U.S. patent number 6,283,988 [Application Number 09/260,401] was granted by the patent office on 2001-09-04 for bronchial stenter having expandable electrodes.
This patent grant is currently assigned to Broncus Technologies, Inc.. Invention is credited to Keith M. Burger, Michael D. Laufer, Bryan E. Loomas, Don A. Tanaka.
United States Patent |
6,283,988 |
Laufer , et al. |
September 4, 2001 |
Bronchial stenter having expandable electrodes
Abstract
An apparatus and method are provided for treating collapsed
bronchial tubes found in patients with chronic obstructive
pulmonary diseases, such as asthma. The apparatus delivers energy
to inductively heat the tissue of the bronchial tube by directing
electromagnetic energy into the tissue. The apparatus includes
expandable electrodes that come into contact with the walls of the
bronchial tubes. The expandable electrodes may be conical-shaped
electrodes, loop-shaped electrodes, plate-shaped electrodes, or
other shapes. The method includes heating the bronchial tube to
cause tissue in the wall of the bronchial tube to undergo a
structural transformation effective to render the wall capable of
supporting a non-collapsed lumen. The procedure effectively
reinforces the structural integrity of the bronchial tube wall and
thereby prevents the lumen from collapsing.
Inventors: |
Laufer; Michael D. (Menlo Park,
CA), Burger; Keith M. (San Francisco, CA), Loomas; Bryan
E. (Saratoga, CA), Tanaka; Don A. (San Jose, CA) |
Assignee: |
Broncus Technologies, Inc.
(Mountain View, CA)
|
Family
ID: |
22989014 |
Appl.
No.: |
09/260,401 |
Filed: |
March 1, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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003750 |
Jan 7, 1998 |
5972026 |
Oct 26, 1999 |
|
|
833550 |
Apr 7, 1997 |
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Current U.S.
Class: |
607/96; 607/101;
607/105; 607/115 |
Current CPC
Class: |
A61B
18/00 (20130101); A61B 18/1492 (20130101); A61N
1/06 (20130101); A61N 1/403 (20130101); A61B
18/14 (20130101); A61B 2017/00115 (20130101); A61B
2018/00214 (20130101); A61B 2018/00541 (20130101); A61B
2018/044 (20130101); A61B 2018/1407 (20130101); A61B
2018/1807 (20130101) |
Current International
Class: |
A61B
18/14 (20060101); A61B 18/00 (20060101); A61N
1/40 (20060101); A61N 1/06 (20060101); A61B
18/04 (20060101); A61B 18/18 (20060101); A61B
17/00 (20060101); A61F 002/00 () |
Field of
Search: |
;607/96,101,102,113
;606/41,45-47,49-50 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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280 225 A2 |
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Aug 1988 |
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EP |
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286 145 A2 |
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Oct 1988 |
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EP |
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286 145 A3 |
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Oct 1988 |
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EP |
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768 091 A1 |
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Apr 1997 |
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EP |
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2 233 293 |
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Jan 1991 |
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GB |
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545 358 |
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Jul 1977 |
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RU |
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WO 97/40751 |
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Nov 1997 |
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WO |
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WO 99/03413 |
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Jan 1999 |
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WO |
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Other References
Kitamura, S., Color Atlas of Clinical Application of Fiberoptic
Bronchoscopy, p. 17, (Mosby-Year Book, Inc., 1990)..
|
Primary Examiner: Cohen; Lee
Assistant Examiner: Gibson; Roy
Attorney, Agent or Firm: Morrison & Foerster LLP
Parent Case Text
REFERENCE TO RELATED APPLICATION
This is a continuation-in-part application of U.S. application Ser.
No. 08/833,550 filed on Apr. 7, 1997 and U.S. application Ser. No.
09/003,750 filed on Jan. 7, 1998, now U.S. Pat. No. 5,972,026
issued on Oct. 26, 1999.
Claims
What is claimed is:
1. A method of treating a bronchial tube comprising the steps
of:
advancing a treatment apparatus into the lumen of the bronchial
tube wherein the apparatus comprises:
at least one electrode which when energized causes tissue in a wall
of the lumen to undergo a structural transformation effective to
render the wall capable of supporting a non-collapsed lumen,
wherein the at least one electrode is expandable radially outward
to contact the wall of the bronchial tube; and
activating the treatment apparatus to raise the temperature of the
wall to sufficiently effect a structural transformation in the
tissue of the wall.
2. The method of claim 1, wherein the wall is heated to a
temperature of at least 45.degree. C.
3. The method of claim 2, wherein the wall is heated to a
temperature in the range between about 70.degree. C. and about
85.degree. C.
