U.S. patent application number 13/839357 was filed with the patent office on 2013-10-17 for transcatheter stent-valves and methods, systems and devices for addressing para-valve leakage.
The applicant listed for this patent is SYMETIS SA. Invention is credited to Youssef Biadillah, Stephane Delaloye, Jacques Essinger, Jean-Luc Hefti, Fabien Lombardi, Luc Mantanus.
Application Number | 20130274873 13/839357 |
Document ID | / |
Family ID | 49325779 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130274873 |
Kind Code |
A1 |
Delaloye; Stephane ; et
al. |
October 17, 2013 |
Transcatheter Stent-Valves and Methods, Systems and Devices for
Addressing Para-Valve Leakage
Abstract
Some embodiments of the present disclosure provide a stent-valve
for transcatheter implantation to replace a cardiac valve. In some
embodiments, the stent valve being compressible to a compressed
state for delivery, and expandable to an operative state for
implantation. In some embodiments, the stent-valve comprises a
stent, a plurality of leaflets for defining a prosthetic valve, an
inner skirt, an outer skirt, and a paravalve seal for sealing
against surrounding tissue. In some embodiments, the paravalve seal
comprising material that swells in response to contact with blood
or components thereof.
Inventors: |
Delaloye; Stephane; (Bulach,
CH) ; Essinger; Jacques; (St-Prex, CH) ;
Hefti; Jean-Luc; (Cheseaux-Noreaz, CH) ; Biadillah;
Youssef; (Lausanne, CH) ; Mantanus; Luc;
(Lausanne, CH) ; Lombardi; Fabien; (Prilly,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SYMETIS SA |
Ecublens |
|
CH |
|
|
Family ID: |
49325779 |
Appl. No.: |
13/839357 |
Filed: |
March 15, 2013 |
Current U.S.
Class: |
623/2.18 |
Current CPC
Class: |
A61F 2250/0003 20130101;
A61F 2/2418 20130101; A61F 2/2469 20130101; A61F 2/2412 20130101;
A61F 2/2409 20130101; A61F 2210/0061 20130101; A61F 2250/0069
20130101; A61F 2220/0075 20130101 |
Class at
Publication: |
623/2.18 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2012 |
EP |
12002015.1 |
Claims
1. A stent-valve for transcatheter implantation to replace a
cardiac valve, the stent valve being compressible to a compressed
state for delivery, and expandable to an operative state for
implantation, the stent-valve comprising a stent, a plurality of
leaflets for defining a prosthetic valve, an inner skirt, an outer
skirt, and a paravalve seal for sealing against surrounding tissue,
the paravalve seal comprising material that swells in response to
contact with blood.
2. The stent-valve of claim 1, wherein at least one of the skirts
comprises the swellable material.
3. The stent-valve of claim 1, wherein the stent comprises at least
one of: a lower tubular portion; an upper crown portion; a
plurality of upstanding commissural supports; a plurality of
stabilization arches.
4. The stent-valve of claim 3, wherein the stent comprises the
lower tubular portion, the upper crown portion, the plurality of
upstanding commissural supports, and the plurality of stabilization
arches.
5. The stent-valve of claim 4, wherein the lower tubular portion
communicates with the upper crown and the commissural supports,
wherein the commissural supports upstand relative to the upper
crown portion, and wherein the stabilization arches communicate
with the commissural supports.
6. The stent-valve of claim 4, wherein the swellable material is
positioned between and spaced from respective extremities of both a
free edge of the upper crown, and a free edge of the lower tubular
portion.
7. The stent-valve of claim 4, wherein the lower tubular portion is
configured for deployment after at least partial deployment of the
upper crown portion, the commissural supports and the stabilization
arches.
8. The stent-valve of claim 1, wherein the outer skirt comprises
fabric comprising fibers of the swellable material.
9. The stent-valve of claim 1, wherein the swellable material is
captive within a containing chamber, the containing chamber carried
by the outer skirt.
10. A stent-valve for transcatheter implantation to replace a
cardiac valve, the stent valve being compressible to a compressed
state for delivery, and expandable to an operative state for
implantation, the stent-valve comprising a stent, a plurality of
leaflets for defining a prosthetic valve, and a paravalve seal for
sealing against surrounding tissue, the paravalve seal comprising
material that swells in response to contact with blood, the
paravalve seal being positioned towards one extremity of the stent,
and spaced from said one extremity.
11. The stent-valve of claim 10, wherein said one extremity of the
stent comprises a zig-zag edge, the zig-zag edge including first
apexes alternating with second apexes, wherein the paravalve seal
is positioned such that it does not extend in the region between
the apexes.
