U.S. patent application number 10/673528 was filed with the patent office on 2004-05-20 for stent with smooth ends.
This patent application is currently assigned to Scimed Life Systems, Inc.. Invention is credited to Wang, Lixiao.
Application Number | 20040098119 10/673528 |
Document ID | / |
Family ID | 22110723 |
Filed Date | 2004-05-20 |
United States Patent
Application |
20040098119 |
Kind Code |
A1 |
Wang, Lixiao |
May 20, 2004 |
Stent with smooth ends
Abstract
A stent having at least one smooth end is disclosed. The stent
may include a coating or coatings on one or both end portions to
provide a smooth finish to reduce possible damage to body passages
when the stent is deployed and delivered. The stent may also
contain drugs or surgical adhesives or a combination thereof in or
on the coated portion of the stent. The stent may also be of the
type where the materials of the stent may be treated to have a
smooth flexible end or ends. The stent may also be of a
configuration such that at least one end is more flexible than the
middle portion of the stent.
Inventors: |
Wang, Lixiao; (Maple Grove,
MN) |
Correspondence
Address: |
JONES DAY
222 EAST 41ST STREET
NEW YORK
NY
10017
US
|
Assignee: |
Scimed Life Systems, Inc.
|
Family ID: |
22110723 |
Appl. No.: |
10/673528 |
Filed: |
September 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10673528 |
Sep 29, 2003 |
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10017004 |
Dec 14, 2001 |
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6652575 |
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10017004 |
Dec 14, 2001 |
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09374425 |
Aug 13, 1999 |
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6379379 |
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09374425 |
Aug 13, 1999 |
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09072944 |
May 5, 1998 |
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Current U.S.
Class: |
623/1.42 |
Current CPC
Class: |
A61L 2300/606 20130101;
A61L 2300/608 20130101; A61F 2/90 20130101; A61K 9/0024 20130101;
A61F 2/91 20130101; A61L 2300/25 20130101; A61F 2/915 20130101;
A61F 2002/91558 20130101; A61F 2/92 20130101; A61F 2220/005
20130101; A61L 31/10 20130101; A61F 2002/91541 20130101; A61F 2/82
20130101; A61L 2420/08 20130101; A61F 2/88 20130101; A61L 31/16
20130101; A61L 2300/416 20130101; A61F 2250/0018 20130101 |
Class at
Publication: |
623/001.42 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. An expandable intraluminal stent comprising a main body portion
having a first end portion, a second end portion, a middle portion
and a flow passage defined therethrough, at least a portion of the
first end portion having a biocompatible coating.
2. The stent of claim 1 wherein the coating comprises a
biocompatible polymer.
3. The stent of claim 1 wherein the coating comprises a
biodegradable polymer.
4. The stent of claim 1 wherein the first end portion comprises an
inner surface, an outer surface, an end and an edge, the coating
covering the end and at least a portion of the edge of the first
end portion.
5. The stent of claim 1 wherein at least a portion of the second
end portion has a biocompatible coating.
6. The stent of claim 5 wherein the second end portion comprises an
outer surface, an inner surface, an end, and an edge, the coating
covering the end and at least a portion of the edge of the second
end portion.
7. The stent of claim 5 wherein the coating comprises a
biocompatible polymer.
8. The stent of claim 1 wherein the coating includes a drug.
9. The stent of claim 8 wherein the drug comprises TAXOL.
10. The stent of claim 1 wherein the coating includes a
bioadhesive.
11. The stent of claim 1 wherein the coating comprises a plurality
of layers.
12. The stent of claim 11 wherein the plurality of layers is
comprised of the same coating material.
13. The stent of claim 11 wherein the plurality of layers is
comprised of different coating materials.
14. The stent of claim 12 wherein at least one of the layers
includes a drug.
15. The stent of claim 5 wherein the coating comprises a plurality
of layers.
16. The stent of claim 15 wherein the plurality of layers is
comprised of the same coating material.
17. The stent of claim 15 wherein the plurality of layers is
comprised of different materials.
18. The stent of claim 15 wherein at least one of the layers
includes a drug.
19. An expandable intraluminal stent comprising a main body portion
having a first end portion, a second end portion, a middle portion
and a flow passage defined therethrough, and a sleeve of
biocompatible material connected to the first end portion.
20. The stent of claim 19 wherein the sleeve comprises a
biocompatible polymer.
21. The stent of claim 19 wherein the coating comprises a
biodegradable polymer.
