U.S. patent application number 12/335679 was filed with the patent office on 2010-06-17 for electrosurgical system with selective control of active and return electrodes.
This patent application is currently assigned to ArthroCare Corporation. Invention is credited to Hadar Cadouri, Philip M. Tetzlaff.
Application Number | 20100152726 12/335679 |
Document ID | / |
Family ID | 42241439 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100152726 |
Kind Code |
A1 |
Cadouri; Hadar ; et
al. |
June 17, 2010 |
ELECTROSURGICAL SYSTEM WITH SELECTIVE CONTROL OF ACTIVE AND RETURN
ELECTRODES
Abstract
Electrosurgical system with selective control of active and
return electrodes. At least some of the illustrative embodiments
are systems comprising an electrosurgical wand and an
electrosurgical controller. The wand comprises a non-conductive
outer surface, at least three electrodes disposed on a distal end
of the wand, and at least three electrical leads extending from a
proximal end of the wand (one electrical lead electrically coupled
to each electrode). The controller comprises a voltage generator
and a control circuit coupled between the voltage generator and the
electrodes of the wand. The control circuit is configured to:
selectively electrically couple the active terminal singly and in
combination to the electrodes of the wand; and selectively
electrically couple the return terminal singly and in combination
to electrodes of the wand.
Inventors: |
Cadouri; Hadar; (Sunnyvale,
CA) ; Tetzlaff; Philip M.; (Austin, TX) |
Correspondence
Address: |
ARTHROCARE CORPORATION;ATTN: Matthew Scheele
7500 Rialto Boulevard, Building Two, Suite 100
Austin
TX
78735-8532
US
|
Assignee: |
ArthroCare Corporation
Austin
TX
|
Family ID: |
42241439 |
Appl. No.: |
12/335679 |
Filed: |
December 16, 2008 |
Current U.S.
Class: |
606/35 ;
606/41 |
Current CPC
Class: |
A61B 2018/1467 20130101;
A61B 18/1206 20130101; A61B 2018/00345 20130101; A61B 2018/124
20130101; A61B 18/1233 20130101; A61B 2018/00577 20130101; A61B
18/1402 20130101; A61B 18/148 20130101; A61B 2218/002 20130101;
A61B 18/16 20130101; A61B 2018/1472 20130101; A61B 2018/00404
20130101; A61B 2018/00619 20130101 |
Class at
Publication: |
606/35 ;
606/41 |
International
Class: |
A61B 18/14 20060101
A61B018/14 |
Claims
1. A system comprising: a wand comprising a non-conductive outer
surface, at least three electrodes disposed on a distal end of the
wand, and at least three electrical leads extending from a proximal
end of the wand, one electrical lead electrically coupled to each
electrode; and a controller comprising: a controller connector
coupled to the electrical leads; a voltage generator configured to
generate voltage of varying amplitude, the voltage generator has an
active terminal and a return terminal; and a control circuit
coupled between the controller connector and the voltage generator;
the control circuit configured to selectively electrically couple
the active terminal singly and in combination to the electrodes of
the wand; and the control circuit configured to selectively
electrically couple the return terminal singly and in combination
to electrodes of the wand.
2. The system of claim 1 wherein the controller further comprises
an operator interface device, and wherein the control circuit is
configured to selectively electrically couple the active and return
terminals to the electrical leads based on commands received
through the operator interface.
3. The system of claim 1 further comprising a foot pedal assembly
operationally coupled to the controller, and wherein the control
circuit is configured to selectively electrically couple the active
and return terminals based on actuation of the foot pedal.
4. The system of claim 1 wherein the wand further comprises an
internal passage, and wherein at least one electrode resides within
the internal passage proximate to the distal end of the wand.
5. The system of claim 1 further comprising: a wand connector
coupled to the electrical leads, the wand connector comprising at
least three electrical pins, one pin electrically coupled to each
electrical lead; wherein the controller connector and wand
connector are configured to couple in only one orientation.
6. The system of claim 5 wherein the wand connector and controller
connector further comprise a tab and slot arrangement where the tab
and slot are configured to allow the connectors to couple in the
only one orientation.
7. The system of claim 6 wherein the tab and slot arrangement is at
least one selected from the group consisting of: the tab on the
wand connector and the slot on the controller connector; and the
tab on the controller connector and the slot on the wand
connector.
8. The system of claim 1 wherein each electrode of the defines a
surface area, and at least one electrode has a surface area less
than three-quarters the surface area of another electrode.
9. The system of claim 1 wherein distances between centers of each
electrode are constant during deployment and use.
10. An electrosurgical wand comprising: an elongate shaft that
defines a proximal end and a distal end, at least a portion of the
exterior surface comprising non-conductive material; a connector
comprising a plurality of pins; a first electrode disposed on the
distal end of the elongate shaft, and a first electrical lead
electrically coupled to the first electrode and a first pin of the
connector; a second electrode disposed on the distal end of the
elongate shaft, and a second electrical lead electrically coupled
to the second electrode and a second pin of the connector; and a
third electrode disposed on the distal end of the elongate shaft,
and a third electrical lead electrically coupled to the third
electrode and a third pin of the connector; each electrode defines
a center, and distances between centers are fixed; and wherein each
electrode is configured to be selectively coupled to a high
frequency voltage generator as an active electrode and as a return
electrode.
11. The electrosurgical wand of claim 10 further comprising an
internal passage at least partially through the elongate shaft and
having an aperture at the distal end of the elongate shaft.
12. The electrosurgical wand of claim 11 further comprising the
first electrode disposed within the internal passage.
13. The electrosurgical wand of claim 10 wherein the connector is
further configured to couple to a connector of a controller in only
one orientation.
14. The electrosurgical wand of claim 13 wherein the connector
comprises at least one selected from the group consisting of: a tab
configured to mechanically couple to a slot of the connector of the
controller; and a slot configured to mechanically couple to a tab
of the connector of the controller.
15. The electrosurgical wand of claim 10 wherein each electrode of
the wand defines a surface area, and at least one electrode has a
surface area less than three-quarters the surface area of another
electrode.
