U.S. patent application number 13/239514 was filed with the patent office on 2012-01-12 for methods and devices for tissue grasping and assessment.
This patent application is currently assigned to ABBOTT VASCULAR INC.. Invention is credited to Eric A. GOLDFARB, Jan KOMTEBEDDE, Yen C. LIAO, John P. MADDEN, Brian B. MARTIN, Ferolyn T. POWELL, Alfred H. RASCHDORF, Jaime E. SARABIA, Troy L. THORNTON, Sylvia WEN-CHIN FAN.
Application Number | 20120010461 13/239514 |
Document ID | / |
Family ID | 41569255 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120010461 |
Kind Code |
A1 |
GOLDFARB; Eric A. ; et
al. |
January 12, 2012 |
METHODS AND DEVICES FOR TISSUE GRASPING AND ASSESSMENT
Abstract
Devices, systems and methods are provided for stabilizing and
grasping tissues such as valve leaflets, assessing the grasp of
these tissues, approximating and fixating the tissues, and
assessing the fixation of the tissues to treat cardiac valve
regurgitation, particularly mitral valve regurgitation.
Inventors: |
GOLDFARB; Eric A.; (San
Francisco, CA) ; THORNTON; Troy L.; (San Francisco,
CA) ; RASCHDORF; Alfred H.; (Kings Park, NY) ;
SARABIA; Jaime E.; (Smyrna, GA) ; MADDEN; John
P.; (Palo Alto, CA) ; POWELL; Ferolyn T.; (San
Francisco, CA) ; MARTIN; Brian B.; (Boulder Creek,
CA) ; WEN-CHIN FAN; Sylvia; (San Francisco, CA)
; KOMTEBEDDE; Jan; (Menlo Park, CA) ; LIAO; Yen
C.; (San Mateo, CA) |
Assignee: |
ABBOTT VASCULAR INC.
SANTA CLARA
CA
|
Family ID: |
41569255 |
Appl. No.: |
13/239514 |
Filed: |
September 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12575100 |
Oct 7, 2009 |
8052592 |
|
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13239514 |
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11237213 |
Sep 27, 2005 |
7635329 |
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12575100 |
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60613867 |
Sep 27, 2004 |
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Current U.S.
Class: |
600/37 |
Current CPC
Class: |
A61B 2017/00243
20130101; A61B 2017/2926 20130101; A61B 2017/2931 20130101; A61B
2090/3908 20160201; A61B 2017/306 20130101; A61F 2/2466 20130101;
A61B 17/29 20130101; A61B 17/3478 20130101; A61B 2017/22098
20130101; A61B 2017/2825 20130101; A61B 2017/22088 20130101; A61B
2017/22089 20130101; A61B 17/08 20130101; A61B 17/0401 20130101;
A61B 2017/081 20130101; A61B 2090/3925 20160201; A61F 2/246
20130101 |
Class at
Publication: |
600/37 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A method of fixing a pair of valve leaflets together along their
coaptation line, the method comprising: fixing the pair of valve
leaflets together at a first location along the coaptation line
with a first fixation device; and fixing the pair of valve leaflets
together at a second location along the coaptation line with a
second fixation device, wherein the first and second locations
differ.
2. A method as in claim 1, wherein the first and second locations
are adjacent to each other.
3. A method as in claim 1, wherein the first and second locations
are approximately 1 cm apart.
4. A method as in claim 1, wherein the first and second locations
are positioned so as to provide a double orifice geometry when a
pressure gradient opens the pair of valve leaflets.
5. A method as in claim 1, wherein the first and second locations
are positioned so as to provide a triple orifice geometry when a
pressure gradient opens the pair of valve leaflets.
6. A method as in claim 1, wherein the first fixation device has a
first pair of grasping elements and a second pair of grasping
elements, and wherein fixing the pair of valve leaflets together at
the first location comprises grasping one leaflet of the pair of
valve leaflets between the first pair of grasping elements and
grasping another leaflet of the pair of valve leaflets between the
second pair of grasping elements.
7. A method as in claim 1, further comprising assessing performance
of the valve leaflets after the step of fixing the pair of valve
leaflets together at the first location to determine need for the
step of fixing the pair of valve leaflets together at the second
location.
8. A method comprising: advancing a minimally invasive device into
a chamber of a heart having a valve with valve leaflets, wherein
the chamber comprises the left atrium and the valve comprises the
mitral valve, and wherein the device comprises a stabilizer;
temporarily stabilizing the valve leaflets by reducing movement of
the valve leaflets by positioning the stabilizer against the
ventricular side of the leaflets so as to reduce flail of the
leaflets, wherein temporarily stabilizing the valve leaflets
comprises temporarily slowing the natural pace of the heart with a
pacing instrument.
9. A method as in claim 8, wherein the stabilizer comprises an
expandable member, a flap or at least one loop.
10. A method as in claim 8, wherein the device includes at least
one loop, and wherein temporarily stabilizing comprises positioning
the at least one loop against the leaflets so as to reduce movement
of the leaflets.
11. A method as in claim 10, wherein temporarily stabilizing
further comprises moving the at least one loop along the leaflets
toward the center of the valve so as to reduce movement of the
leaflets.
12. A method as in claim 8, wherein the chamber comprises a
ventricle including chordae extending from the ventricle to the
valve leaflets, and wherein temporarily stabilizing comprises
holding the chordae with the device so as to reduce movement of the
valve leaflets.
13. A method as in claim 12, wherein the device includes an
expandable member and wherein holding the chordae comprises
expanding the expandable member against the chordae.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/575,100 filed Oct. 7, 2009 which is a
divisional of U.S. patent application Ser. No. 11/237,213, now U.S.
Pat. No. 7,635,329, filed Sep. 27, 2005 which claims the benefit
and priority of U.S. Provisional Patent Application No. 60/613,867,
filed Sep. 27, 2004, the full disclosures of which are hereby
incorporated by reference.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
[0002] NOT APPLICABLE
REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM
LISTING APPENDIX SUBMITTED ON A COMPACT DISK
[0003] NOT APPLICABLE
BACKGROUND OF THE INVENTION
Field of the Invention
[0004] The present invention relates generally to medical methods,
devices, and systems. In particular, the present invention relates
to methods, devices, and systems for the endovascular, percutaneous
or minimally invasive surgical treatment of bodily tissues, such as
tissue approximation or valve repair. More particularly, the
present invention relates to repair of valves of the heart and
venous valves.
[0005] Surgical repair of bodily tissues often involves tissue
approximation and fastening of such tissues in the approximated
arrangement. When repairing valves, tissue approximation includes
coapting the leaflets of the valves in a therapeutic arrangement
which may then be maintained by fastening or fixing the leaflets.
Such coaptation can be used to treat regurgitation which most
commonly occurs in the mitral valve.
[0006] 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. Regurgitation of the valve can significantly decrease
the pumping efficiency of the heart, placing the patient at risk of
severe, progressive heart failure.
[0007] Mitral valve regurgitation can result from a number of
different mechanical defects in the mitral valve or the left
ventricular wall. The valve leaflets, the valve chordae which
connect the leaflets to the papillary muscles, the papillary
muscles or the left ventricular wall 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.
[0008] The most common treatments for mitral valve regurgitation
rely on valve replacement or repair including leaflet and annulus
remodeling, the latter 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 high mortality and morbidity.
[0009] Consequently, alternative and additional methods, devices,
and systems for performing the repair of mitral and other cardiac
valves have been developed. Such methods, devices, and systems
preferably do not require open chest access and are capable of
being performed either endovascularly, i.e., using devices which
are advanced to the heart from a point in the patient's vasculature
remote from the heart or by a minimally invasive approach. Examples
of such methods, devices and systems are provided in U.S. Pat. Nos.
6,629,534 6,752,813, and U.S. patent application Ser. Nos.
10/441,753, 10/441,531, 11/130,818, 10/441,508, 10/441,687,
10/975,555, all of which are incorporated herein by reference for
all purposes.
[0010] In some instances, however, a variety of challenges are
faced in desirably fixating the valve leaflets. For example, it is
commonly found in cases of mitral valve regurgitation that a
portion of the leaflet is moving out of phase with the other
leaflets or portions of the leaflets. This can occur due to an
elongation or disconnection of the structures (chordae tendinae)
holding the leaflets stable and in synchrony. Such a malfunction
can lead to one leaflet or portion of a leaflet to swing or "flail"
above the level of healthy coaptation, thereby allowing blood to
regurgitate into the right atrium. Such flailing provides a
challenge to the practitioner when attempting to fix the leaflets
together, particularly via an endoscopic approach. The leaflets may
be difficult to grasp, and even when grasped, the leaflets may not
be desirably grasped. For example, a leaflet may only be partially
grasped rather than having full contact with a grasping element.
This may lead to less desirable coaptation and/or eventual slippage
of the leaflet from fixation.
[0011] Therefore, devices, systems and methods are desired which
stabilize the tissue, to resist flailing and other movement, prior
to and/or during grasping of the tissue. Further, devices, systems
and methods are desired which assist in grasping the tissue, enable
more desirable coaptation of tissues, provide grasping assessment,
and enable the practitioner to determine if desirable grasping of
the tissues has occurred, particularly prior to fixation. And still
further, devices, systems and methods are desired which enable
fixation assessment, enabling the practitioner to determine if
desirable fixation of the tissues has occurred. These would be
useful for repair of tissues in the body other than leaflets and
other than heart valves. At least some of these objectives will be
met by the inventions described hereinbelow.
BRIEF SUMMARY OF THE INVENTION
[0012] The present invention provides a variety of devices, systems
and methods for stabilizing, grasping, assessing and fixating
tissues, particularly valve leaflets in the treatment of cardiac
valve regurgitation, more particularly mitral valve regurgitation.
Many of the devices, systems and methods utilize or are utilized in
conjunction with a preferred embodiment of a fixation device having
at least one proximal element and at least one distal element,
wherein the tissue is grasped therebetween. It may be appreciated,
however, that the devices, systems and methods of the present
invention may utilize any suitable device, particularly any
minimally invasive device. When treating valve leaflets, the
leaflets are typically grasped to position the fixation device
along the line of coaptation at a location which reduces
regurgitation of the valve, such as near the center of the valve
simulating a standard surgical bow-tie repair. However, more than
one fixation device may be placed, and in various arrangements, as
will be discussed in later sections.
[0013] To assist in desirable grasping of the tissue, a variety of
devices and techniques are provided to stabilize the tissue prior
to grasping. Such stabilization is aimed to assist in effectively
and efficiently grasping the tissue thereby increasing the
likelihood that the desired amount of tissue will be incorporated
into the fixation device without necessitating multiple grasps.
Further, a variety of devices and techniques are provided to
improve a grasp, such as by adjusting the position of the grasped
tissue between the proximal and distal elements. Once the tissue or
leaflets have been grasped, it is often desired to evaluate or
assess the quality of the grasp, such as the amount of purchase,
orientation of the tissues and likelihood that the fixation device
will maintain the grasp over time. Thus, a variety of devices and
techniques are provided to assess the quality of the grasp.
Further, once the tissue has been fixed by the fixation device, the
quality of the fixation of the tissue may be evaluated or assessed.
This can be achieved by evaluating the improvement in the medical
condition being treated, such as improvement in regurgitation. It
is often desired to assess the fixation prior to decoupling the
fixation device from the delivery catheter so that the fixation
device may be repositioned if the improvement is not satisfactory.
Thus, a variety of devices and techniques are provided to assess
the fixation prior to decoupling the fixation devices. Additional
devices, systems and methods are also provided.
[0014] In one aspect of the present invention, methods are provided
for assessing the grasp of one or more tissues by a minimally
invasive device. In one embodiment, the method includes advancing a
minimally invasive device having a proximal element and a distal
element into a body cavity having a tissue, grasping the tissue
between the proximal element and the distal element and assessing
the presence of the tissue in a target area between the proximal
and distal elements. Typically, the tissue comprises valve
leaflets. In some embodiments, assessing the presence comprises
observing the target area under fluoroscopy, ultrasound or
echocardiography. In such instances, the method may further
comprise enhancing the visibility of at least a portion of the
proximal element and/or the distal element. Alternatively or in
addition, the method may further comprise enhancing the visibility
of the tissue.
[0015] In a variety of embodiments, the device includes an
indicator which indicates the presence of tissue within the target
area. In such instances, the method may further comprise observing
the indicator. When the indicator changes shape and/or orientation
based on the presence of tissue within the target area, observing
the indicator may include observing the change in shape and/or
orientation.
[0016] In some embodiments, the device includes an injectable
enhanced visibility substance. In such instances, assessing the
presence of tissue in the target area may comprise observing a flow
pattern of the enhanced visibility substance. When the substance is
contained in a reservoir having ports, assessing the presence of
tissue in the target area may comprise observing the substance
flowing through ports near the target area.
[0017] In further embodiments, the method further comprising
introducing an injectable enhanced visibility substance through the
device. In such instances, assessing the presence of tissue in the
target area may comprise observing the absence of a flow pattern of
the enhanced visibility substance. In still further embodiments,
the method further includes advancing a probe into the target area.
In such instances, assessing the presence of the tissue in a target
area may comprise determining a depth of the probe advancement. In
some embodiments, the device includes a sensor which indicates the
presence of tissue within the target area, wherein the method
further comprises evaluating a signal from the sensor.
[0018] In another aspect of the present invention, methods are
provided for adjusting the tissue grasped between the proximal and
distal element. In some embodiments, the method comprises advancing
a minimally invasive device having a proximal element and a distal
element into a body cavity having a tissue, grasping the tissue
between the proximal element and the distal element, and adjusting
the tissue between the proximal element and the distal element.
Adjusting may comprise applying suction to the tissue and moving
the tissue by suction forces. When the device includes a secondary
grasper, adjusting may comprise grasping and moving the tissue with
the secondary grasper. When the device includes a rotating
component which moves the tissue between the proximal and distal
elements, adjusting may comprise rotating the rotating component.
When the proximal element is moveable relative to the distal
element, adjusting may comprise moving the proximal element
relative to the distal element. Typically, the tissue comprises
valve leaflets.
