Electrosurgical hemostatic device with adaptive electrodes

An electrosurgical instrument is provided for cauterization and/or welding of tissue of varying impedance, thickness, compressibility, density, vascularity, etc., especially in the performance of endoscopic procedures. The instrument provides two electrodes of different electrical potentials. One electrode is moveable with respect to the other electrode to vary the distances between the electrodes and thus the impedance of the tissue as presented to the generator. The electrode distances may be varied by an automated or user controlled device.

FIELD OF THE INVENTION 
This invention relates to an electrosurgical instrument for cauterization, 
coagulation and/or tissue welding in the performance of surgical 
procedures, especially endoscopic procedures. 
BACKGROUND OF THE INVENTION 
Surgical procedures requiring cutting of tissue can cause bleeding at the 
site of the cutting. Various techniques have been adapted to control 
bleeding with varying degrees of success such as, for example, suturing, 
applying clips to blood vessels, and stapling, as well as electrocautery 
and other tissue heating techniques. Advances in tissue joining or 
welding, tissue repair and wound closure also have permitted surgical 
procedures previously not possible or too risky. 
Surgical staplers have been used for tissue security, joining and 
approximation, and to provide hemostasis in conjunction with tissue 
cutting. Such devices include, for example, linear and circular cutting 
and stapling instruments. Typically, a linear cutter has parallel rows of 
staples with a slot for a cutting means to travel between the rows of 
staples. This type of surgical stapler secures tissue for improved 
cutting, joins layers of tissue, and provides hemostasis by applying 
parallel rows of staples to layers of surrounding tissue as the cutting 
means cuts between the parallel rows. 
Electrocautery devices have been used for effecting improved hemostasis by 
heating tissue and blood vessels to cause coagulation or cauterization. 
Monopolar devices utilize one electrode associated with a cutting or 
cauterizing instrument and a remote return electrode, usually adhered 
externally to the patient. More recently, bipolar instruments have been 
used because the cauterizing current is generally limited to tissue 
between two electrodes of a tissue treating portion of an instrument. 
Bipolar forceps have been used for cutting and/or coagulation in various 
procedures. Generally, bipolar forceps grasp tissue between two poles and 
apply electrical current through the grasped tissue. Bipolar forceps, 
however, have certain drawbacks, some of which include the tendency of the 
current to arc between poles when tissue is thin or the forceps to short 
when the poles of the forceps touch. The use of forceps for coagulation is 
also very technique dependent and the forceps are not adapted to 
simultaneously cauterize a larger area of tissue. Furthermore, forceps 
tend to cause areas of thermal spread, i.e., dissipation of heat outside 
of area defined by grasping or engaging surfaces of the forceps. 
When using RF energy in electrosurgical devices, there may be an optimal 
range of tissue impedances that results in the best or optimal energy 
delivery for the output characteristics of the particular generator to 
which the impedance load is presented. 
Generally, the optimal range is related to the principal that where the 
source and load impedances are matched, the transfer of power from the 
source to the load is maximized. Further, the power output for a given 
generator decreases at a predictable rate as impedance of the load, i.e., 
tissue, falls off of the source impedance. 
The optimal range is defined herein as the range of load impedances at 
which the power transfer from the generator is sufficient to achieve the 
intended result, i.e., controlled coagulation, cauterization, or tissue 
welding. The optimal range may vary from application to application or 
from generator to generator. 
It is believed that tissue impedance varies depending on a number of 
parameters which may include: tissue type, liquid content, tissue 
condition (i.e., coagulated or uncoagulated), tissue thickness, the amount 
of tissue compression, the size and length of the flow path of electrical 
current through the tissue, and energy frequency applied to tissue. 
Additionally, for a given area or volume of tissue, the impedance model of 
the tissue is dynamic due to the fact that tissue impedance changes as 
tissue is heated and begins to coagulate, thus effecting the current flow 
pattern through the area or volume of tissue as coagulating current is 
delivered to the tissue. It is also believed that the tissue thickness 
typically changes as it is electrosurgically treated, because, for 
example, as water escapes in the form of steam or vapor the volume of the 
material grasped by the instrument is reduced. Depending on the specific 
end effector configuration, this could provide an additional variable in 
the impedance model of the tissue if in the particular end effector tissue 
thickness were to effect the length of the current path and/or the amount 
of compression applied to the tissue. 
