title: [Turbulence and high intensity transient signals (HITS) as a parameter for optimum orientation of mechanical heart valves].
abstract: BACKGROUND
  In previous studies, the impact of valve orientation on the hemodynamic performance of mechanical aortic valves has been demonstrated. This study investigates Turbulence (RNS values) and High Intensity Transient Signals (HITS) as a new and objective parameter for hemodynamics in various orientations of Medtronic Hall (MH) and St. Jude Medical (SJM) aortic valves.
  
  
  METHODS
  Rotation devices carrying a MH or SJM valve were implanted into four pigs. The device allowed valve rotation without reopening the aorta. In various orientations, turbulent shear stresses (RNS values) and HITS were measured.
  
  
  RESULTS
  RNS and HITS changed for both valve designs in the different orientations, with superior results for the MH in the hemodynamically best orientation. Downstream turbulence (RNS) and HITS varied in the same direction, but a one to one correlation was not observed.
  
  
  CONCLUSIONS
  RNS and HITS vary with respect to valve orientation and design with superior results for the tilting disc valve. Both MH and SJM valves showed lower turbulence and HITS counts in their hemodynamically best orientations. HITS were related to downstream turbulence and the hemodynamic performance of the mechanical aortic valves.
authors.affiliation: Herz-Kreislauf-Klinik Bevensen, Herz- und Thoraxchirurgie, Römstedter Str. 25, 29549 Bad Bevensen, Germany. M.Perthel@t-online.de
authors.forename: M
authors.initials: M
authors.lastname: Perthel
authors.forename: J M
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: H
authors.initials: H
authors.lastname: Nygaard
authors.forename: W
authors.initials: W
authors.lastname: Kupper
authors.forename: J
authors.initials: J
authors.lastname: Laas
mesh_terms: D000818:Animals; D001021:Aortic Valve; D006350:Heart Valve Prosthesis / Q000592:standards; D006439:Hemodynamics; D013552:Swine