[0019] In another aspect of the present invention, methods are
provided for temporarily stabilizing valve leaflets. In some
embodiments, the method includes advancing a minimally invasive
device into a chamber of a heart having a valve with valve
leaflets, temporarily stabilizing the valve leaflets by reducing
movement of the valve leaflets. When the chamber comprises the left
atrium, the valve comprises the mitral valve, and the device
includes a stabilizer, temporarily stabilizing may comprise
positioning the stabilizer against the atrial side of the leaflets
so as to reduce flail of the leaflets. In some embodiments, the
stabilizer comprises an expandable member, a flap or at least one
loop. When the device includes at least one loop, temporarily
stabilizing may comprises positioning the at least one loop against
the leaflets so as to reduce movement of the leaflets. In some
embodiments, temporarily stabilizing further comprises moving the
at least one loop along the leaflets toward the center of the valve
so as to reduce movement of the leaflets. When the chamber
comprises a ventricle including chordae extending from the
ventricle to the valve leaflets, temporarily stabilizing may
comprise holding the chordae with the device so as to reduce
movement of the valve leaflets. When the device includes an
expandable member, holding the chordae may comprise expanding the
expandable member against the chordae. In some embodiments,
temporarily stabilizing the valve leaflets comprises temporarily
slowing the natural pace of the heart with a pacing instrument.
[0020] In a further aspect of the invention, a minimally invasive
device is provided comprising at least one proximal element and at
least one distal element configured for grasping tissue
therebetween, and an indicator which indicates a presence or
absence of tissue in a target area between the at least one
proximal and distal elements. In some embodiments, the indicator
comprises an enhanced visibility substance. For example, the
enhanced visibility substance may be disposed on or within the at
least one proximal and/or the at least one distal elements. The
device may further comprise a reservoir within which the enhanced
visibility substance is disposed. In some embodiments, the
reservoir is configured to release at least a portion of the
enhanced visibility substance due to the presence of tissue in the
target area between the at least one proximal and distal elements.
Alternatively or in addition, the reservoir may be configured to
move locations due to the presence of tissue in the target area
between the at least one proximal and distal elements. Or, the
device may further comprise a conduit through which the enhanced
visibility substance is injectable toward the target area.
[0021] In some embodiments, the indicator is configured to change
shape and/or orientation based on a presence of tissue within the
target area. For example, the indicator may be configured to extend
into the target area in the absence of tissue within the target
area and to change shape or orientation within the target area due
to the presence of tissue within the target area. In some
instances, the indicator comprises a floating block, a flap, a
reservoir, a loop, a slackline, a probe, a detectable element, or a
combination of any of these.
[0022] In other embodiments, the indicator comprises a sensor.
Examples of sensors include a conductor, a strain gauge, a
radiosensor, an optical sensor, an ultrasound sensor, a magnetic
sensor, an electrical resistance sensor, an infrared sensor, an
intravascular ultrasound sensor, a pressure sensor or a combination
of any of these. Optionally, the indicator may be configured to
contact the at least one distal element forming a closed circuit
when the tissue is absent within the target area.
[0023] In another aspect of the present invention, a minimally
invasive device is provided comprising at least one proximal
element and at least one distal element configured for grasping
tissue therebetween, and an adjustment element configured to adjust
a position of the tissue between the at least one proximal and
distal elements. In some embodiments, the adjustment element
comprises a vacuum line configured to apply suction to the tissue
to adjust the position of the tissue between the at least one
proximal and distal elements. In other embodiments, the adjustment
element comprises a secondary grasper configured to grasp the
tissue to adjust the position of the tissue between the at least
one proximal and distal elements. In still other embodiments, the
adjustment element comprises a rotating component configured to
move the tissue between the at least one proximal and distal
elements. And, in yet other embodiments, the adjustment element is
configured to adjust a position of the at least one proximal
element so as to move the tissue in relation to the at least one
distal element.
[0024] In a further aspect of the present invention, a minimally
invasive device is provided comprising at least one proximal
element and at least one distal element configured for grasping
tissue therebetween, and a stabilizer configured to reduce movement
of the tissue prior to grasping the tissue between the at least one
proximal and distal elements. When the tissue comprises a leaflet
of a mitral valve, the stabilizer may comprise an expandable
member, a flap, an overtube or at least one loop configured to be
positioned against an atrial side of the leaflets so as to reduce
flail of the leaflets. For example, the stabilizer may comprise at
least one loop which is moveable toward a center of the valve so as
to reduce movement of the leaflet. When the tissue comprises a
leaflet having chordae extending therefrom, the stabilizer may
comprise an expandable member configured to hold the chordae upon
expansion so as to reduce movement of the leaflet.
[0025] In another aspect of the present invention, a system is
provided for assessing quality of fixation of a tissue within a
body comprising a fixation device having at least one proximal
element and at least one distal element configured for grasping
tissue therebetween, a catheter having a proximal end, a distal end
and a lumen therethrough, the catheter configured for endoluminal
advancement through at least a portion of the body to the tissue,
and a shaft removably coupled to the fixation device. The shaft is
configured to pass through the lumen of the catheter, and at least
a portion of the shaft is flexible to allow movement of the
fixation device relative to the catheter while the tissue is
grasped between the at least one proximal element and the at least
one distal element. In some embodiments, the shaft comprises a
compression coil. Thus, the system may further include a center
actuation wire configured to extend through the compression coil so
as to rigidify the coil during placement of the fixation device.
Optionally, the system may include a sheath extendable over at
least a portion of the flexible shaft so as to rigidify the shaft
during placement of the fixation device. Such rigidifying elements
are then removed to allow movement of the fixation device while the
tissue is grasped to evaluate the desirability of the fixation.
[0026] In another aspect of the present invention, a method of
fixing a pair of valve leaflets together along their coaptation
line is provided. The method comprises fixing the pair of valve
leaflets together at a first location along the coaptation line
with a first fixation device, and fixing the pair of valve leaflets
together at a second location along the coaptation line with a
second fixation device, wherein the first and second locations
differ. In some embodiments, the first and second locations are
adjacent to each other. Or, the first and second locations may be
spaced apart, such as approximately 1 cm apart. The first and
second locations may be positioned so as to provide a single
orifice, double orifice or triple orifice geometry, to name a few,
when a pressure gradient opens the pair of valve leaflets.
[0027] In some embodiments, the first fixation device has a first
pair of grasping elements and a second pair of grasping elements.
Thus, fixing the pair of valve leaflets together at the first
location may comprise grasping one leaflet of the pair of valve
leaflets between the first pair of grasping elements and grasping
another leaflet of the pair of valve leaflets between the second
pair of grasping elements. And, fixing the pair of valve leaflets
together at the second location may comprise grasping one leaflet
of the pair of valve leaflets between the first pair of grasping
elements of the second fixation device and grasping another leaflet
of the pair of valve leaflets between the second pair of grasping
elements of the second fixation device. In some embodiments, the
method further comprises assessing performance of the valve
leaflets after the step of fixing the pair of valve leaflets
together at the first location to determine need for the step of
fixing the pair of valve leaflets together at the second
location.
[0028] Other objects and advantages of the present invention will
become apparent from the detailed description to follow, together
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIGS. 1A-1C illustrate grasping of the leaflets with a
fixation device, inversion of the distal elements of the fixation
device and removal of the fixation device, respectively.
[0030] FIG. 2A-2E illustrate example positions of fixation devices
in desired orientations relative to the leaflets.
[0031] FIGS. 3, 4A-4B, 5A-5B, 6A-6B, 7A-7B illustrate an embodiment
of a fixation device in various positions.
[0032] FIGS. 8A-8L, 9A-9B, 10A-10B, 11A-11B illustrate embodiments
of devices which stabilize the valve leaflets by reducing upward
mobility and flailing of the leaflets.
[0033] FIGS. 12A-12B illustrate an embodiments which stabilizes the
valve leaflets by applying tension to the chordae attached to the
leaflets.
[0034] FIG. 13 illustrates a pacing lead extending to the
sinoatrial node which regulates movement of leaflets to assist in
grasping of the leaflets.
[0035] FIG. 14 illustrates pacing of the left ventricle directly
with a pacing catheter.
[0036] FIG. 15 illustrates an embodiment of a fixation device
having a vacuum line.
[0037] FIG. 16, illustrates an embodiment of a fixation device
having an adjunct-grasper.
[0038] FIG. 17 illustrates an embodiment of a fixation device
having a conveyor belt.
[0039] FIGS. 18A-18B illustrates an embodiment of a fixation device
having proximal elements which are adjustable inwardly to draw
grasped tissue further into the fixation device.
[0040] FIGS. 19A-19C illustrate an embodiment of a fixation device
adapted for use with a pre-grasper.
[0041] FIG. 20 illustrates a fixation device advanced via an atrial
approach and a pre-grasper advanced via a ventricular approach.
[0042] FIGS. 21A-21B illustrate embodiments of a fixation device
having two single-sided fixation elements joinable by a tether.
[0043] FIG. 22 illustrates an embodiment of fixation device having
self-engaging distal elements.
[0044] FIG. 23 illustrates an embodiment of a fixation device
having suction to maintain leaflet position after grasping.
[0045] FIGS. 24A-24B illustrate an embodiment of a fixation device
having extended frictional accessories.
[0046] FIGS. 25A-25B illustrate an embodiment of a fixation device
having a textured gripping surface.
[0047] FIG. 26A-26B illustrate an embodiment of a fixation device
having a gripping surface which penetrates and holds the grasped
leaflets within the fixation device.
[0048] FIGS. 27A-27B illustrate injecting leaflets with a substance
which enhances visibility.
[0049] FIG. 28 illustrates a fixation device wherein the proximal
elements and distal elements have enhanced visibility.
[0050] FIG. 29 illustrates a fixation device wherein the position
of a grasped leaflet within a fixation device may be determined
based on the visibility of frictional elements.
[0051] FIG. 30 illustrates a fixation device wherein the proximal
elements are comprised of segmental parts separated by hinges or
flexible areas.
[0052] FIGS. 31A-31B, 32A-32C, 33, 34A-34B, 35, 36A-36B illustrate
embodiments of a fixation device wherein the position of a grasped
tissue within a fixation device is determined based on the
visibility of an indicator associated with the distal elements.
[0053] FIGS. 37A-37B illustrate embodiments of a fixation device
having mini-grippers.
[0054] FIGS. 38A-38B illustrate an embodiment having a reservoir
within the distal elements which releases a substance
[0055] FIGS. 39A-39B illustrate an embodiment of a fixation device
wherein the position of the grasped tissue within a fixation device
is determined based on the visibility of a released substance from
a conduit.
[0056] FIGS. 40A-40B illustrate an embodiment of a fixation device
having a probe connected with an insertion depth gauge to determine
if a tissue has been desirably grasped.
[0057] FIGS. 41A-41F illustrate embodiments of fixation devices
having detectable elements extending toward the engagement surfaces
to determine if a tissue has been desirably grasped.
[0058] FIG. 42A-42B illustrate a fixation device having at least
one sensor disposed on or within a distal element.
[0059] FIG. 43 illustrate a fixation device having sensors which
extend into a target area between the proximal and distal
elements.
[0060] FIGS. 44A-44B illustrate a fixation device having sensors
positioned on the shaft.
[0061] FIG. 45A-45B, 46A-46B illustrate fixation devices and
methods for simulating the resultant placement and function of a
fixation device that has been positioned to grasp leaflets of the
mitral valve.
DETAILED DESCRIPTION OF THE INVENTION
[0062] The present invention provides devices, systems and methods
for stabilizing and grasping tissues such as valve leaflets,
assessing the grasp of these tissues, approximating and fixating
the tissues, and assessing the fixation of the tissues to treat
cardiac valve regurgitation, particularly mitral valve
regurgitation.
[0063] Grasping will preferably be atraumatic providing a number of
benefits. By atraumatic, it is meant that the devices and methods
of the invention may be applied to the valve leaflets and then
removed without causing any significant clinical impairment of
leaflet structure or function. The leaflets and valve continue to
function substantially the same as before the invention was
applied. Thus, some minor penetration or denting of the leaflets
may occur using the invention while still meeting the definition of
"atraumatic". This enables the devices of the invention to be
applied to a diseased valve and, if desired, removed or
repositioned without having negatively affected valve function. In
addition, it will be understood that in some cases it may be
necessary or desirable to pierce or otherwise permanently affect
the leaflets during either grasping, fixing or both. In addition,
once a leaflet is grasped, it may be desirable to further
incorporate leaflet tissue to ensure that the initial grasp will
result in secure tissue fixation. Furthermore, it may be desirable
once the leaflet is grasped to provide the user with feedback that
sufficient leaflet is incorporated, and/or to provide the user an
indication of the resulting placement, both prior to releasing the
fixation device thereby allowing repositioning or correction of the
placement if desired.
[0064] It may be appreciated that each the steps of stabilizing,
grasping, approximating, fixating and assessing may be accomplished
by a separate device or a plurality of steps may be accomplished by
a single device. In some embodiments, all of the steps may be
achieved by a single device. Further, in some embodiments, steps
are provided by separate devices which approach the tissue from
different directions. For example, when treating a mitral valve,
some devices may use an atrial approach while other devices use a
ventricular approach. Although a number of embodiments are provided
to achieve these results, a general overview of the basic features
will be presented herein. Such features are not intended to limit
the scope of the invention and are presented with the aim of
providing a basis for descriptions of individual embodiments
presented later in the application.
I. Fixation Device Overview
[0065] Many of the devices, systems and methods of the present
invention utilize or are utilized in conjunction with a preferred
embodiment of a fixation device described herein and in U.S. Pat.
No. 6,629,534 and U.S. patent application Ser. Nos. 10/441,531,
11/130,818, 10/975,555, all of which are incorporated herein by
reference for all purposes. The fixation device is provided by an
interventional tool that is positioned near a desired treatment
site and used to grasp the target tissue. In endovascular
applications, the interventional tool is typically an
interventional catheter. In surgical applications, the
interventional tool is typically an interventional instrument. In
preferred embodiments, fixation of the grasped tissue is
accomplished by maintaining grasping with a portion of the
interventional tool which is left behind as an implant. While the
invention may have a variety of applications for tissue
approximation and fixation throughout the body, it is particularly
well adapted for the repair of valves, especially cardiac valves
such as the mitral valve.
[0066] Referring to FIG. 1A, an interventional tool 10, having a
delivery device, such as a shaft 12, and a fixation device 14, is
illustrated having approached the mitral valve MV from the atrial
side and grasped the leaflets LF. The mitral valve may be accessed
either surgically or by using endovascular techniques, and either
by a retrograde approach through the ventricle or by an antegrade
approach through the atrium, as described above. For illustration
purposes, an antegrade approach is described.
