U.S. patent application number 15/050437 was filed with the patent office on 2017-07-06 for thermally adjustable surgical system and method.
The applicant listed for this patent is Domain Surgical, Inc.. Invention is credited to Kim Manwaring, Mark Manwaring, David McNally.
Application Number | 20170189094 15/050437 |
Document ID | / |
Family ID | 42981559 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170189094 |
Kind Code |
A9 |
Manwaring; Kim ; et
al. |
July 6, 2017 |
THERMALLY ADJUSTABLE SURGICAL SYSTEM AND METHOD
Abstract
A power source delivers oscillating electrical energy to an
electrical conductor, such as a wire or catheter, which is coated
circumferentially with a ferromagnetic material in a selected
region. With high frequency electrical energy, the ferromagnetic
material has a quick response in heating and cooling adjustable by
the controllable power delivery. The ferromagnetic material can be
used for separating tissue, coagulation, tissue destruction or
achieving other desired tissue effects in numerous surgical
procedures.
Inventors: |
Manwaring; Kim; (Phoenix,
AZ) ; Manwaring; Mark; (Deary, ID) ; McNally;
David; (Salt Lake City, UT) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Domain Surgical, Inc. |
Salt Lake City |
UT |
US |
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Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20160166308 A1 |
June 16, 2016 |
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Family ID: |
42981559 |
Appl. No.: |
15/050437 |
Filed: |
February 22, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13830037 |
Mar 14, 2013 |
9265554 |
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15050437 |
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12647371 |
Dec 24, 2009 |
8523852 |
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13830037 |
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12647302 |
Dec 24, 2009 |
8523850 |
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13830037 |
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61170220 |
Apr 17, 2009 |
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61170207 |
Apr 17, 2009 |
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61170203 |
Apr 17, 2009 |
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61170203 |
Apr 17, 2009 |
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61170220 |
Apr 17, 2009 |
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61170207 |
Apr 17, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2018/00642
20130101; A61B 2018/00107 20130101; A61B 18/04 20130101; A61B
18/082 20130101; A61B 2018/00595 20130101; A61B 2018/1412 20130101;
A61B 2017/00141 20130101; A61B 2018/00619 20130101; A61M 25/00
20130101; A61B 2018/00077 20130101; A61B 2018/0013 20130101; A61B
18/08 20130101; A61B 2018/00803 20130101; A61B 2018/128 20130101;
A61B 18/1206 20130101; A61B 2018/00791 20130101; A61B 2018/00095
20130101; Y10T 29/49124 20150115; A61B 17/320068 20130101; A61B
18/085 20130101; A61B 2018/00589 20130101; A61B 2018/00755
20130101; A61M 25/0082 20130101; A61B 18/10 20130101; A61B 18/1492
20130101; A61B 2017/32007 20170801; A61B 2018/00702 20130101; A61B
2017/00876 20130101; A61B 17/00234 20130101; A61B 2017/320069
20170801; A61B 2018/00601 20130101; A61B 2018/00958 20130101; A61B
17/3211 20130101; A61B 2018/00577 20130101; A61B 2017/00973
20130101; A61B 2017/320082 20170801; A61B 2018/00654 20130101; A61B
2018/00714 20130101; A61B 2018/1407 20130101 |
International
Class: |
A61B 18/10 20060101
A61B018/10; A61B 18/08 20060101 A61B018/08 |
Claims
1.-55. (canceled)
56. A thermally adjustable surgical tool comprising: an electrical
conductor; a ferromagnetic coating covering at least a portion of
the electrical conductor; a power supply disposed in communication
with the electrical conductor configured to produce oscillating
electrical energy to be delivered to the electrical conductor; and
wherein the power supply is configured to adjust the oscillating
electrical energy.
57. The thermally adjustable surgical tool of claim 56, further
comprising a sensor configured to conduct a measurement.
58. The thermally adjustable surgical tool of claim 57, further
comprising a sensor configured to conduct a measurement proximate
to the ferromagnetic coating.
