Method of fabricating an implantable medical device with biaxially oriented polymers

A method of manufacturing an implantable medical device, comprising:

• introducing a polymer into a forming apparatus comprising a first annular member disposed within a second annular member, wherein the polymer is conveyed through an annular chamber as an annular film between the annular members;
• forming a tube from the annular film, including rotating at least one of the annular members to induce circumferential flow of the polymer material as it is conveyed through the chamber, wherein the rotation is selected so that polymer chains become orientated circumferentially to increase the radial stiffness of the tube;
• drawing the polymer material from the chamber to form the tube;
• cooling the tube as the polymer material exits the chamber;
• and
• fabricating a plurality of interconnecting bars of an implantable medical device from the radially stiffened tube.

A method of manufacturing an implantable medical device, comprising:

• introducing a polymer into a forming apparatus comprising a first annular member disposed within a second annular member, wherein the polymer is conveyed through an annular chamber as an annular film between the annular members;
• forming a tube from the expanded annular film, including rotating a third annular member disposed in a drawing region of the apparatus to induce circumferential flow of the polymer as it exits the chamber;
• inducing a biaxial orientation of polymer chains to increase the stiffness of the tube including the rotating of the third annular member simultaneously with a pulling of the polymer material in an axial direction in a drawing region of the apparatus and a cooling the polymer material to increase strength and stiffness in the tube, and
• fabricating a plurality of interconnecting bars of an implantable medical device from the tube.