U.S. patent application number 12/576481 was filed with the patent office on 2010-02-04 for implantable support device with graft.
Invention is credited to Brian C. Case, Jacob A. Flagle, Michael L. Garrison, Andrew K. Hoffa, Joseph F. Obermiller, Ram H. Paul.
Application Number | 20100030314 12/576481 |
Document ID | / |
Family ID | 33299793 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100030314 |
Kind Code |
A1 |
Case; Brian C. ; et
al. |
February 4, 2010 |
IMPLANTABLE SUPPORT DEVICE WITH GRAFT
Abstract
Implantable medical devices comprising a support frame and a
graft member attached to the support frame. The support frame can
define one or more structural features that substantially prevent
migration of the graft member along the support frame.
Inventors: |
Case; Brian C.;
(Bloomington, IN) ; Flagle; Jacob A.;
(Indianapolis, IN) ; Paul; Ram H.; (Bloomington,
IN) ; Hoffa; Andrew K.; (Bloomington, IN) ;
Garrison; Michael L.; (Bloomington, IN) ; Obermiller;
Joseph F.; (West Lafayette, IN) |
Correspondence
Address: |
BUCHANAN INTELLECTUAL PROPERTY OFFICE LLC
P.O. BOX 700
PERRYSBURG
OH
43552-0700
US
|
Family ID: |
33299793 |
Appl. No.: |
12/576481 |
Filed: |
October 9, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10820918 |
Apr 8, 2004 |
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12576481 |
|
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60461339 |
Apr 8, 2003 |
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Current U.S.
Class: |
623/1.3 ;
623/1.36 |
Current CPC
Class: |
A61F 2/848 20130101;
A61F 2220/0016 20130101; A61F 2/2418 20130101; A61F 2220/0058
20130101; A61F 2230/0054 20130101; A61F 2220/005 20130101; A61F
2230/0026 20130101; A61F 2/2475 20130101; A61F 2230/0095
20130101 |
Class at
Publication: |
623/1.3 ;
623/1.36 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. An implantable medical device, comprising: an expandable support
frame having a first end, a second end, a surface, and a plurality
of struts interconnected by bends; a first series of barbs disposed
at the first end of the expandable support frame and extending in a
first direction; a second series of barbs disposed at the second
end of the expandable support frame and extending in a second,
different direction; and a graft member attached to the support
frame; wherein each barb of the first and second series of barbs
extends away from the surface of the expandable support frame and
through the graft member.
2. The implantable medical device according to claim 1, wherein the
first direction is substantially opposite the second direction.
3. The implantable medical device according to claim 1, wherein the
expandable support frame is adapted such that the first and second
ends of the support frame are brought near each other when the
implantable medical device is positioned within a vessel such that
the barbs of the first series of barbs and the barbs of the second
series of barbs extend in the same direction.
4. The implantable medical device according to claim 1, further
comprising a third series of barbs disposed at the first end of the
expandable support frame and extending in a third direction that is
different than the first direction.
5. The implantable medical device according to claim 4, wherein
each barb of the third series of barbs extends away from the
surface of the expandable support frame and through the graft
member.
6. The implantable medical device according to claim 4, further
comprising a fourth series of barbs disposed at the second end of
the expandable support frame and extending in a fourth direction
that is different than the second direction.
7. The implantable medical device according to claim 6, wherein
each barb of the fourth series of barbs extends away from the
surface of the expandable support frame and through the graft
member.
8. The implantable medical device according to claim 1, wherein the
expandable support frame is self-expandable.
9. The implantable medical device according to claim 1, wherein the
expandable support frame is balloon-expandable.
10. The implantable medical device according to claim 1, wherein
the expandable support frame is formed from wire.
11. The implantable medical device according to claim 1, wherein
the expandable support frame is cut from a piece of tubing.
12. The implantable medical device according to claim 1, wherein
the expandable support frame is formed of one of a metal, a natural
material, a synthetic material, a polymer, and a composite
material.
13. The implantable medical device according to claim 1, wherein
the expandable support frame is formed of one of stainless steel,
Nitinol and cobalt chromium.
14. The implantable medical device according to claim 1, wherein
the expandable support frame is formed of a resorbable
material.
15. The implantable medical device according to claim 1, wherein
the graft member comprises a natural material.
16. The implantable medical device according to claim 1, wherein
the graft member comprises a bioremodellable material.
17. The implantable medical device according to claim 16, wherein
the bioremodellable material comprises an extracellular matrix
material.
18. The implantable medical device according to claim 16, wherein
the bioremodellable material comprises small intestine
submucosa.
19. The implantable medical device according to claim 1, wherein
the graft member comprises a synthetic material.
20. The implantable medical device according to claim 1, wherein
the graft member comprises first and second leaflets that define an
opening.
21. The implantable medical device according to claim 1, wherein
the surface of the expandable support frame has first and second
sides and all barbs of the first and second series of barbs are
disposed on the first side.
22. The implantable medical device according to claim 1, wherein
the surface of the expandable support frame has first and second
sides; wherein at least one barb of the first series of barbs is
disposed on the first side; and wherein at least one barb of the
second series of barbs is disposed on the second side.
23. The implantable medical device according to claim 1, wherein at
least one barb is integrally formed by the expandable support
frame.
24. The implantable medical device according to claim 1, wherein at
least one barb comprises a separate member attached to the
expandable support frame.
25. An implantable medical device according to claim 1, wherein the
graft member defines a valve for regulating fluid flow through the
implantable medical device.
26. An implantable medical device, comprising: an expandable
support frame having a first end, a second end, a surface, and a
plurality of struts interconnected by bends; first and second
opposing barbs disposed at the first end; third and fourth opposing
barbs disposed at the second end; a graft member attached to the
support frame; wherein each of the barbs extends away from the
surface of the expandable support frame and through the graft
member.
