U.S. patent application number 14/851469 was filed with the patent office on 2016-01-07 for system and method for positioning an elongate member with respect to an anatomical structure.
The applicant listed for this patent is VytronUS, Inc.. Invention is credited to James W. Arenson, Robert A. Brommer, David A. Gallup, Hira V. Thapliyal.
Application Number | 20160000502 14/851469 |
Document ID | / |
Family ID | 41415453 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160000502 |
Kind Code |
A1 |
Thapliyal; Hira V. ; et
al. |
January 7, 2016 |
SYSTEM AND METHOD FOR POSITIONING AN ELONGATE MEMBER WITH RESPECT
TO AN ANATOMICAL STRUCTURE
Abstract
Methods and apparatus for an ablation device used in the
treatment of atrial fibrillation comprise an elongate shaft and a
positioning mechanism adjacent the distal end of the shaft. The
positioning mechanism is adapted to facilitate location of an
anatomic structure and also to anchor the elongate shaft adjacent
the anatomic structure. The positioning mechanism comprises an
electrode for stimulating the anatomic structure as well as sensing
electrical signals. Also, an energy delivery element is adjacent
the distal end of the shaft and is adapted to stimulate the
anatomic structure and create a zone of ablation that blocks
abnormal electrical activity thereby reducing or eliminating atrial
fibrillation in the patient.
Inventors: |
Thapliyal; Hira V.; (Los
Altos, CA) ; Gallup; David A.; (Alameda, CA) ;
Arenson; James W.; (Woodside, CA) ; Brommer; Robert
A.; (Fremont, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VytronUS, Inc. |
Sunnyvale |
CA |
US |
|
|
Family ID: |
41415453 |
Appl. No.: |
14/851469 |
Filed: |
September 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12480929 |
Jun 9, 2009 |
9155588 |
|
|
14851469 |
|
|
|
|
61061362 |
Jun 13, 2008 |
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Current U.S.
Class: |
606/41 |
Current CPC
Class: |
A61B 2018/00214
20130101; A61B 2018/00898 20130101; A61B 18/02 20130101; A61B
2018/00029 20130101; A61B 2018/00273 20130101; A61B 18/18 20130101;
A61B 2018/00196 20130101; A61B 18/08 20130101; A61B 2018/00279
20130101; A61B 2018/00839 20130101; A61N 7/022 20130101; A61B
2018/1861 20130101; A61B 2018/1475 20130101; A61M 25/01 20130101;
A61B 18/1492 20130101; A61M 25/0082 20130101; A61B 2018/00375
20130101; A61B 2018/00577 20130101 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1. A method of ablating a target tissue, said method comprising:
providing an elongate shaft having a proximal end and a distal end;
positioning the distal end of the elongate shaft adjacent the
target tissue; delivering energy to the target tissue with an
energy delivery element housed within an energy delivery structure
disposed near the distal end of the shaft, without contacting the
target tissue with the energy delivery structure and the energy
delivery element disposed therein, thereby creating a zone of
ablation in the target tissue; and moving the energy delivery
structure along an ablation path while delivering energy with the
energy delivery element, without contacting the zone of ablation
with the energy delivery structure and the energy delivery element
disposed therein.
2. A device for ablating a target tissue, said device comprising:
an elongate shaft having a proximal end and a distal end; an energy
delivery structure disposed near the distal end of the elongate
shaft; and an energy delivery element housed within the energy
delivery structure, the energy delivery element configured to
deliver energy to the target tissue without contacting the target
tissue, thereby creating a zone of ablation in the target tissue,
and wherein the energy delivery structure is configured to move
along an ablation path while the energy delivery element delivers
energy, without contacting the zone of ablation with the energy
delivery structure and the energy delivery element disposed
therein.
Description
CROSS-REFERENCE
[0001] This application is a continuation of U.S. patent
application No. 12/480,929 (Attorney Docket No. 31760-704.201,
formerly 027680-000210US) now U.S. Pat. No. ______ filed Jun. 9,
2009, which is a non-provisional of, and claims priority to U.S.
Provisional Application No. 61/061,362 (Attorney Docket No.
31760-704.101, formerly 027680-000200US) filed Jun. 13, 2008, the
entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates generally to medical devices
and methods, and more specifically to improved devices and methods
for positioning an ablation device in a human or animal patient.
The device may be used to treat atrial fibrillation.
[0003] The condition of atrial fibrillation is characterized by the
abnormal (usually very rapid) beating of left atrium of the heart
which is out of synch with the normal synchronous movement ("normal
sinus rhythm") of the heart muscle. In normal sinus rhythm, the
electrical impulses originate in the sino-atrial node ("SA node")
which resides in the right atrium. The abnormal beating of the
atrial heart muscle is known as fibrillation and is caused by
electrical impulses originating instead in the pulmonary veins
("PV") [Haissaguerre, M. et al., Spontaneous Initiation of Atrial
Fibrillation by Ectopic Beats Originating in the Pulmonary Veins,
New England J Med., Vol. 339:659-666].
[0004] There are pharmacological treatments for this condition with
varying degrees of success. In addition, there are surgical
interventions aimed at removing the aberrant electrical pathways
from PV to the left atrium ("LA") such as the Cox-Maze III
Procedure [J. L. Cox et al., The development of the Maze procedure
for the treatment of atrial fibrillation, Seminars in Thoracic
& Cardiovascular Surgery, 2000; 12: 2-14; J. L. Cox et al.,
Electrophysiologic basis, surgical development, and clinical
results of the maze procedure for atrial flutter and atrial
fibrillation, Advances in Cardiac Surgery, 1995; 6: 1-67; and J. L.
Cox et al., Modification of the maze procedure for atrial flutter
and atrial fibrillation. II, Surgical technique of the maze III
procedure, Journal of Thoracic & Cardiovascular Surgery, 1995;
2110:485-95]. This procedure is shown to be 99% effective [J. L.
