U.S. patent application number 16/813591 was filed with the patent office on 2020-07-02 for grasping for tissue repair.
This patent application is currently assigned to ABBOTT CARDIOVASCULAR SYSTEMS INC.. The applicant listed for this patent is ABBOTT CARDIOVASCULAR SYSTEMS INC.. Invention is credited to Michael F. Wei.
Application Number | 20200205831 16/813591 |
Document ID | / |
Family ID | 54361215 |
Filed Date | 2020-07-02 |
United States Patent
Application |
20200205831 |
Kind Code |
A1 |
Wei; Michael F. |
July 2, 2020 |
GRASPING FOR TISSUE REPAIR
Abstract
The invention provides improved devices, systems, and methods
for tissue approximation and repair at treatment sites. The
invention provides devices, systems, and methods that may more
successfully approximate and repair tissue by improving the capture
of tissue into the devices. The invention may be a one-way
mechanism that allows tissue to enter the mechanism but not easily
exit, such as a leaf-spring, a protrusion, a pivoting arm and one
or more frictional elements.
Inventors: |
Wei; Michael F.; (Redwood
City, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ABBOTT CARDIOVASCULAR SYSTEMS INC. |
Santa Clara |
CA |
US |
|
|
Assignee: |
ABBOTT CARDIOVASCULAR SYSTEMS
INC.
SANTA CLARA
CA
|
Family ID: |
54361215 |
Appl. No.: |
16/813591 |
Filed: |
March 9, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16748450 |
Jan 21, 2020 |
|
|
|
16813591 |
|
|
|
|
16241647 |
Jan 7, 2019 |
|
|
|
16748450 |
|
|
|
|
14577852 |
Dec 19, 2014 |
10188392 |
|
|
16241647 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2017/00783
20130101; A61F 2220/0091 20130101; A61B 2017/081 20130101; A61F
2/246 20130101; A61B 17/1285 20130101; A61B 17/122 20130101; A61B
2017/00243 20130101; A61F 2220/0016 20130101; A61B 17/08
20130101 |
International
Class: |
A61B 17/08 20060101
A61B017/08; A61B 17/128 20060101 A61B017/128; A61B 17/122 20060101
A61B017/122 |
Claims
1. A device for fixation of leaflets of a heart valve comprising: a
delivery catheter having a distal end; and a fixation implant
releasably attached to the distal end, the fixation implant
comprising: first and second distal elements moveable between an
open position and a closed position, each distal element extending
outwardly from a center of the fixation implant in the open
position; a first retaining element attached to the first distal
element; a second retaining element attached to the second distal
element; a first proximal element movable to capture a first
leaflet of the heart valve between the first proximal element and
the first retaining element; and a second proximal element moveable
to capture a second leaflet of the heart valve between the second
proximal element and the second retaining element, wherein the
first and second distal elements are configured to cover the first
and second retaining elements, respectively, in the closed
position.
2. The device of claim 1, wherein each proximal element includes a
plurality of friction elements.
3. The device of claim 2, wherein the plurality of friction
elements comprises a plurality of barbs.
4. The device of claim 2, wherein each of the first and second
retaining elements is configured to cooperate with the plurality of
friction elements of the respective proximal element to allow a
leading free edge of the first leaflet of the heart valve and the
second leaflet of the heart valve, respectively, to move freely in
a first direction toward the center of the fixation implant and to
restrict movement of the free edge of the respective first and
second leaflet of the heart valve in a second direction opposite
the first direction.
5. The device of claim 1, further comprising at least two sutures
configured to raise and lower each of the first and second proximal
elements relative the first and second retaining elements,
respectively.
6. The device of claim 1, wherein each of the first and second
distal elements includes a fabric covering.
7. The device of claim 6, wherein each of the first and second
distal elements has at least a portion having a concave
surface.
8. The device of claim 7, wherein the concave surfaces of the first
and second distal elements are configured to surround a central
portion of the fixation implant in the closed position.
9. The device of claim 8, wherein the central portion has a
longitudinal axis defining the center of the fixation implant.
10. The device of claim 1, wherein each of the first and second
retaining elements is capable of being aligned parallel with the
respective first and second distal element in the closed
position.
11. The device of claim 1, wherein the first retaining element
comprises a first spring portion and the second retaining element
comprises a second spring portion.
12. The device of claim 1, wherein the first retaining element is
attached proximate a midpoint of the first distal element in the
closed position, and the second retaining element is attached
proximate a midpoint of the second distal element in the closed
position.
13. The device of claim 1, wherein each first and second retaining
element is attached to the first and second distal element,
respectively, proximate the center of the fixation implant.
14. A fixation implant for fixation of leaflets of a heart valve
comprising: first and second distal elements moveable between an
open position and a closed position, each distal element extending
outwardly from a center of the fixation implant in the open
position; a first retaining element attached to the first distal
element; a second retaining element attached to the second distal
element; a first proximal element movable to capture a first
leaflet of the heart valve between the first proximal element and
the first retaining element; and a second proximal element moveable
to capture second leaflet of the heart valve between the second
proximal element and the second retaining element, wherein the
first and second distal elements are configured to cover the first
and second retaining elements, respectively, in the closed
position.
