title: Transitional Flow in the Venous Side of Patient-Specific Arteriovenous Fistulae for Hemodialysis.
abstract: Arteriovenous fistula (AVF) is the first choice for providing vascular access for hemodialysis patients, but maintaining its patency is challenging. AVF failure is primarily due to development of neointimal hyperplasia (NH) and subsequent stenosis. Using idealized models of AVF we previously suggested that reciprocating hemodynamic wall shear is implicated in vessel stenosis. The aim of the present study was to investigate local hemodynamics in patient-specific side-to-end AVF. We reconstructed realistic geometrical models of four AVFs from magnetic resonance images acquired in a previous clinical study. High-resolution computational fluid dynamics simulations using patient-specific blood rheology and flow boundary conditions were performed. We then characterized the flow field and categorized disturbed flow areas by means of established hemodynamic wall parameters. In all AVF, either in upper or lower arm location, we consistently observed transitional laminar to turbulent-like flow developing in the juxta-anastomotic vein and damping towards the venous outflow, but not in the proximal artery. High-frequency fluctuations of the velocity vectors in these areas result in eddies that induce similar oscillations of wall shear stress vector. This condition may importantly impair the physiological response of endothelial cells to blood flow and be responsible for NH formation in newly created AVF.
authors.affiliation: Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi, 3, 24020, Ranica, BG, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Bozzetto
authors.affiliation: Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi, 3, 24020, Ranica, BG, Italy.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Ene-Iordache
authors.affiliation: Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi, 3, 24020, Ranica, BG, Italy. andrea.remuzzi@marionegri.it.|Department of Management, Information and Production and Engineering, University of Bergamo, Viale Marconi, 5, Dalmine, 24044, BG, Italy. andrea.remuzzi@marionegri.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Remuzzi
mesh_terms: D000328:Adult; D000368:Aged; D001163:Arteriovenous Anastomosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001783:Blood Flow Velocity; D003198:Computer Simulation; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D058426:Neointima / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011446:Prospective Studies; D006435:Renal Dialysis
keywords: Computational fluid dynamics; Disturbed flow; Hemodialysis; Transitional flow; Vascular access; Wall shear stress