U.S. patent application number 10/676729 was filed with the patent office on 2006-03-30 for devices, systems, and methods for retaining a native heart valve leaflet.
This patent application is currently assigned to Ample Medical, Inc.. Invention is credited to Robert T. Chang, Timothy R. Machold, John A. Macoviak, David A. Rahdert, Rick A. Soss.
Application Number | 20060069430 10/676729 |
Document ID | / |
Family ID | 44584934 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060069430 |
Kind Code |
A9 |
Rahdert; David A. ; et
al. |
March 30, 2006 |
Devices, systems, and methods for retaining a native heart valve
leaflet
Abstract
Devices, systems and methods retain a native heart valve leaflet
to prevent retrograde flow. The devices, systems, and methods
employ an implant that, in use, rests adjacent a valve annulus and
includes a retaining structure that is sized and shaped to overlay
at least a portion of one or more native valve leaflets. The
retaining structure retains the leaflet or leaflets it overlays, to
resist leaflet eversion and/or prolapse. In this way, the implant
prevents or reduces regurgitation. The implant does not interfere
significantly with the opening of and blood flow through the
leaflets during periods of antegrade flow.
Inventors: |
Rahdert; David A.; (San
Francisco, CA) ; Macoviak; John A.; (La Jolla,
CA) ; Machold; Timothy R.; (Moss Beach, CA) ;
Chang; Robert T.; (Belmont, CA) ; Soss; Rick A.;
(Burlingame, CA) |
Correspondence
Address: |
RYAN KROMHOLZ & MANION, S.C.
POST OFFICE BOX 26618
MILWAUKEE
WI
53226
US
|
Assignee: |
Ample Medical, Inc.
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20040127981 A1 |
July 1, 2004 |
|
|
Family ID: |
44584934 |
Appl. No.: |
10/676729 |
Filed: |
October 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09666617 |
Sep 20, 2000 |
6893459 |
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10676729 |
Oct 1, 2003 |
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PCT/US02/31376 |
Oct 1, 2002 |
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10676729 |
Oct 1, 2003 |
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60429444 |
Nov 26, 2002 |
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60429709 |
Nov 26, 2002 |
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60429462 |
Nov 26, 2002 |
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60326590 |
Oct 1, 2001 |
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Current U.S.
Class: |
623/2.36 ;
623/2.37 |
Current CPC
Class: |
A61F 2/2454
20130101 |
Class at
Publication: |
623/002.36 ;
623/002.37 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. An implant that retains a native heart valve leaflet to resist
retrograde flow comprising a scaffold sized and configured to rest
adjacent all or a portion of a native heart valve annulus, at least
a portion of the scaffold defining a pseudo-annulus and including a
retaining structure near or within the pseudo-annulus that is sized
and shaped to overlay at least a portion of one or more native
valve leaflets, the scaffold further including spaced-apart struts
sized and configured to contact tissue near or within the heart
valve annulus to brace the retaining structure to resist leaflet
eversion and/or prolapse.
2. An implant according to claim 1 wherein the retaining structure
comprises a wire-form structure.
3. An implant according to claim 1 wherein at least one of the
struts comprises a wire-form structure.
4. An implant according to claim 1 wherein the retaining structure
and the struts each comprises a wire-form structure.
5. An implant according to claim 1 wherein the scaffold is
collapsible for placement within a catheter.
6. An implant according to claim 1 wherein at least one of the
struts carries a structure sized and configured to increase a
surface area of contact with tissue at, above, or below the
annulus.
7. An implant according to claim 1 further including at least one
structure appended to the scaffold and being sized and configured
to contact tissue at, above, or below the heart valve annulus to
stabilize the scaffold.
8. An implant according to claim 1 wherein the scaffold includes a
material and a shape to provide a spring-like bias to enable
compliant contact with tissue near or within the heart valve
annulus.
9. An implant according to claim 1 wherein the struts reshape the
heart valve annulus.
10. An implant according to claim 1 wherein the struts apply
tension to tissue to reshape the heart valve annulus.
11. An implant according to claim 1 wherein the struts displace
tissue to reshape the heart valve annulus.
12. An implant according to claim 1 further including a second
heart valve treatment element appended to the scaffold to affect a
heart valve function.
13. An implant according to claim 12 wherein the second heart valve
treatment element includes means for reshaping the heart valve
annulus for leaflet coaptation.
14. An implant according to claim 12 wherein the second heart valve
treatment element includes means for separating tissue along an
axis of the heart valve annulus for leafleted coaptation.