15. A fixation implant for fixation of leaflets of a heart valve
comprising: first and second distal elements moveable between an
open position and a closed position, each distal element including
a fabric covering and defining a concave shape, each distal element
extending outwardly from a center of the fixation implant when in
the open position; a first retaining element attached to the first
distal element and disposed within the concave shape of the first
distal element when in the closed position; a second retaining
element attached to the second distal element and disposed within
the concave shape of the second distal element when in the closed
position; a first proximal element movable to capture a first
leaflet of the heart valve between the first proximal element and
the first retaining element; and a second proximal element moveable
to capture second leaflet of the heart valve between the second
proximal element and the second retaining element.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 16/748,450, filed on Jan. 21,
2020, which is a continuation application of U.S. patent
application Ser. No. 16/241,647, filed on Jan. 7, 2019, which is a
continuation application of U.S. patent application Ser. No.
14/577,852, filed on Dec. 19, 2014, issued as U.S. Pat. No.
10,188,392, the entire contents of which are incorporated herein by
reference.
BACKGROUND
[0002] 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 repairing heart
valves and venous valves, and devices and methods for removing or
disabling mitral valve repair components through minimally invasive
procedures.
[0003] 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.
[0004] 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 oxygenated blood from flowing back into the left atrium. In
this way, oxygenated blood is pumped into the aorta through the
aortic valve. Mitral valve regurgitation can significantly decrease
the pumping efficiency of the heart, placing the patient at risk of
severe, progressive heart failure.
[0005] 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 themselves, 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.
[0006] 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.
One 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 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.
[0007] The need to both open the chest and place the patient on
bypass is traumatic and has associated high mortality and
morbidity.
[0008] In some patients, a fixation device can be installed into
the heart using minimally invasive techniques. The fixation device
can hold the adjacent segments of the opposed valve leaflets
together and may reduce mitral valve regurgitation. One such device
used to clip the anterior and posterior leaflets of the mitral
valve together is the MitraClip.RTM. fixation device, sold by
Abbott Vascular, Santa Clara, Calif., USA.
DESCRIPTION OF THE BACKGROUND ART
[0009] Many techniques exist for approximating and repairing
tissues and organs at treatment sites. For example, minimally
invasive and percutaneous techniques for coapting and modifying
mitral valve leaflets to treat mitral valve regurgitation are
described in PCT Publication Nos. WO 98/35638; WO 99/00059; WO
99/01377; and WO 00/03759; WO 2000/060995; WO 2004/103162. Maisano
et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci et al.
(1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al.
(1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgical
procedures for performing "edge-to-edge" or "bow-tie" mitral valve
repair where edges of the opposed valve leaflets are sutured
together to lessen regurgitation. Dec and Fuster (1994) N. Engl. J.
Med. 331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc.
Surg. 112:238-247 are review articles discussing the nature of and
treatments for dilated cardiomyopathy.
[0010] Mitral valve annuloplasty is described in the following
publications: Bach and Bolling (1996) Am. J. Cardiol. 78:966-969;
Kameda et al. (1996) Ann. Thorac. Surg. 61:1829-1832; Bach and
Bolling (1995) Am. Heart J. 129:1165-1170; and Bolling et al.
(1995) 109:676-683. Linear segmental annuloplasty for mitral valve
repair is described in Ricchi et al. (1997) Ann. Thorac. Surg.
63:1805-1806. Tricuspid valve annuloplasty is described in McCarthy
and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268; Tager et al.
(1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989) Ann.
Thorac. Surg. 48:670-676.
[0011] Percutaneous transluminal cardiac repair procedures are
described in Park et al. (1978) Circulation 58:600-608; Uchida et
al. (1991) Am. Heart J. 121: 1221-1224; and Ali Khan et al. (1991)
Cathet. Cardiovasc. Diagn. 23:257-262. Endovascular cardiac valve
replacement is described in U.S. Pat. Nos. 5,840,081; 5,411,552;
5,554,185; 5,332,402; 4,994,077; and 4,056,854. U.S. Pat. No.
3,671,979 describes a catheter for temporary placement of an
artificial heart valve.
[0012] Other percutaneous and endovascular cardiac repair
procedures are described in U.S. Pat. Nos. 4,917,089; 4,484,579;
and 3,874,338; and PCT Publication No. WO 91/01689.
[0013] Thoracoscopic and other minimally invasive heart valve
repair and replacement procedures are described in U.S. Pat. Nos.
5,855,614; 5,829,447; 5,823,956; 5,797,960; 5,769,812; and
5,718,725.
BRIEF SUMMARY
[0014] The present disclosure describes devices intended for
intravascular delivery and for use in treating mitral valve defects
in human patients. The mitral valve of a human heart has an atrial
side, a ventricular side, an anterior leaflet, a posterior leaflet,
and an opening between the leaflets.
[0015] In one embodiment, the device can include a body, a pair of
proximal elements, and a pair of distal elements. Each proximal
element is coupled at a first end to the body on opposite sides of
the body, and has a free second end. Each proximal element has a
proximal engagement surface between its first and second ends. Each
proximal engagement surface is configured to approximate and engage
a portion of the leaflets adjacent the mitral valve on the atrial
side.
[0016] Each proximal engagement surface also has a proximal
retaining element configured to permit tissue to move toward the
first end of the proximal element and to resist movement of the
tissue away from the first end of the proximal element.
[0017] Each distal element is pivotally coupled at a first end to
the body on opposite sides of the body, and has a free second end.
Each distal element has a distal engagement surface between its
first and second ends. Each distal engagement surface is configured
to approximate and engage a portion of the leaflets adjacent the
mitral valve on the ventricular side.
