Title: Method and system for atrial defibrillation
Abstract: A method and system for atrial defibrillation in a patient are provided. The method comprises introducing into the patient a catheter comprising an elongated catheter body having proximal and distal ends and at least one lumen therethrough, and a basket-shaped electrode assembly at the distal end of the catheter body. The electrode assembly has proximal and distal ends and comprises a plurality of spines connected at their proximal and distal ends, each spine comprising an elongated spine electrode along its length. The electrode assembly has an expanded arrangement wherein the spines bow radially outwardly and a collapsed arrangement wherein the spines are arranged generally along the axis of the catheter body. The method further comprises introducing the electrode assembly into the heart of the patient and applying defibrillation energy to the tissue through one or more of the elongated electrodes. The system comprises a catheter as described above in combination with an external defibrillator electrically connected to the catheter.
Patent Number: 6,980,858 Issued on 12/27/2005 to Fuimaono, et al.
| Inventors:
|
Fuimaono; Kristine B. (Covina, CA);
Moaddeb; Shahram (Irvine, CA)
|
| Assignee:
|
Biosense Webster, Inc. (Diamond Bar, CA)
|
| Appl. No.:
|
040977 |
| Filed:
|
December 31, 2001 |
| Current U.S. Class: |
607/5 |
| Intern'l Class: |
A61N 001/36.5 |
| Field of Search: |
607/5,6,122,123,129,128
600/374,375,518,522
|
References Cited [Referenced By]
U.S. Patent Documents
| 5010894 | Apr., 1991 | Edhag.
| |
| 5165403 | Nov., 1992 | Mehra.
| |
| 5391200 | Feb., 1995 | KenKnight et al.
| |
| 5397341 | Mar., 1995 | Hirschberg et al.
| |
| 5423864 | Jun., 1995 | Ljungstroem.
| |
| 5449381 | Sep., 1995 | Imran.
| |
| 5531779 | Jul., 1996 | Dahl et al.
| |
| 5628313 | May., 1997 | Webster, Jr.
| |
| 5855592 | Jan., 1999 | McGee et al.
| |
| 5928269 | Jul., 1999 | Alt.
| |
| 6101410 | Aug., 2000 | Panescu et al.
| |
Other References
European Search Report dated Oct. 24, 2003 from corresponding European Application
No. EP02259007.9.
|
Primary Examiner: Manuel; George
Attorney, Agent or Firm: Christie, Parker & Hale, LLP
Claims
1. A method for atrial defibrillation in a patient in need thereof comprising:
introducing into the patient a catheter comprising:
an elongated catheter body having proximal and distal ends and at least one lumen
therethrough, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly having proximal and distal ends and comprising a plurality of
spines connected at their proximal and distal ends, each spine comprising an elongated
spine electrode along its length, the electrode assembly having an expanded arrangement
wherein the spines bow radially outwardly and a collapsed arrangement wherein the
spines are arranged generally along the axis of the catheter body;
introducing the electrode assembly into the heart of the patient; and
applying defibrillation energy to tissue of the heart through one or more of
the elongated electrodes, wherein defibrillation energy is delivered to the heart
tissue through only a portion of the spine electrodes, leaving one or more spine
electrodes through which defibrillation energy is not delivered to the heart tissue,
wherein the spine electrodes through which defibrillation energy is delivered are
shorted together.
2. The method of claim 1, wherein defibrillation energy is delivered to the heart
tissue through at least half of the spine electrodes.
3. The method of claim 1, wherein the one or more spine electrodes through which
defibrillation energy is not delivered to the heart tissue are shorted together
and function as a return electrode for the defibrillation energy.
4. A system for atrial defibrillation in a patient comprising:
a catheter comprising:
an elongated catheter body having proximal and distal ends, a length of about
90 cm, and at least one lumen therethrough, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly having proximal and distal ends and comprising a plurality of
spines connected at their proximal and distal ends, each spine comprising an elongated
spine electrode along its length, the electrode assembly having an expanded arrangement
wherein the spines bow radially outwardly and a collapsed arrangement wherein the
spines are arranged generally along the axis of the catheter body;
an external defibrillator electrically connected to the catheter; and
an interface switch box that connects the external defibrillator to the catheter
and that permits the selection of the spine electrodes through which defibrillation
energy is to be delivered.
5. The system of claim 4, further comprising an ECG recorder electrically connected
to the catheter through the interface switch box.