4. The method of claim 1, wherein the wall is heated for about 0.1
to about 600 seconds.
5. The method of claim 4, wherein the wall is heated for about 1 to
about 60 seconds.
6. The method of claim 1, wherein the wall is heated by power
losses through the tissue of the bronchial wall.
7. The method of claim 6, wherein the at least one electrode is
energized by an alternating current at a radio frequency.
8. The method of claim 1, wherein the treatment apparatus is
advanced into the lumen of the bronchial tube through the working
channel of a steerable endoscope.
9. The method of claim 1, wherein the at least one electrode is
resistively heated to treat the tissue of the bronchial wall.
10. The method of claim 9, wherein at least a portion of the
treatment apparatus is insulated from surrounding tissue.
11. An apparatus for treating a wall of a bronchial tube
comprising:
a tubular member having a lumen;
an elongated shaft having a distal portion, the elongated shaft is
at least partially slidably positioned in the lumen of the tubular
member;
at least one electrode supported by the elongated shaft, which when
energized causes tissue in the wall of the bronchial tube to
undergo a structural transformation effective to render the wall
capable of supporting the bronchial tube in a non-collapsed
configuration;
the at least one electrode having a proximal end attached to the
tubular member and a distal end attached to the distal portion of
the elongated shaft, and a contact section between the proximal and
distal ends, wherein the contact section is configured such that
proximal movement of the elongated shaft relative to the tubular
member deflects the contact section of the electrode causing a
sharp bend in the contact section and producing movement of the
contact section in a radially outward direction from the elongated
shaft towards the wall of the bronchial tube; and
a source of energy electrically connected to the at least one
electrode.
12. The apparatus of claim 11 wherein each electrode is biased to
collapse the contact section radially inward towards the elongated
shaft.
13. The apparatus of claim 11 wherein the source of energy produces
energy that is selected from the group consisting of RF energy,
alternating current, microwaves, and combinations thereof.
14. The apparatus of claim 11 wherein the at least one electrode
comprises at least a first electrode and a second electrode, the
first electrode is connected to a positive lead of a RF generator
and the second electrode is connected to a negative lead of the RF
generator.
15. The apparatus of claim 14 wherein the first electrode is
electrically insulated from the second electrode.
16. The apparatus of claim 11 wherein the at least one electrode
comprises at least four electrodes.
17. An apparatus for treating a wall of a bronchial tube
comprising:
a tubular member having a lumen;
an elongated shaft having a distal portion, the elongated shaft is
at least partially slidably positioned in the lumen of the tubular
member;
at least one electrode supported by the elongated shaft, which when
energized causes tissue in the wall of the bronchial tube to
undergo a structural transformation effective to render the wall
capable of supporting the bronchial tube in a non-collapsed
configuration;
wherein each electrode comprises a plurality of opposing portions
having a first end attached to the elongated shaft and a second
free end, said electrode being expandable in a radially outward
direction from the elongated shaft to assume an expanded shape;
and
wherein the tubular member restrains each electrode in a contracted
shape wherein upon advancement out of the tubular member each
electrode assumes the expanded shape causing the free end to
contact the bronchial wall; and
a source of energy electrically connected to the at least one
electrode.
18. The apparatus of claim 17 wherein said plurality of opposing
portions comprises at least one pair of opposing portions.
19. The apparatus of claim 17 wherein the at least one electrode
comprises a plurality of electrodes each having substantially the
same surface contour and each attached at spaced apart locations
along a longitudinal axis of the elongated shaft.
20. The apparatus of claim 17 wherein the at least one electrode is
spring biased to expand radially outward.
21. The apparatus of claim 17 wherein each electrode is formed of a
shape memory material which causes the electrode to expand radially
outwardly in response to a temperature change.
22. The apparatus of claim 17 wherein the source of energy produces
energy that is selected from the group consisting of RF energy,
alternating current, microwaves, and combinations thereof.
23. The apparatus of claim 17 wherein the at least one electrode
comprises a first electrode and a second electrode, the first
electrode is connected to a positive lead of a RF generator and the
second electrode is connected to a negative lead of the RF
generator.
24. The apparatus of claim 23 wherein the first electrode is
electrically insulated from the second electrode.
25. The apparatus of claim 17 wherein the plurality of opposing
portions comprises at least two curved sections which together form
a conical shape, the at least two curved sections overlapping each
other.
26. The apparatus of claim 25 wherein the at least two curved
sections overlap each other further in the contracted shape than in
the expanded shape.
27. The apparatus of claim 17 wherein the plurality of opposing
portions comprises at least one pair of flexible plates located on
substantially opposite sides of the elongated shaft.
