U.S. patent application number 12/784702 was filed with the patent office on 2010-09-09 for method and system for transcervical tubal occlusion.
Invention is credited to J. Brook Burley, Estela H. Hilario, Russel M. Sampson, Eugene V. Skalnyi.
Application Number | 20100228245 12/784702 |
Document ID | / |
Family ID | 35825321 |
Filed Date | 2010-09-09 |
United States Patent
Application |
20100228245 |
Kind Code |
A1 |
Sampson; Russel M. ; et
al. |
September 9, 2010 |
Method and System for Transcervical Tubal Occlusion
Abstract
A medical device and procedure is described for occluding a
fallopian tube. A tubal occlusion device is inserted into a uterine
cavity. The device includes an RF applicator head including an
electrode carrier with one or more bipolar electrodes thereon.
During insertion, the RF applicator head can be in a closed
position. The RF applicator head is positioned at a tubal ostium of
a fallopian tube, such that a distal tip of the RF applicator head
advances into the tubal ostium. The RF applicator head is deployed
into an open position such that the RF applicator head approximates
the shape of the uterine cavity in a region of the tubal ostium.
Current is passed through the one or more bipolar electrodes to the
tubal ostium to destroy tissue to a known depth, which precipitates
a healing response in surrounding tissue that over time scars and
occludes the fallopian tube.
Inventors: |
Sampson; Russel M.; (Palo
Alto, CA) ; Skalnyi; Eugene V.; (Los Altos, CA)
; Hilario; Estela H.; (Los Alto, CA) ; Burley; J.
Brook; (Sunnyvale, CA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
PO BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
35825321 |
Appl. No.: |
12/784702 |
Filed: |
May 21, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11019580 |
Dec 20, 2004 |
7731712 |
|
|
12784702 |
|
|
|
|
Current U.S.
Class: |
606/33 |
Current CPC
Class: |
A61B 18/1492 20130101;
A61B 2218/008 20130101; A61B 2018/00982 20130101; A61B 2018/126
20130101; A61B 2018/00559 20130101; A61B 2018/00898 20130101; A61B
17/42 20130101; A61B 18/1485 20130101; A61F 6/225 20130101; A61B
2018/00214 20130101; A61B 2017/4216 20130101; A61B 2017/4233
20130101; A61B 2017/00022 20130101 |
Class at
Publication: |
606/33 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1. A method for fallopian tubal occlusion, comprising: inserting a
tubal occlusion device including an RF applicator head comprising
an electrode carrier with one or more bipolar electrodes thereon
into a uterine cavity, the RF applicator head being in a closed
position; positioning the RF applicator head at a tubal ostium of a
fallopian tube such that a distal tip of the RF applicator head
advances into the tubal ostium and deploying the RF applicator head
into an open position such that the RF applicator head approximates
the shape of the uterine cavity in a region of the tubal ostium;
and passing current through the one or more bipolar electrodes to
the tubal ostium to destroy tissue to a known depth and to
precipitate a healing response in surrounding tissue that over time
scars and occludes the fallopian tube.
2. The method of claim 1, wherein passing current through the one
or more bipolar electrodes to the tubal ostium to destroy tissue
comprises vaporizing endometrium and destroying superficial
myometrium.
3. The method of claim 1, wherein inserting a tubal occlusion
device into a uterine cavity comprises inserting the tubal
occlusion device with the RF applicator head in a closed position,
the method further comprising: before passing current through the
one or more bipolar electrodes, deploying the RF applicator head
into the open position.
4. The method of claim 1, further comprising: applying suction
through the electrode carrier to draw the surrounding tissue into
contact with the electrodes and to draw moisture generated during
ablation away from the electrodes to substantially prevent the
formation of a low impedance liquid layer at the electrodes.
5. The method of claim 1, wherein passing current through the one
or more bipolar electrodes comprises delivering radio frequency
energy to the one or more bipolar electrodes.
6. The method of claim 1, further comprising: automatically
terminating the flow of current into the tissue once ablation has
approximately reached a predetermined depth of ablation.
7. The method of claim 1, further comprising: before positioning
the RF applicator head at the tubal ostium, insufflating the
uterine cavity; and before passing current through the one or more
bipolar electrodes, ceasing insufflating the uterine cavity and
allowing the uterine cavity to collapse onto the RF applicator
head.
8. The method of claim 1, wherein deploying the RF applicator head
into an open position includes removing a sheath to expose the
electrode carrier.
9. The method of claim 1, wherein the electrode carrier includes a
fabric having conductive metallized regions and one or more
non-conductive regions formed thereon to create the one or more
bipolar electrodes.
