U.S. patent application number 14/161811 was filed with the patent office on 2014-06-19 for user interface for tissue ablation system.
This patent application is currently assigned to Medtronic Ablation Frontiers LLC. The applicant listed for this patent is Medtronic Ablation Frontiers LLC. Invention is credited to J. Christopher FLAHERTY, Fred MORADY, Hakan ORAL, Ricardo David ROMAN, Marshall L. SHERMAN, Randell L. WERNETH.
Application Number | 20140171942 14/161811 |
Document ID | / |
Family ID | 37772344 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140171942 |
Kind Code |
A1 |
WERNETH; Randell L. ; et
al. |
June 19, 2014 |
USER INTERFACE FOR TISSUE ABLATION SYSTEM
Abstract
Devices, systems and methods are disclosed for the ablation of
tissue. Embodiments include an ablation catheter that has an array
of ablation elements attached to a deployable carrier assembly. The
carrier assembly can be constrained within the lumen of a catheter,
and deployed to take on an expanded condition. The carrier assembly
includes multiple electrodes that are configured to ablate tissue
at low power. Systems include an interface unit with a visual
display that provides a visual representation of the geometry of
the ablation elements and/or provides selection means for selecting
an icon provided on the display.
Inventors: |
WERNETH; Randell L.; (San
Diego, CA) ; FLAHERTY; J. Christopher; (Topsfield,
MA) ; ORAL; Hakan; (Ann Arbor, MI) ; MORADY;
Fred; (Ann Arbor, MI) ; ROMAN; Ricardo David;
(San Diego, CA) ; SHERMAN; Marshall L.; (Cardiff
By The Sea, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic Ablation Frontiers LLC |
Minneapolis |
MN |
US |
|
|
Assignee: |
Medtronic Ablation Frontiers
LLC
Minneapolis
MN
|
Family ID: |
37772344 |
Appl. No.: |
14/161811 |
Filed: |
January 23, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11438678 |
May 22, 2006 |
8657814 |
|
|
14161811 |
|
|
|
|
60710451 |
Aug 22, 2005 |
|
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Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 5/7217 20130101;
A61B 2018/00642 20130101; A61B 5/0422 20130101; A61B 2018/00351
20130101; A61B 2018/00654 20130101; A61B 2018/00791 20130101; A61B
2018/00779 20130101; A61B 18/02 20130101; A61B 2018/124 20130101;
A61B 90/37 20160201; A61B 5/7435 20130101; A61B 2018/00797
20130101; A61B 2018/00577 20130101; A61B 2018/00839 20130101; A61B
5/7445 20130101; A61B 5/742 20130101; A61B 2018/00821 20130101;
A61B 2018/00214 20130101; A61B 18/1492 20130101; A61B 2018/00702
20130101; A61B 2018/00982 20130101; A61B 2018/0016 20130101 |
Class at
Publication: |
606/41 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1. An ablation system, the ablation system comprising: an ablation
catheter including a plurality of electrodes; and an interface unit
in communication with the ablation catheter, the interface
including a visual display, the visual display showing a geometric
configuration of the plurality electrodes and at least one
information icon proximate each of the plurality of electrodes.
2. The system of claim 1, wherein the at least one information icon
is selected from the group consisting of: electrical signal from at
least one of the plurality of electrodes, current quantitative
representation of a system parameter, a system parameter target
value, selected energy mode, temperature, rate of temperature
change, energy transmission status of at least one of the plurality
of electrodes, energy delivery value, distance, force, pressure,
location, and combinations thereof.
3. The system of claim 2, wherein the visual display is a first
visual display, the interface unit further including a second
visual display.
4. The system of claim 3, wherein the geometric configuration of
the plurality of electrodes is a first geometric configuration of
the plurality of electrodes, the second visual display showing a
second geometric configuration of the plurality of electrodes and
at least one information icon proximate each of the plurality of
electrodes.
5. The system of claim 4, wherein the at least one information icon
is selected from the group consisting of: electrical signal from at
least one of the plurality of electrodes, current quantitative
representation of a system parameter, a system parameter target
value, selected energy mode, temperature, rate of temperature
change, energy transmission status of at least one of the plurality
of electrodes, energy delivery value, distance, force, pressure,
location, and combinations thereof.
6. The system of claim 2, wherein the system parameter is selected
from the group consisting of: an energy delivery parameter selected
from the group consisting of: current, voltage, frequency, power,
monopolar mode or bipolar mode, duration, impedance, and type of
energy to be delivered; a sensor parameter selected from the group
consisting of: tissue contact measurement value, temperature,
pressure, strain, impedance, ECG or EKG, cardiac flow rate, tissue
thickness, and tissue location an alarm parameter; a physical
catheter parameter; and a threshold value for a system
parameter.
7. The system of claim 1, wherein the ablation catheter further
includes: a plurality of flexible ablation elements, at least one
of the plurality of electrodes located on each of the plurality of
ablation elements; a flexible, tubular body member having a
proximal end, a distal end, and a lumen extending therebetween; and
a control shaft receivable within the lumen of the tubular body
member, the control shaft being configured to retract at least one
of the plurality of ablation elements within the lumen of the
tubular body member and being configured to extend at least one of
the plurality of ablation elements beyond the distal end of the
tubular body member.
8. The system of claim 3, wherein the ablation catheter further
includes at least one sensor.
9. The system of claim 8, wherein the at least one sensor is
located on at least one of the plurality of ablation elements.
10. The system of claim 9, wherein a geometric configuration of the
at least one sensor is shown on at least one of the first visual
display and the second visual display.
11. The system of claim 6, wherein the visual display indicates a
system parameter, the interface unit being configured to change a
value of a system parameter.
12. The system of claim 6, wherein the visual display indicates
changes in the value of a system parameter.
13. The system of claim 3, wherein at least one of the first visual
display and the second visual display show a visual representation
of at least a portion of a patient's anatomy.
14. The system of claim 1, wherein each of the plurality of
electrodes is configured to read at least one of ECG and EKG
information, and configured to transmit energy to tissue in a
monopolar mode, a bipolar mode, and a combination monopolar-bipolar
mode.
15. The system of claim 14, wherein at least one of the plurality
of electrodes defines a triangular cross section.
16. The system of claim 2, wherein the system further comprises an
audio transducer in communication with the interface unit, the
audio transducer being configured to indicate an event selected
from the group consisting of a change in a system parameter and the
system parameter exceeding a threshold value.
17. The system of claim 1, wherein the user interface is
programmable to modifying the operation of at least one of the
plurality of electrodes.
18. The system of claim 1, wherein the user interface is
programmable to selectively deliver energy to one or more of the
plurality of electrodes.
19. An ablation system, the system comprising: an ablation catheter
including a plurality of carrier arms, each carrier arm including
at least one electrode; an interface unit in communication with the
ablation catheter, the interface including a first visual display
and a second visual display, each of the first and second visual
displays showing a geometric configuration of the plurality
electrodes and at least one information icon proximate each of the
plurality of electrodes.
20. A method for selecting electrodes for energy delivery, the
method comprising: displaying a visual display of an interface unit
configured to accept a manual selection of one or more carrier arms
of an ablation catheter for energy delivery; automatically
selecting one or more electrodes in communication with the selected
one or more carrier arms; displaying on the visual display an
option for the manual confirmation of the automatically selected
one or more carrier arms; and automatically determining ablation
parameters and automatically activating the one or more electrodes
when the automatic selection of one or more electrodes is manually
confirmed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of, and claims priority
to, patent application Ser. No. 11/438,678, filed May 22, 2006,
entitled USER INTERFACE FOR TISSUE ABLATION SYSTEM, and also claims
priority to U.S. Provisional Patent Application Ser. No.
60/710,451, filed Aug. 22, 2005, entitled USER INTERFACE FOR TISSUE
ABLATION SYSTEM, the entirety of all of which are incorporated
herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] N/a
FIELD OF THE INVENTION
[0003] The present invention relates generally to systems,
catheters and methods for performing targeted tissue ablation in a
subject. In particular, the present invention provides catheters
comprising two or more ablation elements configured to precisely
and efficiently deliver energy to tissue, and a sophisticated user
interface that allows simplified use of the multi ablation element
catheters.
BACKGROUND OF THE INVENTION
[0004] Tissue ablation is used in numerous medical procedures to
treat a patient. Ablation can be performed to remove undesired
tissue such as cancer cells. Ablation procedures may also involve
the modification of the tissue without removal, such as to stop
electrical propagation through the tissue in patients with an
arrhythmia. Often the ablation is performed by passing energy, such
as electrical energy, through one or more electrodes causing the
tissue in contact with the electrodes to heat up to an ablative
temperature. Ablation procedures can be performed on patients with
atrial fibrillation by ablating tissue in the heart.
[0005] Mammalian organ function typically occurs through the
transmission of electrical impulses from one tissue to another. A
disturbance of such electrical transmission may lead to organ
malfunction. One particular area where electrical impulse
transmission is critical for proper organ function is in the heart.
Normal sinus rhythm of the heart begins with the sinus node
generating an electrical impulse that is propagated uniformly
across the right and left atria to the atrioventricular node.
Atrial contraction leads to the pumping of blood into the
ventricles in a manner synchronous with the pulse.
[0006] Atrial fibrillation refers to a type of cardiac arrhythmia
where there is disorganized electrical conduction in the atria
causing rapid uncoordinated contractions that result in ineffective
pumping of blood into the ventricle and a lack of synchrony. During
atrial fibrillation, the atrioventricular node receives electrical
impulses from numerous locations throughout the atria instead of
only from the sinus node. This condition overwhelms the
atrioventricular node into producing an irregular and rapid
heartbeat. As a result, blood pools in the atria and increases the
risk of blood clot formation. The major risk factors for atrial
fibrillation include age, coronary artery disease, rheumatic heart
disease, hypertension, diabetes, and thyrotoxicosis. Atrial
fibrillation affects 7% of the population over age 65.
[0007] Atrial fibrillation treatment options are limited. Three
known treatments, lifestyle change, medical therapy and electrical
cardioversion all have significant limitations. Lifestyle change
only assists individuals with lifestyle-related atrial
fibrillation. Medication therapy assists only in the management of
atrial fibrillation symptoms, may present side effects more
dangerous than atrial fibrillation, and fail to cure atrial
fibrillation. Electrical cardioversion attempts to restore sinus
rhythm but has a high recurrence rate. In addition, if there is a
blood clot in the atria, cardioversion may cause the clot to leave
the heart and travel to the brain or to some other part of the
body, which may lead to stroke. What are needed are new methods for
treating atrial fibrillation and other conditions involving
disorganized electrical conduction.
[0008] Various ablation techniques have been proposed to treat
atrial fibrillation, including the Cox-Maze procedure, linear
ablation of various regions of the atrium, and circumferential
ablation of pulmonary vein ostia. The Cox-Maze procedure and linear
ablation procedures are unrefined, unnecessarily complex, and
imprecise, with unpredictable and inconsistent results and an
unacceptable level of unsuccessful procedures. These procedures are
also tedious and time-consuming, taking several hours to
accomplish. Pulmonary vein ostial ablation is proving to be less
effective and when ablations are performed too close or inside the
pulmonary vein rapid stenosis and potential occlusion of the
pulmonary veins can result. There is therefore a need for improved
atrial ablation catheters, systems and techniques, as well as
sophisticated user interfaces to safely and effectively use these
catheters.
SUMMARY OF THE INVENTION
[0009] According to a first aspect of the invention, an ablation
system used by an operator to treat a patient is disclosed. The
system comprises ablation catheters that have a flexible carrier
assembly that includes at least two ablation elements configured to
map electrocardiogram and deliver energy to tissue. The system
further includes an interface unit for providing energy to the
ablation elements of the ablation catheter. The interface unit also
has a visual display that provides to the operator a visual
representation of the geometry of the at least two ablation
elements. Information such as system parameter information is
displayed in geometric relation to the visual representation of the
ablation elements enabling simplified viewing and modifying of
system parameters.
[0010] According to a second aspect of the invention, an ablation
system used by an operator to treat a patient is disclosed. The
system comprises an ablation catheter that has a flexible carrier
assembly that includes at least two ablation elements configured to
deliver energy to tissue. The system further includes an interface
unit for providing energy to the ablation elements of the ablation
catheter. The interface unit also has a control interface with a
visual display. The control interface includes selection means
configured to permit an operator to select an icon displayed on the
visual display. Selection of the icon is used to modify the form in
which information is displayed, or select information to be
modified.
[0011] According to a third aspect of the invention, a percutaneous
catheter for performing a sterile medical procedure is disclosed.
The catheter is for inserting into a body cavity such as a vessel
of a patient and includes an elongate tubular structure with a
proximal end and a distal end. On the proximal end of the tubular
structure is a handle that is maintained within a sterile field
during the medical procedure. The handle further includes a control
assembly for controlling a separate medical device. In a preferred
embodiment, the separate medical device is outside of the sterile
field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate various
embodiments of the present invention, and, together with the
description, serve to explain the principles of the invention. In
the drawings:
[0013] FIG. 1 illustrates the treatment to be accomplished with the
devices and methods described below;
[0014] FIG. 2a illustrates a perspective view of an ablation
catheter consistent with the present invention in which the carrier
element has four carrier arms each including two ablation
elements;
[0015] FIG. 2b is a sectional view of a finned electrode of FIG.
