U.S. patent application number 13/282247 was filed with the patent office on 2012-02-16 for methods and apparatus for endovascular heart valve replacement comprising tissue grasping elements.
This patent application is currently assigned to SADRA MEDICAL, INC.. Invention is credited to Daniel Hildebrand, Amr Salahieh, Tom Saul.
Application Number | 20120041550 13/282247 |
Document ID | / |
Family ID | 45565387 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120041550 |
Kind Code |
A1 |
Salahieh; Amr ; et
al. |
February 16, 2012 |
Methods and Apparatus for Endovascular Heart Valve Replacement
Comprising Tissue Grasping Elements
Abstract
A method for endovascularly replacing a patient's heart valve
including the following steps: endovascularly delivering an anchor
and a replacement valve supported within the anchor to a vicinity
of the heart valve in a collapsed delivery configuration, the
anchor having grasping elements adapted to grasp tissue in a
vicinity of the heart valve; expanding the anchor, thereby rotating
the grasping elements; and grasping the tissue with the rotating
grasping elements.
Inventors: |
Salahieh; Amr; (Saratoga,
CA) ; Hildebrand; Daniel; (Menlo Park, CA) ;
Saul; Tom; (El Grandada, CA) |
Assignee: |
SADRA MEDICAL, INC.
Los Gatos
CA
|
Family ID: |
45565387 |
Appl. No.: |
13/282247 |
Filed: |
October 26, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11232441 |
Sep 20, 2005 |
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13282247 |
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10972287 |
Oct 21, 2004 |
7748389 |
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11232441 |
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10746240 |
Dec 23, 2003 |
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10972287 |
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Current U.S.
Class: |
623/2.36 |
Current CPC
Class: |
A61F 2230/0054 20130101;
A61F 2/885 20130101; A61F 2230/0078 20130101; A61F 2/2439 20130101;
A61F 2002/9528 20130101; A61F 2220/0008 20130101; A61F 2/2433
20130101; A61F 2/24 20130101; A61F 2/243 20130101; A61F 2/2436
20130101; A61F 2230/005 20130101; A61F 2220/0058 20130101; A61F
2250/0017 20130101; A61F 2/2418 20130101; A61F 2210/0057 20130101;
A61F 2/86 20130101; A61F 2210/0014 20130101; A61F 2210/0019
20130101; A61F 2220/0083 20130101; A61F 2220/0033 20130101; A61F
2250/0039 20130101; A61F 2250/0048 20130101; A61F 2/2412 20130101;
A61F 2250/006 20130101; A61F 2250/0069 20130101 |
Class at
Publication: |
623/2.36 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A method for endovascularly replacing a patient's native heart
valve, the method comprising: delivering an expandable anchor and a
replacement valve to a vicinity of the native heart valve, wherein
leaflet engagement elements extend distally from the anchor at a
location which is proximal to a distal end of the anchor;
sandwiching native valve leaflets between the distally extending
leaflet engagement elements and the anchor; and expanding the
anchor from a collapsed delivery configuration to an expanded
configuration to secure the anchor within the native heart valve;
and positioning a proximal end of the anchor further from a left
ventricle than the distal end of the anchor; wherein the
replacement valve allows the flow of blood through the replacement
valve in a first configuration and prevents the flow of blood
through the valve in a second configuration.
2. The method of claim 1 wherein expanding the anchor from a
collapsed delivery configuration to an expanded configuration
comprises allowing the anchor to self-expand to thereby sandwich
the native valve leaflets between the distally extending leaflet
engagement elements and the anchor.
3. The method of claim 1 wherein the leaflet engagement elements
extend generally parallel to the longitudinal axis of the
expandable anchor when the anchor is in the expanded
configuration.
4. The method of claim 1 wherein the expandable anchor and the
replacement valve are delivered as two separate elements, the
method further comprising deploying the expandable anchor and the
replacement valve in the vicinity of the native heart valve in two
different steps.
5. The method of claim 4 further comprising engaging the expandable
anchor and the replacement valve after they are deployed in the
vicinity of the native heart valve to secure the replacement heart
valve to the expandable anchor.
6. The method of claim 5 wherein the replacement heart valve
comprises an expandable support structure and replacement valve
leaflets, and wherein engaging the expandable anchor and the
replacement valve in the vicinity of the native heart valve
comprises coupling the expandable anchor and the expandable support
structure to secure the replacement heart valve to the expandable
anchor.
Description
CROSS-REFERENCE
[0001] This application is a continuation application of U.S.
application Ser. No. 11/232,441, filed Sep. 20, 2005, which is a
continuation-in-part application of U.S. application Ser. No.
10/972,287, filed Oct. 21, 2004, now U.S. Pat. No. 7,748,389, which
is a continuation-in-part of U.S. application Ser. No. 10/746,240,
filed Dec. 23, 2003, which is abandoned, all of which are
incorporated herein by reference in their entireties and to which
applications we claim priority under 35 USC .sctn.120.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to methods and apparatus for
endovascularly replacing a heart valve. More particularly, the
present invention relates to methods and apparatus for
endovascularly replacing a heart valve with a replacement valve
using an expandable anchor and tissue grasping elements.
[0003] Heart valve surgery is used to repair or replace diseased
heart valves. Valve surgery is an open-heart procedure conducted
under general anesthesia. An incision is made through the patient's
sternum (sternotomy), and the patient's heart is stopped while
blood flow is rerouted through a heart-lung bypass machine.
[0004] Valve replacement may be indicated when there is a narrowing
of the native heart valve, commonly referred to as stenosis, or
when the native valve leaks or regurgitates. When replacing the
valve, the native valve is excised and replaced with either a
biologic or a mechanical valve. Mechanical valves require lifelong
anticoagulant medication to prevent blood clot formation, and
clicking of the valve often may be heard through the chest.
Biologic tissue valves typically do not require such medication.
Tissue valves may be obtained from cadavers or may be porcine or
bovine, and are commonly attached to synthetic rings that are
secured to the patient's heart.
[0005] Valve replacement surgery is a highly invasive operation
with significant concomitant risk. Risks include bleeding,
infection, stroke, heart attack, arrhythmia, renal failure, adverse
reactions to the anesthesia medications, as well as sudden death.
2-5% of patients die during surgery.
[0006] Post-surgery, patients temporarily may be confused due to
emboli and other factors associated with the heart-lung machine.
The first 2-3 days following surgery are spent in an intensive care
unit where heart functions can be closely monitored. The average
hospital stay is between 1 to 2 weeks, with several more weeks to
months required for complete recovery.
[0007] In recent years, advancements in minimally invasive surgery
and interventional cardiology have encouraged some investigators to
pursue percutaneous replacement of the aortic heart valve. However,
the current devices suffer from several drawbacks.
[0008] First, many of the devices available today can become
mispositioned with respect to the native valve. This misposition
may arise for a number of reasons, such as: the valve slipping
after placement, improper initial positioning arising from the
difficulties associated with visualizing the relative positions of
the native and prosthetic valve, the difficulty in transmitting
tactile feedback to the user through the delivery tool. This is a
critical drawback because improper positioning too far up towards
the aorta risks blocking the coronary ostia of the patient.
Furthermore, a misplaced stent/valve in the other direction (away
from the aorta, closer to the ventricle) will impinge on the mitral
apparatus and eventually wear through the leaflet as the leaflet
continuously rubs against the edge of the stent/valve.
[0009] Moreover, some stent/valve devices simply crush the native
valve leaflets against the heart wall and do not grasp or engage
the leaflets in a manner that would provide positive registration
of the device relative to the native position of the valve. This
increases an immediate risk of blocking the coronary ostia, as well
as a longer-term risk of migration of the device
post-implantation.
[0010] Another drawback of the devices known today is that during
implantation they may still require the patient to be on life
support as the valve does not function for a portion of the
procedure. This further complicates the implantation procedure.
