U.S. patent application number 11/373356 was filed with the patent office on 2006-11-09 for systems and methods for electrosurgical treatment of obstructive sleep disorders.
This patent application is currently assigned to ArthroCare Corporation. Invention is credited to Philip E. Eggers, Maria B. Ellsberry, David C. Hovda, Hira V. Thapliyal.
Application Number | 20060253117 11/373356 |
Document ID | / |
Family ID | 27374556 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060253117 |
Kind Code |
A1 |
Hovda; David C. ; et
al. |
November 9, 2006 |
Systems and methods for electrosurgical treatment of obstructive
sleep disorders
Abstract
The present invention provides systems and methods for
selectively applying electrical energy to a target location within
the head and neck of a patient's body, particularly including
tissue in the ear, nose and throat. The present invention applies
high frequency (RF) electrical energy to one or more electrode
terminals in the presence of electrically conductive fluid to
remove and/or modify the structure of tissue structures. The
present invention is particularly useful for treating sleep
obstructive disorders, such as sleep apnea and snoring.
Inventors: |
Hovda; David C.; (Mountain
View, CA) ; Ellsberry; Maria B.; (Fremont, CA)
; Eggers; Philip E.; (Dublin, OH) ; Thapliyal;
Hira V.; (Los Altos, CA) |
Correspondence
Address: |
ARTHROCARE CORPORATION
680 VAQUEROS AVENUE
SUNNYVALE
CA
94085-3523
US
|
Assignee: |
ArthroCare Corporation
Austin
TX
|
Family ID: |
27374556 |
Appl. No.: |
11/373356 |
Filed: |
March 9, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09562496 |
May 1, 2000 |
|
|
|
11373356 |
Mar 9, 2006 |
|
|
|
09136079 |
Aug 18, 1998 |
6086585 |
|
|
09562496 |
May 1, 2000 |
|
|
|
09083526 |
May 22, 1998 |
6053172 |
|
|
09136079 |
Aug 18, 1998 |
|
|
|
08990374 |
Dec 15, 1997 |
6109268 |
|
|
09083526 |
May 22, 1998 |
|
|
|
08485219 |
Jun 7, 1995 |
5697281 |
|
|
08990374 |
Dec 15, 1997 |
|
|
|
08446767 |
Jun 2, 1995 |
5697909 |
|
|
08485219 |
Jun 7, 1995 |
|
|
|
08059681 |
May 10, 1993 |
|
|
|
08446767 |
Jun 2, 1995 |
|
|
|
07958977 |
Oct 9, 1992 |
5366443 |
|
|
08059681 |
May 10, 1993 |
|
|
|
07817575 |
Jan 7, 1992 |
|
|
|
07958977 |
Oct 9, 1992 |
|
|
|
Current U.S.
Class: |
606/48 ; 128/898;
606/50 |
Current CPC
Class: |
A61B 18/1402 20130101;
A61B 18/1492 20130101; A61B 18/1485 20130101; A61B 2018/162
20130101; A61B 2018/00678 20130101; A61B 2018/00726 20130101; A61B
2018/00601 20130101; A61B 2018/1273 20130101; A61B 2018/00119
20130101; A61B 2018/00083 20130101; A61B 2018/00791 20130101; A61B
2018/126 20130101; A61B 18/148 20130101; A61B 2017/00026 20130101;
A61B 2018/00178 20130101; A61B 2018/1472 20130101; A61B 18/1482
20130101; A61B 2218/007 20130101; A61B 2017/00101 20130101; A61B
2018/00392 20130101; A61B 18/149 20130101; A61B 2018/0016 20130101;
A61B 2017/00247 20130101; A61B 2018/1253 20130101; A61B 2018/00875
20130101; A61B 2018/00029 20130101; A61B 2018/165 20130101; A61B
2218/002 20130101; A61B 2018/00327 20130101; A61B 2018/00827
20130101; A61B 18/1206 20130101; A61B 2017/00084 20130101; A61B
2018/00583 20130101; A61B 18/042 20130101; A61B 2018/00702
20130101; A61B 2018/1407 20130101; A61B 2018/00505 20130101; A61B
2018/00982 20130101; A61B 2018/1213 20130101; A61B 2018/124
20130101; A61B 2018/00577 20130101; A61B 2018/1467 20130101; A61F
2/2493 20130101 |
Class at
Publication: |
606/048 ;
606/050; 128/898 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1-24. (canceled)
25. An electrosurgical system for use with a high frequency power
supply and an electrically conducting fluid supply, the system
comprising: an electrosurgical probe comprising a shaft having a
proximal end and a distal end, at least one active electrode
disposed near the distal end and adapted to be electrically coupled
to the high frequency power supply; a passive electrode adapted to
be electrically coupled to the high frequency power supply; and a
fluid delivery element defining a fluid path in electrical contact
with the passive electrode and the active electrode, the fluid path
having an inlet adapted to be fluidly coupled to the electrically
conducting fluid supply for directing fluid along the fluid path to
generate a current flow path between the passive electrode and the
active electrode wherein the electrically conductive fluid has an
electrical conductivity equal to or greater than 0.2 mS per cm.
26. The electrosurgical system of claim 25 wherein said
electrically conductive fluid has an electrical conductivity equal
to or greater than 2 mS per cm.
27. The electrosurgical system of claim 25 wherein said
electrically conductive fluid has an electrical conductivity equal
to or greater than 10 mS per cm.
28. The electrosurgical system of claim 25 wherein said
electrically conductive fluid has an electrical conductivity about
equal to 17 mS per cm.
29. The electrosurgical system of claim 25 wherein said high
frequency power supply is configured to supply a voltage difference
between said active electrode and said passive electrode such that
said electrically conductive fluid therebetween is vaporized and
forms a plasma, wherein said plasma comprises energy sufficient to
modify tissue in contact with said plasma.
30. The electrosurgical system of claim 29 wherein said plasma
discharges energy in the Ultraviolet range.
31. The electrosurgical system as recited in claim 25, wherein the
passive electrode forms a portion of the shaft of the
electrosurgical probe.
32. The electrosurgical system as recited in claim 31 further
including an insulating member circumscribing the passive
electrode, the passive electrode being sufficiently spaced from the
active electrode to minimize direct contact between the passive
electrode and a body structure at the target site when the active
electrode is positioned in close proximity or in partial contact
with the body structure.
33. The electrosurgical system as recited in claim 31, wherein the
passive electrode is an inner tubular member and the fluid delivery
element comprises an axial lumen within the passive electrode, the
axial lumen directing the fluid and having an inlet in
communication with the electrically conducting fluid supply and an
outlet in fluid communication with the active electrode.
34. The electrosurgical system as recited in claim 31, wherein the
passive electrode is an outer tubular member, the shaft further
comprising an insulating member, wherein the fluid delivery element
comprises an axial passage between the insulating member and the
passive electrode, the axial passage for directing the fluid and
having an inlet in communication with the electrically conducting
fluid supply and an outlet in fluid and electrical communication
with the active electrode.
35. The electrosurgical system as recited in claim 25 wherein the
fluid delivery element comprises a fluid supply instrument separate
from the electrosurgical probe.
36. The electrosurgical system of claim 25 wherein the active
electrode is comprised of a single active electrode disposed near
the distal end of the shaft.
37. The electrosurgical system of claim 25 further comprising an
insulating matrix surrounding and supporting the active electrode
to electrically isolate a proximal portion of the active electrode
from the electrically conducting fluid, the insulating matrix
comprising an inorganic material.
38. The electrosurgical system of claim 25 further comprising a
fluid supply outside of the body.
39. The electrosurgical system of claim 25 wherein the active
electrode and the passive electrode are configured to effect the
molecular breakdown of tissue in the immediate vicinity of the
active electrode when high frequency voltage is applied between the
active electrode and the passive electrode in the presence of
electrically conducting fluid.
40. The electrosurgical system of claim 25 wherein the electrically
conducting fluid is isotonic saline.
41. The electrosurgical system of claim 25 wherein the active
electrode has a distal portion configured for generating high
electric field intensities sufficient to cause molecular
disintegration of a body structure at the target site.
42. The electrosurgical system of claim 25 wherein the active
electrode comprises a surface or edge adapted for cutting of
tissue.
43. The electrosurgical system of claim 25 wherein the probe
comprises a lateral surface, the active electrode being positioned
on the lateral surface such that the active electrode may be
brought into at least partial contact or close proximity with the
tissue surfaces which are substantially tangent to the
electrosurgical probe.
44. The electrosurgical system of claim 25 wherein the passive
electrode is adapted to have minimal tissue effect.
45. The electrosurgical system of claim 25 wherein the passive
electrode is configured to provide a low current density relative
to the active electrode.
46. The electrosurgical system of claim 25 wherein the passive
electrode is substantially larger than said active electrode.
47. The electrosurgical system of claim 25 wherein said passive
electrode is axially spaced away from the active electrode.
48. The electrosurgical system of claim 25 wherein said passive
electrode is axially spaced from the active electrode a distance
between 1 mm to 10 mm.
49. The system as recited in claim 25 wherein said passive
electrode has an exposed surface area 2 to 7.5 times greater than
an exposed surface area of the active electrode.
50. An electrosurgical system for applying electrical energy to a
target site on a structure within or on a patient's body, the
system comprising: a high frequency power supply; an
electrosurgical probe comprising a shaft having a proximal end and
a distal end, an active electrode disposed near the distal end,
said active electrode being electrically coupled to the high
frequency power supply; a passive electrode electrically coupled to
the high frequency power supply; and an electrically conducting
fluid supply for supplying electrically conducting fluid to the
target site such that the electrically conducting fluid generates a
current flow path between the passive electrode and the active
electrode wherein the electrically conductive fluid has an
electrical conductivity equal to or greater than 0.2 mS per cm.
51. An electrosurgical system for applying electrical energy to a
target site on a structure within or on a patient's body, the
system comprising: a high frequency power supply; an
electrosurgical probe comprising a shaft having a proximal end and
a distal end, an active electrode disposed near the distal end,
said active electrode being electrically coupled to the power
supply; a passive electrode electrically coupled to the power
supply; and a fluid delivery element for directing electrically
conducting fluid to the target site and to substantially surround
the active electrode with electrically conducting fluid and to
locate electrically conducting fluid between the active electrode
and the passive electrode and between the active electrode and the
target site wherein the electrically conductive fluid has an
electrical conductivity equal to or greater than 0.2 mS per cm.
52. An electrosurgical system for applying electrical energy to a
target site on a structure within or on a patient's body, the
system comprising: a high frequency power supply; an
electrosurgical probe comprising a shaft having a proximal end and
a distal end, an active electrode disposed near the distal end,
said active electrode being electrically coupled to the high
frequency power supply; a passive electrode electrically coupled to
the high frequency power supply; and an electrically conducting
fluid supply for supplying electrically conducting fluid to the
target site from outside of the body such that the electrically
conducting fluid generates a current flow path between the passive
electrode and the active electrode.
Description
RELATED APPLICATIONS
[0001] The present invention is a continuation-in-part of U.S.
patent application Ser. No. 09/083,526, filed May 22, 1998
(Attorney Docket No. E-3-1), which is a continuation-in-part of
Ser. No. 08/990,374, filed Dec. 15, 1997 (Attorney Docket E-3),
which is a continuation-in-part of U.S. Pat. No. 5,697,281, the
complete disclosures of which are incorporated herein by reference
for all purposes. This application also derives priority from U.S.
patent application Ser. No. 09/041,934, filed Mar. 13, 1998
(Attorney Docket No. A-1-6), the complete disclosure of which is
incorporated herein by reference for all purposes.
[0002] The present invention is related to commonly assigned
co-pending U.S. patent application Ser. No. 09/058,571, filed on
Apr. 10, 1998 (Attorney Docket No. CB-2) and U.S. patent
application Ser. No. 09/054,323, filed on Apr. 2, 1998 (Attorney
Docket No. E-5), U.S. patent application Ser. No. 09/010,382, filed
Jan. 21, 1998 (Attorney Docket A-6), and U.S. patent application
Ser. No. 09/032,375, filed Feb. 27, 1998 (Attorney Docket No.
CB-3), U.S. patent application Ser. No. 08/977,845, filed on Nov.
25, 1997 (Attorney Docket No. D-2), Ser. No. 08/942,580, filed on
Oct. 2, 1997 (Attorney Docket No. 16238-001300), Ser. No.
09/026,851, filed Feb. 20, 1998 (Attorney Docket No. S-2), U.S.
application Ser. No. 08/753,227, filed on Nov. 22, 1996 (Docket
16238-002200), U.S. application Ser. No. 08/687792, filed on Jul.
18, 1996 (Docket No. 16238-001600), and PCT International
Application, U.S. National Phase Serial No. PCT/US94/05168, filed
on May 10, 1994, now U.S. Pat. No. 5,697,909 (Attorney Docket
16238-000440), which was a continuation-in-part of U.S. patent
application Ser. No. 08/059,681, filed on May 10, 1993 (Attorney
Docket 16238-000420), which was a continuation-in-part of U.S.
patent application Ser. No. 07/958,977, filed on Oct. 9, 1992
(Attorney Docket 16238-000410) which was a continuation-in-part of
U.S. patent application Ser. No. 07/817,575, filed on Jan. 7, 1992
(Attorney Docket 16238-00040), the complete disclosures of which
are incorporated herein by reference for all purposes. The present
invention is also related to commonly assigned U.S. Pat. No.
5,683,366, filed Nov. 22, 1995 (Attorney Docket 16238-000700), the
complete disclosure of which is incorporated herein by reference
for all purposes.
BACKGROUND OF THE INVENTION
[0003] The present invention relates generally to the field of
electrosurgery, and more particularly to surgical devices and
methods which employ high frequency electrical energy to treat
tissue in regions of the head and neck, such as the ear, nose and
throat. The present invention is particularly suited for treating
sleep obstructive disorders, such as sleep-apnea, snoring and the
like.
[0004] Sleep-apnea syndrome is a medical condition characterized by
daytime hypersomnolence, intellectual deterioration, cardiac
arrhythmias, snoring and thrashing during sleep. This syndrome is
classically divided into two types. One type, termed "central sleep
apnea syndrome", is characterized by repeated loss of respiratory
effort. The second type, termed obstructive sleep apnea syndrome,
is characterized by repeated apneic episodes during sleep resulting
from obstruction of the patient's upper airway or that portion of
the patient's respiratory tract which is cephalad to, and does not
include, the larynx.
[0005] Treatment for sleep apnea has included various medical,
surgical and physical measures. Medical measures include the use of
medications and the avoidance of central nervous system
depressants, such as sedatives or alcohol. These measures are
sometimes helpful, but rarely completely effective. Physical
measures have included weight loss, nasopharygeal airways, nasal
CPAP and various tongue retaining devices used nocturnally. These
measures are cumbersome, uncomfortable and difficult to use for
prolonged periods of time. In particular, CPAP devices, which act
essentially as a pneumatic "splint" to the airway to alleviate the
obstruction, may last for the entire patient's lifetime, and
typically requires close to 100% usage of the device while sleeping
and napping.