2a;
[0016] FIG. 3a illustrates a perspective, partial cutaway view of a
preferred embodiment of an ablation catheter in which the carrier
element has three carrier arms each including two ablation
elements, an interface attached to the ablation catheter, and a
remote control device, all consistent with the present
invention;
[0017] FIG. 3b is a sectional view of a distal portion of the
ablation catheter of FIG. 3a;
[0018] FIG. 4 illustrates a front view of an interface unit and
user interface consistent with the present invention;
[0019] FIG. 5 illustrates a top view of a handle of a catheter
device consistent with the present invention;
[0020] FIG. 6 is flowchart summarizing a programmed sequence used
to select ablation elements or electrodes; and
[0021] FIG. 7 is flowchart summarizing a procedure in which the
ablation catheter is employed.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Reference will now be made in detail to the present
embodiments of the invention, examples of which are illustrated in
the accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts.
[0023] The present invention utilizes ablation therapy. Tissue
ablation is often used in treating several medical conditions,
including abnormal heart rhythms. Ablation can be performed both
surgically and non-surgically. Non-surgical ablation is typically
performed in a special lab called the electrophysiology (EP)
laboratory. During this non-surgical procedure a catheter is
inserted into a vessel such as a vein, and guided into the heart
using fluoroscopy for visualization. Subsequently, an energy
delivery apparatus is used to supply energy to the heart muscle.
This energy either "disconnects" or "isolates" the pathway of the
abnormal rhythm. It can also be used to disconnect the conductive
pathway between the upper chambers (atria) and the lower chambers
(ventricles) of the heart. For individuals requiring heart surgery,
ablation can be performed during coronary artery bypass or valve
surgery.
[0024] The present invention provides catheters for performing
targeted tissue ablation in a subject. In preferred embodiments,
the catheters comprise a tubular body member having a proximal end
and distal end and preferably a lumen extending therebetween. The
catheter is preferably of the type used for performing intracardiac
procedures, typically being introduced from the femoral vein in a
patient's leg or a vein in the patient's neck. The catheter is
preferably introducible through a sheath with a steerable tip that
allows positioning of the distal portion to be used, for example,
when the distal end of the catheter is within a heart chamber. The
catheters include ablation elements mounted on a carrier assembly.
The carrier assembly is preferably attached to a coupler, which in
turn is connected to a control shaft that is coaxially disposed and
slidingly received within the lumen of the tubular body member. The
carrier assembly is deployable from the distal end of the tubular
body member by advancing the control shaft, such as to engage one
or more ablation elements against cardiac tissue, which is
typically atrial wall tissue or other endocardial tissue.
Retraction of the control shaft causes the carrier assembly to be
constrained within the lumen of the tubular body member.
[0025] Arrays of ablation elements, preferably electrode arrays,
may be configured in a wide variety of ways and patterns. In
particular, the present invention provides devices with electrode
arrays that provide electrical energy, such as radiofrequency (RF)
energy, in monopolar (unipolar), bipolar or combined
monopolar-bipolar fashion, as well as methods for treating
conditions (e.g., atrial fibrillation, supra ventricular
tachycardia, atrial tachycardia, ventricular tachycardia,
ventricular fibrillation, and the like) with these devices.
Alternative to or in combination with ablation elements that
deliver electrical energy to tissue, other forms and types of
energy can be delivered including but not limited to: sound energy
such as acoustic energy and ultrasound energy; electromagnetic
energy such as electrical, magnetic, microwave and radiofrequency
energies; thermal energy such as heat and cryogenic energies;
chemical energy such as energy generated by delivery of a drug;
light energy such as infrared and visible light energies;
mechanical and physical energy such as pressurized fluid;
radiation; and combinations thereof.
[0026] As described above, the normal functioning of the heart
relies on proper electrical impulse generation and transmission. In
certain heart diseases (e.g., atrial fibrillation) proper
electrical generation and transmission are disrupted or are
otherwise abnormal. In order to prevent improper impulse generation
and transmission from causing an undesired condition, the ablation
catheters of the present invention may be employed.
[0027] One current method of treating cardiac arrhythmias is with
catheter ablation therapy, which, to date, has been difficult and
impractical to employ. In catheter ablation therapy, physicians
make use of catheters to gain access into interior regions of the
body. Catheters with attached electrode arrays or other ablating
devices are used to create lesions that disrupt electrical pathways
in cardiac tissue. In the treatment of cardiac arrhythmias, a
specific area of cardiac tissue having aberrant conductive
pathways, such as atrial rotors, emitting or conducting erratic
electrical impulses, is initially localized. A user (e.g., a
physician such as an electrophysiologist) directs a catheter
through a main vein or artery into the interior region of the heart
that is to be treated. The ablating element is next placed near the
targeted cardiac tissue that is to be ablated. The physician
directs energy, provided by a source external to the patient, from
one or more ablation elements to ablate the neighboring tissue and
form a lesion. In general, the goal of catheter ablation therapy is
to disrupt the electrical pathways in cardiac tissue to stop the
emission of and/or prevent the propagation of erratic electric
impulses, thereby curing the heart of the disorder. For treatment
of atrial fibrillation, currently available methods and devices
have shown only limited success and/or employ devices that are
extremely difficult to use or otherwise impractical.
[0028] The ablation catheters of the present invention allow the
generation of lesions of appropriate size and shape to treat
conditions involving disorganized electrical conduction (e.g.,
atrial fibrillation). The ablation catheters and the
energy-providing interface unit of the present invention are also
practical in terms of ease-of-use and limiting risk to the patient,
such as by significantly reducing procedure times. The present
invention accomplishes these goals by, for example, the use of
spiral shaped, radial arm shaped (also called umbrella shaped) and
zigzag shaped carrier assemblies whose ablation elements create
spiral, radial, zigzag or other simple or complex shaped patterns
of lesions in the endocardial surface of the atria by delivery of
energy to tissue or other means. The lesions created by the
ablation catheters are suitable for inhibiting the propagation of
inappropriate electrical impulses in the heart for prevention of
reentrant arrhythmias. Simplified ease of use of these ablation
catheters is accomplished with a sophisticated user interface,
integral to the interface unit, which includes a visual display
that provides a visual representation of the geometry of the
ablation elements of the ablation catheter.
[0029] Definitions. To facilitate an understanding of the
invention, a number of terms are defined below.
[0030] As used herein, the terms "subject" and "patient" refer to
any animal, such as a mammal like livestock, pets, and preferably a
human. Specific examples of "subjects" and "patients" include, but
are not limited, to individuals requiring medical assistance, and
in particular, requiring atrial fibrillation catheter ablation
treatment.
[0031] As used herein, the terms "catheter ablation" or "ablation
procedures" or "ablation therapy," and like terms, refer to what is
generally known as tissue destruction procedures.
[0032] As used herein, the term "ablation element" refers to an
energy delivery element, such as an electrode for delivering
electrical energy. Ablation elements can be configured to deliver
multiple types of energy, such as ultrasound energy and cryogenic
energy, either simultaneously or serially. Electrodes can be
constructed of a conductive plate, wire coil, or other means of
conducting electrical energy through contacting tissue. In
monopolar energy delivery, the energy is conducted from the
electrode, through the tissue to a ground pad, such as a conductive
pad attached to the back of the patient. The high concentration of
energy at the electrode site causes localized tissue ablation. In
bipolar energy delivery, the energy is conducted from a first
electrode to one or more separate electrodes, relatively local to
the first electrode, through the tissue between the associated
electrodes. Bipolar energy delivery results in more precise,
shallow lesions while monopolar delivery results in deeper lesions.
Both monopolar and bipolar delivery provide advantages, and the
combination of their use is a preferred embodiment of this
application. Energy can also be delivered using pulse width
modulated drive signals, well known to those of skill in the art.
Energy can also be delivered in a closed loop fashion, such as a
system with temperature feedback wherein the temperature modifies
the type, frequency and/or magnitude of the energy delivered.
[0033] As used herein, the term "carrier assembly" refers to a
flexible carrier, on which one or more ablation elements are
disposed. Carrier assemblies are not limited to any particular
size, or shape, and can be configured to be constrained within an
appropriately sized lumen.
[0034] As used herein, the term "spiral tip" refers to a carrier
assembly configured in its fully expanded state into the shape of a
spiral. The spiral tip is not limited in the number of spirals it
may contain. Examples include, but are not limited to, a wire tip
body with one spiral, two spirals, ten spirals, and a half of a
spiral. The spirals can lie in a relatively single plane, or in
multiple planes. A spiral tip may be configured for energy delivery
during an ablation procedure.
[0035] As used herein the term "umbrella tip" refers to a carrier
assembly with a geometric center which lies at a point along the
axis of the distal portion of the tubular body member, with one or
more bendable or hinged carrier arms extending from the geometric
center, in an umbrella configuration. Each carrier arm may include
one or more ablation elements. Each carrier arm of an umbrella tip
includes a proximal arm segment and a distal arm segment, the
distal arm segment more distal than the proximal arm segment when
the carrier assembly is in a fully expanded condition. One or more
additional carrier arms can be included which include no ablation
elements, such as carrier arms used to provide support or cause a
particular deflection. An umbrella tip body is not limited to any
particular size. An umbrella tip may be configured for energy
delivery during an ablation procedure.
[0036] As used herein, the term "lesion," or "ablation lesion," and
like terms, refers to tissue that has received ablation therapy.
Examples include, but are not limited to, scars, scabs, dead
tissue, burned tissue and tissue with conductive pathways that have
been made highly resistive or disconnected.
[0037] As used herein, the term "spiral lesion" refers to an
ablation lesion delivered through a spiral tip ablation catheter.
Examples include, but are not limited to, lesions in the shape of a
wide spiral, and a narrow spiral, a continuous spiral and a
discontinuous spiral.
[0038] As used herein, the term "umbrella lesion" or "radial
lesion," and like terms, refers to an ablation lesion delivered
through an umbrella tip ablation catheter. Examples include, but
are not limited to, lesions with five equilateral prongs extending
from center point, lesions with four equilateral prongs extending
from center point, lesions with three equilateral prongs extending
from center point, and lesions with three to five non-equilateral
prongs extending from center point.
[0039] As used herein, the term "coupler" refers to an element that
connects the carrier assembly to the control shaft. Multiple
shafts, or ends of the carrier assembly may connect to the coupler.
Multiple carrier arms can have one or more of their ends attached
to the coupler. The coupler may include anti-rotation means that
work in combination with mating means in the tubular body member.
Couplers may be constructed of one or more materials such as
polyurethane, steel, titanium, and polyethylene.
[0040] As used herein, the term "carrier arm" refers to a wire-like
shaft capable of interfacing with electrodes and the coupler. A
carrier arm is not limited to any size or measurement. Examples
include, but are not limited to: stainless steel shafts; Nitinol
shafts; titanium shafts; polyurethane shafts; nylon shafts; and
steel shafts. Carrier arms can be entirely flexible, or may include
flexible and rigid segments.
[0041] As used herein, the term "carrier arm bend point" refers to
a joint (e.g., junction, flexion point) located on a carrier arm.
The degree of flexion for a carrier arm bend point may range from 0
to 360 degrees. The bend portion can be manufactured such that when
the carrier assembly is fully expanded, the bend point is
positioned in a relatively straight configuration, a curved
configuration, or in a discrete transition from a first direction
to a second direction, such as a 45 degree bend transition. The
bend portion can include one or more flexing means such as a
spring, a reduced diameter segment, or a segment of increased
flexibility.
[0042] The present invention provides structures that embody
aspects of the ablation catheter. The present invention also
provides tissue ablation systems and methods for using such
ablation systems. The illustrated and various embodiments of the
present invention present these structures and techniques in the
context of catheter-based cardiac ablation. These structures,
systems, and techniques are well suited for use in the field of
cardiac ablation.
[0043] However, it should be appreciated that the present invention
is also applicable for use in other tissue ablation applications
such as tumor ablation procedures. For example, the various aspects
of the invention have application in procedures for ablating tissue
in the prostrate, brain, gall bladder, uterus, and other regions of
the body, preferably regions with an accessible wall or flat tissue
surface, using systems that are not necessarily catheter-based.
[0044] The multifunctional catheters of the present invention have
numerous advantages over previous prior art devices. The present
invention achieves efficiency in tissue ablation by maximizing
contact between electrodes and tissue, such as the atrial walls,
while also achieving rapid and/or efficient transfer of heat from
the electrode into the circulating blood ("cooling"), such as by
maximizing electrode surface area in contact with circulating
blood. To achieve this result, in a preferred embodiment the
electrode has a projecting fin that is configured to act as a heat
sink that provides rapid and efficient cooling of the electrode. In
another preferred embodiment, the electrode comprises two
components such that one component, the electrode conductive
portion, contracts tissue and the other component, the
nonconductive portion, remains thermally conductive. The present
invention includes electrodes with improved and miniaturized cross
sectional geometries and carrier assemblies that "fold-up"
efficiently to allow a smaller ablation catheter to be employed.
These improved electrodes are preferably triangularly shaped as
described in detail in reference to subsequent figures below.
Because these triangular electrodes fold up efficiently, and can
have either a "base" to contact tissue or a "point" to contact
tissue, greater efficiency and versatility are achieved. The
devices and systems are configured to minimize the amount of tissue
ablated while still achieving the desired therapeutic benefit of
the ablation therapy. Ablated lesions are created with a target
depth, and minimal widths. System components monitor energy
delivered, parameters associated with energy delivered and other
system parameters. Energy delivered is prevented from achieving one
or more threshold values.
