Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE AND METHODS FOR ENDOSCOPIC ANNULOPLASTY
REFERENCE TO PRIORITY DOCUMENT
This application claims priority of co-pending U.S. Provisional Patent
Application Serial No. 60/674,931 entitled " DEVICE AND METHODS FOR
ENDOSCOPIC ANNULOPLASTY", filed April 25, 2005. Priority of the
aforementioned filing dates is hereby claimed, and the disclosure of the
Provisional Patent Application is hereby incorporated by reference in their
entirety.
This application is a continuation-in-part of U.S. Application Serial
No. 10/820,581 entitled "METHODS AND APPARATUS FOR CARDIAC VALUE
REPAIR", filed April 7, 2004, which is a continuation of U.S. Patent
Application
No. 10/635,776, filed August 5, 2003, which is a continuation of U.S. Patent
Application No. 09/544,930, filed April 7, 2000, now U.S. Patent No.
6,629,534,
which claimed the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent
Application No. 60/128,690, filed on April 9, 1999 under 37 CFR 1.78(a). The
full
disclosures of the aforementioned applications are incorporated herein by
reference.
BACKGROUND
The present-disclosure relates generally to medical methods, devices, and
systems. In particular, the present disclosure relates to methods, devices,
and
systems for the endovascular or minimally invasive surgical repair of the
atrioventricular valves of the heart, particularly the mitral valve.
Mitral valve regurgitation is characterized by retrograde flow from the left
ventricle of a heart through an incompetent mitral valve into the left atrium.
During a normal cycle of heart contraction (systole), the mitral valve acts as
a
check valve to prevent flow of oxygenated blood back into the left atrium. In
this
way, the oxygenated blood is pumped into the aorta through the aortic valve.
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Regurgitation of the valve can significantly decrease the pumping efficiency
of
the heart, placing the patient at risk of severe, progressive heart failure.
Mitral valve regurgitation can result from a number of different mechanical
defects in the mitral valve. The valve leaflets, the valve chordae which
connect
the leaflets to the papillary muscles, or the papillary muscles themselves may
be
damaged or otherwise dysfunctional. Commonly, the valve annulus may be
damaged, dilated, or weakened limiting the ability of the mitral valve to
close
adequately against the high pressures of the left ventricle.
The most common treatments for mitral valve regurgitation rely on valve
replacement or strengthening of the valve annulus by implanting a mechanical
support ring or otfier structure. The latter is generally referred to as valve
annuloplasty. A recent technique for mitral valve repair which relies on
suturing
adjacent segments of the opposed valve leaflets together is referred to as the
"bow-tie" or "edge-to-edge" technique. While all these techniques can be very
effective, they usually rely on open heart surgery where the patient's chest
is
opened, typically via a sternotomy, and the patient placed on cardiopulmonary
bypass. The need to both open the chest and place the patient on bypass is
traumatic and has associated morbidity.
For these reasons, it would be desirable to provide alternative and
additional methods, devices, and systems for performing the repair of mitral
and
other cardiac valves, including the tricuspid valve which is the other
atrioventricular valve. Such methods, devices, and systems should preferably
not require open chest access and be capable of being performed
endovascularly, i.e., using devices which are advanced to the heart from a
point
in the patient's vasculature remote from the heart. Still more preferably, the
methods, devices, and systems should not require that the heart be bypassed,
although the methods, devices, and systems should be useful with patients who
are bypassed and/or whose heart may be temporarily stopped by drugs or other
techniques.
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SUMMARY
The present disclosure provides methods, devices, and systems for the
endovascular repair of cardiac valves, particularly the atrioventricular
valves
which inhibit back flow of blood from a heart ventricle during contraction
(systole),
most particularly the mitral valve between the left atrium and the left
ventricle. By
"endovascular," it is meant that the procedure(s) are performed with
interventional tools, guides, and supporting catheters and other equipment
introduced to the heart chambers from the patient's arterial or venous
vasculature
remote from the heart. The interventional tools and other equipment may be
introduced percutaneously, i.e., through an access sheath, or may be
introduced
via a surgical cut down, and then advanced from the remote access site through
the vasculature until they reach the heart. Thus, the procedures will
generally
not require penetrations made directly through the exterior heart muscle,
i.e.,
myocardium, although there may be some instances where penetrations will be
made interior to the heart, e.g., through the interatrial septum to provide
for a
desired access route. While the procedures will usually be percutaneous and
intravascular, many of the tools will find use in minimally invasive and open
surgical procedures as well that includes a surgical incision or port access
through the heart wall. In particular, the tools for capturing the valve
leaflets prior
to attachment can find use in virtually any type of procedure for modifying
cardiac
valve function.
The atrioventricular valves are located at the junctions of the atria and
their respective ventricles. The atrioventricular valve between the right
atrium
and the right ventricle has three valve leaflets (cusps) and is referred to as
the
tricuspid or right atrioventricular valve. The atrioventricular valve between
the left
atrium and the left ventricle is a bicuspid valve having only two leaflets
(cusps)
and is generally referred to as the mitral valve. In both cases, the valve
leaflets
are connected to the base of the atrial chamber in a region referred to as the
valve annulus, and the valve leaflets extend generally downwardly from the
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annulus into the associated ventricle. In this way, the valve leaflets open
during
diastole when the heart atria fill with blood, allowing the blood to pass into
the
ventricle. During systole, however, the valve leaflets are pushed together and
closed to prevent back flow of blood into the atria. The lower ends of the
valve
leaflets are connected through tendon-like tissue structures called the
chordae,
which in turn are connected at their lower ends to the papillary muscles.
Interventions described herein may be directed at any one of the leaflets,
chordae, annulus, or papillary muscles, or combinations thereof. It will be
the
general purpose of such interventions to modify the manner in which the valve
leaflets coapt or close during systole so that back flow or regurgitation is
minimized or prevented. While the procedures will be most useful with the
atrioventricular valves, at least some of the tools described hereinafter may
be
useful in the repair of other cardiac valves, including the aortic valve.
The methods described herein will usually comprise accessing a patient's
vasculature at a location remote from the heart, advancing an interventional
tool
through the vasculature to a ventricle and/or atrium, and engaging the tool
against a tissue structure which forms or supports the atrioventricular valve.
By
engaging the tool against the tissue structure, the tissue structure is
modified in a
manner that reduces valve leakage or regurgitation during ventricular systole.
The tissue structure may be any of one or more of the group consisting of the
valve leaflets, chordae, the valve annulus, and the papillary muscles, atrial
wall,
ventricular wall or adjacent structures. Optionally, the interventional tool
will be
oriented relative to the atrioventricular valve and/or tissue structure prior
to
engaging the tool against the tissue structure. The interventional tool may be
self-orienting (e.g., pre-shaped) or may include active mechanisms to steer,
adjust, or otherwise position the tool. Alternatively, orientation of the
interventional tool may be accomplished in whole or in part using a separate
guide catheter, where the guide catheter may be pre-shaped and/or include
active steering or other positioning means such as those devices set forth in
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United States Patent Application serial numbers 10/441,753 filed May 19, 2003,
10/441,508 filed May 19, 2003 and 10/441,687 filed May 19, 2003, all of which
are expressly incorporated by reference herein. In all cases, it will usually
be
desirable to confirm the position prior to engaging the valve leaflets or
other
tissue structures. Such orienting step may comprise positioning the tool
relative
to a line of coaptation in the atrioventricular valve, e.g., engaging
positioning
elements in the valve commissures and confirming the desired location using a
variety of imaging means such as MRI, intracardiac echocardiography (ICE),
transesophageal echo (TEE), fluoroscopy, endoscopy, intravascular ultrasound
(IVUS) and the like.
In a first aspect, the tissue structure comprises the valve leaflets and the
engaging step comprises attaching one or more opposed points on or along the
valve leaflets together. In the case of the bicuspid mitral valve, the
attachment
points may be located at or near the center of each leaflet, creating a
generally
symmetric structure with two openings, i.e., between the attachment point(s)
and
each of the two commissures. Alternatively, the attachment points may be close
to each of the commissures. Both will effectively reduce the area in which the
valve can open. In the case of the tricuspid valve, any two of the three
leaflets
can be partially or totally closed together or all three may be partially
closed
together.
In both cases, the attachment of the valve leaflets may be performed in a
variety of ways, including suturing, clipping, stapling, riveting, gluing,
fusing, or
the like. While each of these approaches may differ significantly in the
protocols
and devices used for performing them, the end result will be the same, i.e.,
improved ability of the atrioventricular valve to close against the elevated
pressures within the ventricle during systole. In order to improve apposition
of
the valve leaflets, it may be preferred to attach the leaflets at a point
spaced
inwardly from the free edge of the leaflet. Usually, the attachment point
within
the valve leaflet will be located from 1 mm to 4 mm inward from the free edge.
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It will frequently be desirable to stabilize the interventional tool relative
to
the valve leaflets and other heart tissue structures at least some points
during the
interventional procedure. In a broad sense, such stabilization is intended
primarily to couple motion of the interventional tool to the motion of the
heart so
that the tool may then engage the valve leaflets or other target tissue
structures
with minimum differential motion. The stabilization may be achieved either
through the interventional tool or through a guide catheter or other platform
which
is used to deliver the interventional tool. In both cases, stabilization will
usually
be achieved by engaging a tissue structure of the heart, such as the
interatrial
septum, the atrial wall, the valve annulus, the valve chordae, the papillary
muscles, or the like. For antegrade approaches, immobilization of either the
guide catheter, the interventional tool, or both relative to the valve annulus
or
valve commissures will be particularly effective. For retrograde approaches,
immobilization against the papillary muscles, the chordae, or the valve
leaflets
themselves may be particularly effective. Stabilization should be
distinguished
from valve capture which is usually performed after the interventional tool
and/or
guide catheter have been stabilized within the heart. Thus, the methods may
comprise up to four separate steps or phases prior to valve affixation. First,
the
interventional tool and/or guide catheter may be positioned, either actively
or
passively. Second, the interventional tool and/or guide catheter may be
stabilized within the heart. Next, the interventional tool may be used to
capture
the valve leaflets. Then, prior to affixation, the valve leaflets may be
positioned
and, if necessary, repositioned in order to determine that a particular
coaptation
and affixation are capable of inhibiting the valve regurgitation. Finally,
once
adequate regurgitation inhibition has been confirmed, the valve leaflets may
be
affixed in any of the manners described below.
In a particular approach, the interventional tool may be stabilized by
mechanically fixing the shape of the tool after the tool has been advanced to
a
position proximate the atrioventricular valve. For example, the interventional
tool
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can comprise a plurality of linked elements which can be locked into place,
e.g., a "goose-neck" device. Such mechanically lockable devices may be used
by themselves or in conjunction with any of the other stabilization devices
described herein.
When attaching portions of the valve leaflets together, it will frequently be
desirable to temporarily capture the valve leaflets before implementing the
final
attachment step. For example, the leaflets can be captured using forceps or
other graspers introduced as part of or separately from the interventional
tool.
After capturing the valve leaflets, flow through the valve can be observed by
conventional cardiac imaging techniques, such as trans-esophegeal
echocardiography (TEE), intracardiac echocardiography (ICE) or other
ultrasonic
imaging technique, fluoroscopy, angioscopy, catheter based magnetic resonance
imaging (MRI), computed tomography (CT ) and the like. By thus observing the
flow through the valves, and more importantly whether or not back flow or
regurgitation continues or has been sufficiently inhibited, the desired
attachment
configuration for the leaflets can be determined. If continued regurgitation
is
observed, the valve leaflets may be repositioned and the presence or absence
of
regurgitation again determined. Such repositioning steps may be continued
until
a position is identified in which the regurgitation is sufficiently inhibited.
Additionally, other considerations, such as position of the attachment within
the
leaflet, stress placed on the leaflet, and other factors can be visualized
before
deciding on the final attachment point(s). In a preferred example, the valve
leaflets may be coapted by a grasping instrument which also has a fixation
mechanism, such as stapling, suturing, clipping or riveting as previously
described, so that once a desirable attachment configuration is temporarily
achieved, the final attachment can be made using the same instrument.
Grasping of the valve leaflets can be accomplished using articulated graspers,
vacuum-assisted graspers, grasping pins, or other temporary attachment modes
as described in more detail below. After the leaflets are in the desired
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configuration, they may be permanently secured together by any of the
techniques described above.
In a second aspect, the tissue structure comprises the chordae and the
engaging step comprises linking opposed chordae together, i.e., chordae
attached to different valve leaflets. Usually, the chordae will be partially
gathered
or coupled together using a suture or other loop structure. In some instances
it
may be desirable to closely tie the chordae together at one or more locations.
In a third aspect, the tissue structure comprises the chordae and the
engaging step comprises applying energy to shorten the chordae. Particular
forms of heat energy, most particularly radiofrequency energy, have been found
to be able to modify and shrink collagen so that supporting chordae may be
tightened. By applying energy to shorten one or more of the chordae attaching
either or both (or all three in the case of the tricuspid valve) valve
leaflets, the
flow through the atrioventricular valve can be modified and regurgitation
minimized. In one aspect, the chordae will be initially grasped or captured
and
manipulated to temporarily apply tension to the valve leaflets. The effect of
such
temporary shortening can then be visually assessed and, if a desired
improvement in valve performance is observed, energy can be applied to shorten
the chordae. In many cases, however, it may be preferable to apply a clip,
ring,
suture loop, or other mechanical element to permanently twist, plicate, or
otherwise shorten the chordae, as described elsewhere herein.
In a fourth aspect, the tissue structure comprises the valve annulus and
the engaging step comprises circumferentially tightening or shortening the
annulus. In a preferred technique, the annulus will be strengthened by
positioning and attaching a supporting structure over the annulus in a manner
broadly analogous to the open surgical placement of an annuloplasty ring.
Alternatively, the annulus can be tightened by surgical plication techniques,
or in
some instances by shrinking tissue within the annulus by applying
radiofrequency
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energy as generally described above in connection with shortening of the
chordae.
In a fifth aspect, the tissue structure comprises the papillary muscles and
the engaging step comprises capturing and drawing opposed points or portions
of the papillary muscles together. This approach is similar in many respects
to
capture of the chordae, and will generally comprise suturing or otherwise
forming
a linkage between the opposed portions of the papillary muscles. As with the
chordae, it will generally not be desirable to fully close the papillary
muscles
together, although in some instances such an approach may also find use.
In all the aspects of the method described above, the heart will usually
remain beating while the interventional tool is engaged against the tissue
structure. When the heart is beating, however, it may be desirable to
temporarily
stop valve action during at least a portion of the procedure, particularly to
facilitate grasping of the valve leaflets when such a technique is being
employed.
The valve action can be slowed temporarily by decreasing the heart rate with
intravenous infusion of a beta blocker, such as esmolol, or can be completely
stopped for a brief time, e.g., five to ten seconds, by infusion of a drug,
such as
adenosine. Alternatively, the valve action can be stopped by temporarily
raising
the pressure in the associated ventricle to a pressure above that in the
atrium
during diastole. While the heart will continue to beat, the motion of the
valve
leaflets opening and closing will be stopped to facilitate grasping. As a
further
alternative, it will be possible to mechanically restrain the leaflets
directly or by
capturing the chordae, as described in more detail below. While such an
approach may be effective for some purposes, the difficulty in capturing the
valve
leaflets initially may still be present.
While the methods described herein are particularly desirable since they
permit interventions to occur without stopping the heart, they may also be
used
with patients undergoing cardiopulmonary bypass. Such cardiopulmonary
bypass can be achieved by any presently available technique, including both
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conventional systems and recently developed endovascular bypass systems,
such as those available from Heartport, Inc., Redwood City, California.
During the procedures performed while the heart is beating, it will often be
desirable to stabilize the interventional tool against one or more cardiac
structures prior to grasping the leaflets with the interventional tool. Such
stabilization will lessen the relative motion between the tool and the
structure.
Stabilization mechanisms may be separate from or integral with any part of the
system or device, including but not limited to guidewires, guiding catheters
and
interventional tools. Likewise, the stabilization mechanisms may provide one
or
more additional functions in the tissue modification procedure, such as
steering,
orientation assessment, grasping, coaptation, adjustment and fixation.
Therefore, many components in the system may have dual purposes.
Coaptation may be performed by a number of methods, such as capturing
the leaflets or by releasably capturing the chordae attached to each leaflet.
An
exemplary capture device will comprise a snare, or a pair of snares, which are
advanced through the chordae to capture or entangle individual chordae. This
snare or snares may then be tightened to draw the chordae partially together
and
limit valve motion, at least partially. After such coaptation is achieved, the
valve
leaflets, chordae, papillary muscles, or annulus may then be engaged and
modified, e.g., the leaflets may be attached, using a separate interventional
tool,
as described above and elsewhere herein. Alternatively, it will be possible to
form a permanent link, bridge, or capture of the chordae if the temporary
coaptation appears sufficient to repair valve function. In some instances, it
may
be sufficient to simply detach the snare or other capture mechanism and leave
it
in place permanently. In other instances, it will be possible to exchange the
snare for a more permanent attachment structure, such as a suture loop or
metallic coil. For example, once the snare is in place, if the valve function
is
acceptably repaired, the snare may be drawn out from the chordae through the
placement catheter, where the snare pulls a length of suture in the manner of
a
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needle passing through tissue. The suture can then be tied or otherwise
fastened to form a permanent capture loop for the chordae. Alternatively, a
separate attachment structure, such as a metal coil, barb, malecot, or the
like,
may be advanced around the snared chordae to effect permanent capture, where
a structure will be detached and left in place.
The methods described above may be performed using either antegrade
or retrograde endovascular access through the vasculature. The following
description will describe both antegrade and retrograde access approaches for
gaining access to the mitral valve. Mitral valve access is generally more
difficult
than tricuspid valve access. In a retrograde approach, the interventional
tool,
optional guiding catheter, and any other supporting devices, will be
introduced
through distal arterial vasculature and over the aortic arch and into the left
ventricle through the aortic valve. Typically, the aortic arch or via a
brachial
approach will be approached through a conventional femoral artery access
route,
but could also be approached through the brachial artery, axillary artery, or
a
carotid artery. When entering the left ventricle, the interventional tool will
generally be directed downwardly and away from the mitral valve structure.