[0006] Surgical interventions have included
uvulopalatopharyngoplasty (UPPP), laser-assisted uvuloplasty
procedures (LAUP), tonsillectomy, surgery to correct severe
retrognathia and tracheostomy. The LAUP procedures involve the use
a CO.sub.2 laser to excise and vaporize excess tissue in the region
of the palate and uvula. In UPPP procedures, a scalpel or
conventional electrocautery device is typically employed to remove
portions of the uvula, palate, pharynx and/or tonsils. While these
procedures are effective, the risk of surgery in some patients is
often prohibitive. In addition, UPPP and LAUP procedures performed
with conventional electrocautery or laser devices typically
generate excessive bleeding and extreme post-operative pain which
may be unacceptable to the patient.
[0007] Recently, RF energy has been used to selectively destroy
portions of the tongue to treat air passage disorders, such as
sleep apnea. This procedure, which was developed by Somnus Medical
Technologies of Sunnyvale, Calif., involves the use of a monopolar
electrode that directs RF current into the target tissue to
desiccate or destroy submucosal tissue in the patient's mouth. Of
course, such monopolar devices suffer from the disadvantage that
the electric current will flow through undefined paths in the
patient's body, thereby increasing the risk of unwanted electrical
stimulation to portions of the patient's body. In addition, since
the defined path through the patient's body has a relatively high
impedance (because of the large distance or resistivity of the
patient's body), large voltage differences must typically be
applied between the return and active electrodes in order to
generate a current suitable for ablation or cutting of the target
tissue. This current, however, may inadvertently flow along body
paths having less impedance than the defined electrical path, which
will substantially increase the current flowing through these
paths, possibly causing damage to or destroying surrounding tissue
or neighboring peripheral nerves.
SUMMARY OF THE INVENTION
[0008] The present invention provides systems, apparatus and
methods for selectively applying electrical energy to structures in
the head and neck of a patient's body, such as tissue within the
ear, nose and throat.
[0009] The systems and methods of the present invention are
particularly useful for ablation, cutting and hemostasis of tissue
for gross tissue removal in the mouth and throat and for treating
obstructive sleep disorders, such as snoring or sleep apnea. The
present invention removes obstructive tissue within the mouth and
throat with a novel, precise process that involves lower
temperatures than conventional RF devices and lasers used for such
tissue removal. Consequently, the gross tissue removal of the
present invention provides significantly less collateral tissue
damage, which results in less post-operative pain and faster
healing than conventional procedures.
[0010] Methods of the present invention include introducing one or
more electrode terminal(s) into the patient's mouth, and
positioning the electrode terminal(s) adjacent the target tissue,
e.g., selected portions of the tongue, tonsils, soft palate tissues
(e.g., the uvula and pharynx), hard tissue or other mucosal tissue.
Electrically conductive fluid, such as isotonic saline, is
delivered to the target site within the mouth to substantially
surround the electrode terminal(s) with the fluid. The fluid may be
delivered through an instrument to the specific target site, or the
entire target region may be filled with conductive fluid such that
the electrode terminal(s) are submerged during the procedure. In
both embodiments, high frequency voltage is applied between the
electrode terminal(s) and one or more return electrode(s) to
volumetrically remove or ablate at least a portion of the
obstructive tissue in situ. The high frequency voltage may also be
selected to effect a controlled depth of hemostasis of severed
blood vessels within the tissue, which greatly improves the
surgeon's view of the surgical site during the procedure.
[0011] In a specific configuration, the obstructive tissue is
removed by molecular dissociation or disintegration processes. In
these embodiments, the high frequency voltage applied to the
electrode terminal(s) is sufficient to vaporize an electrically
conductive fluid (e.g., gel or saline) between the electrode
terminal(s) and the tissue. Within the vaporized fluid, a ionized
plasma is formed and charged particles (e.g., electrons) are
accelerated towards the tissue to cause the molecular breakdown or
disintegration of several cell layers of the tissue. This molecular
dissociation is accompanied by the volumetric removal of the
tissue. The short range of the accelerated charged particles within
the plasma layer confines the molecular dissociation process to the
surface layer to minimize damage and necrosis to the underlying
tissue. This process can be precisely controlled to effect the
volumetric removal of tissue as thin as 10 to 150 microns with
minimal heating of, or damage to, surrounding or underlying tissue
structures. A more complete description of this phenomena is
described in commonly assigned U.S. Pat. No. 5,683,366, the
complete disclosure of which is incorporated herein by
reference.
[0012] The present invention offers a number of advantages over
scalpels, conventional RF devices or lasers for gross tissue
removal and the treatment of obstructive sleep disorders. The
ability to precisely control the volumetric removal of tissue
results in a field of tissue ablation or removal that is very
defined, consistent and predictable. The shallow depth of tissue
heating also helps to minimize or completely eliminate damage to
healthy tissue structures, cartilage, bone and/or cranial nerves
that are often adjacent the target sinus tissue. In addition, small
blood vessels within the tissue are simultaneously cauterized and
sealed as the tissue is removed to continuously maintain hemostasis
during the procedure. This increases the surgeon's field of view,
and shortens the length of the procedure. Moreover, since the
present invention allows for the use of electrically conductive
fluid (contrary to prior art bipolar and monopolar electrosurgery
techniques), isotonic saline may be used during the procedure.
Saline is the preferred medium for irrigation because it has the
same concentration as the body's fluids and, therefore, is not
absorbed into the body as much as other fluids.
[0013] Moreover, applicant has found that the relative low
temperature processes of the present invention result in
substantially decreased operative and post-operative pain and
faster healing times than conventional techniques (i.e., scalpel,
laser and conventional RF devices). Typically, such conventional
devices generate extreme pain that may last for one to two weeks
after the operation, and is exacerbated by the constant exposure of
the patient's mouth to air, food, liquids, etc. The present
invention, by contrast, results in substantially less pain both
during and after the operation, as is evident by patient feedback
and feedback from the surgical team. In addition, the present
invention has resulted in increased healing rates for patient's
undergoing such procedures as UPPP's, tonsillectomies and other
gross tissue removal within the mouth and throat.
[0014] Apparatus according to the present invention generally
include an electrosurgical instrument having a shaft with proximal
and distal ends, an electrode assembly at the distal end and one or
more connectors coupling the electrode assembly to a source of high
frequency electrical energy. The electrode assembly includes one or
more electrode terminal(s) configured for tissue ablation and/or
tissue cutting and coagulation, and one or more return electrode(s)
typically spaced from the electrode terminal(s) on the instrument
shaft. The apparatus will preferably further include a fluid
delivery element for delivering electrically conducting fluid to
the electrode terminal(s) and the target site. The fluid delivery
element may be located on the instrument, e.g., a fluid lumen or
tube, or it may be part of a separate instrument. Alternatively, an
electrically conducting gel or spray, such as a saline electrolyte
or other conductive gel, may be applied the target site. In this
embodiment, the apparatus may not have a fluid delivery element. In
both embodiments, the electrically conducting fluid will preferably
generate a current flow path between the electrode terminal(s) and
the return electrode(s). In an exemplary embodiment, the return
electrode(s) are spaced a sufficient distance from the electrode
terminal(s) to substantially avoid or minimize current shorting
therebetween and to shield the return electrode(s) from tissue at
the target site.
[0015] In a specific configuration, the electrosurgical instrument
will include an electrically insulating electrode support member
having a tissue treatment surface at the distal end of the probe.
One or more electrode terminal(s) are coupled to, or integral with,
the electrode support member such that the electrode terminal(s)
are spaced from the return electrode. In one embodiment, the
electrode assembly includes an electrode array having a plurality
of electrically isolated electrode terminals embedded into the
electrode support member such that the electrode terminals extend
about 0.2 mm to about 10 mm distally from the tissue treatment
surface of the electrode support member. In this embodiment, the
instrument further includes one or more lumens for delivering
electrically conductive fluid to one or more openings around the
tissue treatment surface of the electrode support member. In an
exemplary embodiment, the lumen extends through a fluid tube
exterior to the instrument shaft that ends proximal to the return
electrode.
[0016] In one embodiment, the electrode terminal(s) are designed
for cutting tissue, i.e., they typically have a distal edge or
point, and they are aligned with each other to form a linear
cutting path through the tissue. For some applications, such as
tonsillectomies or UPPP's that involve tonsil removal, the target
tissue is extremely vascular and prone to excessive bleeding that
is often difficult to control during the procedure. According to
the present invention, in some embodiments, the electrode assembly
will have sufficient surface area to effectively coagulate and seal
the severed blood vessels within the target tissue. In an exemplary
embodiment, the electrode assembly comprises one or more loop
electrodes aligned with each other, and having a distal edge for
cutting along a substantially linear cutting path. The loop
configuration of the electrode terminals provides additional
exposed surface area for coagulation of severed blood vessels after
the tissue has been removed. In a specific configuration, the
electrode assembly comprises a pair of outer electrode terminals
and an inner loop electrode aligned with each other to form a
linear cutting path. The outer electrode terminals have a
relatively small distal end region that forms an effective cutting
configuration, while the inner loop electrode provides sufficient
exposed surface area for effective coagulation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of an electrosurgical system
incorporating a power supply and an electrosurgical probe for
tissue ablation, resection, incision, contraction and for vessel
hemostasis according to the present invention;
[0018] FIG. 2 is a side view of an electrosurgical probe according
to the present invention;
[0019] FIG. 3 is an end view of the probe of FIG. 2;
[0020] FIG. 4 is a cross sectional view of the electrosurgical
probe of FIG. 1;
[0021] FIG. 5 is an exploded view of a proximal portion of the
electrosurgical probe;
[0022] FIGS. 6A and 6B are perspective and end views, respectively,
of an alternative electrosurgical probe incorporating an inner
fluid lumen;
[0023] FIGS. 7A-7C are cross-sectional views of the distal portions
of three different embodiments of an electrosurgical probe
according to the present invention;
[0024] FIGS. 8A and 8B are cross-sectional and end views,
respectively, of yet another electrosurgical probe incorporating
flattened electrode terminals;
[0025] FIG. 9 illustrates an electrosurgical probe with a
90.degree. distal bend and a lateral fluid lumen;
[0026] FIG. 10 illustrates an electrosurgical system with a
separate fluid delivery instrument according to the present
invention;
[0027] FIG. 11 illustrates an endoscopic sinus surgery procedure,
wherein an endoscope is delivered through a nasal passage to view a
surgical site within the nasal cavity of the patient;
[0028] FIG. 12 illustrates an endoscopic sinus surgery procedure
with one of the probes described above according to the present
invention,
[0029] FIGS. 13A and 13B illustrate a detailed view of the sinus
surgery procedure, illustrating ablation of tissue according to the
present invention;
[0030] FIG. 14 illustrates a procedure for treating obstructive
sleep disorders, such as sleep apnea, according to the present
invention;
[0031] FIG. 15 illustrates a catheter system for electrosurgical
treatment of body structures within the head and neck according to
the present invention;
[0032] FIG. 16 is a cross-section view of a working end of a
catheter according to one embodiment of the present invention;
[0033] FIG. 17A is a cross-section view of a working end of a
catheter according to a second embodiment of the present
invention;
[0034] FIG. 17B is an end view of the catheter of FIG. 17A;
[0035] FIG. 18 is a sagittal section of a patient's head
illustrating a method of removing tissue from body lumens within a
patient's nose according to the present invention;
[0036] FIG. 19 is a coronal section of a patient's head
illustrating the paranasal sinuses;
[0037] FIG. 20 is a detailed end view of an electrosurgical probe
having an elongate, linear array of electrode terminals suitable
for use in surgical cutting;
[0038] FIG. 21 is a detailed view of a single electrode terminal
having a flattened end at its distal tip;
[0039] FIG. 22 is a detailed view of a single electrode terminal
having a pointed end at its distal tip;
[0040] FIG. 23 is a perspective view of another embodiment of an
electrosurgical probe for use in dermatology procedures;
[0041] FIG. 24 is an end view of the distal tip of the probe,
illustrating an electrode support with a plurality of electrode
terminals;
[0042] FIG. 25 illustrates the electrical connections and the
electrode support of the handpiece in greater detail;
[0043] FIG. 26 is a perspective view of the distal portion of
another electrosurgical probe according to the present invention
and
[0044] FIGS. 27 and 28 are partial cross-sectional views of a
distal portion of electrosurgical probes designed for cutting and
coagulation of tissue.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0045] The present invention provides systems and methods for
selectively applying electrical energy to a target location within
or on a patient's body, particularly including tissue in head and
neck, such as the ear, mouth, pharynx, larynx, esophagus, nasal
cavity and sinuses. These procedures may be performed through the
mouth or nose using speculae or gags, or using endoscopic
techniques, such as functional endoscopic sinus surgery (FESS).
These procedures may include the removal of swollen tissue,
chronically-diseased inflamed and hypertrophic mucus linings,
polyps and/or neoplasms from the various anatomical sinuses of the
skull, the turbinates and nasal passages, in the tonsil, adenoid,
epi-glottic and supra-glottic regions, and salivary glands,
submucus resection of the nasal septum, excision of diseased tissue
and the like. The present invention may also be useful for cosmetic
and plastic surgery procedures in the head and neck. For example,
the present invention is particularly useful for ablation and
sculpting of cartilage tissue, such as the cartilage within the
nose that is sculpted during rhinoplasty procedures. The present
invention may also be employed for skin tissue removal and/or
collagen shrinkage in the epidermis or dermis tissue in the head
and neck, e.g., the removal of pigmentations, vascular lesions
(e.g., leg veins), scars, tattoos, etc., and for other surgical
procedures on the skin, such as tissue rejuvenation, cosmetic eye
procedures (blepharoplasties), wrinkle removal, tightening muscles
for facelifts or browlifts, hair removal and/or transplant
procedures, etc.
[0046] In particular, the present invention is useful for cutting,
resection, ablation and/or hemostasis of tissue in procedures for
treating snoring and obstructive sleep apnea (e.g., UPPP and LAUP
procedures), for gross tissue removal, such as tonsillectomies,
adenoidectomies, tracheal stenosis and vocal cord polyps and
lesions, or for the resection or ablation of facial tumors or
tumors within the mouth and pharynx, such as glossectomies,
laryngectomies, acoustic neuroma procedures and nasal ablation
procedures. For convenience, the remaining disclosure will be
directed specifically to the treatment of sleep obstructive
disorders, but it will be appreciated that the system and method
can be applied equally well to procedures involving other tissues
of the body, as well as to other procedures including open
procedures, intravascular procedures, urology, laparascopy,
arthroscopy, thoracoscopy or other cardiac procedures, cosmetic
surgery, orthopedics, gynecology, otorhinolaryngology, spinal and
neurologic procedures, oncology and the like.
[0047] In some embodiments of the present invention, high frequency
(RF) electrical energy is applied to one or more electrode
terminals in the presence of electrically conductive fluid to
remove and/or modify the structure of tissue structures. Depending
on the specific procedure, the present invention may be used to:
(1) volumetrically remove tissue or cartilage (i.e., ablate or
effect molecular dissociation of the tissue structure); (2) cut or
resect tissue; (3) shrink or contract collagen connective tissue;
and/or (4) coagulate severed blood vessels.