[0045] FIGS. 1-7 show various embodiments of the multifunctional
catheters of the present invention. The present invention is not
limited to these particular configurations.
[0046] FIG. 1 illustrates the treatment to be accomplished with the
devices and methods described herebelow. FIG. 1 shows a cutaway
view of the human heart 1 showing the major structures of the heart
including the right atrium 2, the left atrium 3, the right
ventricle 4, and the left ventricle 5. The atrial septum 6
separates the left and right atria. The fossa ovalis 7 is a small
depression in the atrial septum that may be used as an access
pathway to the left atrium from the right atrium. The fossa ovalis
7 can be punctured, and easily reseals and heals after procedure
completion. In a patient suffering from atrial fibrillation,
aberrant electrically conducive tissue may be found in the atrial
walls 8 and 9, as well as in the pulmonary veins 10 and the
pulmonary arteries 11. Ablation of these areas, referred to
arrhythmogenic foci (also referred to as drivers or rotors), is an
effective treatment for atrial fibrillation. Though circumferential
ablation of the pulmonary vein usually cures the arrhythmia that
originates in the pulmonary veins, as a sole therapy it is usually
associated with lesions that have high risk of the eventual
stenosis of these pulmonary veins, a very undesirable condition.
The catheters of the present invention provide means of creating
lesions remote from these pulmonary veins and their ostia while
easily being deployed to ablate the driver and rotor tissue.
[0047] To accomplish this, catheter 100 is inserted into the right
atrium 2, preferably through the inferior vena cava 20, as shown in
the illustration, or through the superior vena cava 21. Catheter
100 may include an integral sheath, such as a tip deflecting
sheath, or may work in combination with a separate sheath. When
passing into the left atrium, the catheter passes through or
penetrates the fossa ovalis 7, such as over a guide wire placed by
a trans-septal puncture device. The catheter 100 carries a
structure carrying multiple ablation elements such as RF
electrodes, carrier assembly 120, into the left atrium. Carrier
assembly 120, which includes multiple electrodes 130, can be
advanced and retracted out of distal end of catheter 100. Carrier
assembly 120 is adapted to be deformable such that pressing carrier
assembly 120 into left atrial wall 9 will cause one or more, and
preferably all of electrodes 130 to make contact with tissue to be
analyzed and/or ablated. Each of the electrodes 130 is attached via
connecting wires to an energy delivery apparatus, RF delivery unit
200, which is also attached to patch electrode 25, preferably a
conductive pad attached to the back of the patient.
[0048] RF delivery unit 200 is configured to deliver RF energy in
monopolar, bipolar or combination monopolar-bipolar energy delivery
modes. In a preferred embodiment, monopolar energy delivery is
followed by bipolar energy delivery. In an alternative embodiment,
the bipolar energy is then followed by a period without energy
delivery; such as a sequence in which the three steps are have
equal durations. In another preferred embodiment, RF delivery unit
200 is configured to also provide electrical mapping of the tissue
that is contacted by one or more electrodes integral to carrier
assembly 120. Electrodes 130, preferably with a triangular cross
section, can also be configured to be mapping electrodes and/or
additional electrodes can be integral to carrier assembly 120 to
provide a mapping function. Carrier assembly 120 is engageable over
an endocardial surface to map and/or ablate tissue on the surface.
RF energy is delivered after a proper location of the electrodes
130 is confirmed with a mapping procedure. If the position is
determined to be inadequate, carrier assembly 120 is repositioned
through various manipulations at the proximal end of the ablation
catheter 100. In another preferred embodiment, RF delivery unit 200
is configured to deliver both RF energy and ultrasound energy
through identical or different electrodes 130. In another preferred
embodiment, RF delivery unit 200 is configured to accept a signal
from one or more sensors integral to ablation catheter 100, not
shown, such that the energy delivered can be modified via an
algorithm which processes the information received from the one or
more sensors. The improved electrodes and other catheter and system
components of the present invention typically require only 3 to 5
watts of RF energy to adequately ablate the tissue. The minimal
power requirements results in reduced procedure time as well as
greatly enhanced safety of the overall procedure.
[0049] FIGS. 2a and 2b illustrate an exemplary embodiment of the
ablation catheter 100 of the present invention. These ablation
catheters have triangular electrodes 130, each with fin 133
configured to provide rapid and efficient cooling of electrode 130.
The cooling efficiency prevents over-heating of the electrode and
neighboring tissue during ablation, as well as a short transition
time from an ablation temperature, preferably 60.degree. C., to
body temperature, typically 37.degree. C. after an ablation cycle
has ceased. This rapid transition is typically less than 20
seconds, even when the electrode remains in contact with recently
ablated tissue. Other benefits of the rapid and efficient cooling
electrode configuration include reducing the risk of blood
clotting.
[0050] The ablation elements of the present invention include RF
energy delivery electrodes 130 of FIGS. 2a and 2b, as well as other
elements capable of delivering one or more forms of energy,
described in detail hereabove, the electrodes and other system
components configured in a manner sufficient to controllably ablate
tissue. Electrodes 130 include conductive materials, such as a
metal or metal-coated material. Metals and combinations of metals
are appropriate such as: platinum, iridium, gold, stainless steel
and aluminum. Conductive polymers are also appropriate materials.
Conductive surfaces may be painted, coated or plated surfaces, such
as gold plated over a copper base. Electrode materials may also
include foils such as aluminum or gold foils attached to a base.
Electrodes 130 deliver RF energy in monopolar or bipolar mode as
has been described in reference to FIG. 1. Electrodes 130 are
designed to have small surface area, typically less than 2.5
mm.sup.2 and preferably approximating 0.56 mm.sup.2. Electrodes 130
are designed to have small volume, typically less than 3.0 mm.sup.3
and preferably approximating 1.3 mm.sup.3. Electrodes 130 are
designed to have small mass, typically less than 0.05 grams, and
preferably approximating 0.03 grams. These miniaturized electrodes,
especially those with a triangular cross section, provide numerous
advantages such as high ratio of energy to surface area (energy
density) during ablation, as well as efficiently compact volume of
carrier assembly 120 when constrained within the lumen of the
ablation catheter in the retracted, undeployed state.
[0051] FIG. 2a shows the structures of the ablation carrier
assembly 120 and other portions of ablation catheter 100. The
ablation carrier assembly 120 shown includes carrier arms 123 that
extend radially out from the central axis of the distal end of
catheter shaft 101, the carrier arms 123 positioned in a symmetric
configuration with equal angles (ninety degrees in a four arm
configuration between each arm). Carrier assembly 120 is shown with
four carrier arms 123, however any number can be used, and each arm
can carry one or more mapping or ablating electrodes 130, or be
void of electrodes. Carrier arms 123 are resiliently biased,
preferably constructed of a wire such as a ribbon wire, and may
have segments with different levels of flexibility. Carrier arms
123 are shown with multiple electrodes 130 fixedly mounted (such as
with glues, soldering, welding, crimping or other attachment means)
to its distal arm segment 127. In an alternative embodiment,
different patterns of electrodes are employed, and one or more arms
may be void of electrodes such as where carrier arm 123 provides
support only. In a preferred embodiment, different types of
ablation elements are mounted to one or more carrier arms 123, such
as electrodes with different geometries, or ablation elements that
deliver different forms of energy. Carrier arms 123 may also
include mapping electrodes, thermal sensors or other sensors, with
or without the inclusion of ablation elements. In a preferred
embodiment, each carrier arm 123 includes at least one ablation
element. In alternative embodiments, three or more arms can be
separated by non-equal angles.
[0052] Each carrier arm 123 includes proximal arm segment 125 and
distal arm segment 127. Electrodes 130 are mounted onto distal arm
segment 127. During the ablation procedure, an operator presses
distal arm segment 127 into tissue prior to and during energy
delivery. Carrier assembly 120 is configured with specific rigidity
such that the operator can exert a nominal force to cause the
appropriate electrodes 130 to press and slightly "bury" into the
tissue, without perforating or otherwise damaging the neighboring
tissue. In a preferred embodiment, the distal arm segments contain
thermocouples such as sensors embedded in the electrodes 130, or
sensors mounted equidistant between two electrodes 130. Proximal
arm segment 125 and distal arm segment 127 connect at a bendable
joint, carrier arm bend point 121. In a preferred embodiment,
proximal arm segment 125, distal arm segment 127 and bend point 121
are a continuous resiliently flexible wire. Each distal arm segment
127 bends radially inward from the bend point 121 toward the
longitudinal axis of catheter shaft 101. The distal arm segments
127 are shown also to tend proximally, to establish an acute angle
with the proximal arm segment 125 from which it extends, and the
angle is small such that the distal end of the distal arm segment
127 is proximal to the carrier arm bend point 121. Bend point 121
allows "folding out" of carrier assembly 120 during retraction,
acting as a hinge in providing the means for rotably joining the
distal arm segment 127 to the proximal arm segment 125. The
proximal arm segment 125 of the carrier arm 123 may include
temperature sensors, not shown, such as thermocouples to measure
temperature of blood. In the configuration shown, the proximal arm
segment 125 will not contact tissue during the ablation procedure.
In an alternative embodiment, proximal arm segment 125 includes one
or more electrodes, for ablation and/or for mapping, such that the
opposite side of carrier assembly 120 can be used to map or ablate
tissue and is configured to contact tissue, such as when carrier
assembly 120 is deployed and catheter shaft 101 is in tension such
as when pulled back by an operator.
[0053] Each distal arm segment 127 connects, at its end opposite
bend point 121, to connection point 124, a mechanical joint such as
a soldered, crimped or welded connection that stabilizes each
distal arm segment 127 relative to the others. In a preferred
embodiment, two continuous wires or ribbons are used to create the
four distal arm segments 127. Each wire or ribbon comprises the
pair of distal arm segments 127 that are linearly aligned, and the
two wires are connected at their midpoint at connection point 124.
These wires or ribbons are preferably constructed of Nitinol, but
other materials such as stainless steel or a plastic may be used.
In an alternative embodiment, the two connection wires are
resiliently biased to deploy in the configuration shown in FIG. 2a,
but do not include connection point 124 such that the center
portion of the two continuous wires can move relative to each
other.
[0054] Referring to the ablation catheter 100 structures, FIG. 2a
shows a tubular body member that is an elongated, flexible, hollow
tube, catheter shaft 101, which connects at its proximal end to
handle 110. The material used for the construction of the catheter
shaft 101 and each component which resides or is configured to be
inserted through a lumen integral to catheter shaft 101, are
selected to provide the suitable flexibility, column strength and
steerability to allow percutaneous introduction of ablation
catheter 100 through the vasculature of the patient, entering the
right atrium 2 through the septum 6 and into the left atrium 3.
Catheter shaft 101 and other tubular conduits of ablation catheter
100 are constructed of materials such as Pebax, urethanes, nylons,
thermoplastic elastomers, and polyimides. The shafts may be
reinforced with wire or plastic braids and/or may include coil
springs. Catheter shaft 101 is typically between 4 to 12 French and
typically 6 to 8 French. In a preferred embodiment, catheter shaft
101 is introduced through a deflectable sheath where the sheath
mechanism is already in place in left atrium 3. In an alternative
embodiment, catheter 100 is inserted directly without the use of an
outer sheath, and catheter 100 includes a deflectable tip assembly
and deflection controls.
[0055] Handle 110 on the ablation catheter includes controls to
operate the carrier assembly 120. Handle 110 is constructed of a
rigid or semi-rigid material such as Delrin or polycarbonate, and
includes button 116 that is connected to switch means, not shown,
for starting and/or stopping the delivery of energy to one or more
of electrodes 130. Handle 110 may include other controls, not
shown, to perform numerous functions such as change energy delivery
settings. Handle 110 may include a retraction mechanism, not shown,
to advance and retreat carrier assembly 120. In an alternative
embodiment, handle 110 is attached to an inner shaft slidingly
received within catheter shaft 101 such that retraction of the
handle 110 causes the carrier assembly 120 to collapse and be
constrained within the lumen at end of catheter shaft 101. Carrier
arm 123 is resiliently biased in shown position so that it can be
collapsed and withdrawn within lumen of catheter shaft 101 through
manipulation of handle 110 on proximal end of catheter 100.
[0056] Handle 110 includes a plug 118 that attaches to an interface
unit of the present invention, such as an RF energy generator that
also includes mapping functions and display. Plug 118 is connected
to electrical wires that extend distally with a lumen integral to
catheter shaft 101 of carrier assembly 120, terminating at each of
the electrodes 130.
[0057] FIG. 2b illustrates the cross section, preferably a uniform
cross section, of one or more electrodes 130 mounted to distal arm
segment 127 of FIG. 2a. A projecting member, fin 133, assists in
the rapid and efficient cooling of electrode 130 during and after
ablation energy application, acting as a heat sink and efficiently
transferring heat energy to the neighboring blood, such as blood
circulating in the left atrium 3 or the right atrium 2 depending
upon where the carrier assembly 120 has been placed by the
operator. The size, surface area and mass of fin 133 are chosen to
effectively transfer the heat energy while allowing carrier
assembly 120 to achieve a sufficiently compact configuration when
constrained within the lumen of the ablation catheter. In a
preferred embodiment, fin 133 is sized such that the portion of the
surface area of electrode 130 that is in contact with circulating
blood is at least 60%, and preferably 70% of the total surface area
of electrode 130. Fin 133 may change laminar and/or other
non-turbulent flows to turbulent flow, such that heat is more
efficiently transmitted away from electrode 130. In an alternative
embodiment, fin 133 may be electrically isolated from the remainder
of electrode 130, such that fin 133 does not deliver energy to the
circulating blood. In another alternative embodiment, electrode 130
may include multiple fins.
