U.S. patent application number 13/332307 was filed with the patent office on 2012-06-14 for longitudinally flexible expandable stent.
Invention is credited to Brian J. Brown, Timothy J. Ley.
Application Number | 20120150280 13/332307 |
Document ID | / |
Family ID | 27393720 |
Filed Date | 2012-06-14 |
United States Patent
Application |
20120150280 |
Kind Code |
A1 |
Brown; Brian J. ; et
al. |
June 14, 2012 |
LONGITUDINALLY FLEXIBLE EXPANDABLE STENT
Abstract
Segmented articulatable stent of open structure comprised of
end-connected struts of first and second lengths making up first
and second segments with angular interconnects between adjacent
first and second segments.
Inventors: |
Brown; Brian J.; (Hanover,
MN) ; Ley; Timothy J.; (Shoreview, MN) |
Family ID: |
27393720 |
Appl. No.: |
13/332307 |
Filed: |
December 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13195581 |
Aug 1, 2011 |
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13332307 |
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10705273 |
Nov 10, 2003 |
7988717 |
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13195581 |
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09197278 |
Nov 20, 1998 |
7204848 |
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10705273 |
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08511076 |
Aug 3, 1995 |
6818014 |
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09197278 |
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08396569 |
Mar 1, 1995 |
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08511076 |
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10800572 |
Mar 15, 2004 |
8114146 |
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13195581 |
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09197278 |
Nov 20, 1998 |
7204848 |
|
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10800572 |
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08511076 |
Aug 3, 1995 |
6818014 |
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09197278 |
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08396569 |
Mar 1, 1995 |
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08511076 |
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Current U.S.
Class: |
623/1.16 |
Current CPC
Class: |
A61F 2002/91525
20130101; A61F 2002/91583 20130101; A61F 2/91 20130101; A61F
2002/91508 20130101; A61F 2002/91533 20130101; A61F 2/89 20130101;
A61F 2/82 20130101; A61F 2002/91516 20130101; A61F 2230/0054
20130101; A61F 2210/0019 20130101; A61F 2250/0018 20130101; A61F
2/915 20130101; A61F 2220/005 20130101; A61F 2/88 20130101; A61F
2002/91558 20130101; A61F 2220/0058 20130101 |
Class at
Publication: |
623/1.16 |
International
Class: |
A61F 2/82 20060101
A61F002/82 |
Claims
1. (canceled)
2. An expandable stent, comprising: a plurality of adjacent
cylindrical band-like elements axially spaced along a longitudinal
axis, the cylindrical band-like elements being contiguous patterns
forming cylinders around the longitudinal axis, the cylindrical
band-like elements joined together by a plurality of
interconnecting constituents, the interconnecting constituents
joining two or more other constituents of the stent; wherein each
interconnecting constituent is nonparallel with respect to the
longitudinal axis; wherein the cylindrical band-like elements
comprise a plurality of substantially linear portions joined
together by a plurality of curved portions, wherein at least one
cylindrical band-like element includes a repeating pattern of a
first segment extending between two interconnecting constituents
and having three substantially linear portions alternating with a
second segment extending between two interconnecting constituents
and having five substantially linear portions and a plurality of
expandable continuous substantially repeating patterns coursing
along the stent in a helical manner and consisting of a plurality
of the first segments connected by the interconnecting
constituents, wherein the other constituents include cylindrical
band-like elements.
3. The expandable stent of claim 2, wherein the stent is in an
unexpanded state.)
4. The expandable stent of claim 2, wherein the stunt is in an
expanded state.
5. The expandable stent of claim 2, wherein the curved portions of
at least two adjacent cylindrical band-like elements are
circumferentially offset from one another.
6. The stent of claim 2, wherein each cylindrical element is
bounded by an upper plane and a lower plane parallel to the upper
plane.
7. The stent of claim 2, wherein a linear portion of the
interconnecting constituent forms an angle of at least
approximately 14 degrees with respect to the longitudinal axis.
8. The stent of claim 7, wherein the linear portion of the
interconnecting constituent forms an angle less than approximately
45 degrees with respect to the longitudinal axis.
9. An expandable stent, comprising: a plurality of expandable
continuous substantially repeating patterns each coursing along the
stent in a helical manner, each repeating pattern including
plurality of first circumferential elements alternating with a
plurality of interconnecting constituents, each first
circumferential element being a contiguous element coursing in a
circumferential manner about the stent and, spanning between two
interconnecting constituents and comprising three substantially
parallel linear portions, each interconnecting constituent joining
two or more other constituents of the stent and, including a linear
segment set a first angle less than approximately 90 degrees and
greater than 0 degree with respect to a longitudinal axis; and a
plurality of adjacent, non-helical cylindrical band-like elements
being contiguous patterns forming cylinders around the stent
longitudinal axis, each cylindrical band-like element formed from a
plurality of second circumferential segments elements alternating
with the first circumferential elements, the cylindrical band-like
elements being attached to one another by interconnecting
constituents, the second circumferential segments being contiguous
elements coursing in a circumferential manner about the stent and
spanning between two interconnecting constituents, wherein the
other constituents Include first and second circumferential
segments.
10. The stent of claim 9, wherein the second circumferential
segments of at least two adjacent cylindrical band-like elements
are circumferentially offset from one another.
11. The stent of claim 9, wherein at least one second
circumferential segment includes five linear portions joined
together by curved portions.
12. The stent of claim 9, wherein each cylindrical band-like
element forms an individual cylinder defining an upper planar
boundary and a lower planar boundary parallel to the upper planar
boundary.
13. The stent of claim 9, wherein the first angle is at least
approximately 14 degrees.
