Short-term effects of polytetrafluoroethylene covered and uncovered metallic "stents" in pig aorta: an experimental model

PURPOSE: To report an experimental study evaluating, through digital morphometry, the intimal thickening of the arterial wall after the implant of auto-expandable stainless steel stents covered or not with polytetrafluoroethylene (PTFE) in the pig aorta. METHODS: In three groups of pigs a 12 F sheath was inserted in distal abdominal aorta. Group I animals (n=5) served as control. Group II animals (n=10) received an auto-expandable uncovered metallic stent. On group III animals (n=10) an auto-expandable stent covered with PTFE was inserted. After four weeks the animals were killed, the specimens were harvested and the intimal thickening was quantified by morphometric analysis. RESULTS: In the comparison among groups I, II and III referring to intimal, medial area and intimal index, it was not observed statistically significant variation. Differences were identified among groups referring to luminal proximal (p=0,036) and distal areas (p=0,044). Through multiple comparison tests for Kruskal-Wallis it was identified a difference between groups I and II. However, when these variables were controlled by weigh factor (luminal area/weigh relation), this difference was not observed anymore. CONCLUSION: In this short term study, the PTFE covering is not associated to further intimal thickening besides that promoted by the metallic mesh in large arteries and in high flow conditions.

Blood vessel prothesis; Polytetrafluoroethylene; Aorta, abdominal; Tunica intima; Models, animal

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