U.S. patent application number 13/086389 was filed with the patent office on 2011-11-17 for methods and devices for treating atrial fibrillation.
Invention is credited to Arnold M. Escano, Gregory W. Fung, Ryan Douglas Helmuth, Russell A. Seiber, Robert Strasser.
Application Number | 20110282250 13/086389 |
Document ID | / |
Family ID | 44798959 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110282250 |
Kind Code |
A1 |
Fung; Gregory W. ; et
al. |
November 17, 2011 |
METHODS AND DEVICES FOR TREATING ATRIAL FIBRILLATION
Abstract
Described here are systems and methods for affecting tissue
within a body to form a lesion. Some systems comprise
tissue-affecting devices, devices that guide the advancement of the
tissue-affecting elements to a target tissue region, devices that
locate and secure tissue, and devices that help position the
tissue-affecting devices along the target tissue. The methods
described here comprise advancing a first tissue-affecting device
to a first surface of a target tissue, advancing a second
tissue-affecting device to a second surface of the target tissue,
and positioning the first and second devices so that a lesion may
be formed in the tissue between them. In some variations, the
devices, systems, and methods described here are used to treat
atrial fibrillation by ablating fibrillating tissue from an
endocardial surface and an epicardial surface of a heart. Methods
of closing, occluding, and/or removing the left atrial appendage
are also described.
Inventors: |
Fung; Gregory W.; (San
Mateo, CA) ; Seiber; Russell A.; (Redwood Shores,
CA) ; Strasser; Robert; (Mountain View, CA) ;
Escano; Arnold M.; (Santa Clara, CA) ; Helmuth; Ryan
Douglas; (Saratoga, CA) |
Family ID: |
44798959 |
Appl. No.: |
13/086389 |
Filed: |
April 13, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61323796 |
Apr 13, 2010 |
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61323801 |
Apr 13, 2010 |
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61323816 |
Apr 13, 2010 |
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Current U.S.
Class: |
601/2 ; 606/1;
606/21; 606/28; 606/33 |
Current CPC
Class: |
A61B 17/12136 20130101;
A61B 17/12172 20130101; A61B 18/24 20130101; A61B 2017/00477
20130101; A61B 2018/00357 20130101; A61B 2018/1861 20130101; A61B
17/12122 20130101; A61B 18/1815 20130101; A61B 18/02 20130101; A61B
17/12195 20130101; A61B 2017/00084 20130101; A61B 18/1492 20130101;
A61B 17/122 20130101; A61B 2018/00279 20130101; A61B 2017/00876
20130101; A61B 2018/0212 20130101; A61B 2018/1407 20130101; A61N
7/02 20130101; A61B 17/12013 20130101; A61M 25/0127 20130101; A61N
7/00 20130101; A61B 17/12131 20130101; A61B 2017/00247 20130101;
A61B 2017/00243 20130101; A61B 2018/00363 20130101; A61N 7/022
20130101; A61B 2018/00791 20130101 |
Class at
Publication: |
601/2 ; 606/1;
606/33; 606/21; 606/28 |
International
Class: |
A61B 18/02 20060101
A61B018/02; A61N 7/00 20060101 A61N007/00; A61B 18/18 20060101
A61B018/18; A61B 17/00 20060101 A61B017/00; A61B 18/04 20060101
A61B018/04 |
Claims
1. A system for affecting tissue within a body comprising: a first
device comprising a first elongate member and one or more
tissue-affecting elements; a second device that corresponds to the
first device, the second device comprising a second elongate member
and one or more tissue-affecting elements that correspond to the
one or more tissue-affecting elements of the first device, wherein
the second device is separate from the first device, and wherein
the tissue-affecting elements of the first and second devices are
configured to operate simultaneously to form a tissue lesion at
least partially therebetween.
2. The system of claim 1, wherein the first and second devices
comprise a magnetic component.
3. The system of claim 2, wherein the first and second devices each
have a one or more temperature sensors.
4. The system of claim 3, wherein the first and second devices have
a first delivery configuration and a second deployed configuration,
wherein the devices are compressed in the first delivery
configuration and the devices are expanded in the second deployed
configuration.
5. The system of claim 4, wherein the first and second devices has
one or more curves in the second deployed configuration.
6. The system of claim 1, wherein the tissue-affecting elements are
configured to deliver cryogenic substances.
7. The system of claim 1, wherein the tissue-affecting elements are
configured to deliver high intensity focused ultrasound.
8. The system of claim 1, wherein the tissue-affecting elements are
configured to deliver heat energy.
9. The system of claim 1, wherein the tissue-affecting elements are
configured to deliver microwave energy.
10. The system of claim 1, wherein the tissue-affecting elements
are configured to deliver radiofrequency energy.
11. A method of affecting tissue within a body comprising:
advancing a first device comprising tissue-affecting elements to a
first surface of a target tissue, wherein the first
tissue-affecting device is positioned against a portion of the
first surface of the target tissue; advancing a second device
comprising tissue-affecting elements to a second surface of the
target tissue, wherein the second surface is opposite the first
surface of the target tissue; positioning the first and second
devices such that ablation energy passes through the target tissue
between the tissue-affecting elements of the first and second
devices; operating the tissue-affecting elements of the first and
second devices simultaneously such that a lesion is formed in the
target tissue.
12. The method of claim 11, wherein advancing the first device
comprises inserting a curved sheath at a location beneath a sternum
and advancing the first device through the sheath.
13. The method of claim 11, wherein the positioning step comprises
positioning the first and second ablation devices using one or more
magnetic components.
14. The method of claim 11, wherein the target tissue is cardiac
tissue.
15. The method of claim 11, wherein the target tissue is
gastrointestinal tissue.
16. The method of claim 11, wherein the target tissue is a
cancerous cell mass.
17. The method of claim 11, further comprising verifying that the
formed lesion spans between the first and second tissue-affecting
devices.
18. The method of claim 17, wherein the verifying step comprises
assessing the lesion using electrical impedance tomography.
19. The method of claim 17, wherein the verifying step comprises
assessing the lesion using thermal imaging techniques.
20. A method of forming a lesion in the tissue of a left atrium
comprising: advancing a first tissue-affecting device into the left
atrium through a puncture in a left atrial appendage, wherein the
first tissue-affecting device is positioned against the atrial
wall; advancing a second tissue-affecting device to an external
atrial wall, wherein the second tissue-affecting device is
positioned against the external atrial wall opposite the first
tissue-affecting device; positioning the first and second
tissue-affecting devices such that ablation energy may pass between
them; operating the first and second tissue-affecting devices
simultaneously such that a lesion is formed in the atrial wall at
least partially therebetween; and isolating the left atrial
appendage.
21. The method of claim 20, wherein advancing the first
tissue-affecting device further comprises advancing a first guide
wire through a puncture in the left atrial appendage into the left
atrium, and advancing the first tissue-affecting device over the
first guide wire.
22. The method of claim 21, wherein advancing the second
tissue-affecting device further comprises advancing a second guide
wire to the external atrial wall, and advancing the second
tissue-affecting device over the second guide wire.
23. The method of claim 22, wherein the positioning step comprises
positioning the first and second ablation devices using one or more
magnetic components.
24. The method of claim 20, wherein isolating the left atrial
appendage comprises positioning an occlusion device comprising a
rounded disc with one or more grooves circumscribing the outer
perimeter of the disc, wherein the disc is sized and shaped to be
constrained in base of the left atrial appendage.
25. A kit for affecting tissue within a body comprising: a first
device comprising one or more tissue-affecting elements and a
longitudinal lumen therethrough, wherein the first device has a
first compressed configuration and a second expanded configuration;
a second device that corresponds to the first device, the second
device comprising one or more tissue-affecting elements and a
longitudinal lumen therethrough, wherein the second device is
separate from the first device, and wherein the tissue-affecting
elements of the first and second devices are configured to operate
simultaneously to form a tissue lesion at least partially
therebetween.
26. The kit of claim 25, wherein the first device and the second
device further comprise one or more magnetic components.
27. The kit of claim 25, further comprising a closure device
comprising an elongate body and a distal snare, wherein the
elongate body comprises a lumen therethrough.
28. The kit of claim 27, further comprising a piercing member
configured to be advanced through the elongate body lumen.
29. The kit of claim 26, further comprising a first and second
cannula.
30. The kit of claim 27, further comprising a first and second
guide wire.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application No. 61/323,796
filed Apr. 13, 2010, U.S. Provisional Patent Application No.
61/323,801 filed Apr. 13, 2010, and U.S. Provisional Patent
Application No. 61/323,816 filed Apr. 13, 2010, the disclosures of
each of which is hereby incorporated by reference in its
entirety.
BACKGROUND
[0002] It is well documented that atrial fibrillation, either alone
or as a consequence of other cardiac disease, continues to persist
as the most common cardiac arrhythmia. Atrial fibrillation may be
treated using several methods, including administering
anti-arrhythmic medications, and chemical and/or electrical
cardioversion. Ablation of cardiac tissue using surgical techniques
have also been developed for atrial fibrillation, such as
procedures for atrial isolation and ablation of macroreentrant
circuits in the atria. For example, the MAZE III procedure creates
an electrical "maze" of non-conductive tissue in the atrium that
acts to prevent the ability of the atria to fibrillate by creating
incisions in certain regions of atrial tissue. In some cases, the
MAZE III procedure may include the electrical isolation of the
pulmonary veins. While the MAZE III procedure has shown some
efficacy in treating medically refractory atrial fibrillation,
additional devices and methods of treatment are desirable,
especially if they provide advantages over existing techniques.
BRIEF SUMMARY
[0003] Described here are devices, systems, and methods for
affecting tissue within a body to form a lesion. Some systems may
comprise devices having tissue-affecting elements that are
configured to be positioned on opposite sides of a tissue and
operated simultaneously to form a lesion in the tissue between
them. Some systems may also comprise devices that guide the
advancement of the tissue-affecting elements to a target tissue
region, devices that locate and secure tissue, devices that provide
access to the target tissue, and/or devices that may help position
the tissue-affecting elements on one or more surfaces of the target
tissue. The methods described here may utilize one or more of these
devices, and generally comprise advancing a first tissue-affecting
device to a first surface of a target tissue, advancing a second
tissue-affecting device to a second surface of the target tissue,
and positioning the first and second devices so that a lesion may
be formed in the tissue between them. In some variations, the
devices, systems, and methods described here may be used to treat
atrial fibrillation by ablating fibrillating tissue from an
endocardial surface and an epicardial surface of an atrium of a
heart. Methods of closing, occluding, and/or removing a portion of
the target tissue (e.g., the left atrial appendage) are also
described.
[0004] One variation of a system for affecting tissue within a body
may comprise a first device and a second corresponding device. The
first and second devices may each comprise an elongate member and
one or more tissue-affecting elements. The one or more
tissue-affecting elements of the second device may correspond to
the tissue-affecting elements of the first device. In some
variations, the first device may be configured to be placed on a
first surface of a target tissue, and the second device may be
configured to be placed on a second surface of the target tissue,
where the second surface is opposite the first surface. The first
and second devices may be configured to operate the
tissue-affecting elements simultaneously to form a lesion in the
target tissue at least partially therebetween.
[0005] Some variations of the first and second devices may comprise
one or more magnetic components. Optionally, the first and second
devices may also comprise a longitudinal lumen therethrough. The
first and second devices may also comprise one or more temperature
sensors. In certain variations, the first and second devices may
have a first delivery configuration and a second deployed
configuration, where the devices are compressed in the delivery
configuration and expanded in the deployed configuration.
[0006] The first and second devices may each comprise one or more
pre-shaped curves in the second deployed configuration. In some
variations, the pre-shaped curves may have varying radii of
curvature, and/or may be spiral or funnel shaped. In some devices,
the deployed configuration may comprise one or more curves in one
or more planes, and may comprise a ring-structure coupled to an
expandable net.
[0007] The tissue-affecting elements of the devices may affect
tissue to form a lesion using any suitable mechanism. For example,
the tissue-affecting elements may ablate tissue using cryogenic
substances, high intensity focused ultrasound (HIFU),
radiofrequency (RF) energy, lasers, heat, microwaves, and the like.
Some tissue-affecting elements may ablate tissue using a
combination of different mechanisms, as suitable for the target
tissue.
[0008] Methods of affecting tissue in a body are also described.
One variation of a method comprises advancing and positioning a
first tissue-affecting device to a first surface of a target
tissue, advancing and positioning a second tissue-affecting device
to a second surface of a target tissue, where the second surface is
opposite the first surface, positioning the first and second
tissue-affecting devices so that ablation energy may pass between
them, and operating both devices simultaneously to form a lesion in
the target tissue. In some variations, advancing the first device
may comprise inserting a curved sheath at a location beneath a
sternum and advancing the first device through the sheath.
Optionally, the method may comprise withdrawing the first and
second tissue-affecting devices after the lesion is formed, as well
as verifying and assessing the lesion using fluoroscopic,
electrical impedance, and thermal imaging techniques. In some
variations of the method, the tissue-affecting devices may comprise
magnetic components. Tissue-affecting devices may apply a variety
of ablation energies, for example, cryogenic, high intensity
focused ultrasound, laser energy, radiofrequency energy, heat
energy and/or microwave energy. These methods may be used to ablate
tissue of the left atrium as part of a procedure to treat atrial
fibrillation, but may also be used to target gastrointestinal
tissue, as well as cancerous cell masses.
[0009] Methods of forming a lesion in the tissue of a left atrium
are also described here. One variation of a method may comprise
advancing and positioning a first tissue-affecting device in the
left atrium through a puncture or access site in a left atrial
appendage, advancing a second tissue-affecting device to an
external wall of the left atrium, where the second device is
positioned opposite to the first device, operating both devices
simultaneously to form a lesion in the atrial wall between them,
and isolating the left atrial appendage. Optionally, the method may
also comprise positioning the first and second devices with respect
to each other using one or more magnetic components, and verifying
and assessing the lesion using various imaging techniques (e.g.
fluouroscopic, electrical impedance, and thermal imaging
techniques). In some variations, the first tissue-affecting device
may be advanced over a first guide (e.g., guide wire) into the left
atrium to circumscribe the base of a pulmonary vein, and the second
tissue-affecting device may be advanced over a second guide (e.g.,
guide wire) to circumscribe the trunk of the pulmonary vein on the
external atrial wall. Additionally or alternatively, the first
guide wire and the first tissue-affecting device may be advanced
into the left atrium to circumscribe the bases of two or more
pulmonary veins, while the second guide wire and the second
tissue-affecting device may be advanced over the external atrial
wall to circumscribe the trunks of two or more pulmonary veins. In
some variations, isolating the left atrial appendage may comprise
positioning an occlusion device comprising a rounded disc with one
or more grooves circumscribing the outer perimeter of the disc,
wherein the disc is sized and shaped to be constrained in an ostium
or base of the left atrial appendage.
[0010] Also described here are kits for affecting tissue within a
body. One variation of a kit may comprise a first device with one
or more tissue-affecting elements and a longitudinal lumen
therethrough, where the first device has a first compressed
configuration and a second expanded configuration, a second device
with one or more tissue-affecting elements and a longitudinal lumen
therethrough, where the first and second devices are configured to
operate simultaneously to form a lesion that spans at least a
portion of tissue between them. In some variations, the kit
optionally comprises first and second devices as described above,
where the first and second devices also comprise one or more
magnetic components and/or one or more temperature sensors. In
certain variations, the kit may also comprise a closure member with
an elongate body and a distal snare, where the elongate body may
comprise a longitudinal lumen therethrough, a piercing member that
is configured to be advanced through the lumen of the elongate
body, a first and second cannula, and a first and second guide
wire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 depicts a heart with a partial cutaway in the left
atrium.
[0012] FIG. 2 depicts one variation of a closure device.
[0013] FIG. 3A depicts an exploded view of one variation of an
access device. FIG. 3B depicts one variation of an assembled access
device.
[0014] FIG. 4 depicts one variation of an endocardial ablation
device.
[0015] FIG. 5 depicts one variation of an epicardial ablation
device.