22. The stent of claim 19 wherein the sleeve includes
apertures.
23. The stent of claim 19 wherein the sleeve includes a drug.
24. The stent of claim 23 wherein the drug comprises TAXOL.
25. The stent of claim 19 wherein the sleeve comprises a plurality
of layers.
26. The stent of claim 25 wherein the plurality of layers is
comprised of the same coating material.
27. The stent of claim 25 wherein the plurality of layers is
comprised of different materials.
28. The stent of claim 25 wherein at least one of the layers
includes a drug.
29. The stent of claim 19 further comprising a second sleeve
connected to the second end portion.
30. The stent of claim 29 wherein the sleeve comprises a
biocompatible polymer.
31. The stent of claim 29 wherein the sleeve includes
apertures.
32. The stent of claim 29 wherein the sleeve includes a drug.
33. The stent of claim 29 wherein the sleeve comprises a plurality
of layers.
34. The stent of claim 33 wherein the plurality of layers is
comprised of the same coating material.
35. The stent of claim 33 wherein the plurality of layers is
comprised of different materials.
36. The stent of claim 33 wherein at least one of the layers
includes a drug.
37. An expandable intraluminal stent comprising a main body portion
having a first end portion, a second end portion, a middle portion
and a flow passage defined therethrough, the first end portion
being polished to provide a smooth first end portion.
38. The stent of claim 37 further comprising a polished second end
portion to provide a smooth second end portion.
39. An expandable intraluminal stent comprising a main body portion
having a first end portion, a second end portion, a middle portion
and a flow passage defined therethrough, the first end portion
being heat treated to provide flexibility.
40. The stent of claim 39 further comprising a heat treated second
end portion to provide flexibility.
41. An expandable intraluminal stent comprising a main body portion
having a first end portion, a second end portion, a middle portion
and a flow passage defined therethrough, the first end portion
constructed in a manner so as to be more flexible than the middle
portion.
42. The stent of claim 41 wherein the stent comprises a looser mesh
first end portion than the middle portion.
43. The stent of claim 41 further comprising the second end portion
constructed in a manner so as to be more flexible than the middle
portion.
44. The stent of claim 43 wherein the stent comprises a looser mesh
second end portion than the middle portion.
45. The stent of claim 1 wherein the coating comprises an RGD
peptide-containing compound.
46. The stent of claim 8 wherein the drug comprises
5-flroracil.
47. The stent of claim 8 wherein the drug comprises Tranilast.
48. The stent of claim 8 wherein the drug comprises Tropidil.
49. The stent of claim 8 wehrien the drug comprises Probucol.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a stent for use in body passages
and more particularly, to a stent having at least one end which is
coated or to a stent having at least one end which is treated to be
smooth and flexible. The invention also has particular relevance to
a stent having at least one end coated where the coating consists
at least in part of drugs for delivery.
BACKGROUND OF THE INVENTION
[0002] Stents are used in human or animal body passages for
maintaining the patency of the passages. Stents are generally
tubular in configuration, open ended and are expandable between a
generally unexpanded insertion diameter and an expanded
implantation diameter. Stents are commonly placed or implanted by a
mechanical transluminal procedure.
[0003] Prior art patents refer to the construction and design of
stents as well as apparatus for positioning stents within a vessel
or other passage. In general, for example, such patents disclose a
technique for positioning an elongated cylindrical stent at a
region of stenosis, an aneurysm, or the like. The stent expands as
necessary to an implanted configuration after insertion with the
aid of a catheter.
[0004] Specifically, U.S. Pat. No. 4,733,665 to Palmaz discloses a
number of stent configurations for implantation with the aid of a
catheter. U.S. Pat. No. 5,019,090 to Pinchuk discloses a generally
cylindrical stent and technique for implanting it using a deflated
balloon catheter to position the stent. U.S. Pat. No. 4,503,569 to
Dotter and U.S. Pat. No. 4,512,338 to Balko et al. disclose a
spring stent and a shape memory alloy stent. There are also
self-expanding stents such as those described in U.S. Pat. Nos.
4,732,152 to Wallsten et al. and U.S. Pat. No. 4,848,343 to
Wallsten et al. All of these patents are hereby incorporated by
reference.
