Abstract
BackgroundVascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model.MethodsA novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery.ResultsAt a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W) due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of ~8 W.ConclusionWe have shown the design and fabrication of an SMP stent and a means of light delivery for photothermal actuation. Though further studies are required to optimize the device and assess thermal tissue damage, photothermal actuation of the SMP stent was demonstrated.
Highlights
Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis
Though improvements in design and coating with drug-eluting agents have resulted in smaller, safer, and more biocompatible stents with reduced rates of restenosis [4], several drawbacks associated with the use of metallic stents still exist
After delivery to the mock artery, the stent did not show signs of expansion in the 37°C water for approximately 3 min prior to actuation. This indicates that the device would likely remain crimped during navigation and positioning under physiological conditions until it is controllably expanded, though further investigation is needed to confirm this hypothesis
Summary
Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. Vascular stents are small tubular scaffolds used to maintain the luminal size of an artery They are widely used in conjunction with transluminal angioplasty in the treatment of arterial stenosis (narrowing of the vessel) to prevent acute vessel closure and late restenosis in a variety of large vessels such as coronary arteries [1], carotid arteries [2], and iliac arteries [3]. Drug elution is currently achieved by coating the metal with a drug-doped polymer [8], which requires a costly additional fabrication step [9]
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