[0016] FIGS. 6A-6F depict side and front views of different
ablation arrays that may be used with various ablation devices,
including the devices shown in FIGS. 4 and 5. FIGS. 6G and 6H
depict variations of ablation arrays comprising temperature
sensors. FIG. 61 depicts a partial cutaway of one variation of a
temperature sensor that may be encapsulated in an alignment magnet
of an ablation array.
[0017] FIG. 7 depicts one variation of an occlusion device
comprising an expandable element.
[0018] FIG. 8A depicts a flowchart that represents one variation of
a method for ablating cardiac tissue from both the endocardial
surface and epicardial surface. FIG. 8B depicts a flowchart that
represents another variation of a method for ablating cardiac
tissue from both the endocardial and epicardial surface.
[0019] FIGS. 9A-9D depict ablation patterns that may be formed by
endocardial and epicardial ablation of atrial wall tissue. FIGS.
9E-9G depict variations of epicardial and endocardial ablation
arrays that comprise temperature sensor in various
configurations.
[0020] FIGS. 10A-10S depict one example of an ablation method for
ablating tissue around the pulmonary veins, and for closing, and/or
occluding, and/or removing the left atrial appendage. FIG. 10A
schematically illustrates potential access sites to the pericardial
space. FIGS. 10B-10G schematically illustrate the use of a closure
device to locate and secure the left atrial appendage. FIGS.
10H-10L schematically illustrate the positioning of endocardial and
epicardial ablation devices. FIGS. 10M-10N depict the alignment of
endocardial and epicardial arrays using magnetic components. FIGS.
10O-10Q depict examples of ablation profiles that may form lesions
that electrically isolate the tissue at or around or within the
pulmonary veins. FIGS. 10R-10S schematically illustrate the use of
an occlusion device to occlude and isolate the left atrial
appendage.
[0021] FIGS. 11A-11C depict one variation of a clip that may be
used to secure the base or ostium of an atrial appendage.
[0022] FIGS. 12A and 12B depict various mechanisms by which an
atrial appendage may be occluded.
[0023] FIG. 13A depicts a flowchart that represents one variation
of a method for ablating atrial wall tissue from an endocardial
surface. FIG. 13B depicts a flowchart that represents another
variation of a method for ablating tissue from an endocardial
surface.
[0024] FIGS. 14A and 14B depict ablation patterns that may be
formed by endocardial ablation of atrial wall tissue.
[0025] FIG. 15 depicts a flowchart that represents one variation of
a method for ablating atrial wall tissue from an epicardial
surface, comprising a procedure to close, and/or occlude, and/or
remove the left atrial appendage.
[0026] FIGS. 16A and 16B depict ablation patterns that may be
formed by epicardial ablation of atrial wall tissue.
[0027] FIG. 17A depicts one variation of an access device. FIG. 17B
depicts a cross-sectional view of the access device of FIG. 17A
taken along the lines 17B-17B. FIG. 17C depicts one variation of a
curved region of the device of FIG. 17A with a plurality of slots.
FIG. 17D depicts one example of how the access device of FIG. 17A
may be used to provide an access path to the heart.
[0028] FIGS. 18A and 18B depict one variation of an occlusion
device that may be used to position a closure element around a left
atrial appendage.
[0029] FIGS. 19A-19F another example of devices and methods that
may be used to place a device at or around a tissue structure.
DETAILED DESCRIPTION
[0030] The system and methods described herein may be used to
affect any portion of tissue within a body to form a lesion, and/or
otherwise electrically isolate a portion of tissue. For
illustrative purposes, these devices and methods are described in
the context of lesion formation in the tissue of the left atrium
for the treatment of atrial fibrillation, and may include the
closure of the left atrial appendage. For example, methods for
affecting tissue to treat atrial fibrillation may comprise
accessing the pericardial space of the heart, creating an access
site through the left atrial appendage (LAA), advancing a
tissue-affecting device intravascularly and/or through the LAA to
contact an endocardial surface of the left atrium, advancing
another tissue-affecting device via the pericardial space to
contact an epicardial surface of the heart, and affecting tissue
from either or both the endocardial and epicardial surfaces. In
some variations, a LAA access/exclusion device may be used to
stabilize the LAA for the advancement of devices therethrough, as
well maintain hemostasis by closing and/or opening the LAA during
and/or at the conclusion of the procedure. While the systems and
methods disclosed here are described in the context of affecting
cardiac tissue, it should be understood that these devices and
methods may be used to affect a variety of tissues, such as the
skin, heart, liver, etc., as well as to treat a variety of
conditions, including various cardiac deficiencies, tumors,
gastrointestinal deficiencies, etc.
I. Anatomy
[0031] FIG. 1 depicts a heart (100), with the cavity of the left
atrium partially cut away to reveal a portion of the mitral valve
(102) and pulmonary veins (104a), (104b), (104c), (104d). Both the
right atrial appendage (106) and the left atrial appendage (108)
are shown, located on the superior portion of the heart (100). The
heart (100) is enclosed by a pericardium (not shown), which is
filled with a fluid that may separate it from the heart. The
fluid-filled space between the pericardium and the heart is the
pericardial space. In a heart affected by atrial fibrillation,
tissues associated with one or more of these anatomical structures
may pulsate irregularly or asynchronously, and may cause the atrium
to contract quickly and/or irregularly. Procedures for the
treatment of atrial fibrillation may comprise the electrical
isolation of arrhythmic cardiac tissue from other tissue regions.
In some variations, devices and methods for treating atrial
fibrillation may be directed towards the formation of lesions in
the right atrium (e.g. in the proximity of the tricuspid valve
annulus, the anterior limbus of the fossa ovalis, and/or the right
atrial appendage), and/or lesions in the left atrium (e.g. in
proximity of the pulmonary veins and/or LAA). For example, one
variation of a method for treating atrial fibrillation in the left
atrium may comprise the electrical isolation of tissue(s) at or
around or within each of the pulmonary veins, and may optionally
include the closure, occlusion, and/or removal of the left atrial
appendage. While the devices and methods described below may be
used to access, affect, and electrically isolate tissue in the left
atrium, similar devices and methods may be used to treat any
suitable portion(s) of the heart, e.g., the right atrium, right
ventricle, left ventricle, etc.
II. Devices
Pericardial Access Device
[0032] In order to access certain portions of the heart, it may be
useful to place one or guide elements in the pericardial space
around the heart. Various devices may be used to provide access to
the pericardial space for the placement of a guide element into the
pericardial space for the advancement of subsequent devices to the
heart. Some pericardial access devices may be configured to provide
an access pathway from an initial access site (e.g., a sub-thoracic
region, an intercostal region, etc.). For example, a pericardial
access device may comprise a sheath with one or more curves, and
one or more needles, guide elements, tissue-piercing elements, etc.
to create a pathway through the pericardium to access the
pericardial space. In some variations, the one or more needles,
guide elements, tissue-piercing elements, etc. may be sized and
shaped to correspond with the one or more curves in the sheath. One
example of a sheath with one or more curves is shown in FIGS. 17A
and 17B. As shown there, the sheath (1702) may have a curved region
(1706) between the proximal portion (1704) to the distal portion
(1708). The proximal portion (1704) may be connected to a proximal
sheath actuator. A sheath actuator may be used to advance the
sheath, e.g., along a longitudinal axis, to navigate the distal
portion of the sheath, and/or may be configured to cause the curved
region (1706) to bend. A cross-section of the sheath (1702) is
depicted in FIG. 17B. The sheath (1702) may have one or more
longitudinal lumens therethrough, for example, a wire lumen (1710)
and an access device lumen (1712). Other variations of a curved or
bendable sheath may have any desired number of lumens therethrough,
e.g. 2, 3, 5, 8, etc. The wire lumen (1710) may be sized and shaped
for passing a wire therethrough. The access lumen (1712) may be
sized and shaped to pass a pericardial access device therethrough,
for example, any of the access devices described above. In some
variations, sheaths may have additional lumens for inserting other
devices therethrough, and/or as necessary for accommodating
mechanisms that may be used to control the flexion of the curved
region (1706).
[0033] The curved region (1706) may have one or more pre-shaped
curves, and/or may be flexible or bendable using a suitable
actuating mechanism controlled by the sheath actuator at the
proximal portion (1704). The curved region (1706) may serve to
generally orient the sheath toward the heart upon insertion at an
initial access point beneath the sternum, and/or may have a
particular radius of curvature to help guide the sheath under the
rib cage to the heart. In some variations, the curvature of the
curved region (1706) may be locked or fixed, e.g., the curved
region (1706) is first actuated to attain a desired degree of
curvature, then locked to retain that desired curvature. Suitable
locking mechanisms may include, for example, maintaining the
tension of a wire that may be inserted through the wire lumen
(1710), or immobilizing the hinge mechanisms to a desired
configuration. A flexible or soft curved region may be locked into
position by fixing the configuration (e.g., curvature, tension,
etc.) of the wire within the wire lumen (1710). Some variations of
a sheath may have a pre-shaped curve, where the radius of curvature
is determined at the time of manufacture, and remains unchanged as
the sheath is used. The radius of curvature of the curved region
may be adjusted for sheaths that are inserted at different initial
access points. For example, the radius of curvature of a curved
region of a sheath to be inserted at an intercostal access site may
be different from the radius of curvature of a curved region of a
sheath to be inserted at a sub-thoracic access site.
[0034] The curved region (1706) may be made of a flexible or
bendable material, or may be made of a substantially rigid material
arranged in articulating segments that allow for the curved region
(1706) to bend when actuated. The curved region (1706) may be
integrally formed with the body of the sheath (1702), or may be
separately formed and attached to the sheath (1702). For example,
the curved region (1706) may be made of polymeric tubing and/or
materials such as Pebax.RTM., nylon, fluoropolymers (e.g., PTFE,
FEP), polyethelene, Teflon.RTM., polyethylene terephthalate (PET),
Tecothane.RTM., etc. In some variations, the curved region (806)
may be made of a polymeric tube with reinforced stainless steel or
nitinol. Where the curved region (1706) is made of a substantially
rigid material, for example, stainless steel, nickel titanium,
nitinol, cobalt alloys (e.g. nickel-cobalt,
cobalt-nickel-chromium-molybdenum), and/or polymers such as PEEK,
polyethylene (HDPE), polyimide, etc., the curved region may be
slotted or segmented to allow bending to occur. In some variations,
a curved region (1707) may have one or more slots (1705), as
illustrated in FIG. 17C. In other variations, the curved region
(1706) may comprise a plurality of segments, where the positioning
of the segments with respect to each other is controlled by a wire
or pivot mandrel. The segments may be coupled together via
mechanical hinges and/or living hinges. Sheaths may also comprise
multiple curved regions, where each of the curved regions may have
the same or different radii of curvature. For example, one curved
region may be made of a material with a selected flexibility, while
another curved region may be made of a material with a different
flexibility. Other curved regions may be slotted or segmented, as
appropriate. Different curved regions may be separated by a
straight portion of the sheath, or may be contiguous. A plurality
of curved regions may help to provide additional maneuverability to
navigate the distal portion of the sheath to the targeted region of
the heart. Adjusting the tension on a wire through the wire lumen
(1710) may alter the curvature of the curved region (1706). For
example, increasing the wire tension may cause bending of the
curved region (1706), while decreasing the wire tension may cause
straightening of the curved region (1706).
[0035] FIG. 17D depicts one variation of a method of using the
sheath (1702). The sheath (1702) may be inserted into the subject
(1730) at a location beneath the sternum (1722). Prior to
insertion, the sheath may be substantially straight, or may be
curved, as appropriate. Once the sheath (1702) has been inserted,
the curved region (1706) may be adjusted in order to bring the
distal portion (1708) close to the surface of the heart (1720). For
example, the distal portion (1708) may be navigated underneath the
ribs (1728) towards the heart (1720). Once the distal portion
(1708) of the sheath (1702) is in a desired location, e.g., an
anterior and/or slightly lateral side of the heart, the curved
region (1706) may be locked to retain the curvature of the curved
region. The location of the distal portion (1708) may be monitored
using any suitable imaging modality, for example, ultrasound,
fluoroscopy, and the like. In some methods, the location of the
distal portion (1708) may be monitored by tactile feedback.
[0036] An articulating sheath such as is shown and described above
may be useful for accessing the heart (1720) where the abdomen
(1724) of the subject (1730) may limit the angle at which the
sheath (1702) may be positioned. Certain subject anatomy, such as a
smaller abdomen (1724) may provide a large range of maneuverability
for the sheath (1702), while a larger abdomen (1724) may limit the
range of maneuverability for the sheath. Providing one or more
curved regions may allow the heart to be more readily accessed
where subject anatomy limits the range in which the sheath may be
positioned. For example, providing one or more curved regions may
help to reduce the force that may be required to position the
sheath (1702), and may provide additional access paths to the heart
in the event the originally planned pathway becomes
unavailable.
Closure Device
[0037] Some methods for treating atrial fibrillation may comprise
accessing an endocardial surface of the left atrium through the LAA
via the pericardial space. Methods that utilize the LAA as an entry
port may also comprise closing and/or opening the LAA during the
procedure (e.g., to advance devices therethrough) to maintain
hemostasis. Optionally, methods may also comprise excluding the LAA
at the conclusion of the procedure. Such a device may be used
during the procedure to stabilize the LAA so that tissue-affecting
devices may be advanced through the LAA into the left atrium, and
may be used to at the conclusion of the procedure to permanently
close off or otherwise occlude the LAA. One example of a device
that may be capable of locating, securing, manipulating,
stabilizing, closing and/or excluding the LAA is depicted in FIG.
2. Closure device (200) may comprise an elongate body (202), a
handle portion (204) located at a proximal portion of the elongate
body (202), an extension (205) located at a distal portion of the
elongate body (202), and a distal looped closure assembly (206)
distally coupled to the extension (205). While the closure device
disclosed below is described in the context of locating, securing,
manipulating, stabilizing and/or closing the LAA, it should be
understood that the closure device may be used to act on any
desirable tissue.
[0038] The elongate body (202) may have any appropriate shape, for
example, the elongate body may be substantially straight (as
depicted in FIG. 2), or may have one or more pre-formed curves and
shapes. The elongate body (202) may have a suitable cross-sectional
diameter and longitudinal length to facilitate navigating the
closure device (200) through the vasculature to contact the LAA (or
other target tissue). The elongate body (202) may be made of one or
more flexible or rigid materials, as may be suitable for navigating
towards the target tissue. In some variations, the elongate body
may be steerable, and comprise steering mechanisms (such as
mandrels, articulating and/or living hinges, cables, etc.) that
allow a user to steer the elongate body using the handle portion
(204). For example, the elongate body may be made of a single
integral flexible material with one or more steering mandrels
embedded in the side wall of the elongate body, such that bending
the mandrel(s) would cause a corresponding deflection of the
elongate body, which may help steer the elongate body towards the
target tissue. Alternatively or additionally, the elongate body may
be made of a plurality of segments that may be connected by
articulating and/or living hinges. Each of the plurality of
segments may be rigid or flexible. One or more mandrels may be
coupled to each of the plurality of segments, and may be used to
bend and steer the elongate body towards the target tissue. The
elongate body may also comprise locking mechanisms so that after
the elongate body is steered to a target location, it may be locked
to retain a certain configuration to maintain contact with that
target location. The elongate body (202) may comprise one or more
working channels (208) that extend from the proximal portion of the
elongate body (202) to the distal portion of the elongate body. A
variety of devices may be inserted through the working channel in
order to manipulate a portion of tissue. Alternatively or
additionally, the closure device (200) may be advanced over a guide
element using the working channel (208).
[0039] As depicted in FIG. 2, the distal extension (205) may extend
distally beyond the distal end of the elongate body (202). This may
allow for additional working space as may be suitable for accessing
the LAA. For example, the distal extension (205) may extend
distally beyond the distal-most portion of the working channel
(208) of the elongate body. The length of the distal extension
(205) may be selected such that when the base of the LAA is engaged
by the distal looped closure assembly (206), the tip of the LAA may
be close to (e.g., in contact with) the distal-most portion of the
working channel (208). This may allow devices that are advanced
through the working channel (208) to directly contact and/or
manipulate the tip of the LAA once it exits the working
channel.