6. The system of claim 5, wherein the catheter further comprises one or more
ring electrodes mounted at or near the distal end of the catheter body.
7. The system of claim 4, further comprising an external pacer electrically connected
to the catheter through the interface switch box.
8. The system of claim 7, wherein the catheter further comprises a tip electrode
mounted at the distal end of the electrode assembly.
9. The system of claim 4, wherein each spine comprises a flexible wire having
proximal and distal ends, wherein at least a portion of the flexible wire forms
the elongated electrode.
10. The system of claim 4, wherein the electrode assembly comprises at least
three spines.
11. The system of claim 4, wherein the electrode assembly comprises at least
five spines.
12. A system for atrial defibrillation in a patient comprising:
a catheter comprising:
an elongated catheter body having proximal and distal ends, a length of at least
about 90 cm, and at least one lumen therethrough, the catheter body having one
or more ring electrodes mounted at or near its distal end, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly having proximal and distal ends and comprising at least three
spines connected at their proximal and distal ends, each spine comprising an elongated
spine electrode along its length, wherein each spine electrode has a length ranging
from about 30 mm to about 80 mm, the electrode assembly having an expanded arrangement
wherein the spines bow radially outwardly and a collapsed arrangement wherein the
spines are arranged generally along the axis of the catheter body, the electrode
assembly having a tip electrode mounted at its distal end;
an external defibrillator connected to the catheter;
an interface switch box that connects the external defibrillator to the catheter
and that permits the selection of spine electrodes through which defibrillation
energy is to be delivered;
an ECG recorder electrically connected to the catheter through the interface
switch box; and
an external pacer electrically connected to the catheter through the interface
switch box.
13. A method for atrial defibrillation in a patient in need thereof comprising:
introducing into the patient a catheter comprising:
an elongated catheter body having proximal and distal ends and at least one lumen
therethrough, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly having proximal and distal ends and comprising a plurality of
spines connected at their proximal and distal ends, each spine comprising an elongated
spine electrode along its length, the electrode assembly having an expanded arrangement
wherein the spines bow radially outwardly and a collapsed arrangement wherein the
spines are arranged generally along the axis of the catheter body;
introducing the electrode assembly into the heart of the patient; and
applying defibrillation energy to the tissue of the heart through selected ones
of the spine electrodes, leaving one or more spine electrodes through which defibrillation
energy is not delivered to the heart tissue, wherein the one or more spine electrodes
through which defibrillation energy is not delivered to the heart tissue are shorted
together and function as a return electrode for the defibrillation energy.
14. A method for atrial defibrillation in a patient in need thereof comprising:
introducing into the patient a catheter comprising:
an elongated catheter body having proximal and distal ends and at least one lumen
therethrough, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly comprising a plurality of spine electrodes and having an expanded
arrangement and a collapsed arrangement;
introducing the electrode assembly into the heart of the patient; and
applying defibrillation energy to tissue of the heart through selected ones of
the spine electrodes, leaving one or more spine electrodes through which defibrillation
energy is not delivered to the heart tissue, wherein the spine electrodes through
which defibrillation energy is delivered are shorted together.
15. A method for atrial defibrillation in a patient in need thereof comprising:
introducing into the patient a catheter comprising:
an elongated catheter body having proximal and distal ends and at least one lumen
therethrough, and
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly comprising a plurality of spine electrodes and having an expanded
arrangement and a collapsed arrangement;
introducing the electrode assembly into the heart of the patient; and
applying defibrillation energy to tissue of the heart through selected ones of
the spine electrodes, leaving one or more spine electrodes through which defibrillation
energy is not delivered to the heart tissue, wherein the one or more spine electrodes
through which defibrillation energy is not delivered to the heart tissue are shorted
together and function as a return electrode for the defibrillation energy.
Description
BACKGROUND OF THE INVENTION
Atrial fibrillation (also called "AF" or "A Fib") is the most common abnormal
heart rhythm. It is a very fast, uncontrolled heart rhythm caused when the upper
changes of the heart (the atria) quiver instead of beating. During atrial fibrillation,
the upper chambers of the heart beat between 350 and 600 times per minute, causing
the pumping function of the upper chambers to not work properly. As a result, blood
is not completely emptied from the heart's chambers, causing it to pool and sometimes
clot. In about 5 percent of patients with atrial fibrillation, clotted blood dislodges
from the atria and results in a stroke. The American Heart Association estimates
that, in the United States, atrial fibrillation is responsible for over 70,000
strokes each year.