[0018] A first one of the proximal elements cooperates with a first
one of the distal elements to form a space for receiving a portion
of the anterior leaflet therebetween. A second one of the proximal
elements cooperates with a second one of the distal elements to
form a space for receiving a portion of the posterior leaflet
therebetween. Each such space has an open end and a closed end, and
the closed end forms an apex.
[0019] The device includes an actuator for selectively moving the
distal elements between a first position in which the distal
elements are in a collapsed, low profile configuration for delivery
of the device, a second position in which the distal elements are
in an expanded configuration for positioning the device relative to
the mitral valve, and a third position in which the distal elements
are secured in position against a portion of the leaflets adjacent
the mitral valve on the ventricular side.
[0020] The device also includes an actuator for selectively moving
the proximal elements between a first position in which the
proximal elements are in a collapsed, low profile configuration for
delivery of the device and a second position in which the proximal
elements are in an expanded configuration for engaging a portion of
the leaflets adjacent the mitral valve on the atrial side.
[0021] Each distal element can also include a distal retaining
element positioned along the distal engagement surface. Each distal
retaining element is configured to cooperate with a corresponding
proximal retaining element to capture a free edge of the mitral
valve leaflet as the device is positioned relative to the mitral
valve. Each retaining element can be configured to cooperate with a
frictional element to allow a leading free edge of the leaflets to
move in a first direction toward the body with little or no
resistance or restriction and to resist or prevent movement of the
free edge of the leaflets in an opposite direction away from the
body.
[0022] These and other objects and features of the present
disclosure will become more fully apparent from the following
description and appended claims, or may be learned by the practice
of the embodiments of the invention as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] To further clarify the above and other advantages and
features of the present disclosure, a more particular description
of the invention will be rendered by reference to specific
embodiments thereof which are illustrated in the appended drawings.
It is appreciated that these drawings depict only illustrated
embodiments of the invention and are therefore not to be considered
limiting of its scope. Embodiments of the invention will be
described and explained with additional specificity and detail
through the use of the accompanying drawings in which:
[0024] FIG. 1 illustrates free edges of leaflets of the mitral
valve in normal coaptation, and FIG. 2 illustrates the free edges
in regurgitative coaptation.
[0025] FIGS. 3A-3C 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.
[0026] FIG. 4 illustrates the fixation device in a desired
orientation relative to the leaflets.
[0027] FIG. 5 illustrates an exemplary fixation device coupled to a
shaft.
[0028] FIGS. 6A-6B, 7A-7B, and 8 illustrate a fixation device in
various possible positions during introduction and placement of the
device within the body to perform a therapeutic procedure.
[0029] FIGS. 9A-9B illustrate a fixation device embodiment with a
leaf spring.
[0030] FIG. 10 illustrates a close-up of a portion of another
embodiment of a fixation device.
[0031] FIG. 11A illustrates a close-up of a portion of another
embodiment of a fixation device.
[0032] FIGS. 11B and 11C each illustrate a close-up cross-sectional
side view of a portion of another embodiment of a fixation
device.
[0033] FIGS. 11D and 11E each illustrate a close-up cross-sectional
transverse view of a portion of another embodiment of a fixation
device.
[0034] FIG. 12 illustrates a close-up of a portion of another
embodiment of a fixation device.
DETAILED DESCRIPTION
I. Introduction
[0035] A. Cardiac Physiology
[0036] As shown in FIG. 1, the mitral valve (MV) comprises a pair
of leaflets (LF) having free edges (FE) which, in patients with
normal heart structure and function, meet evenly to close along a
line of coaptation (C). The leaflets (LF) attach to the surrounding
heart structure along an annular region called the annulus (AN).
The free edges (FE) of the leaflets (LF) are secured to the lower
portions of the left ventricle LV through chordae tendinae (or
"chordae").
[0037] As the left ventricle of a heart contracts (which is called
"systole"), blood flow from the left ventricle to the left atrium
through the mitral valve (MV) (called "mitral regurgitation") is
usually prevented by the mitral valve.
[0038] Regurgitation occurs when the valve leaflets do not close
properly and allow leakage from the left ventricle into the left
atrium. A number of heart structural defects can cause mitral
regurgitation. FIG. 2 shows a mitral valve with a defect causing
regurgitation through a gap (G).
II. General Overview of Mitral Valve Fixation Technology
[0039] Several methods for repairing or replacing a defective
mitral valve exist. Some defects in the mitral valve can be treated
through intravascular procedures, where interventional tools and
devices are introduced and removed from the heart through the blood
vessels. One method of repairing certain mitral valve defects
includes intravascular delivery of a fixation device to hold
portions of the mitral valve tissues in a certain position. One or
more interventional catheters may be used to deliver a fixation
device to the mitral valve and install it there as an implant to
treat mitral regurgitation.
[0040] FIG. 3A illustrates a schematic of an interventional tool 10
with a delivery shaft 12 and a fixation device 14. The tool 10 has
approached the mitral valve MV from the atrial side and grasped the
leaflets LF.
[0041] The fixation device 14 is releasably attached to the shaft
12 of the interventional tool 10 at the distal end of the shaft 12.
In this application, when describing devices, "proximal" means the
direction toward the end of the device to be manipulated by the
user outside the patient's body, and "distal" means the direction
toward the working end of the device that is positioned at the
treatment site and away from the user. When describing the mitral
valve, proximal means the atrial side of the leaflets and distal
means the ventricular side of the leaflets.