28. The apparatus of claim 27 wherein the at least one pair of
flexible plates comprises two pairs of flexible plates.
Description
FIELD OF THE INVENTION
The present invention relates to a device and method for treatment
of the airway obstruction found in chronic obstructive pulmonary
diseases (COPD), such as cystic fibrosis, chronic bronchitis,
emphysema, and asthma.
BACKGROUND OF THE INVENTION
Chronic obstructive pulmonary diseases (COPD), which include such
entities as cystic fibrosis, chronic bronchitis, emphysema, and
asthma are steadily increasing in frequency, possibly due to
continued smoking, increasing air pollution, and the continued
aging of the population. COPD is characterized by edema of the
mucous membranes, which line the interior walls of the
tracheobronchial tree. When the mucosa accumulates an abnormal
quantity of liquid, the profuse and thickened serous fluid excreted
may seriously affect ventilation in the alveoli. The mucus resists
movement up the walls of the tracheobronchial tree, normally
efficiently accomplished by the cilia throughout the airways which
are also destroyed. Consequently, the serous fluid can form mucus
plugs, which can shut off alveoli or entire airways. In addition to
secretion accumulation, airway obstruction can occur because the
tubes collapse due to destruction of connective tissue. This
reduces the ability to get oxygen into the blood and carbon dioxide
out of the blood.
Asthma is the most common form of bronchoconstrictive disease and
pathologically involves constriction of the bronchioles,
hypertrophy of the muscles of the bronchioles, and a characteristic
infiltrate of eosinophils. Both asthma and other COPDs are
characterized by the constriction or collapse of airway passages in
the lungs that are not supported by cartilage. This condition is
marked by labored breathing accompanied by wheezing, by a sense of
constriction in the chest, and often by attacks of coughing and
gasping. Individuals who are afflicted may attempt to compensate by
blowing harder only to have the airways collapse further. A person
with poor resulting ventilation suffers from a number of metabolic
conditions including accumulation of carbon dioxide. These
individuals also often have hyperinflated enlarged lungs and
barrel-shaped chests.
A wide variety of drugs are available for treating the symptoms of
COPD but none is curative. Cystic fibrosis, chronic bronchitis, and
emphysema are typically treated with agents to thin and dry up the
secretions and with antibiotics to combat infection and with
bronchodilators. These drugs include potassium iodide,
antihistamines, various antibiotics, beta agonists, and
aminophylline. Unfortunately, a large number of patients are not
responsive to these medications or become non-responsive after
prolonged periods of treatment. For severe cases involving
collapsed air passages, surgeons have endeavored to alleviate this
disabling condition by either removing a portion of the lungs or
constricting the volume of lung available for respiration by
stapling off sections thereof. The result is that functionally the
diaphragm and muscles in the chest wall operate on a smaller lung
volume which may improve air movement for some individuals. These
operations are quite risky and are associated with a large number
of deaths. Patients undergoing these treatments are quite ill and
these procedures are considered final options.
Notwithstanding the conventional treatments available, there exists
a need in the art for an effective treatment for chronic
obstructive pulmonary diseases, such as cystic fibrosis, chronic
bronchitis, emphysema, and asthma. Specifically, there is a need
for effective treatment for individuals with obstructed airway
passages to restore pulmonary function which only requires minimal
surgery.
SUMMARY OF THE INVENTION
Many types of tissue can be molded and remodeled to correct defects
and dysfunction. One technique involves physical manipulation using
mechanical instruments and/or balloons to effect selective
shrinking, stretching, flattening, thinning, or thickening in
addition to changing the material properties of the tissue. These
changes of properties include alteration of the elastic coefficient
of the tissue causing it to be stiffer, changing the tensile
strength of the tissue, changing the shear strength of the tissue,
and changing the floppiness or resiliency of the tissue. When the
tissue is close to the surface of the skin or part of a
non-critical organ, physical manipulation is feasible and can be
executed with minimal trauma to the patient. However, when the
tissue is in an internal organ, in particular, in the lungs or
other vital organ, molding and remodeling by physical manipulation
can involve complicated and often risky surgery.
The present invention is based, in part, on the development of a
heat treatment apparatus having expandable electrodes that are
capable of delivering energy to bronchial tubes uniformly. The heat
is preferably inductively applied by directing electromagnetic
energy, such as radio frequency, into the tissue to keep the
bronchial tubes open.
In accordance with one aspect of the present invention, a method
for treating a bronchial tube includes the steps of:
a) maneuvering a heating apparatus into a lumen of the bronchial
tube;
b) heating tissue of the bronchial tube to cause tissue in a wall
of the lumen to undergo a structural transformation effective to
render the wall capable of supporting the lumen without collapsing;
and
c) removing the apparatus from the bronchial tube.