Various methods exist for treating atrial fibrillation. One such method is
cardiac ablation, which is a medical procedure performed to prevent abnormal electrical
impulses from ever beginning in the first place. In an ablation procedure, the
electrophysiologist first pinpoints the precise area in the heart at which the
abnormal signals start through a mapping procedure. The electrophysiologist then
eliminates the small area of tissue that is causing the arrhythmia by ablating
that tissue. With a procedure known as AV nodal ablation, the electrophysiologist
ablates the AV node, keeping the abnormal impulses from traveling to the heart's
lower chambers. A pacemaker is used to regulate the heartbeat after this therapy.
Another method for treating atrial fibrillation is AF suppression. With this
method, an implanted pacemaker stimulates the heart in a way that preempts any
irregular rhythms.
In about half of the atrial fibrillation cases, medication can be effective in
controlling the rate at which the upper and lower chambers of the heart beat. Standard
medications used for atrial fibrillation include beta-blockers (such as carvedilol
and propanolol) and calcium-channel clockers (like verapamil and diltiazem), which
slow the heart rate. Digoxin, which slows the heart rate through the AV node, thereby
decreasing the rate at which the electrical impulses conduct from the upper to
lower chambers, can also be used. Other medications, such as disopyramide, flecainide,
procainamide and sotalol, are used to chemically convert AF back to normal rhythm.
In many cases, anticoagulants, such as heparin, are also used to "thin" the blood
to reduce the risk of clot formation.
Cardioversion can also be used to treat atrial fibrillation. Cardioversion
involves changing an abnormal heart rate back to a normal one. Cardioversion can
be done using medication or electricity. In electrical cardioversion, energy is
applied to the heart to "jolt" it out of atrial fibrillation. Two types of electrical
cardioversion exist, external and internal. For external cardioversion, two external
paddles are placed on the patient's chest or on the chest and back. A high-energy
electrical shock is sent through the patches and through the body to the heart.
The energy shocks the heart out of atrial fibrillation and back into normal rhythm.
Internal cardioversion uses a similar approach, but instead of paddles being
placed on the outside of the body, a catheter is inserted through a vein to the
heart. The electrical energy is delivered through the catheter to the inside of
the heart to stop the atrial fibrillation. Internal cardioversion has met with
high success and provides a desirable alternative to external cardioversion. Notably,
internal cardioversion requires far lower energy levels than external cardioversion
and thus can provide a more comfortable procedure for patients by eliminating the
trauma, discomfort and risk associated with high-energy external cardioversion.
Electrophysiologists are developing clinical techniques targeted
toward the use of catheter-based ablation as a therapeutic alternative in the treatment
of focally induced atrial fibrillation. An important component of these efforts
are methods for quickly and reliably inducing and converting the AF arrhythmia
while the patient is in the electrophysiology lab.
SUMMARY OF THE INVENTION
The present invention is directed to an method and system for performing internal
cardioversion utilizing a catheter having a basket-shaped electrode assembly.
In one embodiment, the invention is directed to a method for atrial defibrillation
in a patient in need thereof comprising introducing into the patient a catheter.
The catheter comprises an elongated catheter body having proximal and distal ends
and at least one lumen therethrough, and a basket-shaped electrode assembly at
the distal end of the catheter body. The electrode assembly has proximal and distal
ends and comprises a plurality of spines connected at their proximal and distal
ends, each spine comprising an elongated spine electrode along its length. The
electrode assembly has an expanded arrangement wherein the spines bow radially
outwardly and a collapsed arrangement wherein the spines are arranged generally
along the axis of the catheter body. The method further comprises introducing the
electrode assembly into the heart of the patient and applying defibrillation energy
to the tissue through one or more of the elongated electrodes.
In another embodiment, the invention is directed to a system for atrial defibrillation
in a patient. The system comprises a catheter as described above in combination
with an external defibrillator electrically connected to the catheter.