27. An implantable medical device, comprising: an expandable
support frame having a first end, a second end, a surface, and a
plurality of struts interconnected by bends; first and second barbs
disposed on a first strut of the plurality of struts and extending
away from the surface in opposing directions; a graft member having
an edge in contact with at least a portion of the surface of the
first strut; and an attachment element placed across the first
strut and through the graft member; wherein the attachment element
is disposed between the first and second barbs.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/820,918, filed on Apr. 8, 2004, which
claims priority to U.S. Provisional Application Ser. No.
60/461,339, filed on Apr. 8, 2003. Each of these applications is
hereby incorporated into this disclosure in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to medical devices. More particularly,
the invention relates to intraluminal support devices with attached
graft members. Exemplary embodiments of the invention relate to
intraluminal prosthetic valves, such as prosthetic venous
valves.
BACKGROUND OF THE INVENTION
[0003] Many vessels in animals transport fluids from one bodily
location to another. Frequently, fluid flows in a unidirectional
manner along the length of the vessel. Varying fluid pressures over
time, however, can introduce a reverse flow direction in the
vessel. In some vessels, such as mammalian veins, natural valves
are positioned along the length of the vessel and act as one-way
check valves that open to permit the flow of fluid in the desired
direction, and quickly close upon a change in pressure, such as a
transition from systole to diastole, to prevent fluid flow in a
reverse direction, i.e., retrograde flow. While these natural
valves may function for an extended time, some may lose
effectiveness, which can lead to physical manifestations and
pathology. For example, venous valves are susceptible to becoming
insufficient due to one or more of a variety of factors. Over time,
the vessel wall may stretch, affecting the ability of the valve
leaflets to close. Furthermore, the leaflets may become damaged,
such as by formation of thrombus and scar tissue, which may also
affect the ability of the valve leaflets to close. Once valves are
damaged, venous valve insufficiency is present, and can lead to
discomfort and possibly ulcers in the legs and ankles.
[0004] Current treatments for venous valve insufficiency include
the use of compression stockings that are placed around the leg of
a patient. Surgical techniques are also employed in which valves
can be bypassed or replaced with autologous sections of veins with
competent valves.
[0005] Minimally invasive techniques and instruments for placement
of intraluminal medical devices have developed over recent years. A
wide variety of treatment devices that utilize minimally invasive
technology has been developed and includes stents, stent grafts,
occlusion devices, infusion catheters and the like. Minimally
invasive intravascular devices have especially become popular with
the introduction of coronary stents to the U.S. market in the early
1990's. Coronary and peripheral stents have been proven to provide
a superior means of maintaining vessel patency, and have become
widely accepted in the medical community. Furthermore, the use of
stents has been extended to treat aneurisms and to provide
occlusion devices, among other uses.
[0006] Recently, prosthetic valves have been developed that use a
support frame such as a stent. Frequently, a graft member is
attached to the support frame and provides a valve function to the
device. For example, the graft member can be in the form of a
leaflet that is attached to a stent and movable between first and
second positions. In a first position, the valve is open and allows
fluid flow to proceed through a vessel in a first direction, and in
a second direction the valve is closed to prevent fluid flow in a
second, opposite direction. An example of this type of prosthetic
valve is described in commonly owned U.S. Pat. No. 6,508,833, to
Pavcnik for a MULTIPLE-SIDED INTRALUMINAL MEDICAL DEVICE, which is
hereby incorporated by reference in its entirety. In other examples
of prosthetic valves, a tube that terminates in leaflets is
attached to one or more support frames to form a valve. The
leaflets open to permit fluid flow in a first direction in response
to fluid pressure on one side of the leaflets, and close to prevent
fluid flow in a second, opposite direction in response to fluid
pressure on opposite sides of the leaflets. An example of this
configuration is provided in U.S. Pat. No. 6,494,909 to Greenhalgh
for AN ENDOVASCULAR VALVE, which is hereby incorporated by
reference in its entirety.
[0007] Prosthetic valves are designed to replace or supplement the
function of incompetent natural valves. The use of an expandable
support frame in valve devices allows for the use of minimally
invasive delivery devices and techniques for placement of the
valves within body vessels, which will likely lower the overall
cost of treatment and increase the acceptance of these medical
devices by practitioners and patients alike.
[0008] The inclusion of a support frame and a valve member, such as
a graft member, in a prosthetic valve device necessarily requires a
connection between these components. The dynamic environment in
which prosthetic valves are placed requires a connection that
minimizes migration of the graft member on the support frame.
SUMMARY OF THE INVENTION
[0009] In some embodiments, the invention provides intraluminal
medical devices that include structural features adapted to enable
a more stable connection between the graft member and the support
frame. Thus, the invention provides implantable medical devices
that include a graft member attached to a support frame that
defines structural features that enable a more stable connection
between the graft member and the support frame. In exemplary
embodiments, medical devices according to the invention provide a
valve for regulating fluid flow through a body vessel. The device
is particularly well suited for percutaneous delivery through a
body vessel to a point of treatment, and comprises a prosthetic
venous valve in an illustrative embodiment.
[0010] The prosthetic venous valves according to the invention
include a support frame, such as an endoluminal stent, that has
radially compressed and radially expanded configurations. The
support frame can comprise any suitable support frame, including
self expandable, balloon expandable, wire, tube, metal, polymeric,
composite, and other types of support frames known in the art. The
devices also include at least one graft member attached to the
support frame. The graft member preferably provides a valve
function to the device. In exemplary embodiments, the graft member
comprises a valve leaflet that moves between first and second
positions while remaining attached to the support frame. In the
first position, the leaflet substantially blocks the lumen of the
vessel, while the lumen is substantially open when the leaflet is
in the second position. Thus, the leaflet permits fluid flow
through the vessel in a first direction when in the first position,
and substantially prevents fluid flow in a second, opposite
direction when in the second position. The graft member can also be
formed into other suitable valve configurations, such as a duckbill
configuration, a tube or partial tube configuration, and an
evertable tube configuration. The graft member can be formed of any
suitable material, including natural and synthetic materials. In
exemplary embodiments of the invention, the graft member is formed
of an Extracellular Matrix (ECM) material, such as Small Intestine
Submucosa (SIS).