[0048] In one aspect of the invention, the obstructive tissue is
volumetrically removed or ablated. In this procedure, a high
frequency voltage difference is applied between one or more
electrode terminal(s) and one or more return electrode(s) to
develop high electric field intensities in the vicinity of the
target tissue. The high electric field intensities adjacent the
electrode terminal(s) lead to electric field induced molecular
breakdown of target tissue through molecular dissociation (rather
than thermal evaporation or carbonization). Applicant believes that
the tissue structure is volumetrically removed through molecular
disintegration of larger organic molecules into smaller molecules
and/or atoms, such as hydrogen, oxygen, oxides of carbon,
hydrocarbons and nitrogen compounds. This molecular disintegration
completely removes the tissue structure, as opposed to dehydrating
the tissue material by the removal of liquid within the cells of
the tissue, as is typically the case with electrosurgical
desiccation and vaporization.
[0049] The high electric field intensities may be generated by
applying a high frequency voltage that is sufficient to vaporize an
electrically conducting fluid over at least a portion of the
electrode terminal(s) in the region between the distal tip of the
electrode terminal(s) and the target tissue. The electrically
conductive fluid may be a liquid, such as isotonic saline or blood,
delivered to the target site, or a viscous fluid, such as a gel,
applied to the target site. Since the vapor layer or vaporized
region has a relatively high electrical impedance, it increases the
voltage differential between the electrode terminal tip and the
tissue and causes ionization within the vapor layer due to the
presence of an ionizable species (e.g., sodium when isotonic saline
is the electrically conducting fluid). This ionization, under
optimal conditions, induces the discharge of energetic electrons
and photons from the vapor layer and to the surface of the target
tissue. This energy may be in the form of energetic photons (e.g.,
ultraviolet radiation), energetic particles (e.g., electrons) or a
combination thereof. A more detailed description of this phenomena,
termed Coblation.TM. can be found in commonly assigned U.S. Pat.
No. 5,683,366 the complete disclosure of which is incorporated
herein by reference.
[0050] In some procedures, e.g., soft palate or tongue/pharynx
stiffening, it may be desired to shrink or contract collagen
connective tissue at the target site. In these procedures, the RF
energy heats the tissue directly by virtue of the electrical
current flow therethrough, and/or indirectly through the exposure
of the tissue to fluid heated by RF energy, to elevate the tissue
temperature from normal body temperatures (e.g., 37.degree. C.) to
temperatures in the range of 45.degree. C. to 90.degree. C.,
preferably in the range from about 60.degree. C. to 70.degree. C.
Thermal shrinkage of collagen fibers occurs within a small
temperature range which, for mammalian collagen is in the range
from 60.degree. C. to 70.degree. C. (Deak, G., et al., "The Thermal
Shrinkage Process of Collagen Fibres as Revealed by Polarization
Optical Analysis of Topooptical Staining Reactions," Acta
Morphologica Acad. Sci. of Hungary, Vol. 15(2), pp 195-208, 1967).
Collagen fibers typically undergo thermal shrinkage in the range of
60.degree. C. to about 70.degree. C. Previously reported research
has attributed thermal shrinkage of collagen to the cleaving of the
internal stabilizing cross-linkages within the collagen matrix
(Deak, ibid). It has also been reported that when the collagen
temperature is increased above 70.degree. C., the collagen matrix
begins to relax again and the shrinkage effect is reversed
resulting in no net shrinkage (Allain, J. C., et al., "Isometric
Tensions Developed During the Hydrothermal Swelling of Rat Skin,"
Connective Tissue Research, Vol. 7, pp 127-133, 1980).
Consequently, the controlled heating of tissue to a precise depth
is critical to the achievement of therapeutic collagen shrinkage. A
more detailed description of collagen shrinkage can be found in
U.S. patent application Ser. No. 08/942,580 filed on Oct. 2, 1997,
(Attorney Docket No. 16238-001300).
[0051] The preferred depth of heating to effect the shrinkage of
collagen in the heated region (i.e., the depth to which the tissue
is elevated to temperatures between 60.degree. C. to 70.degree. C.)
generally depends on (1) the thickness of the tissue, (2) the
location of nearby structures (e.g., nerves) that should not be
exposed to damaging temperatures, and/or (3) the location of the
collagen tissue layer within which therapeutic shrinkage is to be
effected. The depth of heating is usually in the range from 0 to
3.5 mm. In the case of collagen within the soft palate or uvula,
the depth of heating is preferably in the range from about 0.5 to
about 3.5 mm.
[0052] In other embodiments, the present invention applies high
frequency (RF) electrical energy in an electrically conducting
fluid environment to remove (i.e., resect, cut or ablate) a tissue
structure and to seal transected vessels within the region of the
target tissue. The present invention is particularly useful for
sealing larger arterial vessels, e.g., on the order of 1 mm or
greater. In some embodiments, a high frequency power supply is
provided having an ablation mode, wherein a first voltage is
applied to an electrode terminal sufficient to effect molecular
dissociation or disintegration of the tissue, and a coagulation
mode, wherein a second, lower voltage is applied to an electrode
terminal (either the same or a different electrode) sufficient to
achieve hemostasis of severed vessels within the tissue. In other
embodiments, an electrosurgical instrument is provided having one
or more coagulation electrode(s) configured for sealing a severed
vessel, such as an arterial vessel, and one or more electrode
terminals configured for either contracting the collagen fibers
within the tissue or removing (ablating) the tissue, e.g., by
applying sufficient energy to the tissue to effect molecular
dissociation. In the latter embodiments, the coagulation
electrode(s) may be configured such that a single voltage can be
applied to coagulate with the coagulation electrode(s), and to
ablate with the electrode terminal(s). In other embodiments, the
power supply is combined with the coagulation instrument such that
the coagulation electrode is used when the power supply is in the
coagulation mode (low voltage), and the electrode terminal(s) are
used when the power supply is in the ablation mode (higher
voltage).
[0053] In one method of the present invention, one or more
electrode terminals are brought into close proximity to tissue at a
target site, and the power supply is activated in the ablation mode
such that sufficient voltage is applied between the electrode
terminals and the return electrode to volumetrically remove the
tissue through molecular dissociation, as described below. During
this process, vessels within the tissue will be severed. Smaller
vessels will be automatically sealed with the system and method of
the present invention. Larger vessels, and those with a higher flow
rate, such as arterial vessels, may not be automatically sealed in
the ablation mode. In these cases, the severed vessels may be
sealed by activating a control (e.g., a foot pedal) to reduce the
voltage of the power supply into the coagulation mode. In this
mode, the electrode terminals may be pressed against the severed
vessel to provide sealing and/or coagulation of the vessel.
Alternatively, a coagulation electrode located on the same or a
different instrument may be pressed against the severed vessel.
Once the vessel is adequately sealed, the surgeon activates a
control (e.g., another foot pedal) to increase the voltage of the
power supply back into the ablation mode.
[0054] The present invention is also useful for removing or
ablating tissue around nerves, such as spinal, or cranial nerves,
e.g., the hypoglossal nerve, the optic nerve, facial nerves,
vestibulocochlear nerves and the like. This is particularly
advantageous when removing tissue that is located close to nerves.
One of the significant drawbacks with the prior art RF devices,
scalpels and lasers is that these devices do not differentiate
between the target tissue and the surrounding nerves or bone.
Therefore, the surgeon must be extremely careful during these
procedures to avoid damage to the nerves within and around the
patient's mouth and throat. In the present invention, the
Coblation'process for removing tissue results in extremely small
depths of collateral tissue damage as discussed above. This allows
the surgeon to remove tissue close to a nerve without causing
collateral damage to the nerve fibers.
[0055] In addition to the generally precise nature of the novel
mechanisms of the present invention, applicant has discovered an
additional method of ensuring that adjacent nerves are not damaged
during tissue removal. According to the present invention, systems
and methods are provided for distinguishing between the fatty
tissue immediately surrounding nerve fibers and the normal tissue
that is to be removed during the procedure. Nerves usually comprise
a connective tissue sheath, or epineurium, enclosing the bundles of
nerve fibers, each bundle being surrounded by its own sheath of
connective tissue (the perineurium) to protect these nerve fibers.
The outer protective tissue sheath or epineurium typically
comprises a fatty tissue (e.g., adipose tissue) having
substantially different electrical properties than the normal
target tissue, such as the turbinates, polyps, mucus tissue or the
like, that are, for example, removed from the nose during sinus
procedures. The system of the present invention measures the
electrical properties of the tissue at the tip of the probe with
one or more electrode terminal(s). These electrical properties may
include electrical conductivity at one, several or a range of
frequencies (e.g., in the range from 1 kHz to 100 MHz), dielectric
constant, capacitance or combinations of these. In this embodiment,
an audible signal may be produced when the sensing electrode(s) at
the tip of the probe detects the fatty tissue surrounding a nerve,
or direct feedback control can be provided to only supply power to
the electrode terminal(s) either individually or to the complete
array of electrodes, if and when the tissue encountered at the tip
or working end of the probe is normal tissue based on the measured
electrical properties.
[0056] In one embodiment, the current limiting elements (discussed
in detail above) are configured such that the electrode terminals
will shut down or turn off when the electrical impedance reaches a
threshold level. When this threshold level is set to the impedance
of the fatty tissue surrounding nerves, the electrode terminals
will shut off whenever they come in contact with, or in close
proximity to, nerves. Meanwhile, the other electrode terminals,
which are in contact with or in close proximity to nasal tissue,
will continue to conduct electric current to the return electrode.
This selective ablation or removal of lower impedance tissue in
combination with the Coblation.TM. mechanism of the present
invention allows the surgeon to precisely remove tissue around
nerves or bone. Applicant has found that the present invention is
capable of volumetrically removing tissue closely adjacent to
nerves without impairment the function of the nerves, and without
significantly damaging the tissue of the epineurium.
[0057] In addition to the above, applicant has discovered that the
Coblation.TM. mechanism of the present invention can be manipulated
to ablate or remove certain tissue structures, while having little
effect on other tissue structures. As discussed above, the present
invention uses a technique of vaporizing electrically conductive
fluid to form a plasma layer or pocket around the electrode
terminal(s), and then inducing the discharge of energy from this
plasma or vapor layer to break the molecular bonds of the tissue
structure. Based on initial experiments, applicants believe that
the free electrons within the ionized vapor layer are accelerated
in the high electric fields near the electrode tip(s). When the
density of the vapor layer (or within a bubble formed in the
electrically conducting liquid) becomes sufficiently low (i.e.,
less than approximately 10.sup.20 atoms/cm.sup.3 for aqueous
solutions), the electron mean free path increases to enable
subsequently injected electrons to cause impact ionization within
these regions of low density (i.e., vapor layers or bubbles).
Energy evolved by the energetic electrons (e.g., 4 to 5 eV) can
subsequently bombard a molecule and break its bonds, dissociating a
molecule into free radicals, which then combine into final gaseous
or liquid species.
[0058] The energy evolved by the energetic electrons may be varied
by adjusting a variety of factors, such as: the number of electrode
terminals; electrode size and spacing; electrode surface area;
asperities and sharp edges on the electrode surfaces; electrode
materials; applied voltage and power; current limiting means, such
as inductors; electrical conductivity of the fluid in contact with
the electrodes; density of the fluid; and other factors.
Accordingly, these factors can be manipulated to control the energy
level of the excited electrons. Since different tissue structures
have different molecular bonds, the present invention can be
configured to break the molecular bonds of certain tissue, while
having too low an energy to break the molecular bonds of other
tissue. For example, fatty tissue, (e.g., adipose) tissue has
double bonds that require a substantially higher energy level than
4 to 5 eV to break. Accordingly, the present invention in its
current configuration generally does not ablate or remove such
fatty tissue. Of course, factors may be changed such that these
double bonds can also be broken in a similar fashion as the single
bonds (e.g., increasing voltage or changing the electrode
configuration to increase the current density at the electrode
tips). A more complete description of this phenomena can be found
in co-pending U.S. patent application Ser. No. 09/032,375, filed
Feb. 27, 1998 (Attorney Docket No. CB-3), the complete disclosure
of which is incorporated herein by reference.
[0059] The present invention also provides systems, apparatus and
methods for selectively removing tumors or other undesirable body
structures while minimizing the spread of viable cells from the
tumor. Conventional techniques for removing such tumors generally
result in the production of smoke in the surgical setting, termed
an electrosurgical or laser plume, which can spread intact, viable
bacterial or viral particles from the tumor or lesion to the
surgical team or to other portions of the patient's body. This
potential spread of viable cells or particles has resulted in
increased concerns over the proliferation of certain debilitating
and fatal diseases, such as hepatitis, herpes, HIV and
papillomavirus. In the present invention, high frequency voltage is
applied between the electrode terminal(s) and one or more return
electrode(s) to volumetrically remove at least a portion of the
tissue cells in the tumor through the dissociation or
disintegration of organic molecules into non-viable atoms and
molecules. Specifically, the present invention converts the solid
tissue cells into non-condensable gases that are no longer intact
or viable, and thus, not capable of spreading viable tumor
particles to other portions of the patient's brain or to the
surgical staff. The high frequency voltage is preferably selected
to effect controlled removal of these tissue cells while minimizing
substantial tissue necrosis to surrounding or underlying tissue. A
more complete description of this phenomena can be found in
co-pending U.S. patent application Ser. No. 09/109,219, filed Jun.
30, 1998 (Attorney Docket No. CB-1), the complete disclosure of
which is incorporated herein by reference
[0060] The electrosurgical instrument will comprise a shaft or a
handpiece having a proximal end and a distal end which supports one
or more electrode terminal(s). The shaft or handpiece may assume a
wide variety of configurations, with the primary purpose being to
mechanically support the active electrode and permit the treating
physician to manipulate the electrode from a proximal end of the
shaft. The shaft may be rigid or flexible, with flexible shafts
optionally being combined with a generally rigid external tube for
mechanical support. Flexible shafts may be combined with pull
wires, shape memory actuators, and other known mechanisms for
effecting selective deflection of the distal end of the shaft to
facilitate positioning of the electrode array. The shaft will
usually include a plurality of wires or other conductive elements
running axially therethrough to permit connection of the electrode
array to a connector at the proximal end of the shaft.
[0061] For procedures within the nose, the shaft will have a
suitable diameter and length to allow the surgeon to reach the
target site (e.g., a blockage in the nasal cavity or one of the
sinuses) by delivering the probe shaft through one of the nasal
passages or another opening (e.g., an opening in the eye or through
an opening surgically creating during the procedure). Thus, the
shaft will usually have a length in the range of about 5-25 cm, and
a diameter in the range of about 0.5 to 5 mm. For procedures in the
small passages of the nose, the shaft diameter will usually be less
than 3 mm, preferably less than about 0.5 mm. Likewise, for
procedures in the ear, the shaft should have a length in the range
of about 3 to 20 cm, and a diameter of about 0.3 to 5 mm. For
procedures in the mouth or upper throat, the shaft will have any
suitable length and diameter that would facilitate handling by the
surgeon. For procedures in the lower throat, such as
laryngectomies, the shaft will be suitably designed to access the
larynx. For example, the shaft may be flexible, or have a distal
bend to accommodate the bend in the patient's throat. In this
regard, the shaft may be a rigid shaft having a specifically
designed bend to correspond with the geometry of the mouth and
throat, or it may have a flexible distal end, or it may be part of
a catheter. In any of these embodiments, the shaft may also be
introduced through rigid or flexible endoscopes. Specific shaft
designs will be described in detail in connection with the figures
hereinafter.
[0062] The electrode terminal(s) are preferably supported within or
by an inorganic insulating support positioned near the distal end
of the instrument shaft. The return electrode may be located on the
instrument shaft, on another instrument or on the external surface
of the patient (i.e., a dispersive pad). The close proximity of
nerves and other sensitive tissue in the mouth and throat, however,
makes a bipolar design more preferable because this minimizes the
current flow through non-target tissue and surrounding nerves.
