Purpose
Stent failure modes, such as device migration and fracture, may be related to the implant material and environment, including normal motion of the implant site. The kinematics of pelvic vascular motion in swine was studied with and without implanted stents to define these parameters in a preclinical implant model. Long-term stent integrity was evaluated in swine coronary and femoral arteries to identify material and site-specific effects.
Materials and methods
The motion and deformation of pelvic vessels during movement were evaluated by CTA with the animals ( n =5) under anesthesia and the hindlimbs (i) fully extended and (ii) fully flexed at the hip. Bare metal stainless steel stents (BMS SS) were implanted in the femoral artery of swine ( n =5) and CTA performed. The in vivo vessel deformation with and without a stent was quantified with image analysis (cvSim) of the CTA. Three-dimensional deformation of the normal and stented vessels was characterized as changes in length, diameter, curvature, and torsion. Nitinol (NiTi) and SS stents were implanted in the lateral circumflex femoral (LCxF) ( n =12) and coronary arteries ( n =12): overlapping NiTi-SS and either single NiTi or SS BMS. Serial CT and fluoroscopy were performed for up to 180 days with radiographs and SEM of explanted stents.
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