U.S. patent application number 10/676815 was filed with the patent office on 2005-12-01 for devices, systems, and methods for supplementing, repairing, or replacing a native heart valve leaflet.
This patent application is currently assigned to Ample Medical, Inc.. Invention is credited to Chang, Robert T., Machold, Timothy R., Macoviak, John A., Rahdert, David A., Soss, Rick A..
Application Number | 20050267573 10/676815 |
Document ID | / |
Family ID | 45353279 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050267573 |
Kind Code |
A9 |
Macoviak, John A. ; et
al. |
December 1, 2005 |
Devices, systems, and methods for supplementing, repairing, or
replacing a native heart valve leaflet
Abstract
Devices, systems and methods supplement, repair, or replace a
native heart valve. The devices, systems, and methods employ an
implant that, in use, extends adjacent a valve annulus. The implant
includes a mobile neoleaflet element that occupies the space of at
least a portion of one native valve leaflet. The implant mimics the
one-way valve function of a native leaflet, to resist or prevent
retrograde flow. The implant restores normal coaptation of the
leaflets to resist retrograde flow, thereby resisting eversion
and/or prolapse, which, in turn, reduces regurgitation.
Inventors: |
Macoviak, John A.; (La
Jolla, CA) ; Chang, Robert T.; (Belmont, CA) ;
Rahdert, David A.; (San Francisco, CA) ; Machold,
Timothy R.; (Moss Beach, 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: |
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Document Identifier |
Publication Date |
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US 0010287 A1 |
January 13, 2005 |
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Family ID: |
45353279 |
Appl. No.: |
10/676815 |
Filed: |
October 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10676815 |
Oct 1, 2003 |
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09666617 |
Sep 20, 2000 |
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6893459 |
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10676815 |
Oct 1, 2003 |
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PCT/US02/31376 |
Oct 1, 2002 |
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60326590 |
Oct 1, 2001 |
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60429462 |
Nov 26, 2002 |
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60429709 |
Nov 26, 2002 |
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60429444 |
Nov 26, 2002 |
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Current U.S.
Class: |
623/2.36 ;
623/2.18 |
Current CPC
Class: |
A61F 2/2418 20130101;
A61F 2/2445 20130101; A61F 2/2454 20130101 |
Class at
Publication: |
623/002.36 ;
623/002.18 |
International
Class: |
A61F 002/24 |
Claims
What is claimed is:
1. An implant that supplements, repairs, or replaces a native heart
valve leaflet or leaflets 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, a neoleaflet element coupled to the scaffold within
pseudo-annulus and being sized and shaped to occupy the space of at
least a portion of one native heart valve leaflet to provide a
one-way valve function that, in response to a first pressure
condition, assumes a valve opened condition within the
pseudo-annulus and, in response to a second pressure condition,
assumes a valve closed condition within the pseudo-annulus, and
spaced-apart struts appended to the scaffold and being sized and
configured to contact tissue near or within the heart valve annulus
to brace the scaffold against migration within the annulus during
the one-way valve function.
2. An implant according to claim 1 wherein the scaffold 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 scaffold and the
struts each comprises a wire-form structure.
5. An implant according to claim 1 wherein the neoleaflet element
includes a bridge appended to the scaffold.
6. An implant according to claim 5 wherein the neoleaflet element
includes a material covering the bridge.
7. An implant according to claim 5 wherein the bridge is a
wire-form structure.
8. An implant according to claim 1 wherein the neoleaflet element
includes a duckbill valve within the psuedo-annulus.
9. An implant according to claim 1 wherein the neoleaflet element
includes a membrane within the pseudo-annulus.
10. An implant according to claim 1 wherein the neoleaflet element
is sized and configured to coapt with a native leaflet when in the
valve closed condition.
11. An implant according to claim 1 wherein the scaffold,
neoleaflet element, and the struts are collapsible for placement
within a catheter.
12. 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.
13. 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.
14. An implant according to claim 1 wherein the scaffold,
neoleaflet element, and struts include materials and shapes to
provide a spring-like bias for compliance with anatomy near or
within the heart valve annulus.
15. An implant according to claim 1 wherein the struts apply
tension to tissue.
16. An implant according to claim 1 wherein the struts apply
tension to tissue to reshape the heart valve annulus.
17. An implant according to claim 1 wherein the struts apply
tension to separate tissue along an axis of the heart valve
annulus.
