U.S. patent application number 12/206591 was filed with the patent office on 2009-03-12 for bipolar devices for modification of airways by transfer of energy.
This patent application is currently assigned to Asthmatx, Inc.. Invention is credited to Michael Biggs, Keith M. Burger, Christopher James Danek, Dave Haugaard, Thomas Keast, Michael D. Laufer, Bryan Loomas, John Arthur Ross.
Application Number | 20090069797 12/206591 |
Document ID | / |
Family ID | 39743202 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090069797 |
Kind Code |
A1 |
Danek; Christopher James ;
et al. |
March 12, 2009 |
BIPOLAR DEVICES FOR MODIFICATION OF AIRWAYS BY TRANSFER OF
ENERGY
Abstract
This relates to a device for treating lung disease, and more
particularly, relates to a device for exchanging energy with airway
tissue such as that found in the airways of human lungs. The
exchange of energy with this airway tissue in the airways reduces
the ability of the airways to constrict and/or reduces the
resistance within the airway to the flow of air through the
airway.
Inventors: |
Danek; Christopher James;
(Santa Clara, CA) ; Loomas; Bryan; (Saratoga,
CA) ; Biggs; Michael; (San Francisco, CA) ;
Burger; Keith M.; (San Francisco, CA) ; Haugaard;
Dave; (San Jose, CA) ; Keast; Thomas;
(Mountain View, CA) ; Ross; John Arthur; (Tracy,
CA) ; Laufer; Michael D.; (Menlo Park, CA) |
Correspondence
Address: |
PERKINS COIE LLP;PATENT SEA
P.O. BOX 1247
SEATTLE
WA
98111
US
|
Assignee: |
Asthmatx, Inc.
Sunnyvale
CA
|
Family ID: |
39743202 |
Appl. No.: |
12/206591 |
Filed: |
September 8, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09436455 |
Nov 8, 1999 |
7425212 |
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12206591 |
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09296040 |
Apr 21, 1999 |
6411852 |
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09436455 |
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09095323 |
Jun 10, 1998 |
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09296040 |
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09349715 |
Jul 8, 1999 |
6488673 |
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09095323 |
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10232909 |
Aug 30, 2002 |
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09349715 |
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09349715 |
Jul 8, 1999 |
6488673 |
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10232909 |
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09260401 |
Mar 1, 1999 |
6283988 |
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09349715 |
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09003750 |
Jan 7, 1998 |
5972026 |
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09260401 |
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08833550 |
Apr 7, 1997 |
6273907 |
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09003750 |
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08994064 |
Dec 19, 1997 |
6083255 |
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09349715 |
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08833550 |
Apr 7, 1997 |
6273907 |
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08994064 |
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09224937 |
Dec 31, 1998 |
6200333 |
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08833550 |
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08833550 |
Apr 7, 1997 |
6273907 |
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09224937 |
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Current U.S.
Class: |
606/33 |
Current CPC
Class: |
A61B 2018/00214
20130101; A61B 2018/1407 20130101; A61B 2018/046 20130101; A61N
1/06 20130101; A61B 2018/00541 20130101; A61B 2018/044 20130101;
A61N 1/403 20130101; A61B 18/14 20130101; A61B 2017/22062 20130101;
A61B 18/08 20130101; A61B 2018/1807 20130101; A61B 2017/00115
20130101; A61B 18/00 20130101; A61B 18/1492 20130101 |
Class at
Publication: |
606/33 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1-78. (canceled)
79. An apparatus for delivering energy to airway tissue,
comprising: a flexible elongated body having a proximal portion and
a distal portion; a radially expandable electrode array including a
rounded tip and at least four elongated flexible electrodes
projecting from the distal portion of the body and longitudinally
relative to the body, wherein each electrode has a proximal end
attached to the distal portion of the elongated body, a distal end
attached to the rounded tip, and an active region between the
proximal and distal ends; a first electric cable configured to be
attached to one pole of an RF energy source and a first plurality
of the electrodes, and a second cable configured to be attached to
an opposite pole of the RF energy source and a second plurality of
the electrodes, wherein the first and second cables provide RF
energy to the first and second plurality of electrodes in a bipolar
manner; and a deployment member extending along the elongated body
and attached to the rounded tip, wherein proximal movement of the
deployment member flexes the electrodes such that the active
regions move away from a longitudinal axis of the elongated body to
contact the airway.
80. The apparatus of claim 79 wherein the electrodes are equally
spaced apart from each other.
81. The apparatus of claim 79 wherein the active regions are
approximately 10 mm long.
82. The apparatus of claim 79 wherein opposing active regions of
the electrodes are diametrically spaced apart from each other by a
distance of 10-12 mm in a fully flexed expanded state.
83. The apparatus of claim 79, further comprising a first
thermocouple operatively coupled to one of the first plurality of
electrodes and a second thermocouple operatively coupled to one of
the second plurality of electrodes.
84. The apparatus of claim 79 wherein the electrodes are made from
a flat wire positioned to flex so that the active regions move
radially outward to a deployed configuration.
85. The apparatus of claim 79, further comprising a power source
that provides RF energy in bipolar fields within airway tissue such
that the electrodes reach a temperature of 65.degree. C. for an
activation time of at least 3 seconds.
86. The apparatus of claim 79, further comprising a power source
that provides RF energy in bipolar fields within airway tissue such
that the electrodes reach a temperature of 70.degree. C. for an
activation time of 2 seconds.
87. The apparatus of claim 79 wherein individual active regions
form individual arches when moved radially outward.
88. An apparatus for delivering energy to airway tissue,
comprising: a flexible elongated body having a proximal portion and
a distal portion; a radially expandable electrode array including a
rounded tip and at least four elongated flexible electrodes
projecting longitudinally relative to the body, wherein each
electrode has a proximal end attached to the distal portion of the
elongated body, a distal end attached to the rounded tip, and an
active region between the proximal and distal ends, and wherein the
electrodes extend generally parallel to a longitudinal axis of the
elongated body in a collapsed state and are configured to flex such
that the active regions move radially outward relative to the
longitudinal axis of the elongated body to contact the airway in an
expanded state; and a first electric cable configured to be
attached to one pole of an RF energy source and a first plurality
of the electrodes, and a second cable configured to be attached to
an opposite pole of the RF energy source and a second plurality of
the electrodes, wherein the first and second cables provide RF
energy to the first and second plurality of electrodes in a bipolar
manner such that airway smooth muscle tissue is debulked and the
ability of the airway smooth muscle to contract is reduced.
89. The apparatus of claim 88 wherein the electrodes are equally
spaced apart from each other.
90. The apparatus of claim 88 wherein the active regions are
approximately 10 mm long.
91. The apparatus of claim 88 wherein opposing active regions of
the electrodes are diametrically spaced apart from each other by a
distance of 10-12 mm in a fully flexed expanded state.
92. The apparatus of claim 88, further comprising a first
thermocouple operatively coupled to one of the first plurality of
electrodes and a second thermocouple operatively coupled to one of
the second plurality of electrodes.
93. The apparatus of claim 88 wherein the electrodes are made from
a flat wire positioned to flex so that the active regions move
radially outward to a deployed configuration.
94. The apparatus of claim 88, further comprising a power source
that provides RF energy in bipolar fields within airway tissue such
that the electrodes reach a temperature of 65.degree. C. for an
activation time of at least 3 seconds.
95. The apparatus of claim 88, further comprising a power source
that provides RF energy in bipolar fields within airway tissue such
that the electrodes reach a temperature of 70.degree. C. for an
activation time of 2 seconds.
96. The apparatus of claim 88 wherein individual active regions
form individual arches when moved radially outward.
97. A method for treating asthma, comprising: inserting a radially
expandable electrode array into an airway in a lung of a patient,
the radially expandable electrode array including at least four
elongated flexible electrodes projecting from the distal portion of
the body and longitudinally relative to the body, wherein each
electrode has a proximal end attached to the distal portion of the
elongated body, a distal end attached to a tip, and an active
region between the proximal and distal ends; flexing the electrodes
such that the active regions move radially outward relative to a
longitudinal axis of the elongated body and contact a wall of the
airway, wherein individual active regions extend longitudinally
along the wall of the airway; and delivering RF energy to the wall
of the airway via the electrodes in a bipolar manner such that
airway smooth muscle tissue is debulked and the ability of the
airway smooth muscle to contract is reduced.
98. The method of claim 97 wherein delivering the RF energy
comprises heating the electrodes to at least 65.degree. C. for at
least 3 seconds and then terminating the RF energy.
99. The method of claim 97 wherein delivering the RF energy
comprises heating the electrodes to approximately 70.degree. C. for
approximately 2 seconds and then terminating the RF energy.
100. The method of claim 97 wherein flexing the electrodes
comprises moving the tip proximally, and wherein the method further
comprises releasing the tip after terminating the RF energy such
that the electrodes exert a longitudinal force that drives the tip
distally and moves the active regions radially inward relative to
the longitudinal axis of the elongated body.
101. The method of claim 97 wherein: flexing the electrode
comprises drawing a pull wire attached to the tip proximally such
that the tip moves proximally; delivering the RF energy comprises
heating the electrodes to at least 65.degree. C. for at least 3
seconds at a first treatment site in the airway and then
terminating delivery of the RF energy; releasing the pull wire
after terminating delivery of the RF energy at the first treatment
site, whereby the electrodes exert a longitudinal force that drives
the tip distally and moves the active regions inward relative to
the longitudinal axis of the elongated body; moving the expandable
electrode array proximally within the airway to a second treatment
site; pulling the pull wire proximally, which moves the tip
proximally and causes the electrodes to flex such that the active
regions move radially outward relative to the longitudinal axis of
the elongated body and contact the wall of the airway at the second
treatment site; delivering the RF energy in a bipolar manner to the
wall of the airway at the second treatment site such that the
electrodes are heated to at least 65.degree. C. for at least 3
seconds.