Accordingly, the return electrode is preferably either integrated
with the instrument body, or another instrument located in close
proximity thereto. The proximal end of the instrument(s) will
include the appropriate electrical connections for coupling the
return electrode(s) and the electrode terminal(s) to a high
frequency power supply, such as an electrosurgical generator.
[0063] The current flow path between the electrode terminal(s) and
the return electrode(s) may be generated by submerging the tissue
site in an electrical conducting fluid (e.g., within a viscous
fluid, such as an electrically conductive gel) or by directing an
electrically conducting fluid along a fluid path to the target site
(i.e., a liquid, such as isotonic saline, or a gas, such as argon).
The conductive gel may also be delivered to the target site to
achieve a slower, more controlled delivery rate of conductive
fluid. In addition, the viscous nature of the gel may allow the
surgeon to more easily contain the gel around the target site
(e.g., rather than attempting to contain isotonic saline). A more
complete description of an exemplary method of directing
electrically conducting fluid between the active and return
electrodes is described in U.S. Pat. No. 5,697,281, previously
incorporated herein by reference. Alternatively, the body's natural
conductive fluids, such as blood, may be sufficient to establish a
conductive path between the return electrode(s) and the electrode
terminal(s), and to provide the conditions for establishing a vapor
layer, as described above. However, conductive fluid that is
introduced into the patient is generally preferred over blood
because blood will tend to coagulate at certain temperatures.
Advantageously, a liquid electrically conductive fluid (e.g.,
isotonic saline) may be used to concurrently "bathe" the target
tissue surface to provide an additional means for removing any
tissue, and to cool the region of the target tissue ablated in the
previous moment.
[0064] The power supply may include a fluid interlock for
interrupting power to the electrode terminal(s) when there is
insufficient conductive fluid around the electrode terminal(s).
This ensures that the instrument will not be activated when
conductive fluid is not present, minimizing the tissue damage that
may otherwise occur. A more complete description of such a fluid
interlock can be found in commonly assigned, co-pending U.S.
application Ser. No. 09/058,336, filed Apr. 10, 1998 (attorney
Docket No. CB-4), the complete disclosure of which is incorporated
herein by reference.
[0065] In some procedures, it may also be necessary to retrieve or
aspirate the electrically conductive fluid and/or the
non-condensable gaseous products of ablation. In addition, it may
be desirable to aspirate small pieces of tissue or other body
structures that are not completely disintegrated by the high
frequency energy, or other fluids at the target site, such as
blood, mucus, the gaseous products of ablation, etc. Accordingly,
the system of the present invention may include one or more suction
lumen(s) in the instrument, or on another instrument, coupled to a
suitable vacuum source for aspirating fluids from the target site.
In addition, the invention may include one or more aspiration
electrode(s) coupled to the distal end of the suction lumen for
ablating, or at least reducing the volume of, non-ablated tissue
fragments that are aspirated into the lumen. The aspiration
electrode(s) function mainly to inhibit clogging of the lumen that
may otherwise occur as larger tissue fragments are drawn therein.
The aspiration electrode(s) may be different from the ablation
electrode terminal(s), or the same electrode(s) may serve both
functions. A more complete description of instruments incorporating
aspiration electrode(s) can be found in commonly assigned,
co-pending patent application entitled "Systems And Methods For
Tissue Resection, Ablation And Aspiration", filed Jan. 21, 1998,
the complete disclosure of which is incorporated herein by
reference.
[0066] As an alternative or in addition to suction, it may be
desirable to contain the excess electrically conductive fluid,
tissue fragments and/or gaseous products of ablation at or near the
target site with a containment apparatus, such as a basket,
retractable sheath or the like. This embodiment has the advantage
of ensuring that the conductive fluid, tissue fragments or ablation
products do not flow through the patient's vasculature or into
other portions of the body. In addition, it may be desirable to
limit the amount of suction to limit the undesirable effect suction
may have on hemostasis of severed blood vessels.
[0067] The present invention may use a single active electrode
terminal or an array of electrode terminals spaced around the
distal surface of a catheter or probe. In the latter embodiment,
the electrode array usually includes a plurality of independently
current-limited and/or power-controlled electrode terminals to
apply electrical energy selectively to the target tissue while
limiting the unwanted application of electrical energy to the
surrounding tissue and environment resulting from power dissipation
into surrounding electrically conductive fluids, such as blood,
normal saline, and the like. The electrode terminals may be
independently current-limited by isolating the terminals from each
other and connecting each terminal to a separate power source that
is isolated from the other electrode terminals. Alternatively, the
electrode terminals may be connected to each other at either the
proximal or distal ends of the catheter to form a single wire that
couples to a power source.
[0068] In one configuration, each individual electrode terminal in
the electrode array is electrically insulated from all other
electrode terminals in the array within said instrument and is
connected to a power source which is isolated from each of the
other electrode terminals in the array or to circuitry which limits
or interrupts current flow to the electrode terminal when low
resistivity material (e.g., blood, electrically conductive saline
irrigant or electrically conductive gel) causes a lower impedance
path between the return electrode and the individual electrode
terminal. The isolated power sources for each individual electrode
terminal may be separate power supply circuits having internal
impedance characteristics which limit power to the associated
electrode terminal when a low impedance return path is encountered.
By way of example, the isolated power source may be a user
selectable constant current source. In this embodiment, lower
impedance paths will automatically result in lower resistive
heating levels since the heating is proportional to the square of
the operating current times the impedance. Alternatively, a single
power source may be connected to each of the electrode terminals
through independently actuatable switches, or by independent
current limiting elements, such as inductors, capacitors, resistors
and/or combinations thereof. The current limiting elements may be
provided in the instrument, connectors, cable, controller or along
the conductive path from the controller to the distal tip of the
instrument. Alternatively, the resistance and/or capacitance may
occur on the surface of the active electrode terminal(s) due to
oxide layers which form selected electrode terminals (e.g.,
titanium or a resistive coating on the surface of metal, such as
platinum).
[0069] The tip region of the instrument may comprise many
independent electrode terminals designed to deliver electrical
energy in the vicinity of the tip. The selective application of
electrical energy to the conductive fluid is achieved by connecting
each individual electrode terminal and the return electrode to a
power source having independently controlled or current limited
channels. The return electrode(s) may comprise a single tubular
member of conductive material proximal to the electrode array at
the tip which also serves as a conduit for the supply of the
electrically conducting fluid between the active and return
electrodes. Alternatively, the instrument may comprise an array of
return electrodes at the distal tip of the instrument (together
with the active electrodes) to maintain the electric current at the
tip. The application of high frequency voltage between the return
electrode(s) and the electrode array results in the generation of
high electric field intensities at the distal tips of the electrode
terminals with conduction of high frequency current from each
individual electrode terminal to the return electrode. The current
flow from each individual electrode terminal to the return
electrode(s) is controlled by either active or passive means, or a
combination thereof, to deliver electrical energy to the
surrounding conductive fluid while minimizing energy delivery to
surrounding (non-target) tissue.
[0070] The application of a high frequency voltage between the
return electrode(s) and the electrode terminal(s) for appropriate
time intervals effects cutting, removing, ablating, shaping,
contracting or otherwise modifying the target tissue. The tissue
volume over which energy is dissipated (i.e., a high current
density exists) may be precisely controlled, for example, by the
use of a multiplicity of small electrode terminals whose effective
diameters or principal dimensions range from about 10 mm to 0.01
mm, preferably from about 2 mm to 0.05 mm, and more preferably from
about 1 mm to 0.1 mm. Electrode areas for both circular and
non-circular terminals will have a contact area (per electrode
terminal) below 50 mm.sup.2 for electrode arrays and as large as 75
mm.sup.2 for single electrode embodiments, preferably being in the
range from 0.0001 mm.sup.2 to 1 mm.sup.2, and more preferably from
0.005 mm.sup.2 to 0.5 mm.sup.2. The circumscribed area of the
electrode array is in the range from 0.25 mm.sup.2 to 75 mm.sup.2,
preferably from 0.5 mm.sup.2 to 40 mm.sup.2, and will usually
include at least one electrode terminal and in some embodiments
includes at least two isolated electrode terminals, often at least
five electrode terminals, often greater than 10 electrode terminals
and even 50 or more electrode terminals, disposed over the distal
contact surfaces on the shaft. The use of small diameter electrode
terminals increases the electric field intensity and reduces the
extent or depth of tissue heating as a consequence of the
divergence of current flux lines which emanate from the exposed
surface of each electrode terminal.
[0071] The area of the tissue treatment surface can vary widely,
and the tissue treatment surface can assume a variety of
geometries, with particular areas and geometries being selected for
specific applications. The active electrode surface(s) can have
area(s) in the range from 0.25 mm.sup.2 to 75 mm.sup.2, usually
being from about 0.5 mm.sup.2 to 40 mm.sup.2. The geometries can be
planar, concave, convex, hemispherical, conical, linear "in-line"
array or virtually any other regular or irregular shape. Most
commonly, the active electrode(s) or electrode terminal(s) will be
formed at the distal tip of the electrosurgical instrument shaft,
frequently being planar, disk-shaped, or hemispherical surfaces for
use in reshaping procedures or being linear arrays for use in
cutting. Alternatively or additionally, the active electrode(s) may
be formed on lateral surfaces of the electrosurgical instrument
shaft (e.g., in the manner of a spatula), facilitating access to
certain body structures in endoscopic procedures.
[0072] In some embodiments, the electrode support and the fluid
outlet may be recessed from an outer surface of the instrument or
handpiece to confine the electrically conductive fluid to the
region immediately surrounding the electrode support. In addition,
the shaft may be shaped so as to form a cavity around the electrode
support and the fluid outlet. This helps to assure that the
electrically conductive fluid will remain in contact with the
electrode terminal(s) and the return electrode(s) to maintain the
conductive path therebetween. In addition, this will help to
maintain a vapor layer and subsequent plasma layer between the
electrode terminal(s) and the tissue at the treatment site
throughout the procedure, which reduces the thermal damage that
might otherwise occur if the vapor layer were extinguished due to a
lack of conductive fluid. Provision of the electrically conductive
fluid around the target site also helps to maintain the tissue
temperature at desired levels.
[0073] The electrically conducting fluid should have a threshold
conductivity to provide a suitable conductive path between the
return electrode and the electrode terminal(s). The electrical
conductivity of the fluid (in units of milliSiemans per centimeter
or mS/cm) will usually be greater than 0.2 mS/cm, preferably will
be greater than 2 mS/cm and more preferably greater than 10 mS/cm.
In an exemplary embodiment, the electrically conductive fluid is
isotonic saline, which has a conductivity of about 17 mS/cm.
[0074] The voltage difference applied between the return
electrode(s) and the electrode terminal(s) will be at high or radio
frequency, typically between about 5 kHz and 20 MHz, usually being
between about 30 kHz and 2.5 MHz, preferably being between about 50
kHz and 500 kHz, often less than 350 kHz, and often between about
100 kHz and 200 kHz. The RMS (root mean square) voltage applied
will usually be in the range from about 5 volts to 1000 volts,
preferably being in the range from about 10 volts to 500 volts
depending on the electrode terminal size, the operating frequency
and the operation mode of the particular procedure or desired
effect on the tissue (i.e., contraction, coagulation, cutting or
ablation). Typically, the peak-to-peak voltage for ablation or
cutting will be in the range of 10 to 2000 volts and preferably in
the range of 200 to 1800 volts and more preferably in the range of
about 300 to 1500 volts, often in the range of about 500 to 900
volts peak to peak (again, depending on the electrode size, the
operating frequency and the operation mode). Lower peak-to-peak
voltages will be used for tissue coagulation or collagen
contraction and will typically be in the range from 50 to 1500,
preferably 100 to 1000 and more preferably 120 to 600 volts
peak-to-peak.
[0075] As discussed above, the voltage is usually delivered in a
series of voltage pulses or alternating current of time varying
voltage amplitude with a sufficiently high frequency (e.g., on the
order of 5 kHz to 20 MHz) such that the voltage is effectively
applied continuously (as compared with e.g., lasers claiming small
depths of necrosis, which are generally pulsed about 10 to 20 Hz).
In addition, the duty cycle (i.e., cumulative time in any
one-second interval that energy is applied) is on the order of
about 50% for the present invention, as compared with pulsed lasers
which typically have a duty cycle of about 0.0001%.
[0076] The preferred power source of the present invention delivers
a high frequency current selectable to generate average power
levels ranging from several milliwatts to tens of watts per
electrode, depending on the volume of target tissue being heated,
and/or the maximum allowed temperature selected for the instrument
tip. The power source allows the user to select the voltage level
according to the specific requirements of a particular neurosurgery
procedure, cardiac surgery, arthroscopic surgery, dermatological
procedure, ophthalmic procedures, open surgery or other endoscopic
surgery procedure. For cardiac procedures and potentially for
neurosurgery, the power source may have an additional filter, for
filtering leakage voltages at frequencies below 100 kHz,
particularly voltages around 60 kHz. Alternatively, a power source
having a higher operating frequency, e.g., 300 to 500 kHz may be
used in certain procedures in which stray low frequency currents
may be problematic. A description of one suitable power source can
be found in co-pending patent applications Ser. No. 09/058,571 and
Ser. No. 09/058,336, filed Apr. 10, 1998 (Attorney Docket Nos. CB-2
and CB-4), the complete disclosure of both applications are
incorporated herein by reference for all purposes.
[0077] The power source may be current limited or otherwise
controlled so that undesired heating of the target tissue or
surrounding (non-target) tissue does not occur. In a presently
preferred embodiment of the present invention, current limiting
inductors are placed in series with each independent electrode
terminal, where the inductance of the inductor is in the range of
10 uH to 50,000 uH, depending on the electrical properties of the
target tissue, the desired tissue heating rate and the operating
frequency. Alternatively, capacitor-inductor (LC) circuit
structures may be employed, as described previously in U.S. Pat.
No. 5,697,909, the complete disclosure of which is incorporated
herein by reference. Additionally, current limiting resistors may
be selected. Preferably, these resistors will have a large positive
temperature coefficient of resistance so that, as the current level
begins to rise for any individual electrode terminal in contact
with a low resistance medium (e.g., saline irrigant or blood), the
resistance of the current limiting resistor increases
significantly, thereby minimizing the power delivery from said
electrode terminal into the low resistance medium (e.g., saline
irrigant or blood).
[0078] It should be clearly understood that the invention is not
limited to electrically isolated electrode terminals, or even to a
plurality of electrode terminals. For example, the array of active
electrode terminals may be connected to a single lead that extends
through the catheter shaft to a power source of high frequency
current. Alternatively, the instrument may incorporate a single
electrode that extends directly through the catheter shaft or is
connected to a single lead that extends to the power source. The
active electrode(s) may have ball shapes (e.g., for tissue
vaporization and desiccation), twizzle shapes (for vaporization and
needle-like cutting), spring shapes (for rapid tissue debulking and
desiccation), twisted metal shapes, annular or solid tube shapes or
the like. Alternatively, the electrode(s) may comprise a plurality
of filaments, rigid or flexible brush electrode(s) (for debulking a
tumor, such as a fibroid, bladder tumor or a prostate adenoma),
side-effect brush electrode(s) on a lateral surface of the shaft,
coiled electrode(s) or the like.
