Stent Placement in Arteriovenous Fistula: An Experimental study

ABSTRACT

PURPOSE: To determine the efficacy of metalic stents in the treatment of experimentally createdcarotid-jugular fistulas. MATERIALS AND METHODS: Carotid-jugular fistulas were constructed surgically in fourmongrel swines. Three Wallstents (Schneider, Bulbanch, Switzerland), 6mm in diameter and 23mm in length, and oneNir stent (Boston Scientific Corporation, Boston, U.S.A.), 3-5mm in diameter and 16mm in length, were placedendovascularly across the fistula holes within the carotid artery. Carotid angiography was performed before,immediately after, and 1-3 months after stent placement. Fistula specimens were ohtained after final angiographyand gross and microscopic examination was performed. RESULTS: Angiography demonstrated decreased flow through thefistula immediately after stent placement. During follow-up, flow through the fistula decreased progressively butcomplete closure did not occur. Carotid arteries p in which Wallstents were placed were patent throughout thefollow-up period. A carotid artery in which a Nir stent was used showed no decreased flow during follow-upangiography lasting two months. Pathologically, a thin layer of endothelium covered the stent wires;there was atransitional zone between the fibrous connective tissue of organizing thrombus, and endothelial proliferationoccurred in the overlying fistula hole. CONCLUSIONS: Stent placement effectively reduced flow through thefistulas but during the ensuing three months closure did not occur. Occlusion was then progressive.Pathologically, intimal proliferntion arose from the oranizing thrombus on the surface of the stent mesh.