Placement of a flexible endovascular stent across the femoral joint: An invivo study in the swine model

PURPOSE: To investigate the effects of joint motion on the structural integ rity of periarticular stents and on the development of neointimal hyperplas ia within these devices. MATERIALS AND METHODS: In four juvenile farm swine, Wallstents were implant ed in the common femoral arteries and contralateral common femoral veins, c entered at the point of maximal conformational change during passive hip fl exion, Control stents were placed in the aortae and iliac veins. Angiograph y and transcatheter blood pressure measurements were obtained across each s tent, with periarticular stents studied in flexion and extension, Two anima ls underwent repeated evaluation after 1 month, the others after 3 months. Findings were correlated with gross and histopathologic findings in the har vested stents, RESULTS: No stent fractures occurred. One femoral vein was injured during s tent placement and was occluded 1 month later at follow-up, Hemodynamically significant stenoses were identified in one arterial stent and one venous stent at 3 months. The amount of neointimal hyperplasia was greater in peri articular stents than in controls and greater in animals studied at 1 month than in those studied at 3 months. The pattern of neointimal hyperplasia w ithin mobile arteries was circumferentially asymmetric and thicker at the d istal ends of the stents, Venous neointimal hyperplasia was thicker and mar kedly different in character than that seen in arterial stents from the sam e animals. CONCLUSIONS: Periarticular Wallstents and the underlying vascular anatomy r emained structurally intact despite the stresses of repetitive motion durin g a 3-month period, Stents deployed across joints or in venous locations ma y be at greater risk for neointimal hyperplasia development and eventual oc clusion than those deployed in immobile vessels and arteries. Neointimal hy perplasia may decrease in thickness after an initial period of exuberant de velopment. Additional studies are necessary to determine longterm outcomes.