14. The stent of claim 9, wherein each of the three linear portions
of at least one of the first circumferential elements are
nonparallel to the longitudinal axis.
15. The stem of claim 9, wherein the stent is in an unexpanded
state.
16. The stent of claim 9, wherein the stent is in an expanded
state.
17. An expanded stem, comprising: a plurality of expandable
continuous substantially repeating patterns coursing along the stem
in a helical manner and including a plurality of circumferential
elements and a plurality of interconnecting constituents, the
interconnecting constituents joining two or more other constituents
of the stent, each circumferential element being a contiguous
element coursing in a circumferential manner about the stent and
spanning between two interconnecting constituents and comprising
three linear portions joined by curved portions, and each
interconnecting constituents including a linear segment set at a
first angle with respect to a longitudinal axis; and a plurality of
adjacent cylindrical band-like elements, each cylindrical band-like
element forming an individual cylinder defining an upper planar
boundary and a lower planar boundary parallel to the upper planar
boundary, each cylindrical band-like element formed from a
plurality of circumferential segments alternating with at least two
of the circumferential elements, and the cylindrical band-like
elements being contiguous patterns forming cylinders around the
stent longitudinal axis, wherein at least one circumferential
segment extends between two interconnecting constituents and
includes five linear portions joined together by curved portions,
wherein the circumferential segments of at least two adjacent
cylindrical band-like elements are circumferentially offset from
one another, and wherein the other constituents include
circumferential elements and circumferential segments, wherein the
cylindrical band-like elements are attached to one another by the
interconnecting constituents.
18. An expandable stent, comprising: a plurality of adjacent non-
helical serpentine bands axially spaced along a longitudinal axis,
the serpentine bands joined together by a plurality of
interconnecting struts, wherein each interconnecting strut includes
a substantially linear portion nonparallel with respect to the
longitudinal axis; wherein the serpentine bands comprise a
plurality of straight portions joined together by a plurality of
cured portions, wherein at least one serpentine band includes a
repeating pattern of a first segment extending between two
interconnecting struts and having three straight portions
alternating with a second segment extending between two
interconnecting struts and having five straight portions, the first
and second segments being contiguous elements coursing in a
circumferential manner about the stent, and a plurality of
continuous substantially repeating patterns coursing along the
stent in a helical manner and consisting of plurality of the first
segments alternating with a plurality of the interconnecting
struts.
19. The stent of claim 18, wherein the curved portions of at least
two adjacent serpentine bands are circumferentially offset from one
another.
20. The stem of claim 18, wherein each serpentine band is bounded
by an upper plane and a lower plane parallel to the upper
plane.
21. The stent of claim 18, wherein the three straight portions are
substantially parallel.
22. The stent of claim 18, wherein the five straight portions are
substantially parallel.
23. The stent of claim 18, wherein the stent is in an unexpanded
state.
24. The stent of claim 18, wherein the stent is in an expanded
state.
25. The stem of claim 2, wherein the three substantially linear
portions are substantially
26. The stent of claim 2, wherein the five substantially linear
portions are substantially parallel.
27. The stent of claim 17, wherein the curved portions of at least
two adjacent cylindrical band-like elements are circumferentially
offset from one another.
Description
[0001] This application is a Continuation of Ser. No. 10/705,273,
filed Nov. 10, 2003, which is Continuation of Ser. No. 09/197,278,
filed Nov. 20, 1998, and issued as U.S. Pat. No. 7,204,848 on Apr.
17, 2004, which is a Continuation-in-Part of application Ser. No.
08/511,076, filed Aug. 3, 1995, and issued as U.S. Pat. No.
6,818,014 on Nov. 16, 2004, which is a Continuation-in-Part of
application Ser. No. 08/396,569, abandoned, filed Mar. 1, 1995, the
disclosures of which are hereby incorporated by reference.
[0002] Further, this application is a Continuation of Ser. No.
10/800,572, filed Mar. 15, 2004, which is Continuation of Ser. No.
09/197,278, filed Nov. 20, 1998, and issued as U.S. Pat. No.
7,204,848 on Apr. 17, 2004, which is a Continuation-in-Part of
application Ser. No. 08/511,076, filed Aug. 3, 1995, and issued as
U.S. Pat. No. 6,818,014 on Nov. 16, 2004, which is a
Continuation-in-Part of application Ser. No. 08/396,569, abandoned,
filed Mar. 1, 1995, the disclosures of which are hereby
incorporated by reference.
FIELD OF THE INVENTION
[0003] This invention relates to an endoprosthesis device for
implantation within a body vessel, typically a blood vessel. More
specifically, it relates to a tubular expandable stent of improved
longitudinal flexibility.
BACKGROUND OF THE INVENTION
[0004] Stents are placed or implanted within a blood vessel for
treating stenoses, strictures or aneurysms therein. They are
implanted to reinforce collapsing, partially occluded, weakened, or
dilated sections of a blood vessel. They have also been implanted
in the urinary tract and in bile ducts.
[0005] Typically, a stent will have an unexpanded (closed) diameter
for placement and an expanded (opened) diameter after placement in
the vessel or the duct. Some stents are self-expanding and some are
expanded mechanically with radial outward force from within the
stent, as by inflation of a balloon.
[0006] An example of the latter type is shown in U.S. Pat. No.
4,733,665 to Palmaz, which issued Mar. 29, 1988, and discloses a
number of stent configurations for implantation with the aid of a
catheter. The catheter includes an arrangement wherein a balloon
inside the stent is inflated to expand the stent by plastically
deforming it, after positioning it within a blood vessel.
[0007] A type of self-expanding stent is described in U.S. Pat. No.