Cox, N. Ad, T. Palazzo, et al. Current status of the Maze procedure
for the treatment of atrial fibrillation, Seminars in Thoracic
& Cardiovascular Surgery, 2000; 12: 15-19] but requires special
surgical skills and is time consuming.
[0005] There has been considerable effort to copy the Cox-Maze
procedure for a less invasive percutaneous catheter-based approach.
Less invasive treatments have been developed which involve use of
some form of energy to ablate (or kill) the tissue surrounding the
aberrant focal point where the abnormal signals originate in PV.
The most common methodology is the use of radio-frequency ("RF")
electrical energy to heat the muscle tissue and thereby ablate it.
The aberrant electrical impulses are then prevented from traveling
from PV to the atrium (achieving conduction block within the heart
tissue) and thus avoiding the fibrillation of the atrial muscle.
Other energy sources, such as microwave, laser, and ultrasound have
been utilized to achieve the conduction block. In addition,
techniques such as cryoablation, administration of ethanol, and the
like have also been used.
[0006] There has been considerable effort in developing the
catheter based systems for the treatment of AF using radiofrequency
(RF) energy. One such method is described in U.S. Pat. No.
6,064,902 to Haissaguerre et al. In this approach, a catheter is
made of distal and proximal electrodes at the tip. The catheter can
be bent in a J shape and positioned inside a pulmonary vein. The
tissue of the inner wall of the PV is ablated in an attempt to kill
the source of the aberrant heart activity. Other RF based catheters
are described in U.S. Pat. Nos. 6,814,733 to Schwartz et al.,
6,996,908 to Maguire et al., 6,955,173 to Lesh; and 6,949,097 to
Stewart et al.
[0007] Another source used in ablation is microwave energy. One
such device is described by Dr. Mark Levinson [(Endocardial
Microwave Ablation: A New Surgical Approach for Atrial
Fibrillation; The Heart Surgery Forum, 2006] and Maessen et al.
[Beating heart surgical treatment of atrial fibrillation with
microwave ablation. Ann Thorac Surg 74: 1160-8,2002]. This
intraoperative device consists of a probe with a malleable antenna
which has the ability to ablate the atrial tissue. Other microwave
based catheters are described in U.S. Pat. Nos. 4,641,649 to
Walinsky; 5,246,438 to Langberg; 5,405,346 to Grundy, et al.; and
5,314,466 to Stem, et al.
[0008] Another catheter based method utilizes the cryogenic
technique where the tissue of the atrium is frozen below a
temperature of -60 degrees C. This results in killing of the tissue
in the vicinity of the PV thereby eliminating the pathway for the
aberrant signals causing the AF [A. M. Gillinov, E. H. Blackstone
and P. M. McCarthy, Atrial fibrillation: current surgical options
and their assessment, Annals of Thoracic Surgery 2002; 74:2210-7].
Cryo-based techniques have been a part of the partial Maze
procedures [Sueda T., Nagata H., Orihashi K., et al., Efficacy of a
simple left atrial procedure for chronic atrial fibrillation in
mitral valve operations, Ann Thorac Surg 1997; 63:1070-1075; and
Sueda T., Nagata H., Shikata H., et al.; Simple left atrial
procedure for chronic atrial fibrillation associated with mitral
valve disease, Ann Thorac Surg 1996; 62: 1796-1800]. More recently,
Dr. Cox and his group [Nathan H., Eliakim M., The junction between
the left atrium and the pulmonary veins, An anatomic study of human
hearts, Circulation 1966; 34:412-422, and Cox J. L., Schuessler R.
B., Boineau J. P., The development of the Maze procedure for the
treatment of atrial fibrillation, Semin Thorac Cardiovasc Surg
2000; 12:2-14] have used cryoprobes (cryo-Maze) to duplicate the
essentials of the Cox-Maze III procedure. Other cryo-based devices
are described in U.S. Pat. Nos. 6,929,639 and 6,666,858 to
Lafintaine and 6,161,543 to Cox et al.
[0009] More recent approaches for the AF treatment involve the use
of ultrasound energy. The target tissue of the region surrounding
the pulmonary vein is heated with ultrasound energy emitted by one
or more ultrasound transducers. One such approach is described by
Lesh et al. in U.S. Pat. No. 6,502,576. Here the catheter distal
tip portion is equipped with a balloon which contains an ultrasound
element. The balloon serves as an anchoring means to secure the tip
of the catheter in the pulmonary vein. The balloon portion of the
catheter is positioned in the selected pulmonary vein and the
balloon is inflated with a fluid which is transparent to ultrasound
energy. The transducer emits the ultrasound energy which travels to
the target tissue in or near the pulmonary vein and ablates it. The
intended therapy is to destroy the electrical conduction path
around a pulmonary vein and thereby restore the normal sinus
rhythm. The therapy involves the creation of a multiplicity of
lesions around individual pulmonary veins as required. The
inventors describe various configurations for the energy emitter
and the anchoring mechanisms.
[0010] Yet another catheter device using ultrasound energy is
described by Gentry et al. [Integrated Catheter for 3-D
Intracardiac Echocardiography and Ultrasound Ablation, IEEE
Transactions on Ultrasonics, Ferroelectrics, and Frequency Control,
Vol. 51, No.7, pp 799-807]. Here the catheter tip is made of an
array of ultrasound elements in a grid pattern for the purpose of
creating a three dimensional image of the target tissue. An
ablating ultrasound transducer is provided which is in the shape of
a ring which encircles the imaging grid. The ablating transducer
emits a ring of ultrasound energy at 10 MHz frequency. In a
separate publication [Medical Device Link, Medical Device and
Diagnostic Industry, February 2006], in the description of the
device, the authors assert that the pulmonary veins can be
imaged.
[0011] While these devices and methods are promising, improved
devices and methods for positioning a device relative to an
anatomic structure such as the pulmonary vein are needed.