[0067] The fixation device 14 is releasably attached to the shaft
12 of the interventional tool 10 at its distal end. When describing
the devices of the invention herein, "proximal" shall mean the
direction toward the end of the device to be manipulated by the
user outside the patient's body, and "distal" shall mean the
direction toward the working end of the device that is positioned
at the treatment site and away from the user. With respect to the
mitral valve, proximal shall refer to the atrial or upstream side
of the valve leaflets and distal shall refer to the ventricular or
downstream side of the valve leaflets.
[0068] The fixation device 14 typically comprises proximal elements
16 (or gripping elements) and distal elements 18 (or fixation
elements) which protrude radially outward and are positionable on
opposite sides of the leaflets LF as shown so as to capture or
retain the leaflets therebetween. The proximal elements 16 are
preferably comprised of cobalt chromium, nitinol or stainless
steel, and the distal elements 18 are preferably comprised of
cobalt chromium alloy (such as Elgiloy.RTM.) or stainless steel,
however any suitable materials may be used. The fixation device 14
is coupleable to the shaft 12 by a coupling mechanism 17. The
coupling mechanism 17 allows the fixation device 14 to detach and
be left behind as an implant to hold the leaflets together in the
coapted position.
[0069] In some situations, it may be desired to reposition or
remove the fixation device 14 after the proximal elements 16,
distal elements 18, or both have been deployed to capture the
leaflets LF. Such repositioning or removal may be desired for a
variety of reasons, such as to reapproach the valve in an attempt
to achieve better valve function, more optimal positioning of the
device 14 on the leaflets, better purchase on the leaflets, to
detangle the device 14 from surrounding tissue such as chordae, to
exchange the device 14 with one having a different design, or to
abort the fixation procedure, to name a few. To facilitate
repositioning or removal of the fixation device 14 the distal
elements 18 are releasable and optionally invertible to a
configuration suitable for withdrawal of the device 14 from the
valve without tangling or interfering with or damaging the chordae,
leaflets or other tissue. FIG. 1B illustrates inversion wherein the
distal elements 18 are moveable in the direction of arrows 40 to an
inverted position. Likewise, the proximal elements 16 may be
raised, if desired. In the inverted position, the device 14 may be
repositioned to a desired orientation wherein the distal elements
may then be reverted to a grasping position against the leaflets as
in FIG. 1A. Alternatively, the fixation device 14 may be withdrawn
(indicated by arrow 42) from the leaflets as shown in FIG. 1C. Such
inversion reduces trauma to the leaflets and minimizes any
entanglement of the device with surrounding tissues. Once the
device 14 has been withdrawn through the valve leaflets, the
proximal and distal elements may be moved to a closed position or
configuration suitable for removal from the body or for reinsertion
through the mitral valve.
[0070] FIGS. 2A-2C illustrate example positions of one or more
fixation devices 14 in desired orientations in relation to the
leaflets LF. These are short-axis views of the mitral valve MV from
the atrial side, therefore, the proximal elements 16 are shown in
solid line and the distal elements 18 are shown in dashed line. The
proximal and distal elements 16, 18 are typically positioned to be
substantially perpendicular to the line of coaptation C. The
devices 14 may be moved roughly along the line of coaptation to any
desired location for fixation. The leaflets LF are held in place so
that during diastole, as shown in FIG. 2A-2C, the leaflets LF
remain in position between the elements 16, 18 surrounded by
openings O which result from the diastolic pressure gradient.
Advantageously, leaflets LF are coapted such that their proximal or
upstream surfaces are facing each other in a vertical orientation,
parallel to the direction of blood flow through mitral valve MV.
The upstream surfaces may be brought together so as to be in
contact with one another or may be held slightly apart, but will
preferably be maintained in the vertical orientation in which the
upstream surfaces face each other at the point of coaptation.
Referring to FIG. 2A, the placement of one fixation device near the
center of the leaflets LF simulates the double orifice geometry of
a standard surgical bow-tie repair. Color Doppler echo will show if
the regurgitation of the valve has been reduced. If the resulting
mitral flow pattern is satisfactory, the leaflets may be fixed
together in this orientation. If the resulting color Doppler image
shows insufficient improvement in mitral regurgitation, the
interventional tool 10 may be repositioned. This may be repeated
until an optimal result is produced wherein the leaflets LF are
held in place. Once the leaflets are coapted in the desired
arrangement, the fixation device 14 is then detached from the shaft
12 and left behind as an implant to hold the leaflets together in
the coapted position. It may be desired to add an additional
fixation element 14', such as illustrated in FIGS. 2B-2E. In FIG.
2B, the additional fixation element 14' is positioned beside the
previously place fixation element 14 retaining the double orifice
geometry. In FIG. 2C, the additional fixation element 14' is
positioned a distance, such as up to 1 cm, from the previously
placed fixation element 14 creating a triple orifice geometry. In
FIG. 2D, the fixation elements 14, 14' are positioned adjacent to
each other near a first commissure CM1. Such arrangement creates
generally a single orifice geometry by plicating on one side of the
valve opening. Likewise, as shown in FIG. 2E, one fixation element
14 may be positioned near the first commissure CM1 and an
additional fixation element 14' may be positioned near a second
commissure CM2. Such arrangement also creates generally a single
orifice geometry by plicating on either side of the valve opening.
The additional fixation element 14' may be desired to ensure
adequate fixation of the leaflets LF and/or to further reposition
the leaflets LF. The additional fixation element 14' may be added
at any time during the procedure or at a separate procedure at a
later point in time. It may be appreciated that any number of
fixation elements 14 may be positioned to fixate the leaflets or
any other tissue, including two, three, four, five or more fixation
elements 14.
[0071] FIG. 3 illustrates an embodiment of a fixation device 14.
Here, the fixation device 14 is shown coupled to a shaft 12 to form
an interventional tool 10. The fixation device 14 includes a
coupling member 19 and a pair of opposed distal elements 18. The
distal elements 18 comprise elongate arms 53, each arm having a
proximal end 52 rotatably connected to the coupling member 19 and a
free end 54. The free ends 54 have a rounded shape to minimize
interference with and trauma to surrounding tissue structures.
Preferably, each free end 54 defines a curvature about two axes,
one being a longitudinal axis 66 of arms 53. Thus, engagement
surfaces 50 have a cupped or concave shape to surface area in
contact with tissue and to assist in grasping and holding the valve
leaflets. This further allows arms 53 to nest around the shaft 12
in a closed position to minimize the profile of the device.
Preferably, arms 53 are at least partially cupped or curved
inwardly about their longitudinal axes 66. Also, preferably, each
free end 54 defines a curvature about an axis 67 perpendicular to
longitudinal axis 66 of arms 53. This curvature is a reverse
curvature along the most distal portion of the free end 54.
Likewise, the longitudinal edges of the free ends 54 may flare
outwardly. Both the reverse curvature and flaring minimize trauma
to the tissue engaged therewith. Arms 53 further include a
plurality of openings to enhance grip and to promote tissue
ingrowth following implantation.
[0072] The valve leaflets are grasped between the distal elements
18 and proximal elements 16. In some embodiments, the proximal
elements 16 are flexible, resilient, and cantilevered from coupling
member 19. The proximal elements are preferably resiliently biased
toward the distal elements. Each proximal element 16 is shaped and
positioned to be at least partially recessed within the concavity
of the distal element 18 when no tissue is present. When the
fixation device 14 is in the open position, the proximal elements
16 are shaped such that each proximal element 16 is separated from
the engagement surface 50 near the proximal end 52 of arm 53 and
slopes toward the engagement surface 50 near the free end 54 with
the free end of the proximal element contacting engagement surface
50, as illustrated in FIG. 3. This shape of the proximal elements
16 accommodates valve leaflets or other tissues of varying
thicknesses.
[0073] Proximal elements 16 may include a plurality of openings 63
and scalloped side edges 61 to increase grip on tissue. The
proximal elements 16 optionally include frictional accessories,
frictional features or grip-enhancing elements to assist in
grasping and/or holding the leaflets. In preferred embodiments, the
frictional accessories comprise barbs 60 having tapering pointed
tips extending toward engagement surfaces 50. It may be appreciated
that any suitable frictional accessories may be used, such as
prongs, windings, bands, barbs, grooves, channels, bumps, surface
roughening, sintering, high-friction pads, coverings, coatings or a
combination of these. Optionally, magnets may be present in the
proximal and/or distal elements. It may be appreciated that the
mating surfaces will be made from or will include material of
opposite magnetic charge to cause attraction by magnetic force. For
example, the proximal elements and distal elements may each include
magnetic material of opposite charge so that tissue is held under
constant compression between the proximal and distal elements to
facilitate faster healing and ingrowth of tissue. Also, the
magnetic force may be used to draw the proximal elements 16 toward
the distal elements 18, in addition to or alternatively to biasing
of the proximal elements toward the distal elements. This may
assist in deployment of the proximal elements 16. In another
example, the distal elements 18 each include magnetic material of
opposite charge so that tissue positioned between the distal
elements 18 is held therebetween by magnetic force.
[0074] The fixation device 14 also includes an actuation mechanism
58. In this embodiment, the actuation mechanism 58 comprises two
link members or legs 68, each leg 68 having a first end 70 which is
rotatably joined with one of the distal elements 18 at a riveted
joint 76 and a second end 72 which is rotatably joined with a stud
74. The legs 68 are preferably comprised of a rigid or semi-rigid
metal or polymer such as Elgiloy.RTM., cobalt chromium or stainless
steel, however any suitable material may be used. While in the
embodiment illustrated both legs 68 are pinned to stud 74 by a
single rivet 78, it may be appreciated, however, that each leg 68
may be individually attached to the stud 74 by a separate rivet or
pin. The stud 74 is joinable with an actuator rod 64 (not shown)
which extends through the shaft 12 and is axially extendable and
retractable to move the stud 74 and therefore the legs 68 which
rotate the distal elements 18 between closed, open and inverted
positions. Likewise, immobilization of the stud 74 holds the legs
68 in place and therefore holds the distal elements 18 in a desired
position. The stud 74 may also be locked in place by a locking
feature.
[0075] In any of the embodiments of fixation device 14 disclosed
herein, it may be desirable to provide some mobility or flexibility
in distal elements 18 and/or proximal elements 16 in the closed
position to enable these elements to move or flex with the opening
or closing of the valve leaflets. This provides shock absorption
and thereby reduces force on the leaflets and minimizes the
possibility for tearing or other trauma to the leaflets. Such
mobility or flexibility may be provided by using a flexible,
resilient metal or polymer of appropriate thickness to construct
the distal elements 18. Also, the locking mechanism of the fixation
device (described below) may be constructed of flexible materials
to allow some slight movement of the proximal and distal elements
even when locked. Further, the distal elements 18 can be connected
to the coupling mechanism 19 or to actuation mechanism 58 by a
mechanism that biases the distal element into the closed position
(inwardly) but permits the arms to open slightly in response to
forces exerted by the leaflets. For example, rather than being
pinned at a single point, these components may be pinned through a
slot that allowed a small amount of translation of the pin in
response to forces against the arms. A spring is used to bias the
pinned component toward one end of the slot.
[0076] FIGS. 4A-4B, 5A-5B, 6A-6B, 7A-7B illustrate embodiments of
the fixation device 14 of FIG. 3 in various possible positions
during introduction and placement of the device 14 within the body
to perform a therapeutic procedure. FIG. 4A illustrates an
embodiment of an interventional tool 10 delivered through a
catheter 86. It may be appreciated that the interventional tool 10
may take the form of a catheter, and likewise, the catheter 86 may
take the form of a guide catheter or sheath. However, in this
example the terms interventional tool 10 and catheter 86 will be
used. The interventional tool 10 comprises a fixation device 14
coupled to a shaft 12 and the fixation device 14 is shown in the
closed position. FIG. 4B illustrates a similar embodiment of the
fixation device of FIG. 4A in a larger view. In the closed
position, the opposed pair of distal elements 18 are positioned so
that the engagement surfaces 50 face each other. Each distal
element 18 comprises an elongate arm 53 having a cupped or concave
shape so that together the arms 53 surround the shaft 12 and
optionally contact each other on opposite sides of the shaft. This
provides a low profile for the fixation device 14 which is readily
passable through the catheter 86 and through any anatomical
structures, such as the mitral valve. In addition, FIG. 4B further
includes an actuation mechanism 58. In this embodiment, the
actuation mechanism 58 comprises two legs 68 which are each movably
coupled to a base 69. The base 69 is joined with an actuator rod 64
which extends through the shaft 12 and is used to manipulate the
fixation device 14. In some embodiments, the actuator rod 64
attaches directly to the actuation mechanism 58, particularly the
base 69. However, the actuator rod 64 may alternatively attach to a
stud 74 which in turn is attached to the base 69. In some
embodiments, the stud 74 is threaded so that the actuator rod 64
attaches to the stud 74 by a screw-type action. However, the rod 64
and stud 74 may be joined by any mechanism which is releasable to
allow the fixation device 14 to be detached from shaft 12.
[0077] FIGS. 5A-5B illustrate the fixation device 14 in the open
position. In the open position, the distal elements 18 are rotated
so that the engagement surfaces 50 face a first direction. Distal
advancement of the stud 74 relative to coupling member 19 by action
of the actuator rod 64 applies force to the distal elements 18
which begin to rotate around joints 76 due to freedom of movement
in this direction. Such rotation and movement of the distal
elements 18 radially outward causes rotation of the legs 68 about
joints 80 so that the legs 68 are directly slightly outwards. The
stud 74 may be advanced to any desired distance correlating to a
desired separation of the distal elements 18. In the open position,
engagement surfaces 50 are disposed at an acute angle relative to
shaft 12, and are preferably at an angle of between 90 and 180
degrees relative to each other. In one embodiment, in the open
position the free ends 54 of arms 53 have a span therebetween of
about 10-20 mm, usually about 12-18 mm, and preferably about 14-16
mm.
[0078] Proximal elements 16 are typically biased outwardly toward
arms 53. The proximal elements 16 may be moved inwardly toward the
shaft 12 and held against the shaft 12 with the aid of proximal
element lines 90 which can be in the form of sutures, wires,
nitinol wire, rods, cables, polymeric lines, or other suitable
structures. The proximal element lines 90 may be connected with the
proximal elements 16 by threading the lines 90 in a variety of
ways. When the proximal elements 16 have a loop shape, as shown in
FIG. 5A, the line 90 may pass through the loop and double back.