18. An implant according to claim 1 further including a second
heart valve treatment element appended to the scaffold to affect a
heart valve function.
19. An implant according to claim 18 wherein the second heart valve
treatment element includes means for reshaping the heart valve
annulus for leaflet coaptation.
20. An implant according to claim 18 wherein the second heart valve
treatment element includes means for stretching leaftlet
commissures for leaflet coaptation.
21. A method for supplementing, repairing, or replacing a native
heart valve leaflet or leaflets comprising the steps of introducing
an implant as defined in claim 1 into a heart, and providing a
one-way valve function that, in response to a first pressure
condition, assumes a valve opened condition and, in response to
second pressure condition, assumes a valve closed condition 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 neoleaflet element as defined in claim 1 occupying the
space of at least a portion of one native heart valve leaflet to
provide the one-way valve function, and with the spaced-apart
struts as defined in claim 1 contacting tissue near or within the
heart valve annulus to brace the scaffold against migration within
the annulus during the one-way valve function.
22. A method according to claim 21 wherein the introducing step
comprises using an open heart surgical procedure.
23. A method according to claim 21 wherein the introducing step
comprises using a surgical procedure in which the implant is
carried within a catheter.
24. A method according to claim 21 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 Ser.
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 Ser. 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
Ser. No. 60/429,444, filed Nov. 26, 2002, and entitled "Heart Valve
Remodeling Devices;" U.S. Provisional Patent Application Ser. No.
60/429,709, filed Nov. 26, 2002, and entitled "Neo-Leaflet Medical
Devices;" and U.S. Provisional Patent Application Ser. 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. 1) 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. 2 and 3) 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. 2), 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. 2 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. 3)--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. 4 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. 5 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. 6 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. As an example, FIG. 7 shows a cutaway view of
a human heart where the anterior leaflet 910 has torn chords 920.
As a result, valve flailing and blood regurgitation occur during
ventricular systole.
[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
supplement, repair, or replace a native heart valve leaflet. The
devices, systems, and methods include an implant that, in use,
rests adjacent a valve annulus. The implant defines a
pseudo-annulus. The implant includes a neoleaflet element that
occupies the space of at least a portion of one native valve
leaflet. The implant allows the native leaflets to coexist with the
implant, or if desired or indicated, one or more native leaflets
can be removed and replaced by the implant. The neoleaflet element
of the implant is shaped and compressed to mimic the one-way valve
function of a native leaflet. The implant includes spaced-apart
struts that are sized and configured to contact tissue near or
within the heart valve annulus to brace the implant against
migration within the annulus during the one-way valve function.
[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. 1 is a perspective, anterior anatomic view of the
interior of a healthy heart.
[0026] FIG. 2 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. 3 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. 4 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. 5 is a posterior oblique cutaway view of a portion of a
human heart, showing a dysfunctional prolapsing mitral valve during
ventricular systole, with the leaflets not properly coapting,
causing regurgitation.
[0030] FIG. 6 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. 7 is a posterior oblique cutaway view of a portion of a
human heart, showing a dysfunctional mitral valve during
ventricular systole, caused by torn chords, that leads to
regurgitation.
[0032] FIG. 8 is a perspective view of an implant that supplements,
repairs, or replaces a native heart valve leaflet, the implant
being sized and configured to extend about a heart valve annulus
and including a neoleaflet element that occupies the space of at
least one native valve leaflet.
[0033] FIG. 9A is a perspective, anatomic view of the implant shown
in FIG. 8, with the neoleaflet element installed over an anterior
leaflet of a mitral valve to restore normal function.
[0034] FIG. 9B is a perspective, anatomic view of the implant of
the type shown in FIG. 8, with the neoleaflet element installed
over a posterior leaflet of a mitral valve to restore normal
function to the native valve leaflet.
[0035] FIG. 10 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being shown installed on a
mitral valve annulus and having a neoleaflet element that occupies
the space of at least one native valve leaflet, the implant also
including a framework that rises above the neoleaflet element in
the atrium to help fix and stabilize the implant.
[0036] FIG. 11 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being sized and configured
to extend about a heart valve annulus and including two neoleaflet
elements that occupy the space of two native valve leaflets.
[0037] FIG. 12 is a perspective view of the implant shown in FIG.
11, with the two neoleaflet elements in a valve opened condition,
as would exist during ventricular diastole.
[0038] FIG. 13 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being sized and configured
to extend about a heart valve annulus and including a neoleaflet
element formed by a membrane.