Description
[0001] This is a Continuation-in-part application of U.S.
application Ser. No. 09/296,040 filed Apr. 21, 1999, and of
Continuation-in-part U.S. application Ser. No. 09/095,323 filed
Jun. 10, 1998 both of which applications are incorporated herein by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a device for treating lung disease,
and more particularly, the invention relates to a device for
transferring energy into airway tissue such as that found in the
airways of human lungs. This includes heating and applying RF
energy to the airway. In the airways of the lung, the transfer of
energy into the airway tissue stiffens that tissue or reduces the
ability of the airways to constrict. In general the treatment
reduces the resistance to the flow of air through the airway.
[0004] 2. Brief Description of the Related Art
[0005] Asthma is a disease in which (i) bronchoconstriction, (ii)
excessive mucus production, and (iii) inflammation and swelling of
airways occur, causing widespread but variable airflow obstruction
thereby making it difficult for the asthma sufferer to breathe.
Asthma is a chronic disorder, primarily characterized by persistent
airway inflammation. However, asthma is further characterized by
acute episodes of additional airway narrowing via contraction of
hyper-responsive airway smooth muscle.
[0006] Asthma stimuli may be allergenic or non-allergenic. Examples
of allergenic stimuli include pollen, pet dander, dust mites,
bacterial or viral infection, mold, dust, or airborne pollutants;
non-allergenic stimuli include exercise or exposure to cold, dry
air.
[0007] In asthma, chronic inflammatory processes in the airway play
a central role. Many cells and cellular elements are involved in
the inflammatory process, particularly mast cells, eosinophils T
lymphocytes, neutrophils, epithelial cells, and even airway smooth
muscle itself. The reactions of these cells result in an associated
increase in the existing sensitivity and hyperresponsiveness of the
airway smooth muscle cells that line the airways to the particular
stimuli involved.
[0008] The chronic nature of asthma can also lead to remodeling of
the airway wall (i.e., structural changes such as thickening or
edema) which can further affect the function of the airway wall and
influence airway hyperresponsiveness. Other physiologic changes
associated with asthma include excess mucus production, and if the
asthma is severe, mucus plugging, as well as ongoing epithelial
denudation and repair. Epithelial denudation exposes the underlying
tissue to substances that would not normally come in contact with
them, further reinforcing the cycle of cellular damage and
inflammatory response.
[0009] In susceptible individuals, asthma symptoms include
recurrent episodes of shortness of breath (dyspnea), wheezing,
chest tightness, and cough. Currently, asthma is managed by a
combination of stimulus avoidance and pharmacology.
[0010] Stimulus avoidance is accomplished via systematic
identification and minimization of contact with each type of
stimuli. It may, however, be impractical and not always helpful to
avoid all potential stimuli.
[0011] Asthma is managed pharmacologically by: (1) long term
control through use of anti-inflammatories and long-acting
bronchodilators and (2) short term management of acute
exacerbations through use of short-acting bronchodilators. Both
approaches require repeated and regular use of the prescribed
drugs. High doses of corticosteroid anti-inflammatory drugs can
have serious side effects that require careful management. In
addition, some patients are resistant to steroid treatment. Patient
compliance with pharmacologic management and stimulus avoidance is
often a barrier to successful asthma management.
[0012] Asthma is a serious disease with growing numbers of
sufferers. Current management techniques are neither completely
successful nor free from side effects.
[0013] Accordingly, it would be desirable to provide an asthma
treatment which improves airflow without the need for patient
compliance.
[0014] In addition to the airways of the lungs, other body conduits
such as the esophagus, ureter, urethra, and coronary arteries, are
also subject to periodic spasms that interfere with their normal
function.
SUMMARY OF THE INVENTION
[0015] The present invention relates to a device for treating
airway tissue within the lungs by transfer of energy into the walls
of the airway to reduce plugging of the airway, to prevent the
airway from being able to constrict, to increase the inner airway
diameter, or to reduce resistance to flow through the airway. The
invention is particularly directed to the treatment of the airways
in the lungs to reduce the effects of asthma and other lung
disease. One variation of the invention includes the transfer of
energy to the airway wall via the application of heat.
[0016] The present invention provides devices to decrease airway
responsiveness and airway resistance to flow which may augment or
replace current management techniques. In accordance with one
variation of the present invention, an energy transfer apparatus
for treating conditions of the lungs by decreasing airway
responsiveness includes transferring energy into an airway wall to
alter the airway wall in such a manner that the responsiveness of
the airway is reduced.
[0017] In particular, the inventive device is an energy transfer
apparatus which facilitates energy transfer with a mass of tissue
within the airways of a lung. The inventive device is sized to
enter the bronchus or bronchiole of a human lung to conduct energy
transfer with the airway tissue therein. The inventive device may
also be sized to fit within a bronchoscope. The bronchoscope may
have a channel with a diameter of preferably 2 mm or less.
[0018] A variation of the inventive device includes a flexible
elongated body having a proximal portion and a distal portion with
a lumen extending between the proximal and distal portions. The
flexible elongated body may be of sufficient stiffness to pass
through a seal of a working channel of a bronchoscope and allow
operation of the device through the working channel seal. The
device may include an expandable portion that is adjacent to a
distal portion of the elongated body. The expandable portion has a
first state, e.g., a size, and a second state where the second
state is radially expanded in size from the elongated body. The
device may include a temperature detecting element which is placed
near to the expandable portion. The device also includes at least
one energy transfer element at an exterior of the expandable
portion, where the energy transfer elements are configured to
contact the wall of the bronchus or bronchiole when the expanded
portion is in an expanded state. The device may also include a
deployment member that is configured to move the expandable portion
between the first and second radially expanded states. The
deployment member may extend between the expandable portion and the
proximal portion of the elongated body. The inventive device may
further include a distal tip located at a distal end of the
apparatus. One variation of the inventive device includes an
expandable portion that has a diameter of less than 15 mm when in a
second expanded state.
[0019] Another variation of the invention includes an expandable
portion which includes pre-shaped tines. Such tines are configured
to be in a first state within an elongated body and, when advanced
out of the elongated body, to expand into a second expanded state.
The tines may be connected to each other with an expanding element
to prevent the tines from entering multiple airways at a
bifurcation.
[0020] Another variation of the invention includes an expandable
portion comprised of a balloon. This variation of the invention may
include the use of a fluid which may expand the balloon into the
second state. Yet another variation of this invention includes the
use of a heat generating element in the balloon which conducts heat
to the fluid to heat an exterior of the balloon. In this variation,
the exterior of the balloon serves as the energy transfer
element.
[0021] A further variation of the inventive device includes an
expandable portion which comprises a plurality of legs which forms
a basket. The legs of this variation may extend from a proximal
joint that is found at an intersection of a distal portion of the
elongated body to a distal joint that is adjacent to a distal tip.
Each leg may have a center that is substantially parallel to the
elongated body so that there is sufficient contact between the
airway walls and the parallel portion of the leg. The center that
is substantially parallel is usually referred to as the active
region of the leg. The
[0022] The legs of this variation may be spaced around a
circumference of the elongated body to form a basket. The legs of
this variation may have a circular cross section or a rectangular
cross section, or other non-axisymmetric cross sections. The cross
sections may be chosen to allow ready deployment from a first state
to a second expanded state, while resisting out-of-plane bending
which may distort the spacing of the legs or the contact of
electrodes with the airway surface. One variation of the invention
includes a basket in which the distance between the proximal and
distal joint is less than 35 mm when the basket is not expanded.
Another variation of this invention includes a basket that
comprises four or five legs. In this case, the legs may be placed
evenly around a circumference of the elongated body. In this case
the legs may be found at intervals of 90 or 72 degrees. Other
variations of the invention include devices having less than four
legs or more than five legs. Another variation of this inventive
device includes placing a temperature detecting element on one or
on more legs. In this variation, the temperature of one leg may be
monitored or the temperature of several legs may be independently
monitored to control the energy delivery. In a further variation,
multiple temperature sensing elements may be combined with
independent control of energy to each leg. Both of these variations
may also apply to a variation of the device having pre-shaped
tines. The legs may be soldered or made to adhere using adhesives
to the elongated body at the proximal and distal ends. Another
variation of the invention includes a multi-lumen elongated body
into which a portion of each leg is inserted. It is also
contemplated that an elongated member may be reinforced via a
reinforcing member. Such a reinforcing member may include a coiled
or braided wire, polymeric insert, or any other similar reinforcing
member.
[0023] The energy transfer element of the invention may include an
element that directly heats tissue by delivering current such as an
RF based electrode. The RF electrode may be either bipolar or
monopolar or a heated element that conductively heats tissue. In
variations of the invention using RF energy, the frequency of the
RF may be selected to be in the 400 kHz range or any other standard
medical range used in electro-surgical applications.
[0024] When the electrode directly heats the tissue, the heated
element may use AC or DC current to resistively heat the element.
RF energy may also be used to resistively heat the element. An
indirect method of heating includes a resistively heated element
that conducts heat to the expandable portion or directly to the
airway. The invention may also include a combination of the types
of electrodes mentioned above.
[0025] In the variation of the invention in which the expandable
portion comprises a basket, each of the energy transfer elements
may be a RF electrode that is attached to each leg. The electrode
may be fastened by a heat shrink fastener. In such a case, a
temperature detecting element may be placed on the leg and
underneath the fastener. A resistance heating element may be coiled
around a portion of the leg. In this case, a temperature detecting
element may be placed underneath the coil. Other examples of the
energy transfer element include a polymeric heating element, an
electrically conductive paint, or a printed flex circuit which are
on a portion of the leg. Another variation employs the basket leg
itself as either a RF electrode or a heated element. In such cases,
the temperature sensing element may be attached directly to a
basket leg by soldering, welding, adhesive bonding, or other
means.
