U.S. patent application number 11/452637 was filed with the patent office on 2007-01-18 for microwave tissue resection tool.
Invention is credited to Fred T. JR. Lee, Daniel Warren van der Weide.
Application Number | 20070016181 11/452637 |
Document ID | / |
Family ID | 37571106 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070016181 |
Kind Code |
A1 |
van der Weide; Daniel Warren ;
et al. |
January 18, 2007 |
Microwave tissue resection tool
Abstract
A medical instrument or device is used for resonant delivery of
microwave power to tissue for the purpose of resection and
coagulation of vessels during surgery and/or other medical
procedures. The device enables delivery of large amounts of power
to tissue without the need for ground pads by accomplishing an
impedance match between tissue and the characteristic impedance of
the waveguide that feeds power to it. The device includes a
semi-rigid coaxial cable having a center conductor which protrudes
from an outer conductor by a length set to be a .lamda./4
(quarter-wavelength) at the frequency of excitation in the
dielectric environment of the tissue of interest. The coaxial cable
is shrouded by a dielectric sleeve that provides both thermal and
electrical insulation. Fitted against this sleeve is a conductive
sleeve whose length is set to be a .lamda./4 (quarter-wavelength)
at the frequency of excitation in the dielectric environment of the
dielectric sleeve and the shroud. The device is connected to a feed
cable at its proximal end, and can be connected to a source of
microwave power. A directional coupler or other wave-sampling
mechanism in combination with a power sensor and feedback circuit
can be used to monitor reflected power from the device during the
procedure, and to control the amount of power supplied to the
device.
Inventors: |
van der Weide; Daniel Warren;
(Madison, WI) ; Lee; Fred T. JR.; (Madison,
WI) |
Correspondence
Address: |
Patula & Associates, P.C.
14th Floor
116 S. Michigan Ave.
Chicago
IL
60603
US
|
Family ID: |
37571106 |
Appl. No.: |
11/452637 |
Filed: |
June 14, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10834802 |
Apr 29, 2004 |
7101369 |
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11452637 |
Jun 14, 2006 |
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11237136 |
Sep 28, 2005 |
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11452637 |
Jun 14, 2006 |
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11237430 |
Sep 28, 2005 |
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11452637 |
Jun 14, 2006 |
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11236985 |
Sep 28, 2005 |
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11452637 |
Jun 14, 2006 |
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11440331 |
May 24, 2006 |
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11452637 |
Jun 14, 2006 |
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Current U.S.
Class: |
606/33 |
Current CPC
Class: |
A61B 18/18 20130101;
A61B 2018/00023 20130101; A61B 18/1815 20130101 |
Class at
Publication: |
606/033 |
International
Class: |
A61B 18/18 20070101
A61B018/18 |
Claims
1. A device for delivery of microwave power to tissue, comprising:
a coaxial cable; a resonant sleeve for impedance matching; a
resonant tip; and a polymer coating for said tip.
2. The device of claim 1, further comprising a means for
controlling the power delivered to the tissue based on monitoring
reflected power from the device.
3. The device of claim 1, wherein the device delivers greater than
100 Watts of power to tissue without the need for ground pads.
4. A medical device comprising: a coaxial cable having a center
conductor and an outer conductor; a dielectric sleeve shrouding the
coaxial cable; and a conductive sleeve fitted against the
dielectric sleeve and contacting the outer conductor; wherein the
center conductor protrudes from the outer conductor by a length,
and wherein the device accomplishes an impedance match between
tissue of interest and a characteristic impedance of the waveguide
that feeds power to the device.
5. The device of claim 4, wherein the conductive sleeve is
positionable to adjust the impedance matching effect.
6. The device of claim 4, wherein the length that the center
conductor protrudes from the outer conductor is set to be a
quarter-wavelength at the frequency of excitation in the dielectric
environment of the tissue.
7. The device of claim 4, wherein the conductive sleeve has a
length set to be a quarter-wavelength at the frequency of
excitation in the dielectric environment of the dielectric sleeve
and a shroud which houses the device.
8. The device of claim 7, wherein the shroud includes cooling
fluid.
9. The device of claim 7, wherein the shroud includes microwave
absorbing material.
10. A method of delivering microwave power to tissue, comprising
the steps of: feeding power to a microwave delivery device;
accomplishing an impedance match between the tissue and a
characteristic impedance of the waveguide that feeds power to the
device; and delivering microwave power to tissue.
Description
CLAIM OF PRIORITY
[0001] This application is a Continuation-In-Part of co-pending
U.S. Non-Provisional Patent Applications entitled "Triaxial Antenna
for Microwave Tissue Ablation" filed Apr. 29, 2004 and assigned
U.S. application Ser. No. 10/834,802; "Segmented Catheter for
Tissue Ablation" filed Sep. 28, 2005 and assigned U.S. application
Ser. No. 11/237,136; "Cannula Cooling and Positioning Device" filed
Sep. 28, 2005 and assigned U.S. application Ser. No. 11/237,430;
"Air-Core Microwave Ablation Antennas" filed Sep. 28, 2005 and
assigned U.S. application Ser. No. 11/236,985; and "Microwave
Surgical Device" filed May 24, 2006 and assigned U.S. application
Ser. No. 11/440,331; the entire disclosures of each and all of
these applications are hereby herein incorporated by reference.
