U.S. patent application number 12/407656 was filed with the patent office on 2009-07-16 for reconfiguring heart features.
This patent application is currently assigned to Millipede LLC. Invention is credited to Steven F. Bolling.
Application Number | 20090182419 12/407656 |
Document ID | / |
Family ID | 39594963 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090182419 |
Kind Code |
A1 |
Bolling; Steven F. |
July 16, 2009 |
RECONFIGURING HEART FEATURES
Abstract
Among other things, a heart tissue support has gripping
elements, each element having a free end that is sharp enough to
penetrate heart tissue when pushed against the tissue, and a
feature to resist withdrawal from the tissue after the sharp free
end has penetrated the tissue. Among other things, the shape of a
heart valve annulus is corrected in a catheter laboratory by
orienting a tip of a catheter holding a heart tissue support that
has gripping elements at the valve annulus, applying a radial force
from the catheter against the annulus by opening a structure at the
tip of the catheter, and while the structure is opened, forcing the
support onto the annulus. Among other things, the shape of a heart
valve annulus is corrected during a surgical procedure by pushing a
heart tissue support that has gripping elements onto the
annulus.
Inventors: |
Bolling; Steven F.; (Ann
Arbor, MI) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
Millipede LLC
Ann Arbor
MI
|
Family ID: |
39594963 |
Appl. No.: |
12/407656 |
Filed: |
March 19, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11620955 |
Jan 8, 2007 |
|
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12407656 |
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Current U.S.
Class: |
623/2.36 |
Current CPC
Class: |
A61B 2017/00243
20130101; A61B 2017/0409 20130101; A61F 2/243 20130101; A61B 17/068
20130101; A61F 2/2466 20130101; A61B 2017/00862 20130101; A61B
2017/00867 20130101; A61B 2017/12018 20130101; A61F 2/2445
20130101; A61B 17/00234 20130101; A61B 2017/0414 20130101; A61B
17/0401 20130101; A61B 2017/0647 20130101; A61B 17/0644 20130101;
A61B 2017/00783 20130101 |
Class at
Publication: |
623/2.36 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. An apparatus comprising: a heart tissue support having gripping
elements, each gripping element having a free end that is sharp
enough to penetrate heart tissue when pushed against the tissue,
and a feature to resist withdrawal of the gripping element from the
tissue after the sharp free end has penetrated the tissue.
2. The apparatus of claim 1 in which the free ends of the gripping
elements project away from a surface of the support.
3. The apparatus of claim 1 in which the feature that resists
withdrawal of the gripping element from the tissue comprises a
finger projecting laterally from the gripping element.
4. The apparatus of claim 1 in which the heart tissue support
comprises an annular surface bearing the gripping elements.
5. The apparatus of claim 1 in which the support is expandable and
contractible.
6. The apparatus of claim 5 in which the support has a native size
that is configurable.
7. The apparatus of claim 6 in which a wire configures the native
size.
8. The apparatus of claim 1 in which the support comprises at least
one of stainless steel, gold, Nitinol, or a biologically compatible
elastomer.
9. The apparatus of claim 1 in which the support comprises a
torus.
10. The apparatus of claim 1 in which the support comprises a
helically wound portion.
11. The apparatus of claim 1 in which some portions of the support
bear no gripping elements.
12. The apparatus of claim 1 in which the gripping elements are
organized in a pattern.
13. The apparatus of claim 12 in which the pattern comprises
rows.
14. The apparatus of claim 12 in which the pattern comprises a
group in which the gripping elements are more densely placed and a
group in which the gripping elements are less densely placed.
15. The apparatus of claim 12 in which the pattern comprises
arcs.
16. The apparatus of claim 12 in which the pattern comprises
clusters.
17. The apparatus of claim 12 in which the pattern comprises random
placement.
18. The apparatus of claim 1 in which at least some of the gripping
elements comprise at least one of platinum, gold, palladium,
rhenium, tantalum, tungsten, molybdenum, nickel, cobalt, stainless
steel, Nitinol, and alloys of any combination of them.
19. The apparatus of claim 1 in which the gripping elements have
the same size.
20. The apparatus of claim 1 in which some of the gripping elements
are of different sizes.
21. The apparatus of claim 1 in which at least some of the gripping
elements have more than one of the feature that resists
withdrawal.
22. The apparatus of claim 2 in which at least some of the gripping
elements project from the surface orthogonally.
23. The apparatus of claim 1 in which at least some of the gripping
elements are curved.
24. The apparatus of claim 1 also including a sleeve through which
tissue can grow.
25. The apparatus of claim 24 in which the sleeve comprises
polyethylene terephthalate.
26. The apparatus of claim 1 in which there are between about 15
and a million gripping elements on the support.
27. The apparatus of claim 1 in which there are between about 100
and about 100,000 gripping elements.
28. The apparatus of claim 1 in which the gripping elements
comprise burr hooks.
29. The apparatus of claim 1 in which the gripping elements
comprise arrows.
30. The apparatus of claim 1 in which the gripping elements
comprise hooks.
31. A method comprising: correcting the shape of a heart valve
annulus in a catheter laboratory by orienting a tip of a catheter
holding a heart tissue support that has gripping elements at the
valve annulus, applying a radial force from the catheter against
the annulus by opening a structure at the tip of the catheter, and
while the structure is opened, forcing the support onto the valve
annulus.
32. A method comprising: correcting the shape of a heart valve
annulus during a surgical procedure by pushing a heart tissue
support that has gripping elements onto the valve annulus.
33. A method comprising attaching, to different sized heart valve
annuli in different patients, supports that can be expanded in
preparation for attachment and allowed to contract to a common
relaxed, non-expanded native size when they are in place on the
annuli, and reducing the sizes of at least some of the in-place
supports to be smaller than the common relaxed non-expanded native
size, to accommodate the different sized heart valve annuli of
different patients.
34. A heart tissue support comprising: a large number of small
grippers, each having a tissue penetration feature and a retention
feature, and the configuration of the grippers relative to a
configuration of a given area of heart tissue to which the support
is to be attached by force being such that (1) the penetration
features of a failed set of the grippers will fail to penetrate the
tissue, (2) the penetration features of a second set of the
grippers will successfully penetrate the tissue, (3) the retention
features of a subset of the second set of grippers will fail to
retain the grippers in the tissue, and (4) the retention features
of the remaining grippers of the second set will successfully
retain the grippers in the tissue and hold the support in an
intended configuration on the tissue.
35. A method comprising: pushing a support onto a region of heart
tissue to cause only a portion of a number of small grippers on the
support to embed themselves and be retained in the tissue, the
portion being sufficient to attach the support securely to the
heart tissue.
36. An apparatus comprising: an annular heart valve support that is
expandable and contractible and bears gripping elements configured
to penetrate heart tissue and to retain the elements in the tissue
after penetration.
37. A tool to attach a support to a heart valve annulus, the tool
comprising mechanisms to hold the support in an expanded
configuration prior to attachment, to expand the heart valve
annulus prior to attachment, to enable the attachment of the
support in its expanded configuration to the expanded valve
annulus, and to release the expanded support to a contracted
configuration after the attachment.
38. The tool of claim 37 attached to an end of a catheter.
39. The tool of claim 37 also comprising an inflatable balloon.
40. The tool of claim 39 in which the balloon plays a role in
positioning the tool.
41. The tool of claim 37 also in which the mechanisms are also to
remove the tool from the heart after attachment.
42. A tool to attach a support to a heart valve annulus, the tool
comprising a structure to expand the annulus of the heart to a
predetermined shape under control of an operator.
43. The tool of claim 42 in which the structure has a conical outer
surface at least a portion of which conforms to the predetermined
shape.
44. The tool of claim 42 in which the structure has an outer
surface that can be expanded to the predetermined shape.
Description
[0001] This is a continuation-in-part of U.S. patent application
Ser. No. 11/620,955, filed on Jan. 8, 2007, which is incorporated
herein in its entirety by reference.
BACKGROUND
[0002] This description relates to reconfiguring heart
features.
[0003] The annulus of a heart valve (a fibrous ring attached to the
wall of the heart), for example, maintains the shape of the valve
opening and supports the valve leaflets. In a healthy heart, the
annulus is typically round and has a diameter that enables the
leaflets to close the valve tightly, ensuring no blood
regurgitation during contraction of the heart. Because the annulus
of the tricuspid valve, for example, is supported more stably by
the heart tissue on one side of the annulus than on the other side,
and for other reasons, the size and shape of the annulus may become
distorted over time. The distortion may prevent the valve from
closing properly, allowing blood to regurgitate backwards through
the valve. The distortion can be corrected, for example, during
open heart surgery, by attaching a ring or other support around the
annulus to restore its shape and size.