[0026] Another variation of the invention includes a sheath
slidably coupled to and exterior to the expandable portion. The
expandable portion may be resilient and self-expand into the second
state when no longer confined by the sheath. For example, the
sheath may be withdrawn in a proximal direction or the expandable
portion may be advanced out of the sheath.
[0027] Yet another variation of the invention includes a deployment
member comprising a handle adjacent to a proximal end of the
elongated body. The elongated body may be slidably attached to the
handle. The deployment member may also comprise a wire that extends
from the handle through the lumen of the elongated body and is
fixedly attached to the distal tip. This wire may also provide a
current to the energy transfer members. The elongated body, the
wire, and the distal tip may be slidably moveable in a distal and
proximal direction. This variation of the deployment member may
also include a stop configured to prevent distal movement of the
wire beyond a deployment point. In this variation, beyond the
deployment point, movement of the elongated body against the
non-moving distal tip causes the expansion member to expand from a
first state into a second expanded state.
[0028] Another variation of the invention includes a deployment
member comprising a sheath that covers the elongated member and
expandable portion and a handle at a proximal end of the sheath.
The sheath may be slidably attached to the handle while the
elongated member is rigidly attached to the handle. A wire may
extend from said handle to a distal tip through a lumen of the
elongated member. The variation may include a first control member
attached to the sheath and slidably attached to the handle where
proximal movement of the first control member causes the sheath to
retract on the elongated member and uncover the expandable portion.
This variation may also include a second control member which is
attached to the wire where proximal movement of the second control
member causes the distal tip and the expandable portion to retract
against the non-moving elongated member and causes the expandable
portion to radially expand into a second state.
[0029] Another variation of the invention includes a deployment
member having force compensation or deflection limiting stops to
prevent over-expansion of the expandable member when deployed
within the body.
[0030] A variation of the invention includes placing a sheath
exterior to the elongated body and expandable portion such that the
expandable portion is placed within the sheath in a first
unexpanded state. When the expandable portion is no longer
restrained by the sheath, the expandable portion expands into its
second state. The invention may also include a control member
moveably secured to the handle where the member is configured to
advance the elongated body and the wire in the distal and proximal
directions. Another variation of the invention includes a detent
means for maintaining the elongated body distally of the deployment
point. The control member may also be configured to frictionally
maintain the elongated body distally of the deployment point. In
these cases, the expandable portion will be in the second expanded
state. Other variations of the inventive device may include use of
levers, control wheels, or screw mechanisms in place of a control
member.
[0031] Another variation of the inventive device includes a distal
tip that may be configured to prevent gouging of the airway tissue.
The distal tip may have a redundant joint to prevent separation of
the tip from the apparatus. The distal tip may also be sized to fit
within a bronchoscope.
[0032] Another variation of the invention includes a central wire
extending from the distal tip to the proximal portion of the
device. The wire may be configured to provide a current to the
energy transfer elements. A temperature detecting element may also
be attached to the wire.
[0033] The inventive device may also be radiopaque or may have
radiopaque elements.
[0034] Another variation of the invention includes providing a
steering member in the device to deflect the distal tip of the
apparatus in a desired direction.
[0035] Another variation of the invention includes placing a vision
system on the apparatus. The vision system may include a
fiber-optic cable or a CCD chip.
[0036] Another variation of the invention includes providing a
power supply configured to deliver energy through the energy
transfer elements to the airway walls. The power supply may be
configured to include a high temperature shut off or one which
shuts down if a minimum temperature is not detected within a
predetermined time or if a minimum temperature slope is not
detected during a predetermined time.
[0037] The invention further includes a kit comprising an energy
transfer apparatus for facilitating energy transfer into a mass of
airway tissue and a generator configured to delivery energy to the
energy transfer apparatus. The kit may further include a
bronchoscope.
[0038] The invention further includes an energy transfer apparatus
for facilitating energy transfer into a mass of airway tissue
within a lung, the energy transfer apparatus having been rendered
sterile for the purposes of prevention of infection of the
lung.
[0039] The invention further includes a modified lung configured to
have an artificially altered airway within the lung, the airway
being artificially altered by transfer of energy to the airway such
that the airway has a reduced ability to constrict, an increased
airway diameter, a increase in resistance to plugging, and a
decrease in resistance to airflow.
[0040] The present invention may be used for a treatment of asthma
or other constriction or spasm of a bodily conduit by application
of energy. The treatment reduces the ability or propensity of the
airway to contract, reduces plugging of the airway, increases the
inner airway diameter, and/or reduces resistance to flow through
the airway.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The invention will now be described in greater detail with
reference to the various embodiments illustrated in the
accompanying drawings:
[0042] FIG. 1 is a cross sectional view of a medium sized bronchus
in a healthy patient.
[0043] FIG. 2 is a cross sectional view of a bronchiole in a
healthy patient.
[0044] FIG. 3 is a cross sectional view of the bronchus of FIG. 1
showing the remodeling and constriction occurring in an asthma
patient.
[0045] FIG. 4 is an illustration of the lungs being treated with a
device according to the present invention.
[0046] FIG. 5A is a partial side view of a variation of the
inventive device having a plurality of wire shaped electrodes.
[0047] FIG. 5B is a cross sectional side view of another variation
of a device having a plurality of wire shaped electrodes with a
deployment wire attached to a distal tip of the device.
[0048] FIG. 5C shows a partial view of a variation of an elongated
member of inventive device having a plurality of lumens for nesting
the legs of the basket.
[0049] FIGS. 5D-5I illustrate a variation of the invention and a
deployment member for deploying the device.
[0050] FIGS. 5J-5L illustrate examples of energy transfer elements
of the device.
[0051] FIG. 5M shows a partial view of a thermocouple attached to a
basket leg.
[0052] FIGS. 6A-6D illustrates distal joints of the invention.
[0053] FIG. 6E illustrates a proximal joint of the invention.
[0054] FIGS. 7A-7D illustrates a series and parallel wiring of legs
of the basket.
[0055] FIGS. 8A-8C illustrate examples of variable thicknesses of
legs of the basket.
[0056] FIGS. 9A-9D illustrate examples of a basket formed from a
single sheet or piece of material.
[0057] FIG. 10 is a side cross sectional view of a variation of the
inventive device having a balloon with electrodes positioned
exterior to the balloon.
[0058] FIG. 11 is a partial side view of a variation of the
inventive device having a balloon with heat generating elements
positioned within the balloon for indirect heating of the
tissue.
[0059] FIG. 12 is cross sectional view of the inventive device with
electrodes and pre-shaped tines as the expandable member.
[0060] FIG. 13 is a cross sectional view of a variation of the
inventive device with energy transfer elements positioned on
expandable balloons.
[0061] FIG. 14 is an illustration of a variation of the inventive
device with electrodes positioned in grooves.
[0062] FIG. 15 is an illustration of a variation of the inventive
device with electrodes and a biasing element.
[0063] FIG. 16 is an illustration of another variation of the
inventive device having electrodes and a biasing element.
[0064] FIG. 17 is a partial side view of a variation of the
inventive device having electrodes exposed by cut away sections of
an elongated member.
[0065] FIG. 18 is a partial side view of the inventive device with
electrodes positioned on a loop shaped member.
[0066] FIG. 19 is a cross sectional view of a variation of the
inventive device having a looped shaped electrode in an unexpanded
position.
[0067] FIG. 20 is a cross sectional view of the variation of FIG.
19 with the looped shape electrode in an expanded position.
DETAILED DESCRIPTION
Reducing the Ability of the Airway to Contract
[0068] The inventive airway energy treatment may be used to reduce
the ability of the airways to narrow or to reduce in diameter due
to airway smooth muscle contraction. This treatment to reduce the
ability of the smooth muscle to contract lessens the severity of an
asthma attack. The reduction in the ability of smooth muscle to
contract may be achieved by treating the smooth muscle itself or by
treating other tissues which in turn influence smooth muscle
contraction or the response of the airway to smooth muscle
contraction. Treatment may also reduce airway responsiveness or the
tendency of the airway to narrow or to constrict in response to a
stimulus.
[0069] The amount of smooth muscle surrounding the airway can be
reduced by exposing the smooth muscle to energy which either kills
the muscle cells or prevents these cells from replicating. The
reduction in smooth muscle reduces the ability of the smooth muscle
to contract and to narrow the airway during a spasm. The reduction
in smooth muscle and surrounding tissue has the added potential
benefit of increasing the caliber or diameter of the airways,
reducing the resistance to airflow through the airways. In addition
to use in debulking smooth muscle tissue to open up the airways,
the device of the present invention may also be used for
eliminating the smooth muscle altogether by thermally damaging or
destroying it. The elimination of the smooth muscle prevents the
hyper-reactive airways of an asthma patient from contracting or
spasming, reducing or eliminating this asthma symptom.
[0070] The ability of the airway to contract can also be altered by
treatment of the smooth muscle in particular patterns. The smooth
muscle is arranged around the airways in a generally helical
pattern with pitch angles ranging from about -30 to about +30
degrees. Thus, the treatment of the smooth muscle by energy which
is selectively delivered in an appropriate pattern interrupts or
cuts through the helical pattern at a proper pitch and prevents the
airway from constricting. This procedure of patterned application
of energy eliminates contraction of the airways without completely
eradicating smooth muscle and other airway tissue. A pattern for
treatment may be chosen from a variety of patterns including
longitudinal or axial stripes, circumferential bands, helical
stripes, and the like as well as spot patterns having rectangular,
elliptical, circular or other shapes. The size, number, and spacing
of the treatment bands, stripes, or spots are chosen to provide a
desired clinical effect of reduced airway responsiveness while
limiting insult to the airway to a clinically acceptable level.
[0071] The patterned treatment of the tissues surrounding the
airways with energy provides various advantages. The careful
selection of the portion of the airway to be treated allows desired
results to be achieved while reducing the total healing load.