Furthermore, it would also be desirable if such devices could
create single or multiple ablation zones to block abnormal
electrical activity in the heart in order to lessen or prevent
atrial fibrillation. Such devices and methods should be easy to
use, cost effective and simple to manufacture.
Description of Background Art
[0012] Other devices based on ultrasound energy to create
circumferential lesions are described in U.S. Pat. Nos. 6,997,925;
6,966,908; 6,964,660; 6,954,977; 6,953,460; 6,652,515; 6,547,788;
and 6,514,249 to Maguire et al.; 6,955,173; 6,052,576; 6,305,378;
6,164,283; and 6,012,457 to Lesh; 6,872,205; 6,416,511; 6,254,599;
6,245,064; and 6,024,740; to Lesh et al.; 6,383,151; 6,117,101; and
WO 99/02096 to Diederich et al.; 6,635,054 to Fjield et al.;
6,780,183 to Jimenez et al.; 6,605,084 to Acker et al.; 5,295,484
to Marcus et al.; and WO 2005/117734 to Wong et al.
[0013] In all above approaches, the inventions involve the ablation
of tissue inside a pulmonary vein or at the location of the ostium.
The anchoring mechanisms engage the inside lumen of the target
pulmonary vein. In all these approaches, the anchor is placed
inside one vein, and the ablation is done one vein at a time.
SUMMARY OF THE INVENTION
[0014] The present invention generally relates to medical devices
and methods and more particularly relates to devices and methods
for positioning an ablation device used in the treatment of atrial
fibrillation.
[0015] In a first aspect of the present invention, an ablation
device for treating atrial fibrillation in a patient comprises an
elongate shaft having a proximal end and a distal end. A
positioning mechanism is adjacent the distal end of the shaft and
is adapted to facilitate location of an anatomic structure and also
adapted to anchor the elongate shaft adjacent the anatomic
structure. The positioning mechanism comprises an electrode for
stimulating the anatomic structure and also for sensing electrical
signals from the anatomic structure. An energy delivery element is
adjacent the distal end of the shaft and is adapted to stimulate
the anatomic structure and create a zone of ablation that blocks
abnormal electrical activity thereby reducing or eliminating atrial
fibrillation in the patient.
[0016] The elongate shaft may comprise a lumen extending between
the proximal and ends of the shaft. The shaft may be rotatable
around the positioning mechanism. The shaft may also have a
sidewall with a window therethrough, and the energy delivery
element may be adapted to stimulate the anatomic structure through
the window.
[0017] The positioning mechanism may be slidably disposed in the
lumen, and it may be in a substantially linear configuration while
disposed in the lumen. The positioning mechanism may exit the shaft
via an aperture in a sidewall of the shaft. The positioning
mechanism may comprises a coil or a plurality of wires expandable
from a contracted configuration to an expanded configuration. In
the expanded configuration, the plurality of wires may form a
cage-like structure. The plurality of wires may also be biased to
flare radially outward when unconstrained. The positioning
mechanism may be adapted to exert an outward biasing force against
an interior surface of the anatomical structure thereby anchoring
the elongate shaft thereto. The anatomic structure may be a
pulmonary vein and the positioning mechanism may be adapted to
indicate an angle of entry of the elongate shaft into the pulmonary
vein. In still other embodiments, the positioning mechanism may
comprise a proximal wire and a distal wire, both proximal and
distal wires at least partially encircling the elongate shaft.
[0018] The electrode may operate in a monopolar mode or the
electrode may comprise a plurality of electrodes operating in a
bipolar mode.
[0019] The energy delivery element may comprise an ultrasound
transducer. The energy delivery element may also be adapted to
deliver radiofrequency energy, microwaves, light energy, thermal
energy, or cryogenic cooling to the anatomic structure. The zone of
ablation may be a linear region, an annular region, or an arcuate.
The zone of ablation may encircle one or more than one pulmonary
veins or the zone of ablation may be outside of and adjacent a
pulmonary vein. The energy delivery element often may remain
unobstructed by the positioning mechanism.
[0020] In another aspect of the present invention, a method of
ablating an anatomic structure in a patient as a treatment for
atrial fibrillation comprises providing an elongate shaft having a
proximal end and a distal end and locating the anatomic structure
with a positioning mechanism disposed adjacent the distal end of
the shaft. The shaft is anchored adjacent the anatomic structure
with the positioning mechanism and an electrode adjacent a distal
portion of the positioning mechanism is used to electrically
stimulate or sense electrical signals from the anatomic structure.
Energy is delivered to the anatomic structure with an energy
delivery element near the distal end of the shaft, thereby creating
a zone of ablation that blocks abnormal electrical activity in
order to reduce or eliminate atrial fibrillation in the
patient.
[0021] The elongate shaft may comprise a lumen extending between
the proximal and distal ends and the method may further comprise
delivering a fluid from the lumen to the anatomic structure. The
step of locating the anatomic structure may comprise visualizing
the anatomic structure, or tactile or audible feedback. The
positioning mechanism may be advanced from or retracted into the
elongate shaft during the step of locating. The positioning
mechanism may comprise a plurality of wires and the anatomic
structure may be located by deflecting at least some of the
plurality of wires. Locating the anatomic structure may also
comprise determining an entry angle of the elongate shaft into the
anatomic structure.
[0022] The step of anchoring the shaft may comprise engaging the
positioning mechanism against the anatomical structure and exerting
an outward biasing force against an interior surface of the
anatomical structure. Anchoring may also comprise forming and
engaging a cage-like structure on the positioning mechanism with
the anatomic structure.
[0023] The step of stimulating the anatomic structure may comprise
stimulating in a monopolar or bipolar mode. Stimulating may also
comprise pacing the patient's heart. The stimulating step may be
performed before, during or after creation of the ablation
zone.
