD1, Adrien Kaladji, MD2, Weiguang Yang, PhD1, Alison Marsden, PhD1, Jason Lee, MD1.
1Stanford University, Stanford, CA, USA, 2Centre Hospitalier Universitaire de Rennes, Rennes, France.
OBJECTIVES: Fenestrated endovascular aneurysm repair (fEVAR) endografts with additional proximal fenestrations are the subject of upcoming pivotal trials in the United States. This study sought to use patient-specific flow simulation (CFS) to assess differences in hemodynamic effects associated with two (2v) versus four-vessel (4v) fEVAR after repair of complex aortic aneurysms. METHODS: Patients from two institutions who underwent 2v fEVAR for juxatrenal, and 4v fEVAR for pararenal/paravisceral aortic aneurysms with the Cook Zenith Fenestrated platform were retrospectively selected. Device diameters were matched between 2v and 4v groups. 3D finite element volume meshes were created from pre- and post-operative CTs. Boundary conditions were adjusted for body surface area, heart rate and blood pressure. Pulsatile flow simulations were performed using a non-compressible Navier-Stokes solver with equal boundary conditions between pre- and post-operative states. Post-operative changes in hemodynamic parameters were then compared between 2v and 4v groups. RESULTS: Patient-specific CFS was performed on 20 patients (10 2v, 10 4v fEVAR) with a total of 70 target vessels (40 renal, 10 celiac, 10 SMA stents, and 10 SMA scallops). 4v fEVAR was associated with a decrease in SMA peak flow rate (-7.1 vs +1.1%, p=.042) and a trend toward decreased peak pressure (-1.5 vs +0.7%, p=.07) compared to 2v fEVAR. There were no significant differences in celiac or renal perfusion metrics (p=.14-.93). 4v fEVAR was associated with decreased paravisceral aortic wall shear stress (WSS) (-31.3 vs +0.6%, p=.008), whereas SMA WSS was increased (+36.9 vs +15.5%, p=.049) compared to 2v fEVAR. No differences in celiac or renal WSS was observed between groups (p=.53-.93). Streamline visualization revealed flow disturbances surrounding flared branch graft protrusions into the aortic lumen which may be associated with changes in SMA perfusion after 4v fEVAR (Figure). CONCLUSIONS: Structural changes in paravisceral aortic geometry following 4v fEVAR may be associated with a subtle change in SMA perfusion and large reduction in aortic wall shear stress compared to 2v fEVAR. Patient-specific CFS is useful for studying the unique hemodynamic effects of additional fenestrations when adopting a higher seal zone.
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