U.S. patent application number 11/235462 was filed with the patent office on 2006-02-02 for ablation catheter with cooled linear electrode.
Invention is credited to Dale Nelson, William Penny, Jeffrey Santer, Steven D. Savage.
Application Number | 20060025763 11/235462 |
Document ID | / |
Family ID | 24575626 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060025763 |
Kind Code |
A1 |
Nelson; Dale ; et
al. |
February 2, 2006 |
Ablation catheter with cooled linear electrode
Abstract
The ablation catheter is comprised of a guiding catheter and an
inner catheter. The guiding catheter is comprised of a shaft
section which is attached to an articulating section at its distal
end and a first handle at its proximal end. The inner catheter is
comprised of an elongated central shaft, an electrode assembly
attached to the distal end of the central shaft, and a second
handle attached to the proximal end of the central shaft. The
electrode assembly is comprised of a flexible plastic catheter tube
having an outer surface, a porous tip electrode, and at least one
linear electrode carried on the outer surface of the catheter tube.
The electrode assembly is articulated to better align the electrode
assembly to the generally arcuate shape of the inner chambers of
the heart.
Inventors: |
Nelson; Dale; (Minneapolis,
MN) ; Savage; Steven D.; (Paynesville, MN) ;
Penny; William; (Arden Hill, MN) ; Santer;
Jeffrey; (Spring Lake Park, MN) |
Correspondence
Address: |
George H. Gerstman;SEYFARTH SHAW
Suite 4200
55 East Monroe Street
Chicago
IL
60603
US
|
Family ID: |
24575626 |
Appl. No.: |
11/235462 |
Filed: |
September 26, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10657647 |
Sep 8, 2003 |
|
|
|
11235462 |
Sep 26, 2005 |
|
|
|
09642202 |
Aug 21, 2000 |
6669692 |
|
|
10657647 |
Sep 8, 2003 |
|
|
|
Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 2017/003 20130101;
A61B 2018/00065 20130101; A61B 18/1492 20130101; A61B 2218/002
20130101; A61B 2018/00029 20130101; A61B 2018/00577 20130101; A61B
2018/00011 20130101; A61B 2018/1407 20130101; A61B 2018/00351
20130101 |
Class at
Publication: |
606/041 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1. An ablation catheter, which catheter comprises: a flexible
plastic catheter tube; and at least one linear electrode comprising
a tubular array of conductive metal strands carried by said
catheter tube, which catheter has a first steering mechanism; and a
guiding catheter having a lumen occupied by said ablation catheter,
said guiding catheter having a second steering mechanism.
2. The catheter of claim 1 in which said plastic catheter tube
extends through said tubular array of conductive metal strands,
said catheter tube defining a plurality of apertures to permit the
flow of cooling fluid from the lumen of the catheter tube and
through said apertures, to flow among said conductive metal
strands.
3. The catheter of claim 2 in which a porous second electrode
connects with one end of the plastic catheter tube.
4. The catheter of claim 1 in which a porous second electrode
connects with one end of the plastic catheter tube.
Description
[0001] This is a division of application Ser. No. 10/657,647, filed
Sep. 8, 2003, which is a division of application Ser. No.
09/642,202 filed Aug. 21, 2000.
FIELD OF THE INVENTION
[0002] This invention relates generally to a cardiac catheter used
for performing cardiovascular procedures on the heart. More
particularly, this invention relates to an ablation catheter used
predominantly for treating cardiac arrhythmias.
BACKGROUND OF THE INVENTION
[0003] Radio frequency ablation (RFA) has become a common treatment
for treating specific cardiac arrhythmias. Portions of the heart
sometimes form alternative conduction pathways which interfere with
the normal conduction of the electrical signals which regulate the
beating of the heart thereby causing some cardiac arrhythmias to
occur. In order to remove these alternative conduction pathways,
the heart is first mapped through catheter mapping procedures in
order to find where these alternative conduction pathways are
located, and then RFA is used to prevent these areas of the heart
from disrupting the normal conduction patterns of the heart.