[0024] Delivering energy to the anatomic structure may comprise
delivering one of ultrasound energy, radiofrequency energy,
microwave, light, and thermal energy. The step of creating the zone
of ablation may comprise creating a linear or arcuate ablation path
such as when the zone of ablation encircles one or more than one
pulmonary vein. Sometimes the elongate shaft may be rotated around
the positioning mechanism while delivering energy. The energy may
be delivered through a window in the elongate shaft and the energy
may be directed at an angle between 65 and 115 degrees to the
anatomic structure. Delivering energy may comprise adjusting power,
frequency, bandwidth, or amplitude of the energy delivered to the
anatomic structure. The method may further comprise cooling the
anatomic structure with cooling fluid.
[0025] These and other embodiments are described in further detail
in the following description related to the appended drawing
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1A and 1B are drawings of the system of the preferred
embodiment of the invention;
[0027] FIGS. 2-4 are drawings of three rotation variations of the
system of the preferred embodiment of the invention;
[0028] FIGS. 5-8C are drawings of a first variation of the
positioning mechanism of the system of the preferred embodiment of
the invention;
[0029] FIGS. 9A and 9B are drawings of a second variation of the
positioning mechanism of the system of the preferred embodiment of
the invention;
[0030] FIGS. 10A and 10B are drawings of a third variation of the
positioning mechanism of the system of the preferred embodiment of
the invention;
[0031] FIG. 11 is a drawing of a fourth variation of the
positioning mechanism of the system of the preferred embodiment of
the invention; and
[0032] FIG. 12 is a drawing of a fifth variation of the positioning
mechanism of the system of the preferred embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The following description of preferred embodiments of the
invention is not intended to limit the invention to these
embodiments, but rather to enable any person skilled in the art to
make and use this invention.
[0034] As shown in FIGS. 1A and 2, the system 10 of the preferred
embodiments includes an elongate member 12 and a positioning
mechanism 14 coupled to the elongate member 12. The elongate member
12 may be radiopaque to allow it to be seen during fluoroscopy.
This may be achieved with radiopaque marker bands or by including
radiopaque filler materials in the elongate member such as barium
sulfate or titanium dioxide. The positioning mechanism 14 performs
one or more of the following functions: (a) facilitate locating an
anatomical structure (preferably a pulmonary vein 3000 in a left
atrium of a heart 3002, but alternatively any other suitable
anatomical structure), (b) anchor the elongate member 12 with
respect to the anatomical structure, and (c) electrically stimulate
and/or sense electrical signals from the anatomical structure. The
system 10 is preferably designed for positioning an elongate member
within a patient and, more specifically, for positioning a therapy
and/or navigation catheter with respect to a pulmonary vein in the
left atrium of the heart of a patient. The system 10, however, may
be alternatively used in any suitable environment and for any
suitable reason.
The Elongate Member
[0035] The elongate member 12 of the preferred embodiments is a
catheter made of a flexible multi-lumen tube, but may alternatively
be a cannula, tube or any other suitable elongate structure having
one or more lumens. The elongate member 12 preferably has a
separate lumen that houses the positioning mechanism 14, but may
alternatively house the positioning mechanism 14 in any other
suitable configuration. The elongate member 12 preferably houses a
single positioning mechanisms 14 (as shown in FIG. 1A), but may
house more than one positioning mechanisms (as shown in FIG. 2).
The elongate member 12 of the preferred embodiments functions to
accommodate pull members, fluids, gases, energy delivery
structures, electrical connections, therapy catheters, navigation
catheters, pacing catheters, and/or any other suitable device or
element. As shown in FIG. 2, the elongate member 12 preferably
includes a distal tip assembly 16 positioned at a distal portion of
the elongate member 12. The distal tip assembly 16 preferably
houses an energy delivery structure 18 that functions to deliver
energy 20 to tissue, such as tissue of a heart 3002. The energy
delivery structure 18 preferably includes an ultrasound transducer
subassembly, but may alternatively include any other suitable
source of ablation energy such as radio frequency (RF) energy,
microwaves, photonic energy, and thermal energy. Ablation could
alternatively be achieved using cooled fluids (e.g., cryogenic
fluid).
The Positioning Mechanism
[0036] As shown in FIGS. 1A and 1B, the positioning mechanism 14 of
the preferred embodiments is coupled to a distal portion of the
elongate member 12. As shown in FIG. 1A, the positioning mechanism
14 is preferably coupled to the distal tip of the elongate member
12. The positioning mechanism 14 is preferably coupled to the
distal tip of the elongate member 14 such that fluid (for cooling
the energy delivery system 18 or for cooling the tissue, for
example) is able to flow through a lumen in the elongate member 12
and exit out of the elongate member as necessary. Alternatively, as
shown in FIG. 1B, the positioning mechanism 14 is preferably
coupled to the side of the elongate member 12 near the distal end
of the elongate member 12. In some variations, the positioning
member 14 is retractable into and exits from the elongate member 12
through the distal end or through a notch 22 near the distal end of
the elongate member 12. In these variations, the positioning member
14 preferably is held in or moves to a smaller configuration (by
folding, straightening, etc.) such that it fits within the elongate
member 12. The positioning member, when residing completely inside
a lumen of the elongate member 12, is preferably held in a
generally straight shape, conforming to confines of the lumen. As
the positing member 14 is advanced outwards, and/or as it exits the
notch 22, it preferably takes on a predetermined shape, for example
as shown in FIGS. 1B, 5, and 11.
[0037] As shown in FIG. 2, the positioning mechanism 14 of the
preferred embodiments performs one or more of the following
functions: (a) facilitate locating an anatomical structure, (b)
anchor the elongate member 12 with respect to the anatomical
structure, and (c) electrically stimulate and/or sense electrical
signals from the anatomical structure. Regarding the first
function, the positioning mechanism 14 facilitates locating an
anatomical structure by providing an indication of where the
positioning mechanism 14 is with respect to the anatomical
structure. The indication is preferably a visual indication (via a
medical imaging system such as a fluoroscope), but is alternatively
or additionally a tactile or audible indication. Additionally, the
elongate member 12 and/or the positioning mechanism 14 may include
indicia, such as markings indicating distance, that indicate the
location of the anatomical structure and/or to indicate the depth
of insertion of the system 10 where the anatomical structure was
located.