SUMMARY
[0004] In general, in an aspect, a heart tissue support has
gripping elements, each gripping element having a free end that is
sharp enough to penetrate heart tissue when pushed against the
tissue, and a feature to resist withdrawal of the gripping element
from the tissue after the sharp free end has penetrated the
tissue.
[0005] Implementations may include one or more of the following
features. The free ends of the gripping elements may project away
from a surface of the support. The feature that resists withdrawal
of the gripping element from the tissue may comprise a finger
projecting laterally from the gripping element. The heart tissue
support may comprise an annular surface bearing the gripping
elements. The support may be expandable and contractible. The
support may have a native size that is configurable. A wire may
configure the native size. The support may comprise at least one of
stainless steel, gold, Nitinol, or a biologically compatible
elastomer. The support may comprise a torus. The support may
comprise a helically wound portion. Some portions of the support
may bear no gripping elements. The gripping elements may be
organized in a pattern. The pattern may comprise rows. The pattern
may comprise a group in which the gripping elements are more
densely placed and a group in which the gripping elements are less
densely placed. The pattern may comprise arcs. The pattern may
comprise clusters. The pattern may comprise random placement. At
least some of the gripping elements may comprise at least one of
platinum, gold, palladium, rhenium, tantalum, tungsten, molybdenum,
nickel, cobalt, stainless steel, Nitinol, and alloys of any
combination of them. The gripping elements may have the same size.
Some of the gripping elements may be of different sizes. At least
some of the gripping elements may have more than one of the feature
that resists withdrawal. At least some of the gripping elements may
project from the surface orthogonally. At least some of the
gripping elements may be curved. The heart tissue support may also
include a sleeve through which tissue can grow. The sleeve may
comprise polyethylene terephthalate. There may be between about 15
and a million gripping elements on the support. There may be
between about 100 and about 100,000 gripping elements. The gripping
elements may comprise burr hooks. The gripping elements may
comprise arrows. The gripping elements may comprise hooks.
[0006] In general, in an aspect, the shape of a heart valve annulus
is corrected in a catheter laboratory by orienting a tip of a
catheter holding a heart tissue support that has gripping elements
at the valve annulus, applying a radial force from the catheter
against the annulus by opening a structure at the tip of the
catheter, and while the structure is opened, forcing the support
onto the valve annulus.
[0007] In general, in an aspect, the shape of a heart valve annulus
is corrected during a surgical procedure by pushing a heart tissue
support that has gripping elements onto the valve annulus.
[0008] In general, in an aspect, a method comprises attaching, to
different sized heart valve annuli in different patients, supports
that can be expanded in preparation for attachment and allowed to
contract to a common relaxed, non-expanded native size when they
are in place on the annuli, and reducing the sizes of at least some
of the in-place supports to be smaller than the common relaxed
non-expanded native size, to accommodate the different sized heart
valve annuli of different patients.
[0009] In general, in an aspect, a heart tissue support comprises a
large number of small grippers, each having a tissue penetration
feature and a retention feature, and the configuration of the
grippers relative to a configuration of a given area of heart
tissue to which the support is to be attached by force being such
that the penetration features of a failed set of the grippers will
fail to penetrate the tissue, the penetration features of a second
set of the grippers will successfully penetrate the tissue, the
retention features of a subset of the second set of grippers will
fail to retain the grippers in the tissue, and the retention
features of the remaining grippers of the second set will
successfully retain the grippers in the tissue and hold the support
in an intended configuration on the tissue.
[0010] In general, in an aspect, a method comprises pushing a
support onto a region of heart tissue to cause only a portion of a
number of small grippers on the support to embed themselves and be
retained in the tissue, the portion being sufficient to attach the
support securely to the heart tissue.
[0011] In general, in an aspect, an annular heart valve support is
expandable and contractible and bears gripping elements configured
to penetrate heart tissue and to retain the elements in the tissue
after penetration.
[0012] In general, in an aspect, a tool to attach a support to a
heart valve annulus comprises mechanisms to hold the support in an
expanded configuration prior to attachment, to expand the heart
valve annulus prior to attachment, to enable the attachment of the
support in its expanded configuration to the expanded valve
annulus, and to release the expanded support to a contracted
configuration after the attachment.
[0013] Implementations may include one or more of the following
features. The tool may be attached to an end of a catheter. The
tool may also comprise an inflatable balloon. The balloon may play
a role in positioning the tool. The mechanisms may also be to
remove the tool from the heart after attachment.
[0014] In general, in an aspect, tool to attach a support to a
heart valve annulus comprises a structure to expand the annulus of
the heart to a predetermined shape under control of an
operator.
[0015] Implementations may include one or more of the following
features. The structure of the tool may have a conical outer
surface at least a portion of which conforms to the predetermined
shape. The structure of the tool may have an outer surface that can
be expanded to the predetermined shape.
[0016] Among advantages of these and other aspects and features are
one or more of the following. The operator need not work as slowly
in order to correctly attach the heart tissue support to the
annulus, nor does placement require as much precision. Not all of
the burr hooks or grippers need be attached to the annulus to keep
the support in place. Some of the burr hooks or grippers might fail
to grab onto tissue, or be pulled away from tissue by force.
Nonetheless, as long as a minimum threshold percentage of the burr
hooks or grippers remain in place, so will the tissue support.
Further, because of its ease and simplicity, this procedure can be
done in a catheterization laboratory, as well as in surgery.
[0017] These and other aspects and features, and combinations of
them, may be expressed as apparatus, methods, systems, and in other
ways.
[0018] Other features and advantages will be apparent from the
description and the claims.
DESCRIPTION
[0019] FIGS. 1A through 1H and 13A through 13D show delivery of a
heart valve support.
[0020] FIGS. 2A through 2D are perspective views of a heart valve
support.
[0021] FIG. 2E is a plan view of a recurved hook.
[0022] FIG. 3 is a section side view of a heart valve support.
[0023] FIGS. 4A through 4C are side and detailed views of a
delivery tool and heart valve support.
[0024] FIG. 5 is a side view of a delivery tool.
[0025] FIGS. 6A and 6B are sectional side views of a catheter
delivery tool.
[0026] FIGS. 7A through 8I show delivery of a heart valve
support.
[0027] FIGS. 9A, 9R, 9T and 9U are plan views of a heart tissue
support.
[0028] FIGS. 9B, 9P, and 9S are perspective views of fragments of
heart tissue supports.
[0029] FIGS. 9C through 9E, 9G and 9H are side views of burr
hooks.
[0030] FIG. 9F is a schematic view of a heart tissue support
attached to annular tissue.
[0031] FIGS. 9I through 9M and 9O are close-up views of portions of
heart tissue support surfaces.
[0032] FIGS. 9N and 9Q are views of a heart tissue support and a
delivery tool.
[0033] FIGS. 10A and 10B are side views of a delivery tool, and a
cross-section of a sheath.
[0034] FIGS. 10C and 10D are cross-sectional views of a delivery
tool and sheath.
[0035] FIG. 11A is a perspective view of a delivery tool in a heart
annulus.
[0036] FIG. 11B is a view of the operator end of a delivery
tool.
[0037] FIGS. 12C and 11F are close-up views of a heart tissue
support attached to a delivery tool.
[0038] FIGS. 11D and 11E are close-up views of a portion of a heart
tissue support attached to annular tissue.
[0039] FIGS. 12A and 12B are views of a core of a delivery
tool.
[0040] FIG. 12C is a perspective view of a core of a delivery
tool.
[0041] As shown in the examples of FIGS. 1A through 1G distortion
of an annulus 18 of a heart valve 16 can be corrected simply and
quickly by the following steps:
[0042] A. Push 201 (FIG. 1A) a conical head-end basket 220 of a
delivery tool 200 into the valve to force the distorted annulus
(203, FIG. 1F) to conform to a desired configuration (e.g., a
circle 205, FIG. 1G) and to a size that is larger (e.g., in
diameter 207) than a desired final diameter 209 of the annulus
(FIG. 1H). (The tool including the basket are shown in side view
and the valve and annulus are shown in sectional side view.)
[0043] B. Continue to push 201 the delivery tool to drive an
expanded heart valve support 100 (which has the desired
configuration and the larger size and is temporarily held in its
expanded configuration on the basket of the tool) towards the
annulus to seat multiple (for example, eight, as shown, or a larger
or smaller number of) recurved hooks 120 located along the
periphery of the support simultaneously into the valve tissue at
multiple locations along the periphery 121 of the annulus (FIG.