16. An electrosurgical controller comprising: a first connector
disposed on an outer surface of the electrosurgical controller, the
first connector configured to couple to a connector of an
electrosurgical wand, and the first connector comprising at least
three electrical pins; a voltage generator configured to generate a
selectable alternating current (AC) output voltage, the voltage
generator has a active terminal and a return terminal; a control
circuit coupled between the first connector and the voltage
generator, the control circuit configured to selectively
electrically couple the active terminal singly or in combination to
the electrical pins of the first connector; and the control circuit
configured to selectively electrically couple the return terminal
singly or in combination to the electrical pins of the first
connector.
17. The electrosurgical controller of claim 16 wherein the
connector is further configured to couple to the connector of an
electrosurgical wand in only one orientation.
18. The electrosurgical controller of claim 17 wherein the
connector comprises at least one selected from the group consisting
of: a tab configured to mechanically couple to a slot of the
connector of the electrosurgical wand; and a slot configured to
mechanically couple to a tab of the connector of the
electrosurgical wand.
19. The electrosurgical controller of claim 16 further comprising:
a second connector disposed on the outer surface of the
electrosurgical controller, the second connector configured to
couple to a pedal device; the control circuit is configured to
select a configuration of electrically coupling the active and
return terminals to the electrical pins based on the actuation of
the pedal.
20. The electrosurgical controller of claim 16 further comprising:
an interface panel visible on the outer surface of the
electrosurgical controller, and the interface panel electrically
coupled to the control circuit; the control circuit is configured
to select a configuration of electrically coupling the active and
return terminals to the electrical pins based on a user's
interaction with the interface panel.
21. A method comprising: treating a first portion of a target
tissue with an electrosurgical wand electrically coupled to a
controller by a connector, wherein treating the first portion
comprises generating a current path between a first electrode of
the wand as an active electrode, and a second electrode and a third
electrode of the wand as return electrodes; and without de-coupling
the connector from the controller; electrically isolating the
first, second, and third electrodes; activating the third electrode
of the electrosurgical wand as an active electrode; activating a
fourth electrode of the electrosurgical wand and at least one of
the first and second electrodes as return electrodes, the fourth
electrode different than the first and second electrodes; and then
treating a second portion of the target tissue with the
electrosurgical wand, wherein treating the second portion comprises
generating a current path between the third and fourth electrodes
and the at least one of the first and second electrodes.
22. The method of claim 21 wherein electrically isolating and
activating further comprises interacting with an operator interface
device on a controller.
23. The method of claim 21 wherein electrically isolating and
activating further comprises interacting with a foot pedal
device.
24. The method of claim 21 further comprising, concurrently with
activating the third electrode as an active electrode, activating a
fifth electrode of the electrosurgical wand as an active electrode,
the fifth electrode different than the first and second
electrode.
25. An electrosurgical wand comprising: an elongate shaft that
defines a proximal end and a distal end; a connector comprising a
plurality of pins; at least two first electrodes disposed on the
distal end of the elongate shaft; at least two second electrodes
disposed on the distal end of the elongate shaft; wherein each of
the electrodes is electrically coupled to one of the plurality of
pins via an electrical lead; wherein each of the at least two first
electrodes have a surface area less than three-quarters the surface
area of each of the at least two second electrodes; and wherein in
a first mode the at least two first electrodes are coupled to a
high frequency voltage generator as active electrodes and the at
least two second electrodes are coupled to the voltage generator as
return electrodes.
26. The electrosurgical wand of claim 25 wherein in a second mode
at least one of the first electrodes is electrically isolated from
the voltage generator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
BACKGROUND
[0002] Electrosurgical systems are used by physicians to perform
specific functions during surgical procedures. For example, in an
ablation mode electrosurgical systems use high frequency electrical
energy to remove soft tissue such as sinus tissue, adipose tissue,
or meniscus, cartilage and/or sinovial tissue in a joint. In a
coagulation mode, the electrosurgical device may aid the surgeon in
reducing internal bleeding by assisting in the coagulation and/or
sealing of vessels.
[0003] However, while the mode of operation of an electrosurgical
system is controlled to some extent by the voltage applied to the
electrodes of an electrosurgical wand, the physical size and
placement of electrodes on the electrosurgical wand also affect
operation. For example, in an ablation mode, a relatively small
active electrode conducting current to a proximally-located larger
return electrode may be preferred to very precisely control the
tissue ablated. By contrast, in a coagulation mode, relatively
large active and return electrodes, perhaps along the side of an
electrosurgical wand and yet still proximate to the distal end, may
be preferred to ensure larger surface area for coagulation.
[0004] In some situations, a surgeon may choose to change
electrosurgical wands as between, for example, an ablation of
tissue and a coagulation procedure. In other situations, an
electrosurgical system may have the ability to change between an
ablation and coagulation mode by controlling the active electrode
on the electrosurgical wand and/or the voltage output of the
controller. However, any advance that increases the functionality
of an electrosurgical system provides competitive advantage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] For a detailed description of exemplary embodiments of the
invention, reference will now be made to the accompanying drawings
in which:
[0006] FIG. 1 shows an electrosurgical system in accordance with at
least some embodiments;
[0007] FIG. 2 shows a perspective view a portion of a wand in
accordance with at least some embodiments;
[0008] FIG. 3 shows a cross-sectional view of a wand in accordance
with at least some embodiments;
[0009] FIG. 4 shows both an elevational end-view (left) and a
cross-sectional view (right) of a wand connector in accordance with
at least some embodiments;
[0010] FIG. 5 shows both an elevational end-view (left) and a
cross-sectional view (right) of a controller connector in
accordance with at least some embodiments;
[0011] FIG. 6 shows an electrical block diagram of an
electrosurgical controller in accordance with at least some
embodiments; and
[0012] FIG. 7 shows a method in accordance with at least some
embodiments.
NOTATION AND NOMENCLATURE
[0013] Certain terms are used throughout the following description
and claims to refer to particular system components. As one skilled
in the art will appreciate, companies that design and manufacture
electrosurgical systems may refer to a component by different
names. This document does not intend to distinguish between
components that differ in name but not function.
[0014] In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ." Also, the term "couple" or "couples" is intended to mean
either an indirect or direct connection. Thus, if a first device
couples to a second device, that connection may be through a direct
connection or through an indirect electrical connection via other
devices and connections.