[0039] FIG. 14 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being sized and configured
to extend about a heart valve annulus and including a neoleaflet
element formed by a membrane, the implant also including a
framework that rises above the neoleaflet element in the atrium to
help fix and stabilize the implant.
[0040] FIG. 15 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being sized and configured
to extend about a heart valve annulus and including two neoleaflet
elements to form a duckbill valve, the valve being shown in an
opened condition as would exist during ventricular diastole.
[0041] FIG. 16 is a perspective view of the implant shown in FIG.
15, the duckbill valve being shown in a closed condition as would
exist during ventricular systole.
[0042] FIGS. 17 and 18 are side views of the implant shown,
respectively, in FIGS. 15 and 16, with the duckbill valve,
respectively, in an opened and a closed condition.
[0043] FIG. 19 is a perspective view of another illustrative
embodiment of an implant that supplements, repairs, or replaces a
native heart valve leaflet, the implant being sized and configured
to extend about a heart valve annulus and including two neoleaflet
elements formed by a duckbill valve, the valve being shown in an
opened condition as would exist during ventricular diastole, the
implant also including a framework that rises above the neoleaflet
elements in the atrium to help fix and stabilize the implant.
[0044] FIG. 20 is a perspective view of the implant shown in FIG.
19, the duckbill valve being shown in a closed condition as would
exist during ventricular systole.
[0045] FIGS. 21A to 21C diagrammatically show a method of gaining
intravascular access to the left atrium for the purpose of
deploying a delivery catheter to place an implant in a valve
annulus to supplement, repair, or replace a native heart valve
leaflet
DETAILED DESCRIPTION
[0046] 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.
[0047] FIGS. 8 and 9 show an implant 400 sized and configured to
supplement, repair, or replace a dysfunctional native heart valve
leaflet or leaflets. In use (see, in particular, FIG. 9), the
implant 400 defines a pseudo-annulus that rests adjacent the native
valve annulus and includes a neoleaflet element that occupies the
space of at least a portion of one native valve leaflet. The
implant 400 allows the native leaflets to coexist with the implant
400. If desired or indicated, one or more native leaflets can be
removed and replaced by the implant 400.
[0048] In its most basic form, the implant 400 is made--e.g., by
machining, bending, shaping, joining, 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 to impart biocompatibility, or a
combination of such materials. The material is also desirably
radio-opaque to facilitate fluoroscopic visualization.
[0049] As FIG. 8 shows, the implant 400 includes a base or scaffold
420 that, in the illustrated embodiment, is sized and configured to
rest adjacent the mitral annulus. At least a portion of the base
420 forms an annular body that approximates the shape of the native
annulus. For this reason, the base 420 will also be referred to as
a "pseudo-annulus."
[0050] The base 420 supports a bridge 430 that extends into the
valve. The bridge 430 is sized and configured (see FIG. 9A) to
overlay the space of at least a portion of one native valve
leaflet. In FIG. 9A, the bridge 430 overlays an anterior leaflet.
However, as FIG. 9B shows, the bridge 430 could be oriented to
overlay a posterior leaflet. As will be described later (see FIG.
11), two bridges can be formed to overlay both leaflets.
[0051] As FIG. 8 shows, the implant 400 includes a material 410
that covers or spans the bridge 430. The spanning material 410 may
be attached to the implant 400 with one or more attachment means
440. For example, the spanning materials 410 may be sewn, glued, or
welded to the implant 400, or it may be attached to itself when
wrapped around the implant 400. The spanning material 410 may be
made from a synthetic material (for example, thin Nitinol,
polyester fabric, polytetrafluoroethylene or PTFE, silicone, or
polyurethane) or a biological material (for example, human or
animal pericardium).
[0052] Together, the bridge 430 and the spanning material 410
comprise a neoleaflet element 470 coupled to the base 420. The
neoleaflet element 470 may be rigid, semi-rigid, or flexible. The
neoleaflet element 470 is coupled to the base 420 in a manner that
exerts a mechanical, one-way force to provide a valve function that
responds to differential pressure conditions across the neoleaflet
element. In response to one prescribed differential pressure
condition, the neoleaflet element 470 will deflect and, with a
native leaflet, assume a valve opened condition. In response to
another prescribed pressure condition, the neoleaflet element 470
will resist deflection and, by coaptation with a native leaflet (or
a companion neoleaflet element) at, above, or below the annulus
plane, maintain a valve closed condition.