1B).
[0044] C. After the hooks are seated, pull 204 (FIG. 1C) on and
evert the tip 230 of the head end basket from the inside to cause
the support to roll so that the tips 122 of the hooks rotate 211
and embed themselves more securely into the annulus tissue (FIG.
1C).
[0045] D. After the hooks are further embedded, continue to pull
204 (FIG. 1D) on the inside 213 of the tip of the head-end basket
to break the tool away from the support (FIG. 1E), allowing the
support to contract to its final size and shape 215 (FIG. 1H) and
leaving the support permanently in place to maintain the annulus in
the desired final configuration and size.
[0046] The entire procedure can be performed in less than a minute
in many cases. By temporarily forcing the annulus of the valve to
expand to the desired circular shape, it is possible to attach the
support quickly, easily, and somewhat automatically by forcing
multiple gripping elements into the tissue at one time. Hooks are
used in this example, although other types of gripping elements may
be used as well. The physician avoids the time consuming steps of
having to attach individual sutures or clips one at a time along
the periphery of a distorted annulus and then cinch them together
to reform the supported annulus to a desired shape and size. Thus,
the physician does not even need to be able to see the annulus
clearly (or at all). Once attached, when the tool is removed, the
support automatically springs back to its final shape and size.
[0047] As shown in FIGS. 2A and 2D, in some implementations the
support includes a circular ring body 110 that bears the hooks 120.
The body 110 can be expanded from (a) a minimal-diameter long-term
configuration (FIG. 2A) to which it conforms after it has been
attached to the annulus to (b) an expanded delivery configuration
(FIG. 2D) to which it conforms when it is held on the head-end
basket of the tool and while it is being attached in the steps
shown in FIGS. 1A, 1B, and 1C. The long-term configuration is
normally circular and has the diameter of a healthy annulus for a
particular patient. When attached, the support maintains the
healthy configuration of the annulus so that the valve will work
properly.
[0048] In some examples, the body 110 has the same (e.g., circular)
shape but different diameters in the delivery configuration and the
long-term configuration. The body is constructed of a material or
in a manner that biases the body to contract to the long-term
configuration. For example, all or portions of the body 110 may be
formed as a helical spring 110a such as a continuous helical spring
connected at opposite ends to form a circular body or one or more
interconnected helical spring segments (FIG. 2B). In some examples,
the support body 110b may be a band of shape memory material such
as Nitinol or a biologically compatible elastomer (or other
material) that will return to the long-term configuration after
being expanded to the delivery configuration (FIG. 2C).
[0049] The hooks 120 may number as few as three or as many as ten
or twenty or more and may be arranged at equal intervals along the
body or at unequal intervals as needed to make the body easy and
quick to deliver, permanent in its placement, and effective in
correcting distortion of the valve annulus. The hooks are
configured and together mounted along the circular outer periphery
so that they can be inserted simultaneously into the tissue along
the periphery of the annulus and then firmly embedded when the tool
is pulled away and the basket is everted.
[0050] In some examples, a portion or portions of the support body
may not have hooks attached if, for example, a segment of the valve
annulus shares a boundary with sensitive or delicate tissue, such
as the atrioventricular (AV) node of the heart. This tissue should
not be pierced by the hooks. A support body configured to avoid
interfering with the AV node could have a section having no hooks
attached or otherwise covered or protected to prevent penetration
by hooks into the AV node. The support body should be positioned so
that this special section of the support body is adjacent the
sensitive or delicate tissue as the support body is put into place.
The support body may have more than one special section lacking
hooks, so that the operator has more than one option when placing
the support body near the sensitive tissue. In some examples, the
support body could have a section removed entirely, and would be
shaped somewhat like the letter "C" instead of a complete ring. In
any of these examples, the procedure described above could have an
additional step preceding step A, in which the operator rotates the
delivery head to position the section having no hooks or to
position the gap in the support body to be adjacent to the
sensitive tissue at the moment when the hooks are to be embedded in
the other tissue. The support body may have radiopaque marks to
help the operator view the positioning.
[0051] For this reason, as shown in FIG. 2E, for example, each of
the hooks has two pointed features. One pointed feature is a sharp
free end 122 pointing away from the valve leaflets during delivery.
The other pointed feature is a barb 128 formed at a bend between
the sharp free end 122 and an opposite connection end 124 where the
hook is attached, e.g., welded or glued, to the body 110. The barb
points toward the valve leaflets during delivery. Thus, the barb is
arranged to penetrate the tissue when the tool is pushed toward the
valve, and the sharp free end is arranged to embed the hook into
the tissue when the tool is pulled away from the valve.
[0052] Each hook 120 can be formed of biologically compatible
materials such as platinum, gold, palladium, rhenium, tantalum,
tungsten, molybdenum, nickel, cobalt, stainless steel, Nitinol, and
alloys, polymers, or other materials. During delivery the barbs of
the hooks are together (and more or less simultaneously) forced
into the tissue at a series of locations around the outer periphery
of the temporarily expanded annulus. In a later step, the sharp
free ends are forced to rotate somewhat away from the leaflets for
secure (e.g., permanent) attachment.
[0053] To cause the hooks to rotate during delivery, the hooks 120
are attached permanently to the support body 110 and the support
body can be rolled 123 (FIG. 3) about a central annular axis 112 of
the support body, as indicated. One way to cause the rolling of the
support body and the associated rotation of the hooks is to enable
the body to change its configuration by rotation of the entire body
about an axis represented by the central circular axis 123, much as
a rubber o-ring can be rolled about its central circular axis. The
reconfiguration of the body to cause the rotation of the hooks can
be achieved in other ways.
[0054] In some examples, applying an axial force (arrows 113) to
the inner peripheral edge of the ring (we sometimes refer to the
support broadly as a ring) will cause the ring to tend to roll and
the hooks to embed themselves in the annulus as intended. By
appropriately mounting the inner periphery of the ring on the outer
periphery of the delivery tool, the axial force 113 can be applied
by pulling the tool away from the leaflets of the valve, as
explained earlier.
[0055] For delivery to the valve annulus, the valve support 100 is
first expanded to its delivery configuration and temporarily
mounted on a delivery head 220 of the tool 200 (FIG. 4A). The
support could be expanded enough in its temporary mounting on the
tool and mounted far enough away from the tip along the conical
head-end basket so that when the head-end basket of the tool is
pushed against the annulus to force it to expand to the size and
shape of the expanded support, the annulus first has reached a
circular, non-distorted shape before the support hook barbs begin
to penetrate the tissue. The tapered profile of the head-end basket
of the delivery tool allows the tool to accommodate supports of
various sizes. In some implementations, different shapes and sizes
of baskets could be used for supports of different sizes.
[0056] The heart valve support 100 is held in place on the delivery
head 220 using one or more releasable connections 246. The
connections 246 are arranged to translate forces from the tool 200
to the support 100 in each of two opposite directions 248 and 250,
toward or away from the leaflets of the valve. When the support has
been embedded in the annulus and the tool is pulled in the
direction 250 to release it from the support, the force on the
connections 246 exceeds a predetermined threshold, and the
connections break, releasing the tool from the support at the end
of the delivery process. The connections 246 may be, in some
examples, breakable sutures 252 (FIG. 4A), or some other breakaway
structure such as clips or adhesive or a structure that can be
manipulated from the tool by unscrewing or other manipulation.
[0057] In some examples, the connections 246 include retainers that
can take, e.g., the configurations shown as 254a or 254b (FIGS. 4B
& 4C, respectively). In the example shown in FIG. 4B, the
retaining element 254a has one rigid finger 256 to translate forces
from the tool 200 to the support 100 when the tool is moved in
direction 248 while the support is attached to the tool and being
pushed into the heart tissue. A second deformable finger 258 aids
in maintaining the connection between the support 100 and the tool
200 when the tool is moved in direction 250 and is deformable
(dashed lines) to release the valve support 100 from the tool 200
when the force in direction 250 relative to the embedded support
exceeds a predetermined threshold.
[0058] In the example shown in FIG. 4C, the retaining element 254b
includes a finger 260 having a crook 262 to receive the support 100
and to translate forces from the tool 200 to the support 100 when
the tool is moved in direction 248. The finger has a resiliently
deformable tip 264 that is biased towards the tapered body 222 and
helps to maintain the connection between the support 100 and the
tool 200 and is deformable (shown in hidden lines) to release the
valve support 100 from the tool 200 when the tool is moved in the
second axial direction 250 against an embedded support and the
force exceeds a predetermined threshold.