4,503,569 to Dotter which issued Mar. 12, 1985, and discloses a
shape memory stent which expands to an implanted configuration with
a change in temperature. Other types of self-expanding stents not
made of shape memory material are also known.
[0008] This invention is directed to stents of all these types when
configured so as to be longitudinally flexible as described in
detail hereinbelow. Flexibility is a desirable feature in a stent
so as to conform to bends in a vessel. Such stents are known in the
prior art. Examples are shown in U.S. Pat. No. 4,856,516 to
Hillstead; U.S. Pat. No. 5,104,404 to Wolff; U.S. Pat. No.
4,994,071 to MacGregor; U.S. Pat. No. 5,102,417 to Palmaz; U.S.
Pat. No. 5,195,984 to Schatz; U.S. Pat. No. 5,135,536 to Hillstead;
U.S. Pat. 5,354,309 to Shepp-Pesch et al.; EPO Patent Application 0
540 290 A2 to Lau; EPO Patent Application No. 0 364 787 B1 to
Schatz, and PCT Application WO 94/17754 (also identified as German
Patent Application 43 03 181).
[0009] Generally speaking, these kinds of stents are articulated
and are usually formed of a plurality of aligned, expandable,
relatively inflexible, circular segments which are interconnected
by flexible elements to form a generally tubular body which is
capable of a degree of articulation or bending. Unfortunately, a
problem with such stents is that binding, overlapping or
interference can occur between adjacent segments on the inside of a
bend due to the segments moving toward each other and into contact
or on the outside of a bend the segments can move away from each
other, leaving large gaps. This can lead to improper vessel
support, vessel trauma, flow disturbance, kinking, balloon burst
during expansion, and difficult recross for devices to be installed
through already implanted devices and to unsupported regions of
vessel.
[0010] A diamond configuration with diagonal connections between
each and every diamond of each segment is also known but such
closed configurations lack flexibility.
[0011] It is an object of this invention to provide a
longitudinally flexible stent of open configuration that avoids
these problems and exhibits improved flexibility (radially and
longitudinally) in the stent body segments thereof rather than in
flexible joints between the segments.
[0012] It is a further object of the present invention to provide a
stent that is flexible yet also allows for side branch access.
SUMMARY OF THE INVENTION
[0013] It is a goal of the present invention to provide a flexible
stent formed of interconnected bands which provides for side branch
access and which further avoids the problem of pinching or overlap
between adjacent bands. Pinching or overlap is avoided where peaks
and troughs of adjacent bands are circumferentially displaced
relative to each other. The stents of the present invention
accomplish this goal by having different bands characterized by
different wavelengths over the length of the stent and/or disposing
the interconnecting members in such a way that after expansion of
the stent, the phase relationship between adjacent bands is altered
with the peaks and troughs displaced circumferentially relative to
each other.
[0014] The inventive expandable stents are formed of a plurality of
interconnected band-like elements characterized by alternating
peaks and troughs. The ends of the interconnecting members which
join adjacent bands are circumferentially offset and optionally,
longitudinally offset. Peaks and troughs in adjacent bands are
circumferentially offset as well so that the stent, in an expanded
state, will have minimal overlap of peaks and troughs.
[0015] To this end, the invention provides a tubular, flexible,
expandable stent, comprising a plurality of undulating band-like
elements of a selected wavelength or wavelengths. The band-like
elements have peaks and troughs and are aligned on a common
longitudinal axis to define a generally tubular stent body. The
peaks and troughs take a generally longitudinal direction along the
stent body. Adjacent band-like elements may be in phase or out of
phase with each other. The inventive stents further comprise a
plurality of interconnecting elements having first ends and second
ends. The first and second ends extend from adjacent band-like
elements and are displaced from one another in a longitudinal
direction and in a radial direction along the stent. Desirably,
upon expansion of the stent, at least some of the peaks and troughs
of a given band-like element are displaced relative to each other
about the periphery of the stent to accommodate longitudinal
flexing of the stent within the band-like elements and without
interference between adjacent band-like elements.
[0016] In one embodiment, two different types of band-like elements
are present in the stent, first band-like elements with a first
selected wavelength and second band-like elements with a second
selected wavelength exceeding the first selected wavelength. The
first and second band-like elements preferably alternate over the
length of the stent. Although the terminology of `first band-like
element` and `second band-like element` is used, it is not intended
to convey the relative order of appearance of the elements in the
inventive stents.
[0017] In another embodiment, two different types of band-like
elements are present, first and second band-like elements, each of
which has peaks and troughs. The first band-like elements have more
peaks (or troughs) than the second band-like elements. Similarly,
the invention is also directed to embodiments having first and
second band-like elements with peaks and troughs where the peaks
(or troughs) of the first band-like elements are spaced closer
together than the peaks (or troughs) of the second band-like
elements.
[0018] In another embodiment in which band-like elements of only
one wavelength are present, adjacent bands are about 180E out of
phase with one another. Interconnecting elements extend at an
oblique angle relative to the longitudinal axis from a peak to a
trough on an adjacent band.
[0019] In another embodiment in which band-like elements of only
one wavelength are present, peaks from which interconnecting
elements emanate are elongated relative to the peaks which are not
connected to troughs and similarly, the troughs from which
interconnectors emanate are elongated relative to troughs which are
not connected to peaks. Further, each interconnecting element
extends from the side of a peak to the side of a trough on an
adjacent band.
[0020] In yet another embodiment in which band-like elements of
only one wavelength are present, adjacent bands are about 90E out
of phase with one another. Each interconnecting element extends
between a peak and a trough and the ends of the interconnecting
member are circumferentially offset from one another and,
optionally, longitudinally offset.