[0053] In the context of the illustrated embodiment (when installed
in a mitral valve annulus), the neoleaflet element resists being
moved in the cranial (superior) direction (into the atrium), when
the pressure in the ventricle exceeds the pressure in the
atrium--as it would during ventricular systole. The neoleaflet
element 470 may move, however, in the caudal (inferior) direction
(into the ventricle), when the pressure in the ventricle is less
than the pressure in the atrium--as it would during ventricular
diastole. The neoleaflet element 470 thereby mimics the one-way
valve function of a native leaflet, to prevent retrograde flow.
[0054] The implant 400 is sized and shaped so that, in use adjacent
the valve annulus of the mitral valve, it keeps the native valve
leaflet closed during ventricular systole (as shown in FIGS. 9A and
9B), to prevent flailing and/or prolapse of the native valve
leaflet it overlays during ventricular systole. The implant 400
thus restores to the heart valve leaflet or leaflets a normal
resistance to the high pressure developed during ventricular
contractions, resisting valve leaflet eversion and/or prolapse and
the resulting back flow of blood from the ventricle into the atrium
during ventricular systole. The pressure difference serves to keep
valve leaflets tightly shut during ventricular systole. The implant
400, however, does not interfere with opening of the native valve
leaflet or leaflets during ventricular diastole (see, e.g., FIG.
12). The implant 400 allows the leaflet or leaflets to open during
ventricular diastole, so that blood flow occurs from the atrium
into the ventricle. The implant 400 thereby restores normal one-way
function to the valve, to prevent retrograde flow.
[0055] The functional characteristics of the implant 400 just
described can be imparted to the neoleaflet element 470 in various
ways. For example, hinges and springs (mechanical or plastic) can
be used to couple the bridge to the base. Desirably, the implant
400 is made from materials that provide it with spring-like
characteristics.
[0056] As shown in FIG. 8, in the illustrated embodiment, the base
420 and bridge 430 are shaped from a length of wire-formed
material. The shape and material properties of the implant
determine its physical spring-like characteristics as well as its
ability to open in one direction only. The spring-like
characteristics of the implant 400 allow it to respond dynamically
to changing differential pressure conditions within the heart.
[0057] More particularly, in the illustrated mitral valve
embodiment, when greater pressure exists superior to the bridge 430
than inferior to the bridge (i.e., during ventricular diastole),
the shape and material properties of the bridge 430 accommodate its
deflection into the ventricle--i.e., an opened valve condition (as
FIG. 12 shows in another illustrative embodiment). When greater
pressure exists inferior to the bridge 430 than superior to the
bridge (i.e., during ventricular systole), the shape and material
properties of the bridge 430 enable it to resist superior movement
of the leaflet into the atrium, and otherwise resist eversion
and/or prolapse of the valve leaflet into the atrium (as FIGS. 9A
and 9B also show).
[0058] 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.
[0059] For example, percutaneous vascular access can be achieved by
conventional methods into the femoral or jugular vein. As FIG. 21A
shows, under image guidance (e.g., fluoroscopic, ultrasonic,
magnetic resonance, computed tomography, or combinations thereof),
a catheter 52 is steered through the vasculature into the right
atrium. A needle cannula 54 carried on the distal end of the
catheter is deployed to pierce the septum between the right and
left atrium. As FIG. 21B shows, a guide wire 56 is advanced
trans-septally through the needle catheter 52 into the left atrium.
The first catheter 52 is withdrawn, and (as FIG. 21C shows) under
image guidance, an implant delivery catheter 58 is advanced over
the guide wire 56 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.
[0060] The distal end of the catheter 58 encloses an implant 400,
like that shown in FIG. 8, which is constrained in a collapsed
condition. A flexible push rod in the catheter 58 can be used to
expel the implant 400 from the catheter 58. Free of the catheter,
the implant 400 will self-expand to its preordained configuration,
e.g., like that shown in FIGS. 9A or 9B.
[0061] The implant 400 may be fixed to the annulus in various ways.
For example, the implant 400 may be secured to the annulus with
sutures or other attachment means (i.e. barbs, hooks, staples,
etc.) Also, the implant 400 may be secured with struts or tabs 450
(see FIGS. 8 and 9A), that extend from the base 420 above or below
the plane of the annulus. The struts 450 are preferably configured
with narrow connecting members that extend through the valve
orifice so that they will not interfere with the opening and
closing of the valve.