Prior to treatment, the lumen can be non-collapsed, partially, or
fully collapsed. Preferably, the bronchial tube is heated to a
temperature in the range of about 60.degree. C. to about 95.degree.
C. for about 0.1 to about 600 seconds. With the inventive
procedure, extensive surgery and the accompanying trauma are
avoided.
This invention is particularly useful for treating subjects
experiencing difficulty in breathing as a result of obstructed
airway passages caused by, for example, chronic obstructive
pulmonary disease, including, for example, cystic fibrosis, chronic
bronchitis, emphysema, and asthma. This invention ameliorates the
affects of these diseases by improving lung function by keeping the
airway passages open. Specifically, the present invention provides
a device and method for effecting changes in soft tissue in the
bronchial tubes or air passages of the lungs which have collapsed.
The causes of the collapse may be the destruction of the connective
tissue, the disease process, swelling, and/or muscle-dependant
constriction. The invention is directed to a treatment process
which effectively creates an internal bronchial stent which
prevents the air passages from collapsing.
In one aspect, the invention is directed to an apparatus for
treating a bronchial tube having a lumen, which includes:
a tubular member having a lumen;
an elongated shaft that is at least partially slidably positioned
in the lumen of the tubular member;
at least one electrode supported by the elongated shaft, which when
energized causes tissue in the wall of the bronchial tube to
undergo a structural transformation effective to render the wall
capable of supporting the bronchial tube in a non-collapsed
configuration, wherein the at least one electrode is pivotally
mounted on the elongated shaft and expandable radially outward to
contact the wall of the bronchial tube; and
a source of energy electrically connected to the at least one
electrode.
In another aspect, the invention is directed to a method of
treating a bronchial tube comprising a lumen of an individual that
includes the step of:
advancing the above described treatment apparatus into the lumen of
the bronchial tube; and
activating the treatment device to raise the temperature of the
wall to sufficiently effect a structural transformation in the
tissue of the wall.
BRIEF DESCRIPTION OF THE DRAWINGS
As used herein, like reference numerals will designate similar
elements in the various embodiments of the present invention
wherein:
FIG. 1 is a schematic side view of one embodiment of a heat
treatment apparatus of the present invention which employs two
collapsible and retractable electrodes;
FIG. 2 is an enlarged partial cross sectional view of a distal end
of another embodiment of a heat treatment having one collapsible
electrode;
FIG. 3 is a side cross sectional view of an alternative embodiment
of a heat treatment device having two wire shape electrodes;
FIG. 4 is a side cross sectional view of the device of FIG. 3 in an
enlarged state within a bronchial tube;
FIG. 5 is a side cross sectional view of an alternative embodiment
of a heat treatment device with four electrodes in an enlarged
state within a bronchial tube;
FIG. 5A is an end view of the device of FIG. 5;
FIG. 6 is a side cross sectional view of an alternative embodiment
of a heat treatment apparatus with a loop shaped electrode in a
contracted state;
FIG. 7 is a side cross sectional view of the apparatus of FIG. 6
with the electrode in an expanded state within a bronchial
tube;
FIG. 8 is a side cross sectional view of an alternative embodiment
of the invention with a plate shaped electrode in a contracted
state;
FIG. 9 is an end view of the apparatus of FIG. 8 in the contracted
state;
FIG. 10 is a side cross sectional view of the apparatus of FIG. 8
with the plate shaped electrodes in an expanded configuration;
and
FIG. 11 is an end view of the expanded apparatus of FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a first embodiment of a heat treatment apparatus 10
which is introduced through a catheter, bronchoscope, or other
tubular introducer member 12. The heat treatment apparatus includes
a shaft 14 and one or more electrodes 16. Electrically connected to
the electrodes 16 is an RF generator 18 or other energy source. The
RF generator is controlled by a controller 20. Although the
invention will be described as employing an RF generator, other
energy sources, such as alternating current and microwave may also
be used.
In accordance with the embodiment of FIG. 1, the electrodes include
a first conical electrode 16A connected to an inner shaft 22 and a
second conical electrode 16B connected to an outer shaft 24. The
conical electrodes 16A, 16B are positioned with their axes aligned
and may be fixed or movable with respect to each other. Each of the
conical electrodes 16A, 16B, includes at least two overlapping
sections or opposing portions 26. The sections 26 are flexible and
overlap one another to allow the electrodes 16A, 16B to be
compressed within the lumen of the catheter 12 for insertion into
the bronchial tube of a patient. Once the catheter 12 is positioned
with a distal end at a desired treatment location within the
bronchial tubes, the shaft 14 is used to push the electrodes 16A,
16B out of the distal end of the catheter. Once deployed from the
catheter 12 the electrodes 16A, 16B expand radially outwardly until
the distal ends of the electrodes contact the walls of the
bronchial tube.