[0002] This application further claims priority to U.S. Provisional
Patent Applications entitled "Segmented Catheter for Tissue
Ablation" filed May 10, 2005 and assigned U.S. application Ser. No.
60/679,722; "Microwave Surgical Device" filed May 24, 2005 and
assigned U.S. application Ser. No. 60/684,065; "Microwave Tissue
Resection Tool" filed Jun. 14, 2005 and assigned U.S. application
Ser. No. 60/690,370; "Cannula Cooling and Positioning Device" filed
Jul. 25, 2005 and assigned U.S. application Ser. No. 60/702,393;
"Intralumenal Microwave Device" filed Aug. 12, 2005 and assigned
U.S. application Ser. No. 60/707,797; "Air-Core Microwave Ablation
Antennas" filed Aug. 22, 2005 and assigned U.S. application Ser.
No. 60/710,276; and "Microwave Device for Vascular Ablation" filed
Aug. 24, 2005 and assigned U.S. application Ser. No. 60/710,815;
the entire disclosures of each and all of these applications are
hereby herein incorporated by reference.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0003] This application is related to co-pending U.S.
Non-Provisional Patent Applications entitled "Triaxial Antenna for
Microwave Tissue Ablation" filed Apr. 29, 2004 and assigned U.S.
application Ser. No. 10/834,802; "Segmented Catheter for Tissue
Ablation" filed Sep. 28, 2005 and assigned U.S. application Ser.
No. 11/237,136; "Cannula Cooling and Positioning Device" filed Sep.
28, 2005 and assigned U.S. application Ser. No. 11/237,430;
"Air-Core Microwave Ablation Antennas" filed Sep. 28, 2005 and
assigned U.S. application Ser. No. 11/236,985; and "Microwave
Surgical Device" filed May 24, 2006 and assigned U.S. application
Ser. No. 11/440,331; and to U.S. Provisional Patent Applications
entitled "Segmented Catheter for Tissue Ablation" filed May 10,
2005 and assigned U.S. application Ser. No. 60/679,722; "Microwave
Surgical Device" filed May 24, 2005 and assigned U.S. application
Ser. No. 60/684,065; "Microwave Tissue Resection Tool" filed Jun.
14, 2005 and assigned U.S. application Ser. No. 60/690,370;
"Cannula Cooling and Positioning Device" filed Jul. 25, 2005 and
assigned U.S. application Ser. No. 60/702,393; "Intralumenal
Microwave Device" filed Aug. 12, 2005 and assigned U.S. application
Ser. No. 60/707,797; "Air-Core Microwave Ablation Antennas" filed
Aug. 22, 2005 and assigned U.S. application Ser. No. 60/710,276;
and "Microwave Device for Vascular Ablation" filed Aug. 24, 2005
and assigned U.S. application Ser. No. 60/710,815; the entire
disclosures of each and all of these applications are hereby herein
incorporated by reference.
FIELD OF INVENTION
[0004] The present disclosure relates generally to medical
instruments, and in particular to medical instruments in the field
of tissue resection, coagulation, and hemostasis. Specifically, the
present disclosure relates to a medical tool or device for resonant
delivery of microwave power or energy to tissue for the purpose of
resection and coagulation of vessels.
BACKGROUND
[0005] Use of energy to ablate, resect or otherwise cause necrosis
in diseased tissue has proven beneficial both to human and to
animal health. Electrosurgery is a well-established technique to
use electrical energy at DC or radio frequencies (i.e. less than
500 kHz) to simultaneously cut tissue and to coagulate small blood
vessels. Radio-frequency (RF) ablation of tumor tissue was
developed from the basis of electrosurgery, and has been used with
varied success to coagulate blood vessels while creating zones of
necrosis sufficient to kill tumor tissue with sufficient
margin.
[0006] Limitations of the above techniques center on the need for
ground pads on the skin of the patient to provide a return path for
the current, as well as the undesirable stimulation of the nervous
system as cuts are being made; this usually requires injection of a
temporary paralyzing agent. Limitations of tissue impedance,
particularly as the tissue becomes desiccated or charred during the
course of the procedure, limit the amount of current, and hence the
amount of ablative power, that can be applied to the tissue. This
in turn limits the size of vessels that can be effectively shut
down.
[0007] Thus current procedures are limited when applied to
resection of tumors from highly-vascularized organs, e.g. liver.
Furthermore, the limitations of current and power limit the speed
at which these procedures can be performed. Accordingly, there is a
need for a device which overcomes the problems and disadvantages
associated with current procedures, and which is an improvement
thereover. The present disclosure fulfills this need.