[0005] It is important that the placement of the stent not
contribute to or cause additional blocking. It is known that when
stents are expanded to their implantation diameter the ends of the
stent may press into the vessel or cavity walls, especially the
distal end of the stent. The sharp or pointed edges and ends of
some stents may then damage the walls. Once damage has occurred,
there is a likelihood that restenosis will occur at these points
where the stents ends and edges have penetrated or pressed against
the walls.
[0006] It is also known that stents may tear a passage wall and
contribute to restenosis. This is particularly important for use of
stents in blood vessels. A tear in the vessel wall may cause
blockage of the vessel. When the wall is torn a flap of tissue is
created. The torn wall or flap usually is the source of the
blockage. The flap falls into the passage and blocks it. It is then
necessary to perform another procedure to remove the blockage and
generally, another stent is needed to open the vessel or other
passage.
[0007] Restenosis occurs in a number of cases where a stent has
been used. Tearing of the wall of the passage or injury of the
endothelial cell layer are possible causes of the restenosis.
Therefore, it is desirable to utilize a stent which reduces the
chances of a damaged vessel wall or body passage which leads to
further problems and further necessary procedures. However, current
stents are not designed to reduce the occurrence of cutting of
vascular passages or the like.
[0008] In addition, it is known that a number of drugs may reduce
the chance of restenosis. Therefore, the use of these drugs in
combination with a stent designed to reduce damage to body passages
would be advantageous. However, known stents are not utilizing
drugs with a means for reducing damage to vessels and the like.
[0009] It is also known that bioadhesives may be used to repair
tissue walls which may have been torn. However, current stents are
not designed to avert a potential problem due to a tear. Currently,
stents are not utilizing a bioadhesive with a stent to repair
tissue walls and prevent further medical procedures required
because of the dissection of a body passage.
[0010] Consequently, a need remains for a stent which reduces the
chances of a tear or other damage of a body passage and which
lessens the chances of further required procedures. The present
invention provides a stent which reduces the limitations of the
prior stents with regard to possible tearing and the need for
further treatment and therefore, performs in an improved
fashion.
SUMMARY OF THE INVENTION
[0011] In accordance with a preferred embodiment of this invention
a stent is characterized in that it includes at least one end
coated with a desired material or materials. The coating may be of
any desirable type which lessens the chance of a tear in the
passage, generally a coating with a smooth finish is preferred.
Generally, any prior art stent may be improved by providing it with
a coating layer or layers of polymeric composition on at least one
end to provide a smooth finish. For another type, a stent may be
provided with a sleeve which may be connected to one or both ends
of the stent.
[0012] In another embodiment, the stent which has been coated or
the stent which utilizes a sleeve may include bioadhesives and/or
drugs to be delivered to the site where the stent is implanted. It
is known that bioadhesives can be used to repair tissue walls. It
is therefore desirable to utilize a polymer coating to carry and
deliver a bioadhesive to the stent implantation location. In this
manner, a potential problem can be averted by the presence of the
bioadhesive in the case of a tear or dissection. It is further
known that a number of different drugs can be useful if delivered
to the stent site. It is desirable to deliver the drug or drugs
with the stent when implantation is occurring or has occurred.
[0013] For yet another embodiment of the invention a stent is
characterized in that at least one end is constructed in a manner
such that the end is treated to be smooth and flexible. The stent
material may be heat treated, for example, or the design of the
stent may be such that it provides for flexibility on an end.
Another embodiment includes a stent designed such that a looser
mesh or pattern is utilized on the end or ends of the stent and a
tighter mesh or pattern is utilized in the middle portion of the
stent. These stents may also be coated on one or both ends as well
as materially treated.
[0014] Yet another embodiment of the invention a stent is
constructed of varying materials having different degrees of
flexibility. A more rigid material is used in the center portion of
the stent and a more flexible material is used for one or both of
the end portions of the stent. This embodiment may also be
materially treated to increase smoothness or flexibility and may
also be coated.
[0015] Stents according to the invention may be self-expanding or
of the type which are expandable from a reduced diameter
configuration by an exterior force (as opposed to self-expanding).
The expandable stents may be balloon expanding for example. Both
types of stents are well known in the art and need not be described
in additional detail herein.
[0016] Stents according to this invention may be metal stents or
polymeric stents, the stent providing the basic framework for the
device.
[0017] These and other advantages and features which characterize
the invention are pointed out with particularity in the claims
annexed hereto and which form a further part hereof. However, for a
better understanding of the invention, its advantages and objects
obtained by its use, reference should be made to the drawings which
form a further part hereof, and the accompanying detailed
description in which there is shown and described an illustrative
embodiment of the invention.
