title: Kangaroo versus freestyle stentless bioprostheses in a juvenile sheep model: hemodynamic performance and calcification behavior.
abstract: BACKGROUND
  Glutaraldehyde-preserved bioprosthetic heart valve substitutes have limited performance and longevity due to tissue degeneration and calcification. The Freestyle valve (Medtronic Heart Valves, Inc, Minneapolis, MN) combines zero fixation pressure and proportional, variant-amino oleic acid (AOA) as antidegeneration and antimineralization measures. The aim of this study was to compare the calcification behavior of glutaraldehyde-preserved kangaroo aortic valves with Freestyle stentless bioprostheses in a juvenile sheep model.
  
  
  METHODS
  Pulmonary artery and valve replacements were performed in juvenile sheep with Freestyle stentless aortic valves (n = 4) or glutaraldehyde-preserved kangaroo stentless aortic valves with no antimineralization measures (n = 6), and explanted at 200 postoperative days.
  
  
  RESULTS
  Freestyle stentless valves and stentless kangaroo aortic valves showed normal valve function immediately postoperatively and up to 120 days. Valve leaflets of all valves were macroscopically free of visible calcification with normal histology. Valve leaflet calcification (microg Ca/mg tissue) was less in kangaroo than Freestyle (1.27 +/- 0.43 versus 2.38 +/- 1.37, p = 0.856). Aortic wall tissue calcification was severe in kangaroo and Freestyle (127.93 +/- 12.22 versus 122.19 +/- 11.99, p = 0.596).
  
  
  CONCLUSIONS
  We conclude that glutaraldehyde-preserved kangaroo aortic valve leaflets are equal to AOA-treated Freestyle stentless valve leaflets with regard to calcification in juvenile sheep. Both bioprostheses are prone to aortic wall calcification. The low calcification features of the kangaroo aortic valve leaflets without antimineralization treatment may benefit the longevity of the valve.
authors.affiliation: Fremantle Heart Institute, Department of Cardiothoracic Surgery, and University of Western Australia, Fremantle Hospital, Alma Street, Fremantle 6160, Western Australia. Leon.Neethling@health.wa.gov.au
authors.forename: William M L
authors.initials: WM
authors.lastname: Neethling
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hodge
authors.forename: Ross
authors.initials: R
authors.lastname: Glancy
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000503:physiopathology* / Q000637:transplantation*; D001705:Bioprosthesis; D002114:Calcinosis; D004195:Disease Models, Animal; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D008297:Male; D011474:Prosthesis Design; D012756:Sheep; D016896:Treatment Outcome