[0011] In view of drawbacks associated with previously known
techniques for endovascularly replacing a heart valve, it would be
desirable to provide methods and apparatus that overcome those
drawbacks.
SUMMARY OF THE INVENTION
[0012] One aspect of the invention provides an apparatus for
endovascularly replacing a patient's heart valve. The apparatus
includes: an expandable anchor supporting a replacement valve, the
anchor and replacement valve being adapted for percutaneous
delivery and deployment to replace the patient's heart valve. The
anchor comprises a braid having grasping elements adapted to grasp
tissue in a vicinity of the patient's heart valve. The grasping
elements preferably are atraumatic.
[0013] Another aspect of the invention provides an apparatus for
endovascularly replacing a patient's heart valve, including: an
expandable anchor supporting a replacement valve, the anchor and
replacement valve being adapted for percutaneous delivery and
deployment to replace the patient's heart valve, the anchor
comprising grasping elements adapted to grasp tissue in a vicinity
of the patient's heart valve. The anchor is self-expanding and has
a delivery configuration, an at-rest configuration and a deployed
configuration, the at-rest configuration having a diameter larger
than a diameter of the delivery configuration and smaller than a
diameter of the deployed configuration. The grasping elements are
positioned substantially parallel with the anchor in the delivery
configuration, at a first angle with the anchor in the at-rest
configuration and at a second angle with the anchor in the deployed
configuration.
[0014] Yet another aspect of the invention provides a method for
endovascularly replacing a patient's heart valve, the method
including: endovascularly delivering an anchor and a replacement
valve supported within the anchor to a vicinity of the heart valve
in a collapsed delivery configuration, the anchor comprising
grasping elements adapted to grasp tissue in a vicinity of the
heart valve; expanding the anchor, thereby rotating the grasping
elements; and grasping the tissue with the rotating grasping
elements.
[0015] In some embodiments, the tissue comprises leaflets of the
patient's heart valve. When the grasping elements grasp the
leaflets, the anchor is substantially distal to the coronary ostia
of the patient. Moreover, once grasped, the grasping elements
prevent the distal movement of the anchor. In some embodiments, the
grasping elements are integral with the anchor or part of the
anchor. In other embodiments, the grasping elements are attached to
the proximal region of the anchor.
[0016] In some embodiments the tissue comprises an annulus of the
patient's heart valve. When the grasping elements grasp the
annulus, the anchor is substantially proximal of the mitral
apparatus. Moreover, once grasped, the grasping elements prevent
the proximal movement of the anchor. In some embodiments, the
grasping elements are integral with the anchor or part of the
anchor. In other embodiments, the grasping elements are attached to
the distal region of the anchor.
[0017] In any of the embodiments described herein, the grasping
elements or the step of grasping the tissue may provide a locating
function for properly placing the apparatus. This locating function
may be accomplished without necessitating a precise placement of
the replacement valve, especially in embodiments that comprise both
proximal and distal grasping elements, e.g., that grasp both the
valve leaflets and the valve annulus. This locating function
advantageously may be accomplished without necessitating tactile
feedback regarding the positioning of the replacement valve.
[0018] Additionally, in any of the embodiments described herein,
the anchor may be adapted for active expansion during deployment.
Active expansion can occur by actuating proximal and/or distal
actuation elements of the anchor. The anchor may be configured for
locking and may include a locking element. The replacement valve is
situated within the anchor and is adapted to permit blood flow and
prevent blood backflow both during and after deployment.
INCORPORATION BY REFERENCE
[0019] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0021] FIGS. 1A and 1B are schematic views of an anchor and valve
apparatus in accordance with the present invention. FIG. 1A
illustrates the apparatus in a collapsed delivery configuration
within a delivery system. FIG. 1B illustrates the apparatus in an
expanded configuration partially deployed from the delivery
system.
[0022] FIG. 2 illustrates an anchor of FIGS. 1 in the collapsed
delivery configuration with locking elements separated.
[0023] FIG. 3 illustrates a braided anchor of the present invention
with closed end turns Tu.
[0024] FIGS. 4A-4O are schematic detail views illustrating
exemplary end turns for a braided anchor.
[0025] FIGS. 5A-5E illustrate additional features for end turns of
a braided anchor.
[0026] FIGS. 6A-6F illustrate deployment of an anchor with leaflet
engagement elements on the deployment system.
[0027] FIG. 7 illustrates a deployed anchor with leaflet engagement
elements on the proximal end of the anchor.
[0028] FIGS. 8A-8C illustrate deployment of an anchor with anchor
registration or leaflet engagement elements and a seal.
[0029] FIGS. 9A-9B illustrate an embodiment of the apparatus with a
seal that does not reach the proximal end of the anchor during both
systole and diastole.
[0030] FIGS. 10A-10B illustrate an embodiment of the apparatus with
a seal that reaches the proximal end of the anchor during both
systole and diastole.
[0031] FIGS. 11A-11D are schematic side views of various braided
anchor configurations.
[0032] FIGS. 12A-12E are schematic side views of a deployment
process for an anchor braid.
[0033] FIGS. 13A-13E are schematic views of different weave
configurations for an anchor braid.
[0034] FIGS. 14A-14C illustrate an embodiment of a replacement
heart valve and anchor in the undeployed and deployed
configurations.
[0035] FIGS. 15A-15D illustrate an embodiment of a replacement
heart valve and anchor having tissue grasping elements that rotate
about the anchor during active expansion of the anchor.
[0036] FIG. 16 is a cross-sectional view illustrating the apparatus
of FIGS. 15 deployed across a patient's native valve.
[0037] FIGS. 17A and 17B illustrate variations of the apparatus of
FIGS. 15 comprising alternative grasping elements deployed across a
patient's native valve.
[0038] FIGS. 18A-18C illustrate additional variations of the
grasping elements.
[0039] FIGS. 19A and 19B illustrate a variation of the grasping
elements that applies an outwardly-directed force, which can
accommodate enlargement in a patient's native valve structures over
time.
[0040] FIGS. 20A-20E illustrate deployment and resheathing of a
replacement valve and anchor having grasping elements via a
delivery system.
[0041] FIG. 21 illustrates a seal for use with grasping elements
coupled to an anchor.
[0042] FIG. 22 illustrates an alternative embodiment of the
grasping elements and seals of FIG. 21.
[0043] FIG. 23 illustrates another alternative embodiment of the
grasping elements and seal of FIG. 21.
[0044] FIG. 24 illustrates the apparatus of FIG. 23 deployed across
a patient's native valve.
[0045] FIG. 25 illustrates alternative grasping elements that are
attached to the anchor.
[0046] FIGS. 26A-26B illustrate a variation of the attached
grasping elements of FIG. 25.
[0047] FIGS. 27A-27B illustrate additional, alternative attached
grasping elements.
DETAILED DESCRIPTION OF THE INVENTION
[0048] The present invention relates to an apparatus and methods
for endovascularly delivering and deploying an aortic prosthesis
within a patient's native heart valve, referred to hereinafter as
"replacing" a patient's heart valve. The delivery system includes a
sheath assembly, a multi-lumen shaft, and a guide wire for placing
the apparatus endovascularly within a patient and a user control
allowing manipulation of the aortic prosthesis. The apparatus
includes an anchor and a replacement valve. The anchor and the
replacement valve are adapted for percutaneous delivery and
deployment within a patient's heart valve.
[0049] In some embodiments, the apparatus includes engagement
elements and/or a seal inverting element situated along a proximal
region of the anchor. The engagement elements are adapted to engage
the native leaflets of the patient's heart, or more preferably the
proximal edge and/or the commissural attachments of the native
leaflets. The engagement elements need not extend all the way into
the pocket or the distal end of the native leaflet. The apparatus
additionally or alternatively may comprise engagement elements
along a distal region of the anchor for engaging an annulus of the
native valve. The engagement elements may be formed integrally with
the anchor or may be attached to the anchor.