Patterned treatment can also achieve desired results with decreased
morbidity, preservation of epithelium, and preservation of a
continuous or near continuous ciliated inner surface of the airway
for mucociliary clearance. The pattern of treatment may also be
chosen to achieve desired results while limiting total treatment
area and/or the number of airways treated, thereby improving speed
and ease of treatment.
[0072] Application of energy to the tissue surrounding the airways
also may be used to cause the DNA of the cells to become cross
linked. The treated cells with cross linked DNA are incapable of
replicating. Accordingly, over time, as the smooth muscle cells
die, the total thickness of smooth muscle decreases because of the
inability of the cells to replicate. The programmed cell death
causing a reduction in the volume of tissue is called apoptosis.
This treatment does not cause an immediate effect but causes
shrinking of the smooth muscle and opening of the airway over time
and substantially prevents re-growth. The application of energy to
the walls of the airway may also be used to cause a cross linking
of the DNA of the mucus gland cells thereby preventing them from
replicating and reducing excess mucus plugging or production over
time.
[0073] The ability of the airways to contract may also be reduced
by altering mechanical properties of the airway wall, such as by
increasing stiffness of the wall or by increasing parenchymal
tethering of the airway wall. Both of these methods increase the
strength of the airway wall and opposes contraction and narrowing
of the airway.
[0074] There are several ways to increase the stiffness of the
airway wall. One way to increase stiffness is to induce fibrosis or
wound healing response by causing trauma to the airway wall. The
trauma can be caused by delivery of therapeutic energy to the
tissue in the airway wall or by mechanical insult to the tissue.
The energy is preferably delivered in such a way that it minimizes
or limits the intra-luminal thickening that can occur.
[0075] Another way to increase the effective stiffness of the
airway wall is by altering the submucosal folding of the airway
upon narrowing. The submucosal layer is directly beneath the
epithelium and its basement membrane and inside the airway smooth
muscle. As an airway narrows, its perimeter remains relatively
constant, with the mucosal layer folding upon itself. As the airway
narrows further, the mucosal folds mechanically interfere with each
other, effectively stiffening the airway. In asthmatic patients,
the number of folds is fewer and the size of the folds is larger,
and thus, the airway is free to narrow with less mechanical
interference of mucosal folds than in a healthy patient. Thus,
asthmatic patients have a decrease in airway stiffness and the
airways have less resistance to narrowing.
[0076] The mucosal folding in asthmatic patients can be improved by
treatment of the airway in a manner which encourages folding.
Preferably, a treatment will increase the number of folds and/or
decrease the size of the folds in the mucosal layer. For example,
treatment of the airway wall in a pattern such as longitudinal
stripes can encourage greater number of smaller mucosal folds and
increase airway stiffness.
[0077] The mucosal folding can also be increased by encouraging a
greater number of smaller folds by reducing the thickness of the
submucosal layer. The decreased thickness of the submucosal layer
may be achieved by application of energy which either reduces the
number of cells in the submucosal layer or which prevents
replication of the cells in the submucosal layer. A thinner
submucosal layer will have an increased tendency to fold and
increased mechanical stiffening caused by the folds.
[0078] Another way to reduce the ability of the airways to contract
is to improve parenchymal tethering. The parenchyma surrounds
airways and includes the alveolus and tissue connected to and
surrounding the outer portion of the airway wall. The parenchyma
includes the alveolus and tissue connected to and surrounding the
cartilage that supports the larger airways. In a healthy patient,
the parenchyma provides a tissue network which connects to and
helps to support the airway. Edema or accumulation of fluid in lung
tissue in asthmatic patients is believed to decouple the airway
from the parenchyma reducing the restraining force of the
parenchyma which opposes airway constriction. Application of
therapeutic energy can be used to treat the parenchyma to reduce
edema and/or improve parenchymal tethering.
[0079] In addition, the applied energy may be used to improve
connection between the airway smooth muscle and submucosal layer to
the surrounding cartilage, and to encourage wound healing, collagen
deposition, and/or fibrosis in the tissue surrounding the airway to
help support the airway and prevent airway contraction.
Increasing the Airway Diameter
[0080] Airway diameter in asthmatic patients is reduced due to
hypertrophy of the smooth muscle, chronic inflammation of the
airway tissues, and general thickening of all parts of the airway
wall. The overall airway diameter can be increased by a variety of
techniques to improve the passage of air through the airways.
Application of energy to the airway smooth muscle of an asthmatic
patient can be used to debulk or reduce the volume of smooth
muscle. This reduced volume of smooth muscle increases the airway
diameter for improved air exchange.
[0081] The airway diameter can also be increased by reducing
inflammation and edema of the tissue surrounding the airway.
Inflammation and edema (accumulation of fluid) of the airway occur
in an asthmatic patient due to irritation. The inflammation and
edema can be reduced by application of energy to stimulate wound
healing and regenerate normal tissue. Healing of the epithelium or
sections of the epithelium experiencing ongoing denudation and
renewal allows regeneration of healthy epithelium with less
associated airway inflammation. The less inflamed airway has an
increased airway diameter both at a resting state and in
constriction. The wound healing can also deposit collagen which
improves parenchymal tethering.
[0082] Inflammatory mediators released by tissue in the airway wall
may serve as a stimulus for airway smooth muscle contraction.
Smooth muscle contraction, inflammation, and edema can be reduced
by a therapy which reduces the production and release of
inflammatory mediators. Examples of inflammatory mediators are
cytokines, chemokines, and histamine. The tissues which produce and
release inflammatory mediators include airway smooth muscle,
epithelium, and mast cells. Treatment of these structures with
energy can reduce the ability of the airway structures to produce
or release inflammatory mediators. The reduction in released
inflammatory mediators will reduce chronic inflammation, thereby
increasing the airway inner diameter, and may also reduce
hyper-responsiveness of the airway smooth muscle.
[0083] A further process for increasing the airway diameter is by
denervation. A resting tone of smooth muscle is nerve regulated by
release of catecholamines. Thus, by damaging or eliminating nerve
tissue in the airways the resting tone of the smooth muscle will be
reduced, and the airway diameter will be increased.
Reducing Plugging of the Airway
[0084] Excess mucus production and mucus plugging are common
problems during both acute asthma exacerbation and in chronic
asthma management. Excess mucus in the airways increases the
resistance to airflow through the airways by physically blocking
all or part of the airway. Excess mucus may also contribute to
increased numbers of leukocytes found in airways of asthmatic
patients by trapping leukocytes. Thus, excess mucus can increase
chronic inflammation of the airways.
[0085] One type of asthma therapy involves treatment of the airways
with energy to target and reduce the amount mucus producing cells
and glands and to reduce the effectiveness of the remaining mucus
producing cells and glands. The treatment can eliminate all or a
portion of the mucus producing cells and glands, can prevent the
cells from replicating or can inhibit their ability to secrete
mucus. This treatment will have both chronic benefits in increasing
airflow through the airways and will lessen the severity of acute
exacerbations.
[0086] Illustrated below are different treatment devices for
transferring energy into the airways. Described below are just some
of the examples of the type of treatment devices which may be used
to treat airway tissue according to the present invention. It
should be recognized that each of the treatment devices described
below can be modified to deliver or to remove energy in different
patterns depending on the treatment to be performed. The treatment
devices may be actuated continuously for a predetermined period
while stationary, may be pulsed, may be actuated multiple times as
they are moved along an airway, may be operated continuously while
moving the device in an airway to achieve a "painting" of the
airway, or may be actuated in a combination of any of these
techniques. The particular energy application pattern desired can
be achieved by configuring the treatment device itself or by moving
the treatment device to different desired treatment locations in
the airway.
[0087] The treatment of an airway with the treatment device may
involve placing a visualization system such as an endoscope or
bronchoscope into the airways. The treatment device is then
inserted through or next to the bronchoscope or endoscope while
visualizing the airways. Alternatively, the visualization system
may be built directly into the treatment device using fiber optic
imaging and lenses or a CCD and lens arranged at the distal portion
of the treatment device. The treatment device may also be
positioned using radiographic visualization such as fluoroscopy or
other external visualization means. The treatment device which has
been positioned with a distal end within an airway to be treated is
energized so that energy is applied to the tissue of the airway
walls in a desired pattern and intensity. The distal end of the
treatment device may be moved through the airway in a uniform
painting like motion to expose the entire length of an airway to be
treated to the energy. The treatment device may be passed axially
along the airway one or more times to achieve adequate treatment.
The "painting-like" motion used to exposed the entire length of an
airway to the energy may be performed by moving the entire
treatment device from the proximal end either manually or by motor.
Alternatively, segments, stripes, rings or other treatment patterns
may be used.
[0088] According to one variation of the invention, the energy is
transferred to or from an airway wall in the opening region of the
airway, preferably within a length of approximately two times the
airway diameter or less, and to wall regions of airways distal to
bifurcations and side branches, preferably within a distance of
approximately twice the airway diameter or less. The invention may
also be used to treat long segments of un-bifurcated airway.
Decreasing Resistance to Airflow
[0089] There are several ways to decrease the resistance to airflow
though the airways which occurs in asthma patients both at rest and
during an asthma attack. One such treatment alters the structure of
the airway, such as by reducing the amount of airway tissue. For
example, the addition of energy to the airway tissue may cause the
DNA of the muscle cells to become cross linked. The smooth muscle
cells with cross linked DNA cannot replicate. Thus, over time, as
smooth muscle cells die, the total thickness of the muscle
decreases because of the inability of the cells to replicate.
Another treatment alters the function of the airway, such as by
reducing smooth muscle contraction, mucus gland secretions, or
disrupting the inflammatory response. These treatments can be
performed by applying energy of different types and in different
patterns to achieve the desired results. In such cases, stiffness
of the airway is increased as the energy induces a fibrosis or
wound healing response that causes trauma to the airway wall.