The electrodes 16A, 16B are electrically connected to the RF
generator 18 by electrical cables 28, 30. When the heat treatment
apparatus 10 employs two electrodes 16A, 16B the two electrodes are
preferably oppositely charged with one of the electrodes connected
to a negative output of the RF generator and the other electrode
connected to a positive output of the RF generator. Alternatively,
both the electrodes 16A, 16B or a single electrode 16 may be
connected to the same output of the RF generator and an external
electrode 34 may be used. The external electrode 34 is connected to
an output of the RF generator 18 having an opposite polarity of the
output connected to the internal electrode 16.
The present invention is based in part on the discovery that the
structural integrity of bronchial tubes, especially those which do
not have significant amounts of cartilage present, can be
significantly recreated by subjecting the bronchial tubes to a
sufficient amount of heat to cause at least a portion of the soft
tissue to undergo a structural transformation thereby causing the
tubes to remain patent. This structural transformation may be due
to a variety of sources such as, scar tissue buildup, collagen
restructuring, or the like. This heating procedure changes the
structure of the tissue and the shape of the tube.
As used herein, the term "bronchial tube" or "air passage" refers
to the sub-segments that branch from the main stem bronchus of the
lungs. The term "collapsed lumen" refers to a condition of lumen of
a bronchial tube wherein the lumen is occluded to the extent that
substantial blockage of air flow through the lumen exists. The
diameter of a non-collapsed lumen may be substantially equal to
that of a normal bronchial tube or may be less as in the case of a
partially collapsed but functional lumen. It is understood that the
term "collapsed lumen" encompasses partially collapsed lumens.
Cartilage is not present around these air passages in appreciable
amounts so they have little intrinsic supportive structures.
FIG. 2 shows an alternative embodiment of a heat treatment
apparatus 40 having a single electrode 16 positioned on a shaft 14.
The electrode 16 is shown as it is deployed from the distal end of
a catheter 12 for heat treatment of the lumen of bronchial
tubes.
The electrodes 16 of the embodiment of FIGS. 1 and 2 are formed of
a suitable conductive material such as metal, plastic with a metal
coating, or the like. The two or more sections 26 of each of the
cone shaped electrodes is fixed to the shaft 14 and biased
outwardly so that the sections expand or unfold to an enlarged
diameter upon release from the distal end of the catheter 12. The
electrodes 16 preferably have an enlarged diameter which is equal
to or slightly greater than an interior diameter of the bronchial
tube to be treated. As shown most clearly in FIG. 2, the sides of
the sections 26 overlap one another even in the expanded state.
In operation of the embodiments of FIGS. 1 and 2, the distal end of
the catheter 10 is first positioned at the treatment site by known
catheter tracking methods. The catheter 10 is then retracted over
the heat treatment apparatus to exposed and expand the electrodes
16. Each electrode 16 of the energy emitting apparatus 10 expands
radially outward upon retraction of the catheter 12 until the
electrodes come into contact with the wall of the bronchial tube.
In the embodiment of FIG. 2, the distance between the two energy
emitting electrodes 16A, 16B may be fixed or may be changeable by
sliding the inner shaft 22 within the outer shaft 24. When
treatment is completed the heat treatment apparatus 10 is retracted
back inside the catheter 12 by sliding the catheter over the
electrodes. As the heat treatment apparatus 10 is retracted the
sides of the sections 26 of the electrode 16 slide over each other
upon coming into contact with a distal edge of the catheter 12.
FIGS. 3 and 4 illustrate an alternative embodiment of a heat
treatment apparatus 50. The heat treatment apparatus may be
delivered to a treatment site in a collapsed configuration
illustrated in FIG. 3. The heat treatment apparatus 50 includes two
leaf spring or wire shaped electrodes 54A and 54B. The electrodes
54A, 54B are connected to an insulating end cap 56 of a hollow
shaft 58. The electrodes 54A, 54B are electrically connected to the
RF generator or other energy source by electric cables 60, 62. The
heat treatment apparatus 50 is provided with a central shaft 64
which is slidable within the hollow shaft 58. The central shaft 64
has a shaft tip 48 which is connected to a distal end of each of
the electrodes 54A, 54B.
