title: Hancock II bioprosthesis: a glance at the microscope in mid-long-term explants.
abstract: OBJECTIVE
  The Hancock II bioprosthesis is a second-generation porcine valve xenograft treated with the detergent sodium dodecyl sulphate (T6) to retard calcification. The aim of this investigation was to study the gross and microscopic features in Hancock II explants to assess the structural changes occurring with time.
  
  
  METHODS
  Among 1382 Hancock II bioprostheses (701 isolated aortic, 421 isolated mitral, 130 double) implanted from 1983 to 1997 in 1252 patients, 22 (16 mitral, 6 aortic) were removed at reoperation until 1999 and were available for pathological investigation: infective endocarditis occurred in 5 and structural deterioration in 8, whereas in the remaining 9 xenografts reoperation was performed for nonstructural valve deterioration (paravalvular leak in 4 and prophylactic replacement in 5). Morphological investigation consisted of gross examination and x-ray, histologic, immunohistochemistry, electron microscopic, and atomic absorption spectroscopic examination.
  
  
  RESULTS
  The cause of structural valve deterioration was dystrophic calcification in 4 cases (1 aortic, 3 mitral; range of time graft was in place, 101 to 144 months), non-calcium-related tears in 3 cases (all mitral, range 121 to 163 months), and commissural dehiscence in 1 (aortic, range 156 months). Five of the nonstructural valve deterioration explants (range 42 to 122 months) showed only pinpoint mineralization at the commissures. Mean calcium content in nonstructural deterioration explants was 14.70 +/- 22.33 versus 99.11 +/- 81.52 mg/g in explants with structural valve deterioration. Electron microscopic examination showed early nuclei of mineralization mostly consisting of calcospherulae upon cell debris. Local or diffuse lipid insudation was observed in all but 2 explants and consisted of cholesterol clefts, lipid droplets, and lipid-laden macrophages featuring foam cells. The lipid insudation was the most plausible cause of tearing in 2 explants.
  
  
  CONCLUSIONS
  These pathologic findings support the clinical results of a delayed occurrence of structural failure of Hancock II bioprostheses and a mitigation of mineralization by the anti-calcification treatment. However, other factors such as lipid insudation may come into play in the long term.
authors.affiliation: Department of Cardiovascular Surgery, University of Padua Medical School, Italy.
authors.forename: Tomaso
authors.initials: T
authors.lastname: Bottio
authors.forename: Gaetano
authors.initials: G
authors.lastname: Thiene
authors.forename: Elena
authors.initials: E
authors.lastname: Pettenazzo
authors.forename: Paolo
authors.initials: P
authors.lastname: Ius
authors.forename: Uberto
authors.initials: U
authors.lastname: Bortolotti
authors.forename: Giulio
authors.initials: G
authors.lastname: Rizzoli
authors.forename: Carlo
authors.initials: C
authors.lastname: Valfré
authors.forename: Dino
authors.initials: D
authors.lastname: Casarotto
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Valente
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000473:pathology / Q000601:surgery; D001705:Bioprosthesis; D002114:Calcinosis / Q000473:pathology / Q000601:surgery; D004389:Durable Medical Equipment; D005260:Female; D006349:Heart Valve Diseases / Q000473:pathology / Q000601:surgery; D006350:Heart Valve Prosthesis; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D008943:Mitral Valve / Q000473:pathology / Q000601:surgery; D011474:Prosthesis Design / Q000295:instrumentation; D011475:Prosthesis Failure; D013057:Spectrum Analysis; D013997:Time Factors; D016896:Treatment Outcome