Method of fabricating an implantable medical device with biaxially oriented polymers

Abstract

Methods and systems for manufacturing an implantable medical device, such as a stent, from a tube with desirable mechanical properties, such as improved circumferential strength and rigidity, are described herein. Improved circumferential strength and rigidity may be obtained by inducing molecular orientation in materials for use in manufacturing an implantable medical device. Some embodiments may include inducing molecular orientation by expansion of a molten annular polymer film. Other embodiments may include inducing circumferential molecular orientation by inducing circumferential flow in a molten polymer. In certain embodiments, circumferential orientation may be induced by expansion of a polymer tube. Further embodiments may include manufacturing an implantable medical device from a biaxially oriented planar polymer film.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to methods of fabricating implantable medical devices such as stents. [0003] 2. Description of the State of the Art [0004] This invention relates to radially expandable endoprostheses which are adapted to be implanted in a bodily lumen. An “endoprosthesis” corresponds to an artificial implantable medical device that is placed inside the body. A “lumen” refers to a cavity of a tubular organ such as a blood vessel. A stent is an example of these endoprostheses. Stents are generally cylindrically shaped devices which function to hold open and sometimes expand a segment of a blood vessel or other anatomical lumen such as urinary tracts and bile ducts. Stents are often used in the treatment of atherosclerotic stenosis in blood vessels. “Stenosis” refers to a narrowing or constriction of the diameter of a bodily passage or orifice. In such treatments, stents reinforce body vessels and prevent resten...

AI Technical Summary

Benefits of technology

[0010] The present invention is directed to methods for fabricating an implantable medical device, such as a stent, from a tube, with desirable mechanical properties, such as improved circumferential strength and rigidity. Improved circumferential strength and rigidity may be obtained by inducing circumferential molecular orientation in materials for use in manufacturing an implantable medical device. Various embodiments of the present invention include methods for inducing circumferential molecular orientation in a material.

Problems solved by technology

However, the characteristics of the material of which a stent is composed also affects the mechanical properties of the stent.

Other potential shortcomings of metal stents include adverse reactions from the body, nonbioerodability, and non-optimal drug-delivery.

Furthermore, another potential problem with polymer stents is that struts can crack during crimping, especially for brittle polymers.

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