[0042] The fixation device 14 comprises proximal elements 16 and
distal elements 18 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 fixation device 14
is coupleable to the shaft 12 by a coupling mechanism 17.
[0043] FIG. 3B illustrates that the distal elements 18 may be moved
in the direction of arrows 40 to an inverted position. The proximal
elements 16 may be raised as shown in FIG. 3C. In the inverted
position, the device 14 may be repositioned and then be reverted to
a grasping position against the leaflets as in FIG. 3A. Or, the
fixation device 14 may be withdrawn (indicated by arrow 42) from
the leaflets as shown in FIG. 3C. Such inversion reduces trauma to
the leaflets and minimizes any entanglement of the device with
surrounding tissues.
[0044] FIG. 4 illustrates the fixation device 14 in a desired
orientation in relation to the leaflets LF. The mitral valve MV is
viewed from the atrial side, so 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 positioned to be
substantially perpendicular to the line of coaptation C. During
diastole (when blood is flowing from the left atrium to the left
ventricle), fixation device 14 holds the leaflets LF in position
between the elements 16, 18 surrounded by openings or orifices O
which result from the diastolic pressure gradient, as shown in FIG.
4.
[0045] Once the leaflets are coapted in the desired arrangement,
the fixation device 14 is detached from the shaft 12 and left
behind as an implant.
[0046] A. Exemplary Fixation Device
[0047] FIG. 5 illustrates an exemplary fixation device 14. 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, a pair of opposed proximal elements 16, and a pair of
opposed distal elements 18.
[0048] 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. Preferably, each free end 54 defines a
curvature about two axes, axis 66 perpendicular to longitudinal
axis of arms 53, and axis 67 perpendicular to axis 66 or the
longitudinal axis of arms 53.
[0049] Arms 53 have engagement surfaces 50. Arms 53 and engagement
surfaces 50 are configured to engage about 4-10 mm of tissue, and
preferably about 6-8 mm along the longitudinal axis of arms 53.
Arms 53 further include a plurality of openings.
[0050] The proximal elements 16 are preferably resiliently biased
toward the distal elements 18. When the fixation device 14 is in
the open position, 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 16 contacting engagement surface 50, as
illustrated in FIG. 5.
[0051] Proximal elements 16 include a plurality of openings 63 and
scalloped side edges 61 to increase their grip on tissue. The
proximal elements 16 optionally include a frictional element or
multiple frictional elements to assist in grasping the leaflets.
The frictional elements may comprise barbs 60 having tapering
pointed tips extending toward engagement surfaces 50. Any suitable
frictional elements 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.
[0052] The proximal elements 16 may be covered with a fabric or
other flexible material. Preferably, when fabrics or coverings are
used in combination with barbs or other frictional features, such
features will protrude through such fabric or other covering so as
to contact any tissue engaged by proximal elements 16.
[0053] The fixation device 14 also includes an actuator or
actuation mechanism 58. 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 actuation mechanism 58 comprises two legs 68 which are each
movably coupled to a base 69. Or, 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 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.
[0054] 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. This
actuator rod and stud assembly may be considered a first means for
selectively moving the distal elements between a first position in
which the distal elements are in a collapsed, low profile
configuration for delivery of the device, a second position in
which the distal elements are in an expanded configuration for
positioning the device relative to the mitral valve, and a third
position in which the distal elements are secured in position
against a portion of the leaflets adjacent the mitral valve on the
ventricular side.
[0055] FIGS. 6A-6B, 7A-7B, and 8 illustrate various possible
positions of the fixation device 14 of FIG. 5. FIG. 6A illustrates
an interventional tool 10 delivered through a catheter 86. The
catheter 86 may take the form of a guide catheter or sheath. 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.
[0056] FIG. 6B illustrates a device similar to the device of FIG.
6A 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. This provides a low profile for the
fixation device 14.
[0057] FIGS. 7A-7B 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 actuator rod relative to shaft 12, and thus
distal advancement of the stud 74 relative to coupling member 19,
applies force to the distal elements 18 which begin to rotate
around joints 76. 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 directed 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 the open position, the free ends
54 of arms 53 may have a span therebetween of about 10-20 mm,
usually about 12-18 mm, and preferably about 14-16 mm.
[0058] 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 extend through the shaft
302 of the delivery catheter 300 and connect with the proximal
elements 16. The proximal elements 16 are raised and lowered by
manipulation of the proximal element lines 90. Once the device is
properly positioned and deployed, the proximal element lines can be
removed by withdrawing them through the catheter and out the
proximal end of the device 10. The proximal element lines 90 may be
considered a second means for selectively moving the proximal
elements between a first position in which the proximal elements
are in a collapsed, low profile configuration for delivery of the
device and a second position in which the proximal elements are in
an expanded configuration for engaging a portion of the leaflets
adjacent the mitral valve on the atrial side.
[0059] In the open position, the fixation device 14 can engage the
tissue which is to be approximated or treated. The interventional
tool 10 is advanced through the mitral valve from the left atrium
to the left ventricle. The distal elements 18 are then deployed by
advancing actuator rod relative to shaft 12 to thereby reorient
distal elements 18 to be perpendicular to the line of coaptation.
The entire assembly is then withdrawn proximally and positioned so
that the engagement surfaces 50 contact the ventricular surface of
the valve leaflets, thereby engaging the left ventricle side
surfaces of 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. 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.