[0062] In this arrangement, the struts 450 are desirably sized and
configured to contact tissue near or within the heart valve annulus
to brace the base 420 against migration within the annulus during
the one-way valve function of the neoleaflet element. In this
arrangement, it is also desirable that the base 420 be "elastic,"
i.e., the material of the base 420 is selected to possess a desired
spring constant. This means that the base 420 is sized and
configured to possess a normal, unloaded, shape or condition (shown
in FIG. 8), in which the base 420 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 450 are
intended to contact. In the illustrated embodiment, the base 420 is
shown resting along the major (i.e., longest) axis of the valve
annulus, with the struts 450 contacting tissue at or near the
leaflet commissures. However, other orientations are possible. The
struts 450 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 base
420 the ability to be elastically compressed out of its normal,
unloaded condition, in response to external compression forces
applied at the struts 450. The base 420 is sized and configured to
assume an elastically loaded, in net compression condition, during
which the struts 450 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 450 is
intended to occur) (see FIGS. 9A or 9B). When in its elastically
loaded, net compressed condition (see FIGS. 9A and 9B), the base
450 can exert forces to the tissues through the struts 450. These
forces hold the base 420 against migration within the annulus.
Furthermore, when the struts 450 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 base 450 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 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.
[0063] As the preceding disclosure demonstrates, different forms of
heart valve treatment can be performed using a single implant.
[0064] Implants having one or more of the technical features just
described, to thereby function in situ as a neo-leaflet, may be
sized and configured in various ways. Various illustrative
embodiments will now be described.
[0065] In FIG. 10, an implant 600 (like implant 400) includes a
base 620 that defines a pseudo-annulus, with a bridge 630 carrying
a spanning material 640 together comprising a neoleaflet element
650 appended to the base 620 within the pseudo-annulus. The
neoleaflet element 650 overlays an anterior native leaflet with the
same purpose and function described for the implant 400.
Alternatively, the neoleaflet element 650 could overlay a posterior
native leaflet, as FIG. 9B shows. The implant 600 also includes
struts 670, which desirably contact and exert force against tissue
near or within the annulus (in the manner previously described) to
brace the base 420 against migration within the annulus.
[0066] In addition, the implant 600 includes an orientation and
stabilization framework 610 that may extend from the annulus to the
atrial dome. In FIG. 10, the framework 610 rises from the base 620
with two substantially parallel arched wires, which connect to form
a semicircular hoop above the base 620. The framework 610 helps to
accurately position the implant 600 within the atrium, and also
helps to secure the implant 600 within the atrium.
[0067] Preferably the framework 610 does not interfere with atrial
contractions, but instead is compliant enough to contract with the
atrium. As such, the implant 600 may have nonuniform flexibility to
improve its function within the heart.
[0068] FIGS. 11 and 12 show another illustrative embodiment of an
implant 700. In FIGS. 11 and 12, the implant 700 contains two
neo-leaflet elements. The implant 700 includes an anterior bridge
730 spanned by an anterior bridge material 710, and a posterior
bridge 735 spanned by a posterior bridge material 720. The bridges
and materials together comprise anterior and posterior neoleaflet
elements 780A and 780P. The implant 700 also includes an
orientation and stabilization framework 770, shown having a
configuration different than the framework 610 in FIG. 9, but
having the same function and serving the same purpose as previously
described for the framework 610.
[0069] In FIGS. 11 and 12, the base 760 includes structures like
the anchoring clips 740 that, in use, protrude above the plane
formed by the annulus of the valve. Additionally, the implant 700
may be secured with struts 750 that extend from the base 760 on
narrow connecting members and below the plane of the annulus into
the ventricular chamber. The anchoring clips 740 and struts 750
desirably contact and exert force against tissue near or within the
annulus (in the manner previously described) to brace the base 760
against migration within the annulus. FIG. 11 shows the dual neo-S
leaflets 780A and 780B (i.e., the covered anterior and posterior
bridges 730 and 735) in a closed valve position. FIG. 12 shows the
dual neo-leaflets 780A and 780B in an open valve position.
[0070] FIG. 13 shows another illustrative embodiment of an implant
1000 having a full sewing ring 1030 with a membrane 1010 that
serves as a neo-leaflet. The device 1000 has an opening 1020 though
the sewing ring 1030 opposite the membrane 1010 for blood flow.