Thus, the interventional tool will usually be curved or turned so that it
approaches
the mitral valve from below, usually through the chordae toward the valve
annulus. For example, the interventional tool can enter the left ventricle
through
the aortic valve and then be deflected or otherwise steered to turn 900 to
directly
approach the mitral valve and chordae. Steering of the tool can be
accomplished
by deflecting a supporting catheter using pull wires, pre-formed curved
catheters,
or the like. In some instances, the papillary muscles could be more directly
accessed since they generally lie below the aortic valve and inline with the
tool
as it enters the left ventricle.
Often, it will be desirable to position the interventional tool toward the
target tissue structure using a preformed and/or steerable guide catheter. In
a
retrograde approach, the guide catheter may be placed from an access point,
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e.g., the femoral artery at the patient's groin, so that it passes over the
aortic
arch, through the aortic valve, and into the left ventricle where it will form
an
access path to the target tissue structure. When the tissue structure is the
chordae or valve leaflets, the guide catheter will usually have to be curved
or be
everted or turned backward so that it can turn the interventional tool around.
Additionally, it may be desirable to provide for stabilization of the distal
end of the
guide catheter. Stabilization may be provided by extendible elements, wires,
cages, balloons, or other structures which engage the valve annulus, chordae
or
ventricular wall portions. Alternatively, two or more stabilizing extensions
may be
provided to project forwardly from the guide catheter and seat in the valve
commissures to position and hold the guide catheter in place. Such extendible
elements may also be used to stabilize guidewires, interventional tools and
other
types of catheter systems. Specific stabilization structures will be described
in
more detail below.
Access for an antegrade endovascular approach will be through the
inferior vena cava or superior vena cava into the right atrium. Such antegrade
access may, in itself, be sufficient to perform procedures on the tricuspid
valve
from the top of the valve. Such procedures, however, will not be described in
detail herein. To access the mitral valve, it will be necessary to pass from
the
right atrium into the left atrium, typically by passing the tool through the
interatrial
septum. The interatrial septum may be endovascularly penetrated by
conventional techniques, typically using a Brockenbrough needle, as described
in
the vaivuloplasty literature. Once the interatrial septum has been penetrated,
the
interventional tool may be passed into the left atrium so that it approaches
the
mitral valve from the top. Such an approach will require that the access path
turn
downward, typically through an angle in the range from 0 to 120 .
The superior vena cava may be accessed through a variety of
conventional peripheral access sites, such as the internal jugular vein, while
the
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inferior vena cava may be accessed through the femoral vein. Such access may
be performed percutaneously or by surgical cut down techniques.
As with the retrograde arterial approach, the antegrade venous approach
may utilize placement of a guide catheter. With the use of a guidewire, the
guide
catheter will be configured to pass from the initial access location, through
either
the superior vena cava or inferior vena cava into the right atrium. The guide
catheter will then be adapted to pass through an interatrial penetration and
into
the left atrium, where it will be pre-shaped or deflected to approach the
mitral
valve from the top. The guidewire, guide catheter and/or the interventional
catheter which carries the interventional tool may be steerable and may
optionally have stabilizing elements. For example, in this specific
embodiment,
the guide catheter may have two or more laterally extensible steering wires
and/or a plurality of stabilizing arms which project forwardly and seat around
the
valve annulus or commissures to hold the guide catheter in place. The
interventional tool may then be deployed through the guide catheter to perform
the desired valve repair technique.
Systems described herein comprise a guide catheter configured to pass
from the remote vasculature of a patient to a position within the heart
adjacent to
a target atrioventricular or other cardiac valve. The systems further comprise
an
interventional catheter configured to pass through the guide catheter and to
engage the atrioventricular or other cardiac valve and/or associated cardiac
structures and an interventional tool on the interventional catheter adapted
to
modify the atrioventricular or other cardiac valve leaflets, valve annulus,
valve
chordae or papillary muscles to reduce regurgitation. In particular, the guide
catheter can be configured for either an antegrade or retrograde approach to
the
mitral valve, as described above. The guide catheter may further comprise a
stabilizing element for engaging tissue within the heart to reduce relative
movement between the guide catheter and the tissue while the heart remains
:)eating. The structure can be any of the cages, wires, or the like, which
have
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previously been described in connection with the method. Additionally, the
interventional catheter may also comprise a stabilizing element for engaging a
tissue structure within the heart to reduce relative motion between the
interventional catheter and the tissue. The stabilizing element can also be an
expansible cage, steering wires, or the like and may include vacuum and/or
surface finishes to enhancing coupling. Specific interventional tools include
suturing devices, stapling devices, clip-applying devices, radiofrequency
electrodes, surgical adhesive applicators, annuloplasty rings, and the like.
Both the interventional tool and the guide catheter may employ stabilizing
mechanisms intended to engage a tissue structure within the heart to reduce
relative movement between the interventional tool and/or guide catheter
relative
to the heart, and in particular relative to the atrioventricular valve. The
stabilization mechanisms in both cases may be the same. Typically, the
stabilization mechanisms will be adapted to engage at least one tissue
structure
selected from the group consisting of the interatrial septum, the atrial wall,
the
valve annulus, the valve commissures, the valve chordae, and the papillary
muscles. For example, the stabilizing mechanism may comprise one or more
extensible wires which are deployable radially outwardly to engage the tissue
structure, such as the valve commissures. Alternatively, the stabilizing
mechanism could comprise an expansible cage that can be deployed to occupy
all or at least a major portion of the atrium above the atrioventricular
valve. As a
still further alternative, the stabilizing mechanism could be a pair of
inflatable
Dalloons which are spaced-apart and adapted to engage the interatrial septum
nrhen the interventional tool and/or guide catheter are passed therethrough.
In further specific aspects, the interventional tool may comprise a valve
eaflet capture device intended for temporarily holding the valve leaflets
prior to
-nodification, e.g., affixation. For example, the valve leaflet capture device
may
;omprise a pair of extensible elements which may be advanced from a distal end
)f the interventional tool to engage and capture the two mitral valve leaflets
or
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three aortic valve leaflets. The particular capture tools may grasp the
leaflets by
pinching, partially or fully penetrating or piercing, and/or suctioning the
leaflets.
The tools may comprise jawed devices, looped devices, coiled devices or
pronged devices, or vacuum devices to grasp and hold the leaflets.
The present disclosure further provides methods for grasping an
atrioventricular or other cardiac valve, particularly the mitral valve, to
facilitate
subsequent intervention or for other purposes. The grasping method comprises
capturing chordae attached to at least one leaflet of the valve while the
heart is
beating. Capture of the chordae from beneath the valve can modify leaflet
movement and improve valve function, optionally closing portions of opposed
valve leaflets against each other. Usually, chordae attached to valve leaflets
(or
possibly three valve leaflets in the case of tricuspid valves) are captured
simultaneously. For example, one or more snares, such as helical coils, can be
advanced into the chordae to capture and immobilize portions thereof.
Alternatively, a loop element can be advanced through the valve chordae and
tightened in order to modify valve function. In some instances, capture of the
chordae can be made permanent and will be sufficient to treat the underlying
regurgitation. In other cases, capture of the chordae will be primarily for
leaflet
coaptation, and the leaflets will be affixed by a subsequent interventional
step.
Preferably, the subsequent interventional step is performed while the chordae
remain captured. The chordae can then be released after the leaflets or other
tissue structures have been modified.
The present disclosure still further provides a chordae capture catheter
comprising a catheter body having a proximal end and a distal end. Means are
provided at or near the distal end of the catheter body for capturing the
chordae.
A first exemplary means comprises one or more coils which are extensible from
the distal end of the catheter and which engage and entangle the chordae when
they are advanced therein. A second exemplary capture means comprises a
loop element which is extensible from the distal end of the catheter and which
is
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pre-formed to pass through the chordae on one or both, preferably both valve
leaflets in order to draw the chordae together and modify valve function.
A further method according to the present disclosure for grasping an
atrioventricular or other cardiac valve leaflets comprises capturing two valve
leaflets separately and preferably sequentially. Such capture is effected by a
leaflet capture catheter having at least three grasping jaws or prongs. A
first
valve leaflet is captured between a first pair of prongs, and second valve
leaflet is
captured between a second pair of prongs. Optionally, the two prong pairs can
have a common center prong, typically where the center prong is fixed
(immobile) and the two outer prongs pivot in order to provide a pair of
adjacent
jaw-type graspers. By separately and sequentially grasping the two leaflets,
the
leaflets can be held in a preferred apposition and the improvement in valve
function observed. Alternatively, the leaflets may be grasped simultaneously.
If
the improvement is adequate, the valves can be permanently affixed in a
separate step. Optionally, the leaflet capture catheter can include a device
for
fixing the valves, e.g., it can carry a clip which can be applied on to the
valves as
the capture catheter is withdrawn.
The present disclosure still further provides leaflet capture catheters suited
for performing the method just described. The catheters comprise a catheter
body having a proximal end and a distal end. A leaflet grasper is provided at
or
near the distal end of the catheter body and includes at least three prongs
wherein at least two of the three prongs are pivotable so that they may be
separately actuated to separately capture individual leaflets or
simultaneously
actuated to capture the leaflets together. Optionally, the catheters further
comprise means for affixing the valve leaflets after they have been captured,
preferably comprising a clip-applier.
The present disclosure further includes leaflet capture catheters and tools
which utilize a vacuum for grasping the valve leaflets and manipulating the
post
leaflets into a desired apposition. Usually, the catheter will have at least
two
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vacuum channels at a distal end where the channels are preferably separately
positionable and independently actuable. In that way, at least two valve
leaflets
can be separately captured and positioned while the base catheter remains
stationary. The catheter may be positioned in an antegrade or retrograde
manner with the tool entering between the valve leaflets and optionally
between
the chordae. The tool and/or catheter may optionally further include
modification
devices, such as suture appliers, clip appliers, staplers, rivet appliers,
adhesive
applicators, heating elements for shortening the chordae, and others of the
specific interventional tools described hereinafter. Likewise, the present
disclosure further includes catheters and tools which include lumens for
monitoring pressures within the chambers of the heart, and/or infusion of
radiopaque contrast solution.
The present disclosure further includes a method of modifying a heart
valve of a patient. The method comprises advancing a catheter through the
patient's vasculature into the heart from a vascular access point remote from
the
heart. The catheter has at least one structure releasably coupled thereto. The
method further comprises deploying the structure from the catheter into a
gutter
on a ventricular side of annulus of the heart valve, the structure adapted to
modify the annulus so as to reduce regurgitation in the heart valve; and, in
combination with deploying the structure, holding leaflets of the heart valve
together so as to reduce regurgitation in the heart valve.
The present disclosure further includes a method of modifying a heart
valve of a patient. The method comprises advancing a catheter through the
patient's vasculature into the heart from a vascular access point remote from
the
hear. The catheter has an annuloplasty device releasably coupled thereto. The
method further comprises performing an intervention on a gutter on a
ventricular
side of the heart valve to modify an annulus of the heart valve and reduce
regurgitation in the heart valve; and in combination with performing an
intervention, modifying a spatial relationship between a first valve leaflet
and a
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second valve leaflet of the heart valve so as to reduce regurgitation in the
heart
valve.
The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features and
advantages will be apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic illustration of the left ventricle of a heart showing
blood flow during systole with arrows.
Fig. 2 is a schematic illustration of the left ventricle of a heart having
prolapsed leaflets in the mitral valve.
Fig. 3 is a schematic illustration of a heart in a patient suffering from
cardiomyopathy where the heart is dilated and the leaflets do not meet.
Fig. 3A shows normal closure of the leaflets, while Fig. 3B shows
abnormal closure in the dilated heart.
Fig. 4 illustrates mitral valve regurgitation in the left ventricle of a heart
having impaired papillary muscles.
Fig. 5 is a schematic illustration showing direct attachment of opposed
valve leaflets to reduce valve regurgitation.
Fig. 6 is a schematic illustration showing attachment of valve chordae to
treat valve regurgitation.
Figs. 7-8 show exemplary antegrade approaches to the mitral valve from
the venous vasculature.
Figs. 9-10 show exemplary retrograde approaches to the mitral valve
through the aortic valve and arterial vasculature.
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Figs. 11-14 illustrate the use of adjustment wires for steering capability.
Figs. 15A-15D illustrate the use of pre-shaped mandrels to steer a
component or structure.
Figs. 16-20, 21A-21C, and 22A-22B depict various orientation assessment
tools.
Fig. 23 is a schematic illustration of an interatrial septum stabilization
device.
Fig. 24 is a schematic illustration of a catheter shaft designed to provide
stabilization against a structure, such as the interatrial septum, or for
flexible
adjustment and locking stability in various positions.
Fig. 25 is a schematic illustration of an atrial stabilization device.
Figs. 26-29 illustrate stabilization mechanisms which utilize coupling to the
valve annulus.
Figs. 30, and 31A-31 D illustrate stabilization mechanisms which utilize
coupling with the valve commissures and/or leaflets.
Figs. 32A and 32B illustrate mitral valve stabilization using snares for
capturing the valve chordae.
Figs. 33A and 33B illustrate an antegrade approach for snaring valve
chordae and optionally suturing the chordae together to treat valve
regurgitation.
Fig. 34 illustrates an antegrade approach for snaring valve chordae to
stabilize the mitral valve.
Figs. 35 and 35A illustrate a snaring catheter particularly intended for
capturing valve chordae from a retrograde approach.
Figs. 36A and 36B illustrate use of the catheter Fig. 35 for snaring valve
chordae.
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Figs. 37 and 38 illustrate a catheter similar to that shown in Figs. 35 and
35A, except that it includes a working channel for introducing interventional
catheters and tools to treat the mitral or other atrioventricular valve.
Figs. 39A and 39B illustrate a coil which can be implanted within the valve
chordae to stabilize the mitral valve.
Fig. 40 illustrates placement of the coil of Figs. 39A and 39B from a
retrograde approach.
Figs. 41A -41 B, 42A-42B and 43 illustrate valve leaflet grasping devices
which utilizes a pinching method.
Figs 44A-44D are schematic illustrations of an atrial-ventricular valve
leaflet grasping device which utilizes a pinching method.
Figs 45A-45B are schematic illustrations of a grasping device which
utilizes rollers in a pinching method.
Figs. 46A-46B are schematic illustrations of a grasping device which
utilizes a pair of opposing coils in a pinching method.
Figs. 47A-D illustrate a pronged valve leaflet device which utilizes a
pinching, partially penetrating or piercing method.
Fig. 48 illustrates a vacuum-assisted stabilization catheter for use in the
methods described herein.
Fig. 49 illustrates an embodiment of a valve suturing device.
Figs. 49A-49C illustrate an additional embodiment of a valve suturing
device.
Fig. 50 illustrates a further embodiment of a valve suturing device.
Fig. 51 illustrates use of the catheter for capturing and suturing opposed
mitral valve leaflets.
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Fig. 52 illustrates the mitral valve leaflets which have been secured as
shown in Fig. 51.
Figs. 53 and 54 illustrate an alternative anchor which can be used with the
suturing devices.
Figs. 55A-55B illustrate the use of an expansible anchor in fixation.
Figs. 56 and 57 illustrate yet another suturing device.
Fig. 58 illustrates use of the suturing device of Figs. 56 and 57 to place
sutures between valve leaflets of the mitral valve.
Fig. 59 illustrates yet another embodiment of a suturing device.
Fig. 60 illustrates use of the device of Fig. 59 and suturing opposed mitral
valve leaflets.
Figs. 61A and 61 B illustrate a stapling device which can be used to staple
opposed leaflets of an atrioventricular valve.
Figs. 62A-D are schematic illustrations of fixation devices.
Fig. 63 illustrates an alternative two part fixation stapling device.
Fig. 64 illustrates use of the stapling device of Fig. 63 for stapling opposed
valve leaflets of a mitral valve.
Fig. 65A-65C are schematic illustrations of coiled fixation devices.
Fig. 66 illustrates use of a self-securing anchor for attaching opposed
surfaces on the leaflets of the mitral valve.
Figs. 66A-66B are schematic illustrations of penetrating fixation devices.
Figs. 67 and 68 are schematic illustrations of penetrating fixation devices
with barb-like distal ends.
Figs. 69A-C and 70A-B are schematic illustrations of clips used as fixation
devices.
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Figs. 71, and 72A-72B are schematic illustrations of clips involving the use
of graspers in the fixation mechanism.
Figs. 73A-73C illustrate a three-jaw clip-applier.
Fig. 74 illustrates a clip which has been applied by the clip-applier of
Figs. 73A-73C.
Fig. 75 illustrates a device for applying radiofrequency energy to shorten
valve chordae.
Figs. 76, and 77A-77B illustrates devices used to plicate and shorten
valve chordae.
Fig. 78 illustrates a first exemplary approach for placing an annuloplasty
ring.
Figs. 79 and 80 illustrate a second exemplary approach for placing an
annuloplasty ring.
Fig. 81 illustrates a method for placing an anchored filament about a mitral
valve annulus that can be used to tighten the annulus.
Fig. 82 illustrates a method for placing multiple sutures about a mitral
valve annulus, where the individual suture plicate and tighten the annulus.
Figs. 83-85 illustrate an embodiment of an atrial device for valve tissue
modification.
Figs. 86, and 87A-87C illustrate an embodiment of an atrial-ventricular
device for valve tissue modification.
Figs. 88-89, and Figs. 90A-90B illustrate an embodiment of a ventricular
device for valve tissue modification.
Fig. 91 shows a cutaway representation of the left ventricle.
Figs.92A and 92B shows an annuloplasty device for positioning in a gutter
of the left ventricle.
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Fig. 93 shows a cutaway representation of the left ventricle with the
annuloplasty device positioned in the gutter.
Fig. 94 is a cross-sectional view of the heart showing the mitral valve,
valve leaflets, annulus, and coronary sinus.
DETAILED DESCRIPTION
1. CARDIAC PHYSIOLOGY
The left ventricle LV of a normal heart H in systole is illustrated in Fig. 1.
The left ventricle LV is contracting and blood flows outwardly through the
tricuspid (aortic) valve AV in the direction of the arrows. Back flow of blood
or
"regurgitation" through the mitral valve MV is prevented since the mitral
valve is
configured as a "check valve" which prevents back flow when pressure in the
left
ventricle is higher than that in the left atrium LA. The mitral valve MV
comprises
a pair of leaflets having free edges FE which meet evenly to close, as
illustrated
in Fig. 1. The opposite ends of the leaflets LF are attached to the
surrounding
heart structure along an annular region referred to as the annulus AN. The
free
edges FE of the leaflets LF are secured to the lower portions of the left
ventricle
LV through chordae tendineae CT (referred to hereinafter as the chordae) which
include plurality of branching tendons secured over the lower surfaces of each
of
the valve leaflets LF. The chordae CT in turn, are attached to the papillary
muscles PM which extend upwardly from the lower portions of the left ventricle
and interventricular septum IVS.
