title: Pathology of explanted polytetrafluoroethylene vascular grafts.
abstract: BACKGROUND
  Graft occlusion is a well-documented etiology for arteriovenous fistulae failure. However, there is little morphologic information elucidating why synthetic vascular grafts fail. The purpose of this study was to examine the tissue responses occurring within and adjacent to explanted polytetrafluoroethylene grafts that were utilized during cardiovascular procedures and subsequently removed.
  
  
  METHODS
  Forty explanted polytetrafluoroethylene grafts (including 32 failed vascular grafts) originating from 18 females and 22 males who ranged in age from 6 to 82 years (mean age, 36 years) were evaluated. Duration of engraftment varied from 1 to 255 months (mean engraftment period, 64 months).
  
  
  RESULTS
  In addition to neointimal hyperplasia, foreign body reaction, and thrombosis, an unexpected finding was calcification involving the graft material, as well as luminal thrombus and adjacent soft tissues. Twenty-seven of forty cases (68%) showed evidence of calcification, either within or adjacent to polytetrafluoroethylene grafts. Histologic examination revealed variable degrees and patterns of calcification within and adjacent to explanted polytetrafluoroethylene membranes and conduits (arterial, arteriovenous, or cardiac grafts). A significantly longer duration of engraftment (P=.015) was identified in calcified versus noncalcified polytetrafluoroethylene materials. Patient age, serum calcium, creatinine level, and blood urea nitrogen level showed no statistically significant differences between patients with calcified grafts and patients without calcified grafts.
  
  
  CONCLUSIONS
  Interstitial calcification is frequently found within explanted polytetrafluoroethylene grafts and is associated with graft disruption. These findings suggest that calcification of polytetrafluoroethylene biomaterials may play a role in eventual graft failure. A better understanding of the process of polytetrafluoroethylene graft calcification may lead to novel therapies that aid in the prevention of polytetrafluoroethylene vascular graft failure.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California-Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA. rmehta@mednet.ucla.edu
authors.forename: Rupal I
authors.initials: RI
authors.lastname: Mehta
authors.forename: Arnob K
authors.initials: AK
authors.lastname: Mukherjee
authors.forename: Tyler D
authors.initials: TD
authors.lastname: Patterson
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fishbein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects; D001672:Biocompatible Materials; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D002114:Calcinosis / Q000209:etiology / Q000473:pathology; D002648:Child; D019544:Equipment Failure Analysis; D005260:Female; D005355:Fibrosis; D015726:Giant Cells / Q000473:pathology; D006801:Humans; D008297:Male; D008679:Metaplasia; D008875:Middle Aged; D058426:Neointima / Q000209:etiology / Q000473:pathology; D011138:Polytetrafluoroethylene; D011475:Prosthesis Failure; D013927:Thrombosis / Q000209:etiology / Q000473:pathology; D013997:Time Factors; D014657:Vasculitis / Q000209:etiology / Q000473:pathology; D055815:Young Adult
chemical_list: D001672:Biocompatible Materials; D011138:Polytetrafluoroethylene