U.S. patent application number 14/663556 was filed with the patent office on 2015-07-09 for medical devices including metallic films and methods for making same.
The applicant listed for this patent is Boston Scientific Scimed Inc.. Invention is credited to Beren W. Correa, Delilah Yin Hui, Alexander Leynov, Masoud MOLAEI, Robert Z. Obara, John Peckham, Stephen Christopher Porter.
Application Number | 20150190255 14/663556 |
Document ID | / |
Family ID | 34914706 |
Filed Date | 2015-07-09 |
United States Patent
Application |
20150190255 |
Kind Code |
A1 |
MOLAEI; Masoud ; et
al. |
July 9, 2015 |
MEDICAL DEVICES INCLUDING METALLIC FILMS AND METHODS FOR MAKING
SAME
Abstract
An endoprosthesis for deployment within a body passage includes
a framework and a metallic film, which can circumferentially
surround the framework or be surrounded by the framework. The
framework and metallic film can be attached without using a third
material, e.g., without sewing. The framework can define a
circumferential recess along at least a portion of its length and
circumference. The recess accommodates at least a portion of the
metallic film therein.
Inventors: |
MOLAEI; Masoud; (Fremont,
CA) ; Correa; Beren W.; (Fremont, CA) ;
Peckham; John; (Sunnyvale, CA) ; Leynov;
Alexander; (Walnut Creek, CA) ; Porter; Stephen
Christopher; (Oakland, CA) ; Obara; Robert Z.;
(Fremont, CA) ; Hui; Delilah Yin; (American
Canyon, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boston Scientific Scimed Inc. |
Maple Grove |
MN |
US |
|
|
Family ID: |
34914706 |
Appl. No.: |
14/663556 |
Filed: |
March 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11025866 |
Dec 29, 2004 |
8998973 |
|
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14663556 |
|
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60549287 |
Mar 2, 2004 |
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Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
A61F 2002/9511 20130101;
A61F 2/86 20130101; A61F 2/90 20130101; A61F 2230/0013 20130101;
A61F 2250/0039 20130101; A61F 2002/075 20130101; A61F 2002/9665
20130101; A61F 2210/0076 20130101; A61F 2/07 20130101 |
International
Class: |
A61F 2/86 20060101
A61F002/86 |
Claims
1-20. (canceled)
21. An endoprosthesis for deployment within a body passage,
comprising: a framework having first and second ends; and a tubular
member comprising a metallic film having a thickness of about 50
.mu.m or less and being generally coextensive with at least a
portion of the framework, the framework and tubular member retained
with respect to one another by a filament at a plurality of
retention sites, each retention site located at substantially the
same distance from the first end of the framework.
22. The endoprosthesis of claim 1, wherein the plurality of
retention sites are located closer to the first end of the
framework than to the second end of the framework.
23. The endoprosthesis of claim 1, wherein the plurality of
retention sites are located closer to the second end of the
framework than to the first end of the framework.
24. The endoprosthesis of claim 1, wherein the tubular member
comprises a plurality of fenestrations and the framework comprises
a plurality of framework members such that the filament passes
through the fenestrations and at least partially around the
framework members.
25. The endoprosthesis of claim 4, wherein the filament at least
partially encircles the framework.
26. The endoprosthesis of claim 5, wherein the tubular member is
compressed between the filament and the framework.
27. The endoprosthesis of claim 1, wherein the metallic film is a
deposited metallic film comprising nickel and titanium.
28. An endoprosthesis for deployment within a body passage,
comprising: a framework having first and second ends; and a tubular
member comprising a metallic film having a thickness of about 50
.mu.m or less and being generally coextensive with at least a
portion of the framework, the framework and tubular member retained
with respect to one another by one filament at one retention
site.
29. The endoprosthesis of claim 8, wherein the retention site is
located closer to the first end of the framework than to the second
end of the framework.
30. The endoprosthesis of claim 8, wherein the retention site is
located closer to the second end of the framework than to the first
end of the framework.
31. The endoprosthesis of claim 8, wherein the tubular member
includes adjacent fenestrations such that the filament passes
through the adjacent fenestrations and at least partially around a
framework member.
32. The endoprosthesis of claim 8, wherein the filament allows
radial and/or longitudinal movement between the tubular member and
framework.
33. The endoprosthesis of claim 8, wherein the filament does not
allow radial and/or longitudinal movement between the tubular
member bad framework.
34. The endoprosthesis of claim 8, wherein the metallic film is a
deposited metallic film comprising nickel and titanium.
35. An endoprosthesis for deployment within a body passage,
comprising: a framework having first and second ends; and a tubular
member comprising a metallic film having a thickness of about 50
.mu.m or less and being generally coextensive with at least a
portion of the framework, the framework and tubular member retained
with respect to one another by a plurality of filaments at a
plurality of retention sites, each retention site located at
substantially the same distance from the first end of the
framework.
36. The endoprosthesis of claim 15, wherein the plurality of
retention sites are located closer to the first end of the
framework than to the second end of the framework.
37. The endoprosthesis of claim 15, wherein the plurality of
retention sites are located closer to the second end of the
framework than to the first end of the framework.
38. The endoprosthesis of claim 15, wherein the tubular member
includes adjacent fenestrations such that a single filament passes
through adjacent fenestrations and at least partially around a
framework member at a single retention site.
39. The endoprosthesis of claim 15, wherein the metallic film is a
deposited metallic film comprising nickel and titanium.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent application No. 60/549,287, filed Mar. 2, 2004, which
application is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention relates to medical devices, such as
endoprostheses, and methods of making the devices.
BACKGROUND
[0003] The body includes various passageways such as arteries,
other blood vessels, and other body lumens. These passageways
sometimes become occluded or weakened. For example, the passageways
can be occluded by a tumor, restricted by plaque, or weakened by an
aneurysm. When this occurs, the passageway can be reopened or
reinforced, or even replaced, with a medical endoprosthesis. An
endoprosthesis is typically a tubular member that is placed in a
lumen in the body. Endoprostheses can be delivered inside the body
by a catheter that supports the endoprosthesis in a compacted or
reduced-size form as the endoprosthesis is transported to a desired
site. Upon reaching the site, the endoprosthesis is expanded, for
example, so that it can contact the walls of the lumen.
[0004] The expansion mechanism may include forcing the
endoprosthesis to expand radially. For example, the expansion
mechanism can include the catheter carrying a balloon, which
carries a balloon-expandable endoprosthesis. The balloon can be
inflated to deform and to fix the expanded endoprosthesis at a
predetermined position in contact with the lumen wall. The balloon
can then be deflated, and the catheter withdrawn.
[0005] In another delivery technique, the endoprosthesis is formed
of an elastic material that can be reversibly compacted and
expanded, e.g., elastically or through a material phase transition.