[0011] The graft member can be attached to the support frame in a
variety of ways, such as by sutures or other suitable attachment
elements. In exemplary embodiments, the support frame defines one
or more structural features that provide a securement position at
which the graft member can be attached to the support frame.
Preferably, the structural feature is adapted to prevent migration
of the graft material relative to the support frame. The type of
structural feature utilized depends on the type of support frame
used. For example, when a wire support frame is utilized, a loop or
eyelet structure can be formed readily in the wire of the support
frame. The loop or eyelet can be used as a securement position at
which the graft member can be attached to the support frame by an
attachment element. If, however, a tube member is used as the
support frame, such as a stent cut from a solid tube of material,
the formation of loops and eyelets may be difficult. Accordingly,
other structural features, such as contoured struts, areas of
enlarged width, barbs formed on the struts, strut projections,
clips, and other structures can be used. Also, various attachment
techniques, either alone or in combination with the various
structural features, can be utilized for attaching the graft member
to the support frame.
[0012] In other embodiments, the graft member is adhered to itself
or to the support frame with agents such as tissue adhesives,
cross-linkers, or natural materials such as fibrin. Also,
techniques such as laser welding can be used. Furthermore, the
graft member itself can define structural features that facilitate
attachment to a support frame, such as a tab and corresponding
slot.
[0013] A more detailed explanation of the invention is provided by
the attached drawings and detailed description, which illustrate
exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a top view of a support frame for use in medical
devices according to the invention.
[0015] FIG. 1a is an enlarged partial cross sectional view of the
support frame illustrated in FIG. 1.
[0016] FIG. 2 is a perspective view of the support frame of FIG. 1
deployed inside a body vessel.
[0017] FIG. 3 is a top view of a prosthetic venous valve according
to a first exemplary embodiment of the invention.
[0018] FIG. 4 is an enlarged partial view of the prosthetic venous
valve illustrated in FIG. 3.
[0019] FIG. 5 is a perspective view of a support frame for use in
medical devices according to the invention.
[0020] FIG. 6 is a perspective view of the support frame
illustrated in FIG. 5 in a radially compressed configuration.
[0021] FIG. 7 is a partial view of a contoured strut for use in a
medical device according to one embodiment of the invention.
[0022] FIG. 8 is a partial view of a contoured strut for use in a
medical device according to another embodiment of the
invention.
[0023] FIG. 9 is a partial view of a contoured strut for use in a
medical device according to another embodiment of the
invention.
[0024] FIG. 10 is a partial view of a contoured strut for use in a
medical device according to another embodiment of the
invention.
[0025] FIG. 11 is a partial view of a contoured strut having an
area of increased width for use in a medical device according to
another embodiment of the invention.
[0026] FIG. 12 is a partial view of a contoured strut defining
projections for use in a medical device according to another
embodiment of the invention.
[0027] FIG. 13 is a partial view of a support frame for use in a
medical device according to another embodiment of the
invention.
[0028] FIG. 14 is an enlarged partial view of the support frame
illustrated in FIG. 13.
[0029] FIG. 15 is a top view of a support frame for use in medical
devices according to another embodiment of the invention.
[0030] FIG. 16 is a perspective view of a medical device according
to the invention positioned within a body vessel.
[0031] FIG. 17 is a partial cross-sectional view taken along line
a-a in FIG. 16.
[0032] FIG. 18 is a schematic illustration of one configuration of
barbs on a strut according to an embodiment of the invention.
[0033] FIG. 19 is a schematic illustration of one configuration of
barbs on a strut according to another embodiment of the
invention.
[0034] FIG. 20 is a schematic illustration of one configuration of
barbs on a strut according to another embodiment of the
invention.
[0035] FIG. 21 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0036] FIG. 22a is a schematic illustration of the fabrication of
the medical device illustrated in FIG. 21.
[0037] FIG. 22b is a schematic illustration of the fabrication of
the medical device illustrated in FIG. 21.
[0038] FIG. 22c is a schematic illustration of the fabrication of
the medical device illustrated in FIG. 21.
[0039] FIG. 23 is a partial cross-sectional view of a medical
device according to an embodiment of the invention.
[0040] FIG. 24 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0041] FIG. 25 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0042] FIG. 26 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0043] FIG. 27 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0044] FIG. 28 is a partial cross-sectional view of a medical
device according to another embodiment of the invention.
[0045] FIG. 29 is a partial view of a medical device according to
another embodiment of the invention.
[0046] FIG. 30 is a top view of a medical device according to
another embodiment of the invention.
[0047] FIG. 31 is a partial view of a medical device according to
another embodiment of the invention.
[0048] FIG. 32 is an enlarged partial view of a medical device
according to another embodiment of the invention.
[0049] FIG. 33 is a partial view of a medical device according to
another embodiment of the invention.
[0050] FIG. 34 is a partial view of a medical device according to
another embodiment of the invention.
[0051] FIG. 35 is a partial view of a medical device according to
another embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0052] The following provides a detailed description of currently
exemplary embodiments of the invention. The description is not
intended to limit the invention in any manner, but rather serves to
enable those skilled in the art to make and use the invention.
[0053] A medical device according to the invention provides a
support frame with an attached graft member. Exemplary embodiments
of the invention provide a valve for regulating fluid flow through
a body vessel. Medical devices according to these embodiments
include a support frame and a graft member that imparts a valve
function to the device.
[0054] The support frame provides an attachment member for the
graft member. A wide variety of support frames are known in the
art, and any suitable support frame can be utilized. The support
frame can also provide a stenting function, i.e., exert a radially
outward force on the interior vessel wall, although this function
is not necessary and is considered optional. By including a support
frame having stenting properties, the medical devices of the
invention can provide both a stenting and a valving function at a
point of treatment.
[0055] The stent art provides numerous support frames acceptable
for use in the invention, and any suitable stent can be used. The
support frame need only provide the desired attachment member for
the graft member. The specific support frame chosen will depend on
numerous factors, including the vessel in which the device is being
implanted, the axial length of the treatment site, the number of
valves desired in the support frame, the inner diameter of the
vessel, the delivery method for placing the support frame and
valve, and others. Those skilled in the art can determine an
appropriate support frame based on these and other factors.
