Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1998-11-05
2001-02-20
Millin, V. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S901000
Reexamination Certificate
active
06190404
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an intravascular stent and method for manufacturing an intravascular stent, wherein the intravascular stent has its inner surface treated to promote the migration of endothelial cells onto the inner surface of the intravascular stent.
2. Description of Related Art
Various types of intravascular stents have been used in recent years. An intravascular stent generally refers to a device used for the support of living tissue during the healing phase, including the support of internal structures. Intravascular stents, or stents, placed intraluminally, as by use of a catheter device, have been demonstrated to be highly efficacious in initially restoring patency to sites of vascular occlusion. Intravascular stents, or stents, may be of the balloon-expandable type, such as those of U.S. Pat. Nos. 4,733,665; 5,102,417; or 5,195,984, which are distributed by Johnson & Johnson Interventional Systems, of Warren, N.J., as the Palmaz™ and the Palmaz-Schatz™ balloon-expandable stents or balloon expandable stents of other manufacturers, as are known in the art. Other types of intravascular stents are known as self-expanding stents, such as Nitinol coil stents or self-expanding stents made of stainless steel wire formed into a zigzag tubular configuration.
Intravascular stents are used, in general, as a mechanical means to solve the most common problems of percutaneous balloon angioplasty, such as elastic recoil and intimal dissection. One problem intraluminal stent placement shares with other revascularization procedures, including bypass surgery and balloon angioplasty, is restenosis of the artery. An important factor contributing to this possible reocclusion at the site of stent placement is injury to, and loss of, the natural nonthrombogenic lining of the arterial lumen, the endothelium. Loss of the endothelium, exposing the thrombogenic arterial wall matrix proteins, along with the generally thrombogenic nature of prosthetic materials, initiates platelet deposition and activation of the coagulation cascade. Depending on a multitude of factors, such as activity of the fibrinolytic system, the use of anticoagulants, and the nature of the lesion substrate, the result of this process may range from a small mural to an occlusive thrombus. Secondly, loss of the endothelium at the interventional site may be critical to the development and extent of eventual intimal hyperplasia at the site. Previous studies have demonstrated that the presence of an intact endothelial layer at an injured arterial site can significantly inhibit the extent of smooth muscle cell-related intimal hyperplasia. Rapid reendothelialization of the arterial wall, as well as endothelialization of the prosthetic surface, or inner surface of the stent, are therefore critical for the prevention of low-flow thrombosis and for continued patency. Unless endothelial cells from another source are somehow introduced and seeded at the site, coverage of an injured area of endothelium is achieved primarily, at least initially, by migration of endothelial cells from adjacent arterial areas of intact endothelium.
Although an in vitro biological coating to a stent in the form of seeded endothelial cells on metal stents has been previously proposed, there are believed to be serious logistic problems related to live-cell seeding, which may prove to be insurmountable. Thus, it would be advantageous to increase the rate at which endothelial cells from adjacent arterial areas of intact endothelium migrate upon the inner surface of the stent exposed to the flow of blood through the artery. At present, most intravascular stents are manufactured of stainless steel and such stents become embedded in the arterial wall by tissue growth weeks to months after placement. This favorable outcome occurs consistently with any stent design, provided it has a reasonably low metal surface and does not obstruct the fluid, or blood, flow through the artery. Furthermore, because of the fluid dynamics along the inner arterial walls caused by blood pumping through the arteries, along with the blood/endothelium interface itself, it has been desired that the stents have a very smooth surface to facilitate migration of endothelial cells onto the surface of the stent. In fact, it has been reported that smoothness of the stent surface after expansion is crucial to the biocompatibility of a stent, and thus, any surface topography other than smooth is not desired. Christoph Hehriein, et. al.,
Influence of Surface Texture and Charge On the Biocompatibility of Endovascular Stents, Coronary Artery Disease
, Vol. 6, pages 581-586 (1995). After the stent has been coated with serum proteins, the endothelium grows over the fibrin-coated metal surface on the inner surface of the stent until a continuous endothelial layer covers the stent surface, in days to weeks. Endothelium renders the thrombogenic metal surface protected from thrombus deposition, which is likely to form with slow or turbulent flow. At present, all intravascular stents made of stainless steel, or other alloys or metals, are provided with an extremely smooth surface finish, such as is usually obtained by electropolishing the metallic stent surfaces. Although presently known intravascular stents, specifically including the Palmaz™ and Palmaz-Schatz™ balloon-expandable stents have been demonstrated to be successful in the treatment of coronary disease, as an adjunct to balloon angioplasty, intravascular stents could be even more successful and efficacious, if the rate and/or speed of endothelial cell migration onto the inner surface of the stent could be increased. Accordingly, the art has sought an intravascular stent, and method for manufacturing an intravascular stent, which may increase the rate of migration of endothelial cells upon the inner surface of the stent after it has been implanted.
SUMMARY OF THE INVENTION
In accordance with the invention, the foregoing advantage has been achieved through the present intravascular stent having an outer surface and an inner surface. The present invention includes an improvement in such intravascular stents, and an improvement in the method for manufacturing such intravascular stents, by providing at least one groove disposed in the inner surface of the stent. A further feature of the present invention is that the at least one groove may have a width, a length, and a depth, and the width and depth may not vary along the length of the at least one groove. Further features of the present invention are that: the width of the groove may vary along the length of the at least one groove; the depth of the groove may vary along the length of the at least one groove; and both the width and the depth may vary along the length of the at least one groove.
Another feature of the present invention is that the at least one groove may have a length, a longitudinal axis, and a cross-sectional configuration, and the cross-sectional configuration of the at least one groove may vary along the length of the at least one groove. An additional feature of the present invention is that the cross-sectional configuration of the at least one groove may not vary along the length of the at least one groove. Further features of the present invention are that the cross-sectional configuration of the at least one groove may be: substantially symmetrical about the longitudinal axis of the at least one groove; substantially asymmetrical about the longitudinal axis of the at least one groove; substantially triangular shaped; substantially rectangular shaped; substantially square shaped; substantially U shaped; or substantially V shaped.
A further feature of the present invention is that the longitudinal axis of the at least one groove may be disposed: substantially parallel with the longitudinal axis of the stent; substantially perpendicular to the longitudinal axis of the stent; at an obtuse angle with respect to the longitudinal axis of the stent; or at an acute angle with respect to the longitudinal axis of the stent. An
Palmaz Julio C.
Sprague Eugene A.
Advanced Bio Prosthetic Surfaces, Ltd.
Bracewell & Patterson L.L.P.
Koh Choon P.
Millin V.
Tobor Ben D.
LandOfFree
Intravascular stent and method for manufacturing an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Intravascular stent and method for manufacturing an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Intravascular stent and method for manufacturing an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2612376