U.S. patent application number 15/494239 was filed with the patent office on 2017-10-05 for spacer for securing a transcatheter valve to a bioprosthetic cardiac structure.
The applicant listed for this patent is Edwards Lifesciences Corporation. Invention is credited to Louis A. Campbell.
Application Number | 20170281337 15/494239 |
Document ID | / |
Family ID | 58188568 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170281337 |
Kind Code |
A1 |
Campbell; Louis A. |
October 5, 2017 |
SPACER FOR SECURING A TRANSCATHETER VALVE TO A BIOPROSTHETIC
CARDIAC STRUCTURE
Abstract
A spacer for creating a docking station for a transcatheter
heart valve is provided. The spacer changes an effective diameter
and/or a shape of an implanted bioprosthetic structure such as a
bioprosthetic heart valve or annuloplasty ring, providing a
supporting structure into which the transcatheter valve expands
without over expanding. The spacer may be deployed through an
interventional technique either through transseptal access,
transfemoral access, or transapical access and is typically
deployed at least in part on an inflow portion of the implanted
bioprosthetic structure.
Inventors: |
Campbell; Louis A.; (Santa
Ana, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Edwards Lifesciences Corporation |
Irvine |
CA |
US |
|
|
Family ID: |
58188568 |
Appl. No.: |
15/494239 |
Filed: |
April 21, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2016/050254 |
Sep 2, 2016 |
|
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15494239 |
|
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62213559 |
Sep 2, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2/2448 20130101;
A61F 2/2433 20130101; A61F 2230/0054 20130101; A61F 2210/0014
20130101; A61F 2/2412 20130101; A61F 2250/006 20130101; A61F 2/2418
20130101; A61F 2250/0063 20130101; A61F 2/2409 20130101; A61F
2220/0025 20130101; A61F 2250/0096 20130101 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A spacer for implantation into a bioprosthetic cardiac structure
such as a bioprosthetic heart valve or annuloplasty ring about a
native valve, comprising: a central flow axis having an upstream
direction and a downstream direction, the downstream direction
corresponding to the direction of blood flow from an upstream
portion of the bioprosthetic cardiac structure through leaflets in
a downstream portion of the valve when the spacer is implanted; the
spacer configured for percutaneous delivery and engageable with the
bioprosthetic structure, the spacer having a transcatheter valve
mounting surface; the spacer further comprising a spacer shaft
adapted to receive a transcatheter valve and providing a surface
onto which the transcatheter valve may secure, the spacer having a
first flange for mounting on an upstream portion of the
bioprosthetic structure and a second flange for mounting on the
bioprosthetic cardiac structure in the downstream direction
relative to the first flange, the spacer shaft interconnecting the
first flange and the second flange, the first flange having a
dimension greater than the second flange and greater than an inner
diameter of the bioprosthetic cardiac structure, the first and
second flanges being rings; wherein the bioprosthetic cardiac
structure is one of a prosthetic heart valve and an annuloplasty
ring.
2. A spacer for implantation into a bioprosthetic cardiac structure
such as a bioprosthetic heart valve or annuloplasty ring about a
native valve, comprising: a central flow axis having an upstream
direction and a downstream direction, the downstream direction
corresponding to the direction of blood flow from an upstream
portion of the bioprosthetic cardiac structure through leaflets in
a downstream portion of the valve when the spacer is implanted; the
spacer configured for percutaneous delivery and engageable with the
bioprosthetic structure, the spacer having a transcatheter valve
mounting surface.
3. The spacer of claim 2, further comprising a spacer shaft adapted
to receive a transcatheter valve and providing a surface onto which
the transcatheter valve may secure.
4. The spacer of claim 2, wherein the spacer further comprises a
first flange for mounting on an upstream portion of the
bioprosthetic structure.
5. The spacer of claim 3, wherein the spacer further comprises a
second flange for mounting on the bioprosthetic cardiac structure
in the downstream direction relative to the first ring flange, the
spacer shaft interconnecting the first flange and the second
flange.
6. The spacer of claim 5, wherein the first flange has a dimension
greater than the second flange and greater than an inner diameter
of the bioprosthetic cardiac structure.
7. The spacer of claim 2, wherein the spacer comprises anchors for
securing the spacer to the bioprosthetic heart valve.
8. The spacer of claim 7, wherein the second flange comprises the
anchors.
