title: In-vitro investigation of the hemodynamics of the Edwards Sapien transcatheter heart valve.
abstract: OBJECTIVE
  The study aim was to evaluate the hemodynamic performance of the Sapien transcatheter heart valve (THV) in the ascending aorta, and its influence on the aortic wall in an in-vitro set-up.
  
  
  METHODS
  A two-dimensional particle image velocimetry (2D-PIV) study was conducted to evaluate the hemodynamic performance of the Edwards Sapien THV in the aortic flow field (image rate 15 Hz). The prosthesis (diameter 23 mm) was placed inside a mock aorta under pulsatile flow conditions. The velocities, shear strength, vorticity and strain rate were obtained and calculated with a fixed frequency (70 Hz) at constant stroke volume (70 ml).
  
  
  RESULTS
  The Sapien THV showed a jet flow-type profile with a maximum velocity of 0.87 +/- 0.16 m/s during peak flow phase (PFP). The jet flow was surrounded by ambilateral vortices with a higher percentage of counterclockwise than clockwise vorticity (335 +/- 66/s versus 277 +/- 44.1/s), analogous to the strain rate (261 +/- 55/s for elongation versus -168 +/- 25/s for contraction). The maximum shear strength was 26,284 +/- 11,550/s2, while the point-of-interest analysis revealed a higher velocity for the bottom aortic wall compared to the upper aortic wall (0.25 +/- 0.05 m/s versus 0.30 +/- 0.04 m/s; p = 0.014). All values were lower during the acceleration and deceleration phases compared to PFP.
  
  
  CONCLUSIONS
  The peak flow of the Sapien THV seems to be slightly higher than that of the native aortic valve, thus imitating near-physiological conditions. That the shear strength, vorticity and strain rate were high during peak flow phase, but low during other phases, might also have an influence on the aortic wall.
authors.affiliation: Department of Mechanics and Robotics, University Duisburg-Essen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Stühle
authors.forename: Daniel
authors.initials: D
authors.lastname: Wendt
authors.forename: Guojun
authors.initials: G
authors.lastname: Houl
authors.forename: Hermann
authors.initials: H
authors.lastname: Wendt
authors.forename: Marc
authors.initials: M
authors.lastname: Schlamann
authors.forename: Matthias
authors.initials: M
authors.lastname: Thielmann
authors.forename: Heinz
authors.initials: H
authors.lastname: Jakob
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kowalczyk
mesh_terms: D001011:Aorta / Q000502:physiology*; D001783:Blood Flow Velocity; D003187:Compliance; D006350:Heart Valve Prosthesis; D006439:Hemodynamics; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D011474:Prosthesis Design; D011673:Pulsatile Flow; D012212:Rheology; D013314:Stress, Mechanical