[0090] FIGS. 1 and 2 illustrate cross sections of two different
airways in a healthy patient. The airway of FIG. 1 is a medium
sized bronchus having an airway diameter D1 of about 3 mm. FIG. 2
shows a section through a bronchiole having an airway diameter D2
of about 1.5 mm. Each airway includes a folded inner surface or
epithelium 10 surrounded by stroma 12 and smooth muscle tissue 14.
The larger airways including the bronchus shown in FIG. 1 also have
mucous glands 16 and cartilage 18 surrounding the smooth muscle
tissue 14. Nerve fibers 20 and blood vessels 22 also surround the
airway.
[0091] FIG. 3 illustrates the bronchus of FIG. 1 in which the
smooth muscle 14 has hypertrophied and increased in thickness
causing the airway diameter to be reduced from the diameter D1 to a
diameter D3.
[0092] FIG. 4 is a schematic side view of the lungs being treated
with an energy transferring apparatus 30 according to the present
invention. The device 30 is an elongated member for facilitating
exchanging energy with a mass of airway tissue at a treatment site
34 within the lungs. The device 30 must be of a size to access the
bronchus or bronchioles of the human lung. The device may be sized
to fit within bronchoscopes, preferably, with bronchoscopes having
a working channel of 2 mm or less. Also, the device should be of
sufficient stiffness to fit and operate through the seal covering
the working channel a bronchoscope.
[0093] The energy may be delivered by the treatment device 30 in a
variety of treatment patterns to achieve a desired response.
Examples of patterns are discussed in further detail below. The
energy which is delivered by the treatment device 30 may be any of
a variety of types of energy including, but not limited to,
radiant, laser, radio frequency, microwave, heat energy, or
mechanical energy (such as in the form of cutting or mechanical
dilation).
[0094] Also, the device may, but is not necessarily, configured to
deliver energy in non-intersecting strip patterns which are
parallel with a central axis of an airway. For example, other
variations of the device may be configured to deliver energy in a
torsional pattern, or in a circumferential pattern around a wall of
the airway. Such configurations which may be determined to deliver
energy to the airway tissue that maximize the ability of the airway
to permit airflow are considered to be within the scope of this
invention.
[0095] The inventive devices include tissue contacting electrodes
configured to be placed within the airway. These devices can be
used for delivering radio frequency in either a monopolar or a
bipolar manner or for delivering other energy to the tissue, such
as conducted heat energy from resistively heated elements. As shown
in FIG. 4, for monopolar energy delivery, one or more electrodes of
the treatment device are connected to a single pole of the energy
source 32 and an optional external electrode 44 is connected to an
opposite pole of the energy source. For bipolar energy delivery,
multiple electrodes are connected to opposite poles of the energy
source 32 and the external electrode 44 is omitted. Naturally, the
external electrode 44 depicted in FIG. 4, is not required in the
case of bipolar energy delivery. The number and arrangement of the
electrodes may vary depending on the pattern of energy delivery
desired. The treatment devices of FIGS. 5A-10, and 12-20 are used
to deliver radiant or heat energy to the airway. The treatment
device of FIG. 11 may also be used to deliver indirect radio
frequency, microwave energy, or conductive heat energy to the
tissue. In cases of heat energy generated by resistive heating, the
current may be AC or DC current or in the case of AC, the current
may be delivered in the RF range. The use of RF provides an added
safety feature of minimizing the possibility of harm to the patient
caused by escaped current. The device may also use a combination of
any of the energy transferring element configurations described
herein.
[0096] The following illustrations are examples of the invention
described herein. It is contemplated that combinations of aspects
of specific embodiments or combinations of the specific embodiments
themselves are within the scope of this disclosure.
[0097] The treatment device 302 of FIG. 5A includes an elongated
member 102 for delivering an expandable member 104 to a treatment
site. The expandable member 104 may have a plurality of energy
transfer elements (not illustrated) which are placed on a plurality
of basket legs 106 to transfer energy at the treatment site. In
this variation, the expandable member comprises a basket 104 which
is defined by a number of basket legs 106. The basket legs 106 are
formed from a plurality of elements which are soldered or otherwise
connected together at two connection areas, a proximal joint 108
and a distal joint 110.
[0098] A desirable length of the basket 104, or the expandable
portion of any variation of the invention, depends upon numerous
factors. One consideration in determining a desired length of the
expandable member, e.g., the distance between the joints of the
basket, of the inventive device is related to the dimension of the
target area or treatment region. For instance, some other factors
include considerations of minimizing the amount of the expandable
portion which is distal to the treatment region for optimized
access, minimizing the amount of the expandable portion that is
proximal to the treatment region for visualization and access
concerns, and setting a desirable length of the expandable portion
that will contact a sufficient portion of the treatment region
during each application of the device. A compromise of such factors
along with other considerations provides a desirable length for the
expandable portion of the device. Preferably, the distance between
the distal and proximal joints of the basket is less than 35 mm
when the basket is in a first unexpanded state.
[0099] The legs 106 may be selected from a material that allows the
basket to expand without plastic deformation. For example, the legs
may comprise a stainless steel, or a shape memory/superelastic
alloy such as a nitinol material. The basket legs 106 may have a
rectangular cross section in those variations where the legs 106
are formed from ribbons, or the legs 106 may have a circular cross
section in those variations where the legs are formed from wires.
As discussed below, the legs 106 may also have other cross section
as desired. It is also contemplated that the legs 106 need not all
have similar cross sections. For instance, the cross section of
each of the legs 106 in a basket 104 may be individually chosen to
optimize such factors as the resilience of the basket 104, or to
optimize energy transfer characteristics. The legs may also have a
variable cross section along the length of the basket.
[0100] Illustrated are variations of the inventive device 302
having a basket 104 comprising of four legs 106. It is preferred
that the legs 106 are spaced at equal intervals around the
expandable member or basket 104. For example, in variations of the
invention having four legs 106, the legs 106 are preferably, but
not necessarily spaced at approximately 90 degree intervals around
the basket 104. In variations having five legs 106, the legs 106
may be spaced at approximately 72 degree intervals. Other
variations of the invention include devices having less than four
legs or more than five legs. It is thought that the most effective
number of legs is a compromise based on the size of the target
airway, contact surface between the leg 106 and airway wall, and
the maximum outer diameter of the elongated member 102.
[0101] The proximal 108 and/or distal 110 joints may also contain
adhesive to bind the legs 106. The basket legs 106 between the
proximal 108 and distal joint 110 are formed into the basket shape
104 so that arch shaped portions of the basket legs 106 will
contact the walls of an airway to facilitate energy transfer.
Although the figures illustrate the basket legs 106 as having a
semi-circular or arc shape the device is not limited to such
shapes. For example, the legs 106 may have a more oblong shape or
sharper bends to allow for a more parallel leg surface area that
contacts the target tissue. Each leg 106 may have a center that is
substantially parallel to the elongated body so that there is
sufficient contact between the airway walls and the parallel
portion of the leg 106. The center that is substantially parallel
is usually referred to as the active region of the leg 106.
[0102] The length of the basket 104 between the proximal and distal
110 joints may be less than 35 mm when the basket 104 is in a first
unexpanded state. The legs 106 may be coated with an insulating
material (not shown) except at the tissue contact points.
Alternatively, the legs 106 of the basket 104 may be exposed while
the proximal 108 and distal joint 110 are insulated. In this
variation, the basket 104 is formed of a resilient material which
allows the distal end of the inventive device 302 to be confined by
a sheath (not shown) for delivery of the device 302 to the
treatment site and allows the basket 104 to return to its original
basket shape upon deployment. In other words, a variation of the
invention is that the basket self-expands from a first state to a
second expanded state upon the removal of any constraining or
restrictive member such as a sheath (not shown). The inventive
device 302 is preferably configured such that the basket legs 106
have sufficient resilience to come into contact with the airway
walls for treatment.
[0103] FIG. 5A further illustrates a variation of the inventive
device 302 in which a distal end of the device 302 is provided with
a distal tip 112 that can have a radius to facilitate insertion of
the device 302 into the lungs and also to minimize the possibility
of causing trauma to surrounding tissue. The tip 112 is preferably
sized to prevent the gouging of airway by the sheath. The design of
the distal tip is selected to be atraumatic. The size of the tip
may be selected to be large enough to prevent the sheath from
gouging airways yet small enough to pass in and out of a
bronchoscope.
[0104] FIG. 5B illustrates a variation of the inventive device 302
having basket legs 108 connected to a distal end 114 of the
elongated member 102 and forming a basket 104. In this variation, a
proximal joint is found at the distal end 114 of the elongated
member 102. The basket 104 is expanded radially, to its second
state, during use to ensure contact between the energy transfer
elements (not shown) and the airway walls (not shown) by, for
example, pulling on a center pull wire 116 which is connected to a
distal tip 118 of the expandable portion 104. The center pull wire
116 may extend through a lumen of the elongated member 102 towards
a proximal portion (not shown) of the elongated member 102. It is
also contemplated that the center pull wire 116 may be configured
to deliver current to the energy transfer elements found on the
expandable member 104. The inventive device 302 may be delivered to
a treatment site through a delivery sheath 120 and may be drawn
along or moved axially along the airway to treat the airway in a
pattern of longitudinal or helical stripes.
[0105] As noted above, the basket 104 may be resilient or
self-expanding (e.g., see FIG. 5A) to expand to a second expanded
state or the basket 104 may require an expanding force (e.g., see
FIG. 5B). An example of this variation of the inventive device 304
is shown in FIG. 5B. In this variation, the basket 104 may be
resilient and the sheath 120 may comprise the deployment member. In
this variation, when the elongate body 102 and basket 104 are
withdrawn into the sheath 120, the basket 104 contracts within the
sheath 120 and assumes a first state. In one variation of the
invention, upon advancing the basket 104 and elongate body 102 out
of the sheath 120, the basket 104 may resiliently assume a second
expanded state. In another variation of the invention, the basket
104 may assume a second expanded state with the aid of a wire 116.