BRIEF DESCRIPTION OF THE FIGURES
[0018] Referring to the drawings, wherein like numerals represent
like parts throughout the several views:
[0019] FIG. 1 is a perspective view of a stent according to the
present invention;
[0020] FIG. 2 is a view of another stent according to one
embodiment of this invention;
[0021] FIG. 3 is a cross sectional view taken along the line 3-3 of
FIG. 2;
[0022] FIG. 4 is fragmentary view of an exemplary representation of
a stent configuration, shown in flat plan view, which may be used
with this invention;
[0023] FIG. 5 is an elevational view of one embodiment of a stent
according to the present invention;
[0024] FIG. 6 is a perspective view of another embodiment of a
stent in accordance with this invention;
[0025] FIG. 7 is a cross section taken along the line 7-7 of FIG.
6;
[0026] FIG. 8 is a perspective view of yet another embodiment of a
stent according to this invention;
[0027] FIG. 9 is a perspective view of a further embodiment of a
stent in accordance with this invention;
[0028] FIG. 10 is a cross sectional view taken along the line 10-10
of FIG. 9;
[0029] FIG. 11 is a perspective view of another embodiment of the
invention utilizing a sleeve; and
[0030] FIG. 12 is an elevational view of another embodiment of a
stent according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] One embodiment of the invention contemplates the use of a
metal or polymer stent which can have any configuration and may be
any stent taken from the prior art or any other stent. This stent
is coated on at least one end with an appropriate biocompatible
coating to provide for a smooth end and edge.
[0032] Referring now to FIG. 1, a metal stent 10 is shown having a
first end portion 12, a middle portion 14 and a second end portion
16. The stent 10 may be stainless steel or any other metal or
material as is known in the art. In a preferred embodiment, the
stent 10 includes a coating 18. The coating 18 is a biocompatible
coating and has characteristics such as a smooth surface and
flexibility for better performance. The coating may be permanent or
biodegradable. Most biodegradable coatings degrade in the body
within a few hours to a few years thereby serving the purpose of
preventing tears during angioplasty or deployment. In a preferred
embodiment the coating 18 is polytetrafluoroethylene (PTFE or
TEFLON) or polyethylene oxide. Many other suitable coatings may be
used with the invention. The following is an exemplary list of
coatings:
[0033] Hydrophilic polymer coatings, copolymers (block or graft) or
their crosslinked versions (e.g. hydrogels), the polymers
including:
[0034] poly(hydroxyethyl methacrylate) and derivatives; poly(vinyl
alcohol);
[0035] polyethylene oxide; polyethylene glycol; poly(propylene
oxide);
[0036] polyacrylamides; polyacrylic acid; polymethacrylic acid;
poly(N-vinyl-2-pyrollidone); hydrophilic polyurethanes;
poly(aminoacid); water soluble cellulosic polymers (sodium
carboxymethyl cellulose, hydroxyethyl cellulose, for example);
collagens; carrageenan; alginate;
[0037] starch; dextrin; gelatins;
[0038] Biodegradable polymers;
[0039] poly(lactide); poly(glycolide); polydioxanone(PDS);
[0040] polycaprolactone; polyhydroxybutyrate(PHBT);
poly(phospazene);
[0041] poly(phosphate ester); poly(lactide-co-glycolide);
poly(glycolide-co-trimethylene carbonate);
poly(glycolide-co-caprolactone- );
[0042] polyanhydrides;
[0043] Permanent coatings:
[0044] polytetrafluoroethylene(PTFE); polyurethanes; polyamides;
polyesters; polyethers; polyketones; polyether ester elastomers;
polyether amide elastomers; polyacrylate-based elastomers;
polyethylene; polypropylene.
[0045] This list is exemplary only. Any appropriate coating may be
used.
[0046] Placing the coating or layer(s) 18 on the stent 10 may be
done by any appropriate method such as dipping, painting, or
spraying as is known in the art. The thickness of the coating can
be varied as desired to achieve different affects and if the
material is biodegradable to last for different desired periods of
time. An exemplary range of thicknesses is about 0.01-0.32 mm. The
thickness chosen depends on the materials used and the desired
results. The thickness of the coating may vary. For example, the
end of the stent may have a greater thickness than that on the
outer surface of the stent. This may provide more of a buffer
between the stent end and edge and the passage where may be needed
the most. It is contemplated that one or more layers of coating may
be applied by appropriate known methods. The layers of coating may
be the same or may be coatings of different materials. Any
appropriate coating materials may be combined as desired.