Each of the electrodes 54A, 54B is preferably insulated with an
insulating sleeve 66 except for an exposed contact section 68. The
heat treatment apparatus 50 is delivered to the lumen of a
bronchial tube to be treated either alone or through a catheter,
bronchoscope, or other channel. The electrodes 54A, 54B are
expanded radially outwardly by moving the central shaft 64
proximally with respect to the hollow shaft 58 of the heat
treatment apparatus 50. Upon expansion, the exposed contact
sections 68 of the electrodes 54A, 54B come into contact with the
walls of the bronchial tube B, shown in FIG. 4. The electrodes 54A,
54B may be configured to bend at a predetermined location forming a
sharp bend as shown in FIG. 4. Alternatively, the electrodes 54A,
54B may form a more gradual curve in the expanded configuration.
The electrodes 54A, 54B are preferably connected to opposite poles
of the energy source. Alternatively, both of the electrodes 54A,
54B may be connected to the same lead of the energy source and the
external electrode 34 may be used. Upon completion of the treatment
process the electrodes 54 are retracted back into the catheter for
removal or moving to a subsequent treatment site.
FIGS. 5 and 5a illustrate an alternative embodiment of the
invention in which the heat treatment apparatus 50 includes four
electrodes 54A, 54B, 54C, 54D. The four electrode embodiment of
FIGS. 5 and 5a operates in the same manner as the embodiments of
FIGS. 3 and 4 with a slidable central shaft 64 employed to move the
electrodes from a compressed configuration to the expanded
configuration illustrated in FIGS. 5 and 5a. Each electrode 54A-54D
is connected at a proximal end to the insulating end cap 56 of the
hollow shaft 58 and at a distal end to the central shaft 64.
Relative motion of the hollow shaft 58 with respect to the central
shaft 64 moves the electrodes 54 from the collapsed to the expanded
position.
FIGS. 6 and 7 illustrate a further embodiment of a heat treatment
apparatus 90 employing one or more wire or leaf spring shaped loop
electrodes 94. As in the previous embodiments, the loop electrode
94 expands from a contracted positioned within a catheter 92 as
illustrated in FIG. 10 to an expanded position illustrated in FIG.
7. In the expanded position, the loop shaped electrode 94 comes
into contact with the walls of the bronchial tube B. Although the
embodiment of FIGS. 6 and 7 has been illustrated with a single loop
shaped electrode 94, it should be understood that multiple loop
shaped electrodes may also be use. The loop shaped electrode 92 is
connected to the shaft 96 of the heat treatment apparatus 90 by an
end cap 98 and is electrically connected to the energy source by
the electric cables 100.
FIGS. 8-11 illustrate an alternative embodiment of a heat treatment
apparatus 110 having a flexible plate shaped electrode 114. The
flexible plate shaped electrode 114 is substantially flower shaped
in plan having a plurality of petals or opposing portions 116 with
curved distal ends extending from a central section 120. The petals
116 flex along a hinge line 118 to the compressed insertion
configuration illustrated in FIG. 8 in which the petals 116 extend
substantially perpendicularly from the central section 120 of the
flexible plate shaped electrode 114.
As illustrated in FIG. 10 and 11, when the heat treatment apparatus
110 is moved distally with respect to the catheter 112 to deploy
the electrode 114 the petals 116 move outwardly until the petal
tips come into contact with the walls of the bronchial tube B. The
flexible plate shaped electrode 114 is preferably formed of a
conductive material and fixed to the end of a shaft 122. Electric
cables 124 connect the plate shaped electrode 114 to the energy
source.
The electrodes in each of the forgoing embodiments may be
fabricated of any material which when compressed will return to an
expanded configuration upon release of the compression forces. For
example, one method of controlling the expansion of the electrodes
is the use of shape memory alloy electrodes. With a shape memory
alloy, the constraint of the electrodes within a catheter may not
be necessary. The shape memory alloy electrodes may be formed to
expand to an expanded energy delivery configuration upon heating to
body temperature within the body. The expansion of the electrodes
is limited by the size of the bronchial tube in which the electrode
is positioned.
The heat treatment apparatus according to the present invention may
be employed in a bipolar mode in which two different expandable
electrodes are connected to two different outputs of the RF
generator 18 having opposite polarities. For example, the
electrodes 16A, 16B may be connected by the electrical cables 28,
30 to different terminals of the RF generator 18. Alternatively,
when more than two electrodes 16 are employed, multiple electrodes
may be connected to one terminal of the RF generator. In each of
the embodiments of the heat treatment apparatus, the oppositely
charged electrodes are separated by an insulating material. For
example, in the embodiment of FIG. 1, the inner shaft 22 and outer
shaft 24 are formed of an insulating material. Further, in the
embodiments of FIGS. 3-5 the end cap 56 and central shaft distal
tip 82 are formed of insulating materials.
In the case where the apparatus includes only one electrode 16 as
shown in FIG. 2, the electrode will be connected to the positive or
negative terminal of the RF generator 18 and the opposite terminal
of the RF generator will be connected to the external electrode
32.