[0015] Reference to a singular item includes the possibility that
there are plural of the same items present. More specifically, as
used herein and in the appended claims, the singular forms "a,"
"an," "said" and "the" include plural references unless the context
clearly dictates otherwise. It is further noted that the claims may
be drafted to exclude any optional element. As such, this statement
serves as antecedent basis for use of such exclusive terminology as
"solely," "only" and the like in connection with the recitation of
claim elements, or use of a "negative" limitation. Lastly, it is to
be appreciated that unless defined otherwise, all technical and
scientific terms used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs.
[0016] "Active electrode" shall mean an electrode of an
electrosurgical wand which produces an electrically-induced
tissue-altering effect when brought into contact with, or close
proximity to, a tissue targeted for treatment, and/or an electrode
having a voltage induced thereon by a voltage generator, power
generator, or other suitable energy source.
[0017] "Return electrode" shall mean an electrode of an
electrosurgical wand which serves to provide a current flow path
for electrons with respect to an active electrode, and/or an
electrode of an electrical surgical wand which may not itself
produce an electrically-induced tissue-altering effect on tissue
targeted for treatment.
[0018] "Proximate" shall mean, in relation to spacing of electrodes
on a wand, within 5 centimeters, and in some cases less than 1
centimeter.
[0019] Where a range of values is provided, it is understood that
every intervening value, between the upper and lower limit of that
range and any other stated or intervening value in that stated
range is encompassed within the invention. Also, it is contemplated
that any optional feature of the inventive variations described may
be set forth and claimed independently, or in combination with any
one or more of the features described herein.
[0020] All existing subject matter mentioned herein (e.g.,
publications, patents, patent applications and hardware) is
incorporated by reference herein in its entirety except insofar as
the subject matter may conflict with that of the present invention
(in which case what is present herein shall prevail). The
referenced items are provided solely for their disclosure prior to
the filing date of the present application. Nothing herein is to be
construed as an admission that the present invention is not
entitled to antedate such material by virtue of prior
invention.
DETAILED DESCRIPTION
[0021] Before the various embodiments are described in detail, it
is to be understood that this invention is not limited to
particular variations set forth herein as various changes or
modifications may be made, and equivalents may be substituted,
without departing from the spirit and scope of the invention. As
will be apparent to those of skill in the art upon reading this
disclosure, each of the individual embodiments described and
illustrated herein has discrete components and features which may
be readily separated from or combined with the features of any of
the other several embodiments without departing from the scope or
spirit of the present invention. In addition, many modifications
may be made to adapt a particular situation, material, composition
of matter, process, process act(s) or step(s) to the objective(s),
spirit or scope of the present invention. All such modifications
are intended to be within the scope of the claims made herein.
[0022] FIG. 1 illustrates an electrosurgical system 100 in
accordance with at least some embodiments. In particular, the
electrosurgical system comprises an electrosurgical instrument 102
(hereinafter "wand") coupled to an electrosurgical controller 104
(hereinafter "controller"). The wand 102 comprises an elongate
shaft 106 that includes distal end 108 where at least some
electrodes are disposed. In certain embodiments, the elongate shaft
106 comprises a conductive material, but is covered with an
insulating material. The elongate shaft 106 further defines a
handle or proximal end 110, where a user may grip the wand 102
during a surgical procedure. The wand 102 further comprises a
flexible multi-conductor cable 112 housing a plurality of
electrical leads (not specifically shown in FIG. 1), and the
flexible multi-conductor cable 112 terminates in a wand connector
114. Though not expressly shown in the FIG. 1, in some embodiments
wand 102 may include an internal passage or lumen fluidly coupled
to a flexible tubular member 116. The internal passage and flexible
tubular member 116 may be used as a conduit to supply conductive
fluid, a non-conductive irrigant, or other desired fluid to be
proximate to the distal end 108, or the internal passage and
flexible tubular member may be used to aspirate the area proximate
to the distal end 108 of the wand 102.
[0023] As shown in FIG. 1, the wand 102 couples to the controller
104, such as by a controller connector 120, on an outer surface 122
(in the illustrative case of FIG. 1 the front surface). A display
device or interface panel 124 is visible through the outer surface
122, and in some embodiments a user may select operational modes of
the controller 104 by way of the interface device 124 and related
buttons 126. The interaction of the interface device 124 and
buttons 126 is discussed more thoroughly below with respect to FIG.
5.
[0024] Still referring to FIG. 1, in some embodiments the
electrosurgical system 100 may also comprise a foot pedal assembly
130. The foot pedal assembly 130 may comprise one or more pedal
devices 132 and 134, a flexible multi-conductor cable 136 and a
pedal connector 138. While only two pedal devices 132, 134 are
shown, any number of pedal devices may be implemented. The outer
surface 122 of the controller 104 may comprise a corresponding
connector 140 that couples to the connector 138. A physician may
use the foot pedal assembly 130 to control various aspects of the
controller 104, such as the operational mode. For example, a pedal
device, such as pedal device 132, may be used for on-off control of
the application of radio frequency (RF) energy to the wand 102, and
more specifically for control of energy in an ablation mode. A
second pedal device, such as pedal device 134, may be used to
control and/or set the operational mode of the electrosurgical
system. For example, actuation of pedal device 134 may switch
between ablation mode and a coagulation mode. Alternatively, pedal
device 134 may be used to control the application of RF energy to
wand 102 in a coagulation mode. The pedal devices may also be used
to change the voltage level delivered to wand 102. As another
example, actuation of the pedal device 134 may change the
configuration of active and return electrodes on the wand 102.
[0025] The electrosurgical system 100 of the various embodiments
may have a variety of operational modes. One such mode employs
Coblation.RTM. technology. In particular, the assignee of the
present disclosure is the owner of Coblation.RTM. technology.
Coblation.RTM. technology involves the application of a RF signal
between one or more active electrodes and one or more return
electrodes of the wand 102 to develop high electric field
intensities within conductive fluid in the vicinity of the target
tissue sufficient to volumetrically dissociate or otherwise ablate
tissue. The electric field intensities may be sufficient to
vaporize an electrically conductive fluid over at least a portion
of the one or more active electrodes in the region between the one
or more active electrodes and the target tissue. The electrically
conductive fluid may be inherently present in the body, such as
blood, or in some cases extracelluar or intracellular fluid. In
other embodiments, the electrically conductive fluid may be a
liquid or gas, such as isotonic saline. In some embodiments the
electrically conductive fluid is delivered in the vicinity of the
active electrodes and/or to the target site by the wand 102, such
as by way of the internal passage and flexible tubular member
116.
