U.S. patent application number 09/939393 was filed with the patent office on 2002-01-03 for mapping and ablation catheter system.
Invention is credited to Avitall, Boaz.
Application Number | 20020002329 09/939393 |
Document ID | / |
Family ID | 46251767 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020002329 |
Kind Code |
A1 |
Avitall, Boaz |
January 3, 2002 |
Mapping and ablation catheter system
Abstract
A recording and ablation catheter method and system for creating
linear lesions in an atrial or other chamber of a heart is
disclosed which includes an array of readily controlled electroded
arcuate distal working catheter shapes that are easily deployed to
contact the inner wall surface of the right atrial cardiac chamber
in a manner that enables easy recording and mapping of impulses and
thereafter facilitates sustained contact so that linear lesions can
be produced from an array of mapping and ablation electrode devices
serially spaced along the working catheter shape.
Inventors: |
Avitall, Boaz; (Milwaukee,
WI) |
Correspondence
Address: |
Charles G. Mersereau, Esq.
Nikolai & Mersereau, P.A.
Suite #820
900 Second Avenue South
Minneapolis
MN
55402
US
|
Family ID: |
46251767 |
Appl. No.: |
09/939393 |
Filed: |
August 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09939393 |
Aug 24, 2001 |
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09629208 |
Jul 31, 2000 |
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6308091 |
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09629208 |
Jul 31, 2000 |
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09154854 |
Sep 17, 1998 |
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6138043 |
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09154854 |
Sep 17, 1998 |
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08968159 |
Nov 12, 1997 |
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5842984 |
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08968159 |
Nov 12, 1997 |
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08593660 |
Jan 29, 1996 |
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5730127 |
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08593660 |
Jan 29, 1996 |
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08487492 |
Jun 8, 1995 |
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5687723 |
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08487492 |
Jun 8, 1995 |
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08161920 |
Dec 3, 1993 |
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5487385 |
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Current U.S.
Class: |
600/377 |
Current CPC
Class: |
A61B 5/6856 20130101;
A61B 2018/0016 20130101; A61B 18/14 20130101; A61N 1/06 20130101;
A61B 2018/00351 20130101; A61B 2018/00029 20130101; A61B 2018/1407
20130101; A61B 18/1815 20130101; A61B 2018/00273 20130101; A61B
5/6855 20130101; A61B 2018/00148 20130101; A61B 2018/00011
20130101; A61B 2218/002 20130101; A61B 2018/1475 20130101; A61B
2018/00839 20130101; A61B 5/287 20210101; A61B 2218/005 20130101;
A61B 2562/043 20130101; A61B 2018/00357 20130101; A61B 2018/00577
20130101; A61B 2018/00077 20130101; A61B 2018/00196 20130101; A61B
18/1492 20130101; A61B 2017/22038 20130101; A61B 2018/00023
20130101; A61B 90/39 20160201; A61B 5/6859 20130101 |
Class at
Publication: |
600/377 |
International
Class: |
A61N 001/05 |
Claims
I claim:
1. A recording and ablation system for accessing a cardiac chamber
of interest, mapping, creating linear ablation lesions in said
cardiac chamber of interest comprising: (a) a guide member for
navigating a catheter or sheath in the vascular system of a
patient, said guide member comprising a distal stop means for
containing the distal travel of a guide member eye, threaded
thereover; (b) an hollow outer catheter or sheath; (c) an inner
deployable system operable within said outer catheter or sheath and
including a flexible distal electroded recording and ablation
device extendable to protrude and be deployed from a distal opening
in said outer catheter or sheath, said electroded device being
axially adjustable relative to said guide member and having at
least a distal guide member eye that slidably threads over said
guide member to said distal stop means such that the electroded
section proximal said distal guide member eye can be adjustably
arcuately flexed according to the relative motion of said distal
guide member eye and said electroded section protruding from said
distal opening as contained by said distal stop means to produce a
desired shape to address an inner surface of said chamber of
interest; (d) locking mehanism to prevent relative rotation between
said electroded device and said guide member; and (e) a plurality
of spaced serial electrodes carried by said recording and ablation
device.
2. The apparatus of claim 1 wherein said outer catheter or sheath
is a sheath and further comprises a directional sheath deflection
system proximal said distal opening for enhancing control of the
shape assumed by the sheath proximal to said distal opening.
3. The apparatus of claim 1 wherein said locking mechanism further
comprises a keying arrangement between said distal stop means and
said guidemember eye.
4. The apparatus of claim 1 wherein said locking mechanism further
comprises a locking clip arrangement.
5. The apparatus of claim 1 wherein said locking mechanism includes
a ball and socket arrangement.
6. The apparatus of claim 1 wherein said recording and ablation
device is fixed to said guidewire.
7. A recording and ablation system for accessing a cardiac chamber
of interest, mapping creating linear ablation lesions in said
cardiac chamber of interest comprising: (a) an hollow outer
catheter or sheath; (b) an inner catheter member operable within
said outer catheter or sheath and including a flexible distal
electoded recording and ablation device extendable to protrude from
a distal opening in said outer catheter or sheath, said electroded
device being axially adjustable relative to said sheath; (c)
wherein said electroded recording and ablation device is in the
form of a deployable ribbon loop carrying a plurality of serially
spaced electrically isolated, separately connected electrodes
forming an array thereof.
8. The apparatus of claim 7 wherein said electrodes are selected
from the group of conductive elements consisting of patterned
conductors, conductive films and continuous conductive filament
material.
9. The apparatus of claim 7 wherein said loop comprises a pair of
segments emerging from an opening in said outer catheter or sheath
joined by a flexible bridge to form a continuous loop, the segments
being in a generally back to back arrangement thereby describing a
loop having an outer and an inner surface, said electrodes being
arranged along said outer surface.
10. The apparatus of claim 9 wherein said electrodes are selected
from the group of conductive elements consisting of patterned
conductors, conductive films and continuous conductive filament
material.
11. The apparatus of claim 9 wherein each of said segments of said
loop is separately controllable and deployable such that said
bridge can be located anywhere along said loop.
12. The apparatus of claim 11 wherein said electrodes are selected
from the group of conductive elements consisting of patterned
conductors, conductive films and continuous conductive filament
material.
13. The apparatus of claim 7 wherein each of said electrodes is
capable of registering an electric signal individually for mapping
and can be energized individually or in any desired combination
with other electrodes of the device to accomplish spot or linear
ablation.