[0079] In one embodiment, an electrosurgical catheter or probe
comprises a single active electrode terminal that extends from an
insulating member, e.g., ceramic, at the distal end of the shaft.
The insulating member is preferably a tubular structure that
separates the active electrode terminal from a tubular or annular
return electrode positioned proximal to the insulating member and
the active electrode. In another embodiment, the catheter or probe
includes a single active electrode that can be rotated relative to
the rest of the catheter body, or the entire catheter may be
rotated related to the lead. The single active electrode can be
positioned adjacent the abnormal tissue and energized and rotated
as appropriate to remove this tissue.
[0080] The current flow path between the electrode terminal(s) and
the return electrode(s) may be generated by submerging the tissue
site in an electrical conducting fluid (e.g., within a viscous
fluid, such as an electrically conductive gel) or by directing an
electrically conducting fluid along a fluid path to the target site
(i.e., a liquid, such as isotonic saline, or a gas, such as argon).
This latter method is particularly effective in a dry environment
(i.e., the tissue is not submerged in fluid) because the
electrically conducting fluid provides a suitable current flow path
from the electrode terminal to the return electrode.
[0081] Referring to FIG. 1, an exemplary electrosurgical system 11
for treatment of tissue in the head and neck will now be described
in detail. Electrosurgical system 11 generally comprises an
electrosurgical handpiece or probe 10 connected to a power supply
28 for providing high frequency voltage to a target site and a
fluid source 21 for supplying electrically conducting fluid 50 to
probe 10. In addition, electrosurgical system 11 may include an
endoscope (not shown) with a fiber optic head light for viewing the
surgical site, particularly in sinus procedures or procedures in
the ear or the back of the mouth. The endoscope may be integral
with probe 10, or it may be part of a separate instrument. The
system 11 may also include a vacuum source (not shown) for coupling
to a suction lumen or tube 205 (see FIG. 2) in the probe 10 for
aspirating the target site.
[0082] As shown, probe 10 generally includes a proximal handle 19
and an elongate shaft 18 having an array 12 of electrode terminals
58 at its distal end. A connecting cable 34 has a connector 26 for
electrically coupling the electrode terminals 58 to power supply
28. The electrode terminals 58 are electrically isolated from each
other and each of the terminals 58 is connected to an active or
passive control network within power supply 28 by means of a
plurality of individually insulated conductors (not shown). A fluid
supply tube 15 is connected to a fluid tube 14 of probe 10 for
supplying electrically conducting fluid 50 to the target site.
Fluid supply tube 15 may be connected to a suitable pump (not
shown), if desired.
[0083] Power supply 28 has an operator controllable voltage level
adjustment 30 to change the applied voltage level, which is
observable at a voltage level display 32. Power supply 28 also
includes first, second and third foot pedals 37, 38, 39 and a cable
36 which is removably coupled to power supply 28. The foot pedals
37, 38, 39 allow the surgeon to remotely adjust the energy level
applied to electrode terminals 58. In an exemplary embodiment,
first foot pedal 37 is used to place the power supply into the
"ablation" mode and second foot pedal 38 places power supply 28
into the "sub-ablation" mode (e.g., coagulation or contraction of
tissue). The third foot pedal 39 allows the user to adjust the
voltage level within the "ablation" mode. In the ablation mode, a
sufficient voltage is applied to the electrode terminals to
establish the requisite conditions for molecular dissociation of
the tissue (i.e., vaporizing a portion of the electrically
conductive fluid, ionizing charged particles within the vapor layer
and accelerating these charged particles against the tissue). As
discussed above, the requisite voltage level for ablation will vary
depending on the number, size, shape and spacing of the electrodes,
the distance in which the electrodes extend from the support
member, etc. Once the surgeon places the power supply in the
"ablation" mode, voltage level adjustment 30 or third foot pedal 39
may be used to adjust the voltage level to adjust the degree or
aggressiveness of the ablation.
[0084] Of course, it will be recognized that the voltage and
modality of the power supply may be controlled by other input
devices. However, applicant has found that foot pedals are
convenient methods of controlling the power supply while
manipulating the probe during a surgical procedure.
[0085] In the subablation mode, the power supply 28 applies a low
enough voltage to the electrode terminals to avoid vaporization of
the electrically conductive fluid and subsequent molecular
dissociation of the tissue. The surgeon may automatically toggle
the power supply between the ablation and sub-ablation modes by
alternatively stepping on foot pedals 37, 38, respectively. In some
embodiments, this allows the surgeon to quickly move between
coagulation and ablation in situ, without having to remove his/her
concentration from the surgical field or without having to request
an assistant to switch the power supply. By way of example, as the
surgeon is sculpting soft tissue in the ablation mode, the probe
typically will simultaneously seal and/or coagulation small severed
vessels within the tissue. However, larger vessels, or vessels with
high fluid pressures (e.g., arterial vessels) may not be sealed in
the ablation mode. Accordingly, the surgeon can simply step on foot
pedal 38, automatically lowering the voltage level below the
threshold level for ablation, and apply sufficient pressure onto
the severed vessel for a sufficient period of time to seal and/or
coagulate the vessel. After this is completed, the surgeon may
quickly move back into the ablation mode by stepping on foot pedal
37. A specific design of a suitable power supply for use with the
present invention can be found in U.S. Provisional Patent
Application 60/062,997, filed Oct. 23, 1997 (attorney docket no.
16238-007400), previously incorporated herein by reference.
[0086] FIGS. 2-5 illustrate an exemplary electrosurgical probe 90
constructed according to the principles of the present invention.
As shown in FIG. 2, probe 90 generally includes an elongated shaft
100 which may be flexible or rigid, a handle 204 coupled to the
proximal end of shaft 100 and an electrode support member 102
coupled to the distal end of shaft 100. Shaft 100 preferably
includes a bend 101 that allows the distal section of shaft 100 to
be offset from the proximal section and handle 204. This offset
facilitates procedures that require an endoscope, such as FESS,
because the endoscope can, for example, be introduced through the
same nasal passage as the shaft 100 without interference between
handle 204 and the eyepiece of the endoscope (see FIG. 11). Shaft
100 preferably comprises a plastic material that is easily molded
into the shape shown in FIG. 1.
[0087] In an alternative embodiment (see FIG. 6A), shaft 100
comprises an electrically conducting material, usually metal, which
is selected from the group comprising tungsten, stainless steel
alloys, platinum or its alloys, titanium or its alloys, molybdenum
or its alloys, and nickel or its alloys. In this embodiment, shaft
100 includes an electrically insulating jacket 108, which is
typically formed as one or more electrically insulating sheaths or
coatings, such as polytetrafluoroethylene, polyimide, and the like.
The provision of the electrically insulating jacket over the shaft
prevents direct electrical contact between these metal elements and
any adjacent body structure or the surgeon. Such direct electrical
contact between a body structure (e.g., tendon) and an exposed
electrode could result in unwanted heating and necrosis of the
structure at the point of contact causing necrosis.
[0088] Handle 204 typically comprises a plastic material that is
easily molded into a suitable shape for handling by the surgeon.
Handle 204 defines an inner cavity (not shown) that houses the
electrical connections 250 (FIG. 5), and provides a suitable
interface for connection to an electrical connecting cable 22 (see
FIG. 1). Electrode support member 102 extends from the distal end
of shaft 100 (usually about 1 to 20 mm), and provides support for a
plurality of electrically isolated electrode terminals 104 (see
FIGS. 3 and 4). As shown in FIG. 2, a fluid tube 233 extends
through an opening in handle 204, and includes a connector 235 for
connection to a fluid supply source, for supplying electrically
conductive fluid to the target site. Depending on the configuration
of the distal surface of shaft 100, fluid tube 233 may extend
through a single lumen (not shown) in shaft 100, or it may be
coupled to a plurality of lumens (also not shown) that extend
through shaft 100 to a plurality of openings at its distal end. In
the representative embodiment, fluid tube 233 extends along the
exterior of shaft 100 to a point just proximal of return electrode
112 (see FIG. 4). In this embodiment, the fluid is directed through
an opening 237 past return electrode 112 to the electrode terminals
104. Probe 90 may also include a valve 17 (FIG. 1) or equivalent
structure for controlling the flow rate of the electrically
conducting fluid to the target site.
[0089] As shown in FIG. 2, the distal portion of shaft 100 is
preferably bent to improve access to the operative site of the
tissue being treated. Electrode support member 102 has a
substantially planar tissue treatment surface 212 (FIGS. 5A and 5B)
that is usually at an angle of about 10 to 90 degrees relative to
the longitudinal axis of shaft 100, preferably about 30 to 60
degrees and more preferably about 45 degrees. In alternative
embodiments, the distal portion of shaft 100 comprises a flexible
material which can be deflected relative to the longitudinal axis
of the shaft. Such deflection may be selectively induced by
mechanical tension of a pull wire, for example, or by a shape
memory wire that expands or contracts by externally applied
temperature changes. A more complete description of this embodiment
can be found in PCT International Application, U.S. National Phase
Serial No. PCT/US94/05168, filed on May 10, 1994 (Attorney Docket
16238-000440), the complete disclosure of which has previously been
incorporated herein by reference.
[0090] The bend in the distal portion of shaft 100 is particularly
advantageous in the treatment of sinus tissue as it allows the
surgeon to reach the target tissue within the nose as the shaft 100
extends through the nasal passage. Of course, it will be recognized
that the shaft may have different angles depending on the
procedure. For example, a shaft having a 90.degree. bend angle may
be particularly useful for accessing tissue located in the back
portion of the mouth and a shaft having a 10.degree. to 30.degree.
bend angle may be useful for accessing tissue near or in the front
portion of the mouth or nose
[0091] In the embodiment shown in FIGS. 2-5, probe 90 includes a
return electrode 112 for completing the current path between
electrode terminals 104 and a high frequency power supply 28 (see
FIG. 1). As shown, return electrode 112 preferably comprises an
annular conductive band coupled to the distal end of shaft 100
slightly proximal to tissue treatment surface 212 of electrode
support member 102, typically about 0.5 to 10 mm and more
preferably about 1 to 10 mm. Return electrode 112 is coupled to a
connector 258 that extends to the proximal end of probe 10, where
it is suitably connected to power supply 10 (FIG. 1).
[0092] As shown in FIG. 2, return electrode 112 is not directly
connected to electrode terminals 104. To complete this current path
so that electrode terminals 104 are electrically connected to
return electrode 112, electrically conducting fluid (e.g., isotonic
saline) is caused to flow therebetween. In the representative
embodiment, the electrically conducting fluid is delivered through
fluid tube 233 to opening 237, as described above. Alternatively,
the fluid may be delivered by a fluid delivery element (not shown)
that is separate from probe 90. In arthroscopic surgery, for
example, the body cavity will be flooded with isotonic saline and
the probe 90 will be introduced into this flooded cavity.
Electrically conducting fluid will be continually resupplied to
maintain the conduction path between return electrode 112 and
electrode terminals 104.
[0093] In alternative embodiments, the fluid path may be formed in
probe 90 by, for example, an inner lumen or an annular gap between
the return electrode and a tubular support member within shaft 100
(see FIG. 6). This annular gap may be formed near the perimeter of
the shaft 100 such that the electrically conducting fluid tends to
flow radially inward towards the target site, or it may be formed
towards the center of shaft 100 so that the fluid flows radially
outward. In both of these embodiments, a fluid source (e.g., a bag
of fluid elevated above the surgical site or having a pumping
device), is coupled to probe 90 via a fluid supply tube (not shown)
that may or may not have a controllable valve. A more complete
description of an electrosurgical probe incorporating one or more
fluid lumen(s) can be found in parent application Ser. No.
08/485,219, filed on Jun. 7, 1995 (Attorney Docket 16238-006000),
the complete disclosure of which has previously been incorporated
herein by reference.
[0094] Referring to FIG. 3, the electrically isolated electrode
terminals 104 are spaced apart over tissue treatment surface 212 of
electrode support member 102. The tissue treatment surface and
individual electrode terminals 104 will usually have dimensions
within the ranges set forth above. In the representative
embodiment, the tissue treatment surface 212 has an oval
cross-sectional shape with a length in the range of 1 mm to 20 mm
and a width in the range from 0.3 mm to 7 mm. The oval
cross-sectional shape accommodates the bend in the distal portion
of shaft 100. The individual electrode terminals 104 preferably
extend outward from tissue treatment surface 212 by a distance of
about 0.1 to 4 mm, usually about 0.2 to 2 mm. Applicant has found
that this configuration increases the high electric field
intensities and associated current densities around electrode
terminals 104 to facilitate the ablation of tissue as described in
detail above.
[0095] In the embodiment of FIGS. 2-5, the probe includes a single,
larger opening 209 in the center of tissue treatment surface 212,
and a plurality of electrode terminals (e.g., about 3-15) around
the perimeter of surface 212 (see FIG. 3). Alternatively, the probe
may include a single, annular, or partially annular, electrode
terminal at the perimeter of the tissue treatment surface. The
central opening 209 is coupled to a suction lumen (not shown)
within shaft 100 and a suction tube 211 (FIG. 2) for aspirating
tissue, fluids and/or gases from the target site. In this
embodiment, the electrically conductive fluid generally flows
radially inward past electrode terminals 104 and then back through
the opening 209. Aspirating the electrically conductive fluid
during surgery allows the surgeon to see the target site, and it
prevents the fluid from flowing into the patient's body, e.g.,
through the sinus passages, down the patient's throat or into the
ear canal.
[0096] Of course, it will be recognized that the distal tip of
probe may have a variety of different configurations. For example,
the probe may include a plurality of openings 209 around the outer
perimeter of tissue treatment surface 212 (see FIG. 6B). In this
embodiment, the electrode terminals 104 extend from the center of
tissue treatment surface 212 radially inward from openings 209. The
openings are suitably coupled to fluid tube 233 for delivering
electrically conductive fluid to the target site, and suction tube
211 for aspirating the fluid after it has completed the conductive
path between the return electrode 112 and the electrode terminals
104.
[0097] FIG. 5 illustrates the electrical connections 250 within
handle 204 for coupling electrode terminals 104 and return
electrode 112 to the power supply 28. As shown, a plurality of
wires 252 extend through shaft 100 to couple terminals 104 to a
plurality of pins 254, which are plugged into a connector block 256
for coupling to a connecting cable 22 (FIG. 1). Similarly, return
electrode 112 is coupled to connector block 256 via a wire 258 and
a plug 260.
[0098] According to the present invention, the probe 90 further
includes an identification element that is characteristic of the
particular electrode assembly so that the same power supply 28 can
be used for different electrosurgical operations. In one
embodiment, for example, the probe 90 includes a voltage reduction
element or a voltage reduction circuit for reducing the voltage
applied between the electrode terminals 104 and the return
electrode 112. The voltage reduction element serves to reduce the
voltage applied by the power supply so that the voltage between the
electrode terminals and the return electrode is low enough to avoid
excessive power dissipation into the electrically conducting medium
and/or ablation of the soft tissue at the target site. The voltage
reduction element primarily allows the electrosurgical probe 90 to
be compatible with other ArthroCare generators that are adapted to
apply higher voltages for ablation or vaporization of tissue. For
contraction of tissue, for example, the voltage reduction element
will serve to reduce a voltage of about 100 to 135 volts rms (which
is a setting of 1 on the ArthroCare Model 970 and 980 (i.e., 2000)
Generators) to about 45 to 60 volts rms, which is a suitable
voltage for contraction of tissue without ablation (e.g., molecular
dissociation) of the tissue.