In a particularly preferred embodiment, the invention is directed to a system
for atrial defibrillation in a patient comprising a catheter. The catheter comprises
an elongated catheter body having proximal and distal ends, a length of at least
about 90 cm, and at least one lumen therethrough. The catheter body has one or
more ring electrodes mounted at or near its distal end. The catheter further comprises
a basket-shaped electrode assembly at the distal end of the catheter body, the
electrode assembly having proximal and distal ends and comprising at least three
spines connected at their proximal and distal ends. Each spine comprises an elongated
spine electrode along its length, wherein each spine electrode has a length ranging
from about 30 mm to about 80 mm. The electrode assembly has an expanded arrangement
wherein the spines bow radially outwardly and a collapsed arrangement wherein the
spines are arranged generally along the axis of the catheter body. The electrode
assembly has a tip electrode mounted at its distal end. The system further comprises
an external defibrillator electrically connected to the catheter, an interface
switch box that connects the external defibrillator to the catheter and that permits
the selection of spine electrodes through which defibrillation energy is to be
delivered, an ECG recorder electrically connected to the catheter through the interface
switch box, and an external pacer electrically connected to the catheter through
the interface switch box.
The inventive method and system offer several advantages over existing methods
and systems. First, the basket-shaped electrode assembly has a larger surface area
than conventional catheters and permits better current distribution to cover a
majority of both atria during treatment. The larger surface area also reduces the
impedance and energy requirements. The ability of the electrode assembly to expand
and contract permits adjustability of the electrodes and better contact with tissue.
The electrode assembly can also be placed within the pulmonary artery for better
current distribution in the left atrium.
DESCRIPTION OF THE DRAWINGS
These and other features and advantages of the present invention will be better
understood by reference to the following detailed description when considered in
conjunction with the accompanying drawings wherein:
FIG. 1 is a perspective view of a catheter according to the invention.
FIG. 2 is a close-up perspective view of the basket-shaped electrode assembly
and the distal end of the catheter body of the catheter shown in FIG. 1.
FIG. 3 is a side cross-sectional view of the control handle of the catheter
shown in FIG. 1
FIG. 4 is a perspective view of an alternative basket-shaped electrode assembly
in accordance with the invention.
FIG. 5 is a schematic diagram of a system in accordance with the invention.
FIG. 6 is a side cross-sectional view of the distal end of a catheter according
to the invention showing an exemplary steering mechanism.
DETAILED DESCRIPTION OF THE INVENTION
The invention is directed to a method and system for atrial defibrillation using
a catheter having a basket-shaped electrode array at its distal end. As shown in
FIG. 1, the catheter
10 comprises an elongated catheter body
12 having
proximal and distal ends, a connector
15 and a control handle
16
at the proximal end of the catheter body, and a basket-shaped electrode assembly
18 mounted at the distal end of the catheter body
12.
In accordance with the invention, the catheter body
12 comprises an elongated
tubular construction having a single, axial or central lumen (not shown), but can
optionally have multiple lumens if desired. The catheter body
12 is flexible,
i.e., bendable, but substantially non-compressible along its length. The catheter
body
12 can be of any suitable construction and made of any suitable material.
A presently preferred construction comprises an outer wall made of polyurethane
or PEBAX® (polyether block amide). The outer wall comprises an imbedded braided
mesh of stainless steel or the like to increase torsional stiffness of the catheter
body
12 so that, when the control handle
16 is rotated, the distal
end of the catheter body will rotate in a corresponding manner.
The length of the catheter, i.e, the catheter body
12 and mapping assembly
18 excluding the connector
15 and control handle
16, is preferably
at least about 90 cm, more preferably from about 110 cm to about 120 cm, still
more preferably about 115 cm. The outer diameter of the catheter body
12
is not critical, but is preferably no more than about 8 french, more preferably
7 french. Likewise the thickness of the outer wall is not critical, but is preferably
thin enough so that the central lumen can accommodate a puller wire, lead wires,
sensor cables and any other wires, cables or tubes. An example of a catheter body
construction suitable for use in connection with the present invention is described
and depicted in U.S. Pat. No. 6,064,905, the entire disclosure of which is incorporated
herein by reference.
The basket-shaped electrode assembly
18 is mounted to the distal end of
the catheter body
12. As shown in FIGS. 1 and 2, the basket-shaped electrode
assembly
18 comprises five spines
20 or arms. The spines
20
are all attached, directly or indirectly, to each other at their proximal and distal
ends, and to the catheter body
12 at their proximal ends. The basket-shaped
electrode assembly
18 is moveable between an expanded position and a contracted
position, so that, in the expanded position the spines
20 are bowed outwardly
and in the contracted position the spines are generally straight and arranged generally
along the axis of the catheter body. As will be recognized by one skilled in the
art, the number of spines
20 can vary as desired depending on the particular
application, so that the assembly has at least two spines, preferably at least
three spines, more preferably at least five spines, and as many as eight or more spines.