[0058] First wire 134 is an energy delivery conduit that connects
to electrode 130 to transfer ablation energy and preferably to also
send and/or receive signals to map the tissue of the heart. Second
wire 135 depicts an exemplary wire that connects to electrode 130,
and may act as the return wire to first wire 134, for return of
ablation energy and/or mapping signals. Wire 134 and wire 135 are
typically 30 awg wire including a 0.003''polyamide insulating outer
jacket, each parameter chosen to carry sufficient ablation currents
and prevent voltage breakdown between neighboring wires. The
efficiency of the electrodes of the present invention, as well as
the efficient configuration of the other components of the system,
allow greatly reduced wire gauge and insulation thickness,
correlating to smaller diameter and more flexible ablation
catheters.
[0059] Surface 136 is the base of the electrode that is the part of
the structure that contacts tissue during ablation. In a preferred
embodiment, surface 136 is a small surface area so that energy
delivered per square area is maximized. Fin 133 projects from the
apex opposite surface 136, and provides sufficient surface area
such that the majority of the surface area of electrode 130 resides
in the circulating blood when surface 136 is in contact with tissue
and energy is being delivered. Within the triangular cross section
of electrode 130 passes each wire 134 and 135, as well as distal
arm segment 127, to which electrode 130 is fixedly mounted.
[0060] Referring now to FIGS. 3a and 3b, another preferred
embodiment of an ablation catheter, system and method of the
present invention is illustrated. The interface unit includes a
control interface and means of selecting one or more icons of a
visual display. The icons are selected to change information viewed
or modify a parameter. Catheter 100 includes carrier assembly 120
configured in another umbrella tip configuration. Carrier assembly
120 includes three carrier arms 123, each separated by 120 degrees
from the neighboring arm when in the deployed condition, and each
of which includes two ablation elements, electrodes 130. In an
alternative embodiment, different patterns of electrodes are
employed, and one or more arms may be void of electrodes.
Electrodes can take on one or more various forms, such as
electrodes with energy delivery portions and non-energy delivery
portions, electrodes with integral thermocouples, electrodes with
projecting fins that provide a heat sinking function, and other
types of electrodes. The six electrodes 130 shown may have similar
or dissimilar characteristics. They may be chosen to maximize
cooling or maximize energy delivery to tissue. Each electrode 130
may be energized with one or more forms of energy such as RF energy
in a sequence of monopolar and bipolar energy delivery. In a
preferred embodiment, multiple temperature sensors are integral to
carrier assembly 130, temperature sensors not shown but preferably
integral to electrodes 130 or fixedly attached to carrier arm 123
approximately mid-way between two electrodes 130. In another
preferred embodiment, one or more force sensors are integral to
carrier assembly 130, force sensors also not shown but typically
one or more strain gauges integral to electrodes 130 or carrier arm
123. In a preferred embodiment, the strain gauge is mounted to an
electrode 130 in a laminate construction, such that force exerted
on the laminate assembly is indicative of the amount of contact of
that electrode with tissue of the patient. Information from these
types of sensors is carried by one or more wires, also not shown,
to the interface unit of the present invention and provides system
parameter information that can be displayed to one or more
operators with current or historic values. This information can be
compared to target values and/or threshold values to simplify and
improve system performance.
[0061] Referring back to FIG. 3a, carrier arms 123 extend radially
out from the central axis of the distal end of catheter shaft 101.
Each carrier arm 123 includes proximal arm segment 125 and distal
arm segment 127, these segments connected at a bendable joint, bend
point 121. In a preferred embodiment, proximal arm segment 125 and
distal arm segment 127 and bend point 121 are a continuous
resiliently flexible wire, such as a "trained" Nitinol wire that
creates the umbrella tip. Each electrode 130 is mounted to an
insulator, insulating band 131 such that the electrode is
electrically isolated from the wire segments of carrier assembly
120. Each electrode 130 is connected to wires that extend along
shafts of carrier assembly 120, toward a lumen of catheter shaft
101, and proximally to handle 110. These wires, not shown but
described in detail hereabove, include insulation to electrically
isolate one wire from another. One end of each distal arm segment
127 is attached to a cylinder, coupler 140, which is sized to be
slidably received within a lumen of catheter shaft 101.
[0062] Coupler 140 can be flexible or rigid, and may contain both
rigid and flexible portions along its length. Coupler 140 may
provide electrical connection means to connect wires extending from
the handle to wires from carrier assembly 120 electrodes. The ends
of the distal arm segments 127 and the ends of the proximal arm
segments 125 can be attached to the outside of coupler 140, the
inside of coupler 140 or both. Coupler 140 includes along its outer
surface, a projection, projection 142, which has a cross section
profile which mates with a recess, groove 106 of catheter shaft 101
which prevents undesired rotation of carrier assembly 120. In an
alternative embodiment, catheter shaft 101 includes a projection,
and coupler 140 includes a groove to accomplish a similar
prevention of rotation. In another alternative embodiment, control
shaft 150, which is slidingly received within a lumen of shaft 101,
additionally or alternatively includes a projection or other means
to mate with shaft 101 to prevent undesired rotation of carrier
assembly 120. As depicted in FIG. 3b, control shaft 140 includes a
thru lumen, lumen 152, such that ablation catheter 101 can be
inserted over a guidewire (guidewire exit on handle 110 not shown).
Additionally or alternatively, lumen 152 may include one or more
wires or other filamentous conduits extending from proximal handle
110 a point more distal.
[0063] Control shaft 150 is mechanically attached to coupler 140.
Control shaft 150 extends proximally to handle 110 and is operably
connected to knob 115 such that rotation of knob 115 from a
deployed position to a withdrawn position causes carrier assembly
120 to be constrained within a lumen of catheter shaft 101, and
rotation of knob 115 from a withdrawn position to a deployed
position causes carrier assembly 120 to extend beyond the distal
end of catheter shaft 101 to be in an expanded condition. In a
preferred embodiment, knob 115 is operably connected to control
shaft 150 via a cam, or set of gears, not shown, to provide a
mechanical advantage in the distance traveled by control shaft
150.
[0064] Catheter shaft 101 is preferably part of a steerable sheath,
steering mechanism not shown, and includes flush port 170, which is
configured to be attachable to a flushing syringe, used to flush
blood and other debris or contaminants from the lumen of an empty
catheter shaft 101 (wherein control shaft 150, coupler 140 and
carrier assembly 120 have been removed) or for flushing the space
between control shaft 150 and the inner wall of catheter shaft 101.
Catheter shaft 101 is not connected to handle 110, such that handle
110 can be withdrawn, removing control shaft 150, coupler 140 and
carrier assembly 120 from catheter shaft 101. This configuration is
useful when these components are provided in a kit form, including
combinations of different versions of these components, the
different combinations made available to treat multiple patients,
or a single patient requiring multiple electrode patterns or other
varied electrode properties such as tissue contact surface area,
electrode cooling properties and temperature sensor location. A
preferred example of a kit would include the catheter shaft 101 and
flush port 170 of FIG. 3a acting as a sheath; kitted with the
insertable shaft assembly comprising handle 110, control shaft 150,
coupler 140 and umbrella tipped carrier assembly 120 (also of FIG.
3a) combined with a second insertable shaft assembly. The second
insertable shaft assembly preferably includes a differently
configured carrier assembly such as an assembly with a different
pattern of electrodes, or an assembly comprising electrodes with
properties dissimilar from the electrodes of the first insertable
shaft assembly. Electrode or other ablation element variations
include but are not limited to: type of energy delivered; size;
cross sectional geometry; cooling properties; heating properties;
and combinations thereof. In another preferred embodiment of the
kit, a catheter configured for creating lesions at or near the
pulmonary veins of the left atrium is included.
[0065] Also depicted in FIG. 3a is a system of the present
invention, including in addition to ablation catheter 100, RF
delivery unit 200, an interface unit of the present invention which
connects to handle 110 with a multi-conductor cable 202 at RF
attachment port 181. RF delivery unit 200 includes user interface
201, such as a user interface including data input devices like
touch screens, buttons, switches, keypads, magnetic readers and
other input devices; and also including data output devices like
data and image screens, lights, audible transducers, tactile
transducers and other output devices. User interface 201 is used to
perform numerous functions including but not limited to: selecting
electrodes to receive energy (electrodes 130 of carrier assembly
120); setting power levels, types (bipolar and monopolar) and
durations; setting catheter and other system threshold levels;
setting mapping and other system parameters; initiating and ceasing
power delivery; deactivating an alarm condition; and performing
other functions common to electronic medical devices. User
interface 201 also provides information to the operator including
but not limited to: system parameter information including
threshold information; mapping and ablation information including
ablation element temperature and cooling information; and other
data common to ablation therapy and other electronic medical
devices and procedures. In a preferred embodiment, RF delivery unit
200 attaches to a temperature probe, such as an esophageal
temperature probe, determines the temperature from one or more
sensors integral to the probe, and further interprets and/or
displays the temperature information on user interface 201. In
another preferred embodiment, RF delivery unit 200 also includes
cardiac mapping means, such that mapping attachment port 182 can be
attached to RF delivery unit 200 avoiding the need for a separate
piece of equipment in the system. In another preferred embodiment,
RF delivery unit 200 can also deliver ultrasound and/or another
form of energy, such energy delivered by one or more additional
ablation elements integral to carrier assembly 120, additional
ablation elements not shown. Applicable types of energy include but
are not limited to: sound energy such as acoustic energy and
ultrasound energy; electromagnetic energy such as electrical,
magnetic, microwave and radiofrequency energies; thermal energy
such as heat and cryogenic energies; chemical energy; light energy
such as infrared and visible light energies; mechanical and
physical energy such as pressurized fluid; radiation; and
combinations thereof.
[0066] In a preferred embodiment, ablation catheter 100 includes an
embedded identifier (ID), an uploadable electronic or other code,
which can be used by RF delivery unit 200 to confirm compatibility
and other acceptability of the specific catheter 100 with the
specific RF delivery unit 200. The electronic code can be a bar
code, not shown, on handle 110 which is read by RF delivery unit
200, an electronic code which is transferred to RF delivery unit
200 via a wired or wireless connection, not shown, or other
identifying means, such as an RF tag embedded in handle 110. In
another preferred embodiment, RF delivery unit 200 also includes an
embedded ID, such as an ID that can be downloaded to catheter 100
for a second or alternative acceptability check. The embedded ID
can also be used to automatically set certain parameters or certain
parameter ranges, and can be used to increase safety by preventing
inadvertent settings outside of an acceptable range for the
specific catheter 100.
[0067] Handle 110 includes mouse control 111, an adjustable knob
that provides two-dimensional control of cursor 230 of user
interface 201, similar to mouse-control devices integral to some
laptop computers. In a preferred embodiment, mouse control 111 can
be torqued in various directions to achieve the two-dimensional
control, and also pressed to provide a "click" or select function.
Additionally or alternatively, an additional control of handle 110
can be used to perform the click function. The click function is
used to select a graphic on visual display 220, such as icon 240,
preferably an icon representation an ablation element 130 of
carrier assembly 120. Numerous icons can be provided to the
operator on display 220, such as icons that include information
relating to system performance such as power being delivered,
patient condition such as electrocardiogram (ECG) or tissue
temperature, or a system parameter that can be set by an operator
such as a target or threshold value. Alternatively, an icon or
other graphic can be selected to modify the display mode, such as
numeric form versus chart form, or a display mode characteristic
such as font size or color.
[0068] Mouse control 111 can control cursor 230 via wireless
transmissions using a wireless transceiver, not shown, or wired
communication utilizing a wire integral to cable 202. Cursor 230
can be moved within visual display 220 of user interface 201
through manipulation of mouse control 111 and/or by other means,
such as one or more controls integral to user interface 201 of RF
delivery unit 200 or a computer mouse attached to RF delivery unit
200 (computer mouse not shown). In a preferred embodiment, visual
display 220 is a touch screen display, permitting the selection of
one or more icons, as well as other graphic images provided on
display 220, by an operator pressing at the appropriate location on
display 220. In another preferred embodiment, a visual
representation of one or more of: the geometry of the electrodes
130, the geometry of one or more sensors, and the geometry of the
patient's anatomy, is further provided. Information, such as system
parameter information or other information, is displayed in
relative geometric orientation to the one or more visual
representations of catheter geometry and patient anatomy.