[0059] As shown in FIG. 5, in an example of a tool 200 that can be
used for delivery of the support during open heart surgery, a
basket 220 is connected at its broad end to a set of stiff wires or
other rigid projections 216 that are splayed from a long shaft 210
having a handle 212 at the operator's end 214. Thus the projections
216 connect the shaft 210 to the basket 220 and transfer pulling or
pushing force between the shaft and the basket (and in turn to the
support).
[0060] The example of the basket shown in FIG. 5 includes a tapered
body 222 having a network of interconnected struts 224 defining an
array of openings 226 together forming a tapered semi-rigid net. In
this example, the basket (which we also sometimes refer to as a
delivery head) 220 has a rounded tip 228. The head 222 tapers
radially outwardly with distance along a longitudinal axis 234 of
the head 220 from the tip 228 towards the operator. The broad end
232 of the tapered body 222 is firmly attached to the projections
216, which taper in the opposite direction from the taper of the
basket. The net formed by the struts 224 is semi-rigid in the sense
of having enough stiffness to permit the operator to force the
valve support against the heart tissue to cause the barbs of the
hooks of the support to penetrate the tissue, and enough
flexibility to permit the head-end basket to be everted when the
operator pulls on the handle to evert the basket and release the
support from the basket.
[0061] In some implementations, the shaft 210 defines a lumen 236
extending between the heart valve end 218 of the shaft 210 and the
handle 212. A wire 238 is arranged to move freely back and forth
within the lumen 236. The wire 238 has one end 240 that extends
from the handle 212 and an opposite end 242 that is connected to
the inside of tip 228. The wire 238 can be pulled (arrow 244) to
cause the delivery head 220 to collapse (hidden lines) and evert
radially inwardly starting at the tip 228 as mentioned earlier.
[0062] Returning to a more detailed discussion of FIGS. 1A through
1E, the operator begins the delivery of the support by pushing the
tapered end 230 of the head basket 220 into the valve 16 (e.g., the
tricuspid valve) to cause the valve leaflets 14 to spread apart.
The tip 230 is small and rounded which makes it relatively easy to
insert into the valve without requiring very precise guidance.
Because the head-end basket is tapered, by continuing to push, the
operator can cause the annulus 18 of the tricuspid valve 16 to
expand in size and to conform to a desired shape, typically
circular. During insertion, because of its symmetrical taper, the
head-end basket tends to be self-centering. The taper of the basket
220 translates the insertion force in direction 248 into a radial
force that causes the annulus 18 to expand and temporarily assume a
desired shape (and a larger than final diameter).
[0063] As the operator continues to push on the tool, the ring of
barbs of the hooks touch and then enter (pierce) the heart tissue
along a ring of insertion locations defined by the outer periphery
of the annulus, and the sharp free ends of the hooks enter and seat
themselves within the tissue, much like fish hooks. Depending on
how the operator guides the tool, the basket can be oriented during
insertion so that essentially all of the hooks enter the tissue at
the same time. Or the tool could be tilted during insertion so that
hooks on one side of the support enter the tissue first and then
the tool delivery angle could be shifted to force other hooks into
the tissue in sequence.
[0064] Generally, when the number of hooks is relatively small (say
between 6 and 20, comparable to the number of sutures that the
physician would use in conventional stitching of a ring onto an
annulus), it is desirable to assure that all of the hooks penetrate
the tissue and are seated properly.
[0065] Once the hooks are embedded in the tissue, the operator
pulls on the near end 240 of wire 238 to cause the basket 220 to
collapse, evert, and be drawn out of the valve 16. Eventually, the
everted portion of the basket reaches the valve support 100. By
further tugging, the operator causes the body 110 of the support
100 to roll about its central axis (as in the o-ring example
mentioned earlier) which causes the hooks 120 to embed more firmly
in the tissue of the annulus 18 of the valve 16.
[0066] Using a final tug, the operator breaks the connections
between the tool 200 and the valve support 100 and removes the tool
200, leaving the valve support 100 in place. As the everting basket
220 passes the points of connection 246, the retaining forces
exerted by the embedded hooks 120 of the support body 110, acting
in direction 248, exceed the forces exerted by the withdrawing
basket 220 on the support body 110 (through the connections 246),
acting in direction 250, thereby causing the connections 246 to
break or release, in turn releasing the support 100.
[0067] The tool 200 is then withdrawn, allowing the valve support
100, along with the annulus 18, to contract to the long-run
configuration.
[0068] In implementations useful for delivery of the support
percutaneously, as shown in FIG. 6A, the delivery head 220a can be
made, for example, from a shape memory alloy, such as Nitinol,
which will allow the body 222a to be collapsed radially toward the
longitudinal axis 234a prior to and during delivery of the head
from a percutaneous entry point (say the femoral vein) into the
heart. The delivery head 220a is biased towards the expanded,
tapered configuration shown in FIG. 6A. Thus, the delivery head
220a, in the form of a tapered semi-rigid net, is connected to a
catheter shaft 210a through projections 216a that splay radially
outwardly from the catheter shaft 210a and taper in a direction
opposite the taper of the delivery head 220a. (Here we refer to the
delivery head as the head-end basket.)
[0069] The projections 216a are resiliently mounted to the catheter
shaft 210a and are biased towards the expanded, tapered orientation
shown, for example, by spring biased projections 216b shown in FIG.
6B. The projections 216a include springs 278, e.g., torsion springs
(as shown), mounted to the catheter shaft 210a and forming a
resilient connection.
[0070] A wire 238a slides within a lumen 236a of the shaft 210a in
a manner similar to the one described earlier.
[0071] The tool 200a also includes a sheath 280 in which the
catheter shaft 210a can slide during placement of the support. The
sheath 280, the catheter shaft 210a, and the wire 238a are all
flexible along their lengths to allow the tool 200a to be deflected
and articulated along a blood vessel to reach the heart and to
permit manipulation of the delivery head once inside the heart.
[0072] To deliver the support percutaneously, as shown in FIG. 7A,
when the delivery head is prepared for use, the sheath 280 is
retracted beyond the projections 216a, allowing the delivery head
220a to expand. The valve support 100 is then expanded to the
delivery configuration (either by hand or using an expansion tool)
and mounted on the tapered body 222a. The valve support 100 is
connected to the delivery head 220a using releasable connections,
e.g., breakable sutures and/or retaining elements (as described
earlier).
[0073] The sheath 280 is then moved along the catheter shaft 210a
towards the delivery head 220, causing the projections 216a and the
delivery head 220a to contract radially inwardly to fit within the
sheath 280, as shown in FIG. 7B. In the contracted configuration,
the tip 228a of the delivery head 220a bears against the end 282 of
the sheath 280. The rounded tip 228a may, e.g., provide easier
delivery and maneuverability in navigating the blood vessels to
reach the heart.
[0074] To deliver the support to the valve annulus, the end 230 of
the tool 200a is fed percutaneously through blood vessels and into
the right atrium 24 (FIG. 8A). The sheath 280 is then retracted,
exposing the valve support 100 and allowing the projections 216a,
the delivery head 220a, and the support 100 to expand, as shown in
FIG. 8A.
[0075] In steps that are somewhat similar to the open heart
placement of the support, the catheter shaft 210a is then advanced,
e.g., under image guidance, in the direction 248a along an axis 30
of the annulus 18. The operator forces the distal end 230a of the
self-centering delivery head 220a into the valve 16 (FIG. 8B) using
feel or image guidance, without actually seeing the valve 16.
[0076] Once the tip is in the valve 16, the operator pushes on the
end 214a of the catheter shaft 210a to force the tool further into
the valve 16. This causes the tapered body 222a of the delivery
head 220a to restore the shape of the annulus 18 to a circle or
other desired shape (such as the distinctive "D" shape of a healthy
mitral valve). The tool 200a tends to be self-centering because of
its shape. The net-like construction of the delivery head 220a (and
the head used in open heart surgery, also) allows blood to flow
through the valve even while the delivery head 220a is
inserted.
[0077] As tool 200a reaches the position at which the support hooks
touch the annulus, by giving an additional push, the operator
drives the hooks 120 of the valve support 100 together into all of
the annular locations at which it is to be attached, as shown in
FIG. 8C. In some examples, it may be possible for the operator to
tilt the delivery head deliberately to cause some of the hooks to
penetrate the tissue before other hooks. The configuration of the
valve support 100 and the tool 200a and the manner of temporary
attachment of the support 100 to the tool 200a tend to assure that
the hooks 120 will penetrate the valve 16 at the correct positions,
just along the outer edge of the annulus 18.