59. The thermally adjustable surgical tool of claim 57, wherein the
oscillating electrical energy comprises at least one signal
characteristic, and wherein the tool is configured to monitor the
signal characteristic to achieve a desired temperature of the
ferromagnetic coated electrical conductor.
60. The thermally adjustable surgical tool of claim 57, wherein the
power supply is configured to adjust the oscillating electrical
energy delivered to the electrical conductor in response to the
measurement of the sensor.
61. The thermally adjustable surgical tool of claim 61, comprising
a plurality of electrical conductors and a plurality of
ferromagnetic coatings, wherein each of the plurality of
ferromagnetic coatings covers at least a portion of one of the
plurality of electrical conductors.
62. The thermally adjustable surgical tool of claim 61, wherein the
power supply is configured to individually adjust the oscillating
electrical energy delivered to at least one of the plurality of
electrical conductors.
63. The thermally adjustable surgical tool of claim 61, wherein the
power supply is configured to adjust the oscillating electrical
energy jointly delivered to at least two or more of the plurality
of electrical conductors.
64. The thermally adjustable surgical tool of claim 61, wherein at
least a portion of the plurality of ferromagnetic coatings are
configured to provide different tissue effects.
65. The thermally adjustable surgical tool of claim 56, further
comprising a user control for adjusting the oscillating electrical
energy delivered to the electrical conductor.
66. The thermally adjustable surgical tool of claim 56, wherein the
power supply responds to a load prediction module configured to
predict a load characteristic of the electrical conductor with the
ferromagnetic coating.
67. The thermally adjustable surgical tool of claim 56, further
comprising a handle and a plug, wherein the handle is configured to
receive the plug and the plug is configured to receive the
electrical conductor, and wherein the plug includes a data module
configured to communicate the load characteristic of the electrical
conductor to the power supply.
68. The thermally adjustable surgical tool of claim 67, wherein the
power supply is further configured to use the predicted load
characteristic to adjust the oscillating electrical energy
delivered to the electrical conductor to achieve a desired
temperature of the ferromagnetic coating.
69. The thermally adjustable surgical tool of claim 67, wherein the
power supply is further configured to use the predicted load
characteristic to adjust the oscillating electrical energy
delivered to the electrical conductor.
70. The thermally adjustable surgical tool of claim 57, wherein the
sensor comprises a temperature sensor proximate to the
ferromagnetic coating.
71. The thermally adjustable surgical tool of claim 56, wherein the
tool is configured to impedance match the ferromagnetic coated
electrical conductor.
72. The thermally adjustable surgical tool of claim 56, further
comprising an impedance matching circuit.
73. The thermally adjustable surgical tool of claim 56, wherein the
oscillating electrical energy is adjusted by at least one of: pulse
width modulation, amplitude modulation, frequency modulation, and
detuning an impedance matching circuit.
Description
RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Patent Application Ser. No. 61/170,203, filed Apr. 17,
2009, U.S. Provisional Patent Application Ser. No. 61/170,220,
filed Apr. 17, 2009, and U.S. Provisional Patent Application Ser.
No. 61/170,207, filed Apr. 17, 2009 which are incorporated hereby
by references in their entirety.
[0002] This application is part of a group of similar applications
including U.S. patent application Ser. No. 12/647,340, filed Dec.
24, 2009, Attorney Docket Number 4340.NEXS.NP; U.S. patent
application Ser. No. 12/647,344, filed Dec. 24, 2009, Attorney
Docket Number 4340.NEXS.NP2; U.S. patent application Ser. No.
12/647,350, filed Dec. 24, 2009, Attorney Docket Number
4340.NEXS.NP3; U.S. patent application Ser. No. 12/647,355, filed
Dec. 24, 2009, Attorney Docket Number 4340.NEXS.NP4; U.S. patent
application Ser. No. 12/647,358, filed Dec. 24, 2009, Attorney
Docket Number 4340.NEXS.NP5; U.S. patent application Ser. No.