[0038] Regarding the second function, the positioning mechanism 14
anchors the elongate member 12 with respect to the anatomical
structure by coupling to a portion of an anatomical structure (for
example a pulmonary vein 3000 and/or a left atrium 3002 of a heart)
and by providing stabilization of the elongate member 12 when
manipulating at least a portion of the elongate member 12 and/or by
providing an axis of rotation to the elongate member 12 as it is
rotated. The elongate member 12 is preferably manipulated to
position the energy delivery structure 18 within the left atrium of
the heart 3002 (or in any other suitable location) and, once
positioned there, is preferably manipulated to move the energy
delivery structure 18 along an ablation path and to direct the
energy delivery structure 18 towards tissue to provide a partial or
complete zone of ablation along the ablation path. The ablation
path preferably has any suitable geometry or geometries to provide
a conduction block--isolation and/or block of conduction pathways
of abnormal electrical activity, which typically originate from the
pulmonary veins in the left atrium--for treatment of atrial
fibrillation in a patient, but may alternatively provide any other
suitable therapy. A linear ablation path is preferably created by
moving and bending the elongate member 12 in an X, Y, and/or Z
direction. A generally circular or elliptical ablation path 30 is
preferably created by rotating the elongate member 12 about an
axis. The elongate member 12 is preferably rotated in one of
several variations. In a first variation, as shown in FIG. 2, the
elongate member is rotated, as shown by arrow 3010, around the two
positioning mechanisms 14, the energy delivery structure 18
preferably sweeps a generally circular ablation path 30. The two
positioning mechanisms 14 preferably assure that the rotation of
the elongate member 12 and therefore the energy delivery structure
18 will occur in an ablation path 30 outside of the pulmonary veins
3000 and 3000'. The ablation path 30 may alternatively encircle a
single pulmonary vein or encircle any other suitable number of
pulmonary veins.
[0039] In a second variation, as shown in FIG. 3, the elongate
member is rotated, as shown by arrow 3012, within the pulmonary
vein 3000 such that the energy delivery structure 18 preferably
sweeps a generally circular ablation path 30, generally
perpendicular to the axis of the pulmonary vein 3000. In an
alternative version of this second variation, the elongate member
may alternatively be located outside of and adjacent to the
pulmonary vein while still generally perpendicular to the axis of
the pulmonary vein 3000. The elongate member is preferably rotated
such that the energy delivery structure 18 preferably sweeps a
generally circular ablation path 30 around at least one ostium of a
pulmonary vein. In this version of the second variation, the energy
delivery structure 18 is preferably angled such that it is
preferably at an acute angle with respect to the axis of the
elongate member and such that the energy delivery structure
preferably points and delivers energy 20 substantially towards the
atrial wall and around the pulmonary vein ostium. In the second
variation, the energy delivery structure 18 preferably rotates
within the distal tip assembly 16, delivering ablation energy
though a window that runs around the circumference of the distal
tip assembly 16. The window is preferably made of a material that
is transparent to ultrasound waves such as a poly 4-methyl,
1-pentene (PMP) material or may alternatively be an open window.
Alternatively, the elongate member 12 and/or distal tip assembly 16
may rotate, rotating the energy delivery structure within. The
positioning mechanism 14 preferably does not rotate along with the
elongate member 12 and/or the distal tip assembly 16.
[0040] In a third variation, as shown in FIG. 4, the positioning
mechanism 14 is pressed against a portion of a heart chamber (such
as the ceiling wall of the left atrium), or in any other suitable
location and the elongate member 12 is rotated, as shown by arrow
3014, around the axis created by the positioning mechanism 14, the
energy delivery structure 18 preferably sweeps a generally circular
ablation path outside of the pulmonary veins 3000 and 3000'. The
ablation path may alternatively encircle a single pulmonary vein or
any other suitable number of pulmonary veins.
[0041] In all variations, the energy delivery structure is
preferably positioned with respect to the tissue at an appropriate
angle. The energy delivery system is preferably directed towards
the target tissue at an angle between 20 and 160 degrees to the
tissue, more preferably at an angle between 45 and 135 degrees to
the tissue, and most preferably at an angle of 65 and 115 degrees
to the tissue.
[0042] Regarding the third function, the positioning mechanism 14
electrically stimulates and/or senses electrical signals from the
anatomical structure by electrically coupling to the anatomical
structure and sending and/or receiving electrical signals to the
tissue. The positioning mechanism 14 preferably includes an even
number of electrodes or electrically active portions such that a
bipolar electrical system may be used, wherein each pair of
electrodes or electrically active portions has an opposite
polarity. The positioning mechanism 14 may alternatively include a
single electrode or electrically active portion and use a monopolar
electrical system, or may include any other suitable number of
electrodes or electrically active portions. The positioning
mechanism 14 functions to map the tissue by sensing the electrical
conduction between the pulmonary veins and the other parts of the
atrial wall on the endocardial side. The positioning mechanism 14
functions to pace the tissue and maintain an artificial heart rate
(preferably temporarily) by sending electrical pulses to the
tissue. The positioning mechanism 14 preferably paces the tissue
located in a position distal from the energy delivery structure 18
and/or the ablation path 30, such that the energy delivery
structure 18 and/or the ablation path 30 are between the
positioning mechanism 14 that is pacing and the beating heart. The
positioning mechanism may alternatively pace tissue in any other
suitable location. The recording and sensing signals received and
sent by the positioning mechanism are preferably compatible with
conventional navigation and mapping systems such as CARTO XP EP
Navigation System (Biosense Webster, Diamond Bar, Calif.), EnSite
System (St. Jude Medical, St. Paul, Minn.), and/or any other
suitable mapping, navigation, or visualization system.