[0040] The distal extension (205) may be integrally formed with
elongate body (202), or separately formed and attached to the
elongate body (e.g., by welding, melding, brazing, adhesives,
etc.). The distal extension (205) may be made of rigid and/or
flexible materials, and may be made of the same or different
materials as the elongate body. The elongate body and/or distal
extension may be made of polymeric materials such as Pebax.RTM.,
polyethelyne, and/or other thermoplastic materials with various
durometers or densities, and/or any polymers that may be tapered or
graduated for varying degrees of flexibility. Additionally or
alternatively, the elongate body and/or distal extension may be
made of metallic materials such as nitinol, stainless steel, etc.
The looped closure assembly (206), distal extension (205), elongate
body (202), and/or portions thereof may comprise visualization
markers, such as fluorescent markers, echogenic markers, and/or
radiopaque markers, that permit the closure device to be visualized
using a variety of imaging modalities. As with the elongate body
(202) described above, the distal extension (205) may also be
steerable. In some variations, the distal extension (205) may be
steered independently from the elongate body, while in other
variations, the distal extension (205) may be steered together with
the elongate body. For example, a steering mandrel that may be used
to steer the elongate body may also be coupled to the distal
extension so that the extension may be steered in concert with the
elongate body. Alternatively, there may be a first mandrel for the
steering the elongate body and a second mandrel for steering the
distal extension independently from the elongate body. Optionally,
the distal extension may have one or more pre-shaped curves which
may help to navigate the closure device (200) to a target tissue
region.
[0041] In some variations, the distal extension (205) may comprise
one or more lumens that may extend from the distal-most end of the
extension to the proximal portion of the closure device (e.g., to
the handle portion). A lumen in the distal extension may slidably
retain a portion of the looped closure assembly such that the
dimensions of the loop may be adjusted. For example, the lumen of
the distal extension (205) may slidably retain the looped closure
assembly (206), which may comprise a distal loop (203). The distal
loop (203) may comprise a snare loop and a suture loop that may be
releasably coupled along the circumference of the snare loop. The
distal loop (203) may be made of polymeric materials such as
Pebax.RTM., and/or metallic materials, such as nitinol, and/or any
elastic, malleable, deformable, flexible material. The portion of
the distal loop that extends outside of the extension, i.e., the
external portion of the distal loop, may be adjustable using an
actuator at the proximal handle portion. Adjusting the length of
the external portion of the distal loop (203) may help to snare
and/or close, or release and/or open, a LAA or any anatomical
protrusion. While the distal loop (203) may have the shape of a
circle, it may also have other shapes, e.g., an ellipse, oval,
triangle, quadrilateral, etc. In other variations, the looped
closure assembly may be configured (e.g. knotted, looped, coiled,
etc.) for other functions, such as locating and securing tissue.
For example, the looped closure assembly may optionally comprise
tissue graspers, hooks, or other such tissue engagement components
that may help secure and retain a tissue portion.
[0042] The looped closure assembly (206) may have an expanded
(e.g., open) configuration, and a tightened (e.g., closed)
configuration, where the circumference of the loop in the tightened
configuration is smaller than in the expanded configuration. For
example, a distal loop with an elliptical shape in the open
configuration may have a length along the minor axis (e.g., the
shortest dimension of the ellipse) from about 15 mm to about 50 mm,
e.g., about 20 mm, and a length along the major axis (e.g., the
longest dimension of the ellipse) from about 15 mm to about 50 mm,
e.g., about 40 mm. A distal loop in the closed configuration may
have a diameter equivalent to about 5 mm to about 10 mm, e.g., 6
mm. The looped closure assembly (206) may be tightened or cinched
to encircle and secure the LAA, and in some variations, may be able
to close the LAA after it has been secured, if desirable.
Optionally, the looped closure assembly (206) may be releasably
coupled to the closure device such that after the LAA is encircled
and secured by the distal loop (203), a knot or locking element may
be deployed to retain the tension on the distal loop, which may
then be released from the closure device. For example, a looped
closure assembly may have a releasable suture loop that is
tightened over the LAA and then released from the closure device.
The tension on the suture loop may be locked so that the looped
closure assembly may be proximally withdrawn from the suture loop.
Optional closure elements, such as sutures, graspers, clips,
staples, and the like, may be included with the looped closure
assembly to help close the LAA. For example, additional closure
features, e.g., graspers or staples, may be included at the tip of
distal extension (205) that may act to secure the LAA. A looped
closure assembly may also comprise one or more energy sources
distributed along the length of the distal loop, where the energy
sources may be used to ablate tissue or induce tissue fusion.
Alternatively or additionally, the looped closure assembly (206)
may be actuated in conjunction with other devices advanced through
the working channel (208) to secure and position the closure device
with respect to the LAA.
[0043] Various types of devices may be inserted through the working
channel (208) of the elongate body (202) as may be desirable. In
some variations, a vacuum device may be inserted through working
channel (208), while in other variations, alignment devices, guide
elements, grasper devices, visualization devices, ablation devices,
and/or cutting devices may be inserted through the working channel.
Variations of the closure device may have a multi-lumen elongate
body, where each lumen may be a working channel for one or more
different devices. For example, the elongate body (202) may have
multiple working channels for the insertion of different devices.
Additionally or alternatively, the elongate body (202) may comprise
working channels for the injection of liquid or gas fluids, as well
as the application of therapeutic and/or chemical agents. The
working channel (208) may have any cross-sectional shape as may be
suitable for the devices to be inserted therethrough, for example,
circular, rectangular, etc.
[0044] The closure device (200) may comprise mechanisms to control
the bending and/or steering of the elongate body, as well as adjust
the length of the distal loop that extends outside of the distal
extension. For example, these functions may be controlled by levers
and/or knobs at the handle portion (204). The handle portion (204)
may comprise a housing (214), a loop actuator (212), and a working
channel actuator (210). The housing (214) may enclose at least a
portion of the actuators that control the use of the elongate body,
the looped closure assembly, and the device in the working channel
of the elongate body. For example, loop actuator (212) may regulate
the tension on the distal loop of the looped closure assembly, and
control the circumference of the external portion of the distal
loop, e.g. decrease it to encircle and/or close the LAA, and
increase it to release the LAA. In some variations, the loop
actuator (212) may be a slider configured to adjust the
circumference of the distal loop (203). In variations where the
distal loop comprises a releasable suture loop, the loop actuator
may also comprise a fob that initially couples the suture loop with
the closure device and may be pulled to release the suture loop
from the closure device. The working channel actuator (210) may
comprise one or more buttons, sliders, levers, knobs, and the like
that are configured regulate the operation of the device(s) in the
working channel(s) of elongate body (202). For instance, the
working channel actuator (210) may be a grasper actuator, and/or
vacuum actuator. Optionally, handle portion (204) may also comprise
one or more buttons, sliders, levers, and/or knobs that may be used
to navigate the LAA access device through the vasculature to access
the LAA, for example, by rotating, pulling, pushing, bending, or
otherwise manipulating steering mandrels. Other features of a
closure device and methods of use are described in U.S. patent
application Ser. No. 12/055,213 (published as U.S. Pub. No.
2008/0243183 A1), which is hereby incorporated by reference in its
entirety. Another example of a closure device and methods of use
are described in U.S. patent application Ser. No. 12/752,873,
entitled "Tissue Ligation Devices and Controls Therefor," filed
Apr. 1, 2010, which is hereby incorporated by reference in its
entirety.
LAA Access Device
[0045] As described above, a variety of devices with different
functions may be inserted through the working channel(s) of the
elongate body of a closure device to secure and/or otherwise
manipulate a portion of tissue. In procedures where access to an
internal tissue structure may be desired (e.g. accessing a lumen of
a hollow organ or vessel), an access device may be inserted through
the working channel of the closure device after the closure device
has been advanced at or near the target tissue (e.g., by advancing
the closure device over a guide element). Access devices may create
a way for the internal portion of a tissue to be accessed from
outside the tissue. In some variations, access devices may create
an incision, puncture, and/or opening, etc., which may be dilated
to allow access to devices larger than the initial opening.
Optionally, some variations of an access device may also comprise a
guide wire that may be advanced into the created access site. One
example of such a device is shown in FIGS. 3A and 3B. FIG. 3A shows
individual components of one variation of an access device that may
be used to access a LAA or other tissue, and FIG. 3B shows the
access device of FIG. 3A fully assembled. In this variation, LAA
access device (300) comprises an access wire (302), a piercing wire
(304), and an actuator portion (306). The access wire (302) may
comprise a lumen (303) therethrough, where the lumen (303) may be
sized and shaped for the passage of a piercing element
therethrough, e.g. the piercing wire (304). The access wire (302)
may be made of a metal alloy or one or more polymers that have
mechanical properties suitable for threading the LAA access device
(300) in the working lumen of a LAA stabilizing device and for
guiding the piercing element. The access wire (302) may be made of
a variety of materials, including but not limited to nitinol,
stainless steel, as well as polymeric materials such as
polyethylene, polypropylene and the like. The piercing wire (304)
may be threaded through the lumen (303) of the access wire (302),
and may comprise a piercing tip (308) at the distal portion. The
piercing tip (308) may be used to create a puncture through the
LAA. Optionally, the piercing wire (304) may comprise a lumen
therethrough for the insertion of other devices, such as a
catheter, guide wire, suture, and/or may be used for the infusion
of fluids (e.g. gas or liquid fluids). In some variations, the
piercing tip (308) may be a needle that is attached to the distal
portion of the piercing wire (304). The piercing tip (308) may be
separately or integrally formed with the piercing wire (304), and
may have a lumen therethrough. The proximal portion of piercing
wire (304) may be coupled with the actuator portion (306). The
actuator portion (306) may be used to advance and/or withdraw
and/or steer and/or rotate the piercing wire (304), and may also be
used to maneuver the access wire (302) to access the LAA or other
target tissue. The actuator portion (306) may be manual or
mechanized, and may contain ergonomic features as appropriate, as
well as electrical/mechanical interfaces to receive and execute
instructions from a computing device or microcontroller. For
example, the actuator portion (306) may be made of a metal alloy
and/or one or more polymers that may be shaped to have an ergonomic
geometry. The actuator portion (306) may be made of any materials
that possess sufficient rigidity, flexibility, durability, etc., to
engage and control the mechanisms driving the use of the closure
device (200).
Corresponding Ablation Devices
[0046] Another example of a device that may be advanced through the
working channel(s) of the elongate body of a closure device is a
tissue-affecting device. Devices that affect tissue may generally
comprise one or more tissue-affecting elements, arranged in various
patterns. In some variations, two or more tissue-affecting devices
may be positioned along a target tissue, and used to affect the
tissue in a desired pattern, where the tissue-affecting elements
may be operated simultaneously or sequentially. In some variations,
the two or more tissue-affecting devices may be placed across each
other on opposite sides of tissue such that the tissue between them
is affected. One example of a tissue-affecting device is an
ablation device. Ablation devices may be provided for procedures
that aim to ablate a portion of tissue that is abnormal, for
example, cancerous tissue, or arrhythmic cardiac tissue. While
affecting tissue by ablation is described in detail here, tissue
may be affected in other ways, including by excision, occlusion,
manipulation and the like. As described below, an ablation device
may be used to ablate fibrillating atrial tissue, which may help to
prevent the conduction of the irregular or asynchronous pulses in
one tissue region to another tissue region.
[0047] In some variations, ablation devices may be used to create a
lesion in the fibrillating atrial tissue. For the treatment of
atrial fibrillation, one or more tissue-affecting devices, such as
ablation devices, may be positioned on the endocardial surface
and/or the epicardial surface of the left atrium. One example of an
endocardial ablation device that may be inserted through a closure
device is shown in FIG. 4. Endocardial ablation device (400) may
comprise an elongate body (402), a handle portion (404), one or
more ablation source(s) (406), and an ablation array (408). The
elongate body (402) may be sized and shaped to be inserted through
a working channel of a closure device, or any suitable guide
cannula or sheath. The elongate body (402) may comprise one or more
lumens therethrough, where the lumens may be configured to pass
devices or fluids from the proximal handle portion (404) to the
ablation array (408) at the elongate body distal portion. The
elongate body may have any number of pre-formed curves for ease of
navigation to the target tissue, and may optionally be flexible
and/or steerable. While the elongate body (402) may be one
continuous segment, other variations of an elongate body may be
made of multiple articulating segments, and may be made of one or
more flexible and/or rigid materials. In some variations, the
elongate body may be steerable via a mechanism in handle portion
(404), and as previously described for the closure device. In
variations where the elongate body is passed through a portion of a
closure device, the curvature and steerability of the elongate body
(402) may correspond to the curvature and steerability of the
closure device. This may help to inform a practitioner of the
orientation of the endocardial ablation device with respect to the
orientation of the closure device.
[0048] As shown in FIG. 4, the ablation array (408) may be located
at the distal portion of elongate body (402). An ablation array may
comprise one or more tissue-affecting elements that may be used for
ablating and/or otherwise forming a lesion in tissue. For example,
the ablation array (408) may comprise magnets (410) and ablation
elements (412) that may be arranged, for example, along pre-formed
curves or loops of the ablation array (408). The elongate body may
also comprise magnets. The magnets may be of any suitable type. For
example, the magnets may be rare-earth, electro-activated, or a
multi-alloy (e.g. iron, boron, neodymium) magnets. The magnets may
also have any suitable size or shape. More generally, the distal
portion of an elongate body may have any open-shape or closed-shape
geometry, and the magnetic and/or ablation elements may be arranged
along the elongate body, ablation array, and/or on a structure at
least partially enclosed within the perimeter of a shaped distal
portion of the elongate body. In some variations, the ablation
elements may themselves be magnetic. There may be any number of
magnets (410) having any suitable configuration(s) or pattern(s),
placed at any suitable location on the ablation array. For example,
the magnets (410) may be arranged in a straight or curved line
along the curvature of the ablation array (408), as shown in FIG.
4. Magnets may also be arranged along a length and a width of
ablation array. There may be any number of ablation elements (412)
as may be suitable to help ensure that sufficient ablation coverage
of the target area is provided. For example, there may be 1, 2, 3,
5, 10, 12, 20, etc. ablation elements. In general, ablation
elements may be utilize any mechanism and be in any form that
conveys the ablation energy/medium to the target tissue. For
example, cryo-ablation elements may comprise conduits that may
circulate a cryogenic substance in conductive proximity to the
target tissue. Ablation elements may be electrodes that ablate
tissue via radiation or heat energy. Alternatively or additionally,
ablation elements may be outlets or ports that infuse substances
that cause necrosis or apoptosis. For example, ablation elements
may ablate tissue using one or more methods, such as cryo-ablation,
heat ablation, high intensity focused ultrasound (HIFU) ablation,
radiofrequency (RF) ablation, laser ablation, or combinations of
the listed methods and/or any method that causes necrotic or
apoptotic cell and/or tissue death. Some ablation arrays may
comprise two or more different types of ablation elements, e.g., 2,
3, or 4 types of ablation elements. In some variations, an ablation
array may comprise both RF and cryo-ablation elements. In some
variations, an ablation array may comprise RF electrodes and HIFU
electrodes. In still other variations, an ablation array may
comprise laser emitters and RF electrodes. In some variations, an
ablation array may comprise HIFU electrodes, RF electrodes, and
cryo-ablation elements. The different types of ablation elements on
an ablation array may be activated simultaneously and/or
sequentially in the course of ablating tissue. Alternatively or
additionally, ablation elements may be sharp elements, e.g.
needles, that excise, cut, or pierce tissue, or any combination of
the above. For example, an endocardial ablation device may comprise
electrode ablation elements and needle ablation elements.
[0049] The shape of the ablation array (408) as shown in FIG. 4 is
semi-circular, which may be suitable for circumscribing and
ablating around a vascular structure, such as a pulmonary vein,
however, other variations of ablation arrays may have other shapes.
For example, an ablation array may have a planar structure with a
length and a width, with ablation elements arranged along both the
length and the width. An ablation array may also be a
one-dimensional array, e.g., a linear structure, where the ablation
elements are arranged linearly therealong. Indeed, ablation arrays
may be any shape suitable for accessing and contacting the target
tissue. For example, the semi-circular shape of ablation array
(408) may be suited for circumscribing vascular structures, such as
veins or arteries, and may be configured to create circular
ablation patterns. Ablation arrays may also have a tapered region
that may be helpful in accessing and contacting in the lumen of
tubular structures, e.g., the inner lumen of a vein. In some
variations, an ablation array may have a narrow undeployed
configuration and an expanded deployed configuration. For example,
an ablation array may be constrained in a sheath for delivery, and
may expand into the deployed configuration by removing the sheath.
In another variation, a curved ablation array may be retained in a
straight configuration by a straightening mandrel for delivery, and
may be expanded into the curved deployed configuration by removing
the mandrel. Other variations will be described in detail
below.
[0050] The ablation array (408) may be made from a flexible or
shape-memory material, such that it may be advanced to the target
tissue in a substantially straight configuration, and may be
deployed and contacted to tissue in a curved configuration. In some
variations, the ablation array is made of a different material from
the remainder of the ablation device (400), and may have different
mechanical properties. For example, the proximal portion (405) of
the elongate body may be made of a first material, while the distal
portion (407) and/or the ablation array may be made of a second
material. Examples of materials that may be suitable for the
proximal portion (405) and/or the distal portion (407) of the
elongate body may include metal alloys such as nickel titanium
alloy, stainless steel, and/or any polymers, such as polyethylene,
polyurethane, polypropylene, polytetrafluoroethylene, polyimide,
etc., and/or any combinations thereof. In some variations, an
ablation array may be integrally formed with the proximal portion
of the ablation device, or may be attached via an articulating
hinge. The ablation array may also be attached by other mechanical
mechanisms, such as a living hinge, pivot joint, ball joint, etc,
which may allow the ablation array to move with respect to the
proximal portion of the ablation device (e.g., with two or more
degrees of freedom).
[0051] The handle portion (404) located at the proximal end of
elongate body may comprise actuating elements that control the
movement and/or action of the elongate body and ablation array. In
some variations where endocardial ablation device (400) is manually
operated, the handle (400) may be ergonomic, while in other
variations where the device is mechanically/electrically operated,
handle (400) may comprise an interface to receive and execute
instructions from a computing device. The handle portion (404) may
comprise an ablation array actuator (414), which may be used to
regulate application of ablation energy/substances to the ablation
array to the target tissue (e.g. frequency, duty cycle,
magnitude/amplitude, etc.). Additionally, the handle portion (404)
may comprise an actuating mechanism that controls the movement
(e.g., bending, flexing, etc.) and position of elongate body (402).
The handle portion (404) may also comprise an interface to the
ablation source(s) (406), and provide a conduit or conduction
pathway from the ablation source(s) (406) to the ablation array.
For example, the ablation source (406) may comprise a reservoir of
cryogenic substances (e.g., for cryo-ablation), which may be
transported through a lumen in the elongate body (402) to the
ablation array. Alternatively or additionally, the ablation source
(406) may comprise a source of radioactive substances (e.g.,
radioactive seeds or fluids), and/or a light beam source (e.g., for
laser ablation), and/or an ultrasound source (e.g., for HIFU
ablation), and/or a radiofrequency source, and the like, which may
be delivered or transmitted from the handle portion to the ablation
array. In some variations, different ablation sources may be used
together in the same ablation device.
[0052] Depending on the tissue to be ablated and the desired
ablation pattern (e.g. lesion geometry and size) desired, a second
ablation device may be provided, where the second ablation device
corresponds to the first ablation device. A second ablation device
may increase the tissue ablation area and/or may otherwise alter
the ablation characteristics of the first ablation device (e.g. by
constructive or destructive interference). For the purposes of
ablating tissue of a left atrium, a second ablation device may be
provided to help ensure that the lesion formed by ablating tissue
spans at least portion of tissue that is between them. In the
treatment of atrial fibrillation it may be desirable to
electrically isolate the fibrillating tissue from other tissues. In
some variations, the formation of a lesion that spans the entire
thickness of the atrial wall (e.g., from the endocardial surface to
the epicardial surface) using one or more ablation devices may
improve the electrical isolation of a portion of the atrial wall
from other portions of the heart. Accordingly, in some variations,
ablation devices may be placed on opposite sides of a tissue wall
such that a lesion that spans a substantial portion of the tissue
wall between the ablation devices may be formed. In some
variations, positioning a first ablation device on an interior wall
(endocardial surface) of the left atrium, and positioning a second
ablation device on an exterior wall (epicardial surface) of the
left atrium opposite to the first ablation device, may help form a
lesion that spans at least a portion of the tissue between the
first and second ablation devices. FIG. 5 illustrates one variation
of an epicardial ablation device (500) that may be used with an
endocardial ablation device to form a lesion in the left atrium.
The epicardial ablation device (500) may comprise an elongate body
(502), handle portion (504), ablation source (506), and an ablation
array (508). As shown in FIG. 5, the ablation array (508) may be
located at the distal portion of elongate body (502). The ablation
array (508) may comprise magnets (510) and ablation elements (512)
which may correspond to the magnets (410) and ablation elements
(412) of the endocardial ablation device (400). The magnets of the
epicardial and endocardial ablation devices attract each other when
the ablation arrays are placed on opposite sides of tissue, which
may act to align the epicardial and endocardial ablation devices.
For example, the magnets (510) may be positioned on the epicardial
ablation array (508) such that they may be aligned with the magnets
(410) of the endocardial ablation array (408), e.g. magnets (510)
may correspond to, or be mirror images of magnets (410). As with
the magnets, the ablation elements (512) may correspond to, or be
mirror images of the ablation elements (412), or they may be
interlaced between the ablation elements (412). In some variations,
the alignment and attraction of the magnets may position the
endocardial and epicardial ablation devices such that the ablation
elements of the ablation devices are aligned across from each
other. The shape of the ablation array (508) as shown in FIG. 5 is
semi-circular, however, other variations of ablation arrays may
have any shape as may be suitable for accessing and contacting the
target tissue. In some variations, the shape of ablation array
(508) may be a mirror image, or complementary image, of the
endocardial ablation array (408). For example, the semi-circular
shape of the ablation array (508) may be suited for circumscribing
vascular structures, such as veins or arteries. Other variations
will be described in detail below. The ablation array (508) may be
made from a flexible or shape-memory material, such that it may be
advanced to the target tissue in a substantially straight
configuration, and may be deployed and contacted to tissue in a
curved configuration. For example, ablation array may be advanced
to, and contacted with, an external wall of a vascular structure,
e.g. artery, vein, heart chamber, and/or atrial appendage. The
ablation elements of the endocardial array and the epicardial array
may be in communication with each other, so that they may apply
ablation energy in a concerted or programmed fashion.
[0053] The handle portion (504) located at the proximal end of
elongate body may comprise actuating elements that control the
movement and/or action of the elongate body and ablation array. In
some variations where the endocardial ablation device (500) is
manually operated, the handle (500) may be ergonomic, while in
other variations where the device is mechanically/electrically
operated, the handle (500) may comprise an interface to receive and
execute instructions from a computing device. The handle portion
(504) may comprise an ablation array actuator (514), which may be
used to regulate application of ablation energy/substances to the
ablation array to the target tissue (e.g. frequency, duty cycle,
magnitude/amplitude, etc.). In some variations, the handle portion
(504) may be in communication with the handle portion (404) of the
endocardial ablation device (400), such that ablation energy from
both ablation devices may be applied in-phase or out-of-phase to
form a desired ablation wavefront and/or profile. Additionally, the
handle portion (504) may comprise an actuating mechanism that
controls the movement and position of elongate body (502). The
handle portion (504) may also comprise an interface to ablation
source(s) (506), and provide a conduit or conduction pathway from
the ablation source(s) (506) to the ablation array. For example,
the ablation source (506) may comprise a reservoir of cryogenic
substances (e.g., for cryo-ablation), which may be transported
through a lumen in the elongate body (502) to the ablation array.
Alternatively or additionally, the ablation source (506) may
comprise a source of radioactive substances (e.g., radioactive
seeds or fluids), and/or a light beam source (e.g., for laser
ablation), and/or an ultrasound source (e.g., for HIFU' ablation),
and/or a radiofrequency source, and the like, which may be
delivered or transmitted from the handle portion to the ablation
array. In some variations, different ablation sources may be used
together in the same ablation device.
Variations of Ablation Arrays
[0054] While the ablation devices depicted and described in FIGS. 4
and 5 are shown as having a semi-circular shape, ablation arrays
may have other geometries. Ablation and/or other tissue-affecting
arrays may have a variety of geometries and sizes as appropriate to
accommodate and contact the target anatomical structure. For
instance, ablation arrays with various geometries may be suitable
for contacting and ablating tissue, especially vascular or cardiac
tissue. Several variations of ablation arrays are shown in FIGS.
6A-6F. A side view and front view of a spiral ablation array (600)
inserted in the opening of a vascular structure (603) (e.g.
pulmonary vein) is shown in FIGS. 6A and 6B, respectively. As shown
there, the spiral ablation array (600) may be coupled to the distal
portion of an elongate body (602), where ablation elements (604)
and magnetic elements (606) are arranged throughout the curves of
the array (600) such that they may contact the walls of the
vascular structure (603). FIGS. 6C and 6D depict a side view and a
front view of a woven ablation array (610), respectively. The
ablation array (610) may be attached at the distal portion of an
elongate body (612), and may comprise a woven portion (615) and a
rim (617) located along a distal perimeter edge of the woven
portion. Ablation elements (614) and/or magnetic elements (616) may
be arranged throughout the array, for example, along the rim (617)
and/or on various locations on the woven portion (615). The size
and shape of the woven portion (615) may be configured to position
the ablation elements (614) and the magnetic elements (616) in
order to accommodate the geometry of the target tissue (613), e.g.,
where the expanded size and shape of the woven portion may be bent,
shaped, molded or otherwise constrained by the geometry of the
target tissue. The woven portion (615) may be used as an ablation
conduit or array, and may be arranged to be in proximity to target
ablation tissue. Alternatively or additionally, the woven portion
(615) may help stabilize the array (610) during ablation without
occluding the pulmonary vein. The woven portion (615) may be
constructed from various fibers, where the density of the weave may
be adjusted according to the degree of perfusion desired. The
fibers of the woven portion may be made of polypropylene,
polyurethane, polyethylene, polytetrafluoroethylene, as well as
metal alloys such as stainless steel and/or nickel titanium alloy.
The woven portion may be self-expanding or mechanically expanded to
fill the lumen or orifice of the vascular structure, and may be
adjusted according to the size of the vascular structure. In some
variations, the woven portion may be made of a shape-memory
material so that the woven array (610) may have a compressed
delivery configuration and an expanded deployed configuration. The
size of the woven portion may be adjusted to ablate anatomical
structures with dimensions of about 8.0 mm to about 30 mm, or about
12.0 mm to about 18.0 mm. Another variation of an ablation array
(620) is shown in FIGS. 6E and 6F. As shown there, a tapered spiral
ablation array (620) may be coupled to the distal portion of an
elongate body (622), where ablation elements and/or magnetic
elements may be arranged throughout the tapered spiral ablation
array (620). The tapered spiral ablation array (620) may comprise a
single continuous flexible backbone that is wound around the
elongate body (622). Ablation elements may be distributed along the
length of the backbone. In some variations, the backbone of the
spiral ablation array (620) may be a wire that is electrically
conductive, and may itself be capable of ablating tissue without
additional ablation elements. The spiral ablation array (620) may
have a first collapsed configuration shown in FIG. 6E, where the
ablation array may be closely wound around the distal portion of
the elongate body (622), e.g., with a tight radius of curvature.
The narrow profile of the array in the collapsed configuration may
help navigate the array atraumatically through narrow anatomical
structures, and may also be inserted into folded or creased tissue
structures. The ablation array (620) may be retained in its
collapsed delivery configuration by a sheath that may be slidably
disposed over the array (not shown), and/or by retaining tension on
the backbone. FIG. 6F depicts a second expanded configuration of
the tapered spiral ablation array (620), where removing the sheath
and/or reducing the tension on the backbone of the spiral ablation
array (620) may allow the backbone to loosen the radius of
curvature such that the profile of the array expands. In some
variations, expanding the ablation array may act to dilate a narrow
tissue structure, e.g., open a folded or creased tissue structure,
enlarge a tissue lumen or aperture for the insertion of additional
devices, etc. In some variations, the ablation array (620) may help
to maintain perfusion during ablation, and may be an alignment
reference point for epicardial elements at various locations along
the pulmonary veins. The ablation and magnetic elements may be
arranged in any of the previously described configurations, and may
be arranged to help stabilize the ablation device during the
ablation procedure.
[0055] Any of the ablation arrays described above may optionally
comprise one or more temperature sensors. Temperature sensors may
be used to measure the ablation energy that has been applied to a
tissue, and may be used to evaluate the degree to which tissue is
ablated. The measurement of temperature changes in the tissue
during the application of ablation energy may be used to regulate
the duration, power, and/or frequency of the ablation energy (e.g.,
by providing feedback information to the ablation array and/or
ablation array controllers). Monitoring the temperature of the
tissue during ablation may also help prevent excessive or harmful
damage to peripheral tissues. The one or more temperature sensors
may be thermocouples, thermsistors, thermal resistive sensors
(RTD), and the like. One example of an ablation array with
temperature sensors is depicted in FIG. 6G. Ablation array (630)
may comprise an ablation array substrate or housing (634), one or
more ablation elements (not shown), one or more alignment magnets
(638) and one or more atraumatic temperature sensors (636) on the
tissue-facing surface of the ablation array. The alignment magnets
(638), temperature sensors (636), and ablation elements may be
arranged in any suitable configuration on the tissue-facing surface
of the ablation array, for example, the alignment magnets (638) may
be arranged such that the ablation elements of two ablation arrays
positioned on opposite sides of a tissue may attract each other to
align the ablation elements of one ablation array to the other. The
atraumatic temperature sensors (636) may be pressed into the tissue
(632) without puncturing or piercing it to measure the temperature
of the tissue. Another example of an ablation array with
temperature sensors is depicted in FIG. 6H. Ablation array (640)
may comprise an ablation array substrate or housing (644), one or
more ablation elements (not shown), one or more alignment magnets
(648) and one or more sharp temperature sensors (646) on the
tissue-facing surface of the ablation array. The alignment magnets
(648), temperature sensors (646), and ablation elements may be
arranged in any suitable configuration on the tissue-facing surface
of the ablation array, as previously described. The sharp
temperature sensors (646) may be inserted into tissue (642) to
measure the temperature of the tissue at a certain depth from the
surface of the tissue (642). In some variations, the sharp
temperature sensors (646) may pierce or puncture the tissue (642)
in order to gain access to deeper tissue regions. The sharp
temperature sensors (646) may also have a length that corresponds
to the thickness of the tissue, and in some cases, may penetrate
through the entire length of the tissue. Temperature sensors that
penetrate through substantially the entire thickness of the tissue
may provide temperature data across the entire span of the tissue,
which may provide an indication of the uniformity of the tissue
ablation, as well as provide information about the temperature
gradient across the tissue. This may help improve the accuracy of
the tissue temperature measurement that is fed back to the ablation
array and/or ablation array controllers.
[0056] In the variations depicted in FIGS. 6G and 6H, the alignment
magnets and temperature sensors are located adjacent to each other,
however, in other variations, the alignment magnets and temperature
sensors may be incorporated together in one location. This may help
to reduce the overall size of the ablation array, which may reduce
the profile of the array for ease of delivery to the target tissue
site. For example, an ablation array may have alignment magnets
that have a lumen sized and shaped for encapsulating a temperature
sensor. FIG. 61 depicts a regions of one example of an ablation
array (650) comprising a housing (654), a temperature sensor (656)
and an alignment magnet (658) encapsulating the temperature sensor.
The alignment magnet (658) may comprise a lumen (657) that is sized
and shaped for the temperature sensor (656). The temperature sensor
(656) (which may be an atraumatic or tissue-piercing or sharp
temperature sensor) may protrude from the lumen (657), or may be
flush with the opening of the lumen (657). In other variations, an
ablation array may comprise one or more ablation elements that each
comprise a lumen such that a temperature sensor may be encapsulated
in the lumen. In still other variations, an ablation array may
comprise ablation elements, alignment magnets, and/or temperature
sensors that may be retracted into a housing of the ablation array.
