Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent in combination with graft
Reexamination Certificate
1999-08-24
2001-04-10
Isabella, David J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent in combination with graft
C623S001180, C623S001340, C600S036000
Reexamination Certificate
active
06214040
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stent. More particularly, it relates a sandwich stent which provides a mechanical barrier for prohibiting the growth of tissue through an artery implanted stent.
2. Description of the Prior art
In the prior art, stents are well known for use in minimally invasive surgery or interventional procedures for attaching to the inner walls of a blood vessel where a procedure such as a balloon angioplasty has been performed. Such prior art stents are essentially metallic scaffolds that are left in the arteries to prevent the arteries from collapsing back to their original form due to a phenomenon called elastic recoil. Such recoil can be common after the dilatation of a balloon.
Although the subject prior art stents have been generally successful in preventing elastic recoil, they have not been successful in the prevention of in stent restenosis. Such phenomenon occurs when tissue grows into and through the struts of the stent due to openings in the stent struts. The tissue is then permitted to grow into the lumen and reocclude the artery, whereby a balloon angioplasty procedure must be repeated.
In an effort to prohibit in stent restenosis, stents were provided with covering material. Such can be seen in U.S. Pat. No. 5,562,728 to Lazarus et al. wherein a helical wrap of ribbon is attached to a covering material; the attachment being only at the ends. U.S. Pat. No. 5,578,071 to Parodi et al. show a vascular graft that has two stents attached at the ends of the tubular conduit, where at one wire is provided and woven into a distal end, or lower end, of the graft, the wire permitting the distal end of the graft to conform to and sealingly engage within the artery of the patient.
When conveying a stent to its point of use, it is imperative that any covering material be secured about the stent in a secure and tight fashion to preclude the stent from being “hung up” in some area of the vascular system of the patient while it is being conveyed to the point of use. The prior art stents do not adequately secure the cover to the stent to prohibit such hang up. Further, the prior art devices have a very large profile that require being cut down by a surgeon and inserted into the body through a very large opening. Accordingly, minimally invasive surgery, in its strictest meaning, is not provided. Because of the large profile, the prior art devices are not useable in every area of the body, but only in larger arteries.
A stent is needed that overcomes the problems in the prior art. Such a stent needs to be low in profile yet provide the necessary mechanical barrier to prevent in stent restenosis. An improved means of securement is needed to prevent the covering material hang up. Further, providing such an improved stent with a low profile can be used in widespread applications and not be limited to large artery procedures.
SUMMARY OF THE INVENTION
The present invention relates to embodiments of a sandwich stent. The present invention includes the following interrelated objects, aspects and features:
(1) In a first aspect, an inner stent in accordance with the teachings of the present invention is made generally tubular and is initially formed in a collapsed configuration. A balloon catheter may be contained within the collapsed stent and inflation of the balloon catheter at the site of installation causes the stent to expand to its expanded configuration lying closely against the inner walls of the desired blood vessel.
(2) A cover is provided for the inner stent and is attached outside the stent at one or more desired locations. An internal diameter of the cover is equivalent to the size of the artery in which it is being introduced. Since the cover is attached to the inner stent, when the stent is expanded by the balloon catheter, the stent expands to the internal diameter of the cover which happens to be the diameter of the artery. Hence, the covered stent conforms to the interior wall of the artery positioning therewithin.
(3) The attachment of the cover to the inner stent may be accomplished in several ways. In one embodiment, the cover may be attached outside the inner stent at one linear location parallel to the axis of elongation of the stent. In an alternative embodiment, the cover may be attached concentrically about the inner stent and secured in that configuration by a series of sutures. In a further modification, the fabric cover may be attached around the inner stent non-concentrically through the use of suitable sutures.
(4) The cover, also comprising an intermediate stent layer, is suitably collapsed and pleated so that it closely surrounds the inner stent. The present invention contemplates two exemplary embodiments of securement means for securing the cover or intermediate stent layer about the inner stent. In a first alternative, one or more expansible clips are collapsed about the cover to secure it about the inner stent. When the entire stent sandwich is expanded, these clips expand as well and comprise stents themselves. The slow expansion of the clips facilitates the unpleating or unraveling of the cover. Without such clips, the cover could have several folds and crimps upon expansion, hence, a potential for hang up. The clips facilitate uniform expansion and also assist in maintaining cover integrity. In a second alternative, securement of the fabric cover or intermediate stent layer about the inner stent is accomplished through the use of a wire spiraling externally about the outer surface of the cover to secure the cover or intermediate stent layer about the inner stent. When the stent sandwich is expanded, the configuration of this spiraling wire permits it to expand as well and lie against the inner walls of the blood vessel at the desired location.
(5) The stent has spaced ends, each of which may be coated or otherwise provided with a radio-opaque material. A cardiologist or surgeon may insert the stent and view its progress through the vascular system of the patient with equipment such as, for example, an X-ray device to ensure that the stent is properly traveling toward the location of installation and is precisely located at its final destination.
Accordingly, it is a first object of the present invention to provide a sandwich stent.
It is a further object of the present invention to provide such a stent including an inner stent, an intermediate stent comprising a cover and an outer stent comprising securement means for securing the cover about the inner stent.
It is a still further object of the present invention to provide such a stent wherein the cover is secured about the inner stent from within the cover in any one of several ways.
It is a still further object of the present invention to provide such a sandwich stent wherein the cover is secured about the inner stent from the outside therefrom in one of a plurality of possible ways.
These and other objects, aspects and features of the present invention will be better understood from the following detailed description of the preferred embodiment when read in conjunction with the appended drawing figures.
REFERENCES:
patent: 4580568 (1986-04-01), Gianturco
patent: 4733665 (1988-03-01), Palmaz
patent: 5019090 (1991-05-01), Pinchuk
patent: 5100429 (1992-03-01), Sinofsky et al.
patent: 5275622 (1994-01-01), Lazarus et al.
patent: 5405378 (1995-04-01), Strecker
patent: 5562727 (1996-10-01), Turk et al.
patent: 5562728 (1996-10-01), Lazarus et al.
patent: 5578071 (1996-11-01), Parodi
patent: 5624411 (1997-04-01), Tuch
patent: 5645559 (1997-07-01), Hachtman et al.
patent: 5667523 (1997-09-01), Bynon et al.
patent: 5693088 (1997-12-01), Lazarus
patent: 5723003 (1998-03-01), Winston et al.
patent: 5725572 (1998-03-01), Lam et al.
patent: 5741326 (1998-04-01), Solovay
patent: 5824054 (1998-10-01), Khosravi et al.
patent: 5865723 (1999-02-01), Love
Iowa-India Investments Company Limited
Isabella David J.
Koh Choon P.
Larson James E.
Larson & Larson P.A.
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