[0060] It may also be desired to invert distal elements 18 of the
fixation device 14 to aid in repositioning or removal of the
fixation device 14. FIG. 8 illustrates the fixation device 14 in
the inverted position. By further advancement of actuator rod
relative to shaft 12, and thus 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.
[0061] The angle between arms 53 when the device is inverted 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. 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.
[0062] Once the distal elements 18 of the fixation device 14 have
been positioned in a desired location against the left ventricle
side surfaces of the valve leaflets, the leaflets may then be
captured between the proximal elements 16 and the distal elements
18. The proximal elements 16 are lowered toward the engagement
surfaces 50 by releasing tension from proximal element lines 90,
thereby releasing proximal elements 16 so that they are then free
to move, in response to the internal spring bias force formed into
proximal elements 16, from a constrained, collapsed position to an
expanded, deployed position and so that the leaflets are held
between the proximal elements 16 and the distal elements 18. If
regurgitation is not sufficiently reduced, the proximal elements 16
may be raised and the distal elements 18 adjusted or inverted to
reposition the fixation device 14.
[0063] 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 LF in this position
or the fixation device 14 may be returned to or toward a closed
position. This is achieved by retraction of the stud 74 proximally
relative to coupling member 19 so that the legs 68 of the actuation
mechanism 58 apply an upwards force to the distal elements 18 which
in turn rotate the distal elements 18 so that the engagement
surfaces 50 again face one another. The released proximal elements
16 which are biased outwardly toward distal elements 18 are
concurrently urged inwardly by the distal elements 18. The fixation
device 14 may then be locked to hold the leaflets in this closed
position. The fixation device 14 may then be released from the
shaft 12. The fixation device 14 optionally includes a locking
mechanism for locking the device 14 in a particular position, such
as an open, closed or inverted position or any position
therebetween. The locking mechanism may include a release harness.
Applying tension to the release harness may unlock the locking
mechanism.
[0064] The lock lines 92 engage the release harnesses 108 of the
locking mechanism 106 to lock and unlock the locking mechanism 106.
The lock lines 92 extend through the shaft 302 of the delivery
catheter 300. A handle attached to the proximal end of the shaft is
used to manipulate and decouple the fixation device 14.
[0065] Additional disclosure regarding such fixation devices 14 may
be found in PCT Publication No. WO 2004/103162 and U.S. patent
application Ser. No. 14/216,787, the disclosures of both of which
are incorporated herein in their entirety.
[0066] B. Improved Grasping Mechanisms
[0067] Sometimes it can be difficult to capture or retain tissue
within fixation device 14 so that fixation device 14 approximates
or repairs the tissue as desired. Leaflet insertion may be assessed
throughout the process of installing a fixation device 14, but it
can be difficult to differentiate good and poor leaflet insertion
and retention. For example, when fixation device 14 is used in
endovascular or minimally invasive procedures, visualization of the
capturing or retention of tissue may be difficult.
[0068] At times during the process of installing a fixation device
14, the tissue desired to be captured or retained between proximal
elements 16 and distal elements 18 may seem to be securely captured
or retained when it is actually only partially captured or
insecurely captured. As a result, the free edges FE of leaflet
tissue LF may later disassociate from the fixation device 14 and
the fixation device 14 may then not properly coapt, approximate, or
repair the tissue. Even if imaging methods make it possible to
visualize when tissue is captured in the fixation device, they may
not allow for a viewer to distinguish between securely and
insecurely captured tissue. For example, color Doppler echo may
show that regurgitation has been reduced, but it may not provide
precise specifics on where along the leaflets LF fixation device 14
has captured the tissue, and whether the capturing is secure.
[0069] If a leaflet is poorly grasped between proximal elements 16
and distal elements 18, eventually that leaflet LF may separate
from the fixation device 14. This may result in the fixation device
14 being attached to only one of the leaflets LF, or separating
from both leaflets LF, and no longer functioning as desired.
[0070] In addition to difficulties arising from the imaging or
visualization of the device 14 as it is installed, difficulty in
capturing or retaining tissue within fixation device 14 may also
result from the nature of tissue desired to be captured or
retained. For example, when using fixation device 14 to fix mitral
valve leaflets LF to each other to stop or reduce mitral valve
regurgitation, the leaflets LF are constantly moving as the heart
beats.
[0071] FIGS. 9-12 illustrate various embodiments that are intended
to help a fixation device 14' capture and retain the free edges FE
of leaflets LF during placement of the fixation device 14'. To do
so, these embodiments include the addition of a retaining element
400 positioned on the proximal side of each distal element 18'. The
retaining element 400 combines with frictional elements such as
barbs 410 at the lower end of the proximal element 16' to capture
the free edge FE of the leaflet upon its initial insertion and help
retain it there until the proximal and distal elements are fully
deployed. The lower end of the proximal element 16' is the end
closest to the stud 74'.
[0072] The retaining element 400 and barbs 410 are configured to
cooperate to allow the free edge FE of the leaflets LF to easily or
freely move in a first direction toward the apex 430 formed between
each proximal element 16' and the corresponding distal element 18',
but at the same time to resist or prevent movement of the free edge
FE of the leaflet tissue LF in the opposite direction away from
apex 430. In this way, retaining element 400, in cooperation with
the barbs 410, help to retain the leaflets LF in the device 14'
while the device is being positioned relative to the leaflets LF
and before the proximal elements 16' and distal elements 18' are
fully deployed.