This wire may also be configured to deliver power to the energy
exchange elements 106.
[0106] FIG. 5C illustrates another variation of the inventive
device where an elongated member 102 of is configured to have a
plurality of lumens 140 so that each of the basket legs 106 are
isolated within the lumens 140 of the elongated member 102 until
the legs 106 exit the elongated member 102 and connect at a
proximal joint 108. The invention may have basket legs 106 selected
with a sufficient length such that the ends of each of the legs 106
extend substantially into the lumens 140. As a result of being
inserted deeply within the lumen, the ends of the legs 106 would
require significant travel before they exited the lumen 140. This
feature provides added safety as it minimizes the risk of the
basket legs 106 dislodging from the elongate member 102.
[0107] In another variation of the invention, the elongated member
102 may comprise concentric tubes (not shown) rather than
multi-lumen tubes where basket legs are inserted in the annulus
between the tubes. It is also contemplated that an elongated member
may be reinforced with the use of a reinforcing member. Such a
reinforcing member may include a coiled wire or polymeric
insert.
[0108] FIG. 5D-5I illustrate variations of the inventive device
that use an expanding force to expand the basket. FIG. 5D
illustrates a deployment member of the device. FIG. 5E illustrates
the device of FIG. 5D when the elongated member is moved in a
distal direction to a deployment point. FIG. 5F-5G illustrates the
elongated member 102, sheath 120, expandable member 104, distal tip
118, and wire 122 extending through the device. FIG. 5F illustrates
the basket 104 in a first unexpanded state when the elongated
member 102 and wire 122 are proximal of the deployment point 130.
FIG. 5G illustrates the expansion of the basket 104 to a second
expanded state as the elongated member 102 moves distally and the
wire 122 is restrained at the deployment point 130.
[0109] Turning now to FIG. 5D, the deployment member may comprise a
handle 124 which is adjacent to a proximal portion of an elongated
member 102. The handle may be designed to be operated by a single
hand, either right or left. The handle may also have a control
switch for operation of the device. Such a switch could control the
power supply attached to the device as well. Also, the handle may
be configured to determine the position of the device within a
human body as the device is advanced to a target site. For example,
marks on the handle or even a readout could provide information to
the user as to the relative deployment state of the expandable
member. Also, a sensor may be placed on the handle 124, this sensor
may be used to determine the position of the expandable member.
Such a sensor could also be used to measure the size of the airway,
such a measurement could be used as a control variable to determine
the amount of energy that the device power supply must deliver. The
handle 124 may control the expandable member using force
compensation (e.g., a spring, etc.) or deflection limiting stops to
control the expansion of the expandable member. Such force
compensation or deflection stops provide a limit to the expansion
member to avoid over-expansion of a particular airway.
[0110] Turning now to the handle 124 of FIG. 5D, an elongated
member 102 may be slidably mounted to the handle. The variation of
the invention depicted in these Figures may also, but does not
necessarily, include a sheath 120 exterior to the elongated body
102. A wire 122 extends from the handle through the elongated
member 102 and may be attached to a distal tip 118 of the device.
The wire 122, elongated member 102, and distal tip (not shown) are
slidably moveable in both a distal and proximal directions. The
handle may also include a stop 126 which prevents the wire 122 from
moving distally beyond a deployment point 130. The stop 126 may be
connected to a spring (not shown) to limit the expansion of the
expandable member upon reaching a pre-determined force. The handle
124 may include a control member 128 that is moveably attached to
the handle 124 for moving the elongated member 102 in a
distal/proximal direction. Although the handle 124 in the figures
is depicted to have a control member 128 as illustrated, other
variations of control members are also contemplated to be within
the scope of this invention. For example, though not illustrated, a
handle 124 may include other configurations, such as lever,
thumb-wheel, screw-mechanism, ratchet mechanism, etc., which are
attached to the handle 124 to provide control actuation for the
expandable member.
[0111] FIG. 5E illustrates a variation of the inventive device when
the elongated member 102 and wire 122 are moved in a distal
direction. In this illustrations, a stop 126 prevents the wire 122
from moving distally of a deployment position 130. This
illustration further illustrates a variation of the invention where
the stop 126 is attached to springs 127 which provide force
compensation for the expandable member on the device. Although not
shown, a control member 128 may have a stop which limits its travel
along a handle 124. Such a stop is an example of a deflection
limiting mechanism which controls the movement of the control
member 128, thus controlling the extent of the expansion of the
expandable member.
[0112] FIG. 5F illustrates the invention when the expandable member
or basket 104 is in a first unexpanded state. As noted above, the
wire 122 is attached to a distal tip 118 of the device and both are
prevented from distal movement when the wire 122 is in the
deployment position 130. Therefore, as depicted in FIG. 5G,
movement of the elongated member 102 in a distal direction against
a distal tip 118, that is restrained by a wire 122, causes a basket
104 to compress between the advancing elongated member 102 and the
stationary distal end 118. Thus, the basket 104 is forced outward
and radially expands into a second expanded state. As noted above,
the wire 122 may also be used to transfer energy to or from the
energy transfer elements found on the basket 104. Also, it is
contemplated that the wire 122 may be a wire, a ribbon, a tube, or
of any other equivalent structure. Also contemplated, but not
shown, is a detent means for maintaining the elongated member in a
distal position to expand the basket 104 against the distal tip 118
without the need for continual applied force by a user of the
device. Also contemplated is a ratchet member, or friction member
to maintain the basket 104 in the expanded state.
[0113] FIG. 5H illustrates another variation of a deployment
member. In this variation, a sheath 120 may be slidably attached to
a handle 124. In this variation, the elongate member 102 is rigidly
attached to the handle 124. The sheath 120 may be attached to a
first control member 129. A wire 122 extends through the elongate
member 102 and is attached to the distal tip of the device (not
shown). The wire 122 may be attached to a second control member
131. As indicated in FIG. 5I, proximal movement of the first
control member 129 causes the sheath 120 to proximally retract over
the elongate member 102 and uncover the expandable portion (not
shown). Proximal movement of the second control member 131 causes
the wire 122, distal joint, and expandable member to move against
the non-moving elongate member 102 which causes the expandable
member to expand into a second state.
[0114] Turning now to the energy transfer elements located on the
expandable portion, FIG. 5J-5L illustrate examples of energy
transfer elements that may be located on the expandable portion of
the device. In the variation of the invention where the expandable
portion comprises a basket having basket legs 106, the basket legs
106 may function as heat exchange elements. In other words, the
device may be configured so that the leg is an electrode or the
conductive heating element. In these variations, the leg 106 may be
partially covered with an insulation only leaving an active region
exposed for delivery of energy to the airways. Examples of such
insulation include a heat shrink sleeve, a dielectric polymeric
coating, or other material which may function as an insulator.
[0115] FIG. 5J illustrates an example of a basket leg 106 with an
energy transferring element 132 coiled around the leg 106. In this
example, the energy transferring element uses conductive heating
and comprises a resistance heating element 132 coiled around the
leg 106. FIG. 5K illustrates a variation of the invention having an
RF electrode attached to the basket leg 106. The RF electrode may
be attached to the basket leg 106 via the use of a fastener 134.
For example, the electrode may be attached via the use of a heat
shrink fastener 134, (e.g., polymeric material such as PET or
polyethylene tubing).
[0116] FIG. 5L illustrates another variation of the invention where
the energy transfer element is a printed circuit 138 that is
situated around the leg 106 and secured to the leg. Also
contemplated, but not shown for use as energy transfer elements are
a polymeric heating material, an electrically conductive paint, a
resistance element sputtered onto the leg in a pattern or formed on
a substrate by photofabrication. Also, the basket leg itself may be
chosen of appropriate size and resistivity to alloy dual use as a
basket and energy transfer element. Many nickel-chromium alloys
have both high specific resistance and significant spring-like
properties. In any variation of the invention the use of adhesives
or other coatings may also be used to secure the energy transfer
element to the basket leg 106. Also, the energy transfer elements
are not limited to what is illustrated in the drawings. It is also
contemplated that other types of energy transferelements may be
used such as radiant, laser, microwave, and heat energy.
[0117] FIG. 6A illustrates a variation of a distal tip 210 having a
redundant joint. The distal tip 208 has a polymeric cap 210
covering the distal ends of the basket legs 106 and wire 212. The
legs 106 are soldered 214 to the distal end of the wire 212. Also
used to maintain the joint is an adhesive 216 substantially filling
the polymeric cap 210. A multi-lumen piece 218 separates the legs
106 and wire 212. A side view of the multi-lumen piece 218 is shown
in FIG. 6B. A multi-lumen tubing may be used for the multi-lumen
piece 218. The ends 220 of the polymeric cap 210 may be heat formed
or otherwise tapered down around the legs 106.
[0118] FIG. 6C illustrates another variation of a distal tip 222
having a redundant joint. The distal tip 222 has a polymeric cap
210 covering the distal ends of the basket legs 106 and wire 212.
The legs 106 are soldered 214 to the distal end of the wire 212.
Also used to maintain the joint is an adhesive 216 substantially
filling the polymeric cap 210. A hypo-tube 224 covers the legs 106
and wire 212. A side view of the hypo-tube 224 is shown in FIG. 6D.
The distal end of the hypo-tube 224 may be flared to seat a ball
located on a distal end of the wire 212 and the legs 106. A
proximal end of the hypo-tube 224 may be flared to provide greater
interlock with ends 220 of the polymeric cap 210. As shown in FIG.
6C, the ends of the legs 106 taper outwards from the hypo-tube 224
and form an area with a diameter larger than the end of the cap 226
which may be tapered down around the legs 106 and wire 212. The
ends 220 of the polymeric cap 210 may be heat formed or otherwise
tapered down.