When the proximal elements 16 have an elongate solid shape, as
shown in FIG. 5B, the line 90 may pass through one or more of the
openings 63 in the element 16. Further, a line loop 48 may be
present on a proximal element 16, also illustrated in FIG. 5B,
through which a proximal element line 90 may pass and double back.
Such a line loop 48 may be useful to reduce friction on proximal
element line 90 or when the proximal elements 16 are solid or
devoid of other loops or openings through which the proximal
element lines 90 may attach. A proximal element line 90 may attach
to the proximal elements 16 by detachable means which would allow a
single line 90 to be attached to a proximal element 16 without
doubling back and would allow the single line 90 to be detached
directly from the proximal element 16 when desired. Examples of
such detachable means include hooks, snares, clips or breakable
couplings, to name a few. By applying sufficient tension to the
proximal element line 90, the detachable means may be detached from
the proximal element 16 such as by breakage of the coupling. Other
mechanisms for detachment may also be used. Similarly, a lock line
92 may be attached and detached from a locking mechanism by similar
detachable means.
[0079] In the open position, the fixation device 14 can engage the
tissue which is to be approximated or treated. This embodiment is
adapted for repair of the mitral valve using an antegrade approach
from the left atrium. The interventional tool 10 is advanced
through the mitral valve from the left atrium to the left
ventricle. The distal elements 18 are oriented to be perpendicular
to the line of coaptation and then positioned so that the
engagement surfaces 50 contact the ventricular surface of the valve
leaflets, thereby grasping the leaflets. The proximal elements 16
remain on the atrial side of the valve leaflets so that the
leaflets lie between the proximal and distal elements. In this
embodiment, the proximal elements 16 have frictional accessories,
such as barbs 60 which are directed toward the distal elements 18.
However, neither the proximal elements 16 nor the barbs 60 contact
the leaflets at this time.
[0080] The interventional tool 10 may be repeatedly manipulated to
reposition the fixation device 14 so that the leaflets are properly
contacted or grasped at a desired location. Repositioning is
achieved with the fixation device in the open position. In some
instances, regurgitation may also be checked while the device 14 is
in the open position. If regurgitation is not satisfactorily
reduced, the device may be repositioned and regurgitation checked
again until the desired results are achieved.
[0081] It may also be desired to invert the fixation device 14 to
aid in repositioning or removal of the fixation device 14. FIGS.
6A-6B illustrate the fixation device 14 in the inverted position.
By further advancement of stud 74 relative to coupling member 19,
the distal elements 18 are further rotated so that the engagement
surfaces 50 face outwardly and free ends 54 point distally, with
each arm 53 forming an obtuse angle relative to shaft 12. The angle
between arms 53 is preferably in the range of about 270 to 360
degrees. Further advancement of the stud 74 further rotates the
distal elements 18 around joints 76. This rotation and movement of
the distal elements 18 radially outward causes rotation of the legs
68 about joints 80 so that the legs 68 are returned toward their
initial position, generally parallel to each other. The stud 74 may
be advanced to any desired distance correlating to a desired
inversion of the distal elements 18. Preferably, in the fully
inverted position, the span between free ends 54 is no more than
about 20 mm, usually less than about 16 mm, and preferably about
12-14 mm. In this illustration, the proximal elements 16 remain
positioned against the shaft 12 by exerting tension on the proximal
element lines 90. Thus, a relatively large space may be created
between the elements 16, 18 for repositioning. In addition, the
inverted position allows withdrawal of the fixation device 14
through the valve while minimizing trauma to the leaflets.
Engagement surfaces 50 provide an atraumatic surface for deflecting
tissue as the fixation device is retracted proximally. It should be
further noted that barbs 60 are angled slightly in the distal
direction (away from the free ends of the proximal elements 16),
reducing the risk that the barbs will catch on or lacerate tissue
as the fixation device is withdrawn.
[0082] Once the fixation device 14 has been positioned in a desired
location against the valve leaflets, the leaflets may then be
captured between the proximal elements 16 and the distal elements
18. FIGS. 7A-7B illustrate the fixation device 14 in such a
position. Here, the proximal elements 16 are lowered toward the
engagement surfaces 50 so that the leaflets are held therebetween.
In FIG. 7B, the proximal elements 16 are shown to include barbs 60
which may be used to provide atraumatic gripping of the leaflets.
Alternatively, larger, more sharply pointed barbs or other
penetration structures may be used to pierce the leaflets to more
actively assist in holding them in place. This position is similar
to the open position of FIGS. 5A-5B, however the proximal elements
16 are now lowered toward arms 53 by releasing tension on proximal
element lines 90 to compress the leaflet tissue therebetween. At
any time, the proximal elements 16 may be raised and the distal
elements 18 adjusted or inverted to reposition the fixation device
14, if regurgitation is not sufficiently reduced.
[0083] After the leaflets have been captured between the proximal
and distal elements 16, 18 in a desired arrangement, the distal
elements 18 may be locked to hold the leaflets in this position or
the fixation device 14 may be returned to or toward a closed
position.
[0084] It may be appreciated that the fixation devices 14 of the
present invention may have any or all of the above described
functions and features. For example, the fixation devices 14 may or
may not be moveable to an inverted position. Or, the fixation
devices 14 may or may not include proximal elements 16. Thus, the
above described aspects of the fixation devices 14 are simply
preferred embodiments and are not intended to limit the scope of
the present invention.
II. Stabilization of Leaflets
[0085] A variety of devices and techniques are provided to
stabilize the leaflets prior to grasping. Such stabilization is
aimed to assist in effectively and efficiently grasping the
leaflets thereby increasing the likelihood that the desired amount
of leaflet will be incorporated into the fixation device without
necessitating multiple grasps. It may be appreciated that the
stabilization devices and techniques may be used in combination
with the above described fixation device or may be used with any
suitable grasping and/or fixing device. Further, many of such
stabilization techniques and devices may be used to stabilize valve
leaflets, or other tissues, for any purpose.
[0086] Typically in cases of mitral valve regurgitation, a portion
of the leaflet LF is moving out of phase with the other leaflets or
portions of the leaflets. This can occur due to an elongation or
disconnection of the structures (chordae tendinae) holding the
leaflets stable and in synchrony. Such a malfunction can lead to
one leaflet or portion of a leaflet to swing or "flail" above the
level of healthy coaptation, thereby allowing blood to regurgitate
into the right atrium. FIGS. 8A-8L, 9A-9B, 10A-10B illustrate
embodiments of devices which stabilize the valve leaflets by
reducing upward mobility and flailing of the leaflets thereby
allowing the user to more reliably grasp the targeted leaflets. In
these embodiments, a catheter 86 is advanced into a left atrium LA
of a heart H, as illustrated in FIG. 8A, and a fixation device 14
is advanced through the catheter 86 and through a mitral valve MV
having leaflets LF so that at least a portion of the fixation
device 14 is positioned within a left ventricle LV. The valve
leaflets LF are shown flailing upwards toward the left atrium LA
while the fixation device 14 resides below the valve, within the
left ventricle LV. In this example, the fixation device 14
resembles the fixation device described above in relation to FIG. 3
and includes proximal elements 16 and distal elements 18. The
fixation device 14 is at least partially opened to extend the
distal elements 18 radially outwardly while the proximal elements
16 remain held against the shaft 12. It is desired to engage the
leaflets LF with the distal elements 18 so that the proximal
elements 16 may be lowered grasping the leaflets LF
therebetween.
[0087] One or more stabilizing loops 100 may be advanced from the
catheter 86 and positioned against the atrial side of the leaflets
LF. FIG. 8B illustrates a cross-sectional top view of an embodiment
of a stabilizing loop 100. The loop 100 is shown extending radially
outwardly from the catheter 86 to form a circular shape. The
diameter of the circular shape may be varied by advancement or
retraction of the loop 100 from the catheter 86. The loop 100 may
be comprised of any suitable material such as metal, polymer, or
fiber, and may have any suitable form such as wire, ribbon, links,
or weave. FIG. 8C provides a side view of the embodiment shown in
FIG. 8B. The circular shape of the loop 100 resides in a plane
substantially perpendicular to the catheter 86. Thus, the loop 100
may be positioned along the annulus of the valve, as illustrated in
FIG. 8A. In this position, the leaflets LF may still flail upwards.
Referring to FIG. 8D, the diameter of the loop 100 may then be
reduced, as indicated by arrows 102. This may be achieved by
partial retraction of the loop 100 into the catheter 86. Continual
reduction of the diameter draws the loop 100 from the annulus
toward the center of the valve. As the loop 100 travels (prior loop
100' shown in dashed line), the loop 100 restricts upward motion or
flailing of the leaflets LF in a controlled manner and positions
the leaflets LF for optimal grasping between the proximal and
distal elements 16, 18.
[0088] It may be appreciated that more than one loop 100 may be
present to stabilize the leaflets; the loops may be concentric,
adjacent to each other, in separate planes or in any suitable
arrangement. For example, FIG. 8E illustrates an embodiment having
a first loop 100a and a second loop 100b. The loops 100a, 100b
function similarly to the embodiment illustrated in FIGS. 8A-8D,
however, the second loop 100b is smaller and located concentrically
within the first loop 100a. The diameters of the loops 100a, 100b
may have any suitable size and the relationship of the diameters
may vary. FIG. 8F provides a side view of the embodiment shown in
FIG. 8E. As shown, the circular shapes of the loops 100a, 100b
reside in a plane substantially perpendicular to the catheter 86.
Thus, the loops 100a, 100b may be positioned against the valve
leaflets LF to stabilize the leaflets LF. The diameter of the loops
100a, 100b may then be reduced, simultaneously or individually, by
partial retraction of the loops 100a, 100b into the catheter 86.
Continual reduction of the diameters draw the loops 100a, 100b
toward the center of the valve. Again, as the loops 100a, 100b
travel, the loops 100a, 100b restrict upward motion or flailing of
the leaflets LF in a controlled manner and positions the leaflets
LF for optimal grasping between the proximal and distal elements
16, 18.
[0089] FIG. 8G illustrates another embodiment having a first loop
100a and a second loop 100b. However, in this embodiment, the loops
100a, 100b are non-concentric, each loop extending from an opposite
side of the catheter 86. The diameters of the loops 100a, 100b may
have any suitable size and the relationship of the diameters may
vary. FIG. 8H provides a side view of the embodiment shown in FIG.
8G. As shown, the circular shapes of the loops 100a, 100b reside in
a plane substantially perpendicular to the catheter 86. Thus, the
loops 100a, 100b may be positioned against the valve leaflets LF to
stabilize the leaflets LF. FIG. 8I provides a top view of the
mitral valve MV wherein the catheter 86 is positioned above the
valve MV so that the fixation device (not shown) may be passed
through the leaflets LF. The loops 100a, 100b are shown extended
radially outwardly toward the annulus. The diameter of the loops
100a, 100b may then be reduced, as indicated by arrows 102. This
may be achieved by partial retraction of the loops 100a, 100b into
the catheter 86. Continual reduction of the diameter draws the
loops 100a, 100b from the annulus toward the center of the valve.
As the loops 100a, 100b travel (prior loops 100a', 100b' shown in
dashed line), the loops 100a, 100b restricts upward motion or
flailing of the leaflets LF in a controlled manner and positions
the leaflets LF for optimal grasping between the proximal and
distal elements 16, 18. As shown, each loop 100a, 100b restricts
movement of an individual leaflet LF. However, it may be
appreciated that the catheter 86 may be oriented (such as at a 90
degree rotation) so that each loop 100a, 100b contacts more than
one leaflet LF.
[0090] FIG. 8J illustrates an embodiment having a single loop 100
which resides in a plane substantially parallel to the catheter 86.
FIG. 8K provides a side view of the embodiment shown in FIG. 8J.
The loop 100 may have any suitable shape and diameter. Thus, the
loop 100 may be positioned against the valve leaflets LF to
stabilize the leaflets LF. FIG. 8L provides a top view of the
mitral valve MV wherein the catheter 86 is positioned above the
valve MV so that the fixation device (not shown) may be passed
through the leaflets LF. The loop 100 is shown extended radially
outwardly toward the annulus, perpendicular to the commissures C.
Such positioning restricts upward movement of the leaflets LF. In
addition, the diameter of the loop 100 may then be reduced, as
indicated by arrows 102. This may be achieved by partial retraction
of the loop 100 into the catheter 86. Continual reduction of the
diameter draws the loop 100 from the annulus toward the center of
the valve. As the loop 100 travels (prior loop 100' shown in dashed
line), the loop 100 maintains restricted upward motion or flailing
of the leaflets LF and positions the leaflets LF for optimal
grasping between the proximal and distal elements 16, 18.
[0091] It may be appreciated that in any of the embodiments
described above, the loops may be extended to stabilize both
leaflets or may be extended to stabilize one leaflet that is
flailing. This may be achieved by orientation of the catheter 86,
shape of the loop 100, amount of extension of the loop 100 or any
other method. The embodiments illustrated in FIGS. 8G-8I are
particularly suited for single leaflet flailing wherein only the
first loop 100a may be present. It may further be appreciated that
the loops 100 may include surface treatments or accessories, such
as rollers or grippers, to assist in stabilization of the
leaflets.
[0092] FIGS. 9A-9B illustrate another embodiment which stabilizes
the valve leaflets LF by reducing upward mobility and flailing of
the leaflets LF. As shown in FIG. 9A, a catheter 86 is advanced
into a left atrium LA of a heart H and a fixation device 14 is
advanced through the catheter 86 and through a mitral valve MV
having leaflets LF so that at least a portion of the fixation
device 14 is positioned within a left ventricle LV. The valve
leaflets LF are shown flailing upwards toward the left atrium LA
while the fixation device 14 resides below the valve, within the
left ventricle LV. In this example, the fixation device 14
resembles the fixation device described above in relation to FIG. 3
and includes proximal elements 16 and distal elements 18. The
fixation device 14 is at least partially opened to extend the
distal elements 18 radially outwardly while the proximal elements
16 remain held against the shaft 12. It is desired to engage the
leaflets LF with the distal elements 18 so that the proximal
elements 16 may be lowered grasping the leaflets LF
therebetween.