Referring now to Figs. 2-4, a number of structural defects in the heart can
cause mitral valve regurgitation. Ruptured chordae RCT, as shown in Fig. 2,
can
cause a valve leaflet LF2 to prolapse since inadequate tension is transmitted
to
the leaflet via the chordae. While the other leaflet LFI maintains a normal
profile,
the two valve leaflets do not properly meet and leakage from the left
ventricle LV
into the left atrium LA will occur, as shown by the arrow.
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Regurgitation also occurs in the patients suffering from cardiomyopathy
where the heart is dilated and the increased size prevents the valve leaflets
LF
from meeting properly, as shown in Fig. 3. The enlargement of the heart causes
the mitral annulus to become enlarged, making it impossible for the free edges
FE to meet during systole. The free edges of the anterior and posterior
leaflets
normally meet along a line of coaptation C as shown in Fig. 3A, but a
significant
gap G can be left in patients suffering from cardiomyopathy, as shown in Fig.
3B.
Mitral valve regurgitation can also occur in patients who have suffered
ischemic heart disease where the functioning of the papillary muscles PM is
impaired, as illustrated in Fig. 4. As the left ventricle LV contracts during
systole,
the papillary muscles PM do not contract sufficiently to effect proper
closure.
The leaflets LF1 and LF2 then prolapse, as illustrated. Leakage again occurs
from the left ventricle LV to the left atrium LA, as shown by the arrow.
II. INTERVENTIONAL APPROACHES
The described methods and devices treat cardiac valve regurgitation,
particularly mitral valve regurgitation, by intervention at various locations.
First,
as shown in Fig. 5, the valve leaflets LF may be directly attached or coupled
to
each other by a structure S or other means. Typical structures include suture,
staples, clips, pins, or other closure devices of a type commonly used in
attaching opposed tissue surfaces. Alternatively, the opposed surfaces on the
valve leaflets could be attached using adhesives, fusion energy, including
radiofrequency current, laser energy, microwave, ultrasonic energy, or the
like. A
variety of specific techniques for valve leaflet attachment will be described
hereinafter.
A second and often preferred interventional point will be in the chordae, as
shown in Fig. 6. There, an attachment structure S is shown to couple
individual
chordae or tendons which are attached to each of the two leaflets LF. A
variety
of specific structures can be utilized, such as snares, staples, sutures,
coils,
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clips, snaps, rivets, adhesives, and the like. Opposed chordae will usually
also
be attached directly, optionally employing any of the same structures listed
above. Alternatively, opposed chordae may be indirectly tied or coupled
together
by a structure which links or couples their movement, but which does not
physically attach chordae from each of the valve leaflets directly together.
In
addition to attaching the chordae, chordal intervention can include shortening
the
chordae, e.g., by applying energy to shrink the collagen therein, or may
utilize
mechanical plication devices, such as clips, to physically shorten the
chordae.
A third interventional point is the annulus AN (shown in FIG. 1) of the
mitral valve AV. An annuloplasty device, such as a ring or a partial ring, can
be
positioned on the annulus to strengthen or re-shape the annulus. The atrial
side
of the annulus has a smooth, sloping surface around the circumference of the
mitral valve. However, it can be difficult to secure an annuloplasty device to
the
smooth surface of the atrial side of the annulus. The ventricular side of the
annulus has a concave, annular "gutter" around the valve. The gutter provides
a
location in which an annuloplasty device can be located and held while it is
fastened to tissue. Thus, percutaneous annuloplasty could be more readily
attainable by delivering an annuloplasty ring to the ventricular side rather
than
the atrial side of the valve, as described more fully below.
Ill. ACCESS TO THE MITRAL VALVE
Access to the mitral valve or other atrioventricular valve will preferably be
accomplished through the patient's vasculature in a "percutaneous" manner. By
"percutaneous" it is meant that a location of the vasculature remote from the
heart is accessed through the skin, typically using a surgical cut down
procedure
or a minimally invasive procedure, such as using needle access through, for
example, the Seldinger technique. The ability to percutaneously access the
remote vasculature is well-known and described in the patent and medical
literature. Depending on the point of vascular access, the approach to the
mitral
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valve may be "antegrade" and require entry into the left atrium by crossing
the
interatrial septum. Alternatively, approach to the mitral valve can be
"retrograde"
where the left ventricle is entered through the aortic valve. Once
percutaneous
access is achieved, the interventional tools and supporting catheter(s) will
be
advanced to the heart intravascularly where they may be positioned adjacent
the
target cardiac valve in a variety of manners, as described elsewhere herein.
While the methods will preferably be percutaneous and intravascular, many of
the tools described herein will, of course, also be useful for performing open
surgical techniques where the heart is stopped and the heart valve accessed
through the myocardial tissue. Many of the tools will also find use in
minimally
invasive procedures where access is achieved thorascopically and where the
heart will usually be stopped but in some instances could remain beating.
A typical antegrade approach to the mitral valve is depicted in Figs. 7
and 8. The mitral valve MV may be accessed by an approach from the inferior
vena cava IVC or superior vena cava SVC, through the right atrium RA, across
the interatrial septum IAS and into the left atrium LA above the mitral valve
MV.
As shown in Fig. 7, a catheter 10 having a needle 12 may be advanced from the
inferior vena cava IVC into the right atrium RA. Once the catheter 10 reaches
the anterior side of the interatrial septum IAS, the needle 12 may be advanced
so
that it penetrates through the septum at the fossa ovalis FO or the foramen
ovale
into the left atrium LA. At this point, a guidewire may be exchanged for the
needle 12 and the catheter 10 withdrawn.
As shown in Fig. 8, access through the interatrial septum IAS will usually
be maintained by the piacement of a guide catheter 14, typically over a
guidewire
16 which has been placed as described above. The guide catheter 14 affords
subsequent access to permit introduction of the interventional tool(s) which
will
be used for performing the valve or tissue modification, as described in more
detail below.
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The antegrade approach to the mitral valve, as just described, is
advantageous in a number of respects. For example, the use of the antegrade
approach will usually allow for more precise and effective centering and
stabilization of the guide catheter and/or interventional tool. Precise
positioning,
of course, facilitates accuracy in the tissue modification, particularly
affixation of
the valve leaflets or chordae. The antegrade approach also reduces the risk of
damaging the subvalvular apparatus during catheter and interventional tool
introduction and manipulation. Additionally, the antegrade approach eliminates
the risks associated with crossing the aortic valve. This is particularly
relevant to
patients with prosthetic aortic valves which cannot be crossed. When employing
chordal fixation, the tools can be placed very close to the free edge of the
leaflet
since they will be removed in a direction away from the chordae which are
being
fixed. Additionally, an antegrade approach allows more direct access to the
valve leaflets unimpeded by presence of the chordae.
A typical retrograde approach to the mitral valve is depicted in Fig. 9.
Here the mitral valve MV may be accessed by an approach from the aortic arch
AA, across the aortic valve AV, and into the left ventricle below the mitral
valve
MV. The aortic arch AA may be accessed through a conventional femoral artery
access route, as well as through more direct approaches via the brachial
artery,
axillary artery, or a radial or carotid artery. Such access may be achieved
with
the use of a guidewire 42. Once in place, a guide catheter 40 may be tracked
over the guidewire 42. The guide catheter 40 affords subsequent access to
permit introduction of the interventional tool(s) which will be used for
performing
the valve or tissue modification, as described in more detail below.
In some instances, a retrograde arterial approach to the mitral valve will
be preferred due to its advantages. Use of the retrograde approach will
eliminate
the need for a trans-septal puncture. The retrograde approach is also more
commonly used by cardiologists and thus has the advantage of familiarity.
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Additionally, the retrograde approach provides more direct access to the
chordae.
The interventional tool(s) used for performing the valve or tissue
modifications may be specifically designed for the approach or they may be
interchangeable. For example, tools may be specifically designed for an
antegrade or retrograde approach, or they may be designed to be used with
either approach. In any case, tools may be used in any appropriate fashion to
achieve a desired result. However, for the sake of clarity, a nomenclature has
been developed to describe the common usage of such tools. Tools which
perform the modification procedure while primarily residing primarily in the
atrium
are referred to as "atrial" tools. These utilize an antegrade approach. Tools
which perform the modification procedure while primarily residing in the
ventricle
are referred to as "ventricular" tools, and likewise utilize a retrograde
approach.
Tools which cross over the valve to perform the modification procedure,
residing
in both the atrium and the ventricle, are referred to as "atrial-ventricular"
tools,
and may utilize either an antegrade or retrograde approach.
IV. ORIENTATION STEERING
Approaching the desired valve or tissue structure for effective treatment,
as described above, requires proper orientation of the catheters, tools and
devices used throughout the procedure. Such orientation may be accomplished
by gross steering of the device to the desired location and then refined
steering
of the device components to achieve a desired result.
Gross steering may be accomplished by a number of methods. First, a
steerable guidewire may be used to introduce a guide catheter, interventional
tool and/or treatment device into the proper position. The guide catheter may
be
introduced, for example, using a surgical cut down or Seldinger access to the
femoral artery in the patient's groin. After placing a guidewire, the guide
catheter
may be introduced over the guidewire to the desired position. Alternatively, a
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shorter and differently shaped guide catheter could be introduced through the
other routes described above.
Second, a guide catheter may be pre-shaped to provide a desired
orientation relative to the mitral valve. For example, as shown in Figs. 9 and
10,
guide catheter 40 may have a pre-shaped J-tip which is configured so that it
turns toward the mitral valve MV after it is placed over the aortic arch AA
and
through the aortic valve AV. As shown in Fig. 9, the guide catheter 40 may be
configured to extend down into the left ventricle LV and to evert so that the
orientation of an interventional tool or catheter is more closely aligned with
the
axis of the mitral valve MV. The guide catheter 40 of Fig. 10 orients an
interventional catheter (not shown) in a lateral direction relative to the
access of
the mitral valve MV. Each of the guide catheters 40 shown in Figs. 9 and 10
may
find use under different circumstances. For example, the guide catheter 40 of
Fig. 10 might be particularly suited for introducing tools which modify the
chordae
CT, while the catheter 40 of Fig. 9 may be more useful for engaging tools
against
the valve leaflets. As shown in Fig. 9, a guidewire 42 may be positioned from
the
tip of the guide catheter 40 directly through the opening of the mitral valve
MV.
Interventional tools can then be directed over the guidewire 42 to form the
particular procedures described hereinafter. Likewise, the interventional tool
itself may be pre-shaped to provide a desired orientation.
Third, the guidewire, guide catheter or interventional tool may be actively
deflected, e.g., having push/pull wires which permit selective deflection of
the
distal end in 1, 2, 3, or 4 directions depending on the number of pull wires,
having
shape memory nitinol, or having balloons, wires, wire cages or similar mesh
structures to direct the device away from a cardiac structure and therefore
into a
desired position, to name a few.
Either of the guide catheters 40 shown in Figs. 9 or 10 may be provided
with steering capabilities. For example, two or more adjustment wires 46 may
be
provided at the distal tip of the guide catheter 40 as shown in Fig. 11. These
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adjustment wires may be active or passive, and may be positioned within the
valve commissures to enhance alignment of the guide catheter with the mitral
valve MV. As shown in Figs. 12A and 12B, the adjustment wires 46 may be
positioned in the medial commissure MVC and lateral commissure LVC, and the
guide catheter 40 may thus be moved from a central location, as shown in
Fig. 12A to a more medial position, as shown in Fig. 12B. The catheter could
of
course also be moved in the lateral direction (not shown). The ability to
position
the guide catheter will be of great benefit in performing the specific
interventions
and valve modifications described hereinafter. It will be appreciated that
similar
steering mechanisms could be provided on an interventional catheter introduced
through the guide catheter, and in some instances it may be most desirable to
provide the guidewire, the guide catheter, and the interventional catheter
with
steering and positioning capabilities.
Steering wires 50 on a guide catheter 40 may also be provided to engage
opposed surfaces within the left ventricle LV, as shown in Fig. 13. By
providing
such a steering capability, the distal tip of the guide catheter 40 can be
moved
further downward from the mitral valve. Catheter 40 of Fig. 13 would be
particularly useful in combination with an interventional catheter which
itself has
steering capabilities which engage portions of the mitral valve, such as the
valve
commissures as described above.
As shown in Fig. 14, the guidewire 52 may have laterally deflectable
steering elements 54 which may be positioned in, for example, the valve
commissures as described previously. This way, the guidewire 52 may be
positioned toward the medial or lateral sides of the mitral valve MV, and an
interventional catheter 56 introduced over the guidewire to a desired target
structure within or surrounding the mitral valve MV. Providing such a
steerable
and positionable guidewire, it is particularly advantageous when it is desired
to
position the tip of an interventional catheter 56 at a region well below the
opening
of the mitral valve. That is, neither the guide catheter nor the
interventional
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catheter have to be advanced fully to the opening of the mitral valve, leaving
them free to be positioned elsewhere.
In some instances, it will be desirable to introduce interventional tools
sequentially or simultaneously from both the antegrade and retrograde
directions.
While it will be possible to separately introduce guiding catheters and
guidewires
by the approaches described above, in at least some instances it may be
preferable to pass a single guidewire between the vena cava and the right
atrium, crossing the interatrial septum as previously described. The guidewire
may then pass in an antegrade direction through the aortic valve, through the
ascending and descending aorta, and then percutaneously out of the vasculature
at a location remote from the heart, such as the femoral artery.
Location of a single guidewire in this manner provides a continuous "rail"
through the heart, allowing placement of separate devices in both an antegrade
and retrograde direction. Additionally, any interaction or cooperation between
the devices is facilitated since they will necessarily advance toward one
another
in an alignment which is controlled and assured bythe guidewire, e.g., when
fully
advanced any two devices will necessarily meet. Thus, one device would extend
inward from the venous side of the heart in an anterior antegrade direction to
the
mitral valve, and a second device would enter through the arterial side of the
heart in a retrograde direction. The two devices would then be precisely
located
relative to each other as they approach and optionally meet at or near the
mitral
valve. In a particular example, a stabilizing catheter could be introduced in
a
retrograde direction to approach the chordae and underside of the mitral valve
leaflets to provide for temporary stabilization and/or leaflet coaptation, as
generally described above. A catheter carrying a fixation device could then be
advanced in an antegrade direction to approach the valve leaflets from above.
The second device could then be separately actuated to affix the valve
leaflets
once the proper temporary stabilization has been achieved with the first
device.
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Fourth, the guidewire, guide catheter or interventional tool may be
positioned with the use of a floating balloon. This may be most useful for use
with an antegrade approach. The distal balloon of a balloon tipped guidewire
or
balloon tipped floppy catheter may be inflated and floated antegrade through
the
mitral valve. If the heart is slowly beating, blood will be flowing from the
left
atrium, through the mitral valve to the left ventricle. A floating balloon may
be
carried along this flow trajectory, carrying the guidewire or catheter with
it. The
balloon may then be deflated and newly placed guidewire or catheter may be
utilized as desired.
Fifth, a hollow guidewire, guide catheter or interventional or other tool may
be positioned with the use of a rigid, pre-shaped mandrel or insertable
member.
As shown in Figs. 15A-D, the mandrel 600 may be comprised of wire, metal,
plastic or any suitable material that may be formed to hold a desired shape
601,
such as a bend or bump. The mandrel 600 may then be inserted into a lumen in
a flexible structure 602 to be positioned. Such a structure may be a hollow
guidewire, guide catheter, interventional tool or any other tool or component
of a
structure. As the shape 601 is advanced, the flexible structure 602 conforms
to
the shape 601 as it is passed through. This may be utilized to position a
structure or component of a structure in a desired location for later steps in
the
procedure.
It may be appreciated that any of the devices, systems and methods used
for gross steering may be also be applied to refined steering of the device or
device components to achieve a desired result. In particular, it may be
desired to
independently or dependently manipulate components of the interventional tools
throughout the procedure. Such steering may allow urging of the components
relative to the leaflets, annulus, atrial wall or other specific cardiac
structures.
This may be achieved with any of the devices or methods described above.
V. ORIENTATION ASSESSMENT
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Proper orientation of the systems and devices is necessary for performing
the valve or tissue modification. Both the orientation of the devices and the
components of the devices, in relation to cardiac structures and to each
other,
are of concern. Cardiac structures to which orientation is desired may include
the atrial walls, interatrial septum, valve annulus, valve leaflets, valve
commissures, valve chordae, papillary muscles and ventricle walls, to name a
few. Assessment of the orientation of the components and devices may be
achieved by a number of mechanisms and methodologies.
First, orientation may be assessed by tactile feedback. Introduction and
manipulation of the devices and components may allow them to contact cardiac
structures or other devices. Such contact may guide the devices into proper
position and relevant orientation. For example, it may be possible to
tactilely
sense the force of the distal end of a guidewire, catheter or interventional
tool
against the leaflets, commissures, annulus, chordae, papillary muscles,
ventricular walls, and/or atrial walls, to name a few. The force may be
translated
along its length to its proximal end to provide feedback to the physician or
operator. Similarly, sensors may be used to achieve a similar result.
Additionally, the catheter or tool may have a lumen to allow for pressure
monitoring. This may provide feedback throughout the procedure which may
indicate the presence and level of mitral regurgitation.
Second, orientation may be assessed by visualization of the devices and
components themselves. The components or the overall system may be
modified for enhanced echogenic and/or fluoroscopic visibility. Echogenicity
of a
material in a blood medium is dependent on the difference in acoustic
impedance
(product of velocity of sound and density of the medium through which the
sound
wave is traveling) between the material and blood. Therefore, a thin polymer
coating on the components or the overall system may provide modulation of the
acoustic impedance at the interface of the component and blood, thereby
improving echovisibility. Likewise, microscopic air bubbles trapped on the
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surface or embedded within the coating may also improve echovisibility.
Similarly, fluoroscopic visibility may be improved with radiopaque coatings,
radiopaque marker bands, or the like. Additionally, a lumen within the
catheter or
tool may be provided to inject radiopaque contrast solution to improve
fluoroscopic visibility or surrounding tissues. In any case, such coatings,
markings and fluids may provide visualization of the devices and components
themselves or any structures or elements used throughout the treatment
procedure. Similarly, angioscopic vision may be used to access the orientation
throughout the procedure.