9. The spacer of claim 2, wherein the spacer comprises a shape
memory material and is self-expanding.
10. The spacer of claim 5, wherein the second flange is adapted to
be secured to an inner diameter of a cylindrical space in an
upstream portion of a bioprosthetic cardiac structure relative to
valve leaflets that are in a downstream direction relative to the
cylindrical space.
11. The spacer of claim 2, wherein at least a portion of the spacer
is balloon-expandable.
12. The spacer ring of claim 2, wherein the spacer includes snares
connected thereto to control expansion of the spacer.
13. The spacer of claim 2, wherein at least a portion of the spacer
is covered with fabric.
14. The spacer of claim 2, wherein the spacer comprises a
cobalt-chromium alloy.
15. The spacer of claim 2, wherein a portion of the spacer is
adapted to secure to a stiffening band in a cylindrical space in
the bioprosthetic cardiac structure.
16. The spacer of claim 3, wherein the spacer shaft is
substantially cylindrical.
17. The spacer of claim 5, wherein the second flange is a ring.
18. The spacer of claim 4, wherein the first flange is a ring.
19. The spacer of claim 18 wherein the first flange is a ring
having a non-circular configuration to adapt to a non-circular
portion of the bioprosthetic cardiac structure.
20. The spacer of claim 2 wherein the spacer comprises sensors that
communicate sensor data.
21. The spacer of claim 3 wherein a shaft into which a THV may dock
is spring loaded.
22. The spacer of claim 3 wherein a shaft into which a THV may dock
comprises a compressible surface.
23. The spacer of claim 2, wherein the bioprosthetic cardiac
structure is a prosthetic heart valve.
24. The spacer of claim 2, wherein the bioprosthetic cardiac
structure is an annuloplasty ring.
25-45. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/US2016/050254, filed Sep. 2, 2016, which claims
the benefit of U.S. Patent Application No. 62/213,559, filed Sep.
2, 2015, the entire disclosures of which are incorporated by
reference herein.
TECHNICAL FIELD
[0002] The present disclosure relates to transcatheter valve
implantation in a bioprosthetic valve or a native valve that has
been repaired with an annuloplasty ring and, in particular, an
apparatus and method to assist in securing the transcatheter valve
in the bioprosthetic valve or to the annuloplasty ring.
BACKGROUND
[0003] Valve-in-valve transcatheter valve implantation is
increasingly used when bioprosthetic heart valves fail.
Bioprosthetic valves are used more often than mechanical valves,
and increasingly, in younger patients. Although the durability of
bioprosthetic valves has improved, some patients outlive the life
of the valve, for example, when structural deterioration causes the
valve to fail. For a younger person with a bioprosthetic valve
replacement, there is a significant likelihood that another valve
replacement will be needed later in life. In such a replacement,
the new valve may be a transcatheter valve (THV) that is placed
within the existing bioprosthetic valve without the need for
open-heart surgery.
[0004] There are transcatheter valves that are appropriately sized
to be placed inside most aortic bioprosthetic valves. Such
transcatheter valves are too small to be secured into some larger
bioprosthetic valve sizes, however. A challenge with valve-in-valve
replacements in the larger valves is that the transcatheter valve
may not be large enough to sufficiently expand inside the implanted
tissue valve to stay in place and to be competent. If the
transcatheter valve is expanded too much, the leaflets of the valve
may not properly come together or coapt for the valve to function
properly.
[0005] Similarly, it may be necessary to implant a transcatheter
valve in a native valve that has been repaired with an annuloplasty
band. Annuloplasty is a technique for repairing valves. An
annuloplasty ring is implanted surrounding the valve annulus,
pulling the leaflets together to facilitate coaptation and proper
function of the native valve leaflets. The annuloplasty ring may
have a non-circular configuration, such as a D-shape as just one
example, particularly when the ring is used in conjunction with the
mitral valve. A spacer according to the present invention may be
adapted to secure to a suitable annuloplasty ring, in order to
provide a structure into which a transcatheter heart valve may be
expanded and secured.