[0050] In some embodiments, the proximal and/or distal engagement
elements comprise grasping elements configured to grasp tissue in
the vicinity of the patient's heart valve, e.g. to rotate into the
tissue and secure the apparatus relative to the tissue. The
grasping elements preferably are atraumatic. Preferred embodiments
of the apparatus are depicted in FIGS. 1-27, which are discussed in
more detail below.
[0051] FIGS. 1A and 1B illustrate one embodiment of a delivery
system and the apparatus of the present invention.
[0052] As illustrated by FIG. 1A, apparatus 10 comprising
replacement valve 20 and anchor 30 may be collapsed for delivery
within a delivery system 100. Delivery system 100 includes a
guidewire 102, a nose cone 104, anchor actuation elements 106
(e.g., "fingers") coupled to a multi-lumen shaft 108, an external
sheath 110 having a proximal handle 111, and a control handle 120.
Delivery system 100 further comprises distal region control
elements (not shown) comprised of, or actuated by, control wires
(not shown), which pass through one or more lumens of shaft 108 and
are reversibly coupled to posts 32 of anchor 30 for manipulating a
distal region of apparatus 10. Thus, the distal region control
elements may function as a distal actuation element. The control
wires may comprise, for example, strands of suture, or metal or
polymer wires.
[0053] The delivery system also comprises proximal region control
elements that are comprised of, or actuated by, additional control
wires that pass through one or more lumens of shaft 108 and anchor
actuation elements 106. The wires reversibly couple the anchor
actuation elements to a proximal region of anchor 30. In some
embodiments, the anchor actuation elements and associated wires may
be referred to as proximal actuation elements.
[0054] Control handle 120 is coupled to multi-lumen shaft 108. A
knob 122 disposed in slot 123 is coupled to the distal region
control wires for controlling movement of the distal region of
apparatus 10. Likewise, a knob 124 disposed in slot 125 is coupled
to the proximal region control wires for control of the proximal
region of apparatus 10. Handle 120 may also have a knob 126 for,
e.g., decoupling the proximal and/or distal region control wires
from apparatus 10, or for performing other control functions.
[0055] As illustrated by FIG. 1B, apparatus 10 comprises an anchor
30 and a replacement valve 20. Anchor 30 preferably comprises a
braid. Such braid can have closed ends at either or both of its
ends but preferably at least in its proximal end. Replacement valve
20 is preferably coupled to the anchor at posts 32 attached at a
distal region of the anchor. Thus, posts 32 may function as a valve
support and may be adapted to support the replacement valve within
the anchor. In the embodiment shown, there are three posts,
corresponding to the valve's three commissure attachments. The
posts can be attached to the braid of anchor 30. The posts can be
attached to the braid's distal region, as shown in FIG. 2, central
region, or proximal region. Replacement valve 20 can be composed of
a metal, a synthetic material and/or may be derived from animal
tissue. Replacement valve 20 is preferably configured to be secured
within anchor 30.
[0056] In preferred embodiments, anchor 30 is collapsible and/or
expandable and is formed from material such as Nitinol.TM.,
cobalt-chromium steel or stainless steel wire. More preferably, an
anchor 30 is self-collapsing and/or self-expanding and is made out
of shape memory material, such as Nitinol.TM.. An anchor composed
of shape memory material may self-expand to or toward its "at-rest"
configuration. This "at rest" configuration of an anchor can be,
for example its expanded configuration, its collapsed
configuration, or a partially expanded configuration (between the
collapsed configuration and the expanded configuration). In some
embodiments, an anchor's at-rest configuration is between its
collapsed configuration and its expanded configuration. Depending
on the "at rest" diameter of the anchor and the diameter of the
patient's anatomy at the chosen deployment location, the anchor may
or may not self-expand to come into contact with the diameter of
the patient's anatomy at that location.
[0057] Anchor 30 may be expanded to a fully deployed configuration
from a partial deployed configuration (e.g., self-expanded or
at-rest configuration) by actively expanding, e.g., actively
foreshortening, anchor 30 during endovascular deployment. Active
foreshortening is described in more detail in U.S. patent
application Ser. No. 10/746,280, which is incorporated herein by
reference in its entirety. During active foreshortening, the distal
region of anchor 30 may be pulled proximally via a proximally
directed force applied to posts 32 via a distal deployment system
interface comprised of the distal system control elements. The
distal deployment system interface is adapted to expand radially
during application of a proximally directed force on the distal end
of the anchor when opposed by a distally directed force applied to
the proximal end of the anchor, e.g., by the anchor actuation
elements 106.
[0058] In some embodiments, actuating foreshortening of the
apparatus involves applying a proximally directed force on a
deployment system interface at the distal end of the anchor, while
maintaining the proximal end of the anchor in the same location. In
other embodiments, foreshortening of the apparatus involves
applying a distally directed force on proximal end of the anchor
(e.g., by applying a distally directed force on the anchor
actuation elements).
[0059] Anchor actuation elements 106 (e.g., fingers, tubes, posts,
and control wires connecting to posts) are preferably adapted to
expand radially as the anchor expands radially and to contract
radially as the anchor contracts radially. Furthermore, proximally
or distally directed forces by the anchor actuation elements on one
end of the anchor do not diametrically constrain the opposite end
of the anchor. In addition, when a proximally or distally directed
force is applied on the anchor by the anchor actuation elements, it
is preferably applied without passing any portion of a deployment
system through a center opening of the replacement valve. This
arrangement enables the replacement valve to operate during
deployment and before removal of the deployment system.
[0060] The distal deployment system interface may include control
wires that are controlled, e.g., by control knob 122 of control
handle 120. Similarly, the proximal regions of anchor 30 may be
pushed distally via a proximal deployment system interface at the
proximal end of the anchor. The proximal deployment system
interface is adapted to permit the deployment system to apply a
distally directed force to the proximal end of anchor 30 through,
e.g., anchor actuation elements 106, which are controlled by, e.g.,
control knob 124 of control handle 120. The proximal deployment
system interface may be further adapted to expand radially during
application of a distally directed force on the proximal end of the
anchor. Such active expansion of the anchor optionally may be
assisted via inflation of a balloon catheter (not shown) reversibly
disposed within apparatus 10, as described in U.S. patent
application Ser. No. 10/746,280.
[0061] Once anchor 30 is fully deployed, posts 32 and buckles 34 of
anchor 30 may be used to lock and maintain the anchor in the
deployed configuration. In one embodiment, the control wires
attached to posts 32 are threaded through buckles 34 so that the
proximally directed force exerted on posts 32 by the control wires
during deployment pulls the proximal locking end of posts 32 toward
and through buckles 34. Such lock optionally may be selectively
reversible to allow for repositioning and/or retrieval of apparatus
10 during or post-deployment. Apparatus 10 may be repositioned or
retrieved from the patient until the two-part locking mechanism of
posts 32 and buckles 34 of anchor 30 have been actuated. When the
lock is selectively reversible, the apparatus may be repositioned
and/or retrieved as desired, e.g., even after actuation of the
two-part locking mechanism. Once again, further details of this and
other anchor locking structures may be found in U.S. patent
application Ser. No. 10/746,280. Locking mechanisms used herein may
also include a plurality of levels of locking wherein each level of
locking results in a different amount of expansion of anchor 30.
For example, the proximal end of the post can have multiple
configurations for locking within the buckle wherein each
configuration results in a different amount of anchor expansion.
FIG. 2 illustrates a braided anchor of FIGS. 1 in the collapsed
delivery configuration with locking elements separated.