[0069] Also included in the system of the present invention is an
additional device, handheld remote control 300. Remote control 300
includes a user interface with user input components such as
buttons, and may include user output components such as an LCD
screen or touch screen. Remote control 300 communicates with RF
delivery unit 200 with wireless transmissions via an integral
wireless transceiver than sends wireless information to RF delivery
unit 200, and preferentially can also receive wireless
communications from RF delivery unit 200 and other devices. In a
preferred embodiment, remote control 300 is sterile and maintained
in the sterile field of the patient, for use by one or more sterile
operators, during the ablation procedure. In an alternative
embodiment, remote control 300 is placed in a sealed, sterile bag
and maintained in the sterile field. Remote control 300, in
addition to mouse control 111 of ablation catheter 100 allow the
clinician operator in the sterile field to modify one or more
parameters of RF delivery unit 200, preferably not in the sterile
field. Parameters may include parameters that cause one or more of:
the activation or cessation of energy delivery; a change in the
information displayed on visual display 220; a change in the manner
in which information is displayed on visual display 220 such as a
change in font size, graphic size, brightness or contrast; a change
in alert status such as the muting of an alarm; or other function
otherwise needed to be performed by an operator outside of the
sterile field of the patient. In an alternative embodiment, remote
control 300 has a wired connection to RF delivery unit 200.
[0070] Handle 110 also includes two push buttons, first button 116
and second button 117. These buttons can be used to perform one or
more functions, and can work in cooperation with user input
components of user interface 201 such that commands entered into
user interface 201 set the action taken when either or both button
116 and button 117 are pressed. In a preferred embodiment, both
button 116 and button 117 must be pressed simultaneously to deliver
energy to one or more ablation elements of catheter 100. At the
distal end of catheter shaft 101 is a circumferential band, band
104. Band 104 is preferably a visualization marker, such as a
radiographic marker, ultrasound marker, electromagnetic marker,
magnetic marker and combinations thereof. In an alternative
embodiment, band 104 transmits or receives energy, such as when the
marker is used as a ground or other electrode during an ablation.
In another alternative embodiment, band 104 is an antenna used to
determine the position of the distal end of catheter shaft 101 or
the location of another component in relation to band 104. In
another preferred embodiment, band 104 is used to store energy,
such as capacitively stored energy that can be used to generate a
magnetic field or to deliver ablation energy.
[0071] While the ablation catheter of FIGS. 3a and 3b is shown with
an umbrella tip geometry, it should be appreciated that numerous
configurations of carrier arms, such as spiral, zigzag, and other
patterns could be employed. These carrier assemblies are configured
to provide sufficient forces to maximally engage the appropriate
ablation element with the tissue to be ablated, without adversely
impacting neighboring structures and other tissues. While the
carrier assembly 120 of FIG. 3a "folds in" during retraction of
shaft 150, other collapsing configurations can be employed such as
the "fold out" configuration of the catheter of FIG. 2a, or
configuration in which the carrier assembly transforms from a
spiral, zigzag, or other curvilinear shape to a relatively straight
or linear configuration as it is retracted and captured by the
lumen of catheter shaft 101. Electrodes 130 of carrier assembly of
FIG. 3a are shown facing out from the distal end of shaft 101 such
that advancement or "pushing" of carrier assembly 120 engages
electrodes 130 with tissue. In an alternative embodiment,
electrodes are positioned, alternatively or additionally, to face
toward the distal end of shaft 101. These electrodes may be mounted
to proximal arm segment 125 such that retraction or "pulling" of
carrier assembly 120, once deployed, engages these rear-facing
electrodes with tissue.
[0072] Ablation catheter 100 and RF delivery unit 200 are
configured to ablate tissue with minimal power and precise control.
RF Power levels are preferably less than 10 watts per electrode,
and preferably 3 to 5 watts. Electrodes 130 are powered to reach an
ablation temperature of approximately 60.degree. C. The electrode
geometries of the present invention, described in detail in
reference to FIGS. 2a and 2b, provide numerous and varied benefits
including enhanced cooling properties. Electrodes of the present
invention are configured to rapidly transition from an ablation
temperature of 60.degree. C. to body temperature of 37.degree. C.,
such as in a time period less than 10 seconds. These electrodes are
further configured to rapidly increase from body temperature to
ablation temperature, such as in a time period less than 5 seconds.
In a preferred embodiment, bipolar RF energy is delivered
subsequent to monopolar delivery. The electrodes and power delivery
subsystems of the present invention are configured to allow the
electrode and neighboring tissue to decrease in temperature during
the bipolar RF energy delivery following the monopolar delivery.
This bimodal, sequential power delivery reduces procedure time,
allows precise control of lesion depth and width, and reduces large
swings in ablation temperatures. In another preferred embodiment,
the temperature in the tissue in proximity to the electrode
actually continues to increase as the electrode temperature
decreases, such as during the bipolar delivery following monopolar
delivery. In an alternative embodiment, the monopolar delivery
cycle, the bipolar delivery cycle, or both, are followed by a
period of time in which no RF energy is delivered. During this
"off" time period, no energy may be delivered or an alternative
energy may be delivered such as cryogenic energy that actually
decreases the temperature of the tissue in order to ablate.
[0073] In a preferred embodiment, parameters associated with the
bipolar and monopolar energy delivery are adjusted during the
procedure, automatically by the system and/or manually by the
operator. The energy delivery parameters are adjusted by measured,
calculated or otherwise determined values include those relating
to: energy delivered measurements such as voltage or current
delivered to an electrode; force or pressure measurement such as
the force exerted by the carrier assembly as measured by an
integral strain gauge; other ablation catheter or ablation system
parameter; temperature of tissue; rate of change of temperature of
tissue; temperature of an electrode or other ablation element; rate
of change of temperature of an electrode or other ablation element;
ECG; tissue thickness; tissue location; cardiac flow-rate; other
patient physiologic and other patient parameters; and combinations
thereof. The energy delivery drive parameters may be adjusted by a
combination of these determined values. In order to automatically
modify an energy delivery parameter, or to notify an operator of a
condition, these determined values are compared to a threshold,
such as via a threshold comparator integral to the interface unit
of the present invention. Threshold values can be calculated by the
system or can be entered by the operator into a user interface of
the system.
[0074] Energy delivered measurements, such as current, voltage and
power measurements, which may be compared to a threshold value,
include average energy; instantaneous energy; peak energy;
cumulative or integrated energy amounts; and combinations thereof.
In the catheter and system of the present invention, average power
is approximately 5 Watts and less, cumulative energy for a cycle of
bipolar and monopolar delivery is typically less than 500
Watt-seconds and preferably less than 300 Watt-seconds (5 watts for
60 seconds). Each threshold value may change over time and may be
adjustable by an operator such as via a password enabled user
interface. Cumulative determined values, such as cumulative energy
delivered and "time at temperature" values may be able to be reset,
such as automatically by the system and/or manually by an operator.
Automatic resets may occur at specific events such as each time an
ablation element is repositioned on tissue or each time energy
delivered changes states, including the switching of electrodes
receiving energy or the completion of a monopolar-bipolar delivery
cycle.
[0075] Determined values such as temperature measurements may be
made from single or multiple sensors, such as multiple temperature
sensors during a single ablation cycle. In a preferred embodiment,
multiple sensors are used and the more extreme (e.g. a higher
temperature) value is compared to a threshold. When the threshold
comparator determines a particular threshold has been reached, the
system can adjust or otherwise react in various ways. In a
preferred embodiment, the system enters an alarm or alert state. In
another preferred embodiment, the energy delivery transmitted to an
ablation element is modified; such as to cease or reduce the amount
of RF energy delivered to an electrode. Numerous energy delivery
parameters can be modified including but not limited to: current
level; voltage level; frequency (usually fixed at 500 KHz); bipolar
delivery "on" times; monopolar delivery "on" times; no energy
delivery "on" times; electrode selected such as bipolar return
electrode selected; and combinations thereof.
[0076] The automatic and manual adjustments of the present
invention are triggered by comparing a measured, calculated or
otherwise determined value to a threshold. These adjustments
improve numerous outcomes of the proposed ablation therapy
including those associated with improved efficacy and reduced
adverse events. Specific benefits include precision controlled
depth and width of lesions through a combination of bipolar and
monopolar sequential duty cycles. The system is adjustable by the
operator to modify intended lesion geometry to safely avoid
structures like pulmonary vein lumens and the esophagus, as well as
work in portions of the atrial wall that require deep lesions to
effectively interrupt aberrant pathways.
[0077] Referring now to FIG. 4, an interface unit of the present
invention is illustrated. The interface unit is for attachment to
an ablation catheter, not shown, that includes at least two
ablation elements used to deliver energy to tissue. In a preferred
embodiment, the at least two ablation elements of the ablation
catheter are further configured to record electrical signals from
tissue. The interface unit provides one or more forms of energy to
the ablation catheter. The interface unit includes a visual display
that provides a visual representation of the geometry of the at
least two ablation elements. This visual representation allows
numerous icons and other graphics, such as those containing system
input or output information, to be visualized by one or more
operators of the system in a geometric location relative to the
geometric representation of the ablation elements. The
functionality of the various icons and other graphics presented on
the display may be modified or programmed by the user. That is, the
icons may be programmed by the user to visually represent different
system parameters and/or permit the modification of one or more
system parameters. In an alternative or additional embodiment, the
user can create a new icon, after which one or more functionalities
can be assigned, by the user or otherwise, to the activation of
that icon. Such enhanced visualization of information simplifies
programming and use, especially with ablation catheters including
larger number of ablation elements and/or complex ablation element
patterns. Simplified use correlates to a shorter and safer
procedure for the patient, and reduced costs for the healthcare
system. Information, such as system parameter information, includes
information related to values of parameters, on or off states of
functions such as energy delivery and alarm functions, patient
physiologic parameters such as tissue temperature and ECG, and
other information used or produced by the system during the
ablation and/or mapping procedure. Information may include numeric
and/or or text values, and may be associated with a specific
component of a catheter, such as a specific ablation or mapping
element.
[0078] In a preferred embodiment, system parameter information
displayed, selected and/or modified is selected from the group
consisting of:
[0079] an energy delivery parameter such as the specific ablation
element or elements selected for energy delivery, current, voltage,
frequency, power, mode such as monopolar or bipolar mode, duration
such as on time or off time, impedance, and type of energy to be
delivered such as RF energy or ultrasound energy;
[0080] a sensor parameter such as selected sensor or selected
multiple sensors, tissue contact measurement value; temperature,
pressure, strain and ECG, cardiac flow rate, tissue thickness and
tissue location;
[0081] an alarm parameter such as an alarm on state;
[0082] an additional catheter parameter such as distance between
two ablation elements, distance between a sensor and an ablation
element, and distance between two sensors;
[0083] an additional system component parameter;
[0084] target value for a system parameter;
[0085] a threshold value for a system parameter;
[0086] a current ("real time") value for a system parameter;
[0087] as well as derivatives (such as mathematically processed
values) and combinations thereof.
[0088] Referring back to FIG. 4, the interface unit of the present
invention is comprised of RF delivery unit 200, which is configured
to provide RF energy to an ablation catheter. RF delivery unit 200
is comprised of a single discrete component including attachment
ports, user input components and user output components. In an
alternative embodiment, RF delivery unit 200 includes multiple
discrete components such as a RF generator unit and one or more
separate video monitors. RF delivery unit 200 includes multiple
attachment ports, port 205a, 205b and 205c. Port 205a is for
attachment to an ablation catheter, and includes energy delivery
conduit attachment such as a wire for delivering the RF energy,
wires and other conduits such as fiber optic cables for
transmitting or receiving light signals and energy. Port 205b and
port 205c may be attached to the same ablation catheter, a second
ablation catheter, and/or another catheter or other device. Each
attachment port may be configured to send or receive power or
information signals, in various forms including electrical, light
and fluid such as cryogenic fluid. Attachment ports may provide
connections for pressurized air or saline for balloon inflation,
flow of fluid for ablation and/or cooling, or other connection
needs.
[0089] Unit 200 includes two visual displays, each preferably a
touch screen display, first visual display 220a and second visual
display 220b. Each display is configured to provide information to
one or more operators of the system as well as allow these
operators to modify a system parameter or modify which information
is to be displayed and the form in which it is displayed. The
display may be preconfigured by the manufacturer so that the
operator or operators are prived with customized information for
future selection and/or activation by the operator's choice. The
programming may be performed with an input device such as the touch
screen display, the keypad 210, cursor 230, mechanical switches, or
the like. In some cases the functionality of the input devices
themselves may also be programmed by the operator. One or more
selection means can be used to select an icon or other graphic
displayed unit 200. Keypad 210 is a membrane keypad mounted to the
front panel allowing an operator to press one or more keys to
select and modify displayed information. Wireless transceiver 206
is a wireless communication element of the present invention and
allows a separate component, such as an ablation catheter of the
present invention, also including wireless communication means, to
send data in order to select and modify displayed information.
Alternatively, an ablation catheter can transmit wired
communication signals such as through attachment port 205a.
[0090] As shown in FIG. 4, first visual display 220a, preferably a
touch screen display, provides a visual representation of a
four-arm umbrella shaped carrier assembly, such as of the carrier
assembly of the ablation catheter of FIG. 2a. The visual
representation of the carrier assembly includes eight electrode
icons, labeled "1" thru "8" on visual display 220a. The electrode
icons, such as first electrode icon 241 for electrode 1 and second
electrode icon 242 for electrode 2, are shown mounted to a visual
representation of the carrier arms, such as icon 241 and icon 242
mounted to carrier arm 249. Shown on each ablation element icon is
temperature information for that electrode, for example degrees
Celsius information "38" for electrode 1 and "43" for electrode 2
(two electrodes not receiving ablation energy), and "61" for
electrode 7 and "59" for electrode 8 (two electrodes receiving
ablation energy). Adjacent to and geographically associated with
each ablation icon is an ECG information icon, such as ECG
information icon 247. The visual representation can be displayed
"actual size" in a 1 to 1 relationship, in an enlarged view, or in
a miniaturized or reduced view.