[0056] The support frame can be either self-expandable or balloon
expandable. A balloon expandable support frame may provide
advantage to treatment sites where greater radial strength is
desired. Self-expandable stents provide a relatively simple
deployment at the point of treatment. Suitable support frames can
also have a variety of configurations, including braided strands,
helically wound strands, ring members, consecutively attached ring
members, tube members, and frames cut from solid tubes.
[0057] Suitable support frames can be made from a variety of
materials, and need only be biocompatible, or able to be made
biocompatible, and provide the desired stenting function, if
appropriate. Examples of suitable materials include, without
limitation, stainless steel, nickel titanium (NiTi) alloys, e.g.,
nitinol, other shape memory and/or superelastic materials,
cobalt-chromium alloys, natural and synthetic polymers, and
composite materials. Examples of suitable polymeric materials
include polypropylenes and polyethylenes. A resorbable material can
also be use for the support frame. As used herein, the term
"resorbable" refers to the ability of a material to be absorbed
into a tissue and/or body fluid upon contact with the tissue and/or
body fluid. A number of resorbable materials are known in the art,
and any suitable resorbable material can be used. Examples of
suitable types of resorbable materials include resorbable
homopolymers, copolymers, or blends of resorbable polymers.
Specific examples of suitable resorbable materials include
poly-alpha hydroxy acids such as polylactic acid, polylactide,
polyglycolic acid (PGA), or polyglycolide; trimethlyene carbonate;
polycaprolactone; poly-beta hydroxy acids such as
polyhydroxybutyrate or polyhydroxyvalerate; or other polymers such
as polyphosphazines, polyorganophosphazines, polyanhydrides,
polyesteramides, polyorthoesters, polyethylene oxide,
polyester-ethers (e.g., polydioxanone) or polyamino acids (e.g.,
poly-L-glutamic acid or poly-L-lysine). There are also a number of
naturally derived resorbable polymers that may be suitable,
including modified polysaccharides, such as cellulose, chitin, and
dextran, and modified proteins, such as fibrin and casein.
[0058] Stainless steel and nitinol are currently considered
desirable materials for use in the support frame due at least to
their biocompatibility, shapeability, and well-characterized
nature.
[0059] Examples of suitable support frames for use in medical
devices according to the invention include those described in U.S.
Pat. No. 6,464,720 to Boatman et al. for a RADIALLY EXPANDABLE
STENT; U.S. Pat. No. 6,231,598 to Berry et al. for a RADIALLY
EXPANDABLE STENT; U.S. Pat. No. 6,299,635 to Frantzen for a
RADIALLY EXPANDABLE NON-AXIALLY CONTRACTING SURGICAL STENT; U.S.
Pat. No. 4,580,568 to Gianturco for a PERCUTANEOUS ENDOVASCULAR
STENT AND METHOD FOR INSERTION THEREOF; and published United States
patent application 2001/0039450 to Pavcnik et al. for an
IMPLANTABLE MEDICAL DEVICE, all of which are hereby incorporated by
reference in their entirety.
[0060] In some embodiments of the invention, a support frame formed
from wire is utilized. FIG. 1 illustrates a suitable wire support
frame 10 for use in a medical device according to the invention.
This support frame 10 is exemplary of suitable support frames that
can be modified to include the invention. Support frame 10 is
described in detail in U.S. Pat. No. 6,508,833 to Pavcnik et al.
for a MULTIPLE-SIDED INTRALUMINAL MEDICAL DEVICE, which is hereby
incorporated by reference in its entirety. The support frame 10 is
made of resilient material, preferably metal wire formed from
stainless steel or a superelastic alloy, such as nitinol. While
round wire is depicted in the figure, other wire types, e.g., flat,
square, triangular, D-shaped, delta-shaped, etc. may be used to
form the frame. In the illustrative embodiment, the frame 10
comprises a closed circumference of a single piece of material that
is formed into a device having a plurality of sides 12
interconnected by a series of bends 14, 16, 18, 20. The depicted
embodiment includes four sides 12 of approximately equal length.
Alternative embodiments include forming a frame into any polygonal
shape, for example, a pentagon, hexagon, octagon, etc. In the
embodiment of FIG. 1, each of the bends 14, 16, 18, 20
interconnecting the sides 13 comprise a coil 14 of approximately
one and a quarter turns. Alternative bend embodiments include
outward-projecting fillets and inward-projecting fillets comprising
a series of curves. Fillets are well known in the stent art as a
means to reduce stresses in bends. When using stainless steel wire,
the size of the wire which should be selected depends on the size
of device and the application. Wire that is too stiff can damage
the vessel, not conform well to the vessel wall, and increase the
profile of the device when loaded in the delivery system prior to
deployment.
[0061] The single piece of material comprising the frame 10 is
formed into the closed circumference by securing the first and
second ends 24, 26 with an attachment mechanism 28 such as a piece
of metal cannula (see FIG. 1A). The ends 24, 26 of the single piece
are inserted into the cannula 28 and secured with solder 30, a
weld, adhesive, or crimping to form the closed frame 10. The ends
24, 26 of the single piece can be joined directly without addition
of a cannula 28, such as by soldering, welding, or other methods to
join ends 24, 26. Besides joining the wire, the frame could be
fabricated as a single piece of material, by stamping or cutting
the frame 10 from another sheet (e.g., with a laser), fabricating
from a mold, or some similar method of producing a unitary
frame.
[0062] The support frame 10 depicted in FIG. 1 is shown in a first
configuration 25 whereby all four bends 14, 16, 18, 20 and each of
the sides 12 generally lie within a single flat plane. To
resiliently reshape the frame 10 into a second configuration 35,
shown in FIG. 2, the frame 10 of FIG. 1 is folded twice, first
along one diagonal axis 32 with opposite bends 16 and 20 being
brought into closer proximity, followed by opposite bends 14 and 18
being folded toward one another and brought into closer proximity.