[0026] When the electrically conductive fluid is heated to the
point that the atoms of the fluid vaporize faster than the atoms
recondense, a gas is formed. When sufficient energy is applied to
the gas, the atoms collide with each other causing a release of
electrons in the process, and an ionized gas or plasma is formed
(the so-called "fourth state of matter"). Stated otherwise, plasmas
may be formed by heating a gas and ionizing the gas by driving an
electric current through the gas, or by directing electromagnetic
waves into the gas. The methods of plasma formation give energy to
free electrons in the plasma directly, electron-atom collisions
liberate more electrons, and the process cascades until the desired
degree of ionization is achieved. A more complete description of
plasma can be found in Plasma Physics, by R. J. Goldston and P. H.
Rutherford of the Plasma Physics Laboratory of Princeton University
(1995), the complete disclosure of which is incorporated herein by
reference.
[0027] As the density of the plasma becomes sufficiently low (i.e.,
less than approximately 1020 atoms/cm.sup.3 for aqueous solutions),
the electron mean free path increases such that subsequently
injected electrons cause impact ionization within the plasma. When
the ionic particles in the plasma layer have sufficient energy
(e.g., 3.5 electron-Volt (eV) to 5 eV), collisions of the ionic
particles with molecules that make up the target tissue break
molecular bonds of the target tissue, dissociating molecules into
free radicals which then combine into gaseous or liquid species.
Often, the electrons in the plasma carry the electrical current or
absorb the electromagnetic waves and, therefore, are hotter than
the ionic particles. Thus, the electrons, which are carried away
from the target tissue toward the active or return electrodes,
carry most of the plasma's heat, enabling the ionic particles to
break apart the target tissue molecules in a substantially
non-thermal manner.
[0028] By means of the molecular dissociation (as opposed to
thermal evaporation or carbonization), the target tissue is
volumetrically removed through molecular dissociation of larger
organic molecules into smaller molecules and/or atoms, such as
hydrogen, oxygen, oxides of carbon, hydrocarbons and nitrogen
compounds. The molecular dissociation completely removes the tissue
structure, as opposed to dehydrating the tissue material by the
removal of liquid within the cells of the tissue and extracellular
fluids, as occurs in related art electrosurgical desiccation and
vaporization. A more detailed description of the molecular
dissociation can be found in commonly assigned U.S. Pat. No.
5,697,882 the complete disclosure of which is incorporated herein
by reference.
[0029] In addition to the Coblation.RTM. mode, the electrosurgical
system 100 of FIG. 1 is also useful for sealing larger arterial
vessels (e.g., on the order of about 1 mm in diameter), when used
in what is known as a coagulation mode. Thus, the system of FIG. 1
may have an ablation mode where RF energy at a first voltage is
applied to one or more active electrodes sufficient to effect
molecular dissociation or disintegration of the tissue, and the
system of FIG. 1 has a coagulation mode where RF energy at a
second, lower voltage is applied to one or more active electrodes
(either the same or different electrode(s) as the ablation mode)
sufficient to heat, shrink, seal, fuse, and/or achieve homeostasis
of severed vessels within the tissue.
[0030] The energy density produced by electrosurgical system 100 at
the distal end 108 of the wand 102 may be varied by adjusting a
variety of factors, such as: the number of active electrodes;
electrode size and spacing; electrode surface area; asperities
and/or sharp edges on the electrode surfaces; electrode materials;
applied voltage; current limiting of one or more electrodes (e.g.,
by placing an inductor in series with an electrode); electrical
conductivity of the fluid in contact with the electrodes; density
of the conductive 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 electrosurgical system 100 may be configured
to produce energy sufficient to break the molecular bonds of
certain tissue but insufficient to break the molecular bonds of
other tissue. For example, fatty tissue (e.g., adipose) has double
bonds that require an energy level higher than 4 eV to 5 eV (i.e.,
on the order of about 8 eV) to break. Accordingly, the
Coblation.RTM. technology in some operational modes does not ablate
such fatty tissue; however, the Coblation.RTM. technology at the
lower energy levels may be used to effectively ablate cells to
release the inner fat content in a liquid form. Other modes may
have increased energy such that the 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 electrodes).
[0031] A more complete description of the various phenomena can be
found in commonly assigned U.S. Pat. Nos. 6,355,032, 6,149,120 and
6,296,136, the complete disclosures of which are incorporated
herein by reference.
[0032] FIG. 2 illustrates the distal end 108 of wand 102. In some
embodiments, distal end 108 of wand 102 comprises electrode support
member 105 that may be constructed of an inorganic insulating
(i.e., non-conductive) material. The distal end 108 further
comprises a plurality of electrodes. For example, in the
illustrative case of FIG. 2, seven electrodes 202, 204, 206, 208,
210, 212 and 214 are shown; however, any suitable configuration of
three or more electrodes may be equivalently used. As illustrated
in FIG. 2, the electrodes may take many forms. Electrodes 202, 204
and 206 are illustrative of wire-type electrodes that protrude
slightly from the end 216 of electrode support member 105. The
wire-type electrodes 202, 204 and 206 may be used, for example,
singly or in combination to be the active electrodes to which the
RF energy is applied in the ablation mode. Electrodes 208, 210 are
disposed on a radial or side surface 218 of the distal end 108, and
the electrodes 208, 210 span a certain circumferential distance.
Electrodes 212, 214 are similar to electrodes 208, 210, but span a
smaller circumferential distance. The electrodes 208, 210, 212 and
214 may be used in some modes as return electrodes for ablation,
and in other modes may be the active and/or return electrodes in
the coagulation mode. Other electrode types, such as button
electrodes (i.e., round electrodes), arrays of button electrodes,
or screen electrodes, may be equivalently used. Alternatively, the
disposition of electrodes may also be changed such that smaller
electrodes are disposed on a side surface and not on an end of wand
102.