[0078] Once the valve support 100 has been attached to the valve
16, the operator pulls on the proximal end 240a causing the
delivery head 220a to evert (hidden dashed lines) and be drawn out
of the valve 16 (shown in FIG. 8D). Eventually the everted portion
of the tool 200a reaches the valve support 100. By further tugging,
the operator causes the torus of the support 100 to roll around its
periphery which jams the free ends of the hooks 120 securely into
the annulus 18 of the valve 16, as illustrated in FIG. 8E, seating
the support permanently and permitting later growth of tissue
around the support 100. The depth and radial extent of each of the
placed hooks 120 can be essentially the same as a conventional
suture so that their placement is likely to be as effective and
familiar to the operator and others as conventional sutures.
[0079] Using a final tug, the operator breaks the connections 246
between the tool 200a and the valve support 100 and retracts the
catheter shaft 210, leaving the support 100 in place. The catheter
shaft 210 is retracted to a position beyond the valve annulus 18
and the wire is advanced in the first direction allowing the
delivery head 220a to assume its original tapered shape (FIG. 8F).
The catheter shaft 210a is then retracted into the sheath 280 (FIG.
8G), and the tool 200a is withdrawn.
[0080] In some examples, as shown in FIGS. 8H and 8I, the tip 228a
of the tool 200a, when everted, has a compressed dimension that is
smaller than an internal diameter 284 of the sheath 280, permitting
the catheter shaft 210a to be retracted directly into the sheath
280 after deployment, with the everted tip held within the
collapsed delivery basket, as shown in FIG. 8I.
[0081] With the tool 200a withdrawn, the valve support 100
contracts, reshaping the annulus 18 such that the valve leaflets 14
coapt to prevent a backflow of blood during systole.
[0082] Other implementations are within the scope of the
claims.
[0083] For example, distortion of either the tricuspid valve or
mitral valve can be corrected. For tricuspid valve repair, the
hooks can be arranged around only about three-quarters of the
support and therefore the annulus. During the placement procedure,
the operator will rotate the support to position the portion of the
support having hooks. For mitral valve repair, the hooks can cover
the entire periphery of the annulus. In this scenario, the hooks
are arranged around the full circumference of the support.
Alternatively, the hooks can cover only the posterior section of
the annulus of the mitral valve. In this scenario, the hooks can be
arranged around two-thirds of the support. Similarly to the
tricuspid valve example, the operator will position the portion of
the support having hooks against the posterior section of the
mitral valve annulus. Further, for mitral valve repair, a back-up
valve can be provided as part of the delivery tool to maintain
heart function during the delivery procedure. Materials other than
shape memory materials may be used as the material for the support
body, and other ways can be used to force the support back to a
desired size following expansion, including, for example,
cross-bars that span the opening of the support.
[0084] In addition, the left atrial appendage of the heart can be
closed by a similar technique. For example, the tool can be pushed
into an opening of an atrial appendage causing the opening to
assume a predetermined shape. The tool can continue to be pushed in
order to embed the hooks of the expanded support into the periphery
of the opening of the appendage. The tool can then be withdrawn,
releasing the support, and allowing the support to contract. The
support can have a relatively small contracted diameter such that,
when the tool is withdrawn, releasing the support, the support can
contract to a relatively small size, effectively closing off the
appendage.
[0085] In addition to the open heart and percutaneous deployment
procedures, the valve support can also be deployed through the
chest.
[0086] The head-end of the tool need not be a basket, but can take
any form, mechanical arrangement, and strength that enables the
valve annulus to be forced open to a shape that corresponds to the
shape of the support. The basket can be made of a wide variety of
materials. The basket can be held and pushed using a wide variety
of structural mechanisms that permit both pushing and pulling on
the support both to seat and embed the support in the annulus
tissue and disconnect the support from the tool.
[0087] The tool need not be conical.
[0088] The support could take a wide variety of configurations,
sizes, and shapes, and be made of a wide variety of materials.
[0089] The hooks could be replaced by other devices to seat and
embed the support using the pushing force of the tool.
[0090] The hooks of the support need not be embedded directly in
the annulus but might be embedded in adjacent tissue, for
example.
[0091] The support could take other forms and be attached in other
ways.
[0092] In FIG. 9A, the support body 110a can be a torus in the form
of a helical spring (as mentioned earlier). Such a support body can
have a native circumference 116 on the order of ten centimeters in
its contracted state, and a proportional native diameter 114. The
circumference can be selected based on the physical requirements of
a particular patient.
[0093] A close-up view of a fragment of this support body, FIG. 9B,
shows that some implementations have a number (e.g., a large or
very large number, for example, as few as say 15, or 100, and up to
hundreds or even thousands) of burr hooks 120a attached to an outer
surface 111 of the support body 110a. In the example shown in FIG.
9B, the helical support body is wound from a flat strip that has
the outer surface 111 and an inner surface 117. Although FIG. 9B
shows the burr hooks attached only to the outside surface, burr
hooks could also be attached to the inner surface for manufacturing
reasons or for other purposes.
[0094] The burr hooks, which are small relative to the body, are
each configured to partially or fully pierce annular tissue when
the part of the body to which the burr hook is attached is pushed
against the tissue.
[0095] As shown in FIG. 9C, in some examples, each burr hook 120a
has a sharp free end 122a for piercing tissue and at least one
barbed end 128a, 128b (two are shown in FIG. 9C) for keeping the
burr hooks embedded in tissue. Each burr hook also has an end 124a
that is attached to the surface of the support body. Once the
support (we sometimes refer to the support structure simply as the
support) is in contact with heart tissue, the embedded burr hooks
hold the body in a proper position and configuration on the
annulus. Burr hooks can be attached to the surface of the support
body using glue, cement, or another type of adhesive, or formed
from the support body as part of an industrial process, such as
molding, etching, die cutting, welding, or another process, or can
be attached by a combination of these techniques. Different burr
hooks on a given support can be attached by different
mechanisms.
[0096] Each burr hook 120a can be structured and attached so that
the free end 122a points in a direction 122b perpendicular (or some
other selected effective direction, or deliberately in random
directions) to the body surface 111. In some cases, the burr hook
can be curved. A barbed end 128a could be located on a concave edge
113 (FIG. 9D) or a convex edge 115 (FIG. 9E) of a curved burr
hook.
[0097] The burr hooks bear a resemblance to burr hooks on natural
plant burrs. A different kind of attachment device could be used by
analogy to metal tipped hunting arrows in which a sharp point has
two broad and sharp shoulders that cut the tissue as the point
enters. The tips of the two shoulders serve a similar function to
the barbs, keeping the arrow embedded once it enters the
tissue.
[0098] In some implementations, the burr hooks on a support body
have two or more (in some cases, many) different shapes, sizes,
orientations, materials, and configurations. By varying these
features, for example, the orientations of the burr hooks, it may
be more likely that at least some of the burr hooks will become
embedded in the tissue, no matter how the support body is oriented
at the moment that it comes into contact with the annulus. Varying
the number, orientation, and curvature of the hooks may make it
more likely that the support body will remain in place. For
example, in such a support, a force applied to the support body in
a particular direction may unseat or partially unseat some of the
burr hooks by disengaging the barbed ends from the tissue, but the
same force may not affect other burr hooks that have barbed ends
oriented in a different direction or in a different configuration
than the unseated burr hooks. The force applied to seat the support
may cause some burr hooks to embed more securely than other burr
hooks.
[0099] In use, typically not all of (in some cases not even a large
portion of) the burr hooks will embed themselves in the tissue when
the support body is pushed against the tissue, or remain embedded
after placement. As shown in FIG. 9F, there are enough burr hooks
arranged in an appropriate way so only a fraction of the total
hooks need be embedded in annular tissue (and in some cases only in
certain regions) to create a physical bond to keep the support body
properly in place. The proportion of burr hooks on a support that
need to embed securely in the tissue could range from 1% to 10% or
40% or more. The averaging spacing of the successfully embedded
burr hooks could range from, say, one burr hook per millimeter of
support body length to one burr hook per two or three or more
millimeters (or more) to secure the support appropriately. When
burr hooks are grouped rather than arranged evenly on the support,
the percentages of and distances between successfully embedded
hooks may differ.