[0021] The invention further provides a tubular, flexible,
expandable stent having a longitudinal axis, comprising one or more
cylindrical shaped first segments having first struts, the first
segment being defined by a member formed in an undulating pattern
of interconnected paired first struts and in which adjacent pairs
of first struts in a given first segment are interconnected at
opposite ends and one or more cylindrical shaped second segments
defined by a member formed in an undulating pattern of
interconnected paired second struts and in which adjacent pairs of
second struts in a given second segment are interconnected at
opposite ends. The first struts are shorter than the second struts.
The first segments are formed of a number of first struts and the
second segments are formed of a number of second struts with the
number of first struts in a first segment exceeding the number of
second struts in a second segment. The first and second segments,
present and desirably alternating along the stent body, are aligned
on a common longitudinal axis to define a generally tubular stent
body. Adjacent first and second segments are connected by a
plurality of interconnecting elements, each interconnecting element
extending from an end of paired first struts on a first segment to
an end of paired second struts on an adjacent second segment. The
ends of interconnecting elements are circumferentially offset
relative to each other, and optionally, longitudinally offset.
Desirably, upon expansion of the stent, the paired struts of the
adjacent segments are displaced relative to each other about the
periphery of the stent body to accommodate longitudinal flexing of
the stent within the segments and without interference between
adjacent segments.
BRIEF DESCRIPTION OF THE FIGURES
[0022] FIG. 1a shows a band-like element used in the inventive
stents.
[0023] FIG. 1b shows a schematic of a peak region which contains a
double peak and a trough region containing a double trough.
[0024] FIG. 2 shows a flat view of a stent configuration according
to the invention.
[0025] FIG. 3 shows the pattern of FIG. 2 in a tubular stent.
[0026] FIG. 4a shows a flat view of a stent configuration according
to the invention.
[0027] FIG. 4b shows a flat view of a stent configuration according
to the invention.
[0028] FIG. 5a shows a flat view of a stent configuration according
to the invention.
[0029] FIG. 5b shows a flat view of a stent configuration according
to the invention.
[0030] FIG. 6 shows a flat view of a stent configuration according
to the invention.
[0031] FIG. 7 shows a flat view of a stent configuration according
to the invention.
[0032] FIG. 8 shows a flat view of a stent configuration according
to the invention.
[0033] FIG. 9 shows a flat view of a stent configuration according
to the invention.
[0034] FIG. 10 shows a flat view of a stent configuration according
to the invention.
[0035] FIG. 11 shows a flat view of a stent configuration according
to the invention.
[0036] FIG. 12 shows a flat view of a stent configuration according
to the invention.
[0037] FIG. 13 shows the pattern of FIG. 12 in a tubular stent.
[0038] FIG. 14 shows an expanded stent of the configuration shown
in FIG. 12.
[0039] FIG. 15 shows a flat view of an alternate stent
configuration according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0040] While this invention may be embodied in many different
forms, there are described in detail herein specific preferred
embodiments of the invention. This description is an
exemplification of the principles of the invention and is not
intended to limit the invention to the particular embodiments
illustrated.
[0041] For the sake of consistency, the terms `peak` and `trough`
shall be defined with respect to the proximal and distal ends of
the stent. Each of the stents has a proximal end 91 and a distal
end 93 and a longitudinal axis 95, as seen in FIG. 1a. Peaks 36 are
generally concave relative to the proximal end of the stent and
generally convex relative to the distal end of the stent. Troughs
40, on the other hand, are generally convex relative to the
proximal end of the stent and generally concave relative to the
distal end of the stent. Notwithstanding this definition, the term
peak is also intended to extend to regions 48 that are generally
peak-like which may, nevertheless, contain trough-like regions
within the peak-like region as seen in FIG. 1b. Similarly the term
trough is also intended to extend to regions 52 that are generally
trough-like which may, nevertheless, contain peak-like regions
within the trough-like region as seen in FIG. 1b.
[0042] Corresponding to each peak 36 is an inner diameter peak 38
where the inner diameter of the band-like element reaches its peak.
The set of points on a given band-like element which are distal to
inner diameter peak 38 is denoted peak region 48. Similarly,
corresponding to each trough 40 is an inner diameter trough 42
where the inner diameter of the band-like element reaches its
trough. The set of points on a given band-like element which are
proximal to inner diameter trough 42 is denoted trough region 52.
For the sake of clarity, unless otherwise indicated, analogous
portions of stents will be similarly labeled, using three digit
reference numerals to distinguish among the various embodiments
shown.
[0043] Also included within this definition of peak regions and
trough regions are peak regions which are comprised of multiple
peaks as well as trough regions which are comprised of multiple
troughs such as those shown schematically in FIG. 1b. Peak 36 is
seen to consist of two sub-peaks 36a,b and trough 40 is similarly
seen to consist of two sub-troughs 40a,b. In the case of peaks
containing sub-peak and troughs containing sub-troughs, the peak
region 48 includes all of the points along the band-like element
between the sub-peaks that make up the peak and similarly, the
trough region 52 includes all of the points along the band-like
element between the sub-troughs that make up the trough.
[0044] The inventive stents may incorporate one or more bands of a
chosen wavelength. In some embodiments, the inventive stents
include one or more small amplitude, short wavelength bands to
provide for flexibility and one or more large amplitude, long
wavelength bands to give side branch access or to provide for
sections of alternative strengths such as soft and/or stiff
sections.
[0045] Turning to the Figures, FIG. 2 shows a flat view of a stent
configuration and FIG. 3 shows the stent of FIG. 2 in tubular form.