BRIEF SUMMARY
[0006] In one embodiment a spacer, which may alternatively be
referred to as a THV docking station herein, is provided for
implantation into a bioprosthetic cardiac structure such as
bioprosthetic heart valve or an annuloplasty ring that has a
central flow axis, an upstream direction and a downstream
direction. The downstream direction corresponds to the direction of
blood flow from an upstream portion of the bioprosthetic structure,
and through flaps in a downstream portion of a heart valve when the
spacer is implanted. The spacer has a transcatheter valve mounting
surface.
[0007] Considering optional features that may additionally be used,
either alone or in combination with one another, the spacer may
include a first flange for mounting on an upstream surface of the
bioprosthetic structure and a spacer shaft. The spacer may
optionally also have a second flange for mounting on the
bioprosthetic structure in the downstream direction relative to the
first flange. In an embodiment in which the spacer has both a first
and a second flange, the spacer shaft interconnects the first
flange and the second flange. As a further alternative, the spacer
may have a spacer shaft secured to an interior surface of the
existing bioprosthetic structure, without a first or second
flange.
[0008] The first flange may optionally have a dimension that is
greater than that of the second flange and of an inner diameter of
the bioprosthetic structure. The second flange may optionally be
adapted to be secured to an inner diameter of a cylindrical space
in an upstream portion of the bioprosthetic structure relative to
valve leaflets that are in a downstream direction relative to the
cylindrical space. The spacer may optionally include spikes or
other attachment means known in the art for securing the spacer to
the bioprosthetic heart valve. In one embodiment, the second flange
includes such spikes.
[0009] In one aspect, the spacer includes a shape memory material
and is self-expanding for transcatheter delivery into the
bioprosthetic valve. Alternatively, at least a portion of the
spacer may be balloon-expandable.
[0010] Considering other optional features, the spacer may include
snares connected thereto to control expansion of the spacer ring
during deployment. At least a portion of the spacer may be covered
with fabric or other blood-impermeable material. The spacer may
comprise, for example, a cobalt-chromium alloy, nitinol, stainless
steel, and/or other materials known in the art. The second flange
may be adapted to secure to a stiffening band in a cylindrical
space in an upstream portion of the bioprosthetic structure. The
first and/or second flanges may optionally be rings. The spacer
shaft may optionally be substantially cylindrical. In one
embodiment, the spacer includes sensors that communicate sensor
data. The shaft into which a THV may dock may be spring loaded. The
shaft into which a THV may dock comprises a compressible
surface.
[0011] Another aspect is a method of providing a securing surface
for a transcatheter valve within a bioprosthetic structure. The
structure has a central flow axis with an upstream direction and a
downstream direction, the downstream direction corresponding to the
direction of blood flow from an upstream portion of the
bioprosthetic structure through flaps in a downstream portion of
the structure when a spacer is implanted. The method may include
providing a collapsible spacer for a bioprosthetic structure,
collapsing the spacer to a reduced diameter, coupling the spacer to
a distal end portion of an elongate catheter, advancing the
elongate catheter through a patient's vasculature and delivering
the spacer into position relative to the bioprosthetic structure,
and expanding the spacer to provide an engagement surface for a
transcatheter heart valve.
[0012] Considering further optional features of the method that may
additionally be used, either alone or in combination with one
another, the method may further include expanding an upstream
spacer flange such that an outside dimension of the upstream spacer
flange is greater than the inside diameter of an upstream end of
the bioprosthetic structure. The upstream spacer flange may be
positioned into contact with an upstream end surface of the
bioprosthetic structure, and then expansion of the spacer
completed. The spacer may, for example, be secured within the
bioprosthetic structure, the downstream portion of the spacer being
positioned upstream of flaps of the bioprosthetic heart valve or
the native heart valve.
[0013] After being fixed within the bioprosthetic structure, the
spacer ring may have an upstream flange mounted on an upstream
surface of the bioprosthetic structure, and a spacer engagement
surface extending downstream and toward valve flaps. The method may
also include expanding a transcatheter heart valve within the
bioprosthetic structure, the transcatheter heart valve securing to
a surface of the spacer. The spacer may be sequentially pushed out
of a delivery system, an upstream flange being first pushed out of
the delivery system and flipping into position, the upstream flange
pulled to the valve, and the remainder of the spacer pushed out to
complete expansion of the spacer.