12/647,363, filed Dec. 24, 2009, Attorney Docket Number
4340.NEXS.NP6; U.S. patent application Ser. No. 12/647,302 filed
Dec. 24, 2009, Attorney Docket Number 4389.NEXS.NP2; U.S. patent
application Ser. No. 12/647,329, filed Dec. 24, 2009, Attorney
Docket Number 4390.NEXS.NP1; U.S. patent application Ser. No.
______ filed Dec. 24, 2009, Attorney Docket Number 4390.NEXS.NP2;
and U.S. patent application Ser. No. ______ filed Dec. 24, 2009,
Attorney Docket Number 4390.NEXS.NP3; and U.S. patent application
Ser. No. ______ filed Dec. 24, 2009, Attorney Docket Number
4390.NEXS.NP4, each of which is incorporated hereby by references
in its entirety.
BACKGROUND OF THE INVENTION
[0003] 1. The Field of the Invention
[0004] The present invention relates to surgical tools. More
specifically, the present invention relates to thermally adjustable
tools used in open and minimally invasive surgical procedures and
interventional surgical and therapeutic procedures.
[0005] 2. State of the Art
[0006] Surgery generally involves cutting, repairing and/or
removing tissue or other materials. These applications are
generally performed by cutting tissue, fusing tissue, or tissue
destruction.
[0007] Current electrosurgery modalities used for cutting,
coagulating, desiccating, ablating, or fulgurating tissue, have
undesirable side effects and drawbacks.
[0008] Monopolar and bipolar electrosurgery modalities generally
have disadvantages relating to "beyond the tip" effects. These
effects are caused by passing alternating current through tissues
in contact with conducting instruments or probes.
[0009] Monopolar surgical instruments require electric current to
pass through the patient. A return electrode is placed on the
patient, often on the patient's thigh. Electricity is conducted
from a "knife" electrode through the tissue and returns through the
return electrode. Other forms of monopolar instruments exist, such
as those which use the capacitive effect of the body to act as the
return electrode or ground.
[0010] A low voltage high frequency waveform will incise, but has
little hemostatic effect. A high voltage waveform will cause
adjacent tissue hemostasis and coagulation. Therefore, when
hemostasis is desirable, high voltage is used. The high voltage
spark frequently has deeper tissue effects than the cut because the
electricity must pass through the patient. The damage to the tissue
extends away from the actual point of coagulation. Furthermore,
there are complaints of return electrode burns. Yet, any reduction
of voltage reduces the effectiveness of hemostasis. Further, the
temperature of the spark or arc cannot be precisely controlled,
which can lead to undesirable charring of target tissue.
[0011] Bipolar surgical instruments can produce tissue damage and
problems that are similar to monopolar devices, such as sparking,
charring, deeper tissue effects and electric current damage away
from the application of energy with varying effects due to the
differing electrical conductivity of tissue types, such as nerve,
muscle, fat and bone, and into adjacent tissues of the patient.
However, the current is more, but not completely, contained between
the bipolar electrodes. These electrodes are also generally more
expensive because there are at least two precision electrodes that
must be fabricated instead of the one monopolar electrode.
[0012] Electrocautery resistive heating elements reduce the
drawbacks associated with charring and deeper tissue damage caused
by other electrosurgery methods. However, such devices often
present other tradeoffs, such as the latency in controlling heating
and cooling time, and effective power delivery. Many resistive
heating elements have slow heating and cooling times, which makes
it difficult for the surgeon to work through or around tissue
without causing incidental damage.
[0013] Tissue destruction instruments generally heat tissue to a
predetermined temperature for a period of time to kill, or ablate,
the tissue. In some controlled heating of tissues, a laser is
directed to an absorptive cap to reach and maintain a predetermined
temperature for a predetermined amount of time. While this provides
the benefits of thermal heating, it is expensive due to the
complexity and expense of laser hardware.