[0073] The retaining element 400 may serve as a passive capture
mechanism that retains leaflet tissue LF without needing to be
activated. For example, the retaining element 400 may retain
leaflet tissue LF in the device 14' when a length of tissue of
about 4-10 mm, and preferably about 6-8 mm, is located along the
longitudinal axis of the distal elements 18'. A retaining element
400 may be located on the distal elements 18', as shown in the
illustrated embodiments, or the retaining element 400 may be
located on the proximal elements 16', or it may be located on both
the distal elements 18' and the proximal elements 16'. A retaining
element 400 may hold a leaflet LF in place without closing the
fixation element 18' and gripping element 16'.
[0074] As shown in FIGS. 9A-9B, in one embodiment, a retaining
element 400 may be a spring element 402 that retains leaflets LF
inserted into the fixation device 14'. The spring element 402 may
help capture or hold any leaflet LF that inserts past a given point
along the distal elements 18' which is determined to be sufficient
insertion depth.
[0075] Referring again to FIGS. 9A-B, the spring element 402 is on
a distal element 18'. Each distal element 18' has a spring element
402 incorporated into or attached to the distal element 18'. The
spring element 402 may be incorporated into or attached to the
distal element 18' at a midpoint 414 between a first end 404 of the
distal element 18' that attaches to a stud 74' and the free end 406
of the distal element 18'. It may also be incorporated into or
attached to the distal element 18' closer to the free end 406 of
each distal element 18' or to the first end 404 of each distal
element 18'. As shown in FIGS. 9A-B, the fixed end 412 of the
spring element 402 is located between the midpoint 414 and free end
406 of the distal element 18'. In addition, the spring element 402
of the retaining element 400 is elongate and can extend in an
elongate fashion along substantially an entire length of the distal
element 18' and associated distal engagement surface.
Alternatively, the retaining element 400 can extend in an elongate
fashion from a location near or adjacent first end 404 to a
location distal a midpoint of the distal engagement surface of the
distal element 18' or from a location near or adjacent second end
406 to a location distal a midpoint of the distal engagement
surface of the distal element 18'.
[0076] The spring element 402 may comprise a low-force leaf spring
408 biased to push the spring element 402 towards the leaflet LF
and encourage frictional elements or barbs 410 to be deeply
inserted into the leaflet LF, so the leaflet LF remains in a fully
seated state until distal elements 18' are further closed. As
illustrated, barbs 410 are orientated at an angle pointing toward
apex 430. With barbs 410 oriented in that direction, the leading
edge LE of the leaflet tissue LF is allowed to move in a first
direction toward apex 430 with little or no restriction or
resistance. As the leading edge LE of the leaflet tissue moves
toward apex 430, spring element 402 directs or urges the leaflet
tissue LF toward and into contact with barbs 410. Once the leaflet
tissue LF comes into contact with and engages the barbs 410, the
angled orientation of the barbs 410 causes barbs 410 to penetrate
into the leaflet tissue LF and then restricts or prevents movement
of the leaflet tissue LF in the opposite direction away from apex
430. Thus, the combination of the retaining element 400 and the
barbs 410 effectively function as a directional trap that permits
the leaflet tissue LF to move in a first direction toward apex 430
with little or no resistance, while restricting or preventing
movement of the leaflet tissue LF in a second or opposite direction
away from apex 430.
[0077] The leaf spring 408 may have one or more lobes or a partial
lobe. The leaf spring 408 may be biased to allow for little to no
resistance to a leaflet LF as it inserts. It may have surface
features, a pointed edge, or other elements that create resistance
to make it difficult for the leaflet LF to retract out. Such
surface features may include, for example, dimples, bumps, ridges,
or indents. For example, as shown in FIG. 9A-B, the free end 416 of
the spring element 402 may be configured to curve toward the distal
elements 18' (as shown in FIG. 9A) when tissue LF is being trapped,
and curve away from the distal element 18' (as shown in FIG. 9B)
when tissue LF is being released. When the leaflet is entrapped
between the distal elements 18' and the proximal elements 16', the
free end 416 of the spring element 402 may be configured to lie
flat against the distal element 18'.
[0078] The retaining element 400 helps the fixation device 14
capture tissue when proximal elements 16' are raised and distal
elements 18' are still partially open. The retaining element 400
may be configured to urge the leaflet tissue against the barbs 410
on the proximal elements 16. The retaining element 400 may be a
one-way mechanism that allows tissue to enter but not exit, such as
a ratchet or something similar to a ratchet.
[0079] Because repositioning and regrasping the fixation device 14'
is sometimes required, the one-way mechanism should have a way for
the leaflet tissue LF to be permitted to escape. The retaining
element can be designed to allow tissue to exit under certain
circumstances, such as when the distal elements 18' are opened to
approximately 180.degree., as shown in FIG. 9B, or are opened even
further in an inverted position, as shown in FIG. 8. Or, when the
proximal elements 16' are raised, the leaflet tissue LF may be
released to allow regrasping.
[0080] To ensure that the leaflets LF are properly grasped in a
fixation device 14', one method of using a device with a retaining
element 400 such as a spring element 402 located near each set of
distal elements 18' and proximal elements 16' is to first capture
one or both leaflets LF in the spring element 402. The spring
element urges the leaflets LF against the barbs 410 at the lower
end of the proximal element 16' to capture the free edge FE of the
leaflet LF upon its initial insertion and help retain it there
until the proximal and distal elements 16, 18 are fully deployed.