[0047] The coating 18 is applied to at least the first end portion
12 of the stent 10. If desired, the coating 18 may also be applied
to the second end portion 16. The middle portion of the stent 10
remains uncoated in the present invention. Generally, it is more
important to coat the distal end of the stent. This distal end is
the end that first enters or engages the passage where the stent is
needed. It is important that the stent not injure or tear the
vessel wall as it is delivered to the problem area. The coated
stent provides for a smooth stent portion to reduce the chances of
damage. It is sometimes desirable to coat the proximal portion of
the stent instead of or in addition to the distal end. The same or
different biocompatible coating or coatings may be used to coat the
distal and proximal ends.
[0048] The stent end portion or end portions may be coated on the
outside surface 20, the inside surface 22, the side surface or
surfaces 27, the end or ends 24 or the edge or edges 25. Depending
on the configuration, the stent may have one or more end or side
surfaces and one or more edges 25. A stent of such a configuration
is shown in FIGS. 1-5, for example. The edges are created where two
surface areas of the stent intersect such as the outer surface and
the end surface; two end surfaces; or an end surface and a side
surface, for example. The edges that are coated may include any of
the edges in an end portion of the stent. It should be understood
that any one or any combination of these surfaces 20, 22, 24, 25,
and 27 may be coated. Generally, it is desirable to coat at least
the end surface or surfaces 24 and the edge or edges 25 most
proximate to the ends 24. In order to ensure that the coating
adheres to the edge 25 of the stent at least a minimal portion of
the outside or inside surface may also be coated. The coatings may
cover any single area or combination of areas desired. When coating
the outside, inside, edge and/or side surfaces 20, 22, 25 and 27, a
varying portion of the length of the stent may be covered (length
illustrated by 1 in FIG. 1). When coating one end portion of the
stent, such as the distal end portion for example, anywhere from
about 1% to 40% of the total stent may be coated. When coating both
the distal and proximal end portions of the stent anywhere from
about 2% to 80% of the stent may be coated. The length of the stent
end portion(s) that is(are) coated will depend on a number of
factors including the coatings used, results desired, stent
application, etc.
[0049] The coating 18 may be applied such that a solid layer of
coating covers the stent end portion (similar to FIG. 11) or the
coating may have apertures or perforations which may or may not
coincide with the pattern of the stent (similar to FIGS. 1-10).
[0050] The coating 18 may also be used as a drug delivery system to
prevent restenosis or for other treatment. The drugs may include
radiochemicals to irradiate and prohibit tissue growth. Angioplasty
and stent deployment may cause injury of the endothelial cell layer
of blood vessels, causing smooth muscle cell proliferation, leading
to restenosis. To control smooth muscle cell growth
endothelialization of cells on the inner wall surface of vessels
will prevent or prohibit the smooth muscle growth. To stimulate
endothelialization without provoking smooth muscle cell
proliferation human growth factors may be included in the outer
layer and delivered. Growth factors include VEGF, TGF-beta, IGF,
PDGF, FGF, etc. These growth factors are dispersed in the matrix of
the outer polymer coating 18 of the stent. All such materials are
referred to herein generally as "drugs".
[0051] For carrying drugs, a gel-like material may be used. It may
be applied over the coating 18 or directly to the stent 10 and used
as the coating 18. There are two ways to apply drugs to such
materials. The first way is to mix the drug with the materials,
then coat the mixture onto the stent. They can be cast as film or
sheet with drug together, then laminate to the core stent. A second
way is to coat or laminate polymer with the core stent without the
drug. The stent device is made, then sterilized. Due to their
gel-like nature, the stent can then be inserted into a drug
solution. The drug will be absorbed into/onto the gel. The stent
can then be delivered into the body. The drug will then be
released.
[0052] In one embodiment of the invention, the polymeric layer or
coating 18 may be polyethylene oxide containing Taxol. Other
coatings that may be used with a drug may be polymers such as
PGA/PLA, PEO/PLA or the like containing a drug such as Taxol or
hydrogen peroxide.
[0053] Preferred gel like materials for use as a coating for the
stent when drug delivery is desired are polyethylene oxide,
polyvinyl pyrrolidone, polyacrylates, and their blends or
copolymers or lightly crosslinked forms. Polyethylene glycol block
copolymer with polylactides or other polyesters are examples.