Third, one or more orientation elements may be used to assess orientation
of the components and/or systems in relation to cardiac structures,
specifically
the target valve. Thus, orientation elements may be any structure or feature
that
provides information as to the orientation of the component, device or system
described herein. The elements may be separate from or integral with any part
of the system or device. They may be removably or fixedly mounted on the
guidewire, guide catheter, interventional tool and/or other device. Likewise,
the
elements may be components or parts of components of the device which
provide one or more additional functions in the tissue modification procedure,
such as stabilization, grasping, coaptation, adjustment or fixation. Further
the
elements may be atrial, ventricular or atrial-ventricular devices such that
they
may or may not cross the valve in the orientation assessment process. In
addition, such elements may be used to steer and/or orient the components and
systems prior to or simultaneous with assessment.
Orientation elements may be in the form of propellers, wings, petals, arms,
loops, and the like. One or more of these elements may be present, typically
extending radially from a central shaft. When two elements are present, they
are
commonly placed 120 to 180 degrees apart around the central shaft; more than
two elements are typically arranged in a radial pattern around the central
shaft.
In the preferred embodiments, the orientation elements are typically placed
either
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perpendicular to the line of coaptation or following the line of coaptation.
This
may provide the most useful reference, however many other placement
orientations may be used.
Examples of orientation elements placed perpendicular to the line of
coaptation are depicted in Figs. 16 and 17. Fig. 16 is a short axis view of
the
mitral valve MV with an orientation element 612 shown having a pair of
orientation structures 613 arranged 180 degrees apart around a central shaft
614. The orientation element 612 is shown perpendicular to the line of
coaptation C. Such positioning of the element 612 may indicate that the device
is in its desired orientation, specific components are in a desired
orientation, or
devices or components may be oriented in relation to the positioned element
which may be more visible than other parts of the device.
Fig. 17 is a long axis view of the mitral valve MV. Here, a guidewire 615
with a pair of orientation propellers 616 is shown inserted through the mitral
valve
MV via a retrograde approach. Visualization of the propellers 616 may allow
repositioning of the guidewire 615 until the propellers are perpendicular to
the
line of coaptation C. At this point, a guide catheter, interventional or other
tool
may be tracked over the catheter in the desired orientation. Such tracking may
be facilitated with the use of a keyed, notched, oval or similar lumen for
guidance. Similarly, such orientation propellers 616 may be mounted on a guide
catheter with a keyed lumen for guided insertion of interventional tools.
Examples of orientation elements placed along the line of coaptation are
depicted in Figs. 18 and 19. Fig. 18 is a long axis view of an orientation
element
620 inserted into the valve opening along the line of coaptation C. An end
view
shown in Fig. 19 illustrates the penetration of the element 620 through the
valve
opening and the valve leaflets LF sealing against the element 620. In
addition,
portions of the orientation element 620 may contact the commissures CM at each
end of the valve opening for support and/or for reference. Using the position
of
the orientation element 620 as a reference, the location of a variety of
cardiac
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structures, particularly the valve leaflets LF, are known. In addition, if the
position of specific components of the device are known in relation to the
orientation elements 620, such relation may be used to infer the relation of
those
components to the cardiac structures. For example, if the orientation elements
are known to be perpendicular to the graspers, positioning of the orientation
elements in the manner described above would ensure that the graspers would
be aligned perpendicular to the line of coaptation C or in a desirable
location to
grasp the valve leaflets LF.
In this example, the orientation element 620 is shown as an inflatable
bladder coaxially attached to a distal central shaft 621. Such a bladder may
be
comprised of a compliant or noncompliant material, such as PET, PUR, Silicone,
Chronoprene, or the like. The bladder material itself may be echo or
fluorogenic,
or it may be filled with an echo or fluorogenic liquid or suitable medium,
such as
carbon dioxide or agitated saline. In its inflated state, it is preferred that
the
bladder is wide or thick enough to so that the endview of the bladder is
visible in
a short axis view of the mitral valve, as shown in Fig. 19, and that the
bladder is
long or high enough so that the anterior and posterior leaflets may seal
against
the bladder in systole.
In addition, as shown in Fig. 20, the bladder 625 may be supported by a
frame 626. The frame 626 may be comprised of any suitable material, such as
nitinol, stainless steel, plastic or any combination thereof, of any
consistent or
variable flexibility, and any cross-sectional shape, such as round wire,
hollow
tube or flat ribbon. This material may be echo or fluorogenic or treated for
such
effects. In addition, the shape of the frame 626 may be of any suitable
symmetrical or nonsymmetrical geometry, including but not limited to
triangular,
rectangular, circular, oblong, and single or multi-humped. A rectangular
geometry is depicted in Fig. 20. In addition, the frame 626 may be expandable
as shown in Figs. 21A-C. In the collapsed state, Fig. 21A, the bladder 625 and
enclosed frame 626 may be inserted through a lumen in a guide catheter or
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interventional tool. When appropriately positioned, the frame 626 may be
gradually expanded, Fig. 21 B, to a desired geometry, Fig. 21 C. It may be
appreciated that the orientation element may function without inflation of the
bladder 625 or with just the frame 625 and no bladder.
Fourth, orientation may be assessed by visualization of flow patterns
resulting from system or component position with respect to cardiac
structures.
As mentioned, the heart may be slowly beating throughout the tissue
modification
procedure. As the heart beats, blood may be flowing from the left atrium,
through
the mitral valve, to the left ventricle. Visualization of these flow patterns
using
Color Doppler Echocardiography may allow inferences as to how systems or
components are positioned. For example, as shown in Figs 22A, if a thin planar
structure 650 is inserted in the valve opening with its long axis
perpendicular to
the line of coaptation C, a higher level of regurgitation may result due to
blood
flow through the unsealed portions 651. If the structure 650 is inserted with
its
long axis along the line of coaptation C, as shown in Fig. 22B, a lower level
of
regurgitation may result due to more adequate sealing of the valve leaflets LF
against the structure 650. Thus, such a structure 650 or similarly designed
device may be used as an orientation element.
VI. STABILIZATION
Before a valve or tissue modification or intervention is performed, it will
usually be desirable to temporarily stabilize the interventional tool in
relation to
the a cardiac structure. By "stabilization" it is meant that the
interventional tool
will be somehow coupled to a cardiac structure so that any existing relative
motion between the tool and the structure is lessened. Cardiac structures
which
may be utilized for coupling include the atrial walls, interatrial septum,
valve
annulus, valve leaflets, valve commissures, valve chordae, papillary muscles
and
ventricle walls, to name a few. Such stabilization is performed in order to
facilitate a subsequent intervention. For example, an access catheter may be
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mechanically coupled to the valve or tissue surrounding the valve, such as the
annulus or the chordae, and the interventional tool deployed from the catheter
to
perform a desired intervention, such as suturing, stapling, snaring,
annuloplasty,
RF tissue modification, or the like. The stabilization will usually be
terminated
after the particular valve modification is completed, but in some instances
the
stabilization could be terminated and redeployed multiple times at various
points
throughout the procedure.
The stabilization mechanisms may be separate from or integral with any
part of the system or device. They may be removably or fixedly mounted on the
guidewire, guide catheter, interventional tool and/or other device. Likewise,
the
elements may be components or parts of components of the device which
provide one or more additional functions in the tissue modification procedure,
such as steering, orientation assessment, grasping, coaptation, adjustment or
fixation. Further the mechanisms may be atrial, ventricular or atrial-
ventricular
devices such that they may or may not cross the valve in the stabilization
process. In particular, such mechanisms may be used to steer and/or orient the
components and systems prior to or simultaneous with stabilization.
In the preferred embodiments, three general categories of stabilization
mechanisms may be formed for descriptive purposes: 1) stabilization against
the
atrial septum, atrial walls or ventricle walls, 2) stabilization against the
valve, and
3) stabilization against the chordae or papillary muscles. Stabilization
against the
atrial septum may be useful when approaching antegrade with atrial or atrial-
ventricular devices. As previously described, an antegrade approach involves
crossing from the right atrium RA to the left atrium LA by penetrating the
interatrial septum IAS. This may be accomplished with a needle bearing
catheter, which may then be exchanged for an introducer, guide catheter or
similar catheter. Interventional tools may be introduced through this catheter
for
tissue modification treatment. To prevent movement of the catheter in an axial
direction, a stabilization mechanism may be used to engage and lock the
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catheter to the interatrial septum. A preferred embodiment is shown in Fig.
23,
which depicts a catheter shaft 660 having a distal balloon 661 and a proximal
balloon 662 inflated on opposite sides of the interarterial septum IAS.
Inflation of
the balloons 661, 662 against the septum couples the shaft 660 to the septum
and stabilizes the system. It may be appreciated that a number of components,
such as disks, cages, balls, mesh, or other structures, may be used in place
of
one or more of the balloons to achieve a similar result.
Stabilization against the atrial septum may also be achieved by forming an
introducer or guide catheter which is rigid through the interatrial septum and
left
atrium. Typically, such introducers or guide catheters are flexible along
their
length to facilitate introduction through the tortuous paths of the vascular
system.
In an antegrade approach as described, the catheter may be inserted through
the
interatrial septum with its distal end suspended in the left atrium. In the
case of a
flexible catheter, movements at the septum may not be translated linearly to
the
catheter tip. Therefore, there may be relative movement between the distal end
and the portion passing through the septum. This may be reduced by coupling
the distal end to the portion passing through the septum. In a preferred
embodiment, the catheter shaft between and including the distal end and the
portion passing through the septum may be made rigid. Referring to Fig. 24,
the
catheter shaft 670 may be comprised of stacked elements 671. The elements
671 may be domed disks or collar segments with domed ends which are
mechanically coupled by a structure 672. The structure 672 may connect the
centers of the elements 671, as shown, in a flexible manner so that the shaft
670
may be shaped in any desired geometry suitable for use in the tissue
modification treatment. Once a desired shape is formed, the structure 672 may
be rigidified to hold the shape. Such rigidity may allow any movement of the
interatrial septum to be translated to the distal end of the catheter shaft,
thus
coupling the catheter to the movements of the heart. This may improve
stabilization of the devices and systems used in the tissue modification
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treatment. It may be appreciated that a variably rigid shaft as described may
be
utilized for coupling to any cardiac feature and may be used with or as part
of any
device component or device in the procedure. Thus, the feature may be utilized
to lock any device component, catheter or tool into place once it has been
manipulated into a desired shape. This may be useful in a variety of
situations in
addition to those mentioned above.
Stabilization against the valve may be most useful when approaching
antegrade with atrial or atrial-ventricular devices, however it may also be
useful
when approaching retrograde with ventricular or atrial-ventricular devices.
When
approaching antegrade, stabilization may be most easily achieved by coupling
one or more components of the device to the atrial walls, valve annulus, valve
leaflets, and/or valve commissures.
Coupling to the atrial walls may be accomplished by a number of
stabilization mechanisms. In each embodiment, structures such as wires,
ribbons, mesh, cages or balloons extend outwardly from the device, contacting
and applying radial force to the atrial walls. Such contact may couple the
movements of the atrium with the device for stabilization. A preferred
embodiment is shown in Fig. 25. Here, flexible wires 680 bend out radially
from
the catheter shaft 681 with curved portions contacting the atrial walls AW. It
may
be appreciated that any number of wire patterns or means of extending from the
shaft may be utilized, as mentioned above.
Coupling to the valve annulus may also be accomplished by a number of
stabilization mechanisms, many of which include simultaneous coupling to other
valve features, such as the leaflets and/or commissures. In preferred
embodiments, such stabilization mechanisms may be comprised of loops, rings,
wings, petals, arms, and the like. Coupling can be enhanced by varying surface
friction and/or combining structures with vacuum. One or more of these
mechanisms may be present, typically extending radially from a central shaft.
When two elements are present, they are commonly placed 90 to 180 degrees,
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preferably 120 to 180 degrees, apart around the central shaft. More than two
elements are typically arranged in a radial pattern around the central shaft.
Structure, size, angle and arrangement may be adjustable to fit individual
patient
anatomy.
Examples of such embodiments are shown in Figs. 26-29. Referring to
Fig. 26, a guide catheter 14 may have deployable adjustment wires 20 to serve
as a stabilization mechanism. The wires 20 are typically attached at one end
to
the distal tip of the guide catheter 14 and may be advanced at their other
ends so
that they selectively deploy from the guide catheter to engage the mitral
valve
MV. The adjustment wires 20 may act to stabilize or anchor the guide catheter
relative to the mitral valve MV by coupling to the valve annulus, leaflets or
commissures.
Similarly, the guide catheter 14 may have any number of stabilization
elements, as illustrated in Figs. 27-29. As shown in Fig. 27, the
stabilization
elements may be comprised of a number of petals 22 arranged around the distal
tip of the catheter 14. Similarly, the stabilization element may be a single
large
loop 25, as depicted in Fig. 28. Alternatively, the interventional catheter 30
may
have a plurality of stabilizing arms 34 (Fig. 29) which both position and
anchor
the distal tip of the interventional catheter 30 relative to the valve
annulus.
Usually, at least three stabilizing arms will be utilized, with four being
illustrated,
however any number may be used. The stabilizing arms 34 may be pre-shaped,
resilient metal rods (for example, formed from nitinol or other shape memory
or
superelastic alloy), ribbons, tubes, polymers or composites thereof that may
be
selectively extended from the tip of the interventional catheter 30 to engage
the
valve annulus. The interventional catheter 30 of Fig. 29 is shown with a
separately extendable interventional tool 36 which performs the desired valve
or
tissue modification, as described in more detail below. Such stabilization
elements may preferably engage the annulus located about the mitral valve MV
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and apply forward pressure against the annulus to maintain contact and provide
axial stabilization.
Stabilization may also be achieved by applying radial pressure to the
commissures. As shown in Fig. 30, a pair of stabilization elements 32 may
extend radially from a guide catheter 14 or interventional tool 30 to contact
the
commissures. The distance between the elements 32 may be equal to or slightly
greater than the distance between the commissures to apply radial force
against
the commissures. The stabilization elements 32 may be comprised of any
suitable material, such as nitinol, stainless steel, plastic or any
combination
thereof, of any consistent or variable flexibility, and any cross-sectional
shape,
such as round wire, flat ribbori or hollow tube. As shown in Figs. 31A-31 D,
the
shape of the stabilization element may be of any suitable symmetrical or
nonsymmetrical geometry, including but limited to triangular (Fig. 31A),
rectangular (Fig. 31 B), circular, oblong, double-humped (Fig. 31 C) or single-
humped (Fig. 31 D). It may be appreciated that such stabilization mechanisms
may also serve in orientation assessment, particularly as the frame 626 (Fig.
20)
previously described. Thus, they may be echo or fluorogenic or treated for
such
effects. In addition, it may be appreciated that such stabilization elements
may
be passive, i.e., pre-sized and shaped to fit the patient anatomy so that they
engage the valve annulus without adjustment, or may be active so that they can
be used to steer the guide catheter as previously described.
A number of stabilization mechanisms apply both radial and axial pressure
to the valve for stabilization. For example, the double-humped element, shown
in
Fig. 31 C, has a superior hump 700 which may protrude into the left atrium,
contacting the superior aspect of the annulus and possibly the left atrial
wall, and
an inferior hump 701 which may protrude into the left ventricle, contacting
the
inferior aspect of the annulus and possibly the left ventricle wall or chordal
tissue.
The superior hump 700 may apply a downward axial force on the annulus and
the inferior hump 701 may apply an upward axial force. The waist 702 between
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the humps may be dimensioned or adjustably sized to fit between the
commissures and to apply a radial force on the commissures. Similarly, a
single-
humped element, shown in Fig. 31 D, may provide similar stabilization without
the
added support from the protruding inferior hump. Additionally, this design may
be easier to position in the mitral valve.
The last general category of stabilization mechanisms for descriptive
purposes is stabilization against the chordae. Stabilization against the
chordae
may be most useful when approaching retrograde with ventricular or atrial-
ventricular devices. Coupling to the chordae may be useful in stabilization
for
tissue modification to the valve, the chordae, the annulus or a combination of
these. When modifying the valve, the contact with the valve structures
(typically
grasping of the valve leaflets) may still be necessary. However, when
modifying
the chordae, additional contact (such as grasping the chordae) may not be
necessary since the stabilization methods may include this step. Therefore,
stabilization against the chordae will be discussed in Section VII I Grasping.
VII. IMMOBILIZATION
Immobilization refers to substantially retarding or diminishing the motion of
the cardiac structures or intermittently or temporarily stopping the cardiac
cycle.
This may be accomplished with a variety of methodologies. First, drugs may be
injected to temporarily slow or stop the cardiac cycle. Such drugs may include
but are not limited to esmolol, adenosine, isofluorane and transarrest
mixture,
with or without electrical pacing. Likewise, induced atrial fibrillation may
interrupt
the cardiac cycle.
Mechanical immobilization of the valve can be effected in a variety of
ways. Most simply, valve action can be diminished or stopped by raising the
pressure in the associated ventricle to a pressure above that in the atrium
during
diastole. For example, a suitable liquid can be infused into the ventricle to
raise
the intraventricular pressure, or the aortic valve could be temporarily
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incapacitated allowing aortic regurgitation and raising the ventricular
diastolic
pressure. Alternatively, interventional tools and/or catheters carrying such
tools
may simply be mechanically stabilized against the valve, valve annulus, valve
commissures, ventricular wall, atrial wall, generally as described above.
Mechanical valve immobilization will usually involve more interaction with
the valve than simple stabilization. Immobilization will usually involve
either
capture and immobilization of either or both valve leaflets (or all three
valve
leaflets in the case of a tricuspid valve) or capture and immobilization of
the
chordae. For example, balloons or mesh cages may be used and placed under
one or both leaflets to hold them partially closed. By temporarily
immobilizing or
adjusting the valve action, such as changing the point of coaptation, it is
possible
to see if a particular modification will be sufficient to treat the
regurgitation. For
example, by temporarily grasping the valve leaflets at a particular point and
holding the leaflets together, it can be determined whether a permanent
suturing,
stapling, or other affixation at that point will achieve a sufficient
reduction in
regurgitation. When the heart is beating, valve regurgitation can be examined
in
real time via conventional imaging techniques, such as TEE. If the temporary
valve modification appears sufficient, it can then be made permanent using any
one of a variety of interventional techniques.