[0004] RFA typically involves the use of a specialized ablation
catheter which is positioned at the site of the alternative
conduction pathway. Radio frequency (RF) waves are then typically
delivered through the ablation catheter and onto the alternative
conduction pathway. The radio frequency waves create heat at the
site of the alternative conduction pathway creating a lesion which
destroys the tissues forming the alternative conduction
pathways.
[0005] Ablation catheters have been developed in order to deliver
radio frequency waves at the site of the abnormal pathway. While
some of these prior art ablation catheters are well suited for
particular procedures, the ability of these prior art ablation
catheters to perform a variety of procedures effectively have been
limited due to a number structural constraints which are
necessitated by the spatial and physiological requirements of the
applications in which these ablation catheters are to be used.
Size, flexibility, and maneuverability are common restraints which
have previously prevented more effective ablation catheter
designs.
[0006] One drawback to the prior art is their inability to make a
variety of lesions. There are typically two types of lesions which
are generated by ablation catheters. One type of lesion is a focal
lesion where the RF wave is concentrated at a point. Typically, the
prior art is limited to making focal lesions. A tip electrode
carried on the distal tip of an ablation catheter is preferably
used for making focal lesions. However, there are a variety of
procedures in which linear lesions are preferred requiring that the
RF energy be delivered along a line. There are prior art ablation
catheters which are capable of creating linear lesions; however,
these prior art ablation catheters are not particularly suited for
making focal lesions. A linear electrode is preferably utilized for
making linear lesions. Although tip electrodes can also be used
utilized for making linear lesions, the use of tip electrodes to
make linear lesions can be significantly more difficult and time
consuming.
[0007] The maneuverability of the prior art ablation catheters also
limit their effectiveness. The ablation catheters are typically
utilized within the interior chambers of the heart. The precise
placement of the electrodes onto the site to which the RF waves are
to be delivered and the sufficiency of the contact between an
electrode and the site significantly impacts the effectiveness of
the treatment. Linear electrodes, and especially longer linear
electrodes, tend to be stiffer, making it more difficult for them
to maneuver and to conform to the generally arcuate shape of the
interior walls of the heart.
[0008] Another problem common amongst the prior art ablation
catheters is the formation of coagulum around the electrode during
ablation. The heat generated by the RFA sometimes causes the
electrode to overheat causing the blood surrounding the electrode
to coagulate on the electrode. As the coagulum collects on the
electrode, the impedance between the electrode and the site to
which the RF wave is applied increases, thereby reducing the
effectiveness of the electrode. As a result it is often necessary
to stop the RFA in order to remove the coagulum from the
electrode.
[0009] Accordingly, it is an object of this invention to provide an
ablation catheter which is capable of generating both focal lesions
and linear lesions while having the appropriate size, flexibility
and maneuverability to enable it to be used effectively in a
variety of RFA procedures.
[0010] Accordingly, it is also an object of this invention to
provide for an ablation catheter with a linear electrode which is
easily maneuverable and conforms readily to the arcuate shape of
the interior of the heart while still having the appropriate size,
flexibility and maneuverability to enable the ablation catheter to
be used effectively in a variety of RFA procedures.
[0011] Accordingly, it is also a further object of this invention
to provide an ablation catheter with a means for cooling the
electrode in order to reduce the rate at which the coagulum builds
up on the surface of an electrode while still having the
appropriate size, flexibility and maneuverability to enable it to
be used effectively in most RFA procedures.
[0012] Other objects and advantages of the invention will become
apparent as the description proceeds.
[0013] To achieve these objectives, and in accordance with the
purposes of the present invention the following ablation catheter
is presented. As will be described in greater detail hereinafter,
the present invention provides the aforementioned and employs a
number of novel features that render it highly advantageous over
the prior art.
