title: Pulmonary root replacement with the Freestyle stentless aortic xenograft in growing pigs.
abstract: BACKGROUND
  The stentless xenograft with its favorable hemodynamic performance on the left side of the heart seems an attractive, readily available alternative for the reconstruction of the right ventricular outflow tract in children.
  
  
  METHODS
  To assess its function in a preclinical animal investigation, we replaced the pulmonary root with a Freestyle stentless aortic xenograft in 18 piglets of 26.6 +/- 3.2 kg weight. The animals were allowed to grow as much as possible and slaughtered when symptoms of heart failure developed or body weight reached more than 160 kg. All valve explants were analyzed by gross examination and photography and, in 4 representative pigs, by histologic examination.
  
  
  RESULTS
  Fourteen animals died prematurely after 2 weeks to 11 months. Twelve xenograft explants showed thick, immobilized, large nodular structures as cuspal remnants causing significant stenosis. At microscopy, large cuspal masses of degenerating collagen and fibrin and various inflammatory cells were frequently found. In the growing pig, most of the xenografts implanted in the pulmonary position showed early degeneration causing severe stenosis.
  
  
  CONCLUSIONS
  Use of this valve for right ventricular outflow tract reconstruction in children cannot be recommended.
authors.affiliation: Department of Cardiac Surgery, University Hospital Leiden, The Netherlands. PSchoof@thorax.azl.nl
authors.forename: P H
authors.initials: PH
authors.lastname: Schoof
authors.forename: M G
authors.initials: MG
authors.lastname: Hazekamp
authors.forename: H H
authors.initials: HH
authors.lastname: van Krieken
authors.forename: H A
authors.initials: HA
authors.lastname: Huysmans
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000637:transplantation; D001705:Bioprosthesis; D001835:Body Weight; D002114:Calcinosis / Q000473:pathology; D002303:Cardiac Output, Low / Q000209:etiology; D002423:Cause of Death; D003094:Collagen / Q000648:ultrastructure; D003251:Constriction, Pathologic / Q000473:pathology; D004195:Disease Models, Animal; D004696:Endocarditis / Q000473:pathology; D005337:Fibrin / Q000648:ultrastructure; D006128:Growth; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011664:Pulmonary Valve / Q000601:surgery*; D013499:Surface Properties; D013552:Swine
chemical_list: D005337:Fibrin; D003094:Collagen