[0014] As the spacer is expanded, spikes on the spacer may be
secured into the implanted bioprosthetic structure to maintain the
spacer in position. As one example, the spikes may be secured into
an inner diameter of the bioprosthetic structure. In one
embodiment, the inner diameter of the bioprosthetic structure is
covered with cloth, fabric, or other covering, and the spikes are
secured into the covering. In another aspect, the spacer may have a
downstream flange, with spikes extending from the downstream
flange, and the step of the spikes securing into the inner diameter
of the bioprosthetic structure may include securing spikes that
extend from the downstream flange into the inner diameter of the
bioprosthetic structure upstream of flaps of the valve.
[0015] Expansion of the spacer may be accomplished with a spacer
that is self-expandable. Alternatively, the step of expanding the
spacer may be at least partially accomplished with a balloon. In a
further optional feature, the method may include a step of
controlling expansion of the spacer with snares that are coupled to
the spacer.
[0016] In one embodiment, the spacer has an upstream ring flange
and the method comprises the step of engaging the upstream ring
flange with an upstream portion of the bioprosthetic structure. The
spacer may include a downstream ring flange, and the method
includes the step of engaging the downstream ring flange with a
downstream portion of the bioprosthetic structure.
[0017] Again, the disclosed concept includes variations, and the
optional features noted above may be added to embodiments of the
invention, either alone or in various combinations as
appropriate.
[0018] A further understanding of the nature and advantages will
become apparent by reference to the remaining portions of the
specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 illustrates an embodiment of a spacer mounted onto a
bioprosthetic mitral, tricuspid or aortic valve;
[0020] FIG. 2 is a top view of the spacer of FIG. 1;
[0021] FIG. 3 is a perspective view of the spacer of FIGS. 1 and
2;
[0022] FIG. 4 is a cross-section of the spacer ring of FIG. 3;
[0023] FIG. 5 is a cross-section of one embodiment of a surgical
bioprosthetic valve illustrating a stiffening ring and a
covering;
[0024] FIG. 6 is a cross-sectional view of a catheter delivery
system with one non-limiting example of a self-expanding spacer
ring inside, ready for deployment onto the bioprosthetic valve;
[0025] FIG. 7 illustrates a catheter delivery system of FIG. 6,
with a pusher pushing a self-expanding upper ring flange portion of
the spacer out of the delivery system;
[0026] FIG. 8 illustrates the expanded upper ring flange portion
pulled into place on an upstream portion of the bioprosthetic
valve;
[0027] FIG. 9 is the system of FIG. 8, with the spacer wall and the
lower ring flange expanded into position and the spikes on the
lower ring flange securing the spacer into fabric within the
bioprosthetic valve;
[0028] FIG. 10 illustrates the delivery system being pulled away
after the spacer ring has been implanted;
[0029] FIG. 11 illustrates an alternative embodiment in which
snares control expansion of the spacer;
[0030] FIG. 12 illustrates an alternative embodiment in which the
spacer has an upper flange and a spacer, but no downstream flange,
with the struts not shown for simplicity;
[0031] FIG. 13 illustrates the spacer ring of FIG. 12 in
cross-section;
[0032] FIG. 14 is a perspective view of a spacer interconnected
with an annuloplasty ring;
[0033] FIG. 15 is a top view of the annuloplasty ring of FIG.
14;
[0034] FIG. 16 is a perspective view of the spacer of FIGS. 14 and
15;
[0035] FIG. 17 is a cross-section of the spacer of FIG. 16 taken at
line 17-17;
[0036] FIG. 18 is a perspective view of the spacer of FIG. 14 with
a cover disposed thereover; and
[0037] FIG. 19 illustrated the spacer of FIG. 18 with a
transcatheter heart valve expanded therein.
DETAILED DESCRIPTION
[0038] FIG. 1 illustrates one embodiment of a spacer ring 5
deployed in a surgical mitral or tricuspid prosthetic valve 10, for
example, a Carpentier-Edwards PERIMOUNT Magna Mitral Ease.RTM.
mitral heart valve (Model 7300TFX, Edwards Lifesciences, Irvine,
Calif.). The spacer ring 5 is provided to narrow or reduce the
space an implanted bioprosthetic mitral, tricuspid, pulmonic, or
aortic valve 10 into which the transcatheter valve is to be
implanted, for example, a surgically implantable bioprosthetic
valve. As discussed above, the spacer ring 5 is useful in
situations in which an interior space or lumen of a previously
implanted prosthetic valve is too large for direct implantation of
a largest available transcatheter valve therein. FIG. 2 is a top
view of the same spacer ring 5 in place on the surgical mitral or
tricuspid valve 10. FIG. 3 is a perspective view of the spacer ring
itself, and FIG. 4 is a cross-section of the spacer ring of FIG.
