title: Sovering annuloplasty rings: experimental pathology in the sheep model.
abstract: BACKGROUND
  A new flexible annuloplasty ring (Sovering, Sorin Biomedica Cardio), both closed and open, has been designed and consists of radiopaque silicone core impregnated with barium sulfate and covered by a knitted polyester fabric coated with Carbofilm. The aim of the study was to test the biological compatibility of the new device in large animals in orthotopic position.
  
  
  METHODS
  Ten Sovering rings were implanted in 10 female adult sheep, 7 mitral (3 open, 4 closed) and 3 tricuspid (all open). The size was 23-25 mm in the mitral and 28-30 mm in the tricuspid position, and the time in place varied from 63 to 110 days (mean = 89 +/- 14) and from 58 to 63 days (mean = 61 +/- 3), respectively. The morphological analysis consisted of gross, histological, immunohistochemical and ultrastructural investigations.
  
  
  RESULTS
  The prosthetic ring appeared well implanted in the valve atrioventricular (AV) junction, encapsulated by a thin fibrous sheath without any evidence of thrombus deposition, fibrinous lining or exuberant fibrous tissue overgrowth. No adverse inflammatory reaction was observed, but rare lymphocytes, macrophages and foreign body giant cells. At electron microscopy, the fibrous tissue appeared to permeate deeply within the fabric network; reendothelization on the surface was noted and confirmed by immunohistochemistry. Sirius red staining at polarized light revealed a higher content of collagen type III in the mitral than in the tricuspid position.
  
  
  CONCLUSIONS
  Sovering annuloplasty rings implanted in the AV valves of adult sheep showed excellent biocompatibility, fibrous encapsulation and reendothelization. The absence of thrombosis and exuberant fibrous tissue reaction supports the effective use of Carbofilm covering in annuloplasty devices.
authors.affiliation: Institute of Pathological Anatomy, University of Padua Medical School, Padua, Italy.
authors.forename: Mila
authors.initials: M
authors.lastname: Della Barbera
authors.forename: François
authors.initials: F
authors.lastname: Laborde
authors.forename: Gaetano
authors.initials: G
authors.lastname: Thiene
authors.forename: Valter
authors.initials: V
authors.lastname: Arata
authors.forename: Elena
authors.initials: E
authors.lastname: Pettenazzo
authors.forename: Enrico
authors.initials: E
authors.lastname: Pasquino
authors.forename: Luc
authors.initials: L
authors.lastname: Behr
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Valente
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D006348:Cardiac Surgical Procedures / Q000379:methods; D020099:Coated Materials, Biocompatible; D005260:Female; D006350:Heart Valve Prosthesis; D008855:Microscopy, Electron, Scanning; D008943:Mitral Valve / Q000473:pathology* / Q000648:ultrastructure; D023421:Models, Animal; D011474:Prosthesis Design; D012756:Sheep; D014261:Tricuspid Valve / Q000473:pathology* / Q000648:ultrastructure
chemical_list: D020099:Coated Materials, Biocompatible