[0062] FIG. 3 provides a detail view of a front side region of
anchor braid 30 with closed end turns Tu. Anchor braid 30 includes
various cells, some having an end turn Tu. End turns can serve
various functions. For example, end turns can be configured to
reduce the sheathing force, to reduce stress within the braid
during delivery and deployment, to prevent migration during
expansion of the anchor, to positively register the anchor against
the native valve during deployment. In preferred embodiments, an
end turn feature functions to prevent migration and to register the
anchor by engaging the native leaflets and/or the annulus of the
native valve. In preferred embodiments, the proximal region or the
distal region of anchor 30 comprises embodiments (Tu). In some
embodiments, the end turn feature grasps tissue in the vicinity of
the native heart valve, such as the native valve leaflets and/or
the valve annulus, e.g., by rotating into the tissue during
expansion of the anchor.
[0063] FIGS. 4A-4N provide multiple examples of edge cells having
an end turn feature. The end turn features disclosed and others
known in the art may be used as engagement or grasping elements to
engage and/or grasp tissue in the vicinity of a patient's heart
valve, such as the native heart leaflets or the valve annulus, with
the anchor. The engagement or grasping elements may be integral
with the anchor, for example, may be part of a braided anchor.
Alternatively, the engagement or grasping elements may be attached
to the anchor, for example, via interweaving, crimping, welding,
soldering, wire wrapping, or other suitable attachment means. The
end turn features can occur at the proximal, central, or distal
region of the anchor, or a combination thereof.
[0064] For example, FIG. 4A illustrates a detail view of a standard
end turn Tu in an anchor braid resulting in a braid with
substantially uniform cell size and shape.
[0065] FIG. 4B illustrates a turn that has been elongated to
lengthen the distance over which forces concentrated in the turn
may be distributed, resulting in an anchor braid having edge cells
that are longer along the anchor axis than the other cells defined
by the braid. This elongated turn feature may be formed by routing
the wire of braid about outer posts and then heat setting the
wire.
[0066] FIG. 4C illustrates an alternative anchor edge cell
configuration, wherein the tip of the elongated wire turn may be
bent out of a cylindrical shape defined by the braid of anchor
braid 30. This may be achieved, for example, via a combination of
routing of wire W within a fixture and then heat setting. Such a
turn Tu in the anchor edge cells in FIG. 4C may reduce stress in
some configurations without increasing height, and may also provide
a lip for engaging or grasping the patient's native valve leaflets
to facilitate proper positioning of apparatus 10 during
deployment.
[0067] In FIG. 4D, a W-shaped turn feature has been formed at the
wire turn, e.g., by routing the wire of anchor braid 30 about a
central inner post and two flanking outer posts. As with the
elongated braid cells of FIGS. 4B and 4C, the W-shape may better
distribute stress about turn Tu.
[0068] The anchor edge cell configuration in FIG. 4E includes a
loop formed in braid 30 at the turn, which may be formed by looping
wire W around an inner or outer post.
[0069] FIG. 4F provides another alternative anchor edge cell
configuration having a figure-eight shape. Such a shape may be
formed, for example, by wrapping wire W about an inner post and an
aligned outer post in a figure-eight fashion, and then heat setting
the wire in the resultant shape.
[0070] In FIG. 4G, the edge cells of braid 30 include a
heart-shaped configuration, which may be formed by wrapping the
wire about an aligned inner and outer post in the desired
manner.
[0071] In FIG. 4H, the edge cells of braid 30 have an asymmetric
loop at turn Tu. The asymmetric loop will affect twisting of braid
30 during expansion and collapse of the braid, in addition to
affecting stress concentration.
[0072] In FIG. 4I, the anchor edge cells have a double-looped turn
configuration, e.g. via wrapping about two adjacent inner or outer
posts. Additional loops may also be employed.
[0073] The double loop turn feature may be formed with a smooth
transition between the loops, as in FIG. 4I, or may be heat set
with a more discontinuous shape, as in FIG. 4J.
[0074] FIG. 4K illustrates that the edge cells of braid 30 may have
multiple different configurations about the anchor's circumference.
For example, the anchor edge cells shown in FIG. 4K have extended
length cells as in FIG. 4B disposed adjacent to standard size edge
cells, as in FIG. 4A.
[0075] The anchor edge cells of FIG. 4L have an extended turn
configuration having an extended loop.
[0076] The anchor edge cells shown in FIG. 4M have an alternative
extended configuration with a specified heat set profile.
[0077] In FIG. 4N, some or all anchor edge cells are interwoven.
When interwoven, one or more edge cells may be shorter or longer
than an adjacent edge cell. This permits one or more edge cells to
extend into one or more leaflet pocket(s). For example, in FIG. 4N
the middle Tu may be taller than the two adjacent edge cells thus
permitting the edge cell to be situated within a leaflet
pocket.
[0078] In any of the embodiments herein, edge cells may be wrapped
using wire, string, or sutures, at a location where the wire
overlaps after an end turn as is illustrated in FIG. 4O. This
tied-end turn feature prevents cells from interlocking with each
other during deployment.
[0079] The anchor and any of its features may be heat set at
different configurations. For example, the anchor may be heat set
at its "at-rest" configuration such that upon unsheathing it
expands radially. The end turn features/leaflet engagement elements
may be heat set at a different "at-rest" configuration than the
rest of the anchor. In some embodiments, the end turn features are
heat set to "flower" and then "evert" upon unsheathing. In other
embodiments, the end turns are heat set in an everted configuration
and lie parallel/radially concentric with the anchor, e.g., lie
substantially flat against the anchor, in the sheathed delivery
configuration and then to expand outward upon unsheathing. When
used as grasping elements, the end turns may rotate relative to the
anchor during active expansion of the anchor in order to grasp
tissue in the vicinity of the patient's heart valve.
[0080] The end turn features of FIGS. 4 are provided only for the
sake of illustration and should in no way be construed as limiting.
Additional turn features within the scope of the present invention
will apparent to those of skill in the art in view of FIGS. 4.
Furthermore, combinations of any such end turn features may be
provided to achieve the desired characteristics of anchor 30.
[0081] Referring now to FIGS. 5A-E, additional configurations for
reducing stress concentration and/or circumferential stiffness of
an anchor braid and/or engagement/grasping elements are
illustrated. Such configurations can be used independently or in
conjunction with other configurations disclosed herein. Such
configurations are preferably used at the anchor's edges to locally
reduce the cross-sectional area of substantially all cells or of
substantially all cells in the anchor braid's edge (e.g., proximal
and/or distal). As seen in FIGS. 5A and 5B, turns Tu in wire W
typically may have a substantially continuous (e.g., round)
cross-sectional profile. As seen in FIG. 5C, modifying the edge
cell configuration by locally reducing the thickness or
cross-sectional area of wire W at turn(s) Tu will reduce stress
concentration within the wire at the turns and facilitate collapse
and/or expansion of anchor braid 30 from the delivery to the
deployed configurations. Furthermore, it is expected that such
localized reduction in thickness or cross-sectional area will
reduce a risk of kinking, fatigue or other failure at turns Tu.
[0082] In any of the embodiments herein, localized reduction of an
anchor wire may be achieved via a localized etching and/or
electropolishing process. Alternatively or additionally, localized
grinding of the turns may be utilized. Additional processing
techniques will be apparent to those of skill in the art. As seen
in FIGS. 5D-5E, wire W may, for example, comprise an oval or
rectangular cross-sectional profile, respectively, after localized
reduction. The wire alternatively may comprise a round profile of
reduced cross-sectional area (not shown). Additional profiles will
be apparent. Localized reduction can take place at any time (e.g.,
before or after a braid is woven). Preferably, localized reduction
occurs after weaving. However, in some embodiments, a wire of a
given length may be etched or ground at preset segments and
subsequently woven.