[0091] In embodiments in which first visual display 220a is a touch
screen, an icon can be selected by pressing the part of the display
in which the icon appears. Additionally or alternatively, the icon
can be selected by moving cursor 230 to a location at or above the
icon, such as with a mouse (not shown) attached to unit 200, a
control such as a control on keypad 210 of unit 200, or a remote
cursor control device such as a handle control described in
reference to FIG. 3a and FIG. 5. When cursor 230 is placed above a
particular icon, a click function such as a mouse click or keyboard
click function can be used to select the icon. Once selected, an
icon can be changed in the value of information displayed or the
form in which the information is displayed utilizing one or more of
the controls used to position the cursor.
[0092] Unit 200 of FIG. 4 further provides a second display, visual
display 220b that includes a second visual representation of the
geometry of the ablation elements of a catheter that is attached to
unit 200, catheter not shown. Display 220b includes an array of
electrode icons, similar to the visual representation provided on
display 220a. Adjacent to or above the electrode icons is
information that is related to each specific electrode, such as
target power level information provided on icon 251 neighboring
electrode 1, and the actual power level information provided on or
within the icon for electrode 1. This particular presentation of
current and target information, a preferred embodiment of the
present invention, provided in the actual geometric configuration
of the ablation catheter, such as the four arm ablation catheter
shown, provides a greatly simplified user interface for the
clinician or other operator to rapidly and simply interpret.
Further provided on visual display 220b is a visual representation
of the distal end of the ablation catheter, catheter icon 246,
including a visual representation of an electrode mounted on the
catheter body, catheter electrode icon 248. Catheter electrode icon
248 represents an electrode mounted on the distal end of the
tubular body member of a catheter. Alternatively, icon 248 may
represent a sensor, such as a temperature sensor. Information
associated with the geometric location of icon 248 is displayed on
or near icon 248, information not shown.
[0093] The visual displays of unit 200 of FIG. 4 display system
parameter information in geometric relation to a visual
representation of one or more parts of an attached ablation
catheter. The system parameter information displayed may be based
on signals received from one or more sensors integral to the
attached ablation catheter. The system parameter information may
include patient physiologic information such as ECG information
received from a mapping electrode or a combined ablation and
mapping electrode. In a preferred embodiment, ECG information is
provided simultaneous with energy delivery, such as when delivery
unit 200 includes an "active" filter which is configured to
actively remove noise signals generated by the concurrent tissue
ablation and "picked up" by the electrode provide the mapping
electrode, for example, the same electrode also delivering the
ablation energy. The active filter is configured to take advantage
of the known frequency, voltage and current being supplied to the
electrode by unit 200, to actively separate the resultant noise
from the true ECG signal.
[0094] The information displayed on visual display 220a or 220b can
be provided in one or more modes selected from the group consisting
of: alphanumeric text; a graph such as a line or bar graph; a chart
such as a pie chart; and combinations thereof. In a preferred
embodiment, the information mode of a set of information is
configured to be adjusted by a user, such as by selecting
information with a control on the ablation catheter or unit 200. In
another preferred embodiment, the mode of a set of information
adjusts automatically, such as when the information changes in
value.
[0095] The information displayed on visual display 220a or 220b can
be provided with one or more mode characteristics selected from the
group consisting of: size such as font size; font type such as
Arial or Helvetica; graphic size, color; contrast; hue; brightness;
and combinations thereof. In a preferred embodiment, the
information mode characteristic of a set of information is
configured to be adjusted by a user, such as by selecting
information with a control on the ablation catheter or unit 200. In
another preferred embodiment, the mode characteristic of a set of
information adjusts automatically, such as when the information
changes in value. Numerous configurations of information colors,
sizes and boldness can be used to simplify use, and avoid
potentially dangerous situations such as an increase in font size
or boldness when a system parameter approaches an unsafe state,
such as an unsafe temperature set by a threshold. In a preferred
embodiment, the information displayed is actual or current tissue
temperature information and the information displayed is shown in
blue font when the temperature approximates body temperature, and
transitions to shades of red as the temperature rises. In another
preferred embodiment, temperature values are displayed in blue when
the temperature is at or below a target temperature. Temperature is
displayed in yellow when temperatures are above the blue
temperature range but still within an allowable specification (e.g.
a second target level). Temperature is displayed in red when above
the yellow temperature range (e.g. at an undesired or unacceptable
level). In yet another preferred embodiment, the displayed
information transitions from a lighter shade to a darker shade as
the value of a piece of information increases. In yet another
preferred embodiment, the information displayed is target
information, such as target temperature information, and the
information is displayed in blue or yellow, blue representing a
temperature level below the temperature level represented by
yellow. In yet another preferred embodiment, unit 200 further
comprises an audio transducer, not shown. The audio transducer
emits an alert sound to the operator to signify one or more of: an
icon or other displayed information is selected; information is
modified; a threshold is reached by a system parameter; and
combinations thereof.
[0096] The information displayed on visual display 220a or 220b can
be of one or more information types selected from the group
consisting of: current, historic, target, threshold, and
combinations thereof. Current information may be real time (current
time) information selected from the group consisting of: ECG or
recognized ECG pattern; energy delivery value such as power,
voltage or current; temperature; rate of temperature change;
distance; force; pressure; location; and combinations thereof.
Target information may be information selected from the group
consisting of: recognized ECG pattern; energy delivery value such
as power, voltage or current; temperature; rate of temperature
change; distance; force; pressure; location; and combinations
thereof. Threshold information may be information selected from the
group consisting of: recognized ECG pattern; energy delivery value
such as power, voltage or current; temperature; rate of temperature
change; distance; force; pressure; location; and combinations
thereof. In a preferred embodiment, related current and target
information are displayed simultaneously. In another preferred
embodiment, related current and threshold information are displayed
simultaneously. In yet another preferred embodiment, multiple
pieces of information of the same information type are displayed
with the same display mode characteristic. In yet another preferred
embodiment, multiple pieces of information of the same information
type are displayed in the same color.
[0097] System parameter and other information measured, calculated
and otherwise determined by the system of the present invention may
include similar information from two or more system components,
such as temperature information received from two or more sensors.
An operator of the system may prefer to only view the extreme
conditions, such as the "worst-case" conditions, such as the
highest of all temperatures received. In a preferred embodiment,
worst-case information is displayed on visual display 220a or 220b
in a different mode or with a different mode characteristic than
non worst-case information. In another preferred embodiment,
worst-case information is shown in redundant form on either or both
displays 220a and 220b, such as in one location in proximity to the
element producing the associated information, and in a separate
"worst-case location", providing a standard location for the
operator to view to see the worst-case information.
[0098] In a preferred embodiment, the attached ablation catheter
includes one or more sensors, and a visual representation of the
sensor geometry is shown on display 220a, 220b or both. Sensor
geometry may include thermocouples integral to one or more
electrodes, or a separate temperature sensor shown in relation
(relative distance) to one or more neighboring electrodes. In
another preferred embodiment, the ablation catheter includes an
elongate body member, and a visual representation of the elongate
body member is provided on display 220a, 200b or both. One or more
system parameters are shown in geometric relation to the distal
portion of the elongate body member.
[0099] In another preferred embodiment, a visual representation of
the patient's anatomy, such as the anatomy neighboring the carrier
assembly of the attached ablation catheter, is shown of display
220a, 220b, or both. The displayed patient's anatomy preferably is
a visual representation of the patient's heart, such as an atrium
of the heart. Unit 200 may include a library of typical anatomical
landscapes, and unit 200 is configured to allow an operator to
select an appropriate anatomical image, and position the image
relative to the visual representation of the ablation elements or a
different visual representation described hereabove. Alternatively
or additionally, the image may be generated or partially generated
from information received from an imaging device, all not shown,
such as a: fluoroscope, external ultrasound device, internal
ultrasound device, MRI unit, infrared camera, and combinations
thereof. The imaging device may be included in the ablation
catheter or inserted within a lumen of the ablation catheter, such
as an ultrasound catheter or a fiber optic camera device. The fiber
optic camera may comprise an inserted fiber optic cable with a
wide-angle lens on the fiber optic's distal end, and a fiber optic
receiving camera on the fiber optic's proximal end.
[0100] In a preferred embodiment, bipolar RF ablation energy is
combined with monopolar RF energy to form specifically sized and
positioned lesions. Energy can be delivered to multiple electrodes
or multiple pairs of electrodes simultaneously or sequentially.
Selecting which electrodes are to receive energy, and in which form
(monopolar or bipolar), is greatly simplified with the user
interfaces of the present invention. In a preferred embodiment, two
electrodes are selected for receipt of bipolar energy by one or
more of: dragging a finger or stylus device from a first electrode
icon, such as electrode icon 241, to a second electrode icon such
as electrode icon 242; selecting a first electrode icon, moving a
cursor from the first electrode icon to a second electrode icon,
and selecting the second electrode icon; and combinations
thereof.
[0101] The interface unit 200 may be programmable so that energy is
delivered to certain electrodes or pairs of electrodes in a
predetermined sequence or sequences determined and/or selected by
the operator. The predetermined sequence may depend on the value of
other system or ablation parameters that have previously been
selected. For instance, if the operator selects a particular
carrier arm, one of the predetermined sequences may automatically
select to receive energy the innermost electrode on that arm or any
of the other electrodes on that arm. Additionally, in bipolar mode,
if the operator selects a particular electrode on a particular
carrier arm to receive energy, a predetermined sequence may be
programmed to automatically select another electrode(s) on that arm
(or a different arm) which has a preselected position relative to
the particular electrode selected by the operator. For instance,
the second electrode that is automatically selected to receive
energy may be the next electrode inward (or outward) from the first
electrode selected by the operator. Alternatively, the second
electrode that is automatically selected may be the corresponding
electrode on an adjacent arm (determined in a clockwise or
counterclockwise direction along the carrier array). As another
example, if the operator selects a particular arm for unipolar
operation only, a predetermined (e.g., outermost) electrode on that
arm is automatically selected. A button on the keypad may allow the
user to toggle between the various electrodes in the event that a
different electrode is desired. Another button (or other input
means) may be employed to override the programming so that the
selection of electrodes does not necessarily follow one of the
predetermined sequences.
[0102] FIG. 6 is flowchart summarizing a programmed sequence used
to select ablation elements or electrodes. In step 610 the
clinician or other operator selects a carrier arm to which energy
is to be delivered. In step 620, the system automatically selects a
particular electrode or electrode on the selected arm. The operator
is then given the option of accepting or rejecting the automatic
selection in step 630. If the operator accepts the automatic
selection, the various ablation parameters are set for that
electrode (if needed) after which the ablation process may begin.
If the operator does not accept the automatic selection, then in
step 640 the operator overrides the automatic selects and makes his
or her own selection, after which the various ablation parameters
are once again set for the operator-selected electrode (if
needed).
[0103] Referring back to FIG. 4, graphic display unit 200 may
include means of controlling a robotic ablation and/or mapping
catheter, not shown, such as a catheter whose tip orientation,
carrier assembly deployment condition or other catheter geometry
orientation is remotely controllable. The robotic catheter
typically comprises one or more linear or rotary actuators, such as
motors or solenoids, which are operably attached to elongate,
flexible linkage members slidingly received by the catheter's
shaft, all not shown. The actuators are activatable by an operator
via a control on graphic display unit 200, such as an icon on
visual display 220a or a button on keypad 210. The linkage members,
attached at their proximal end to an actuator such as via a cam or
other mechanical advantage assembly, are attached at their distal
end to an ablation and/or mapping carrier assembly, to a distal
portion of the catheter shaft, or to another catheter geometry
modifying component. Advancement and/or retraction of a linkage
cause the catheter's geometry to controllably, repeatably and
reversibly change. In this alternative embodiment, first visual
display 200a and/or second visual display 220b display the current
geometric configuration of one or all of the portions of the
robotically controlled catheter that can be remotely changed in its
orientation (e.g. via known actuator condition and/or information
from a catheter sensor). One or more controls of graphic display
unit 200, such as a button on keypad 210, or a control icon on
visual display 220a or 220b can be used to manipulate or otherwise
modify one or more catheter orientations, such as by sending
signals to an actuator operably connected to a linkage. As the
linkage is advanced or retracted via a control on graphic display
unit 200, the current displayed geometry of the catheter changes,
such as by changing in real time, to provide visual feedback to the
operator regarding catheter orientation. In a preferred embodiment,
graphic display unit 200 receives information from one or more
sensors integral to the robotically controlled catheter, such that
closed loop catheter geometry information is provided to graphic
display unit 200. Sensors may include strain gauges, magnetic
sensors and other sensors. The visual feedback information provided
on graphic display unit 200 can be used by an operator is use of
the catheter, in addition to visual information received via a
x-ray image provided through use of fluoroscopy and one or more
radiographic portions of the catheter. Fluoroscopic images are
often plagued with inaccuracies due to parallax and other
non-orthogonal imaging perplexities. These issues can be avoided by
the catheter specific geometry information provided to the operator
by graphic display unit 200. In an alternative or additional
embodiment, an integral shape memory component, such as a shape
memory polymer or an embedded shape memory alloy wire, provides
geometry information to graphic display unit 200. In a similar
fashion to the remote control described above, an operator used a
control on graphic display unit 200 to modify the geometry of a
portion of the catheter by changing the shaped memory component
condition. Simultaneous with the geometry change, a visual
representation of the current geometry is displayed on display 200a
and/or 200b.