The frequency range of RF radiation useful in the present invention
is typically about 10 KHz to about 100 MHz, preferably in the range
of about 200 KHz to about 800 KHz. However, frequencies outside
this range may be used at the discretion of the operating surgeon.
Typically, the amount of power employed will be from about 0.01 to
100 watts and preferably in the range of about 1 to 25 watts for
about 1 to 60 seconds. Alternatively, alternating current or
microwave radiation typically in the frequency range of about 1,000
MHz to about 2,000 MHz and preferably from about 1,100 MHz to about
1,500 MHz may be used in place of RF radiation. In the latter case,
the RF generator 18 is replaced with a microwave generator, and the
electric cables 28, 30 are replaced with waveguides.
When the heat treatment apparatus with the bipolar electrodes is
positioned inside the lumen of a bronchial tube, activation of the
RF generator 18 causes tissue in the lumen wall to increase in
temperature. The heating may be caused by resistance heating of the
electrodes themselves and/or power losses through the tissue of the
bronchial wall. The particular heat pattern in the tissue will
depend on the path of the electric field created by the positioning
and configuration of the electrodes.
In the monopolar mode, the external electrode 34, shown in FIG. 1,
having a much larger surface area than the inner electrodes is
placed on the outer surface of the patient's body. For example, the
external electrode 34 can be an external metal mesh or a solid
plate that is placed on the skin. Both the internal and external
electrodes are connected to the RF generator 18 which produces an
electric field at a high frequency. Because the collective surface
area of the internal electrodes is much smaller than that of the
outer electrode 34, the density of the high frequency electric
field is much higher around the internal electrodes. The electric
field reaches its highest density in the region near the internal
electrodes. The increased density of the field around the internal
electrodes produces localized heating of the tissue around the
bronchial tube without causing significant heating of the body
tissue between the bronchial tube and the external electrode.
In use, after the operating surgeon has placed the heat treatment
apparatus within the lumen of a bronchial tube to be treated, if
necessary, the catheter is retracted to expose the electrodes. In
the case where the lumen of the bronchial tube has collapsed or is
partially collapsed, the size of the energy emitting device is
designed so that expansion of the electrodes causes the lumen to
expand to its normal or non-collapsed diameter due to contact of
the electrodes with the inner surface of the lumen. Alternatively,
in the case where the lumen has not collapsed, the device is
designed so that upon expansion the electrodes are in substantial
contact with the inner surface of the lumen. Indeed, only minimum
expansion may be necessary in treating a non-collapsed bronchial
lumen.
The degree of expansion of the electrodes of the heat treatment
apparatus can be monitored by means of endoscopy, fluoroscopy, or
by other suitable imaging methods of the art. Generally, the heat
required is induced in the tissue of the bronchial tube wall by the
RF or microwave radiation emitting from the electrodes. The RF or
microwave energy is applied while observing the tissue for changes
via simultaneous endoscopy, or other suitable imaging methods of
the art.
As is apparent, the inventive heat treatment apparatus can be
employed to treat a bronchial tube regardless of whether the tube
lumen has collapsed or not. Specifically, the devices can be used
to treat bronchial tubes that have not collapsed, are partially
collapsed, or are fully collapsed. Moreover, bronchial tubes may
exhibit different degrees of closure depending on the state of
respiration. For example, a bronchial tube may have a fully
expanded lumen after inhalation but partially or completely closed
during exhalation.
The electrodes employed in the present invention are constructed of
a suitable current conducting metal or alloys such as, for example,
copper, steel, platinum, and the like or of a plastic material with
a conductive metal insert. The electrodes can also be constructed
of a shape memory alloy which is capable of assuming a
predetermined, i.e., programmed, shape upon reaching a
predetermined, i.e., activation temperature. Such metals are well
known in the art as described, for example, in U.S. Pat. Nos.
4,621,882 and 4,772,112 which are incorporated herein by reference.
For the present invention, the shape memory metal used should have
the characteristic of assuming a deflection away (i.e., expands)
from the elongated rod when activated, i.e., heated in excess of
the normal body temperature and preferably between 60.degree. C.
and 95.degree. C. A preferred shape memory alloy is available as
NITINOL from Raychem Corp., Menlo Park, Calif. In one embodiment,
the electrodes are constructed of NITINOL in a predetermined shape
and in the alloy's super elastic phase which can withstand very
large deflections without deformation.
