title: Preclinical hemodynamic assessment of a new trileaflet mechanical valve in the aortic position in a bovine model.
abstract: OBJECTIVE
  The hemodynamic characteristics of a new trileaflet mechanical heart valve (TTV) (TriFlo Inc., Costa Mesa, CA, USA) in the aortic position were evaluated in a bovine model. The TTV was designed to combine the durability of mechanical heart valves with the central flow characteristics of a bioprosthesis.
  
  
  METHODS
  Using nine calves, the native aortic valve was replaced with a 21-mm TTV (n = 6) or a St. Jude Medical (SJM) valve (n = 3). Hemodynamic values were assessed with echocardiography at implantation and with catheterization at explantation. All calves underwent a necropsy, followed by gross pathology and light microscopy studies.
  
  
  RESULTS
  The mean implant duration was 159 +/- 55 days for the TTV and 102 +/- 67 days for the SJM valve. Immediately before euthanasia, the peak and mean pressure gradients were respectively 35 +/- 14 and 24 +/- 9 mmHg for the TTV, and 100 +/- 72 and 59 +/- 38 mmHg for the SJM valve (p = 0.03). Two of the SJM-valve animals were electively sacrificed after showing symptoms of aortic stenosis. At necropsy, all nine valves were free from thrombi, pannus, occlusive tissue, or mechanical impairment of leaflet motion. The prematurely sacrificed SJM-valve animals had concentric myocardial hypertrophy consistent with severe functional aortic stenosis.
  
  
  CONCLUSIONS
  The significantly higher gradients and left ventricular hypertrophy in the SJM-valve animals were related to a smaller effective orifice area, which precluded adaptation to increasing transvalvular volumes in the growing animal. This problem was not seen with the TTV, which performed hemodynamically as well as the SJM valve. The high transvalvular gradients seen with the SJM valve at study end may suggest that the hemodynamic characteristics of the TTV may be superior, though additional studies are needed to confirm this.
authors.affiliation: Cardiovascular Surgical Research Laboratory, Texas Heart Institute, Houston, Texas 77030, USA.
authors.forename: Igor D
authors.initials: ID
authors.lastname: Gregoric
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Eya
authors.forename: Daniel
authors.initials: D
authors.lastname: Tamez
authors.forename: Roberto
authors.initials: R
authors.lastname: Cervera
authors.forename: Denise
authors.initials: D
authors.lastname: Byler
authors.forename: Jeff
authors.initials: J
authors.lastname: Conger
authors.forename: Egemen
authors.initials: E
authors.lastname: Tuzun
authors.forename: Hyun Keun
authors.initials: HK
authors.lastname: Chee
authors.forename: Fred J
authors.initials: FJ
authors.lastname: Clubb
authors.forename: Kamuran
authors.initials: K
authors.lastname: Kadipasaoglu
authors.forename: O H
authors.initials: OH
authors.lastname: Frazier
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000209:etiology; D002417:Cattle; D004195:Disease Models, Animal; D004452:Echocardiography; D004562:Electrocardiography; D019544:Equipment Failure Analysis; D006350:Heart Valve Prosthesis; D006439:Hemodynamics / Q000502:physiology*; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000209:etiology; D008955:Models, Cardiovascular; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology; D011474:Prosthesis Design; D017755:Prosthesis Fitting