Fabrication and in vitro deployment of a laser-activated shape memory polymer vascular stent.
BACKGROUND
Vascular 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.


METHODS
A 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.


RESULTS
At 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.


CONCLUSIONS
We 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.
Department of Biomedical Engineering, University of California, Davis, California 95616 USA. gmbaer@ucdavis.edu
Géraldine M
GM
Baer
Ward
W
Small
Thomas S
TS
Wilson
William J
WJ
Benett
Dennis L
DL
Matthews
Jonathan
J
Hartman
Duncan J
DJ
Maitland
D001807:Blood Vessel Prosthesis; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry*; D013193:Stainless Steel / Q000737:chemistry; D015607:Stents
D020099:Coated Materials, Biocompatible; D011108:Polymers; D013193:Stainless Steel