[0043] As mentioned above, the positioning mechanism 14 of the
preferred embodiments performs one or more of the following
functions: (a) facilitate locating an anatomical structure, (b)
anchor the elongate member 12 with respect to the anatomical
structure, and (c) electrically stimulate and/or sense electrical
signals from the anatomical structure. Although the positioning
mechanism 14 is preferably one of the several variations described
below, the positioning mechanism 14 may be any suitable mechanism
to perform one or more of these functions.
First Variation of the Positioning Mechanism
[0044] In a first variation, as shown in FIGS. 5, 6A, and 6B, the
positioning mechanism 14' includes a plurality of wires each having
a first end 24 and a second end 26. The plurality of wires are
preferably flexible wires, but may alternatively be movable in any
other suitable fashion. The first end 24 is preferably coupled to
the distal tip of the elongate member 12, but may alternatively be
attached in any other suitable location (shown in FIG. 4). The
second end 26 preferably extends from the distal tip of the
elongate member and is positioned in a fully extended position, as
shown in FIG. 5. The second end 26 preferably deflects due to
contact with a surface, as shown in FIGS. 6A and 6B. The second end
26 is preferably biased towards the fully extended position, but
may alternatively be biased towards any other suitable position.
The first end 24 is preferably slidably coupled to the elongate
member 12 such that it is partially or fully retractable into the
elongate member 12. For example, the plurality of wires may be
pushed or pulled through the distal tip of the elongate member 12
by a wire that extends through the elongate member 12. The
plurality of wires may be pulled back through the distal tip of the
elongate member 12 in order to return the wires to the fully
extended position, as shown in FIG. 5. The plurality of wires may
alternatively be fixed to the distal tip of the elongate member 12
or coupled to the elongate member 12 in any other suitable fashion.
The wires are preferably made from a conductive material and/or a
material with shape memory such as nickel/titanium or a shape
memory polymer. The material is preferably flexible so as not to
cause injury to the tissue of the heart where the positioning
mechanism 14' might contact and move against it. At least a portion
of each wire is preferably made from a fluoro-opaque material, such
as platinum or gold, such that it may be seen while positioned
inside the internal structures of a patient through the use of a
fluoroscope. The fluoro-opaque portion 28 is preferably located at
the second end 26 of a wire, but may alternatively be located in
any suitable position such that it may be seen while positioned
inside the internal structures of a patient through the use of a
fluoroscope. The fluoro-opaque portion is preferably flush with the
wire, but may alternatively have a round or any other suitable
shape such that it will not damage the tissue. Additionally, the
plurality of wires preferably includes at least one electrically
active portion and/or at least one insulated portion (e.g. an
insulating coating on a portion of each wire). The electrically
active portion is preferably located at the second end 26 of a
wire, but may alternatively be located in any suitable position,
such as the center portion, such that it conies in contact with
tissue.
[0045] The plurality of wires preferably has any suitable geometry
such that positioning mechanism 14' may perform any combination of
functions described. Additionally, the plurality of wires
preferably have a length and/or geometry such that when they
deflect, they do not cover, block, or lay in front of the energy
delivery structure 18, or any portion thereof Therefore, they
preferably do not block any portion of the energy delivered by the
energy delivery structure 18 and cause a "shadow" effect. In a
first version, as shown in FIG. 5, the wires are substantially
straight. In a second version, as shown in FIG. 8A, the wires are
curved or bent such that they are biased away from the elongate
member 12. In a third version, as shown in FIG. 8B, the plurality
of wires includes six wires circumferentially disposed around the
elongate member 12. The plurality of wires preferably includes an
even number of wires, but may alternatively include a single wire
or any other suitable number of wires. In a fourth version, as
shown in FIG. 8C, the plurality of wires includes multiple tiers or
layers of wires. Each tier or layer may include any suitable number
of wires and each tier or level may include a different number of
wires from any other tier or level.
[0046] As shown in FIGS. 6A and 6B, the plurality of wires function
to facilitate locating an anatomical structure by flexing as they
come in contact with the anatomical structure. For example, the
wires will remain fully extended from the elongate member 12 when
they are unobstructed in the left atrium of the heart 3002, as
shown in FIG. 4. As the system 10 is moved within the left atrium
of the heart 3002 and begins to contact the ostium (opening) of a
pulmonary vein 3000, the plurality of wires will begin to deflect
partially, as shown in FIG. 6A. As the system 10 is moved into the
pulmonary vein 3000, the wires will deflect more dramatically as
shown in FIG. 6B. As the system is moved deeper into the pulmonary
vein, the wires will not deflect as much, if at all, and an
operator of the system 10 will be able to determine when the
positioning mechanism 14 of the system 10 is correctly located
within the pulmonary vein.
[0047] Furthermore, as shown in FIG. 7, the angle 3004 at which the
system 10 enters the pulmonary vein 3000 with respect to the
longitudinal axis of the pulmonary vein 3000 is determined. For
example, if the system 10 is entering the pulmonary vein 3000 at
angle 3004, a wire to the left of the elongate member 12 will
deflect to an angle 3006 with respect to the elongate member 12
while a wire to the right of the elongate member 12 will deflect to
an angle 3008 with respect to the elongate member 12. Therefore,
the angle 3004 at which the system 10 is entering the pulmonary
vein 3000 is preferably determined from the size of angles 3006 and
3008. These angles 3006 and 3008 are preferably detected visually
under fluoroscopic guidance by the operator of the system 10, but
may alternatively be detected and processed by a processor in order
to determine angle 3004. Upon the detection of the angle 3004, an
operator of the system 10 is alerted of an off-center entry, the
operator adjusts and centers the system 10 and/or is instructed on
how to do so. The system 10 may alternatively be adjusted
automatically through a motor drive system or any other suitable
system. The ablation path 30 is preferably altered such that energy
delivery structure will be located substantially the same distance
from each point of tissue along the ablation path 3 and/or the
energy delivery structure is preferably adjusted to accommodate an
off-center entry. The energy delivery structure is preferably
adjusted by changing the power and/or frequency, bandwidth, and
amplitude of the sound wave propagated into the tissue along
certain portions of an ablation path 30. Due to an off-center
entry, the energy delivery structure will be closer to some tissue
along the ablation path 30 and further away from other tissue. In
one example, the energy delivery structure is adjusted to use less
power for the portions of the tissue that are closer to the energy
delivery structure.