[0099] Of course, for some procedures, such as endoscopic sinus
surgery, the probe will typically not require a voltage reduction
element. Alternatively, the probe may include a voltage increasing
element or circuit, if desired.
[0100] In the representative embodiment, the voltage reduction
element is a dropping capacitor 262 which has first leg 264 coupled
to the return electrode wire 258 and a second leg 266 coupled to
connector block 256. Of course, the capacitor may be located in
other places within the system, such as in, or distributed along
the length of, the cable, the generator, the connector, etc. In
addition, it will be recognized that other voltage reduction
elements, such as diodes, transistors, inductors, resistors,
capacitors or combinations thereof, may be used in conjunction with
the present invention. For example, the probe 90 may include a
coded resistor (not shown) that is constructed to lower the voltage
applied between return electrode 112 and electrode terminals 104 to
a suitable level for contraction of tissue. In addition, electrical
circuits may be employed for this purpose.
[0101] Alternatively or additionally, the cable 22 that couples the
power supply 10 to the probe 90 may be used as a voltage reduction
element. The cable has an inherent capacitance that can be used to
reduce the power supply voltage if the cable is placed into the
electrical circuit between the power supply, the electrode
terminals and the return electrode. In this embodiment, the cable
22 may be used alone, or in combination with one of the voltage
reduction elements discussed above, e.g., a capacitor.
[0102] Further, it should be noted that the present invention can
be used with a power supply that is adapted to apply a voltage
within the selected range for treatment of tissue. In this
embodiment, a voltage reduction element or circuitry may not be
desired.
[0103] FIGS. 7A-7C schematically illustrate the distal portion of
three different embodiments of probe 90 according to the present
invention. As shown in 7A, electrode terminals 104 are anchored in
a support matrix 102 of suitable insulating material (e.g., ceramic
or glass material, such as alumina, zirconia and the like) which
could be formed at the time of manufacture in a flat, hemispherical
or other shape according to the requirements of a particular
procedure. The preferred support matrix material is alumina,
available from Kyocera Industrial Ceramics Corporation, Elkgrove,
Ill., because of its high thermal conductivity, good electrically
insulative properties, high flexural modulus, resistance to carbon
tracking, biocompatibility, and high melting point. The support
matrix 102 is adhesively joined to a tubular support member 78 that
extends most or all of the distance between matrix 102 and the
proximal end of probe 90. Tubular member 78 preferably comprises an
electrically insulating material, such as an epoxy or
silicone-based material.
[0104] In a preferred construction technique, electrode terminals
104 extend through pre-formed openings in the support matrix 102 so
that they protrude above tissue treatment surface 212 by the
desired distance. The electrodes are then bonded to the tissue
treatment surface 212 of support matrix 102, typically by an
inorganic sealing material 80. Sealing material 80 is selected to
provide effective electrical insulation, and good adhesion to both
the alumina matrix 102 and the platinum or titanium electrode
terminals. Sealing material 80 additionally should have a
compatible thermal expansion coefficient and a melting point well
below that of platinum or titanium and alumina or zirconia,
typically being a glass or glass ceramic.
[0105] In the embodiment shown in FIG. 7A, return electrode 112
comprises an annular member positioned around the exterior of shaft
100 of probe 90. Return electrode 90 may fully or partially
circumscribe tubular support member 78 to form an annular gap 54
therebetween for flow of electrically conducting liquid 50
therethrough, as discussed below. Gap 54 preferably has a width in
the range of 0.25 mm to 4 mm. Alternatively, probe may include a
plurality of longitudinal ribs between support member 78 and return
electrode 112 to form a plurality of fluid lumens extending along
the perimeter of shaft 100. In this embodiment, the plurality of
lumens will extend to a plurality of openings.
[0106] Return electrode 112 is disposed within an electrically
insulative jacket 18, which is typically formed as one or more
electrically insulative sheaths or coatings, such as
polytetrafluoroethylene, polyamide, and the like. The provision of
the electrically insulative jacket 18 over return electrode 112
prevents direct electrical contact between return electrode 56 and
any adjacent body structure. Such direct electrical contact between
a body structure (e.g., tendon) and an exposed electrode member 112
could result in unwanted heating and necrosis of the structure at
the point of contact causing necrosis.
[0107] As shown in FIG. 7A, return electrode 112 is not directly
connected to electrode terminals 104. To complete this current path
so that terminals 104 are electrically connected to return
electrode 112, electrically conducting liquid 50 (e.g., isotonic
saline) is caused to flow along fluid path(s) 83. Fluid path 83 is
formed by annular gap 54 between outer return electrode 112 and
tubular support member. The electrically conducting liquid 50
flowing through fluid path 83 provides a pathway for electrical
current flow between electrode terminals 104 and return electrode
112, as illustrated by the current flux lines 60 in FIG. 6A. When a
voltage difference is applied between electrode terminals 104 and
return electrode 112, high electric field intensities will be
generated at the distal tips of terminals 104 with current flow
from terminals 104 through the target tissue to the return
electrode, the high electric field intensities causing ablation of
tissue 52 in zone 88.
[0108] FIG. 7B illustrates another alternative embodiment of
electrosurgical probe 90 which has a return electrode 112
positioned within tubular member 78. Return electrode 112 is
preferably a tubular member defining an inner lumen 57 for allowing
electrically conducting liquid 50 (e.g., isotonic saline) to flow
therethrough in electrical contact with return electrode 112. In
this embodiment, a voltage difference is applied between electrode
terminals 104 and return electrode 112 resulting in electrical
current flow through the electrically conducting liquid 50 as shown
by current flux lines 60 (FIG. 3). As a result of the applied
voltage difference and concomitant high electric field intensities
at the tips of electrode terminals 104, tissue 52 becomes ablated
or transected in zone 88.
[0109] FIG. 7C illustrates another embodiment of probe 90 that is a
combination of the embodiments in FIGS. 7A and 7B. As shown, this
probe includes both an inner lumen 57 and an outer gap or plurality
of outer lumens 54 for flow of electrically conductive fluid. In
this embodiment, the return electrode 112 may be positioned within
tubular member 78 as in FIG. 7B, outside of tubular member 78 as in
FIG. 7A, or in both locations.
[0110] FIG. 9 illustrates another embodiment of probe 90 where the
distal portion of shaft 100 is bent so that electrode terminals
extend transversely to the shaft. Preferably, the distal portion of
shaft 100 is perpendicular to the rest of the shaft so that tissue
treatment surface 212 is generally parallel to the shaft axis. In
this embodiment, return electrode 112 is mounted to the outer
surface of shaft 100 and is covered with an electrically insulating
jacket 18. The electrically conducting fluid 50 flows along flow
path 83 through return electrode 112 and exits the distal end of
electrode 112 at a point proximal of tissue treatment surface 212.
The fluid is directed exterior of shaft to surface 212 to create a
return current path from electrode terminals 104, through the fluid
50, to return electrode 12, as shown by current flux lines 60.
[0111] FIG. 10 illustrates another embodiment of the invention
where electrosurgical system 11 further includes a liquid supply
instrument 64 for supplying electrically conducting fluid 50
between electrode terminals 104 and return electrode 112. Liquid
supply instrument 64 comprises an inner tubular member or return
electrode 112 surrounded by an electrically insulating jacket 18.
Return electrode 112 defines an inner passage 83 for flow of fluid
50. As shown in FIG. 8, the distal portion of instrument 64 is
preferably bent so that liquid 50 is discharged at an angle with
respect to instrument 64. This allows the surgical team to position
liquid supply instrument 64 adjacent tissue treatment surface 212
with the proximal portion of supply instrument 64 oriented at a
similar angle to probe 90.
[0112] The present invention is not limited to an electrode array
disposed on a relatively planar surface at the distal tip of probe
90, as described above. Referring to FIGS. 8A and 8B, an
alternative probe 90 includes a pair of electrodes 105a, 105b
mounted to the distal end of shaft 100. Electrodes 105a, 105b are
electrically connected to power supply as described above and
preferably have tips 107a, 107b with a screwdriver shape. The
screwdriver shape provides a greater amount of "edges" to
electrodes 105a, 105b, to increase the electric field intensity and
current density at the edges and thereby improve the cutting
ability as well as the ability to limit bleeding from the incised
tissue (i.e., hemostasis).
[0113] FIGS. 11-13 illustrate a method for treating nasal or sinus
blockages, e.g., chronic sinusitis, according to the present
invention. In these procedures, the polyps, turbinates or other
sinus tissue may be ablated or reduced (e.g., by tissue
contraction) to clear the blockage and/or enlarge the sinus cavity
to reestablish normal sinus function. For example, in chronic
rhinitis, which is a collective term for chronic irritation or
inflammation of the nasal mucosa with hypertrophy of the nasal
mucosa, the inferior turbinate may be reduced by ablation or
contraction. Alternatively, a turbinectomy or mucotomy may be
performed by removing a strip of tissue from the lower edge of the
inferior turbinate to reduce the volume of the turbinate. For
treating nasal polypi, which comprises benign pedicled or sessile
masses of nasal or sinus mucosa caused by inflammation, the nasal
polypi may be contracted or shrunk, or ablated by the method of the
present invention. For treating severe sinusitis, a frontal sinus
operation may be performed to introduce the electrosurgical probe
to the site of blockage. The present invention may also be used to
treat diseases of the septum, e.g., ablating or resecting portions
of the septum for removal, straightening or reimplantation of the
septum.
[0114] The present invention is particularly useful in functional
endoscopic sinus surgery (FESS) in the treatment of sinus disease.
In contrast to prior art microdebriders, the electrosurgical probe
of the present invention effects hemostasis of severed blood
vessels, and allows the surgeon to precisely remove tissue with
minimal or no damage to surrounding tissue, bone, cartilage or
nerves. By way of example and not limitation, the present invention
may be used for the following procedures: (1) uncinectomy or medial
displacement or removal of portions of the middle turbinate; (2)
maxillary, sphenoid or ethmoid sinusotomies or enlargement of the
natural ostium of the maxillary, sphenoid, or ethmoid sinuses,
respectively; (3) frontal recess dissections, in which polypoid or
granulation tissue are removed; (4) polypectomies, wherein polypoid
tissue is removed in the case of severe nasal polyposis; (5) concha
bullosa resections or the thinning of polypoid middle turbinate;
(6) septoplasty; and the like.
[0115] FIGS. 11-13 schematically illustrate an endoscopic sinus
surgery (FESS) procedure according to the present invention. As
shown in FIG. 11, an endoscope 300 is first introduced through one
of the nasal passages 301 to allow the surgeon to view the target
site, e.g., the sinus cavities. As shown, the endoscope 300 will
usually comprise a thin metal tube 302 with a lens (not shown) at
the distal end 304, and an eyepiece 306 at the proximal end 308. As
shown in FIG. 2, the probe shaft 100 (not shown in FIG. 11) has a
bend 101 to facilitate use of both the endoscope and the probe 90
in the same nasal passage (i.e., the handles of the two instruments
do not interfere with each other in this embodiment).
Alternatively, the endoscope may be introduced transorally through
the inferior soft palate to view the nasopharynx. Suitable nasal
endoscopes for use with the present invention are described in U.S.
Pat. Nos. 4,517,962, 4,844,052, 4,881,523 and 5,167,220, the
complete disclosures of which are incorporated herein by reference
for all purposes.
[0116] Alternatively, the endoscope 300 may include a sheath (not
shown) having an inner lumen for receiving the electrosurgical
probe shaft 100. In this embodiment, the shaft 100 will extend
through the inner lumen to a distal opening in the endoscope. The
shaft will include suitable proximal controls for manipulation of
its distal end during the surgical procedure.
[0117] As shown in FIG. 12, the distal end of probe 90 is
introduced through nasal passage 301 into the nasal cavity 303
(endoscope 300 is not shown in FIG. 12). Depending on the location
of the blockage, the electrode terminals 104 will be positioned
adjacent the blockage in the nasal cavity 303, or in one of the
paranasal sinuses 305, 307. Note that only the frontal sinus 305
and the sphenoidal sinus 307 are shown in FIG. 12, but the
procedure is also applicable to the ethmoidal and maxillary
sinuses. Once the surgeon has reached the point of major blockage,
electrically conductive fluid is delivered through tube 233 and
opening 237 to the tissue (see FIG. 2). The fluid flows past the
return electrode 112 to the electrode terminals 104 at the distal
end of the shaft. The rate of fluid flow is controlled with valve
17 (FIG. 1) such that the zone between the tissue and electrode
support 102 is constantly immersed in the fluid. The power supply
28 is then turned on and adjusted such that a high frequency
voltage difference is applied between electrode terminals 104 and
return electrode 112. The electrically conductive fluid provides
the conduction path (see current flux lines) between electrode
terminals 104 and the return electrode 112.
[0118] FIGS. 13A and 13B illustrate the removal of sinus tissue in
more detail As shown, the high frequency voltage is sufficient to
convert the electrically conductive fluid (not shown) between the
target tissue 302 and electrode terminal(s) 104 into an ionized
vapor layer 312 or plasma. As a result of the applied voltage
difference between electrode terminal(s) 104 and the target tissue
302 (i.e., the voltage gradient across the plasma layer 312),
charged particles 315 in the plasma (viz., electrons) are
accelerated towards the tissue. At sufficiently high voltage
differences, these charged particles 315 gain sufficient energy to
cause dissociation of the molecular bonds within tissue structures.
This molecular dissociation is accompanied by the volumetric
removal (i.e., ablative sublimation) of tissue and the production
of low molecular weight gases 314, such as oxygen, nitrogen, carbon
dioxide, hydrogen and methane. The short range of the accelerated
charged particles 315 within the tissue confines the molecular
dissociation process to the surface layer to minimize damage and
necrosis to the underlying tissue 320.
[0119] During the process, the gases 314 will be aspirated through
opening 209 and suction tube 211 to a vacuum source. In addition,
excess electrically conductive fluid, and other fluids (e.g.,
blood) will be aspirated from the target site 300 to facilitate the
surgeon's view. During ablation of the tissue, the residual heat
generated by the current flux lines (typically less than
150.degree. C.), will usually be sufficient to coagulate any
severed blood vessels at the site. If not, the surgeon may switch
the power supply 28 into the coagulation mode by lowering the
voltage to a level below the threshold for fluid vaporization, as
discussed above. This simultaneous hemostasis results in less
bleeding and facilitates the surgeon's ability to perform the
procedure. Once the blockage has been removed, aeration and
drainage are reestablished to allow the sinuses to heal and return
to their normal function.
[0120] Another advantage of the present invention is the ability to
precisely ablate layers of sinus tissue without causing necrosis or
thermal damage to the underlying and surrounding tissues, nerves
(e.g., the optic nerve) or bone. In addition, the voltage can be
controlled so that the energy directed to the target site is
insufficient to ablate bone or adipose tissue (which generally has
a higher impedance than the target sinus tissue). In this manner,
the surgeon can literally clean the tissue off the bone, without
ablating or otherwise effecting significant damage to the bone.