Hydrophilic polyurethane, poly(maleic anhydride-alt-ethylene) and
their derivatives are examples. Other materials are polysaccharides
and their derivatives. There are also sodium alginate, karaya gum,
gelatin, guar gum, agar, algin carrageenans, pectin, locust bean
gums, xanthan, starch-based gums, hydroxy alkyl and ethyl ethers of
cellulose, sodium carboxymethyl cellulose. Some of the materials
will be heated, then cooled, then a gel is formed. Some of the
above are food gels. Some of them are bioadhesives.
[0054] Any drugs may be used, singly or in combination. For
example, the drugs can be an anticoagulant, e.g. D-Phe-ProArg
chloromethyl ketone. An RGD peptide-containing compound, heparin,
antithrombin compounds, platelet receptor antagonists, antibodies,
aspirin, urokinase, protaglandin inhibitors, platelet inhibitors,
or antiplatelet peptide. The drug can be an inhibitor of vascular
cell growth, DNA, RNA, cholesterol-lowering agents, vasodilating
agents. The drug can be any drug such as Taxol, 5-Fluorouracil,
Beta-Estradiol, Tranilast, Trapidil, Probucol, Angiopeptin or any
combination of them.
[0055] Since there are many drugs and many polymers, the stent can
have multiple layers of different polymers with the same or
different drugs. For example, the stent can have two layers of the
same polymer coating 18 with one layer with drug and another layer
without drugs. The stent may have two layers of the same polymer
with two different drugs as another example.
[0056] In particular, various combinations of a cycling sinase
inhibitor identified as p21 and the vascular endothelial growth
factor identified as VEGF, an endothelial nitrogen, may preferably
be included in and dispensed from the coating polymer layer of a
stent.
[0057] Incorporation of drugs and growth factors into a polymer
layer can also be performed by several other methods, including the
solvent method, melting method, soaking method and spraying method.
If both polymer and drug have a cosolvent, a solution case will be
an easy way to provide the polymer matrix loaded with the drug or
growth factor. If the polymer can be melted at low temperature and
the drug or growth factor tolerates heating, a melting method can
be used to mix the drug or growth factor into the polymer matrix.
Also, a polymer-drug solution or suspension solution can be used
for coating to provide a layer containing the drug or growth
factor.
[0058] In another embodiment of the invention the coating may be a
film of bioadhesive. Bioadhesives glue body tissue together. Using
a bioadhesive for the coating serves two purposes. The stent is
smooth and if a tear has occurred the tissue can be repaired. In
this manner, blood flow will be maintained in a vessel, for
example. The bioadhesive may or may not also have drugs loaded for
delivery. Dissection, cutting or tearing occurs in some stent and
PTA or PTCA cases. Bioadhesives or surgical adhesives may be used
to repair the passage wall. However, these tears or cuts are not
necessarily discovered immediately. In those cases, a further
medical procedure must be undertaken to repair the wall. The
present invention eliminates some of these further medical
procedures as a bioadhesive is included in the coating 18 which is
delivered when the stent is deployed in place. The bioadhesive will
repair damage to the vessel wall and it may not be necessary to
undertake a further procedure to do the repair. The bioadhesive is
chosen as the coating for the stent or is used in addition to a
coating on the stent and is applied in a known manner to one or
both ends of the stent. The end or edge, side, outside and/or
inside of the stent may utilize the bioadhesive.
[0059] Any appropriate bioadhesive may be used. For example, the
following bioadhesives may be used singly or in combination:
[0060] cyanoacrylate: ethyl cyanoacrylate, butyl cyanoacrylate,
octyl cyanoacrylate, hexyl cyanoacrylate;
[0061] fibrin glue: fibrinogen/thrombin/Factor XIII/calcium as
catalyst gelatin-resorcinol-formol (GRF) glue: formed from gelatin,
resorcinol and water in the presence of formaldehyde,
glutaraldehyde and heat (45.degree. C.);
[0062] mussel adhesive protein, prolamine gel and transforming
growth factor beta(TGF-B);
[0063] polyacrylic acid, modified hypromellose, hydroxypropylmethyl
cellulose, hydroxypropylcellulose, carboxymethyl cellulose, sodium
alginate, gelatin, pectin, polyvinylpylindone, polyethylene glycol,
aldehyde relative multifunctional chemicals, polyallylsaccharose,
and polypeptides.
