Degradable implantable medical devices

Abstract

Devices and methods are provided for an implantable medical device which is degradable over a clinically relevant period of time. The medical devices may have the form of implants, graft implants, vascular implants, non vascular implants, wound closure implants, sutures, drug delivery implants, biologic delivery implants, urinary tract implants, inter-uterine implants, organ implants, bone implants including bone plates, bone screws, dental implants, spinal disks, or the like. In preferred embodiments, the implantable medical device comprises an implantable luminal prosthesis, such as vascular and non-vascular stents and stents grafts.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 60 / 668,707 (Attorney Docket No. 022265-000200US), filed on Apr. 5, 2005, incorporated herein by reference for all purposes.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to medical devices and methods. More particularly, the present invention relates to implantable luminal prostheses and other medical devices which degrade in a body environment. [0004] 2. Description of the Background Art [0005] Coronary artery disease is the leading cause of death in the industrialized countries around the world. It begins as the accumulation of atherosclerotic deposits in the walls of the major arteries which supply blood to the heart. As the deposits accumulate, normal blood flow to the heart is restricted. The heart has several compensatory mechanisms, which, to a point, can offset such diminished blood flow. Beyond these c...

AI Technical Summary

Benefits of technology

[0022] In a fourth aspect of the present invention, the degradation rate of the implantable structure is controlled at least in part by the manipulation of corrosion enhancing and / or corrosion resisting elements in the implant structure. Thus, atoms or compounds which lower the resistance of a metal or metal alloy to corrosion can be added to or increased if already present in these materials. Likewise, one or more corrosion resisting elements may be depleted. Such manipulation of elements may occur on a surface of the implant structure, throughout the implant structure or adjacent to a grain boundary of a metal or alloy to control corrosion of the metal or alloy.

[0026] In an eighth aspect of the invention, the degradation rate of the implantable structure is controlled at least in part by incorporating or manipulating a protective layer. In some embodiments, the implantable structure comprises an implantable body comprising a metal, metal alloy or combination thereof having a degradation rate, and a layer which covers at least a portion of the implantable body, wherein aspects of the layer are controlled which controls the degradation rate of the implantable body. The protective layer may comprise a passivation layer or a coating. Such coatings may comprise a polymer, metal, metal alloy, therapeutic agent, corrosive agent, radiopaque agent or combination of these. Such aspects of the protective layer may include thickness, chemical composition, chemical permeability, durability, amount of coverage of the implantable structure, or a combination of thereof, such aspects of the protective layer may include amount of corrosion-resistant oxides. Optionally, the protective layer may have openings which reveal underlying portions of the implantable body, wherein the openings assist in controlling the degradation rate of the implantable body.

Problems solved by technology

However, as the disease progresses, its symptoms become more apparent, despite drug therapy.

However, restenosis, or reocclusion of the treated lesion, has plagued PTCA.

Such permanent implantation may increase the amount of intimal hyperplasia, thrombosis or other adverse medical effects.

Thus, these stents do not permit temporary placement within the body unless patient and surgeon are prepared to undertake a second procedure to remove the stent, which is difficult or impossible in most cases.

Further, the presence of a stent which remains mechanically rigid could potentially cause complications to the patient.

Such polymer stents, however, tend to provide less mechanical support for the vessel wall and therefore have to be substantially thicker than a comparable metallic stent.

The thickness can reduce the available blood flow lumen and can cause undesirable biologic responses.

Such degradable metal stents, however, often compromise strength, profile, and other desirable characteristics which are found in conventional metal stents.

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