Description
RELATED APPLICATIONS
[0001] The present disclosure claims priority to European patent
application no. EP 12 002 015.1 filed, Mar. 22, 2012, the entire
disclosure of which is herein incorporated by reference.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to the field of transcatheter
stent-valves. In some embodiments, the stent-valve may be a cardiac
valve, for example, an aortic valve.
BACKGROUND
[0003] Transcatheter valve implantation (for example, transcatheter
aortic valve implantation (TAVI)) is an evolving technology for
replacement valve therapy that (i) avoids the trauma of
conventional open-chest surgery, and (ii) avoids the need for heart
and lung bypass. In such a technique, a stent-valve is compressed
and loaded into a delivery catheter. The delivery catheter is
introduced to the desired site of implantation (for example at the
heart) via a percutaneous route or via minimally invasive surgery.
The stent-valve is deployed into the implantation position from or
by the delivery catheter, and the delivery catheter is then
withdrawn.
[0004] Despite the successes of transcatheter stent-valves,
technological challenges remain. One such challenge is preventing
leakage of blood around the stent-valve (so called para-valve
leakage). The above stents form a friction fit with the native
anatomy to anchor the stent-valve in position, and are round in
cross-section. However, the native anatomy in which the stent is
implanted is often off-round and is different for each person.
Moreover, heavy calcification of the native anatomy may obstruct
full depolyment of any stent, and make the native anatomy even more
irregular. It can sometimes be difficult to provide a perfectly
sealing fit between the stent-valve and the surrounding
anatomy.
[0005] In order to address para-valve leakage, it is known to
incorporate an external skirt or cover as part of the stent-valve.
For example, the skirt is made of compressible biocompatible
material, such as pericardial tissue or PET. The thicker the
material of the skirt, the more able the skirt is to occlude gaps
and effect a seal. However, a disadvantage is that such skirts add
to the bulk of the stent-valve. A thick skirt makes the stent-valve
problematic to compress to a desirably small size for
implantation.
[0006] It would be desirable to provide a technique for mitigating
para-valve leakage without substantially hindering the
compressibility of a stent-valve.
SUMMARY OF THE DISCLOSURE
[0007] In some embodiments of the present disclosure, a stent-valve
for transcatheter delivery is provided, with the stent-valve
comprising a stent supporting a plurality of valve leaflets.
[0008] In some embodiments, a seal for mitigating para-valve
leakage (which may be referred herein throughout either as "seal"
or "para-valve leakage seal") is provided. The seal may be of
flexible and/or compliant material.
[0009] In some embodiments, the seal is carried by at least one
seal support. The seal support may be collapsible to a stowed
condition in which the seal is relatively streamlined or compressed
with respect to the stent when the stent is compressed. For
example, in the stowed condition, the seal support may be generally
coplanar with the body of the stent, or may be arranged compressed
against the stent. The seal support may be deployable to a deployed
condition in which the support holds or biases the seal to a
deployed state with respect to the stent. The seal support may be
self-deploying from the stowed condition to the deployed condition.
For example, the seal support may be constrainable in the stowed
condition by sheathing of the stent in a compressed state for
delivery. The seal support may be self-deploying from the stored
state when the effect of the constraining sheath is removed. The
seal support may be of shape memory material, for example,
nitinol.
[0010] Various forms and structure of seal support are envisaged.
In some embodiments, the seal support may be integral with the
stent (e.g. integrally formed as part of the stent). In other
forms, the seal support may be distinct from the stent. Such a seal
support may optionally be coupled to or captive on the stent.
[0011] The seal support may be configured to bear against the
material of the seal without penetrating through the seal material.
For example, the seal support may have a shape that distributes
contact force. A function of the seal support may be to urge the
seal outwardly without the seal support penetrating through the
seal material or into a tissue surface against which the seal is
desired.
[0012] In some embodiments, the seal support may comprise a biasing
element that biases the seal to a deployed condition (for example).
The seal support (e.g. biasing element) may comprise, for example,
a cantilever element (or a plurality of cantilever elements). The
cantilever elements may be capable of flexing independently of one
another, in order to provide a high degree of local seal conformity
against an irregular lumen or tissue surface. In some embodiments,
each cantilever element is associated with a respective aperture of
a lattice structure of the stent. The cantilever elements may, for
example, have one end coupled (or integral) with the stent body,
and an opposite or remote end that is free to deploy outwardly. The
remote end may have a rounded or enlarged or pad tip to avoid
having a sharp end that might otherwise risk penetrating through
the seal material. The cantilever elements may extend generally in
the same direction as each other (e.g. having the remote end
directed to one end (such as the outflow end) of the stent-valve),
or the cantilever elements may be arranged in two opposite
directions (e.g. at least one pointing towards the outflow end, and
at least another pointing towards the inflow end), or the
cantilever elements may be arranged in a variety of different
directions.