[0064] Referring now to FIGS. 2 and 3, another metal stent is
shown. An end portion of stent 26 is coated with a coating 28.
Another embodiment of the invention includes a metal stent
configuration such as the type shown in part in FIG. 4. Both end
portions of stent 30 are coated with a coating 32. These
embodiments of FIGS. 2-4 include any appropriate coating utilized
as described above and the coating may contain drugs for release
and the coating may be a bioadhesive or include a bioadhesive. The
stent may be coated on the outer surface only or may be coated on
the inner surface as well. The end or edge would also be coated, if
desired. One or both ends of the stent may be coated.
[0065] It is also contemplated that a stent according to the
invention may be of polymeric material. The stents may be of any
configuration and may be of a biodegradable or nonbiodegradable
polymeric material. A coating or coatings as described above are
utilized on one or both ends of the polymeric stent to reduce
injury to body passages and reduce restenosis and possible further
medical procedures as described above. The coating may be multiple
or single layers and be chosen from a variety of suitable
biocompatible coatings. The coating may also include drugs for
delivery and/or a bioadhesive may be utilized.
[0066] Another stent is shown in FIG. 5. The stent is generally
designated 34. The stent may be composed of a series of strands
arranged in a crossing configuration which may be woven, braided or
the like or alternatively it may be formed of a polymeric sheet.
The end portion of stent 34 includes a coating 36. The coating may
be applied by any various standard methods such as dipping,
spraying, painting, etc.
[0067] FIGS. 6 and 7 show yet another stent configuration utilizing
a coating on one or both ends. The coil stent 38 includes a coating
40 on both the distal and proximal end portions of the wire member
which forms the stent in a preferred embodiment. The appropriate
coatings described herein may be utilized with this stent. The
coating may be applied to the wire member and then formed or the
stent may be formed and lastly, the coating may be applied. Of
course, the appearance of both types of stent will differ. One or
both end portions may be coated and the coating may be applied to
the various areas of the end portions as described earlier.
[0068] FIG. 8 shows yet another stent form, a variation of which is
shown in FIGS. 9 and 10, the variation comprising apertures in a
sheet like body portion. Both of these stents may be regarded as
being formed from a rolled up flat sheet comprised of a metal or a
polymeric material having a coating 42 on one or both end portions.
The coating 42 is of the type described in this application and may
be applied to various areas of the stent as described herein.
[0069] Materials suitable for use in forming the polymeric stents
to which the invention relates are such that when fabricated to a
desired geometry they will afford the stent sufficient strength and
support for the particular intended use. Suitable materials do not
produce toxic reactions or act as carcinogens. The preferred core
polymeric stent materials are those such as are set forth below,
which list is not exhaustive but exemplary only: Poly(L-lactide)
(PLLA), Poly(D,L-lactide) (PLA), poly(glycolide) (PGA),
poly(L-lactide-co-D,L-lactide) (PLLA/PLA),
poly(L-lactide-co-glycolide) (PLLA/PGA),
poly(D,L-lactide-co-glycolide) (PLA/PGA),
poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polydioxanone
(PDS), Polycaprolactone (PCL), polyhydroxybutyrate (PHBT),
poly(phosphazene) poly(D,L-lactide-co-caprolactone) PLA/PCL),
poly(glycolide-co-caprolactone) (PGA/PCL) and poly(phosphate
ester).
[0070] Referring now to FIG. 11 another stent of the invention is
shown. The stent 44 includes at least one sleeve 46 which is
designed and configured to fit over the end of a stent. The sleeve
46 is generally hollow like the stent, having a flow passage
therethrough. In the preferred embodiment shown, the sleeve is a
hollow cylindrical configuration which is connected to overlay the
end portion(s) of the stent. The sleeve 46 shown in FIG. 11
overlays both the inside and outside of the stent end when it is
attached. The sleeve includes an inner wall 48 and an outer wall 50
having a space therebetween wherein the inner wall 48 is adjacent
the inside of the stent and the outer wall 50 is adjacent the
outside of the stent. In this manner, the sleeve 46 receives the
end of the stent in the space provided between the inner and outer
walls. However, it is contemplated that the sleeve could be of a
design such that the inner surface of the stent is not covered. The
sleeve 46 may also be designed to be slightly longer in length than
the stent body so that the sleeve extends beyond the end of the
metal or polymeric body. It should also be understood that the
sleeve 46 may be of any configuration which will receive the end of
any configured stent. Of course, stents of any configuration, shape
and materials may be utilized.