[0104] Referring now to FIG. 5, a catheter of the present invention
is illustrated. The catheter is for performing a sterile medical
procedure and for insertion into a body cavity of a patient. An
integral control assembly is included for controlling a separate
medical device. Catheter 400 includes handle 410 mounted on its
proximal end. Handle 410 is mounted to a flexible shaft, such as a
shaft configured for percutaneous insertion and advancement in the
vasculature of a patient, to perform a medical procedure such as an
interventional therapeutic or diagnostic procedure. On the proximal
end of handle 410 are two attachment ports, first attachment port
420a, such as an attachment port for an ECG mapping system and
attachment port 420b, such as an attachment port for an ablation
energy delivery unit. Further included on handle 410 are two
buttons, first button 416, such as a button to initiate energy
delivery, and button 417 such as a button to reset an alarm
condition.
[0105] Handle 410 further includes knob 415, which is operably
attached to a pull-wire that extends near the distal end of shaft
401, pull-wire and distal end not shown. Rotation of knob 415
causes the distal end of shaft 401 to deflect, such as to orient an
advancable tube toward a target. Battery 430 is integral to handle
410, and provides power to one or more electronic components or
assemblies of handle 410. One electronic component of handle 410 is
tactile transducer 440, preferably a miniature motor assembly with
an eccentric weight on its shaft. Rapid rotation of the shaft
causes an angular momentum change such that an operator holding
handle 410 can be notified of a condition such as an alarm
condition.
[0106] Handle 410 further includes wireless transceiver 450, a
wireless communication assembly that transfers information via RF
communication 451 or other wireless communication means to a
properly configured wireless receiver or transceiver. Handle 410
includes various input components, mouse 411 and keypad 412. Keypad
412 is preferably a waterproof, membrane keypad with multiple
activatable switches. Mouse 111 is preferably a waterproof,
adjustable knob that provides two-dimensional control of a display
cursor, similar to mouse-control devices integral to some laptop
computers. Handle 410 further includes one or more electronic
components, not shown, to process signals received from mouse 411
and keypad 412 and produce signals to be transmitted by wireless
transceiver 450. The wireless information is transmitted, such as
in a secure wireless transmission, to a separate medical device, in
order to control or otherwise change the state of the separate
medical device.
[0107] The separate medical device, not shown but preferably a
device maintained out of the sterile field of the ablation catheter
400, includes one or more control functions applicable to keypad or
mouse control. In a preferred embodiment, the separate medical
device to be controlled is selected from the group consisting of: a
fluoroscope system; an ultrasound system; a data management system
such as a patient information system; a cardiac defibrillation
system; a cardiac monitoring system; an esophageal probe system;
and combinations thereof. In a preferred embodiment, wireless
transceiver 450 sends wireless communications 451 to multiple
separate medical devices. Embedded in the transmissions is
preferably an ID, which signifies and/or identifies the particular
device that is intended to respond to the transmitted command. In
an alternative embodiment, wireless transceiver 450 receives
information and/or commands from a separate medical device.
Received information may indicate a remote device is in an alarm
state, and tactile transducer 440 may alert the operator of the
remote device's alarm state.
[0108] It should be understood that numerous other configurations
of the systems, devices and methods described herein may be
employed without departing from the spirit or scope of this
application. The ablation catheter includes one or more ablation
elements such as electrodes. These electrodes may include various
cross-sectional geometries, projecting fins, energy delivering
portions and non-energy delivering portions, and other varied
features. The systems of the present invention are configured to
automatically, semi-automatically or manually adjust various
ablation, mapping and other system parameters such as the energy
applied to the ablation elements such as by adjusting one or more
of the following: the level or amount of energy delivered; type of
energy delivered; drive signal supplied such as monopolar and
bipolar; phasing, timing or other time derived parameter of the
applied energy; and combinations thereof.
[0109] In some cases the ablation parameters may be adjusted to
their appropriate values with the use of macros to automate
frequently-used combinations of setting, parameters and/or
sequences. For instance, some macros may be employed in which two
or more ablation parameters are set by a single user action. The
macros may be pre-loaded into the interface unit or they may be
programmed by the user via a programming interface incorporated in
the interface unit. For example, when the user selects a particular
ablation element or ablation element pair, one macro may establish
values for the form of energy to be delivered to it, its power,
duration and maximum temperature. Other ablation parameters that
may be incorporated into macros include, without limitation, energy
parameters (e.g., the form or type of energy, duty cycle parameter,
power, monopolar and/or bipolar energy), ablation catheter
parameter (e.g. catheter model number or configuration), patient
parameter (e.g., a patient physiologic parameter such as heart wall
thickness or an electrocardiogram parameter) anatomical location
parameter (e.g. a location for an ablation to be performed such as
the septum between the left and right atria) and a temperature
parameter (e.g. a target ablation temperature or a maximum ablation
temperature). In a preferred embodiment, a uniformity of
temperature parameter is assigned to and/or activatable by a macro.
This uniformity of temperature may be a comparison of temperature
between two or more temperature sensors such as thermocouples. The
thermocouples may be integrated into the ablation catheter such
that a first sensor is indicative of tissue temperature and a
second sensor is indicative of neighboring blood. Each thermocouple
may be proximate a single ablation element, or an ablation element
pair such as a pair used to deliver bipolar radiofrequency
energy.
[0110] Some of the macros may be learning macros in which
previously used combinations of settings, parameters and/or
sequences are automated over time. Such learning macros may be
defined for certain procedures, patient parameters, ablation
elements, and the like.
[0111] The macros may be established and implemented using any of
the aforementioned input devices associated with the interface unit
200 such as the touch screen display 220a, keypad 210 and/or cursor
230. For instance, a particular macro may be initiated by use of a
predefined button on the keypad 210. The association between the
macros and the buttons on the keypad may be programmed by the user.
Of course, other devices such as switches and the like may be used
to establish and/or implement the macros. For instance, upon
establishing a new macro, icons on the touch screen display 22a may
be sequentially selected to record various ablation parameters
associated with the element represented by the icon. If a touch
screen display is not employed, the icons or other macro activation
elements may be selected by use of cursor 230 and a cursor
controlling device such as a mouse or keypad. In a preferred
embodiment, multiple components can be used to select, activate or
adjust an icon or other activatable adjustment means. In another
preferred embodiment, a selection component is located in the
sterile field of the patient (e.g. a cursor control element in the
handle of an ablation and/or mapping catheter of the present
invention).
[0112] In some systems, the interface unit may include an
autocomplete function in which the first few characters of an
alphanumeric character string are entered by a user and
automatically compared by the system to previously entered
character strings in order to reduce the number of steps required
to complete the entry. The characters that are entered may also be
compared to an electronic database or library of appropriate terms
to complete the entry. The database or library may include, without
limitation, historic system parameter data as well as terms
pertaining to patient specific data, operator specific data,
manufacturer-supplied data and the like. The historic system
parameter data may include both data entered by an operator in
previous use of the system, as well as data recorded by the system
during its use such as recorded temperature or power information
achieved during use. Historic information may include information
relevant to a first interface unit that has been uploaded into a
second interface unit, such as information transferred through
electronic transfer media (e.g. USB storage device) and/or
electronically networked components.
[0113] The autocomplete function may be based on a word prediction
algorithm that locates the identical or best match when comparing
the entered characters to previously entered character strings that
have been previously entered or otherwise are stored in a database
of relevant information. In a preferred embodiment, the library is
segregated into sub-libraries by system parameter type (e.g.
temperature information is segregated from power information such
that autocomplete is more appropriate). The algorithm that is
employed may successively compare the partially entered character
string with a library or sub-library set of values, each time a new
character is entered by the user, until an appropriate match is
determined. When a match is found, the user may be given an
opportunity to accept or reject the selection, such as via a
confirm function described herebelow. If no match is found, the
user simply completes the entry in the normal manner. If a match is
found, but the user continues to enter additional characters, the
autocomplete function is disabled. If more than one match is found,
one or more of them may be displayed (possibly in a rank order
beginning with the best or most likeliest match) and optionally
selected by the user.
[0114] In a preferred embodiment, the system of the present
invention includes a confirm function which must be activated in
order for a macro, such as an autocomplete macro, to be accepted or
initiated. The confirm function may be activated through the
selection of an icon (e.g. a touch screen icon) or a switch (such
as a membrane switch integral to the handle of an ablation
catheter). In a preferred embodiment, the confirm function icon is
displayed prior to macro initiation, and the operator selects the
icon to initiate the macro.
[0115] The wireless transmissions of the present invention
preferably include information that assures secure communications
between the two devices. Handshaking, error identification and
correction methods, and other wireless communication protocols are
preferably employed to assure safe and effective therapeutic
results. In a preferred embodiment, wireless communications include
a unique ID for either or both devices in communication. Wireless
communication means may include one-way or two-way capabilities.
The selection means of the present invention can take on various
forms selected from the group consisting of: control on the
interface unit, device in communication with interface unit such as
wired or wireless mouse or tablet; control on ablation catheter
such as a wired or wireless control on handle of ablation catheter;
control on separate therapeutic device; a verbal command such as a
recognized voice command made by an operator of the system; and
combinations thereof.
[0116] The operators of the present invention may take on various
forms, such as electrophysiologists that perform cardiac arrhythmia
treatment procedures in a catheterization or electrophysiology lab.
Multiple operators may be involved, such as the clinician
performing the procedure and residing in the sterile field of the
patient, and an assistant outside the sterile field and involved
with changing one or more system parameters.
[0117] The ablation elements of the present invention are attached
to energy delivery conduits that carry the energy to the electrode
that is supplied by the interface unit. RF electrodes are connected
to wires, preferably in a configuration with individual wires to at
least two electrodes to allow independent drive of the electrodes
including sequential and simultaneous delivery of energy from
multiple electrodes. Alternative or additional energy delivery
conduits may be employed, such as fiber optic cables for carrying
light energy such as laser energy; tubes that carry cryogenic fluid
for cryogenic ablation or saline for saline mediated electrical
energy ablation; conduits for carrying sound energy; other energy
delivery conduits; and combinations thereof.
[0118] The ablation elements of the catheter of the present
invention can additionally or alternatively perform the function of
cardiac mapping, such as metal plate or band electrodes integral to
the carrier assembly which record electrical activity present in
tissue. In these embodiments, the interface unit is electrically
connected to these mapping elements, receives the electrical
signals recorded from the tissue in contact with the mapping
elements, and processes these signals to display ECG and other
relevant signal information. The interface unit may or may not also
provide ablation energy to the catheter (e.g. if ablation elements
are also integral to the catheter). The various ablation system
user interface features and methods of the present invention,
described hereabove in reference to one or more ablation elements,
are directly applicable to embodiments involving mapping elements
and a mapping element user interface. A mapping system visual
display may provide a visual representation of the geometry of one
or more mapping elements. The mapping system visual display may
include an operator selectable icon, such as an icon representing a
mapping element. The mapping system user interface may include a
programming interface with a macro function that initiates two
commands with a single action. The mapping system user interface
may include an autocomplete function to automatically complete an
alphanumeric string that has been partially entered by an operator.
The mapping system user interface may include an operator
programmable adjustment means. The mapping system user interface
may include a programming interface which provides means of
selecting at least one arm of a carrier assembly of a mapping
catheter. After the specific arm is chosen by an operator, a
specific mapping element is automatically selected to have its
information displayed on a visual display of the system. The
mapping system user interface may provide a visual representation
of the geometry of one or more mapping elements as well as a visual
representation of a robotically maneuverable segment.
[0119] The system includes multiple functional components, such as
the ablation catheter, and the interface unit. The interface unit
preferably comprises: energy supply means and a user interface;
calculating means for interpreting data such as mapping data and
data received from one or more sensors; and means of comparing
measured, calculated or otherwise determined values to one or more
thresholds, such as a temperature or energy delivery threshold. The
interface unit further includes means of adjusting one or more
system parameters, such as the amount type, or configuration of
energy being delivered, when a particular threshold is met. The
ablation catheter includes ablation elements for delivering energy
to tissue such as cardiac tissue. Cardiac tissue applicable for
ablation includes left and right atrial walls, as well as other
tissues including the septum and ventricular tissue. The ablation
catheter of the present invention includes a flexible shaft with a
proximal end, a distal end, and a deployable carrier assembly with
multiple ablation elements. The flexible shafts may include one or
more lumens, such as thru lumens or blind lumens. A thru lumen may
be configured to allow over-the-wire delivery of the catheter or
probe. Alternatively the catheter may include a rapid exchange
sidecar at or near its distal end, consisting of a small projection
with a guidewire lumen therethrough. A lumen may be used to
slidingly receive a control shaft with a carrier assembly on its
distal end, the carrier assembly deployable to exit either the
distal end or a side hole of the flexible shaft. The advancement of
the carrier assembly, such as through a side hole, via controls on
the proximal end of the device, allows specific displacement of any
functional elements, such as electrodes, mounted on the carrier
assembly. Other shafts may be incorporated which act as a
rotational linkage as well as shafts that retract, advance or
rotate one or more components. A lumen may be used as an inflation
lumen, which permits a balloon mounted on a portion of the exterior
wall of the flexible shaft to be controllably inflated and
deflated. The balloon may be concentric or eccentric with the
central axis of the shaft, it may be a perfusion balloon, and may
include an in-line pressure sensor to avoid over-pressurizing. A
lumen may be used to receive a rotating linkage, such as a linkage
used to provide high-speed rotation of an array of ultrasound
transducers mounted near the distal end of the linkage. Each device
included in a lumen of the flexible shafts may be removable or
configured to prevent removal.