10. The method of claim 1, further comprising: advancing an
illuminator and an optical instrument into the uterine cavity; and
wherein positioning the RF applicator head at the tubal ostium of a
fallopian tube includes using the optical instrument to visualize
the tubal ostium.
Description
CLAIM OF PRIORITY
[0001] This application is a divisional of U.S. application Ser.
No. 11/019,580, filed Dec. 20, 2004, now issued as U.S. Pat. No.
7,731,712, which is incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to a medical device and
procedure.
BACKGROUND
[0003] Female sterilization typically involves occluding the
fallopian tubes to prevent sperm access to an egg within a female's
fallopian tube. One conventional female sterilization procedure is
laparoscopic tubal occlusion. In this procedure, an incision is
made in the abdominal wall to provide access to the fallopian
tubes. The tubes are surgically occluded with the aid of a
laparoscope, for example, using bipolar or monopolar coagulation.
Laparoscopic tubal occlusion is invasive and requires multiple
incisions and passing of several instruments and a gaseous
distension medium into the patient's abdomen. Thermal and
mechanical injury to the surrounding tissues and organs has been
reported.
[0004] Minimally invasive transcervical approaches to female
sterilization have been used more recently. One such procedure
involves placing small, flexible devices into the fallopian tubes;
the devices are inserted transcervically into the uterine cavity
providing access to the fallopian tubes. The devices are made from
polyester fibers and metals and once in place, body tissue grows
into the devices and blocks the fallopian tubes. The devices
permanently remain in the patient's body, which has raised concerns
about the long term effects of the implanted devices as well as
restrictions on potential subsequent surgical interventions within
the uterus, given the conductive metallic components in the
devices.
[0005] A monopolar radio frequency technique has been investigated
that included passing a small diameter wire (an active electrode)
transcervically through the uterine cavity and the tubal ostium to
the fallopian tubes. A large, passive electrode is positioned
externally. The current path between the two electrodes is not well
defined and can lead to inadvertent burns. The technique was not
successful and was abandoned. It could manage neither the varying
thicknesses of endometrial tissue at the tubal ostium, nor the
required tight tolerance on the depth of destruction within the
fallopian tubes.
SUMMARY
[0006] This invention relates to a medical device and procedure. In
general, in one aspect, the invention features a method for
fallopian tubal occlusion. A tubal occlusion device is inserted
into a uterine cavity. The device includes an RF applicator head
including an electrode carrier with one or more bipolar electrodes
thereon. During insertion, the RF applicator head is in a closed
position. The RF applicator head is positioned at a tubal ostium of
a fallopian tube such that a distal tip of the RF applicator head
advances into the tubal ostium. The RF applicator head is deployed
into an open position such that the RF applicator head approximates
the shape of the uterine cavity in a region of the tubal ostium.
Current is passed through the one or more bipolar electrodes to the
tubal ostium to destroy tissue to a known depth, which precipitates
a healing response in surrounding tissue that over time scars and
occludes the fallopian tube.
[0007] Implementations of the invention can include one or more of
the following features. Passing current through the one or more
bipolar electrodes to the tubal ostium to destroy tissue can
include vaporizing endometrium and destroying superficial
myometrium. Inserting a tubal occlusion device into a uterine
cavity can include inserting the tubal occlusion device with the RF
applicator head in a closed position, and before passing current
through the one or more bipolar electrodes, deploying the RF
applicator head into the open position. Suction can be applied
through the electrode carrier to draw the surrounding tissue into
contact with the electrodes, and to draw moisture generated during
ablation away from the electrodes to substantially prevent the
formation of a low impedance liquid layer at the electrodes.
Passing current through the one or more bipolar electrodes can
include delivering radio frequency energy to the one or more
bipolar electrodes.
[0008] The method can further include automatically terminating the
flow of current into the tissue once ablation has approximately
reached a predetermined depth of ablation. Before positioning the
RF applicator head at the tubal ostium, the uterine cavity can be
insufflated. Insufflation is ceased before passing current through
the one or more bipolar electrodes, allowing the uterine cavity to
collapse onto the RF applicator head. Deploying the RF applicator
head into an open position can include removing a sheath to expose
the electrode carrier. The electrode carrier can include a fabric
having conductive metallized regions and one or more non-conductive
regions formed thereon to create the one or more bipolar
electrodes. The method can further include advancing an illuminator
and an optical instrument into the uterine cavity. Positioning the
RF applicator head at the tubal ostium of a fallopian tube can
include using the optical instrument to visualize the tubal
ostium.