VII. GRASPING
Valve or tissue modifications or interventions most commonly require
grasping a portion of the valve or tissue to be modified. Such grasping may be
useful in adjusting tissues (such as coapting valve leaflets) for appropriate
modification, checking the positioning of the tissues for improved biological
function, and stabilizing or immobilizing the tissue for the modification
procedure.
As previously described, such grasping may also be useful to stabilize another
tissue which will be modified in the procedure, such as the grasping the
chordae
to stabilize the valve for valve modification. Since the most common
procedures
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may involve valve modification or chordal modification, grasping of these
cardiac
structures will be discussed. However, it may be appreciated that described
grasping devices, systems and methods may apply to any cardiac or other
structure.
A. Chordal grasping
Grasping of the chordae may involve capturing and anchoring the
chordae, as illustrated in Figs. 32-40. As shown in particular in Figs. 32A
and
32B, a guide catheter 40 can deploy a first capture coil 60 and a second
capture
coil 62 through a pair of deployment catheters 64 and 66, respectively. The
coils
will be positioned while visualizing so that the first coil 60 captures
chordae
attached to a first valve leaflet LF and coil 62 captures chordae attached to
a
second valve leaflet LF. The capture coils will typically be elastic wires,
preferably composed of a superelastic material such as nitinol, which are
delivered through the deployment catheters in a straightened configuration.
When they are advanced out of the deployment catheters, the capture coils will
assume a helical or other configuration that can be advanced into and entangle
the chordae.
The coils 60 and 62 may then be brought together laterally preferably
coapt the leaflets LF together by advancing a retaining ring 68 which is
secured
at the distal end of a deployment wire 70, as illustrated in Fig. 32B. The
leaflets
are thus brought together and immobilized for a subsequent intervention.
Alternatively, if immobilization via the coils 60 and 62 is sufficient in
itself, it will
be possible to make the deployment permanent. It is a particular advantage of
the temporary immobilization that the valve action can be examined via the
real
time imaging techniques to see if regurgitation has been adequately addressed.
If it hasn't, the coils can be redeployed or the relative positions of the two
coils 60
and 62 can be changed until an adequate pair has been effected.
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It will be appreciated that if a subsequent interventional step is required,
it
can be made from either an antegrade or retrograde approach. A variety of
specific interventional techniques are described in detail hereinbelow.
An antegrade approach for deploying a single chordae snare 74 and
optionally securing a suture loop about the captured chordae is illustrated in
Figs. 33A and 33B. A guide catheter 14 deployed over the leaflets LF of the
mitral valve MV may be deployed as described previously. A pair of deployment
catheters 76 and 78 are advanced from the distal end of the guide catheter 14
and observed in real time via any of the imaging techniques described
previously. The pre-shaped snare 74 is advanced out of the first deployment
catheter 76 and is advanced through both of the chordae CT, as illustrated in
Fig.
33A. A capture loop 80 is advanced from the second deployment catheter 78
and positioned so that it lies in the path of the pre-shaped snare 74 as it is
advanced through the chordae CT. After a capture tip 82 passes through the
capture loop 80, the loop can be tightened to secure to the capture tip 82 and
draw the tip into the second deployment catheter 78. The capture tip 82 is
attached to an end of a length of suture 84 (Fig. 33B) which runs back through
a
lumen in the snare 74. In this way, the suture may be pulled into the second
deployment catheter 78, while the snare 74 is withdrawn back into the first
deployment catheter 76, leaving only the suture in place grasping both the
chordae. By then tying or otherwise securing the suture together into a
permanent loop through the chordae, the coaptation of the valve leaflets LF
can
be modified in a desired way. As with the previous embodiments, a particular
advantage of this approach is that the valve coaptation can first be viewed
using
the real time imaging capability to assure that valve regurgitation is
adequately
addressed before making the chordae capture permanent.
An alternative technique for deploying suture to capture chordae CT is
illustrated in Fig. 34. First deployment catheter 90 (positioned through a
guide
catheter which is not shown) is positioned through the opening between valve
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leaflets LF. A balloon 93 at the distal end of chordae snare 92 is extended
through the chordae, as described previously. The balloon 93 is inflated and
floated through the mitral valve during regurgitation. The balloon will pass
through the previously deployed capture snare 95. Alternatively, the chordae
snare 92 could be shaped so that it will encircle the chordae and then pass
outwardly through the valve opening and into the previously deployed capture
snare 95.
A chordae stabilization catheter 100 which is particularly suited for a
retrograde approach is illustrated in Fig. 35. The catheter 100 includes a
catheter body 102 having a pair of lumens 104 and 106 extending from a
proximal end (not shown) to a distal end which is illustrated in Fig. 35A. The
main lumen 104 extends fully to the distal tip of the catheter body 102 and a
chordal snare 108 is slidably received in the lumen. The snare 108 has a loop
pre-formed over its distal end so that, when extended from the catheter 100,
it
will assume the shape shown in Fig. 35. The loop has a diameter generally in
the range from 3 mm to 20 mm and is shaped so that it will evert backwardly
into
a secondary loop formed by a capture snare 112. The capture snare 112 is
disposed in the secondary lumen 106 and emerges from an opening 114 space
proximally from the distal end of the catheter 100. The distal tip of the
capture
snare 112 is fixed at an anchor point 116 in the distal tip of the catheter
body
102. Thus, by extending and retracting the capture snare 112, the capture loop
can be moved between the position shown in full line and broken line.
Referring now to Figs. 36A and 36B, use of the catheter 100 for capturing
and stabilizing chordae CT will be described. The catheter 100 is introduced
in a
retrograde direction (although antegrade would also be possible), typically
through a guide catheter 40 as generally described above. Under direct (e.g.,
fluoroscopic) observation, the distal end of the catheter 100 will be guided
to a
position generally within the chordae CT, as illustrated in Fig. 36A. The
chordae
snare 108 will then be extended from the distal tip so that it passes through
and
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becomes entangled with the chordae CT attached to both of the leaflets LF. The
distal tip of the chordal snare 108 will eventually pass through the loop
defined by
the capture snare 112, also as illustrated in Fig. 36A. The capture snare will
then
be tightened to hold the distal tip of the chordae snare 108, and the chordae
snare then retracted so that the loop of the snare which passes through the
chordae will be tightened, generally as shown in Fig. 36B. Generally, the
catheter 100 will not be intended for permanently affixing the chordae CT.
Instead, immobilization of the valve leaflets LF will be intended to
facilitate a
subsequent treatment step, as described hereinafter. Use of the retrograde
approach for immobilizing the chordae CT will be particularly advantageous
when
used with antegrade interventions.
The catheter of Fig. 35 could, however, be modified to facilitate
performance of retrograde interventions while the chordae are stabilized. As
shown in Fig. 37, the catheter 120 inciudes a catheter body 122 which is
generally the same as that shown for catheter 100 in Fig. 35 (with common
components being given identical reference numbers), except that a third
working lumen 124 is provided. The working lumen 124 can be used to deliver
and position a wide variety of interventional tools for performing at least
most of
the specific interventions described elsewhere in this application. The
catheter
120 will, of course, be particularly useful for performing interventions which
rely
on retrograde stabilization of the chordae CT of the type provided by the
catheter. For example, the lumen 124 may be used to position an RF energy
delivery tool for heating the chordae to cause shrinkage, as described in more
detail below. Alternatively, the working lumen 124 could be used to position a
chordae stabilization coil 130, generally as described in Figs. 39A and 39B.
The
coil is typically a helical filament having a secondary helical structure
comprising,
for example, three major loops. The coil may comprise an inner element
composed of a shape memory material, such as nitinol, inserted into an outer
coil
132 made of a radiopaque material, such as a platinum alloy. The shape
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memory coil 134 is formed into a "stacked coil" configuration (with no space
between adjacent windings of the coil) and then programmed so that it will
assume the stacked coil configuration at a temperature slightly above body
temperature. The coil assembly 130 is formed by heat treating the platinum 132
to a diameter D1 and length L1, as shown in Fig. 39A. The shape memory coil
134 is then stretched to a near linear configuration and inserted into the
platinum
coil 132, and the two are coupled at the end. Upon heating, the shape memory
coil contracts back into its tightly stacked coil shape, compressing the
platinum
coil 132, and causing the entire assembly 130 to assume a smaller diameter D2
and length L2, as shown in Fig. 39B. The coil 130 may be delivered using a
pusher catheter through the working lumen 124 so that it deploys within and
antangles the chordae CT, as shown in Fig. 40. The pusher catheter (not shown)
could be configured similarly to embolic coil delivery catheters, such as
those
Jescribed in U.S. Patent Nos. 5,226,911; 5,234,437; 5,250,071; 5,261,916;
5,312,415; 5,350,397; and 5,690,671, the full disclosures of which are
ncorporated herein by reference.
B. Valve leaflet grasping
Valve leaflet grasping may be accomplished using a number of methods,
-nost commonly the following three: 1) pinching, 2) partially or fully
penetrating or
)iercing, and 3) the use of suction or vacuum. Pinching involves grasping the
wrface or edge of the leaflet without penetrating the tissue. This may be
ccomplished by an antegrade or retrograde approach using atrial, ventricular
or
atrial-ventricular devices. It may be appreciated that although the following
mbodiments are examples which are described relative to a specific approach
antegrade or retrograde), each device or component may be used or adapted to
)e used in all approaches.
In preferred embodiments, depicted in Figs. 41-43, pinching of the valve
eaflets LF can be achieved, for example, by using a grasping catheter
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introduced in a retrograde direction to temporarily capture the free ends of
the
valve leaflets LF. It may be possible to use a simple two-jaw tool at the
distal
end of a catheter to capture both opposed leaflets. Such a two-jaw tool 710 is
depicted in its open position in Fig. 41A. In this position, opposing jaws 711
may
be positioned on opposite sides of the free ends of the valve leaflets LF. In
its
closed position, depicted in Fig. 41 B, the leaflets may be drawn together and
pinched to immobilize the valve. Although this may be adequate, it may be
preferred to use a three-jaw capture tool as shown in Figs 42-43. The catheter
140 can be delivered through a guide catheter generally as described above.
The catheter includes a tool 142 at its distal end. Tool 142, as best shown in
Fig. 42B, includes a fixed center jaw 144 and a pair of pivotable outer jaws
146
and 148. The jaws 146 and 148 may be independently opened to a "capture"
position as shown in broken line in Fig. 42B. Actuation of the jaws 146 and
148
may be achieved in a variety of conventional manners, including pull wires,
push
wires, inflatable balloons, heat memory alloy motors, and the like. By
independently opening and closing the capture jaws 146 and 148 against the
fixed jaw 144, the valve leaflets LF can be captured independently.
As shown in Fig. 42A, a first leaflet LF can first be captured. The catheter
140 can then be manipulated and positioned, typically under real time imaging,
to
capture the second leaflet LF, as shown in Fig. 43. It will be appreciated
that
independent capture of the leaflets greatly facilitates the procedure. Use of
a
single pair of capture jaws requires that the leaflets be captured at the
instant
when they are properly opposed. In the case of prolapsed valves, such an
instance may never occur. Once captured and immobilized, as shown in Fig. 43,
the valve leaflets can then be modified in any one of a variety of ways, as
described elsewhere in the application.
Additional embodiments, depicted in Figs. 44-46, involve pinching of the
valve leaflets LF by using a grasping catheter introduced in an antegrade
direction to temporarily capture the surfaces or the free ends of the valve
leaflets
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LF. Referring to Figs. 44A-44D, the valve leaflets LF may be pinched between a
superior loop 720 and an inferior loop 721. In a preferred embodiment, the
grasper is comprised of a nitinol flat ribbon heat set in the shape of double
loops
720, 721. The ribbon may be mounted on a series of three coaxial shafts, an
interior shaft 725, a central shaft 726 and an exterior shaft 727. The distal
end of
the ribbon may be attached to the distal end 730 of the interior shaft 725, a
midportion of the ribbon may be attached to the distal end 731 of the central
shaft
726, and the proximal end of the ribbon may be attached to the distal end 732
of
the exterior shaft 727. One or more ribbons may be mounted on the coaxial
shafts; in this example, two ribbons are shown 180 degrees apart. When
extended, as shown in Fig. 44A, the grasper may be pulled flat against the
shafts
725, 726 ,727 for ease of insertion through a guide catheter or tool and into
a
desired position between the valve leaflets LF. When the central shaft 726 is
retracted or the exterior shaft 727 advanced, as shown in Fig. 44B, the
superior
loops 720 may extend radially from the shafts. The superior loops 720 may rest
on the superior surface of the valve leaflets LF in the atrium, as shown in
Fig. 44D. In this position, the superior loops 720 may aid in orientation
assessment, as the superior loops may be echo or fluorogenic and may be easily
visible in relation to the cardiac structures or other devices or components.
When positioned in a desired location, the interior shaft 725 may then be
retracted, as shown in Fig. 44C, to extend the inferior loops 721 radially
from the
shafts. The inferior loops 721 may be in contact with the inferior surface of
the
valve leaflets LF in the ventricle. Thus, the valve leaflets LF may be pinched
between the inferior loop 721 and superior loop 720. It may also be
appreciated
that the inferior loops 721 may be deployed prior to the superior loops 720.
Referring to Figs. 45A-45B, the valve leaflets LF may be pinched between
a superior roller 750 and an inferior roller 751. As shown in Fig. 45A, the
rollers
750, 751 may be mounted on a shaft 755 and connected by a pull actuation wire
756. The rollers 750, 751 may be serrated or surface treated in a directional
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pattern to facilitate grasping of the valve leaflets LF. To grasp a leaflet
LF, the
rollers 750, 751 may be placed against the surface or free edge of the leaflet
LF.
Pulling of the actuation wire 756 may rotate the superior roller 750 and
inferior
roller 751 toward each other. This may draw the leaflet LF between the rollers
750, 751, as shown in Fig. 45B. Thus, the leaflets LF may be individually
grasped for treatment.
Referring to Figs. 46A-46B, the valve leaflets LF may be pinched between
a pair of flat coils 770. In a preferred embodiment, each coil 770 may be
comprised of nitinol flat ribbon heat set in the shape of a coil. As shown in
Fig. 46A, the coils 770 may be linked together with opposing curvature by a
clip
772. Movement of the clip 772 along the coils 770 may uncurl the coils 770 to
a
straightened configuration. As shown in Fig. 46B, this may also be
accomplished
by a catheter shaft 773 placed over the coils 770. In the straightened
position,
the coils 770 may be inserted between the valve leaflets LF in an atrial-
ventricular position so that the distal ends 775 of the coils 770 are in the
ventricle. As the shaft 773 or clip 772 is retracted, the coils 770 may begin
curling radially beneath the valve leaflets LF and upwardly so that the distal
ends
775 of the coils 770 contact the inferior surface of the valve leaflets LF.
Similarly,
if the coils 770 continue curling, a portion of the flat ribbon proximal to
the distal
end 775 may contact the valve leaflet. In this manner, the leaflets may be
grasped for treatment. Such a grasping device may also serve as a fixation
device with the pair of coils 770 left in place, as will be described in a
later portion
of the application.
A valve or tissue structure may also be grasped by atraumatic partial or
full penetration or piercing. This may be accomplished with a variety of
grasping
mechanisms. Preferred embodiments include one or more prongs extending
from an interventional tool in an arrangement to grasp a specific structure.
Specifically, three opposing prongs may extend from a grasping sheath with
distal ends configured to pinch, partially penetrate or pierce. Such ends may
be
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pointed or may be soft, as in the case of rounded, urethane coated or solder
coated ends. Referring to Fig. 47A, the opposing prongs 800 may be retracted
into a grasping sheath 801 to hold the prongs 800 in a closed configuration.
It
may be preferred to orient the device to a desired position in this
configuration.
When the target tissue has been located, the prongs 800 may be extended to
grasp the tissue structure, as shown in Fig. 47B. This may be accomplished by
either extending the prongs 800 axially or retracting the grasping sheath 801.
The target tissue may be pinched, partially penetrated or pierced with the
prongs
800 in this configuration, or such action may be facilitated by closing or
partially
closing the prongs 800 as previously depicted in Fig. 47A. Alternatively, the
prongs 800 may be attached to or integral with a prong-tipped tube 802, as
shown in Fig. 47C. Such a design may be more conducive to the insertion of
tools or fixation devices for further treatment steps, such as tissue
modification.
Tools or devices may be inserted through a lumen in the prong-tipped tube 802,
depicted by arrows 804, for use at or near the grasping location. Similarly,
tools
or fixation devices may be inserted through a lumen in a hollow prong 806, as
depicted in Fig. 47D. Here, one or more prongs 806 may be hollow, and the
remaining prongs 808 may be comprised of solid wire or a suitable material.
Tools or devices may be inserted through a lumen in the hollow prong 806,
depicted by arrows 810, for use at or near the grasping location. Prongs,
hollow
or solid, may be made from stainless steel, NiTi, plastic or other suitable
material.
Additionally, they may be coated or coiled to enhance visibility. Likewise,
the
geometries of the prongs may be varied to facilitate grasping of the desired
amount of tissue. And, the distal tip sharpness and surface finish can be
varied
to establish the amount, if any, of piercing.
In addition to directly engaging the valve leaflets to effect stabilization
and/or immobilization with the grasper devices described above, the devices
and
methods may also employ a catheter or other tool having vacuum or suction
applicators to temporarily capture the valve leaflets. As shown in Fig. 48, a
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catheter 812 comprises a shaft having a pair of vacuum applicator rods 813 and
814. Usually, the vacuum applicator rods 813 and 814 will comprise separate
shafts which may be axially translated relative to the main shaft of the
catheter.
Further optionally, the shafts could be articulated or otherwise manipulable
so
that they can be independently positioned relative to the valve leaflets or
other
tissue structures once the catheter 812 is in place. The vacuum applicators
have
one or more apertures to permit contact and adherence to tissue when the
applicators are attached to external vacuum sources. Usually, the shaft will
be
placed across the valve, either in an antegrade or retrograde fashion, and the
applicators positioned to grasp and manipulate the valve leaflets. Optionally,
the
catheter 812 may comprise additional stabilizing and/or steering wires of the
type
previously described. For example, a steering wire 815 (and optionally a
second
steering wire on the opposite side) may be provided for engaging against the
valve commissures to permit positioning of the catheter with respect to the
valve
leaflets. The vacuum applicators would further be independently positionable
to
engage the valves in the desired fashion. Using this catheter, the leaflets
can be
grasped and the competency of the valve evaluated using the methods described
previously. The valve adjustment can then be effected using any of the
interventional approaches described herein. Further, it may be appreciated
that
in each embodiment, timing of grasping may be facilitated by the use of gating
with the patient's EKG, pressure waves of the cardiac cycle, audio heart
sounds,
electronic pressure or contact sensors on the graspers.