14. The apparatus of claim 13 wherein the interelectrode distance
is less than or equal to the electrode length.
15. A recording and ablation system for accessing a cardiac chamber
of interest comprising (a) a maneuverable outer catheter or sheath
having a distal opening for the deployment of a recording and
ablation device therefrom; (b) a plurality of vent openings
proximal the distal opening for releasing entrapped air a distance
proximal said distal opening.
16. The apparatus of claim 15 further comprising one or more
locator rings proximal the distal opening.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part of application Ser. No.
08/487,492, filed Jun. 8, 1995, which, in turn, is a
continuation-in-part of application Ser. No. 08/161,920, filed Dec.
3, 1993.
BACKGROUND OF THE INVENTION
[0002] I. Field of the Invention
[0003] The present invention relates generally to the field of
mapping and ablation using steerable vascular catheters. The
invention is particularly directed to recording and ablation
catheter systems applicable to create continuous linear lesions in
any cardiac chamber.
[0004] II. Discussion of the Related Art
[0005] Steerable catheter systems of several types have been
devised. Such devices can be inserted into blood vessels or similar
bodily areas and their distal ends navigated through the tortuous
vascular path to reach areas of the body normally inaccessible
without surgery. Catheters of the steerable or self-navigating
type, having distal electroded sections for monitoring parts of the
body, such as for electrically mapping the heart by receiving and
transmitting electrical signals related to the operation of that
organ to recording signal processing and display devices are also
known. The ability to successfully record impulses or signals and
from them electrically map cardiac chambers and valves using
flexible catheters having steerable electroded tips has further led
to the development of techniques for transcatheter ablation of
cardiac tissues that have been identified as the pathways that
enable cardiac arrhythmias. This technique has emerged as one of
the most important advances in cardiac electrophysiology. Its goal
is to destroy the arrhythmogenic tissue without compromising the
mechanical or muscular integrity of the cardiac tissues and
vessels.
[0006] Not long ago, for example, many patients with
Wolff-Parkinson-White syndrome or ventricular tachycardia were
forced to undergo surgical dissection of the arrhythmogenic tissue
followed by a painful and prolonged recovery. Introduction of the
transcatheter approach has dramatically reduced the suffering and
cost of definitive treatment for many cardiac arrhythmias.
[0007] The general approach to this procedure initially preferably
utilized high energy direct current delivered to the catheter
poles, for example, to disrupt the A-V node condition and even to
create a complete heart block by ablating the His bundle. More
recently, however, radio frequency has replaced high energy direct
current as the preferred primary source of energy and the
transcatheter approach for cardiac ablation has become an accepted
and common procedure and has been used increasingly as the primary
mode of treating cardiac arrhythmias. Transcatheter cardiac tissue
ablation is more fully discussed in Avitall et al, "Physics and
Engineering of Transcatheter Tissue Ablation", JACC, Volume 22, No.
3:921-32. The rapid clinical acceptance of this procedure and the
proliferation of physicians engaged in transcatheter tissue
ablation has mandated the development of improved steerable
catheter devices.
[0008] Other common cardiac arrhythmias untreatable except with
medication, and more recently, surgery, involve atrial fibrillation
and flutter. These conditions, in fact, are the most common rhythm
disturbances in human beings. For example, approximately 1% of the
population of the United States, i.e., more than 2.5 million
people, depends on medication to control this condition. These
irregular heart rhythms can reach rates of 180 beats/minute or
more. The resulting loss of blood flow due to incomplete atrial
contractions along with a rapid heart rate can lead to shortness of
breath, dizziness, limited physical endurance, chest pains, in
patients with coronary heart disease, and other related
problems.
[0009] Recently, Dr. Cox et al of Washington University School of
Medicine in St. Louis, Mo., have devised a surgical procedure
called the Maze and Corridor operation. This procedure is an
attempt to restore the normal heart rhythm by segmenting the atrial
tissues in a manner that allows the normal heart pacemaker to
conduct to the AV node as well as preventing the atrial tissues
from sustaining the atrial fibrillation. By cutting the atrial
tissue, no electrical activity can be transmitted from one segment
to another, thus making the segments too small to be able to
sustain the fibrillatory process. The approach, while successful,
has the same drawbacks as other previous surgical approaches with
respect to the recovery of the patient. This represents another
area of cardiac arrhythmic treatment where a more benign approach,
i.e., without invasive surgery, would represent a definite
advance.
[0010] In this regard, as with certain other arrhythmia conditions,
electrical decoupling of tissues by heating the tissues with radio
frequency (RF) energy, microwave energy, laser energy, freezing and
sonication, represent possible alternative approaches. Heating
tissues above 55.degree. C. is known to cause permanent cellular
injury, making the cells electrically silent. It has been found
that segmenting tissues by creating continuous linear lesions via
ablation in the atria mimics some aspects of the maze and corridor
procedure. The most important aspect of these lesions is their
transmural and continuous character; otherwise, segmenting the
heart and preventing atrial fibrillation would not be possible.
However, it is possible that limited division of tissues within the
right atrium may prevent atrial fibrillation in some patients.
Furthermore, segmenting a corridor between the sinus node and the
AV node will maintain physiological control of heart rate despite
the fibrillation of the atrial tissues.
[0011] Present steerable catheter systems, while successful in
addressing many internal cardiac areas, have not been so successful
in treating atrial fibrillation, for example, because they have not
been able to sustain contact with certain surface areas of the
atrial chambers without great difficulty. In this regard, prior
devices have failed to successfully create the necessary linear
lesions via ablation to achieve the desired segmentation. The
provision of a recording and ablation catheter system that can
successfully treat atrial fibrillation and flutter and other
conditions as by making creation of continuous linear lesions in
the relevant chamber easier would represent a definite advance in
the treatment of this condition.
[0012] Accordingly, it is a primary object of the invention to
provide an improved catheter, easily deployed and maneuvered to
contact desired inner wall surfaces of the any cardiac chamber and
sustain contact so that linear lesions can be produced as
required.
[0013] Another object is to provide multi-electrode working
catheter shapes that are easily deployed from sheaths or main
catheters once the desired chamber is reached.
[0014] An additional object of the invention is to provide such
catheter shapes capable of being readily modified to address
internal surfaces of varying contour in a linear manner.
[0015] Yet another object of the invention is to provide a method
of readily mapping and ablating in an atrial chamber.
[0016] Still another object of the invention is to provide an
improved multi-electrode mapping and ablation catheter for
deployment in an atrial chamber by accessing one atrial chamber
from the other atrial chamber through the atrial septum.