[0013] In some embodiments, the seal support comprises a ring
shape, or tubular shape, or annular member. The member may have an
annular coil shape.
[0014] In some embodiments, the seal support comprises a member
that can be stowed in a generally elongate or helical form, and
which deploys to a radially expanded loop form.
[0015] In some embodiments, the seal support comprises a portion of
the stent that everts from a stowed condition to a deployed
condition. Eversion of the stent can provide radial expansion upon
deployment without increasing significantly the diameter of the
stent when compressed (de-everted). For example, an inflow end or
portion of the stent may evert towards the outflow end.
[0016] In some embodiments, the stent carries a sealing skirt (or
web). The seal support may bias the skirt (or portions thereof)
radially outwardly to distend away from the body of the stent.
[0017] Additionally or alternatively to embodiments noted above for
a seal support, a seal of the stent-valve may be configured to be
responsive to direction of blood flow past the seal, relative to
inflow and outflow ends of the stent-valve. The seal may be
configured such that blood flow in a reverse direction (for outflow
to inflow) biases the seal to a deployed state to obstruct such
flow.
[0018] For example, in some embodiments, the seal may comprise at
least one web defining one or more pockets. The one or more pockets
may be configured to fill with blood (or blood components) in
response to blood flow in the reverse direction, such that the
pocket distends outwardly. Distention of the pocket can fill a gap
between the stent-valve and the surrounding anatomy, to obstruct
the reverse flow of blood past the pocket.
[0019] In some embodiments, the pocket may be defined or carried at
a respective aperture of a lattice structure of the stent. The
pocket may be defined at least partly by an outer skirt carried on
an exterior of the stent. Additionally or alternatively, the pocket
may be defined at least partly by an inner skirt carried on an
interior of the stent.
[0020] Additionally or alternatively to the above embodiments, a
seal may comprise a skirt at least a portion of which is captive
with respect to the stent, and at least a further portion of which
is free to deploy or float relative to the stent.
[0021] In some embodiments, the further portion may contact a
surrounding tissue or lumen wall before the body of the stent is
fully deployed. As part of the deployment procedure, the stent may
be displaced or biased in a first axial direction to seat against
native leaflets. The frictional contact of the skirt against the
tissue may cause the further portion of the skirt to bunch or
wrinkle in the axial direction during the displacement action. Such
bunching or wrinkling may provide additional material to fill voids
or gaps between the stent and the surrounding tissue.
[0022] Additionally or alternatively, in some embodiments, the
further portion of the skirt may seal may be responsive to
direction or paravalve blood flow or to pressure blood. The further
portion may, for example, deploy outwardly to contact a surrounding
tissue lumen wall. The further portion may form a generally channel
shape in response to pressure of blood or flow of blood in the
reverse direction. The channel shape may bias an outer portion of
the skirt to seat against the surrounding tissue or lumen
surface.
[0023] Additionally or alternatively to the above embodiments, a
seal of the stent-valve may be embossed to present a non-smooth
surface. For example, the embossing may be defined by one or more
sutures. The one or more sutures may define a zig-zag pattern. The
suture may define a generally continuous embossment to obstruct
blood flow past the stent.
[0024] Additionally or alternatively to the above embodiments, a
seal of the stent-valve may be generally oversized compared to the
diameter of the stent. The seal may be bunched or pleated by
connections (e.g. suturing) to the stent that causes bunching or
pleating between the connections. The bunching/pleating may create
additional compliant bulk of seal material able to fill voids or
gaps between the stent-valve and the surrounding tissue or lumen
surface. The positions of the connections may define bunching or
pleating in directions in a pattern that obstructs leakage of
blood.
[0025] Additionally or alternatively to the above embodiments, a
seal of the stent-valve may be configured to be self-expanding or
self-filling due to a physical property of the seal.
[0026] For example, in some embodiments, the seal may be of or
comprise a foam, sponge or fibrous material. Such a material may
self-expand resiliently when the stent deploys. Additionally or
alternatively, such a material may absorb blood (and/or components
thereof) within its pores or interstices in order to expand the
material physically or add bulk.