3.
[0039] Considering FIG. 4, the spacer has a first ring flange 20 on
the upstream side, a spacer shaft 30 with an interior surface to
which a transcatheter heart valve may secure, and a downstream
lower ring flange 40 having anchors, barbs, or spikes 50. The
spikes 50 are provided to secure the spacer ring to fabric on the
interior of the surgical bioprosthetic valve. It is noted that the
terms "upstream" and "downstream" are used in conjunction with an
embodiment in which a bioprosthetic valve is the bioprosthetic
structure to which the spacer is to attach, for example, and that
the terms as used with other bioprosthetic structures to which the
spacer attaches may simply refer to relative positions rather than
strictly to directions in which blood flows.
[0040] FIGS. 1 and 2 illustrate a spacer 10 secured in place on
bioprosthetic surgical heart valve 10. Once the spacer is in place,
a transcatheter valve can be placed in the bioprosthetic valve in
the same fashion as would be done in a smaller surgical valve, in
which a spacer ring is not needed, with the transcatheter valve
engaging the interior surface on the spacer that has been placed in
the bioprosthetic valve. The spacer provides axial support for the
transcatheter valve, so that the transcatheter valve will not move
in either the upstream or the downstream direction, as well as
radial support for an outer wall or stent of the transcatheter
valve, thereby reducing a risk of over-expanding the transcatheter
valve.
[0041] FIG. 5 is a cross-sectional view of a representative
surgical bioprosthetic aortic valve 100, such as the
Carpentier-Edwards PERIMOUNT.RTM. aortic heart valve (Model
2700TFX, Edwards Lifesciences) as just one example. The spacer and
method are also adaptable to other prosthetic valves, for example,
prosthetic valves with other structural details, as well as
prosthetic valves designed for other native valve locations
including pulmonic, mitral, and tricuspid prosthetic valves, as
discussed above. As seen, the valve 100 has an inflow direction
corresponding to the direction blood flows into the valve. The
valve also has an outflow direction corresponding to the direction
the blood flows as it exits the valve through the flaps (leaflets).
The valve includes a fabric-covered stent portion supporting valve
leaflets 80. On the inflow side of the valve is an annular cuff. On
the interior of the valve is a generally cylindrical space 120,
illustrated in the cross-sectional view of FIG. 5, backed by a
stiffening ring 125 in the illustrated embodiment. Other
embodiments of the valve do not include a stiffening ring. The
interior is covered with fabric or other covering known in the art
130. This provides a space 120 onto which the spacer 10 (FIGS. 1-4)
may mount on the inflow portion of the valve without substantially
interfering with the operation of the leaflets 80, which could make
the tissue valve incompetent. The spacer may be deployed through an
interventional technique, for example, either through transseptal
access, transfemoral access, or transapical access, and is
typically deployed on or near the inflow end of the implanted
bioprosthetic valve. Alternatively, the spacer may be deployed
surgically, for example, in a minimally-invasive surgical (MIS)
procedure.
[0042] Positioning a device within a beating heart can be
difficult, for example, including one or more challenging steps.
FIG. 6 is a cross-sectional view of a catheter 210 inserted within
an artery 220 for delivery of the spacer 5'. The spacer 5' includes
upstream flange portion 20', spacer surface portion 30', and
downstream flange portion 40' having spikes 50'. A pusher 200
pushes the spacer 5' upstream for delivery onto existing
bioprosthetic valve 10'. In one embodiment the spacer is partially
expanded such that the outside diameter of the upstream flange of
the spacer is larger than the inside diameter of the surgical
valve, as seen in FIG. 7. The spacer can then be pulled from the
atrial position illustrated in FIG. 7 into contact with the
implanted bioprosthetic valve (FIG. 8), where the expansion would
be completed (FIG. 9), for example, by retracting the catheter 210
and/or adjusting a position of the pusher 200. In FIG. 10, the
delivery system including the catheter 210 and the pusher 200'
pulled away from the spacer 5' and bioprosthetic valve 10'. This
approach permits aligning the spacer on the inflow aspect of the
implanted valve without causing the surgical valve to become
incompetent. With this approach, the spacer may be either a
balloon-expandable device or a controlled self-expanding device. As
seen in FIGS. 1 and 2, the structure of the spacer ring includes a
series of struts, most commonly defining diamond-shaped cells, but
in the alternative includes chevron-shaped cells, rectangular
cells, and/or other cell shapes known in the art, and combinations
thereof. The spacer may be expanded by other balloon and/or
mechanical expansion methods known in the art. The spacer may also
be partially self-expanding and partially balloon-expanded. As just
one example, the upstream and/or downstream flanges may
self-expanding, for example, while the central portion of the
spacer is balloon-expanded. Entirely self-expanding embodiments can
also be balloon expanded post-initial deployment, for example, to
ensure that the spacer is fully expanded and/or to seat any
anchors.