[0100] When the burr hooks come into contact with the annular
tissue during delivery, some 131, 133, but not necessarily all, of
the burr hooks pierce the tissue and (when a retracting force is
applied to the delivery tool) their barbs grip the tissue. Of the
remaining burr hooks, some 135, 137 may (because of the contours of
the tissue, for example) not even come into contact with the
tissue, and others 139, 141 may not come into contact with the
tissue with sufficient force or in the right orientation to pierce
the tissue and have their barbs seat securely in the tissue. Some
of the burr hooks 143, 145 may penetrate the tissue but fail to
grip the tissue. Some of the burr hooks 147, 149 may only penetrate
the tissue at the barbed end 128a, and not with respect to the free
end 122a, providing a physical bond that may be weaker than one in
which the free end has been embedded in the tissue. For some or
many or most of the burr hooks that enter the tissue, however, the
barbed ends 128a seat properly and resist forces in the direction
151 that would otherwise unseat the burr hook. Even though a
wrenching force applied to a particular burr hook in direction 151
could still be large enough to unseat the barbed end, overall the
combination of many burr hooks embedded in tissue tends to keep the
support body set in place and in the proper configuration. Over
time, some of the burr hooks that were not embedded when the
support was placed may become embedded, and some of the burr hooks
that were embedded when the support was placed may become
unseated.
[0101] The resistance provided by each of the barb or barbs to
removal of a given burr hook from the tissue may be relatively
small. However, the aggregate resistance of the burr hooks that
successfully embed themselves will be higher and therefore can
reliably keep the support body in place and the annulus of the
valve in a desirable shape. In addition, because there are a number
(potentially a very large number) of small burr hooks spread over a
relatively large area, the stress on any part of the tissue of the
annulus is quite small, which helps to keep the support body
properly seated and the valve shape properly maintained along its
entire periphery, all without damaging the tissue. The fact that a
large number of burr hooks at close spacings may become embedded
along the length of the support means that the support may become
attached to the annulus more evenly and continuously than might be
the case with the relatively smaller number of hooks described
earlier, and therefore perform better.
[0102] With respect to the implementations described beginning with
FIG. 1A, the implementations shown beginning at FIG. 9A tend to
have more and smaller hooks not all of which need to become
embedded successfully. A common concept between the two
arrangements is that the hooks penetrate by being pushed into the
tissue and have retaining elements that become securely embedded in
the tissue when a pulling force is applied at the end of the
placement process. The two concepts are not mutually exclusive.
Supports like those shown in FIG. 1A could also have burr hooks and
supports like those shown in FIG. 9A could also have hooks of the
kind shown in FIG. 1A. Placement of the support could rely on a
combination of both kinds of hooks.
[0103] Each burr hook can be formed of a biologically compatible
material such as platinum, gold, palladium, rhenium, tantalum,
tungsten, molybdenum, nickel, cobalt, stainless steel, Nitinol, and
alloys, polymers, or another material. As for the hooks shown
beginning with FIG. 1A, the hooks can also be formed of a
combination of such materials. An individual support body may
exhibit burr hooks having a range of compositions. Some of the burr
hooks attached to a support body may be composed of one material or
combination of materials, and some of the burr hooks may be
composed another material or combination of materials. Each burr
hook may be unique in composition. Further, some parts of a burr
hook may be composed of one set of materials, and other parts may
be composed of another set of materials. In some examples, the
region of the burr hook at the barbed end is composed of one set of
materials, alloys, polymers, or mixtures, and the region of the
burr hook at the free end is composed of another set of materials,
alloys, polymers, or mixtures, and the rest of the burr hook is
composed of a further set of materials, alloys, polymers, or
mixtures. FIG. 9G shows an example burr hook that only has one
barbed end 128a. The burr hook extends from an attached end 124a to
a free end 122a along the path of a principal axis 920 that (in
this case) is perpendicular to the support body surface 111. The
barbed end spans a length 904 from the burr hook's free end 122a to
the barbed end's free end 906. This free end 906 forms a point
spanning an acute angle 910 and the barbed end 128a spans an acute
angle 911 to grab the tissue in response to any force that would
otherwise pull an embedded burr hook away from tissue.
[0104] The length 901 of each burr hook could be between about 1
and 12 millimeters, as measured from the attached end 124a to the
free end 122a along the principal axis. Each barbed end could
extend a distance 902 from the burr hook lesser or greater than a
principal width or diameter 903 of the burr hook as measured at the
attached end. The cross-section of the body of the burr hook could
be flat or cylindrical or ovoid or any other of a wide variety of
shapes.
[0105] Different burr hooks may be placed on the support body
surface in different sizes and configurations. For example,
different burr hooks may have different lengths and different
numbers and placement of barbed ends. As shown in FIG. 9H, for
example, a portion of support body surface 111 contains burr hooks
120a that each have two barbed ends 128a, 128b facing in a first
direction 950 and shorter burr hooks 120b each having one barbed
end 128a facing in a second direction 951. Also, the burr hooks may
be arranged on the body surface in various densities and patterns
of distribution. For example, as shown in FIG. 9I, the burr hooks
may be placed on the surface of the body in repeating rows 930. As
shown in FIG. 9J, the burr hooks may be placed on the surface in
rows of different lengths and densities 931, 932. As shown in FIG.
9K, the burr hooks may be placed on the surface along arc
formations 933. As shown in FIG. 9L, the burr hooks may be placed
on the surface as cluster formations 934. As shown in FIG. 9M, the
burr hooks may be distributed randomly 935. Other patterns may also
be used.
[0106] A single support body can include a wide variety of patterns
of burr hooks on its surface, because the physical characteristics
of a particular heart valve may mean that the valve tissue is
either more receptive or less receptive to a particular pattern of
burr hook distribution. Some patterns may be more effective on some
types of tissue, and other patterns may be more effective on other
types of tissue.
[0107] In addition, as shown in FIG. 9N, the burr hooks need not be
present at the points where the body 110a contacts the delivery
tool 220, including in the area near the rigid fingers 256, 258.
This tends to prevent the burr hooks from causing the support body
to stick to the tool.
[0108] As shown in FIG. 9O, any two burr hooks may be placed at a
distance 905 from each other greater than or less than the length
901, 901a of either one.
[0109] As shown in FIG. 9P, when a support is formed helically, the
ring can be considered to have a front side 961 (which faces the
valve when the support is delivered), and a back side 960 that
faces away from the valve. In some examples, the support body 110a
does not have burr hooks 120a on the back side 960. In these
implementations of the support body, the back side 960 is covered
by a sleeve 963. After the support body has been attached to the
annulus, the sleeve assists in the long-term process of integration
with valve tissue. Over a period of time, heart tissue will attach
to the support body as part of the process of healing. The sleeve
is made of a material that allows this process to occur faster than
without the sleeve. For example, the sleeve may be composed of a
porous material, which allows tissue to grow into the sleeve, thus
securing the support to the tissue more effectively than without
the sleeve. The sleeve material may be a thermoplastic polymer such
as Dacron (polyethylene terephthalate). The sleeve material may
alternatively be a metal or another type of material. The sleeve
can be placed on the support body at a location other than the back
side. For example, the sleeve could be placed on the inner side 965
of the body, with burr hooks remaining on the outer side 964.
[0110] The sleeve is formed as a half-torus in this example, but
could have a wide variety of other configurations. Such a sleeve
may be used with any kind of support, including the one shown
beginning in FIG. 1A, could cover all or only part of the support,
and could cover portions of the support that include hooks or barb
hooks or both. In the latter case, the hook may be arranged to
penetrate the sleeve during setup and before the support is placed
into the heart. The sleeve could also cover a portion of the
support meant to contact delicate or sensitive tissue, such as the
AV node. In this case, the sleeve is made of a material that is
less likely to damage or interfere with the operation of the
delicate or sensitive tissue, as compared to other materials that
may be used in the support.
[0111] Using burr hooks may make attaching the support faster,
simpler, more reliable, and easier than for the larger hooks
described earlier. The delivery tool operator may not need to apply
as much force as might be necessary to embed larger hooks in the
annular tissue. In some cases, the barbs would not need to be
rotated as described for the larger hooks in order to embed them
securely. The operator need not be concerned whether all of the
burr hooks have become embedded. Once the operator has determined
that the support body has made contact with the tissue and by
inference that many of the burr hooks have become attached, the
operator can tug on the support to confirm that it has been seated
and then release the support body from the delivery tool using one
of the mechanisms described earlier. Because of the ease of
positioning, the procedure could be performed easily in a
non-surgical context, such as in a catheterization laboratory.
[0112] As shown in FIGS. 13A-13D, in the catheterization context,
for a burr-hook support or any other kind of support being placed,
the catheter may include a balloon 228b at the tip of the delivery
tool. The balloon remains deflated as the catheter is passed
through the patient's blood vessels into the heart, as in FIG. 13A.
