title: Hemodynamic impact of abdominal aortic aneurysm stent-graft implantation-induced stenosis.
abstract: The current study aims to computationally evaluate the hemodynamic impact of a novel sealing mechanism employed by a recently developed endograft (Ovation TriVascular Stent-Graft System) for endovascular aneurysm repair. The exploitation of two inflatable O-rings to achieve sealing may be advantageous in terms of accommodating challenging anatomies, but comes at a price of a marked inflow stenosis. Here, four representative patient cases of inflow stenosis ranging from 30 to 80 % were analyzed. Lumen surface models were constructed from 1 month post-operative computed tomography images and then used to numerically compute the complex endograft flow field. Our results highlight coexistence of stenotic wall regions exposed to high shear rate and post-stenotic recirculation zones. These conditions may implicate platelet activation and predispose thrombus formation and thromboembolic complications. A clinically insignificant cycle-averaged pressure drop along the inflow stenosis and further in the endograft main body legs was predicted (range 0.01-1.72 mmHg) which was, however, notable at peak systole (range 3.52-19.73 mmHg). Although the functional impact of the endograft stenosis at rest flow conditions may appear insignificant, increased flow rate during exercise is expected to strongly accentuate the observed effects. Pressure drop in the endograft legs was attributed to suboptimal, based on Murray's scaling law, cross-sectional area ratio between trunk and legs of the device.
authors.affiliation: Institute of Applied and Computational Mathematics, Foundation for Research and Technology - Hellas, Nikolaou Plastira 100, Vassilika Vouton, 71 110, Heraklion, Crete, Greece.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Aristokleous
authors.affiliation: Department of Vascular Surgery, University of Crete Medical School, Heraklion, Crete, Greece.
authors.forename: Nikolaos G
authors.initials: NG
authors.lastname: Kontopodis
authors.affiliation: Institute of Applied and Computational Mathematics, Foundation for Research and Technology - Hellas, Nikolaou Plastira 100, Vassilika Vouton, 71 110, Heraklion, Crete, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tzirakis
authors.affiliation: Department of Vascular Surgery, University of Crete Medical School, Heraklion, Crete, Greece.
authors.forename: Christos V
authors.initials: CV
authors.lastname: Ioannou
authors.affiliation: Institute of Applied and Computational Mathematics, Foundation for Research and Technology - Hellas, Nikolaou Plastira 100, Vassilika Vouton, 71 110, Heraklion, Crete, Greece. yannisp@iacm.forth.gr.
authors.forename: Yannis
authors.initials: Y
authors.lastname: Papaharilaou
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000601:surgery*; D003198:Computer Simulation; D003251:Constriction, Pathologic / Q000209:etiology*; D006801:Humans; D012189:Retrospective Studies; D015607:Stents / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed
keywords: Abdominal aortic aneurysm; Endovascular graft; Image-based CFD; Thrombosis