[0009] In general, in another aspect, the invention features a
system for fallopian tubal occlusion. The system includes a tubal
occlusion device, a source of radio frequency energy, a controller
and a vacuum source. The tubal occlusion device has a distal end
and a proximal end, the distal end including an electrode carrier
with one or more bipolar electrodes thereon. In an open condition
the distal end is shaped to approximate a uterine cavity in a
region of a tubal ostium of a fallopian tube to be occluded. The
source of radio frequency energy is electrically coupled to the one
or more bipolar electrodes. The controller is configured to control
the delivery of radio frequency energy to the one or more bipolar
electrodes such that passing radio frequency energy through the one
or more bipolar electrodes to the tubal ostium can be controlled to
destroy tissue to a known depth, which precipitates a healing
response in surrounding tissue that over time scars and occludes
the fallopian tube. The vacuum source is operable to draw the
tissue into contact with the one or more bipolar electrodes and to
draw moisture generated during delivery of the radio frequency
energy to the bipolar electrodes away from the bipolar electrodes.
This can substantially eliminate liquid surrounding the bipolar
electrodes.
[0010] Implementations of the invention can include one or more of
the following features. Passing radio frequency energy through the
one or more bipolar electrodes to the tubal ostium destroying
tissue can include vaporizing endometrium and destroying
superficial myometrium. The electrode carrier can include a
structural support member within a fabric sheath having conductive
metallized regions and having one or more non-conductive regions
formed thereon to create the one or more bipolar electrodes. The
structural support member can include flexible members movable
between a closed condition and the open condition. The system can
further include an illumination source electrically coupled to the
distal end of the tubal occlusion device to illuminate the uterus,
and an optical instrument electrically coupled to the distal end of
the tubal occlusion device to provide images of the uterus.
[0011] In general, in another aspect, the invention features an
apparatus for occluding a fallopian tube. The apparatus includes an
elongate member, an electrode carrier and a tube. The elongate
member has a distal end, a proximal end and a hollow central
interior. The electrode carrier is attached to the distal end of
the elongate member and has one or more bipolar electrodes formed
thereon. The electrode carrier is operable to couple to a radio
frequency energy generator and is movable between a closed position
in which the electrode carrier is collapsed for insertion into a
uterine cavity, and an open position in which a distal end of the
electrode carrier is shaped to fit within a tubal ostium of a
fallopian tube. The hollow central interior of the elongate member
is operable to couple to a vacuum source and to draw moisture away
from the one or more electrodes.
[0012] Implementations of the invention can include one or more of
the following features. The apparatus can further include an
illuminator attached to the distal end of the elongate member and
operable to couple to an illumination source, and an optical
instrument attached to the distal end of the elongate member and
operable couple to an image display device. The electrode carrier
can include a structural support member within a fabric sheath
having conductive metallized regions and have one or more
non-conductive regions formed thereon to create the one or more
bipolar electrodes The structural support member can include
flexible members movable between a closed condition and the open
condition.
[0013] Implementations of the invention can realize one or more of
the following advantages. The tubal occlusion procedure described
is minimally invasive: the tubal occlusion device can be introduced
into the patient's uterine cavity transcervically and requires no
abdominal incision. The procedure does not leave any foreign
objects in the patient's body, minimizing the risk of infection and
eliminating the need to restrict subsequent surgical intervention
options. The procedure can be performed quickly, the actual
duration of ablation being approximately one minute per fallopian
tube. Because the RF energy is limited to the region of ablation,
there is less risk of damage to other organs during the procedure.
The system and procedure automatically compensate for varying
endometrial thicknesses, facilitating the proper, contoured depth
of tissue destruction in the region of the tubal opening. Further,
unlike the technique described above that implanted permanent
devices in the fallopian tubes, there is no need to navigate a
catheter through the fallopian tubes, which are prone to spasm,
inhibiting the placement of permanent devices, making such a
procedure difficult to achieve.
[0014] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0015] FIG. 1A is a schematic representation of a uterus.
[0016] FIG. 1B is a schematic representation of a RF applicator
head positioned in a tubal ostium.
[0017] FIG. 1C is a schematic representation of a region of ablated
tissue in a uterus and tubal ostium.
[0018] FIG. 2 shows a side view of a tubal occlusion device.
[0019] FIG. 3A shows a top view of the tubal occlusion device of
FIG. 2 with a RF applicator head in a closed position.
[0020] FIG. 3B shows a top view of the tubal occlusion device of
FIG. 2 with the RF applicator head in an open position.
[0021] FIGS. 4A and 4B show one embodiment of a structural body of
a RF applicator head in closed and open positions respectively.
[0022] FIG. 4C is a schematic representation of a RF applicator
head in an open position.