Thus, it is desirable to provide an electrosurgical device which can 
efficiently provide hemostasis in multiple tissue types and thicknesses, 
e.g., in fleshy or vascular tissue areas, and high, low or combination 
impedance tissues. Hemostasis is used herein, generally, to mean the 
arresting of bleeding including by coagulation, cauterization and/or 
tissue joining or welding. 
It is further desirable to provide a device which adapts to the changing 
impedance and/or tissue thicknesses as the tissue is being treated, so 
that the impedance presented to the generator is within an optimal range. 
SUMMARY OF THE INVENTION 
It is therefore an object of the invention to provide an electrosurgical 
method and device which optimize the efficiency of a tissue treating 
energy by configuring the electrodes of the end effector to adapt to the 
type, thickness, impedance, or other parameter of tissue to be engaged by 
the end effector. This allows the instrument to bring a range of expected 
tissue impedance levels within an optimal load impedance range for the 
generator, and to obtain a desired result, e.g. controlled coagulation, 
cauterization, or tissue welding. 
Accordingly, one embodiment of the present invention provides an adjustable 
device in which the distance between the opposite poles or electrodes of a 
tissue grasping or clamping device may be adjusted. The device may be 
adapted to compensate for tissue thickness, various tissue types or 
applications of the device. 
Also, an embodiment of the present invention provides a device which 
dynamically or continuously adapts to the changing impedance and thickness 
of tissue as the tissue is being coagulated so that energy is efficiently 
delivered to the tissue. The device may be adjusted continuously or at 
intervals during a period of treatment. 
In a preferred embodiment the adjustment means may be an automated or user 
actuated mechanical device. 
The device may be used in various instruments using therapeutic 
electrosurgical energy such as, for example, tissue fastening devices, 
e.g. staplers, clip appliers, suturing devices, etc. Other end effector 
configurations may be used such as, for example, cutting devices, linear 
or circular cutting and stapling devices, etc. 
These and other objects of the invention will be better understood from the 
following attached Detailed Description of the Drawings, when taken in 
conjunction with the Detailed Description of the invention. 
DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1. is a perspective view of an endoscopic electrosurgical clamping and 
coagulating device of one embodiment of the present invention; 
FIG. 2 is a bottom isolated view of the lower jaw of the clamping 
instrument of FIG. 1; 
FIG. 3 is a front cross sectional view of the distal end of the instrument 
of FIG. 1 engaging relatively thin tissue; 
FIG. 4 is a front cross sectional view of the distal end of the instrument 
of FIG. 1 engaging relatively thicker tissue than that of FIG. 3; 
FIG. 5 is a perspective partial breakaway, partial exploded view of an 
alternative embodiment of a clamping device of the present invention; 
FIG. 6 is a front cross-sectional view of the device illustrated in FIG. 5 
along the lines 6--6 with a cartridge for relatively thick tissue inserted 
into the end effector; 
FIG. 7 illustrates a front cross-sectional view of the device illustrated 
in FIG. 5 along lines 6--6 with a cartridge for relatively thinner tissue 
than in FIG. 6; and 
FIG. 8 is an exploded perspective view of the proximal handle portion of 
the instrument of FIG. 1; 
FIG. 9 is an exploded perspective view of the intermediate and distal 
portion of the instrument of FIG. 1; 
FIG. 10 is a side elevational view of the proximal handle portion in a 
first, open position of the instrument of FIG. 1, shown with the left side 
handle cover and wireforms removed; 
FIG. 11 is an elevational view of the inside of the left side handle 
portion showing the location of the wireforms and connectors used in the 
present invention; 
FIG. 12 is a longitudinal cross-sectional view of the intermediate portion 
of the instrument; 
FIG. 13 is an elevational view of the proximal end of the intermediate 
portion showing the contact of the wireforms to their respective contact 
positions; 
FIG. 14 is an enlarged cross-sectional view of the proximal end of the 
intermediate portion of the instrument; 
FIG. 15 is a transverse cross sectional view taken along the lines 15--15 
of FIG. 14; 
FIG. 16 is a perspective view showing the wireforms contacting their 
respective contact position; and 
FIG. 17 is an end view of FIG. 16 showing a slight bias in the wireforms 
allowing for pressure of the wireforms onto their respective contact 
position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIGS. 1-4, 8-17 there is illustrated an instrument of the 
present invention. FIGS. 5-7 illustrate an end effector of an alternative 
embodiment which may use similar electrosurgical energy delivery and 
actuation mechanisms. 