When the tip of the catheter reaches the heart, the balloon can be
inflated, shown in FIG. 13B. The inflated balloon floats in the
blood being pumped through the heart and (along with the delivery
tool) is carried easily and to some extent automatically toward and
into the valve that is to be repaired. The balloon can continue to
move beyond the valve annulus, and, when located as shown in FIG.
13C, supports the distal end of the catheter while the operator
supports the proximal end of the catheter. The shaft of the
catheter then serves as a "rail" supported at both ends and along
which operations involving the delivery tool and the support can be
performed with confidence that the rail is being held generally on
axis with the valve.
[0113] In some of the examples described earlier, the annulus of
the heart valve is expanded to the desired shape by pushing a
conical surface, such as the basket, along the axis of and into the
heart valve. Whether the delivery is done in the context of open
heart surgery or in a catheterization lab, or elsewhere, the
pushing of the conical surface into the annulus can be supplemented
by or replaced by a technique in which the expansion of the annulus
is done after the delivery tool is inserted into the valve.
[0114] FIG. 9A shows one diameter of the support body, the native
(long-term configuration) diameter 114. Recall that this diameter
is different from the diameter in the delivery configuration. The
former diameter 114 is, as shown in FIG. 9Q, smaller than the
latter diameter 202 of the delivery tool at the point of support
body attachment 247. When the support body is placed on the
delivery head 220, the coils of the helical spring stretch outward
as the body expands to fit on the tool.
[0115] During delivery, shown in FIGS. 13A-13D, when the support
body has been attached to the annulus 18, the operator releases the
support from the delivery tool. FIG. 13D shows that, in the absence
of the outward force previously applied by the delivery tool, the
coils of the helical spring contract inwardly 1308 so that the
support body returns to a final diameter 1309 of approximately its
native diameter. Referring again to FIG. 1H, recall that because
the annulus is attached to the support body, the support body will
also pull the annulus inward, reforming the annulus to a desired
smaller diameter 209.
[0116] If the support body is made of a material or alloy that is
appropriately plastic, the support body may not fully contract to
its original native diameter. However, if the support body is made
of a shape memory alloy such as Nitinol, the memory effect of the
alloy will tend to cause the support body to contract to a diameter
nearly identical or identical to its original diameter.
[0117] As shown in FIG. 9R, the support body 110a may have other
portions bearing no burr hooks. As mentioned earlier, sensitive or
delicate tissue such as the AV node should not be punctured or
bound to hooks. In some examples, the support body 110a can have a
binding section 972 having burr hooks and a non-binding section 974
having no burr hooks. A non-binding section 974 of sufficient
length to abut the AV node spans an angle 975 between about 40 and
60 degrees of the support body circumference. The binding section
972 will span an angle 973 of the remaining circumference. In some
examples, a non-binding section 974 is covered in a sleeve made of
a material suited to contact the AV node or other sensitive
tissue.
[0118] As shown in FIG. 9S, the two sections 972, 974 can have
radiopaque markers 976, 977 indicating the borders between the two
sections. The markers 976, 977 are each in the shape of an arrow
pointing to the non-binding section. During delivery, an operator
can use the radiopaque markers 976, 977 to view the boundary of the
non-binding section 974 and position the non-binding section 974
against the AV node or other sensitive tissue.
[0119] As shown in FIG. 9T, the support body 110a can have multiple
sections 974, 978 having no burr hooks. In some situations, the
operator may be limited in the degree to which the delivery head
can be rotated. In this example, the operator has multiple options
for positioning the support body in order to avoid puncturing the
AV node, and the operator would not have to rotate the delivery
head more than about 90 degrees in any direction.
[0120] Two non-binding sections are shown, but the support body can
also have three or more of these sections. The non-binding sections
974, 978 span angles 975, 979 between about 40 and 60 degrees of
the total circumference. In the example of two non-binding
sections, there will also be two binding sections 980, 982 spanning
angles 981, 983 of the remaining two lengths of circumference.
[0121] As shown in FIG. 9U, the feature of the support body 110a
that should abut the AV node can take the form of an open section
990. As with the non-binding section described above, the open
section 990 may span an angle 995 between about 40 and 60 degrees
of the circle defined by the support body 110a, while the support
body spans the remaining angle 993. The open section 990 can also
have radiopaque markers on the open ends 992, 994 of the support
body 110a to assist an operator in positioning the open section 990
against the AV node or other sensitive tissue.
[0122] As shown in FIGS. 10A-10D, the delivery head 220 can include
a sheath 280a for covering the support body during insertion. FIGS.
10A and 10B show the sheath in a side section, and FIGS. 10C-10D
show the sheath as well as the delivery head in a cross-section at
A-A in FIG. 10B. The sheath 280a wraps around the delivery head
220, including the support body 110a, so that the burr hooks do not
accidentally puncture or attach to any other tissue or devices
prior to reaching the annulus. The sheath is made of a flexible
material, such as rubber, silicone rubber, latex, or another
biologically compatible material or combination of materials. The
sheath can also be made of the same material or materials as the
catheter. Recall that one implementation of the sheath is shown in
FIGS. 6A-6B and described in the corresponding text. Other
implementations of the sheath are possible.
[0123] For example, the implementation of the sheath 280a shown in
side section in FIG. 10A is kept in place by attachment to an
elastic retainer ring 1000 and a crossbar 1010 permanently affixed
through and extending outward from the catheter shaft 210
perpendicular to the longitudinal axis 234. The retainer ring 1000
is positioned closer to the operator and farther from the distal
end than is the support body 110a, and the crossbar 1010 is
positioned farther from the operator and closer to the distal end
than is the support body. This sheath 280a is permanently attached
1002 to the retainer ring 1000. The sheath 280a is also attached to
the crossbar temporarily at holes 1030, 1032 (visible in FIG. 10B)
sized to fit the projecting tips 1020, 1022 of the crossbar
1010.
[0124] As shown in FIGS. 10B-10D, after insertion of the catheter
into the valve and when the delivery head 220 is expanded in
preparation for attaching the support body 110a, the combination of
the retainer ring and crossbar allows the sheath to automatically
detach from the crossbar and retract upward away from the support
body as part of the expansion procedure. The process by which this
happens is as follows.
[0125] Referring to FIG. 10B, when the delivery head expands
outward 1006, the diameter 1008 of the delivery head at the
original point of retainer ring attachment 1012 increases to a
diameter greater than the diameter 1009 of the retainer ring 1000.
As a result, the retainer ring rolls upward 1004 from a point 1012
to a point 1005 on the delivery head of smaller diameter. As the
retainer ring rolls, it pulls the distal end of the sheath in the
same upward direction 1004 along the delivery head 220 and away
from the support body 110a. Part of the sheath 280a wraps around
the ring as part of the rolling process; in a sense, the retainer
ring is "rolling up" the sheath, in the fashion of a scroll
wrapping around a roller. The retainer ring 1000 is rubber or
another biologically-compatible material with sufficient elasticity
to allow the ring to roll up the expanding delivery head.
[0126] When the delivery head 220 expands, the sheath 280a is also
released from the crossbar. A cross-section of the delivery head
220 including the crossbar 1010 is shown in FIG. 10C. When the
delivery tool is in transit to a heart valve, the delivery head 220
is in the collapsed configuration. The sheath 280a has holes 1030,
1032 configured to allow the crossbar 1010 to pass through, holding
the distal end of the sheath to the crossbar. Because the crossbar
projects beyond the sheath, the ends 1020, 1022 of the crossbar are
rounded and smooth to prevent the crossbar from piercing or tearing
any tissue that it contacts before the delivery head reaches its
destination. Once the delivery head is positioned near or inside a
heart valve and begins expanding outward 1006 from the shaft 210,
the delivery head pushes the sheath 280a outward.
[0127] During the expansion process, as shown in FIG. 10D, the
crossbar remains in place and does not extend outward or change
configuration, because the crossbar is permanently and securely
attached to the shaft 210. As a result, the delivery head pushes
the sheath beyond the tips 1020, 1022 of the crossbar, releasing
the sheath from the crossbar. Thus, the sheath can move freely when
the retainer ring rolls upward along the delivery head, as
described above. The crossbar 1010 may be made of any of the
materials used in the delivery tool, or another
biologically-compatible material, provided that the crossbar is
sufficiently rigid to keep the sheath 280a in place, as
described.
[0128] FIG. 11A shows another version of the delivery head 220b.