[0017] Yet still another object of the invention is to provide an
improved multi-electrode mapping and ablation catheter for
deployment in the left atrial chamber that accesses the left atrial
chamber via the inferior or superior vena cava, right atrial
chamber and the atrial septum.
[0018] A further object of the invention is to provide an improved
multi-electrode mapping and ablation catheter for deployment in the
left atrial chamber capable of aligning multiple electrodes in any
disposition with reference to the wall of that chamber.
[0019] A still further object of the invention is to provide a
multi-electrode mapping or ablation catheter for deployment in an
atrial chamber by accessing the atrial chamber via the aorta.
[0020] A yet still further object of the invention is to provide a
multi-electrode mapping or ablation catheter for deployment in the
left atrial chamber by accessing the left atrial chamber via the
aorta and that is capable of ablating a linear lesion of any
disposition within the left atrial chamber.
[0021] An additional object of the invention is to provide a
multi-electrode mapping and ablation catheter deployable in a heart
chamber having a plurality of shape controlling devices associated
with the deployed system.
[0022] Yet an additional object of the invention is to provide a
multi-electrode ablation catheter with integral electrode
cooling.
[0023] Another object of the invention is to provide a deployable
mapping and ablation catheter for creating linear lesions in the
form of a deployable ribbon loop device.
[0024] Yet another object of the invention is to provide an over
the wire and a fixed wire multi-electrode mapping and ablation
device with relative rotation control.
[0025] Other objects and advantages of the invention will become
apparent to those skilled in the art in accordance with the
descriptions and Figures of this specification.
SUMMARY OF THE INVENTION
[0026] By means of the present invention, there is provided an
array of readily controlled arcuate distal working catheter shapes
that form the distal portion of an inner catheter carried by an
outer catheter or sheath. The catheters may also be in the form of
ribbon like structure which can be displayed from a sheath to form
symmetric or asymmetric loop configurations. The working catheter
sections are easily deployed to contact the inner wall surface of
any cardiac chamber in a manner that allows them to contour the
endocardial surface and enables easy recording or mapping of
impulses and thereafter facilitates sustained contact so that
linear lesions can be produced from an array of mapping and
ablation electrode devices serially spaced along the working
catheter shape using the electric heating or radio frequency
ablation energy.
[0027] The inner catheter is provided with a distal electroded
section known as the working catheter section and is inserted
through or carried within a lumen of a main vascular catheter or
sheath and the working catheter section of the inner catheter is
designed to be deployed from the main catheter or sheath once the
desired chamber is entered. The main catheter or sheath is provided
with an opening at or near the distal end from which the distal
portion of the inner catheter or working catheter section is caused
to emerge. Using any of several posturing techniques, the working
catheter section may be caused to assume any of several deployed
shapes, the control of which may be independent of or with
reference to the slidable attachment of one or both ends of the
working catheter section to an axially displaceable guidewire or
other catheter mounted element.
[0028] While certain configurations may favor one or the other, it
is contemplated that the working catheter of the invention be
deployable and fully effective in any heart chamber including
either atrial chamber. It is further contemplated that the working
catheter section or electroded distal section be one which can
access either atrial or ventricular chamber and embodiments are
provided for using more than one access route. In this manner, the
left atrial chamber, for example, may be accessed via the arterial
system through the aorta, the left ventricle and the mitral valve;
or through the venous system through either vena cava (the use of
the inferior vena cava is illustrated in the Figures) and
thereafter piercing the atrial septum to access the left atrial
chamber. Once the chamber of interest has been entered in the
manner desired, the electroded portion or section which may
conveniently be called the working catheter section may be deployed
and maneuvered into the desired pattern of contact with the chamber
wall. Both mapping and ablation procedures may be combined or
achieved singularly using the special deployment and electrode
configurations of the invention.
[0029] It is important that control of the disposition or posture
of the working catheter within the chamber to be treated be made as
easy as possible so that the desired alignment at the ablation site
can be achieved in the shortest time. Another important aspect of
the invention is that the working catheter be able to be controlled
so as to sustain an electrode position until ablation is
accomplished.
[0030] Positioning may also be assisted in certain embodiments by
providing additional control devices. In catheters designed to
operate slidably over a guidewire, a locking system may be provided
in any of several forms to optionally prevent rotation of the
distal portion of the catheter relative to the guidewire. In other
self-guiding embodiments, the distal end may be permanently fixed
to a control wire.
[0031] If desired, the ablation catheter may be provided with an
auxiliary cooling system to prevent overheating of the tissue
adjacent or abutting ablation electrodes after they have been
energized. This system flushes desired electrodes with infused
saline from an encased movable internal tube through cooling
effusion ports provided tube which can be aligned with pores or
ports provided in the working catheter and in the electrodes
themselves which can be connected with a source of fluid
coolant.
[0032] The working catheter of the invention may be deployed
independently of or may include one or more rider devices which
slidably thread over a wire member, which may be the guidewire, and
which cooperate with stops limiting travel of at least one of the
rider members such that adjustable arcuate forms are assumed by the
section intermediate the rider members as their relative separation
distance is modulated. A linear or non-linear semi-rigid tube guide
member may also be used in conjunction with the guidewire in
posturing the working catheter. Additional control elements may be
attached along the working catheter between electrodes to provide
additional shape modification. In another alternate embodiment, a
right- or left-handed loop shape is assumed by the specialty shaped
working catheter upon deployment. One or more radiopaque markers
may also be provided to assist in positioning and orienting the
system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In the drawings, wherein like numerals designate like parts
throughout the same:
[0034] FIG. 1 is a schematic representation of one embodiment of an
atrial fibrillation mapping and ablation catheter in accordance
with the invention with the extended length of the main tube
segment broken away;
[0035] FIGS. 2-4 illustrate a different embodiment of a mapping and
ablation catheter;
[0036] FIG. 5 illustrates schematically the deployment of the
catheter embodiment of FIG. 1 in a right atrial chamber;
[0037] FIGS. 6 and 7 depict the deployment of the embodiment of
FIG. 8 in a right atrial chamber;
[0038] FIG. 8 is an enlarged schematic representation of an
alternate to the embodiment of FIGS. 2-4 of a working catheter in
accordance with the invention with the elongated sheath shown
broken;
[0039] FIG. 9 is a schematic representation of yet a different
embodiment of the catheter of the invention;
[0040] FIG. 10 is an enlarged fragmentary view illustrating an
infusion port usable with the catheter system of the invention;
[0041] FIGS. 11-13 are fragmentary views of yet a different
embodiment of the catheter of the invention which takes the form of
a loop configuration when deployed;
[0042] FIG. 14 is a simplified schematic front diagram partially in
section of a heart illustrating the chambers and an accessing route
to the left atrial chamber through the inferior vena cava and
atrial septum;
[0043] FIGS. 15a-15d are additional views similar to FIG. 14
further illustrating the accessibility of a variety of areas of the
surface of the left atrium accessed as per FIG. 14 and using the
working catheter section of the invention;
[0044] FIG. 16 is a simplified schematic front sectional diagram
partially in section of a heart showing an alternate access route
to the left atrium through the arterial system;
[0045] FIGS. 17a-17d are additional views similar to FIG. 16
showing the working catheter section of the invention accessing a
variety of surfaces in the left atrial chamber accessed by the
route of FIG. 16;
[0046] FIG. 18a is a view similar to FIG. 8 slightly reduced and
with a single (distal) guidewire port;
[0047] FIG. 18b is a view similar to FIG. 18a depicting a
semi-rigid tubular control member;
[0048] FIG. 19 is a schematic view of still another embodiment of a
catheter in accordance with the invention;
[0049] FIG. 20 depicts a greatly magnified fragmentary view of the
distal end of a working catheter segment in accordance with the
invention showing the water effusion system;
[0050] FIG. 21 is a view in slightly reduced scale of the proximal
terminal portion of the catheter of FIG. 20;
[0051] FIGS. 22a-22c depict another embodiment in which a working
catheter system is provided with an alternate multi-element control
system;
[0052] FIG. 23 depicts yet another embodiment in which a system
similar to FIG. 8, 18a or 18b is provided with additional control
member;
[0053] FIG. 24 is an enlarged side view of a ribbon type mapping
and ablation device in accordance with the invention emerging from
the distal end of an outer sheath;
[0054] FIG. 25 is a view of the ribbon catheter of FIG. 24 rotated
90.degree. to show the collapsed or stored profile;
[0055] FIG. 26 is an enlarged fragment of a ribbon catheter section
illustrating types of electrodes suitable for use in various
versions of the several embodiments of ribbon catheters in
accordance with the invention;
[0056] FIG. 27 shows the ribbon mapping and ablation device
deployed as a symmetrical loop configuation;
[0057] FIG. 28 depicts an asymmetrical loop ribbon
configuration;
[0058] FIGS. 29 and 30 depict a steerable catheter sheath and the
sheath with a ribbon mapping and ablation device deployed
therefrom;
[0059] FIGS. 31a and 31b depict fragmentary front and profile views
of one version of a rotation control lock for a guidewire mounted
catheter tip;
[0060] FIGS. 32, 33a, 33b and 34 depict additional embodiments of
guidewire mounted catheter tip rotation control lock mechanism;
[0061] FIG. 35 depicts a deployed catheter having a distal tip
fixed to a guidewire having a floppy distal soft tip guide
hook;
[0062] FIG. 36 is a view of an embodiment similar to that of FIG.
35 without the guide tip;
[0063] FIG. 37 shows an alternative self-guiding and anchoring
catheter tip; and
[0064] FIG. 38 depicts a catheter sheath having distal air release
openings.
DETAILED DESCRIPTION
[0065] The electrical mapping and ablation system is carried by a
distal working catheter or probe portion, extension or segment
which, in accordance with the invention, may present itself in any
of several forms. The distal portion or area is normally deployed
from a main catheter or sheath in the vicinity of any cardiac
chamber of interest. The electrode position and form chosen will
depend on the particular surface to be addressed and the mode of
access to the chamber. Also, the electrode configuration is not
meant to be limited in any manner to the illustrated patterns, it
being further understood that any size and pattern of electrodes
consistent with mapping and ablation objectives in any part of the
chamber of interest can be employed.
[0066] The electrode systems in accordance with the distal working
catheter section are generally designed so that each individual
electrode is electrically connected by a separate insulated lead
threaded through the catheter system to the distal end thereof
where each lead is connected to a control system that enables
separate mapping or recording of impulses received from each
electrode and separate or ganged connection of the same electrodes
for ablation. This enables ablation using any desired pattern of
multiple electrodes in the serial array to produce any
configuration of desired lesions. Such an arrangement of electrode
control is illustrated and described in applicant's co-pending
application Ser. No. 08/161,916 filed of even date with the
grandparent of this application (Dec. 3, 1993) and now U.S. Pat.
No. 5,454,370 issued Oct. 3, 1995, which is hereby incorporated by
reference for any necessary purpose.
[0067] The working catheter of the invention is designed to enable
the skilled practitioner to achieve a greater degree of control
with respect to mapping and precisely placing linear lesions in the
internal surface of tissue in the vicinity of a cardiac chamber
with greater facility using RF ablation or the like to achieve
electrical segmentation. This is achieved by the provision of a
variety of unique working catheter embodiments configured to
contact continuous segments of atrial chamber surfaces. While
certain of the embodiments may be described with particular
reference to a specific cardiac chamber, it will be understood that
the working catheters of the invention may find further equally
viable use in other chambers and organs. Thus, for example, the
various embodiments described with relation to atrial ablation may
also be used in ventricle chambers and also in the vicinity of
heart valves as well.
[0068] Such a catheter, shown generally at 20 in FIG. 1, includes
three main cooperating components including a distal working
catheter sheath section or portion 22, which may be an extension of
an elongated main tubular catheter member 24 shown broken to
indicate the relatively extensive length, and a control handle 26
with a working tip manipulation or orientation control knob as at
28. The working catheter sheath section is provided with a slotted
opening 30 from which a flexible segment or relatively short distal
length of working catheter 32 which can readily be deflected or
bent and which carries a plurality of serially spaced electrodes as
at 34 emerges to be deployed. The control knob 28 may be attached
to deploy and spatially manipulate (deflect and rotate) the working
catheter section 32 in any well-known manner. One such control
system is illustrated and described in the applicant's copending
application Ser. No. 08/156,284 filed Nov. 22, 1993, now U.S. Pat.
No. 5,465,716 issued Nov. 14, 1995, entitled Catheter Control
Handle. Material from that application to the extent helpful or
necessary to this description is further deemed incorporated herein
by reference for any necessary purpose. In any event, the working
catheter portion 32 is deployed from the sheath opening 30 and is
designed to be manipulated both as to curvature and posture to
position the electrodes against a surface to be mapped or
ablated.