It may be possible to confirm that one or more leaflets LF is
captured based on imaging methods such as color Doppler echo. When
leaflets LF are trapped between the spring element 402 and the
barbs 410, then the proximal elements 16' may be lowered toward the
surfaces 50' of the distal elements 18', so that the leaflets LF
are held therebetween and the distal elements 18' may be locked to
hold the leaflets LF in this position or the fixation device 14'
may be returned to or toward a closed position.
[0081] In another embodiment, as shown in FIG. 10, a retaining
element 400 comprises an arm 417. Each distal element 18' has an
arm 417 incorporated into or attached to the distal element 18'.
The arm 417 may be incorporated into or attached at a fixed end 415
to the distal element 18' at a midpoint 414 between a first end 404
of the distal element 18' that attaches to a stud 74' and the free
end 406 of the distal element 18'. It may also be incorporated into
or attached to the distal element 18' closer to the free end 406 of
each distal element 18' or to the first end 404 of each distal
element 18'. As shown in FIG. 10, the fixed end 415 of the arm 417
is located between the midpoint 414 and free end 406 of the distal
element 18'.
[0082] The arm 417 has a projection or projections 418 of a
suitable shape and size to assist in retaining the leaflets LF in
position. These projections 418 may have sharp tips located
opposite to the arm 417, or sharp edges between their tips and the
arm 417. They may comprise barbs having tapering pointed tips,
scalloped edges, prongs, windings, bands, grooves, channels, bumps,
surface roughening, sintering, high-friction pads, coverings,
coatings or a combination of these. As shown in FIG. 10, these
projections may be oriented away from the surface 50' and angled
away from the free ends 406 of the distal element 18'. They may
also orient toward the free ends 406, or be perpendicular to the
surface 50'. The projections may flex or collapse toward the distal
element 18' when the fixation device 14' is closed and flex out to
a fixed angle when the fixation device 14' is open. For example,
the projections 418 may bias toward a fixed angle from the
engagement surfaces 50', but may be pushed flat against the distal
element 18' when the distal elements 18' close around the shaft
12.
[0083] The fixation device should be configured with enough space
between the proximal elements 16' and the distal elements 18' for a
leaflet LF to be easily inserted past the projections 418 on the
distal elements 18'. The chordal tethered leaflets LF may be
tensioned lightly upon the fixation device 14' just prior to
closing the distal elements 18' and proximal elements 16'. They may
also be securely affixed to the device 14' prior to closing the
distal elements 18' and proximal elements 16'.
[0084] In one embodiment, the arm 417 may be a flexible leaf-spring
that pivots at a fixed end 415 and is positioned between the
proximal element 16' and distal elements 18'. It may also include a
system of projections 418 angled to allow entry of the tissue
between the distal element 18' and proximal element 16', but to
prevent retraction of the tissue LF. As shown, the projection 418
and leaf spring 417 may be combined in the same structure. In
addition, the arm 417 of the retaining element 400 is elongate and
can extend in an elongate fashion along substantially an entire
length of the distal element 18' and associated distal engagement
surface. Alternatively, the retaining element 400 can extend in an
elongate fashion from a location near or adjacent first end 404 to
a location distal a midpoint of the distal engagement surface of
the distal element 18' or from a location near or adjacent second
end 406 to a location distal a midpoint of the distal engagement
surface of the distal element 18'.
[0085] As shown in FIG. 11, in another embodiment the retaining
element 400 may comprise one or more protrusions 420. One or more
protrusions 420 may be positioned close to the hinge point of the
distal elements 18' on the engagement surface 50'. When a leaflet
LF is inserted past the protrusion 420, the protrusion 420 may
reduce leaflet detachment upon deployment of the fixation device
14' by directing or urging the leaflet LF into contact with the
gripping surfaces or barbs 410 located on the opposing proximal
element 16'. The protruding feature 420 may be located near a
midpoint 414 between a first end 404 of the distal element 18' that
attaches to a stud 74' and the free end 406 of the distal element
18'. It may also be incorporated into or attached to the distal
element 18' closer to the free end 406 of each distal element 18'
or to the first end 404 of each distal element 18'. A protruding
feature 420 may be a rigid piece of material that is affixed to the
engagement surface 50' of distal elements 18' and may be atraumatic
to aid with directing or urging the leaflet LF while causing
minimal damage to the leaflet LF, such as not penetrating or
puncturing the leaflet LF. The protruding feature may be comprised
of any biocompatible material or materials, such as a polymer,
nitinol, or other alloys, or bioabsorbable materials.
[0086] The protruding feature 420 of the distal elements 18' may
passively engage the leaflet tissue LF when leaflet tissue LF is
sufficiently inserted into the device 14'. Or, the protruding
feature 420 may be configured to help engage leaflet tissue and
secure it into position when the proximal elements 16' are lowered
and also secure the leaflet tissue LF. The protruding feature 420
may help entrap tissue between the protruding feature 420 and the
gripping surfaces of the proximal elements 16'. The feature 420 may
urge the tissue LF against the barbs 410.
[0087] While the protruding feature 420 is illustrated as including
a generally curved or domed outer surface, it will be understood
that various other surface orientations are appropriate while
maintaining the atraumatic nature and ability to aid with directing
or urging the leaflet LF. For instance, as illustrated in FIGS.