[0014] In another tissue destruction procedure, a microwave antenna
array is inserted into the tissue. These arrays are powered by
instruments that cause microwave energy to enter and heat the
tissue. While such devices are often effective at killing, or
ablating, the desired tissue, they often cause deeper tissue
effects than the desired area. Additionally the procedures can
require expensive equipment.
[0015] Tissue destruction with resistively heated tools can produce
unintended collateral tissue damage, in addition to having slow
heating and cooling attributes.
[0016] Use of ferrite beads and alloy mixes in ceramics have been
examined as alternatives. When excited by the magnetic field
associated with high frequency current passing through a conductor,
ferrite beads and alloy mixes in ceramics can reach high
temperatures very quickly. However, one major problem with the use
of these materials is that a large temperature differential can
cause the material to fracture, especially when it comes into and
out of contact with liquids. In other words, if a hot ferrite
surgical instrument is quenched by a cooler pool of liquid, such as
blood or other body fluids, the material's corresponding
temperature drops rapidly and may cause the material to fracture.
These fractures not only cause the tool to lose its effectiveness
as a heat source, because the magnetic field is disrupted, but may
require extraction of the material from the patient. Obviously, the
need to extract small pieces of ferrite product from a patient is
highly undesirable. Thus, there is a need for an improved thermal
surgical tool.
SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to provide an
improved thermally adjustable surgical or therapeutic tool and a
method of using the same.
[0018] According to one aspect of the invention, a thermal surgical
tool system is provided with a ferromagnetic coating over a
conductor and an oscillating electrical energy source for
generating heat at the location of the coating. The oscillating
electrical energy may cause inductive heating of the ferromagnetic
coating to thereby enable the cutting, ablating, etc., of
tissue.
[0019] In accordance with another aspect of the invention, the
thermal surgical tool system is provided with a power control
mechanism which enables the surgeon to quickly adjust the power to
the surgical or therapeutic tool to achieve desired tissue welding,
cutting, ablation, vaporization, etc., depending on the amount of
power supplied to the tool. This may provide the advantage of
allowing the surgeon to only deliver a thermal effect at desired
locations, which may also prevent the accidental delivery of
undesired thermal effects while waiting for the tool to cool.
[0020] According to another aspect of the invention, a thermal
surgical tool system may be configured so that the power delivery
to a ferromagnetic element may be altered by the surgeon in near
real-time to achieve different tissue effects, including
hemostasis, tissue welding and tissue destruction.
[0021] According to another aspect of the invention, controlled
thermal tissue destruction may be performed.
[0022] According to another aspect of the invention, the coated
conductor may be powered by a generator and incorporated in a
catheter or endoscope, which could also provide for sensing,
viewing, aspiration, irrigation, delivery of a thermally-cured
material, or removal of a thermally-melted or ablated material,
through a channel.
[0023] According to another aspect of the invention a catheter may
be used to deliver a ferromagnetic coated conductor into an area
for a desired therapeutic effect.
[0024] According to another aspect of the invention, the heating of
the ferromagnetic coating may be directed by changing
characteristics of the power delivered to the conductor.
[0025] According to another aspect of the invention, a plurality of
ferromagnetic conductors may be disposed on a primary geometry,
each conductor being individually controlled such that the
ferromagnetic conductors may provide different tissue effects at
the same time.