Expansion and contraction of the electrode assembly
18 can be accomplished
by any suitable means. For example, as shown in FIG. 2, the assembly
18
includes an expander
22 attached at its distal end to the distal ends of
the spines
20 with the spines mounted, preferably generally evenly-spaced,
around the expander so that the expander forms the axis of the electrode assembly.
The expander
22 is generally coaxial with the catheter body
12. The
expander
22 extends through the catheter body and out the proximal end of
the catheter body, preferably into a suitable control handle
16, as discussed
further below. The expander
22 is not connected to the catheter body
12,
so that longitudinal movement of the expander relative to the catheter body results
in expansion and contraction of the electrode assembly
18.
The expander
22 can comprise a wire, such as a Nitinol wire, that optionally
extends through a non-conductive tubing (not shown) outside of the catheter body
12. Alternatively, the expander
22 can comprise a flexible tubing
having a lumen (not shown) extending through its entire length. The lumen permits
a guidewire to extend through the entire length of the catheter for introduction
of the catheter into the body and so that the electrode assembly
18 can
be removed and later reintroduced to the same position, if desired. In a preferred
embodiment, the expander
22 comprises braided polyimide tubing, i.e., tubing
having inner and outer layers of polyimide with a braided stainless steel mesh
therebetween, as is generally known in the art. A more detailed description of
a catheter having a basket-shaped electrode assembly with such an expander is disclosed
in copending application entitled "BASKET CATHETER WITH MULTIPLE LOCATION SENSORS,"
filed on Dec. 14, 2001, the disclosure of which is incorporated herein by reference.
Each spine
20 comprises a flexible wire
24 that forms an elongated
spine electrode
25 along at least a portion of its length. The elongated
electrode
25 preferably has a length ranging from about 10 mm to about 100
mm, more preferably from about 30 mm to about 80 mm, still more preferably from
about 50 to about 60 mm. In a preferred embodiment, the flexible wires
24
each comprise a flat or round Nitinol wire. The flexible wires
24 are insulated
from one another at their proximal and distal ends. In the depicted embodiment,
each wire
24 has non-conductive coverings
26 at its proximal and
distal ends, with the remainder being exposed to form the spine electrode
25.
As would be recognized by one skilled in the art, the elongated spine electrodes
25 could have other suitable designs such that the are of sufficient length.
For example, the flexible wires
24 could be covered along their entire length
with a non-conductive covering
26, with an elongated electrode then placed
over the non-conductive covering.
In a preferred embodiment, the distal ends of the spines
20 are connected
and covered by a plastic, preferably polyurethane, cap
28. If desired, the
distal ends of the spines
20 can be held in place within the cap
28
using polyurethane glue or the like. A tip electrode
30 is mounted on the
distal end of the plastic cap
28, preferably for use as a pacing electrode,
as discussed in more detail below. Alternatively, the tip electrode
30 can
be used as a mapping electrode. The tip electrode
30 can comprise any suitable
conductive metal, such as gold or platinum, and preferably an alloy of platinum
and iridium.
Each of the spine electrodes
25 and tip electrode
30 is electrically
connected to a suitable source of energy, as discussed further below, by an electrode
lead wire
32. An electrode lead wire
32 can be attached to the spine
electrodes
25 and tip electrode
30 by any suitable means, preferably
by solder of the like. Each electrode lead wire
32 attached to a spine electrode
25 is attached to the proximal end of the corresponding electrode, extends
through a lumen in the catheter body
12 and is attached to the connector
17. The lead wire
32 for the tip electrode
30 is attached
to the tip electrode
30, extends through a lumen in the expander
22,
extends through the catheter body
12, and is attached at its proximal end
to the connector
17. Each lead wire
32 is attached to its corresponding
spine electrode
25 or tip electrode
30 by any suitable method, preferably
solder or the like.
In the depicted embodiment, four ring electrodes
34 are mounted along
the
distal end of the catheter body
12. Each ring electrode
34 preferably
comprises a ring of platinum, gold or a combination of platinum and iridium. The
ring electrodes
34 can be used for pacing, for detecting electrical signals
before, during or after defibrillation [please confirm], or for a return electrode
for defibrillation, as discussed further below. As would be recognized by one skilled
in the art, the presence and number of ring electrodes
34 can vary depending
on the particular application.