[0023] FIG. 4D is a schematic representation of center lines of
electrodes of the RF applicator head of FIG. 4C.
[0024] FIG. 4E is a cross-sectional view of a main body of the
tubal occlusion device of FIGS. 2 and 3.
[0025] FIGS. 5A-D are schematic representations of cross-sectional
views showing electrodes in contact with tissue for ablation.
[0026] FIG. 6 is a flowchart showing a process for tubal
occlusion.
[0027] FIGS. 7A-D are schematic representations of steps of a
process for tubal occlusion.
[0028] FIG. 8 is a schematic representation of an alternative
embodiment of a structural body of a RF applicator head.
[0029] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0030] A method and system for occlusion of a female's fallopian
tubes is described that provides a minimally invasive alternative
for female sterilization. Referring to FIG. 1A, a schematic
representation of a uterus 3 is shown, including a uterine cavity 5
surrounded by uterine tissue, namely endometrial tissue 7a and
myometrial tissue 7b. The fallopian tubes 11 connect to the uterine
cavity 5 at the tubal ostia 9. Occluding the tubal ostia 9 prevents
sperm from entering the fallopian tubes 11 and fertilizing an egg,
thereby sterilizing the female.
[0031] Referring to FIG. 1B, a RF (radio frequency) applicator head
2 can be introduced transcervically into the uterine cavity and
positioned at a tubal ostium 9. Transmitting RF energy through the
RF applicator head 2 ablates the uterine tissue 7a, 7b and tissue
within the tubal ostium 9, as shown schematically by the region 11
in FIG. 1C. Following the destruction of tissue at the tubal ostium
9, the healing response occludes the tubal ostium 9 and the
adjacent portion of the fallopian tube 11 resulting in
sterilization. Referring again to FIG. 1C, the targeted destruction
from A-A to B is approximately 1.5 to 2.5 millimeters, from A-A to
C is approximately 10 to 20 millimeters, and the depth D-D is
typically approximately 2.0 to 3.5 millimeters.
[0032] Referring to FIGS. 2, 3A and 3B, one embodiment of a tubal
occlusion device 15 is shown. The tubal occlusion device 15
includes generally three major components: the RF applicator head
2, a main body 4, and a handle 6. FIG. 2 shows a side view of the
tubal occlusion device 15 and FIGS. 3A and 3B show top views. FIG.
3A shows the tubal occlusion device 15 with the RF applicator head
2 in a closed position within a sheath 32 and FIG. 3B shows the RF
applicator head 2 in an open position outside of the sheath 32. The
RF applicator head 2 includes an electrode carrier 12 mounted to
the distal end of the shaft 10 and electrodes 14 formed on the
surface of the electrode carrier 12. An RF generator 16 can be
electrically connected to the electrodes 14 to provide mono-polar
or bipolar RF energy to them.
[0033] The main body 4 includes a shaft 10. The shaft 10 is an
elongate member having a hollow interior. In one embodiment, the
shaft 10 is approximately 30 centimeters long and has a
cross-sectional diameter of approximately 4 millimeters. Extending
through the shaft 10 is a suction/insufflation tube 17 having a
plurality of holes 17a formed in its distal end (see FIGS. 4A and
4B).
[0034] Referring particularly to FIG. 3B, electrode leads 18a and
18b extend through the shaft 10 from the distal end 20 to the
proximal end 22 of the shaft 10. At the distal end 20 of the shaft
10, each of the leads 18a, 18b is coupled to a respective one of
the electrodes 14. At the proximal end 22 of the shaft 10, the
leads 18a, 18b are electrically connected to the RF generator 16 by
an electrical connector 21. During use, the leads 18a, 18b carry RF
energy from the RF generator 16 to the electrodes 14. Each of the
leads 18a, 18b is insulated, and the leads 18a and 18b can be
connected to opposite terminals of the RF generator 16. When
opposite polarity is applied to alternating electrodes or groups of
electrodes, an electrode pair (i.e., one positively charged and one
negatively charged electrode or group of electrodes) can be
referred to as a bipolar electrode. Any references herein to a
bipolar electrode refer to such an electrode pair.