[0026] These and other aspects of the present invention are
realized in a thermally adjustable surgical tool as shown and
described in the following figures and related description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Various embodiments of the present invention are shown and
described in reference to the numbered drawings wherein:
[0028] FIG. 1 shows a perspective view of a thermal surgical tool
system in accordance with the principles of the present
invention;
[0029] FIG. 2 shows a perspective view of an alternate embodiment
of a thermal surgical tool system in accordance with the present
invention;
[0030] FIG. 3 shows a diagram of a thermal surgical tool system in
accordance with the principles of the present invention;
[0031] FIG. 4A shows a thermal surgical tool system with heat
prevention terminals, heat sink, and wireless communication
devices;
[0032] FIG. 4B shows a thermal surgical tool system with impedance
matching network;
[0033] FIG. 5A shows a close-up, side cross-sectional view of a
single layer ferromagnetic coated conductor tip in accordance with
one aspect of the present invention;
[0034] FIG. 5B shows an electrical equivalent representation of
FIG. 5A's ferromagnetic coated conductor;
[0035] FIG. 6 shows a close-up, side cross-sectional view of a
single layer ferromagnetic coated conductor tip with a thermal
insulator in accordance with one aspect of the present
invention;
[0036] FIG. 7A shows a close-up view of ferromagnetic coated
conductor surgical tool tip with a loop geometry in accordance with
one aspect of the present invention;
[0037] FIG. 7B shows a close-up view of a ferromagnetic coated
conductor surgical tool tip with a generally square geometry in
accordance with one aspect of the present invention;
[0038] FIG. 7C shows a close-up view of a ferromagnetic coated
conductor surgical tool tip with a pointed geometry;
[0039] FIG. 7D shows a close-up view of a ferromagnetic coated
conductor surgical tool tip with an asymmetrical loop geometry;
[0040] FIG. 7E shows a close-up view of a ferromagnetic coated
conductor surgical tool tip with a hook geometry in which the
concave portion may be used for therapeutic effect, including
cutting;
[0041] FIG. 7F shows a close up view of a ferromagnetic coated
conductor surgical tool tip with a hook geometry in which the
convex portion may be used for therapeutic effect, including
cutting;
[0042] FIG. 7G shows a close up view of a ferromagnetic coated
conductor surgical tool tip with an angled geometry;
[0043] FIG. 8 shows a cut-away view of a retracted snare;
[0044] FIG. 9A shows a side view of an extended snare;
[0045] FIG. 9B shows an alternate embodiment of an extended
snare;
[0046] FIG. 10A shows a close-up view of a ferromagnetic coated
conductor surgical tool with a loop geometry and linear array of
coatings;
[0047] FIG. 10B shows a close up view of a ferromagnetic coated
conductor surgical tool with an alternate hook geometry and linear
array;
[0048] FIG. 11 shows a cut-away view of a retracted snare with an
array of coatings;
[0049] FIG. 12 shows a side view of an extended snare with a linear
array of coatings;
[0050] FIG. 13 shows an axial cross-sectional view of a single
layer ferromagnetic coated conductor surgical tool in the
ferromagnetic-coated region;
[0051] FIG. 14A shows a perspective view of a multi-layer
ferromagnetic coated conductor surgical tool tip;
[0052] FIG. 14B shows a side cross-sectional view of a multi-layer
ferromagnetic coated conductor surgical tool tip shown in 14A;
[0053] FIG. 15 shows an axial cross-section of the multi-layer
ferromagnetic coated conductor surgical tool tip shown in FIG.