An electrode lead wire
32 is attached to each ring electrode
34
by any suitable method. A preferred method for attaching a lead wire
32
to a ring electrode
34 involves first making a small hole through the outer
wall of the catheter body
12. Such a hole can be created, for example, by
inserting a needle through the wall of the catheter body
12 and heating
the needle sufficiently to form a permanent hole. The lead wire
32 is then
drawn through the hole by using a microhook or the like. The end of the lead wire
32 is then stripped of any coating and welded to the underside of the ring
electrode
34, which is then slid into position over the hole and fixed in
place with polyurethane glue or the like. Alternatively, each ring electrode
34
may be formed by wrapping the lead wire
32 around the catheter body
12
a number of times and stripping the lead wire of its own non-conductive coating
on its outwardly facing surfaces.
Longitudinal movement of the expander
22 relative to the catheter
body
12, which results in expansion of the electrode assembly
18,
is accomplished by manipulation of the control handle
16. As shown in FIG.
3, the control handle
16 comprises a generally-hollow handle housing
54
and a piston
56 slidably mounted within the distal end of the handle housing.
The proximal end of the catheter body
12 is fixedly attached to the distal
end of the piston
56 by a shrink sleeve (not shown), as is generally known
in the art, or by any other suitable method.
Within the control handle
16, the proximal end of the expander
22
extends through a passage
57 in the piston
56, through the handle
housing
54 and into a support tube
58, preferably made of braided
polyimide or PEBAX®. The support tube
58 extends out the proximal end
of the control handle
16 and terminates in a luer hub
60. The support
tube
58 and expander
22 are together fixedly attached to the handle
housing
54 by any suitable method, preferably with polyurethane glue or
the like. If the expander
22 does not have a lumen, e.g., is in the form
of a puller wire or the like, the expander can be attached to the handle housing
54 without the use of the support tube
58 and luer hub
60,
as is generally known for handles for steerable catheters. Examples of such handle
designs are disclosed in U.S. Pat. Nos. Re 34,502 and 5,897,529, the disclosures
of which are incorporated herein by reference.
If desired, the expander can be eliminated. With such a design, the basket-shaped
mapping assembly
18 may be expanded and contracted by moving a guiding sheath
proximally off the basket and distally over the basket, respectively, so that the
catheter itself does not need to include a means for expanding and contracting
the basket. In this embodiment, as shown in FIG. 4, the mapping assembly
18
include five spines, but only four of the spines
20a form electrodes
25. The fifth spine
20b comprises a flexible wire
24
having a non-conductive covering
26 over its entire length. The electrode
lead wire
32 for the tip electrode extends along the fifth spine
20b
within the non-conductive covering
26 and then into the catheter body
12, as generally described above with respect to the embodiment shown in
FIG. 2.
If desired, the catheter can include one or more location sensors (not shown)
for providing location information about the electrode assembly
18. Such
a design is particularly useful if the an electrical map of the heart has been
produced by a mapping catheter having one or more location sensors. The electrophysiologist
can then use the location sensors to determine the proper placement of the electrode
assembly
18. A catheter having a basket-shaped electrode assembly with location
sensors is described in copending application entitled "BASKET CATHETER WITH MULTIPLE
LOCATION SENSORS," filed on Dec. 14, 2001.
As shown generally in FIG. 5, the catheter of the invention is used in connection
with a suitable external defibrillator
110, an external pacer
112,
and an ECG recorder
114, which are all connected via an interface switch
box
116. Any suitable external defibrillator, external pacer and ECG recorder
known in the art can be used in connection with the invention. The interface switch
box
116 provides a centralized connection to the other system components
while also facilitating electrode selection.
Specifically, cardioversion can be achieved using various electrode
arrangements. For example, cardioversion can be achieved internally by shorting
together all of the spine electrodes
25 so that they can together be used
as a single shocking electrode. Shorting of the spine electrodes
25 is achieved
using the interface switch box, as is generally known in the art. In such an embodiment,
one or more of the ring electrodes
34 on the catheter body
12 and/or
the tip electrode
30 mounted on the electrode assembly
18 can be
used as the return electrode, and preferably multiple ring electrodes are shorted
together to form a return electrode. With this embodiment, a large shocking electrode
surface is formed with the five spine electrodes
25.
