INFECTION OF ENDOVASCULAR STENTS IN A SWINE MODEL

BACKGROUND: Percutaneous balloon angioplasty with intravascular metall ic stent placement has rapidly gained popularity for the treatment of arterial occlusive disease. Although the incidence of vascular prosthe tic infection is well described, the risk of infection following metal lic stent placement is unknown, The purpose of this study was to deter mine if intravascular metallic stents could become infected following systemic bacterial challenge. METHODS: Balloon expandable metallic ste nts were implanted in the iliac arteries of 10 swine following balloon catheter angioplasty, A second angioplasty, without stent placement, was also performed in the contralateral iliac artery, A bacterial chal lenge with Staphylococcus aureus was then infused into the aorta immed iately after stent placement, Group 1 (n = 5) was killed at 72 hours, and group 2 (n = 5) at 3 weeks, A third group (n = 5) underwent stent placement without bacterial challenge and was killed at 3 weeks. At th e time of death, the stents were cultured, and both iliac arteries wer e submitted for pathologic examination, Arterial patency and evidence of systemic infection were also assessed. RESULTS: In the animals sacr ificed at 72 hours (group 1), 80% had stent cultures with significant growth of S aureus; while at 3 weeks (group 2), 60% of cultures were p ositive, Of the stents placed without bacterial challenge (group 3), n one had a positive culture at 3 weeks, in group 2, 40% of the stented arteries remained patent, while 100% of group 3 remained patent until sacrifice at 3 weeks. All of the stented arteries which were patent at 3 weeks were culture negative, while all those which were thrombosed were culture positive for S aureus. When compared to angioplasty alone , the presence of a stent was strongly associated with pathologic evid ence of inflammation [93% versus 7%]. The quality of inflammation in t he stented groups also differed. Ninety percent of the stented arterie s in groups 1 and 2 had acute inflammation, compared to only 20% in gr oup 3. The remainder of the stented arteries in group 3 had chronic in flammation or were normal. CONCLUSION: In the swine model, intravascul ar metallic stents have the potential to become infected, This is asso ciated with acute inflammation of the arterial wall and vessel thrombo sis, Further studies evaluating the incidence of stent infections in h umans are needed.