15. A method for retaining a native heart leaflet to resist
retrograde flow comprising the steps of introducing an implant as
defined in claim 1 into a heart, and resisting leaflet eversion
and/or prolapse by locating the scaffold as defined in claim 1
adjacent all or a portion of a native heart valve annulus to define
a pseudo-annulus with the retaining structure as defined in claim 1
overlaying at least a portion of one or more native valve leaflets
and with the spaced-apart struts as defined in claim 1 contacting
tissue near or within the heart valve annulus to brace the
retaining structure.
16. A method according to claim 15 wherein the introducing step
comprises using an open heart surgical procedure.
17. A method according to claim 15 wherein the introducing step
comprises using a surgical procedure in which the implant is
carried within a catheter.
18. A method according to claim 15 wherein the introducing step
comprises using an intravascular surgical procedure.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of co-pending U.S.
patent application Ser. No. 09/666,617, filed Sep. 20, 2000 and
entitled "Heart Valve Annulus Device and Methods of Using Same,"
which is incorporated herein by reference. This application also
claims the benefit of Patent Cooperation Treaty Application Serial
No. PCT/US 02/31376, filed Oct. 1, 2002 and entitled "Systems and
Devices for Heart Valve Treatments," which claimed the benefit of
U.S. Provisional Patent Application Serial No. 60/326,590, filed
Oct. 1, 2001, which are incorporated herein by reference. This
application also claims the benefit of U.S. Provisional Application
Serial No. 60/429,444, filed Nov. 26, 2002, and entitled "Heart
Valve Remodeling Devices;" U.S. Provisional Patent Application
Serial No. 60/429,709, filed Nov. 26, 2002, and entitled
"Neo-Leaflet Medical Devices;" and U.S. Provisional Patent
Application Serial No. 60/429,462, filed Nov. 26, 2002, and
entitled "Heart Valve Leaflet Retaining Devices," which are each
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention is directed to devices, systems, and methods
for improving the function of a heart valve, e.g., in the treatment
of mitral valve regurgitation.
BACKGROUND OF THE INVENTION
[0003] I. The Anatomy of a Healthy Heart
[0004] The heart (see FIG. 1B) is slightly larger than a clenched
fist. It is a double (left and right side), self-adjusting muscular
pump, the parts of which work in unison to propel blood to all
parts of the body. The right side of the heart receives poorly
oxygenated ("venous") blood from the body from the superior vena
cava and inferior vena cava and pumps it through the pulmonary
artery to the lungs for oxygenation. The left side receives
well-oxygenation ("arterial") blood from the lungs through the
pulmonary veins and pumps it into the aorta for distribution to the
body.
[0005] The heart has four chambers, two on each side--the right and
left atria, and the right and left ventricles. The atria are the
blood-receiving chambers, which pump blood into the ventricles. A
wall composed of membranous and muscular parts, called the
interatrial septum, separates the right and left atria. The
ventricles are the blood-discharging chambers. A wall composed of
membranous and muscular parts, called the interventricular septum,
separates the right and left ventricles.
[0006] The synchronous pumping actions of the left and right sides
of the heart constitute the cardiac cycle. The cycle begins with a
period of ventricular relaxation, called ventricular diastole. The
cycle ends with a period of ventricular contraction, called
ventricular systole.
[0007] The heart has four valves (see FIGS. 1B and 1C) that ensure
that blood does not flow in the wrong direction during the cardiac
cycle; that is, to ensure that the blood does not back flow from
the ventricles into the corresponding atria, or back flow from the
arteries into the corresponding ventricles. The valve between the
left atrium and the left ventricle is the mitral valve. The valve
between the right atrium and the right ventricle is the tricuspid
valve. The pulmonary valve is at the opening of the pulmonary
artery. The aortic valve is at the opening of the aorta.
[0008] At the beginning of ventricular diastole (i.e., ventricular
filling)(see FIG. 1B), the aortic and pulmonary valves are closed
to prevent back flow from the arteries into the ventricles. Shortly
thereafter, the tricuspid and mitral valves open (as FIG. 1B
shows), to allow flow from the atria into the corresponding
ventricles. Shortly after ventricular systole (i.e., ventricular
emptying) begins, the tricuspid and mitral valves close (see FIG.
1C)--to prevent back flow from the ventricles into the
corresponding atria--and the aortic and pulmonary valves open--to
permit discharge of blood into the arteries from the corresponding
ventricles.