[0119] FIG. 6E shows another variation of the invention having a
hoop or ring 228 at a proximal joint of the device. The hoop 228
may be soldered or welded to the legs 106 and keeps the legs 106
attached even if a joint fails between the legs and the elongate
member 102. Also, the hoop 228 may electrically connect the legs,
preventing disconnection of single leg 106 having a temperature
sensing element attached.
[0120] The invention also includes a temperature detecting element
(not shown). Examples of temperature detecting elements include
thermocouples, infrared sensors, thermistors, resistance
temperature detectors (RTDs), or any other apparatus capable of
detecting temperatures or changes in temperature. The temperature
detecting element is preferably placed in proximity to the
expandable member. In the variation illustrated in FIG. 5C, a
temperature sensor may be mounted along the pull wire 116. For the
variations depicted in FIG. 5J-5L, a temperature sensor may be
mounted between the energy transfer elements 132, 136, 138 and the
leg 106. In one variation of the invention a temperature sensor is
placed on a single basket leg 106 to provide a signal to control
energy transfer. It is also contemplated that a temperature sensor
may be placed on more than one basket leg 106, and/or on a central
wire 116 to provide control for multiple areas of energy transfer.
The temperature sensor may be placed on the inside of the basket
leg 106 to protect the temperature sensor while still providing a
position advantageous to determining the device temperature at the
energy transfer element.
[0121] FIG. 5M illustrates a variation of the invention having
thermocouple leads 139 attached to a leg 106 of the device. The
leads may be soldered, welded, or otherwise attached to the leg
106. This variation of the invention shows both leads 139 of the
thermocouple 137 attached in electrical communication to a leg 106
at separate joints 141. In this case, the temperature sensor is at
the surface of the leg. This variation provides in case either
joint becomes detached, the circuit will be open and the
thermocouple 137 stops reading temperature. The device may also
include both of the thermocouple leads as having the same
joint.
[0122] FIG. 7A-7D illustrate variations of the device in which
impedance may be varied by wiring the basket legs 106 in series or
in parallel. FIG. 7A illustrates a series wiring diagram in which a
current path 142 flows from a first leg to a second leg 106, a
third leg 106, and a fourth leg 106 sequentially. FIG. 7B
illustrates the series wiring diagram and shows a single wire 143
connecting the legs 106 in series. The wire 143 may, for example,
extend to a distal end of the leg and wrap over itself to the
proximal end of the leg 106. A covering (not shown) may be placed
over the wire 143 wrapped leg 106 at the proximal end of the
device. FIG. 7C illustrates another variation of a series wiring
diagram. In this example, a wire 143 extends from the proximal end
of a leg 106 to its distal end and then extends to the distal end
of an adjacent leg 106 and extends back to the proximal end of the
adjacent leg 106.
[0123] FIG. 7D illustrates a parallel wiring diagram in which a
current path 142 flows to each leg 106. Series wiring has an added
advantage in that all current will pass through each energy
transfer element. By design, this configuration equalizes the heat
dissipated at each leg through construction of legs with equal
resistance. In addition, in the event of failure of any electrical
connection, no energy is delivered. This provides an additional
safety feature over parallel wiring. As mentioned elsewhere, the
electrical current may be AC or DC. AC may be delivered in the RF
range as a safety measure additional to electrical isolation. DC
may be used to allow a portable device powered by a battery pack or
provide an energy source within the device itself.
[0124] FIG. 8A-8C illustrates variation of the legs 106 of the
basket 104. As discussed above, the legs may, for example, comprise
a stainless steel, or a shape memory/superelastic alloy such as a
nitinol material. The basket legs 106 may have a rectangular cross
section in those variations where the legs 106 are formed from
ribbons, or the legs 106 may have a circular cross section in
variations where the legs 106 are formed from wires. Also, a leg
106 may be configured to have a non-axisymmetric cross-section. For
example, the leg may have an oval or flat cross section as well.
The legs 106 of a basket 104 need not all have similar cross
sections. For instance, the cross section of each of the legs 106
in a basket 104 may be individually chosen to optimize such factors
as the resilience of the basket 104, or to optimize energy transfer
characteristics. An example of a cross section of a basket leg 106
is seen in FIG. 8A which illustrates a top view of a basket leg 106
that has a contoured shape 144. In this illustration, the energy
exchange element is not shown in the figure for clarity. One of the
purposes of such a contoured shape 144 is illustrated in FIG. 8B.
When the basket (not shown) expands to its second state, leg 106 is
configured to bend at or substantially near to points 146. A
benefit of such a configuration is to allow a substantially
parallel active surface as defined by the contour shape 144. FIG.
8C illustrates another variation of a leg 106. In this variation,
the leg 106 has a region of increased diameter 148 in the case of
round wire, or increased width or thickness in the case of
rectangular or other non-axisymmetric wire. Such a region 106 could
also be a flat wire with bumps or protrusions creating areas of
increased width of the flat wire. This region 148 may, for example,
provide a stop that assists in locating insulation, heat shrink, or
other external covering around the leg 106. Also contemplated is a
leg 106 that consists of a composite construction. In this
variation, the leg 106 may comprise of differing materials in
predetermined regions to control the bending of the leg 106 as the
basket 104 expands, or the leg may be constructed of different
materials to selectively control regions of deliver of energy on
the leg.
[0125] FIG. 9A-9D illustrates another variation of the inventive
device in which the expandable member comprises basket from a
single piece or sheet of material. Such a configuration could
comprise an etched, machined, laser cut, or otherwise manufactured
piece of metal. FIG. 9A illustrates a partial view of a basket 104
formed from a single piece of material. The thickness of the
material is, for example 0.005 inches but may vary as desired. The
illustration of FIG. 9A shows the basket 104 prior to being wrapped
about the Z direction as indicated. As shown, the legs 106 may be
of varying length or they may be the same length 106 or a
combination thereof. The basket 104 may have a distal portion 164
or basket head 164 which may be configured to facilitate
construction of the device. For example, the basket head 164 may be
notched 166 to obtain a desired shape as the basket is wrapped
about the Z direction. FIG. 9B illustrates a variation of the
basket head 165 being notched such that sections 165 of the
material may be bent from the plane of the material to form tabs
165. Tabs 165 may be used to form mechanical joints with another
part, such as a distal tip cap. FIG. 9C illustrates another
variation of a basket 104 made from a single piece of material. In
this example, the legs 106 of the basket 104 are bent in a
direction orthogonal to the plane of the basket head 164. In this
example, the distance between the ends of the legs 106 may be, for
example, about 2.75 inches. FIG. 9D illustrates a variation of the
proximal ends of the legs 106 of the basket 104. In this example,
the proximal ends of the legs 106 may have features 168 which
promote the structural integrity of the proximal joint (not shown)
of the device. In this variation, the ends of the legs 106 have a
saw-tooth design which improve the integrity of the proximal joint
connecting the legs 106 to the elongated member. The variation of
FIG. 9D also illustrates a proximal end of the leg 106 as having a
radius, however, the end of the leg 106 may have other
configurations as required. Also, the legs 106 may have a width of,
for example, 0.012 inches and a separation of, for example, 0.016
inches. However, these dimensions may vary as needed.
[0126] FIG. 10 illustrates another variation of the inventive
device 306 in which the expandable member comprises a balloon
member 150. This variation of the device 306 includes electrodes
154 positioned on an exterior surface of the balloon member 150.
The electrodes 154 may be connected to an energy source (not shown)
by leads 156 extending through the balloon and through the lumen of
an elongated member 102. The balloon member 150 may be filled with
a fluid 152 such as saline or air to bring the electrodes 154 into
contact with the airway wall 10. As noted above, the electrodes may
also be resistance heating elements, RF electrodes, or another
suitable element for conducting energy transfer with the airway.
Also, a single electrode may continuously surround a circumference
of a balloon 150, or a plurality of electrodes may be spaced at
certain intervals to substantially surround the circumference of a
balloon 150.
[0127] FIG. 11 illustrates another variation of the inventive
device 308 in which the expandable member comprises a balloon
member 150 in which a fluid 152 within the balloon member 150 is
heated by a heat generating element 158. The heat generating
elements 158 are illustrated in the shape of coils surrounding the
shaft of the elongated member 102, however other types of heat
generating elements (not shown) shapes may also be used. The heat
generating elements 154 may be used as resistance heaters by
application of an electric current to the heat generating elements.
Alternatively, radio frequency or microwave energy may be applied
to the heat generating elements 158 to heat fluid 152 within the
balloon member 150. The fluid may be configured to optimize
conductive heat transfer from the electrodes 158 to the exterior of
the balloon member 150. The heat then passes from an exterior of
the balloon 150 to the airway wall 10. Radio frequency or microwave
energy may also be applied indirectly to the airway wall through
the fluid and the balloon. In addition, hot fluid may be
transmitted to the balloon member 150 from an external heating
device for conductive heating of the airway tissue.
[0128] Another variation of the inventive device 310 is illustrated
in FIG. 12 includes a plurality of energy transfer elements 162
positioned on pre-shaped tines 160. The pre-shaped tines 160 may be
outwardly biased such that they expand from a first shape inside
sheath 120 into a second expanded shape once advanced out of sheath
120. The tines 160 may also be configured so that they retract into
a first state once withdrawn into a sheath 120. The pre-shaped
tines 160 may be connected to an elongate member 102 which is
positioned within a sheath 120. The pre-shaped tines 160 and the
energy transfer elements 162 may be delivered through a delivery
sheath 120 to a treatment site within the airways. When the
pre-shaped tines 160 exit a distal end of the sheath 120, the
pre-shaped tines 160 may bend outward until the energy transfer
elements 162 come into contact with the airway walls for transfer
of energy with the airway walls.