Alternatively, this embodiment could have two neo-leaflets. This
embodiment could be surgically attached to the valve annulus and/or
combined with a framework for anchoring the device within the
atrium using catheter based intraluminal techniques. Additionally,
the device may be secured with struts 1040 that extend from the
base on narrow connecting members and below the plane of the
annulus into the ventricular chamber. The struts 1040, which
desirably contact and exert force against tissue near or within the
annulus (in the manner previously described) to brace the base 420
against migration within the annulus.
[0071] As can be seen, a given implant may carry various structures
or mechanisms to enhance the anchorage and stabilization of the
implant in the heart valve annulus. The mechanisms may be located
below the plane of the annulus, to engage infra-annular heart
tissue adjoining the annulus in the ventricle, and/or be located at
or above the plane of the annulus, to engage tissue on the annulus
or in the atrium. These mechanisms increase the surface area of
contact between the implant and tissue. A given implant can also
include tissue in-growth surfaces, to provide an environment that
encourages the in-growth of neighboring tissue on the implant. Once
in-growth occurs, the implant becomes resistant to migration or
dislodgment from the annulus. Conventional in-growth materials such
as polyester fabric can be used.
[0072] FIG. 14 shows another illustrative embodiment of an implant
1100 having a framework 1120 and struts or tabs 1110. This implant
1100 includes a membrane 1130, that serves as a neo-leaflet,
attached to the base 1140 of the device with an attachment means
1150.
[0073] FIG. 15 shows another illustrative embodiment of an implant
1200. In this embodiment, the implant 1200 includes a base 1220
that defines a pseudo-annulus and that, in use, is rests adjacent
all or a portion of a native valve annulus. The base 1240 supports
a duckbill valve 1210, which forms a neoleaflet element.
Peripherally supported on the base 1240, the duckbill valve 1210
rests in the pseudo-annulus. Struts 1230 (which also carry
additional tab structures to increase the surface area of tissue
contact) help brace the base 1240 to tissue near or within the
heart valve annulus.
[0074] In this embodiment, the duckbill valve 1210 replaces the
native anterior and posterior leaflets. The duckbill valve 1210
serves as dual neo-leaflets, which mutually open and close in
response to changes in pressure, replacing the function of the
native leaflets. FIG. 15 shows the duckbill valve 1210 in the open
valve position. In FIG. 15, the arrow shows the direction of blood
flow through the opened valve. FIG. 16 shows the duckbill valve in
the closed valve position. When closed, the duckbill valve 1210
resists eversion and regurgitation.
[0075] When the implant 1200 is used to replace a mitral valve (see
FIGS. 17 and 18), the duckbill valve 1210 extends from the plane of
the valve annulus and into the ventricle. The duckbill valve 1210
is shown to have a more rigid or thick composition emerging from
the base member, and gradually becoming less rigid or thick away
from the base member. This variation in mechanical properties
ensures a valve that responds dynamically to pressure changes, but
that is also rigid enough to not become everted. FIG. 17 shows the
valve 1210 in an opened valve condition. In FIG. 17, the arrow
shows the direction of blood flow through the opened valve. FIG. 18
shows the duckbill valve in the closed valve position, without
eversion and regurgitation.
[0076] FIGS. 19 and 20 show another illustrative embodiment of an
implant 1600 of the type shown in FIGS. 15 and 16. Like the implant
1200, the implant 1600 includes base 1620 defining a pseudo-annulus
to which a duckbill valve 1630 is appended, which serves as a
neoleaflet element to replace the native anterior and posterior
leaflets and serves as dual neo-leaflets. FIG. 19 shows the
duckbill valve 1630 in the open valve position, allowing forward
flow of blood through the opened valve. FIG. 20 shows the duckbill
valve 1630 in the closed valve position, resisting eversion and
regurgitation.
[0077] In FIGS. 19 and 20, the implant 1600 includes an orientation
and stabilization framework 1610. The framework 1610 rises from the
base 1620 as two arches extending from opposite sides of the base
1620. The dual arch framework 1610 possesses compliance to contract
with the atrium. As before explained, the framework 1610 helps to
accurately position the implant 1600 within the atrium, and also
helps to secure the implant 600 within the atrium. The implant 1600
also includes struts 1640, which desirably contact and exert force
against tissue near or within the annulus (in the manner previously
described) to brace the base 1620 against migration within the
annulus.
[0078] 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 prevent or resist 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.
* * * * *