[0033] Still referring to FIG. 2, in some embodiments the wand 102
includes an internal lumen 250 that fluidly couples to the flexible
tubular member 116 (FIG. 1). In some modes of operation, the
internal lumen 250 may preferably be used to supply conductive
fluid to the target area. In other modes of operation, the internal
lumen 250 may be used to aspirate the area near the distal end 108
of the wand 102, such as when sufficient conductive fluid is
already present at the target location and ablation is taking
place, or to remove byproducts of the ablation process including
fluid, gas bubbles, or particles of tissue.
[0034] In accordance with the various embodiments, while a wand 102
may be designed to have a multitude of electrode types and
arrangements, in at least some embodiments the electrodes are in a
fixed relationship for any one design. For example, the
center-to-center distance "D" of illustrative electrodes 212 and
214 is set by the design of the particular wand 102, and remains
constant as between use and non-use. Similar fixed relationships
exist between all the illustrative electrodes of wand 102.
Furthermore, while a wand 102 may be designed to have a multitude
of exposed electrode surface areas, in at least some embodiments at
least one electrode has a surface area less than three-quarters the
surface area of another electrode. In the illustrative case of FIG.
2, for example, electrode 212 as shown has a surface area less than
three-quarters of either electrode 208 or 210. Thus, in accordance
with the various embodiments, one is able not only to select
particular electrodes to control the relationship of the electrodes
from a distance perspective, but is also able to select electrodes
to control the relative cumulative proportion of surface area
between the active electrodes and the return electrodes. For
example, in a first mode, a user may select an active electrode and
a return electrode having the same surface area (e.g., electrodes
208 and 210); however, in a second mode the user may select an
active electrode and a return electrode having different sizes
(e.g., electrode 212 as an active electrodes and electrode 210 as a
return electrodes).
[0035] In at least some embodiments, in ablation modes (using, for
example, Coblation.RTM. technology as discussed herein) the one or
more return electrodes are spaced proximally from the one or more
active electrodes a suitable distance to avoid electrical shorting
between the electrodes when in the presence of electrically
conductive fluid. In many cases, the distal edge of the exposed
surface of the closest return electrode is about between about 0.5
milli-meters (mm) to about 25 mm from the proximal edge of the
exposed surface of the closest active electrode, and in some
embodiments between about 1.0 mm to 5.0 mm. For example, electrode
208 may be selected to be a return electrode and electrode 210 may
be selected to be an active electrode, and the axial distance
between electrode 208 and 210 may be in the range of 0.5 mm to 25
mm. As yet another example using the Coblation.RTM. technology,
one, two or all the wire-type electrodes 202, 204 and 206 may be
active, and electrode 210 (which was the active electrode in the
previous example) may be the return electrode. In the second
example, the axial distance between the active electrode(s) and the
return electrode 210 may be 0.5 mm to 25 mm. As yet another
example, electrodes 202 and 206 may be return electrodes, with any
of the electrodes 204, 208, or 210 being active. The distances may
vary with different voltage ranges, conductive fluids, and
proximity of tissue structures to available active and return
electrodes. In some embodiments, return electrode may have an
exposed length in the range of about 1 mm to 20 mm.
[0036] As alluded to by the examples of preceding paragraph, in
accordance with at least some embodiments, any single electrode or
combination of multiple electrodes may be selected as the active
electrode for a particular mode of operation. Likewise in
accordance with at least some embodiments, any single electrode or
combination of multiple electrodes may be selected as the return
electrode for a particular mode of operation. However, in any
scenario discussed above, at least one electrode shall be selected
as an active electrode and at least one electrode shall be selected
as a return electrode. It follows that, in accordance with various
embodiments, most if not all electrodes of wand 102 are preferably
electrically isolated from each other, and thus have individual
electrical leads that run from each electrode to the wand connector
114.
[0037] FIG. 3 shows a cross-sectional view of wand 102 in
accordance with at least some embodiments. In particular, FIG. 2
illustrates the elongate shaft 106 comprising distal end 108 and
proximal end 110. Distal end 108 comprises a plurality of
electrodes 300, and while the electrodes 300 are similar to the
electrodes of FIG. 2, electrodes 300 are not necessarily the same
as those of FIG. 2. In accordance with the various embodiments
where any electrode 300 may be selected singly or in combination
with other electrodes to be active electrode(s), and likewise any
electrode 300 may be selected singly or in combination with other
electrodes 300 to be the return electrode(s), each electrode 300
has an electrical lead associated therewith that runs through the
elongate shaft 106 to the flexible multi-conductor cable 112. In
particular, electrode 300A has dedicated electrical lead 302A which
runs within the elongate shaft to the become part of cable 112.
Similarly, electrode 300B has dedicated electrical lead 302B which
runs within the elongate shaft 106 to become part of cable 112.
Illustrative electrodes 300C and 300D likewise have dedicated
electrical leads 302C and 302D which run within the elongate shaft
106 to become part of cable 112. In some embodiments, the elongate
shaft 106 has dedicated internal passages (in addition to internal
lumen 250) through which the electrical leads 302 run. In other
embodiments, the electrical leads 302 may be cast within the
material that makes up the elongate shaft.
[0038] FIG. 3 also illustrates internal lumen 250 having an
aperture 304 fluidly coupled to the flexible tubular member 116 on
the proximal end 110. In other embodiments, the fluid coupling of
the internal lumen 250 to the flexible tubular member 116 may be
between the distal end 108 and proximal end 110. The internal lumen
250 is used in some embodiments to supply conductive fluid through
the aperture 302 to the target area, and in other embodiments the
internal lumen 250 is used for aspiration of ablated tissue
fragments and/or molecules. In some embodiments, an electrode 300D
may be disposed within the internal lumen 250 proximate to the
aperture 304. An electrode 300D within the internal lumen 250 may,
for example, be selected as either an active or return electrode in
an ablation mode, and may aid in disassociation of tissue pieces
into smaller pieces during ablation and aspiration procedures.