[0069] The catheter 20 further includes a short relatively flexible
vascular guide member 36 fixed to the distal tip thereof to enable
the device to be essentially self-navigating. A liquid-tight sheath
locking device 37 with infusion port 38 is provided proximal the
point of catheter introduction which cooperates with an introducer
device in a well-known manner such that catheter controls and
input/output devices are accessible from outside or proximal the
point of catheter introduction. A plurality of conductors are shown
at 39.
[0070] FIG. 5 is a schematic representation of a heart 40 sectioned
through the chambers including a right atrial chamber 42, right
ventricle 44, separated by tricuspid valve 46. The pulmonary valve
and artery are shown, respectively, at 48 and 50. The superior vena
cava is shown at 52 and the inferior vena cava, at 54. The working
catheter section is shown in the right atrium and extending in the
vena cava and illustrates that the right atrial chamber 42 can be
accessed either through the superior vena cava or the inferior vena
cava and the electroded working segment deployed in conjunction
with movement of the sheath 22 to enable placement of the
electrodes 34 as desired.
[0071] FIGS. 2-4 depict an alternative functional embodiment 120 of
the catheter/sheath of the invention in which the guidewire or
guide tip 122 protrudes from a closed distal end 124. The sheath
section or portion 125 is provided with an elongated slot or
opening 126 through which the working catheter section 127 with a
plurality of electrodes 128 is deployed. As better seen in FIG. 3,
in this embodiment the guide member 122 extends into the lumen 129
of the sheath 125 and is further slidably threaded through a bore
130 in a rider segment 131 in the distal end of the working
catheter section 127.
[0072] The working catheter section 127 has the rider of its distal
end slidably threaded over the vascular guide member so that the
more proximal portion of the catheter section 127 produces an
adjustable arcuate curve in the electroded working catheter
section. A control wire attached in the proximal area of the distal
working catheter section in a well-known manner as, for example,
described in the above cross-referenced copending applications,
when reciprocally manipulated as by handle 28 will produce an
arcuate curve of varying severity as illustrated in FIGS. 3 and 4.
In this manner, the plurality of serially spaced electrodes 128 can
be caused to assume an adjustable pattern that can be placed
adjacent chamber surfaces of varying arcuate shapes; FIG. 4
illustrates a plurality of possible configurations. The nose
portion 124 provides a distal stop that determines the furthest
distal location of the tip rider 131 of the distal catheter segment
126 so that further distal directed longitudinal displacement of
the proximal portion of the working catheter within the sheath will
produce arcuate deflections to form configurations such as those
illustrated.
[0073] FIG. 8 is an enlarged schematic view of a guide-mounted
embodiment using a slide-over-type flexible guiding, navigation
member or wire 140 over which the working catheter section 142 with
electrodes 143 is threaded both distal and proximal the electroded
portion using rider segments as illustrated at 144 and 145,
respectively, leaving the central portion detached to form a
"caterpillar" attachment arrangement. A positive stop 141 attached
to the guide member 140 limits the distal travel of the catheter
tip. The main catheter sheath is shown at 147, broken away for
convenience, and optionally provided with an infusion port 148 with
lock system 149.
[0074] The number, size and spacing of the electrodes 143 is
optional. One embodiment used 20 ring electrodes about 4 mm long,
spaced 4 mm apart. It will be appreciated, however, that the
serially spaced electrode configuration in accordance with the
invention and its several embodiments has as a primary goal, aside
from arcuate tissue mapping or recording, the creation of linear
lesions by means of ablation to achieve segmentation of conduction
paths within the chamber surface tissue. With this in mind, certain
combinations of electrode configurations and shapes can be
employed. Electrodes .about.2 mm in length spaced 0.5-3 mm apart in
the embodiments of FIGS. 1-4 and 9 have also been used as have
electrodes arranged in spaced pairs as in FIGS. 11-13.
[0075] The embodiment of FIG. 8 is further illustrated with respect
to catheter placement in the right atrial chamber of a heart in
FIGS. 6 and 7. These schematic sectional views illustrate that the
relative arcuate shape of the mapping/ablation working catheter
section 142 can be controlled to any desired shape and that such
arcuate shapes very closely resemble the contour shapes of the
internal surfaces of the various walls of the right atrium. In FIG.
6, for example, the upper interior section 150 is readily addressed
by the arcuate shape assumed by the working catheter section 142 as
is the lower segment 152. In FIG. 7, the right wall of the atrial
chamber is addressed at 154. The working catheter section has
further been rotated with respect to the guide member 140. These
positions can be maintained despite continuously flowing blood and
moving chamber walls.
[0076] With respect to the embodiment of FIG. 8, a 7F sliding
catheter system similar to that of FIG. 8 was constructed that
allowed the catheter to curve and adapt to the endocardial surface
of the right atrium. The catheter was equipped with 20 closely
spaced 4 mm electrodes used for both mapping and ablation. In 7
models, susceptibility to AFIB was created by sterile pericarditis,
vagal stimulation and isuprel infusion (3 .mu.gram/min). A stiff
guidewire with a floppy pigtail tip (as at 140 in FIG. 8) was
inserted via the femoral vein into the superior vena cava. A sheath
was placed over the guidewire with its tip at the inferior vena
cava/right atrial junction. The ablation catheter was inserted into
the sheath over the guidewire and initially positioned at the
posterolateral right atrium with the electrodes in contact with the
superior vena cava, right atrium and inferior vena cava tissues.
Catheter deflection was achieved by pushing the catheter shaft
against a stopper located 10 cm from the guidewire tip.
[0077] Graded RF power starting at 20 watts and proceeding to 30,
40 and 50 watts was applied to each electrode for 30 seconds at
each power level. Following the ablation, the catheter was moved
and curved over the anterior wall of the right atrium and the
ablations were repeated. AFIB was induced at least 10 consecutive
times before and after ablation using 60 Hz alternating current
applied for 5 seconds to the left atrial appendage. Six of the 7
models had sustained AFIB (>3 min). Following the ablation, AFIB
could not be sustained and lasted only 20.+-.48 seconds.
Examination of each heart revealed continuous transmural lesions
bisecting the right atrium posterolaterally and anteriorly.