That is, the stent is shown for clarity in FIG. 2 in the flat and
may be made from a flat pattern 110 (FIG. 2) which is formed into a
tubular shape by rolling the pattern so as to bring edges 112 and
114 together (FIG. 2). The edges may then joined as by welding or
the like to provide a cylindrical configuration such as that shown
generally at 115 in FIG. 3.
[0046] A more preferred method of manufacture begins with a thin
walled tube which is then laser cut to provide the desired
configuration. It may also be chemically etched or EDM'd
(electrical discharge machined) to form an appropriate
configuration.
[0047] The configuration can be seen in these Figures to be made up
of one or more spaced first band-like elements 120. First band-like
elements have a generally serpentine configuration to provide
continuous waves to the first band-like elements. The waves are
characterized by a plurality of peaks 124 and troughs 128 taking a
generally longitudinal direction along the cylinder such that the
waves in first band-like elements 120 open as the stent is expanded
from an unexpanded state having a first diameter to an expanded
state having a second diameter.
[0048] The stent further comprises a plurality of spaced second
band-like elements 132 having a generally serpentine configuration
to provide continuous waves to the second band-like elements. The
waves are characterized by a plurality of peaks 136 and troughs 140
taking a generally longitudinal direction along the cylinder such
that the waves in the second band-like elements open as the stent
is expanded from an unexpanded state having a first diameter to an
expanded state having a second diameter. First and second band-like
elements are characterized by respective wavelengths and amplitudes
with the wavelength and amplitude of the second band-like elements
exceeding the wavelength and amplitude of the first band-like
elements.
[0049] Adjacent first band-like elements 120 and second band-like
elements 132 are interconnected via a plurality of interconnecting
elements 144. The ends of interconnecting element are
circumferentially offset from each other.
[0050] In an embodiment, as shown in FIGS. 2 and 3, first band-like
elements 120 and second band-like elements 132 alternate over the
length of the stent. Optionally, as shown in FIGS. 2 and 3, each
end 152 of the stent may terminate in a first band-like element.
The invention also, however, contemplates each end terminating in a
second band-like element, or further, one end terminating in a
first band-like element and the other end terminating in a second
band-like element.
[0051] While a minimum of one connecting element is required to
join adjacent band-like elements, two or more interconnecting
elements are preferred. In one embodiment, as shown in FIGS. 2 and
3, adjacent first and second band-like elements 120 and 132 are
connected with three interconnecting elements 144. Further, in one
embodiment, adjacent interconnecting elements 144 extending from
peaks 136 on a first band-like element 120 are spaced five peaks
apart on the first band-like element while adjacent interconnecting
elements 144 extending from troughs 140 on a second band-like
element 132 are spaced three troughs apart on the second band-like
element.
[0052] It is a further feature of the present invention that peaks
124 on first band-like elements 120 are circumferentially displaced
on the periphery of the stent from troughs 140 on adjacent second
band-like elements 132. It is desirable that peaks and troughs be
displaced in the expanded state of the stent to minimize the
possibility of pinching or overlap between adjacent band-like
elements.
[0053] Although the stent of FIG. 2 is comprised of two different
wavelength band-like elements, the invention contemplates stents
with a plurality of different wavelength band-like elements. As
such, other stents may have three, four or more different
wavelength band-like elements.
[0054] In another embodiment, the inventive stent is comprised of
band-like elements of a single wavelength, interconnected by
interconnecting elements. Turning to FIGS. 4a and 4b, band-like
elements 220a,b are interconnected by interconnecting elements
244a,b. Adjacent band-like elements 220a,b are 180E out of phase
with one another. In the compressed state, the band-like elements
consist of a plurality of peaks 236a,b and troughs 240a,b. Peak
region 248a,b and trough region 252a,b have been shaded in one
instance for illustrative purposes.
[0055] In the embodiment shown in FIG. 4a, each interconnecting
element 244a extends between a peak region 248a and a trough region
252a. Rectilinear interconnecting elements 244a consist of a first
shank 280a, a second shank 284a and a link 288a disposed in-between
the first and second shanks 280a and 284a. First shank 280a extends
in a longitudinal direction from peak region 248a and is
substantially perpendicular to link 288a. Second shank 284a extends
in a longitudinal direction from trough region 252a and is
perpendicular to link 288a.
[0056] In the embodiment shown in FIG. 4b, the stent differs from
the embodiment of FIG. 4a in that interconnecting element 244b
extending between a peak region 248b and a trough region 252b is
curvilinear rather than rectilinear.
[0057] In both FIGS. 4a and 4b, the interconnecting elements are
seen to emanate from the middle of the peak and trough regions.
[0058] In another embodiment, as shown in FIG. 5a, the inventive
stent is comprised of band-like elements 320a of a single
wavelength, interconnected by interconnecting elements 344a.
Adjacent band-like elements 320a are 180E out of phase with one
another. The band-like elements consist of a plurality of peaks
336a and troughs 340a. Interconnecting elements 344a extend between
a peak region 348a and a trough region 352a. The peak regions 348a
and trough regions 352a from which interconnecting elements 344a
emanate on a given band-like element 320a are seen to extend
longitudinally beyond adjacent peak regions 348a' and trough
regions 352a' from which no interconnecting elements extend. The
extension is such that at least a portion of peak regions 348a
overlap longitudinally along the stent with at least a portion of
trough region 352a on an adjacent band-like element 320a'. Of
course, the overlap is limited to the longitudinal direction and
not to the circumferential direction.
[0059] In another embodiment, as shown in FIG. 5b, interconnecting
elements 344b extend between peak region 348b and a second closest
trough region 352b on an adjacent band-like element.