The second configuration 35, depicted in FIG. 2, has two opposite
bends oriented at the first end 32 of the frame 10, while the other
opposite bends 16, 20 are oriented at the second end 34 of the
frame 10 and rotated approximately 90.degree. with respect to bends
14 and 18 when viewed in cross-section. The medical device in the
second configuration 35 can be used as a stent to maintain an open
lumen 36 in a vessel 38, such as a vein, artery, or duct. The
bending stresses introduced to the frame 10 by the first and second
folds required to form the second configuration 35 apply force
radially outward against the vessel wall 40 to hold the frame 10 in
place and prevent vessel closure. Absent any significant plastic
deformation occurring during folding and deployment, the second
configuration 35, when not in the vessel or subject to other
constraining means, will at least partially return to the first
configuration 25, although some deformation can occur depending on
the material used. It is also possible to plastically deform the
frame 10 into the second configuration 35, such that it does not
unfold when restraint is removed. This might be particularly
desired if the device is made from nitinol or a superelastic
alloy.
[0063] FIG. 3 illustrates a medical device 100 formed from a wire
support frame 110 configured into a diamond shape 112. A graft
member 114 is attached to the support frame 110 and has two
leaflets 116, 118 that define a central opening 120. The graft
member 114 is attached to the support frame 110 by attachment
elements 122. As used herein, the term "attachment element" refers
to any member that can be used to form a connection between a
support frame and a graft member. Examples of suitable attachment
elements include, without limitation, sutures, coils, wires, clips,
rings, and other suitable members. The attachment element can
comprise a separate member or can be integrally formed by the
support frame or graft member. The specific attachment element
chosen for a particular embodiment of the invention will depend on
various considerations, including the type and configuration of the
support frame and/or graft member.
[0064] Similar to the embodiment illustrated in FIGS. 1 and 2, the
support frame 110 illustrated in FIG. 3 includes bends 124, 126,
128 and 130 that each comprise a coil 132. The coil 132 provides an
eyelet configuration in the support frame 110. As such, the coil
132 defines a structural feature in the support frame 110 to which
the graft member 114 can be attached.
[0065] FIG. 4 illustrates a magnified view of a coil 132 in the
device 100 illustrated in FIG. 3. As illustrated in FIG. 4, the
graft member 114 has a notch area that receives the coil 132 and
allows for the placement of attachment elements 122 around the
portion of the support frame 110 in the coil 132 and through the
adjacent graft member 114. In this configuration, the coil 132
provides an additional attachment point for the graft member 114.
The graft member 114 is not able to migrate along the support frame
110 near the position of the coil 132 because the overlap region
134 blocks the attachment elements 122 from traveling along the
support frame 110. The overlap region 134 is a length along the
support frame 110 that includes at least two thicknesses of the
wire member that forms the support frame 110. To further prevent
migration in this area, the two portions of the support frame 110
that overlap in the overlap region 134 can be joined together by
various means, such as placement of an attachment element at the
overlapping portions.
[0066] FIGS. 5 and 6 illustrate a second type of support frame 210
suitable for use in medical devices according to the invention.
Support frame 210 is described in detail in U.S. Pat. No.
6,299,635, to Frantzen. The support frame 210 comprises a unitary
member cut from a solid piece of metal tubing, such as by laser
cutting. A variety of unitary support frames cut from tubes are
known to those skilled in the art. Any suitable support frame of
this type can be utilized in the invention. Generally, these
support frames, such as the support frame 210 illustrated in FIG.
5, include a plurality of struts 212 of the tube material left
after the cutting process. A plurality of open spaces 214 is formed
by the removal of the material between the struts 212.
[0067] A variety of configurations of the struts 212 and open
spaces 214 can be utilized. The configuration chosen will depend on
numerous factors, including the size of the vessel, the desired
radial strength of the stent, and the desired longitudinal
flexibility of the stent. Also, as will be described more fully
below, the struts 212 can be configured in a variety of manners in
accordance with the invention to provide the desired attachment of
the graft member to the support frame 210.
[0068] Similar to the support frame illustrated in FIGS. 1 and 2,
the support frame 210 has both a radially expanded and radially
compressed configuration. FIG. 6 illustrates the radially
compressed configuration of the support frame 210. As best
illustrated in FIG. 6, the open spaces 214 are reduced in size when
the support frame is in the radially compressed configuration.
Support frames cut from tube members, such as the frame 210
illustrated in FIGS. 5 and 6, are typically balloon expandable
support frames.
[0069] Medical devices according to the invention include a support
frame and a graft member. The graft member can be attached to the
support frame in a variety of configurations. Also, the support can
define structural features that are adapted to substantially
prevent movement of the graft member along the struts of the
support frame.
[0070] In a first series of embodiments of the invention, struts of
the support frame are contoured to provide at least one non-linear
segment across which a graft member can be attached. FIGS. 7
through 10 illustrate portions of medical devices in accordance
with this first series of embodiments.
[0071] FIG. 7 illustrates a portion of a medical device 300
according to an embodiment of the invention. In this embodiment, a
strut 310 defines a serpentine path 312 that includes a plurality
of non-linear segments 314. The serpentine path 312 is defined by a
single strut 310, and does not include any bend or other transition
to another strut. FIG. 35 illustrates an alternate embodiment in
which one strut 1800 defines a structural feature, such as enlarged
region 1802, that cooperates with one or more other struts 1804,
1806 to prevent migration of an attachment element 1808 that
attaches a graft member 1810 to the strut 1800. In the embodiment
illustrated in FIG. 7, the graft member 316 is secured to the strut
310 by two or more attachment elements 318 that surround a
circumference of the strut 310 and extend through the graft member
316. The graft member 316 is a sheet of material and an edge 317 of
the graft member 316 is in contact with a surface of the strut 310.
This contact can be an abutting relationship. As illustrated in the
FIG. 7, an attachment element 318 can be disposed on each side of a
non-linear segment 314 along the strut 310. In the illustrated
embodiment, a series of attachment elements 318 are secured to the
strut 310 and graft member 316 along a series of non-linear
segments 314 on the strut 310. In this configuration, the graft
member 316 is substantially prevented from migrating due to the
curvilinear path that would need to be traveled by the attachment
elements 318 for such migration to occur.
