U.S. patent application number 10/164989 was filed with the patent office on 2002-10-24 for stent configurations.
This patent application is currently assigned to SCIMED LIFE SYSTEMS, INC.. Invention is credited to Ehr, Timothy G.J., Kveen, Graig L..
Application Number | 20020156524 10/164989 |
Document ID | / |
Family ID | 22537143 |
Filed Date | 2002-10-24 |
United States Patent
Application |
20020156524 |
Kind Code |
A1 |
Ehr, Timothy G.J. ; et
al. |
October 24, 2002 |
Stent configurations
Abstract
Improved stent configurations exhibiting limited recoil,
resistance to compression and improved longitudinal flexibility are
disclosed. The stent comprised of a plurality of annular elements
aligned to form a cylindrical stent body. The annular elements are
comprised of a plurality of open, generally boomerang-shaped
segments interconnected top-to-bottom around each of the annular
elements. Adjacent annular elements are interconnected by
interconnecting element.
Inventors: |
Ehr, Timothy G.J.; (Elk
River, MN) ; Kveen, Graig L.; (Maple Grove,
MN) |
Correspondence
Address: |
VIDAS, ARRETT & STEINKRAUS, P.A.
6109 BLUE CIRCLE DRIVE
SUITE 2000
MINNETONKA
MN
55343-9185
US
|
Assignee: |
SCIMED LIFE SYSTEMS, INC.
One SciMed Place
Maple Grove
MN
55311-1566
|
Family ID: |
22537143 |
Appl. No.: |
10/164989 |
Filed: |
June 6, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10164989 |
Jun 6, 2002 |
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09707447 |
Nov 7, 2000 |
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09707447 |
Nov 7, 2000 |
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09151053 |
Sep 10, 1998 |
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6193744 |
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Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
A61F 2/91 20130101; A61F
2/915 20130101; A61F 2002/91541 20130101; A61F 2002/91558 20130101;
A61F 2002/91525 20130101 |
Class at
Publication: |
623/1.15 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is as follows:
1. A generally cylindrical, radially expandable stent comprised of
a plurality of annular elements aligned to form a cylindrical stent
body, each element comprised of a plurality of open,
boomerang-shaped segments, each segment having a top and a bottom,
the segments interconnected top-to-bottom around each of the
annular elements, adjacent annular elements interconnected in one
or more places.
2. The stent of claim 1 wherein adjacent annular elements are
interconnected by one or more interconnecting elements, each
interconnecting element extending from an end of a boomerang-shaped
segment in one annular element to an end of a boomerang-shaped
segment in an adjacent annular element.
3. The stent of claim 1 wherein an interconnecting element extends
from each boomerang-shaped segment in an annular element to a
boomerang-shaped segment in an adjacent annular element.
4. The stent of claim 3 wherein an interconnecting element extends
from each boomerang-shaped segment in an annular element to a
neighboring boomerang-shaped segment in an adjacent annular
element.
5. The stent of claim 1 wherein each interconnecting element has
one or more bends therein.
6. The stent of claim 5 wherein each interconnecting element is a
U-shaped segment.
7. The stent of claim 5 wherein each interconnecting element is a
zig-zag-shaped segment.
8. The stent of claim 1 wherein at least a portion of each
interconnecting element is curvilinear
9. The stent of claim 1 wherein each boomerang-shaped segment is
symmetric about a midline extending from the top of the segment to
the bottom of the segment, the midline situated midway between the
ends of the segments
10. The stent of claim 1 wherein each bottom has a dimple
therein.
11. The stent of claim 1 made of metal.
12. The stent of claim 11 made of stainless steel.
13. The stent of claim 11 wherein the metal is a shape memory
metal.
14. The stent of claim 1 made of a bio-compatible material.
15. A generally cylindrical, radially expandable stent comprised of
a plurality of annular elements aligned to form a cylindrical stent
body, each element comprised of a plurality of open,
boomerang-shaped segments interconnected top-to-bottom around each
of the annular elements, and interconnecting U-shaped elements
interconnecting adjacent ends of each boomerang-shaped segment to a
neighboring segment in an adjacent annular element.
16. A generally cylindrical, radially expandable stent comprised of
a plurality of annular elements aligned to form a cylindrical stent
body, each element comprised of a plurality of open,
boomerang-shaped segments, each segment having a top and a bottom,
adjacent segments in an annular element connected by a link
extending from the top of a segment to the bottom of an adjacent
segment, adjacent annular elements interconnected by one or more
interconnecting elements, each interconnecting element extending
from an end of a boomerang-shaped segment in one annular element to
an end of a boomerang-shaped segment in an adjacent annular
element.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to stents of improved
configuration.