11B-11E, the protruding feature 420 can have a curved surface that
is symmetric or asymmetric in (i) a direction from first end 404
towards the second end 406. (ii) a direction cross-wise,
transverse, or oblique to the direction from first end 404 towards
the second end 406, or (iii) both. So the protruding feature 420
can be symmetric in at least one axis, at least two axes, or in all
three axes. Alternatively, the protruding feature 420 can be
asymmetric in at least one axis, at least two axes, or in all three
axes.
[0088] In another embodiment, shown in FIG. 12, the retaining
element 400 may comprise a hinge 422 that is attached to the
surface 50' of the distal elements 18'. The hinge 422 connects to
an arm 424 that can swing toward and away from the distal element
18'. As shown in FIG. 12, the arm 424 may bias toward the first end
404 of each distal element 18'. The arm 424 may be capable of
laying parallel to or flat against the surface 50' while being
oriented toward the first end 404 of the distal element 18'. It
also may be capable of laying parallel to or flat against the
surface 50' while being oriented toward the free end 406 of the
distal element 18', and therefore capable of rotating 180.degree..
The hinge 422 may restrict the movement of the arm 424 so that it
can, for example, only lie parallel to the surface 50' while being
oriented toward the first end 404 of the distal element 18' and be
rotated about 90.degree., so that the angle formed between the arm
424 and the portion of the distal element 18' below the hinge 422
can be no greater than 90.degree.. The hinge 422 may also be a
pivoting element.
[0089] There may also be multiple arms 424 on the distal element
18'. For example, there may be two arms, each located the same
distance between the ends 404 and 406, and positioned next to each
other on the engagement surface 50'. If there are multiple
retaining elements 400, such as multiple arms 424 or multiple
spring elements 402, they may be configured to be positioned on
either side of the barbs 410 on the proximal element. Retaining
element or elements 400 may also be positioned to be located
between barbs 410 on the proximal element 16', if there are
multiple barbs 410 on the proximal element 16'. In addition, the
arm 424 of the retaining element 400 is elongate and can extend in
an elongate fashion along substantially an entire length of the
distal element 18' and associated distal engagement surface.
Alternatively, the retaining element 400, and associated arm 424,
can extend in an elongate fashion from a location near or adjacent
first end 404 to a location distal a midpoint of the distal
engagement surface of the distal element 18' or from a location
near or adjacent second end 406 to a location distal a midpoint of
the distal engagement surface of the distal element 18'.
[0090] The distal elements 18 may be covered with a fabric or other
flexible material. Preferably, when fabrics or coverings are used
in combination with projections 418, such features will protrude
through such fabric or other covering so as to contact the leaflet
tissue LF.
[0091] Analogous to a mechanical pawl, the bias, angle, and
direction of a retaining element 400 may allow the leaflet to fall
or slide deeper towards the stud 74' without much resistance but
may restrict the ability of the leaflet LF to move back out. By
permitting the leaflet LF to easily enter but not permitting it to
easily be removed from the fixation device 14', this may help
entrap the leaflet LF in a fully inserted state.
[0092] In the embodiments described above, the retaining element
400 is a passive element. However, retaining element 400 may also
include an active element such that, when a piece of leaflet tissue
LF proceeds beyond or next to a portion of the retaining element
400, the retaining element 400 may automatically spring or deploy
in such a way as to retain tissue LF in place.
[0093] In another embodiment, a fixation device 14 or 14' may
comprise a mechanical or physical sensor or some visual indicator
of when a leaflet is properly inserted into the device prior to
closing the distal elements 18' and deployment of the fixation
device 14 or 14'. For example, a tactile sensor may be embedded
near the first end 404 of each distal element. Each tactile sensor
may provide a signal or indication when the leaflet LF touches the
sensor, and the sensor may be located so that the leaflet LF will
be unable or unlikely to touch the sensor unless the leaflet is
adequately captured.
[0094] Yet another mechanism for enhancing the placement and
retention of the leaflet tissue LF in the fixation device 14 or 14'
is to facilitate actuation of each proximal element 16 or 16' and
each distal element 18 or 18' independent from one another. When
the proximal elements 16 or 16' for both leaflets LF are activated
simultaneously, and the distal elements 18 or 18' for each leaflet
LF are also activated simultaneously, it can be hard to capture
both leaflets, because it is necessary to capture both at the same
time. In other words, when the activation of both proximal elements
16 or 16' is symmetric, and the activation of both distal elements
18 or 18' is symmetric, the fixation device 14 or 14' is not able
to grasp one leaflet first and then the other. If a catheter or the
fixation device 14 or 14' is not properly positioned, or if either
leaflet LF has redundant or loose length, the fixation device 14 or
14' may not fully seat the leaflets between each distal fixation
element 18 or 18' and proximal gripping element 16 or 16'.
[0095] In one embodiment, each proximal element 16 or 16' and/or
each distal element 18 or 18' may be activated independently from
each other. For example, there may be a separate proximal element
line for each proximal element 16 or 16'. Similarly, there may be
two actuator rods 64 which extend through the shaft 12, each of
which may be configured to activate one distal element 18 or
18'.
[0096] In addition to being used to repair mitral valves, these
devices can be used in a variety of therapeutic procedures,
including endovascular, minimally-invasive, and open surgical
procedures, and can be used in various anatomical regions,
including abdominal, thoracic, cardiovascular, intestinal,
digestive, respiratory, and urinary systems, and other systems and
tissues. The invention provides devices, systems, and methods that
may more successfully approximate and repair tissue by improving
the capture of tissue into the devices.
[0097] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *