U.S. patent application number 14/043650 was filed with the patent office on 2014-08-07 for cardiac ablation devices and methods.
The applicant listed for this patent is Endoscopic Technologies, Inc.. Invention is credited to Arthur A. Bertolero, Tamer Ibrahim.
Application Number | 20140221993 14/043650 |
Document ID | / |
Family ID | 46304869 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140221993 |
Kind Code |
A1 |
Bertolero; Arthur A. ; et
al. |
August 7, 2014 |
CARDIAC ABLATION DEVICES AND METHODS
Abstract
Devices and methods provide for ablation of cardiac tissue for
treating cardiac arrhythmias such as atrial fibrillation. Although
the devices and methods are often used to ablate epicardial tissue
in the vicinity of at least one pulmonary vein, various embodiments
may be used to ablate other cardiac tissues in other locations on a
heart. Devices generally include at least one tissue contacting
member for contacting epicardial tissue and securing the ablation
device to the epicardial tissue, and at least one ablation member
for ablating the tissue. Various embodiments include features, such
as suction apertures, which enable the device to attach to the
epicardial surface with sufficient strength to allow the tissue to
be stabilized via the device. For example, some embodiments may be
used to stabilize a beating heart to enable a beating heart
ablation procedure. Many of the devices may be introduced into a
patient via minimally invasive introducer devices and the like.
Although devices and methods of the invention may be used to ablate
epicardial tissue to treat atrial fibrillation, they may also be
used in veterinary or research contexts, to treat various heart
conditions other than atrial fibrillation and/or to ablate cardiac
tissue other than the epicardium.
Inventors: |
Bertolero; Arthur A.;
(Danville, CA) ; Ibrahim; Tamer; (Pleasant Hill,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Endoscopic Technologies, Inc. |
San Ramon |
CA |
US |
|
|
Family ID: |
46304869 |
Appl. No.: |
14/043650 |
Filed: |
October 1, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12564821 |
Sep 22, 2009 |
8545498 |
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14043650 |
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11186148 |
Jul 20, 2005 |
7591818 |
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12564821 |
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10988021 |
Nov 12, 2004 |
7399300 |
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11186148 |
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10410618 |
Apr 8, 2003 |
7226448 |
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10988021 |
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10272446 |
Oct 15, 2002 |
6849075 |
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10410618 |
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60337070 |
Dec 4, 2001 |
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60519726 |
Nov 12, 2003 |
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Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 18/1402 20130101;
A61B 2018/00363 20130101; A61B 2017/00243 20130101; A61B 18/20
20130101; A61B 1/12 20130101; A61B 2018/0022 20130101; A61B 18/148
20130101; A61N 1/0587 20130101; A61B 2018/00404 20130101; A61B
2018/00011 20130101; A61B 18/1442 20130101; A61B 2018/00023
20130101; A61B 18/1477 20130101; A61B 18/18 20130101; A61B 2018/126
20130101; A61B 2017/22051 20130101; A61B 2018/00345 20130101; A61B
2018/00351 20130101; A61B 2090/378 20160201; A61B 5/0536 20130101;
A61B 2018/1425 20130101; A61B 2018/00375 20130101; A61B 2018/00875
20130101; A61B 2018/00577 20130101; A61B 2017/2945 20130101; A61B
2018/0225 20130101; A61B 18/00 20130101; A61B 2018/0262 20130101;
A61B 2018/1432 20130101; A61B 2018/00982 20130101; A61B 18/14
20130101; A61B 2090/373 20160201; A61B 2018/00029 20130101; A61B
2018/00291 20130101; A61B 2018/00083 20130101; A61B 18/1492
20130101 |
Class at
Publication: |
606/41 |
International
Class: |
A61B 18/00 20060101
A61B018/00 |
Claims
1. Apparatus for ablating heart tissue comprising: a tubular
introducer cannula having an internal lumen; a first elongate jaw
and a second elongate jaw, the first and second elongate jaws being
sized and configured for insertion through the internal lumen of
the introducer cannula in a side-by-side configuration; a first
ablation electrode located on an inner surface of the first
elongate jaw near a distal end of the first elongate jaw and a
second ablation electrode located on an inner surface of the second
elongate jaw near a distal end of the second elongate jaw; and a
first connection wire extending from the first ablation electrode
to a proximal end of the first elongate jaw and a second connection
wire extending from the second ablation electrode to a proximal end
of the second elongate jaw; wherein the first elongate jaw and the
second elongate jaw are configured such that, when inserted through
the internal lumen of the tubular introducer cannula in a
side-by-side configuration, the first inner surface and second
inner surface separate from one another as the distal ends of the
first elongate jaw and the second elongate jaw extend beyond a
distal end of the tubular introducer cannula, allowing the first
ablation electrode and the second ablation electrode to be placed
on opposing sides of a portion of heart tissue to be ablated, and,
when the first elongate jaw and the second elongate jaw are
withdrawn partially into the internal lumen of the tubular
introducer cannula, the first inner surface and second inner
surface are urged toward one another, pressing the first ablation
electrode and the second ablation electrode against the portion of
heart tissue to be ablated.
2. The apparatus of claim 1, wherein the first ablation electrode
and the second ablation electrode are configured with a plurality
of electrode segments.
3. The apparatus of claim 1, wherein the first ablation electrode
and the second ablation electrode are configured with a plurality
of individually addressable electrode segments.
4. The apparatus of claim 1, wherein the first elongate jaw and the
second elongate jaw are configured to urge the first ablation
electrode and the second ablation electrode toward one another in
parallel alignment.
5. The apparatus of claim 1, wherein the first elongate jaw and the
second elongate jaw are configured such that the distal ends of the
first elongate jaw and the second elongate jaw close around the
tissue first to prevent the tissue from being squeezed out from
between the first ablation electrode and the second ablation
electrode.
6. The apparatus of claim 1, wherein the first elongate jaw and the
second elongate jaw each include a malleable portion.
7. The apparatus of claim 1, further comprising a first guidewire
lumen extending from the proximal end to the distal end of the
first elongate jaw and a second guidewire lumen extending from the
proximal end to the distal end of the second elongate jaw.
8. The apparatus of claim 7, further comprising a guidewire sized
and configured to enter through the first guidewire lumen of the
first elongate jaw and exit through the second guidewire lumen of
the second elongate jaw.
9. A method of optimizing parameters of an ablation apparatus
including: performing an ablation procedure on a model of heart
tissue; recording a thermal image of the results of the ablation
procedure on the model of heart tissue; adjusting the parameters
ablation apparatus based on the thermal image recorded.
10. The method of claim 9, wherein the method steps are repeated
until the parameters ablation apparatus have been satisfactorily
optimized.
11. The method of claim 9, wherein the model of heart tissue
comprises an artificial heat sink model of a human heart.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. Pat. No.
8,545,498 filed Sep. 22, 2009, which is a continuation of U.S. Pat.
No. 7,591,818 filed Jul. 20, 2005, which is a continuation-in-part
of U.S. patent application Ser. No. 10/988,021, now U.S. Pat. No.
7,399,300, which was filed on Nov. 12, 2004, which is a
continuation-in-part application which claims priority of U.S.
patent application Ser. No. 10/410,618, now U.S. Pat. No.
7,226,448, which was filed on May 27, 2004, which is a
continuation-in-part of and claims priority of U.S. patent
application Ser. No. 10/272,446, no U.S. Pat. No. 6,849,075, which
was filed Oct. 15, 2002, which claims priority to U.S. Provisional
Patent Application Ser. No. 60/337,070, filed Dec. 4, 2001,
entitled "Methods and Devices for the Least Invasive Cardiac
Surgery of Atrial Fibrillation." U.S. patent application Ser. No.
10/988,021 also claims the priority to U.S. Provisional Patent
Application Ser. No. 60/519,726, filed Nov. 12, 2003, entitled
"Ablation Device." The entire contents of these applications are
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to medical devices
and methods. More specifically, the invention relates to devices
and methods for ablating epicardial tissue to treat cardiac
arrhythmias such as atrial fibrillation.
[0003] Atrial fibrillation (AF) is a heart beat rhythm disorder (or
"cardiac arrhythmia") in which the upper chambers of the heart
known as the atria quiver rapidly instead of beating in a steady
rhythm. This rapid quivering reduces the heart's ability to
properly function as a pump. AF is characterized by circular waves
of electrical impulses that travel across the atria in a continuous
cycle. It is the most common clinical heart arrhythmia, affecting
more than two million people in the United States and some six
million people worldwide.
[0004] Atrial fibrillation typically increases the risk of
acquiring a number of potentially deadly complications, including
thrombo-embolic stroke, dilated cardiomyopathy and congestive heart
failure. Quality of life is also impaired by common AF symptoms
such as palpitations, chest pain, dyspnea, fatigue and dizziness.
People with AF have, on average, a five-fold increase in morbidity
and a two-fold increase in mortality compared to people with normal
sinus rhythm. One of every six strokes in the U.S. (some 120,000
per year) occurs in patients with AF, and the condition is
responsible for one-third of all hospitalizations related to
cardiac rhythm disturbances (over 360,000 per year), resulting in
billions of dollars in annual healthcare expenditures.
[0005] AF is the most common arrhythmia seen by physicians, and the
prevalence of AF is growing rapidly as the population ages. The
likelihood of developing AF increases dramatically as people age;
the disorder is found in about 1% of the adult population as a
whole, and in about 6% of those over age 60. By age 80, about 9% of
people (one in 11) will have AF. According to a recent statistical
analysis, the prevalence of AF in the U.S. will more than double by
the year 2050, as the proportion of elderly increases. A recent
study called The Anticoagulation and Risk Factors in Atrial
Fibrillation (ATRIA) study, published in the Spring of 2001 in the
Journal of the American Medical Association (JAMA), found that 2.3
million U.S. adults currently have AF and this number is likely to
increase over the next 50 years to more than 5.6 million, more than
half of whom will be age 80 or over.
[0006] As the prevalence of AF increases, so will the number of
people who develop debilitating or life-threatening complications,
such as stroke. According to Framingham Heart Study data, the
stroke rate in AF patients increases from about 3% of those aged
50-59 to more than 7% of those aged 80 and over. AF is responsible
for up to 35% of the strokes that occur in people older than age
85.
[0007] Efforts to prevent stroke in AF patients have so far focused
primarily on the use of anticoagulant and antiplatelet drugs, such
as warfarin and aspirin. Long-term warfarin therapy is recommended
for all AF patients with one or more stroke risk factors, including
all patients over age 75. Studies have shown, however, that
warfarin tends to be under-prescribed for AF. Despite the fact that
warfarin reduces stroke risk by 60% or more, only 40% of patients
age 65-74 and 20% of patients over age 80 take the medication, and
probably fewer than half are on the correct dosage. Patient
compliance with warfarin is problematic, and the drug requires
vigilant blood monitoring to reduce the risk of bleeding
complications.
[0008] Electrophysiologists classify AF by the "three Ps":
paroxysmal, persistent, or permanent. Paroxysmal AF--characterized
by sporadic, usually self-limiting episodes lasting less than 48
hours--is the most amenable to treatment, while persistent or
permanent AF is much more resistant to known therapies. Researchers
now know that AF is a self-perpetuating disease and that abnormal
atrial rhythms tend to initiate or trigger more abnormal rhythms.
Thus, the more episodes a patient experiences and the longer the
episodes last, the less chance of converting the heart to a
persistent normal rhythm, regardless of the treatment method.
[0009] AF is characterized by circular waves of electrical impulses
that travel across the atria in a continuous cycle, causing the
upper chambers of the heart to quiver rapidly. At least six
different locations in the atria have been identified where these
waves can circulate, a finding that paved the way for maze-type
ablation therapies. More recently, researchers have identified the
pulmonary veins as perhaps the most common area where AF-triggering
foci reside. Technologies designed to isolate the pulmonary veins
or ablate specific pulmonary foci appear to be very promising and
are the focus of much of the current research in catheter-based
ablation techniques.
[0010] Although cardiac ablation devices and methods are currently
available, many advances may still be made to provide improved
devices and methods for ablating-epicardial tissue to treat AF and
other arrhythmias. For example, currently available devices can be
difficult to position and secure on epicardial tissue to perform an
ablation. Devices such as bipolar ablation clamps and others can
ablate tissue only in very limited patterns, such as one or two
straight lines. Ablation devices often have no means for shielding
ablative energy, to avoid unwanted burning of tissues in the
vicinity of the heart, such as the esophagus. Relatively few
devices can be secured to epicardial tissue with sufficient force
to allow for stabilization of the heart. And many ablation devices
may not be introduced by minimally invasive means, thus requiring
an open surgical procedure. Typically, therefore, current cardiac
ablation procedures for AF treatment still require stopping the
heart and using a cardiopulmonary bypass apparatus.
[0011] Therefore, a need exists for improved devices and methods
for ablating epicardial tissue to treat AF and other cardiac
arrhythmias. Preferably, such devices and methods would provide
ablation adjacent to and/or encircling one or more pulmonary veins,
to disrupt conduction pathways and thus partially or completely
treat AF. Also preferably, such devices and methods would allow for
minimally invasive ablation procedures, in some cases on a beating
heart. Such devices might also provide additional advantages, such
as advantageous ablation patterns, shielding of ablative energy
and/or the like. At least some of these objectives will be met by
the present invention.
BRIEF SUMMARY OF THE INVENTION
[0012] Devices and methods of the present invention provide for
ablation of cardiac tissue for treating cardiac arrhythmias such as
atrial fibrillation. Although the devices and methods are often
used to ablate epicardial tissue in the vicinity of at least one
pulmonary vein, various embodiments may be used to ablate other
cardiac tissues in other locations on a heart. Generally, devices
of the invention include a tissue contacting member for contacting
a portion of the epicardial tissue of a heart and securing the
ablation device to the epicardial tissue, and an ablation member
for ablating at least a portion of the tissue. In various
embodiments, the devices have features which enable the device to
attach to the epicardial surface with sufficient strength to allow
the tissue to be stabilized via the device. For example, some
embodiments may be used to stabilize a beating heart to enable a
beating heart ablation procedure. Many of the devices may be
introduced into a patient via minimally invasive incisions,
introducer devices and the like. Although much of the following
description focuses on using devices and methods of the invention
to treat atrial fibrillation (AF) by ablating epicardial tissue on
a human heart, the devices and methods may be used in veterinary or
research contexts, to treat various heart conditions other than
atrial fibrillation and/or to ablate cardiac tissue other than the
epicardium.
[0013] In one aspect, a system for treating heart tissue to treat a
cardiac arrhythmia comprises: at least one energy transmission
member for applying energy to the heart tissue in a pattern to
treat the cardiac arrhythmia; at least one tissue securing member
coupled with the at least one energy transmission member for
enhancing contact of the energy transmission member with the heart
tissue; and at least one guiding member coupled with at least one
of the energy transmission member and the tissue securing member
for guiding the energy transmission member and the tissue securing
member to a location for treating the heart tissue.
[0014] Optionally, such as system may further include at least one
visualization member for enhancing visualization of the heart
tissue and the treatment location. In some embodiments, for
example, the visualization member may include an optic imaging
device, a thermal imaging device, an ultrasound device, an
electrical imaging device, a Doppler imaging device or the like,
though any suitable device may be used. In some embodiments, an
optic imaging device comprises a fiber optic device positionable to
view a posterior portion of the heart tissue. In other embodiments,
a thermal imaging device measures at least one heat transfer
coefficient of the heart tissue to determine at least one of a type
and a thickness of the heart tissue. In still other embodiments, an
electrical imaging device measures electrical resistance and/or
impedance of the heart tissue to determine a type and/or a
thickness of the heart tissue.
[0015] In some embodiments, the at least one visualization member
is removably coupled with at least one of the at least one energy
transmission member, the at least one tissue securing member and
the at least one guiding member. Also in some embodiments, the at
least one visualization member may comprise at least one optic
member for acquiring optic signals of an area to be visualized, and
wherein the visualization member includes at least one inflatable
member coupled with the visualization member at or near the optic
member. For example, the inflatable member may provide a space in a
body cavity and/or between at least two body tissues to enhance
operation of the optic member. In some embodiments, the inflatable
member includes an inflation port in fluid communication with an
inflation lumen coupled with the visualization member for allowing
introduction of a liquid or a gas to inflate the inflatable member.
In some embodiments, the inflatable member reduces motion of the
heart tissue when applied to the heart tissue.
[0016] Some embodiments of the invention also include at least one
positioning device for contacting the heart tissue and positioning
the heart tissue for treatment. For example, the positioning device
may comprise a suction positioning device. In some embodiments, the
positioning device reduces motion of a beating heart to further
position the heart tissue for treatment.
[0017] The energy applied to the heart tissue may be any suitable
energy, such as but not limited to radio frequency energy,
ultrasound energy, microwave energy, cryogenic energy,
thermoelectric energy and laser energy. In some embodiments,
optionally, the energy transmission member contacts an epicardial
surface of the heart tissue to transmit the energy, and wherein the
energy is transmitted from the epicardial surface through the heart
tissue to an endocardial surface. Sometimes, the energy is further
transmitted through at least one of fat and connective tissue
covering at least part of the epicardial surface. Some embodiments
also include at least one grounding device for dispersing the
energy from a patient undergoing an energy transmission heart
procedure. Some embodiments may also include at least one needle
coupled with the energy transmission member for insertion into the
heart tissue to enhance the application of energy to the heart
tissue. In some of these embodiments, the energy is transmitted
from a tip of each needle. Optionally, the needle may be
retractable. In some embodiments, for example, the retractable
needle is exposed and retracted via a pneumatic member coupled with
the energy transmission member. In some embodiments, the
retractable needle is exposed and retracted automatically when the
energy transmission member contacts the heart tissue. Also in some
embodiments, the depth of penetration of the retractable needle
into the heart tissue is adjustable.
[0018] Some embodiments may also include at least one closed
circuit feedback loop for measuring and regulating operation of the
energy transmission member. In some embodiments, either the energy
transmission member or the tissue securing member further comprises
at least one fluid aperture for applying fluid to the heart tissue
to enhance the application of energy to the heart tissue.
[0019] In some embodiments, the energy transmission member is
coupled with at least one guiding member such that a change in
shape of the guiding member causes a corresponding change in shape
of the energy transmission member. For example, the guiding member
may comprise a deformable linear member, its shape being adjustable
by a user, and wherein the energy transmission member comprises a
deformable linear member coaxially coupled with the guiding member
so as to move with the guiding member. In some embodiments, the
guiding member is adjustable to at least partially encircle at
least one pulmonary vein.
[0020] In some embodiments, the tissue securing member includes at
least one connector for removably coupling with the at least one
energy transmission member. Sometimes, the tissue securing member
is conformable to a surface topography of the heart tissue. In
various embodiments, a first longitudinal axis of the tissue
securing member and a second longitudinal axis of the removably
coupled energy transmission member may be collinear, parallel to
one another or offset from one another. In some embodiments, the
energy transmission member comprises a linear member, and the
connector comprises a plurality of connectors disposed along a
length of the tissue securing member for removably coupling the
linear member with the tissue securing member. The tissue securing
member may allow compressive force to be applied between the at
least one energy transmission member and the heart tissue.
[0021] In some embodiments, the tissue securing member comprises at
least one vacuum applying member. The vacuum applying member may
comprise, for example: at least one vacuum lumen; at least one
vacuum port in fluid communication with the lumen for coupling the
lumen with a vacuum source; and at least one aperture in fluid
communication with the lumen for applying vacuum force to the heart
tissue. In some embodiments, the vacuum lumen comprises multiple,
separate lumens, and each separate lumen is in fluid communication
with a separate vacuum port. Such embodiments may optionally
further include means for selectively applying vacuum to one or
more of the separate lumens without applying vacuum to one or more
other separate lumens. Alternatively or in addition, the apparatus
may be provided with suction pod plugs that serve to occlude one or
more of the suction apertures so that suction is applied only
through the remaining suction apertures that have not been occluded
with a suction pod plug.
[0022] In other embodiments, the tissue securing member comprises
at least one expansible balloon member. The expansible balloon
member may include at least one fluid introduction port for
allowing introduction of a liquid or a gas to expand the balloon
member. Some embodiments include multiple, separate balloon
members, wherein each separate balloon member is in fluid
communication with a separate fluid introduction port. Such
embodiments may also include means for selectively introducing
fluid into one or more of the separate balloons without introducing
fluid into one or more other separate balloons. Optionally, in some
embodiments, the tissue securing member prevents a portion of the
heart tissue from being treated by the at least one energy
transmission member. For example, the tissue securing member may
comprise at least one insulation material for preventing the
portion of the heart tissue from being treated. In one embodiment,
the insulation material further prevents the at least one energy
transmission member from contacting or harming other, non-cardiac
tissue of the patient and from contacting or harming a user of the
energy transmission member.
[0023] In some embodiments, the guiding member comprises at least
one of an elongate shaft, a steerable guidewire and an introducer
sheath. For example, the steerable guidewire may comprise a
pushable guidewire having at least one relatively stiff portion and
one relatively flexible portion for positioning the energy
transmission member in a location for treatment. For example, the
steerable guidewire may comprise a pullable guidewire to which
tension is applied to steer the guidewire to position the energy
transmission member in a location for treatment.
[0024] In another aspect, a system for treating heart tissue to
treat a cardiac arrhythmia comprises: at least one therapeutic
agent transmission member for applying at least one therapeutic
agent to the heart tissue in a pattern to treat the cardiac
arrhythmia; at least one tissue securing member coupled with the at
least one energy transmission member for enhancing contact of the
energy transmission member with the heart tissue; and at least one
guiding member coupled with at least one of the energy transmission
member and the tissue securing member for guiding the energy
transmission member and the tissue securing member to a location
for treating the heart tissue. In some embodiments, for example,
the therapeutic agent transmission member comprises at least one
lumen and at least one aperture in the lumen for allowing passage
of the at least one therapeutic agent out of the lumen to contact
the heart tissue.
[0025] Optionally, such a system may further include at least one
needle coupled with the therapeutic agent transmission member for
insertion into the heart tissue to enhance application of the at
least one therapeutic agent to the heart tissue. The therapeutic
agent transmission member itself may comprise at least one needle
and at least one aperture adjacent a tip of each needle for
allowing passage of the at least one therapeutic agent out of the
needle to contact the heart tissue. Optionally, the needle may be
retractable. For example, the retractable needle may be exposed and
retracted via a pneumatic member coupled with the therapeutic agent
transmission member. In some embodiments, the retractable needle is
exposed and retracted automatically when the therapeutic agent
transmission member contacts the heart tissue. Also in some
embodiments, a depth of penetration of the retractable needle into
the heart tissue is adjustable.
[0026] In another aspect of the invention, a method for treating
heart tissue of a patient to treat a cardiac arrhythmia involves:
advancing at least one treatment member coupled with at least one
tissue securing member through an incision on the patient;
visualizing a treatment area in the patient with at least one
visualization member; contacting the heart tissue of the patient
with the treatment member and the tissue securing member; applying
a force, through the tissue securing member, to enhance contact of
the treatment member with the heart tissue; and treating the heart
tissue, using the at least one treatment member. In some
embodiments, the treatment member and/or the tissue securing member
are advanced through a port applied to the patient, the port having
a diameter no greater than 5 cm.
[0027] In some embodiments, the advancing step includes guiding the
treatment member and/or the tissue securing member using at least
one guiding member. Guiding may involve, for example, using a
pushable guidewire having at least one relatively stiff portion and
one relatively flexible portion for positioning the treatment
member in a location for treatment. Alternatively, guiding may
involve using a pullable guidewire to which tension is applied to
steer the guidewire to position the treatment member in a location
for treatment.
[0028] Some embodiments of the method further include using at
least one positioning device to position the heart tissue for
treatment. This may involve, for example, applying suction to the
heart tissue. In some embodiments, using the positioning device
reduces motion of the heart tissue. In other embodiments,
contacting the heart tissue comprises applying a suction force with
the tissue securing member to increase a contact surface area of
the tissue securing member with the heart tissue. Applying the
suction force may further comprise providing consistent contact
force between the heart tissue and the tissue securing member.
Optionally, applying the suction force may comprise securing the
tissue securing member and the treatment member to the heart
tissue, the tissue securing member and the treatment member having
the same cross-sectional shape.
[0029] In some embodiments, treating the heart tissue comprises
applying energy to the heart tissue in a pattern to reduce or
eliminate the cardiac arrhythmia. The applied energy may be in any
suitable form, such as radio frequency energy, ultrasound energy,
microwave energy, cryogenic energy, thermoelectric energy or laser
energy. In some embodiments, the energy is applied to an epicardial
surface of the heart, wherein the energy is transmitted from the
epicardial surface through the heart tissue to an endocardial
surface. Optionally, the energy may be further transmitted through
fat and/or connective tissue covering at least part of the
epicardial surface. Some methods may further include dispersing the
energy from the patient through at least one grounding device
coupled with the patient.
[0030] Some embodiments further involve inserting at least one
needle into the heart tissue to enhance the application of energy
to the heart tissue. For example, the energy may transmitted from a
tip of each needle. Some methods include extending the at least one
needle from a retracted position before applying the energy and
retracting the at least one needle to the retracted position when
the energy has been applied. Such methods may also include
selecting a depth of penetration of the at least one retractable
needle into the heart tissue. Other embodiments may involve
measuring the application of energy to the heart tissue using at
least one closed circuit feedback loop and regulating the
application of energy to the heart tissue based on the measurement.
Still other embodiments may include applying fluid to the heart
tissue to enhance the application of energy to the heart
tissue.
[0031] In alternative embodiments, treating the heart tissue
comprises applying at least one therapeutic agent to the heart
tissue in a pattern to reduce or eliminate the cardiac arrhythmia.
For example, applying the at least one therapeutic agent may
involve infusing the agent through at least one aperture in the at
least one treatment member. In some embodiments, the therapeutic
agent is infused through at least one aperture in at least one
needle coupled with the treatment member. In some embodiments,
applying the at least one therapeutic agent comprises inserting at
least one needle into the heart tissue to a desired depth,
injecting the at least one agent into the heart tissue, and
removing the at least one needle from the heart tissue. Such a
method may further include extending the at least one needle from a
retracted position for insertion into the heart tissue and
retracting the at least one needle to the retracted position after
injection.
[0032] Yet another embodiment may include adjusting a shape of a
guiding member coupled with the at least one treatment member to
alter the shape of the treatment member. In some embodiments,
adjusting the shape of the guiding member allows the treatment
member to conform to a surface of the heart tissue. Also in some
embodiments, adjusting the shape of the guiding member allows the
treatment member to at least partially encircle at least one
pulmonary vein. Some embodiments may also include removably
coupling the tissue securing member with the at least one treatment
member. Some embodiments may further include conforming the tissue
securing member to a surface topography of the heart tissue.
[0033] In some embodiments, applying force comprises applying
compressive force between the at least one treatment member and the
heart tissue. Applying the compressive force, in turn, may comprise
applying vacuum force via at least one vacuum member of the tissue
securing member. Such methods may further involve applying the
vacuum force through at least a portion of the vacuum member while
not applying the vacuum force through at least another portion of
the vacuum member. In some embodiments, applying the compressive
force comprises applying force via at least one expansible balloon
member. A method may further comprising preventing, using the
tissue securing member, a portion of the heart tissue from being
treated by the at least one treatment member. For example, the
tissue securing member may comprise at least one insulation
material for preventing the portion of the heart tissue from being
treated.
[0034] In some embodiments, visualizing comprises using at least
one visualization member selected from the group consisting of an
optic imaging device, a thermal imaging device, an ultrasound
device, an electrical imaging device and a Doppler imaging device.
Some embodiments also include expanding an expansible balloon
coupled with the visualization member near an optic element to
enhance visualization. Sometimes, expanding the balloon provides a
space in a body cavity and/or between at least two body tissues to
enhance operation of the optic member. Optionally, expanding the
balloon may reduce motion of the heart tissue when applied to the
heart tissue.
[0035] The invention also includes ablation systems which include
an ablation energy source for providing energy to the ablation
device. The ablation energy source of the invention is particularly
suited for use with ablation apparatus as described herein using RF
energy, but is not limited to such use, and other kinds of ablation
energy sources and ablation devices may be useable in the
invention. A typical RF ablation system comprises a RF generator
which feeds current to an ablation device, including those
described in this application, containing a conductive electrode
for contacting targeted tissue. The electrical circuit is completed
by a return path to the RF generator, provided through the patient
and a large conductive plate, which is typically in contact with
the patient's back.
[0036] In some embodiments, the ablation system is configured to
recognize the kind of ablation device connected by including keyed
plugs, which describes specialized socket shapes configured to
accept only plugs which are manufactured with the matching shape.
The energy source includes predetermined settings appropriate for
the kind of device that is accepted by that socket. In another
embodiment, the ablation system of the invention includes apparatus
for recognizing the kind of device that has been coupled to the
energy source and for automatically adjusting various settings to
accommodate the detected device.
[0037] In further embodiments the ablation device may be inserted
minimally invasively under stress, and is configured to conform to
the topography or anatomy of the tissue to be treated when relaxed.
This feature may enhance the adherence of the ablation device to
the tissue because the suction is not working against resistance of
the ablation device to conforming to the desired shape.
[0038] In other embodiments, the ablation device may include
indicators for identifying which ablation element is to be
activated. For example, the ablation device may include different
colored lines to assist the user in distinguishing the orientation
and alignment of the ablation device.
[0039] In some embodiments, the ablation device may be configured
to allow the ablation member to extend beyond the edge of the
tissue contacting member to allow for ablation to occur outside of
the region covered by the tissue contacting member.
[0040] In another embodiments, the artery securing arms may instead
be configured to grasp a second ablation member, thereby allowing
ablation to occur outside of the region covered by the tissue
contacting member.
[0041] In some embodiments the length of the suction pods may be
varied such that suction pods of more than one length are used on
the same tissue contact member. Furthermore, the suction pods may
be spaced apart or placed in groupings separated by selected
lengths. Some or all of the length of the ablation device used to
emit ablation energy may not include any suction pods. In some
embodiments an insulated member may cover the majority of the
geometry of the ablation device such that only areas contacting
target tissue can emit energy that will penetrate the tissue. This
feature may protect surrounding tissues from unintentional
ablation. Positioning the ablation member within an insulating
tissue contacting member provides a safety margin protecting
adjacent tissue that is not intended to be ablated. The insulated
member may include lumens for delivering saline to lower impedance
or increase conductivity or other substance to improve performance
and efficiency of energy emission.
[0042] The suction force may be used to create a fluid gradient
through the thickness of the tissue. A dynamic fluid gradient may
enhance energy conduction.
[0043] In some apparatus and methods of the invention, once the
tissue contact member is positioned and suctioned onto the heart,
the probe may also be slid within the probe channel in the tissue
contact member so that the energy emitting section of the ablation
member may be positioned as a separate step from the step of
positioning the tissue contacting member. It is also possible to
position the tissue contacting member separately from the ablation
member, then in a later step, slide the ablation member into the
tissue contact member. In some embodiments, an ablation member with
a short energy emitting section may be moved along a channel in the
tissue contact member so that the device can create long lesions,
perhaps longer than the ablation section of the ablation member,
with minimal manipulations of the device within the track.
[0044] Using a single placement of the tissue contacting member may
enhance continuity of ablation lesions. Not having to move the
ablation device between discrete ablation cycles, and instead only
moving the ablation member within the tissue contacting member,
insures that adjacent ablation segments are contiguous with no
ablation gaps. Avoiding the creation of gaps can be critical to
insure electrical isolation of desired tissue areas, and may also
decrease procedure time by not requiring the surgeon to verify
overlap of adjacent ablation lesions.
[0045] In some embodiments the preferred features of the material
used to manufacture the tissue contacting member include one or
more of the following: the material provides electrical or thermal
insulation, the material is flexible to facilitate remote
advancement via tortuous pathways, the material has shape memory
allowing large elastic deformation of the tissue contacting member
but also allowing the tissue contacting member to return to a
preformed shape in a relaxed configuration, the material may be
translucent or transparent to help the user see the position of the
ablation probe, and the material may be lubricious to facilitate
insertion and placement.
[0046] The method may further include the steps of using visual and
audible cues to verify the ablation device is adhered to tissue.
For example the user can hear a suction sound or `whistle` when the
suction has been activated and the ablation device is not correctly
adhered. Also, the user can hear vacuum pump elevate as vacuum
increases. In some embodiments, the user can visually observe the
tissue contacting member collapse when the ablation device is
correctly adhered and suction is activated.
[0047] In some embodiments, the preferred vacuum pressure is -200
mmHG to -760 mmHG.
[0048] In still further embodiments, the ablation device may
include more electrodes that are available on the energy source. In
this embodiment, the ablation device includes a plurality of
electrodes, and wherein the energy source includes fewer electrodes
than the ablation device. Further, the ablation device includes at
least two plugs, with each plug providing power to a subset of the
plurality of electrodes on the ablation device. The method
comprises the steps of connecting the first plug of the ablation
device to the energy source, applying ablation energy to the
tissue, unplugging the first plug from the energy source, plugging
the second plug of the ablation device into the energy source, and
applying ablation energy to the tissue.
[0049] This allows ablation device construction to facilitate
longer ablations by utilizing multiple connections to the energy
source. For example, if an energy source includes seven electrodes
coupled to a single plug to power seven ablation segments on the
ablation device, the ablation device could include fourteen or
twenty-one separate ablation segments. Each set of seven ablation
segments would couple to a separate plug. In use, the first plug is
inserted into the energy source and the first set of seven ablation
segments is activated. Upon completion of treatment, possibly
without moving the ablation device, a second region may be ablated
by removing the first plug and inserting the second plug to
activate the next seven ablation segments on the ablation device.
This embodiment can result in a smaller, less expensive energy
source that is still capable of powering a long ablation
device.
[0050] In yet another aspect, a method for treating heart tissue of
a patient to treat a cardiac arrhythmia comprises: advancing at
least one treatment member and at least one tissue securing member
through an incision on the patient; removably coupling the at least
one treatment member with the at least one tissue securing member;
visualizing a treatment area in the patient with at least one
visualization member; contacting the heart tissue of the patient
with the treatment member and the tissue securing member; applying
a force, through the tissue securing member, to enhance contact of
the treatment member with the heart tissue; and treating the heart
tissue, using the at least one treatment member. In some
embodiments, and treatment member is advanced through the tissue
securing member. Optionally, in some embodiments, the treatment
member and the tissue securing member are advanced through a
minimally invasive port applied to the patient. Another method of
the invention includes the following steps. An introducer is
advanced through a first incision into the transverse sinus cavity
with obturator fully inserted. At a desired area near the pulmonary
veins, the obturator is withdrawn, which allows the introducer to
assume its pre-formed J shape reaching around the pulmonary veins,
possibly also guided by contact with the pericardium. The
introducer is preferably long enough to be inserted through a
thoracotomy into the transverse sinus cavity around the pulmonary
veins and out through the oblique sinus and out through the same or
a different thoracotomy. Another instrument is advanced through the
same or different thoracotomy to grasp the distal end of the
introducer. The introducer is pulled around the pulmonary veins
until the distal end is outside the body of the patient. At this
point, both the proximal and distal ends of the introducer are
preferably outside the body of the patient. Once the ablation
device is in position, suction is applied to adhere the ablation
device to the tissue surrounding the pulmonary veins. Ablation
energy is applied. Once treatment is complete, the ablation device
can be removed.
[0051] Various embodiments of the devices and methods described
briefly above are further described in the appended drawings and
the following detailed description. The description of specific
embodiments is provided for exemplary purposes and should not be
interpreted to narrow the scope of the invention as defined in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a perspective view illustration of a human heart
and an ablation device in position for performing an ablation
procedure, according to one embodiment of the invention.
[0053] FIG. 2 is a perspective view of an ablation device,
according to one embodiment of the invention.
[0054] FIG. 2a is a perspective view of the ablation device shown
in FIG. 2, with the ablation member removed.
[0055] FIG. 3 is a bottom-surface view of an ablation device,
according to one embodiment of the invention.
[0056] FIG. 4 is a perspective view of a flexible, elongate
ablation device with two rows of suction apertures, according to
one embodiment of the invention.
[0057] FIG. 4a is a bottom-surface view of the ablation device as
shown in FIG. 4, with the ablation member removed.
[0058] FIG. 5 is a bottom-side view of a flexible, elongate
ablation device with one row of suction apertures, according to one
embodiment of the invention.
[0059] FIGS. 5a, 5b, and 5e are perspective views of another
embodiment of a flexible, elongate ablation device with one row of
suction apertures, separated by flexible joining members.
[0060] FIGS. 5c and 5d show several alternate cross sections of the
flexible joining members of FIGS. 5a and 5b.
[0061] FIG. 6 is a perspective view of a human heart and an
ablation device in position for performing an ablation procedure,
according to one embodiment of the invention.
[0062] FIG. 7 is a perspective view of an elongate shaft ablation
device, according to one embodiment of the invention.
[0063] FIG. 7a is a perspective view of the distal end of a shaft
as in FIG. 6, with straight jaws, according to one embodiment of
the invention.
[0064] FIG. 8 is a perspective view of a human heart and an
elongate shaft ablation device in position for ablating cardiac
tissue, according to one embodiment of the invention.
[0065] FIG. 9 is a block diagram of a method for ablating tissue
according to one embodiment of the invention.
[0066] FIG. 10 is an embodiment of the invention including an
elongated tissue contact member, built in accord with the
invention.
[0067] FIG. 11 is an example embodiment of a power source built in
accord with the invention.
[0068] FIGS. 12a and 12b is an example of an ablation device in
accord with the invention, and an introducer for use with the
ablation device.
[0069] FIG. 13 is an assembly drawing of an ablation device in
accord with the invention, and an introducer for use with the
ablation device.
[0070] FIG. 14 is an exploded view showing the components of the
ablation device of FIG. 13.
DETAILED DESCRIPTION OF THE INVENTION
[0071] The present invention relates generally to medical devices
and methods and more specifically to devices and methods for
ablating cardiac tissue for treating cardiac arrhythmias such as
atrial fibrillation. Ablation of cardiac tissue in various patterns
has been shown to disrupt conduction pathways in the heart to
ameliorate or eliminate AF or other arrhythmias. The devices and
methods will often be used to ablate epicardial tissue in the
vicinity of at least one pulmonary vein, but various embodiments
may be used to ablate other cardiac tissues in other locations on a
heart.
[0072] Generally, ablation devices of the invention include at
least one tissue contacting member for contacting a portion of the
epicardial tissue of a heart, securing means for securing the
ablation device to the tissue and at least one ablation member
coupled with the contacting member for ablating at least a portion
of the tissue. In various embodiments, the devices have features
which enable the device to attach to the epicardial surface with
sufficient strength to allow the tissue to be stabilized via the
device. For example, some embodiments may use suction force to
secure the device to epicardial tissue and stabilize a beating
heart to enable a beating heart ablation procedure. In some
embodiments, the preferred vacuum pressure is -200 mmHG to -760
mmHG. The suction force may be used to create a fluid gradient
through the thickness of the tissue. A dynamic fluid gradient may
enhance energy conduction. Other embodiments may include other
optional features, such as sensors for sensing whether tissue has
been ablated, a support member with an arm for connecting the
device to a positioning device, cooling apparatus for cooling
epicardial tissue, visualization devices and/or the like. Some
embodiments of the device are introducible into a patient via
minimally invasive means, such as a minimally invasive incision,
sheath, trocar or the like. Ablation devices of the invention
configured for use in minimally invasive procures will, in some
embodiments, be longer than two feet the majority of the probe
rests outside of the patient while the active ablation portion of
the device is inserted via minimally invasive incision. Some
embodiments will further comprise apparatus for reducing kinking of
the ablation probe.
[0073] In alternate embodiments the length of the suction pods may
be varied such that suction pods of more than one length are used
on the same tissue contacting member. Furthermore, the suction pods
may be spaced apart or placed in groupings separated by lengths of
the probe or ablation device. Some or all of the length of the
ablation device used to emit ablation energy may not include any
suction pods. In such embodiments an insulated member may cover the
majority of the geometry of the ablation device such that only
areas contacting target tissue can emit energy that will penetrate
the tissue. This feature may protect surrounding tissues from
unintentional ablation. Positioning the ablation member within an
insulating tissue contacting member provides a safety margin
protecting adjacent tissue that is not intended to be ablated. The
insulated member may include lumens for delivering saline to lower
impedance or increase conductivity or other substance to improve
performance and efficiency of energy emission. In other
embodiments, the ablation device may include indicators for
identifying which ablation element is to be activated. For example,
the ablation device may include different colored lines to assist
the user in distinguishing the orientation and alignment of the
ablation device.
[0074] The invention also includes ablation systems which include
an ablation energy source for providing energy to the ablation
device. The ablation energy source of the invention is particularly
suited for use with ablation apparatus as described herein using RF
energy, but is not limited to such use, and other kinds of ablation
energy sources and ablation devices may be useable in the
invention. A typical RF ablation system comprises a RF generator
which feeds current to an ablation device, including those
described in this application, containing a conductive electrode
for contacting targeted tissue. The electrical circuit is completed
by a return path to the RF generator, provided through the patient
and a large conductive plate, which is typically in contact with
the patient's back.
[0075] In some embodiments, the ablation system is configured to
recognize the kind of ablation device connected by including keyed
plugs, which describes specialized socket shapes configured to
accept only plugs which are manufactured with the matching shape.
The energy source includes predetermined settings appropriate for
the kind of device that is accepted by that socket.
[0076] In another embodiment, the ablation system of the invention
includes apparatus for recognizing the kind of device that has been
coupled to the energy source and for automatically adjusting
various settings to accommodate the detected device.
[0077] Methods of the invention generally include contacting a
device with epicardial tissue, using a tissue contacting member on
the device to secure the device to the tissue, and ablating the
tissue with an ablation member on the device. In some embodiments,
the method further includes additional steps such as positioning
the device on the epicardial tissue, stabilizing cardiac tissue,
cooling cardiac tissue, positioning the device using a positioning
device, visualizing epicardial tissue with an imaging device and/or
the like. Again, although much of the following description focuses
on embodiments used to treat AF by ablating epicardial tissue near
one or more pulmonary veins on a human heart, the devices and
methods may be used in veterinary or research contexts, to treat
various heart conditions other than AF, to ablate cardiac tissue
other than the epicardium and/or in any other suitable manner or
context.
[0078] Referring now to FIG. 1, an ablation device 100 is shown in
position for ablating epicardial tissue on a human heart 140. A top
view of ablation device 100 is shown, the visible components of
device 100 including a tissue contacting member 102 coupled with a
suction connector 216 and a support member 104 having a support arm
106. Tissue contacting member 102 also includes multiple artery
securing arms 108 for securing one or more coronary arteries.
Suction connector 216 is coupled with a suction cannula 112, which
in turn is coupled with a suction source 120. Support arm 106 is
coupled via a clamp 116 to a positioner 114, which in turn is
coupled to a stabilizing device 118 for stabilizing positioner 114.
Finally, an ablation member (not visible) of ablation device 100 is
coupled, via a wire 110, to an energy source 122. In various
embodiments, ablation device 100 may be introduced into a patient
through a minimally invasive introducer device, such as a sheath
124, trocar or the like, as is represented in FIG. 1 by a
simplified representation of sheath 124.
[0079] In an alternate embodiment, the artery securing arms 108 may
instead be configured to grasp a second ablation member, thereby
allowing ablation to occur outside of the region covered by the
tissue contacting member. In this embodiment the features 108 are
instead auxiliary securing arms. Although example auxiliary
securing arms are shown only in FIG. 1, this feature could be used
on other ablation device embodiments.
[0080] In FIG. 1, ablation device 100 is shown in a position
partially encircling the right superior pulmonary vein 142 and the
right inferior pulmonary vein 144. As will be described in further
detail below, such a position is only one possible configuration
for treating heart 140. In other embodiments, for example, both of
the right pulmonary veins 142, 144 may be completely encircled,
only one may be partially or completely encircled, the left
superior 148 and/or left inferior 150 pulmonary veins may be
partially or completely encircled and/or various patterns may be
ablated on the left atrium 146, the right atrium 152 and/or the
right and left ventricles (not labeled). Any ablation pattern
suitable for heart treatment may be accomplished by one or more
embodiments of the present invention. Thus, the following
descriptions of various embodiments should not be interpreted to
narrow the scope of the invention as set forth in the claims.
[0081] Generally, ablation device 100 includes at least one tissue
contacting member 102 coupled with at least one ablation member
(not shown in FIG. 1). One embodiment of a device which may be used
as tissue contacting member 102 is described in U.S. Patent
Application Ser. No. 60/182,048, filed on Feb. 11, 2000, the entire
contents of which is hereby incorporated by reference. Ablation
device 100 shown in FIG. 1 actually includes two tissue contacting
members 102, one on either side of the right pulmonary veins 142,
144. Tissue contacting members 102 may be coupled together via
support member 104 and suction connector 216. In other embodiments,
some of which will be described below, tissue contacting member 102
may include only one member, more than two members, a coupling
member disposed between multiple arms and/or the like.
Alternatively, tissue contacting member 102 may be conical, linear,
shaped as a flat pad or a flat elongate member or may have any
other suitable configuration. Additionally, tissue contacting
members 102 may have any suitable size and dimensions. For example,
in FIG. 1, tissue contacting members 102 and device 100 in general
have a shape and dimensions to contact and ablate epicardial tissue
on heart 140 in a pattern partial encircling the right pulmonary
veins 142, 144. Many other configurations and sizes are possible,
as described further below.
[0082] Tissue contacting members 102 may be manufactured from any
suitable material, such as a polymer, plastic, ceramic, a
combination of materials or the like. In one embodiment, for
example, tissue contacting members 102 are manufactured from a
liquid molded rubber. In some embodiments, the material used to
make tissue contacting members 102 is chosen to allow the members
102 to be at least partially deformable or malleable. Deformable
tissue contacting members 102 may allow ablation device 100 to be
inserted into a patient and/or advanced to a surgical site within
the patient via a minimally invasive incision or a minimally
invasive introducer device, such as sheath 124. Deformable tissue
contacting members 102 may also allow device 100 to conform to a
surface of heart 140, to enhance ablation of epicardial or other
cardiac tissue. In some embodiments, tissue contacting members 102
include one or more artery securing arms 108, for securing,
exposing and/or occluding one or more coronary arteries via
silastic tubing attached between the artery and securing arm 108.
Securing arms 108 are generally made of the same material(s) as
tissue contacting members 102 but may also suitably comprise other
materials.
[0083] In some embodiments the ablation device may be inserted
minimally invasively under stress, and is configured to conform to
the topography or anatomy of the tissue to be treated when relaxed.
This feature may enhance the adherence of the ablation device to
the tissue because the suction is not working against resistance of
the ablation device to conforming to the desired shape.
[0084] Thus, some embodiments the preferred features of the
material used to manufacture tissue contacting member 102 may
further include one or more of the following characteristics: the
material provides electrical or thermal insulation, the material is
flexible to facilitate remote advancement via tortuous pathways,
the material has shape memory allowing large elastic deformation of
the tissue contacting member but also allowing the tissue
contacting member to return to a pre-formed shape in a relaxed
configuration, the material may be translucent or transparent to
help the user see the position of the ablation probe, the material
may be lubricious to facilitate insertion and placement, and the
material allows thin walled construction of the tissue contacting
member so that collapse of the tissue contacting member can be seen
to confirm the operation of the vacuum when activated.
[0085] In some embodiments, tissue contacting members 102 are
coupled with support member 104. Support member 104 may be made of
any suitable biocompatible material, such as titanium, stainless
steel, nickel titanium alloy (Nitinol) or the like. Support member
104 may be coupled with tissue contacting members 102 by any
suitable means, such as but not limited to one or more adhesive
substances, placement of a portion of support member 104 within a
sleeve on tissue contacting members 102 or a combination of both.
Like tissue contacting members 102, support member 104 may also be
malleable or deformable to allow for insertion of ablation device
100 through a minimally invasive sheath 124 and/or for enhancing
conformability of device 100 to a surface of heart 140. Support
member 104 typically includes at least one support arm 106 or
similar protrusion or multiple protrusions for removably coupling
ablation device 100 with positioner 114 or one or more other
positioning devices. Positioner 114, for example, may comprise a
flexible, positioning arm, with attachment means such as clamp 116
for attaching to support arm 106 and stabilizing device 118 for
stabilizing positioner 114. For example, a flexible, articulating
positioner 114 may be of the type which rigidities when tensile
force is applied, such as via a tensioning wire. Any other suitable
positioner 114 may alternatively be used. In other embodiments,
device 100 may not include support member 104. Such devices 100 may
incorporate a connection arm onto a tissue contacting member 102,
may be positioned on heart 140 using a positioning device inserted
through a separate incision, or may be positioned or manipulated by
a physician or other user via any other suitable means.
[0086] Tissue contacting members 102 may also be coupled with one
or more suction cannulas 112 to provide suction for enhancing
contact of ablation device 100 with epicardial tissue. In various
embodiments, tissue contacting members 102 may be directly coupled
to one or more cannulas 112 or may be connected via one or more
suction connectors 216. In FIG. 1, a V-shaped suction connector is
used to couple the two tissue contacting members 102 with a common
cannula 112. Cannula 112, in turn, is connected to suction source
120, which may be a conventional wall suction or stand-alone
suction source. Generally, cannula 112 may be any suitable
conventional cannula 112, which are well known to those skilled in
the art. Suction connector 216 is typically comprised of the same
material(s) as tissue contacting members 102, but may also be made
of a material or materials used to make cannula 112. Suction
connector 216 may further include a nozzle 218 (FIG. 2) for
connecting to cannula 112.
[0087] Ablation device 100 also includes at least one ablation
member 210 (FIG. 2). Ablation member 210 typically receives energy
from a separate energy source 122, although ablation members 210
with internal energy sources are also contemplated. Where a
separate energy source 122 is used, ablation member 210 may be
coupled with source 122 by any suitable means. In one embodiment,
for example, ablation member 210 may be coupled to energy source
122 with wire 110. Wire 110 may be any suitable connector, such as
fiber optic cable, electric cable, coaxial cable, ultrasound
transmission device or the like. As is described further below, any
suitable energy may be provided by energy source 122 for ablation
and any means for transmitting energy to ablation member 210 is
contemplated within the scope of the invention. In some
embodiments, for example, energy may be transmitted remotely, so
that no wires or other similar connecting devices are required. In
other embodiments, radio frequency energy may be provided by an RF
energy source and transmitted to ablation member 210 via
conventional electrical wire(s) 110.
[0088] Generally, ablation member 210 may be configured to transmit
energy of any suitable quantity or force. For example, in some
embodiments sufficient energy will be transmitted through ablation
member 210 to ablate only epicardial tissue on a heart. In other
embodiments, sufficient energy may be transmitted to cause one or
more layers beneath the epicardial tissue to be ablated. In some
embodiments, for example, one or more transmural lesions (across
the entire wall of the heart) may be ablated. Typically, an amount
of energy transmitted through ablation member 210 will be
adjustable to create a desired ablation depth. In addition, the
depth of ablation can also be affected by the contact pressure
between the ablation member 210 and the tissue. Generally, the
greater the contact pressure between the ablation member 210 and
the tissue the deeper the ablation lesion will extend into the
tissue. The contact pressure can be adjusted to a desired level by
adjusting the mechanical force applied through the tissue
contacting members 102 and/or by adjusting the level of suction
applied through the suction apertures 212.
[0089] In addition, the contact pressure between the ablation
member 210 and the tissue gives a degree of directional control
over the direction the lesion ablation lesion will extend into the
tissue. Only the tissue in contact with the ablation member 210 and
in a direction perpendicular to the surface of the tissue will be
ablated. Adhering the ablation member 210 to the target tissue with
suction applied through the suction apertures 212 assures that only
the intended tissue will be ablated and will prevent migration or
rollover of the tissue contacting members 102 and ablation member
210.
[0090] In this example and other embodiments disclosed herein, the
suction apertures 212 may be connected to multiple, separate
suction lumens. Optionally, the apparatus may include means for
selectively applying vacuum to one or more of the separate lumens
without applying vacuum to one or more other separate lumens.
Alternatively or in addition, the apparatus may be provided with
suction pod plugs that serve to occlude one or more of the suction
apertures 212 so that suction is applied only through the remaining
suction apertures 212 that have not been occluded with a suction
pod plug.
[0091] As mentioned briefly above, a minimally invasive introducer
sheath 124, trocar or other minimally invasive device may be used
for introducing one or more of the components shown in FIG. 1 into
a patient. In some embodiments, a sheath need not be used and
instead only a minimally invasive incision is used. In other
embodiments, multiple minimally invasive incisions and/or sheaths
124 may be used for introducing various devices into a patient. For
example, one sheath 124 may be used for introducing ablation device
100 and another sheath 124 may be used for introducing positioner
114. Although devices and methods of the present invention are
often suitable for minimally invasive procedures, they may also
typically be used in open surgical procedures, either with or
without cardiopulmonary bypass, in various embodiments.
[0092] Referring now to FIG. 2, an embodiment of ablation device
100 is shown in further detail. Device 100 is shown from a
bottom/angled view to show a tissue contacting surfaces 224 of
tissue contacting members 102, ablation member 210, suction
apertures 212 and sensors 214. Like tissue contacting members 102,
tissue contacting surfaces 224 may be given any configuration and
sizes to contact cardiac tissue in an area around the tissue to be
ablated. For example, in an embodiment as in FIG. 2 a tissue
contacting surface 224 on one tissue contacting member 102 may have
a length of approximately 1.25 in. and a width of approximately 0.5
in., with a space between the two tissue contacting surfaces
measuring approximately 0.4 in. Such exemplary dimensions are in no
way limiting, and all combinations of dimensions for one or more
tissue contacting members 102 are contemplated. In some
embodiments, as in FIG. 2, surfaces 224 may be flat and smooth. In
other embodiments, surfaces 224 are textured, curvilinear or
otherwise shaped to enhance contact of tissue contacting members
102 with heart 140. Some embodiments may further include one or
more surface features 222. Such features 222 may enhance friction
between tissue contacting surfaces 224 and epicardial tissue and/or
may provide an area for placement of additional features, such as
irrigation apertures for cooling tissue or the like.
[0093] Ablation member 210 may include one or more ablation members
for transmitting one or more of a variety of ablation agents to
epicardium or other cardiac tissue. In some embodiments, as
commonly shown in the drawing figures, ablation member 210 may
comprise a single, continuous, RF ablation coil or wire for
transmitting RF energy to cardiac tissue. In other embodiments,
ablation member 210 may be multiple radio frequency devices or one
or more cryogenic devices, ultrasound devices, laser devices,
thermo-electric chip devices, chemical agent delivery devices,
biological agent delivery devices, light-activated agent devices,
thermal devices, microwave devices, or ablating drug delivery
devices. Other suitable ablation devices are also contemplated
within the scope of the invention. Additionally, radio frequency
ablation members 210 may be bipolar or unipolar in various
embodiments. In conjunction with any of these various embodiments,
energy source 122 may provide any of the above-listed types of
ablative energy or substance, any combination thereof or any other
suitable ablative energy or substance.
[0094] Ablation member 210 may be given any configuration or size
for ablating cardiac tissue. In the embodiment shown in FIG. 2, for
example, ablation member 210 has two linear portions disposed along
most of the lengths of contacting surfaces 224 of tissue contacting
members 102, and the linear portions are continuous with a curved
portion 226 so that ablation member 210 is generally U-shaped.
Alternatively or additionally, ablation member 210 may continue
proximally from tissue contacting members 102 in one or more arms
230 which eventually connect to wire 110 or other connective
device. In some embodiments, curved portion 226 may be eliminated
so that ablation member 210 comprises two linear ablation members
connected to wire 110 via arms 230. In yet other embodiments, arms
230 may be eliminated and ablation member 210 may be coupled
directly to wire 110 without interposing arms.
[0095] Generally, ablation members 210 and tissue contacting member
102 may have any shapes, sizes, configurations or combinations of
shapes and sizes to produce a desired ablation pattern on
epicardial or other tissue of a heart. In some examples, ablation
members 210 and tissue contacting members 102 are configured to
partially or completely encircle or surround one pulmonary vein. In
other embodiments, they may be configured to partially or
completely surround two pulmonary veins on the same side of the
heart, such as the left superior and left inferior pulmonary veins.
In still other embodiments, the right and left inferior pulmonary
veins or the right and left superior pulmonary veins may be
partially or wholly encircled. And in still other embodiments, all
four pulmonary veins may be partially or completely encircled by
ablation members 210 and tissue contacting member 102. Some of
these embodiments are described in further detail below, but it
should be understood that any possible configuration is
contemplated within the scope of the present invention.
[0096] In some embodiments, all or a portion of ablation member 210
or tissue contacting member 102 may be steerable. Steerability
means that an ablation member 210 or tissue contacting member 102
may be adjusted to fit around or next to one or more pulmonary
veins or to otherwise assume a desired configuration. For example,
some embodiments may include a pull wire coupled with ablation
member 210 and/or tissue contacting member 102. The pull wire, when
pulled, deflects ablation member 210 and/or tissue contacting
member 102 to one side or around a curved structure. Other
embodiments may include pushable wires, combinations of flexible
and stiff portion and/or the like to provide steerability.
[0097] In some embodiments, for example, it is desirable to ablate
epicardial tissue in a circumferential pattern around one or more
pulmonary arteries. Various configurations of tissue contacting
members 102 and ablation members 210 are contemplated for achieving
such ablation patterns. For example, a retractable RF coil 240 or
other retractable ablation device may be incorporated into or used
in conjunction with ablation member 210 as shown in FIG. 2.
Retractable coil 240 could be housed within tissue contacting
member 102, for example, and could be released when desired to
surround or encircled one or two pulmonary veins. As already
described, the RF ablation member 210 and/or the RF retractable
coil 240 pictured in FIG. 2 may be replaced, in other embodiments,
with devices using radio frequency energy, ultrasound energy,
microwave energy, cryogenic energy, thermoelectric energy or laser
energy for ablating tissue. For example, ablation member 210 in
some embodiments comprises multiple thermoelectric chips disposed
in a pattern on tissue contacting members 102.
[0098] Although ablation device 100 and ablation member 210 are
often shown as being generally U-shaped, many other configurations
are possible. As described further below, a ablation device 100 may
be conical in shape, with ablation member 210 being disposed in a
circle at the base of the cone which contacts cardiac tissue. In
other embodiments, device 100 may be configured as a flat patch and
one or more linear or curvilinear ablation members 210 may be
incorporated into the patch. For example, ablation device 100 may
include a combination of multiple ablation members 210 to ablate a
pattern on heart 140 such as: a first linear ablation member for
contacting heart tissue between a left pulmonary vein and a right
pulmonary vein; a second linear ablation member for contacting
heart tissue at a location approximating a line extending to the
atrioventricular groove; and a third linear ablation member for
contacting heart tissue on a left atrial appendage. In such an
embodiments, one or more of ablation members 210 may overlap one
another. In some embodiments involving multiple ablation members
210, each member may be controllable on a separate radio frequency
channel or other energy transmission channel.
[0099] Tissue contacting members 102 optionally include one or more
attachment means for enhancing contact of ablation device 100 with
epicardial or other cardiac tissue. In some embodiments, one or
more suction apertures 212 are used. Each suction aperture 212
generally includes a depressed surface and a small suction hole.
The suction hole is connected to a lumen (not shown) within tissue
contacting member 102, and the lumen is then couplable with a
suction cannula 122 or connector 216 for connecting to cannula 122.
Suction apertures 212 may be given any suitable configuration, size
or pattern. For example, suction holes may be disposed on tissue
contacting member 102 is a largely linear pattern, as in FIG. 2. In
other embodiments, suction apertures may be arranged in two
parallel lines such that ablation member 210 is disposed between
the two parallel lines of suction apertures 212. In still another
embodiment, ablation device 100 may include one tissue contacting
member 102 having a conical shape, with the base of the cone
contacting epicardial tissue and the entire conical tissue
contacting member 102 acting as one suction aperture.
[0100] In some embodiments, suction force may be applied via
suction apertures 210 with sufficient strength to allow for
stabilization and/or positioning of heart 140. For example, a
physician may place ablation device 100 on a beating heart 140,
apply suction, and hold heart 140 is a relatively stable or
reduced-motion position while performing an ablation procedure. The
physician may also (or alternatively) turn or otherwise move heart
140, using ablation device 100, such as when a different angle of
heart 140 would be advantageous for viewing or treating a portion
of heart 140. In these or other embodiments, suction force applied
through suction apertures 212 may be of sufficient strength to
dissect through one or more layers of adipose tissue covering
epicardial tissue. Such dissection by suction apertures 212 may
allow for improved contact of the epicardial tissue by device and,
thus, improved ablation. In alternative embodiments, suction
apertures 212 may be replaced or supplemented by other means for
securing ablation device 100 to epicardial tissue. For example, an
adhesive may be applied to tissue contacting surfaces 224. Such
adhesives or other securing means may also be sufficiently strong,
in some embodiments, to allow for positioning and/or stabilization
of heart 140.
[0101] Referring to FIG. 2, tissue contacting members 102 may also
include one or more sensors 214 for judging the thickness of the
tissue or to determine the amount of therapy or energy that must be
delivered to the tissue, for sensing whether the ablation device
100 is properly positioned in contact with the tissue to be
ablated, and to monitor the progress of the ablation to recognize
when the tissue along a selected length of the ablation device 100
has received sufficient treatment and communicates with a means for
directing the ablation device 100 to discontinue or reduce
treatment at that site; in some embodiments, while continuing to
apply ablation energy at other locations along the length of the
ablation device 100. For these and other purposes, the sensors 214
may include one or more thermal sensors, electrical sensors,
thermoelectric sensors, microchips, thermistors, thermocouples,
Doppler sensors, microwave sensors, and ultrasonic sensors.
[0102] As shown in FIG. 2, some embodiments include two or more
paired sensors 214, with one sensor of each pair on one side of
ablation member 210 and the other sensor on the opposite side. In
some embodiments, one sensor 214 transmits a signal through
epicardial tissue to its paired sensor 214. If epicardial tissue
between the two paired sensors 214 has been ablated, then energy
will transmit poorly through that ablated tissue. Thus, the
receiving sensor 214 will receive reduced or no energy transmitted
from the transmitting sensor 214. If tissue between two paired
sensors has not been ablated, the signal should travel through the
tissue with only slight reduction in strength. By using such paired
sensors 214 and comparing signals received in different pairs,
areas of ablation can be compared, to determine if all desired
areas for ablation have been sufficiently ablated. Other
configurations one or more sensors 214 may also be used.
[0103] Referring now to FIG. 2a, another view of ablation device
100 as in FIG. 2 is shown, with ablation member 210 removed for
clarity. In some embodiments, tissue contacting members 102 include
a linear trough 250 in which ablation member 210 is placed, either
removably or permanently. Positioning ablation member 210 in trough
250 may provide improved contact between ablation member 210 and
epicardial tissue while also providing ablation device 100 with
durability. Surface features 222 are again shown in FIG. 2a. These
features may simply enhance contact of tissue contacting members
102 with epicardial tissue or may also contain additional features,
such as sensors, irrigation apertures for allowing passage of
irrigation fluid for cooling ablated tissue, small suction
apertures and/or the like.
[0104] Optionally, various embodiments of ablation device 100 may
further include at least one cooling member for cooling a portion
of ablated epicardial tissue, epicardial tissue surrounding an
ablated area, other nearby tissues and/or a portion of device 100.
Cooling members are not shown in the drawing figures, for purposes
of clarity. Generally, a cooling member may comprise any suitable
device for cooling a tissue. In some embodiments, cooling member
includes at least one inlet port, for allowing introduction of a
cooling substance into the member, a hollow internal cooling
member, and at least one outlet port for allowing egress of the
cooling substance. The cooling substance itself may be carbon
dioxide, any other suitable gas, saline or any other suitable
liquid. In some embodiments, the hollow cooling member comprises a
tubular member disposed within tissue contacting member 102 in
general proximity with ablation member 210. In other embodiments,
cooling member may comprise a chamber for containing cooling
substance or a series of irrigation holes for allowing cooling
substance to flow out of tissue contacting member 102 to contact
ablated or other epicardial tissue. Many other suitable cooling
apparatus are contemplated for use within the scope of the present
invention.
[0105] With reference now to FIG. 3, another embodiment of ablation
device 300 is shown from a bottom-side view. Ablation device 300
includes a tissue contacting member 302, coupled with an ablation
member 310 and a support member 304. As with some above-described
embodiments, tissue contacting member includes a tissue contacting
surface 324, tissue attaching means including multiple suction
apertures 312 and multiple artery securing arms 308. Tissue
contacting member 302 is removably couplable with a suction cannula
318 via a V-shaped suction connector 316. Ablation member 310 is
coupled with energy transmitting wire 314 for coupling with an
energy source (not shown). Support member 304 includes a support
arm 306 (shown partially in dotted lines, since it extends on the
opposite side of tissue contacting member 302) for coupling device
300 with a positioning device.
[0106] In ablation device 300, tissue contacting member 302,
ablation member 310 and support member 304 are all generally shaped
as a square with a central area 303 and a top area 305 left open.
Such a configuration may be used, for example, to contact and
ablate epicardial tissue almost completely encircling one or more
pulmonary veins. Leaving top area 305 open may allow device 300 to
be positioned around such veins or other vessels while still
providing almost circumferential ablation. In other embodiments,
either central area 303, top area 305 or both may be closed to
provide for different contact and/or ablation patterns on
epicardial tissue. In still other embodiments, one or more hinges
may be positioned on ablation device 300 to allow top area 305 to
be closed after positioning device 300 around one or two pulmonary
veins. Again, any configuration, shape, size, dimensions or the
like are contemplated within the scope of the invention.
[0107] Referring now to FIG. 4, another embodiment of ablation
device 400 comprises a largely flexible device which includes a
tissue contacting member 402 and an ablation member 410. Tissue
contacting member 402 may be made of any suitable, flexible
material, such as a silicone, polyurethane, polycarbonate, another
suitable polymer or combination of polymers or the like. Tissue
contacting member 402 generally includes a tissue contacting
surface 424 having multiple suction apertures 412. Tissue
contacting surface 424 may be slightly concave (as shown), flat or
may have any other suitable shape. Suction apertures 412 are
disposed in two parallel lines, one line on either side of ablation
member 410 and communicate with suction lumens 414 and 416. Suction
lumens 414, 416 may be coupled with one or more suction cannulas or
similar devices for providing suction force through suction
apertures 412. Other embodiments may include one common suction
lumen for connection to a suction cannula.
[0108] As with various embodiments described above, any suitable
ablation means may be used as ablation member 410 in device 400. In
the embodiment shown, ablation member 410 comprises a linear radio
frequency coil. Ablation member 410 may extend beyond the length of
tissue contacting member 402, either in a proximal or distal
direction and may be coupled with a source of energy via a wire
(not shown) or other connection device. In various embodiments, one
or more of the features described above, such as support members,
retractable ablation elements, sensors, cooling members,
positioning arms and/or the like may be incorporated into or used
with ablation device 400. Alternatively, ablation device 400 may
simply include tissue contacting member 402 and linear ablation
member 410. Such an embodiment may be advantageous for introduction
through a narrow, minimally invasive introducer sheath, due to the
device's flexibility and relatively small size. In one embodiment,
for example, device 400 may measure approximately 3.25 in. in
length and approximately 0.9 in. wide and may further be deformable
to a narrower configuration for insertion through a sheath.
Furthermore, device 400 may be sufficiently flexible to conform to
curved surfaces of heart 140, allowing for enhanced contact with
and ablation of epicardial tissue. Finally, it may sometimes be
advantageous to ablate epicardial tissue in a linear pattern or in
multiple line. Ablation device 400 may be movable, to allow
ablation in a first line, a second line, a third line and/or the
like.
[0109] Referring now to FIG. 4a, a bottom-side view of ablation
device 400 is shown with ablation member removed. It can be seen
that tissue contacting member 402 may include a trough 420 in which
ablation member 410 may be positioned. In some embodiments,
ablation member 410 may be a removable piece which may be removably
attached to tissue contacting member 402, at least partially
disposed within trough 420, so that one ablation member 410 may be
used with multiple tissue contacting members 402, one after
another, for example if tissue contacting members 402 are
single-use, disposable devices.
[0110] In some apparatus and methods of the invention, once the
tissue contact member is positioned and suctioned on to the heart,
the ablation device 400 may also be slid within the trough 420 in
the tissue contact member 402 so that the energy emitting section
of the ablation member 410 may be positioned as a separate step
from the step of positioning the tissue contacting member 402. It
is also possible to position the tissue contacting member 402
separately from the ablation member 410, then in a later step,
slide the ablation member 410 into the tissue contact member 401.
In some embodiments, an ablation member 410 with a short energy
emitting section may be moved along a trough 420 in the tissue
contact member 401 so that the ablation device 400 can create long
lesions, perhaps longer than the ablation section of the ablation
member 410, with minimal manipulations of the device within the
track.
[0111] Using a single placement of the tissue contacting member may
enhance continuity of ablation lesions. Not having to move the
ablation device between discrete ablation cycles, and instead only
moving the ablation member within the tissue contacting member,
insures that adjacent ablation segments are contiguous with no
ablation gaps. Avoiding the creation of gaps can be critical to
insure electrical isolation of desired tissue areas, and may also
decrease procedure time by not requiring the surgeon to verify
overlap of adjacent ablation lesions
[0112] FIG. 5 shows yet another embodiment of ablation device 500,
including a tissue contacting member without an ablation member
being shown. Device 500 is similar to ablation device 400, but
tissue contacting member 502 has one row of suction apertures 512
rather than two and ablation member, placed in ablation trough 520,
overlays suction apertures 512. Suction holes 522 shown in suction
apertures 512 demonstrate that the apertures sometimes include both
a depressed or concave surface and one or more holes communicating
with a suction lumen. The embodiment of ablation device 500 in FIG.
5 may be advantageous for forming one or more linear ablations on
heart 140 when there is minimal space in which to manipulate device
500 and/or when a narrow, minimally invasive incision or sheath is
desired for insertion of device 500. Device 500 may be manufactured
from any suitable material or combination of materials, such as
those described above, may use any suitable form of ablation member
and may include various additional features as desired.
[0113] FIG. 5a is a bottom perspective view of an alternate another
embodiment suction pods 524 spaced some distance apart and joined
by a flexible joining members 526, which may also be used to
provide a channel for a vacuum lumen. The distance between the
suction pods 524 and the flexibility of the joining members 526
between the suction pods 524 has been found to increase the ability
of the tissue contacting member 502 to bend in sharp turns. In
FIGS. 5a and 5b, the joining members 526 are cylindrical in cross
section, which may improve the overall flexibility of the ablation
device 500 in all directions. The flexibility can be varied as
desired by changing the thickness, shape, and size of the joining
members 526 between the suction pods 524, and by varying the
flexibility of the material used to fabricate the joining members
526. For example, FIGS. 5c and 5d show example alternate joining
member 526 cross sections. The square cross section of FIG. 5c may
allow bending in X and Y axes, but may resist axial rotation. The
example cross section shown in FIG. 5d may allow bending in a
downward vertical direction, but may resist bending in lateral
directions. FIG. 5E shows an ablation member 528 including ablation
segments 530 configured for insertion of tissue contacting member
502.
[0114] Referring now to FIG. 6, ablation device as described with
reference to FIGS. 4 and 4a is shown in position for performing
epicardial ablation on a human heart 140. Generally, ablation
device 400 may be placed in any desired position on heart 140 for
ablating epicardial tissue. Thus, in various embodiments device may
be placed adjacent one or both of the right pulmonary veins 142,
144, adjacent one or both of the left pulmonary veins 148, 150, or
in any other suitable location. Furthermore, ablation device 400
may be used to ablate tissue in a linear pattern at one location
and then may be moved to ablated tissue in a linear pattern in
another location. As discussed above with reference to various
embodiments, ablation device 400 may be introduced into a patient
via a minimally invasive device, such as a sheath 630 or trocar,
and may be coupled with a source of suction 120 via a suction
cannula 112 and with a source of ablative energy 122 via a wire 110
or other connective device.
[0115] Ablative device 400, as well as other embodiments of
ablative devices described above, may be positioned on heart 140
via a positioning device 602 which is introduced via a second
minimally invasive incision or second sheath 620. Second sheath 620
may be placed at any suitable location on the patient to allow
access to ablation device with the positioning device 602.
Positioning device 602 may then be introduced through sheath and
advanced to the position of ablation device 400. Positioning device
602 may then be used to secure device 400, such as by opposable
jaws 610 or any other suitable means, and position device 400 in a
desired location on heart 140. In some embodiments, positioning
device may further be used to reposition device 400 to perform
ablation in multiple locations on heart 140. The proximal end of
positioning device 602 may include a handle 604 for holding and
manipulating device 602 and one or more actuators 606, such as a
trigger for opening and closing opposable jaws 610 or other
distally positioned end effectors of device 602. Examples of
positioning device 602 may include, but are not limited to,
conventional minimally invasive surgical devices such as
laproscopic surgical devices and the like.
[0116] Referring now to FIG. 7, another embodiment of ablation
device 700 suitably includes at least one elongate shaft 702 having
a proximal end 724 and a distal end 726, a jaw member 704 coupled
with shaft 702 near distal end 726, at least one ablation member
712, 714 coupled with jaw member 704, and a handle 706 and at least
one actuator 708, 710 near the proximal end 724 for manipulating
device 700, opening and closing the jaw member, activating ablation
member 712, 714 and the like. Device 700 is generally configured to
be introduced through a minimally invasive sheath, trocar or
incision, though it may also be used in open surgical procedures.
Shaft 702 may be made of any suitable material, such as metal,
ceramic, polymers or any combination thereof, and may be rigid
along its entire length or rigid in parts and flexible in one or
more parts. In various embodiments, the shaft may be malleable, may
articulate about at least one joint and/or may be steerable for
positioning the device. In some embodiments, the ablation member is
coupled with a portion of the shaft.
[0117] Jaw member 704 may be disposed on or near distal end 726 of
shaft 702 and is generally configured to open and close to grasp
epicardial or other tissue between the opposing jaws. For example,
jaw member 704 may be coupled with shaft 702 at a hinge point 730
to allow for such opening and closing motion. An ablation member is
coupled with at least part of jaw member 704. As with the
above-described embodiments, the ablation member may use any
suitable energy source for ablating tissue. In some embodiments,
multiple ablation members 712, 714 may be used. For example, one
electrode 712 of a bipolar ablation member may be coupled with one
opposing jaw and another electrode 714 may be coupled with the
other opposing jaw. Alternatively, ablation members 712, 714 may
include one unipolar ablation device or any of the ablation devices
described with reference to various embodiments above. The jaw
member and/or the ablation member may be shaped to contact and
ablate the epicardial tissue in a pattern such as, but not limited
to, a U-shaped pattern, an L-shaped pattern, a circular pattern or
a linear pattern. Actuators 708, 710 may have one or more various
functions, such as opening and closing jaw member 704, activating
ablation members 712, 714, changing an angle of orientation of jaw
member 704, straightening or bending jaw member 704 and/or the
like. One actuator 710, for example, may comprise a trigger-like
actuator while another actuator 708 may comprise a turnable
dial.
[0118] Generally, jaw member 704 may have any suitable
configuration for contacting a surface of a heart, for grasping
epicardial or other tissue to be ablated and/or for placing
ablation members 712, 714 in contact with tissue to be ablated. As
such, jaw members 714 may be straight, curved, bent or otherwise
configured for contacting, grasping and/or ablating tissue. In some
embodiments, jaw member 704 may be adjustable via an actuator 708,
710, so as to allow their shapes to be bent, straightened or the
like during a procedure. With reference to FIG. 7a, one embodiment
of a straight jaw member 718 may allow jaw member 718 to be
retracted within shaft (arrows). Retraction may help protect a
patient as well as jaw member during insertion and advancement of
the device within the patient. Again, ablation members 720, 722 on
such straight jaw members 718 may be bipolar RF members, unipolar
RF members or any other suitable ablation devices.
[0119] Optionally, the device may further include an insulation
member at least partially surrounding the device to protect body
structures in the vicinity of the epicardial tissue to be ablated
from damage due to heat or electrical current. Also optionally, the
ablation member may be adjustable to deliver two or more varying
amounts of ablative energy to two or more locations on the
epicardial tissue. Various embodiments may further include at least
one sensor for sensing a quantity of ablation provided by the
ablation member to the tissue.
[0120] FIG. 8 shows ablation device 700, as just described, in a
position for performing an ablation procedure on epicardial tissue
of heart 140. Device as shown will ablate in a pattern
approximating two lines adjacent the right pulmonary veins 142,
144. It should be understood, from the foregoing descriptions of
various embodiments, that jaw member 704 and ablation members 712,
714 could alternatively be configured in any other suitable shape,
size or configuration to ablate in other patterns on heart 140.
Additionally, device 700 may be moved to a variety of positions to
ablate multiple patterns in multiple locations on the epicardial
tissue.
[0121] With reference now to FIG. 9, a method for ablating cardiac
tissue, such as epicardial tissue, suitably includes contacting
cardiac tissue with an ablation device 910, securing the device to
the tissue 920 and ablating at least a portion of the contacted,
secured tissue 930. Various embodiments of the invention will
utilize additional steps or sub-steps of these three basic steps,
but it should be emphasized that any additional steps or variations
are optional. For example, in some embodiments, contacting the
cardiac tissue 910 is preceded by advancing the device into the
patient through a minimally invasive introducer device. Contacting
the device with the tissue 910 may include positioning the device
using a positioning arm or other positioning device. In some
embodiments, securing the device to the tissue 920 may also
comprise invaginating a portion of epicardial tissue partially
within one or more suction apertures and/or may include using one
or more suction apertures to dissect through fatty tissue disposed
over epicardium. Securing the device 920 may also involve securing
with enough force to allow stabilization and/or positioning of the
heart itself. And ablation of epicardial tissue 930 may involve
ablation in any location or pattern as described above with
reference to the inventive devices. Therefore, the descriptions of
various methods provided herein are offered for exemplary purposes
only and should not be interpreted to limit the scope of the
invention as described in the claims.
[0122] Other aspects of a method for ablating epicardial tissue may
include imaging the epicardial tissue and an area surrounding the
tissue to be ablated, using a visualization device. Such a device
may be coupled with the ablation device or may be a separate
imaging device. In some embodiments, an insufflation device may be
inserted between the epicardium and the pericardium and
insufflation fluid or gas may be introduced to form a space between
the epicardium and pericardium. The space may be used to enhance
visualization, allow for freer manipulation of devices near the
site for ablation and the like. Another aspect may include sensing
ablation of epicardial tissue with one or more sensors, as
described above. In some embodiments, tissue may optionally be
cooled via a cooling member and/or irrigation of fluid into contact
with the tissue. Finally, the actual ablation of epicardial tissue
may be accomplished with any suitable ablation member and form of
energy, including RF, thermoelectric, cryogenic, microwave, laser,
ultrasound or the like. In one embodiment, ablation is achieved
and/or enhanced by delivery of one or more drugs to the tissue.
[0123] The method may further include the steps of using visual and
audible cues to verify the ablation device is adhered to tissue.
For example the user can hear a suction sound or `whistle` when the
suction has been activated and the ablation device is not correctly
adhered. Also, the user can hear vacuum pump elevate as vacuum
increases. In some embodiments, the user can visually observe the
tissue contacting member collapse when the ablation device is
correctly adhered and suction is activated.
[0124] In general, any number of suction pods may be used in the
invention, and the number used may depend on the procedure that is
to be performed. For example, FIG. 10 shows an embodiment of the
ablation device 500 including a tissue contact member 534 with only
a single elongated suction pod 530. In this embodiment, the suction
pod 530 extends a selected length of the ablation member 536 and
includes graspers 532 to hold the ablation member 536 within the
suction pod 530. Any desired mechanism for holding the ablation
member 536 may be used. For example, the graspers 532 may be narrow
channel sections in which the ablation member 536 may be snapped
into place, or the graspers 532 may be loops through which the
ablation member 536 is slid into place.
[0125] In further embodiments, the ablation device may be
configured to allow the ablation member to extend beyond the edge
of the tissue contacting member to allow for ablation to occur
outside of the region covered by the tissue contacting member.
[0126] Referring to FIG. 11, an ablation system 800 built in accord
with the invention is shown including an ablation energy source 802
for providing power to the ablation device 804. The ablation energy
source 802 shown is an RF energy source particularly suited for use
with ablation apparatus as described herein, but is not limited to
such use. Other kinds of ablation energy sources and ablation
devices may be useable in the invention.
[0127] In some embodiments, the ablation system 802 is configured
to recognize the kind of ablation device connected by including
keyed plugs. Thus, in this embodiment, the energy source 802
includes sockets 808 configured with specialized shapes to accept
only plugs which are manufactured with the matching shape. The
Energy source 802 is configured with predetermined settings
appropriate for the kind of device that is accepted by that socket
shape. More than one socket 808 and associated pre-determined
setting may be included. Ablation devices 804 to be used with the
energy source will be provided with a plug shape (for example plug
806 on ablation device 804) to be received in on of the sockets 808
that will provide the appropriate energy requirements.
[0128] In another embodiment, the ablation system of the invention
includes apparatus for recognizing the kind of device that has been
coupled to the energy source and for automatically adjusting
various settings to accommodate the detected device. Examples
include but are not limited to known logic chip device recognition
systems and RFID systems. This embodiments can be used in
combination with keyed plugs as described above.
[0129] In another embodiment, the ablation system will provide
information useful to the treating physician and/or other medical
personnel, about the progress of treatment and the status of the
equipment. For example, the system may include a feedback loop to
self monitor the energy delivery of the system and automatically
turn off the delivery of energy once the treatment is complete. The
feedback mechanism may include electrical sensors, thermoelectric
sensors, microchips, thermistors, thermocouples, Doppler sensors,
microwave sensors, and ultrasonic sensors, or thermal energy
emitting and receiving devices. In some embodiments, the treatment
progress is monitored and indicated with a visual display such as
example visual displays 810 and 812. In these embodiments the
sensors may be in communication with processors or other control
devices included in the energy source, which can analyze and
display the data received from the sensors.
[0130] In still further embodiments, the ablation device may
include more electrodes that are available on the energy source.
This allows ablation device construction to facilitate longer
ablations by utilizing multiple connections to energy source. For
example,
[0131] In one embodiment, the ablation device includes a plurality
of electrodes, and the energy source includes less electrodes than
the ablation device. In this case, the ablation device preferably
includes at least two plugs, with each plug providing power to a
subset of the plurality of electrodes on the ablation device. By
connecting the first plug of the ablation device to the energy
source, applying ablation energy to the tissue, unplugging the
first plug from the energy source, plugging the second plug of the
ablation device in to the energy source, and applying ablation
energy to the tissue, all of the ablation elements can be
activated. More specifically, if an energy source includes seven
electrodes couple to a single plug to power seven ablation segments
on the ablation device, the ablation device may include fourteen
separate ablation segments. Each set of seven ablation segments
would couple to a separate plug. In use, the first plug is inserted
into the energy source and the first set of seven ablation segments
is activated. Upon completion of treatment, possibly without moving
the ablation device, a second region may be ablated by removing the
first plug and inserting the second plug to activate the next seven
ablation segments on the ablation device. This embodiment can
result in a smaller less expensive energy source that is still
capable of powering a long ablation device.
[0132] In one embodiment, a method first includes advancing an
ablation device through a minimally invasive introducer device into
a patient and to a location for ablating epicardial tissue. The
device is then contacted with the epicardial tissue and positioned
on the tissue with a positioning arm or other device inserted
through the same or a separate minimally invasive introducer or
incision. Positioning device, in some embodiments, may be a
flexible, rigidifying positioner which allows for positioning and
then stabilizing with the same device. The ablation device may be
placed in any suitable location for ablating epicardial tissue. In
one embodiment, for example, ablation device will contact tissue at
least partially encircling two pulmonary veins, such as the right
superior and right inferior pulmonary veins. The ablation device
may contact epicardial tissue directly adjacent the bases of the
veins but may be configured to maintain a safe distance between the
ablation member on the device and the actual veins.
[0133] Once the epicardial tissue is contacted, the device may be
secured to the tissue by securing means, such as suction or
adhesive. In fact, the device may be secured to the tissue
sufficiently in some embodiments to allow the heart to be
stabilized and/or positioned using the device and a positioner. For
example, a beating heart may be stabilized to reduce or eliminate
motion during an ablation procedure or may be pulled, turned or
otherwise moved into an advantageous position for ablating,
visualizing or treating the heart. Suction force may also be
supplied in sufficient strength to dissect through a layer of
adipose tissue overlying the epicardial tissue, which may provide
improved contact of an ablation member with the epicardial tissue.
Once the tissue is secured, at least a portion of the tissue may be
ablated by delivering energy to an ablation member (or members) on
the device. As already described in detail, such energy may include
any suitable energy and may additionally or alternatively include
one or more ablative drugs. After ablation, tissue may be cooled
via cooling means and/or ablation of tissue may be sensed with one
or more sensors. When an ablative procedure is complete, the device
may be removed and placed in another location on the heart for an
additional procedure or may be removed from the patient
altogether.
[0134] Another apparatus and method of the invention includes the
following. Referring to FIGS. 12a and 12b. In some embodiments, the
ablation device 814 may be deployed using an introducer 816 (best
seen in FIG. 12b). The introducer 816 in this embodiment comprises
a tube 818 that is pre-bent into a J shape. An obturator 820 with a
handle 822 and a shaft 828 which is inserted in to the tube 818
with the shaft 828 extending substantially through the length of
the tube 818. When the obturator 820 is removed, the tube 818
returns to its pre-bent J shape.
[0135] A distal end 824 of introducer 816 has a designate region
for grasping. A selected instrument may be introduced through a the
same or a second incision to grasp the distal end 824 of the
introducer 816 to pull the distal end 824 of the introducer 816
outside the body of the patient. The distal end 826 of the ablation
device 814 of FIG. 12a is attached to the proximal end 830 of the
introducer 816. The introducer 816 is then withdrawn until the
ablation device 814 is properly positioned.
[0136] In the example embodiment of the ablation device 814 seen in
FIG. 12a, the ablation device 814 includes a tissue contacting
member 832 including a single suction pod 834. An ablation member
836 extends through the length of the tissue contacting member 832
and includes graspers 838 to hold the ablation member 836 within
the suction pod 832. Once the treatment is complete, the ablation
device 814 may be decoupled from the energy source and pulled
out.
[0137] An example method for using the invention described above
includes the following steps. An introducer is advanced through a
first incision into the transverse sinus cavity with obturator
fully inserted. At desired area near the pulmonary veins, obturator
is withdrawn and the which allows the introducer to assume its
pre-formed J shape reaching round the pulmonary veins, possibly
also guided by contact with the pericardium. The introducer is
preferably long enough to be inserted from thoracotomy into
transverse sinus cavity around the pulmonary veins and out through
the oblique sinus and out through the same or a different
thoracotomy. Another instrument is advanced through the same or
different thoracotomy to grasp the distal end of the introducer.
The introducer is pulled around the pulmonary veins until the
distal end is outside the body of the patient. At this point, both
the proximal and distal ends of the introducer are preferably
outside the body of the patient.
[0138] The proximal end of introducer is attached, possibly with
luer fitting, to the distal end of an ablation device. Indication
markers and lines on introducer and on the ablation device can be
used to assist the user in properly positioning the ablation
device. In a preferred embodiment, circumferential indication
markers on the introducer are used as depth measurements, and an
indication stripe on the surface of the introducer are aligned with
similar markings on the ablation device to insure that the ablation
device will be facing properly when inserted.
[0139] In this method, the introducer preferably has torsional
rigidity to facilitate steerability. Further, the introducer is
preferably a highly visible color for endoscopic visualization and
distinguishing from natural anatomical colors.
[0140] Once the ablation device is in position, suction is applied
to adhere the ablation device to the tissue surrounding the
pulmonary veins. Ablation energy is applied. Once treatment is
complete, the ablation device can be removed.
[0141] Another method of the invention includes a method of
performing a `hybrid` medical procedure comprising creating a
continuous lesion encircling or partially encircling the pulmonary
veins to electrically isolate the pulmonary veins during a surgical
procedure and creating additional ablation lesions in the left
and/or right atrium, vena cava, endocardium to the mitral valve
annulus, or along the left atrial appendage to create a Maze-like
lesion set for treatment of atrial fibrillation.
[0142] FIG. 13 is an assembly drawing of an ablation device 840
that is configured to be used through an introducer or trocar
cannula 842. FIG. 14 is an exploded view showing the components of
the ablation device 840 of FIG. 13. A thoracic access port is
created between the ribs for insertion of the ablation device 840.
An introducer or trocar cannula 842 is placed through the thoracic
access port. The ablation device 840 includes two elongate flexible
polymeric clamp jaws 844, 846. The outer surfaces of the clamp jaws
844, 846 are rounded. The inner surfaces of the clamp jaws 844, 846
are flat with an ablation electrode 848, 850 on each of the clamp
jaws 844, 846. Preferably, the ablation electrodes 848, 850 are
embedded within the flat inner faces near the distal ends of the
clamp jaws 844, 846. The ablation electrodes 848, 850 may be
configured as simple wires embedded in the flat inner faces of the
clamp jaws 844, 846. Alternatively, each of the ablation electrodes
848, 850 may be configured with at least one, and up to about ten,
electrode segments. For flexibility, the electrode segments are
preferably configured as helically cut cylinders of metal
hypodermic tubing or the like embedded in the flat inner faces of
the clamp jaws 844, 846. The use of a flexible or deformable
conductive material in the ablation electrodes 848, 850 provides
evenly distributed contact pressure and lesion depth over a
variable thickness portion of tissue. Optionally, a mesh coating
covers the electrode segments to prevent contact of the ground and
active electrode segments if tissue is not between them. The coils
are typically dipped in saline before use to insure conductivity.
Optionally, the electrode segments may be individually addressable
as in some of the embodiments described above. A connection wire
858, 860 extends from each of the ablation electrodes 848, 850 to
the proximal end of the clamp jaws 844, 846 to allow connection to
an ablation power source. As the clamp jaws 844, 846 are advanced
distally though the introducer or trocar cannula 842, they open up,
with the ablation electrodes 848, 850 on the flat inner faces
separating, the faces being maintained parallel, and separation
distance up to 5 cm. As the clamp jaws 844, 846 are retracted
proximally through the port, the introducer or trocar cannula 842
exerts forces on the outer faces of the clamp jaws 844, 846 causing
them to close around the tissue. Preferably, the clamp jaws 844,
846 are configured to close around the tissue with the ablation
electrodes 848, 850 and the flat inner faces in parallel alignment.
Alternatively, the clamp jaws 844, 846 can be configured so that
the distal ends close around the tissue first, to prevent the
tissue from being squeezed out from between the clamp jaws 844, 846
as they close. Optionally, one or both of the clamp jaws 844, 846
may include a tooth or other grasping feature near the distal end
to prevent the tissue from being squeezed out from between the
clamp jaws 844, 846 as they close. The length of jaws may be up to
60 cm or more to facilitate remote insertion.
[0143] Optionally, one or both of the clamp jaws 844, 846 could be
malleable or include a malleable member to allow reconfiguring of
the clamp jaws 844, 846 for accessing a desired target tissue. The
malleable portion may extend the full length of the clamp jaws 844,
846 or it may be limited to a proximal, distal or intermediate
portion of the clamp jaws 844, 846. Alternatively or in addition,
one or both of the clamp jaws 844, 846 could also have one or more
hinge joints or articulating links to facilitate optimal
positioning of the ablation device. For example, a remotely
steerable hinge joint may be located on each of the clamp jaws 844,
846 just proximal to the ablation electrodes 848, 850 to facilitate
accessing a desired target tissue, while maintaining the ablation
electrodes 848, 850 in an approximately parallel alignment. In
alternate configurations, the clamp jaws 844, 846 may be joined
together, e.g. hinged or molded as one piece in a V-shaped or
Y-shaped configuration. Alternatively or in addition, the clamp
jaws 844, 846 may be curved to cause the inner surfaces with the
ablation electrodes 848, 850 to separate as the clamp jaws 844, 846
advance distally trough the introducer or trocar cannula 842.
Preferably, the clamp jaws 844, 846 will have a central lumen 852,
854 to facilitate a guidewire 856 that can be steerable going out
of one jaw and into another. This could act to lasso a tissue
structure to be brought into the clamp jaws 844, 846.
[0144] Preferably, the ablation electrodes 848, 850 on the clamp
jaws 844, 846 are configured for bipolar ablation. When applying
ablation energy through the ablation electrodes 848, 850, one
electrode may act as an active electrode, while the other acts as a
passive ground. Alternatively, the ablation electrodes 848, 850 may
both act as active electrodes by applying opposite voltages or
polarity of alternating (e.g. radio frequency) current to the two
ablation electrodes 848, 850. Typically, another ground electrode
will be applied to an external surface of the patient for
safety.
[0145] The apparatus can be used to create any lesion, with one jaw
endocardial and the other epicardial. In a preferred method, the
apparatus is used with both jaws positioned epicardially to isolate
one or more electrical focii (pulmonary veins) or peninsula-like
tissue structure (such as the left or right atrial appendage). The
apparatus can be used to create one or more lesions along the
atrial base of the pulmonary veins, thereby electrically isolating
the pulmonary veins from the left atrium.
[0146] As described above, thermal imaging can be used to visualize
the energy emission during an ablation procedure using any of the
ablation devices described herein. In addition, thermal imaging can
be used as a development tool for ablation probes. Thermal images
of the ablation procedure in vitro or in vivo allow optimization of
the device geometry and energy settings. For example, thermal
imaging has been used to optimize energy settings of ablation
devices in an epicardial beating heart heat sink model. The energy
settings thus established were subsequently used in vivo to achieve
the desired depth of heat penetration in tissue during actual
ablation procedures.
[0147] While the present invention has been shown and described
with reference to various embodiment thereof, the above and other
changes in form and detail may be made without departing from the
spirit and scope of the invention as defined in the following
claims.
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