[0071] The sleeve may be utilized on any stent configuration
including, but not limited to, those shown in the figures of this
application. The sleeve may be made of any appropriate material as
described herein and may include drugs and/or a bioadhesive as
discussed above. It should also be understood that it is also
contemplated that the sleeve include one or more layers of material
including drugs and/or bioadhesives. The materials used may be
permanent or biodegradable. It is further contemplated that the
sleeve may have a solid wall as shown in FIG. 11 or the wall may be
perforated or may be of any design which may or may not coincide
with the design of the stent body. The sleeve may be designed to
cover various lengths of the stent and if a sleeve is utilized on
both ends of the stent they would not necessarily be of the same
length.
[0072] The sleeve may be bonded to the stent in a number of ways.
The sleeve may of a material that has elastic properties so that it
will stay in place on the stent end portion. The sleeve may also be
bonded to the stent by use of an adhesive. The adhesive would be an
appropriate biocompatible adhesive such as those bioadhesives
listed earlier in this description, for example, polyurethane and
epoxy adhesive. It is also contemplated that the sleeve may be
bonded to the stent by the use of heat and pressure. In this
manner, the stent will be partially embedded in the sleeve.
[0073] Another embodiment of the invention contemplates the use of
a metal stent where the stent end or ends have been formed and/or
treated so as to be smooth and flexible. Any metal stent may be
utilized including but not limited to those shown in FIGS. 1-4. The
stent would be manufactured so that the ends would be more flexible
and the edges or ends are smoothed to eliminate any sharp edges,
jagged areas, or bumps and the like. In order to achieve the
additional smoothness the stent may be electropolished and/or
tumbled. In this manner, the edges are rounded or smoothed out so
that the possibility of damage to a passage is lessened. The stent
may also be heat treated to provide improved flexibility in the end
portions. The increase in flexibility also decreases the chances of
injury to a passage. The stent will bend more easily which will
reduce damage which could be caused by a more rigid device. Methods
for smoothing articles are known in the art and other appropriate
known methods may be used. It is known that heat treating will add
flexibility to a metal. Any other method which will provide
enhanced smoothness and flexibility to the stent may be
utilized.
[0074] For example, it is also contemplated that a stent with
flexible ends may be provided by utilizing a tighter mesh in the
center portion of the stent and a looser mesh on one or both end
portions of the stent. Any type of mesh, pattern or braid may be
utilized with this embodiment. Such a stent is shown in FIG. 12.
The end portions 54 and 56 are of a looser configuration which
allows for more flexibility in the end portions. Such a stent may
also be treated by methods such as those described above to provide
more flexibility and the stent may also be treated to provide for
smooth edges or ends. Any stent pattern may be reconfigured to
provide for more numerous or tighter struts in the center and less
numerous or looser struts on one or both ends.
[0075] Another embodiment of a stent in accordance with the
invention would include a metal stent which has been treated in
accordance with the above methods to be smooth and flexible and
then is coated as described earlier in this description.
[0076] Yet another embodiment of the invention is a metal stent
where different materials of varying flexibility are utilized for
portions of the stent body. Such a stent may be configured as shown
in FIGS. 1-4 although any stent configuration is appropriate. In a
preferred embodiment, such a stent would be of stainless steel in
the center portion. The end portions would be of Nitinol, a known
nickel and titanium alloy. Nitinol is known to be more flexible
than stainless steel. Other appropriate materials may be utilized
to provide flexible ends and a more rigid center portion which
provides the strength needed in a stent. One or both ends may be of
a more flexible material than the center portion. Such a stent may
also utilize the above mentioned material treating methods to
provide more smooth and flexible ends. For example, if Nitinol ends
are utilized, they may be heat treated to add flexibility. Such a
stent may also include coated potions as discussed above.
[0077] Any of the above described embodiments may be utilized where
appropriate in vascular or nonvascular, respiratory,
gastro-intestinal, rectal, urethral, and vaginal routes.
[0078] The above Examples and disclosure are intended to be
illustrative and not exhaustive. These examples and description
will suggest many variations and alternatives to one of ordinary
skill in this art. All these alternatives and variations are
intended to be included within the scope of the attached claims.
Those familiar with the art may recognize other equivalents to the
specific embodiments described herein which equivalents are also
intended to be encompassed by the claims attached hereto.
* * * * *