[0072] Any suitable graft member can be used in medical devices
according to the invention. The graft member can comprise any
suitable material for implantation in a body vessel. The graft
member need only be biocompatible or be able to be made
biocompatible. Examples of suitable materials for the graft member
include natural materials, synthetic materials, and combinations
thereof. Examples of suitable natural materials include ECMs, such
as small intestine submucosa (SIS), and other bioremodellable
materials, such as bovine pericardium. Other examples of ECM
materials that can be used for the graft member include stomach
submucosa, liver basement membrane, urinary bladder submucosa,
tissue mucosa, and dura mater. Examples of suitable synthetic
materials include polymeric materials, such as expanded
polytetrafluoroethylene and polyurethane. ECMs are particularly
well suited materials for use in the graft member, at least because
of their abilities to remodel and become incorporated into adjacent
tissues. These materials can provide a scaffold onto which cellular
in-growth can occur, eventually allowing the material to remodel
into a structure of host cells.
[0073] FIG. 8 illustrates a portion of medical device 400 according
to another embodiment of the invention. In this embodiment, the
strut 410 defines a plurality of angulated linear segments 412. The
attachment elements 414 are preferably disposed across these
angulated segments. Similar to the embodiment illustrated in FIG.
7, an edge 417 of the graft member 416 is in contact with a surface
of the strut 410. In this embodiment, the graft member 416 has one
or more folds 418 that are substantially coaxial with a portion of
the strut 410 and provide a point at which the graft member 416 can
be secured to the strut 410 by attachment element 414.
[0074] FIG. 9 illustrates a portion of a medical device 500
according to another embodiment of the invention. This embodiment
is similar to that illustrated in FIG. 8, except that the graft
member 516 does not include folds. Thus, the strut 510 includes a
plurality of angulated linear segments 512. A series of attachment
elements 514 secure the graft member 516 to the strut 510. Thus, as
illustrated in FIG. 9, the graft member 516 follows a substantially
linear path. Also, an edge 517 of the graft member is in contact
with a surface of the strut 510.
[0075] FIG. 10 illustrates a portion of a medical device 600
according to another embodiment of the invention. This embodiment
is similar to the embodiment illustrated in FIG. 7, except as
described below. The strut 610 includes linear portions 612
disposed between adjacent curvilinear segments 614. The linear
segment 612 provides an area for attachment of attachment elements
616 to the strut 610. As illustrated in FIG. 10, the curvilinear
portions 614 are disposed between two linear segments 612 and
provide a structural feature that substantially prevents sliding of
attachment elements 616 along the strut 610. An edge 617 of the
graft member 618 is in contact with a surface of the strut 610.
[0076] FIG. 11 illustrates a portion of a medical device 700
according to another embodiment of the invention. In this
embodiment, the strut 710 includes a portion 712 having an
increased width w2. The width w2 of the area 712 is greater than
the width w1 of at least one other portion of the strut 710. As
used herein, the term "width" refers to any dimension of a strut
other than length, and includes a width of a substantially two
dimensional strut, a thickness of a three dimensional strut, and a
diameter of a strut with a substantially circular cross-sectional
shape. As illustrated in FIG. 11, a portion 712 having an increased
width w2 is disposed between two portions 714 of a lesser width,
such as width w1. Attachment elements 716 are disposed around a
circumference of the strut 710 and through the graft member 718 at
a position on the strut between portions 712 and 714. The
attachment elements 716 are drawn tight to the circumference of the
strut 710 at these locations. Consequently, each attachment element
716 is substantially prevented from migrating towards an adjacent
portion 712 of increased width w2. When two attachment elements 716
are disposed on either side of portion 712 of increased width w2,
the prevention of migration is effective in both directions because
migration of one attachment element 716 towards an adjacent portion
714 of lesser width w1 necessarily involves migration of the other
attachment element 716 towards the portion of increased width w2,
which is prevented due to the taught nature of the connection
between the attachment element 716 and the strut 710. An edge 717
of the graft member 718 is in contact with a surface of the strut
710.
[0077] FIG. 12 illustrates a portion of a device 800 according to
another embodiment of the invention. In this embodiment, the strut
810 defines one or more projections 812. Attachment elements 814
are placed across a circumference of the strut 810 and through the
graft member 816, adjacent one or more projections 812. An edge 817
of the graft member 818 is in contact with a surface of the strut
710. The projections 812 define stops that prevent migration of the
attachment element 814 along the length of the strut 810. The
projections 812 can take a variety of forms, including the barb
like forms illustrated in FIG. 12, as well as bumps, nibs, and
rings. Furthermore, the projections 812 can be defined by the strut
810, or alternatively can comprise separate members attached to the
strut 810.
[0078] FIG. 12 illustrates three configurations of the projections
812 on the strut 810. For example, at the upper portion of FIG. 12,
the strut 810 includes a single projection 812. The attachment
element 814 is disposed adjacent the projection 812. In the middle
portion of FIG. 12, two projections 812 are placed on a single side
of the strut 810. An attachment element 814 is disposed between the
projections 812. This configuration effectively captures the
attachment element 814 between the projections 812. In the lower
portion of FIG. 12, two projections 812 are disposed on opposite
sides of the strut 810. The attachment element 814 is disposed
between the opposing projections 812. In this configuration, the
projections 812 define stops on each side of the attachment element
814. In medical devices according to the invention, a variety of
these configurations can be used either exclusively or in any
suitable combination with one another. Furthermore, as illustrated
in FIG. 12, attachment elements 814 can be disposed across the
strut 810 in areas that do not include any projections 812. The use
of one or several projections 812 along the length of the strut 810
substantially prevents migration of the graft member 816 along the
strut 810.
[0079] FIGS. 13 and 14 illustrate a support frame 900 suitable for
use in medical devices according to the invention. In this
embodiment, the support frame 900 defines one or more barbs 902
along its length. As illustrated in the enlarged partial view shown
in FIG. 14, the barbs 902 preferably comprise pointed members
extended away from the surface of the support frame 900. The
pointed configuration of the barb 902 allows for piercing through
an attached graft member. Each barb 902 can be formed from a
portion of the material of the support frame 900, as shown in FIG.