[0035] Referring to FIGS. 4A-C, the RF applicator head 2 can be
shaped to approximate the shape of the region to be ablated. The
embodiment of the RF applicator head 2 shown in FIG. 4C has a
V-shape which can fit within a corner of the uterine cavity 5 and
reach into the tubal ostium 9. FIGS. 4A and 4B show the RF
applicator head 2 without the electrode carrier 12, thereby
revealing the structural body 100 of the RF applicator head 2. A
flexible member 19 is attached to the distal end of the shaft 10 of
the main body and to the distal end of the tube 17. A flexure 22 is
attached to the tube 17 and to an inner surface of the flexible
member 19. In the closed position shown in FIG. 4A, the flexure 22
is compressed within the space formed between the inner surface of
the flexible member 19 and the tube 17, and the shape of the
structural body 100 of the RF applicator head 2 is substantially
cylindrical. In one embodiment, the flexure 22 and flexible member
19 are made from stainless steel, are approximately 0.012 inches
thick and are substantially planar.
[0036] The RF applicator head 2 can be deployed into the open
position shown in FIG. 4B by moving the tube 17 relative to the
shaft 10. In one embodiment, the shaft 10 is pulled toward the
proximal end of the shaft, i.e., away from the RF applicator head
2. Movement of the shaft 10, which is connected to the flexible
member 19, causes the flexible member 19 to also move in the same
direction, causing the flexure 22 to move laterally away from the
tube 17. As shown in FIG. 4B, flexible member 19 is deformed
outwardly, away from the tube 17, creating the V-shape at the
distal end of the RF applicator head 2. The shape of the distal end
differs depending on how much the shaft 10 and tube 17 are moved
relative to one another.
[0037] In an alternative embodiment, the tube 17 can be pushed
toward the proximal end of the flexible member 19, i.e., toward the
RF applicator head 2, thereby moving the tube 17 relative to the
shaft 10. The relative movement has the same effect as described
above, that is, the flexible member 19 is deformed outwardly,
creating a V-shape at the distal end.
[0038] FIG. 4C shows the distal end of the RF applicator head 2
with the electrode carrier 12 over the structural body. The
electrode carrier 12 can be formed of a fabric that is stretched
over the structural body; the fabric is metallized in the regions
forming the electrodes 14. The electrodes 14 are conductive and can
alternate between positive and negative polarity (an electrode pair
being a "bipolar electrode" as described above). In the embodiment
depicted, there are four electrodes 14 (or 2 bipolar electrodes),
two on either face of the electrode carrier 12. A non-conductive
insulator 23 divides the electrode carrier 12 into the bipolar
electrodes 14.
[0039] In one embodiment, the fabric is formed from a composite
yarn with a thermoplastic elastomer (TPE) core and multiple
polyfilament nylon bundles wound around the TPE as a cover. The
nylon bundles are plated with thin conductive metal layers.
Preferably, the nylon is metallized, but not the TPE core. This
construction facilitates stretching; the nylon windings open up
their coils as the TPE core is elongated, without cracking the
metallic layer. The TPE core facilitates recovery from the
stretched position, pulling the nylon coils back into their initial
configuration.
[0040] In an alternative embodiment, the electrode carrier 12 can
be a sack formed of a material that is non-conductive, that is
permeable to moisture, and that can be compressed to a smaller
volume and subsequently released to its natural size upon
elimination of compression. Examples of materials for the electrode
carrier 12 include foam, cotton, fabric, or cotton-like material,
or any other material having the desired characteristics. The
electrodes 14 can be attached to the outer surface of the electrode
carrier 12, e.g., by deposition or another attachment mechanism.
The electrodes 14 can be made of lengths of silver, gold, platinum,
or any other conductive material. The electrodes 14 can be formed
on the electrode carrier 12 by electron beam deposition, or they
can be formed into coiled wires and bonded to the electrode carrier
12 using a flexible adhesive. Other means of attaching the
electrodes, such as sewing them onto the surface of the electrode
carrier 12, may alternatively be used.
[0041] Depth of destruction of the target tissue can be contoured
to achieve repeatable, predetermined depths. Variables such as the
electrode construction, power applied to the electrodes (power
density or power per unit surface area of the electrode), and the
tissue impedance at which power is terminated can be used to affect
the depth of tissue destruction, as discussed further below.
[0042] The spacing between the electrodes (i.e., the distance
between the centers of adjacent electrodes) and the widths of the
electrodes are selected so that ablation will reach predetermined
depths within the tissue, particularly when maximum power is
delivered through the electrodes. Maximum power is the level at
which low impedance, low voltage ablation can be achieved. For
example, referring to FIG. 4D, lines 19a and 19b represent center
lines of the electrodes 14 of the RF applicator head 2 of FIG. 4C,
i.e., the spacing. The center lines diverge and are closest at the
distal end I and further apart at the proximal end H. The closer
the center lines the shallower the depth of destruction. That is,
the depth of destruction at the distal end, which during operation
is positioned within or closest to the tubal ostium 9, is
least.