[0039] The power provided to the wand 102 may be current limited or
otherwise controlled so that undesired heating of the target tissue
or surrounding (non-target) tissue does not occur. In some
embodiments, current limiting inductors are placed in series with
some or all the electrodes, where the inductance of each inductor
is in the range of 10 micro-Henries (pH) to 50,000 pH, depending on
the electrical properties of the target tissue, the desired tissue
heating rate and the operating frequency. Alternatively,
inductor-capacitor (LC) circuit structures may be employed, as
described 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. The current-limiting
resistors will have a large positive temperature coefficient of
resistance so that, as the current level begins to rise for any
individual active electrode in contact with a low resistance medium
(e.g., saline or blood), the resistance of the current limiting
resistor increases significantly, thereby reducing the power
delivery from the active electrode into the low resistance medium.
In some embodiments, the current limited devices may reside within
the elongate shaft 106, or may reside within the flexible cable
112.
[0040] As illustrated in FIG. 1, flexible multi-conductor cable 112
(and more particularly its constituent electrical leads 302) couple
to the wand connector 114. Wand connector 114 couples to the
controller 104, and more particularly the controller connector 120.
FIG. 4 shows both a cross-sectional view (right) and an end
elevation view (left) of wand connector 114 in accordance with at
least some embodiments. In particular, wand connector 114 comprises
a tab 400. Tab 400 works in conjunction with a slot on controller
connector 120 (shown in FIG. 5) to ensure that the wand connector
114 and controller connector 120 only couple in one relative
orientation. The illustrative wand connector 114 further comprises
a plurality of electrical pins 402 protruding from wand connector
114. The electrical pins 402 are coupled one each to a single
electrical lead 302. Stated otherwise, each electrical pin 402
couples to a single electrical lead 302, and thus each illustrative
electrical pin 402 couples to a single electrode 300 (FIG. 3).
While FIG. 4 shows only four illustrative electrical pins, in some
embodiments up to 26 or more electrical pins may be present in the
wand connector 114.
[0041] FIG. 5 shows both a cross-sectional view (right) and an end
elevation view (left) of controller connector 120 in accordance
with at least some embodiments. In particular, controller connector
120 comprises a slot 500. Slot 500 works in conjunction with a tab
400 on wand connector 114 (shown in FIG. 4) to ensure that the wand
connector 114 and controller connector 120 only couple in one
orientation. The illustrative controller connector 120 further
comprises a plurality of electrical pins 502 residing with
respective holes of controller connector 120. The electrical pins
502 are each individually coupled to a relay within the controller
104 (discussed more thoroughly below). When wand connector 114 and
controller connector 120 are coupled, each electrical pin 502
couples to a single electrical pin 402, and thus each illustrative
electrical pin 502 couples to a single electrode 300 (FIG. 3).
While FIG. 5 shows only four illustrative electrical pins, in some
embodiments as many as 26 or more electrical pins may be present in
the wand connector 120.
[0042] While illustrative wand connector 114 is shown to have the
tab 400 and male electrical pins 402, and controller connector 120
is shown to have the slot 500 and female electrical pins 502, in
alternative embodiments the wand connector has the female
electrical pins and slot, and the controller connector 120 has the
tab and male electrical pins. In other embodiments, the arrangement
of the pins within the connectors may enable only a single
orientation for connection of the connectors, and thus the tab and
slot arrangement may be omitted. In yet still other embodiments,
other suitable mechanical arrangements to ensure the wand connector
and controller connector couple in only one orientation may be
equivalently used.
[0043] FIG. 6 illustrates a controller 104 in accordance with at
least some embodiments. In particular, the controller 104 in
accordance with at least some embodiments comprises a processor
600. The processor 600 may be a microcontroller, and therefore the
microcontroller may be integral with read-only memory (ROM) 602,
random access memory (RAM) 604, digital-to-analog converter (D/A)
606, digital outputs (D/O) and digital inputs (D/I) 610. The
processor 600 may further provide one or more externally available
peripheral busses, such as a serial bus (e.g., I.sup.2C), parallel
bus, or other bus and corresponding communication mode. The
processor 600 may further be integral with a communication logic
612 to enable the processor 600 to communicate with external
devices, as well as internal devices, such as display device 124.
Although in some embodiments the controller 104 may implement a
microcontroller, in yet other embodiments the processor 600 may be
implemented as a standalone central processing unit in combination
with individual RAM, ROM, communication, D/A, D/O and D/I devices,
as well as communication port hardware for communication to
peripheral components.
[0044] ROM 602 stores instructions executable by the processor 600.
In particular, the ROM 602 may comprise a software code that
implements the various embodiments of selectively coupling the
electrodes of the wand to the voltage generator 616, as well as
interfacing with the user by way of the display device 614 and/or
the foot pedal assembly 130 (FIG. 1) and/or a speaker assembly (not
specifically shown). The RAM 604 may be the working memory for the
processor 600, where data may be temporarily stored and from which
instructions may be executed. Processor 600 couples to other
devices within the controller 104 by way of the D/A converter 606
(i.e., the voltage generator 616), digital outputs 608 (i.e.,
electrically controlled switches 620), digital inputs 610 (i.e.,
push button switches 126, and the foot pedal assembly 130 (FIG.
1)), communication device 612 (i.e., display device 124), and other
peripheral devices. The other peripheral devices may comprise
electrode relays and/or switches, devices to set desired voltage
generator 616 output voltage, and other secondary devices internal
to the generator.
[0045] Voltage generator 616 generates selectable alternating
current (AC) voltages that are applied to the electrodes of the
wand 102. In some embodiments, the voltage generator defines an
active terminal 624 and a return terminal 626. The active terminal
624 is the terminal upon which the voltages and electrical currents
are induced by the voltage generator 616, and the return terminal
626 provides a return path for electrical currents. In some
embodiments, the return terminal 626 may provide a common or ground
being the same as the common or ground within the balance of the
controller 104 (e.g., the common 628 used on push-buttons 622), but
in other embodiments the voltage generator 616 may be electrically
"floated" from the balance of the supply power in the controller
104, and thus the return terminal 626, when measured with respect
to the common (e.g., common 628) within the controller 104, may
show a voltage difference; however, an electrically floated voltage
generator 616 and thus the potential for voltage readings on the
return terminal 626 does not negate the return terminal status of
the terminal 626 relative to the active terminal 624.