VIII. COAPTATION, ADJUSTMENT AND EVALUATION
Once the valve leaflets, chordae or tissue structure is grasped by an
interventional tool, the tissue may be manipulated to achieve a desired
result,
such as improvement in valve function. Such manipulation may occur during the
grasping step, or it may require a separate step following grasping. In the
case
of leaflet modification, valve leaflets may be coapted or brought together and
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held in a preferred apposition. The valve function may then be evaluated for
indications of improved valve function, such as reduced regurgitation. If
further
improvement is desired, the valve leaflets may be additionally manipulated or
adjusted. Adjustment should primarily occur in a superior/inferior (up/down)
motion in order to bring the leaflets to a final positioning where
regurgitation is
minimized. During adjustment, one or both leaflets may be released and
recaptured with new positioning. After the final evaluation, the valve
leaflets may
be fixated in the desired position by an appropriate fixation device. In the
case of
chordae shortening or other tissue modification, similar steps may be taken.
IX. TISSUE MODIFICATIONS
Repair of atrioventricular or other cardiac valves is effected by modifying
the valve or a supporting tissue structure in some way to affect blood flow
through the valve during a phase of the cardiac cycle, for example to permit
blood flow through the valve during diastole when the associated ventricle is
filling with blood but which inhibits or prevents blood regurgitation back
through
the valve during systole. A number of techniques for modifying the valve
closure
by capturing or grasping the chordae attached to each valve leaflet have been
described above. These techniques are often used just for valve grasping
and/or
coaptation and adjustment prior to a separate valve modification step, but
they
may also be made permanent to provide the final valve modification. Other
techniques for more directly modifying the leaflets or other supporting
structures
of the atrioventricular valves will be described in this section. These
techniques
may be utilized either with or without the valve grasping and/or coaptation
and
adjustment techniques described above. For purposes of simplicity, however,
the following methods will generally be described without specifically
illustrating
such grasping, coapting and adjustment approaches, focusing primarily on the
methods and devices involved with fixation. In addition, it may be appreciated
that although the following embodiments are examples which are described
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relative to a specific approach (antegrade or retrograde), each device or
component may be used or adapted to be used in all approaches. Further,
although devices and methods are described for fixating specific tissues, such
as
valve leaflets or chordae, such devices and methods may be used for any
cardiovascular tissues and the like.
A. Fixation of Valve Leaflets
Suture can be delivered through the valve leaflets and then tied in a
manner analogous to an open surgical procedure. In one embodiment, a
suturing tool 200, shown in Fig. 49, may be positioned at the distal end of an
interventional catheter. The interventional catheter will usually be advanced
in
an antegrade direction (i.e., from above the mitral valve), either directly
through a
guiding catheter or through a working lumen in a stabilization catheter. The
tool
200 carries a length of suture 202 attached to a pair of needles 204 at either
end
thereof. The suture may be comprised of conventional suture material or of
wire,
typically stainless steel, nitinol or other material. The needles are held on
a
reciprocating shaft 206 disposed within a lumen of a retrieval sheath 208. The
tool 200 can be positioned to capture the opposed free ends of the mitral
valve
leaflets LF, generally as shown in Fig. 49. The needles can then be advanced
through the leaflets LF by drawing the shaft 206 toward the sheath 208 so that
the needles 204 penetrate the leaflet and are captured in needle receptacles
210
formed in the sheath 208. The sheath can then be withdrawn. A knot can be
tied in the suture, and the knot then advanced through the associated catheter
to
tighten over the valve leaflets. The tool 200 can carry two, three, four, or
even
more lengths of suture which may be simultaneously or sequentially introduced
into the valve leaflets in order to permit multiple suture loops to be placed.
The
resulting tied suture loops will be similar to the "bow tie" sutures placed in
open
surgical procedures which have been described in the medical literature as
described above.
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The need to place and draw long lengths of suture through the valve
leaflets can, however, be deleterious to the fragile leaflet structures. Thus,
alternative needle and suture devices which rely on mechanical fasteners in
relatively short suture lengths may be preferred. In one embodiment, a hollow
suturing coil 1300, shown in Fig. 49A, may be positioned at or near the distal
end
of an interventional catheter. The suturing coil 1300 may be comprised of any
material of sufficient rigidity to pierce and penetrate through valve leaflets
LF,
such as stainless steel, various shape memory or superelastic materials, metal
alloys and various polymers, to name a few. The hollow suturing coil 1300 may
contain a suture 1302 comprised of conventional suture material or of wire,
typically stainless steel, nitinol or other material. The suture 1302 may be
secured at the tip 1304 of the coil 1300 with a toggle rod 1305. After the
valve
leaflets LF have been grasped and coapted, the suturing coil 1300 may be
advanced in a corkscrew fashion through the valve leaflets LF, as shown in
Fig. 49A. Though such advancement is shown from above, advancement may
be made from any direction through any number and configuration of valve
leaflet
layers. When advancing, the sharpened tip 1304 of the coil 1300 may pierce
through the leaflets LF any number of times. It may be appreciated that such
corkscrew piercing may be made through the middle portions of the leaflets
such
that a pierce is made at each half-rotation, or the piercings may be made
along
the edges of the leaflets such that a pierce is made at each full-rotation, to
name
a few.
Once the coil 1300 has advanced to a desired location, the toggle rod
1305 may be secured against a leaflet LF to hold the suture 1302 in place. At
this point, the coil 1300 may be removed by retracting the coil 1300 in a
reverse
corkscrew fashion, as depicted in Fig. 49B, leaving the suture 1302 behind.
Since the coil 1300 may be much larger in diameter than the thickness of the
leaflets (to aid in placement), the suture 1302 may be loose-fitting and the
valve
leaflets LF insufficiently modified. The suture 1302 may then be tightened, as
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shown in Fig. 49C, so that the suture 1302 holds the leaflets LF together in a
desired configuration. This may be aided by the use of a soft-tipped catheter
1306 which may be advanced to contact the surfaces of the leaflets LF when
tightening to prevent the leaflets LF from prolapsing. Once the suture 1302 is
sufficiently tight, a restrictive collar 1308 may be deployed from the
catheter 1306
or another device to secure and terminate the suture 1302. Such a restrictive
collar 1308 may be comprised of any suitable material, such as heat-shrink
tubing, nitinol shape-memory or superelastic coil or the like. Thus, this
embodiment eliminates the need for needle passers and needle receivers
providing a simplified method of valve leaflet fixation.
Alternatively, referring to Figs. 50 and 51, a short length of suture 220 may
be positioned using a curved needle 222 which can be extended from the distal
tip 224 of an interventional catheter 225. The needle 222 is formed from an
elastic material, such as a shape memory alloy, and may be constrained in a
generally straightened configuration within the catheter 224. When extended,
as
shown in Fig. 50, it assumes a curved shape so that it may be advanced through
the atrioventricular or other cardiac valve leaflets LF, as shown in Fig. 51.
A
distal anchor 226 is secured to the distal end of the suture 220 while a
slideable,
locking anchor 228 is placed over a portion of the suture located proximally
to the
distal anchor 226 as shown in Fig. 50. The catheter 225 may be advanced to the
valve leaflets LF in a retrograde approach, as shown in Fig. 51, using a guide
catheter 40, as generally described above. The distal end 224 of the catheter
225 is positioned adjacent to the underside of a valve leaflet, and the needle
222
then advanced outwardly from the distal tip so that it passes through both
valve
leaflets.
In order to assure that the valve leaflets are in a proper orientation prior
to
needle advancement, the valve leaflets may be coapted and observed using any
of the techniques described previously. After the needle has been advanced
through the leaflets LF, a deployment sleeve 230 is advanced to release the
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slideable anchoring catheter 228 from the needle and advance it toward an
underside of the valve leaflet LF. As the anchor 228 approaches the valve
leaflet, tension on the suture 220 will pull the distal anchor 226 from the
needle.
The deployment sleeve 230 can be advanced sufficiently to draw the two
anchors 226 and 228 together on opposite sides of the valve leaflets, as seen
in
Fig. 52. The suture can then be tied off or, alternatively, locked in place
using a
mechanical lock 232. If the suture is comprised of a malleable wire, as
previously described, the wire may be twisted together. In either case, the
suture
is then severed and the catheter 225 withdrawn.
The anchors 226 and 228 shown in Fig. 50 are generally oval shaped and
have a length dimension which is greater than the width of the needle used to
introduce them. Thus, when pulled laterally, they can seal against the opposed
surfaces of the two valve leaflets. In some instances, however, it will be
desirable to have anchors which are capable of expanding to a much larger
dimension to assure that they do not pull through the relatively fragile
tissue of
the leaflets. An exemplary expansible anchor 240 is shown in its collapsed
configuration within a needle 242 in Fig. 53 and its expanded configuration in
Fig. 54. The anchor 240 is connected to a length of suture 244 and could be
used with a similar slideable, expansible anchor (not shown) analogous to the
non-expansible anchor 228 of Fig. 50.
Additional expansible anchors may be seen in Figs. 55A and 55B. In this
embodiment, the anchor is comprised of an expanding randomly oriented wire
coil. The coil is made from a shape memory nitinol wire that is annealed (heat
set) in a straight configuration and then coiled. As shown in Fig. 55A,
different
sections 820, 821 of the coil may be processed to have different properties by
varying the diameter and tension in the coil along its length. When the coil
is
heated to a specified level (T1), such as with RF energy, a designated portion
821 of the coil will become a randomly oriented mass of wire 824 with self-
locking struts to prevent disentanglement. When the coil is heated to a
different
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specified level (T2), a different designated portion of the coil 825 will
become
randomly oriented. As each portion of the coil 824, 825 expands and changes
shape, a full entanglement of the coils is allowed to occur, effectively
compressing and fixing the two halves 824, 825 of each coil together. The coil
may be introduced through the valve leaflets LF with the use of a shape
memory,
super elastic or heat/current activated needle introducer 826. Once the valve
leaflets LF are pierced, an anchor 824 may be activated and deployed distally.
The introducer 826 may then be retracted to the proximal side of the second
leaflet LF2 and the second anchor (not shown) may be deployed in the same
manner. The amount of tension between the anchors 824, 825 may be affected
with the shape memory or super elastic properties of the expanding anchor. It
may be appreciated that the heat activated expanding coil may alternatively
take
other forms, such as a wire mesh, for example. Additional expansible anchors
may be in the form of inflatable chambers filled with a liquid that may
optionally
partially or fully solidify.
Yet another form of detachable anchor attached to a length of suture is
illustrated in Figs. 56 and 57. Fig. 56 is a front view, while Fig. 57 is a
side view
of the same structure. A self-penetrating anchor 260 attached to a length of
suture 262 is carried on a pair of rods 264. The rods are mounted within an
open
lumen of a deployment catheter 266. The anchor 260 can pivot on a detent
structure 268 formed between the distal ends of the deployment rods 264. The
anchor has a sharpened distal tip 270 which permits the anchor to be directly
penetrated through the valve leaflet tissue when the rods are extended from
the
catheter 266.
Referring now to Fig. 57, the catheter 266 may be deployed over the
leaflets LF of the mitral valve MV in an antegrade direction through a guide
catheter 14 as generally described above. The catheter 266 can be used to
deliver a pair of the anchors 260 sequentially. As shown in Fig. 58, a first
anchor
260a has been deployed through a first leaflet and a second anchor 260b has
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just been placed through the second leaflet. The anchors 260a and 260b are
deployed by pushing them through the leaflet tissue while the sharpened tip
270
remains generally in a distal or forward direction. After passing through the
tissue, the anchor 260a/260b can be turned, either by pulling back on the
deployment rods 264 or by pulling backwardly on the suture 262. The two ends
of suture 262 can then either be tied or fastened using a mechanical fastener
in
order to draw the opposed leaflets into proper apposition.
Referring now to Figs. 59 and 60, a deployment catheter 290 having a
needle 280 with sharpened distal tip 282 can be used to place suture loops in
individual valve leaflets. A needle 280 is carried on a pair of actuator rods
284
with a length of suture 286 attached to the needle. The needle 280 is first
passed through the leaflet in a generally axial orientation with respect to
the
catheter 290. After passing through the leaflet from a guide catheter 14, as
shown in Fig. 60, the needle is canted at an angle from 20 to 30 and passed
back through the leaflet at a different position. A locking groove.288 on the
needle is captured on a bar 292 in the distal end of the catheter 290. The
needle
280 may thus be detached from the rods 284 to pull suture 286 in a loop back
through the leaflet. This way, loops of suture may be placed successively
through both leaflets LF of a mitral valve MV, as shown in Fig. 60. The suture
loops may then be tied off, connected with fasteners, fused together using RF,
microwave or ultrasound energy, or otherwise secured to close the valves
together in a desired apposition.
In addition to sutures and suture-based devices, as just described,
opposed points on the valve leaflets and/or chordae can be attached with a
variety of staples and tissue-penetrating fasteners. The staples and other
fasteners can be delivered through guide catheters, generally as described
above, and may be positioned during or after valve grasping, coaptation and
adjustment, also as described above.
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Referring now to Figs. 61A and 61 B, staple applying catheter 300 is
schematically illustrated. Typically, the leaflets LF of a mitral or other
atrioventricular valve will first be accessed by any of the techniques
described
above. The catheter 300 will then be introduced in a retrograde fashion, for
example, as illustrated previously. A staple 302 is held in an open position
at the
distal tip of the catheter 300 and has a generally W-shaped profile with two
recesses for receiving each of the leaflets LF, as shown in Fig. 61A. After
proper
positioning is confirmed visually, the staple 302 may be closed over the
leaflets
so that the tips penetrate opposed points on each leaflet by pulling on an
actuator cord 304, as shown in Fig. 61 B. The actuator cord can then be
detached and the catheter 300 withdrawn, leaving the staple 302 in place to
hold
the leaflets together. Optionally, additional clips can be placed in a like
manner
to further strengthen the affixation of the leaflets. As described, the clip
is a
malleable clip which undergoes plastic deformation for emplacement.
Alternatively, the clip could be formed of an elastic material, such as a
shape
memory alloy, and held in its open position as shown in Fig. 61A. The clip
could
then be placed by releasing it to return to its memory (closed) configuration,
as
shown in Fig. 61 B. Other actuation mechanisms could also be used, such as the
use of heat to induce a shape change in a heat memory alloy staple.
In addition, two part snaps, rivets and staples may be used to hold leaflets
in place by locking together. This may be achieved by a number of device
designs. Preferred embodiments involve two disks 850, pledgets, or the like,
placed on opposite sides of tissues or leaflets LF to be bound together, as
shown
in Fig. 62A. Typically a shaft 852, pin or needle may pierce the leaflets LF
and
connect the two disks 850. The disks 850 may then be snapped or joined
together by interlocking one or both disks 850 to the shaft 852 and/or
portions of
the shaft 852 to each other. Such a fixation device may be introduced through
a
lumen of a specialized catheter 854, introducer or component of an
interventional
tool, as shown in Fig. 62B. The disks 850 may be solid and/or rigid requiring
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placement on each side of the tissue, or the disks 850 may be flexible,
collapsible and/or inflatable such that they may be inserted through the
tissue for
placement on the other side of the tissue. Preferred embodiments also involve
two disks 855, pledgets, or the like, which are placed between tissues or
leaflets
LF to be bound together, as shown in Fig. 62C. Here, the disks 855 have
penetrating prongs 856 at each end to pierce and grasp tissue. When the disks
855 are snapped or joined together by interlocking one or both disks 855 to a
shaft 858, shown in Fig. 62D, and/or portions of the shaft 858 to each other,
the
leaflets LF may be bound together.
An additional embodiment of a two part rivet-like stapling mechanism is
illustrated in Fig. 63. A stapling mechanism 322 at the distal end of a
catheter
320 comprises a first jaw 324 which carries a fastener 326 and a second jaw
328
which carries a retaining ring 330. The fastener has a collapsible cone 332 at
its
distal end so that it may be forced into an aperture 334 in the retaining ring
330.
The jaws 324 and 328 are pivotally mounted within the distal end 340 of the
catheter so that they may be opened and closed to grasp the free ends of the
valve leaflets therebetween. The closing of the jaws 324 and 328, however,
does not lock the fastener 326 into the retaining ring 330. Thus, the valve
leaflets can be temporarily grasped and the improvement in valve regurgitation
visually assessed. If the improvement is sufficient, the fastener 332 can be
driven into the tissue and locked in the retaining ring 330. If the
improvement is
not sufficient, the jaws can be repositioned on the valve leaflets one or more
additional times until an adequate or optimized repositioning of the leaflets
is
obtained. The fastener 332 can be driven into the retaining ring in a variety
of
ways. In the illustrated embodiment, a cam device 342 is slidably mounted
behind an inclined surface 344 on the rear of the fastener 326. By drawing the
cam actuator 342 downwardly using draw cord 348, the rivet can be driven
through the valve leaflets and into the retaining ring 330, as illustrated in
Fig. 64.
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In addition to rivets, snaps, pins and the like, coils may be used in a
similar manner to fix valve leaflets in a desirable arrangement, as shown in
Fig. 65A. Coils 900 may be comprised of a superelastic material and pre-shaped
in a coil configuration for engagement with the leaflets. The coil 900 may be
advanced from an introducer sheath 902 to deploy the coil 900 in an
orientation
that will approximate the leaflets in compression. Alternatively, the coil 900
may
be comprised of a heat or current activated shape memory material As depicted
in Fig. 65B, the coil 900 may be straightened in its initial configuration for
ease of
piercing and advancing through the leaflets LF. When positioned, the material
may be activated by heat or current to assume a shape memory coil
configuration corresponding with Fig. 65A. Again, the coils may be oriented to
approximate the leaflets in compression. To achieve maximum leaflet
compression at the coaptation points, a super elastic or shape memory coil 900
may be delivered in a manner that places the coil in an inverted orientation
across the leaflets, as illustrated in Fig. 65C. This may be accomplished with
the
use of a specialized delivery system 904. When released from the delivery
system 904, the distal end 905 of the coil produces a compressive force as the
coil attempts to achieve a non-inverted orientation.