[0093] One or more flaps 104 may extend radially outwardly from the
catheter 86, as shown, and be positioned against the atrial side of
the leaflets LF. The flaps 104 may be comprised of any suitable
material such as metal, polymer, or fiber, and may have any
suitable form such as a solid, a mesh, or a weave. Further, the
flaps 104 may have any suitable shape and may include one or more
cutouts 106. As shown in FIG. 9B, the cutouts 106 may be sized and
positioned to allow the proximal elements 16 of the fixation device
14 to extend therethrough. This allows the flaps 104 to be held
against the atrial side of the leaflets LF restricting upward
motion or flailing of the leaflets LF. This positions the leaflets
LF for optimal grasping between the proximal and distal elements
16, 18. Once the leaflets have been grasped, the flaps 104 may be
removed with the catheter 86 or may be left behind to assist in
holding the leaflets LF.
[0094] FIGS. 10A-10B illustrate another embodiment which stabilizes
the valve leaflets LF by reducing upward mobility and flailing of
the leaflets LF. As shown in FIG. 10A, a catheter 86 is advanced
into a left atrium LA of a heart H and a fixation device 14 is
advanced through the catheter 86 and through a mitral valve MV
having leaflets LF so that at least a portion of the fixation
device 14 is positioned within a left ventricle LV. The valve
leaflets LF are shown flailing upwards toward the left atrium LA
while the fixation device 14 resides below the valve, within the
left ventricle LV. In this example, the fixation device 14
resembles the fixation device described above in relation to FIG. 3
and includes proximal elements 16 and distal elements 18. The
fixation device 14 is at least partially opened to extend the
distal elements 18 radially outwardly while the proximal elements
16 remain held against the shaft 12. It is desired to engage the
leaflets LF with the distal elements 18 so that the proximal
elements 16 may be lowered grasping the leaflets LF
therebetween.
[0095] One or more expandable members 110 may extend radially
outwardly from the catheter 86, as shown, and be positioned against
the atrial side of the leaflets LF. The expandable member 110 may
be comprised of any suitable material such as silicone or
polyurethane and may have any suitable form such as a balloon. FIG.
10B provides an additional view of the embodiment. As shown, the
expandable member 110 may be expanded within the left atrium and
held against the atrial side of the leaflets LF restricting upward
motion or flailing of the leaflets LF. This positions the leaflets
LF for optimal grasping between the proximal and distal elements
16, 18.
[0096] FIGS. 11A-11B illustrate another embodiment which stabilizes
the valve leaflets LF by reducing upward mobility and flailing of
the leaflets LF. In this example, the fixation device 14 resembles
the fixation device described above in relation to FIG. 3 and
includes proximal elements 16 and distal elements 18. Again, the
fixation device 14 is advanced through a catheter and through a
mitral valve MV having leaflets LF so that the distal elements 18
of the fixation device 14 are positioned within a left ventricle
LV. The fixation device 14 is at least partially opened to extend
the distal elements 18 radially outwardly while the proximal
elements 16 remain held against the shaft 12. It is desired to
engage the leaflets LF with the distal elements 18 so that the
proximal elements 16 may then be lowered grasping the leaflets LF
therebetween. However, prior to lowering the proximal elements 16,
an overtube 121 having slots 123 is advanced over the shaft 12 and
be positioned against the atrial side of the leaflets LF, as
illustrated in FIG. 11B. The overtube 121 may be comprised of any
suitable material such as polyimide, poly ethyl ethyl ketone
(PEEK.TM.), nylon resins (such as PEBAX.RTM.), or polyurethane and
the slots may have any suitable dimension to allow passage of the
proximal elements 16 therethrough. Holding of the leaflets LF by
the overtube 121 restricts upward motion or flailing of the
leaflets LF, and allows confirmation that leaflets are positioned
correctly prior to lowering the proximal elements 16. This
positions the leaflets LF for optimal grasping between the proximal
and distal elements 16, 18. The proximal elements 16 may then be
released, wherein the proximal elements 16 pass through the slots
123 hold the leaflets between the proximal and distal elements 16,
18. The overtube 121 may then be retracted and removed.
[0097] FIGS. 12A-12B illustrate embodiment which stabilizes the
valve leaflets by applying tension to the chordae attached to the
leaflets. Such stabilization may be desired to reducing upward
mobility and flailing of the leaflets or to simply reduce movement
of the leaflets. FIG. 12A illustrates a heart H having a mitral
valve MV comprised of leaflets LF. Chordae CH are shown extending
from one of the leaflets LF to the left ventricle LV. It may be
appreciated that chordae are numerous and extend from both leaflets
to the left ventricle however select chordae are illustrated for
simplicity. As shown in FIG. 12B, a catheter 120 having an
expandable member 122, such as a balloon, may be advanced to the
left ventricle LV wherein the catheter 120 is positioned and the
expandable member 122 expanded so that tension is applied to the
chordae CH. FIG. 12B shows the catheter 120 advanced through the
aortic valve AV however the catheter 120 may approach the chordae
CH via any suitable pathway, including through the mitral valve MV
or through the septum S. Applying tension to the chordae CH adjusts
the position of the attached leaflet LF. Thus, the leaflet LF may
be manipulated and repositioned by manipulating the catheter 120
and expandable member 122, including varying expansion of the
expandable member 122. In particular, by pressing laterally against
the chordae CH with the expandable member 122 the leaflet LF may be
drawn downward restricting upward mobility and flailing of the
leaflet LF. Once the leaflets LF are disposed in a desirable
position, the leaflets LF may be fixed by a fixation device such as
described in relation to FIG. 3. Alternatively, a grasper may be
employed to tension the chordae CH.
[0098] The above described embodiments focus on mechanically
stabilizing the valve leaflets. Additional embodiments focus on
stabilizing the valve leaflets by physiologically slowing the
motion of the leaflets. This may be achieved by slowing the natural
pace of the heart. In one embodiment, illustrated in FIG. 13, a
pacemaker 130, or pulse generator, is shown having a pacing lead
132 with an electrode 134 which extend to the sinoatrial node SA in
the right atrium RA. Pacing is achieved when the pacemaker 130
sends electrical impulses through the pacing lead 132 to the
electrode 134 which stimulates the sinoatrial node SA. This
stimulates the right atrium RA to pump blood into the right
ventricle RV and thereon through the heart H. Thus, the pumping of
the heart and therefore movement of the leaflets of the valves can
be regulated with the use of the pacemaker 130. FIG. 13 illustrates
a fixation device 14 passed through the leaflets LF of the mitral
valve MV. The movement of the leaflets LF may be paced so that, for
example, the mitral valve MV stays in systole (closed) for a longer
period of time to aid in grasping the leaflets LF with the fixation
device 14. Similarly, as illustrated in FIG. 14, the left ventricle
LV may be paced directly with a pacing catheter 136 by stimulating
left bundle LB. This may be achieved by advancing the pacing
catheter 136 through the aortic valve AV to the left ventricle LV
as shown.
III. Grasping Assistance
[0099] To assist in effectively and efficiently grasping the
leaflets, a variety of devices and techniques are provided. Many of
the devices and techniques will be described as adjuncts to the
fixation device described in relation to FIG. 3. However, many
features may be used with any suitable grasping and/or fixing
device. Further, many of such techniques and devices may be used to
grasp valve leaflets, or other tissues, for any purpose.
[0100] In some situations, one or more leaflets LF are not grasped
between the proximal elements 16 and distal elements 18 in a
desired position. For example, a less than desired amount of the
leaflet LF may be grasped. Such decreased purchase may, for
example, reduce the effectivity of the regurgitation treatment
and/or increase the risk of the leaflet LF slipping out of the
fixation device. Once a portion of the leaflet LF is grasped, the
leaflet LF position may be adjusted; for example, the leaflet LF
may be "pulled in" or advanced toward the shaft 12 of the fixation
device 14 to increase the purchase. Embodiments to assist in such
adjustment are provided in FIGS. 15-17, 18A-18B.
[0101] FIG. 15 illustrates an embodiment of a fixation device 14
similar to the fixation device 14 illustrated in FIG. 3. As shown,
a leaflet LF is partially grasped between a proximal element 16 and
a distal element 18. In this embodiment, a vacuum line 140 extends
through the shaft 12 and is connected to a vacuum source 142. The
vacuum line 140 has a distal end 144 which protrudes into a space
146 between the proximal and distal element 16, 18. Actuation of
the vacuum source 142 applies suction to the space 146 which draws
the leaflet LF inward toward the shaft 12. Thus, the leaflet LF,
once grasped, may be repositioned within the proximal and distal
elements by suction force. It may be appreciated that the same
vacuum line 140 or an additional vacuum line may apply suction to a
leaflet between the other proximal and distal elements. Further, it
may be appreciated that suction force may be applied during the
initial grasp to assist in the act of grasping.
[0102] Similarly, as illustrated in FIG. 16, another embodiment of
a fixation device 14 is shown similar to the fixation device 14
illustrated in FIG. 3. Again, a leaflet LF is partially grasped
between a proximal element 16 and a distal element 18. In this
embodiment, an adjunct-grasper channel 150 extends through the
shaft 12 for passage of an adjunct-grasper 152 having jaws 154,
however any type of grasping mechanism may be present such as
atraumatic hooks, clamps or claws. The jaws 154 protrude into a
space 146 between the proximal and distal element 16, 18. The
adjunct-grasper 152 may be advanced to grasp the leaflet LF with
the jaws 154 and retracted to pull the leaflet LF inward toward the
shaft 12. Thus, the leaflet LF may be repositioned by manipulation
of the adjunct-grasper 152. It may be appreciated that the same or
an additional adjunct-grasper 152 may be used to reposition a
leaflet between the other proximal and distal elements. Further, it
may be appreciated that the adjunct-grasper 152 may be used during
the initial grasp to assist in the act of grasping.
[0103] FIG. 17 illustrates another embodiment of a fixation device
14 similar to the fixation device 14 illustrated in FIG. 3. Again,
a leaflet LF is partially grasped between a proximal element 16 and
a distal element 18. In this embodiment, a conveyor belt 160 is
disposed within each distal element 18 so that a surface of the
belt 160 contacts the grasped leaflet LF. The conveyor belt 160 is
mounted on one or more rollers 162. Rotation of the rollers 162
moves the conveyor belt 160 which in turn moves the contacted
leaflet LF. For example, clockwise rotation of the rollers 162 may
pull or drag the leaflet LF inwardly toward the shaft 12, as shown.
Similarly, counterclockwise rotation of the rollers 162 may pull or
drag the leaflet LF outwardly. Thus, the leaflet LF may be
repositioned by movement of the conveyor belt 160. It may be
appreciated that conveyor belts 160 disposed within the distal
elements 18 may function independently or in unison. Further, it
may be appreciated that the conveyor belts 160 may be used during
the initial grasp to assist in the act of grasping.
[0104] FIGS. 18A-18B illustrate another embodiment of a fixation
device 14 similar to the fixation device 14 illustrated in FIG. 3
having proximal elements 16 and distal elements 18. In this
embodiment, the proximal elements 16 are connected by a bridge 166
which straddles the shaft 12. Referring to FIG. 18B, once a leaflet
is grasped between the proximal and distal elements 16, 18, a force
may be applied to move the bridge 166 toward the base 69 of the
fixation device 14, as indicated by arrow 168. Due to the curvature
of the proximal elements 16, such movement of the bridge 166 draws
the proximal elements 16 inwardly toward the shaft 12 (as indicated
by arrows 170) which it turn draws the grasped leaflet inwardly
toward the shaft 12. Similarly, force applied to move the bridge
166 away from the base 69 moves the proximal elements 16 outwardly.
Thus, the leaflets may be repositioned by movement of the bridge
166. It may be appreciated that the bridge 166 may move toward the
base 69 due to movement of the distal elements 18 toward the closed
position. Or, the proximal elements 16 may be attached to a cam, or
other suitable element, so as the distal elements 18 close, the
proximal elements 14 are drawn inwardly toward the shaft 12. Thus,
the proximal elements 16 may move while the distal elements 18 are
static, or both the proximal elements 16 and the distal elements 18
may move relative to each other. It may further be appreciated that
in some embodiments, the distal elements 18 may move while the
proximal elements 16 are static.
[0105] FIGS. 19A-19C illustrate an embodiment of a fixation device
14 similar to the fixation device 14 illustrated in FIG. 3 with the
inclusion of a passageway through the shaft 12 for passage of a
pre-grasper 176 as shown. The pre-grasper 176 has a shaft 178 and
jaws 180 disposed near its distal end 182, however any type of
grasping mechanism may be present such as atraumatic hooks, clamps
or claws. Referring to FIG. 19B, the fixation device 14 is advanced
through the mitral valve in an atrial approach as described above
so that the fixation device 14 resides within the ventricle. The
pre-grasper 176 is advanced through the shaft 12 and manipulated to
grasp a portion of one or both of the leaflets LF. The pre-grasper
176 may be steered by any suitable mechanisms, including pullwires,
or the pre-grasper 176 may be pre-formed in a desired
configuration. Further, the pre-grasper 176 may be rotated within
the shaft 12. The pre-grasper 176 may grasp one leaflet or the
pre-grasper 176 may grasp both leaflets, such as in a coapted
orientation, to stabilize the leaflet(s) and/or move the leaflet(s)
to a desired orientation. Once the leaflets are satisfactorily
oriented, the fixation device 14 may be used to grasp the leaflets
LF as illustrated in FIG. 19C. The pre-grasper 176 may then be
released from the leaflets LF and removed by withdrawal through the
passageway in the shaft 12. Alternatively, the pre-grasper 176 can
be left in place to reinforce the fixation of the leaflets.
[0106] In other embodiments the pre-grasper 176 is separately
advanced to the tissue to leaflets LF, such as by a different
approach. FIG. 20 illustrates the fixation device 14 advanced via
an atrial approach and the pre-grasper 176 advanced via a
ventricular approach. Again, the pre-grasper 176 has a shaft 178
and jaws 180 disposed near its distal end 182, however any type of
grasping mechanism may be present such as atraumatic hooks, clamps
or claws. The pre-grasper 176 is advanced and manipulated to grasp
a portion of one or both of the leaflets LF. The pre-grasper 176
may be steered by any suitable mechanisms, including pullwires, or
the pre-grasper 176 may be pre-formed in a desired configuration.
Further, the pre-grasper 176 may be rotated. The pre-grasper 176
may grasp one leaflet or the pre-grasper 176 may grasp both
leaflets, such as in a coapted orientation, to stabilize the
leaflet(s) and/or move the leaflet(s) to a desired orientation.