[0120] The ablation catheter of the present invention may include
one or more functional elements, such as one or more location
elements, sensors, transducers, antennas, or other functional
components. Functional elements can be used to deliver energy such
as electrodes delivering energy for tissue ablation, cardiac pacing
or cardiac defibrillation. Functional elements can be used to sense
a parameter such as tissue temperature; cardiac signals or other
physiologic parameters; contact with a surface such as the
esophageal or atrial walls of a patient; an energy parameter
transmitted from another functional element such as amplitude,
frequency; phase; direction; or wavelength parameters; and other
parameters. In a preferred embodiment of the present invention, the
ablation catheter includes multiple functional elements. In another
preferred embodiment, the ablation catheter includes a deflectable
distal end; such as a deflected end that causes one or more
functional elements to make contact with tissue. Deflection means
may include one or more of: a pull wire; an expandable cage such as
an eccentric cage; an expandable balloon such as an eccentric
balloon; an expandable cuff; a deflecting arm such as an arm which
exits the flexible catheter shaft in a lateral direction; and a
suction port.
[0121] The ablation catheter of the present invention preferably
includes a handle on its proximal end. The handle may be attached
to an outer sheath, allowing one or more inner shafts or tubes to
be controlled with controls integral to the handle such as sliding
and rotating knobs that are operable attached to those shafts or
tubes. Alternatively, the handle may be attached to a shaft that is
slidingly received by an outer sheath, such that an operator can
advance and retract the shaft by advancing and retracting the
handle and holding the sheath in a relatively fixed position. The
handle may include one or more attachment ports, such as attachment
ports which electrically connect to one or more wires; ports which
provide connection to optical fibers providing laser or other light
energies; ports which fluidly connect to one or more conduits such
as an endoflator for expanding a balloon with saline or a source of
cooling fluids; and combinations thereof. Other controls may be
integrated into the handle such as deflecting tip controls, buttons
that complete a circuit or otherwise initiate an event such as the
start of energy delivery to an ablation element. In addition, the
handle may include other functional components including but not
limited to: transducers such as a sound transducer which is
activated to alert an operator of a change is status; a visual
alert component such as an LED, a power supply such as a battery; a
lock which prevents inadvertent activation of an event such as
energy delivery; input and output devices that send and receive
signals from the interface unit of the present invention; and
combinations thereof.
[0122] The interface unit of the present invention provides energy
to the ablation elements of the ablation catheter. In preferred
embodiments, one or more ablation elements are electrodes
configured to deliver RF energy. Other forms of energy, alternative
or in addition to RF, may be delivered, including but not limited
to: acoustic energy and ultrasound energy; electromagnetic energy
such as electrical, magnetic, microwave and radiofrequency
energies; thermal energy such as heat and cryogenic energies;
chemical energy; light energy such as infrared and visible light
energies; mechanical energy and physical energy such as pressurized
fluid; radiation; and combinations thereof. The ablation elements
can deliver energy individually, in combination with or in serial
fashion with other ablation elements. The ablation elements can be
electrically connected in parallel, in series, individually, or
combinations thereof. The ablation catheter may include cooling
means to prevent undesired tissue damage and/or blood clotting. The
ablation elements may be constructed of various materials, such as
plates of metal and coils of wire for RF or other electromagnetic
energy delivery. The electrodes can take on various shapes
including shapes used to focus energy such as a horn shape to focus
sound energy, and shapes to assist in cooling such as a geometry
providing large surface area. Electrodes can vary within a single
carrier assembly, such as a spiral array of electrodes or an
umbrella tip configuration wherein electrodes farthest from the
central axis of the catheter have the largest major axis. Wires and
other flexible energy delivery conduits are attached to the
ablation elements, such as electrical energy carrying wires for RF
electrodes or ultrasound crystals, fiber optic cables for
transmission of light energy, and tubes for cryogenic fluid
delivery.
[0123] The ablation elements requiring electrical energy to ablate
require wired connections to an electrical energy power source such
as an RF power source. In configurations with large numbers of
electrodes, individual pairs of wires for each electrode may be
bulky and compromise the cross-sectional profile of the ablation
catheter. In an alternative embodiment, one or more electrodes are
connected in serial fashion such that a reduced number of wires,
such as two wires, can be attached to two or more electrodes and
switching or multiplexing circuitry are included to individually
connect one or more electrodes to the ablative energy source.
Switching means may be a thermal switch, such that as a first
electrodes heats up, a single pole double throw switch change state
disconnecting power from that electrode and attaching power to the
next electrode in the serial connection. This integral temperature
switch may have a first temperature to disconnect the electrode,
and a second temperature to reconnect the electrode wherein the
second temperature is lower than the first temperature, such as a
second temperature below body temperature. In an alternative
embodiment, each electrode is constructed of materials in their
conductive path such that as when the temperature increased and
reached a predetermined threshold, the resistance abruptly
decreased to near zero, such that power dissipation, or heat,
generated by the electrode was also near zero, and more power could
be delivered to the next electrode incorporating the above
switching means.
[0124] The interface unit of the present invention includes a user
interface including components including but not limited to: an
ultrasound monitor such as an ultrasound monitor in communication
with one or more ultrasound crystals near a temperature sensor of
an esophageal probe or ultrasound crystals within an electrode
carrier assembly of the ablation catheter; an x-ray monitor such as
a fluoroscope monitor used to measure the distance between two or
more location elements; other user output components such as lights
and audio transducers; input components such as touch screens,
buttons and knobs; and combinations thereof. In a preferred
embodiment, the interface unit provides functions in addition to
providing the energy to the ablation catheter including but not
limited to: providing a cardiac mapping function; providing cardiac
defibrillation energy and control; providing cardiac pacing energy
and control; providing a system diagnostic such as a diagnostic
confirming proper device connection; providing the calculating
function of the present invention; providing a signal processing
function such as interpreting signals received from one or more
sensors of a probe, such as an esophageal probe, and/or the
ablation catheter; providing drive signals and/or energy to one or
more functional elements of the ablation catheter; providing a
second energy type to the ablation elements of the ablation
catheter; and combinations thereof.
[0125] In a preferred embodiment, the interface unit provides an
analysis function to determine one or more system parameters that
correlate to ablation settings, the parameters including but not
limited to: an energy delivery amount; an energy delivery
frequency; an energy delivery voltage; an energy delivery current;
an energy delivery temperature; an energy delivery rate; an energy
delivery duration; an energy delivery modulation parameter; an
energy threshold; another energy delivery parameter; a temperature
threshold; an alarm threshold; another alarm parameter; and
combinations thereof. The analysis function compares a measured,
calculated or otherwise determined function to a threshold value,
such as a threshold value settable by an operator of the system. In
a preferred embodiment, the interface unit receives temperature
information from multiple sensors of the ablation catheter and/or
other body inserted devices, and the highest reading received is
compared to a temperature threshold such as a temperature threshold
determined by the location of tissue being ablated. The analysis
function includes one or more algorithms that mathematically
process information such as signals received from sensors of the
ablation catheter or other device; information entered into the
user interface of the interface unit by the operator; embedded
electronic information uploaded from the ablation catheter or other
device such as information determined during the manufacture of the
catheter or device; and combinations thereof. In a preferred
embodiment, the ablation setting determined by the analysis
function is provided to the operator via a display or other user
interface output component.
[0126] The interface unit of the present invention performs one or
more mathematical functions, signal processing functions; signal
transmission functions; and combinations thereof, to determine a
system performance (e.g. during ablation) or other system
parameter. A calculation may include a function performed by an
operator of the system such as a distance value that is entered
into the interface unit after a measurement is performed such as a
measurement made from an IVUS monitor or a fluoroscopy screen. In a
preferred embodiment, energy delivered, such as a maximum
cumulative energy, maximum peak energy or maximum average energy,
is limited by a threshold. In a preferred embodiment, when a
temperature reaches a threshold, one or more system parameters are
modified. These modifications include but are not limited to: a
threshold parameter such as an increased temperature threshold; an
alarm or alert parameter such as an audible alarm "on" state; an
energy parameter such as a parameter changing energy type or
modifying energy delivery such as switching from RF energy to
cryogenic energy or stopping energy delivery; a sensor parameter
such as a parameter which activates one or more additional sensors;
cooling apparatus parameter such as a parameter activating a
cooling apparatus; a parameter that changes the polarity of energy
delivery or the modulation of energy delivery such as a parameter
that switches from monopolar to bipolar delivery or phased
monopolar-bipolar to bipolar; and combinations thereof.
[0127] FIG. 7 is flowchart summarizing a procedure in which the
ablation catheter is employed. In step 605 the clinician selects an
appropriate patient having an arrhythmic disturbance to undergo an
ablation procedure. In step 610 the various patient parameters
(e.g., arrhythmia type) are entered into the system via the
interface unit in the manner discussed above. In step 615 the
clinician introduces the ablation catheter into the right or left
atrium of the patient, as appropriate. The electrodes of the
catheter engage the cardiac tissue and measure the electrogram in
step 620. In decision step 625 the system evaluates the
electrograms and notifies the clinician if the site should be
ablated. If the system concludes that the site should not be
ablated in step 630, the catheter is repositioned to evaluate
another site in step 635. If, on the other hand, the system
concludes that the site should be ablated in step 640, the system
loads the appropriate catheter parameters such and energy,
temperature and time. In step 650 the clinician reviews the
parameters that have been established and either agrees with them
or changes one or more of them as necessary. In step 655 ablation
is performed, after which the catheter is repositioned to evaluate
another site in step 660.
[0128] The system of the present invention preferably includes
multiple functional elements integral to the ablation catheter
and/or other system component. These functional elements may be
mounted on the outer wall of the flexible shaft of the device.
Alternatively or additionally, one or more functional elements may
be mounted to a balloon, such as a perfusion balloon, eccentric
balloon or concentric balloon and/or elements may be mounted to a
carrier assembly such as a carrier assembly that exits the distal
end or a side hole of the flexible shaft. These functional elements
may be covered with a membrane and multiple elements may be
configured in an array such as an array that is rotated within a
lumen of the flexible shaft. Functional elements may be placed on
the patient's chest, such as ECG electrodes, pacing electrodes or
defibrillation electrodes. Functional elements include but are not
limited to: sensors such as temperature sensors; transmitters such
as energy transmitting electrodes, antennas and electromagnetic
transmitters; imaging transducers; signal transmitters such as
drive signal transmitters.
[0129] Functional elements may include sensing functions such a
sensor to detect a physiologic parameter. In a preferred
embodiment, one or more functional elements are configured as
sensors to receive signals that are indicative of one or more
cardiac functions of the patient. Sensors may include but are not
limited to: an electrical signal sensor such as a cardiac
electrode; a temperature sensor such as a thermocouple; an imaging
transducer such as an array of ultrasound crystals; a pressure
sensor; a pH sensor; a blood sensor, a respiratory sensor; an EEG
sensor, a pulse oximetry sensor; a blood glucose sensor; an
impedance sensor; a contact sensor; a strain gauge; an acoustic
sensor such as a microphone; a photodetector such as an infrared
photodetector; and combinations thereof. Functional elements
alternatively or additionally include one or more transducers. The
transducer may be a location element; a transmitter such as a
transmitting antenna, an RF electrode, a sound transmitter; a
photodiode, a pacing electrode, a defibrillation electrode, a
visible or infrared light emitting diode and a laser diode; a
visualization transducer such as an ultrasound crystal; and
combinations thereof.
[0130] Numerous kit configurations are also to be considered within
the scope of this application. An ablation catheter is provided
with multiple carrier assemblies. These carrier assemblies can be
removed for the tubular body member of the catheter, or may include
multiple tubular body members in the kit. The multiple carrier
assemblies can have different patterns, different types or amounts
of electrodes, and have numerous other configurations including
compatibility with different forms of energy. Multiple sensors,
such as ECG skin electrodes may be included, such as electrodes
that attach to the interface unit of the present invention. A kit
may include one or more catheters, such as an ultrasound catheter,
which are configured to enter and extend distally in a lumen of the
ablation catheter. One or more esophageal probes may be included
such as probes with different tip or sensor configurations.
[0131] Though the ablation device has been described in terms of
its preferred endocardial and percutaneous method of use, the array
may be used on the heart during open-heart surgery, open-chest
surgery, or minimally invasive thoracic surgery. Thus, during
open-chest surgery, a short catheter or cannula carrying the
carrier assembly and its electrodes may be inserted into the heart,
such as through the left atrial appendage or an incision in the
atrium wall, to apply the electrodes to the tissue to be ablated.
Also, the carrier assembly and its electrodes may be applied to the
epicardial surface of the atrium or other areas of the heart to
detect and/or ablate arrhythmogenic foci from outside the
heart.
[0132] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims. In addition, where this application has listed
the steps of a method or procedure in a specific order, it may be
possible, or even expedient in certain circumstances, to change the
order in which some steps are performed, and it is intended that
the particular steps of the method or procedure claim set forth
here below not be construed as being order-specific unless such
order specificity is expressly stated in the claim.
* * * * *