[0027] In some embodiments, the seal may be generally flat and/or
tubular in a stowed state, and may roll or curl into an annular
bead or doughnut when in a deployed state. The seal may be
self-biased to the deployed state, but be resiliently deformable to
the stowed state during compression of the stent for loading into a
delivery apparatus. Upon removal of a constraining effect of a
sheath of the delivery apparatus, the seal may be configured to
readopt the deployed state, in order to provide a radially enlarged
seal around the stent.
[0028] In some embodiments, at least a portion of the stent
comprises a lattice structure, and the stent-valve further
comprises one or more seals deployable from or through apertures of
the lattice. In one form, the seals comprise web portions of
material that define pockets associated with respective apertures
of the lattice. The web portions may be configured to distend
outwardly from the respective apertures. For example, in some
embodiments, the web portions define pockets open on or to one side
such that a respective pocket fills with blood to distend outwardly
from the aperture of the lattice. Additionally or alternatively,
the lattice structure of the stent may comprise biasing elements
for biasing the web portions (e.g. pockets) of material radially
outwardly from the lattice structure.
[0029] In some embodiments, the stent carries a sealing skirt (or
web). The stent may comprise biasing elements for biasing the skirt
(or portions thereof) radially outwardly to distend away from the
body of the stent. The sealing skirt may optionally be carried on
the exterior of the stent. An inner skirt (or web) may optionally
be carried on the interior of the stent (and optionally coupled
directly to the leaflets). At least one of the skirts may be of
fabric (e.g. PET). Additionally or alternatively, at least one of
the skirts may be of biological tissue, for example,
pericardium.
[0030] In some embodiments, a biasing element distinct from the
stent may bias a seal outwardly. For example, the biasing element
may be a ring element (e.g. closed ring or split ring), within an
annular seal. The biasing element may be compressible with the
stent to a radially compressed condition. The biasing element may
expand (e.g. self-expand) towards a radially expanded state when
the stent is deployed. The biasing element may be of shape memory
material, e.g. nitinol.
[0031] Certain features, ideas and advantages of the embodiments
taught by the present disclosure are identified above and/or in the
appended claims, but these do not limit any embodiment or invention
disclosed herein. Protection is claimed for any novel idea or
feature described herein and/or illustrated in the drawings whether
to not emphasis has been placed thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Non-limiting embodiments of the disclosure are illustrated
in the accompanying drawings, in which:
[0033] FIG. 1 is a schematic drawing illustrating a stent-valve 10,
according to some embodiments of the disclosure.
[0034] FIG. 2a is a front view of a seal arrangement with
cantilevered seal supports, and FIG. 2b is a side view of FIG. 2a
in a deployed configuration, each according to some embodiments of
the disclosure.
[0035] FIG. 3 is a schematic view of a seal arrangement with an
annular wire seal support according to some embodiments of the
disclosure.
[0036] FIG. 4a is a schematic perspective view of an elongate seal
support around the stent in a compressed state, and FIG. 4b is a
schematic top view of the seal when in a deployed state, each
according to some embodiments of the disclosure.
[0037] FIG. 5a is a schematic view of a seal arrangement in a
sheathed non-everted state, FIG. 5b shows initial unsheathing of
the seal arrangement of FIG. 5a to permit everting, and FIG. 5c
shows the seal arrangement of FIG. 5a when unsheathed, each
according to some embodiments of the disclosure.
[0038] FIG. 6 is a schematic side view of a further example of seal
arrangement with flexible cantilever arms, according to some
embodiments of the disclosure.
[0039] FIG. 7a is a schematic side view of a seal arrangement
comprising a rollable cuff when in a deployed state, and FIG. 7b is
a schematic view of the seal arrangement when in a stowed, sheathed
state, each according to some embodiments of the disclosure.
[0040] FIG. 8 is a schematic side view of a seal arrangement
comprising a porous material, according to some embodiments of the
disclosure.
[0041] FIG. 9a is a schematic side view of a seal arrangement
comprising a floating skirt, and
[0042] FIG. 9b is a schematic side view of the effect of the seal
arrangement of FIG. 9a when implanted, according to some
embodiments of the disclosure.
[0043] FIG. 10 is a schematic illustration of an alternative
arrangement of a floating skirt seal, according to some embodiments
of the disclosure.
[0044] FIG. 11 is a schematic illustration of an alternative seal
arrangement using a plated skirt, according to some embodiments of
the disclosure.
[0045] FIG. 12 is a schematic illustration of an alternative seal
arrangement using a folded skirt, according to some embodiments of
the disclosure.
[0046] FIG. 13 is a schematic illustration of an alternative seal
arrangement using distensible pockets, according to some
embodiments of the disclosure.
[0047] FIG. 14 is a schematic drawing of an alternative sealing
arrangement using swellable material, according to some embodiments
of the disclosure.
[0048] FIG. 15 is a schematic drawing illustrating administration
of a sealant around the stent-valve, according to some embodiments
of the disclosure.
[0049] FIG. 16 is a schematic view of an alternative sealing
arrangement using coagulation material, according to some
embodiments of the disclosure.
[0050] FIG. 17 is a schematic view of an alternative sealing
arrangement using material that elutes calcium locally, according
to some embodiments of the disclosure.
[0051] FIG. 18 is a partial schematic view of optional details of a
stent-valve of FIG. 1, according to some embodiments of the
disclosure.
[0052] FIG. 19 is a schematic section of the paravalve seal of FIG.
18, according to some embodiments of the disclosure.
DETAILED DESCRIPTION
[0053] Referring to FIG. 1 (and FIG. 18), a cardiac stent-valve 10
is illustrated for transcatheter implantation. The stent-valve 10
may be cardiac stent-valve, for example, an aortic stent-valve, a
mitral stent-valve, a pulmonary stent-valve or a tricuspid
stent-valve, for implantation at the respective valve position in a
human heart.
[0054] The stent-valve 10 may optionally comprise biological tissue
(for example, pericardium (such as porcine pericardium and/or
bovine pericardium) and/or natural cardiac valve leaflets (for
example, natural porcine cardiac valve leaflets, optionally
attached to a portion of natural cardiac wall tissue). The
biological tissue may be fixed, for example, using
glutaraldehyde.
[0055] The stent-valve 10 may be compressible to a radially
compressed condition (not shown) for delivery using a delivery
catheter, and be expandable to an expanded condition (as shown) at
implantation. The stent-valve 10 may comprise a stent 12 carrying a
plurality of leaflets defining a valve 14. Various geometries of
stent 12 may be used. In some embodiments, the stent 12 may include
one of more of: a lower tubular or crown portion 16; an upper crown
portion 18; a plurality of upstanding commissural supports 20; and
a plurality of stabilization arches 22. In use, the lower portion
16 of the stent 12 may be configured to be deployed after the other
regions of the stent 12 have first been at least partly deployed.
For example, the arches 22, the supports 20 and the upper crown 18
may be deployed at least partly before the lower portion 16 (in
that order, or in reverse order, or in a different order). At least
once the upper crown 18 has been at least partly deployed, the
stent 12 may be urged and/or displaced in the direction of arrow 24
to seat the upper crown 18 against native leaflets at the
implantation site. Deploying the lower portion 16 last fixes the
stent 12 in its final position.
[0056] At least the lower portion 16, and optionally a portion of
the upper crown 18, may be formed by a lattice structure of the
stent. The lattice structure may define apertures, for example,
generally diamond-shaped apertures.
[0057] The native leaflets may generally overlap a portion 26 of
the stent. The native valve annulus may overlap a portion 28 of the
stent.
[0058] Optionally, the stent-valve 10 may further comprise an inner
skirt 30 communicating with the leaflets 14 and carried on an
interior of the stent 12. Additionally or alternatively, the
stent-valve 10 may further comprise an outer skirt 32 carried on an
exterior of the stent 12. When both skirts are provided, the skirts
may partially overlap. The skirts may be offset such that one skirt
(e.g. the outer skirt 32) extends further towards a lower extremity
of the stent 12 than the other (e.g. inner skirt 30). Additionally
or alternatively, one skirt (e.g. the inner skirt 30) extends
further towards an upper extremity of the stent 12 than the other
(e.g. outer skirt 32). The skirts may be of any suitable flexible
and/or compliant material, for example, fabric (e.g. of PET), or of
plastics film (e.g. of PET), or of biological tissue (e.g. of
pericardium).
[0059] Optionally, at least the outer skirt 32 is positioned to
leave the upper crown 18 substantially un-obscured by the outer
skirt 32. Such an arrangement may assist good blood flow to the
coronary arteries (for example, in the case of a stent-valve for
the aortic valve).
[0060] In some embodiments, the lower portion 16 has an extremity
formed with a substantially zig-zag shape. The zig-zag shape may
comprise lower apexes 16a and upper apexes 16b. The upper apexes
16b may be masked in FIG. 1 by the superimposed presentation of
both the front most and rearmost cells of the lattice structure.
The zig-zag shape may be substantially continuous around the
circumference of the stent 12. The outer skirt 32 may have a
peripheral edge having a zig-zag shape that matches substantially
the zig-zag shape of the extremity of the lower portion 16. Such an
arrangement can avoid excessive material at the extremity, and
thereby facilitate crimping of the stent-valve 10. At the same
time, the outer skirt 32 covers (for example, complete) open cells
of the lattice structure down to the stent extremity to reduce risk
of blood leakage through the apertures of the cells. The outer
skirt 32 can also provide a layer of material over the struts of
the stent, thereby to cushion the engagement between the stent and
the sensitive native heart tissue.
[0061] The valve 14 may comprise biological tissue, for example,
pericardium (such as porcine pericardium or bovine pericardium) or
natural cardiac valve leaflets (for example, natural porcine
cardiac valve leaflets, optionally attached to a portion of natural
cardiac wall tissue). Other biological or non-biological material
could also be used for the valve 14, as desired.
[0062] The stent 12 may optionally be of a self-expanding type that
is compressible to the compressed state for loading into a delivery
catheter having a sheath for constraining the stent 12 in the
compressed state for delivery to the site of implantation. In use,
by removal of the constraining effect of the sheath, the stent 12
self-expands to or towards the expanded state. A self-expanding
stent may, for example, me of shape-memory material, for example,
shape-memory metal alloy, for example, nitinol. Alternatively, the
stent 12 may be configured to be expanded by application of an
expanding force from the delivery catheter, such as by using an
expansion balloon.
[0063] There now follows a description of various seal
configurations that may be used with the above-described
stent-valve 10. The seal configurations may also be used with
different stent shapes and configurations.
[0064] FIG. 2 illustrates a first example of seal support in the
form of a plurality cantilever elements 40 mounted on or integral
with the stent 12. Each cantilever element 40 may be associated
with a respective aperture 42 of the lattice structure. Each
cantilever element 40 may be bendable generally independently of
the others. Each cantilever element 40 may be movable between a
stowed condition, in which the cantilever element is generally
co-planar with the portion of the stent 12 around the aperture 42
(or at least is compressed to lie directly or indirectly there
against), and a deployed condition in which the cantilever element
40 is biased radially outwardly from the body (e.g. lower portion
16) of the stent 12 (FIG. 2b). The seal support urges a seal (e.g.
the outer skirt 32) outwardly so as to fill gaps or voids between
the stent-valve 10 and the surrounding lumen/tissue. The ability of
the cantilever elements 40 to flex independently can provide a high
degree of local conformity. Each cantilever element 40 may have a
remote end 40a in the form of a rounded, or pad-like, or other
non-damaging shape that can bear against the seal material to bias
the seal radially outwardly, without penetrating through, or
puncturing, the seal material.
[0065] The cantilever elements 40 may be arranged generally in the
same orientation (e.g. with the remote ends 40a directed towards
one end, e.g. the outlet end, of the stent 12), or distributed to
be orientated in two opposite directions, or be distributed to be
orientated in a variety of different directions.
[0066] The seal urged by the cantilever elements 40 may be
generally continuous, or it may be discontinuous in the form of
webs or pockets. The pockets may be arranged such that
back-pressure of blood, or para-valvular blood flow in the reverse
direction from outlet to inlet end of the stent 12, fills the
pockets to cause the pockets further to distend, thereby enhancing
the seal effect to obstruct such para-valvular flow. Further detail
of such pockets is also described with reference to FIG. 13, and
any of such features may also be used with the present example.
[0067] Referring to FIG. 3, a seal support 46 is illustrated in the
form of an annular wire or ring that is oversize compared to the
stent 10. The annular wire is compressible to a stowed state when
the stent is compressed, and expands to a deployed state when
unconstrained, to urge the seal 48 to a radially expanded state to
form a seal against the surrounding tissue/lumen.
[0068] Referring to FIG. 4, a seal support 50 is illustrated in the
form of an elongate member carrying a seal 52. The seal support is
compressible to a stowed form (FIG. 4a) for example a helical shape
around the stent 12 when in its compressed state. The seal support
is expandable to a deployed state (FIG. 4b), for example, a
radially expanded closed or semi-closed loop form in which the seal
support presents the seal 52 in expanded form around the stent
12.
[0069] Referring to FIG. 5, a seal support 54 is illustrated in the
form of an everting portion of the lower region 16 of the stent 12.
The seal support 54 is movable between a stowed, non-everted
configuration and a deployed, everted configuration. In a
compressed form constrained by a sheath 56 (FIG. 5a), the lower
portion of the stent including the seal support 54 is generally
tubular (non-everted). As the sheath 56 is progressively removed
axially (FIG. 5b), the seal support 56 is unsheathed.
Unconstrained, the seal support 56 everts to its deployed state in
which the seal is presented and/or biased radially outwardly from
the stent body. Further unsheathing of the stent 12 or the lower
portion 16 (FIG. 5c) permits the stent 12 to expand to its expanded
state. The everted seal support 54 urges the seal into tight
sealing contact with the surrounding tissue/lumen. The seal may be
carried on the inners surface of the stent when compressed, and
presented in an outward direction when everted.
[0070] FIG. 6 illustrates a seal support that is similar to both
FIGS. 2 and 5. The seal support 58 comprises flexible cantilever
elements at the lower portion 16 of the stent 12, similar to those
of FIG. 2 The seal support 58 also resembles the everted state of
the seal support 56 of FIG. 5. In the example of FIG. 6, the
cantilever elements do not move between an everted and non-everted
state. In the stowed state, the cantilever elements are generally
flat against or within the structure of the stent 12 (similar to
FIG. 2).
[0071] FIG. 7 illustrates a seal in the form of a rollable bead or
cuff 60. The rollable cuff 60 may be self-biased or it may be
supported by a seal support frame that tends to roll the cuff 60.
In a stowed state (FIG. 7b), the cuff is unrolled to define a
generally flat tubular form. The cuff may be constrained in the
stowed state by a constraining sheath 62 of a delivery device. When
unsheathed, the cuff 60 is free to move to its deployed state (FIG.
7a) in which the cuff 60 rolls up to define a cuff or bead shape.
Such a seal provides a compliant bead of material to fill any gap
between the stent 12 and the surrounding tissue/lumen.
[0072] FIG. 8 illustrates a seal 74 in the form of foam, or sponge
or fibrous porous material. Such material is compressible when dry,
because air is easily expelled from the pores and/or interstices of
material when compressed. The seal 74 may therefore adopt a
compressed state without increasing the bulk of the stent-valve 10
significantly. Once implanted, blood may penetrate and fill the
pores and/or interstices of the seal material. The blood may become
trapped in the pores and/or interstices, thereby creating a barrier
to blood flow through the material. The blood may also cause
distension of the seal material to further expand the seal
outwardly and fill any gaps of voids around the stent-valve 10.
[0073] FIG. 9 illustrates a seal in the form of a flexible skirt
80. The skirt 80 depends, for example, from the junction between
the upper crown 18 and the lower portion 16 of the stent 16, to at
least partly overlap the lower portion 16. A first (e.g. upper)
portion 82 of the skirt 80 is coupled to the stent 12, to hold the
skirt 80 captive. For example, the first portion 82 may be sutured
to the stent 12. A second (e.g. depending) portion 84 of the skirt
80 is generally unconstrained, and is free to float relative to the
stent 12.
[0074] As illustrated in FIG. 9b (and explained above in relation
to FIG. 1), the implantation procedure for the stent-valve 10 may
involve displacing the stent-valve in the direction of arrow 24 to
seat the upper crown 18 against native valve leaflets. The friction
between the floating second portion 84 of the skirt 80, and the
surrounding tissue/lumen may cause the second portion 84 to bunch
or wrinkle axially, thus creating an excess of material that is
able to seal any gap between the stent-valve 10 and the surrounding
tissue/lumen.
[0075] FIG. 10 illustrates an alternative seal in the form of a
flexible skirt 90. In contrast to the skirt of FIG. 9, the skirt 90
projects from the upper crown 18 towards the upper end of the stent
12. As indicated in phantom, under back pressure of blood, or
reverse flow of blow around the stent-valve 10, the flexible skirt
bears outwardly to seal against the surrounding tissue/lumen. The
flexible skirt may form a channel shape section such that the back
pressure of blood increases the sealing pressure against the
surrounding tissue/lumen.
[0076] FIG. 11 illustrates an alternative seal in the form of an
oversized flexible skirt 100 that is connected to the stent 12 at
one or more positions to define pleating or bunching. The
connections may be by suturing. The pleating or bunching creates
additional compliant material able to fill vids of gaps between the
stent 12 and the surrounding tissue/lumen.
[0077] FIG. 12 illustrates an alternative seal in the form of a
skirt that is folded to define a cuff 102. The skirt material is
flexible, but the fold creates a radiused bend providing a natural
bulge. The bulge biases the seal material outwardly in order to
fill voids or gaps between the stent 12 and the surrounding
tissue/lumen.
[0078] FIG. 13 illustrates an alternative seal comprising a
plurality of flexible pockets 110. Each pocket may be associated
with a respective aperture 112 of a lattice structure of the stent,
for example, the lower portion 16 and/or the upper crown 18. The
pocket 110 may be defined by a flexible web of material. One wall
of the pocket may be define by a portion of the outer skirt.