Once the leaflets are satisfactorily oriented, the fixation device
14 may be used to grasp the leaflet. LF the fixation device 14 is
advanced through the mitral valve in an atrial approach as
described above so that the fixation device 14 resides within the
ventricle. This is typically achieved by passing at least a portion
of the fixation device 14 through the leaflets LF adjacent to the
area of the leaflets grasped by the pre-grasper 176. The
pre-grasper 176 may then be released from the leaflets LF and
removed by withdrawal. Alternatively, the pre-grasper 176 can be
left in place to reinforce the fixation of the leaflets. It may be
appreciated that in other embodiments, the fixation device 14 is
advanced via a ventricular approach and the pre-grasper 176
advanced via an atrial approach.
[0107] FIGS. 21A-21B illustrate embodiments of a fixation device 14
having two single-sided fixation elements 190 joinable by a tether
192. Each single-sided fixation element 190 is comprised of at
least a proximal element 16 and a distal element 18. In some
embodiments, the single-sided fixation element 190 resembles one
half of the fixation device 14 illustrated in FIG. 3. FIG. 21A
illustrates a pair of single-sided fixation elements 190, each
fixation element 190 grasping a leaflet LF between its proximal
element 16 and distal element 18. The fixation elements 190 may be
delivered to the leaflets LF through a delivery catheter 191, each
element 190 connected to an elongate delivery apparatus 193 which
passes through the catheter 191. The fixation elements 190 are also
connected to each other by the tether 192. Once, the fixation
elements 190 have satisfactorily grasped the leaflets LF the
fixation elements 190 may be detached from the delivery apparatuses
193 and left behind to hold the leaflets LF in a desired
orientation via the tether 192. Alternatively, the tether 192 may
be shortened or tensioned to draw the fixation elements 190
together, thereby coapting the leaflets LF. In some embodiments,
such as illustrated in FIG. 21B, the tether 192 comprises a
resilient element, such as a coil or spring, that "self-shortens"
upon release from the catheter 191. Other means of shortening or
tensioning the tether 192 may include applying a suture fastener to
the tether 192, preferred embodiments of which are described and
illustrated in U.S. patent application Ser. No. 10/087,004
(Attorney Docket No. 020489-000500US). In other embodiments, each
one-sided fixation element 190 is attached to an individual tether
which extends through the catheter 191. The individual tethers may
then be knotted together, the knot being pushed toward the fixation
elements 190 so as to tie them together at a desired distance.
[0108] Thus, the fixation elements 190 may be linked, attached,
coupled or joined together to hold the leaflets LF in the coapted
position. It may be appreciated that any number of single-sided
fixation elements 190 may be used, some or all of which may be
joinable by one or more tethers 192. Further, it may be appreciated
that at least one of the single-sided fixation elements 190 may be
used to grasp tissues other than valve leaflets, such as chordae,
to assist in treatment of the valve. For example, the elements 190
may join leaflet to leaflet, leaflet to papillary muscle, leaflet
to chordae, etc. Still further, it may be appreciated that each of
the single-sided fixation elements 190 may be deployed from
opposite sides of the valve, such as from an atrial approach and a
ventricular approach, and joined across the valve. Thus, one
single-sided fixation element 190 may be deployed on an anterior
side of the valve and one on a posterior side of the valve, the
elements 190 then cinched together to correct regurgitation.
[0109] FIG. 22 illustrates an embodiment of a fixation device 14
similar to the fixation device 14 illustrated in FIG. 3, including
proximal elements 16 and distal elements 18. However, in this
embodiment, the distal elements 18 are "self-engaging". The
fixation device 14 may be positioned within the mitral valve so
that the distal elements 18 are disposed within the ventricle and
the proximal elements 16 are disposed within the atrium, as
illustrated in FIG. 22. Rather than engaging the leaflets LF with
the distal elements 18 and then lowering the proximal elements 16
to grasp the leaflets LF therebetween, the proximal elements 16 are
first lowered to engage the leaflets LF. Lowering of the proximal
elements 16 may stabilize the leaflets LF and reduce possible
upward motion or flailing of the leaflets LF. The distal elements
18 may then self-engage or automatically move toward a closed
position to engage the leaflets LF and grasp the leaflets LF
between the proximal and distal elements 16, 18. Self-engagement
may be actuated by a variety of mechanisms, including a mechanism
that signifies lowering of the proximal elements 16 to a
predetermined position or a sensor that senses sufficient
engagement of the proximal elements 16 with the leaflets LF. It may
be appreciated that the method of lowering the proximal elements 16
prior to engagement of the distal elements 18 may be utilized with
the fixation device 14 of FIG. 3 without automatic engagement of
the distal elements 18.
[0110] Once the leaflets have been grasped, a variety of features
may assist in holding the grasped leaflets within the fixation
device. For example, FIG. 23 illustrates an embodiment of a
fixation device 14 having suction to maintain leaflet position
after grasping, particularly during movement of the distal elements
18 toward a closed position. In this embodiment, suction lines 200
extend to suction ports 202 disposed on the engagement surfaces 50
of the distal elements 18. The suction lines 200 extend through the
fixation device to a vacuum source similarly to the embodiment
illustrated in FIG. 15. Once the distal elements 18 engage the
leaflets with the engagement surfaces 50, suction applied through
the suction ports 202, assists to hold the leaflets against the
engagement surfaces 50. Such suction may be applied prior to,
during and/or after lowering of any proximal elements 14 to hold
the leaflets therebetween. As mentioned, such suction may be
particularly helpful in securing the leaflets within the fixation
device 14 during movement of the distal elements 18 toward a closed
position.
[0111] In another example, FIGS. 24A-24B illustrate an embodiment
of a fixation device 14 having extended frictional accessories. As
described previously, the proximal elements 16 optionally include
frictional accessories, frictional features or grip-enhancing
elements to assist in grasping and/or holding the leaflets. And, as
described and illustrated in FIG. 5B, the frictional accessories
may comprise barbs 60 having tapering pointed tips extending toward
engagement surfaces 50. FIG. 24A illustrates proximal elements 16
having extended barbs 206 which are directed toward engagement
surfaces 50 of the distal elements 18. Likewise, FIG. 24B provides
a closer view of the barbs 206 on the proximal elements 16 of FIG.
24A. As shown, the length L is extended. Such extended barbs 206
may be comprised of any suitable material, including rubber,
flexible or rigid polymers or various metals. In preferred
embodiments, the extended barbs 206 are atraumatic, the additional
length L providing increased surface area to hold the leaflets with
frictional forces.
[0112] FIGS. 25A-25B illustrate an embodiment of a fixation device
14 having a textured gripping surface 212 to assist in holding the
grasped leaflets within the fixation device 14. An embodiment of
the textured gripping surface 212 is illustrated in FIG. 25A. The
surface 212 includes a plurality of protrusions 214 which extend
outwardly at an angle. The protrusions may be comprised of any
suitable material, preferably flexible material such as silicones,
polymers, or fibers. The protrusions 214 are angled in a
substantially uniform direction to provide friction against an
object moving in the opposite direction. The textured gripping
surface 212 may be applied to any suitable portion of the fixation
element 14, such as the proximal elements 14 or the engagement
surfaces 50 of the distal elements 18. FIG. 25B illustrates a
fixation element 14 having the textured gripping surface 212 on a
covering 210 over the distal elements 18. The covering 210 may be
present to promote tissue growth. In this embodiment, the covering
comprises a biocompatible fabric cover positioned over the distal
elements 18. The covering 210 may optionally be impregnated or
coated with various therapeutic agents, including tissue growth
promoters, antibiotics, anti-clotting, blood thinning, and other
agents. Alternatively or in addition, the covering 210 may be
comprised of a bioerodable, biodegradable or bioabsorbable material
so that it may degrade or be absorbed by the body after the
repaired tissues have grown together. It may be appreciated that
such a covering 210 may cover the distal elements 18 and/or
proximal elements 16 of any of the fixation devices 14 described
herein. The textured gripping surface 212 is shown disposed on the
covering 210 which covers the engagement surfaces 50. The
protrusions 214 are angled toward the shaft 12 of the fixation
device 14. Therefore, leaflet LF may be drawn toward the shaft 12
in the same direction as the protrusions 214 encountering minimal
friction. However, leaflet LF' moving away from the shaft 12
encounters significant friction from the protrusions 214 as the
protrusions 214 are engaged and resist movement of the leaflet LF'.
Thus, the textured gripping surface 212 resists movement of the
leaflets away from the shaft 12, assisting in holding the grasped
leaflets within the fixation device 14.
[0113] FIGS. 26A-26B illustrate another embodiment of a fixation
device 14 having a textured gripping surface 212 to assist in
holding the grasped leaflets within the fixation device 14. In this
embodiment, the surface 212 includes a plurality of protrusions 214
which extend outwardly at an angle. The protrusions may be
comprised of any suitable material, preferably a rigid material
capable of piercing into and/or through the leaflet. Therefore, the
protrusions may also be pointed or sharpened. The textured gripping
surface 212 may be applied to any suitable portion of the fixation
element 14, preferably the engagement surfaces 50 of the distal
elements 18. FIG. 26A shows leaflets LF grasped by the distal
elements 18, the protrusions 214 extending through the leaflets LF
which assist in holding the leaflets LF in place. The proximal
elements 16 may then be released, grasping the leaflets LF between
the proximal and distal elements 16, 18. In some embodiments, the
proximal elements 16 apply force to the protrusions 214, bending
the protrusions 214 toward the engagement surfaces 50 so that the
protrusions 214 "staple" the leaflets LF to the engagement surfaces
50, as illustrated in FIG. 26B. Alternatively, the protrusions 214
may have barbed or arrowhead shaped tips which may similarly act to
staple the leaflets LF to the engagement surfaces 50.
IV. Grasping Assessment
[0114] Once the tissue or leaflets have been grasped, it is often
desired to evaluate or assess the quality of the grasp, such as the
amount of purchase, orientation of the tissues, and likelihood that
the fixation device will maintain the grasp over time. Thus, a
variety of devices and techniques are provided to assess the grasp.
It may be appreciated that the assessment devices and techniques
may be used in combination with the above described fixation
devices or may be used with any suitable grasping and/or fixing
device. Further, many of such assessment devices and techniques may
be used to assess grasping of valve leaflets, or other tissues, for
any purpose.
[0115] One method of determining quality of grasp is to visualize
the grasp by means of fluoroscopy, ultrasound, echocardiography or
other known visualization techniques. Using these techniques, a
physician or practitioner may be able to observe an image of the
fixation device and the grasped tissue to determine if the grasp is
desirable. The fixation device may be visually differentiated from
the surrounding tissue by enhancing the visibility of portions of
the surrounding tissue, particularly the tissue intended to be
grasped, such as the valve leaflets. Thus, as illustrated in FIGS.
27A-27B, the leaflets LF may be injected with a substance which
enhances visibility prior to and/or after grasping with the
fixation device. Example substances include liquid contrast
material or bioabsorbable polymer beads having air bubbles trapped
within. As shown in FIG. 27A, an injection catheter 220 having a
needle 222 may be advanced to the leaflet LF to inject the
substance. Exemplary injection catheters are described in U.S. Pat.
Nos. 6,685,648; 4,578,061; 6,540,725; 6,165,164. FIG. 27B
illustrates a leaflet LF having the substance 224 injected therein
(as indicated by shading) and another leaflet being injected by the
needle 222 of the injection catheter 220.
[0116] Alternatively, portions of the fixation device may have
enhanced visibility to differentiate the fixation device from the
surrounding tissue. For example, FIG. 28 illustrates a fixation
device 14 wherein the proximal elements 16 and distal elements 18
have enhanced visibility, as indicated by shading. Such enhanced
visibility may assist differentiation of the proximal and distal
elements 16, 18 from valve leaflets LF captured therebetween.
Further, the practitioner may be able to determine where the
leaflet edges E are located with respect to the proximal and distal
elements 16, 18, e.g. how closely the edges E are to the shaft 12
of the fixation element 14. This may indicate the size of the
purchase. In some embodiments, surfaces of the fixation device are
roughened, such as by bead blasting, to enhance visibility such as
echogenicity. In other embodiments, at least portions of the
fixation device 14 have an enhanced visibility covering. Such a
covering may be comprised of cloth having titanium threads, spun
polyester or other material which provides echogenicity.
Alternatively or in addition, the covering may be stamped or
impregnated with materials which provide echogenicity, such as
barium sulfate. Or, the visibility of the covering may be enhanced
by a bulky appearance of the covering.
[0117] In some embodiments, the fixation device includes an
ultrasound receiving indicator. The ultrasound receiving indicator
is typically disposed along a proximal or distal element near a
target area. The indicator is used to determine the presence or
absence of tissue within the target area thereby assessing the
quality of the grasp. The indicator comprises a chip or other
device that resonates or vibrates at a specific ultrasonic
frequency which differs from the general frequency used to
visualize the remainder of the fixation device and the surrounding
tissue. Therefore, when the specific ultrasonic frequency is used
for visualization, the indicator provides a bright visual artifact
on an echocardiogram image. This indicates that the tissue is not
sufficiently grasped within the target area because the indicator
is freely vibrating. However, if the tissue is compressed between
the proximal and distal elements within the target area, the tissue
compresses the indicator, reducing or damping the vibration of the
indicator. Thus, if the bright visual artifact is not seen at the
specific ultrasonic frequency, it may be determined that the tissue
is sufficiently grasped within the target area of the fixation
device. This allows the practitioner to actively evaluate the grasp
by viewing a dynamic change in the image being viewed at the time
of interrogation with the specific ultrasonic frequency.
[0118] Alternatively, the indicator may comprise a chip or other
device that resonates at the same general frequency used to
visualize the remainder of the fixation device and the surrounding
tissue. When the general frequency is used for visualization, the
indicator provides a bright visual artifact on an echocardiogram
image. This indicates that the tissue is not sufficiently grasped
within the target area because the indicator is freely vibrating.
Again, if the tissue is compressed between the proximal and distal
elements within the target area, the tissue compresses the
indicator, reducing or damping the vibration of the indicator.
Thus, if the bright visual artifact is not seen at the general
ultrasonic frequency, it may be determined that the tissue is
sufficiently grasped within the target area of the fixation device.
This allows the practitioner to evaluate the grasp by viewing more
static images of the echocardiogram. It may be appreciated that the
above described ultrasound receiving indicators may both be used
with real time ultrasonic images, however one allows evaluation of
the grasp based on viewing a dynamic change in an image due to
interrogation with a specific ultrasonic frequency and the other
allows evaluation of the grasp based on viewing a more static image
at a general ultrasonic frequency.