For example, during delivery of the ablation array to the target
tissue site, the ablation elements, alignment magnets, and/or
temperature sensors may be in a first retracted configuration, such
that the profile of the ablation array is narrow. After the
ablation array has been generally positioned at the target tissue
site, the ablation elements, alignment magnets, and/or temperature
sensors may be a second protracted configuration, where the
ablation elements, alignment magnets, and/or temperature sensors
are capable of contacting the target tissue for alignment,
ablation, and/or measurement of temperature.
Occlusion Device
[0057] As described previously, some methods may include steps to
help maintain hemostasis in the course of the procedure for the
treatment of atrial fibrillation. For example, in procedures where
access to an endocardial surface of the heart is gained using the
LAA as a port, it may be desirable to close and/or exclude the LAA
to maintain hemostasis and/or help prevent thrombosis. In some
variations, a procedure for the treatment of atrial fibrillation
may also include the temporary or permanent closure, and/or
occlusion, and/or removal of the left atrial appendage. FIG. 7
illustrates one variation of an occlusion device (700) that may be
used with the devices and methods described here. The occlusion
device (700) may comprise an elongate body (702), an insert port
(704) at a proximal portion of the elongate body, and an expandable
member (706) at a distal portion of the elongate body. The elongate
body (702) may have one or more lumens, for example, a guide wire
lumen (708) sized and shaped for passing a guide wire therethrough.
The elongate body (702) as shown in FIG. 7 may also comprise one or
more side apertures (710) and imaging markers (712). Any number of
side apertures (710) may be provided for infusion of any fluid
substance, such as a contrast agent or pharmacological agent (e.g.,
heparin, antibacterial agent, etc.). The imaging markers (712) may
be radiopaque or echogenic, etc., as appropriate for the imaging
modality used to monitor the position of the occlusion device
(700).
[0058] The elongate body (702) may be made from one or more rigid
and/or flexible materials. In some variations, the elongate body
(702) may be steerable. An insert port may comprise one or more
apertures for the insertion of fluids or devices through the
elongate body (702). For example, the insert port (704) may
comprise a guide wire aperture (714) and a fluid lumen (716). The
guide wire aperture (714) and the fluid lumen (716) may each have
independent lumens that may merge into one lumen at a bifurcation
(717) of the insert port (704), or may each have separate lumens in
the elongate body (702). The guide wire aperture (714) may be
continuous with the guide wire lumen (708), and the fluid lumen
(716) may be continuous with a cavity of the expandable member
(706), such that the introduction of fluid into or out of the fluid
lumen (716) may expand or constrict the expandable member.
Optionally, the insert port (704) may also comprise actuation
mechanisms for navigating and adjusting the shape of the elongate
body (702), as well as control the motion of a guide wire, and the
expansion of the expandable member (706).
[0059] The expandable member (706) may be any structure that
comprises a first small profile and a second larger profile, for
example, a balloon or an articulating polygonal structure, e.g.
rectangular prism or tetrahedron, and the like. The expandable
member (706) may be sized and shaped to fit within the guide wire
lumen (208) of the closure device (200) so that it may be advanced
and/or withdrawn through the lumen (208). In some variations, the
expandable element (706) may have a first collapsed configuration,
and a second expanded configuration. For example, the rounded
expandable element (706) shown in FIG. 7 may have a diameter of
about 15 mm to about 30 mm, e.g., 20 mm. The expandable member may
be made of various materials, including polymeric and/or metallic
materials. Examples of polymers that may be used in an expandable
member may include materials such as latex, silicone, polyisoprene,
polyethelene. Example of metals and/or metallic alloys that may be
used with an expandable member may include nitinol, stainless
steel, titanium and the like. The expandable member may be
configured to either self expand or be mechanically expanded by an
actuator. For example, the expandable member (706) may be
transitioned from the small profile to the larger profile by
introducing positive pressure or by a mechanical actuation. In some
variations, a balloon expandable member may be urged into the
larger configuration by applying positive fluid (gas or liquid)
pressure into the lumen of the balloon. The expandable member may
have any shape and size as appropriate for the target tissue. For
example, a round expandable balloon may be used to occlude a
vascular structure, such as a vein or an atrial appendage, e.g.
LAA.
[0060] Another variation of a device that may be used for occluding
the LAA is depicted in FIGS. 18A and 18B. As shown there, an
occlusion device (1820) may comprise grooves (1822) in its deployed
configuration. In some variations, the closure device may be
deployed and positioned at the anatomical ostium of a left atrial
appendage (1800). However, the occlusion device (1820) may be
positioned at any desired location in the heart. The occlusion
device (1820) may have a collapsed delivery configuration, which
may enable it to be enclosed within a catheter or sheath and
advanced through the vasculature (e.g., from a retrograde approach,
or an antegrade transseptal approach) or through a port in the LAA.
The occlusion device (1820) may be deployed into its expanded
configuration after it is positioned at or near the ostium of the
LAA. In some variations, the occlusion device may be a rounded
plate or disc comprising one or more grooves circumscribing the
outer perimeter. Grooves (1822) may be configured to interfit with
a closure element (1810) (e.g., suture loop or snare loop) of a
closure device as the circumference of the closure element is
reduced, as shown in FIG. 18B. The occlusion device (1820) may be
sized according to the desired degree of closure of the left atrial
appendage (1800). Once the closure element (1810) has been secured
and decoupled from the rest of the closure device (e.g., by cutting
or detaching at a breakaway point), the occlusion device (1820) may
be reverted to its collapsed configuration and withdrawn from the
ostium of the left atrial appendage (1800). The devices and methods
described above for closing and/or excluding the left atrial
appendage may be included at the conclusion of a procedure that
uses the left atrial appendage as an access site. This may be a
more expedient method of closing a heart access site than other
conventional methods, such as suture stitching, which may be
substantially more time-consuming.
[0061] The above-described devices may be used to secure, ablate,
and excise a portion of tissue to help alleviate the symptoms of
atrial fibrillation. For example, the devices above may be used to
secure a LAA, ablate atrial tissue in the proximity of the LAA and
the pulmonary veins, and to close, and/or occlude, and/or remove
the LAA. While the description below provides methods of securing,
ablating, and excising tissue of the left atrium and/or LAA, it
should be understood that the methods may be used to perform
similar procedures on the right atrium, as well as other vascular
structures or organs. Similar methods may also be used to secure,
ablate, and excise tissues and/or organs that have one or more
cavities therethrough, e.g. stomach, intestine, bladder, etc., for
a variety of indications.
III. Methods
[0062] Methods for ablating tissue for the treatment of atrial
fibrillation may generally comprise accessing targeted cardiac
tissue regions, advancing ablation arrays to the targeted tissue
regions, ablating the tissue regions, and withdrawing the ablation
arrays once the desired degree of tissue ablation has been
attained. Additionally, some methods may include the closure of the
left and/or right atrial appendages, which may help reduce the risk
of thrombosis and may help maintain hemostasis. Some variations of
methods for tissue ablation may comprise ablating the tissue from
an endocardial surface, an epicardial surface, or both. Ablation
devices may access an endocardial surface of the left atrium
intravascularly, and/or through the LAA via the pericardial space.
Once the one or more ablation devices have been placed on the
endocardial and/or epicardial surface(s), the ablation devices may
be activated sequentially and/or simultaneously to achieve the
desired degree of tissue ablation. Ablation array activation
sequences may be repeated as may be desirable, and may comprise
applying ablation energy pulses (from either or both of the
endocardial and epicardial ablation arrays) of varying duration,
frequency, duty cycle, power, intensity, etc. The ablation array(s)
may be re-positioned to ablate tissue at various desired locations.
Once all the desired tissue regions have been ablated, the ablation
arrays may be withdrawn. In variations where the LAA is used to
access the endocardial surface on the left atrium, the LAA may be
closed and/or excluded.
Epicardial and Endocardial Ablation
[0063] One variation of a method that may be used to electrically
isolate tissue in the left atrium and/or LAA is depicted as a
flowchart in FIG. 8A. Method (800) may be used to ablate tissue
from both epicardial and endocardial surfaces using surgical,
intravascular and/or other minimally invasive techniques (e.g.,
percutaneous, small incisions or ports), and may be used in stopped
heart or beating heart procedures. The method (800) may comprise
gaining access to the pericardial space (802), for example, using
the access devices described above. Optionally, a device may be
used to locate and stabilize the LAA (804), for example, the
closure device (200) as described above and shown in FIG. 2. Once
access into the pericardial space and to the LAA has been
established, a device may be used to enter the LAA (806), for
example, by creating a puncture in the LAA. Additional devices and
methods of using the LAA as an access port to deliver devices into
the heart (e.g., to contact and/or affect an endocardial surface of
the heart) are described in U.S. Provisional Patent Application No.
61/323,816 filed Apr. 13, 2010, which was previously incorporated
by reference in its entirety, and U.S. patent application Ser. No.
______ entitled "Methods and Devices for Accessing and Delivering
Devices to a Heart," filed Apr. 13, 2011, which is hereby
incorporated by reference in its entirety. Various tissue regions
in the left atrium (e.g., atrial wall tissue, tissue at or around
the base of the pulmonary veins, tissue within the pulmonary veins,
etc.) may be accessed from an endocardial side (810). Devices may
be introduced into the left atrium through the LAA, for example, an
endocardial ablation array may be positioned and placed in the left
atrium (812). An epicardial ablation array may be aligned with the
endocardial ablation array (814), for example, based on the
position of the corresponding magnets on the endocardial and
epicardial ablation arrays. The epicardial ablation array may be
introduced to the epicardial surface of the heart using the same
initial access site as the endocardial ablation array, or may be
introduced through a different access site. For example, the
endocardial ablation array may be introduced through a right
intercostal site, while the epicardial ablation array may be
introduced through a left intercostal site. Alternatively, the
endocardial and epicardial ablation arrays may both be introduced
through a left intercostal site, for example. Additional
description of access sites are described below. The endocardial
and epicardial ablation arrays may be positioned in order to obtain
a particular ablation pattern, after which both ablation arrays may
be activated (816). For example, the endocardial ablation array may
circumscribe the base of the pulmonary veins, while the epicardial
ablation array may circumscribe the trunk of the pulmonary veins.
After the desired tissue regions have been ablated, the ablation
devices may be removed (818), and the LAA may be occluded, closed,
and/or removed (820). Once the LAA has been decoupled from the
remainder of the left atrium, all devices may be retracted from the
surgical site (822).
[0064] As described previously, the endocardial side of the left
atrium may be accessed intravascularly and/or from the LAA via the
pericardial space. The access path into the left atrium may be
selected based on the targeted anatomical features in the left
atrium such that the path length of the catheter and/or ablation
devices may be reduced. The access path may also be selected to
reduce the maneuvering, manipulating, bending, torquing, etc. that
may be required to position the catheter and/or devices at the
targeted tissue site in the left atrium. For example, an
endocardial ablation device may access the left atrium using either
an intravascular retrograde approach or an antegrade transseptal
approach. Entering the left atrium via an intravascular antegrade
transseptal approach may allow access to the left pulmonary veins
while reducing the maneuvering, manipulating, bending, torquing,
etc. of the distal portion of the device. Entering the left atrium
via an intravascular retrograde approach may allow access to the
right and left pulmonary veins while reducing the maneuvering,
manipulating, bending, torquing, etc. of the distal portion of the
device. Alternatively or additionally, entering the left atrium
through the LAA via a pericardial approach may allow access to the
right pulmonary veins without much maneuvering, manipulating,
bending, torquing, etc. of the distal portion of the device. Any of
these approaches may be used to position an endocardial ablation
device in the left atrium. In some variations, a first endocardial
ablation array may enter the left atrium through an intravascular
approach, and a second endocardial ablation array may enter the
left atrium through the LAA via a pericardial approach.
[0065] One example of a method (830) that comprises accessing the
endocardial surface of the left atrium both intravascularly and
through the LAA via the pericardial space is depicted in FIG. 8B.
As previously described, an access pathway may be created to the
pericardial space (832). A LAA access/exclusion device may be used
to locate and stabilize the LAA (834). Once access into the
pericardial space and to the LAA has been established, a device may
be used to create a LAA access site (836), e.g., by puncturing the
LAA, which may allow a device to access the left atrium through the
LAA. An intravascular pathway to the left atrium may also be
attained by advancing a delivery catheter through the vasculature
into the left atrium (838), e.g., using a retrograde or an
antegrade transseptal approach. Once the intravascular and/or LAA
access pathways into the left atrium have been established, a first
endocardial ablation array may be advanced into the left atrium
through the LAA (840). The first endocardial ablation array may be
positioned at any desired tissue region in the left atrium (e.g.,
atrial wall tissue, tissue at or around the base of the pulmonary
veins, tissue within the pulmonary veins, etc.), such as the tissue
along the bases of the right pulmonary veins (842). The first
endocardial ablation array may be activated to ablate tissue (844).
A second endocardial ablation array may be advanced intravascularly
through the delivery catheter into the left atrium (846). The
second endocardial ablation array may be positioned at any desired
tissue region in the left atrium (e.g., atrial wall tissue, tissue
at or around the base of the pulmonary veins, tissue within the
pulmonary veins, etc.), such as the tissue along the bases of the
left pulmonary veins (848). The second endocardial ablation array
may be activated to ablate tissue (850). An epicardial ablation
array may be advanced via the pericardial space to a location on
the outer surface of the heart (852), for example, a location
corresponding to either or both the endocardial ablation arrays
(854), and/or along tissue at or near one or more pulmonary veins,
e.g., at or around the trunks of the pulmonary veins. Additional
variations of advancing and positioning an epicardial device at
around the trunks of the pulmonary veins are described below. In
some variations, the endocardial ablation array(s) and the
epicardial ablation array may be positioned opposite each other
using alignment magnets. Once the epicardial ablation array is
positioned at the desired location, the epicardical ablation array
may be activated to ablate tissue (856). The positioning and
activation of the epicardial and endocardial ablation arrays may be
repeated as desired. After ablating the desired tissue regions, the
ablation arrays may be removed (858). The LAA may be closed with
the access/exclusion device (860), and then the access/exclusion
device may be removed (862).
[0066] While the steps of the method (830) have been described in
the sequence as depicted in FIG. 8B, it should be understood that
the steps may take place in an alternate sequence, and certain
steps may take place substantially simultaneously. For example, the
delivery catheter may be advanced intravascularly into the left
atrium (838) before or after the LAA access site is created (836).
In some variations, the epicardial ablation array may be positioned
on the epicardial surface of the heart (854) before either or both
of the endocardial ablation arrays are positioned in the left
atrium. The activation of the ablation arrays may occur
sequentially or simultaneously. For example, the first or second
endocardial ablation array and the epicardial ablation array may be
activated simultaneously. Alternatively or additionally, the first
and second ablation arrays and the epicardial ablation array may
all be activated simultaneously, and/or the first and second
ablation arrays may be activated simultaneously without activating
the epicardial ablation array. In some cases, the epicardial
ablation array may be activated without activating either or both
of the first and second ablation arrays. The method (830) involves
the use of two endocardial ablation arrays, but in other
variations, only one endocardial ablation array may be used to
ablate the left and/or right pulmonary veins. The single
endocardial ablation array may be advanced intravascularly or
through the LAA, as may be desirable.
[0067] The methods described above ablate the tissue of the left
atrium and/or pulmonary veins from both the endocardial and
epicardial surfaces, either simultaneously or sequentially.
Placement of the ablation arrays on both the endocardial and
epicardial surfaces may help ablate atrial tissue from both sides.
Ablating tissue simultaneously from both sides may help promote the
formation of a lesion that spans a significant portion of the
thickness of the tissue between the ablation arrays. A lesion that
spans a significant portion of atrial tissue thickness may help to
electrically isolate fibrillating tissue. The application of
ablation energy (e.g., phase, magnitude, pulse sequence, etc.),
type of ablation energy (e.g., radiofrequency, laser, high
intensity focused ultrasound, cryogenic agents, microwave energy,
heat energy, etc.), and the shape and size of ablation arrays may
be varied according to the geometry of the tissue and the ablation
profile desired. For example, the endocardial ablation array may
ablate tissue cryogenically, while the epicardial ablation array
may ablate tissue with heat energy. Alternatively, the endocardial
ablation array may ablate tissue using heat energy, while the
epicardial ablation array may ablate tissue cryogenically. In other
variations, the endocardial ablation array may ablate tissue using
HIFU, while the epicardial ablation array may ablate tissue using
microwaves. The type(s) of ablation energy used and the shape of
the ablation array may be selected to limit ablation of non-target
peripheral tissue.
