Fabrication of micropored elastomeric film‐covered stents and acute‐phase performances

To prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood‐contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 μm in wall thickness) as a cover material was multiply micropored by excimer laser‐directed microprocessing (pore diameter, 30 μm; interpore distance, 125 μm). An aqueous mixed solution of benzophenone‐derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon‐expandable stent with gelatin/heparin gel‐layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, “half‐covered” stents, in which half at the distal side was covered with the gel‐layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half‐covered stents ( n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 52–61, 2003