SUMMARY OF THE INVENTION
[0014] In accordance with an illustrative embodiment of the present
invention, an ablation catheter is provided which comprises two
major components, an articulating guiding catheter and an inner
articulating catheter disposed therein. The guiding catheter is
typically inserted into the vascular system and is guided and
manipulated through the vascular system until it reaches the
appropriate chamber of the heart. The inner catheter is disposed
within the guiding catheter until a desired location in the heart
is reached. At that point the inner catheter is then extended
beyond the guiding catheter allowing the inner catheter to more
precisely position itself onto a treatment site.
[0015] In an illustrative embodiment, the guiding catheter is
comprised of a shaft section which is attached to an articulating
section at its distal end and a first handle at its proximal end.
The inner catheter is comprised of an elongated central shaft, an
electrode assembly attached to the distal end of the central shaft,
and a second handle attached to the proximal end of the central
shaft.
[0016] In one embodiment, the electrode assembly is comprised of a
flexible plastic catheter tube having an outer surface, a porous
tip electrode, and at least one linear electrode carried on the
outer surface of the catheter tube. The catheter tube is used to
provide axial and radial stability to the electrode assembly and to
provide a conduit to the electrode assembly. Fluid is distributed
to the linear electrode and the porous tip electrode through a
plurality of apertures extending from the inner surface of the
catheter tube to the outer surface of the catheter tube.
[0017] The linear electrode is utilized in order to make linear
lesions in the heart tissue. In one embodiment, the linear
electrode is comprised of a tubular array of conductive metal
strands carried on the outer surface of the catheter tube, the
conductive strands extending along the catheter tube in a plurality
of directions relative to the longitudinal axis of the catheter
tube. In one embodiment, the tubular array of metal strands is a
wound helical coil. In an alternate embodiment, the tubular array
of metal strands is arranged in a braided construction. The porous
tip electrode is located at the distal end of the electrode
assembly. The tip electrode provides a means for creating lesions
concentrated at particular points in the heart, otherwise called
focal lesions.
[0018] Articulation of the electrode assembly is utilized in order
to better align the linear electrode to the generally arcuate shape
of the inner chambers of the heart. One means for articulating the
electrode assembly is by extending a pull wire through the inner
catheter and attaching it to the distal tip of the catheter tube.
An alternate means for articulating the electrode assembly is
achieved by running the pull wire through the inner catheter, then
having the wire run externally along the linear electrode, and then
finally attaching the pull wire to the distal tip of the electrode
assembly. A second alternate means for articulating the electrode
assembly is achieved through the use of a memory shaped tube which
is thermally activated to conform to a predetermined shape upon
reaching body temperature.
[0019] A more detailed explanation of the invention is provided in
the following description and claims, and is illustrated in the
accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a planar view of an ablation catheter embodying
features in accordance with the present invention.
[0021] FIG. 2 is a side section view of the distal portion of the
ablation catheter shown in FIG. 1 providing an enlarged view of the
electrode assembly.
[0022] FIG. 3 is a side view of a linear electrode assembly having
helically wound coils.
[0023] FIG. 4 is a side view of a linear electrode assembly having
a braided construction.
[0024] FIG. 5 is a side section view of a linear electrode assembly
utilizing coils made of hypodermic tubing.
[0025] FIG. 6 is a side section view of a linear electrode assembly
utilizing coils made of a combination of hypodermic tubing and
solid wire.
[0026] FIG. 7 is a side section view of a linear electrode assembly
with added monitoring capabilities.
[0027] FIG. 8 is side section view of a linear electrode assembly
having an articulating means.
[0028] FIG. 9 is a side section view of a linear electrode assembly
having an exterior articulating means.
[0029] FIG. 10 is side section view of a linear electrode assembly
having a thermally activated alternative articulating means.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0030] Referring to FIG. 1, an ablation catheter is comprised of
two major components, an articulating guiding catheter 10 and an
inner articulating catheter 50 disposed therein. The guiding
catheter 10 is typically inserted into the vascular system and is
guided and manipulated through the vascular system until it reaches
the appropriate chamber of the heart. Once positioned within the
heart, the guiding catheter 10 provides a uniform conduit for
introducing the inner catheter 50 into the chambers of the heart.