[0068] While the methods and devices described here may be used to
ablate cardiac tissue, it should be appreciated that the methods
and devices described here may be adapted to ablate any tissue from
any two tissue surfaces. For example, endocardial and epicardial
ablation arrays may be adapted to ablate a tumor cell mass from one
or more surfaces. Endocardial and epicardial ablation arrays may
also be used to ablate tissue of a hollow organ (e.g., stomach,
bladder, lungs, vascular structures, etc.) by positioning them
opposite each other on both the inside and outside surfaces. When
two ablation arrays are placed on opposite sides of tissue, they
may ablate tissue therebetween in any variety of patterns, some of
which are shown in FIGS. 9A-9D. These ablation patterns are
described in the context of cardiac structures, however, it should
be understood that these patterns may be formed in any desirable
tissue, as described above. The ablation profile when using both
endocardial and epicardial arrays on atrial tissue (900) may vary
depending on the type of ablation energy (e.g. cryo-ablation, high
intensity focused ultrasound, radiofrequency, laser, etc.). For
example, as depicted in FIG. 9A, a first ablation array (908) may
be placed on the endocardial surface (904) and a second ablation
array (906) may be placed opposite the first ablation array (908)
on an epicardial surface (902) of atrial tissue (900). Both the
first and second ablation arrays (908, 906) may be simultaneously
operated, where the first ablation array (908) and the second
ablation array (906) may deliver ablation energy at substantially
the same time. In some variations, the ablation arrays are operated
to deliver ablation energy in-phase, out-of-phase, or at an offset
to form the ablation pattern (910). FIG. 9B depicts an ablation
pattern (920) that may arise when epicardial ablation array (916)
delivers ultrasound ablation energy (e.g., HIFU) that may be
reflected off endocardial array (918) back to epicardial array
(916). Similarly, FIG. 9C depicts an ablation pattern (930) that
may be formed when endocardial ablation array (928) delivers
ultrasound ablation energy that may be reflected off epicardial
array (926) back to endocardial array (928). FIG. 9D illustrates an
ablation pattern (940) that may arise when both endocardial
ablation array (938) and epicardial ablation array (936) reflect
the ultrasound ablation energy delivered by the opposite array.
[0069] The ablation pattern created in the tissue may be monitored
using one or more one or more temperature sensors on either or both
the endocardial and epicardial arrays. For example, as depicted in
FIG. 9E, epicardial ablation array (950) and endocardial ablation
array (951) may both comprise one or more temperature sensors (952)
and alignment magnets (954). Both the epicardial and endocardial
ablation arrays may comprise temperature sensors so that a
temperature change arising from activating the opposite ablation
array may be measured, and may be used to indicate the progress of
the ablation of tissue (953). In some variations, a temperature
threshold may be set such that reaching or exceeding that
temperature will signal an activated ablation array to deactivate.
This may be used to prevent excessive or harmful damage to tissue
(953). For example, the epicardial ablation array (950) may be
activated when the endocardial ablation array (951) is not
activated. The temperature sensors of the endocardial ablation
array (951) may provide a temperature measurement as a feedback
signal to the epicardial ablation array controller. For example,
the duration, magnitude, and other characteristics of the ablation
energy applied by the epicardial ablation array may be regulated
based on the temperature measured by the temperature probe on the
endocardial surface of the heart. The activation of the endocardial
ablation array (951) may be similarly regulated by temperature
feedback using the temperature sensors on the epicardial ablation
array. In other variations, temperature sensors may only be
provided on an ablation array on one side of the tissue, but not on
the ablation array on the other side of the tissue. For example, in
the example depicted in FIG. 9F, epicardial ablation array (960)
may have one or more temperature sensors (962), while endocardial
ablation array (961) may not have any temperature sensors. Both the
epicardial and endocardial ablation arrays comprise one or more
alignment magnets (964) that may be used to align the arrays with
respect to each other across tissue (954). The tissue (963) may be
clamped between the ablation arrays, such that the endocardial
ablation array (961) acts as a support for the penetration of the
temperature sensors of epicardial ablation array (960). The
temperature sensors (962) may have a length that spans over a
substantial thickness of tissue (963), which may allow the
temperature of the middle of tissue (963) to be measured. In some
variations, the temperature sensors of an ablation array may span
the entire depth of the tissue, as depicted in FIG. 9G. As seen
there, the temperature sensors (972) of the epicardial ablation
array (970) may span the entire thickness of the tissue (973) and
may, in some cases, even contact endocardial ablation array (971).
This may allow the temperature gradient across the tissue (973) to
be measured. For instance, it may be determined based on the
temperature measurement if the tissue is ablated in a uniform
manner, etc. Such data may be fed back to an ablation controller to
adjust the power, intensity, frequency, magnitude, etc. of the
ablation mechanism to attain the desired ablation pattern. As
described previously, the temperature sensors may be atraumatic or
may be tissue-piercing, as may be desirable.
[0070] One variation of a method for ablating tissue from both the
endocardial and epicardial surfaces is depicted in FIGS. 10A-10S.
Access to the pericardial space may be attained in a variety of
ways, some examples of which are shown in FIG. 10A. Additional
examples are described in U.S. Provisional Patent Application No.
61/323,801 filed Apr. 13, 2010, which was previously incorporated
by reference in its entirety, and U.S. application Ser. No.
13/086,328, filed on Apr. 13, 2011, entitled "Methods and Devices
for Pericardial Access," which is hereby incorporated by reference
in its entirety. As shown in FIG. 10A, a pericardial sac (1002)
encases the heart and LAA (1000). Access to the LAA (1000) may be
obtained from an initial site located in between ribs, or below the
rib cage (1004). For example, the pericardium may be accessed
through a right intercostal site (1006), a left intercostal site
(1008), or a sub-thoracic site (1010), below the costal cartilages.
The pericardium may also be accessed from below the diaphragm. In
some procedures, the pericardium may be accessed from multiple
sites, for example, from both right intercostal (1006) and left
intercostal (1008) sites, the right intercostal (1006) and
sub-thoracic (1010) sites, and the left intercostal (1008) and
sub-thoracic (1010) sites. Depending on the location of the tissue
targeted by one or more of the devices described herein, the access
sites may be selected such that the target tissue region may be
readily accessed. For example, an access site may be chosen for a
particular target tissue region such that the tissue region may be
reached by an ablation device without acute bending of the device,
and/or excessive device maneuvering, manipulating, bending,
torquing, etc. In some variations, an access site may be selected
to reduce the path length between the initial entry site and the
target tissue. Pericardial access may be monitored and/or confirmed
using one or more imaging techniques, for example, fluoroscopy,
echocardiography, and endoscopy. Once access to the pericardium has
been established and confirmed, an incision or needle puncture may
be made in the pericardial sac (1002), where an incision size may
be based in part on the size of the device used for entry (e.g.,
guide wire, cannula, or any of the devices described here). In some
variations, a small incision or puncture may be initially made and
subsequently expanded by dilators to enable entry of other devices.
Entry of any device(s) into the pericardial sac (1002) may also be
monitored and confirmed using one or more imaging techniques as
described above.
[0071] Various devices may be introduced into the epicardial space
via an incision or puncture in the pericardium. FIG. 10B depicts a
side view of the LAA (1000) and the left atrium (1003), encased by
the epicardium (1001), myocardium (1005), and pericardial sac
(1002). Within the cavity of the left atrium (1003), the bases of
two pulmonary veins (1007a) and (1007b) may be seen. Devices may be
advanced towards the LAA (1000) by inserting guide wire (1014) into
a pericardial sac incision (1011). A guide cannula (1012) may be
advanced over the guide wire (1014). A guide cannula (1012) and a
guide wire (1014) may be steerable and/or pre-shaped according to a
desired access route, for example, an access route that enables the
penetration of LAA (1000) from between or under the rib cage. In
some variations, one or more dilators may be used to insert and
position the guide cannula (1012), after which the one or more
dilators may be removed. In some variations, the guide wire (1014)
may be removed after the guide cannula is positioned. Once in
place, the guide cannula (1112) may provide navigational support
and guidance to a LAA device, such as the LAA closure device (200)
shown in FIG. 2. One method of localizing and stabilizing the LAA
(1000) is depicted in FIG. 10C, where a LAA stabilizing device
(1020) may be advanced via the guide cannula (1012) towards the LAA
to contact the LAA. One variation of a LAA stabilizing device
(1020) may contact the LAA (1000) by advancing a vacuum device
(1022) through a looped closure assembly (1024). In this variation,
the vacuum device (1022) may apply negative pressure which may draw
a portion of the LAA (1000) into a collector, for example, one or
more lumens, a basket, any woven semi-rigid structure, or a cup
(1023), thereby securing the LAA. Some variations of the LAA
stabilizing device (1020) may also comprise graspers. Graspers may
be advanced through the looped closure assembly (1024) and such
that they may secure the wall of the LAA (1000). Optionally,
graspers may penetrate or pierce through the LAA wall. After the
desired level of LAA stability is attained by activating the vacuum
device (1022) and/or graspers, the looped closure assembly (1024)
may be advanced over the LAA, and closed over the LAA. In some
variations, the looped closure assembly may comprise a snare loop
and a suture loop releasably coupled to the snare loop, where the
snare loop and the suture loop may be separately tightened, and/or
tightened in a coordinated fashion. The suture loop may be released
and/or disengaged from the snare loop after the suture loop has
been tightened over the neck of left atrial appendage. In some
variations, the suture loop may be released from the LAA
stabilizing device (1020) after being closed and locked around the
LAA. In some variations, the looped closure assembly (1024) may be
closed to secure/locate the LAA, and then may be opened to allow
devices to be advanced therethrough, and then closed to
secure/locate the LAA. The opening and closing of the looped
closure assembly (1024) may help to maintain hemostasis during the
procedure. Examples of a looped closure assembly and other
stabilization and closure devices that may be used with the LAA
stabilization device (1020), along with other devices and methods
for ensnaring a LAA, are described in U.S. patent application Ser.
No. 12/055,213 (published as U.S. 2008/0243183 A1), which was
previously incorporated herein by reference in its entirety.
[0072] FIG. 10D illustrates the proximal portion of the LAA
stabilizing device (1020), which may comprise one or more ports,
for example, a vacuum source port (1021) and a needle port (1030),
and actuators (1028a) and (1028b). The vacuum source port (1021)
and the needle port (1030) may comprise valves to regulate the
passage of devices or fluids through the ports. Actuators (1028a)
and (1028b) may activate the looped closure assembly (1024) and the
vacuum device (1022), respectively. While the vacuum device (1022)
is activated (e.g. applying negative or positive pressure), an
access needle (1032) may be inserted into the needle port (1030).
The LAA access device (300) as described above and depicted in FIG.
3 may be used here. As seen in FIG. 10E, an access needle (1032)
may be advanced through the needle port (1030), through the LAA
stabilizing device, and through the vacuum device (1022) to
puncture and enter the LAA (1000). Optionally, before or after the
LAA is punctured by the access needle, looped closure assembly
(1024) may be adjusted, e.g. closed or opened, to control bleeding
and/or provide endocardial access to devices. Other hemostatic
devices (e.g., valves, plugs, etc.) may be used at or near the
needle puncture to control and/or limit bleeding. Once access
needle (1032) has penetrated the LAA, a standard guide wire (1031)
may be advanced into the LAA, and the access needle may be
withdrawn. In some variations, the access needle (1032) may remain
in the LAA and left atrium, to maintain the puncture in the LAA
and/or left atrium. After the guide wire (1031) is inserted into
the LAA and/or left atrium, the vacuum device (1022) may be
removed, as shown in FIG. 10F.
[0073] Optionally, LAA stabilizing devices may comprise additional
LAA attachment features that may further secure the LAA after it
has been stabilized, for example, as depicted in FIG. 10G. As shown
there, a distal segment of a LAA stabilizing device (1020') may
comprise a looped closure assembly (1024') and apertures (1025)
through which positive or negative pressure may be applied.
Negative pressure may be applied through apertures (1025) to draw
the LAA towards the device, further securing and stabilizing it. In
this variation, negative pressure may be applied to apertures
(1025) after looped closure assembly (1024') has effectively
encircled the LAA, which may help ensure that the LAA is fully
stabilized prior to the insertion of access needle (1032). The
position of looped closure assembly (1024') after it has encircled
the LAA may be adjusted by applying positive pressure to the
apertures (to release the LAA) and negative pressure (to secure the
LAA). Alternatively, a distal segment (1019) of the LAA stabilizing
device (1020') may be adapted to help looped closure assembly
(1024') to engage and encircle the LAA. For example, the distal
segment (1019) may be advanced towards the LAA. The looped closure
assembly (1024') may then engage a tip portion of the LAA, after
which negative pressure is applied to the distal-most aperture,
while the remaining apertures remain pressure-neutral. Then, the
distal segment (1019) may be advanced towards the LAA, and then the
negative pressure in the distal-most aperture is released,
immediately followed by the application of negative pressure on the
second distal-most aperture. These steps may be repeated, where
distal segment (1019) may effectively advance in a step-wise
fashion across the LAA by sequentially applying and then releasing
negative pressure on each of the apertures (starting from the
distal-most aperture and moving proximally), until the looped
closure assembly (1024') reaches the ostium of the LAA. Once the
looped closure assembly (1024') reaches the ostium of the LAA, it
may be cinched to secure the LAA, and optionally, negative pressure
may be applied on all apertures (1025) to further secure the
LAA.
[0074] Various devices may be advanced over the guide wire (1031)
to access the internal portion of LAA (1000) and left atrium
(1003). The guide wire (1031) may be navigated and controlled by
actuator (1028c). Ablation devices may be advanced over the guide
wire (1031) to ablate asynchronous tissue for the treatment of
atrial fibrillation. FIG. 10H depicts one variation of an
endocardial ablation device (1040) as it is advanced over guide
wire (1031), through the wall of the LAA and into the left atrium.
For example, the endocardial ablation device (400) as described
above and depicted in FIG. 4 may be used here. In some variations,
an endocardial ablation device may be advanced through the LAA to
access the left pulmonary veins. Optionally, an endocardial
ablation device may be advanced via an intravascular antegrade
transseptal approach to access the right pulmonary veins. As
described previously, an ablation device such as the endocardial
ablation device (1040) may utilize any tissue-affecting mechanism
to create a lesion in the target tissue. Examples of
tissue-affecting mechanisms include cryo-ablation, radiofrequency
(RF), ultrasound, microwave, laser, any suitable type of
photo-ablation using light-activated agents that may trigger
cellular apoptosis, heat, localized delivery of chemical or
biological agents, and the like. In some variations of an
endocardial ablation device, a source (1044) may be a reservoir of
one or more cryogenic, chemical, or biological agents, and/or may
be an energy source (e.g., laser light source, pulse generator,
ultrasonic source, etc.) and may be located a proximal portion of
the ablation device (1040). A conductive structure (1041) may
provide a conduit for conveying the ablation energy from the source
(1044) to the distal portion of ablation device (1040). For
instance, the conductive structure (1041) may be a wire, fiber
optic cable, lumen, channel, microfluidic channel, etc.
[0075] Ablation array (1042) of the endocardial ablation device
(1040) may be integrally formed with the proximal portion of the
ablation device (1040), or may be attached via an articulating
hinge (1043). In some variations, an ablation array may comprise
ablation elements and/or magnetic elements, as previously described
above. The endocardial ablation device (1040) may have a first
delivery configuration, where the ablation array (1042) has a
narrow profile (as shown in FIG. 10H), and a second deployed
configuration, where the ablation array (1042) assumes a wider
profile (as shown in FIG. 10I). In the delivery configuration, the
ablation array (1042) may have a substantially straight linear
geometry. In the deployed configuration, the ablation array (1042)
may be expanded to have a curved shape, such as a semi-circular
shape, to circumscribe the base of pulmonary vein (1007b). The
deployed configuration of the ablation array may have any shape
that may be configured to accommodate the anatomy of the target
tissue to achieve a desired ablation profile. For example, the
ablation array may have any of the shapes previously described and
depicted in FIGS. 6A-6F.