[0043] Considering this process in more detail, FIG. 6 illustrates
a self-expanding spacer assembly 5' inside a transcatheter delivery
system in cross-section. In the illustrated embodiment, the spacer
5' is in a delivery configuration in the catheter 210, with the
upstream flange 20', spacer shaft 30', and downstream flange 40'
each extending generally longitudinally, and with the upstream
flange 20' and downstream flange 40' radially compressed. In some
embodiments, the spacer shaft 30' is also radially compressed. The
illustrated embodiment also includes a plurality of optional
engagement means, engagement elements, or anchors 50', which in
other embodiments have a different configuration. As a pusher 200
pushes the spacer assembly 5' out of the catheter 210, the upstream
flange 20' first extends longitudinally out of the opening at the
distal end of the catheter 210, then flips or rotates down into a
generally horizontal or radial position, as seen in FIGS. 6 and 7.
The spacer and catheter are then pulled or retracted proximally so
that the spacer contacts the valve, and expansion of the spacer,
including spacer shaft 30' and downstream ring 40', continues as
the spacer 5' is urged out of the catheter 201, for example, by
retracting the catheter while preventing proximal movement of the
spacer 5' using the pusher 200, as shown in FIG. 8. A series of
spikes 50' on the downstream ring 40' then flip from a longitudinal
delivery configuration to a radial deployed configuration as the
downstream ring 40' does the same. In the embodiment illustrated in
FIG. 9, the pusher 200 is urged distally, for example, urging the
downstream ring 40' into the final deployed configuration and/or
urging the anchors or spikes 50' into the fabric disposed around
the inner diameter of the implanted bioprosthetic valve 10' to
maintain and to secure the spacer in position. As the spacer is
pushed out of the delivery system, the spikes 50' extend across the
inner diameter and into fabric of the surgical valve. As an
alternative, the flanges 20' and 40' may be deployed to sandwich
the structure 10' to hold the spacer in place.
[0044] In a preferred embodiment, the upstream and downstream
flanges and the spacer shaft are, in plan view, ring-shaped.
However, it is noted that the flanges and the spacer shaft may take
forms other than rings. Further, the upstream and downstream
flanges and the spacer shaft may have different plan,
cross-sectional geometries from one another, so long as they serve
their respective purposes in the spacer assembly.
[0045] FIG. 11 illustrates that in an alternative embodiment,
expansion of the spacer after leaving the delivery system may be
controlled by snares 240. The snares 240 may be loops of suture
material or wire, for example, or another suitable design. In one
approach, the snares 240 extend up through a passageway in a pusher
200'. Expansion of the spacer 5' is then controlled when the snares
240 are held relatively tightly in tension, then the tension
released in a controlled manner, for example, gradually, until the
spacer 5' is in position, or in any manner appropriate in a given
situation.
[0046] In some bioprosthetic valves, for example, certain
bioprosthetic valves manufactured and provided by Edwards
Lifesciences, the valve has a stiffening ring 125, as illustrated
in FIG. 5. The stiffening ring 125 is typically a fabric-covered or
otherwise covered ring preferably made of cobalt-chromium alloy
(e.g., ELGILOY.RTM. alloy, Elgiloy Specialty Metals, Elgin, Ill.)
that extends around the inflow aspect of the prosthetic valve,
although the stiffening ring may include other materials, for
example, any combination of stainless steel, nitinol,
cobalt-chromium, and polymer. The stiffening ring 125 stabilizes
and strengthens the prosthetic valve. As seen in FIG. 10, for
example, length of the spacer portion and the lower ring is
sufficiently short so as to ensure that the spiked portion of the
spacer rings does not extend into or contact the leaflets of the
valve, but will rather engage with the fabric covering 120 over the
stiffening element on the inflow aspect.