[0078] FIG. 9 illustrates yet another embodiment in which the
distal end or tip 160 of the working catheter segment 161 with
electrodes 162 is deployed from a guided distal opening 163 in the
distal end of a lumen 165 in a catheter or sheath 166 equipped with
a flexible soft wire tip-type vascular guide member 167. In this
embodiment, as with the embodiment of FIG. 1, the amount of
deployment, deflection and posture of the working catheter tip
section 160 may be controlled by handle manipulations means in
conjunction with one or more control wires or elements (not
shown).
[0079] FIGS. 11-13 depict yet another configuration for providing
an arcuate shape suitable for mapping and ablation within the
confines of the right atrial or any other desired chamber of the
heart. As can be seen in those Figures, the distal end 170 of a
distal working catheter section 171 emanating from a sheath or main
catheter 172 at 173 has a bore slidably threaded through a flexible
guidewire 174 provided with a positive stop member 175 fixed a
predetermined distance from the distal navigating tip end of the
guidewire 174. A control wire (not shown) attached through the
working catheter 172 is used to axially adjust the position of the
proximal end of the working catheter section 172 in relation to the
stop to thereby form and adjust the relative size of the
essentially circular loop 176. In this manner, the loop 176, 176A
may be made larger or smaller in a given set amount thereby
enabling it to address right atrial chambers of different sizes and
be expanded against arcuate shapes of varying radii. It can also
assume a substantially linear shape prior to or after deployment to
be retracted into the catheter or sheath. Whereas the electrodes
177 are depicted in spaced pairs, other configurations such as that
of FIG. 8 can be used.
[0080] FIGS. 11 and 12 depict opposite-handed circular loops which
can be formed from the working catheter shown broken in FIG. 13.
The device may be predisposed to form a right- or left-handed loop
with regard to a given orientation of the catheter and depending on
the direction of entry into the right atrium or other chamber
and/or the particular surface to be mapped and/or ablated, one or
the other might be preferable. Otherwise, the two are the same.
[0081] With respect to the dimensions of the various embodiments of
the catheters of the invention, the working catheter segments are
typically about 5 French to 8 French in diameter and the sheath
member is approximately 7-10 French in diameter. The catheters
having sheath or side openings, typically extend approximately 5 mm
beyond the openings 30, 126, etc. and approximately 15 cm beyond
the opening in the embodiment of FIG. 9. The working catheter
segments are typically 5-15 cm in length in the case of the
segments 127, 146 and somewhat shorter in the case of segments 32
and 160. The loop configurations of FIGS. 11 and 12 may be any
desired length but typically are such that the loop approximates
the size of the caterpillar design of FIGS. 3, 4 and 8.
[0082] FIG. 10 illustrates an alternate infusion system to that of
FIG. 8, or the like, and includes an infusion port 192 above a
catheter or sheath seal and lock (not shown) and the electrode
conducting wires as at 192 and possibly a guidewire and/or control
member 194 can be provided with passage through the system to the
proximal controls.
[0083] FIG. 14 is a simplified schematic frontal diagram of a heart
140 including a right atrial chamber 142 and right ventricle 144
separated by tricuspid valve 146. The left atrial chamber is shown
at 148 and left ventricle at 150 separated by mitral valve 152. The
inferior vena cava is shown at 154 and the superior vena cava at
156. The ventricular septum is illustrated by 158 and the atrial
septum is shown at 160. A catheter sheath is shown at 162 with
guidewire 164 extending through the inferior vena cava, and through
the right atrium and just penetrating the left atrium at 166. The
guidewire 164 is further shown extending into one of the left
pulmonary veins 168 which connect and lead into the left
atrium.
[0084] FIG. 15a is similar to the schematic diagram of FIG. 14
depicting a guidewire mounted distal working catheter section 170
having a plurality of spaced electrodes 172 deployed in a generally
arcuate shape to contact a segment of the surface of the upper
section of the left atrium. FIG. 15b is similar to FIG. 15a with
the electroded catheter segment 170 deployed in a different contour
contacting a lower surface of the left atrium, possibly in the
vicinity of a cusp of the mitral valve 152. Of course, by advancing
or anchoring the distal end of the guidewire in a pulmonary vein,
as at 168, adjustment of the electroded segment is facilitated.
[0085] In FIG. 15c, the guidewire 164 is shown as extending through
the mitral valve 150 into the left ventricle chamber 150 to
leverage the deployment of the working catheter section 170 against
yet a different atrial wall area. FIG. 15d depicts the use of an
elongated or more fully deployed working catheter section 180 to
contact a longer linear segment of the wall of the left atrium.
[0086] FIG. 16 illustrates an alternate way to effectively employ
the electroded catheters of the invention to map and/or ablate in
the left atrium. It includes a partial schematic diagram of a heart
240 with left atrium 242, left ventricle 244, mitral valve orifice
246 with pulmonary veins as at 248. A portion of the aortic arch is
shown at 250 with aortic valve 252. A guiding deflection control
sheath 254 with distally protruding guidewire 256 is seen entering
the left atrium via mitral valve 246 and the extending guidewire is
again extended into a left pulmonary vein 248.
[0087] FIGS. 17a-17d are similar to FIGS. 15a-15d in that they
portray the deployment of electroded working catheter segments 260
with electrodes 262 within the left atrium in a variety of
dispositions to illustrate the extremely versatile nature of the
catheter embodiment of the invention. The guidewire may be inserted
into a right pulmonary vein as at 249 in some applications as shown
in FIGS. 17a and 17b. The deployments of the FIGS. 14-17 may be
accomplished by any of the catheter embodiments using a distal
guidewire rider as in the embodiments of FIGS. 2-4 and 11-13; or
distal and proximal guidewire riders as in FIG. 8. As illustrated,
any amount of electroded working catheter length necessary can be
employed and linear lesions of any length desired can be
created.
[0088] FIG. 18a further depicts a catheter generally similar to
that of FIG. 8 but which is provided with a single distal guidewire
rider or eye 144 which rides on the guidewire 140. The proximal end
of the working catheter 142 is retained by the sheath 141
independent of the guidewire 140. The guidewire steering distal
floppy hook device is optional and may be removed leaving only a
positive stop illustrated by stopper ball 141 at the distal extreme
of the guidewire. Movement of the guidewire relative to the working
catheter section 142 is used to provide at least part of the
arcuate shaping of the working catheter to address the wall of a
chamber of interest once that chamber is penetrated.