During introduction into the body, the endoprosthesis is restrained
in a radially compacted condition. Upon reaching the desired
implantation site, the restraint is removed, for example, by
retracting a restraining device such as an outer sheath, enabling
the endoprosthesis to self-expand by its own internal elastic
restoring force.
SUMMARY OF THE INVENTION
[0006] The invention relates to medical devices, such as
endoprostheses, and methods of making the devices. Exemplary
endoprostheses include stents, covered stents, and
stent-grafts.
[0007] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework having first and second ends
and a tubular member including a metallic film having a thickness
of about 50 .mu.m or less and being generally coextensive with at
least a portion of the framework. The framework and tubular member
can be retained with respect to one another, when deployed in the
body passage, at substantially only one distance from the first end
of the framework.
[0008] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0009] When deployed in the body passage, the framework and the
tubular member may be secured to one another at one or more
different locations, e.g., at a plurality of locations. Each
location is spaced a respective distance di from the first end of
the framework. A ratio of (a) a maximum difference between
distances di to (b) a length of the framework may be about 0.15 or
less. Each of the one or more different locations may be located
closer to the first end of the framework than to the second end. In
embodiments, the framework and tubular member are secured to one
another at a single location.
[0010] In some embodiments, a delivery device includes the
endoprosthesis. The delivery device has a distal end and a proximal
portion. The endoprosthesis is in the compressed state and the
first end of the framework is located closer to the distal end of
the delivery device than to the proximal portion. Prior to
deployment in the body passage, the framework and the tubular
member may be secured to one another at one or more proximal
locations and at one or more other, e.g., distal and/or central,
locations. Subsequent to deployment, the framework and tubular
member are secured at substantially only one distance from the
first end of the framework. For example, one or more filaments
securing the other locations may rupture or become undone during
deployment.
[0011] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework including at least one radial
projection having a radially enlarged end and a deposited film
generally coextensive with at least a portion of the framework. The
film has at least one fenestration and the at least one projection
of the framework extends through the fenestration and retains a
portion of the deposited film adjacent the fenestration between the
radially enlarged end and the framework. The film may be a
deposited metallic film including, e.g., deposited nickel and
titanium.
[0012] The deposited film and framework may have at least some
freedom of movement in at least one of a radial, circumferential,
or longitudinal dimension.
[0013] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework having at least one framework
member and a deposited film generally coextensive with at least a
portion of the framework. The film includes a first projection
having a fixed end and a plurality of free edges. The first
projection extends from its fixed end across the framework member
to retain the framework and film with respect to one another.
[0014] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0015] In embodiments, the film includes a second projection having
a fixed end and a plurality of free edges. The fixed ends of the
first and second projections may be located on opposite sides of
the framework member so that the first and second projections
extend over the framework member in opposite orientations. A
spacing between nearest free edges of the first and second
projections may be about equal to or less than a width of the
projections.
[0016] The endprosthesis and the framework member may have a
respective longitudinal axis, with the longitudinal axes may be
aligned with one another.
[0017] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework defining a perimeter and a
deposited film generally coextensive with at least a portion of the
framework. The film has a plurality of projections, each projection
having a fixed end and a free end. Each projection extends from its
fixed end, which may be located on a first side of the perimeter to
a free end, which may be located on a second, opposite side of the
perimeter to retain the framework and the film with respect to one
another.
[0018] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0019] The projections may extend longitudinally outward from an
end of the film.
[0020] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework including at least one radial
projection and a deposited film generally coextensive with at least
a portion of the framework. The film has at least one fenestration
through which the at least one projection of the framework extends.
A filament extends circumferentially around at least a portion of
the film and through the radial projection to retain the framework
and tubular member with respect to one another.
[0021] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0022] In embodiments, an endoprosthesis for deployment within a
body passage includes a framework having first and second end
portions and a central portion. The central portion and at least
the first end portion have a diameter that differs by an amount
.DELTA.d to form a recess. A tubular member is circumferentially
coextensive with at least the central portion of the framework and
is at least partially accommodated within the recess.
[0023] The central portion may have a smaller diameter than the
first end portion so that the recess is formed within an exterior
of the framework.
[0024] The framework and tubular member may have at least
circumferential freedom of movement with respect to one
another.
[0025] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0026] In some embodiments, an endoprosthesis for deployment within
a body passage includes a framework and a deposited metal film
generally coextensive with the framework, the deposited metal film
comprising at least one elongate band and at least one
fenestration, the elongate band extending circumferentially with
respect to the framework and through the at least one
fenestration.
[0027] The film may be a deposited metallic film including, e.g.,
deposited nickel and titanium. The deposited film may have a
thickness of about 50 .mu.m or less, 50 .mu.m or less, e.g., about
35 .mu.m or less. The deposited film may have a thickness of 4
.mu.m or greater. The film may exhibit super-elastic
properties.
[0028] In one aspect, the invention features an endoprosthesis
including a metallic film, e.g., a vapor deposited film, including
nickel, titanium, and chromium. A ratio of a weight of chromium of
the metallic film to a combined weight of nickel, titanium, and
chromium of the metallic film is at least 0.001 and can be less
than 0.0075.
[0029] Other aspects, features, and advantages of the invention
will be apparent from the description of the preferred embodiments
thereof and from the claims.
BRIEF DESCRIPTION OF THE FIGURES
[0030] FIG. 1 is a side view of an endoprosthesis in the radially
expanded state as deployed within a body passage adjacent an
aneurysm.
[0031] FIG. 2a is a side view of a distal portion of a deployment
device prior to radial expansion of the endoprosthesis.
[0032] FIG. 2b is a side view of the distal portion of the
deployment device subsequent to radial expansion of the
endoprosthesis adjacent the aneurysm.
[0033] FIG. 3a is a side view of the endoprosthesis of FIG. 1
removed from the body passage and viewed from the opposite
side.
[0034] FIG. 3b is a side view of an embodiment of an endoprosthesis
including a stent body and a tubular member.
[0035] FIG. 3c is a side view of an embodiment of an endoprosthesis
including a stent body and a tubular member.
[0036] FIG. 3d is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0037] FIG. 3e is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0038] FIG. 4a is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0039] FIG. 4b is a perspective view of the stent body of the
endoprosthesis of FIG. 4a.
[0040] FIG. 5a is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0041] FIGS. 5b and 5c show detail of a retention site of the
endoprosthesis of FIG. 5a. FIG. 5b being a view from a first side
of the tubular member and FIG. 5c being a view from a second,
opposing side of the tubular member.
[0042] FIG. 6a is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0043] FIG. 6b is a detail view of an end portion of the
endoprosthesis of FIG. 6a.
[0044] FIGS. 6c and 6d are detail views of alternative retention
sites between a tubular member and a stent body.