14A;
[0054] FIG. 16 shows a cross-sectional view of a flattened side
cylindrical geometry ferromagnetic coated conductor showing
electromagnetic lines of flux;
[0055] FIG. 17 shows a closed conductor tip in accordance with
another aspect of the present invention;
[0056] FIG. 18A shows a single edge ferromagnetic coated conductor
surgical tool tip in accordance with one aspect of the
invention;
[0057] FIG. 18B shows a double edge ferromagnetic coated conductor
surgical tool tip;
[0058] FIG. 18C shows a three wire ferromagnetic coated conductor
surgical tool tip;
[0059] FIG. 18D shows a receptacle for the tips shown in FIGS. 18A
through 18C;
[0060] FIG. 19A shows a normally cold cutting scalpel with
alternate inductive ferromagnetic thermal function;
[0061] FIG. 19B shows an alternate embodiment of a normally cold
cutting scalpel with alternate inductive ferromagnetic thermal
function;
[0062] FIG. 20A shows a thermal surgical tool with a spatula shaped
geometry;
[0063] FIG. 20B shows a thermal surgical tool with a spatula shaped
geometry in a forceps configuration;
[0064] FIG. 20C shows a top view of the thermal surgical tool of
FIG. 20A with the ferromagnetic coated conductor upon the primary
geometry;
[0065] FIG. 20D shows a top view of the thermal surgical tool of
FIG. 20A with the ferromagnetic coated conductor embedded within
the primary geometry;
[0066] FIG. 21A shows a thermal surgical tool with a ball shaped
geometry and horizontal winding;
[0067] FIG. 21B shows an alternate embodiment of a thermal surgical
tool with a ball shaped geometry and horseshoe configuration;
[0068] FIG. 21C shows an alternate embodiment of a thermal surgical
tool with a ball shaped geometry and vertical orientation;
[0069] FIG. 22A shows a thermal surgical tool with a pointed
geometry;
[0070] FIG. 22B shows a thermal surgical tool with a pointed
geometry in a forceps configuration;
[0071] FIG. 22C shows a thermal surgical tool having two different
activatable thermal zones;
[0072] FIG. 23A shows a perspective view of a catheter having a
coil of ferromagnetic coated conductor disposed around the tip of
the catheter;
[0073] FIG. 23B shows a perspective view of an ferromagnetic coated
conductor surgical tool catheter tip;
[0074] FIG. 24 shows a side view of an alternate embodiment of an
ferromagnetic coated conductor surgical tool catheter tip;
[0075] FIG. 25 shows an alternate embodiment of a ferromagnetic
coated conductor surgical tool ferromagnetic tip disposed within an
endoscope;
[0076] FIG. 26 shows a tissue ablation tool; and
[0077] FIG. 27 shows a thermal spectrum as related to tissue
effects.
[0078] It will be appreciated that the drawings are illustrative
and not limiting of the scope of the invention which is defined by
the appended claims. The embodiments shown accomplish various
aspects and objects of the invention. It is appreciated that it is
not possible to clearly show each element and aspect of the
invention in a single figure, and as such, multiple figures are
presented to separately illustrate the various details of the
invention in greater clarity. Similarly, not every embodiment need
accomplish all advantages of the present invention.
DETAILED DESCRIPTION
[0079] The invention and accompanying drawings will now be
discussed in reference to the numerals provided therein so as to
enable one skilled in the art to practice the present invention.
The drawings and descriptions are exemplary of various aspects of
the invention and are not intended to narrow the scope of the
appended claims.
[0080] As used herein, the term "ferromagnetic," "ferromagnet," and
"ferromagnetism" refers to any ferromagnetic-like material that is
capable of producing heat via magnetic induction, including but not
limited to ferromagnets and ferrimagnets.
[0081] Turning now to FIG. 1, there is shown a perspective view of
a thermal surgical tool system, generally indicated at 10. As will
be discussed in additional detail below, the thermal tool system
preferably uses a ferromagnetic coated conductor to treat or
destroy tissue (i.e. endothelial tissue welding, homeostasis,
ablation, etc).
[0082] It will be appreciated that the thermal surgical tool uses
heat to incise tissue and does not cut tissue in the sense of a
sharp edge being drawn across the tissue as with a conventional
scalpel. While the embodiments of the present invention could be
made with a relatively sharp edge so as to form a cutting blade,
such is not necessary as the heated coating discussed herein will
separate tissue without the need for a cutting blade or sharp edge.
However, for convenience, the term cutting is used when discussing
separating tissue.
[0083] In the embodiment shown as thermal surgical tool system 10,
a control mechanism, such as a foot pedal 20 is used to control
output energy produced by a power subsystem 30. The energy from the
power subsystem 30 may be sent via radio frequency (RF) or
oscillating electrical energy along a cable 40 to a handheld
surgical tool 50, which contains a conductor 60 having a section
thereof coated with a ferromagnetic coating 65. The ferromagnetic
coating 65 may transfer the electrical energy into available
thermal energy via induction and corresponding hysteresis losses in
the ferromagnetic material disposed around a conductor wire 66.
