title: Calcification of allograft and stentless xenograft valves for right ventricular outflow tract reconstruction: an experimental study in adolescent sheep.
abstract: OBJECTIVE
  Aortic homografts were compared with pulmonary homografts in the setting of right ventricular outflow tract reconstruction in adolescent sheep. Furthermore, clinically available stentless porcine and bovine xenografts were studied as an alternative to homografts.
  
  
  METHODS
  In 51 adolescent sheep cryopreserved aortic and pulmonary (ovine) homografts, as well as 6 different types of clinically available stentless bioprostheses (Prima Plus, Toronto SPV, Toronto BiLinx, Freestyle, Pericarbon Stentless, and Contegra) were implanted in the pulmonary position. After 5 to 6 months, the valves were explanted and studied for structural valve degeneration by means of radiographic analysis, histology, and calcium content determination.
  
  
  RESULTS
  Pulmonary homografts calcified significantly less than aortic homografts in the wall portion. Leaflet calcification was mild, hardly detectable on radiographic analysis, and comparable between aortic and pulmonary homografts. Stentless porcine xenografts showed severe calcification in the aortic wall portion, irrespective of the antimineralization treatment. Leaflet calcification was mild and in the range of that seen in homografts. Pannus formation was present but never induced leaflet retraction or cusp immobilization. Calcification was absent in the stentless Pericarbon valve implants, but all valves showed extensive pannus overgrowth, leaflet retraction, and cusp immobilization. The Contegra valves showed wall calcification, but the leaflets were completely free of calcification and pannus.
  
  
  CONCLUSIONS
  For right ventricular outflow tract reconstruction, the pulmonary homograft remains the first choice. All xenografts result in either calcific degeneration or cusp immobilization.
authors.affiliation: Laboratory for Experimental Cardiac Surgery, Department of Cardiovascular Diseases, Katholieke Universiteit Leuven, Leuven, Belgium. willem.flameng@med.kuleuven.be
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
authors.forename: Ramadan
authors.initials: R
authors.lastname: Jashari
authors.forename: Geofrey
authors.initials: G
authors.lastname: De Visscher
authors.forename: Lindsay
authors.initials: L
authors.lastname: Mesure
authors.forename: Bart
authors.initials: B
authors.lastname: Meuris
mesh_terms: D000367:Age Factors; D000818:Animals; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D001705:Bioprosthesis; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D015925:Cryopreservation; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006352:Heart Ventricles / Q000601:surgery*; D008297:Male; D011474:Prosthesis Design; D011664:Pulmonary Valve / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D011859:Radiography; D012720:Severity of Illness Index; D012756:Sheep; D013997:Time Factors; D014184:Transplantation, Homologous / Q000009:adverse effects
chemical_list: D002118:Calcium