[0083] With reference now to FIGS. 6A-F, a method of endovascularly
replacing a patient's diseased aortic valve is provided. The method
involves endovascularly delivering an anchor/valve apparatus and
properly positioning such apparatus via positive registration with
the patient's native valve leaflets. Registration with the native
valve leaflet occurs using at least one leaflet engagement
element.
[0084] In FIG. 6A, modified delivery system 100' delivers apparatus
10 to diseased aortic valve AV within sheath 110. Apparatus 10 is
delivered in a collapsed delivery configuration within lumen 112 of
the sheath.
[0085] As seen in FIGS. 6B and 6C, apparatus 10 is deployed from
lumen 112 of sheath 110, for example, under fluoroscopic guidance.
Sheath 110 includes at its distal end leaflet engagement elements
120. Upon deployment, anchor 30 of apparatus 10 dynamically
self-expands to a partially deployed or at-rest configuration. This
causes the anchor actuation elements, illustratively tubes 60, to
also dynamically expand, as well as membrane filter (or braid) 61A
and leaflet engagement elements 120. As when deployed via delivery
system 100, deployment of apparatus 10 via delivery system 100' is
fully reversible until locks 40 have been actuated.
[0086] Leaflet engagement elements 120 preferably self-expand along
with anchor 30. In preferred embodiments, the distal ends of
leaflet engagement elements 120 expand a greater radial distance
than anchor 30. Moreover, engagement elements 120 may be disposed
between tubes 60 of delivery system 100' and a proximal region of
anchor 30. However, leaflet engagement elements 120 may also be
disposed, e.g., attached or coupled, on the proximal region of the
anchor (as is illustrated in FIG. 7). In FIG. 6, leaflet engagement
elements 120 releasably engage the anchor. As seen in FIG. 6C, the
leaflet engagement elements 120 are initially deployed proximal of
the patient's native valve leaflets L. Apparatus 10 and elements
120 then may be advanced, i.e., dynamically repositioned, until
engagement elements positively register against the leaflets,
thereby ensuring proper positioning of apparatus 10. The leaflet
engagement elements engage with the proximal edges of the native
valve leaflets and/or with the commissural attachments. The leaflet
engagement elements need not extend all the way to the distal edge
of the native leaflets (the leaflet pockets). In preferred
embodiments, a leaflet engagement element length is less than about
20 mm, more preferably less than about 15 mm, or more preferably
less than about 10 mm. Once leaflet engagement elements 120 are
registered against the native valve leaflets and/or commissural
attachments, apparatus 10 deploys substantially distal to the
coronary ostia of the heart.
[0087] In any of the embodiments herein, the delivery system
optionally can include filter structure 61A (e.g., a filter
membrane or braid) as part of the anchor actuation elements, such
as push tubes 60, to act as an embolic protection element. Emboli
can be generated during manipulation and placement of an anchor
from either diseased native leaflet(s) or surrounding aortic
tissue, and can cause blockage. Arrows 61B in FIG. 6E show blood
flow through filter structure 61A where blood is allowed to flow,
but emboli are trapped in the delivery system and removed with it
at the end of the procedure.
[0088] Active expansion, e.g., foreshortening, may be imposed upon
anchor 30 while elements 120 are disposed proximal of the leaflets,
as is illustrated in FIG. 6D. Active foreshortening can be
accomplished by actuating distal anchor actuation elements (e.g.,
wires 50) and/or proximal anchor actuation elements (e.g., tubes
60). Upon positive registration of elements 120 against leaflets L,
elements 120 preclude further distal migration of apparatus 10
during additional foreshortening, thereby reducing a risk of
improperly positioning the apparatus. FIG. 6E details engagement of
elements 120 against the native leaflets.
[0089] As seen in FIG. 6F, once apparatus 10 is fully deployed,
anchor 30 may be locked (reversibly or irreversibly) via lock 40.
Subsequently, structure 61A, leaflet engagement elements 120, wires
50 and/or tubes 60 may be decoupled from the apparatus, and
delivery system 100' may be removed from the patient, thereby
completing the procedure.
[0090] FIG. 7 illustrates an alternative embodiment of the
apparatus of FIGS. 6A-F described above, wherein leaflet engagement
elements 120 are coupled to anchor 30 of apparatus 10' rather than
to delivery system 100. In the embodiment illustrated in FIG. 7,
leaflet engagement elements 120 remain implanted near the patient's
native heart valve after the deployment of apparatus 10' and
removal of delivery system 100. Leaflets L may be sandwiched
between the proximal region of anchor 30 and leaflet engagement
elements 120 in the fully deployed configuration. In this manner,
elements 120 positively register apparatus 10' relative to the
leaflets L and preclude distal migration of the apparatus over
time.
[0091] FIGS. 8A-8C illustrate another embodiment for endovascularly
delivering an apparatus of the present invention. In FIG. 8A, a
catheter 600 is delivered percutaneously in a retrograde fashion to
the aortic valve. The catheter passes through the native aortic
valve before an operator actuates the unsheathing of the
anchor/valve apparatus. As the sheathing catheter is pulled
proximally out of the native valve, anchor 30 and replacement valve
20 become unsheathed Immediately the portion of the unsheathed
anchor 30 dynamically self-expands to its "at-rest" position, and
replacement valve 20 within the anchor regains an uncollapsed
structure, allowing it to begin to function. In preferred
embodiments in its "at-rest" position, anchor 30 presses against
the native leaflets limiting blood from flowing in between the
anchor and leaflet. Also, in preferred embodiments, anchor 30
portions relatively adjacent to the valve are externally covered by
a seal 62, more preferably the entire exterior contour of anchor 30
excluding the leaflet engagement elements is externally covered by
a seal, or more preferably the entire contour of anchor 30
including the external face of the leaflet engagement elements is
externally covered by a seal. A seal can be composed of any
material that prevents or limits the flow of blood through the
anchor. In preferred embodiments, a seal is composed of a thin,
elastic polymer or any other type of fabric. The seal can be
attached to the anchor and, in some embodiments, to the distal end
of the valve, by any means known in the art. In preferred
embodiments, a seal is attached to the anchor by suturing.
[0092] In FIG. 8B, as the catheter is further pulled proximally,
the proximal end of anchor 30 and anchor actuation elements or
fingers 50 are unsheathed. In this embodiment, it is possible to
visualize that the seal covers the entire contour of the anchor
including the external face of the leaflet engagement element(s)
70. As soon as the proximal end of the anchor is exposed, it also
dynamically expands. Furthermore, when fingers 50 become exposed,
replacement valve 20 begins to function, permitting blood to flow
through replacement valve 20, between fingers 50 and around the
catheter 600. This also permits blood to flow into the coronary
ostias. In other embodiments where the seal does not cover the
proximal end of the anchor, the replacement valve can begin to
function as soon as the unsealed portion of the anchor is
unsheathed. This causes the leaflet engagement element(s) 70 to
radially expand to their heat set position and engage with the
native heart leaflets.
[0093] Next, as seen in FIG. 8C, as the apparatus is actively
foreshortened using proximal actuators (e.g., fingers) and/or
distal actuators (e.g., wires 55), the leaflet engagement elements
positively register with the native valve leaflets. Foreshortening
can cause seal 62 to bunch up and create pleats. These pleats can
then fill pockets, thereby improving the paravalvular seal. In
embodiments in which the leaflet engagement elements are covered
with a seal, at least a portion of the seal is also positioned
between the native valve leaflets and the aortic wall. Once the
anchor is fully compressed within the aortic valve, the anchor is
locked, the proximal and distal actuators are disengaged, and the
seal is adapted to further limit blood flow around the replacement
valve. The catheter is subsequently withdrawn, leaving behind valve
20, seal 62 and anchor 70. When fully deployed, the anchor is
substantially distal to the coronary ostia of the patient, such
that it will not interfere with blood flow through the ostia.