14, or can comprise a separately attached member.
[0080] As best illustrated in FIG. 13, the barbs 902 at a first end
906 of the support frame 900 can extend in a first direction, and
the barbs 902 at a second end 908 of the support frame 900 can
extend in a second direction. This configuration is particularly
well suited for support frames, such as the frame 900 illustrated
in FIG. 13, in which the two opposing ends are brought near each
other when the device is positioned within a vessel. When the two
ends are brought near each other, all barbs 902 extend in the same
direction, providing effective resistance to migration of an
attached graft member in the opposite direction.
[0081] In some applications, medical devices according to the
invention will be exposed to flow that occurs in both directions at
different times. For example, prosthetic venous valves are exposed
to both antigrade and retrograde flow continually over time. Thus,
it may be desirable to provide resistance to migration of an
attached graft member in both directions. FIG. 15 illustrates a
support frame 1000 that includes a variety of barbs extending from
its surface 1002. At a first end 1004 of the support frame 1000, a
first series of barbs 1006 extend in a first direction, and a
second series of barbs 1008 extend in a second, different
direction, which can be a substantially opposite direction.
Likewise, at a second end 1010 of the support frame, a first series
of barbs 1012 extend in a first direction and a second series of
barbs 1014 extend in a second, different direction. As discussed
above, all of the barbs preferably comprise pointed members
extending away from the surface of the support frame 1100.
[0082] The first series of barbs 1006 at the first end 1004 and the
first series of barbs 1012 at the second end 1010 resist migration
of an attached graft member 1016 in a first direction 1018, as
illustrated in FIG. 16, when the device is deployed in a vessel
1020. The second series of barbs 1008 at the first end 1004 and the
second series of barbs 1014 at the second end 1010 resist migration
of the graft member 1016 in a second, different direction 1024.
Thus, the support frame 1000 substantially prevents migration of
the graft member 1016 along the support frame 1000 in two different
directions.
[0083] FIG. 17 illustrates a cross-sectional view of a barb 1030
extending through the graft member 1016. By extending through the
graft member 1016, the barb 1030 substantially prevents migration
of the graft member 1016 along the support frame.
[0084] FIGS. 18 and 19 illustrate alternative configurations for
barbs on support frame 1000. In FIGS. 18 and 19, opposing barbs
1030, 1030' are arranged on one side of support frame 1000. These
configurations are particularly well-suited for use in medical
devices composed of flat stock or nearly flat material.
[0085] FIG. 20 illustrates an alternative embodiment for
positioning of the barbs on the support frame. In this embodiment,
barbs 1040, 1040' are positioned on different sides of the support
frame 1000. This is in contrast to the embodiments illustrated in
FIGS. 13-19 in which the barbs are positioned on a single side of
the support frame.
[0086] FIG. 21 illustrates a portion of a medical device 1100
according to another embodiment of the invention. In this
embodiment, the support frame 1102 defines a plurality of
projections 1104 that extend through the thickness of the graft
member 1106 and along a portion of a length of the graft member
1106. In this configuration, the projections 1104 provide
additional securement of the graft member 1106 to the frame by
effectively clamping the graft member 1106 to the frame 1102.
[0087] FIGS. 22a, 22b, and 22c provide schematic illustrations of a
fabrication process for the device 1100 illustrated in FIG. 21.
First, as illustrated in FIG. 22a, a support frame 1102 includes an
upstanding projection 1104. A section of graft material 1106
defining an opening 1108 is placed on the support frame 1102 such
that the upstanding projection 1104 is passed through the opening
1108. FIG. 22b illustrates the intermediate product in which the
graft member 1106 is positioned on the support frame 1102 and the
upstanding projection 1104 extends through the opening 1108. Next,
the upstanding projection 1104 is bent over a portion of the graft
member 1106 so that a portion of the projection 1104 extends along
a portion of a length of the graft member 1106. The graft member
1106 can be further secured to the support frame 1102 by clamping
or crimping the projection 1104 against the graft member 1106 and
support frame 1102, effectively capturing the graft member
1106.
[0088] FIGS. 23 through 27 illustrate portions of medical devices
according to embodiments of the invention. In these embodiments, a
strut 1200 defines one or more projections that define a stop for
an attachment element 1202. The projections of these embodiments
are similar to those illustrated in FIG. 12 and described above,
except as detailed below.
[0089] FIGS. 23 through 26 illustrate various projections that are
suitable for use when it is desirable to attach a graft member 1204
to a portion of a support frame in a manner that the graft member
1204 extends substantially coplanar with the strut 1200. Also, an
edge 1205 of the graft member 1204 is in contact with a surface of
the strut 1200. This contact can be an abutting relationship. In
FIG. 23, two projections 1206, 1208 surround a single attachment
element 1202. Each of the projections 1206, 1208 define an enlarged
region of the strut 1200 having a width w2 that is greater than a
width w1 of a non-enlarged region of the strut 1200. This
configuration essentially captures the attachment element 1202
between the enlarged regions 1206, 1208, thereby preventing
migration of the graft member 1204 along the strut 1200. FIG. 24
illustrates a first alternative configuration of projections 1206',
1208'. In this configuration, the cross-sectional shape of the
projections 1206', 1208' each comprise a substantially triangular
shaped region defined by the strut 1200. FIG. 25 illustrates
another alternative configuration of the projections 1206'',
1208''. In this embodiment, each of the barbs 1206'', 1208''
comprise a square or rectangular cross-sectional shaped area of the
strut 1200. The projections 1206'', 1208'' extend outward from at
least two sides of the strut 1200. In FIG. 26, the projections
1206''', 1208''' also comprise square or rectangular
cross-sectional shaped areas of the strut 1200. In this embodiment,
however, the enlarged regions 1206'', 1208'' extend outward from
only one side of the strut 1200. Each of these described
configurations may provide advantages in manufacturing of support
frames or in assembly of the device in which the graft member 1204
is secured to the strut 1200.