[0046] The voltage generated and applied between the active
terminal 624 and return terminal 626 by the voltage generator 616
is a RF signal that, in some embodiments, has a frequency of
between about 5 kilo-Hertz (kHz) and 20 Mega-Hertz (MHz), in some
cases 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. In some applications, a
frequency of about 100 kHz is useful because target tissue
impedance is much greater at 100 kHz. In other applications, such
as procedures in or around the heart or head and neck, higher
frequencies may be desirable (e.g., 400-600 kHz) to reduce low
frequency current flow into the heart or the nerves of the head and
neck.
[0047] The RMS (root mean square) voltage generated by the voltage
generator 616 may be in the range from about 5 Volts (V) to 1000 V,
preferably being in the range from about 10 V to 500 V, often
between about 10 V to 400 V depending on the active electrode 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). The peak-to-peak voltage
generated by the voltage generator 616 for ablation or cutting in
some embodiments is a square wave form in the range of 10 V to 2000
V and in some cases in the range of 100 V to 1800 V and in other
cases in the range of about 28 V to 1200 V, often in the range of
about 100 V to 320V peak-to-peak (again, depending on the electrode
size, number of electrodes the operating frequency and the
operation mode). Lower peak-to-peak voltage is used for tissue
coagulation, thermal heating of tissue, or collagen contraction and
may be in the range from 50 V to 1500V, preferably 100 V to 1000 V
and more preferably 60 V to 130 V peak-to-peak (again, these values
are computed using a square wave form).
[0048] The voltage and current generated by the voltage generator
616 may be delivered in a series of voltage pulses or AC voltage
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 pulsed about 10 Hz to 20 Hz). In addition, the duty cycle
(i.e., cumulative time in any one-second interval that energy is
applied) of the square wave voltage produced by the voltage
generator 616 is on the order of about 50% for some embodiments as
compared with pulsed lasers which may have a duty cycle of about
0.0001%. Although square waves are generated and provided in some
embodiments, the various embodiments may be equivalently
implemented with many applied voltage waveforms (e.g., sinusoidal,
triangular).
[0049] Still referring to the voltage generator 616, the voltage
generator 616 delivers average power levels ranging from several
milliwatts to hundreds of watts per electrode, depending on the
voltage applied to the target electrode for the target tissue being
treated, and/or the maximum allowed temperature selected for the
wand 102. The voltage generator 616 is configured to enable a 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 voltage
generator 616 may have a filter that filters leakage voltages at
frequencies below 100 kHz, particularly voltages around 60 kHz.
Alternatively, a voltage generator 616 configured for higher
operating frequencies (e.g., 300 kHz to 600 kHz) may be used in
certain procedures in which stray low frequency currents may be
problematic. A description of one suitable voltage generator 616
can be found in commonly assigned U.S. Pat. Nos. 6,142,992 and
6,235,020, the complete disclosure of both patents are incorporated
herein by reference for all purposes.
[0050] In accordance with at least some embodiments, the voltage
generator 616 is configured to limit or interrupt current flow when
low resistivity material (e.g., blood, saline or electrically
conductive gel) causes a lower impedance path between the return
electrode(s) and the active electrode(s). Further still, in some
embodiments the voltage generator 616 is configured by the user to
be a constant current source (i.e., the output voltage changes as
function of the impedance encountered at the wand 102).
[0051] In some embodiments, the various operational modes of the
voltage generator 616 may be controlled by way of digital-to-analog
converter 606. That is, for example, the processor 600 may control
the output voltage by providing a variable voltage to the voltage
generator 616, where the voltage provided is proportional to the
voltage generated by the voltage generator 616. In other
embodiments, the processor 600 may communicate with the voltage
generator by way of one or more digital output signals from the
digital output 608 device, or by way of packet based communications
using the communication 612 device (the alternative embodiments not
specifically shown so as not to unduly complicate FIG. 6).
[0052] In addition to controlling the output of the voltage
generator 616, in accordance with the various embodiments the
controller 104 is also configured to selectively electrically
couple the active terminal 624 singly or in combination to the
electrodes of the wand (by way of the electrical pins of the
controller connector 120). Likewise, in the various embodiments,
the controller 104 is also configured to selectively electrically
couple the return terminal 626 singly or in combination to the
electrodes of the wand (again by way of the electrical pins of the
controller connector 120). In order to perform the selective
coupling, the controller 104 implements a control circuit 630,
shown in dashed lines in FIG. 6. For convenience of the figure the
control circuit has two parts, 630A and 630B, but the two parts
nevertheless comprise the control circuit 630. In particular, the
control circuit 630 comprises the processor 600, voltage controlled
switches 620 and mechanic relays R1-R6. The coils of relays R1-R6
are shown within portion 630A, while the contacts for each
mechanical relay are shown within portion 630B. The correlation
between the coils for mechanical relays R5 and R6 and the contacts
for mechanical relays R5 and R6 are shown by dashed arrow-headed
lines 650 and 652 respectively. The correlation between the
remaining coils and contacts is not specifically shown with
arrow-headed lines so as not to unduly complicate the figure;
however, the correlation is noted by way of corresponding
references.
[0053] In accordance with at least some embodiments, at least three
electrodes of the wand 102 are separately electrically coupled to
the controller 104. Thus, the description of FIG. 6 is based on
three separately electrically coupled electrodes, but it will be
understood that three or more separately electrically coupled
electrodes may be used. The electrical pin of the controller
connector 120 for each electrode is configured to be selectively
coupled to either the active terminal 624 or the return terminal
626. For example, the electrical lead configured to couple
illustrative electrode 1 of FIG. 6 couples to the normally open
contact terminals for the mechanical relays R1 and R2. The other
side of the normally open contact for mechanical relay R1 couples
to the active terminal 624, while the other side of the normally
open contact for the mechanical relay R2 couples to the return
terminal 626. Thus, by selectively activating mechanical relay R1
or mechanical relay R2, electrode 1 can be either an active or
return electrode in the surgical procedure. Alternatively, both
relays can remain inactivated, and thus electrode 1 may remain
unconnected.