[0076] Once the ablation array (1042) of the endocardial ablation
device is positioned at a region of tissue in the left atrium, e.g.
around the base of pulmonary vein (1007b), an epicardial ablation
device may be aligned and placed on the epicardial surface of the
atrium (1003). A second guide cannula (1052) may be inserted in any
of the access sites previously described and depicted in FIG. 10A,
and may use the same or different access point from the first guide
cannula (1012). The guide cannula (1052) may be advanced to the
pericardial space as described previously, and once positioned and
stabilized, the guide wire (1050) may be advanced through guide
cannula (1052) to track around a target tissue region, e.g. the
tissue region directly across where the endocardial ablation array
(1042) is positioned, as shown in FIG. 10J. Guide cannula (1052)
may have one or more curves, and may vary in length, as suitable
for the access site(s) used. Guide wire (1050) may comprise a
magnetic component at its distal tip (not shown). The magnetic
component may be of any suitable type, size, and shape, for
example, the magnet may be a rare-earth, electro-activated, or a
multi-alloy (e.g. iron, boron, neodymium) magnet. A guide wire with
a magnetic distal tip may facilitate the navigation of the guide
wire to the magnetic component(s) of the positioned endocardial
ablation device. The epicardial ablation device may be navigated
over the guide wire (1050) and through the guide cannula (1052) to
the target site, e.g. at or around pulmonary vein (1017b) which is
directly across from the base (1007b). In some variations, the
epicardial ablation device (500) as described above and depicted in
FIG. 5, may be used here. As with the endocardial ablation device,
an ablation array (1062) may be attached to the distal portion of
the epicardial ablation device (1060), as shown in FIGS. 10K and
10L. In some variations, an ablation array may comprise ablation
elements and/or magnetic elements, as previously described with
respect to ablation array (508). Similar to the endocardial
ablation device (1040), the epicardial ablation device (1060) may
have a delivery configuration that has a substantially narrow
profile, as seen in FIG. 10K, and a second deployed configuration,
where ablation array (1062) assumes a wider profile, as seen in
FIG. 10L. In the delivery configuration, the ablation array (1062)
may have a substantially straight linear geometry. In the deployed
configuration, the ablation array (1062) may have a curved shape,
such as a semi-circular shape to circumscribe the trunk of the
pulmonary vein (1017b), however, may be any shape to accommodate
the anatomy of the target tissue to achieve a desired ablation
profile. In the variation of method described here, the tissue
around the pulmonary veins may be ablated both epicardially and
endocardially. According to this variation, the shape of the
deployed configuration of the epicardial ablation device
corresponds with the shape of the deployed configuration of the
endocardial ablation device, e.g., mirror-symmetric. Once the
epicardial ablation device has assumed its deployed configuration,
the guide wire (1050) may be withdrawn.
[0077] Endocardial and epicardial ablation devices may comprise
alignment features, which may help ensure a particular orientation
of one ablation device with respect to another, and may also create
an intimate contact between the ablation devices and the tissue to
be ablated. In the variation of the ablation devices described
here, the attractive forces between the magnets on one or both of
the epicardial and endocardial ablation devices may align the
devices to one another. FIGS. 10M and 10N show enlarged
cross-sectional views of the endocardial ablation array (1042) and
the epicardial ablation array (1062) positioned across each other,
where the endocardial ablation array may circumscribe the base of a
pulmonary vein within the cavity of the left atrium, and the
epicardial ablation array may circumscribe the trunk of the same
pulmonary vein on the outer surface of the left atrium. As shown in
FIG. 10M, the epicardial ablation device may be advanced such that
the epicardial ablation array (1062) is positioned approximately
opposite the endocardial ablation array (1042), i.e. around the
pulmonary vein (1017b) of the left atrium (1003), such as a left
pulmonary vein. Endocardial magnetic components (1045) and
epicardial magnetic components (1065) may attract each other,
drawing the ablation arrays towards each other to form a stable
contact with the wall of the left atrium, as shown in FIG. 10N. The
magnetic attraction between the ablation arrays may compress the
wall of the left atrium against the ablation arrays, which may
improve the efficacy of lesion formation in the atrial wall, which
may reduce the magnitude of the energy (or the quantity of fluid)
needed to ablate the tissue between the ablation arrays. In some
cases, arranging the ablation arrays on both sides of the atrial
wall may help form a transmural lesion that spans the entire
thickness of the wall between the arrays.
[0078] While the devices and methods above are directed towards
ablating tissue endocardially and epicardially to form an ablation
pattern that circumscribes the base of a pulmonary vein, other
ablation patterns and profiles may be also be used for the
treatment of atrial fibrillation. Examples of other ablation
patterns are schematically illustrated in FIGS. 10O-10P. A cutaway
of left atrium (1003) and LAA (1000) reveals the four pulmonary
veins (1007a), (1007b), (1007c), and (1007d). FIG. 10O depicts one
variation of an ablation pattern (1070) where each of the pulmonary
veins are individually circumscribed. FIG. 10P depicts another
ablation pattern (1071) where pairs of pulmonary veins are
circumscribed, i.e., (1007a) and (1007c) are circumscribed by one
lesion, and (1007b) and (1007d) are circumscribed by another
lesion. Different pairs of pulmonary veins may be circumscribed
together, depending on the profile of electrical isolation that is
needed. The shape (e.g., number of curves, radii of curves, etc.)
of the endocardial and epicardial ablation arrays may be adjusted
such that ablation pattern (1071) may be obtained. For example, the
endocardial and epicardial ablation arrays may have an elongated
elliptical shape (e.g., where the length is substantially greater
than the width) to attain the ablation pattern of FIG. 10P. FIG.
10Q depicts yet another ablation pattern (1072) where all pulmonary
veins are circumscribed by a single lesion. In this variation, the
endocardial and epicardial ablation arrays may be sized and shaped
to circumscribe all of the pulmonary veins. In addition to the
lesion patterns described in FIGS. 10O-10Q for pulmonary vein
isolation, the endocardial and/or epicardial ablation arrays may be
used to create linear lesions through tissue of the left atrium
(LA) including: the LA roof line (e.g., along the connection
between the right superior pulmonary vein (1007b) and the left
superior pulmonary vein (1007a)), the mitral valve isthmis line
(e.g., along the connection between left inferior pulmonary vein
(1007c) to the mitral valve annulus (1009)), and the posterior LA
line (e.g., along the connection between both sets of pulmonary
veins across the posterior LA). Other ablation patterns and lesion
geometries may be used to obtain a desired degree and profile of
electrical isolation. While these ablation patterns have been
described in the context of simultaneous ablation of tissue from
both the endocardial and epicardial surfaces, it should be
understood that these ablation patterns may also be attained by
ablating either the endocardial surface or the epicardial surface.
In general, any appropriate ablation profile may be achieved for
any target tissue by adjusting the size and shape of the ablation
arrays on the ablation devices. For example, to ablate a larger
volume and/or area of tissue, a smaller ablation array (e.g. an
array that ablates a volume of tissue smaller than the desired
ablation pattern) may apply the ablation energy multiple times at
different tissue regions. Alternatively, a larger volume and/or
area of tissue may be ablated by an ablation array that is
comparably sized with the desired ablation volume/area, and may be
shaped according to the target tissue. In this variation, the
ablation energy may only need to be applied once. While the
ablation regions around the pulmonary veins have been described,
additional ablation targets for the treatment of atrial
fibrillation may include other anatomical regions. For example,
other tissue regions that may be suitable non-pulmonary vein
ablation targets may include the superior vena cava (SVC), LA
posterior wall, crista terminalis, coronary sinus (CS), ligament of
Marshall, intrarterial septum, and/or any other tissue regions that
may trigger atrial fibrillation.
[0079] During and/or after tissue ablation, the progress of the
ablation and the lesion size may be monitored and verified. Lesion
formation may be monitored functionally and/or anatomically. For
example, lesion formation may be monitored by heat transfer
measurements, electrocardiography mapping, ejection fraction, local
electrogram amplitude reduction and mapping, impedance tomography,
ultrasound, fluoroscopy, and other suitable functional metrics or
imaging modalities. Based on these measurements and images, the
rate, size, and other characteristics of lesion formation may be
modified, e.g., by adjusting power and wavelength of the ablation
energy, to achieve the desired degree of electrical isolation. In
some variations, lesion formation may be measured in terms of the
change in the tissue temperature across the thickness of the
tissue. For example, endocardial and epicardial ablation arrays may
each comprise temperature sensors as previously described may be
pressed into the atrial wall tissue to measure the temperature on
either side of the atrial wall. In some variations, either the
endocardial or the epicardial ablation array has a temperature
probe, so that the heat transfer front from the other ablation
array may be measured. The temperature probe may also be a separate
device that is advanced to the desire target tissue region.
[0080] Once the desired portion of tissue has been ablated (e.g.,
verified that a lesion of a desired size and shape has been
formed), the ablation devices and positioning catheters may be
removed. The alignment feature that couples the endocardial
ablation array (1042) with the epicardial ablation array (1062) may
be deactivated, either mechanically (e.g., by applying a force
stronger than, and opposite to, the coupling force) or electrically
(e.g., by turning off the electro-magnet). The endocardial ablation
device (1040) and the epicardial ablation device (1060) may be
removed sequentially or simultaneously, as may be appropriate. The
endocardial guide wire (1031) may be kept in place to facilitate
the navigation of any additional devices to the left atrium and/or
LAA, however, in other variations, the guide wire (1031) may be
removed.
[0081] Optionally, a method for the electrical isolation of tissue
in the LAA and/or left atrium may comprise a step that electrically
isolates the LAA. FIG. 10R depicts an occlusion device (1080) that
may be advanced over the guide wire (1031) via a guide wire port
(1082) and through a working channel of the LAA stabilizing device
(1020) to access the internal portion of the LAA (1000). For
example, the occlusion device (700) as described previously and
depicted in FIG. 7 may be used here. In some variations, an
occlusion device may be configured to deliver contrast and/or
therapeutic agents through the guide wire port or an infusion lumen
that may extend along the occlusion device from the proximal
portion to distal portion. The looped closure assembly (1024) may
remain in a closed configuration to stabilize and localize the LAA.
The distal portion of the occlusion device (1080) may comprise an
expandable member (1086) which may have a collapsed delivery
configuration (shown in FIG. 10R) and an expanded deployed
configuration (shown in FIG. 10S). Optionally, the distal portion
of the occlusion device (1080) may also comprise radioopaque and/or
echogenic markers (1085) so that the position of the occlusion
device may be detected by imaging. Some variations of an occlusion
device may comprise side apertures that provide for the infusion of
a contrast agent to enhance visualization of the occlusion device,
or the infusion of other agents, including therapeutic agents such
as heparin or other anticoagulants, saline, etc. The expandable
member (1086) may be expanded by introducing a fluid, e.g. liquid
or gas, via a fluid lumen (1084), from a pressurized fluid
reservoir (1083). Alternatively or additionally, in other
variations of an occlusion device, the expandable member may be
mechanically dilated, e.g., by actuating struts. During or after
the expansion of the expandable member (1086), the looped closure
assembly (1024) may be further tightened around the LAA by
actuating tab (1028d). Tightening the looped closure assembly
(1024) around the neck of LAA (1000) may block the exchange of any
substances between the LAA cavity and the left atrial cavity. In
some variations, tightening the looped closure assembly may sever
the LAA entirely, such that it is excluded from the left atrium.
For example, a releasable suture loop and a snare loop of the
looped closure assembly may be tightened to exclude the LAA, and
the snare loop may be proximally withdrawn from the suture loop,
e.g., after the suture loop is released from the looped closure
assembly by further pulling on tab (1028d). The LAA may be
extracted from the body by any suitable method, for example, by
using negative pressure to secure the LAA into a collector or
tubular member, which is then retracted out of the body.
Optionally, a debrider may be used to break the excised LAA into
smaller portions prior to extraction, which may be suitable for use
with a minimally invasive procedure. In some variations, a chemical
or enzyme agent may used prior to extraction to break down or
soften the LAA for removal.
[0082] As described above, the neck of LAA may be encircled and
cinched by a suture snare, however, other mechanisms may be
included to close and/or occlude the LAA cavity. As shown in FIGS.
11A-11C, a clip (1100) may be used to close the LAA. Clip (1100)
may be advanced through a guide cannula and encircled around a LAA
or LAA neck. Subsequently, a mandrel (1104) may be advanced through
the guide cannula in the direction of arrow (1006) to urge a collet
(1102) onto a clip neck (1103), as shown in FIG. 11A. FIG. 11B
depicts that the collet (1102) may continue to be urged in the
direction of arrow (1108), until it is completely secured onto the
clip (1100), and the LAA enclosed by the clip is tightened. The
collet (1102) may be engaged onto the clip (1100) by snap-fit,
press-fit, or friction-fit. In some variations, alternate closure
mechanisms may be used, such as a cable tie with a ratchet
mechanism, a Nitinol cable or loop, and the like. The clip (1100)
may be made of shape memory material, such as a nickel titanium
alloy, where in the unconstrained configuration, the neck (1103)
naturally springs open, and the spring force engages and secures
collet (1102). After the collet has secured and closed the clip,
the mandrel (1104) may be removed.
[0083] A variety of expandable members may be used to occlude
and/or exclude the LAA. For example, an inflatable expandable
member, such as a balloon similar to the expandable member (1086),
may be used to occupy the LAA cavity, preventing the escape of, or
continuing development of, thrombi in the LAA. In another variation
shown in FIG. 12A, expandable member (1200) in LAA (1000) may be
filled with a hardening material (1202), such as thermal polymers,
hydrogels, epoxy, and any suitable hardening materials. The
hardening material may initially be a liquid or gel that may be
delivered through a lumen (1204) in the occlusion device, and may
solidify after being deposited in the expandable member (1200)
within the LAA (1000). Alternatively or additionally, an expandable
member may be self-expanding, as depicted in FIG. 12B. As shown
there, an expandable element (1210) may be an ostial occluder that
automatically expands once urged by mandrel (1212) into the LAA
cavity. The expandable member may be made of one or more polymeric
materials, for instance, polypropylene, polyurethane, polyethylene,
polytetrafluoroethylene, and in some variations, may alternatively
or additionally include one or more metal alloys such as nitinol,
stainless steel, etc., or any shape-memory material. A
self-expanding expandable member may be an enclosed structure, such
as a balloon, or a mesh-like structure. Mechanisms of
self-expansion include shape-memory, thermal expansion,
spring-action, and the like.
Endocardial Ablation
[0084] While some methods for the treatment of atrial fibrillation
may ablate tissue in the left atrium both endocardially and
epicardially, other variations of ablating tissue in the left
atrium, and subsequently occluding and/or excising the LAA may be
used. One example of a method that ablates an endocardial surface
of a left atrium is shown in FIG. 13A. Method (1300) may be used to
ablate tissue from an endocardial surface using surgical,
intravascular and/or other minimally invasive techniques (e.g.,
percutaneous, small incisions or ports), and may be used in stopped
heart or beating heart procedures. The method (1300) may comprise
accessing the pericardial space (1302). Optionally, a device may be
used to locate and stabilize the LAA (1304), for example, the
closure device (200) as described above and shown in FIG. 2. Once
access into the pericardial space and to the LAA has been
established, a device may enter the LAA (1306) by creating a
puncture in the LAA. Access to various tissue regions in the left
atrium (e.g., atrial wall tissue, tissue at or around the base of
the pulmonary veins, tissue within the pulmonary veins, etc.) from
an endocardial side may be established (1310). An endocardial
ablation array may be positioned and placed along an endocardial
surface of the left atrium (1312). For example, the endocardial
ablation array may circumscribe the pulmonary veins to obtain a
particular ablation pattern. The endocardial ablation array may
then be activated (1314). After the desired tissue has been ablated
(e.g., atrial wall tissue, tissue at or around the base of the
pulmonary veins, tissue within the pulmonary veins, etc.), the
ablation devices may be removed (1316), and the LAA may be
occluded, closed, and/or removed (1318). Once the LAA has been
decoupled from the remainder of the left atrium, all devices may be
retracted from the surgical site (1320). In some variations of
methods for ablating tissue in the left atrium, the endocardial
ablation device may be advanced intravascularly (e.g., from a
retrograde approach, or an antegrade transseptal approach, etc.).