[0009] The opening and closing of heart valves occur primarily as a
result of pressure differences. For example, the opening and
closing of the mitral valve occurs as a result of the pressure
differences between the left atrium and the left ventricle. During
ventricular diastole, when ventricles are relaxed, the venous
return of blood from the pulmonary veins into the left atrium
causes the pressure in the atrium to exceed that in the ventricle.
As a result, the mitral valve opens, allowing blood to enter the
ventricle. As the ventricle contracts during ventricular systole,
the intraventricular pressure rises above the pressure in the
atrium and pushes the mitral valve shut.
[0010] FIG. 1D shows a posterior oblique cutaway view of a healthy
human heart 100. Two of the four heart chambers are shown, the left
atrium 170, and the left ventricle 140 (not shown are the right
atrium and right ventricle). The left atrium 170 fills with blood
from the pulmonary veins. The blood then passes through the mitral
valve (also known as the bicuspid valve, and more generally known
as an atrioventricular valve) during ventricular diastole and into
the left ventricle 140. During ventricular systole, the blood is
then ejected out of the left ventricle 140 through the aortic valve
150 and into the aorta 160. At this time, the mitral valve should
be shut so that blood is not regurgitated back into the left
atrium.
[0011] The mitral valve consists of two leaflets, an anterior
leaflet 110, and a posterior leaflet 115, attached to chordae
tendineae 120 (or chords), which in turn are connected to papillary
muscles 130 within the left atrium 140. Typically, the mitral valve
has a D-shaped anterior leaflet 110 oriented toward the aortic
valve, with a crescent shaped posterior leaflet 115. The leaflets
intersect with the atrium 170 at the mitral annulus 190.
[0012] In a healthy heart, these muscles and their chords support
the mitral and tricuspid valves, allowing the leaflets to resist
the high pressure developed during contractions (pumping) of the
left and right ventricles. In a healthy heart, the chords become
taut, preventing the leaflets from being forced into the left or
right atria and everted. Prolapse is a term used to describe the
condition wherein the coaptation edges of each leaflet initially
may coapt and close, but then the leaflets rise higher and the
edges separate and the valve leaks. This is normally prevented by
contraction of the papillary muscles and the normal length of the
chords. Contraction of the papillary muscles is simultaneous with
the contraction of the ventricle and serves to keep healthy valve
leaflets tightly shut at peak contraction pressures exerted by the
ventricle.
[0013] II. Characteristics and Causes of Mitral Valve
Dysfunction
[0014] Valve malfunction can result from the chords becoming
stretched, and in some cases tearing. When a chord tears, the
result is a flailed leaflet. Also, a normally structured valve may
not function properly because of an enlargement of the valve
annulus pulling the leaflets apart. This condition is referred to
as a dilation of the annulus and generally results from heart
muscle failure. In addition, the valve may be defective at birth or
because of an acquired disease, usually infectious or
inflammatory.
[0015] FIG. 2 shows a cutaway view of a human heart 200 with a
prolapsed mitral valve. The prolapsed valve does not form a tight
seal during ventricular systole, and thus allows blood to be
regurgitated back into the left atrium during ventricular
contraction. The anterior 220 and posterior 225 leaflets are shown
rising higher than normal (i.e., prolapsing) into the left atrium.
The arrows indicate the direction of regurgitant flow. Among other
causes, regurgitation can result from redundant valve leaflet
tissue or from stretched chords 210 that are too long to prevent
the leaflets from being blown into the atrium. As a result, the
leaflets do not form a tight seal, and blood is regurgitated into
the atrium.
[0016] FIG. 3 shows a cutaway view of a human heart 300 with a
flailing mitral valve 320. The flailing valve also does not form a
tight seal during ventricular systole. Blood thus regurgitates back
into the left atrium during ventricular contraction, as indicated
by the arrows. Among other causes, regurgitation can also result
from torn chords 310.
[0017] As a result of regurgitation, "extra" blood back flows into
the left atrium. During subsequent ventricular diastole (when the
heart relaxes), this "extra" blood returns to the left ventricle,
creating a volume overload, i.e., too much blood in the left
ventricle. During subsequent ventricular systole (when the heart
contracts), there is more blood in the ventricle than expected.
This means that: (1) the heart must pump harder to move the extra
blood; (2) too little blood may move from the heart to the rest of
the body; and (3) over time, the left ventricle may begin to
stretch and enlarge to accommodate the larger volume of blood, and
the left ventricle may become weaker.