The inner catheter 50 is disposed within the guiding catheter and
typically travels within the guiding catheter until a desired
location in the heart is reached. At that point the inner catheter
50 is then extended beyond the guiding catheter 10 allowing the
inner catheter 50 to more precisely position itself onto a
treatment site.
[0031] The guiding catheter 10 is comprised of a shaft section 12
having an articulating section 19 at its distal end and a first
handle 14 attached at its proximal end. A plurality of ring
electrodes 13 is carried on the distal end of the guiding catheter
10. The ring electrodes 13, when in contact with the heart tissue,
are able to take measurements of endocardial potentials. The shaft
12 is comprised of preferably constructed of an inner and outer
layer of plastic which encapsulate a braided metal, but other means
of constructing the shaft would work suitably with the present
invention. The handle 14 is comprised of a first mechanism for
articulating 17 the articulating section 19, an interface for
electricity 15, a first fluid interface 16, and an interface for
inserting 18 the inner articulating catheter 50. It should be
understood that various additional interfaces can be incorporated
in the guiding catheter.
[0032] The inner catheter 50 is comprised of an elongated central
shaft 53, an electrode assembly 54 attached to the distal end of
the central shaft, and a second handle 56 attached to the proximal
end of the central shaft 53. The inner catheter is removably
disposed within the guiding catheter, allowing the inner catheter
to be removed and reinserted into the guiding catheter a number of
times during a medical procedure.
[0033] The second handle 56 is comprised of a second mechanism 55
for articulating the distal end of the inner catheter 50, an RF
interface 58 for connecting the inner catheter 50 to an RF
generator, and a second fluid inter face 57. The second fluid
interface is connected to a separate lumen within the inner
catheter that extends to the distal end of the inner catheter,
providing a conduit for fluids from the second fluid interface to
the electrode assembly 54. It should also be understood that
various additional interfaces can be incorporated in the inner
catheter design.
[0034] Referring to FIG. 2, the electrode assembly 54 is comprised
of a flexible plastic catheter tube 60 having an outer surface, a
porous tip electrode 52 attached on the outer surface at the distal
end of the catheter tube 60, and at least one linear electrode 61
carried on the outer surface of the catheter tube 60.
[0035] The catheter tube 60 is used to provide axial and radial
stability to the electrode assembly and to provide a conduit for
the flow of fluid to cool the linear electrode 61 and tip electrode
52. The catheter tube 60 is preferably a thin walled, non
conductive, single lumen tube constructed of a flexible polymer
plastic. Fluid received from the second fluid interface flows
through the inner catheter 50 to the catheter tube 60. There the
fluid is distributed to the linear electrode 61 and the tip
electrode 52 through a plurality of apertures 62 extending from the
inner surface of the catheter tube 60 to the outer surface of the
catheter tube 60. The apertures 62 are spaced to allow for uniform
flow of fluid to all parts of the linear electrode 61 and the
porous tip electrode 52. During a RFA procedure, "hot spots" may
develop on sections of an electrode if there is not enough fluid
flow reaching the area. Since fluid is being uniformly delivered to
all sections of the linear electrode 61 and tip electrode 52
through the catheter tube 60, the chances for a "hot spot" to
develop is minimized or eliminated.
[0036] The linear electrode 61 is utilized in order to make linear
lesions in the heart tissue. The linear electrode can be attached
either to the elongated central shaft 53 or the catheter tube 60.
