title: Closure of the pericardium using synthetic bioabsorbable polymers.
abstract: BACKGROUND
  Pericardial substitutes are known to ensure safer resternotomy at reoperation. A synthetic sheet made from expanded-polytetrafluoroethylene (e-PTFE) has been most commonly used as a pericardial substitute. The e-PTFE sheet, however, can induce severe inflammatory reaction and diffuse fibrosis. This study was designed to investigate the absorption rate and tissue reaction associated with two absorbable pericardial substitutes: a gelatin sheet and L-lactic acid-epsilon-caprolactone copolymer (L-C copolymer). In addition, e-PTFE sheet and autologous pericardium were used as controls.
  
  
  METHODS
  Sixty dogs were divided into four groups of 15. In group A, a 3 x 3 cm segment of pericardium was excised, and the autologous pericardium was resutured. In group B, the pericardial defect was replaced with gelatin sheet. In group C, the defect was replaced with L-C copolymer sheet. In group D, the defect was replaced with e-PTFE sheet. For each group, the implanted membranes were retrieved at 2 weeks (n = 1), 4 weeks (n = 3), 12 weeks (n = 5), and 24 weeks (n = 6) after implantation.
  
  
  RESULTS
  The e-PTFE sheet produced severe adhesions to the heart and pleura and a more prominent inflammatory reaction, as compared with the gelatin sheet. The absorbable pericardial substitutes were completely absorbed by 24 weeks after implantation, and were replaced with fibrous membrane.
  
  
  CONCLUSIONS
  Gelatin sheet may involve less adhesion and a reduced inflammatory reaction compared with e-PTFE.
authors.affiliation: Department of Cardiovascular Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan. ksakuma@mail.tains.tohoku.ac.jp
authors.forename: Kei
authors.initials: K
authors.lastname: Sakuma
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iguchi
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Ikada
authors.forename: Koichi
authors.initials: K
authors.lastname: Tabayashi
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D004285:Dogs; D017254:Leukemic Infiltration / Q000139:chemically induced; D010496:Pericardium / Q000601:surgery*; D011091:Polyesters / Q000627:therapeutic use*; D011138:Polytetrafluoroethylene / Q000009:adverse effects*
chemical_list: D011091:Polyesters; C062968:lactide-caprolactone copolymer; D011138:Polytetrafluoroethylene