An endoscopic clamping and cutting instrument 10 is shown having a housing 
16 coupled to a sheath 30 with a lumen extending therethrough and an end 
effector 15 extending from the distal end of the sheath 30. The end 
effector 15 comprises first and second jaw members 32, 34. Jaw member 32 
is movably secured to jaw member 34. The housing 16 has a clamping trigger 
12 for closing jaw members 32, 34, an RF switch detente arm 58 and 
electrical switch contacts 67a, 67b, coupled to an electrical switch 59 
for turning on RF energy, and a firing trigger 14 for advancing the 
cutting element 11 through tissue. 
Jaw member 32 comprises a U-shaped electrode 51 forming a knife channel 29 
extending longitudinally through jaw member 32. An insulator 31 preferably 
formed of a polymer such as polyphenyleneoxide surrounds the electrode 51. 
Jaw member 32 has an inner surface 33 comprised of the electrode 51 and 
insulator 31. Inner surface 33 substantially faces an inner surface 35 of 
jaw member 34. 
Jaw member 34 comprises an insulator 36 forming a portion of surface 35 and 
forming an indentation 39 on surface 35, and a spring electrode 52 
inserted into the indentation 39. The electrodes 51, 52 are comprised of a 
conductor, such as, surgical grade stainless steel. Spring electrode 52 
further comprises a layer of insulation 52a formed on its inner surface. 
The electrode 51 acts as a first pole of a bipolar tissue treatment or 
therapeutic system. When the jaws 32, 34 are closed together the electrode 
51 is electrically isolated from spring electrode 52 by the insulator 52a 
to prevent shorting by inadvertent contact of electrode 51 with spring 
electrode 52. The spring electrode 52 acts as a second therapeutic 
electrode of the bipolar treatment or therapeutic system, the electrode 52 
being electrically opposite of the electrode 51. 
The spring electrode 52 extends longitudinally, proximal to distal, within 
indentation 39 of jaw member 34 and comprises a V-shaped body 22 having 
flaps 23, 24 extending longitudinally through indentation and forming 
electrode bars 27, 28. The inner surface 22a of the body 22 is insulated 
by insulator 52a whereas the bars 27, 28 are exposed. The insulation may 
be made of an insulating polymer such as, for example, polypheyleneoxide. 
The spring electrode 52 is biased in a closed v-direction. 
When thin tissue is engaged by the jaw members 32, 34 (FIG. 3), the flaps 
23, 24 tend to be closer together because the compressive force is not as 
great as when thicker tissue (FIG. 4) is engaged. When thicker tissue is 
engaged, the compressive force between surfaces 33, 35 is greater, causing 
the flaps 23, 24 to spread away from each other. Thus, when thinner tissue 
is engaged, the distance between electrode bars 27, 28 and electrode 51 is 
less than when thicker tissue is engaged. 
In a preferred embodiment the device is used for a relatively thin more 
compressible, or fatty tissue such as mesentery tissue, or a relatively 
thick or more dense tissue such as muscular tissue or adnexa. 
Compressibility as used herein means the ability of tissue to compress in 
size upon application of a given force. Generally, fatty tissue tends to 
have a higher impedance, lower density and higher compressibility than 
muscular or adnexa tissue. The electrodes are arranged on interfacing 
surfaces to adapt to the expected tissue type. When thinner mesentery 
tissue is engaged, the current path or distance between the electrodes is 
shortened to decrease the relative impedance on the electrodes, whereas 
with thicker muscular or adnexa tissue, the distance is increased to 
increase the relative impedance as presented to the electrodes and thus 
the generator. Thus, in this embodiment, the adaptive electrodes decrease 
the differences in load impedance between two different tissue types. 
The spring electrode 52 is arranged to continuously adapt to the change in 
tissue thickness and compression as the tissue is treated with 
electrosurgical energy. Typically, the tissue will become thinner as it is 
treated. The tissue also tends to increase in impedance as it coagulates. 
The spring electrode will move towards a closed-V position as the tissue 
becomes thinner or more compressed, thereby shortening the current pathway 
and thus lowering the impedance of the tissue and/or continuing to ensure 
electrical contact of tissue with the electrodes 51, 52. 
An alternative embodiment of the end effector is illustrated in FIGS. 5-7. 
Jaw member 132 comprises an insulator 131 preferably formed of a polymer 
such as polyphenyleneoxide. Jaw member 132 includes a knife channel 129 
extending longitudinally through it. Jaw member 132 has an inner surface 
133 which substantially faces an inner surface 135 of jaw member 134. 
