Tapered Polymeric Stent And Method Of Fabricating Same

Abstract

A polymeric stent has an inner surface with an inner diameter that tapers continuously in size. A method for manufacturing a stent includes blow molding a polymeric tube within a mold having a tapered, cylindrical cavity such that the polymeric tube attains a corresponding tapered shape. The tapered tube is used as a substrate from which a laser cuts interconnecting stent struts.

1 . Method of manufacturing a stent, the method comprising:
 disposing a polymeric tube into a cylindrical mold, the cylindrical mold comprising an inner surface facing the polymeric tube, the inner surface having an inner diameter that varies along an axial length of the cylindrical mold;   expanding the polymeric tube in radially outward directions to form an expanded tube, the expanding including blowing a gas or liquid into the cylindrical mold so that an outer surface of the polymeric tube conforms to the inner surface of the cylindrical mold and so that the outer surface of the expanded tube has an outer diameter that varies along an axial length of the expanded tube; and   fabricating a stent from the expanded tube.   
     
     
         2 . The method of  claim 1 , wherein the outer surface of the expanded tube is tapered such that the outer diameter increases from an end segment of the expanded tube to an opposite end segment of the expanded tube. 
     
     
         3 . The method of  claim 2 , wherein the outer diameter increases continuously from the end segment to the opposite end segment. 
     
     
         4 . The method of  claim 1 , wherein the outer surface forms a conical shape. 
     
     
         5 . The method of  claim 1 , wherein the expanded tube comprises a first end segment, a second end segment opposite the first end segment, and a central segment between the first and second end segments, and wherein the outer surface of the expanded tube is tapered such that the outer diameter is greater at the first end segment than at the central segment and is greater at the central segment than at the second end segment. 
     
     
         6 . The method of  claim 1 , wherein the expanded tube comprises a first end segment, a second end segment opposite the first end segment, and a central segment between the first and second end segments, and wherein the outer diameter is larger at the central segment than at the first and second end segments. 
     
     
         7 . The method of  claim 1 , wherein the expanded tube comprises a first end segment, a second end segment opposite the first end segment, and a central segment between the first and second end segments, and wherein the outer surface of the expanded tube is tapered such that the outer diameter increases from the first end segment to the central segment. 
     
     
         8 . The method of  claim 7 , wherein the outer diameter increases from the second end segment to the central segment. 
     
     
         9 . The method of  claim 1 , further comprising heating the polymeric tube to a temperature above Tg of the polymer either before or during the expanding. 
     
     
         10 . The method of  claim 1 , further comprising heating the polymeric tube to a temperature above Tg of the polymer before and during the expanding. 
     
     
         11 . The method of  claim 10 , wherein the polymeric tube is heated by the liquid or gas blown into the cylindrical mold. 
     
     
         12 . The method of  claim 1 , wherein the fabricating includes cutting a pattern of interconnecting struts from the expanded tube. 
     
     
         13 . The method of  claim 12 , wherein the pattern of interconnecting struts is configured to be crimped and expanded. 
     
     
         14 . The method of  claim 1 , wherein the polymeric tube is a biodegradable and/or biostable polymer. 
     
     
         15 . The method of  claim 1 , wherein the polymeric tube is made of poly(L-lactic acid). 
     
     
         16 . The method of  claim 1 , wherein the polymeric tube is made of poly(lactide-co-glycolide). 
     
     
         17 . A stent formed from a polymeric tube that was disposed into a cylindrical mold, subsequently expanded in radially outward directions in the cylindrical mold, and subsequently removed from the cylindrical mold and cut to form interconnecting stent struts, wherein the polymeric tube has an outer surface with an outer diameter that, after being removed from the cylindrical mold, varies along an axial length of the polymeric tube. 
     
     
         18 . The stent of  claim 17 , wherein the cylindrical mold comprises an inner surface having an inner diameter that varies along an axial length of the cylindrical mold, and the outer surface of the polymeric tube has a shape corresponding to the inner surface of the cylindrical mold. 
     
     
         19 . The method of  claim 1 , wherein the polymeric tube comprises a first end segment, a second end segment opposite the first end segment, and a central segment between the first and second end segments, and wherein after the polymeric tube is removed from the cylindrical mold, the outer surface of the polymeric tube is tapered such that the outer diameter is greater at the first end segment than at the central segment and is greater at the central segment than at the second end segment. 
     
     
         20 . The method of  claim 1 , wherein the polymeric tube comprises a first end segment, a second end segment opposite the first end segment, and a central segment between the first and second end segments, and wherein after the polymeric tube is removed from the cylindrical mold, the outer diameter is larger at the central segment than at the first and second end segments.