As a further alternative, a cinch-type fastener 360 may be positioned in a
loop through opposed valve leaflets LF, as shown in Fig. 66. The fastener 360
could be advanced from either a retrograde or antegrade direction, but the
antegrade direction is illustrated for convenience. A positioning catheter 362
can
be introduced through a guide catheter 14 which has been previously positioned
by any of the techniques described above. After advancing the cinch-type
fastener 360 through the leaflets, for example by pushing a pre-shaped
fastener
360 through the leaflets so that it returns to the distal tip of the placement
catheter 360, a fastening collar 364 may then be advanced to tighten the
fastener
loop 360 until the leaflets are positioned in a desired fashion.
Alternatively, the
fastener 360 may be twisted to constrict the open loop. Typically, the
fastener
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360 has chevrons or other one-way surface features so that the locking column
may be advanced and will remain in place without loosening over time, or in
the
case of twisting, untwisting over time. The fastener 360 is then released and,
if
desired, additional fasteners positioned in a like manner. The fastening
collar
364 may alternatively be used to secure the sutures shown previously in Fig.
49.
The collar 364 may be crimped onto the sutures 202 or locked in place by the
use of a combination of one-way surface features on the collar 364 and sutures
202.
Further, a variety of penetrating and non-penetrating clips, barbs,
grappling hooks, and the like, may be used to fasten valve leaflets in a
desired
configuration. As previously described as a means to grasp the free ends of
the
valve leaflets in a pinching manner, a pair of flat coils may also be used as
a
fixation device. As previously shown and described in relation to Fig. 46A,
the
coils 770 may be linked together with opposing curvature by a clip 772. When
inserted as shown in Fig. 46B, the coils 770 may be permanently joined in this
orientation and may remain as a permanent implant. Alternatively, the coils
910
may pierce the leaflets LF to hold them in place as shown in Figs. 66A and
66B.
During placement, the coil 910 may be inserted through a delivery catheter 911
in a straight configuration and pierce the leaflets LF in this form, allowing
the free
distal end 912 of the coil 910 to curl after it has penetrated the leaflets
LF, as
shown in Fig. 66A. The proximal end may then curl after it disengages from the
delivery catheter 911 to remain as an implant as shown in Fig. 66B.
Likewise, a variety of barb-like structures may be used in a similar fashion
to fasten valve leaflets in a desired configuration. Referring to Fig. 67, a
shaft
920 with one or several curved barb-like distal ends 922 may be positioned so
that the distal ends partially or fully penetrate each leaflet LF to be fixed.
The
shaft 920 may be a shape memory or super elastic wire. By activating the shaft
920 with heat or current, in the case of a shape memory material, or allowing
the
shaft 920 to assume its pre-configured shape, in the case of a super elastic
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material, several barbs 922 may be approximated to coapt the leaflets in the
desired position. On the other hand, several discontinuous barbs 922 may be
tensioned and coapted using a crimping or coupling and trimming system.
Similarly, as shown in Fig. 68, a shaft 924 with expanding barb-like distal
ends
926 may be positioned so that the distal ends 926 penetrate each leaflet LF to
be
fixed. Here, however, the distal ends 926 may be comprised of one or more
struts 927 which expand to further prevent retraction of the shaft 924. Such
expansion may be achieved by activation of the shaft 924 with heat or current
or
allowing the device to assume its pre-configured shape. In addition to end 926
expansion, the shaft 924 may be approximated to coapt the leaflets or several
discontinuous shafts may be tensioned and coapted using a crimping or coupling
and trimming system.
In addition to fixation, clips may be used to draw leaflets together in a
suitable coaptation configuration. While temporarily holding two or more
leaflets
in a desired configuration, such as with grasping tools, a clip may be
deployed to
maintain the desired position or to further manipulate the leaflets. For
example, a
clip 940 may be mounted on a delivery catheter or interventional tool 942, as
shown in Fig. 69A. It may then be positioned in a desired location to hold the
leaflets LF, as shown in Fig. 69B. In the deployed and activated state,
depicted
in Fig. 69C, the clip 940 may tend to pinch inwardly, pulling the leaflets
together,
as indicated by arrows 944. This may be achieved by activation of super
elastic
or shape memory material. Alternatively, referring to Figs. 70A and 70B, the
clip
945 may pinch inwardly, indicated by arrows 944, by manual crimping of the
spine 946 or interlocking of the piercing legs 948. When positioned
appropriately
between the valve leaflets LF, as shown in Fig. 70B, the leaflets may be drawn
together by crimping the spine 946 of the clip 945 with the use of a removable
actuator 950. As the actuator 950 passes over the spine 946, the spine 946 may
be plastically deformed to a new configuration. Or, as the actuator 950 passes
over the spine 946, the proximal ends of the piercing legs 948 may become
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interlocked. In either case, inward movement of the clip 945 may be controlled
by passing the actuator 950 only over portions of the spine 946 in which such
pinching is desired. Therefore, a single clip may provide variable inward
forces.
Inward forces may also be applied by components of an interventional
tool, such as a by graspers. Graspers, as previously described, are devices
which grasp and hold tissues (such as coapting valve leaflets) for appropriate
modification, such as fixation. Thus, graspers are most likely in place while
a
fixation device is deployed and positioned. Referring to Fig. 71, an
embodiment
of graspers 960 is shown holding the leaflets LF on opposite sides of a
deployed
clip 962. Inward force may be applied to the clip 962 by moving or applying
force
to the graspers 960 in an inward direction, as depicted by arrows. In a
further
embodiment, the graspers may serve as a grasping device and as an
implantable fixation device. Referring to Fig. 72A, an embodiment of graspers
960 is shown coapting and holding the leaflets LF together. The graspers 960
may then be joined by a coupling device 964 and detached for implantation, as
shown in Fig. 72B.
Because of the fragility of the tissue in the valve leaflets, it will
sometimes
be preferred to utilize methods or devices which do not completely pierce or
penetrate the tissue. For example, leaflets may be fused together in a desired
coaptation position by applying laser, RF, microwave or ultrasonic energy at
specified coaptation points. In addition or alternatively, external clips
which are
partially penetrating or non-penetrating may be used. A variety of deformable
and elastic clips can be utilized, and clips will usually be deployed in a
retrograde
fashion so that an opening in the clip can be placed over the undersides of
the
adjacent valve leaflets.
A preferred clip-applying catheter 380 in is depicted in Figs. 73A, 73B, and
73C. The catheter 380 has a three-jaw clip-applying device 382 at its distal
end.
The three-jaw structure allows the clip-applier to be used as a three-jaw
grasping
device before final deployment of the clip. Such grasping has been described
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earlier with reference to Figs. 42A, 42B, and 43 above. A center jaw 384 of
the
device has a tubular structure and allows the catheter to be introduced over a
guidewire 386, where the guidewire may be placed through the atrioventricular
valve prior to catheter positioning. A clip 388 has a V-shaped structure and
is
normally closed so that a force is required to open the distal ends of the
clip.
Jaws 390 and 392 hold the clip and can open the clip by selectively opening
either jaw, with jaw 392 shown in open in broken line in Fig. 73A. Thus, jaw
392
may be opened first to capture a free end of a first valve leaflet. With the
catheter 380 thus attached to just the first valve leaflet, the catheter can
be
repositioned so that the other jaw 390 can be opened and used to capture the
second valve leaflet. After the valve leaflets are captured and held in a
proper
orientation, valve improvement can be confirmed by visual observation. If
improvement is sufficient, the clip can be detached from the catheter and left
in
place, as shown in Fig. 74.
B. Shortening of the Chordae
In addition to suturing, fastening, and otherwise physically attaching
portions of the valve leaflets and/or chordae together, valve leaflet closure
can be
improved by shrinking portions of either or both of the chordae attached to
the
two valve leaflets. An exemplary catheter 400 having an energy-applying coil
402 at its distal end is shown in Fig. 75. Such energy may be in the form of
radiofrequency (RF), microwave, ultrasound, laser, heat or current. The
catheter
400 may be deployed in either an antegrade or retrograde direction, with
retrograde generally being preferred to facilitate access to the chordae. One
or
more chordae CT are captured within the coil and RF energy, for example,
applied from a conventional power supply. Application of the RF energy to the
chordae, which are composed of collagen and other normal tissue constituents,
over a length L will cause shrinkage of the tissue to a length which is
shorter than
the original length L. Similarly, such application of energy to the chordae
may
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also be achieved with the use of an energy applying chordal snare or similar
device. By applying such shortening of the chordae, valve conditions, such as
prolapsed valves can be effectively treated.
In addition to the use of energy for shortening chordae, the chordae can
be plicated using mechanical plication devices 420, as illustrated in Fig. 76.
Each of the devices 420 comprise a cap piece 422 and a receptacle 424. A
receptacle has a channel 426 which receives a pin 428 on the cap piece 422.
There is sufficient clearance between the pin 428 and channel 426 so that a
portion of the chordae CT can be captured and folded therein by placing the
cap
into the receptacle. Each plication device 420 will thus shorten a portion of
the
chordae by a predetermined amount. Multiple devices can be used to achieve a
desired overall shortening of the chordae. The devices can be placed using jaw-
type devices and shortening can be visually observed by any of the techniques
described above. Alternatively, chordae may be mechanically plicated with the
use of suture loops. Referring to Fig. 77A, a suture 980 may penetrate the
chordae CT at a first location 982 and then penetrate the chordae CT again at
a
second location 984 forming a loop. By pulling closed the loop, as shown in
Fig. 77B, the effective length of the chordae CT is reduced. The suture loop
may
then be fixed and trimmed for implantation. This may be repeated along a
chordae to form multiple individual or continuous loops, and/or it may be
repeated on along more than one chordae. Similarly, such plication may also be
achieved with the use of a shape memory or super elastic wire coil which may
penetrate a chordae at one or more points and draw the tissue together upon
activation.
C. Annuloplasty
The intravascular approaches described herein can also be used to place
annuloplasty devices, such as supporting rings and other devices, around the
atrioventricular valve annulus, including the mitral valve annulus AN (shown
in
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Figure 1). Such annuloplasty devices can provide support which is analogous to
that provided by annuloplasty rings implanted in open surgical procedures.
As mentioned, annuloplasty device can be positioned on either the atrial
side or the ventricular side of the annulus. An advantage to positioning the
annuloplasty device on the ventricular side of the annulus is that the device
can
be positioned within an annular gutter G that is located immediately adjacent
the
ventricular side of the mitral valve MV. The gutter G is shown in the cutaway
representation of the left ventricle LV in Fig. 91. As mentioned, the gutter G
has
a concave shape, which provides a geometrically-supportive location in which
the
annuloplasty device can be securely nested during and after deployment of the
device. The rounded, concave shape of the gutter G provides an increased
amount of contact area between the wall of the left ventricle and an
annuloplasty
device positioned in the gutter.
The annuloplasty device can have a variety of configurations. For
example, with reference to Figs. 92A and 92B, the annuloplasty device 1090 can
be shaped as a ring (Figure 92A) or as a partial ring (Figure 92B). The
annuloplasty device 1090 can be equipped with any of a variety of securing or
retaining structures for securing the device to the heart, including hooks,
barbs,
prongs, adhesive fasteners, bendable legs, etc. In addition, secondary
attachment devices or materials can be coupled to the annuloplasty device
1090,
such as, for example, staples or adhesive, for permanently or temporarily
securing the device to the annulus.
Fig. 78 shows another exemplary annuloplasty device comprised of an
annuloplasty ring 500. The annuloplasty ring 500 includes an outer ring having
radially-extending spokes 504, which can be used to open the outer ring. The
annuloplasty ring can be deployed using a catheter 502 positioned through a
guide catheter 14, as described more fully below. The ring can be secured in
place using sutures, staples, tissue adhesives, or other conventional
techniques.
The catheter 502 may then be removed, together with the deployment spokes
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504, leaving the ring permanently in place. One or more of the spokes can be
attached to one or more clips that coapt the valve flaps. The spokes can be
stiff
or the spokes can be sutures or other flexible material to allow free or
limited
movement of the clips. Alternatively, rigid or flexible members in the form of
sutures or pins/posts could extend upwardly from the annuloplasty device and
penetrate through the annulus tissue to the left atrium where members fasten
to
the atrial side of the clip in tension. This could help to anchor the
annuloplasty
device in place and could partially or totally immobilize the clip, should
that be
desirable.
Magnets can also be used to secure the annuloplasty device 1090 to the
heart. This is described in more detail with reference to Fig. 93, which shows
the
annuloplasty device positioned in the gutter G. A pair of magnets 9310a and
9310b sandwich at least a portion of the annuloplasty device therebetween. The
magnet 9310a is located on a ventricular side of the mitral valve and the
magnet
9310b is located on the atrial side of the mitral valve. The magnets are of
opposite polarity such that they exert an attractive force on one another to
force
the device against the wall of the gutter G and retain the annuloplasty device
in
the gutter G. Alternately, the magnet 9310a can be replaced with magnetic
material that is integrally formed within the annuloplasty device. The atrial
magnet 9310b can be left in place permanently or it can be removed once
annuloplasty device is permanently secured either through fixation devices of
through tissue growth.
In an exemplary embodiment, the annuloplasty device is configured to be-
reshaped after placement in the annulus. For example, the annuloplasty device
can be malleable such that it can be reformed into a desired shape after
placement of the device by using an endovascular grasping/shaping tool. In
another embodiment, a pull wire spans the circumference of the device. The
pull
wire has a grasping means, such as a loop, handle, snare, etc. After the
annuloplasty device has been deployed, the end of the pull wire is grasped and
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pulled by a catheter so as to cause the wire to constrict the device into a
smaller
diameter or to re-shape the device in a predetermined manner.
The pull wire can alternatively extend from the annuloplasty device to an
extra-cardiac location, either in the chest cavity or in a peripheral vessel
for later
access. The pull wire can be left in a subcutaneous location like a pacing
lead to
facilitate easy access. The pull wire and/or the annuloplasty device can be
coated with agents to prevent endothelialization, tissue encapsulation, and
infection.
In another approach, the annuloplasty device is formed at least partially of
a thermal shape memory material that changes shape upon heating. A source of
heat, such as an electrical lead through which current could be delivered, can
be
coupled to the annuloplasty device at a desired time to cause the device to
change shape. Alternatively, the annuloplasty device could have a mechanism
that is remotely controllable (from outside the body) so that it can be
transitioned
to the desired shape at any time during or after the procedure without further
intervention. For example, the device could have magnetic components to allow
the shape to be controlled via MRI steering technology. Other remotely
controllable mechanisms are also possible.
In another approach of a re-shapeable annuloplasty device, the device
has one or more articulating joints with one-way locking or ratchet mechanisms
in each joint that allow the device to be shaped (e.g. by pulling a wire
attached to
one end) from straight into a curved or bent shape. The annuloplasty device
can
then be locked into the re-shaped configuration with any desired degree of
curvature or angle.
The annuloplasty device can be resiliently flexible such that it can be
compressed into a state of reduced size that would fit through the lumen of a
guide or delivery catheter. In the reduced-size state, the annuloplasty device
can
comprise a flattened ring in a straightened configuration. When released from
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the guide catheter, the annuloplasty device resiliently returns to a
predetermined
shape, such as the ring or partial ring shown in Figs. 92A and 92B. Thus, an
elastic annuloplasty ring can be delivered through the guide catheter in a
collapsed fashion, deployed to open over the annulus, and then stitched or
stapled in place using appropriate catheters.
Rather than being comprised of a single ring or partial ring structure, the
annuloplasty device can comprise of a plurality of structures that
collectively
re-shape the annulus when positioned therein. For example, a plurality of
attachment members, such as staples or clips, can be positioned in an annular
formation around the entire circumference of the annulus or along a portion of
the
annulus. Each attachment member is attached to the annulus in such a manner
that it re-shapes a local portion of the tissue. The plurality of attachment
members collectively re-shape a global area of the annulus.
The plurality of anchors approach is shown in Fig. 81, which shows a
plurality of anchors comprised of as staples 540 about the annulus of the
mitral
valve, such as in the gutter described above. A suture 542 or other filament
can
then be placed through the anchors 540 and tightened in a "purse string"
fashion.
The suture filament can then be tied off to maintain the desired tightening
and
enforcement of the valve annulus.
As yet a further alternative, the valve annulus can be plicated by
positioning a plurality of staples about the annulus, as shown in Fig. 82.
Here,
each staple 560 plicates or shortens a small peripheral segment of the
annulus.
A staple applying catheter 562 may have the same general structures described
above in connection with Figs. 61A and 61 B.
In an embodiment, a period of time elapses after placement of the
annuloplasty device in the annulus. The annuloplasty device is then re-shaped
after passage of the period of time. During the time period, the tissue around
the
annulus forms scar tissue where the annuloplasty device has been attached. In
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this regard, the annuloplasty device can be covered with a suitable material,
such
as Dacron, that promotes tissue healing and growth. The scar tissue
strengthens
the attachment between the tissue and the annuloplasty device and reduces the
likelihood of injury to the tissue or detachment from the tissue during
reshaping.
The amount of the time period can vary. In one embodiment, the annuloplasty
device is deployed in the annulus and the annuloplasty device is re-shaped
after
a time period of four to twenty four weeks has elapsed.
The annuloplasty device can be delivered to the annulus in a variety of
manners and using various devices. The annuloplasty device can be delivered
using an antegrade approach or a retrograde approach. As discussed above
with reference to Fig. 9, in the retrograde approach, the annuloplasty device
is
introduced by deploying a delivery device through distal arterial vasculature
and
over the aortic arch and into the left ventricle through the aortic valve. As
discussed above, a guidewire 42 can be used to provide initial access to the
left
ventricle. A guide catheter 40 is then tracked over the guidewire 42 to the
left
ventricle.
An interior lumen of the guide catheter 40 provides subsequent access to
the left ventricle for a delivery catheter that holds the annuloplasty device
at its
tip. When entering through the left ventricle, the delivery catheter may be
required to curve or turn such that it approaches the gutter of the mitral
valve
annulus from below. In this regard, the delivery catheter may have a
predetermined shape that facilitates such an approach. The delivery catheter
can also have a deflectable distal tip that can be deflected (such as via a
pull
wire) so that the distal tip angles outwardly and upwardly toward the gutter
region
of the annulus. The delivery catheter then deploys the annuloplasty device in
the
gutter region and the annuloplasty device is secured in place. A second
catheter
can also be deployed to the gutter to secure the annuloplasty in place while
the
delivery catheter temporarily holds the annuloplasty device in position. It
should
be appreciated that the delivery devices and methods for approaching the
mitral
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valve annulus described above can be used in delivering the annuloplasty
device.
