title: Histologic analysis of stent graft oversizing in the thoracic aorta.
abstract: OBJECTIVE
  To elucidate the histologic changes after stent graft oversizing in nonatherosclerotic aortas using an experimental porcine model. We previously reported that the diameter and angulation of the aorta in this model are similar to those in young individuals who undergo stent graft repair for blunt aortic injuries. The lack of commercially available stent grafts specific for repairing blunt aortic injuries, particularly for small and angulated aortas, may be related to the high rate of endograft complications in this population.
  
  
  METHODS
  Twenty-five pigs were randomized into one control group (without stent graft implantation) and four oversized groups (A: 10%-19%, B: 20%-29%, C: 30%-39%, and D: >40%). Three circumferential fragments were collected from the aorta for histologic and immunohistochemical studies. Morphometric analyzes were performed using an inflow system and image analysis software (Quantimet 500; Leica Cambridge Ltd, Cambridge, UK).
  
  
  RESULTS
  Collagen expression in the aortic wall was not significantly different among the five groups (P = .5604). There were significantly fewer muscle fibers in the aortic wall in the oversized groups compared with the control group (P = .000198). The proportion of elastic fibers in the aortic wall was significantly smaller in the oversized groups compared with the control group (P = .0000001). Immunohistochemical analysis showed that α-actin expression in the aortic wall was significantly decreased in the oversized groups compared with the control group (P = .002031). There were no significant differences in either the number of muscle fibers or α-actin expression among the four oversized groups.
  
  
  CONCLUSIONS
  Histologic and immunohistochemical studies confirmed the structural disarrangement of the aortic wall after insertion of an endoprosthesis, including reduced number of muscle and elastic fibers.
authors: Hospital Israelita Albert Einstein, Centro de Experimentação e Treinamento em Cirurgia, University of São Paulo Medical School, São Paulo, Brazil; Department of Surgical Technique and Experimental Surgery, University of São Paulo Medical School, São Paulo, Brazil. Electronic address: igorsincos@usp.br.
authors: Igor Rafael
authors: IR
authors: Sincos
authors: Erasmo Simão
authors: ES
authors: da Silva
authors: Sergio Quilici
authors: SQ
authors: Belczak
authors: Anna Paula Weinhardt
authors: AP
authors: Baptista Sincos
authors: Maria
authors: M
authors: de Lourdes Higuchi
authors: Vitor
authors: V
authors: Gornati
authors: José Piñatas
authors: JP
authors: Otoch
authors: Ricardo
authors: R
authors: Aun
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000293:injuries / Q000473:pathology* / Q000601:surgery; D001027:Aortography; D001807:Blood Vessel Prosthesis; D004195:Disease Models, Animal; D057510:Endovascular Procedures / Q000379:methods*; D007150:Immunohistochemistry; D011474:Prosthesis Design; D015607:Stents; D013314:Stress, Mechanical; D013552:Swine; D014057:Tomography, X-Ray Computed; D057772:Vascular System Injuries / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*