[0090] As described above, the embodiments illustrated in FIGS. 23
through 26 provide projections that are suitable for use when it is
desirable to extend the graft member coplanar with a strut. In some
devices, however, it may be desirable to extend the graft member at
an angle with respect to a strut. FIG. 27 illustrates a strut 1300
that defines a projection 1302 that is suitable for this purpose.
As illustrated in the figure, the projection 1302 comprises a first
region 1304 that extends away from one side of the strut 1300 in a
first direction, and a second region 1306 that extends away from a
second side of the strut 1300 in a second direction. As illustrated
in FIG. 27, the regions 1304, 1306 advantageously have triangular
cross-sectional shapes that are substantially opposite in
arrangement relative to one another. The attachment element 1308 is
disposed across the projection 1302 and through the graft member
1310. The projection 1302 formed by the regions 1304, 1306 allows
for placement of the attachment element 1308 at an angle to a
lengthwise axis of the strut 1300, thereby allowing the graft
member 1310 to be positioned at an angle with respect to the strut
1300. Also, an edge 1311 of the graft member 1310 is in contact
with a surface of the strut 1300, and can be in an abutting
relationship with the strut 1300. It is noted that a combination of
the various projections can be used in medical devices according to
the invention. For example, in a single medical device, it may be
desirable to have a graft extend coplanar with a strut in one
portion of the device, in which a projection such as those
illustrated in FIGS. 23 through 26 would be appropriate, while
having a graft member extend at an angle with respect to a strut in
another portion of the device, in which a projection, such as that
illustrated in FIG. 27, would be appropriate. A desirable number,
configuration, and placement of the various projections used can be
determined for a particular support frame in a medical device
according to the invention.
[0091] FIG. 28 illustrates a cross-sectional view of a portion of a
medical device 1400 according to another embodiment of the
invention. In this embodiment, a clip member 1402 is disposed
around the graft member 1404 to form a snug fit between the graft
member 1404 and strut 1406. The clip member 1402 is a suitable
attachment element for use in embodiments of the invention. The
clip member 1402 retains the graft member 1404 on the strut 1406 by
this snug fit. The clip member 1402 is preferably formed of a
resilient material and is force fit over the graft member 1404 and
strut 1406. The clip member 1402 can take a variety of
configurations. A C-shaped clip member 1402, such as that
illustrated in FIG. 28, provides an opening 1408 through which the
graft member 1404 and strut 1406 can be passed, while still
retaining the desired snug fit. Once the clip member 1402 is
positioned over the graft member 1404 and strut 1406, the clip
member 1402 retains the graft member 1404 adjacent the strut 1406
by the frictional engagement of the snug fit, preventing migration
of the graft member 1404 along the length of the strut 1406.
Multiple clip members 1402 can be arranged at various positions on
a medical device according to the invention. Also, various
configurations, such as various lengths, of clip members 1402 can
be used. The specific number and configuration of clip members 1402
used in any particular device will depend on various factors, such
as the size of the device and the desired degree of interference
fit between the strut 1406 and the graft member 1404.
[0092] To further enhance the connection between the graft member
1404 and strut 1406, additional securement means can be utilized in
conjunction with the clip member 1402, such as another attachment
element around a circumference of the strut 1406 and through the
graft member 1404, as well as other securement means such as an
adhesive disposed between the graft member 1404 and strut 1406.
[0093] Various configurations of attachment elements can be
utilized to attach the graft member to the support frame. For
example, FIGS. 29 through 31 illustrate various suitable
arrangements that utilize sutures as the attachment elements. It is
understood that other suitable attachment elements can be used in
these arrangements. In FIG. 29, two individual attachment elements
1502, 1504 are passed through the graft member 1506 and around
individual leg struts 1510, 1512. Also, each attachment element
1502, 1504 is tied around connecting strut 1514 that joins leg
struts 1510, 1512. The embodiment illustrated in FIG. 30 is
identical to that in FIG. 29, except that the attachment elements
are tied around a junction area 1516 of connecting strut 1514 and
the leg struts 1510, 1512. In FIG. 31, an embodiment identical to
that in FIG. 29 is illustrated, except that this embodiment uses a
single attachment element 1518, with portions 1520 and 1522. The
use of a single attachment element 1518 eliminates one knot in the
attachment element.
[0094] FIG. 32 illustrates a portion of a medical device 1600
according to an embodiment of the invention. In this embodiment,
strut 1602 defines an aperture 1604. An attachment element 1606 is
passed through the graft member 1608, around the leg struts 1616,
1612, and through the aperture 1606. This attachment element
arrangement in combination with the structural feature of the
aperture 1606 substantially prevents migration of the graft member
1608 along the leg struts 1610, 1612.
[0095] FIGS. 33 and 34 illustrate portions of a medical device 1700
according to another embodiment of the invention. In this
embodiment, the strut 1702 defines a barb that extends away from
the strut 1702. An attachment element 1708 secures the graft member
1706 to the strut 1702, and is passed behind the barb. The length y
of the barb prevents the attachment element 1708 from separating
from the barb as the length is greater than the slack present in
the attachment element 1708, and therefore no knot is needed at the
barb. The barb can comprise a member with one or more curvilinear
sides, such as barb 1704 illustrated in FIG. 33, or a member with
one or more linear sides, such as barb 1704' illustrated in FIG.
34. No matter the configuration, the barb advantageously includes a
point 1710, which allows the barb to also provide an anchoring
function to the device.
[0096] As indicated above, some medical devices, such as venous
valves, are exposed to fluid flow in two opposite directions once
implanted in a vessel. Accordingly, it may be necessary to include
features that resist migration of the graft member in the two
directions. A combination of one or more barbs disposed at one end
of a device and an attachment element configuration or other
feature described above can provide the desired resistance to
migration in two different directions.
[0097] The foregoing description includes the best mode for
practicing the invention. The description is intended only to aid
in the understanding of the invention, and is not intended to limit
the scope of the invention in any manner.
* * * * *