title: Comparison Between Bench-Top and Computational Modelling of Cerebral Thromboembolism in Ventricular Assist Device Circulation.
abstract: Despite improvements in ventricular assist devices (VAD) design, VAD-induced stroke rates remain remarkably high at 14-47%. We previously employed computational fluid dynamics (CFD) to propose adjustment of VAD outflow graft (VAD-OG) implantation to reduce stoke. Herein, we present an in-vitro model of cerebral vessel embolization in VAD-assisted circulation, and compare benchtop results to CFD predictions. The benchtop flow-loop consists of a 3D printed aortic bed using Accura 60 polymer driven by a continuous-flow pump. Three hundred spherical particles simulating thrombi of 2, 3.5, and 5 mm diameters were injected at the mock VAD-OG inlet. A water and glycerin mixture (3.8 cP viscosity) synthetically mimicked blood. The flowrate was adjusted to match the CFD Reynolds number. Catch cans were used to capture and count particles reaching cerebral vessels. VAD-OG geometries were evaluated using comparison of means Z-score range of -1.96 ≤ Z ≤ 1.96 to demonstrate overall agreement between computational and in-vitro techniques. Z-scores were: (i) Z = -1.05 for perpendicular (0°), (ii) Z = 0.32 for intermediate (30°), and (iii) Z = -0.52 for shallow (60°) anastomosis and confirmed agreement for all geometries. This study confirmed added benefits of using a left carotid artery bypass-graft with percent embolization reduction: 22.6% for perpendicular, 21.2% for intermediate, and 11.9% for shallow anastomoses. The shallow anastomosis demonstrated lower degrees of aortic arch flow recirculation, consistent with steady-flow computations. Quantitatively and qualitatively, contemporary steady-flow computational models for predicting VAD-induced cerebral embolization can be achieved in-vitro to validate the CFD equivalent.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL, 32816, USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Clark
authors.affiliation: College of Medicine, University of Central Florida, Orlando, FL, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Eslahpazir
authors.affiliation: Division of Cardiothoracic Surgery, The Heart Center at Arnold Palmer Hospital for Children, Orlando, FL, USA.
authors.forename: I Ricardo
authors.initials: IR
authors.lastname: Argueta-Morales
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL, 32816, USA. alain.kassab@ucf.edu.
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Kassab
authors.affiliation: Department of Mechanical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Divo
authors.affiliation: College of Medicine, University of Central Florida, Orlando, FL, USA.|Division of Cardiothoracic Surgery, The Heart Center at Arnold Palmer Hospital for Children, Orlando, FL, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: DeCampli
mesh_terms: D002339:Carotid Arteries / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000098:blood supply*; D001026:Coronary Artery Bypass / Q000379:methods; D006353:Heart-Assist Devices; D057446:Hydrodynamics; D020767:Intracranial Thrombosis / Q000503:physiopathology*; D008955:Models, Cardiovascular
keywords: Computational fluid dynamics; In-vitro cardiovascular modeling; Left ventricular assist device; Stroke