Conductive wire connects the linear electrode to the RF interface
58. The linear electrode 61 is comprised of a tubular array of
conductive metal strands carried on the outer surface of the
catheter tube 60, the conductive strands extending along the
catheter tube 60 in a plurality of directions relative to the
longitudinal axis of the catheter tube 60. The conductive strands
are preferably made from rounded or flat solid wire 311, or
hypodermic tubing 300, or a combination of both as shown in FIG. 5
and 6. Hypodermic tubing has the advantage of enabling the linear
electrode 61 to be cooled by circulating fluid within the
hypodermic tubing as well as from fluid flow from the apertures 62
in the catheter tube 60.
[0037] Referring to FIG. 3, in one embodiment, the tubular array of
metal strands is a wound helical coil 200. The spacing between
loops in the coil is varied in order to achieve different
physiological effects. The loops can be wound tightly with each
loop in the coil in contact with its neighboring loops as in FIG. 3
or the loops can be wound loosely as in FIG. 5. A tight spacing of
the loops in the coil will enable the linear electrode 61 to
deliver a higher energy density, but may increase the stiffness of
the linear electrode and may increase parasitic power loss. Greater
spacing between the loops in the coil will provide more flexibility
and less power loss. Referring to FIG. 4 in an alternate
embodiment, the tubular array of metal strands is arranged in a
braided construction 201.
[0038] Referring to FIG. 7, in order to add more precise
electrocardiac mapping capability, additional monitoring electrodes
401 can be placed onto the linear electrode 61. The monitoring
electrodes would preferably rest on an insulating sleeve 402
electrically isolated from the linear electrode. The monitoring
electrodes are preferably cylindrical metallic bands 401. The
metallic bands 401 are coupled to physiological monitoring
equipment through a wire 403 extending from the metallic band and
through the inner catheter.
[0039] Referring to FIG. 2, the porous tip electrode 52 is located
at the distal end of the electrode assembly 54. The porous tip
electrode 52 provides the inner catheter 50 a means for creating
lesions concentrated at particular points in the heart, otherwise
called focal lesions. RF energy is supplied to the porous tip
electrode through a conductor wire 65 which extends from the tip
electrode 52 to the RF interface 58 in the second handle 56.
[0040] Referring to FIGS. 1, 2, 8 and 9, articulation of the
electrode assembly is utilized in order to better align the linear
electrode 61 to the generally arcuate shape of the inner chambers
of the heart. One means for articulating the electrode assembly is
by extending a pull wire 501 from the second mechanism for
articulating 55 through the inner catheter 50 and attaching it to
the distal tip of the catheter tube 60. Creating a pulling motion
on the pull wire 501 by means of the second mechanism for
articulating 55 will cause the distal end of the catheter tube 60
to deflect towards the direction of the pulling motion. A stiffener
can be used in this configuration in order to return the electrode
assembly 54 back to its original position.
[0041] Referring to FIG. 9, an alternate means for articulating the
electrode assembly is achieved by running the pull wire 501 from
the second mechanism for articulating 55 through the inner catheter
50, then having the wire run externally along the linear electrode,
and then finally attaching the pull wire 501 to the distal tip of
the electrode assembly 54.
[0042] Referring to FIG. 10, a second alternate means for
articulating the electrode assembly is achieved through the use of
a memory shaped tube 702 which is thermally activated to conform to
a predetermined shape. Nitinol.TM. tubing or other materials having
thermally activated shape memory characteristics can be used for
the catheter tube 60. The catheter tube would remain relatively
erectile during the positioning of the electrode assembly 54, but
once the RF energy is applied, the thermal energy would cause the
Nitinol.TM. tubing to deflect into an arcuate shape. This means for
articulation has the advantage of not requiring the use of pull
wires 501 or mechanisms for articulating.
[0043] It can be seen that the ablation catheter which has been
provided above allows for greater choice in the type of lesions
which can be made, also allows for greater maneuverability, more
precise placement, and better cooling of the electrodes. Although
illustrative embodiments of the invention have been shown and
described, it is not intended that the novel device be limited
thereby. It is to be understood that this novel invention may be
susceptible to modifications and variations that are within the
scope and fair meaning of the accompanying claims and drawings.
* * * * *