[0054] Similarly, the electrical lead configured to couple
illustrative electrode 2 couples to the normally open contact
terminals for the mechanical relays R3 and R4. The other side of
the normally open contact for mechanical relay R3 couples to the
active terminal 624, while the other side of the normally open
contact for the mechanical relay R4 couples to the return terminal
626. Thus, by selectively activating mechanical relay R3 or
mechanical relay R4, electrode 2 can be either an active or return
electrode in the surgical procedure. Alternatively, both relays R3
and R4 can remain inactivated, and thus electrode 2 may remain
unconnected. Finally with respect to the illustrative electrode 3,
the electrical lead configured to couple to illustrative electrode
3 couples to the normally open contact terminals for the mechanical
relays R5 and R6. The other side of the normally open contact for
mechanical relay R5 couples to the active terminal 624, while the
opposite side of the normally open contact for the mechanical relay
R6 couples to the return terminal 626. Thus, by selectively
activating mechanical relay R5 or mechanical relay R6, electrode 3
can be either an active or return electrode in the surgical
procedure. Alternatively, both relays can remain inactivated, and
thus electrode 3 may remain unconnected.
[0055] In accordance with at least some embodiments, mechanical
relays R1-R6 are selectively activated (by way of their respective
coils 634) by voltage controlled switches 620. For example, when
the control circuit 630 desires to couple the active terminal to
electrode 1, the voltage controlled switch 620A is activated, which
allows current to flow through the coil 634A of mechanical relay
R1. Current flow through the coil 634 activates the relay, thus
closing (making conductive) the normally open contacts. Similarly,
the control circuit 630 may selectively activate any of the voltage
controlled switches 620, which in turn activate respective
mechanical relays R1-R6. In accordance with at least some
embodiments, each mechanical relay is a part number JW1FSN-DC 12V
relay available from Panasonic Corporation of Secaucus, N.J.;
however, other mechanical relays may be equivalently used.
Moreover, while FIG. 6 illustrates the use of field effect
transistors as the voltage controlled switches 620 to control the
current flow through coils of the mechanical relays, other devices
(e.g., transistors, or if coils use AC driving current, triacs) may
be equivalently used. Further still, in embodiments where the
digital outputs 608 have sufficient current carrying capability,
the voltage controlled switches may be omitted.
[0056] The selection of which electrode(s) of the wand 102 be
active electrodes, and which electrode(s) to be return electrodes,
may be determined in any of several forms. For example, a user may
observe options for electrode selection by way of the display
device 124, and may select particular options by interaction with
the controller 104 by way of push buttons 126. In other
embodiments, selection of particular electrodes as active or return
may be made way of foot pedal assembly 102. In the embodiments
illustrated in FIG. 6, selection of particular electrodes as active
or return is conveyed to the illustrative processor 600 by way of
the digit inputs 610; however, FIG. 6 is merely illustrative of a
control circuit 630 implemented using a processor. In other
embodiments, the processor may be omitted and the logic implemented
by way of discrete logic devices.
[0057] In order to illustrate the flexibility of the
electrosurgical system in accordance with the various embodiments,
the table below shows the possible status of each electrode in a
system having an illustrative three electrodes:
TABLE-US-00001 TABLE (1) Electrode 1 Electrode 2 Electrode 3
Isolated Isolated Isolated Return Active Active Return Return
Active Active Return Return Active Active Return Active Isolated
Return Return Isolated Active Isolated Active Return Isolated
Return Active Active Return Isolated Return Active Isolated
Where "Isolated" indicates that a particular electrode is connected
to neither the active terminal nor the return terminal of the
voltage generator, "Active" means that the electrode is connected
to the active terminal of the voltage generator, and "Return" means
that the electrode is coupled to the return terminal of the voltage
generator. It should be noted that in certain configurations an
"isolated" electrode may still attract current and may heat up,
acting essentially as an antennae. In this scenario, the isolated
state may be referred to as "floating." Table (1) illustrates that,
in accordance with at least some embodiments, an electrode of the
wand can be an active electrode or a return electrode, and that
depending on the mode of operation, multiple electrodes may be the
active electrode at any one time. Likewise, multiple electrodes may
be a return electrode at any one time.
[0058] FIG. 7 illustrates a method in accordance with at least some
embodiments. In particular, the method starts (block 700) and
proceeds to treating a first portion of a target tissue with an
electrosurgical wand electrically coupled to a controller by a
connector by generating a current path between a first electrode of
the wand as an active electrode, and a second electrode of the wand
as a return electrode (block 704), for example, during a molecular
disassociation. Then, and without de-coupling the connector from
the controller, the method proceeds to electrically isolating both
the first and second electrodes (block 708), activating a third
electrode of the electrosurgical wand as an as an active electrode
with the third electrode different than the first and second
electrodes (block 712), and activating a fourth electrode of the
electrosurgical wand as a return electrode with the fourth
electrode different than the first and second electrodes (block
716). Thereafter, the method comprises treating a second portion of
the target tissue with the electrosurgical wand (block 720), and
the method ends (block 724). Treating the second portion of the
target tissue may comprise, for example, generating a current path
between the third and fourth electrodes during a molecular
disassociation
[0059] The above discussion is meant to be illustrative of the
principles and various embodiments of the present invention.
Numerous variations and modifications possible. For example, while
three or more electrodes may have the ability to be either active,
return or isolated, other electrodes may be present without
departing from the scope and spirit of the invention. Moreover, two
electrodes may be electrically coupled within the wand 102, such
that the coupled electrodes act as single electrode from the
perspective of the controller, with the ability to be active,
return or isolated. Further still, the system may provide audible
feedback to the user as to the selected electrode configuration
and/or voltage output level. For example, in FIG. 6 the audible
feedback may be provided by way of speaker 670 coupled to the
digital-to-analog converter 606. It is intended that the following
claims be interpreted to embrace all such variations and
modifications.
[0060] While preferred embodiments of this disclosure have been
shown and described, modifications thereof can be made by one
skilled in the art without departing from the scope or teaching
herein. The embodiments described herein are exemplary only and are
not limiting. Because many varying and different embodiments may be
made within the scope of the present inventive concept, including
equivalent structures, materials, or methods hereafter though of,
and because many modifications may be made in the embodiments
herein detailed in accordance with the descriptive requirements of
the law, it is to be understood that the details herein are to be
interpreted as illustrative and not in a limiting sense.
* * * * *