[0045] FIG. 7a is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0046] FIG. 7b is a top view of the tubular member of the
endoprosthesis of FIG. 7a. The tubular member is shown in two
dimensions.
[0047] FIG. 8a is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0048] FIG. 8b is a perspective view of the stent body of the
endoprosthesis of FIG. 8a.
[0049] FIG. 8e is a perspective view of an alternative tubular
member for use with the stent body of FIG. 8b. The tubular member
is shown in two dimensions.
[0050] FIG. 9 is a perspective view of an embodiment of an
endoprosthesis including a stent body and a tubular member.
[0051] FIG. 10a is an embodiment of an endoprosthesis including a
stent body and a tubular member.
[0052] FIG. 10b is a side view of the stent body of FIG. 10b.
[0053] FIG. 10c is a side view of the tubular member of FIG.
10a.
DETAILED DESCRIPTION
[0054] Referring to FIG. 1, an endoprosthesis 100 is deployed
within a body passage, e.g., within a vessel weakened by an
aneurysm, e.g., an aneurysm 25 of a vessel 26 of a human brain.
Endoprosthesis 100 includes a framework, e.g., a stent body 52,
covered by a tubular member or cover 54, made of thin metallic
film. The stent body provides a relatively rigid framework that
secures the endoprosthesis at the treatment site. The framework
defines relatively large openings or fenestrations that contribute
to the mechanical properties of the stent. The cover 54 is
relatively thin and flexible and includes smaller fenestrations
that contribute to the mechanical properties of the cover and
occlude the fenestrations of the stent.
[0055] In some embodiments, endoprosthesis 100 modifies an amount
or velocity of blood passing between vessel 26 and aneurysm 25. For
example, prosthesis 100 can be deployed to reduce or block blood
flow between vessel 26 and aneurysm 25, e.g., to occlude the
aneurysm 25. If so deployed, prosthesis 100 may sufficiently reduce
blood flow to allow clotting or other healing processes to take
place within aneurysm 25 and/or opening 29 thereof. Tubular member
54 can provide a greater attenuation of the blood flow into the
aneurysm 25 than stent body 52 alone. Endoprosthesis 100, however,
can allow some flow to pass between vessel 26 and aneurysm 25 even
while providing some reduction in the rate and/or volume of flow.
Prosthesis 100 can also (or alternatively) allow blood to pass
between vessel 26 containing the prosthesis and adjacent vessels,
e.g., feeder vessel 27, while still providing reduced flow with
respect to the aneurysm.
[0056] Referring to FIG. 2a, endoprosthesis 100 is deployed to
aneurysm 25 using a deployment device 30, which includes a
retractable outer sheath 31 and an inner catheter 32. FIG. 2a shows
only a distal portion of the delivery device. An operator
manipulates the device 30 using a proximal portion (not shown).
Device 30 is introduced over a guide wire 37 extending along the
interior 28 of vessel 26. During introduction, the endoprosthesis
100 is radially compacted between outer sheath 31 and inner
catheter 32 adjacent a distal end 40 of the outer sheath.
Endoprosthesis 100 is longitudinally restrained by a proximal stop
33 and a distal tip 34 of inner catheter 32. Device 30 includes
distal and proximal markers 38,39, which can be radiographically
monitored to determine when endoprosthesis 100 has reached aneurysm
25. Prosthesis 100 includes markers 75, to provide radiopacity,
which can also or alternatively be used to visualize the position
of endoprosthesis 100.
[0057] With reference to FIG. 2b, the outer sheath 31 is retracted
upon reaching the desired deployment site, e.g., aneurysm 25. In
some embodiments, endoprosthesis 100 self-expands by its own
internal elastic restoring force when the radially restraining
outer sheath is retracted. Alternatively, or in combination with
self-expansion, deployment of prosthesis 100 may include use of a
balloon or other device to radially expand prosthesis 100 within
vessel 26. The inner catheter 32 and guide wire 37 are withdrawn
from vessel 26. Suitable delivery systems include the Neuroform,
Neuroform2, and Wingspan Stent System available from Boston
Scientific Target Therapeutics, Fremont, Calif. In embodiments, the
outer sheath and/or inner catheter includes a reinforcing member to
respectively resist elongation or compression as the outer sheath
is withdrawn. Such reinforcing members include polymer shafts,
braids, and coil structures.
[0058] Upon expansion, endoprosthesis 100 assumes a shape and
radial extent generally coextensive with an inner surface of the
vessel 26, e.g., a tubular shape centered about a longitudinal axis
at of the prosthesis (FIG. 1). Depending upon the application,
prosthesis 100 can have a diameter d of between, for example, 1 mm
to 46 mm. In certain embodiments, a prosthesis for deployment
within a vessel at an aneurysm can have an expanded diameter d of
from about 2 mm to about 6 mm, e.g., about 2.5 mm to about 4.5 mm.
Depending upon the application, prosthesis 100 can have a length
along axis a.sub.1 of at least 5 mm, at least 10 mm, e.g., at least
about 30 mm. An exemplary embodiment has an expanded diameter of
about 3.5 mm and a length of about 15 mm. In embodiments, the stent
body has a closed cell framework, an open cell framework, a helical
framework, a braided framework, or combination thereof.
[0059] In some embodiments the tubular member 54 of endprosthesis
100 includes a metallic film deposited by a vapor deposition
process. Vapor deposited materials are formed by depositing film
constituents from a vapor or a vacuum onto a surface. In
embodiments, the constituents are vaporized by bombarding, heating
or sputtering a bulk target. The vaporized constituents deposit on
a substrate to form the film. Deposited films can exhibit highly
uniform thickness and microstructure in very thin films, e.g. about
50 microns or less, e.g. 4-35 microns. Suitable vapor deposition
processes are described in Busch et al. U.S. Pat. No. 5,061,914,
Bose et al. U.S. Pat. No. 6,605,111, Johnston U.S. Pat. No.
6,533,905, and Gupta et al. U.S. 2004/0014253, the entire contents
of all of which are hereby incorporated by reference.
[0060] In some embodiments, the deposited film can include an alloy
of nickel and titanium present in amounts sufficient to provide the
deposited film with desirable mechanical or shape memory
properties. For example, the film may include an alloy, e.g., a
superelastic or pseudo-elastic metal alloy, as described, for
example, in Schetsky, L. McDonald, "Shape Memory Alloys,"
Encyclopedia of Chemical Technology (3rd ed.), John Wiley &
Sons, 1982, vol. 20, pp. 726-736; and commonly assigned U.S. Ser.