The function of the heat treatment apparatus is to apply a
sufficient amount of energy to the walls of air passages to cause
tissue in the walls to undergo a structural transformation to
create more rigid walls that can support a non-collapsed, patent
lumen. RF energy is no longer applied after there has been
sufficient transformation, e.g., shrinkage, of the tissue fibers
which may be gauged by removing the heating device from the
treatment site and visually determining whether the lumen remains
noncollapsed. Sufficient shrinkage may also be detected by
fluoroscopy, external ultrasound scanning, pulse-echo ultrasound
scanning, sensing the collapsing or straightening of the heating
element with appropriate feedback variables, impedance monitoring
or any other suitable method.
Substantial tissue transformation may be achieved very rapidly,
depending upon the specific treatment conditions. Because the
transformation can proceed at a rather rapid rate, the RF energy
should be applied at low power levels. Preferably, the RF energy is
applied for a length of time in the range of about 0.1 second to
about 600 seconds, and preferably about 1 to about 60 seconds.
Suitable RF power sources are commercially available and well known
to those skilled in the art. In one embodiment the RF generator 18
employed has a single channel, delivering approximately 1 to 100
watts, preferably 1 to 25 watts, and most preferably 2 to 8 watts
of RF energy and possessing continuous flow capability. The rate of
collagen transformation can be controlled by varying the energy
delivered to the heat treatment device. Regardless of the source of
energy used during treatment, the lumen or the bronchial tube is
maintained at a temperature of at least about 45.degree. C.,
preferably between .degree. C. and 95.degree. C. and more
preferably between 70.degree. C. and 85.degree. C.
When the heat treatment apparatus includes multiple energy emitting
devices, not all the electrodes need to be activated at the same
time, that is, different combinations of electrodes can be employed
sequentially. For example, in the case of the embodiment shown in
FIG. 1, with two electrodes 16A, 16B, the electrodes can be
activated simultaneously or sequentially.
In addition, when a heat treatment apparatus includes multiple
energy emitting devices, the apparatus can operate in the
monopolar, bipolar mode, or both modes at the same time. For
instance, one of the electrodes can be designed to operate in the
bipolar mode while another electrode operates in the monopolar
mode.
When treating a person with obstructed air passages, a preliminary
diagnosis is made to identify the air passages or bronchial tube
that can be treated. In treating a particular site, excessive fluid
is first removed from the obstructed air passage by conventional
means such as with a suction catheter. Thereafter, the inventive
heat treatment device is maneuvered to the treatment site.
Depending on the diameter of the lumen of the bronchial tube, the
device can be positioned directly at the treatment site or it can
be positioned into place with a bronchoscope. The elongated shafts
22, 24 and outer catheter 12 are preferably made of a flexible
material so that the catheter can be maneuvered through a
bronchoscope. A bronchoscope is a modified catheter which includes
an illuminating and visualization instrument for monitoring the
treatment site and a channel for passing instruments (e.g., the
treatment device) into the bronchial tubes.
In operation, the bronchoscope is advanced from the person's nasal
or oral cavity, through the trachea, main stem bronchus, and into
an obstructed air passage. The heat treatment apparatus is advanced
forward through the bronchoscope to expose the tip of the heat
treatment device before the treatment device is energized.
Depending on the size of the treatment device, the treatment device
can be moved to another position for further heat treatment of the
air passage. This process can be repeated as many times as
necessary to form a series of patency bands supporting an air
passage. This procedure is applied to a sufficient number of air
passages until the physician determines that he is finished. As is
apparent, the procedure can be completed in one treatment or
multiple treatments. After completion of the treatment, energy is
discontinued and the treatment device is removed from the
patient.
The heating apparatus can be made to provide protection against
overheating of the connective tissue which will cause the collagen
to denature. Temperature monitoring and impedance monitoring can be
utilized in a system which provides feedback to the user in the
form of sounds, lights, other displays or a mechanism which shuts
down the application of energy from the heating element to the
treatment site when sufficient tissue transformation is detected
and to avoid burning of the treatment site. The amount of energy
applied can be decreased or eliminated manually or automatically
under certain conditions. For example, the temperature of the wall
of the air passage, or of the heating element can be monitored and
the energy being applied adjusted accordingly. The surgeon can, if
desired, override the feedback control system. A microprocessor can
be included and incorporated into the feedback control system to
switch the power on and off, as well as to modulate the power. The
microprocessor can serve as a controller to monitor the temperature
and modulate the power.
The invention is also directed to the demonstration or instruction
of the inventive surgical techniques including, but not limited to,
written instructions, actual instructions involving patients,
audio-visual presentations, animal demonstrations, and the
like.
While the invention has been described in detail with reference to
the preferred embodiments thereof, it will be apparent to one
skilled in the art that various changes and modifications can be
made and equivalents employed, without departing from the present
invention.
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