[0089] FIG. 18b shows yet a different control approach in which a
semi-rigid metallic or other type tubular member 155 is threaded
over the guidewire 140 to stabilize the shape of the working
catheter section 142. A radiopaque, preferably metallic, ring
member 157 is shown which can be used to reference the location of
the distal end of the sheath 147. The shape of the radiopaque
member 157 is also such that the directional orientation of the
sheath member 147 can be readily determined. Of course, radiopaque
markers can also be used as desired with any of the embodiments. It
should further be noted that the tubular member 147 should be
flexible enough to readily navigate the necessary vascular passages
as it moves along the guidewire 140 and the member 147 may also be
of a predetermined non-linear shape.
[0090] FIG. 19 represents a rudimentary schematic view of yet
another catheter embodiment generally at 280 illustrating the use
of a double concentric directional deflection sheath system in such
a device. Directional deflective sheath systems are sheaths which
utilize one or more relatively weak or more flexible wall areas
aligned in the same or radially diverse directions serially spaced
for producing greater flexibility in a preferred direction in the
outer wall of the sheath. Thus, a plurality of directional flexure
tendencies may be consecutively induced in a single sheath or in
concentric super-imposed sheaths which overlap and combine to
modulate the total bending characteristics. Either such system is
contemplated for the catheters of the present invention and the
system illustrated at 280 in FIG. 19 is one using a double sheath
layer. The double directed sheath system includes an outer
directional tubular sheath 282 overlaying an inner directional
sheath 284 shown with respective directional notches 283 and
285.
[0091] The directional notches are indicative of but one of a
number of ways to impart the weakness or increased flexibility to
the sheath in a particular direction. Direction control members or
filaments threaded through the sheath system are normally attached
to the internal sheath surface or wall as at 286 and 287 to control
the deflection of the weakened section just proximal of the
attached control member. Other techniques include directionally
weakened wall sections, directionally weakened wall sections used
in cooperation with internal flexure control members and the use of
internal flexure control members alone. These systems are used in
conjunction with axially adjustable control filaments or wires
fixed to the sheath distal of the weakened area sought to be
controlled. Greater details concerning directional sheath systems
including configurations and directional controls for them can be
found in applicant's copending application Ser. No. 08/148,598,
filed Nov. 8, 1993, now U.S. Pat. No. 5,441,483, issued Aug. 15,
1995, entitled "CATHETER DEFLECTION CONTROL", which itself is a
continuation-in-part of Ser. No. 07/976,784, filed Nov. 16, 1992,
abandoned, which are hereby incorporated herein by reference in
their entirety for any necessary purpose.
[0092] The outer sheath may be axially adjustable relative to the
inner sheath and generally will possess a different preferred
directional orientation or tendency to deflect in a different
direction. Interaction between the concentric sheath layers can be
used to adjust the relaxed or controlled shape of the distal
portion of the sheath system just proximal the working catheter
section as shown generally at 286. A guidewire is depicted at 288
with stopper ball 289 and the electroded working catheter section
is shown including electrodes 291 on deployed portion 290.
Electrical leads are depicted at 292.
[0093] It is further apparent that the use of a deflection
controlled sheath member or combination of diversely orientated
direction controlled sheath members represents another important
way to impart additional precision to the control of the navigation
and shape of the electroded working catheter to facilitate proper
placement of the electrode system of many of the embodiments
disclosed. The actual deflection of such member, of course, can be
modulated or controlled by any of many techniques such as those
illustrated in the above incorporated references. Thus, axially
displaceable control elements may be fixed to each active
deflection sheath member below the directional deflection portion
to control deflection with or without auxiliary internal deflection
member, for example.
[0094] Additional alternate control or shape modifying systems are
depicted in FIGS. 22a-22c. In FIG. 22a, an electroded spine or
catheter similar to ones previously shown in conjunction with FIGS.
18a and 18b, for example, has a modified distal extremity fitted
with a nonconductive and relatively rigid distal control member or
element 293 fixed to the distal end at 293a and additional
non-conductive, relatively rigid control elements 294, 295 are
attached between electrodes spaced proximally along the electroded
member 142 as at 196 and 197, respectively. The mode of attachment
of the control members 294 and 295 is such that the member 142 is
free to turn relative to the attached control elements. The
elements 293, 294 and 295 cooperate in axial adjustment as shown in
FIGS. 22b and 22c in more schematic form to control curvature of
the member 142 even to produce a controlled loop configuration at
298 in FIG. 22c. Of course, the control members 294 and 295 must
have sufficient tensile to avoid collapse of the loop 298 which may
attempt to straighten to reassume shape of FIG. 22a.
[0095] In FIG. 23, an embodiment similar to either FIG. 18a or 18b
is provided with an intermediate control element 299 attached to
the catheter or spine 142 at 299a in the manner of those previously
discussed in conjunction with FIGS. 22a-22c, above. The element
299, which may be a non-conducting, relatively rigid control wire
or the like, can be tensioned to adjust the shape of the catheter
142 as necessary intermediate the guide member eye and the sheath
opening. The member 142 resists the modification as it attempts to
resume the arcuate configuration of FIGS. 18a and 18b. Additional
spaced intermediate elements can be used if desired.
[0096] The deployment and shape control techniques associated with
the catheters of the invention including the possible use of active
deflection sheaths all assisting in the control of various catheter
embodiments. FIG. 19 depicts a greatly enlarged schematic view of a
distal fragment of a working catheter section at 300 illustrating
an auxiliary cooling system for use in ablation as can be used with
any of the catheters but is particularly illustrated with a
catheter such as shown in FIGS. 8, 18a and 18b. The catheter is
provided with a system that includes an inner sliding tubular
member 302 operable, within the outer tubular catheter member 304.
A series of spaced ring or hollow bead electrodes are shown that
encircle the outer catheter 304 at 306, a rider or guidewire eye is
shown at 308. The electrodes 306, normally metallic, are further
provided with axially spaced series of radially spaced pores or
effusion openings 310 aligned with congruent or similar openings in
the catheter member 304 to which they are fixed. The tubular member
302 is also provided with effusion openings or pores that can be
aligned with the openings 310. The inner tube 302 is configured to
slide and rotate within the member 304 in a manner that enables the
effusion openings to be aligned or misaligned such that coolant
fluid supplied to the inner tubular member 302 can be effused to
cool or withheld from the electrodes 306 by the relative position
of the member 302.
[0097] FIG. 21 depicts a typical proximal fragment to be used with
the distal fragment of FIG. 20 and includes a sheath with an
infusion port 314 for infusing washing saline or other material to
the member 304 and sheath. A guidewire is shown at 316 with
electrical leads 318. The inner coolant tube 302 is provided with
an infusion port for saline or other benign coolant material at
320.
