Patent ID: 9668897
Date: 2017-06-06
CPC Classifications: A61F,A61L

Claim:
1. A stent apparatus comprising: a stent comprising an outer surface and formed of a first biodegradable polymer comprising poly-L-lactide (PLLA), the biodegradable polymer having a shape memory property as a tubular shape and a shape memorized size capable of scaffolding a vessel from an inside of the vessel when implanted in the vessel, wherein the stent is mounted on a balloon of a balloon catheter in a contracted state having a smaller diameter than the shape memorized size before expansion, and a stent covering member comprising a plurality of openings and an inner surface and for covering the outer surface of the stent contracted and mounted on the balloon of the balloon catheter and expandable by balloon inflation, wherein: the stent covering member is formed of a second biodegradable copolymer of PLLA and poly-ε-caprolactone (PCL) in which a molar ratio of PLLA to PCL ranges from 95:5 to 20:80, the first biodegradable polymer and the second biodegradable polymer are configured such that the inner surface of the stent covering member tightly contacts the outer surface of the stent with an affinity to elastically hold the stent in the contracted state, the stent covering member has elasticity as a cylindrical shape having an inner diameter to keep the stent in the contracted state and, when the stent is expanded to the shape memorized size, plastically deforms to release the stent, wherein the elasticity of the stent covering member decreases during the expansion, the stent covering member formed of the biodegradable copolymer having an elastic force larger than that of the second biodegradable polymer constituting the stent, thereby tightly crimping the outer surface of the stent formed of the first biodegradable polymer and elastically holding the stent in the contracted state, wherein when the expansion exceeds the elastic force of the stent covering member, the stent recovers its shape to the shape memorized size and the stent covering member has an elastic modulus ranging from 2×10