[0121] Referring to FIGS. 15-17, the electrosurgical device
according to the present invention may also be configured as a
catheter system 400. As shown in FIG. 15, a catheter system 400
generally comprises an electrosurgical catheter 460 connected to a
power supply 28 by an interconnecting cable 486 for providing high
frequency voltage to a target tissue and an irrigant reservoir or
source 600 for providing electrically conducting fluid to the
target site. Catheter 460 generally comprises an elongate, flexible
shaft body 462 including a tissue removing or ablating region 464
at the distal end of body 462. The proximal portion of catheter 460
includes a multi-lumen fitment 614 which provides for
interconnections between lumens and electrical leads within
catheter 460 and conduits and cables proximal to fitment 614. By
way of example, a catheter electrical connector 496 is removably
connected to a distal cable connector 494 which, in turn, is
removably connectable to generator 28 through connector 492. One or
more electrically conducting lead wires (not shown) within catheter
460 extend between one or more active electrodes 463 at tissue
ablating region 464 and one or more corresponding electrical
terminals (also not shown) in catheter connector 496 via active
electrode cable branch 487. Similarly, one or more return
electrodes 466 at tissue ablating region 464 are coupled to a
return electrode cable branch 489 of catheter connector 496 by lead
wires (not shown). Of course, a single cable branch (not shown) may
be used for both active and return electrodes.
[0122] Catheter body 462 may include reinforcing fibers or braids
(not shown) in the walls of at least the distal ablation region 464
of body 462 to provide responsive torque control for rotation of
electrode terminals during tissue engagement. This rigid portion of
the catheter body 462 preferably extends only about 7 to 10 mm
while the remainder of the catheter body 462 is flexible to provide
good trackability during advancement and positioning of the
electrodes adjacent target tissue.
[0123] Conductive fluid 30 is provided to tissue ablation region
464 of catheter 460 via a lumen (not shown in FIG. 15) within
catheter 460. Fluid is supplied to lumen from the source along a
conductive fluid supply line 602 and a conduit 603, which is
coupled to the inner catheter lumen at multi-lumen fitment 114. The
source of conductive fluid (e.g., isotonic saline) may be an
irrigant pump system (not shown) or a gravity-driven supply, such
as an irrigant reservoir 600 positioned several feet above the
level of the patient and tissue ablating region 8. A control valve
604 may be positioned at the interface of fluid supply line 602 and
conduit 603 to allow manual control of the flow rate of
electrically conductive fluid 30. Alternatively, a metering pump or
flow regulator may be used to precisely control the flow rate of
the conductive fluid.
[0124] System 400 further includes an aspiration or vacuum system
(not shown) to aspirate liquids and gases from the target site. The
aspiration system will usually comprise a source of vacuum coupled
to fitment 614 by a aspiration connector 605.
[0125] FIGS. 16 and 17 illustrate the working end 464 of an
electrosurgical catheter 460 constructed according to the
principles of the present invention. As shown in FIG. 16, catheter
460 generally includes an elongated shaft 462 which may be flexible
or rigid, and an electrode support member 620 coupled to the distal
end of shaft 462. Electrode support member 620 extends from the
distal end of shaft 462 (usually about 1 to 20 mm), and provides
support for a plurality of electrically isolated electrode
terminals 463. Electrode support member 620 and electrode terminals
462 are preferably secured to a tubular support member 626 within
shaft 460 by adhesive 630.
[0126] The electrode terminals 463 may be constructed using round,
square, rectangular or other shaped conductive metals. By way of
example, the electrode terminal materials may be selected from the
group including stainless steel, tungsten and its alloys,
molybdenum and its alloys, titanium and its alloys, nickel-based
alloys, as well as platinum and its alloys. Electrode support
member 620 is preferably a ceramic, glass or glass/ceramic
composition (e.g., aluminum oxide, titanium nitride).
Alternatively, electrode support member 620 may include the use of
high-temperature biocompatible plastics such as
polyether-ether-keytone (PEEK) manufactured by Vitrex International
Products, Inc. or polysulfone manufactured by GE Plastics. The
adhesive 630 may, by way of example, be an epoxy (e.g., Master Bond
EP42HT) or a silicone-based adhesive.
[0127] As shown in FIG. 17B, a total of 7 circular active
electrodes or electrode terminals 463 are shown in a symmetrical
pattern having an active electrode diameter, D.sub.1 in the range
from 0.05 mm to 1.5 mm, more preferably in the range from 0.1 mm to
0.75 mm. The interelectrode spacings, W.sub.1 and W.sub.2 are
preferably in the range from 0.1 mm to 1.5 mm and more preferably
in the range from 0.2 mm to 0.75 mm. The distance between the outer
perimeter of the electrode terminal 463 and the perimeter of the
electrode support member, W.sub.3 is preferably in the range from
0.1 mm to 1.5 mm and more preferably in the range from 0.2 mm to
0.75 mm. The overall diameter, D.sub.2 of the working end 464 of
catheter body 462 is preferably in the range from 0.5 mm to 10 mm
and more preferably in the range from 0.5 mm to 5 mm. As discussed
above, the shape of the active electrodes may be round, square,
triangular, hexagonal, rectangular, tubular, flat strip and the
like and may be arranged in a circularly symmetric pattern or may,
by way of example, be arranged in a rectangular pattern, square
pattern, or strip.
[0128] Catheter body 462 includes a tubular cannula 626 extending
along body 462 radially outward from support member 620 and
electrode terminals 463. The material for cannula 626 may be
advantageously selected from a group of electrically conductive
metals so that the cannula 626 functions as both a structural
support member for the array of electrode terminals 463 as well as
a return electrode 624. The support member 626 is connected to an
electrical lead wire (not shown) at its proximal end within a
connector housing (not shown) and continues via a suitable
connector to power supply 28 to provide electrical continuity
between one output pole of high frequency generator 28 and said
return electrode 624. The cannula 626 may be selected from the
group including stainless steel, copper-based alloys, titanium or
its alloys, and nickel-based alloys. The thickness of the cannula
626 is preferably in the range from 0.08 mm to 1.0 mm and more
preferably in the range from 0.1 mm to 0.4 mm.
[0129] As shown in FIG. 16, cannula 626 is covered with an
electrically insulating sleeve 608 to protect the patient's body
from the electric current. Electrically insulating sleeve 608 may
be a coating (e.g., nylon) or heat shrinkable plastic (e.g.,
fluropolymer or polyester). The proximal portion of the cannula 626
is left exposed to function as the return electrode 624. The length
of the return electrode 624, L.sub.5 is preferably in the range
from 1 mm to 30 mm and more preferably in the range from 2 mm to 20
mm. The spacing between the most distal portion of the return
electrode 624 and the plane of the tissue treatment surface 622 of
the electrode support member 620, L.sub.1 is preferably in the
range from 0.5 mm to 30 mm and more preferably in the range from 1
mm to 20 mm. The thickness of the electrically insulating sleeve
608 is preferably in the range from 0.01 mm to 0.5 mm and more
preferably in the range from 0.02 mm to 0.2 mm.
[0130] In the representative embodiment, the fluid path is formed
in catheter by an inner lumen 627 or annular gap between the return
electrode 624 and a second tubular support member 628 within shaft
460. This annular gap may be formed near the perimeter of the shaft
460 as shown in FIG. 16 such that the electrically conducting fluid
tends to flow radially inward towards the target site, or it may be
formed towards the center of shaft 460 (not shown) so that the
fluid flows radially outward. In both of these embodiments, a fluid
source (e.g., a bag of fluid elevated above the surgical site or
having a pumping device), is coupled to catheter 460 via a fluid
supply tube (not shown) that may or may not have a controllable
valve.
[0131] In pan alternative embodiment shown in FIG. 17A, the
electrically conducting fluid is delivered from a fluid delivery
element (not shown) that is separate from catheter 460. In
arthroscopic surgery, for example, the body cavity will be flooded
with isotonic saline and the catheter 460 will be introduced into
this flooded cavity. Electrically conducting fluid will be
continually resupplied to maintain the conduction path between
return electrode 624 and electrode terminals 463.
[0132] FIG. 18 illustrates a method of removing tissue from a body
lumen within a patient's nose. As shown, the patient's nose
includes a nasal cavity 700 divided up by the inferior and middle
nasal conchas 702, 704, and a number of sinus cavities separated
from the nasal cavity by ethmoid bone 706. As shown, the frontal
sinus 708 and the sphenoidal sinus 710 each include a passage or
lumen 712, 714, respectively, extending through ethmoid bone 706
into the nasal cavity 700. In addition, the sinus cavities have
passages (not shown) that connect each other. These passages often
become blocked with swollen or scarred tissue, which causes the
sinus cavities to fill, producing deep pain and pressure. Postnasal
or nasal drainage, nasal congestion with pressure, headaches, sinus
infections and nasal polyps are most commonly associated with
chronic sinusitis. Note that only the frontal sinus 305 and the
sphenoidal sinus 307 are shown in FIG. 18, but the procedure is
also applicable to the ethmoidal and maxillary sinuses. The ostium
720 for the maxillary sinus is shown in FIG. 18.
[0133] As shown in FIG. 18, the ablation region 464 of catheter 460
is advanced through the nostril 722 into the nasal cavity 700 and
to the passage 712 leading to the frontal sinus 708. The catheter
460 may be advanced with a variety of techniques, such as a
guidewire, steerable catheter and the like. Once the surgeon has
reached the point of major blockage within passage 712,
electrically conductive fluid is delivered through one or more
internal lumen(s) (not shown) within the catheter to the tissue.
Alternatively, the nasal cavity 700 is filled with electrically
conductive fluid (similar to an arthroscopic procedure). In some
embodiments, the catheter may be configured to operate with a
naturally occurring body fluid, e.g., blood, as the conductive
medium. The fluid flows past the return electrode 624 to the
electrode terminals 463 at the distal end of the catheter shaft.
The rate of fluid flow is controlled with a valve (not shown) such
that the zone between the occlusion and electrode terminal(s) 463
is constantly immersed in the fluid. The power supply 28 is then
turned on and adjusted such that a high frequency voltage
difference is applied between electrode terminals 462 and return
electrode 624. The electrically conductive fluid provides the
conduction path (see current flux lines) between electrode
terminals 463 and the return electrode 624.
[0134] In the preferred embodiment, the high frequency voltage is
sufficient to convert the electrically conductive fluid (not shown)
between the occlusive media and electrode terminal(s) 463 into an
ionized vapor layer or plasma. As a result of the applied voltage
difference between electrode terminal(s) 463 and the occlusive
media, charged particles in the plasma are accelerated towards the
occlusion to cause dissociation of the molecular bonds within
tissue structures, as discussed above. During the process, products
of ablation and excess electrically conductive fluid, and other
fluids (e.g., blood) may be aspirated from the target site to
facilitate the surgeon's view. During ablation of the tissue, the
residual heat generated by the current flux lines (typically less
than 150.degree. C.), will usually be sufficient to coagulate any
severed blood vessels at the site. If not, the surgeon may switch
the power supply 28 into the coagulation mode by lowering the
voltage to a level below the threshold for fluid vaporization, as
discussed above. This simultaneous hemostasis results in less
bleeding and facilitates the surgeon's ability to perform the
procedure. Once the blockage has been removed, aeration and
drainage are reestablished to allow the sinuses to heal and return
to their normal function.
[0135] FIG. 19 is a coronal section of a patient's head
illustrating the paranasal sinuses in more detail. As shown, the
nasal septum 750 extends through the center of the nasal cavity 700
between the right and left portions 752, 754 of the maxillary
sinus. A series of winding passages 765 connect the nasal cavity
700 with the maxillary sinus portions 752, 754. These passages 765
can become partially or completely blocked. The systems and methods
of the present invention allow the surgeon to advance a small
catheter into these passages and volumetrically remove the blockage
in a minimally invasive manner, i.e., without causing significant
damage to the surrounding cartilage, the nasal septum or the
sinuses.
[0136] FIG. 20 illustrates an embodiment of the present invention
designed for cutting of body structures. In this embodiment, the
electrode terminals 804 are arranged in a linear or columnar array
of one of more closely spaced columns so that as the electrodes 804
are moved along the longer axis (denoted by arrow 806 in FIG. 20),
the current flux lines 810 are narrowly confined at the tip of the
electrode terminals 804 and result in a cutting effect in the body
structure being treated. As before, the current flux lines 810
emanating from the electrode terminals 804 pass through the
electrically conducting liquid to the return electrode structure
812 located proximal to the probe tip.
[0137] Referring now to FIGS. 21 and 22, alternative geometries are
shown for the electrode terminals 804. These alternative electrode
geometries allow the electrical current densities emanating from
the electrode terminals 804 to be concentrated to achieve an
increased ablation rate and/or a more concentrated ablation effect
due to the fact that sharper edges (i.e., regions of smaller radii
of curvature) result in higher current densities. FIG. 21
illustrates a flattened extension of a round wire electrode
terminal 804 which results in higher current densities at the edges
820. Another example is shown in FIG. 22 in which the electrode
terminal 804 is formed into a cone shaped point 822 resulting in
higher current densities at the tip of the cone.
[0138] FIGS. 23-25 illustrate an exemplary electrosurgical probe
830 or "Plasma Scalpel" for cutting and removing structures from
the outer surface of the skin, such as lesions, scars, etc., or for
cutting and removing tissue within the patient's nose, mouth and
throat. Probe 830 comprises a shaft or disposable tip 832 removably
coupled to a proximal handle 834, and an electrically insulating
electrode support member 836 extending from tip 832 for supporting
a plurality of electrode terminals 840 (see FIGS. 23 and 25). Tip
832 and handle 834 typically comprise a plastic material that is
easily molded into a suitable shape for handling by the surgeon. As
shown in FIG. 26, handle 834 defines an inner cavity 842 that
houses the electrical connections 844, and provides a suitable
interface for connection to electrical connecting cable 34 (see
FIG. 1). In the exemplary embodiment, handle 834 is constructed of
a steam autoclavable plastic or metal (e.g., polyethylether
keytone, or a stable metal alloy containing aluminum and/or zine.
so that it can be re-used by sterilizing handle 834 between
surgical procedures. High service temperature materials are
preferred, such as a silicone cable jacket and a poly-ether-imide
handpiece or ULTEM.RTM. that can withstand a repeated exposure to
high temperatures.
[0139] Referring to FIG. 23, tip 834 preferably comprises first and
second housing halves that snap fit together, and form a recess
therebetween for holding electrode support member 836 within the
tip 832. Electrode support member 836 extends from the distal end
of tip 832 (usually about 0.5 to 20 mm), and provides support for a
plurality of electrically isolated electrode terminals 840 and one
or more return electrodes 852 (see FIG. 25). Alternatively,
electrode support member 836 may be recessed from the distal end of
tip 832 to help confine the electrically conductive fluid around
the electrode terminals 840 during the surgical procedure, as
discussed above. Electrode support member 836 has a substantially
planar tissue treatment surface 860 that is usually disposed at an
angle of about 10 to 90 degrees relative to the longitudinal axis
of handle 834 to facilitate handling by the surgeon. In the
exemplary embodiment, this function is accomplished by orienting
tip 832 at an acute angle relative to the longitudinal axis of
handle 834.
[0140] In the embodiment shown in FIGS. 23-25, probe 830 includes a
single annular return electrode 452 for completing the current path
between electrode terminals 840 and power supply 28 (see FIG. 1).