[0003] 2. Brief Description of the Prior Art
[0004] Stents are radially expandable endoprosthesis which are
typically intravascular implants capable of being implanted
transluminally and enlarged radially after being introduced
percutaneously. They have also been implanted in urinary tracts and
bile ducts. They are used to reinforce body vessels and to prevent
restenosis following angioplasty in the vascular system. They may
be self-expanding or expanded by an internal radial force, such as
when mounted on a balloon.
[0005] In the past, stents have been generally tubular but have
been composed of many configurations and have been made of many
materials, including metals and plastic. Ordinary metals such as
stainless steel have been used as have shape memory metals such as
Nitinol and the like. Stents have also been made of biodegradable
plastic materials. Such stents have been formed from wire, tube
stock, etc. Some stents are self-expanding and some are expanded by
an interior radial force.
SUMMARY OF THE INVENTION
[0006] This invention provides new configurations of the segments
making up stents which may be adapted to all of the various types
of prior art stents described configurations. For example, the
configurations of the invention limit recoil and add resistance to
compression for an expanded stent, among other things. Also, the
stents of this invention are longitudinally flexible.
[0007] The inventive stents comprise a plurality of annular
elements aligned to form a cylindrical stent body. Each annular
element, in turn, is comprised of a plurality of open, generally
boomerang-shaped segments. The segments are interconnected
top-to-bottom around each of the annular elements. Adjacent annular
elements are interconnected by one or more interconnecting
elements. Each interconnecting element extends from an end of a
boomerang-shaped segment in one annular element to an end of a
boomerang-shaped segment in an adjacent annular element. In a
preferred embodiment an interconnecting element extends from each
boomerang-shaped segment in an annular element to a neighboring
boomerang-shaped segment in an adjacent annular element.
[0008] Interconnecting elements joining adjacent annular elements
are desirably U-shaped or zig-zag shaped, although other
curvilinear and rectilinear interconnecting elements may also be
used.
[0009] Adjacent boomerang-shaped segments in an annular element may
be interconnected via a link extending from the top of a segment to
the bottom of an adjacent segment. The links may range in design
from a short, straight connector to any of the shapes described
below for the interconnecting elements.
Brief Description of the Figures
[0010] FIG. 1 is a schematic showing boomerang shapes;
[0011] FIG. 2 is a flat plan view of an embodiment of a stent
configuration of the invention in the unexpanded condition;
[0012] FIG. 3 is a longitudinal view of the stent of FIG. 2 in its
normal tubular unexpanded condition;
[0013] FIG. 4 is a flat plan view of an embodiment of a stent
configuration of the invention in the unexpanded condition;
[0014] FIG. 5 is a longitudinal view of the stent of FIG. 3 in its
tubular, expanded condition;
[0015] FIG. 6 is an interconnecting element that may be used to
join adjacent annular elements in another embodiment of the
invention; and
[0016] FIG. 7 is a view of the stent of FIG. 3 after being
bent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] For the purposes of this invention, the term boomerang is
used to describe the shape of certain stent segments and is used in
the sense as described in the Websters New Collegiate Dictionary
with reference to FIG. 1 hereof:
[0018] "boomerang 1: A bent or angular throwing club which can be
thrown so as to return near the starting point."
[0019] An embodiment of a generally cylindrical stent according to
the invention is illustrated in the flat at 110 in FIG. 2 or FIG.
4. The stent may be formed of a metal tube such as nitinol, or
stainless steel preferably, which has been etched or preferably
laser cut to the configuration shown in the flat plan view of FIGS.
2 or 4. The configuration may be formed in flat sheet and rolled
into a cylinder with a welded seam or the like joining together
edges 112 and 114, or the configuration may be formed directly in a
small tube such as a hypotube. A tubular form of the stent is shown
generally at 210 in FIG. 3.
[0020] The configurations shown in FIGS. 2-4 are made up of a
plurality of aligned annular elements 114 aligned as shown to
provide a generally cylindrical stent body. Each annular element
114 is comprised of a series of generally boomerang shaped segments
indicated at 118 (see darkened segment in the Figures for clarity)
having an open structure joined top 120 to bottom 122 at segment
junction 124. Segments 118 are arranged or networked as shown in
the Figures with ends 126 of neighboring segments on adjacent
annular elements joined by interconnecting elements 128. In FIGS.
2-4, interconnecting element 128 is a U-shaped element which is a
partly open curve. Alternative interconnecting elements including
zig-zag shaped element 228 as shown in FIG. 6, which may be used in
place of U-shaped element 128 to join adjacent annular elements 114
together.