[0098] The size and number of the openings or pores 310 may vary
but generally a 7 French electrode about 4 mm in length will be
provided with about 4-8 openings having a nominal diameter between
0.2 and 0.6 mm, nominally 0.4 mm. This system helps to control the
temperature as necessary at the ablation sites. Thermocouple or
other temperature monitoring techniques may be employed in a
well-known manner to monitor the electrode temperature if
desired.
[0099] The mapping and ablation system of the invention may also
take on a ribbon like loop configuration. Embodiments of this
category are depicted in FIGS. 24-30. A mapping and ablation ribbon
device shown generaly at 400 is nominally deployed from a distal
end opening 402 of a main steerable vascular catheter or sheath 404
and is shown at least partially deployed in the figures. The ribbon
400 is held in a generally collapsed loop state in the sheath with
two individually deployable and controllable loop segments 406, 408
nested in substantially parallel back to back relation (FIG. 25)
joined by a high strength flexible bridge member 410. This
embodiment is shown in a symmetrical loop expanded disposition in
FIG. 27. An asymmetric arrangement in which the two segments are
deployed unequally as shown in the view of FIG. 28 in which a major
segment 412 is joined to a minor segment 414 by a flexible bridge
at 416. Still another version of the ribbon system is depicted in
the perspective fragmentary views of FIG. 29 and FIG. 30 in which a
ribbon 418 is deployed with the bridge segment 420 at the point of
emergence at the distal end of the sheath 404. This sheath is one
having a plurality of adjustable sheath rings 426 and one or more
deflection control wires as at 427 attached to the sheath at 428 to
control deflection as previously described. This represents a
totally asymmetric arrangement. Of course, symmetry can be
controlled by relative extension of each of the emerging loop
segments.
[0100] The ribbon catheter system like those previously described
carries a serially mounted electrode array consisting of a
plurality of serially arranged electrodes 422 each connected by an
isolated insulated conductive connector or filament as at 424. The
system is configured in a manner such as has been described so that
each electrode is capable of registering an elecrical signal
individually for mapping and can be energized individually as in
any desired combination with other of the electordes of the
catheter to accomplish spot or linear ablation. Linear lesions can
be induced in any orientation in any chamber by proper orientation
of the sheath and loop combination.
[0101] With respect to the electrodes themselves, particularly as
pictured in FIGS. 25, 27 and 28 they may be areas of any desired
size slightly raising above the outer surfaces of the ribbon.
Examples of electordes are shown in FIG. 26. For example, the
electrodes may be as thin as a deposited film or conductive paint
material as at 430, may be configured from a strand of conductive
wire packed in convoluted switch back loops as depicted at 432 or
may be in the form of a segmented condutive pattern as shown at
434. Other types compatible with the ribbon catheter contruction
will occur to the skilled artisan. Typically raised electodes are
in the order of about 0.5 mm thick and 4-5 mm long by 2.5 to 3 mm
wide. The interelectrode distance also may vary but is typically
less than the electrode length so that energizing consecutive
electrodes produces continuous linear lesions.
[0102] It is further contemplated with respect to certain control
wire or guidewire mounted catheter sytems in accordance with the
invnetion to add a further degree of control with respect to the
relative rotational or angular displacement between the wire and
the distal rider or guidewire eye. The ability to control or fix
the distal end with respect to a particular orientation about the
guidewire in a system having an over the wire distal tip
construction enables better control of orientation during
deployment for a mapping and ablation procedure.
[0103] A series of embodiments illustrating tip and wire locking
mechanisms are shown in FIGS. 31-34. FIGS. 31 and 31a depict a ball
and socket type system in which a locking ball member 440 is
attached to the guidewire 442 at the lower end of a floppy tip 444
the guidewire eye 446 of the catheter 448 contains an upper or
distal recess 450 designed to accomodate locking ball 440 as the
wire 442 is withdrawn through the guidewire eye. In FIG. 32 a slot
462 in the tip of catheter 460 is used in combination with a key
464 fixed to central guidewire 466 having floppy tip 468. FIGS. 33a
and 33b depict another embodiment in which a catheter 470 with
offset guidewire eye 472 is slidably engaged on guidewire 474 which
in turn is provided with a fixed shaped locking clip 476 which
locks against a catheter nose shape at 478 when the wire 474 is
retracted. A floppy guide tip is shown t 479. FIG. 34 depicts a
distal catheter tip fragment 480 with guidewire eye 482 threaded
over guidewire 484. The guidewire eye is of a rectangular shape to
accomodate a similary shaped key member 486 fixed to wire 484 just
proximal soft tip 488. Of course, any desired polygon key shape can
be used.
[0104] Another control technique involves fixing the distal end of
the catheter to a control wire or element. This is illustrated in
the fragmentary views of FIGS. 35-37. In FIG. 35, a mapping and
ablation catheter 500 carrying electrodes 502 is shown emerging
with a control wire 504 from a sheath 506. The distal end of the
catheter 500 is permanently connected to the wire 504 at 508 just
proximal pigtail 509. FIG. 36 shows the catheter of FIG. 36 sans
pigtail 509. FIG. 37 depicts the distal tip fragment of a similar
catheter 510 in which the tip 512 is formed into a guiding and
anchoring hook above a permanent attachment point 514 of an
associated control wire 516 just above a distal ring electrode
shown at 518.
[0105] FIG. 38 depicts a sheath, generally 520, for containing a
catheter or other recorded and ablation system such as those
previously described. This system is particularly useful in
addressing the left heart chambers via the right heart chambers. It
has a deflectable are a 522 and a plurality of distal position
recording and x-ray enhancing or locator rings at 524 for locating
the distal end of the sheath. The sheath is also provided with one
or more vent openings 526 which are designed to allow air to be
released at a point sufficiently proximal to the distal end such
that the vent openings remain in the right heart area when the left
heart area is addressed by a mapping and ablation device eminating
from the distal end. In this manner air released from the sheath
volume will be safely exchanged in the lungs prior to the blood
entering the left atrium. The system is designed to contain a
catheter or other recording and ablation device which can be
deployed from the distal end of the sheath.
[0106] This invention has been described herein in considerable
detail in order to comply with the Patent Statutes and to provide
those skilled in the art with the information needed to apply the
novel principles and to construct and use embodiments of the
example as required. However, it is to be understood that the
invention can be carried out by specifically different devices and
that various modifications can be accomplished without departing
from the scope of the invention itself.
* * * * *