(While conductor wire is used for ease of reference, it will be
appreciated that the conductor material need not be a wire and
those skilled in the art will be familiar with multiple conductors
which will work in light of the disclosure of the present
invention).
[0084] Application of a magnetic field (or magnetizing) to the
ferromagnetic coating may produce an open loop B-H curve (also
known as an open hysteresis loop), resulting in hysteresis losses
and the resultant thermal energy. Electrodeposited films, such as a
nickel-iron coating like PERMALLOY.TM., may form an array of
randomly aligned microcrystals, resulting in randomly aligned
domains, which together may have an open loop hysteresis curve when
a high frequency current is passed through the closely coupled
conductor.
[0085] The RF energy may travel along the conductor's surface in a
manner known as the "skin effect". The alternating RF current in
the conductor's surface produces an alternating magnetic field,
which may excite the domains in the ferromagnetic coating 65 that
is in close proximity to the surface of the conductor. As the
domains realign with each oscillation of the current, hysteresis
losses in the coating may cause inductive heating.
[0086] The RF conductor from the signal source up to and including
the tip, may form a resonant circuit at a specific frequency (also
known as a tuned circuit). Changes in the tip "detune" the circuit.
Thus, should the ferromagnetic coating 65 or the conductor wire 66
become damaged, the circuit may likely become detuned. This
detuning should reduce the efficiency of the heating of the
ferromagnetic coating 65 such that the temperature will be
substantially reduced. The reduced temperature should ensure little
or no tissue damage after breakage.
[0087] A breakage or other fault may also be detected by a sensor.
Interruptions to normal circuit operation may thus be detected and
cause the surgical system to shut down. In one embodiment, current
is monitored. If a sudden unexpected increase in current is
detected, the system may shut down because the ferromagnetic
coating may be no longer be dissipating the power it should.
Similarly, impedance may be monitored and used as an indicator of a
system fault.
[0088] It should be understood that the handheld surgical tool 50
may include indicia of the power being applied and may even include
a mechanism for controlling the power. Thus, for example, a series
of lights 52 could be used to indicate power level, or the handheld
surgical tool 50 could include a switch, rotary dial, set of
buttons, touchpad or slide 54 that communicates with the power
source 30 to regulate power and thereby affect the temperature at
the ferromagnetic coating 65 to having varying effects on tissue.
These indicia may display the current status as represented by the
power source and communicated to a user adjustable control by the
power source. While the controls are shown on the foot pedal 20 or
the handheld surgical tool 50, they may also be included in the
power subsystem 30 or even a separate control instrument. Safety
features such as a button or touchpad that must be contacted to
power the handheld surgical tool 50 may be employed, and may
include a dead man's switch.
[0089] While the ferromagnetic coating 65 heats through induction,
it also provides a temperature cap due to its Curie temperature. A
Curie temperature is the temperature at which the material becomes
paramagnetic, such that the alignment of each domain relative to
the magnetic field decreases to such an extent that the magnetic
properties of the coating are lost. When the material becomes
paramagnetic, the heating caused by induction may be significantly
reduced or even cease. This causes the temperature of the
ferromagnetic material to stabilize around the Curie temperature if
sufficient power is provided to reach the Curie temperature. Once
the temperature has dropped below the Curie temperature, induction
may again start causing heating of the material up to the Curie
temperature. Thus, the temperature in the ferromagnetic coating may
reach the Curie temperature during inductive heating with the
application of sufficient power, but will not likely exceed the
Curie temperature.