[0018] Although mild cases of mitral valve regurgitation result in
few problems, more severe and chronic cases eventually weaken the
heart and can result in heart failure. Mitral valve regurgitation
can be an acute or chronic condition. It is sometimes called mitral
insufficiency.
[0019] III. Prior Treatment Modalities
[0020] In the treatment of mitral valve regurgitation, diuretics
and/or vasodilators can be used to help reduce the amount of blood
flowing back into the left atrium. An intra-aortic balloon
counterpulsation device is used if the condition is not stabilized
with medications. For chronic or acute mitral valve regurgitation,
surgery to repair or replace the mitral valve is often
necessary.
[0021] To date, invasive, open heart surgical approaches have been
used to repair or replace the mitral valve with either a mechanical
valve or biological tissue (bioprosthetic) taken from pigs, cows or
horses.
[0022] The need remains for simple, cost-effective, and less
invasive devices, systems, and methods for treating dysfunction of
a heart valve, e.g., in the treatment of mitral valve
regurgitation.
SUMMARY OF THE INVENTION
[0023] The invention provides devices, systems and methods that
retain a native heart valve leaflet. The devices, systems, and
methods include an implant that, in use, rests adjacent all or a
portion of a valve annulus. The implant includes a retaining
structure that is shaped to overlay at least a portion of one or
more native valve leaflets. The implant further includes
spaced-apart struts sized and configured to contact tissue near or
within the heart valve annulus. The struts brace the retaining
structure to resist leaflet eversion and/or prolapse. In this way,
the implant prevents or reduces retrograde flow and regurgitation.
The implant does not interfere with the opening of and blood flow
through the leaflets during antegrade flow.
[0024] Other features and advantages of the invention shall be
apparent based upon the accompanying description, drawings, and
claims.
DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1A is a perspective, anterior anatomic view of the
interior of a healthy heart.
[0026] FIG. 1B is a superior anatomic view of the interior of a
healthy heart, with the atria removed, showing the condition of the
heart valves during ventricular diastole.
[0027] FIG. 1C is a superior anatomic view of the interior of a
healthy heart, with the atria removed, showing the condition of the
heart valves during ventricular systole.
[0028] FIG. 1D is a posterior oblique cutaway view of a portion of
a human heart, showing a healthy mitral valve during ventricular
systole, with the leaflets properly coapting.
[0029] FIG. 2 is a posterior oblique cutaway view of a portion of a
human heart, showing a dysfunctional mitral valve during
ventricular systole, with the leaflets not properly coapting,
causing regurgitation.
[0030] FIG. 3 is a posterior oblique cutaway view of a portion of a
human heart, showing a dysfunctional mitral valve during
ventricular systole, with the leaflets flailing, causing
regurgitation.
[0031] FIG. 4 is a perspective, anatomic view of a wire form
implant that includes a retaining element to resist eversion and/or
prolapse of a native valve leaflet, the implant being shown
installed on a mitral valve annulus.
[0032] FIG. 5 is a side elevation view of the implant shown in FIG.
4, shown outside of the body.
[0033] FIG. 6 is a top view of the implant shown in FIG. 4, shown
outside the body.
[0034] FIG. 7 is a top view of another illustrative wire form
implant of the type shown in FIG. 6.
[0035] FIGS. 8 and 9 are top views of illustrative wire form
implants of the type shown in FIGS. 4 and 5, which include
retaining elements to resist eversion and/or prolapse of a native
valve leaflet, and which also include both infra-annular struts and
tabs and supra-annular pads to fix the position of the implants in
a valve annulus.
[0036] FIG. 10 is a perspective view of the implant shown in FIG.
9.
[0037] FIG. 11 is a perspective, anatomic view of the wire form
implant shown in FIG. 10, the implant being shown installed on a
mitral valve annulus.
[0038] FIGS. 12 to 14 are perspective, anatomic views showing the
intravascular introduction and deployment of the implant shown in
FIG. 11 on a mitral valve annulus.
[0039] FIG. 15 is a perspective view of an illustrative wire form
implant of the type shown in FIGS. 4 and 5, which include retaining
elements to resist eversion and/or prolapse of a native valve
leaflet, and which also include frameworks to orient and stabilize
the position of the implants in a valve annulus.
[0040] FIG. 16 is a top view of wire-form mesh implant that resists
eversion and/or prolapse of a native valve leaflet.
[0041] FIG. 17 is a perspective, anatomic view of the wire-form
mesh implant shown in FIG. 16 installed on a mitral valve
annulus.
[0042] FIGS. 18 and 19 are top views of illustrative embodiments of
implants of the types shown in FIGS. 5 and 6, showing implants that
are narrow and do not peripherally rest on the entire valve
annulus.