This version differs slightly from the versions of the delivery
head already shown. Specifically, in this version 220b, the rigid
projections 216b are composed of an outer sleeve 1140 that encloses
an inner arm 1142 attached to the shaft 210b by a hinge 1144. When
this version of the delivery head expands, the sleeve 1140 extends
from the inner portion 1142, and when the delivery head contracts,
the sleeve withdraws along the length of the inner arm. This
version of the delivery head is used in FIG. 11A to demonstrate the
use of a tightening wire 1100, but this tightening wire can be used
with other versions of the delivery head as well.
[0129] As shown in FIG. 11B, this tightening wire 1100 is threaded
into and back out of a hole 1103 at the operator end 214b of the
delivery tool 200b. In doing so, the wire traverses the interior of
the shaft 210b of the delivery tool 200b. The ends of the wire
exterior to the operator end 214b form a loop 1102 to be
manipulated by an operator. This wire 1100 can be used to activate
a mechanism to adjust the shape of the support body 110a to a small
degree, with the goal of contracting the final diameter 1309, an
example of which is shown in FIG. 13B. Referring back to FIG. 11A,
at the other end of the delivery tool 200b, the wire exits the
shaft 210b at a hole 1105 placed at a point above the delivery head
220b. The wire extends down the side of the delivery head 220b,
guided by hoops 1120, 1122. As shown in FIG. 11C, the wire is
threaded along the interior of the helical coil 1150, 1152 of the
support. At the position 1164 where the wire has completed a
circumference of the support body 110a, the wire returns up the
side of the delivery head and back into the shaft.
[0130] FIG. 11C also shows hoops 1124, 1126 that are placed on the
struts 224b of the delivery head at regular intervals to keep the
wire properly positioned. At the position 1164 where the wire meets
itself and returns up the side of the delivery head, spools 1130,
1132, 1134, 1136 attached to the strut 224b guide the wire and
prevent the wire from scraping against 1160, 1162 the helical loops
1150, 1152 at the wire exit region. The end of the wire that
re-enters the hole 1105 (FIG. 11A) continues back up the shaft
alongside itself, and exits the delivery tool (FIG. 11B) to form
the loop 1102 by connecting with the other end.
[0131] When the support body 110a is firmly seated at the heart
valve annulus 18 (for example, in the scenario shown in FIG. 13C),
an operator can pull 1104 the loop 1102 (FIG. 11B) to reduce the
final diameter of the support. When pulled, the wire tightens; as
shown in FIG. 11C, this brings 1106 the coils 1150, 1152 of the
support closer together.
[0132] The adjusted circumference becomes permanent as the burr
hooks of the support embed themselves in the annular tissue.
Although some burr hooks will already have been embedded, the
tightening procedure will pull out some of those burr hooks and
embed other burr hooks in the tissue. This "bunches" annular tissue
closer together. FIG. 11D shows an example of a portion of the
support body 110a attached to the periphery 121 of an annulus
before the support body is tightened. As shown in FIG. 11E, after
tightening, the support body 110a pulls the tissue at the periphery
121 closer together. The final diameter of the annulus will be
slightly smaller due to this bunching effect. Once the delivery
head is removed, the support body, and thus the attached annulus,
will contract to the desired size.
[0133] Referring to FIG. 11F, to detach the wire from the support
body 110a, the delivery head 220b has a blade 1170 attached to one
of the two rigid fingers 256b, 258b that keep the support body in
place. When the rigid finger 256b pulls away from the support body
110a after the support body is in place, the cutting segment 1172
of the blade structure severs the wire. The operator may pull the
external loop after the wire has been severed to keep the stray
ends of the wire from moving freely outside of the delivery tool
when the tool is being removed from the annulus.
[0134] As shown in FIGS. 12A through 12C, a delivery tool 200b for
use in (but not only in) a catheterization context shares elements
in common with the delivery tools discussed earlier, including the
shaft 210b, collapsible conical head end basket 220b, set of struts
224b, and operator end 214b. This delivery tool 200b allows the
operator to expand or contract the collapsible conical head-end
basket 220b radially from a collapsed (closed) configuration (shown
in FIG. 12A) to an expanded (open) configuration (shown in FIG.
12B), much in the way that an umbrella can be opened. For this
purpose the basket can include a set of spars 1210, 1212, 1214,
1216, 1218 arranged about the axis, as shown in FIG. 12C. Referring
back to FIG. 12B, each spar has one hinged end 1220, 1222 connected
to a central collar 1200 that can ride up 1202 and down 1204 along
a central shaft 1250 of the basket. Its other hinged end 1230, 1232
is connected to the hinged 1240, 1242 struts 224b of the basket in
such a way that when the opening and closing mechanism is
manipulated 1208 by the user to cause the collar 1200 to move back
and forth along the shaft 1250, the spars 1210, 1220 force 1206 the
basket open or closed, akin to the mechanism of an umbrella. The
operator end 214b of the delivery tool has a twist or slide control
1150 that enables the operator to control the collar. In FIG. 12B,
the control is a slide control, and can be slid downward, for
example. In this way, the annulus can be expanded to the desired
shape by radial forces 1206 that are not imposed by moving the
entire basket linearly along the valve axis. Instead the basket is
moved into the desired position linearly along the valve axis and
then the annulus is expanded to its desired shape. The radial
forces could also be imposed by a combination or sequence of moving
the entire basket axially and expanding the basket laterally.
[0135] As shown in FIG. 13A, radiopaque measurement marks 1310,
1312 can be placed on the shaft or basket at regular spacings
according to a standard measurement unit (e.g., one mark per
centimeter). The marks can be used to determine the distance that
the delivery tool has traversed inside the heart and the location
of the basket as it is inserted into the valve, allowing the
operator to place the basket at a good position along the axis of
the valve.
[0136] The placement of the support from the basket onto the
annulus can be done either as part of the operation of opening the
basket or following the opening of the basket. In the former case,
illustrated in FIGS. 13A through 13D, the basket would be inserted
into the valve to a point where the basket is adjacent to the valve
annulus. Simultaneously with the opening of the basket, burr hooks
on the outer periphery of the support would be forced radially into
the annulus tissue. In this method of placing the support, the
porous sleeve described earlier and shown in FIG. 9P would be
positioned on the inner periphery 965, away from the embedded
hooks.
[0137] In the other approach, akin to the process shown in FIGS. 1A
through 1D, the basket would be inserted into the valve so that the
support on the basket was positioned slightly upstream of the
location of the annulus. The basket would then be opened to force
the annulus into the desired shape, then the tool and basket would
be pushed slightly to force the support into place, embedding the
hooks.
[0138] In either approach, once the support is placed, the basket
would be at least partially closed, releasing the basket from the
support, and the tool would be withdrawn from the valve.
[0139] Further, in some implementations, a combination of the
approaches could be used. For example, the basket could be
partially opened, inserted into the annulus, and then fully
opened.
[0140] The approach of FIGS. 13A through 13D follows these
steps:
[0141] A. Position 1301 (FIG. 13A) the collapsed (closed) conical
head-end basket 220b of the delivery tool 200b at the medial axis
30 of the valve with the support adjacent the annulus. (The tool
and basket are shown in side view and the valve and annulus are
shown in sectional side view.)
[0142] B. Press a button 1302 on the operator end 214b to inflate a
balloon 228b (FIG. 13B) on the distal end 230b of the delivery
tool, allowing the delivery head 220b to float into the correct
position in the heart valve 16. If necessary, rotate the delivery
head to align any section of the support body not bearing burr
hooks, or any gap in the support body, or any portion that is
sheathed, with any section of the annulus abutting delicate or
sensitive tissue.
[0143] C. Slide 1208 or twist the control 1150 to expand 1306 the
basket bringing the support body 110a into contact with the
distorted annulus 18. The support bears burr hooks that embed
themselves in valve tissue at the periphery 121 of the annulus 18
upon contact, thus attaching the support to the tissue (FIG.
13C).
[0144] D. When the basket 220b has reached a desired diameter 1303,
the expanded heart valve support 110a forces the annulus 18 to
conform to a desired configuration (e.g., a circle) and to a size
that is larger (e.g., in diameter) than a desired final diameter of
the annulus. Optionally, pull 1104 the wire loop 1102 to tighten
the coils of the support body 110a to achieve a smaller final
diameter.
[0145] E. When the heart valve support is in its final position, to
break the tool away from the support attachments 246b, pull 1304
(FIG. 13D), allowing the support to contract 1308 to its final size
(including final diameter 1309) and shape and leaving the support
permanently in place to maintain the annulus in the desired final
configuration and size. Deflate 1311 the balloon 228b by pressing
the button on the operator end.
* * * * *