Cardioversion can also be achieved internally by using less than all
of the spine electrodes
25 as a shocking electrode and using the remaining
spine electrodes as a return electrode. For example, with the embodiment shown
in FIG. 4, two of the spine electrodes
25 can be shorted together to form
a shocking electrode, with the two remaining spine electrodes shorted together
to form the return electrode. In this embodiment, a relatively large shocking electrode
surface is formed using two spine electrodes.
Alternatively, cardioversion can be achieved with a combination of
internal and external electrodes. For example, one or more of the spine electrodes
25 can be used as the shocking electrode, as generally described above.
An electrode patch (not shown) is provided on the outside of the patient's body
and electrically connected to the external defibrillator
110 through the
interface switch box
116. The electrode patch serves as the return electrode
for defibrillation.
As shown in FIG. 5, the external defibrillator
110 has two electrical
connections
to the interface switch box
116, namely, a shocking connection
118
through which electrical energy to the one or more shocking electrodes is delivered,
and a return connection
120 through which electrical energy passes to the
defibrillator from the return electrodes. The defibrillator delivers sufficient
energy to achieve defibrillation, preferably from about 0.5 to about 20 joules,
more preferably from about 1 to about 10 joules, still more preferably from about
1 to 4 joules. The energy is preferably delivered over a period of time ranging
from about 2 to about 10 msec, more preferably about 6 msec. The shape of the energy
delivered can be uniphasic, biphasic, or multiphasic.
The external pacer
112 is electrically connected to the interface switch
box
116 by one or more pacer connections
122 depending on the number
of pacing electrodes on the catheter. In the depicted embodiment, the catheter
includes one tip electrode
30 and four ring electrodes
34 that can
be use for pacing, and thus the system includes five pacer connections
122.
The ECG recorder
114 is similarly connected to the interface switch box
116 by one or more recorder connections
124 depending on the number
of electrodes available for obtaining ECG information. In the depicted embodiment,
the catheter includes one tip electrode
30 and four ring electrodes
34
that can be used for obtaining electrical information, and thus the system includes
five recording connections
124.
To use the catheter of the invention, an electrophysiologist introduces a guiding
sheath, guidewire and dilator into the patient, as is generally known in the art.
A suitable guiding sheath for use in connection with the inventive catheter is
the PREFACE™ Braided Guiding Sheath (commercially available from Biosense
Webster, Inc., Diamond Bar, Calif.). The dilator is removed, and the catheter is
introduced through the guiding sheath whereby the guidewire lumen in the expander
22 permits the catheter to pass over the guidewire. The guiding sheath covers
the spines
20 of the electrode assembly
18 internally in a collapsed
position so that the entire catheter can be passed through a vein or artery to
a desired location. Once the distal end of the catheter reaches the desired location,
the guiding sheath is withdrawn. The expander
22 is then manipulated so
that the spines
20 of the electrode assembly
18 flex outwardly into
an expanded arrangement. In such an arrangement the spines
20 (and thus
spine electrodes
25) contact the tissue of the heart. As will be recognized
by one skilled in the art, the electrode assembly
18 can be fully or partially
expanded in a variety of configurations depending on the precise configuration
of the region of the heart in which the assembly is positioned.
Once the electrode assembly
18 is in the desired position, the system
is set up. The catheter
10 is electrically connected to the interface switch
box
116 via the electrode lead wires
32, which can be done before
or after insertion of the catheter. The interface switch box
116 is also
electrically connected to the external defibrillator
110, external pacer
112, and ECG recorder
114, as described above. The electrode impedance
is verified through the external defibrillator
110 and/or external pacer
112. The intercardiac ECG amplitude is also verified to assure that the
electrodes are working properly and in good contact with the heart tissue. The
electrophysiologist then selects the electrode, defibrillation and pacing modes,
as well as the defibrillation parameters (such as energy and pulse width) to be
delivered through the external defibrillator.
After the electrode assembly
18 is in the desired position and the system
set up, the electrophysiologist can then introduce into the patient's heart a suitable
treatment catheter, such as an ablation catheter for ablating lines of block. The
electrophysiologist performs the ablation or other atrial fibrillation treatment,
as is generally known in the art. It is not uncommon for the patient's heart to
stop beating during such procedures. Accordingly, to the extent this occurs, the
electrophysiologist uses the basket catheter of the invention to deliver shocking
energy to the heart. To do so, the electrophysiologist synchronizes cardioversion
with the R-wave and then delivers the defibrillation energy to the heart. The electrophysiologist
then verifies capture, and if there is not capture, he redelivers the defibrillation energy.
