Histopathological reaction of the abdominal aorta wall to non-drug eluting stents

Objective: To evaluate the histopathological reaction of the abdominal aorta wall in pigs’ renal arteries to the presence of non-covered stainless steel stents. Methods: The abdominal aorta of ten pigs (6 months old and weighing 86.6 kg on average) was histopathologically studied 100 days after the implant of stainless steel stents in the abdominal aorta, with one segment of the stent implanted in the renal artery. Self-expanding non-covered stents were released by laparotomy. The histological slices were made at the transition from the normal aorta and the aorta containing the stent; the aorta portion containing the stent; the portion with the ostia of renal arteries; periaortic lymph nodes and renal parenchyma. The samples were stained by the hematoxylin and eosin technique. Results: Macroscopic findings showed periaortic lymphadenopathy, thickened aortic wall, patency of lumbar and renal arteries and normal renal anatomical structure. Microscopic analyses near the stents revealed thickening of vessel wall secondary to intima fibrosis, and media layer affected by interstitial fibrosis. Micrometric measurements of aorta wall with the stent, compared to the aortic portion without it, presented a 75.90% increase in the total thickness of the wall by thickening of the intima layer secondary to fibroblast proliferation, collagen deposits with lymphocytary inflammatory infiltrate and foreign body-type granulomas. Conclusion: The non-covered stainless steel stents in pigs’ aortas produced a significant inflammatory reaction with fibrosis in the media and intima layers evidenced by histopathological analyses; their presence did not interfere in the patency of the abdominal aorta or the renal and lumbar arteries.