title: A randomized assessment of an advanced tissue preservation technology in the juvenile sheep model.
abstract: BACKGROUND
  Despite improved anticalcification technology, bioprosthetic heart valves still cannot be used in younger patients because of progressive structural valve degeneration. A novel advanced tissue preservation technology was developed that uses stable functional group capping and preservation by glycerolization. Valves incorporating this novel technology can be stored in a dry condition and do not require rinsing before use. The aim of the study was to assess the effects of this new technology in terms of valve function and durability in a chronic sheep model of orthotopic implantation.
  
  
  METHODS
  Forty-five juvenile sheep were randomized and either a Perimount mitral valve (6900P, control group) or the same valve design incorporating the novel tissue preservation technology (test group) was implanted in the mitral position. All valves were 25 mm. A transthoracic echocardiography was performed at 1 week and at 8 months postoperatively. The animals were then killed, an autopsy was performed, and the valves were examined radiographically (soft tissue radiograph), histologically (hematoxylin and eosin and Von Kossa staining), and chemically (calcium content). Exclusion criteria for analysis included surgical or procedural death, bacterial endocarditis or other diseases leading to premature death.
  
  
  RESULTS
  Thirty-one animals (14 controls and 17 test animals) remained in perfect condition during the 8-month follow-up period. Echocardiography at 1 week showed normal valve function in both groups. At 8 months, cardiac output increased significantly to the same extent in both groups (vs baseline; P < .01). The mean transvalvular pressure gradient also increased but significantly more in the control group compared with the test group (P = .03). Flow turbulence across the prosthesis was increased in the control valves compared with the test valves. The test valves had significantly less calcium content than the controls (1.9 ± 0.3 vs 6.8 ± 1.6 μg/mg; P = .002). This was confirmed by radiographic analysis and histology.
  
  
  CONCLUSIONS
  This study demonstrates that the novel tissue preservation technology, when applied to the Perimount mitral valve, significantly improves hemodynamic and anticalcification properties compared with the standard Perimount, a valve currently considered the standard of care.
authors.affiliation: Laboratory of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
authors.affiliation: Laboratory of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Hadewich
authors.initials: H
authors.lastname: Hermans
authors.affiliation: Laboratory of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Verbeken
authors.affiliation: Laboratory of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, Katholieke Universiteit Leuven, Leuven, Belgium. Electronic address: bart.meuris@uzleuven.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Meuris
mesh_terms: D000367:Age Factors; D000818:Animals; D001705:Bioprosthesis; D002114:Calcinosis / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D002118:Calcium / Q000378:metabolism; D005260:Female; D005990:Glycerol / Q000494:pharmacology*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006439:Hemodynamics; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D023421:Models, Animal; D011474:Prosthesis Design; D011859:Radiography; D011897:Random Allocation; D012756:Sheep; D013997:Time Factors; D014021:Tissue Preservation / Q000379:methods*; D014463:Ultrasonography
chemical_list: D005990:Glycerol; D002118:Calcium