SUMMARY
[0008] The present disclosure relates to delivery of microwave
(e.g. approximately 800 MHz and higher frequencies) power to tissue
for the purpose of ablating tissue or resecting tissue with little
or no loss of blood.
[0009] The device enables delivery of large amounts of power (e.g.
greater than 100 Watts) to tissue without the need for ground pads
since it accomplishes an impedance match between tissue and the
characteristic impedance of the waveguide that feeds power to it.
This is accomplished in a hand-held format similar to many surgical
tools. It can accept a variety of tips for different cutting and
coagulation purposes. Furthermore, because of the impedance
matching, reflected power from the tool is minimized. Reflected
power can further be monitored at the generator or along the feed
cable to use as feedback to the generator power control.
[0010] Numerous other advantages and features of the disclosure
will become readily apparent from the following detailed
description, from the claims and from the accompanying drawings in
which like numerals are employed to designate like parts throughout
the same.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A fuller understanding of the foregoing may be had by
reference to the accompanying drawings wherein:
[0012] FIG. 1 is a cross-sectional view of a preferred embodiment
of the present disclosure, showing the arrangement of an
impedance-matching sleeve and the tip.
[0013] FIG. 2 is a plan view of the preferred embodiment of the
present disclosure encapsulated in a ceramic or plastic
housing.
[0014] FIG. 3 is a schematic circuit diagram for a microwave power
delivery and control system in accordance with the preferred
embodiment of the present disclosure.
DESCRIPTION OF DISCLOSED EMBODIMENT(S)
[0015] While the invention is susceptible of embodiment in many
different forms, there is shown in the drawings and will be
described herein in detail one or more embodiments of the present
disclosure. It should be understood, however, that the present
disclosure is to be considered an exemplification of the principles
of the invention, and the embodiment(s) illustrated is/are not
intended to limit the spirit and scope of the invention and/or the
claims herein.
[0016] With reference to the drawings, an example of the preferred
embodiment of the energy delivery device or microwave tissue
resection tool of the present disclosure is shown in FIG. 1.
[0017] As illustrated in FIG. 1, a semi-rigid coaxial cable,
preferably constructed of copper or silver with a suitable low-loss
dielectric, forms the basis of the device. The cable's center
conductor 10 protrudes from the outer conductor 12 by a length L1,
which is set to be a .lamda./4 (quarter-wavelength) at the
frequency of excitation (e.g. 915 MHz, 2.45 GHz, or another
suitable frequency) in the dielectric environment of the tissue of
interest. The cable can be chosen from commercially-available
standards, but it should be thick enough to be rated for the power
delivered.
[0018] The coaxial cable is shrouded by a dielectric sleeve 14 that
provides both thermal and electrical insulation. Fitted against
this sleeve is a conductive sleeve (e.g. made of copper or silver
or another suitable conductor) whose length is set to be a
.lamda./4 (quarter-wavelength) at the frequency of excitation (e.g.
915 MHz, 2.45 GHz, or another suitable frequency) in the dielectric
environment of the dielectric sleeve 14 and the shroud 30 (FIG. 2).
This conductive sleeve 16 contacts the outer conductor of the
coaxial cable 12 at a point 18, where it is free to slide if
necessary to fine-tune the impedance matching effect. It can then
be fixed in place with adhesive or other suitable mechanism.
[0019] The protrusion of the coaxial cable's center conductor 10 is
shrouded by a non-stick material 20 (e.g. PTFE or Teflon) to
minimize adhesion of the device to the tissue. A tip 22 at the
distal end of the device can be specially formed to maximize the
electric field emanating from it. For example, the tip 22 can be
sharpened and optionally exposed directly to the tissue.
[0020] The device is connected to a feed cable at its proximal end
26. This cable can be optionally connectorized, by attaching any
suitable connector known in the art of connecting cable, to
simplify exchange of the device.
[0021] As shown in FIG. 2, the device can be enshrouded in a
suitable ceramic or plastic housing 30, which can contain cooling
fluid (e.g. air, nitrogen, water, etc) and microwave absorbing
material (e.g. polyiron) to minimize radiation from the tool to the
extent necessary or desired.
[0022] As shown in FIG. 3, the device 30 can be used in a system by
which it is connected to a source of microwave power 36 via a cable
32. A directional coupler or other wave-sampling mechanism 34 in
combination with a power sensor and feedback circuit 38 can be used
to monitor reflected power from the device during the procedure. If
the amount of reflected power exceeds a threshold, power from the
generator 36 can be reduced to minimize heating of the device 30,
while if the amount of reflected power is below a threshold, power
can be increased to speed the procedure.
[0023] It is to be understood that the embodiment(s) herein
described is/are merely illustrative of the principles of the
present invention. Various modifications may be made by those
skilled in the art without departing from the spirit or scope of
the claims which follow.
* * * * *