Access to the left atrium may be accessed by any method or approach
as may be suitable for contacting the targeted tissue region.
[0085] While the method described above uses one endocardial
ablation array for ablating the tissue of the left atrium from an
endocardial side, other methods may use two endocardial ablation
arrays. One example of a method that uses two endocardial ablation
arrays for ablating atrial tissue on an endocardial side is
depicted in FIG. 13B. As previously described, an access pathway is
created to the pericardial space (1332). A LAA access/exclusion
device may be used to locate and stabilize the LAA (1334). Once
access into the pericardial space and to the LAA has been
established, a device may be used to create a puncture in the LAA
(1336), which may allow a device to access the left atrium through
the LAA. An intravascular pathway to the left atrium may also be
attained by advancing a delivery catheter through the vasculature
into the left atrium (1338), e.g., using a retrograde or an
antegrade transseptal approach. Once the intravascular and/or LAA
access pathways into the left atrium have been established, a first
endocardial ablation array may be advanced into the left atrium
through the LAA (1340). The first endocardial ablation array may be
positioned at any desired tissue region (e.g., atrial wall tissue,
tissue at or around the base of the pulmonary veins, tissue within
the pulmonary veins, etc.), such as along tissue at or around the
bases of the right pulmonary veins (1342). The first endocardial
ablation array may be activated to ablate tissue (1344). A second
endocardial ablation array may be advanced intravascularly through
the delivery catheter into the left atrium (1346). The second
endocardial ablation array may be positioned along tissue at or
around the bases of the left pulmonary veins (1348). The second
endocardial ablation array may be activated to ablate tissue
(1350). The positioning and activation of the first and second
endocardial ablation arrays may be repeated as desired. After
ablating the desired tissue regions, the ablation arrays may be
removed (1352). The LAA may be closed with the access/exclusion
device (1354), and then the access/exclusion device may be removed
(1356).
[0086] While the steps of the method (1330) have been described in
the sequence as depicted in FIG. 13B, it should be understood that
the steps may take place in an alternate sequence, and certain
steps may take place substantially simultaneously. For example, the
delivery catheter may be advanced intravascularly into the left
atrium (1338) before or after the LAA access site is created
(1336). In some variations, the second ablation array may be
advanced through the delivery catheter into the left atrium (1346)
before the first endocardial ablation array is advanced through the
LAA into the left atrium. The activation of the ablation arrays may
occur sequentially or simultaneously. For example, the first or
second endocardial ablation array may be activated simultaneously
or sequentially.
[0087] Examples of ablation patterns that may be formed by
endocardial ablation method (1300) are shown in FIGS. 14A and 14B.
Ablation array (1402) is positioned against atrial wall (1400) on
the endocardial side (1404). The ablation energy (1403) may be any
mechanism of tissue ablation, as described previously. As depicted
in FIG. 14B, the portion of the atrial wall (1405) that is closest
to ablation array may be ablated relatively quickly, while the
portion of the atrial wall further from the ablation array, e.g.
tissue near the epicardial side (1406), may not be ablated. To
ablate tissue furthest from the ablation array (1402), a longer
exposure to a greater quantity of ablation energy (1403) may be
needed. For example, to ablate tissue closest to the epicardial
side (1406), radiofrequency or cryogenic delivery may need to be
increased, and laser energy and heat may need to be more intense.
Additionally or alternatively, the ablation of tissue further from
the ablation array (1402) may involve increasing the exposure time
of tissue (1400) to the ablation energy (1403). The ablation depth
achieved an ablation array may be regulated by adjusting more of
the above-described factors, as may be desirable. For example, the
depth of tissue that is ablated may be 5%, 10%, 25%, 40%, 50%, 60%,
75%, 80%, 95%, etc. of the thickness of the tissue wall. In some
variations, closed system or open system irrigation may be included
during the delivery of the energy source to regulate the ablation
of tissue adjacent to the ablation array. As described previously a
temperature probe may be used to measure temperature changes that
may arise from tissue ablation, which may help to regulate the
amount of ablation applied to a tissue region.
Epicardial Ablation
[0088] Ablation of tissue of the LAA and left atrium may be
achieved by epicardial ablation. An example of a method (1500) for
epicardial ablation is shown in FIG. 15. Method (1500) may be used
to ablate tissue using surgical techniques or intravascular
techniques, and may be used in stopped heart or beating heart
procedures. As previously described, an access pathway may be
created to the pericardial space (1532). An epicardial ablation
array may be advanced via the pericardial space to the outer
surface of the heart (1534). The epicardial ablation array may be
positioned along tissue at or near the trunk of the pulmonary veins
(1536). The epicardial ablation array may be activated to ablate
tissue (1538). Optionally, the epicardial ablation array may be
positioned and activated at different locations on the outer
surface of the heart, as may be desirable. After ablating the
desired tissue regions, the ablation arrays may be removed (1540).
Optionally, a LAA access/exclusion device may be advanced to the
LAA via the pericardial space (1542). The access/exclusion device
may be used to locate and stabilize the LAA (1544). The LAA may be
occluded or excised by the access/exclusion device (1546), and then
the access/exclusion device may be removed (1548). Decoupling the
LAA from the remainder of the left atrium may help reduce the risk
of thrombosis or stroke that may occur in atrial fibrillation.
[0089] FIGS. 19A-19F depict another variation of an access device
and method that may be used to position a device on an epicardial
surface of the heart, e.g., around a tissue structure such as a
blood vessel or the LAA. Access device (1900) or a similar device
may be used to place a guide element (1902) or other device around
a tissue structure (1904), such as a blood vessel or the left
atrial appendage. As shown there, access device (1900) may comprise
a cannula (1906), a first guide (1908), and a second guide (1910).
First (1908) and second (1910) guides each may comprise a lumen
(1912) extending therethrough, and may further comprise a magnetic
alignment element (1914) at a distal end thereof. First (1908) and
second (1910) guides may be at least partially housed inside
cannula (1906), and may be configured to be advanced out of a
distal end of the cannula (1906). In some variations, first (1908)
and second (1910) guides may be housed in a single lumen (not
shown) of cannula (1906). In other variations, first (1908) and
second (1910) guides may be housed in separate lumens (e.g., a
first lumen and a second lumen, respectively). It should be
appreciated that cannula (1906) may comprise any suitable number of
lumens (e.g., one, two, or three or more).
[0090] Returning to the figures, cannula (1906) may be advanced to
tissue structure (1904), as shown in FIG. 19A. In some variations,
the tissue structure (1904) may be the right atrial appendage.
Cannula (1906) may be advanced in any suitable manner. In some
variations, cannula (1906) may be advanced over a guidewire (e.g.,
via one or more lumens of the cannula (1906). Additionally or
alternatively, one or more portions of the cannula (1906) may be
steerable. While shown in FIGS. 19A-19F as being a blood vessel
(1905), tissue structure (1904) may be any suitable anatomical
structure. In some variations, tissue structure (1904) may be the
left atrial appendage.
[0091] Once cannula (1906) is positioned at or near the tissue
structure (1904), first guide (1908) may be advanced out of the
distal end of cannula (1906), as shown in FIG. 19B. As first guide
(1908) is advanced out of the distal end of cannula (1906), it may
take on a curved configuration. In some variations, the first guide
(1908) has a pre-shaped curved configuration, which may be
constrained when it is housed within cannula (1906). In other
variations, the first guide (1908) may be steered or otherwise
actuated to take on the curved configuration. The first guide
(1908) may be advanced such that a distal portion of the guide
(1908) curves at least partially around the tissue structure
(1904), as depicted in FIG. 19B.
[0092] The second guide (1910) may then be advanced from the distal
end of cannula (1906), as depicted in FIG. 19C. As shown there, the
second guide (1910) may be advanced toward and may engage the first
guide (1908). For example, in variations where the first (1908) and
second (1910) guides each comprise a magnetic alignment element
(1914), the magnetic alignment elements (1914) of the first (1908)
and second (1910) guides may attract each other and hold the distal
ends of the two guides in place relative to each other. In some
variations, the distal ends of first (1908) and second (1910)
guides may be positioned such that the lumens (1912) of the two
guides are aligned. In some of these variations, the magnetic
alignment elements (1914) of each of the first (1908) and second
(1910) guides may hold the lumens (1912) of the two guides in
alignment.
[0093] Once the lumens (1912) of the first (1908) and second (1910)
guides are aligned, a guide element (1902) may be advanced through
the lumen (1910) of first guide (1908) such that it exits the
distal end of first guide (1908) and enters the lumen of the second
guide (1910) (or vice versa). The guide element (1902) may then be
advanced through the second guide (1910) (or the first guide
(1908)) and the first (1908) and second (1910) guides may be
withdrawn through the cannula, as shown in FIG. 19D. In some
instances, both ends (not shown) of the guide element (1902) may
extend out from a proximal end of the cannula and/or may extend
outside of the body. In these variations, guide element (1902) may
be a wire, a suture, yarn, strand, or the like. While FIGS. 19A-19D
depict advancing a guide element (1902) through lumens (1912) of
the first (1908) and second (1910) guides, it should be appreciated
that in some variations, a tube or catheter may be advanced over
the first (1908) and second (1910) guides to place the tube or
catheter around the tissue structure (1904).
[0094] In some variations, the ends of the guide element (1902) may
be pulled proximally to cinch the distal exposed portion of guide
element (1902) (e.g., the portion of guide element extending from
the distal end of cannula (1906)) around the tissue structure
(1904), as shown in FIG. 19E. In variations where tissue structure
(1904) is the left atrial appendage (not shown), cinching guide
element (1902) around the left atrial appendage may act to close
the left atrial appendage (temporarily or permanently). In
variations where the left atrial appendage is used as an access
port into the interior of the heart, as described hereinthroughout,
guide element (1902) may be used to help provide hemostasis by
temporarily closing the left atrial appendage around one or more
devices placed through tissue of the left atrial appendage.
Additionally or alternatively, in some variations, a knot, clip, or
clamping structure (not shown) may be advanced over a portion of
the guide element (1902) to hold the guide element in place around
the tissue structure (1904). In variations where the guide element
(1902) is placed around the left atrial appendage, the guide
element (1902) may be used to close the left atrial appendage (as
described immediately above). For example, a knot, clip, or
clamping structure may be advanced over the guide element (1902) to
hold it in place such that the left atrial appendage is held in a
closed configuration. In some variations, the guide element may
comprise a releasable suture loop, where cinching the guide element
around the tissue structure (1904) likewise cinches the suture loop
around the tissue structure (1905). Once the desired level of
tightening is achieved, the suture loop may be released from the
guide element, and the guide element may be retracted proximally.
To secure the tension in the suture loop, a knot, clip or other
clamping structure may be advanced through the cannula to lock the
suture loop. In some variations, a suture-cutter or the like may be
advanced over a portion the guide element (1902) or suture loop to
sever at least a portion of the guide element (1902) or suture loop
(e.g., the portions of guide element located proximal to the knot,
clip, or clamping structure.)
[0095] Additionally or alternatively, one or more devices may be
advanced over the guide element (1902) to place the device at or
around the tissue structure (1904). In some variations, one or more
ablation devices may be advanced over the guide element, such as
ablation device (1918) shown in FIG. 19F. As shown there, ablation
device (1918) may comprise one or more ablation elements (1920) and
one or more magnetic elements (1922), and may be any of the
ablation devices previously described. Additionally or
alternatively, access device (1900) may also be used to place
measurement electrodes, temperature sensors, and the like at or
around the pulmonary veins, the LAA, and/or any tissue structure on
the epicardial surface of the heart. The devices and methods
depicted in FIGS. 19A-19F may be used in combination with any of
the devices and methods previously described (e.g., in combination
with the methods depicted in FIGS. 8A and 8B, FIG. 15, etc.).
[0096] Examples of ablation patterns that may be formed by
epicardial ablation method (1500) are shown in FIGS. 16A and 16B.
Ablation array (1602) is positioned against an atrial wall (1600)
on the epicardial side (1604). The ablation energy (1603) may be
any mechanism of tissue ablation, as described above. The portion
of atrial wall tissue (1600) that is closest to ablation array
(1602) may be ablated relatively quickly, while tissue further from
the ablation array, e.g. tissue near the endocardial side (1606),
may not be ablated. To ablate a targeted tissue furthest from
ablation array (1602), such as targeted tissue (1607) depicted in
FIG. 16B, a longer exposure to a greater quantity of ablation
energy (1603) may be needed. For example, to ablate tissue closest
to the endocardial side (1606), ultrasound and radio frequencies
may need to be increased, and laser energy and heat may need to be
more intense. Additionally or alternatively, the ablation of tissue
further from ablation array (1602) may involve increasing the
exposure time of atrial wall (1600) to the ablation energy (1603).
Depending on the type of ablation energy (1603) and/or the quality
of the tissue (e.g., thermal energy conductivity, etc.), greater
quantities of ablation energy may successfully ablate the targeted
tissue (1607) without burning, charring, and/or coagulation of the
tissue closest to the ablation array. For example, ultrasound
ablation may be shaped and focused such that more energy is
delivered to the targeted tissue (1607) than to the tissue on the
epicardial side (1604). In some variations, closed system or open
system irrigation may be included during the delivery of the energy
source to limit the heating of tissue adjacent to the ablation
array, while delivering larger quantities of energy to tissue
further away from the ablation array. As described previously a
temperature probe may be used to measure temperature changes that
may arise from tissue ablation, which may help to regulate the
amount of ablation applied to a tissue region.
IV. Systems
[0097] Also described herein are systems for affecting tissue
within a body to form a lesion. In general, the systems may
comprise devices that have one or more tissue-affecting elements,
together with additional components that help to locate and secure
the target tissue. For example, the system may comprise a first and
second device, where each of the devices comprises an elongate
member and one or more tissue-affecting elements. The first and
second devices may be separate from each other, but have
corresponding geometries and sizes so that operating the
tissue-affecting elements may form a lesion in the tissue between
them. These devices may have any geometry (e.g., size, number of
curves, radii of curvature, etc.), one or more configurations
(e.g., a delivery configuration and a deployed configuration) and
may apply a variety of tissue-affecting mechanisms (e.g., cryogenic
substances, lasers, high intensity focused ultrasound,
radiofrequency energy, heat, microwave, etc.). The tissue-affecting
elements for a given device may deliver a combination of one or
more types of tissue-affecting mechanisms. The tissue-affecting
elements may be any of the ablation elements previously described.
Some devices may also comprise magnetic components so that the
attractive force between the magnets may cause the first and second
devices to be positioned in a certain orientation with respect to
each other, e.g. opposite one another. Systems may also include
actuators and controllers that regulate the application of the
tissue-affecting mechanisms. For example, tissue-affecting elements
may be configured to be operated simultaneously, and/or apply
energy to the tissue in a pre-programmed manner. A controller may
be coupled to the tissue-affecting elements to synchronize their
operation temporally (e.g., to affect tissue in-phase or
out-of-phase, synchronously or asynchronously) and spatially (e.g.,
to affect one region of tissue without affecting another, to affect
one region of tissue from more than one surface, etc.). In some
variations, a controller may be configured to receive temperature
data measured at the target tissue site to regulate the operation
of the tissue-affecting elements.
[0098] Some systems for affecting tissue within a body may include
devices that aid in accessing and securing the tissue, as well as
positioning the tissue-affecting elements with respect to the
tissue. For example, some systems may comprise a closure device
(such as described above) may be included to locate and secure
target tissue, a piercing member, one or more guide cannulas, and
one or more guide wires. These devices may be configured to be
inserted through, or advanced over, each other, which may be
desirable for minimally invasive procedures.
[0099] Although the foregoing invention has, for the purposes of
clarity and understanding been described in some detail by way of
illustration and example, it will be apparent that certain changes
and modifications may be practiced, and are intended to fall within
the scope of the appended claims.
* * * * *