No. 10/346,487, filed Jan. 17, 2003. The alloy may be nitinol. The
alloy may include a third compound, e.g., chromium, which modifies
a mechanical property, e.g., a stiffness or elasticity, of the
film. Tubular member 54 may include a deposited metal film
including nickel, titanium, and, optionally, chromium. Exemplary
films and deposition of such films is described in U.S. application
Ser. No. ______, filed September ______, 2004, titled MEDICAL
DEVICES INCLUDING METALLIC FILMS AND METHODS FOR MAKING SAME,
attorney docket no. 10527-570001, which application is incorporated
herein by reference.
[0061] Referring to FIG. 3a, endoprosthesis 100 includes stent body
52 and tubular member 54, which are secured together by a filament
101 at substantially only one location relative to a length l of
the prosthesis. Stent body 54 includes a plurality of framework
members. A plurality of circumferential bands 57 are defined by
longitudinal members 58. Adjacent circumferential bands are
connected by connectors 59 and define fenestrations 60
therebetween.
[0062] Tubular member 54 is defined by a plurality of longitudinal
members 68, which themselves define fenestrations 62
therebetween.
[0063] Filament 101, which, like all filaments discussed herein can
be formed of a polymer, a suture, a ductile metal wire, such as
nitinol or gold wire, or other material, at least partially
encircles prosthesis 101 securing stent body 52 and tubular member
54 at each of a plurality of retention sites 102.sub.i, where, i is
at least 1 and may be 2 or more, 3 or more, 4 or more, e.g., 6 or
more. At each site 102, filament 101 may be threaded through
adjacent fenestrations 62 of tubular member 54 and at least
partially around a longitudinal member 58 or a connector 59 of
stent body 52. Each filament may connect at least two sites 102,
e.g., at least 3 sites.
[0064] Each of the retention sites 102 can be located at
substantially the same distance from a distal or proximal end of
prosthesis 100. In the embodiment shown, each site 102i is located
at a respective distance d3i from a distal end 103 of prosthesis
100. Taken together, sites 102 are located an average distance
d.sub.3 from the distal end 103 of prosthesis 100. A ratio of
average distance d.sub.3 to the total length l of prosthesis 100
may be 50% or less, 35% or less, 25% or less, 15% or less, or 5% or
less. A maximum difference in the distance d.sub.3i for different
retention sites 102.sub.i relative to length l may be 15% or less,
5% or less, or 2.5% or less. In some embodiments, retention sites
102.sub.i are at substantially the same distance, e.g., the same
distance, from an end of prosthesis 100. Retention sites 102 may be
located with respect to a proximal end 105 of prosthesis 100 in the
same manner as that described with respect to distal end 103.
Retention sites 102 may be located centrally with respect to ends
103,105.
[0065] Because stent body 52 and tubular member 54 are secured
together closer to distal end 103 than to proximal end 105, more
proximal portions of stent body 52 and tubular member 54 may move
with respect to one another, e.g., longitudinally along
longitudinal axis a.sub.2 or circumferentially with respect to
prosthesis 100. Thus, during radial expansion, e.g., during
deployment in a body passage, or radial compression, e.g., when
loading the prosthesis within a delivery device, differential
length changes between stent body 52 and tubular member 54 have
little or no tendency to create tension or compression between
portions secured at different locations along longitudinal axis
a.sub.1. Accordingly, upon radial compression and expansion, stent
body 52 and tubular member 54 may tolerate a substantial length
change differential, e.g., the length change differential may be
15% or more, 25% or more, or 35% or more. In some embodiments, the
length change differential is 20% or less, 15% or less, 10% or
less, or 5% or less.
[0066] The longitudinal length change exhibited by tubular member
54 upon expansion and compression can be related to the shape and
size of fenestrations present along the member. In general, greater
longitudinal contraction upon radial expansion occurs as the
circumferential dimension of the fenestrations increases.
Accordingly, the shape and size of the fenestrations may be
modified to reduce or increase the longitudinal length change in
relation to a stent body.
[0067] In some embodiments, retention sites 102 are positioned to
selectively facilitate radial compression or radial expansion of
the prosthesis. For example, deployment and radial expansion of
prosthesis 100 may include withdrawing a sheath that
circumferentially surrounds a radially compressed prosthesis 100.
The withdrawing sheath generally moves from distal portions of
prosthesis 100 toward more proximal portions. In the embodiment
shown (FIG. 3a) with retention sites 102 near the distal end of the
prosthesis, friction between the sheath and stent body 52 or
tubular member 54 has little or no tendency to create compression
between proximally secured portions secured at different locations
along longitudinal axis a, because there are no proximal retention
sites. In embodiments including proximal retention sites as opposed
to distal retention sites, the prosthesis behaves similarly during
loading, which may include passing a sheath over the prosthesis
from the proximal end toward the distal end.
[0068] In some embodiments, the tubular member and stent body are
secured together at both ends prior to loading into a delivery
device. The retention at a first end, e.g., the distal end, is
configured to remain intact during loading and deployment. The
retention at a second end, e.g., the proximal end, can be removed
after loading or does not remain intact during delivery and radial
expansion. For example, the proximal end of the stent body and
tubular member can be secured using a filament that is removable
after loading. The removable retention assists the loading process
as described above and, upon its removal, allows the prosthesis to
accommodate length changes and sheath withdrawal during
implantation. Accordingly, a method for loading a delivery device
for deploying an endoprosthesis can include loading the
endoprosthesis into the delivery device with a stent body and
tubular member of the endoprosthesis being initially secured at
both distal and proximal ends thereof. As part of or after a
process for radially compressing the endoprosthesis, retention
sites at one end, e.g., the proximal end, are removed (or simply do
not survive the complete loading process).
[0069] Filament 101 is shown in FIG. 3a as passing generally around
the exterior of tubular member 54. In other embodiments, one or
more portions of filament 101 may pass inside of tubular member
54.
[0070] In some embodiments, filament 101 only partially encircles
the endoprosthesis. An endoprosthesis may include a plurality of
such partially-encircling filaments. In some embodiments, the
filaments radially constrict tubular member 54 such that the
tubular member is compressed between the filaments and stent body.
In other embodiments, the filaments exert little or no radially
constrictive force. Such filaments may nonetheless operate to
prevent tubular member 54 and stent body 52 from becoming displaced
along the longitudinal axis of the prosthesis.
[0071] In some embodiments, the tubular member differs from a
fabric at least in that the tubular member lacks fibers than can be
pushed apart to receive a filament as by sewing a fabric.
Accordingly, the fenestrations can be formed prior to the process
of passing the filament through the tubular member. Fenestrations
that receive the filaments can be formed by, e.g., etching, laser
cutting, or a photolithographic process.
