title: Aortic valve re-replacement after Bentall procedure with a biological valved conduit in a sheep model.
abstract: OBJECTIVE
  The Bentall procedure is the 'gold standard' for the repair of a combined pathology of ascending aorta and aortic valve. Because there is no need for long-term anticoagulation, biological-valved conduits have become increasingly popular; however, the possible need for reoperation due to valve degeneration is a major disadvantage. The aim of this animal-based study was to prove the feasibility of an isolated replacement of the aortic valve prosthesis six months after a previous implantation of a biological valved conduit (BioValsalva) in a sheep model. A total aortic root replacement, using the BioValsalva conduit, was performed in 10 juvenile sheep. After six months, the surviving sheep were reoperated on, and the stentless valve was replaced with a stented biological valve placed inside the previously implanted vascular conduit.
  
  
  RESULTS
  Five animals survived the initial implantation of a BioValsalva conduit. During reoperation, the triple-layered vascular graft with polytetrafluoroethylene on the outside showed only slight adhesions with the surrounding tissue. The stentless valve was removed in one piece, after which a new stented valve was implanted inside the conduit. An X-radiographic examination of the explanted valve showed moderate calcification of the leaflet, and severe calcification of the aortic wall.
  
  
  CONCLUSIONS
  The results of this animal study confirmed that a degenerated stentless biological valve inside the BioValsalva conduit could be replaced with a new valve, without having to remove the entire conduit.
authors.affiliation: Department of Cardiothoracic, Transplantation, and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Hassina
authors.initials: H
authors.lastname: Baraki
authors.forename: Igor
authors.initials: I
authors.lastname: Tudorache
authors.forename: Klaus
authors.initials: K
authors.lastname: Hoeffler
authors.forename: Nawid
authors.initials: N
authors.lastname: Khaladj
authors.forename: Christian
authors.initials: C
authors.lastname: Hagl
authors.forename: Serghei
authors.initials: S
authors.lastname: Cebotari
authors.forename: Axel
authors.initials: A
authors.lastname: Haverich
authors.forename: Malakh
authors.initials: M
authors.lastname: Shrestha
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology / Q000601:surgery*; D001021:Aortic Valve / Q000473:pathology / Q000601:surgery*; D001705:Bioprosthesis / Q000009:adverse effects / Q000592:standards; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D002114:Calcinosis / Q000209:etiology / Q000601:surgery*; D002985:Clinical Protocols; D004195:Disease Models, Animal; D005240:Feasibility Studies; D006350:Heart Valve Prosthesis / Q000009:adverse effects / Q000592:standards; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D012086:Reoperation / Q000295:instrumentation / Q000379:methods; D012756:Sheep; D016896:Treatment Outcome