[0047] In an alternative embodiment of a spacer, a cover made of
fabric or suitable material may be placed over the spacer itself or
over a portion thereof. In a preferred embodiment, the spacer does
not have a cover, since a cover can add expense to the spacer
and/or increase a delivery profile thereof. Moreover, many
transcatheter valves do not have a fabric cover, so a cover
disposed over the spacer would have no benefit. On the other hand,
as an alternative, a cover on the spacer device may encourage
fibrous tissue overgrowth and incorporation of the spacer into the
transcatheter valve and the surgical valve, and/or reduce
perivalvular leakage around an implanted transcatheter valve.
[0048] FIG. 12 illustrates an alternative embodiment in which the
spacer has an upstream flange 320 and a spacer shaft 330, but no
downstream ring below the spacer 330. FIG. 13 is a cross-sectional
view of the spacer of FIG. 12, both of which are shown without
struts for simplicity of illustration, although the ring would
normally have struts as in FIGS. 1 and 2. The spacer of FIG. 12 may
be secured with anchors or spikes 350, for example, disposed on the
lower or outflow surface of the upstream flange 320, and/or
disposed on an outer wall of spacer shaft 330 as shown.
[0049] In an embodiment of the spacer ring that is
balloon-expandable, the spacer is preferably made from a material
that is fairly close in the galvanic series to the transcatheter
valve and/or to the prosthetic surgical valve. In this way, there
is not a stress corrosion problem between metal portions of the
transcatheter valve, metal portions of the spacer, and/or metal
portions of the prosthetic surgical valve, for example, the stent
of the transcatheter valve contacting the spacer shaft, or the band
of the prosthetic surgical valve contacting the anchors of the
spacer. For example, the spacer ring may be made of one or more of
a stainless steel alloy, titanium alloy, nitinol, or a
cobalt-chromium alloy, depending on the material of the
transcatheter valve. Cobalt-chromium has a similar oxidation
potential to nitinol, and consequently cobalt-chromium is a
preferred material for use with transcatheter valves that include
nitinol frames. A cobalt-chromium spacer ring could then be used
with a transcatheter valve including nitinol and/or
cobalt-chromium, for example, in a stent or frame, to avoid a
corrosion problem.
[0050] Spacer rings according to the present invention may be used
to provide a dock that secures to an annuloplasty ring, such as the
Carpentier-Edwards.RTM. Classic Annuloplasty Ring (Edwards
Lifesciences, Irvine, Calif.) with a titanium core and fabric
cover, or any of a wide variety of other annuloplasty rings. The
annuloplasty ring reshapes the valve annulus, so that the native
valve leaflets may properly coapt. Still, the native valve may
ultimately need replacement with, for example, a transcatheter
heart valve. A spacer structure that is secured to the annuloplasty
ring may provide a docking region suitable for a THV to expand into
and anchor. The drawings illustrate an exemplary D-shaped
annuloplasty ring, although the spacer is applicable to rings of
other shapes, including open rings or bands, as well as with rigid
or flexible rings. Embodiments of the spacer are applicable to both
mitral and tricuspid annuloplasty rings. In some embodiments, the
spacer provides a structure at the open portion of an open ring
that constrains THV expansion, for example, against the left
ventricular tract (LVOT), thereby reducing the likelihood of LVOT
obstruction in such cases. As with the embodiments of the spacer
described and illustrated above, embodiments of annuloplasty-ring
spacers have a longitudinal or vertical profile that permits the
native leaflets to remain competent when the spacer is engaged to
the annuloplasty ring, before a THV is deployed therein.
[0051] FIGS. 14 and 15 illustrate a spacer 405 that is secured to a
generally D-shaped annuloplasty ring 410. The annuloplasty ring 410
includes a central open cylindrical shaft 415, an upper flange 420,
a surface 430 within the cylindrical shaft onto which a THV can
expand and anchor, and a lower flange 440. The curved armatures of
the upper and lower flanges have lengths chosen to adapt to the
shape of the annuloplasty ring 410. The annuloplasty ring 410 is
typically covered with a fabric covering, and spikes 450 extend
from the lower flange 440 into the fabric to help secure the spacer
405 to the annuloplasty ring 410. The upper flange 420 of the
spacer is typically against an upper surface of the annuloplasty
ring and may optionally secure to a fabric covering of the
annuloplasty ring with spikes or other attaching means. FIGS. 16
and 17 illustrate the expanded spacer 405 in isolation.