[0072] Referring to FIG. 3b, an endoprosthesis 125 includes stent
body 52 and tubular member 54, which are secured together by
filaments 126 at substantially only one location along a length l
of the prosthesis. Each filament 126 secures stent body 52 and
tubular member 54 at only a single retention site 127. For example,
at each location 127, filament 126 may be threaded through adjacent
fenestrations 62 of tubular member 54 and at least partially around
a longitudinal member 58 or connector 59 of stent body 52 without
then extending to an adjacent retention site 127.
[0073] Retention sites 127 may be located and positioned with
respect to longitudinal axis a1, length l, and distance d.sub.3 of
prosthesis 125, as retention sites 102 are located and positioned
with respect to longitudinal axis a1, length l, and distance
d.sub.3 of prosthesis 100.
[0074] Referring to FIG. 3c, an endoprosthesis 135 includes stent
body 52 and tubular member 54, which are secured together by a
filament 136 at substantially only one location with respect to a
length l of the prosthesis. Filament 136 secures stent body 52 and
tubular member 54 at only a single retention site 137. For example,
at site 137, filament 136 may be threaded through adjacent
fenestrations 62 of tubular member 54 and at least partially around
a longitudinal member 58 or connector 59 of stent body 52. Filament
136 may, but in the embodiment shown does not, extend to an
adjacent of longitudinal member 58 or connector 59.
[0075] Retention site 137 may be located and positioned with
respect to longitudinal axis a1, length l, and distance d.sub.3 of
prosthesis 135, as retention sites 102 are located and positioned
with respect to longitudinal axis a1, length l, and distance
d.sub.3 of prosthesis 100. For example, the single retention site
137 may be located distally, proximally, or centrally with respect
to prosthesis 135. Retention site 137 may be a single point along
prosthesis 135.
[0076] Referring to FIG. 3d, an endoprosthesis 175 includes a stent
body 177 and a tubular member 179, which are secured together by a
filament 181 at substantially only one location with respect to a
length l2 of the prosthesis 175. Filament 181 at least partially
encircles prosthesis, passing through retention fenestrations 185
of tubular member 179 and at least partially around longitudinal
members 183 of stent body 177.
[0077] Referring to FIG. 3e, an endoprosthesis 195 includes stent
body 177 and a tubular member 194, which are secured together by a
filament 181 at substantially only one location with respect to
length l2 of the prosthesis 195. Filament 181 does not encircle
prosthesis. Rather, filament 181 passes through adjacent retention
fenestrations 197 of tubular member 194 and at least partially
around a longitudinal member 183 of stent body 177 so as to define
a single retention site. In some embodiments, filament 181 allows
some relative radial and or longitudinal freedom of movement
between stent body 52 and tubular member 54. In some embodiments,
filament 181 allows essentially no relative radial and or
longitudinal freedom of movement between stent body 52 and tubular
member 54.
[0078] In some embodiments, a tubular member includes a plurality
of fenestrations configured to modify a flow of blood between a
vessel and aneurysm as discussed above. The tubular member and a
stent body can be secured to one another by filaments that extend
through fenestrations having a size and shape identical to
fenestrations that modify the flow of blood. In other embodiments,
tubular member fenestration are particularly associated with
retention of the tubular member with respect to the stent body. For
example, the size and location of such fenestrations may correspond
with certain sites of the stent body. The only fenestrations of the
tubular member may be associated with retention of the tubular
member and stent body.
[0079] Referring to FIGS. 4a and 4b, an endoprosthesis 275 includes
a stent body 277 and a tubular member 279, which can be secured
together with complementary elements that are integral with the
stent body and tubular member. For example, the stent body 277 and
tubular member 279 can be secured together without a third material
or structure. In the embodiment shown, stent body 277 includes a
plurality of projections, e.g., pins 283 that extend generally
radially, e.g., radially outward or inward, from the stent body.
Tubular member 279 includes a plurality of fenestrations that align
with pins 283. Upon positioning tubular member 279
circumferentially with respect to stent body 277, the pins 283
extend through the fenestrations. Pins 283 are then radially
enlarged, as by compression along their length, to form a cap or
grommet-like structure. The radially enlarged pins 283 can obscure
fenestrations of the tubular member 279 as shown.
[0080] Each radially enlarged pin forms a retention site 281 at
which a portion of tubular member 279 adjacent the fenestration is
retained between, e.g., compressed between, stent body 277 and the
cap or grommet-like structure of the radially enlarged pin. The
retention is sufficient to limit or prevent the complete separation
of the tubular member and stent body (in the absence of damage to
either one). In some embodiments, the size and shape of the
fenestrations and the amount of compression along the length of
each pin is configured to allow the tubular member and stent body
radial, circumferential, and/or longitudinal freedom of movement
with respect to one another. For example, the radial,
circumferential, and/or longitudinal freedom of movement may be at
least 2.5%, at least 5%, at least 10%, at least 20% relative to the
radius, circumference, or length of the endoprosthesis,
respectively. In such embodiments, fenestrations of the tubular
member 279 may be shaped to allow the movement. For example, a
circumferentially extending slot allows circumferential movement
between the stent body and tubular member. In some embodiments, no
such freedom of movement is allowed in one or more dimensions.
[0081] In some embodiments, the endoprosthesis includes only one
retention site 281, which may be located near an end of the
prosthesis or a middle. A plurality of retention sites 281 may be
positioned at various locations along a longitudinal axis of
prosthesis 275. Alternatively, a plurality of retention sites 281
may be located at substantially one distance with respect to a
proximal or distal end of the prosthesis, e.g., as discussed with
respect to prosthesis 100.
[0082] In some embodiments, pins 283 have a different strength or a
different malleability than other portions of stent body 277. For
example, pins 283 may be formed with a different composition and/or
microstructure to provide pins 283 with more malleability than
circumferential bands 287, which contribute to radial expansion of
prosthesis 277.
[0083] Referring to FIG. 5a, an endoprosthesis 350 includes a stent
body 177 and a tubular member 351 which can be secured together
with complementary elements that are integral with the stent body
and tubular member. Stent body 177 and tubular member 351 are
secured to one another by at least one retention site 352.
Referring also to FIGS. 5b and 5c, each retention site includes a
first tab 354 and an optional second tab 355. Each tab may have one
or more free edges 359 and at least one fixed end or edge 360,
which is joined with tubular member 351. The nearest free edges of
tabs 354,355, which edges are adjacent in the embodiment shown,
may, in other embodiments, be separated by a distance about equal
to or less than a width of each tab, e.g., a width of each fixed
edge.
[0084] Each tab 354,355 extends over, e.g., is hooked over, a
longitudinal member 183 of stent body 177. Each tab may extend from
its fixed end, which is generally located on a first side of a
local circumferential perimeter of the stent body to the opposite
side of the perimeter. For example, fixed ends 360 of tabs 355 are
located outside the local perimeter of stent body 177. The tabs 355
extend from the fixed ends 360 toward the inside of the
perimeter.