As noted above, because the basket-shaped electrode assembly has a larger surface
area than conventional catheters, the impedance and energy requirements are reduced,
thereby causing less pain to the patient than with conventional defibrillation
methods. Moreover, the ability of the electrode assembly to expand and contract
permits adjustability of the electrodes and better contact with tissue. After the
patients achieves a regular heartbeat, the electrophysiologist can resume the ablation
or other treatment procedure. Additionally, the basket catheter of the invention
can be used for pacing during the ablation or other treatment procedure using the
tip electrode and/or ring electrodes.
Although the inventive methods and systems have been described with respect
to a particularly preferred basket catheter configuration, other similar basket
catheter configurations can also be used. Examples of such configurations are generally
described in U.S. Pat. Nos. 6,262,695, 5,782,239, 5,772,590, 5,628,313, and 5,411,025,
the disclosures of which are incorporated herein by reference.
If desired, the catheter can include a steering mechanism for deflection of the
distal end of the catheter body
12. With such a design, the distal end of
the catheter body
12 preferably includes a tip section
14 comprising
a short length of tubing, e.g., 2 to 4 inches, that is more flexible than the remainder
of the catheter body, as shown in FIG. 6. The tip section
14 can be attached
to the catheter body
12 by any suitable method, such as by polyurethane
glue or the like, as described in more detail in U.S. patent application Ser. No.
09/796,198, entitled "Catheter Having Continuous Braided Electrode," the entire
disclosure of which is incorporated herein by reference.
The steering mechanism comprises a puller wire
34 that extends from a
proximal end in the handle through the catheter body and into an off axis lumen
36 in the tip section
14. The tip section
14 comprises a primary
lumen
38, which can be an off-axis lumen or an axial lumen, into which the
expander
22, electrode lead wires
32 and the proximal ends of the
spines
20 extend. Within the catheter body
12, the puller wire preferably
extends through a closely wound coil (not shown) that is bendable but substantially
compressible, as generally described in U.S. patent application Ser. No. 09/796,198,
entitled "Catheter Having Continuous Braided Electrode," the entire disclosure
of which is incorporated herein by reference. Preferably the coil is fixed near
the proximal and distal ends of the catheter body to prevent deflection of the
catheter body. The distal end of the puller wire
34 is anchored in the tip
section
14 proximal to the proximal end of the electrode assembly
18
by any suitable means. In the depicted embodiment, the puller wire
34 is
anchored to the distal end of the tip section
14 with a T-shaped anchor
37, as generally described in U.S. patent application Ser. No. 09/796,198,
entitled "Catheter Having Continuous Braided Electrode," the entire disclosure
of which is incorporated herein by reference. As described in U.S. patent application
Ser. No. 09/796,198, the T-shaped anchor can also be used to attach the puller
wire to the side wall of the tip section.
The proximal end of the puller wire
34 is anchored to a movable member
in the control handle
16 that can be moved relative to the catheter body
12. If the catheter does not include an expander
22, the above-described
control handle
16 can be used for manipulating the puller wire
34
in place of the expander, as would be recognized by one skilled in the art. In
other words, the proximal end of the puller wire
34 is attached, directly
or indirectly, to the handle housing
54 so that proximal movement of the
handle housing relative to the piston
56 and catheter body
12 results
in longitudinal movement of the puller wire
34 relative to the catheter
body, thereby deflecting the tip section
14. If a steering mechanism is
included in addition to an expander
22, the control handle
16 may
be of any suitable construction for manipulating two wires, in this case, the expander
22 and the puller wire
34. Preferably the handle has a pair of movable
members to which the expander and puller wire attach, such as handles typically
used for bidirectional and multidirectional catheters. Examples of such handles
are disclosed in U.S. Pat. Nos. 6,210,407, 6,198,974, 6,183,463, 6,183,435, 6,171,277,
and 6,123,699, the disclosures of which are incorporated herein by reference.
The preceding description has been presented with references to presently preferred
embodiments of the invention. Persons skilled in the art and technology to which
this invention pertains will appreciate that alterations and changes in the described
structures and methods can be practiced without meaningfully departing from the
principle, spirit and scope of this invention. Accordingly, the foregoing description
should not be read as pertaining only to the precise structures and methods described
and shown in the accompanying drawings, but rather should be read as consistent
with and as support for the following claims, which are to have their fullest and
fairest scope.
*