Jaw member 134 comprises a channel 122 which is adapted to receive 
cartridge 123. The channel 122 comprises a U-shaped electrode 151 forming 
the outer circumference of the jaw member 134. A changeable cartridge 123 
is inserted into the channel 122. The cartridge 123 comprises an insulator 
139 and a U-shaped electrode 152 forming substantially parallel bar 
electrodes 127, 128 which comprise a portion of surface 135 and form 
compression ridges 156. The U-shaped electrode 152 is surrounded by the 
insulator 139. 
The cartridge 123 may be interchangeable with cartridges having different 
electrode configurations adapted for particular tissue types, thicknesses 
and/or different applications. FIG. 6 illustrates the end effector of FIG. 
5 engaging relatively thick adnexa tissue. The cartridge 123 has a narrow 
U-shaped electrode 152. Bars 127 and 128 are a distance D.sub.1 from 
ridges 156 of electrode 152. FIG. 7 illustrates an end effector engaging 
relatively thin mesentery tissue. The end effector includes an alternative 
cartridge 123a having a wide U-shaped electrode 152a forming ridges 156a. 
Bars 127a and 128a are a distance D.sub.2 from electrode 151 of electrode 
152a where D.sub.1 &gt;D.sub.2. Cartridges 123 and 123a may be selected 
depending on the expected tissue thickness, compressibility, density, 
composition, or particular application of the device. The electrodes 151 
and 152 or 152a may be connected to an energy source in a similar manner 
as the electrodes 51 and 52. 
Referring again to FIGS. 1-4 and 8-17, the sheath 30 is formed of an 
insulative material and has a closure tube 38 extending through its lumen. 
A channel retainer 37a extends from the proximal end of the closure tube 
38 and is secured to channel 37 which there extends distally through the 
remainder of the closure tube 38 to form jaw member 34. The channel 37 
includes jaw member 34 extending distally from the closure tube 38. 
The body 16 has a clamping trigger 12 for advancing the closure tube 38 to 
close the jaws 32, 34 towards each other engaging tissue therebetween. 
Rotation of the clamping trigger 12 causes the closure tube 38 to advance 
co-axially through the sheath 30 over a camming surface 32a of jaw 32 to 
close the jaws 32, 34 onto tissue situated between the jaws 32, 34. 
The channel retainer 37a guides co-axial movement of a drive rod 41 within 
the channel 37. The drive rod 41 is advanced by the rotation of the firing 
trigger 14 as described in more detail below. The driving rod 41 is 
coupled on its distal end to a block 43. The block 43 is coupled to a 
cutting means 11 which the drive rod 41 advances by way of the block 43 
into the end effector 15. Jaw member 32 is secured by way of the channel 
37 to the jaw member 34. 
When the drive rod 41 advances the cutting element 11, the cutting element 
11 advances through the knife channel 29 in between the bars 27, 28 to cut 
tissue engaged by jaws 32, 34. This preferably occurs when the tissue has 
been electrosurgically treated. Thus, the cut line is medial to the 
coagulation lines formed by the bar electrodes 27, 28. 
A knob 44 located on the distal end of the body 16 rotates the closure tube 
38, channel retainer 37a, channel 37 and end effector 15 which are 
directly or indirectly coupled to the knob 44 so that the knob 44 may be 
used for rotational placement of the end effector jaws 32, 34. The knob 44 
includes a peg (not shown) which fits into and engages indentation 38a 
closure tube 38. Closure tube 38 is fitted at its proximal end, into the 
housing 16. 
Electrical energy is supplied to the electrode 51 and 52, by generator 70 
through connections such as those described below, or other connections 
means, such as, for example, like those described in parent application 
Ser. No. 08/095,797, (U.S. Pat. No. 5,403,312) incorporated herein by 
reference. The generator 70 is user controlled by way of RF switch 59 
located in the housing 16. Alternatively, a user controlled foot pedal may 
be used. 
Wires 19a and 19b extend into the body 16 of the instrument and deliver 
energy to electrodes 51, 52 respectively. Wires 19a, 19b are coupled to 
low impedance contact elements 20a, 20b respectively and contact elements 
20a, 20b are coupled to wireforms 47a, 47b respectively. Wireforms 47a, 
47b are exposed at their distal ends 48a, 48b. Wireforms 47a and 47b are 
biased respectively towards contact ring 49a and contact ring 49b located 
on the proximal end of channel retainer 37a, so as to make electrical 
contact with the contact ring 49a and ring 49b respectively. 
Wire 19a delivers electrical current to the electrode 51 by way of first 
wire form 47a which contacts contact ring 49a coupled to wire 40a 
extending through closure tube to electrode 51. 