[0048] The plurality of wires function to anchor the elongate
member 12 with respect to the anatomical structure, preferably a
pulmonary vein 3000, by coupling to the anatomical structure. The
outward biasing force of the plurality of wires against the
interior wall of the pulmonary vein will preferably hold the
positioning mechanism 14' within the pulmonary vein due to
friction. Alternatively, the tips of the plurality of wires may
function as barbs such that the plurality of wires are preferably
advanced into the pulmonary vein, but the tips of the wires will
prevent the positioning mechanism 14 from being pulled out of the
pulmonary vein. In this version, the wires may be manually
retracted upon completion of the procedure to allow for the removal
of the positioning mechanism 14'. The positioning mechanism may
alternatively function to anchor the elongate member 12 with
respect to the anatomical structure in any other suitable
fashion.
Second Variation of the Positioning Mechanism
[0049] In a second variation, as shown in FIGS. 9A and 9B, the
positioning mechanism 14'' includes a plurality of wires, a first
end cap 32, a second end cap 34, and a pull member 36. The
plurality of wires are circumferentially disposed around the
elongate member 12. The plurality of wires preferably includes an
even number of wires such as two, four, six, eight, or more, but
may alternatively include a single wire or any other suitable
number of wires. The first end cap 32 is preferably coupled to the
distal tip of the elongate member 12, but may alternatively be
attached in any other suitable location, as shown in FIG. 4. The
second end cap 34 preferably extends from the distal tip of the
elongate member 12 along the longitudinal axis of the elongate
member 12 and transitions between a fully extended position, as
shown in FIG. 9A, and a retracted position, as shown in FIG. 9B.
When the second end cap 34 is in the fully extended position, the
wires are preferably substantially straight. When the second end
cap 34 is in the retracted position, the wires preferably flex and
bend at one location along the wire to form a basket or cage-like
structure. The second end cap 34 preferably transitions between a
fully extended position and a retracted position by pulling the
pull member 36. The pull member 36 is preferably coupled to the
second end cap 34 and runs through the first end cap 32 such that
the first end cap 32 is slidably coupled to the pull member 36.
Preferably, the pull member 36 is attached to the second end cap 34
with an adhesive band, but may alternatively be coupled to the
second end cap 34 with any other suitable chemical and/or
mechanical connection such as adhesive, welding, pins and/or
screws. The pull member is preferably disposed within a lumen of
the first end cap and the elongate member 12, but may alternatively
be held in any suitable location. The pull member preferably
terminates at a slider in a proximal housing (not shown) that
preferably includes various actuating mechanisms to transition the
second end cap from the fully extended position to the retracted
position. The second end cap preferably returns to the fully
extended position by the spring force of the plurality of wires
(they are preferably biased towards the substantially straight
position), but may alternatively return to the fully extended
position in any other suitable fashion.
[0050] The wires may alternatively flex or bend in multiple
locations and each wire may bend in a different location. The wires
are preferably biased towards the substantially straight position,
but may alternatively be biased towards the bent position or any
other suitable position. The wires are preferably made from a
conductive material and/or a material with shape memory such as
nickel/titanium alloys or a shape memory polymer, but may
alternatively be made from any suitable material such as plastic.
The material is preferably flexible so as not to cause injury to
the tissue of the heart where the positioning mechanism 14 might
contact and move against it. At least a portion of each wire is
preferably made from a fluoro-opaque material (also referred to
herein using the term "radiopaque"), such as platinum or gold, such
that it may be seen while positioned inside the internal structures
of a patient through the use of a fluoroscope. The fluoro-opaque
portion is preferably located in any suitable position such that it
may be seen while positioned inside the internal structures of a
patient through the use of a fluoroscope. The fluoro-opaque portion
is preferably flush with the wire, but may alternatively have a
round or any other suitable shape such that it will not damage the
tissue. Additionally, the plurality of wires preferably includes at
least one electrically active portion and/or at least one insulated
portion (e.g. an insulating coating on a portion of each wire). The
electrically active portion is preferably located towards the
center portion of each wire, but may alternatively be located in
any suitable position such that it comes in contact with
tissue.
[0051] The positioning mechanism 14'' functions to facilitate
locating an anatomical structure by the plurality of wires flexing
as they come in contact with the anatomical structure. For example,
when the wires are flexed or bent as shown in FIG. 9B, and as the
system 10 is moved within the left atrium of the heart 3002 and
begins to contact the ostium (opening) of a pulmonary vein 3000,
the plurality of wires will begin to deflect inward or away from
the adjacent wires due to contact with a tissue surface. As the
system is moved deeper into the pulmonary vein, the wires will not
deflect as much if at all, and an operator of the system 10 will be
able to determine when the positioning mechanism 14'' of the system
10 is correctly located within the pulmonary vein.
[0052] The plurality of wires of the positioning mechanism 14''
function to anchor the elongate member 12 with respect to the
anatomical structure, preferably a pulmonary vein 3000, by coupling
to the anatomical structure. Preferably, the outward force of the
plurality of wires in the flexed or bent position, as shown in FIG.
9B, against the interior wall of the pulmonary vein will hold the
positioning mechanism 14'' within the pulmonary vein due to
friction. In this version, the second end cap 34 will be returned
to the fully extended position upon completion of the procedure,
straightening the plurality of wires, to allow for the removal of
the positioning mechanism 14''. The positioning mechanism 14'' may
alternatively function to anchor the elongate member 12 with
respect to the anatomical structure in any other suitable
fashion.