[0119] In other embodiments, the fixation device includes a
magnetic indicator. The magnetic indicator is typically disposed
along a proximal or distal element near a target area. The
indicator is used to determine the presence or absence of tissue
within the target area thereby assessing the quality of the grasp.
The indicator comprises a device, such as a ball bearing, that is
movable when a magnetic field is applied. Such a magnetic field may
be locally applied, such as by a catheter, or globally applied,
such as by magnetic resonance imaging. Movement of the indicator
may be visualized by any suitable medium, such as fluoroscopy. Such
movement indicates that the tissue is not sufficiently grasped
within the target area because the indicator is freely movable.
However, if the tissue is compressed between the proximal and
distal elements within the target area, the tissue compresses the
indicator, reducing or damping the movement of the indicator. Thus,
if movement is reduced or not seen when the magnetic field is
applied, it may be determined that the tissue is sufficiently
grasped within the target area of the fixation device. This allows
the practitioner to actively evaluate the grasp.
[0120] In other embodiments, the position of a grasped leaflet
within a fixation device may be determined based on the visibility
of frictional elements. Such frictional elements typically have an
observable shape, such as barbs, and are coated or comprised of an
enhanced visibility material. FIG. 29 illustrates a fixation device
14 having such barbs 60 disposed on the proximal elements 16 as
frictional elements. In this embodiment, the proximal elements 16
have a visually opaque or semi-opaque covering 230 which cover the
barbs 60. The covering 230 may be comprised of, for example, fibers
made from gold or platinum wire or polymer fibers coated or
sputtered for radiopacity. When a leaflet LF is grasped and
captured between the proximal element 16 and distal element 18, the
leaflet LF presses the covering 230 against the proximal element 16
causing the barbs 60 to extend through the covering 230. The
exposed barbs 60 are visibly observable by visualization
techniques. The quantity and location of visible barbs 60 indicates
the position of the grasped leaflet. For example, when a leaflet
LF' is grasped and partially captured between the proximal element
16' and distal element 18', only a portion of the barbs 60 (such as
single barb 60') are exposed. Thus, the low quantity and outward
location of the visible barb 60' indicate that the leaflet LF is
not fully captured. The leaflet LF may then be released and
regrasped.
[0121] In still other embodiments, the position of a grasped
leaflet within a fixation device may be determined based the
visible shape of the proximal elements 16. In such embodiments, the
proximal elements 16 may be comprised of segmental parts separated
by hinges or flexible areas 240, as illustrated in FIG. 30. The
proximal elements 16 are coated or comprised of an enhanced
visibility material. When a leaflet LF is grasped and fully
captured between the proximal element 16 and distal element 18, the
proximal element 16 has a shape which substantially follows the
contour of the distal element 18. When a leaflet LF' is grasped and
partially captured between the proximal element 16' and distal
element 18', the proximal element 16' may flex at a flexible area
240 near an edge E' of the partially captured leaflet LF'. The
proximal element 16' may also flex due to a variety of other
misorientations of the grasped leaflet LF'. Visualization of the
shape of the segmental proximal element indicates the locations in
which irregularities occur which may indicate how much of the
leaflet has been captured. If the leaflet is not desirably
captured, the leaflet LF may then be released and regrasped.
[0122] In additional embodiments, the position of a grasped leaflet
within a fixation device may be determined based the visibility of
an indicator associated with the distal elements 18. For example,
FIGS. 31A-31B illustrate an embodiment of a fixation device 14
having a distal element 18 which includes a flap 240. The flap 240
has an attached end 242 which is attached to the engagement surface
50 or a portion of the distal element 18 and a free end 244 which
extends toward the proximal element 16. The flap 240 forms an angle
.theta. with the engagement surface 50. The flap 240 is typically
flexible or is attached so that the flap 240 is able to move
throughout the angle .theta.. The flap 240 is coated or comprised
of an enhanced visibility material so that the practitioner may
observe the flap 240 and its angle .theta. by visualization
techniques. In preferred embodiments, the distal element 18 is also
coated or comprised of an enhanced visibility material. Prior to
grasping a tissue, such as a leaflet, the flap 240 is fully visible
and is positioned having a maximum angle .theta., as illustrated in
FIG. 31A. When a leaflet LF is grasped between the proximal and
distal elements 16, 18, the leaflet LF presses the flap 240 toward
the engagement surface 50. When the leaflet LF is fully captured,
the leaflet LF may press the flap 240 so that it is parallel with
or uniform with the engagement surface 50, as illustrated in FIG.
31B. Thus, the lack of observable flap 240 may be an indicator that
the leaflet LF has been satisfactorily grasped. Alternatively, the
practitioner may be able to determine the extent of grasp or
purchase based on the angle .theta.. For example, flap 240 having
an angle (.theta./2) may indicate that the leaflet LF only extends
half way along the engagement surface 50. If this is not desirable,
the leaflet LF may then be released and regrasped. It may be
appreciated that the flap 240 may have any suitable shape, size or
location, including location on a proximal element 16 or any other
suitable element. Further, more than one flap 240 may be
present.
[0123] FIGS. 32A-32C illustrate another embodiment wherein the
position of a grasped leaflet within a fixation device may be
determined based the visibility of an indicator associated with the
distal elements 18. Here the indicator comprises a floating block
248 associated with the distal element 18. The floating block 248
is coupled with the distal element 18 so that it may pass through
the distal element 18 upon application of force. The block 248 is
coated or comprised of an enhanced visibility material so that the
practitioner may observe the block 248 by visualization techniques.
In preferred embodiments, the distal element 18 is also coated or
comprised of an enhanced visibility material. Typically, the block
248 biased, such as spring biased, so that the block 248 is raised
toward the proximal element 14, as illustrated in FIG. 32A, prior
to grasping a tissue, such as a leaflet. When a leaflet LF is
grasped between the proximal and distal elements 16, 18, the
leaflet LF presses the block 248 toward the engagement surface 50.
When the leaflet LF is partially captured, as illustrated in FIG.
32B, a portion of the block 248 may be visible raised from the
engagement surface 50 and a portion may be visible extending from
the opposite side. The practitioner may determine the position of
the leaflet LF based on the rotation point of the block 248. When
the leaflet LF is fully captured, as illustrated in FIG. 32C, the
leaflet LF may move the block 248 so that it is fully passed
through the distal element 18 and extends outwardly from the
opposite side. Thus, the practitioner may determined the
desirability of the grasp based on the position of the floating
block 248. It may be appreciated that the block 248 may have any
suitable shape, size or location including location on a proximal
element 16 or any other suitable element. Further, more than one
block 248 may be present.
[0124] FIG. 33 illustrate an embodiment wherein the indicator
comprises a bladder or reservoir 249 associated with the distal
element 18. The reservoir 249 is coupled with the distal element 18
so that it may pass through the distal element 18 upon application
of force. The reservoir 249 is filled with an enhanced visibility
material so that the practitioner may observe the reservoir 249 by
visualization techniques. Typically, the reservoir 249 is
positioned so that it is raised toward the proximal element 14, as
illustrated in the left side of FIG. 33, prior to grasping a
tissue, such as a leaflet LF. When a leaflet LF is grasped between
the proximal and distal elements 16, 18, as illustrated in the
right side of FIG. 33, the leaflet LF presses the reservoir 249
toward the engagement surface 50. When the leaflet LF is partially
captured, a portion of the reservoir 249 may be visible raised from
the engagement surface 50 and a portion may be visible extending
from the opposite side. The practitioner may determine the position
of the leaflet LF based on the position of the reservoir 249. When
the leaflet LF is fully captured, the leaflet LF may move the
reservoir 249 so that it is fully passed through the distal element
18 and extends outwardly from the opposite side. Thus, the
practitioner may determined the desirability of the grasp based on
the position of the reservoir 249.
[0125] Similarly, as illustrated in FIGS. 34A-34B, the reservoir
249 may have particular size, shape, and/or location so that when
both reservoirs 249 are appropriately displaced (indicating both
leaflets satisfactorily grasped) the reservoirs 249 may come
together to form a distinctive size or volume, as illustrated in
FIG. 34B. This may indicate to the practitioner that the leaflets
LF are desirably grasped. It may be appreciated that the reservoirs
249 of FIG. 33 and FIGS. 34A-34B may have any suitable shape, size
or location including location on a proximal element 16 or any
other suitable element. Further, more than one reservoir 249 may be
present.
[0126] FIG. 35 illustrates another embodiment wherein the position
of a grasped leaflet within a fixation device may be determined
based the visibility of an indicator associated with the distal
elements 18. Here the indicator comprises one or more loops 251,
such as wire loops, associated with the distal element 18. The
loops 251 are coupled with the distal element 18 so that the loops
251 may pass through the distal element 18 upon application of
force. The loops 251 are coated or comprised of an enhanced
visibility material so that the practitioner may observe the loops
251 by visualization techniques. Typically, the loops 251 are
biased, such as spring biased, so that the loops 251 are raised
toward the proximal element 14, as illustrated in the left side of
FIG. 35, prior to grasping a tissue, such as a leaflet LF. When a
leaflet LF is grasped between the proximal and distal elements 16,
18, the leaflet LF presses the loops 251 toward the engagement
surface 50. When the leaflet LF is fully captured, as illustrated
in the right side of FIG. 35, the leaflet LF may move the loops 251
so that they are fully passed through the distal element 18 and
extend outwardly from the opposite side. Thus, the practitioner may
determine the desirability of the grasp based on the position of
the loops 251. It may be appreciated that the loops 251 may have
any suitable shape, size or location including location on a
proximal element 16 or any other suitable element.
[0127] FIGS. 36A-36B illustrate another embodiment wherein the
position of a grasped leaflet within a fixation device may be
determined based the visibility of an indicator associated with the
distal elements 18. Here the indicator comprises at least one
slackline 265, such a wire, suture, thread, filament, polymer, or
strand, which extends around portions of the fixation device 14. In
this embodiment, as shown in FIG. 36A, the slackline 265 extends
through a lumen in catheter 86 and along the shaft 12 toward the
base 69 of the fixation device 14. The slackline 265 then extends
around a free end 54' of one of the distal elements 18' and
continues across to a free end 54'' of the opposite distal element
18'', creating an indicator segment 265a between the distal
elements 18', 18''. The slackline 265 then extends toward the base
69 and returns along the shaft 12 to another lumen (or the same
lumen) in catheter 86. The slackline 265 is coated or comprised of
an enhanced visibility material so that the practitioner may
observe the slackline 265 by visualization techniques. The
slackline 265 also has sufficient slack to allow movement of at
least the indicator segment 265a when force is applied, such as by
a leaflet. FIG. 36B illustrates the fixation device 14 of FIG. 36A
wherein a pair of leaflets LF are desirably grasped. Here,
desirable positioning of the leaflets between the proximal elements
16', 16'' and distal elements 18', 18'' forces the indicator
segment 265a into a different configuration, in this case lowering
the indicator segment 265a. Thus, the practitioner may determine
the desirability of the grasp based on the position of the
indicator segment 265a. It may be appreciated that the indicator
segment 265a and/or the slackline 265 may have any configuration,
and more than one slackline 265 may be present.
[0128] In other embodiments, the position of one or more leaflets
LF within the fixation device 14 may be determined or verified
prior to releasing of the proximal elements 16. For example, FIG.
37A illustrates an embodiment of a fixation device 14 having
mini-grippers 263 which may be shaped similarly to the proximal
elements 16 yet are smaller in size. Each mini-gripper 263 is
disposed between a set of proximal and distal elements 16, 18. The
fixation device 14 is positioned to so that the leaflets are
engaged by the engagements surfaces 50 of the distal elements 18.
The mini-grippers 263 are then released, each extending radially
outwardly from the shaft 12 a short distance along the engagement
surfaces 50 of the distal elements 18. It may be appreciated that
the mini-grippers 263 may be released independently or
simultaneously. If the mini-grippers 263 grasp the leaflets, it may
be determined that the leaflets are adequately positioned within
the fixation device 14 since such grasping indicates that the
leaflets extend to a desired distance relative to the shaft 12.
Once desired grasping of the leaflets is determined, the proximal
elements 16, may be released to grasp the leaflets between the
proximal and distal elements 16, 18. The mini-grippers 263 may
remain in place or be removed.
[0129] Alternatively, both the mini-grippers 263 and the proximal
elements 16 may be deployed simultaneously. The proximal elements
16 may then be raised or released while the mini-grippers 263
remain deployed, thereby confirming whether the leaflets are still
held by the mini grippers 263. If the mini-grippers 263 still hold
the leaflets, it may be determined that the leaflets are adequately
positioned within the fixation device 14 since such grasping
indicates that the leaflets extend to a desired distance relative
to the shaft 12. Once desired grasping of the leaflets is
determined, the proximal elements 16, may be re-released to grasp
the leaflets between the proximal and distal elements 16, 18. The
mini-grippers 263 may remain in place or be removed.
[0130] In yet other embodiments, as illustrated in FIG. 37B, the
mini-grippers 263 may extend through a window 265 or space in the
distal elements 18 if the released mini-grippers 263 do not contact
the leaflets in the target area. Thus, visualization of the
mini-grippers 263 extending beyond the distal elements 18, as
shown, indicates that the leaflets have not been desirably grasped.
Such visualization may be achieved prior to or after release of the
proximal elements 16. When the mini-grippers 263 are released
simultaneously with the proximal elements 16, such visualization
allows grasping assessment to be achieved without additional
movement of the proximal elements 16.
[0131] In other embodiments, the position of a grasped leaflet
within a fixation device may be determined based the visibility of
a released substance which is visible under visualization
techniques, such as liquid contrast material or bioabsorbable
polymer beads having air bubbles trapped within. In one embodiment
illustrated in FIG. 38A, the substance 258 is contained in a
bladder or reservoir 260 within the distal element 18. When a
leaflet LF is grasped between the proximal and distal elements 16,
18, the leaflet LF presses the reservoir 260 releasing the
substance 258 through ports 262, as illustrated in FIG. 38B. The
ports 262 may be disposed along the length of the distal element 18
so that the substance 258 is expelled through the ports 262 only in
the areas where the leaflet LF is engaged. Therefore, the
practitioner may be able to determine the extent of grasp or
purchase based on the location and/or amount of expelled substance
258. It may be appreciated that the reservoir 260 may have any
suitable shape, size or location, including location on a proximal
element 16 or any other suitable element. Further, more than one
reservoir 260 may be present.
