title: Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve.
abstract: BACKGROUND
  Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.
  
  
  RESULTS
  An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.
  
  
  CONCLUSIONS
  We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.
authors.affiliation: Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering, University of Padua, Padua, Italy.
authors.forename: Francesca Maria
authors.initials: FM
authors.lastname: Susin
authors.affiliation: Department of Civil and Environmental Engineering, Sapienza University of Rome, Rome, Italy. stefania.espa@uniroma1.it.
authors.forename: Stefania
authors.identifier: http://orcid.org/0000-0002-2936-0136
authors.initials: S
authors.lastname: Espa
authors.affiliation: Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering, University of Padua, Padua, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Toninato
authors.affiliation: Department of Civil and Environmental Engineering, Sapienza University of Rome, Rome, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Fortini
authors.affiliation: Department of Civil, Environmental Engineering and Architecture, University of Cagliari, Cagliari, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Querzoli
mesh_terms: D001011:Aorta / Q000378:metabolism; D001021:Aortic Valve / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D006350:Heart Valve Prosthesis; D006461:Hemolysis; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011673:Pulsatile Flow / Q000502:physiology; D013314:Stress, Mechanical
keywords: Haemolysis index; Image velocimetry; Pulse duplicator; Valve leaflets dynamics