[0043] Referring to FIG. 5A, preferably each electrode is energized
at a polarity opposite from that of its neighboring electrodes. By
doing so, energy field patterns, designated 52, 53 and 54 in FIG.
5A, are generated between the electrode sites and thus help to
direct the flow of current through the tissue T to form a region of
ablation A. As can be seen in FIG. 5A, if electrode spacing is
increased by energizing, for example, every third or fifth
electrode rather than all electrodes, the energy patterns will
extend more deeply into the tissue. See, for example, pattern 53
which results from energization of electrodes having a
non-energized electrode between them, or pattern 54 which results
from energization of electrodes having two non-energized electrodes
between them.
[0044] The depth of ablation is also effected by the electrode
density (i.e., the percentage of the target tissue area which is in
contact with active electrode surfaces) and may be regulated by
pre-selecting the amount of this active electrode coverage. For
example, the depth of ablation is much greater when the active
electrode surface covers more than 10% of the target tissue than it
is when the active electrode surfaces covers only 1% of the target
tissue.
[0045] By way of illustration, by using 3-6 mm spacing and an
electrode width of approximately 0.5-2.5 mm, delivery of
approximately 20-40 watts over a 9-16 cm.sup.2 target tissue area
will cause ablation to a depth of approximately 5-7 millimeters
when the active electrode surface covers more than 10% of the
target tissue area. After reaching this ablation depth, the
impedance of the tissue will become so great that ablation will
self-terminate. By contrast, using the same power, spacing,
electrode width, and RF frequency will produce an ablation depth of
only 2-3 mm when the active electrode surfaces covers less than 1%
of the target tissue area. This can be better understood with
reference to FIG. 5B, in which high surface density electrodes are
designated 51a and low surface density electrodes are designated
51b. For purposes of this comparison between low and high surface
density electrodes, each bracketed group of low density electrodes
is considered to be a single electrode. Thus, the electrode widths
W and spacings S extend as shown in FIG. 5B.
[0046] As is apparent from FIG. 5B, the electrodes 51a, which have
more active area in contact with the underlying tissue T, produce a
region of ablation A1 that extends more deeply into the tissue T
than the ablation region A2 produced by the low density electrodes
51b, even though the electrode spacings and widths are the same for
the high and low density electrodes. Some examples of electrode
widths, having spacings with more than 10% active electrode surface
coverage, and their resultant ablation depth, based on an ablation
area of 6 cm.sup.2 and a power of 20-40 watts, are given on the
following table:
TABLE-US-00001 ELECTRODE WIDTH SPACING APPROX. DEPTH .sup. 1 mm 1-2
mm 1-3 mm 1-2.5 mm 3-6 mm 5-7 mm 1-4.5 mm 8-10 mm 8-10 mm
[0047] Examples of electrode widths, having spacings with less than
1% active electrode surface coverage, and their resultant ablation
depth, based on an ablation area of 6 cm.sup.2 and a power of 20-40
watts, are given on the following table:
TABLE-US-00002 ELECTRODE WIDTH SPACING APPROX. DEPTH .sup. 1 mm 1-2
mm 0.5-1 mm 1-2.5 mm 3-6 mm 2-3 mm 1-4.5 mm 8-10 mm 2-3 mm
[0048] Thus it can be seen that the depth of ablation is
significantly less when the active electrode surface coverage is
decreased.
[0049] Referring to FIG. 5C, if multiple, closely spaced,
electrodes 51 are provided on the electrode carrying member, a user
may set the RF generator 16 to energize electrodes which will
produce a desired electrode spacing and active electrode area. For
example, alternate electrodes may be energized as shown in FIG. 5C,
with the first three energized electrodes having positive polarity,
the second three having negative polarity, etc. All six electrodes
together can be referred to as one bipolar electrode. As another
example, shown in FIG. 5D, if greater ablation depth is desired the
first five electrodes may be positively energized, and the seventh
through eleventh electrodes negatively energized, with the sixth
electrode remaining inactivated to provide adequate electrode
spacing. Therefore, in one implementation, a user can control which
electrodes are energized to produce a desired depth of
destruction.
[0050] Referring again to FIGS. 3A and 3B, in one implementation,
to achieve the desired depth of ablation, a controller included in
the RF generator 16 can monitor the impedance of the tissue at the
distal end of the RF applicator head 2 and include an automatic
shut-off once a threshold impedance is detected. As the tissue is
desiccated by the RF energy, fluid is lost and withdrawn from the
region by a vacuum through the tube 17, which can be connected to
suction/insufflation unit 40 via suction/insufflation port 38
(FIGS. 3A, 3B). The suction draws moisture released by tissue
undergoing ablation away from the electrode carrier 12 and prevents
formation of a low-impedance liquid layer around the electrodes 14
during ablation. As more tissue is desiccated, the higher the
impedance experienced at the electrodes 14. By calibrating the RF
generator 16, taking into account system impedance (e.g.,
inductance in cabling etc.), a threshold impedance level can be set
that corresponds to a desired depth of ablation.