[0094] FIGS. 9A-9B illustrate an embodiment wherein only a distal
portion of anchor 30 is covered by seal 62, and wherein anchor 30
is only partially deployed since the blood can escape through the
proximal end of the anchor braid. As anchor 30 in this embodiment
is unsheathed, it presses against the native valve leaflets. At
this point replacement valve 20 is functional even though anchor 30
is not fully deployed, since blood can escape through the proximal
end of the anchor braid. This allows blood to flow through
replacement valve 20 and out of holes in the distal end of anchor
30 during systole (FIG. 9A) while preventing backflow during
diastole (FIG. 9B).
[0095] FIGS. 10A-10B illustrate a similar embodiment wherein seal
62 around anchor 30 surrounds the entire contour of anchor 30. In
this embodiment, valve 20 does not become functional until both
anchor 30 and a portion of fingers 50 are unsheathed. As soon as a
portion of fingers 50 is unsheathed, replacement valve 20 is fully
functional. This allows blood to flow through replacement valve 20
and anchor 30, out of fingers 50, and around catheter 600 into the
aorta and coronary ostias during systole. Similarly, during
diastole, replacement valve 20 closes preventing blood backflow
from entering the chamber.
[0096] In any of the embodiments herein the anchor is preferably a
self-expanding anchor braid. Anchor braids of the present invention
can be made from one or more wires, more preferably 2-20 wires,
more preferably 3-15 wires, or more preferably 4-10 wires.
Moreover, the density of the braid can be modified by various forms
of weave used.
[0097] FIGS. 11A-11D illustrate various anchor braid embodiments
contemplated by the present invention.
[0098] FIG. 11A illustrates two groups of cells or two braids
interwoven in the center. The top group of cells forms a more open
weave than the bottom group of cells, which forms a denser
weave.
[0099] FIG. 11B illustrates another embodiment of an anchor braid
having three groups of cells. The top and bottom (proximal and
distal) edges of the anchor braid have denser cells than the
central portion of the anchor. Also, the edges of the anchor are
woven from a thinner filament than the central portion.
[0100] In another embodiment illustrated by FIG. 11C, all three
sections of an anchor valve are woven by more than one wire. The
wires of each section are made of a different material and/or
thickness. Wires at the sectional boundaries may or may not
interconnect with wires from a different section. Each of the
sections of the braid anchor may be composed of a different number
of wires.
[0101] FIG. 11D illustrates another embodiment of a braided anchor
having three sections. In this embodiment, all sections are
composed of a single wire. The proximal and distal sections/edges
of the braided anchor have the same pitch. The central region of
the braided anchor has a different pitch than the edge
sections.
[0102] FIGS. 12A-12E illustrate side views of braided anchors
having more than one braid pitch. Varying pitch within the anchor
allows localized variations in foreshortening across the anchor, as
greater foreshortening is achieved by higher pitch of the braid.
Moreover, the localized foreshortening features allow for the
design of a braid which incorporates various diameters depending
upon the amount of foreshortening. (The greater the foreshortening,
the greater the diameter increase upon deployment.)
[0103] FIGS. 12A, is a side view representation of the braided
anchor of FIG. 11D. On the left side of the figure, the expanded
anchor is illustrated having a denser weave (shorter pitch) at the
distal and proximal ends; hence the dots are located closer to each
other. The middle section of the anchor is composed of a looser
weave that is generated by a higher pitch braid and is represented
by dots that are farther away from each other. On the right side of
the figure, the braided anchor is foreshortened and the dots are
collapsed closer to each other. In this case, the central portion
of the anchor foreshortened more than the proximal and distal
edges.
[0104] FIG. 12B illustrates a side view of a foreshortened braided
anchor that is created by low pitch at the edges and high pitch in
the middle.
[0105] FIG. 12C illustrates a side view of a foreshortened braided
anchor that is created by high pitch edges and low pitch middle
section.
[0106] FIG. 12D illustrates a side view of a foreshortened braided
anchor that includes a sealing feature or space filling feature at
both ends. This type of anchor can be created by a high pitch braid
at edges, low pitch braid in the middle and heat setting the edges
to curl upon unsheathing. These end features can be useful in
facilitating anchoring by functioning as a locator and/or sealing.
In one embodiment, the curled ends of the anchor in FIG. 12D can be
used as tissue engagement elements.
[0107] FIG. 12E illustrates a side view of a foreshortened braided
anchor that is associated with an everting valve or
locational/engagement/grasping features. In preferred embodiments,
the middle section of the anchor may be composed of thicker wire(s)
than edge section(s). For example, an everting feature at the
proximal end can function as a leaflet engagement element as
disclosed herein.
[0108] FIGS. 13A-13E illustrate an example of the process of
deploying an anchor, such as the one illustrated in FIG. 12B
above.
[0109] FIG. 13A illustrates a braided anchor 30 in its expanded or
elongated configuration. The anchor is composed of three sections.
The distal and proximal sections of the anchor are made of a fine
weave, low pitch braid and the middle section of the anchor is made
of a thicker thread and higher pitch braid. The distal and proximal
section are preferably heat set to roll upon unsheathing, though
some rolling may occur simply from active foreshortening of the
fine weave braid. In preferred embodiments, the filaments of the
fine weave braid are less than 0.01 cm, or more preferably less
than 0.005 cm in thickness. On the other hand, thicker filaments of
the middle section are preferably 0.01 cm or greater in thickness
or more preferably 0.015 cm or greater in thickness. Posts 32 are
coupled to the middle section of the anchor. For deployment, tubes
(or fingers) 106 are coupled to the anchor's middle section.
[0110] FIG. 13B illustrates an anchor during the process of
deployment after the anchor is unsheathed. The anchor is pushed
distally by tubes and pulled proximally by wires and begins
foreshortening. In some embodiments, the distal section rolls up
and can act as a locator, assisting the operator in locating the
aortic valve or engaging the valve annulus, or as a seal preventing
leakage. In some embodiments, the proximal section may roll down
and be used as a leaflet engagement element to prevent distal
migration or as a proximal seal.
[0111] In FIG. 13C, the device may be configured such that the
middle section of the valve may form an hour glass shape or a round
shape. The tubes may subsequently be removed as described
before.
[0112] FIG. 13D is another illustration of the braided anchor in
its elongated configuration.
[0113] FIG. 13E is another illustration of the braided anchor in
its foreshortened configuration.
[0114] FIGS. 14A-14C illustrate the process of forming a pleated
seal around a replacement valve to prevent leakage. FIG. 14A
illustrates a fabric seal 380 prior to deployment and
foreshortening of the anchor/valve apparatus. In FIG. 14A, the
fabric seal 380 extends from the distal end of valve 20 proximally
over anchor 30 during delivery. During deployment, as illustrated
in FIG. 14B, anchor 30 foreshortens, and the fabric seal 380
bunches up to create fabric flaps and pockets that extend into
spaces formed by the native valve leaflets 382. The bunched up
fabric or pleats occur, in particular, when the pockets are filled
with blood in response to backflow blood pressure. The pleating can
create a seal around the replacement valve. FIG. 14C illustrates
anchor 30, surrounded by fabric seal 380 in between native valve
leaflets 382. In preferred embodiments, at least a portion of a
seal is captured between the leaflets and the wall of the heart
when the anchor is fully deployed
[0115] Referring now to FIGS. 15 and 16, a replacement heart valve
and anchor having engagement elements configured to grasp tissue in
the vicinity of a patient's heart valve is described. The grasping
engagement elements are configured to rotate about the anchor
during active expansion of the anchor. Such rotation may be used to
grasp the tissue, e.g., to grasp leaflets of the patient's native
heart valve. The grasping elements preferably grasp tissue
atraumatically.