[0043] FIG. 20 is a top view of an illustrative embodiment of a
wire-form mesh implant of the type shown in FIGS. 16 and 17, being
shown in a flattened condition for intravascular deployment, which,
upon deployment, resists eversion and/or prolapse of a native valve
leaflet, and which also include an auxiliary structure to orient
and stabilize the position of the implants in a valve annulus, the
implant in FIG. 20 also including infra-annular struts and tabs to
fix the position of the implant in the valve annulus.
[0044] FIG. 21 is a perspective, anatomic view of the wire-form
mesh implant shown in FIG. 20, installed on a mitral valve
annulus.
[0045] FIGS. 22, 23, and 24 are top views of illustrative
embodiments of wire-form mesh implants of the type shown in FIG.
20, which resist eversion and/or prolapse of a native valve
leaflet, and which also include a combination of auxiliary
structures and infra-annular struts and tabs to fix, orient, and
stabilize the position of the implants in a valve annulus, the
implants being shown in a flattened condition for intravascular
deployment.
[0046] FIG. 25 is a perspective view of illustrative embodiments of
wire-form mesh implants of the type shown in FIG. 20, which resist
eversion and/or prolapse of a native valve leaflet, and which also
include a combination of auxiliary structures and infra-annular
struts and tabs to fix, orient, and stabilize the position of the
implants in a valve annulus, the implants being shown in an
expanded condition after intravascular deployment.
DETAILED DESCRIPTION
[0047] Although the disclosure hereof is detailed and exact to
enable those skilled in the art to practice the invention, the
physical embodiments herein disclosed merely exemplify the
invention, which may be embodied in other specific structure. While
the preferred embodiment has been described, the details may be
changed without departing from the invention, which is defined by
the claims.
[0048] I. Implants for Retaining a Native Heart Valve Implant
[0049] A. Planar Wire-Form Implants
[0050] 1. Overview
[0051] FIGS. 4, 5, and 6 show an implant 400 sized and configured
to retain at least one dysfunctional native heart valve leaflet. In
use (see, in particular, FIG. 4), the implant 400 rests adjacent
all or a portion of the native heart valve annulus, which, in FIG.
4, is in the atrium. The implant 400 includes a scaffold 410, at
least a portion of which defines a pseudo-annulus. The scaffold 410
includes a retaining element 420 at or near the pseudo-annulus. The
retaining element 420 is sized and shaped to overlay at least a
portion of the superior surface at least one native valve leaflet.
The implant 400 allows the native leaflets to coexist with the
implant 400.
[0052] In its most basic form, the components of the implant 400
are made--e.g., by bending, shaping, joining, machining, molding,
or extrusion--from a biocompatible metallic or polymer material, or
a metallic or polymer material that is suitably coated,
impregnated, or otherwise treated with a material or combination of
materials to impart biocompatibility. The material is also
desirably radio-opaque to facilitate fluoroscopic visualization.
The implant material may be rigid, semi-rigid, or flexible.
[0053] In the embodiment shown in FIG. 4, the scaffold 410 is sized
and configured to rest adjacent all or a portion of the mitral
annulus in the atrium. In the illustrated embodiment (FIG. 4), the
scaffold 410 forms an annular body that, at least in part,
approximates the shape of the native annulus. For this reason, at
least a portion of the scaffold 410 is said to define a
pseudo-annulus. The scaffold 410 includes the retaining element
420, which extends from the periphery of the scaffold 410 radially
into the pseudo-annulus.
[0054] The retaining element 420 is sized and configured (see FIG.
4) to overlay the superior surface of at least one native valve
leaflet. In the illustrated embodiment, the retaining element 420
overlays regions of both leaflets. However, the retaining element
420 could be sized, configured, and oriented to overlay all or a
portion of one leaflet or both leaflets. The size, configuration,
and orientation of the retaining element 420 can vary, depending on
patient needs, as will be described in greater detail later.
[0055] When installed adjacent a mitral valve annulus, during
ventricular systole the retaining element 420 exerts a restraining
force on the superior surface of the leaflet or leaflets it
overlays, resisting deflection of the leaflet or leaflets into the
atrium and preventing leaflet eversion and/or prolapse as well as
retrograde flow of blood through the valve during ventricular
systole from the ventricle into the atrium. The restraining force
also serves to keep valve leaflets tightly shut during peak
ventricular systolic pressures. The retaining element 420 thus
serves as a "backstop" for the leaflet or leaflets it overlays.
During ventricular diastole this restraining force goes to zero and
the retaining element 420 does not prevent opening of the native
valve leaflet or leaflets during antegrade flow. During ventricular
diastole, the native valve leaflet or leaflets open normally so
that blood flow occurs from the atrium into the ventricle. The
implant 400 thereby restores normal one-way function to the
valve.
[0056] As shown in FIGS. 5 and 6, in the illustrated embodiment,
the scaffold 410 and the retaining element 420 are shaped from a
continuous length of wire-formed material. The shape and materials
of the scaffold 410 and retaining element 420 provide the implant
400 with spring-like characteristics. The retaining element 420 is
shaped so that, during ventricular systole, it elastically resists
eversion and/or prolapse of the leaflet or leaflets.
[0057] 2. Fixation of Implants
[0058] The spring-like bias of the implant 400 facilitates
compliant fixation of the outer periphery of the implant 400 to or
near the annulus. The scaffold 410 of the implant 400 dynamically
conforms to the shape of the anatomy.
[0059] As FIGS. 5 and 6 show, the scaffold 410 can also include
supra-annular contact structures 440. The structures 440 are
appended to the scaffold 410 to provide multiple contact regions
between the implant 400 and the atrial wall, above the valve
annulus. The multiple regions of contact that the structures 440
provide uniformly distributes the resting forces of the implant,
and help to prevent erosion of the atrial walls and migration of
the implant.
[0060] Alternatively or in combination with the supra-annular
structures 440, the implant 400 can include infra-annular contact
struts 430. The struts 430 are appended to the scaffold 410,
extending below the plane of the annulus into the ventricular
chamber. The struts 430 are preferably configured to extend through
the valve orifice on narrow connecting members, so that they will
not interfere with the opening and closing of the valve. The struts
430 fix and stabilize the implant within the annulus.
[0061] In this arrangement, the struts 430 are desirably sized and
configured to contact tissue near or within the mitral valve
annulus to brace the retaining structure 420 to resist leaflet
eversion and/or prolapse during ventricular systole. In this
arrangement, it is also desirable that the scaffold 410 be
"elastic," i.e., the material of the scaffold 410 is selected to
possess a desired spring constant. This means that the scaffold 410
is sized and configured to possess a normal, unloaded, shape or
condition, in which the scaffold 410 is not in net compression, and
the struts 450 are spaced apart farther than the longest
cross-annulus distance between the tissue that the struts 430 are
intended to contact. In the illustrated embodiment (FIG. 4), the
scaffold 410 shown resting along the major (i.e., longest) axis of
the mitral valve annulus, with the struts 430 contact tissue at or
near the leaflet commissures. However, other orientations are
possible. The struts 430 need not rest at or near the leaflet
commissures, but may be significantly removed from the commissures,
so as to gain padding from the leaflets. The spring constant
imparts to the scaffold 410 the ability to be elastically
compressed out of its normal, unloaded condition, in response to
external compression forces applied at the struts 430. The scaffold
410 is sized and configured to assume an elastically loaded, in net
compression condition, during which the struts 430 are spaced apart
a sufficiently shorter distance to rest in engagement with tissue
at or near the leaflet commissures (or wherever tissue contact with
the struts 430 is intended to occur) (see FIG. 9A or 9B). When in
its elastically loaded, net compressed condition (see FIGS. 9A and
9B), the scaffold 410 can exert forces to the tissues through the
struts 430. These forces hold the scaffold 410 (and thus the
retaining element 420 itself) against migration within the annulus.
Furthermore, when the struts 430 are positioned at or near the
commissures, they tend to outwardly displace tissue and separate
tissue along the major axis of the annulus, which also typically
stretches the leaflet commissures, shortens the minor axis, and/or
reshapes surrounding anatomic structures. The scaffold 410 can also
thereby reshape the valve annulus toward a shape more conducive to
leaflet coaptation. It should be appreciated that, in order to be
therapeutic, the implant 400 may only need to reshape the annulus
during a portion of the heart cycle, such as during ventricular
systolic contraction. For example, the implant may be sized to
produce small or negligible outward displacement of tissue during
ventricular diastole when the tissue is relaxed, but restrict the
inward movement of tissue during ventricular systolic
contraction.
[0062] As just described, different forms of heart valve treatment
can be provided using a single implant 400.
[0063] Implants having one or more of the technical features just
described, to thereby function in situ as a backstop or retainer
for native leaflets, may be sized and configured in various ways.
Various illustrative embodiments will now be described.
[0064] FIG. 7 shows another illustrative embodiment of an implant
400 including a scaffold 410 that defines a pseudo-annulus and a
retaining element 420 that functions as a leaflet retainer 420. In
FIG. 7, the implant 400 is shown in a flattened condition. The
implant 400 includes infra-annular struts 430. Upon deployment, the
struts 430 contact tissue near or within the heart valve annulus,
and, in particular, between or nearly between the commissures of
the leaflets, and extend into the ventricular side of the valve. As
before described, the struts 430 function to brace and secure the
implant in situ.
[0065] FIG. 8 shows yet another illustrative embodiment of an
implant 400 including a scaffold 410 that defines a pseudo-annulus
and a retaining element 420 that functions as a leaflet retainer.
The implant 400 also includes infra-annular struts 430. In
addition, the implant 400 includes supra-annular contact structures
440, used to disperse the loads experienced by the implant
throughout the atrium.
[0066] FIG. 9 shows other illustrative embodiment of an implant 400
including a scaffold 410 that defines a pseudo-annulus and a
retaining element 420 that functions as a leaflet retainer. In
FIGS. 8 and 9, the retaining element 420 extends across the
interior of the implant in a figure eight pattern and has two
support struts 430. Like the implant shown in FIG. 8, the implant
400 in FIG. 9 includes a plurality of infra-annular struts 430 and
a plurality of supra-annular contact structures 440 that brace,
fix, and stabilize the implants in situ.
[0067] As can be seen in the perspective view in FIG. 10, one or
more of the struts 430 can include a superior component that rests
on the atrial side of the valve, and an inferior component that
rests on the ventricular side of the valve (see FIG. 11). In this
arrangement, the struts 430 place the implant near or within a
heart valve annulus, e.g., between the commissures of the leaflets.
As before described, the shape and tension of the scaffold 410 can
apply a force through the struts 430 that outwardly displaces
tissue and stretches the annulus. The displacement of the tissue
can remodel the annulus and promote normal valve function, free of
eversion and/or prolapse, through a different mechanism than the
retaining elements 420.
[0068] Any number of supra-annular contact structures 440 can also
be used, to disperse the loads experienced by the implant
throughout the atrium.
[0069] As FIG. 15 shows, a given implant 400 can include one or
more auxiliary structures 450 to orient and stabilize the implant
400 within the left atrium. In FIG. 15, the implant 400 includes,
in addition to the scaffold 410 and the retaining element 420, an
orientation and stabilization framework 450. The framework 450
rises from the scaffold 410 above the retaining element 420, e.g.,
with two substantially parallel arched wires, which connect to form
a semicircular hoop above the restraining element 420. The
framework 450 helps to accurately position the implant 400 within
the atrium, and also helps to secure the implant 400 within the
atrium.
[0070] Preferably the framework 450 does not interfere with atrial
function, but instead is compliant enough to contract with the
atrium. As such, the implant 400 may have nonuniform flexibility to
improve its function within the heart.
[0071] Additionally, the implant 400 of FIG. 15 has infra-annular
struts 430 that contact tissue near or within the heart valve
annulus to brace the implant 400 and assist in positioning and
anchoring of the implant.
[0072] The implant 400 may be additionally fixed to the annulus in
various auxiliary ways. For example, the implant 400 may be secured
to the annulus with sutures or other attachment means (i.e. barbs,
hooks, staples, etc.). Still, the position and orientation of the
implant is desirably braced or fixed by structures appended to or
carried by the implant itself, obviating reliance upon such
auxiliary fixation measures.
[0073] In FIG. 15, the retaining element 420 is sized and
configured to cover the superior surface of a single leaflet.
[0074] FIGS. 18 and 19 show other illustrative embodiments of
implants 400 sized and configured to function as leaflet retainers.
In these embodiment, each implant 400 includes a narrow leaflet
retaining element 420. The narrow leaflet retaining elements 420
span the annulus, but the associated scaffold 410 need not
peripherally follow the entire annulus.
[0075] 3. Deployment of Wire Form Implants
[0076] The implant 400 may be delivered percutaneously,
thoracoscopically through the chest, or using open heart surgical
techniques. If delivered percutaneously, the implant 400 may be
made from a superelastic material (for example superelastic Nitinol
alloy) enabling it to be folded and collapsed such that it can be
delivered in a catheter, and will subsequently self-expand into the
desired shape and tension when released from the catheter. The
deployment of an implant in this fashion will now be described.