[0085] Each tab may exert a force urging the tab toward tubular
member 351, e.g., out of the page in FIG. 5b. For example, tabs
354,355 formed of a memory alloy such as nitinol may be shape set
in an orientation that enhances such force. Hence, longitudinal
member 183 may be compressed between the tabs 354,355 and tubular
member 351.
[0086] If more than one retention site is present, the retention
sites may be located at different distances from a distal or
proximal end of prosthesis 350 as shown. Alternatively, a plurality
of retention sites may be located at substantially the same
distance with respect to a distal or proximal end of prosthesis 350
as discussed for prostheses 100, 125, and 135.
[0087] Stent body 177 and tubular member 351 may have freedom of
movement with respect to one another along a longitudinal axis a3
of prosthesis 351 and/or circumferentially with respect to
prosthesis 351. For example, in some embodiments, most or all of
tabs 354,355 engage only longitudinal members having a longitudinal
axis a4 that is aligned with axis a3 of the prosthesis. Such a
construction can allow for longitudinal freedom of movement. In
other embodiments, most or all of tabs 354,355 engage only
longitudinal members having a longitudinal axis a4 that is at a
non-zero angle with respect to axis a3 of prosthesis 325, e.g., at
45.degree. thereto or perpendicular thereto. Such a construction
can allow for circumferential freedom of movement.
[0088] In some embodiments, tabs 354,355 are unitary with tubular
member 351. For example, tabs 354,355 may be formed by laser
cutting tublar member 351 along dimensions defining free edges 359
of the resulting tabs. In other embodiments, tabs 354,355 are
formed by securing another piece of material adjacent to a
fenestration of tubular member 351. In any event, whether or not
tubular member 351 includes a deposited film, tabs 354,355 may be
made of a metal, e.g., a memory alloy such as nitinol. Tabs 354,355
may include a memory alloy of titanium, nickel, and, optionally,
chromium. In some embodiments, tabs 345,355 are subjected to a
process that modifies, e.g., increases a number of
dislocations.
[0089] Tubular member 351 is shown as surrounding stent body 177.
In other embodiments, a portion or all of tubular member 351 is
disposed within a circumference of stent body 177. Tubular member
351 is shown as lacking fenestrations except for those associated
with retention sites 352. In other embodiments, tubular member 351
may include a plurality of fenestrations not associated with
retention sites, e.g., as discussed with respect to tubular member
54.
[0090] Referring to FIGS. 6a and 6b, an endoprosthesis 375 includes
a stent body 177 and a tubular member 353, which can be secured
together with complementary elements that are integral with the
stent body and tubular member. In particular, tabs 355 of tubular
member 353 engage fenestrations 357 of stent body 177. Engagement
between the tabs 355 and fenestrations 177 retains the tubular
member 353 and stent body with respect to one another. Tabs 355 can
be folded back on themselves about portion 359 of stent body
177.
[0091] In some embodiments, tabs 355 are unitary with tubular
member 353. For example, tabs 355 can be deposited as a portion of
a metallic film of the tubular member. Alternatively, tabs 355 can
be machined, e.g., by laser cutting, to form tubular member 353. In
other embodiments, tabs 355 include a separate piece of material
that is attached to the bulk of tubular member 353. Such attachment
may be provided using, e.g., mechanical, brazing, welding, or
adhesive retention.
[0092] In the embodiment shown in FIG. 6a, tubular member 353
surrounds stent body 177. Each tab 355 extends radially inward of a
terminus 359 of stent body 355. Tabs 355 may be formed with a force
that urges the tabs radially outward, e.g., out of the page with
respect to FIG. 6b, so as to more securely engage stent body 177.
For example, tabs 355 may be formed of a memory alloy that is shape
set to a radially outwardly projecting state.
[0093] Referring to FIG. 6c, another embodiment of an engagement
between tab 355 and an eyelet 361 of a stent body (the major
portion of which is not shown) includes tab 355 extending through a
hole 363 having a maximum inner extent of about 5 times or less of
a width of tab 355, e.g., about 2.5 times or less of a width of tab
355.
[0094] Referring to FIG. 6d, in another embodiment, a tubular
member 371 includes one or more fenestrations 367. Stent body 373
includes one or more projections or tabs 365, which engage a
respective fenestration 367 of the tubular member. Tabs 365 may
include radiopaque markers. The engagement can secure the stent
body and tubular member together without use of a third material to
form an endoprosthesis. In some embodiments, one or more
fenestrations 367 and tabs 365 are located at one end only of the
endoprosthesis. In other embodiments, one or more fenestrations 367
and tabs 365 are located at both ends of the endoprosthesis.
[0095] Tubular member 371 may surround stent body 373 or be
surrounded by the stent body. In any event, either or both tubular
member and stent body may be provided with a radial force that
enhances the retention between the tubular member and stent body.
For example, in embodiments in which tubular member 371 surrounds
stent body 373, end portions of tubular member 371 may exert a
radial inward force against tabs 365 of stent body 373.
[0096] In some embodiments, prosthesis 350 includes only a single
tab engaging a single fenestration of the stent body. In other
embodiments, a plurality of circumferentially located tabs engage a
respective fenestration at one end only of the prosthesis, e.g.,
only the proximal or distal end.
[0097] Tabs of endoprostheses shown in FIGS. 6a-6d are depicted as
extending away from a longitudinal center of the prosthesis, e.g.,
tabs 355 have an end fixed with respect to tubular member 353 and
an end free with respect to tubular member 353, wherein the fixed
end is positioned closer to the longitudinal center of the
prosthesis. In other embodiments, such tabs may extend inward
toward the center. For example, the fixed end of one or more tabs
355 can be located closer than the free end of the one or more tabs
to the ends of the endoprosthesis so that the tabs extend toward
the longitudinal center of the endprosthesis. In other embodiments,
the tabs are oriented along a dimension that extends both
circumferentially and longitudinally with respect to the
endoprosthesis. In such embodiments, the stent body and tubular
member may be allowed some degree of rotational and longitudinal
freedom of movement.
[0098] Referring to FIGS. 7a and 7b, an endoprosthesis 425 includes
stent body 177 and a tubular member 426, which can be secured
together with complementary elements that are integral with the
stent body and tubular member. As seen in FIG. 7b, tubular member
426 includes elongate bands 429, which extend from an edge 431 of
member 426. Elongate bands 429 extend at least partially around a
circumference of prosthesis 425 and can extend beneath another
portion of tubular member 426. Such engagement can maintain a
desired three-dimensional structure, e.g., shape and diameter, of
endoprosthesis 425. Alternatively, or in combination, elongate
bands 429 can engage a longitudinal member 183 or other portion of
stent body 177. Such engagement can limit or prevent relative
radial and/or longitudinal movement of tubular member 426 and stent
body 177.