Another wall of the pocket may be defined by a portion of the inner
skirt. The pocket may be open on one side facing towards the outlet
end of the stent, and closed in the opposite direction. In a stowed
state, the pocket may collapse or fold substantially flat so as not
to increase the bulk of the stent-valve. Once deployed, the pocket
may open either under the influence of natural resilience, or under
the influence of blood back pressure entering the mouth of the
pocket. The back pressure causes the pocket to distend outwardly
against surrounding tissue/lumen, and thereby further obstructing
leakage of blood around the outside of the stent-valve 10.
[0079] FIG. 14 illustrates an alternative seal arrangement
comprising material 120 that swells in response to contact with
blood. The swelling characteristics increase the bulk of the seal,
enabling the seal to distend to fill any gaps between the
stent-valve 10 and the surrounding tissue/lumen. Example swellable
materials include a hydrogel and/or a liquid swellable polymer,
and/or a so called superabsorbent material. The material may, for
example, be carried by, or impregnated or otherwise embodied within
the outer skirt. For example, the skirt may be of fabric comprising
fibers of the swellable material. The material may be captive
within a containing chamber, for example a flexible and/or
distensible pouch or cuff. The combination of inner and outer
skirts, with one comprising swellable material, can provide an
especially effective seal arrangement. Further background
information of use of, for example, a hydrogel for stent-valves may
be found in US 2005/137688.
[0080] The seal of FIG. 14 is also illustrated in other embodiments
of FIGS. 18 and 19. The swellable material is denoted by numeral
44, the containing chamber 42, together defining the paravalve seal
40 carried by, or comprised within, the outer skirt 32.
[0081] FIG. 15 illustrates an alternative seal arrangement in which
a sealant 122 is dispensed from the delivery catheter 124 (or from
a further delivery catheter inserted after implantation), in order
to seal around the periphery of the stent valve 10. For example,
the sealant is dispensed on the outflow side of the stent-valve to
seal any gaps between the upper crown and the native leaflets.
[0082] FIG. 16 illustrates an alternative seal arrangement
comprising material 124 that provides hemostatic and/or coagulant
effects in response to contact with blood. The material 124 may,
for example, be carried by, or impregnated or otherwise embodied
within the outer skirt. The material may be captive within a
containing chamber, for example a flexible and/or distensible pouch
or cuff. The combination of inner and outer skirts, with one
comprising such material, can provide an especially effective seal
arrangement.
[0083] FIG. 17 illustrates an alternative seal arrangement
comprising material 126 that elutes calcium locally. The calcium
may deposit directly or indirectly against the surrounding
tissue/lumen such that any gaps can be occluded. The material 126
may, for example, be carried by, or impregnated or otherwise
embodied within the outer skirt. The material may be captive within
a containing chamber, for example a flexible and/or distensible
pouch or cuff. The combination of inner and outer skirts, with one
comprising such material, can provide an especially effective seal
arrangement.
[0084] Although the seal arrangements have been described as
alternatives, it is envisaged that any two or more of the seal
arrangements may be combined for synergistic effect.
[0085] Any and all references to publications or other documents,
including but not limited to, patents, patent applications,
articles, webpages, books, etc., presented in the present
application, are herein incorporated by reference in their
entirety.
[0086] Although a few variations of the disclosed subject matter
have been described in detail above, other modifications are
possible. For example, any logic flow depicted in the accompanying
figures and/or described herein does not require the particular
order shown, or sequential order, to achieve desirable results.
Other implementations may be within the scope of at least some of
the following exemplary claims.
[0087] Example embodiments of the devices, systems and methods have
been described herein. As noted elsewhere, these embodiments have
been described for illustrative purposes only and are not limiting.
Other embodiments are possible and are covered by the disclosure,
which will be apparent from the teachings contained herein. Thus,
the breadth and scope of the disclosure should not be limited by
any of the above-described embodiments but should be defined only
in accordance with claims supported by the present disclosure and
their equivalents. Moreover, embodiments of the subject disclosure
may include methods, systems and devices which may further include
any and all elements from any other disclosed methods, systems, and
devices, including any and all elements corresponding to
stent-valves, and/or seals for stent-valves. In other words,
elements from one or another disclosed embodiments may be
interchangeable with elements from other disclosed embodiments. In
addition, one or more features/elements of disclosed embodiments
may be removed and still result in patentable subject matter (and
thus, resulting in yet more embodiments of the subject
disclosure).
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