[0077] FIGS. 12 to 14 show a sequence of steps for a
catheter-based, percutaneous deployment of an implant 400 having
the technical features described. Percutaneous vascular access is
achieved by conventional methods into the femoral or jugular vein.
Under image guidance (e.g., fluoroscopic, ultrasonic, magnetic
resonance, computed tomography, or combinations thereof), a first
catheter (not shown) is steered through the vasculature into the
right atrium. A needle cannula carried on the distal end of the
first catheter is deployed to pierce the septum between the right
and left atrium. A guide wire 1710 is advanced trans-septally
through the needle catheter into the left atrium. The first
catheter is withdrawn, leaving the guide wire 1710 behind. FIG. 12
shows the guide wire 1710 introduced through the vena cava 1730 and
into the right atrium, and then through the septum 1720 between the
right and left atriums, into the left atrium.
[0078] As FIG. 13 shows, under image guidance, an implant delivery
catheter 1820 is advanced over the guide wire 1710 into the left
atrium into proximity with the mitral valve. Alternatively, the
implant delivery catheter 58 can be deployed trans-septally by
means of surgical access through the right atrium.
[0079] The implant delivery catheter 1820 carries within it a
wire-form implant 400 of a type shown in FIGS. 10 and 11,
previously described. The implant 10 is constrained within the
catheter 1820 in a collapsed, straightened condition. A push rod
within the catheter 1820 expels the implant (see FIG. 13). Free of
the catheter 1820, the implant 400 will expand, as FIG. 14 shows.
Progressively freed from the catheter 1820, the implant 400 shapes
and seats about the annulus, as the struts 430 seat within the
commissures and the retaining elements 420 extend over the
leaflets. The implant can also be positioned or repositioned under
image guidance within the left atrium using a catheter-deployed
grasping instrument.
[0080] B. Wire-Form Mesh Implants
[0081] FIGS. 16 and 17 show another embodiment of an implant 400
including a scaffold 410 that defines a pseudo-annulus and a
retaining element 420 that functions as a leaflet retainer. In this
embodiment, the retaining element 420 includes wire-form mesh that
has been shaped to fit the heart anatomy (see FIG. 16). The
wire-form mesh can be secured within the atrium with sutures or
other attachment means (i.e. barbs, hooks, staples, etc.).
Alternatively, the body of the wire-form mesh can be secured by
spring action between the body of the implant and the walls of the
heart.
[0082] In FIG. 20, another illustrative embodiment of an implant
400 including a scaffold 410 that defines a pseudo-annulus and a
retaining element 420. The implant 400 is shown in a flattened out
condition. FIG. 21 shows the implant 400 shown in FIG. 20 after
deployment in a left atrium. The implant 400 includes a leaflet
retaining element 420, upwardly extending stabilization arch
structures 440, as well as infra-annular struts 430, shaped and
configured as previously described. The arch structures 440 and
struts 430 cooperate to orient and stabilize the implant in the
desired position for retaining the valve leaflets.
[0083] FIGS. 22, 23, and 24 show illustrative embodiments of other
implants 400 of the type shown in FIGS. 20 and 21 in flattened out
conditions. Each of these implants 400 include a scaffold 410 that
defines a pseudo-annulus and a retaining element 420. In these
embodiments, the implants 400 include, in addition to a leaflet
retaining element 420, a plurality of arch structures 440 that,
when deployed, contact the interior of the atrium to support and
align the implant 400, as well as infra-annular struts 430 that
contact tissue near or within the heart valve annulus to brace the
retaining structure 420 to resist leaflet eversion and/or prolapse
during ventricular systole. FIG. 25 shows various illustrative
embodiments of an implant 400 in a deployed conditioned.
[0084] While the new devices and methods have been more
specifically described in the context of the treatment of a mitral
heart valve, it should be understood that other heart valve types
can be treated in the same or equivalent fashion. By way of
example, and not by limitation, the present systems and methods
could be used to resist or prevent retrograde flow in any heart
valve annulus, including the tricuspid valve, the pulmonary valve,
or the aortic valve. In addition, other embodiments and uses of the
invention will be apparent to those skilled in the art from
consideration of the specification and practice of the invention
disclosed herein. The specification and examples should be
considered exemplary and merely descriptive of key technical
features and principles, and are not meant to be limiting. The true
scope and spirit of the invention are defined by the following
claims. As will be easily understood by those of ordinary skill in
the art, variations and modifications of each of the disclosed
embodiments can be easily made within the scope of this invention
as defined by the following claims.
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