Interconnecting elements 344b are seen to be perpendicular to the
longitudinal axis. As in the stent of FIG. 5a, peak regions 348b
from which interconnecting elements 344b extend and trough regions
352b from which interconnecting elements 344b extend may extend
beyond adjacent peak regions 348b' and trough regions 352b' from
which no interconnecting elements 344b emanates.
[0060] In another embodiment, as shown in FIG. 6, adjacent
band-like elements 420 are in phase with each other. As in previous
Figs, band-like elements 420 are of a single wavelength,
interconnected by interconnecting elements 444. The band-like
elements consist of a plurality of peaks 436 and troughs 440.
Interconnecting elements 444 extend at an oblique angle relative to
the longitudinal axis of the stent between a peak region 448 and a
trough region 452. As such, ends of interconnecting elements 444
are circumferentially offset relative to each other. The exact
angle will, of course, depend on the region from which the
interconnecting elements extend, as well as on whether
interconnecting elements interconnect nearest peaks and troughs,
next nearest peaks and troughs or peaks and troughs that are
further separated.
[0061] In FIGS. 5a, 5b and 6, the interconnecting elements are seen
to emanate from the sides of the peak and trough regions.
[0062] Although for the embodiments of FIGS. 1-6, the
interconnecting elements extend from peak regions on band-like
elements to trough regions on adjacent band-like elements, the
invention further contemplates interconnecting elements extending
from a position between a peak region and an adjacent trough region
on a band-like element to a position intermediate a trough region
and a peak region on an adjacent second band-like element as in
FIG. 7.
[0063] In the embodiment of FIG. 7, interconnecting elements are
seen to extend from a region between the peak region and the trough
region on a band-like element. The stent is formed of adjacent
band-like elements 520 which are 180E degrees out of phase with one
another. Interconnecting elements 544 extend from a region
intermediate a peak region 548 and a trough region 552 on a
band-like element to a region intermediate a peak region 548 and a
trough region 552 on an adjacent band-like element. Interconnecting
elements 544 consist of a first shank 560, a second shank 564, and
an intermediate member 568 disposed in-between first and second
shanks 560 and 564. First shank 560 and second shank 564 are
substantially perpendicular to intermediate member 568 which
extends in the longitudinal direction. Although not depicted, the
region from which interconnecting elements 544 emanate may be
midway between peaks and troughs.
[0064] The embodiment of FIG. 7 also differs from the embodiments
of FIGS. 2-6 in the orientation of the interconnecting elements.
Whereas the interconnecting elements in FIGS. 2-6 are all similarly
oriented, in the embodiment of FIG. 7, the orientation of
interconnecting elements alternates between adjacent pairs of
adjacent band-like elements. Specifically, second shanks 564' of
interconnecting elements 544' are seen to be displaced in a
clockwise circumferential direction along the stent relative to
first shanks 560', and seconds shank 564'' of interconnecting
elements 544'' are seen to be displaced in a counterclockwise
circumferential direction along the stent relative to while first
shank 560''.
[0065] This feature is also seen in the embodiment of FIG. 8 in
which adjacent in-phase band-like elements 620 are interconnected
by interconnecting elements 644. Interconnecting elements 644
extend at an oblique angle relative to the longitudinal axis of the
stent between a peak region 648 and a trough region 652. As in FIG.
7, the orientation of interconnecting elements alternates between
adjacent pairs of adjacent band-like elements. Specifically, the
distal ends of interconnecting elements 644' are seen to be
oriented in a counterclockwise circumferential direction along the
stent relative to the proximal end of the interconnecting elements
while the distal ends of interconnecting elements 644'' are seen to
be displaced in a clockwise circumferential direction along the
stent relative to the proximal ends.
[0066] Although in the embodiments of FIGS. 2-8, adjacent bands are
connected by five interconnecting elements, additional or fewer
interconnecting elements may be used. Further, while
interconnecting elements are shown spaced three peaks apart and
three troughs apart, other separations are contemplated as
well.
[0067] In the embodiment of FIG. 9, each band-like element 720 is
seen to comprise peaks 736 of more than one amplitude and troughs
740 of more than one amplitude. Large amplitude peaks 736a and
small amplitude peaks 736b alternate as do large amplitude troughs
740a and small amplitude troughs 740b. As in the previous
embodiments, the interconnecting elements are oriented at an
oblique angle relative to the longitudinal axis 795 of the stent.
More generally, the invention is directed at stents comprising
band-like elements whose amplitude varies along the band-like
element.
[0068] In another embodiment of the invention, as shown in FIG. 10,
each band-like element 820 is seen to comprise peaks 836 of more
than one amplitude and troughs 840 of more than one amplitude,
however, peaks of the same amplitude are grouped together within a
band-like element as are troughs of the same amplitude. It is
further noted that in the embodiment of FIG. 10, the location of a
group of peaks of given amplitude in a band-like element varies
circumferentially along the length of the stent. Interconnecting
elements 844 connect peaks 836 and troughs 840 in adjacent
band-like elements 820. Where several peaks of different amplitudes
are present in a band-like element, the invention further
contemplates the possibility of interconnecting elements extending
from the large peaks 836a to large troughs 840a as in FIG. 9 as
well as the possibility of interconnecting elements extending from
large peaks to small troughs or from small peaks 836b to large
troughs 840a as in FIG. 10. Further, the interconnecting elements
between any two adjacent band-like elements may be of different
lengths from one another as seen in FIG. 10 and commence at
different longitudinal positions within a band-like element and
terminate at different longitudinal positions within a band-like
element. Interconnecting element 844a is seen to be longer than
interconnecting element 844b. As in the previous embodiments, the
interconnecting elements are oriented at an oblique angle relative
to the longitudinal axis 895 of the stent. In the embodiment of
FIG. 10, interconnecting element 844a is seen to be oriented at a
smaller oblique angle relative to the longitudinal axis of the
stent than interconnecting element 844b. As is apparent from FIG.
