title: Evaluation of histological techniques for quantifying haemodialysis arteriovenous (AV) graft hyperplasia.
abstract: BACKGROUND
  Assessing treatment efficacies for preventing haemodialysis arteriovenous (AV) graft stenosis requires a reproducible method for quantifying intimal hyperplasia. We identified sources of variability in three histological methods for assessing hyperplasia in a porcine AV graft model.
  
  
  METHODS
  Carotid-jugular synthetic grafts were placed in pigs. After explantation at 3-6 weeks, the tissue was stained with haematoxylin and eosin (H&E), Masson's trichrome or elastic tissue Van Gieson (EVG) stains and examined histologically. Hyperplasia at the anastomosis of 14 grafts was quantified using three different methods, each by four blinded observers. These methods were visual scoring, ratio of intima-to-media surface area (I/M ratio), and ratio of intra-graft hyperplasia to graft surface area (H/G ratio) at the graft-vessel interface.
  
  
  RESULTS
  The EVG stain proved superior in delineation of the elastic lamina yet quantification of the intimal and medial layers was still often difficult. This is illustrated by the greater inter-observer median coefficient of variances (CV) found using the I/M ratio method (intimal area CV=13.7%; medial area CV=32.7%; I/M ratio CV=44.0%) than with the H/G method (intra-graft hyperplasia area CV=7.3%, graft area CV=5.3%; H/G ratio CV=6.9%) or by visual scoring (CV=26.8%). The H/G ratios correlated positively with visual scores (r=0.941; P=0.0007; n=14) and the I/M ratio (r=0.719; P=0.0095; n=14). While hyperplasia was seen in both native vessel and graft lumen, in only one of the 14 anastomoses was the degree of hyperplasia greater in the native vessel than in the graft lumen, suggesting that the degree of hyperplasia occurring within the graft lumen predicted the total hyperplasia around the anastomosis.
  
  
  CONCLUSIONS
  The H/G method for assessing hyperplasia is preferred in a porcine model of AV graft because it is quantitative, less variable and does not require the delineation of the elastic lamina, although it infrequently underestimates the total hyperplasia that occurs.
authors.affiliation: Department of Medicine, University of Utah and Medical Service, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, UT 84112-5350, USA. Christi.terry@hsc.utah.edu
authors.forename: Christi M
authors.initials: CM
authors.lastname: Terry
authors.forename: Donald K
authors.initials: DK
authors.lastname: Blumenthal
authors.forename: Sreevalli
authors.initials: S
authors.lastname: Sikharam
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kuji
authors.forename: Steven E
authors.initials: SE
authors.lastname: Kern
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Cheung
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects; D017536:Carotid Artery, Common / Q000166:cytology / Q000601:surgery*; D004547:Elastic Tissue / Q000473:pathology; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000473:pathology*; D006965:Hyperplasia; D007601:Jugular Veins / Q000473:pathology* / Q000601:surgery*; D011138:Polytetrafluoroethylene / Q000627:therapeutic use; D006435:Renal Dialysis / Q000009:adverse effects; D013194:Staining and Labeling / Q000379:methods*; D013552:Swine; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology
chemical_list: D011138:Polytetrafluoroethylene