As shown, return electrode 852 preferably has a fluid contact
surface slightly proximal to tissue treatment surface 860,
typically about 0.1 to 2 mm, preferably about 0.2 to 1 mm. Return
electrode 852 is coupled to a connector (not shown) that extends to
the proximal end of handle 834, where it is suitably connected to
power supply 28 (FIG. 1).
[0141] Referring to FIG. 26, tip 832 further includes a male
electrical connector 870 that holds a plurality of wires 872 each
coupled to one of the electrode terminals 840 and the return
electrode 852 on support member 836. A female connector 874 housed
within handle 834 is removably coupled to male connector 870, and a
plurality of wires 876 extend from female connector 874 to cable 34
(FIG. 1). Probe 830 will preferably also include an identification
element, such as a coded resistor (not shown), for programming a
particular voltage output range and mode of operation for the power
supply. This allows the power supply to be employed with a variety
of different probes for a variety of different applications.
[0142] In the representative embodiment, probe 830 includes a fluid
tube 880 (FIG. 23) for delivering electrically conductive fluid to
the target site. Fluid tube 880 is sized to extend through a groove
in handle 834 and through an inner cavity in tip 832 to a distal
opening 882 (FIG. 24) located adjacent electrode support member
836. Fluid tube 880 includes a proximal connector 4884 for coupling
to an electrically conductive fluid source 21 (FIG. 1).
[0143] Probe 830 will also include a valve or equivalent structure
for controlling the flow rate of the electrically conducting fluid
to the target site. In the representative embodiment, handle 312
comprises a rotatable sleeve 890 to provide a valve structure for
fluid tube 880. Rotation of sleeve 890 will impede, and eventually
obstruct, the flow of fluid through tube 880. Of course, this fluid
control may be provided by a variety of other input and valve
devices, such as switches, buttons, etc.
[0144] Referring to FIGS. 24 and 25, electrically isolated
electrode terminals 840 are spaced apart over tissue treatment
surface 860 of electrode support member 836, preferably in a linear
array. In the representative embodiment, three electrode terminals
840, each having a substantially conical shape, are arranged in a
linear array extending distally from surface 860. Electrode
terminals 840 will usually extend a distance of about 0.5 to 20 mm
from tissue treatment surface 860, preferably about 1 to 5 mm.
Applicant has found that this configuration increases the electric
field intensities and associated current densities at the distal
edges of electrode terminals 840, which increases the rate of
tissue cutting. In the representative embodiment, the tissue
treatment surface 380 has a circular cross-sectional shape with a
diameter in the range of about 0.5 mm to 20 mm (preferably about 2
to 10 mm). The individual electrode terminals 840 preferably taper
outward as shown, or they may form a distal edge, such as the
electrodes shown in FIGS. 8A and 11.
[0145] Electrode support member 836 preferably comprises a
multilayer substrate comprising a suitable high temperature,
electrically insulating material, such as ceramic. The multilayer
substrate is a thin or thick-film hybrid having conductive strips
that are adhered to the ceramic wafer layers (e.g., thick-film
printed and fired onto or plated onto the ceramic wafers). The
conductive strips typically comprise tungsten, gold, nickel,
silver, platinum or equivalent materials. In the exemplary
embodiment, the conductive strips comprise tungsten, and they are
co-fired together with the wafer layers to form an integral
package. The conductive strips are coupled to external wire
connectors by holes or vias that are drilled through the ceramic
layers, and plated or otherwise covered with conductive material. A
more complete description of such support members 370 can be found
in U.S. patent application Ser. No. 08/977,845, filed Nov. 25, 1997
(Attorney Docket No. D-2), previously incorporated herein by
reference.
[0146] Referring now to FIG. 26, another embodiment of an
electrosurgical probe 900 comprises a shaft 908 and at least two
electrode terminals 904 extending from a support matrix 902 at the
distal end of the shaft. The electrode terminals 904 preferably
define a distal edge 910 for cutting an incision in tissue. The
edges 910 of the electrode terminals 904 are substantially parallel
with each other and usually spaced a distance of about 4 to 15 mm,
preferably about 8-10 mm. The edges 910 extend from the distal end
of support matrix 902 by a distance of about 0.5 to 10 mm,
preferably about 2 to 5 mm. In the exemplary embodiment, probe 900
will include a return electrode 912 spaced proximally from the
electrode terminals 904. Alternatively, the return electrode 912
may be one of the electrode terminals 904, or it may be a
dispersive pad located on an external surface of the patient's
body.
[0147] Referring to FIG. 27, an electrosurgical scalpel 930
comprises a shaft 932 with an electrode assembly 934 at its distal
end, and a return electrode 936 proximally spaced from electrode
assembly 934 by an insulating member 938 (similar to some of the
devices described above). In this embodiment, electrode assembly
934 comprises a pair of outer electrode terminals 940 and an inner
loop electrode 942 aligned with each other to form a substantially
linear cutting path for cutting through tissue. The electrodes in
this embodiment will generally have the same extension lengths and
sizes as described above. This embodiment is particularly useful
for cutting tissue and effecting simultaneous hemostasis of the cut
tissue. The outer electrode terminals 940 extend distally to a
distinct, small area or point for precise cutting of tissue, while
the loop electrode 942 provides sufficient exposed surface area to
effectively coagulate tissue. In severely bleeding tissue, the
power supply 28 will be switched into the subablation mode to
remove the plasma layer and increase the effectiveness of
coagulation. Alternatively, the surgeon may decrease or eliminate
the supply of electrically conductive fluid to the target site and
remain at a higher power level. Applicant has found that this
forces the blood to become the conductive path between the return
electrode 936 and the electrode terminals 940, which increases the
rate of coagulation in the target area.
[0148] FIG. 28 illustrates yet another electrosurgical scalpel 950
according to the present invention. Scalpel 950 comprises a single
loop electrode 952 at the distal end of the instrument shaft 954
for both cutting and coagulation of tissue. Similar to the above
embodiment, the sharp distal line formed by the loop electrode 952
provides efficient and precise cutting of tissue, while the
increased surface area of the loop electrode facilitates
hemostasis. In other embodiments, the scalpel 950 may include a
plurality of such loops, aligned linearly, in parallel or in an
array.
[0149] Methods for treating air passage disorders according to the
present invention will now be described. In these embodiments, an
electrosurgical probe such as one of those described above can be
used to ablate, cut or resect targeted masses including, but not
limited to, the tongue, tonsils, turbinates, adenoids, soft palate
tissues (e.g., the uvula and soft palate), hard tissue and other
mucosal or submucosal tissue. In one embodiment, selected portions
of the uvula 320, soft palate and tonsils are removed to treat
sleep apnea. In this method, the distal end of an electrosurgical
instrument 90 such as one of the probes or catheters discussed
above is introduced into the patient's mouth 310, as shown in FIG.
14. This procedure is typically accomplished in a hospital under
general anesthesia, although it is possible to perform the
procedure in an office setting under local anesthesia, e.g., with a
tumescent or other local anesthesia. An endoscope (not shown), or
other type of viewing device, may also be introduced, or partially
introduced, into the mouth 310 to allow the surgeon to view the
procedure (the viewing device may be integral with, or separate
from, the electrosurgical probe). The electrode terminals 104 are
positioned adjacent to or against the target tissue (e.g., tonsils,
uvula 320, soft palate, etc.) and electrically conductive fluid is
delivered to the target site as described above. The power supply
28 (FIG. 1) is then activated and a high frequency voltage
difference is applied between the electrode terminals 104 and
return electrode 112. Depending on the procedure and the
configuration of the distal end of probe 90, the surgeon will then
manipulate the probe 90 to cut, ablate or otherwise remove the
obstructive tissue without damaging sensitive structures, such as
nerves and non-target tissue in the mouth. The target site may also
be aspirated to improve visualization and to ensure that excess
fluid and/or products of ablation do not flow down the patient's
throat.
[0150] As discussed above, the present invention uses a novel
Coblation process for removing tissue that involves lower
temperatures than conventional RF and laser devices used for
treating sleep obstructive disorders. Accordingly, the tissue is
removed with minimal charring and extremely low depths of tissue
necrosis. This minimal collateral damage and low temperature
results in significantly less pain to the patient during and after
the operation, and increased healing times over conventional
devices. In addition, the low temperature plasma at the end of the
probe 90 provides simultaneous hemostasis of any severed blood
vessels in the region of the target tissue. This minimizes bleeding
during the operation, which increases visualization, decreases the
duration of the operation and possibly contributes to faster
healing and less post-operative pain. Moreover, the precise nature
of the Coblation mechanism provised some comfort to the surgeon
that damage to adjacent nerves and other sensitive structures will
be minimized or completely eliminated.
[0151] In some cases, patient bleeding may be more intense than in
others. In particular, the removal of infected tonsils often
presents a significant hemostasis problem to the surgeon. Applicant
has found that the electrosurgical probes described in FIGS. 27 and
28 are particularly well suited for coagulating and sealing severed
blood vessels in the tonsils during the ablation procedure. In
severe cases, applicant has found that eliminating the presence of
conductive fluid (e.g., saline) at the target site facilitates
coagulation and hemostasis (e.g., by turning the pump off and
entering the coagulation mode).
[0152] In another embodiment, the electrosurgical probe of the
present invention can be used to ablate and/or contract soft palate
tissue to treat snoring disorders. In particular, the probe is used
to ablate or shrink sections of the uvula 320 without causing
unwanted tissue damage under and around the selected sections of
tissue. For tissue contraction, a sufficient voltage difference is
applied between the electrode terminals 104 and the return
electrode 112 to elevate the uvula tissue temperature from normal
body temperatures (e.g., 37.degree. C.) to temperatures in the
range of 45.degree. C. to 90.degree. C., preferably in the range
from 60.degree. C. to 70.degree. C. This temperature elevation
causes contraction of the collagen connective fibers within the
uvula tissue.
[0153] In one method of tissue contraction according to the present
invention, an electrically conductive fluid is delivered to the
target site as described above, and heated to a sufficient
temperature to induce contraction or shrinkage of the collagen
fibers in the target tissue. The electrically conducting fluid is
heated to a temperature sufficient to substantially irreversibly
contract the collagen fibers, which generally requires a tissue
temperature in the range of about 45.degree. C. to 90.degree. C.,
usually about 60.degree. C. to 70.degree. C. The fluid is heated by
applying high frequency electrical energy to the electrode
terminal(s) in contact with the electrically conducting fluid. The
current emanating from the electrode terminal(s) 104 heats the
fluid and generates a jet or plume of heated fluid, which is
directed towards the target tissue. The heated fluid elevates the
temperature of the collagen sufficiently to cause hydrothermal
shrinkage of the collagen fibers. The return electrode 112 draws
the electric current away from the tissue site to limit the depth
of penetration of the current into the tissue, thereby inhibiting
molecular dissociation and breakdown of the collagen tissue and
minimizing or completely avoiding damage to surrounding and
underlying tissue structures beyond the target tissue site. In an
exemplary embodiment, the electrode terminal(s) 104 are held away
from the tissue a sufficient distance such that the RF current does
not pass into the tissue at all, but rather passes through the
electrically conducting fluid back to the return electrode. In this
embodiment, the primary mechanism for imparting energy to the
tissue is the heated fluid, rather than the electric current.
[0154] In an alternative embodiment, the electrode terminal(s) 104
are brought into contact with, or close proximity to, the target
tissue so that the electric current passes directly into the tissue
to a selected depth. In this embodiment, the return electrode draws
the electric current away from the tissue site to limit its depth
of penetration into the tissue. Applicant has discovered that the
depth of current penetration also can be varied with the
electrosurgical system of the present invention by changing the
frequency of the voltage applied to the electrode terminal and the
return electrode. This is because the electrical impedance of
tissue is known to decrease with increasing frequency due to the
electrical properties of cell membranes which surround electrically
conductive cellular fluid. At lower frequencies (e.g., less than
350 kHz), the higher tissue impedance, the presence of the return
electrode and the electrode terminal configuration of the present
invention (discussed in detail below) cause the current flux lines
to penetrate less deeply resulting in a smaller depth of tissue
heating. In an exemplary embodiment, an operating frequency of
about 100 to 200 kHz is applied to the electrode terminal(s) to
obtain shallow depths of collagen shrinkage (e.g., usually less
than 1.5 mm and preferably less than 0.5 mm).
[0155] In another aspect of the invention, the size (e.g., diameter
or principal dimension) of the electrode terminals employed for
treating the tissue are selected according to the intended depth of
tissue treatment. As described previously in copending patent
application PCT International Application, U.S. National Phase
Serial No. PCT/US94/05168, the depth of current penetration into
tissue increases with increasing dimensions of an individual active
electrode (assuming other factors remain constant, such as the
frequency of the electric current, the return electrode
configuration, etc.). The depth of current penetration (which
refers to the depth at which the current density is sufficient to
effect a change in the tissue, such as collagen shrinkage,
irreversible necrosis, etc.) is on the order of the active
electrode diameter for the bipolar configuration of the present
invention and operating at a frequency of about 100 kHz to about
200 kHz. Accordingly, for applications requiring a smaller depth of
current penetration, one or more electrode terminals of smaller
dimensions would be selected. Conversely, for applications
requiring a greater depth of current penetration, one or more
electrode terminals of larger dimensions would be selected.
[0156] In addition to the above procedures, the system and method
of the present invention may be used for treating a variety of
disorders in the mouth 310, pharynx 330, larynx 335, hypopharynx,
trachea 340, esophagus 350 and the neck 360. For example, tonsillar
hyperplasis or other tonsil disorders may be treated with a
tonsillectomy by partially ablating the lymphoepithelial tissue.
This procedure is usually carried out under intubation anesthesia
with the head extended. An incision is made in the anterior faucial
pillar, and the connective tissue layer between the tonsillar
parenchyma and the pharyngeal constrictor muscles is demonstrated.
The incision may be made with conventional scalpels, or with the
electrosurgical probe of the present invention. The tonsil is then
freed by ablating through the upper pole to the base of the tongue,
preserving the faucial pillars. The probe ablates the tissue, while
providing simultaneous hemostasis of severed blood vessels in the
region. Similarly, adenoid hyperplasis, or nasal obstruction
leading to mouth breathing difficulty, can be treated in an
adenoidectomy by separating (e.g., resecting or ablating) the
adenoid from the base of the nasopharynx.
[0157] Other pharyngeal disorders can be treated according to the
present invention. For example, hypopharyngeal diverticulum
involves small pouches that form within the esophagus immediately
above the esophageal opening. The sac of the pouch may be removed
endoscopically according to the present invention by introducing a
rigid esophagoscope, and isolating the sac of the pouch. The
cricopharyngeus muscle is then divided, and the pouch is ablated
according to the present invention. Tumors within the mouth and
pharynx, such as hemangionmas, lymphangiomas, papillomas, lingual
thyroid tumors, or malignant tumors, may also be removed according
to the present invention.
[0158] Other procedures of the present invention include removal of
vocal cord polyps and lesions and partial or total laryngectomies.
In the latter procedure, the entire larynx is removed from the base
of the tongue to the trachea, if necessary with removal of parts of
the tongue, the pharynx, the trachea and the thyroid gland.
[0159] Tracheal stenosis may also be treated according to the
present invention. Acute and chronic stenoses within the wall of
the trachea may cause coughing, cyanosis and choking.
* * * * *