10, the invention is also directed to stents comprised of band-like
elements whose wavelength varies along a given band-like element.
Region 898 and region 899 of band-like element are characterized by
different wavelengths.
[0069] It is also noted that in the embodiment of FIG. 10, all of
the troughs 840a, b in a given band-like element 820 are aligned
longitudinally along the stent and differ only in their
circumferential position along the stent.
[0070] It is further noted in the embodiment of FIG. 10, the stent
comprises a first group of interconnecting elements 844a and a
second group of interconnecting elements 844b. The interconnecting
elements of the first group are all parallel to one another and
disposed at a different oblique angle relative to the longitudinal
axis than the members of the second group which are all parallel to
one another. As such, the invention contemplates stents having
several different groups of obliquely disposed interconnecting
elements where the oblique angle differs from group to group.
[0071] In another embodiment of the invention, as shown in FIG. 11,
each band-like element 920 is seen to comprise peaks 936a,b of
different amplitudes and troughs 940 of different amplitudes,
however, peaks of the same amplitude are grouped together within a
band-like element as are troughs of the same amplitude. It is
further noted that in the embodiment of FIG. 11 the location of
groups of peaks of given amplitude in a band-like element varies
circumferentially along the length of the stent. Interconnecting
elements 944 connect large amplitude peaks 936a and small amplitude
troughs 940b in adjacent band-like elements 920. Similarly,
interconnecting elements 944 also connect small amplitude peaks
936b and large amplitude troughs 940a.
[0072] The invention also contemplates stents similar to that shown
in FIG. 11 in which interconnecting elements extend from large
peaks 936a to large troughs 940a, as in FIG. 9. Similarly,
interconnecting elements may extend from small peaks 936b to small
troughs 940b.
[0073] Further, the interconnecting elements between any two
adjacent band-like elements may be of different lengths from one
another and disposed at different oblique angles.
[0074] As is apparent from FIG. 11, the invention is also directed
to stents comprised of band-like elements whose wavelength varies
along a given band-like element. Region 998 and region 999 of
band-like element 920 are characterized by different
wavelengths.
[0075] It is also noted that in the embodiment of FIG. 11 the large
amplitude portions 999 of band-like element 920 are symmetrically
disposed about the center 1001 of the band-like element as are the
small amplitude portions 998. The center 1001 of the band-like
element is defined as a ring that runs along a path that is midway
between the large peaks 936a and large troughs 940a of the
band-like element. This feature may also be seen in the embodiment
of FIG. 9.
[0076] The invention is also directed to a tubular, flexible,
expandable stent having a longitudinal axis, comprising one or more
cylindrical shaped first segments. Cylindrical shaped first
segments 20 as seen in FIG. 1, have first struts 23 having first 25
and second 27 ends. First segments 20 are defined by a member
formed in an undulating pattern of interconnected paired first
struts 23, in which adjacent pairs of first struts 29' and 29'' in
a given first segment 20 are interconnected at opposite ends 31'
and 31'', respectively. Adjacent segments are interconnected.
[0077] The stent may be seen more clearly in FIGS. 2-8. As shown,
the stent of FIG. 3, in addition to comprising first segments 120
which are defined by an undulating pattern of interconnected paired
first struts 123 in which adjacent pairs of first struts 129' and
129'' in a given first segment 120 are interconnected at opposite
ends 131' and 131'', respectively, the stent further comprises one
or more cylindrical shaped second segments 132, each second segment
being defined by a member formed in an undulating pattern of
interconnected paired second struts 135 and in which adjacent pairs
of second struts 137' and 137'' in a given second segment 132 are
interconnected at opposite ends 139' and 139'', respectively. First
struts 123 are shorter than second struts 135. First segments 120
are formed of a number of first struts 123 and second segments 132
formed of a number of second struts 135, the number of first struts
in a first segment exceeding the number of second struts in a
second segment. First and second segments 120 and 132 are aligned
on a common longitudinal axis 195 to define a generally tubular
stent body, shown generally at 115. First and second segments 120
and 132 alternate along the stent body. Adjacent first and second
segments 120 and 132 are connected by a plurality of
interconnecting elements 144. Each interconnecting element 144
extends from an end 131'' of paired first struts on a first segment
120 to an end 139'' of paired second struts on an adjacent second
segment 132. The ends of interconnecting elements 144 are
circumferentially offset relative to each other.
[0078] Desirably, upon expansion of stent 115, paired struts 129''
and 137'' of adjacent segments 120 and 132 are displaced relative
to each other about the periphery of the stent body to accommodate
longitudinal flexing of the stent within the segments and without
interference between adjacent segments.
[0079] In the embodiments as shown in FIGS. 4a,b, cylindrical
shaped segments 220a,b are formed of interconnected struts 223a,b
having first 225 and second 227 ends. Adjacent pairs of struts
229a,b' and 229a,b'' in a given segment 220a,b are interconnected
at opposite ends 231a,b' and 231a,b'', respectively. Adjacent
segments are connected by a plurality of interconnecting elements
244a,b. Each interconnecting element 244a,b extends from an end of
paired struts 231a,b'' on a segment to an end of paired struts
231a,b' on an adjacent segment. First end 245a,b and second end
247a,b of interconnecting elements 244a,b are seen to be
circumferentially displaced along the stent.
[0080] Similar structure, denoted by similar reference numerals may
be found in the stents of FIGS. 5a,b, and 6-8.