Third, Fourth, and Fifth Variation Positioning Mechanism
[0053] In a third variation, as shown in FIGS. 10A and 10B, the
positioning mechanism is a combination of the first and second
variations of the positioning mechanisms 14' and 14''. In this
variation, the positioning mechanism preferably includes two
pluralities of wires. The first plurality of wires has a first end
24 and a second end 26 as described above, and the second plurality
of wires has a first end cap 32, a second end cap 34, and a pull
member 36 also as described above. When the second end cap 34 is in
the retracted position, as shown in FIG. 10B, the second plurality
of wires preferably flex and bend in one location to form a basket
or cage-like structure. The first plurality of wires deflect due to
contact with a surface and will preferably deflect down and in
between the second plurality of wires such that they will not
obstruct the function of the second plurality of wires.
[0054] In a fourth variation, as shown in FIG. 11, the positioning
mechanism 14' is a coil. The coil is preferably made from a
conductive material and/or a material with shape memory such as
nickel/titanium alloys or a shape memory polymer. The material is
preferably flexible so as not to cause injury to the tissue of the
heart where the positioning mechanism 14 might contact and move
against it. At least a portion of the coil is preferably made from
a fluoro-opaque material, such as platinum or gold, such that it
may be seen while positioned inside the internal structures of a
patient through the use of a fluoroscope. The fluoro-opaque portion
is preferably located in any suitable position such that it may be
seen while positioned inside the internal structures of a patient
through the use of a fluoroscope. The fluoro-opaque portion is
preferably flush with the wire, but may alternatively have a round
or any other suitable shape such that it will not damage the
tissue. Additionally, the coil preferably includes at least one
electrically active portion and/or at least one insulated portion
(e.g. an insulating coating on a portion of each wire). The
electrically active portion is preferably located in any suitable
position such that it comes in contact with tissue.
[0055] The positioning mechanism 14''' functions to facilitate
locating an anatomical structure by the coil flexing as it comes in
contact with the anatomical structure. For example, as the system
10 is moved within the left atrium of the heart 3002 and begins to
contact the wall of the atrium or the ostium (opening) of a
pulmonary vein 3000, the coil will begin to deflect. As the system
is moved deeper into the pulmonary vein, the wires will not deflect
as much if at all, and an operator of the system 10 will be able to
determine when the positioning mechanism 14''' of the system 10 is
correctly located within the pulmonary vein.
[0056] The coil of the positioning mechanism 14''' functions to
anchor the elongate member 12 with respect to the anatomical
structure, preferably a pulmonary vein 3000, by coupling to the
anatomical structure. Preferably, the outward force of the coil
against the interior wall of the pulmonary vein will hold the
positioning mechanism 14''' within the pulmonary vein due to
friction. The positioning mechanism 14''' may alternatively
function to anchor the elongate member 12 with respect to the
anatomical structure in any other suitable fashion.
[0057] In a fifth variation, as shown in FIG. 12, the positioning
mechanism includes at least one distal wire 38 and at least one
proximal wire 40, each wrapped around at least a portion of the
elongate member 12. The wires are preferably made from a conductive
material and/or a material with shape memory such as
nickel/titanium alloys or a shape memory polymer. The material is
preferably flexible so as not to cause injury to the tissue of the
heart where the wires might contact and move against it. At least a
portion of each of the wires is preferably made from a
fluoro-opaque material, such as platinum or gold, such that it may
be seen while positioned inside the internal structures of a
patient through the use of a fluoroscope. The fluoro-opaque portion
is preferably located in any suitable position such that it may be
seen while positioned inside the internal structures of a patient
through the use of a fluoroscope. The fluoro-opaque portion is
preferably flush with the wire, but may alternatively have a round
or any other suitable shape such that it will not damage the
tissue. Additionally, each of the wires preferably includes at
least one electrically active portion 42 and/or at least one
insulated portion (e.g. an insulating coating on a portion of each
wire). The wires each preferably include an even number of
electrically active portions 42 such that a bipolar electrical
system may be used, wherein each pair of electrodes or electrically
active portions has an opposite polarity. For clarity, only a
single electrically active portion 42 per wire has been shown in
FIG. 12. The wires may alternatively include a single electrode or
electrically active portion and use a monopolar electrical system,
or may include any other suitable number of electrodes or
electrically active portions. The electrically active portion 42 is
preferably located in any suitable position such that it comes in
contact with tissue. The distal wire 38 is preferably located
distally from the energy delivery structure 18, and the proximal
wire is preferably located proximally from the energy delivery
structure. The wires are preferably each coupled to the elongate
member 12 at one end of the wire and then the other end is
preferably wrapped around at least a portion of the elongate member
12 such that the other ends unwind towards the tissue once the
distal tip assembly 16 is placed within the pulmonary vein 3000 or
any other suitable structure. The wires preferably unwind such that
the electrically active portion 42 of each wire is in contact with
the tissue. The wires are preferably wrapped around the elongate
member such that as the elongate member 12 and/or distal tip
assembly are rotated (as shown by arrow R in FIG. 12), the
electrically active portions 42 of the wires sweep along the
tissue. The wires are further preferably wrapped around at least a
portion of the elongate member such that they are biased away from
one another. For example, the distal wire 38 may be wrapped such
that the end is biased towards the distal end of the catheter. This
will encourage the wires to not block the energy delivery structure
and to not contact one another. There is preferably at least one
distal wire and at least one proximal wire such that, as the energy
delivery structure 18 delivers energy to the tissue to form an
ablation path and/or conduction block, there will be at least one
wire distal to the conduction block and at least one wire proximal
to the ablation path and/or conduction block.
[0058] Although omitted for conciseness, the preferred embodiments
include every combination and permutation of the various elongate
members 12 and positioning mechanism 14.
[0059] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting in scope of the invention which is
defined by the appended claims.
* * * * *