[0099] As seen in FIG. 7a, elongate bands 429 extend through
fenestrations 427, beneath a portion 439 of tubular member 426, and
out of fenestrations 428. Elongate bands 429 also extend beneath
longitudinal members 183 of stent body 177. Edge 431 can overlap at
least a portion of tubular member 426 so that an opposing edge 433
is concealed. In other embodiments, opposed edge 433 overlaps edge
431. In such embodiments, elongate bands 429 can extend beneath a
portion 440 of tubular member 426, out from fenestrations 427, over
portion 439 and into fenestrations 428.
[0100] When tubular member 426 is configured in three dimensions,
as shown in FIG. 7a, edge 431 is aligned generally with a
longitudinal axis a6 of prosthesis 425. In other embodiments, edge
431 extends at an angle to axis a.sub.6. For example, edge 431 may
spiral generally around a circumference of prosthesis 425.
[0101] Elongate bands 429 can have a longitudinal axis a.sub.7. In
some embodiments, axis a.sub.7 and edge 431 are oriented generally
perpendicular to one another. In other embodiments, axis a.sub.7 is
oriented at an angle of less than 90.degree. with respect to edge
431. In some embodiments, axis a.sub.7 and axis a.sub.6 are
oriented generally perpendicular to one another. In other
embodiments, axis a.sub.7 is oriented at an angle of less than
90.degree. with respect to axis a.sub.6. For example, one or both
of elongate bands 429 may spiral generally around a circumference
of prosthesis 425.
[0102] In some embodiments, tubular member 429 includes only 1
elongate band. In other embodiments, tubular member 426 includes at
least 3, e.g., at least 4 elongate bands. The one or more elongate
bands can be evenly spaced along a length of tubular member 426 or
positioned at non-equal intervals. For example, one or more bands
may be positioned near either or both of the proximal and distal
ends of the prosthesis. One or more bands may be centrally located
with respect to a length of the prosthesis.
[0103] Referring to FIG. 8a, an endoprosthesis 450 includes a stent
body 451 and a tubular member 452, which may include a thin film
and other properties of tubular member 54. Referring also to FIG.
8b, stent body 451 includes a plurality of radial projections 453,
which may be formed by bends or hooks in longitudinal members or
connectors of the stent body. Projections 453 are shown as
projecting outward from a radial center of prosthesis 450 but some
or all of the projections may project inward. Projections 453 may
be closed, e.g., as an eyelet or closed portion of the stent body
or the projections may be open, as in a hook-shape. Tubular member
452 includes a plurality of fenestrations 461, each of which
corresponds to a projection 453 of stent body 451.
[0104] Tubular member 452 circumferentially surrounds stent body
451 so that projections 453 are accessible via fenestrations 461.
In some embodiments, at least a portion of projections 453 extends
outward through fenestrations 461. Filaments 455 extend
circumferentially around at least a portion of prosthesis 450.
Filaments 455, fenestrations 461, and projections 453 cooperate to
form a plurality of retention sites that limit or prevent relative
movement between tubular member 452 and stent body 451. Filaments
455 are generally disposed adjacent an opposite surface of tubular
member 452 from stent body 451. For example, if tubular member 452
surrounds stent body 451, filament 455 can be disposed adjacent an
external surface of the tubular member.
[0105] In some embodiments, filaments 455 radially constrict
tubular member 452 about stent body 451, such that tubular member
452 is compressed between the filaments and stent body 451. In
other embodiments, filaments 455 provide essential no radial
compression but limit a radial freedom of movement between tubular
member 452 and stent body 451 such that they do not become
substantially displaced along a longitudinal axis of the
prosthesis.
[0106] Projections 453 define a longitudinal axis a9 extending
therethrough. In some embodiments, all or some of projections 453
are oriented so that axes a9 are generally aligned with
longitudinal axis a8 of prosthesis 450. In some embodiments, all or
some of projections 453 are oriented so that axes a9 are generally
perpendicular to axis a8. In some embodiments, filaments 455 extend
longitudinally as opposed to or in combination with
circumferentially extending filaments. Fenestrations and
projections can be positioned at similar or different locations
with respect to the length of prosthesis 450 as, e.g., retention
sites of prostheses 100, 125, and 135.
[0107] Referring to FIG. 8c, a tubular member 470 is configured for
retention to a stent body, such as to stent body 451 having
projections 453. Member 470 includes a plurality of projections
479, each defined by a fixed edge 480 and a plurality of free edges
481, a projection 482, defined by a fixed edge 483 and a plurality
of free edges 484, a projection 485, defined by a fixed edge 486
and a plurality of free edges 487, and a plurality of projections
488, each defined by a fixed edge 489 and a plurality of free edges
490.
[0108] Although shown as two-dimensional, tubular member 470 can be
manufactured in an initially three-dimensional state or made
three-dimensional, e.g., by rolling member 470 about longitudinal
axis a10 or about an axis oriented at an angle thereto, e.g.,
perpendicular thereto. Member 470 can be circumferentially mated
with stent body 451 by positioning member 470 about the stent body.
Projections of tubular member 470 engage projections 453 of the
stent body to limit or reduce relative movement between member 470
and stent body 453.
[0109] In some embodiments, some or all of the projections of the
tubular member 470 are oriented to engage projections 453 of stent
body 451 having an axis a9 that is generally perpendicular to axis
a8 of stent body 451. Such an engagement configuration can allow
tubular member 470 and stent body 451 to have some circumferential
freedom of movement while being more limiting with respect to
longitudinal freedom of movement. In some embodiments, some or all
of the projections of the tubular member 470 are oriented to engage
projections 453 of stent body 451 having an axis a9 that is
generally aligned with axis a8 of stent body 451. Such an
engagement configuration can allow tubular member 470 and stent
body 451 to have some longitudinal freedom of movement while being
more limiting with respect to circumferential freedom of
movement.
[0110] In some embodiments, some or all of the projections are
oriented so that a fixed edge of the projection is generally
perpendicular to a longitudinal axis of the stent body. For
example, fixed-edge 480 of projection 479 and fixed edge 489 of
projection 488 would each be perpendicular to axis a8 of stent body
451 if the tubular member were rolled about axis a10 and mated with
the stent body. In some embodiments, some or all of the projections
are oriented so that a fixed edge of the projection is generally
aligned with a longitudinal axis of the stent body. For example,
fixed edge 483 of projection 482 and fixed edge 486 of projection
485 would be aligned with axis a8 of stent body 451 if the tubular
member were rolled about axis a10 thereof.
[0111] Projections 479, 482, 485, and 488 are shown as projecting
toward an interior 493 of tubular member 470. In some embodiments,
some or all of the projections project toward an outer edge of the
tubular member.