[0081] In particular, in the embodiment as shown in FIG. 8,
cylindrical shaped segments 620 are formed of interconnected struts
623, having first 625 and second 627 ends. Segments 620 are defined
by a member formed in an undulating pattern of interconnected
paired struts 623 in which adjacent pairs of struts 629' and 629''
in a given segment 620 are interconnected at opposite ends 631' and
631'', respectively. Segments 620 are aligned on a common
longitudinal axis 695 to define a generally tubular stent body.
Adjacent segments are connected by a plurality of interconnecting
elements 644 (and 644') having first 645 (645') and second 647
(647') ends, each interconnecting element 644 (644') extending from
an end of paired struts 631'' on a segment to an end of paired
struts 631' on an adjacent segment. First end 645 (645') and second
end 647 (647'') are seen to be circumferentially displaced along
the stent.
[0082] Additional embodiment of the stents are shown in FIGS.
12-15. FIG. 12 and FIG. 13 show a fragmentary flat view of an
unexpanded stent configuration and the actual tubular stent
(unexpanded), respectively. That is, the stent is shown for clarity
in FIG. 12 in the flat and may be made from a flat pattern 1110
(FIG. 12) which is formed into a tubular shape by rolling the
pattern so as to bring edges 1112 and 1114 together (FIG. 12). The
edges may then joined as by welding or the like to provide a
configuration such as that shown in FIG. 13.
[0083] The configuration can be seen in these Figures to be made up
of a plurality of adjacent segments generally indicated at 1116,
each of which is formed in an undulating flexible pattern of
substantially parallel struts 1118. Pairs of struts are
interconnected at alternating end portions 1119a and 1119b. As is
seen in FIG. 12, the interconnecting end portions 1119b of one
segment are positioned opposite interconnecting end portions 1119a
of adjacent segments. The end portions as shown are generally
elliptical but may be rounded or square or pointed or the like. Any
configuration of end portions is acceptable so long as it provides
an undulating pattern, as shown. When the flat form 1110 is formed
into an unexpanded tube as shown in FIG. 13, the segments are
cylindrical but the end portions 1119 of adjacent segments remain
in an opposed position relative to each other.
[0084] A more preferred method of manufacture begins with a thin
walled tube which is then laser cut to provide the desired
configuration. It may also be chemically etched or EDM'd
(electrical discharge machined) to form an appropriate
configuration.
[0085] Interconnecting elements 1120 extend from one end portion
1119 of one segment 1116 to another end portion 1119 of another
adjacent segment 1116 but not to an oppositely positioned end
portion 1119 of an adjacent segment 1116. There are at least three
struts included between the points on each side of a segment 1116
at which an interconnecting element 1120 contacts an end portion
1119. This results in the interconnecting elements 1120 extending
in an angular direction between segments around the periphery of
the tubular stent. Interconnecting elements 1120 are preferably of
the same length but may vary from one segment to the other. Also,
the diagonal direction may reverse from one segment to another
extending upwardly in one case and downwardly in another, although
all connecting elements between any pair of segments are
substantially parallel. FIG. 12, for example shows them extending
downwardly, right to left. Upwardly would extend up left to right
in this configuration.
[0086] As a result of this angular extension of the interconnecting
elements 1120 between adjacent segments and loops, upon expansion
of the stent as seen in FIG. 14, the closest adjacent end portions
1119 between segments 1116 are displaced from each other and are no
longer opposite each other so as to minimize the possibility of
binding or overlapping between segments, i.e., pinching.
[0087] The number of interconnecting elements 1120 may vary
depending on circumstances in any particular instance. Three per
segment are satisfactory for the configuration shown and at least
three will be used typically.
[0088] The alternate design shown in FIG. 15 includes longer struts
1118a in the two end segments 1116a than in the intermediate
segments 1116. This allows the end segments (1116a) to have less
compression resistance than the intermediate segments (1116),
providing a more gradual transition from the native vessel to the
support structure of the stent. Otherwise, the configuration is the
same as that shown in FIG. 12.
[0089] As indicated in the Figures, the invention contemplates a
variation of interconnecting element shapes ranging from
rectilinear to curvilinear. The invention further contemplates
embodiments in which all interconnecting elements are similarly
oriented as well as embodiments in which adjacent sets of
interconnecting elements extending between adjacent pairs of
segments are oppositely oriented (e.g., FIGS. 7 and 8). The
invention also contemplates the use of interconnecting elements
which extend from a range of positions along the segments, ranging
from various positions in the area in which paired struts are
interconnected to other positions along the struts.
[0090] The invention also contemplates the possibility of
interconnecting elements extending at an oblique angle relative to
the longitudinal axis of the stent and connecting adjacent peaks
and troughs on adjacent segments as well as peaks and troughs on
adjacent segments which are separated by one or more peaks and/or
troughs.
[0091] The invention also contemplates reversing the orientation of
interconnecting elements as shown in FIGS. 7 and 8.
[0092] Finally, there are preferably at least three interconnecting
elements joining adjacent first and second segments although fewer
or additional interconnecting elements are also contemplated.
[0093] It is understood that the peaks and troughs of the present
invention need not be rounded, as shown in the Figures. The peaks
and troughs may be bulbous, triangular, square, pointed, or
otherwise formed of interconnected straight sections.
[0094] As already indicated, this invention is applicable to
self-expanding configurations, mechanically expandable
configurations and to a wide variety of materials, including both
metal and 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. It may be
thin-walled. It may be of shape memory alloy such as Nitinol or the
like, etc. The interconnecting elements may be formed integrally
with the band-like elements (or segments) or may be bonded thereto
via such methods as adhesive bonding, welding or any other known
method of bonding.
[0095] The above Examples and disclosure are intended to be
illustrative and not exhaustive. These examples and this
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.
* * * * *