[0052] The spacer may be secured to the annuloplasty ring in the
manner illustrated in FIGS. 6-9. As with some other embodiments,
snares may be used to control expansion of the spacer ring during
deployment. Alternatively, the second flange may be deployed such
that the annuloplasty ring is sandwiched in between the first and
second flanges.
[0053] From another perspective, one embodiment of a docking
station is designed to seal at the proximal inflow section to
create a conduit for blood flow and to prevent pericardial leakage.
The distal outflow section, however, is generally left open. In one
specific embodiment, cloth, such as a polyethylene terephthalate
(PET) cloth for example, or other material covers the proximal
inflow section, but the covering does not cover at least a portion
of the distal outflow section. The openings in the cloth are small
enough to significantly impede blood passage therethrough. Again, a
variety of other biocompatible covering materials may be used such
as, for example, a fabric that is treated with a coating that is
impermeable to blood, polyester, polytetrafluoroethylene fabric
(PTFE, for example, ePTFE), a processed biological material, such
as pericardium, or other coverings known in the art. The spacer
ring may alternatively be fully covered, or covered only in
selected areas. When the surface to which the THV secures is
covered, the covering may assist in creating a tight seal and/or
improving engagement with the THV.
[0054] In another aspect, the inner diameter of the spacer ring
remains within the operating range of the THV. Consequently, the
THV can operate within a space that otherwise would be too wide for
the THV to operate properly, and/or in a space that otherwise would
not permit a THV to reliably secure, for example, the D-shaped
opening illustrated in the drawings.
[0055] As noted previously, the spacers may be self-expanding or
balloon expanded. In a balloon expanded embodiment, one or more
balloons inflates to expand the spacer. The balloons are removed,
and a THV is delivered and expanded into the central shaft of the
spacer. Other methods of expansion known in the art may be
employed. For example, the spacer ring may be bundled with the THV
prior to delivery, with both the spacer ring and the THV being
delivered and expanded in a single delivery.
[0056] In another embodiment, the spacer may include a sensor, such
as a pressure sensor. As one use for a sensor, the pressure of the
docking station against the vessel wall may be detected during
deployment. The sensor may communicate sensor data via a delivery
catheter, for example. The data is used during balloon expansion,
for instance, to determine when sufficient pressure against the
vessel wall, the surgical valve and/or the annuloplasty ring as the
case may be has been achieved, such that further expansion is not
necessary. This approach may be useful when the dimensions,
elasticity of the vessel walls, and/or other variables are
uncertain prior to expansion of the docking station.
[0057] In another aspect, the outer surface of the spacer may be
secured by positive pressure. A THV is expanded into the inner
surface of the ring. The inner ring may be "spring loaded" to
maintain force against the THV, thereby holding the THV in place. A
stent structure in between the inner and outer ring surfaces may
provide the spring loading. Alternatively, spring-like mechanisms
may be built into the space in between the inner and outer ring
surfaces.
[0058] In other alternative, an inner ring acts as a landing zone
into which the THV docks. The inner ring may have a soft or
compressible inner surface, such as foam, a resilient polymer, a
hydrogel, or other suitable biocompatible material. The inner
surface may give way under the force of the expanded THV. The area
between the inner surface and outer surface of the ring may be
sealed, such as with a fabric covering or a skirt that is on an
interior surface of the ring, or otherwise have s surface that
prevents the bypass of blood around the THV. It is noted that
"ring" as used herein includes shapes that are not circular in
cross-section, such as for example the outer ring that conforms to
a D-shape or other shape in order to secure the outer ring to the
supporting structure.
[0059] In view of the many possible embodiments to which the
disclosed principles may be applied, it should be recognized that
the illustrated embodiments are only preferred examples and should
not be taken as limiting the scope of the disclosure. Rather, the
scope is defined by the following claims. We therefore claim all
that comes within the scope and spirit of these claims.
* * * * *