[0051] Once the threshold impedance is detected, the controller
shuts off the RF energy, preventing excess destruction of tissue.
For example, when transmitting RF energy of 5.5 watts per square
centimeter of tissue, an impedance of the tissue of 50 ohms can
indicate a depth of destruction of approximately 3 to 4 millimeters
at the proximal end H and approximately 2.5 millimeters at the
distal end I. In an alternative embodiment, the RF generator 16 can
be configured such that above the threshold impedance level the RF
generator's ability to deliver RF power is greatly reduced, which
in effect automatically terminates energy delivery.
[0052] Referring again to FIGS. 3A and 3B, an introducer sheath 32
facilitates insertion of the tubal occlusion device 15 into, and
removal of the device from, the uterine cavity 5. The sheath 32 is
a tubular member that is slidable over the shaft 10. The sheath 32
is slidable between a distal condition, shown in FIG. 3A, in which
the RF applicator head 2 is compressed inside the sheath, and a
proximal condition in which the sheath 32 is moved proximally to
release the RF applicator head 2 from inside the sheath 32 (FIG.
3). By compressing the electrode carrier 12 to a small volume, the
RF applicator head 2 can be easily inserted transcervically into
the uterine cavity 5.
[0053] During use, the sheath 32 is retracted from the electrode
carrier 12, for example, by moving the distal handle member 34
towards the proximal handle member 37 to slide the sheath 32 in the
distal direction. Moving the distal handle member 34 toward the
proximal handle member 27 can also advance the shaft 10 in the
proximal direction. The movement of the shaft 10 relative to the
suction/insufflation tube 17 causes the shaft 10 to pull proximally
on the flexible member 19. Proximal movement of the flexible member
19 in turn pulls the flexure 22, causing it to move to the opened
condition shown in FIG. 3B (see also FIG. 4B). In one embodiment, a
locking mechanism (not shown) is required to hold the shaft in the
fully withdrawn condition to prevent inadvertent closure of the RF
applicator head 2 during the ablation procedure.
[0054] The amount by which the flexible member 19 is deformed
outwardly from the tube 17 can be controlled by manipulating the
handle 6 to slide the shaft 10, proximally or distally. The amount
by which the shaft 10 is slid relative to the tube 17 controls the
shape of the flexible member 19.
[0055] As mentioned above, in an alternative embodiment, the handle
6 can be configured so that the tube 17 can be moved distally
relative to the shaft 10. Distal movement of the tube 17 in turn
deforms the flexible member 19 outwardly. The amount by which the
flexible member 19 is deformed outwardly from the tube 17 can be
controlled by manipulating the handle 6 to slide the tube 17
proximally or distally, and the amount by which the tube 17 moves
relative to the shaft 10 controls the shape of the flexible member
19.
[0056] As shown in FIG. 3A, a flow pathway 36 is formed from the RF
applicator head 2 to the suction/insufflation port 38. The proximal
end of the suction/insufflation tube 17 is fluidly coupled to the
flow pathway so that gas fluid may be introduced into, or withdrawn
from the suction/insufflation tube 17 via the suction/insufflation
port 38. For example, suction may be applied to the fluid port 38
using a suction/insufflation unit 40. This causes water vapor
within the uterine cavity 5 to pass through the permeable electrode
carrier 12, into the suction/insufflation tube 17 via holes 17a,
through the tube 17, and through the suction/insufflation unit 40
via the port 38. If insufflation of the uterine cavity 5 is
desired, insufflation gas, such as carbon dioxide, may be
introduced into the suction/insufflation tube 17 via the port 38.
The insufflation gas travels through the tube 17, through the holes
17a, and into the uterine cavity 5 through the permeable electrode
carrying member 12.
[0057] One or more additional components can be provided for
endoscopic visualization purposes. For example, lumen 42, 44, and
46 may be formed in the walls of the introducer sheath 32 as shown
in FIG. 4E. An optical instrument can be used to provide images
from within the uterine cavity. For example, referring to FIGS. 3B
and 4E, an imaging conduit, such as a fiberoptic bundle, extends
through lumen 42 and is coupled via a camera cable 43 to a camera
45. Images taken from the camera may be displayed on a monitor 47.
An illumination fiber 50 can extend through lumen 44 and couple to
an illumination source 49. The optional third lumen 46 can be an
instrument channel through which surgical instruments may be
introduced into the uterine cavity 5, if necessary. In an
alternative embodiment, one or more of the lumen 42, 44, 46 can be
formed in the walls of the shaft 10.
