Method of forming an introducer sheath
View Patent ↗A method of forming an introducer sheath having a crease-free tapered distal tip portion. A mandrel is provided having an outer configuration comprising an elongated body and a tapered distal tip portion. A generally tubular inner liner comprising heat shrinkable PTFE, is positioned over the mandrel. The inner liner is heat shrunk to the outer configuration of the mandrel, in a manner that avoids the formation of creases along the inner diameter of the liner. A reinforcing member is positioned over a length of the inner liner, and an outer jacket is positioned over the reinforcing member and the inner liner. The liner, reinforcing member, and outer jacket are heated in a heat shrink enclosure, whereby the outer jacket melts and bonds to an outer surface of the inner liner.
1. A method of forming an introducer sheath having a tapered distal tip portion, comprising:
providing a mandrel having an outer configuration comprising an elongated body and a tapered distal tip;
positioning a generally tubular inner liner over the mandrel, said inner liner comprising a heat shrinkable fluoropolymer;
heat shrinking the inner liner over the mandrel such that said inner liner shrinks to the outer configuration of the mandrel, a distal portion of the inner liner shrinking to the configuration of the mandrel tapered distal tip and having an inner diameter substantially free of creases therealong;
positioning a reinforcing member over a length of the inner liner;
positioning an outer jacket over the reinforcing member and the inner liner; and
heating an assembly comprising said inner liner, reinforcing member, and outer jacket, such that said outer jacket bonds to an outer surface of said inner liner.
2. The method of claim 1 , wherein said fluoropolymer comprises heat shrinkable polytetrafluoroethylene (PTFE).
3. The method of claim 2 , wherein said PTFE inner liner is heat shrunk over said mandrel at a temperature of about 650° F. (340° C.).
4. The method of claim 2 , wherein said reinforcing member comprises a coil having a plurality of coil turns, and wherein said outer jacket bonds to said inner liner through said coil turns.
5. The method of claim 4 , wherein said assembly is heated in a heat shrink enclosure.
6. The method of claim 5 , wherein said enclosure comprises fluorinated ethylene propylene (FEP).
7. The method of claim 4 , wherein said outer jacket comprises a thermoplastic material selected from the group consisting of polyether block amide, nylon, and polyurethane.
8. The method of claim 4 , wherein said outer jacket comprises a plurality of jacket segments, said segments aligned in order of decreasing durometer from a proximal end to a distal end of said outer jacket.