[0116] Anchor 30 comprises grasping elements 80. The grasping
elements may comprise, for example, heat-set end turns Tu of a
braid from which the anchor is fabricated, a special weave of the
braid, or multiple wires attached to one another by crimping,
welding or other means. The grasping elements may be integral with
anchor 30 or may be attached to the anchor, for example, via
interweaving, crimping, welding, soldering, wire wrapping, or other
suitable attachment means. Grasping elements 80 may have a
different cross-sectional profile than that of the material from
which the body of anchor 30 is fabricated, e.g., from that of the
wires forming the braid of anchor 30. Additionally or
alternatively, the grasping elements may be fabricated of different
materials than those from which the anchor is fabricated and/or
from which other grasping elements are fabricated.
[0117] In FIGS. 15, grasping elements 80 illustratively extend from
a proximal region of the anchor, e.g., for atraumatic grasping of
tissue of the patient's native valve leaflets. Such grasping of the
valve leaflets may facilitate proper positioning of the anchor
distal of the coronary ostia, and also might resist distal movement
of the anchor. Grasping elements may additionally or alternatively
extend from a distal region of the anchor, e.g., for atraumatic
grasping of the annulus of the patient's heart valve. Such grasping
of the annulus may facilitate positioning proximal of the mitral
apparatus, and also might resist proximal movement of the
anchor.
[0118] Anchor 30 comprises a self-expanding anchor having a
delivery configuration, as seen in FIG. 15A; an at-rest
configuration, as seen in FIG. 15B; and a deployed configuration,
as seen in FIG. 15D. The anchor may, for example, self-expand from
the delivery configuration to the at-rest configuration after
deployment from a delivery sheath. The anchor then may be actively
expanded, e.g., foreshortened, to the deployed configuration of
FIG. 15D, in which configuration it may, for example, be locked
using, e.g., one of the lock mechanisms described above. FIG. 15C
illustrates the anchor during active expansion and during
transition from the at-rest configuration to the deployed
configuration. Grasping elements 80 may move radially relative to
one another during expansion of the anchor. For example, in FIGS.
15, the grasping elements move radially apart during self-expansion
of the anchor to the at-rest configuration, then move radially
closer together during active expansion to the deployed
configuration.
[0119] As seen in FIG. 15A, grasping elements 80 are positioned
substantially parallel with anchor 30 in the delivery
configuration, e.g., the grasping elements lie substantially flat
against the anchor during delivery. The grasping elements may be
constrained to lie flat by an exterior constraint, such as the
delivery sheath. As seen in FIG. 15B, grasping elements 80 form a
first angle .alpha. with the anchor in the at-rest configuration.
As seen in FIG. 15C, as the anchor expands to the deployed
configuration, the grasping elements 80 rotate about anchor 30,
such that the angle .alpha. changes. In the fully deployed
configuration of FIG. 15D, the grasping elements form a second
angle .beta. with the anchor. If a lock is provided with the
anchor, locking the anchor in its deployed configuration helps
maintain the anchor's grasp of the tissue.
[0120] The first angle .alpha. illustratively is larger than the
second angle .beta., such that the grasping elements rotate inward
toward the body of anchor 30 during active anchor expansion from
the at-rest configuration to the deployed configuration. The
grasping elements may grasp tissue, such as the patient's valve
leaflets, between the body of the anchor and the grasping elements
during such rotation of the grasping elements. As seen in FIG. 15D,
the second angle 13 may, for example, approximate zero when no
tissue is grasped or captured between the grasping element and the
anchor. In alternative embodiments of grasping elements 80, the
second angle .beta. may be larger than the first angle .alpha.,
such that the grasping elements rotate outward and away from the
body of the anchor for grasping tissue during active anchor
expansion. In still further alternative embodiments, the second
angle .beta. may be substantially equal to the first angle .alpha.,
such that the grasping elements do not rotate, or rotate only
minimally, during active expansion of the anchor.
[0121] FIG. 16 shows anchor 30 and replacement valve 20 deployed
across a patient's native valve. Grasping elements 80 rotate inward
towards the body of anchor 30 during expansion of the anchor,
thereby grasping leaflets L of the patient's aortic valve and
pulling the leaflets toward the anchor, e.g., during diastole. This
grasping of the leaflets secures the apparatus against the native
valve, thereby resisting distal migration of the apparatus and/or
leakage. Furthermore, grasping elements 80 ensure that apparatus 10
is disposed distal of coronary ostia O and extends distal of the
leaflets to valve annulus A.
[0122] With reference now to FIGS. 17, anchor 30 may comprise any
of a variety of grasping elements 80. In FIG. 17A, the anchor
illustratively comprises five separate grasping elements to grasp
the leaflets around the entire circumference of the valve. The
anchor may, for example, comprise 3-6 grasping elements for
grasping the leaflets. Alternatively, the anchor may comprise more
than six grasping elements, as in FIG. 17B. Providing additional
grasping elements may facilitate grasping of the commissures of the
leaflets. Furthermore, providing multiple grasping elements may
distribute forces applied to the tissue amongst the grasping
elements, thereby reducing a risk of misalignment of the anchor
and/or replacement valve. As with the earlier embodiments, this
embodiment may also be provided with a lock mechanism to maintain
expansion of the anchor and grasping of the tissue.
[0123] With reference to FIGS. 18, in addition to altering the
number of grasping elements, the location and/or orientation of the
grasping elements also may be altered. FIGS. 18 show variations of
anchor 30 in the deployed (and possibly locked) configuration. In
FIG. 18A, the anchor comprises two circumferential sets of grasping
elements 80 spaced from one another along the length of the anchor.
In one variation described hereinbelow with respect to FIGS. 19,
the grasping elements of FIG. 18A provide an outwardly-directed
force such that the proximal set of grasping elements may, for
example, grasp wall tissue, while the more distal set may grasp the
interior of the patient's valve leaflets and press the leaflets
against the wall.
[0124] In FIG. 18B, the grasping elements extend from the distal
region of anchor 30, for example, to grasp the annulus of the
patient's valve. In FIG. 18C, the anchor comprises a
circumferential set of grasping elements that extend from the
proximal region of the anchor for grasping the patient's valve
leaflets, as well as a circumferential set of the grasping elements
that extend from the distal region of the anchor for grasping the
patient's valve annulus. The proximal grasping elements are
oriented distally to facilitate grasping of the leaflets, while the
distal grasping elements are oriented proximally to facilitate
grasping of the annulus.
[0125] Referring now to FIGS. 19, a variation of the grasping
elements of FIG. 18A that can accommodate enlargement in a
patient's native valve structures over time is described. In FIGS.
19, grasping elements 80 apply an outwardly-directed force when
anchor 30 is deployed. Anchor 30 may be deployed such that grasping
elements 80 grasp tissue in the vicinity of the patient's heart
valve, for example, such that the proximal grasping elements grasp
wall tissue and the more distal elements grasp the interior of the
valve leaflets and press them against the wall. Over time, the
patient's native valve structures may expand. If the anchor is
locked in the expanded configuration, it may be unable to further
expand with the native structures. As seen in FIG. 19B, since the
grasping elements apply an outwardly-directed force, they rotate
outward relative to the anchor as the native structures expand,
thereby accommodating such expansion and reducing a risk of
migration of the anchor or blood leakage around the anchor.
[0126] FIGS. 20 show deployment and resheathing of apparatus 10
comprising grasping elements 80. As seen in FIG. 20A, apparatus 10
having replacement valve 20 and anchor 30 with grasping elements 80
is positioned in the delivery configuration within sheath 110 of
delivery system 100. Grasping elements 80 are positioned
substantially parallel to, and/or lie flat against, anchor 30.