[0132] Another embodiment, illustrated in FIGS. 39A-39B, the
position of a grasped leaflet LF within a fixation device 14 is
also determined based the visibility of a released substance which
is visible under visualization techniques, such as liquid contrast
material or bioabsorbable polymer beads having air bubbles trapped
within. Here, the substance 258 is released through a lumen 270
which extends through the shaft 12 of the fixation device 14 and
through an conduit 272, as illustrated in FIG. 39A. The conduit 272
is directed toward a target area of the engagement surface 50 of
the distal element 18. The target area is positioned so that a
grasped leaflet LF covering the target area is considered
sufficiently grasped. When a leaflet LF covers the target area, as
illustrated in FIG. 39A, the released or injected substance 258 is
blocked by the leaflet LF. Such blockage may either prevent
injection of the substance 258, cause injection of the substance
258 into the leaflet LF, or allow some visibility of the substance
258 on the side of the leaflet LF receiving the injected substance
258. Thus, the practitioner may determine that the leaflet LF is
satisfactorily grasped due to the lack of or reduced quantity of
substance 258 or the location of the injected substance 258 (i.e.
within the leaflet or on the side of the leaflet receiving the
injected substance 258). When a leaflet LF does not cover the
target area, as illustrated in FIG. 39B, the released or injected
substance 258 is not blocked by the leaflet LF. Therefore, the
substance 258 will be injected into the area between the proximal
and distal elements 16, 18 and is free to extravagate into the
circulation. Thus, the practitioner may determine that the leaflet
LF is not satisfactorily grasped due to the visibility of
extravagated substance 258. It may be appreciated that the conduit
272 may have a variety of forms, sizes and orientations and may be
directed toward a variety of target areas. Further, more than one
conduit 272 may be present. It may also be appreciated that
needles, tubes or other instruments may be advanced through the
conduit 272 to deliver the substrate or for any other purpose.
[0133] It may also be appreciated that the above described lumen
270 and conduit 272 may alternatively be used to draw suction. When
a leaflet LF covers the target area, as illustrated in FIG. 39A,
suction drawn through the conduit 272 will cause the leaflet LF to
press against the conduit 272 preventing blood from entering the
conduit 272. However, when a leaflet LF does not cover the target
area, blood will be suctioned up through the conduit 272.
Therefore, the practitioner may determine whether the leaflet LF is
satisfactorily grasped based on the presence of blood suctioned
through the conduit 272.
[0134] Similarly, an embodiment, illustrated in FIGS. 40A-40B, is
provided having a lumen 270 which extends through the shaft 12 of
the fixation device 14 and through a conduit 272. Again, the
conduit 272 is directed toward a target area of the engagement
surface 50 of the distal element 18. The target area is positioned
so that a grasped leaflet LF covering the target area is considered
sufficiently grasped. In this embodiment, a probe 280 is
advanceable through the lumen 270. In addition, the probe 280 is
connected with an insertion depth gauge 282 so that the
practitioner is able to determine the advancement distance of the
probe 280. When a leaflet LF covers the target area, as illustrated
in FIG. 40A, the probe 280 may only be advanced until it contacts
the leaflet LF. Thus, the practitioner may determine that the
leaflet LF is satisfactorily grasped due to the minimal advancement
distance indicated by the insertion depth gauge 282. When a leaflet
LF does not cover the target area, as illustrated in FIG. 40B, the
probe 280 is able to advance further toward the distal element 18.
Thus, the practitioner may determine that the leaflet LF is not
satisfactorily grasped due to the advancement distance. Again, it
may be appreciated that the conduit 272 may have a variety of
forms, sizes and orientations and may be directed toward a variety
of target areas. Further, more than one conduit 272 may be
present.
[0135] Similarly, as illustrated in FIGS. 41A-41F, detectable
elements 281 may extend from the shaft 12 of the fixation device
14. In FIGS. 41A-41B, the detectable elements 281 are coupled with
the proximal elements 16 so that release of each proximal element
16 draws an associated detectable element 281 toward a target area
of the engagement surface 50 of the associated distal element 18.
Each target area is positioned so that a grasped leaflet LF
covering the target area is considered sufficiently grasped. When a
leaflet LF' covers its corresponding target area, as illustrated in
the left side of FIG. 41A, the detectable element 281' contacts the
leaflet LF'. When a leaflet LF'' does not cover its corresponding
target area, as illustrated in the right side of FIG. 41A, the
detectable element 281'' is able to advance toward the target area,
extending a further distance than if a leaflet were present. The
detectable elements 281', 281'' are comprised of a detectable
material or coating, such as a material which is detectable by
fluoroscopy, conductance or impedance signal. Therefore, the
practitioner is able to detect the position of the detectable
elements 281', 281'' and consequently determine if the leaflets are
desirably grasped, as illustrated in FIG. 41B. The detectable
elements 281', 281'' are then released from the proximal elements
16 and removed upon detachment of the fixation device 14. It may be
appreciated that the detectable elements 281 may be individually
extendable from the shaft 12 (i.e. not coupled with the proximal
elements 16). Also, in other embodiments, the detectable elements
281 may form a circuit when contacting the engagement surface 50 of
the associated distal element 18. For example, when a leaflet LF'
covers its corresponding target area, the detectable element 281'
contacts the leaflet LF', such as illustrated above in the left
side of FIG. 41A. Thus, the detectable element 281' does not
contact the engagement surface 50 and the circuit remains open.
When a leaflet LF'' does not cover its corresponding target area,
such as illustrated in the right side of FIG. 41A, the detectable
element 281'' is able to advance toward the target area and contact
the engagement surface, completing the circuit. The integrity of
the circuit may be detected by any suitable device, such as an
ohmmeter or an ammeter, thereby indicating if the leaflets are
desirably grasped.
[0136] In FIGS. 41C-41D, the detectable elements 281 are each
advanceable from the shaft 12 toward a target area of the
engagement surface 50 of its associated distal element 18. When a
leaflet LF' covers its corresponding target area, as illustrated in
the left side of FIG. 41C, the detectable element 281' contacts the
leaflet LF' and creates a first shape. When a leaflet LF'' does not
cover its corresponding target area, as illustrated in the right
side of FIG. 41C, the detectable element 281'' is able to advance
toward the target area, creating a second shape which differs from
the first shape. The detectable elements 281', 281'' are comprised
of a detectable material or coating, such as a material which is
detectable by fluoroscopy or by impedance signal. Therefore, the
practitioner is able to detect the shapes of the detectable
elements 281. When both leaflets are desirably grasped, both
detectable elements 281', 281'' will substantially form the first
shape, as illustrated in FIG. 41D.
[0137] In FIGS. 41E-41F, a single detectable element 281 is
advanceable from the shaft 12 toward target areas of the engagement
surfaces 50 of the distal elements 18. When a leaflet LF' covers
its corresponding target area, as illustrated in the left side of
FIG. 41E, a portion 283' of the detectable element 281 contacts the
leaflet LF' and creates a first shape. When a leaflet LF'' does not
cover its corresponding target area, as illustrated in the right
side of FIG. 41F, a portion 283'' of the detectable element 281 is
able to advance toward the target area, creating a second shape
which differs from the first shape. The detectable element 281 is
comprised of a detectable material or coating, such as a material
which is detectable by fluoroscopy or by impedance signal.
Therefore, the practitioner is able to detect the shape of the
portions 283' 283'' of the detectable element 281. When both
leaflets are desirably grasped, both portions 283' 283'' of the
detectable element 281 will substantially form the first shape, as
illustrated in FIG. 41F, creating a symmetrical shape.
[0138] In some embodiments, the fixation device includes one or
more sensors to determine the position of a grasped tissue.
Typically, the sensor determines the presence or absence of tissue
on or near the sensor. For example, FIGS. 42A-42B illustrate a
fixation device 14 having at least one sensor 290 disposed on or
within a distal element 18. In this embodiment, the sensor 290 is
positioned near the shaft 12 to determine if a grasped leaflet LF
is fully inserted into the fixation device 14 or only partially
inserted. As shown in FIG. 42A, the sensor 290 may emit a first
signal 292 when the leaflet LF is not detected near the sensor 290
indicating that the leaflet LF is not fully engaged. When the
leaflet LF is fully engaged, as illustrated in FIG. 42B, the sensor
290 detects the leaflet LF near the sensor 290 and emits a second
signal 294, which differs from the first signal 292. The sensor 290
may have any suitable form, such as a conductor, a strain gauge, a
radiosensor, an optical sensor, an ultrasound sensor, an infrared
sensor, an electrical resistance sensor, an intravascular
ultrasound (IVUS) sensor or a pressure sensor, to name a few.
Alternatively, the sensor 290 may comprise a resonating sensor that
responds to magnetic energy in the fixation device 14 to indicate
leaflet insertion. For example, magnetic energy may be applied to
the fixation device 14 wherein the sensor 290 does not resonate or
is not activated if the leaflet is not sufficiently inserted. It
may be appreciated that any number of sensors 290 may be present
and may be disposed on or within any element, including the
proximal elements 16. FIG. 43 illustrates a fixation device 14
having sensors 290 which extend into a target area between the
proximal and distal elements 16, 18.
[0139] FIGS. 44A-44B illustrate a fixation device 14 having sensors
290', 290'' positioned on the shaft 12. In this embodiment, the
sensors 290', 290'' emit ultrasound signals toward a portion of the
distal elements 18 near the shaft 12. In FIG. 44A, leaflet LF'' is
not detected by the sensor 290'' since the leaflet LF'' is not
grasped between the corresponding proximal and distal elements 16,
18 and the leaflet LF'' does not extend into the path of the
emitted signals. The practitioner may then reposition the fixation
device 14. FIG. 44B illustrates a fixation device 14 having both
leaflets LF', LF'' desirably grasped so that both sensors 290',
290'' sense the leaflets LF', LF''.
[0140] It may also be appreciated that sensors may be used to
actuate movement of the fixation device. For example, sensors in
the form of strain gauges may be disposed on each of the distal
elements. Engaging the distal elements with the leaflets applied
tension to the distal elements which is measurable by the strain
gauges. Therefore, when the strain gauges measure a predetermined
quantity, the proximal elements may be automatically lowered to
grasp the leaflets therebetween. It may be appreciated that the
strain gauge measurements may be used to actuate a variety of other
movements or simply indicate to the practitioner that such
movements are acceptable.
V. Fixation Assessment
[0141] Once the quality of the grasp of the tissue has been
assessed, it is often desired to evaluate or assess the quality of
the fixation of the tissue. This can be achieved by evaluating the
improvement in the medical condition being treated. In the case of
valve leaflet fixation, improvement in regurgitation may be
evaluated. It is often desired to assess the fixation prior to
decoupling the fixation device from the delivery catheter so that
the fixation device may be repositioned if the improvement is not
satisfactory. Thus, a variety of devices and techniques are
provided to assess the fixation prior to decoupling the fixation
device from the delivery catheter. It may be appreciated that the
assessment devices and techniques may be used in combination with
the above described fixation devices or may be used with any
suitable grasping and/or fixing device. Further, many of such
assessment devices and techniques may be used to assess fixation
for any purpose.
[0142] FIGS. 45A-45B illustrate an embodiment of devices and
methods for simulating the resultant placement and function of a
fixation device 14 that has been positioned to grasp leaflets LF of
the mitral valve MV. In this embodiment, the fixation device 14 is
delivered to the mitral valve MV by a catheter 86. The fixation
device 14 is removably coupled to a shaft 12 which is passed
through a catheter 86. In addition, a sheath 300 is provided which
passes through the catheter 86 and over the shaft 12 to provide
support while the fixation device 14 is positioned within the valve
MV and the leaflets LF are grasped between the proximal and distal
elements 16, 18. Once the leaflets LF are satisfactorily grasped,
the sheath 300 may be retracted, as illustrated in FIG. 45B.
Retraction of the sheath 300 exposes a flexible linkage 302 which
extends from the shaft 12 to the catheter 86. The flexible linkage
302 allows the fixation device 14 to move freely, mimicking the
behavior of the fixation device 14 after decoupling from the shaft
12. The improvement in regurgitation may then be assessed. If the
improvement is considered unsatisfactory, the sheath 300 may be
advanced to cover the flexible linkage 302 and provide support for
repositioning of the fixation device 14. Upon repositioning, the
sheath 300 may then be retracted and the function of the valve
again assessed. This may be repeated as many times as desired. Once
the improvement is considered satisfactory, the fixation device 14
may be decoupled from the shaft 12.
[0143] Similarly, FIGS. 46A-46B also illustrate an embodiment of
devices and methods for simulating the resultant placement and
function of a fixation device 14 that has been positioned to grasp
leaflets LF of the mitral valve MV. In this embodiment, the
fixation device 14 is delivered to the mitral valve MV by a
catheter 86. The fixation device 14 is removably coupled to a shaft
12 which is passed through a catheter 86. Here, the shaft 12 is
comprised of a flexible structure 306, such as a compression coil,
that is held rigid by a center actuation wire 308. The wire 308 is
held taught to provide support while the fixation device 14 is
positioned within the valve MV and the leaflets LF are grasped
between the proximal and distal elements 16, 18. Once the leaflets
LF are satisfactorily grasped, the wire 308 tension is released to
allow the flexible structure 306 to flex which allows the fixation
device 14 to move freely, mimicking the behavior of the fixation
device 14 after decoupling from the shaft 12. The improvement in
regurgitation may then be assessed. If the improvement is
considered unsatisfactory, the tension may be reapplied to the wire
308 to provide support for repositioning of the fixation device 14.
Upon repositioning, tension may again be released and the function
of the valve assessed. This may be repeated as many times as
desired. Once the improvement is considered satisfactory, the
fixation device 14 may be decoupled from the shaft 12.
[0144] In other embodiments, the fixation device may be decoupled
from the shaft while maintaining a tether, such as a suture line,
to the catheter. This allows the fixation device 14 to be evaluated
while it is decoupled from the shaft but provides assistance in
retrieval of the fixation device for repositioning. The tether may
be present specifically for this purpose, or other elements used in
the positioning of the fixation device 14 may be used as a tether,
such as a lock line 92 or a proximal element line 90.
Alternatively, a snare may be extended from the catheter 86 to
retrieve the fixation device 14. In any case, the fixation device
may be retrieved with the tether, recoupled with the shaft 12 and
repositioned until a satisfactory result is achieved.
[0145] Although the foregoing invention has 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 of the invention which is
defined by the appended claims.
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