title: Valve thrombosis following transcatheter aortic valve replacement: significance of blood stasis on the leaflets.
abstract: OBJECTIVE
  Leaflet thrombosis following transcatheter aortic valve replacement (TAVR) and valve-in-valve (ViV) procedures has been increasingly recognized. However, the factors affecting the post-TAVR/ViV thrombosis are not fully understood. This study aimed to investigate the effect of the geometric confinement of transcatheter aortic valve (TAV) on blood residence time (BRT) on the TAV leaflets and in turn on the post-TAVR valve thrombosis.
  
  
  METHODS
  Two computational models, representing a surgical bioprosthesis and a TAV, were developed to study the effect of the geometric confinement on BRT on the leaflets in ViV setting/TAVR Intra-annular positioning. 3D flow fields were obtained via a one-way fluid-solid interaction modelling approach validated by experimental testing. BRT was compared between the two models by quantification and statistical analysis of the residence time of randomly distributed particles in close proximity of the leaflets.
  
  
  RESULTS
  Significantly longer BRT on the leaflets was observed in the TAV compared to the surgical valve during different stages of the cardiac cycle. During forward flow, the mean value of BRT was found to be 39% higher in the TAV compared to the surgical bioprosthesis ( P <  0.0001). During diastole, specifically from end-systole to mid-diastole and from mid-diastole to the beginning of systole, the amount by which the mean BRT was higher for TAV compared to the surgical valve was 150% and 40%, respectively ( P <  0.0005).
  
  
  CONCLUSIONS
  The geometric confinement of TAV by the failed bioprosthesis or the calcified native valve increases the BRT on the TAV leaflets. This may act as a permissive factor in valve thrombosis.
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
authors.forename: Koohyar
authors.initials: K
authors.lastname: Vahidkhah
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Barakat
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Abbasi
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Javani
authors.affiliation: Division of Cardiovascular Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Peyman N
authors.initials: PN
authors.lastname: Azadani
authors.affiliation: Division of Cardiovascular Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Anwar
authors.initials: A
authors.lastname: Tandar
authors.affiliation: Division of Cardiology, University of Washington, Seattle, WA, USA.
authors.forename: Danny
authors.initials: D
authors.lastname: Dvir
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
authors.forename: Ali N
authors.initials: AN
authors.lastname: Azadani
mesh_terms: D001021:Aortic Valve / Q000503:physiopathology / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000503:physiopathology*; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D013927:Thrombosis / Q000503:physiopathology*; D065467:Transcatheter Aortic Valve Replacement / Q000009:adverse effects*
keywords: Blood residence time; Thrombosis ; Transcatheter heart valve replacement ; Valve-in-valve 