title: Simulations of morphotype-dependent hemodynamics in non-dilated bicuspid aortic valve aortas.
abstract: Bicuspid aortic valves (BAVs) generate flow abnormalities that may promote aortopathy. While positive helix fraction (PHF) index, flow angle (θ), flow displacement (d) and wall shear stress (WSS) exhibit abnormalities in dilated BAV aortas, it is unclear whether those anomalies stem from the abnormal valve anatomy or the dilated aorta. Therefore, the objective of this study was to quantify the early impact of different BAV morphotypes on aorta hemodynamics prior to dilation. Fluid-structure interaction models were designed to quantify standard peak-systolic flow metrics and temporal WSS characteristics in a realistic non-dilated aorta connected to functional tricuspid aortic valve (TAV) and type-I BAVs. While BAVs generated increased helicity (PHF>0.68) in the middle ascending aorta (AA), larger systolic flow skewness (θ>11.2°) and displacement (d>6.8mm) relative to the TAV (PHF=0.51; θ<5.5°; d<3.3mm), no distinct pattern was observed between morphotypes. In contrast, WSS magnitude and directionality abnormalities were BAV morphotype- and site-dependent. Type-I BAVs subjected the AA convexity to peak-systolic WSS overloads (up to 1014% difference vs. TAV). While all BAVs increased WSS unidirectionality on the proximal AA relative to the TAV, the most significant abnormality was achieved by the BAV with left-right-coronary cusp fusion on the wall convexity (up to 0.26 decrease in oscillatory shear index vs. TAV). The results indicate the existence of strong hemodynamic abnormalities in non-dilated type-I BAV AAs, their colocalization with sites vulnerable to dilation and the superior specificity of WSS metrics over global hemodynamic metrics to the valve anatomy.
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Cao
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA.
authors.forename: Samantha K
authors.initials: SK
authors.lastname: Atkins
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: McNally
authors.affiliation: Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, USA.
authors.forename: Janet
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, USA. Electronic address: philippe.sucosky@wright.edu.
authors.forename: Philippe
authors.initials: P
authors.lastname: Sucosky
mesh_terms: D001011:Aorta / Q000502:physiology*; D001018:Aortic Diseases / Q000503:physiopathology; D001021:Aortic Valve / Q000002:abnormalities* / Q000033:anatomy & histology / Q000502:physiology; D000082882:Bicuspid Aortic Valve Disease; D006349:Heart Valve Diseases; D006439:Hemodynamics; D006801:Humans; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D014261:Tricuspid Valve / Q000502:physiology
keywords: Aorta; Aortic disease; Bicuspid aortic valve; Hemodynamic stress; Hemodynamics