Wire 19b delivers electrical current to the electrode 52 through second 
wire form 47b which contacts contact ring 49b coupled to wire 40b 
extending through the closure tube 38 to the electrode 52. 
The contact rings 49a, 49b permit the knob 44 to rotate while contact is 
maintained between ring 49a, ring 49b, and wireforms 47a, 47b, 
respectively. The ring 49a is electrically insulated from the ring 49b. 
Wires 40a, 40b extend through seal 45 which fits into channel retainer 37a, 
which fits into closure tube 38. 
Clamping trigger 12 includes gear teeth 12a which movably engage with teeth 
66b of yoke 66. Yoke 66 is coupled on its distal end to the closure tube 
38. When clamping trigger 12 is actuated, the gear teeth 12a engage with 
teeth 66b in yoke 66 causing the yoke 66 to advance distally. Closure tube 
38 closes jaws 32, 34 as it advances over camming surface 32a of jaw 32. 
The RF switch 59 is rotated to switch on RF energy to be supplied to the 
therapeutic electrodes 51, 52. When the RF switch 59 is rotated, detente 
protrusion 59a on the switch 59 hooks under detente protrusion 58a on 
detente arm 58, preventing the switch 59 from deactivating RF energy 
unless the RF switch 59 is manually rotated back to its original position. 
The RF energy may also be turned off electrically, e.g., in response to 
tissue impedance feedback. 
Switch 59 has a moveable contact 67a and a stationary contact 67b. The 
moveable contact 67a rotates with switch 59 to contact stationary contact 
67b when switch is on. 
Ledge 60a of release button 60 is engaged with the proximal end of the yoke 
66 adjacent step ledge 66a on proximal end of yoke 66. When the yoke 66 is 
advanced by the clamping trigger 12, the ledge 60a rotates down behind 
proximal end of yoke 66, thereby preventing yoke 66 from retracting until 
release button 60 has been pressed. Thus the jaws 32, 34 will remain in a 
closed position until a user releases the jaws 32, 34 with release button 
60. 
The switch 59 includes fingers 59c which sit just above proximal end of 
yoke 66. The ledge 60a of the release button 60 fits in between fingers 
59c. The RF switch 59 cannot be activated, i.e., rotated forward, until 
the yoke 66 has been advanced distally so that fingers 59c of switch 59 
are free to rotate behind proximal end of yoke 66. 
The switch 59 also includes a lower hook 59b which engages groove 53a of 
firing rack 53. Firing rack 53 includes gear teeth 53b which are engaged 
by gear teeth 14a of firing trigger 15. The firing rack 53 is coupled on 
its distal end to pinion gear 54 which in turn engages the drive rod 41. 
When the firing trigger 14 is pulled, the fire rack 53 is advanced distally 
to rotate pinion 54 which advances the driving rod 41 distally to actuate 
the cutting element 11 to cut tissue engaged by the end effector 15. 
The firing rack 53 cannot advance however until the lower hook 59b of the 
RF switch is disengaged from the groove 53a of the firing rack 53. This 
occurs only when the RF switch 59 has been activated. 
Thus, the presently described device includes a lockout device or devices 
for preventing application of RF energy, or knife actuation until the jaws 
32, 34 have been closed. The lockout device(s) require the proper sequence 
is followed, i.e, jaw closure, followed by application of RF energy, 
followed by cutting element actuation. It also provides a detented RF 
switch so that RF energy is continuously applied until the switch 59 is 
manually released or until the RF energy is switched off, e.g., by an 
electrical feedback control signal to the generator 70. 
The closure trigger 12 and firing trigger 14 are interlocked and a spring 
57 is mechanically coupled to both triggers 12, 14. 
When tissue is engaged between clamped jaw members 32, 34, and RF energy 
has been applied, the firing trigger 14 located on housing 16 may be 
actuated to advance a cutting element 11 through the engaged tissue to cut 
the tissue. 
Several variations of this invention have been described in connection with 
specific embodiments. Naturally, the invention may be used in numerous 
applications where hemostasis or other electrosurgical tissue effects are 
desired. For example, the devices described herein may include a mechanism 
for cutting tissue and/or applying staples or other fasteners. See for 
example U.S. Ser. Nos. 08/095,797 (U.S. Pat. No. 5,403,312) and 08/096,154 
incorporated herein by reference. Accordingly, it will be understood by 
those skilled in the art that various changes and modifications may be 
made in the invention without departing from its scope, which is defined 
by the following claims and their equivalents.