[0127] In FIG. 20B, as the sheath is retracted relative to
apparatus 10, the anchor and grasping elements begin to dynamically
self-expand. The grasping elements positioned along the proximal
region of the anchor move laterally apart from the grasping
elements positioned along the central region of the anchor as the
anchor self-expands. In FIG. 20C, once the sheath has been fully
retracted, the anchor assumes the at-rest configuration with the
grasping elements 80 forming a first angle .alpha. with the body of
the anchor. It should be understood that each grasping element 80
may form its own, potentially distinct, angle with the anchor.
[0128] Anchor actuation elements 106 then may be used in
conjunction with distal control wires and other elements of
delivery system 100 to actively expand the anchor (and optionally
lock the anchor), as described previously. Grasping elements 80
rotate relative to anchor 30 during active expansion of the anchor
and form a second angle .beta. with the anchor in the fully
deployed configuration of FIG. 20D. As with the first angle
.alpha., each grasping element 80 may form its own, potentially
distinct, second angle .beta. with the anchor. The second angle(s)
.beta. may be larger or smaller than the first angle(s) .alpha.,
i.e., the grasping elements may rotate outward or inward relative
to the anchor. In some embodiments, the second angle(s) .beta. may
be substantially equal to the first angle(s) .alpha., i.e., the
grasping elements may not rotate, or may rotate only minimally,
during active expansion of the anchor. In FIGS. 20, the grasping
elements rotate inward and the proximal grasping elements move
laterally closer to the more distal grasping elements during active
expansion.
[0129] FIG. 20E illustrates that the anchor may be resheathed,
e.g., within sheath 110, after deployment of the anchor. The
grasping elements again lie substantially flat against the anchor
during resheathing. The apparatus may be repositioned or retrieved
via resheathing.
[0130] Referring now to FIG. 21, a seal for use with grasping
elements 80 is described. Seal 90 of FIG. 21 only covers the
grasping elements 80, such that the seal does not interfere with
the primary anchoring function of anchor 30. Seal 90 illustratively
covers all grasping elements 80, but alternatively may cover only a
subset of the grasping elements. Furthermore, the seal may be
utilized regardless of the positioning, orientation or quantity of
the grasping elements. The seal may be captured between leaflets of
the patient's heart valve and a wall of the patient's heart when
the anchor and replacement valve are fully deployed. The seal may
be adapted to reduce or prevent blood flow around the replacement
valve when the anchor and replacement valve are fully deployed.
[0131] FIG. 22 illustrates an alternative embodiment of the
grasping elements and seals of FIG. 21. In FIG. 22, anchor 30
comprises both proximal grasping elements 80 for grasping valve
leaflets and distal grasping elements 80 for grasping the annulus
of the patient's valve. Seal 90 illustratively is positioned only
over the distal grasping elements, such that the seal is captured
against an annulus of the patient's heart valve in the deployed
configuration. The seal forms a distal `skirt` that reduces or
prevents blood flow around the replacement valve when the anchor
and the replacement valve are fully deployed.
[0132] FIG. 23 illustrates another alternative embodiment wherein
seal 90 covers both the proximal and distal grasping elements and
extends between the elements. The seal forms a tubular seal
structure exterior to the body or braid of anchor 30 which can
conform and seal against paravalvular leaks. FIG. 24 illustrates
seal 90 of FIG. 23 deployed across a patient's native valve. The
proximal grasping elements grasp the valve leaflets L and resist
distal migration, while the distal grasping elements grasp the
valve annulus A and resist proximal migration. Tissue grasping with
grasping elements 80 preferably is atraumatic. As seen in FIG. 24,
apparatus 10 is positioned distal of coronary ostia O, and seal 90
prevents or reduces blood flow around the replacement valve
apparatus.
[0133] FIG. 25 is an embodiment of apparatus 10 comprising grasping
elements 80 that are attached to anchor 30, rather than being
formed integrally with the anchor, is described. In FIG. 25,
grasping elements 80 comprise wires 82, as well as wire crimps 84
that attach the wires to the anchor. Each grasping element 80
comprises a wire 82 that optionally may be interwoven with the
braid of anchor 30. Each end of each wire 82 is attached to the
braid of anchor 30 via a crimp 84. The spacing about the
circumference of the anchor between the ends of each wire forms an
atraumatic grasping element 80. A plurality of such grasping
elements are formed about the circumference of the anchor to
facilitate circumferential grasping of tissue.
[0134] In FIG. 25, grasping elements 80 are attached to anchor 30
in a manner such that adjacent grasping elements partially overlap
one another. The degree of overlap may be varied, as desired.
Alternatively, the grasping elements may be attached such that
there is no overlap between adjacent grasping elements.
[0135] Each crimp 84 of FIG. 25 has a first end that crimps to a
wire 82 and a second end that crimps to the braid of anchor 30. In
this configuration, each grasping element requires two unique
crimps 84 for attachment to the braid. With reference to FIG. 26,
an alternative crimp 85 for attaching the grasping elements to the
anchor is described that reduces the total number of crimps
required to attach a given number of grasping elements 80 to anchor
30. Each crimp 85 comprises a central section 86 that crimps onto
the anchor, a first end 87a that crimps onto a first wire 82 and a
second end that crimps onto a second wire 82. Thus, crimps 85 are
shared between adjacent grasping elements 80, thereby reducing the
number of crimps needed to attach the grasping elements. In FIGS.
26, adjacent grasping elements illustratively do not overlap, but
it should be understood that overlapping grasping elements
alternatively may be provided, as in FIG. 25.
[0136] In any of the embodiments of engagement or grasping elements
described herein, the elements may have a different cross-sectional
profile than that of the material from which the body of the anchor
is fabricated, e.g., from that of the wires forming the braid of
anchor 30. Additionally or alternatively, the grasping elements may
be fabricated of different materials than those from which the
anchor is fabricated and/or from which other grasping elements are
fabricated. In FIGS. 26, wires 82 forming grasping elements 80
illustratively have larger cross-sectional diameters than the
cross-sectional diameter of the wire(s) forming the braid of anchor
30. This may, for example, make the wires forming grasping elements
80 stiffer than the wire(s) forming the braid of anchor 30.
[0137] Referring now to FIGS. 27, alternative attached grasping
elements 88 are described. Each grasping element 88 is only
attached to anchor 30 at a single location. Each grasping element
88 comprises a wire 82 that is formed into a loop. The two ends of
the loop are crimped within a first end of a crimp 84. The other
end of the crimp is crimped onto the anchor. By forming each wire
82 into a loop, an atraumatic grasping element 88 is formed for
tissue grasping without necessitating attachment of the grasping
element to the anchor at multiple locations about the circumference
of the anchor.
[0138] Although the grasping elements of FIGS. 25-27 have been
attached to anchor 30 via crimping, it should be understood that
any alternative or additional attachment technique may be utilized.
For example, the grasping elements may additionally or
alternatively be attached via interweaving with the braid and/or
via welding soldering, wire wrapping, or other suitable attachment
means. Additional attachment techniques within the scope of the
present invention will be apparent to those of skill in the
art.
[0139] In any of the embodiments described herein, the engagement
or grasping elements or the step of engaging/grasping the tissue
may provide a locating function for properly placing the apparatus.
This locating function may be accomplished without necessitating a
precise placement of the replacement valve, especially in
embodiments that comprise both proximal and distal grasping
elements, e.g., that grasp both the valve leaflets and the valve
annulus. This locating function advantageously may be accomplished
without necessitating tactile feedback regarding the positioning of
the replacement valve.
[0140] While preferred embodiments of the present invention are
shown and described herein, it will be obvious to those skilled in
the art that such embodiments are provided by way of example only.
Numerous variations, changes, and substitutions will now occur to
those skilled in the art without departing from the invention. It
should be understood that various alternatives to the embodiments
of the invention described herein may be employed in practicing the
invention. It is intended that the following claims define the
scope of the invention and that methods and structures within the
scope of these claims and their equivalents be covered thereby.
* * * * *