Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent in combination with graft
Reexamination Certificate
1998-03-31
2002-12-03
McDermott, Corrine (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent in combination with graft
C623S001230, C623S001390, C623S001460, C623S001150
Reexamination Certificate
active
06488701
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to endoluminal grafts for stenotic or diseased lumens and methods of making such grafts. More particularly, the invention includes a stent-graft assembly comprising a thin-walled graft component and methods of making the assembly.
BACKGROUND OF THE INVENTION
A wide range of medical treatments have been previously developed using “endoluminal prostheses,” which terms are herein intended to mean medical devices which are adapted for temporary or permanent implantation within a body lumen, including both naturally occurring or artificially made lumens. Examples of lumens in which endoluminal prostheses may be implanted include, without limitation: arteries, such as those located within the coronary, mesentery, peripheral, or cerebral vasculature; veins; gastrointestinal tract; biliary tract; urethra; trachea; hepatic shunts; and fallopian tubes. Various types of endoluminal prostheses have also been developed, each providing a uniquely beneficial structure to modify the mechanics of the targeted luminal wall.
For example, various grafts, stents, and combination stent-graft prostheses have been previously disclosed for implantation within body lumens. More specifically regarding stents, various designs of these prostheses have been previously disclosed for providing artificial radial support to the wall tissue which forms the various lumens within the body, and often more specifically within the blood vessels of the body. An example of such a stent displaying optimal radial strength includes, but is not limited to, the stent disclosed in U.S. Pat. No. 5,292,331 to Boneau, the disclosure of which is herein incorporated by reference. Stents of other designs are known in the art, and may also be suitable for use in the stent-graft assembly. Other example of stents include but are not limited to those disclosed in U.S. Pat. No. 4,733,665 issued to Palmaz, U.S. Pat. No. 5,195,984 issued to Schatz, or U.S. Pat. No. 5,514,154 issued to Lau. Stents are used alone or in conjunction with grafts.
The use of an angioplasty balloon catheter is common in the art as a minimally invasive treatment to enlarge a stenotic or diseased blood vessel. This treatment is known as percutaneous transluminal angioplasty, or PTA. To provide radial support to the treated vessel in order to prolong the positive effects of PTA, a stent may be implanted in conjunction with the procedure. Under this procedure, the stent may be collapsed to an insertion diameter and inserted into a body lumen at a site remote from the diseased vessel. The stent may then be delivered to the desired site of treatment within the affected lumen and deployed to its desired diameter for treatment. Although the stents listed above are balloon expandable, stents which rely on other modes of deployment such as self-expansion, may be used to make a device according to the present invention. Because the procedure requires insertion of the stent at a site remote from the site of treatment, the device must be guided through the potentially tortuous conduit of the body lumen to the treatment site. Therefore, the stent must be capable of being reduced to a small insertion diameter and must be flexible.
During an angioplasty procedure, atheromatous plaques undergo fissuring, thereby creating a thrombogenic environment in the lumen. Excessive scarring may also occur following the procedure, potentially resulting in reocclusion of the treated lumen. Attempts to address these problems include providing a suitable surface within the lumen for more controlled healing to occur in addition to the support provided by a stent. These attempts include providing a lining or covering in conjunction with an implanted stent. A stent with such a lining or covering is known in the art as a stent-graft.
The graft component, or membrane, of a stent-graft may prevent excessive tissue prolapse or protrusion of tissue growth through the interstices of the stent while allowing limited tissue in-growth to occur to enhance the implantation. The surface of the graft material at the same time may minimize thrombosis, prevent scarring from occluding the lumen, prevent embolic events and minimize the contact between the fissured plaque and the hematological elements in the bloodstream.
A combination stent-graft may serve other objectives, such as delivering therapeutic agents via the assembly, excluding aneurysms or other malformations, occluding a side branch of a lumen without sacrificing perforator branches, conferring radiopacity on the device, and others. Various designs to achieve these objectives include stents partially or completely coated or covered with materials, some of which are impregnated with therapeutic agents, radiopaque elements, or other features designed to achieve the particular objectives of the device.
A graft component may be combined with a stent in order to achieve some or all of the foregoing objectives. However, adding a graft layer to the stent increases the challenges of delivering a stent via a catheter by increasing the crossing profile, or diameter, of the device, and by decreasing the flexibility of the device. Because the angioplasty process requires the insertion of the device into a body lumen at a site remote from the site of treatment and the guiding of the device the body lumen to the treatment site, it is required that the device be both capable of being collapsed to a relatively small diameter and be quite flexible. Moreover, flexibility and a desirable insertion diameter must be achieved without sacrificing the treatment objectives of the assembly, which include, at a minimum, radial strength. Therefore, an objective of a combination stent and graft is achieving the advantages of both a stent and a graft without significantly increasing the crossing profile of the device or significantly decreasing the flexibility of the device.
Various methods of manufacturing graft devices alone have been disclosed in the art. One such method for manufacturing a graft is disclosed in U.S. Pat. No. 5,641,373, issued to Shannon et al. The disclosed method comprises reinforcing an extruded flouropolymer tube with a second flouropolymer tube. The second tube is prepared by winding fluoropolymer tape around the exterior of a mandrel and heating it to form a tube. The graft may then be mounted on an anchoring mechanism such as a stent or other fixation device.
Another example of a graft is disclosed in U.S. Pat. No. 4,731,073, issued to Robinson. The graft disclosed therein comprises multiple layers of segmented polyether-polyurethane which form multiple zones having varying porosities.
U.S. Pat. No. 5,628,786, issued to Banas, discloses a polytetrafluoroethylene (PTFE) graft which has a reinforcing structure integrally bound to the graft. The reinforcing structure may be in the form of a rib which is sintered or otherwise integrally bound to the graft.
U.S. Pat. No. 5,207,960, issued to Moret de Rocheprise, discloses a process for the manufacture of a thin-walled tube of fluorinated resin tape. The method includes winding the tape around a mandrel and sintering the tape. While still on the mandrel, the tube is rolled to elongate the tube, to reduce the thickness of the tube, and to facilitate removal of the tube from the mandrel. The patent discloses that the tubes obtained can be used particularly as sheaths for the lining of metal tubes.
There are also numerous examples of combination stent-grafts disclosed in the art. U.S. Pat. No. 5,653,747 issued to Dereume discloses a stent to which a graft is attached. The graft component is produced by extruding polymer in solution into fibers from a spinnerette onto a rotating mandrel. A stent may be placed over the fibers while on the mandrel and then an additional layer of fibers spun onto the stent. The layer or layers of fibers may be bonded to the stent and/or one another by heat or by adhesives.
PCT Application WO 95/05132 discloses a stent around which a thin film of PTFE has been wrapped circumferentially one time and overlapped upon itse
Birdsall Matthew J.
Lashinski Robert D.
Nolting John E.
Shull Samuel L.
Williams Michael S.
McDermott Corrine
Medtronic AVE Inc.
Miller Cheryl
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