[0021] The configurations of FIGS. 2 and 4 are substantially
similar to one another, differing principally in the presence of a
dimple 130 in each bottom 122 of each segment 118 in the
configuration of FIG. 4. Without being bound by a particular
theory, it is believed that the presence of the dimple limits the
extent to which the stent buckles out of the plane on
expansion.
[0022] It is desirable that the boomerang-shaped segments be at
least substantially symmetric about a midline 138 extending from
the top 120 of the segment to the bottom 122 of the segment.
Midline 138 is situated midway between ends 126 of the segment.
[0023] When the stent of FIG. 2 is expanded, as shown generally at
310 in FIG. 5 on a balloon for example, the boomerang-shaped
segments 118 of the unexpanded stent take on a new configuration.
The segments 318 take on the shape of rounded triangles with
bulging bottoms 322.
[0024] It is desirable that the interconnecting elements be
U-shaped as shown in FIGS. 2 and 4 or zig-zag shaped as shown in
FIG. 6. However, in a more general sense, the invention
contemplates the use of curvilinear as well as rectilinear
interconnecting elements, including straight elements. Examples of
other suitable connectors are disclosed in U.S. patent application
Ser. No. 09/111531 filed Jul. 8, 1998, U.S. patent application Ser.
No. 08/846,164 filed Apr. 25, 1997, WO 97/32543 to Divysio
Solutions LTD. and WO 97/40780 to David G. Jang, all of which are
incorporated herein by reference. Of course, adjacent
boomerang-shaped segments may also be joined side-by-side with a
region of overlap between adjacent boomerang-shaped segments.
[0025] It is also desirable that interconnecting elements be
flexible so as to accommodate bending of the stent without
substantial distortion of the boomerang-shaped segments. FIG. 7
shows the stent of FIG. 3 having been bent. As shown in FIG. 7, as
the stent is bent, interconnecting elements in tension open while
interconnecting elements in compression close to accommodate
bending of the stent.
[0026] Although as shown in the Figures an interconnecting element
extends from each boomerang-shaped segment in an annular element to
a nearest neighboring boomerang-shaped segment in an adjacent
annular element, the invention further contemplates the possibility
of an interconnecting element extending from each boomerang-shaped
segment in an annular element to a next-nearest neighboring
boomerang-shaped segment in an adjacent annular element. In the
latter case, the first end 140 and second end 144 of each
interconnecting element 128 would be circumferentially offset along
the stent.
[0027] In a more general sense, the invention further contemplates
a stent in which each adjacent annular element is interconnected by
one or more interconnecting elements and each interconnecting
element extends from an end of a boomerang-shaped segment in one
annular element to an end of a boomerang-shaped segment in an
adjacent annular element. As such, an interconnecting element need
not extend from each boomerang-shaped segment. An example of this
is a stent in which interconnecting elements extend from every
second or third boomerang-shaped segment in an annular element.
[0028] The invention also contemplates the possibility of altering
the orientation of some of the annular elements. In one such
embodiment, adjacent annular elements in the flat pattern are
rotated by 180.degree. relative to one another so that adjacent
annular elements point in opposite directions.
[0029] Although the ends of nearest neighboring segments in
adjacent annular elements are shown in the figures as aligned with
one another along the circumference of the stent, the invention
further contemplates embodiments of the stent in which nearest
neighboring segments in adjacent annular elements are
circumferentially displaced relative to one another.
[0030] In yet another series of embodiments, adjacent (or
non-adjacent) annular elements may be formed of different sized
boomerang-shaped elements. As such, adjacent (or non-adjacent)
annular elements may span different lengths. Alternatively,
adjacent (or non-adjacent) annular elements may comprise different
numbers of boomerang-shaped segments.
[0031] Although in the embodiment of FIGS. 2-4, segment junction
124 is shown as a small, straight link extending from the top of
one segment to the bottom of an adjacent segment, the invention
also contemplates the possibility of adjacent boomerang-shaped
segments within an annular element being connected by U shaped
links, zig-zag shaped links or any of the shapes disclosed above
for the interconnecting elements. Additionally, other shaped
segments may be interspersed among the boomerang-shaped
segments.
[0032] The inventive stent may be self-expanding or mechanically
expandable such as by balloon. The stent may be made of a variety
of suitable bio-compatible materials including metal, plastic and
any other material capable of functioning as an expandable stent.
For example, the stent may be of metal wire or ribbon such as
tantalum, stainless steel or the like or of metal sheeting or metal
tubing. It may be thin-walled. It may be of shape memory alloy such
as Nitinol or the like.
[0033] 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.
* * * * *