[0058] Because during use it is most desirable for the electrodes
14 on the surface of the electrode carrier 12 to be held in contact
with the interior surface of the uterine cavity 5 and tubal ostia
9, the electrode carrier 12 may have additional components inside
it that add structural integrity to the electrode carrying means
when it is deployed within the body.
[0059] Referring to FIGS. 1A-C, 5 and 6A-D, a process 58 for using
the tubal occlusion device 15 to sterilize a female shall be
described. The tubal occlusion device 15 is inserted through the
vagina and cervix to the internal as 13 at the base of the uterus 3
(step 59). A gas, e.g., carbon dioxide, is delivered into the
uterine cavity 5 via the suction/insufflation tube 17 from the
suction/insufflation unit 40 to distend the uterine cavity 5 (step
60). The tubal occlusion device 15 is then advanced into the
uterine cavity 5 (step 61).
[0060] The user visualizes the target tubal ostium 9 on the monitor
47 using images provided by the camera 45 (step 62). FIG. 7A is a
schematic representation of what the user may see upon the tubal
occlusion device 15 entering the uterine cavity 5; the tubal ostium
9 is a relatively small spot in the distance. As the tubal
occlusion device 15 advances toward the tubal ostium 9, the tubal
ostium 9 is easier to visualize, as shown in FIG. 7B. The distal
end of the RF applicator head 2, which is still within the sheath
32, is positioned at the tubal ostium 9, as depicted in FIG. 7C
(step 63). The sheath 32 is withdrawn to expose the electrodes 14
(step 64) and the RF applicator head 2 is deployed into the open
position (step 65), as depicted in FIG. 7D.
[0061] Insufflation is ceased and the uterine cavity 5 is allowed
to collapse onto the RF applicator head 2 (step 66). Vacuum can be
applied to the RF applicator head 2 via the suction/insufflation
tube 17 to draw the surrounding tissue into contact with the
electrodes 14 (step 67). The RF generator 16 is turned on to
provide RF energy to the electrodes 14 (step 68). The RF energy is
ceased once the desired amount of tissue has been ablated (step
69). In one implementation, 5.5 watts of RF power is supplied for
per square centimeter of electrode surface area until the
predetermined impedance threshold is reached, at which point power
is terminated.
[0062] The uterine cavity 5 can be insufflated a second time, the
RF applicator head 2 collapsed into a closed position and the tubal
occlusion device 15 rotated approximately 180.degree.. The RF
applicator head 2 can then be positioned at the other tubal ostium
9 and the above procedure repeated to ablate tissue at the other
tubal ostium 9. The tubal occlusion device 15 is then closed and
withdrawn from the patient's body. After ablation, healing and
scarring responses of the tissue at the tubal ostia 9 permanently
occlude the fallopian tubes 11, without requiring any foreign
objects to remain in the female's body and without any incisions
into the female's abdomen. The procedure is fast, minimally
invasive, and is highly effective at tubal occlusion.
[0063] Referring to FIG. 8, an alternative embodiment of a
structural body 70 of the RF applicator head 2 is shown. The
structural body 70 includes an external hypotube 72 and an internal
hypotube 74. If implementing the structural body 70 in the
embodiment of the tubal occlusion device 15 described above, the
external hypotube 72 can be the shaft 10 and the internal hypotube
74 can be the suction/insufflation tube 17. A cage 78 is formed
over the internal hypotube 74 configured in a V-shape at the distal
end 79 that can reach into a tubal ostium 9. The cage 78 can be a
braided or woven structure made from a memory material, e.g.,
nitinol.
[0064] The cage 78 can be collapsed into a narrow cylindrical
configuration by moving the internal hypotube 74 relative to the
external hypotube 72, e.g., by pushing the internal hypotube 74
distally away from the external hypotube 72. In a collapsed state
the cage 78 can fit, for example, within the sheath 32 described
above, when the RF applicator head 2 is placed in a closed
position. Once the sheath 32 is removed and the internal hypotube
74 is moved back into the open position relative to the external
hypotube 72, the nature of the material from which the cage 78 is
made expands the cage 78 into the desired shape that is depicted.
An electrode carrier, such as the electrode carrier 12 made from a
metallized fabric described above, can be fitted over the
structural body 70, completing the RF applicator head.
[0065] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the following claims.
* * * * *