[0112] Referring to FIG. 9, a prosthesis 500 includes a tubular
member 501 and a stent body 177 secured by filament 503. Tubular
member 501 includes fenestrations 505, which are defined by slits
or cut-outs. Filament 503 passes through a fenestration 505 and
beneath a portion 506 of tubular member 501, where the filament
engages stent body 177, e.g., a longitudinal member 183. Filament
503 passes back to the exterior of tubular member 501 through
another fenestration 505.
[0113] Referring to FIGS. 10a-10c, an endoprosthesis 325 includes a
stent body 327 and a tubular member 329, which may include a film
or thin film structure as described for tubular member 54. Stent
body 327 includes a portion 331 having a diameter d5 and a portion
337 having a smaller diameter d6. At least a portion of tubular
body 329 occupies a recess that results from the difference in
radii between portions 331,337. A radial differential
.DELTA.r.sub.1 may provide the recess with a depth sufficient to
fully accommodate tubular member 329 with respect to a radial
direction. In some embodiments, radial differential .DELTA.r.sub.1
is at least 7.5 .mu.m, at least 15 .mu.m, or at least 25 .mu.m. In
some embodiments, radial differential .DELTA.r.sub.1 is 250 .mu.m
or less, 125 .mu.m or less, 75 .mu.m or less, 50 .mu.m or less,
e.g., 25 .mu.m or less. A difference .DELTA.d in diameter between
portions 331,337 is given by 2.DELTA.r.sub.1.
[0114] In some embodiments, tubular member 329 has a smaller
expanded diameter than portion 337 of stent body 327 would have in
the absence of member 329. Hence, portion 337 of stent body 327 may
exert a radial force against tubular member 329 in the radially
expanded state of the prosthesis 325.
[0115] In some embodiments, portion 337 is formed by radially
removing material from the stent body. For example, material may be
removed from the stent body chemically, as by etching, or
mechanically, as by grinding. In some embodiments, portion 337 is
formed by adding additional material to portion 331. For example,
diameter d5 can be increased by sputtering material, e.g., nitinol,
onto portion 331.
[0116] Portion 331 may be located at either a distal end or a
proximal end of prosthesis 325. Portion 331 extends a distance d4
along a length l4 of prosthesis 325. Portion 337 extends a distance
d7 along length l4. A ratio of d4 to l4 may be at least 0.05, at
least 0.1, e.g., at least 0.2. A ratio of d4 to l4 may be 0.3 or
less, 0.2 or less, 0.15 or less, e.g., 0.1 or less. A ratio of d7
to l4 may be at least 0.5, at least 0.6, at least 0.8, at least 0.9
or at least 0.95. Various dimensions for prosthesis 325 are with
reference to the radially expanded state of the prosthesis.
[0117] In some embodiments, prosthesis includes a second portion
333, which has a larger diameter than portion 337. In general,
portion 333 has a diameter identical to portion 331. Portion 333
extends a distance d8 along length l4 of prosthesis 325. A ratio of
d8 to l4 may assume values as described for the ratio of d4 to
l4.
[0118] In some embodiments, a gap 335 is present between portion
331 and 337. Gap 335 may have a width sufficient to accommodate
differential expansion between the stent body and tubular member. A
ratio of a total width of gaps 335 to length l4 may be 0.25 or
less, 0.15 or less, 0.075 or less, e.g., 0.05 or less.
[0119] In some embodiments, portion 331 and optional portion 333
exert a higher radial force than portion 337. For example, a radial
outward force exerted by portions 331,333 may be at least 20%, at
least 50%, or at least 100% greater than a radial outward force
exerted by portion 337.
[0120] Stent body 327 and tubular member 329 can be secured using
any of the retention techniques discussed herein, e.g.,
mechanically, by welding, by brazing, or adhesively. In some
embodiments, stent body 327 and tubular member 329 are secured
radially but are allowed some longitudinal freedom of movement
along length l4 so as to accommodate length changes during
expansion and contraction. An exemplary embodiment includes at
least one circumferential collar 341, which is secured to either
the stent body or tubular member 329 but generally not to both.
Collar 341 may be formed of a metal, e.g., a superelastic alloy, or
polymer. Collar 341 may be secured using, e.g., mechanical,
welding, brazing, or adhesive techniques. In some embodiments
collar 341 allows tubular member at least radial freedom of
movement. For example, radial differential .DELTA.r.sub.1 may
exceed a diameter of tubular member 329, which may have an expanded
diameter intermediate diameter d5 and d6.
[0121] Other examples of endoprostheses including a thin film as
well as related systems and methods are described in U.S.
provisional patent application No. 60/549,287, filed Mar. 2, 2004,
which application is incorporated herein by reference.
[0122] An endoprosthesis may include a cover disposed externally to
a framework as shown and/or internally of a framework.
Endoprostheses having a cover including, e.g., a deposited thin
film, disposed internally of a framework are described in U.S.
patent application Ser. No. ______, attorney docket no.
10527-567001, titled MEDICAL DEVICES INCLUDING METALLIC FILMS AND
METHODS FOR MAKING SAME, and filed concurrently herewith, which
application is incorporated herein by reference.
[0123] An endoprosthesis may include features to enhance a
flexibility of the endoprosthesis as described in U.S. patent
application Ser. No. ______, attorney docket no. 10527-568001,
titled MEDICAL DEVICES INCLUDING METALLIC FILMS AND METHODS FOR
MAKING SAME, and filed concurrently herewith, which application is
incorporated herein by reference.
[0124] An endoprosthesis may include a deposited thin film and a
polymer as described in U.S. patent application Ser. No. ______,
attorney docket no. 10527-596001, titled MEDICAL DEVICES INCLUDING
METALLIC FILMS AND METHODS FOR MAKING SAME, and filed concurrently
herewith, which application is incorporated herein by
reference.
[0125] An endoprosthesis may include one or more filaments, e.g.,
wires, adapted to enhance mechanical properties of a deposited thin
film as described in U.S. patent application Ser. No. ______,
attorney docket no. 10527-621001, titled MEDICAL DEVICES INCLUDING
METALLIC FILMS AND METHODS FOR MAKING SAME, and filed concurrently
herewith, which application is incorporated herein by
reference.
[0126] Methods for loading an endoprosthesis into a delivery device
and systems for delivering an endoprosthesis to a treatment site
are described in U.S. patent application Ser. No. ______, attorney
docket no. 10527-569001, titled MEDICAL DEVICES INCLUDING METALLIC
FILMS AND METHODS FOR LOADING AND DEPLOYING SAME, which application
is incorporated herein by reference.
[0127] All publications, references, applications, and patents
referred to herein are incorporated by reference in their
entirety.
[0128] Other embodiments are within the claims.
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