In the antegrade approach, the device is introduced through the inferior
vena cava IVC or superior vena cava SVC into the right atrium RA, as described
above with reference to Figs. 7 and 8. The interatrial septum lAS is then
penetrated such as using a catheter 10 having a needle 12, as shown in Figure
7. As shown in Fig. 8, access through the interatrial septum IAS can be
maintained by the placement of a guide catheter 14, typically over a guidewire
16. The guide catheter 14 permits introduction to the left atrium LA of a
delivery
device having the annuloplasty device at a distal end. The delivery device is
passed downward through the mitral valve MV such that it approaches the gutter
region from below the mitral valve MV. As discussed above, the delivery
catheter can be preshaped to facilitate such an approach or it can be equipped
with a mechanism that enables the distal region of the delivery catheter to be
deflected toward the gutter region.
Alternatively, an annuloplasty ring 520 can be delivered on a balloon
catheter 522 as shown in Figs. 79 and 80. The ring 520 can be formed from a
deformable material, and the balloon 520 inflated within the valve annulus to
expand and deploy the ring, as shown in Fig. 80. The balloon catheter may be
placed directly over a guidewire 524, but will more usually be positioned
using a
combination of a guide catheter and guidewire. Once the ring 520 is deployed,
it
can be sutured, stapled, glued, or otherwise affixed around the valve annulus.
In an alternative approach that can be used in place of or in combination
with deployment of the annuloplasty device, annulus remodeling is accomplished
by applying RF energy to the gutter region of the annulus to shrink or
otherwise
change the annulus shape. A catheter having one or more RF electrodes at a
distal tip is inserted through the guide catheter to the gutter region of the
annulus.
The RF electrodes are energized to deliver energy delivered to the annulus or
to
the surrounding tissue for remodeling. The catheter can include a suction port
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for applying suction to the heart tissue near the annulus to stabilize the
device.
Again the catheter would be steerable by means of pull wires or the like.
Placement of the annuloplasty device can be combined with any of the
other procedures described herein. For example, chordal grasping and/or valve
leaflet grasping can be employed in combination with deployment of the
annuloplasty device. The annuloplasty device delivery catheter can include
grasping arms at a distal end to grasp the valve leaflets during delivery of
the
annuloplasty device.
Placement of the annuloplasty device can also be combined with
temporary or permanent tissue modifications, such as fixation of the valve
leaflets or shortening of the chordae, which tissue modifications are
described in
detail above. With respect to valve leaflet fixation, the delivery catheter
that is
used to deliver the annuloplasty device can be combined with a suturing tool
200
(shown in Fig. 49) or variations of the suturing tool described herein. The
staple
applying catheter 300 (shown in Figs. 61 a and 61 b) can also be used to
deliver
the annuloplasty device. The stapling mechanism catheter 320 (shown in
Fig. 63) can be equipped with a separate lumen for delivery of the
annuloplasty
device. Pursuant to a method of delivery, one of the catheters described
herein
is used to apply a clip or staple to the leaflets or to suture the leaflets.
Before or
after coaptation of the leaflets, the annuloplasty device is deployed in the
gutter
G of the mitral valve annulus AN. It should be appreciated that any of the
delivery or interventional devices described herein can be modified for use
with
the annuloplasty device.
D. Annuloplasty via the Coronary Sinus
Fig. 94 is a cross-sectional view of the heart showing the mitral valve MV,
valve leaflets LF, annulus AN, and coronary sinus CS. The coronary sinus CS is
positioned adjacent the mitral valve MV. Because the coronary sinus
substantially encircles the mitral valve annulus AN, a re-shaping of the
coronary
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sinus CS will results in a re-shaping of the annulus AN. A device of
predetermined shape can be implanted into the coronary sinus CS and allowed
to heal in place so as to form scar tissue adjacent the device. The shape of
the
device is then subsequently changed to also re-shape the coronary sinus CAS
and the adjacent annulus AN in a desired manner. The scar tissue strengthens
the tissue to provide a strong attachment to the device and also reduce the
risk
of injury.
X. DEVICE EMBODIMENTS
The following three device embodiments depict complete device designs
utilizing a variety of the specific components described above and/or new
component designs to accomplish similar objectives.
A. Atrial Device
Referring to Fig. 83, the atrial device 1000 is comprised of a catheter shaft
1002 having a distal end 1004 and a proximal end 1006. The catheter shaft
1002 is comprised of, among others, a conduit 1008, a coaxial outer sheath
1010, and a central guidewire lumen 1011. Toward the distal end 1004, a pair
of
stabilizers 1012 having a single-hump shape (previously illustrated in Fig. 31
D)
are fixedly mounted on the outer sheath 1010 at their proximal end 1014 and
fixedly attached or hinged to extenders 1016 at their distal end 1018. The
stabilizers 1012 are shown in an outwardly bowed position, however they may be
inwardly collapsed by either extending the extenders 1016 or retracting the
outer
sheath 1010. Bowing may be achieved by the reverse process.
Referring to Fig. 84, the atrial device 1000 may be used with a typical
antegrade approach to the mitral valve MV. As previously described and
depicted in Figs. 7 and 8, such an antegrade approach may involve penetrating
the interatrial septum IAS and maintaining such access with a guide catheter
14.
The guide catheter 14 permits introduction of the atrial device 1000 to the
left
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atrium LA and mitral valve MV. To allow passage of the device 1000 through the
guide catheter 14, the stabilizers 1012 must be in a collapsed position as
shown.
In addition, graspers, described below, may be fully retracted to avoid damage
to
cardiac structures. Thus, they are not visible in Fig. 84.
Referring to Fig. 85, the atrial device 1000 may be stabilized against the
mitral valve MV. The stabilizers 1012 may be inserted through the mitral valve
MV and may be aligned with the line of coaptation C between the valve leaflets
LF1, LF2. To minimize mitral valve regurgitation (MVR) due to insertion of the
device 1000, the stabilizers 1012 may be located approximately 120 degrees
apart. This angle may be fixed or adjustably variable. The single-humped shape
of the stabilizers 1012 may allow the inferior portion 1030 to pass within the
valve
and apply radial pressure to the commissures CM and the superior portion 1032
(or hump) to rest upon and apply axial pressure to the commissures CM.
Referring again to Fig. 83, a pair of graspers, comprised of grasping
sheaths 1020 and three opposing prongs 1021 configured to partially or fully
penetrate or pierce, are shown extended from the conduit 1008 in the plane
bisecting the angle of the stabilizers 1012 (i.e. approaches the middle of the
leaflets). This angle may be fixed or variable. When not in use, however, the
graspers may be fully retracted within the conduit 1008. Tension from lateral
steering wires 1022 cause the graspers to deflect away from each other and
approximate the most desirable angle for grasping. Amount of deflection may be
controlled from the proximal end of the device by the steering wires 1022.
When
the graspers are positioned in a desired location as shown in Fig. 85, the
prongs
1021 may be deployed and opened by either retraction of the grasping sheath
1020 or advancement of the prongs 1021 beyond the grasping sheath 1020.
Retraction of the sheath 1020 does not significantly affect the position of
the
graspers, thus enabling the user to contact the valve leaflets LF1, LF2 with
the
prongs 1021 housed within the sheath 1020 and then to initiate grasping the
leaflets at the contacted location by retracting the grasping sheaths 1020.
The
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opposing prongs 1021 may be closed to grasp (pinch, partially penetrate or
pierce) the leaflet tissue by advancing the grasping sheaths 1020 or
retracting
the prongs 1021 within the sheaths 1020.
After both leaflets have been grasped, tension in the steering wires 1022
is released and the conduit 1008 is advanced over the grasping sheaths 1020.
Such advancement draws the sheaths 1020, and grasped leaflets, together for
coaptation. After coaptation, the mitral valve regurgitation is evaluated to
determine if the locations which are grasped are appropriate for fixation. If
the
grasping points are not appropriate, the leaflets may be released and
regrasped
individually or simultaneously by the above described methods. If the grasping
points are appropriate, the preferred embodiment allows for exchange of the
guidewire, located in the guidewire lumen 1011, for a fixation device. The
fixation device may use, for example, staples, sutures, clips, rivets, coils,
fusing
devices, zippers, snares, clamps, hooks, chordal fixation or shortening
devices to
repair the mitral valve regurgitation. Specifically, the fixation device may
be the
hollow suturing coil 1300 shown previously in Figs. 49A-C. As shown in
Fig. 84A, the hollow suturing coil 1300 containing suture 1302 (not shown) may
be deployed through the guidewire lumen 1011 in a coiled configuration. The
coil
1300 may expand or change shape once it is deployed from the lumen 1011,
providing the coil 1300 is comprised of a suitable shape memory or
superelastic
material. Similarly, as shown in Fig. 84B, the suturing coil 1300 may be
deployed
through the guidewire lumen 1011 in a straightened configuration such that it
coils and/or expands or changes shape once it is deployed from the lumen 1011.
The above described components may be manipulated and controlled by
a handle 1026 connected to the proximal end 1006 of the catheter shaft 1002,
as
shown in Fig. 83. The handle 1026 permits independent control of the
components, including but not limited to retraction and extension of extenders
1016, deployment of stabilizers 1012, adjustment and locking of outer sheath
1010, translation and deflection of grasping sheaths 1020, stopping and
locking
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of grasping sheaths 1020 and axial sliding of the conduit 1008. In addition,
the
device may be readily adapted to approach the mitral valve trans-atrially for
a
minimally invasive surgical (MIS) procedure, with either beating or stopped
heart.
B. Atrial-Ventricular Device
Referring to Fig. 86, the atrial-ventricular device 1100 is comprised of a
catheter shaft 1102 having a distal end 1104 and a proximal end 1106. The
catheter shaft 1102 is comprised of, among others, a conduit 1108, a coaxial
outer sheath 1110, a central lumen 1111 through which a double-jaw grasper
1113 may be inserted, and a central guidewire lumen 1105. Toward the distal
end 1104, a pair of stabilizers 1112 having a triangular shape (previously
illustrated in Fig. 31A) are fixedly mounted on the outer sheath 1110 at their
proximal end 1114 and fixedly attached to extenders 1116 at their distal end
1118. The stabilizers 1112 are shown in an outwardly bowed position, however
they may be inwardly collapsed by either extending the extenders 1116 or
retracting the outer sheath 1110. Bowing may be achieved by the reverse
process. The double-jaw grasper 1113 is comprised of two articulating jaw arms
1120 which may be opened and closed against the central shaft 1122
(movement depicted by arrows) either independently or in tandem. The grasper
1113 is shown in the open position in Fig. 86. The surfaces of the jaw arms
1120
and central shaft 1122 may be toothed, as shown, or may have differing surface
textures for varying degrees of friction.
Referring to Figs. 87A-C, the atrial-ventricular device 1100 may be used
with a typical antegrade approach to the mitral valve MV, as previously
described
and depicted in Figs. 7 and 8. However, the double-jaw grasper 1113 extends
through the valve such that the leaflets L1, L2 are grasped from below. Thus,
the
device 1100 is termed "atrial-ventricular."
Referring to Fig. 87A, the atrial device 1100 may be stabilized against the
mitral valve MV. The stabilizers 1112 may be positioned on the superior
surface
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of the valve leaflets LFI, LF2 at a 90 degree angle to the iine of coaptation.
The
grasper 1113 may be advanced in its closed position from the conduit 1108
between the leaflets LF1, LF2 until the jaw arms 1120 are fully below the
leaflets
in the ventricle. At this point, the grasper 1113 may be opened and retracted
so
that the jaw arms 1120 engage the inferior surface of the leaflets LFI, LF2.
In
this manner, the leaflets are secured between the stabilizers 1112 and the jaw
arms 1120. This action allows for leaflets of many different shapes and
orientations to be secured. Cardiomyopathic valves are often enlarged and
distorted so that they coapt irregularly. Such irregularity creates difficulty
in
mechanically coapting such valves for tissue modification. The action of the
grasper 1113 overcomes much of these difficulties.
Referring to Fig. 87B, the grasper 1113 will gradually close, drawing the
leaflets LFI, LF2 together while maintaining a secure hold on the leaflets
between the jaw arms 1120 and the stabilizers 1112. This may be accomplished
by number of methods. For example, the stabilizers 1112 may be gradually
collapsed by either extending the extenders 1116 or retracting the outer
sheath
1110. As the stabilizers 1112 collapse, the jaw arms 1120 may collapse due to
spring loading to gradually close the grasper 1113. Alternatively, the jaw
arms
1120 may be actuated to close against the central shaft 1122 applying force to
the stabilizers 1112 causing them to collapse. In either case, such action
allows
the stabilizers 1112 to simultaneously vertically retract and withdraw from
the
leaflets as the leaflets are clamped between the jaw arms 1120 and the central
shaft 1122. In this manner, the leaflets are effectively "transferred" to the
grasper
1113. Referring to Fig. 87C, once the collapsed stabilizers 1112 are
completely
withdrawn, the leaflets LFI, LF2 are held in vertical opposition by the
grasper
1113 in a more natural coaptation geometry. At this point the leaflets may be
adjusted and fixated. Fixation may be achieved with an external element or the
grasper 1113 may be left in place as a fixation device.
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The above described components may be manipulated and controlled by
a handle 1126 connected to the proximal end 1106 of the catheter shaft 1102,
as
shown in Fig. 86. The handle 1026 permits independent control of the
components described above.
C. Ventricular Device
Referring to Fig. 88, the ventricular device 1200 is comprised of a catheter
shaft 1202 having a distal end 1204 and a proximal end 1206. The distal end
1204 is comprised of a joining coil 1208, an upper jaw 1210, a lower jaw 1212,
an actuator 1214 and a central lumen 1216 through which a guidewire 1218 or
other wires may be inserted. The upper jaw 1210 may open and close (depicted
by arrows) against the lower jaw 1212 by action of the actuator 1214. The
upper
jaw 1210 is shown in the open position. These components may be manipulated
and controlled by a handle 1226 connected to the proximal end 1206 of the
catheter shaft 1202 as shown.
Referring to Figs. 89, the ventricular device 1200 may be used with a
typical retrograde approach to the mitral valve MV, as previously described
and
depicted in Fig. 9. Here the mitral valve MV may be accessed by an approach
from the aortic arch AA across the aortic valve AV, and into the left
ventricle LV
below the mitral valve MV. Such access may be maintained with a guide
catheter 40 through which the ventricular device 1200 may be introduced. The
ventricular device 1200 may be inserted through the guide catheter 40 with the
upper jaw 1210 in the closed position. After it exits the guide catheter 40
just
below the aortic valve AV, the device 1200 may be advanced toward the mitral
valve MV. The catheter shaft 1202 may be pre-shaped to provide favorable
curvature in positioning the distal end 1204 beneath the valve leaflets ALF,
PLF.
Additionally, two mandrels with favorable shapes may be advanced into a lumen
in the catheter shaft 1202. By changing the location of the mandrels with
respect
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to each other and to the catheter shaft 1202, the general curvature of the
shaft
1202 may be altered in-situ.
It is desired to position the distal end 1204 of the device 1200 beneath the
mitral valve leaflets ALF, PLF with the upper jaw 1210 in the open
configuration.
The lower jaw 1212 is to be proximal to the anterior leaflet ALF and the upper
jaw
1210 is to be distal of the posterior leaflet PLF, as shown in Fig. 89, such
that the
leaflets may be secured between the jaws 1210, 1212. To achieve such
positioning, the device 1200 may be required to flex at an extreme angle in
the
region of the joining coil 1208. Therefore, the joining coil 1208 is designed
to
provide such flexibility.
To aid in positioning the device 1200, a balloon wire 1250 may be used.
The balloon wire 1250 may first be inserted through the aortic valve AV,
advanced down to the apex of the ventricle and then back upwards towards the
mitral valve MV behind the posterior leaflet PLF. Once positioned, the balloon
1252 may be inflated to assist in holding the position stationary. A cuff wire
1260
may then be inserted through the aortic valve AV. The cuff wire 1260 may track
along the balloon wire 1250 by means of a locking ring 1262. The cuff wire
1260
may track down to the apex of the ventricle and then back upwards toward the
mitral valve MV. Once the cuff wire 1260 is advanced to a desirable position,
the
locking ring 1262 may be actuated to lock the cuff wire 1260 to the balloon
wire
1250. A typical means of actuation is by inflation of the locking ring. 1262.
The
ventricular device 1200 may then be tracked over the cuff wire 1260 to the
desired position, as shown in Fig. 89. The balloon, or balloon wire 1250, may
also be used to walk or urge the posterior leaflet towards the center of the
valve
to facilitate grasping.
Once positioned, the upper jaw 1210 may be closed against the lower jaw
1212 such that the leaflets are grasped between them. It is often desirable to
adjust or manipulate the leaflets once they are grasped. Manipulation should
occur only in a superior/inferior (up/down) motion in order to bring the
leaflets to
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a final position where regurgitation is minimized. The lower jaw 1212 may be
fitted with a travel mechanism for extending or retracting the jaw 1212. This
would move one leaflet up or down with respect to the other leaflet. Once the
leaflets are sufficiently adjusted, fixation may occur in any manner
previously
described. In a preferred embodiment, fixation may achieved through the lower
jaw 1212, as depicted in Figs. 90A and 90B. As shown in Fig. 90A, a cutout
1270 may be present in the lower jaw 1212 accessing a lumen 1272 which
extends through the catheter shaft 1202 and lower jaw 1212; such a lumen may
also serve as the guidewire lumen 1216. When the upper jaw 1210 is closed
against the lower jaw 1212, the valve leaflets LF may be captured between the
jaws. As shown a side-view, Fig. 90B, the captured leaflets LF may protrude
into
through the cutout 1270 into the lumen 1272. A fixation device 1274 may then
be inserted through the lumen 1272 (in the direction of the arrow) and may
affix
the leaflets LF together. It may be appreciated that such a method of fixation
may be used in a number of devices involving jaw-type graspers, such as the
atrial ventricular device 1100 depicted in Fig. 86.
Although the forgoing devices and methods have been described in some
detail by way of illustration and example, for purposes of clarity of
understanding,
it will be obvious that various alternatives, modifications and equivalents
may be
used and the above description should not be taken as limiting in scope.