[0129] FIG. 13 illustrates a variation of the inventive device 314
in which a elongated member 102 is provided with a plurality of
energy transfer elements 170 positioned on at least one inflatable
balloon 172. The energy transfer elements 170 may be RF electrodes
or resistance heating elements. The balloons 172 are inflated
through the elongated member 102 to cause the energy transfer
elements 170 to come into contact with the airway walls 10. The
energy transfer elements 170 are preferably connected to the energy
source (not shown) by conductive wires (not shown) which extend
from the energy transfer elements 170 through or along the balloons
172 and through the elongated member 102 to the energy source. In
the variation where the energy transfer elements 170 are RF
electrodes, the electrodes 170 may be used in a bipolar mode
without an external electrode. Alternatively, the inventive device
314 may be operated in a monopolar mode with an external electrode
(not shown, see FIG. 4). Another variation of the invention
includes using resistance heating elements as the energy transfer
elements 170. The energy transfer elements 170 may be a single
continuous circular element or there may be a plurality of elements
170 spaced around the balloons 172.
[0130] An alternative of the inventive device 316 of FIG. 14
includes an elongated member 102 having one or more grooves 174 in
an exterior surface. Positioned within the grooves 174 are
electrodes 176 for delivery of energy to the airway walls. Although
the grooves 174 have been illustrated in a longitudinal pattern,
the grooves may be easily configured in any desired pattern.
Preferably, the inventive device 316 of FIG. 14 includes a biasing
member (not shown) for biasing the elongated member 102 against an
airway wall such that the electrodes 176 contact airway tissue. The
biasing member (not shown) may be a spring element, an inflatable
balloon element, or other biasing member. Alternatively, the
biasing function may be performed by providing a preformed curve in
the elongated member 102 which causes the device to curve into
contact with the airway wall when extended from a delivery sheath
(not shown).
[0131] FIG. 15 illustrates a variation of the inventive device 318
having one or more electrodes 178 connected to a distal end of an
elongated tube 102. The electrodes 178 are supported between the
distal end of the elongated tube 102 and a distal tip 180. A
connecting shaft 182 supports the tip 180. Also connected between
the distal end of the elongated member 102 and the distal tip 180
is a spring element 184 for biasing the electrodes 178 against a
wall of the airway. The spring element 184 may have one end which
slides in a track or groove in the elongated member 102 such that
the spring 184 can flex to a variety of different positions
depending on an internal diameter of the airway to be treated.
[0132] FIG. 16 illustrates an alternative of the inventive device
320 in which the one or more electrodes 186 are positioned on a
body 188 secured to an end of an elongated member 102. In the FIG.
16 variation, the body 188 is illustrated as egg shaped, however,
other body shapes may also be used. The electrodes 186 extend
through holes 190 in the body 188 and along the body surface. A
biasing member such as a spring element 184 is preferably provided
on the body 188 for biasing the body with the electrodes 186
against the airway walls. Leads 192 are connected to the electrodes
186 and extend through the elongated member 102 to the energy
source not shown.
[0133] FIGS. 17 and 18 illustrate embodiments of the invention 322,
324 in which electrodes 194 in the form of wires are positioned in
one or more lumens 196 of an elongated member 102. Openings 198 are
formed in side walls of the elongated member 102 to expose the
electrodes 194 to the surrounding tissue. As shown in FIG. 17, the
inventive device 322 may have multiple lumens 196 with electrodes
194 provided in each of the lumens 196. The side wall of the
inventive device 322 is cut away to expose one or more of the
electrodes 194 through a side wall opening 198. In FIG. 17, the
opening 198 exposes two electrodes 194 positioned in adjacent
lumens. The inventive device 322 may be provided with a biasing
member as discussed above to bring the electrodes 195 of the device
into contact with the airway wall.
[0134] Another variation of the inventive device 324 as shown in
FIG. 18 includes an elongated member 102 which has an expandable
loop shaped member 202 to allow the electrodes 194 to be exposed on
opposite sides of the device 324 which contacts opposite sides of
the airway. The resilience of the loop shaped member 202 causes the
electrodes 194 to come into contact with the airway walls.
[0135] FIGS. 19 and 20 illustrate a further variation of the
inventive device 326 having an expandable member 204 in a first
non-expanded state and in a second expanded state. FIG. 19
illustrates the device as having one or more loop shaped electrodes
204 connected to an elongated member 102. In the unexpanded
position shown in FIG. 19, the loop of the electrode 204 lies along
the sides of a central core 206. A distal tip of the loop electrode
204 is secured to the core 206 and to a distal tip 208. The core
206 may be slidable in a lumen of the elongated member 102. Once
the inventive device 326 has been positioned with the distal end in
the airway to be treated, the electrode 204 is expanded by pulling
the core 206 proximally with respect to the elongated member 102,
as shown in FIG. 20. Alternatively, the electrode 204 or the core
206 may be spring biased to return to a configuration of FIG. 20
when a constraining force is removed. This constraining force may
be applied by a delivery sheath or bronchoscope through which the
inventive device 326 is inserted or by a releasable catch.
[0136] The treatment of the tissue in the airway walls by transfer
of energy according to the present invention provides improved long
term relief from asthma symptoms for some asthma sufferers.
However, over time, some amount of smooth muscle or mucus gland
cells which were not affected by an initial treatment may
regenerate and treatment may have to be repeated after a period of
time such as one or more months or years.
[0137] The airways which are treated with the device according to
the present invention are preferably 1 mm in diameter or greater,
more preferably 3 mm in diameter. The devices are preferably used
to treat airways of the second to eighth generation, more
preferably airways of the second to sixth generation.
[0138] Although the present invention has been described in detail
with respect to devices for the treatment of airways in the lungs,
it should be understood that the present invention may also be used
for treatment of other body conduits. For example, the treatment
system may be used for reducing smooth muscle and spasms of the
esophagus of patients with achalasia or esophageal spasm, in
coronary arteries of patients with Printzmetal's angina variant,
for ureteral spasm, for urethral spasm, and irritable bowel
disorders.
[0139] The devices and method describe herein provide a more
effective and/or permanent treatment for asthma than the currently
used bronchodilating drugs, drugs for reducing mucus secretion, and
drugs for decreasing inflammation.
[0140] Moreover, the inventive device may also include a steering
member configured to guide the device to a desired target location.
For example, this steering member may deflect a distal tip of the
device in a desired direction to navigate to a desired bronchi or
bronchiole. Also contemplated it the use of the device with a
vision system. Such a vision system may comprise a fiber optic
cable which allows a user of the device to guide a distal tip of
the device to its desired location. The vision system may include a
CCD chip.
[0141] Also contemplated as the inventive device is the use of a
power supply for providing energy as described above. The power
supply provides the energy to be delivered to airway tissue via the
energy transfer device. While the main goal of the power supply is
to deliver enough energy to produce the desired effect, the power
supply must also deliver the energy for a sufficient duration such
that the effect persists. This is accomplished by a time setting
which may be entered into the power supply memory by a user.
[0142] A power supply may also include circuitry for monitoring
parameters of energy transfer: (for example, voltage, current,
power, impedance, as well as temperature from the temperature
sensing element), and use this information to control the amount of
energy delivered.
[0143] A power supply may also include control modes for delivering
energy safely and effectively. Energy may be delivered in open loop
power control mode for a specific time duration. Energy may also be
delivered in temperature control mode, with output power varied to
maintain a certain temperature for a specific time duration. In the
case of RF energy delivery via RF electrodes, the power supply may
operate in impedance control mode.
[0144] In temperature control mode with RF electrodes described
here, the power supply will operate at up to a 75.degree. C.
setting. The duration must be long enough to produce the desired
effect, but as short as possible to allow treatment of all of the
desired target airways within a lung. For example, 5 to 10 seconds
per activation (while the device is stationary) is preferred.
Shorter duration with higher temperature will also produce
acceptable acute effect.
[0145] Using RF electrodes as described above in power control
mode, power ranges of 10-15 W with durations of 3-5 seconds are
preferred but may be varied. It should be noted that different
device constructions utilize different parameter settings to
achieve the desired effect. For example, while direct RF electrodes
typically utilize temperatures up to 75.degree. C. in temperature
control mode, the resistively heated electrodes may utilize
temperatures up to 90.degree. C. Also, in addition to the control
nodes specified above, the power supply may include control
algorithms to limit excessive thermal damage to the airway tissue.
For example, in order to stop delivery of energy in the event of
contact between airway tissue and device legs having temperature
sensing capabilities, an algorithm may be employed to shut down
energy delivery if the sensed temperature does not rise by a
certain number of degrees in a pre-specified amount of time after
energy delivery begins. Another way to stop energy delivery
includes shutting down a power supply if the temperature ramp is
not within a predefined rage at any time during energy delivery.
Other algorithms include shutting down a power supply if a maximum
temperature setting is exceeded or shutting down a power supply if
the sensed temperature suddenly changes, such a change includes
either a drop or rise, this change may indicate failure of the
temperature sensing element.
[0146] Moreover, a variation of the invention includes configuring
each energy exchange element independently to provide selective
energy transfer radially about the device. As discussed above,
another variation of the invention includes providing feedback
control to determine the impedance of the airway to determine the
power required by a power supply. Again, as discussed above, the
feedback control could also be used to determine the size of the
airway in which the device is positioned.
[0147] Further details as to the use or other variation of the
apparatus described herein may be drawn from the background which
is intended to form part of the present invention. It is noted that
this invention has been described and specific examples of the
invention have been portrayed to convey a proper understanding of
the invention. The use of such examples is not intended to limit
the invention in any way. Additionally, to the extent that there
are variations of the invention which are within the spirit of the
disclosure and are equivalent to features found in the claims, it
is the intent that the claims cover those variations as well. All
equivalents are considered to be within the scope of the claimed
invention, even those which may not have been set forth herein
merely for the sake of brevity. Also, the various aspects of the
invention described herein may be modified and/or used in
combination with such other aspects also described to be part of
the invention either explicitly or inherently to form other
advantageous variations considered to be part of the invention
covered by the claims which follow.
* * * * *