[0090] The thermal surgical tool system 10 allows the power output
to be adjustable in order to adjust the temperature of the tool and
its effect on tissue. This adjustability gives the surgeon precise
control over the effects that may be achieved by the handheld
surgical tool 50. Tissue effects such as cutting, hemostasis,
tissue welding, tissue vaporization and tissue carbonization occur
at different temperatures. By using the foot pedal 20 (or some
other user control) to adjust the power output, the surgeon (or
other physician, etc.) can adjust the power delivered to the
ferromagnetic coating 65 and consequently control the tissue
effects to achieve a desired result.
[0091] Thermal power delivery can be controlled by varying the
amplitude, frequency or duty cycle of the alternating current
waveform, or alteration of the circuit to affect the standing wave
driving the ferromagnetic coated conductor, which may be achieved
by input received by the foot pedal 20, the power subsystem 30, or
the controls on the handheld surgical tool 50.
[0092] For example, it is known that different temperatures are
desirable for inducing different effects on tissue. As will be
explained in additional detail below, certain temperatures can be
used for welding tissues, while other temperatures will induce
cutting, tissue ablation and vaporization.
[0093] One advantage of the present invention is that it enables
the surgeon to control power to the system, which ultimately
affects the temperature at the ferromagnetic coating 65 which can
be applied to the tissue. Power can be adjusted by multiple
methods. Pulse width modulation can be used to change the amount of
time the ferromagnetic coating 65 is being heated, thereby
controlling the temperature. Amplitude modulation can be used to
likewise control the power through the system and the ultimate
temperature dynamics of the ferromagnetic coating 65. As the RF
conductor from the signal source to the tip, including the tip, may
form a resonant circuit at a specific frequency (also known as a
tuned circuit), changes in the tip "detune" the circuit. Thus,
frequency modulation can be used to effectively temporarily detune
the circuit and thereby ultimately control the temperature for
tissue welding, cutting, etc. An exemplary circuit may use a phase
locked loop or frequency synthesizer to adjust frequency.
[0094] Power to the system can be controlled by a regulating
structure, such as, for example, the foot pedal 20. The pedal may
have set points which indicate to the surgeon the power which is
being supplied. This can be accomplished, for example, by having a
pedal which has five positions, with each position requiring more
force. The change in force required will alert the surgeon to the
temperature range that is being applied.
[0095] The power controller, such as a pedal, can also be used to
send a signal to the surgeon as to the power level being applied at
the ferromagnetic coating 65 or the energy available at the coating
available for delivery to the tissue. This could be an auditory or
visual indicator 22 which gives the surgeon a signal to indicate
the power level. For example, if five power levels are provided, an
auditory alarm may indicate the power level being applied. One
chime for level or range 1, two chimes for level or range 2, three
chimes for level or range 3, etc. Similarly, five distinct auditory
signal tones could be used to indicate the five power levels.
[0096] Likewise the tool 50 could include indicia of the power
being applied and could even include a mechanism for controlling
the power. Thus, for example, a series of lights 52 could be used
to indicate power level, or the tool 50 could include a switch,
rotary dial, set of buttons, touchpad or slide 54 that communicates
with the power source 30 to regulate power and thereby affect the
temperature at the ferromagnetic coating 65 to having varying
effects on tissue. While the controls are shown on the foot pedal
20 or the tool 50, it may also be included in the power subsystem
30 or even a separate control instrument. Similarly, safety
features such as a button or touchpad that must be contacted to
power the tool 50 may be employed, such as a dead man's switch.
[0097] One additional advantage achieved by the inductive heating
is that the ferromagnetic material can be heated to a cutting
temperature in a small fraction of a second (typically as short one
quarter of a second). Additionally, because of the relatively low
mass of the coating, the small thermal mass of the conductor, and
the localization of the heating to a small region due to
construction of the handheld surgical tool 50, the material will
also cool extremely rapidly (i.e. approximately one half of a
second). This provides a surgeon with a precise thermal tool while
reducing accidental tissue damage caused by touching tissue when
the thermal tool is not activated.
[0098] It will be appreciated that the time period required to heat
and cool the handheld surgical tool 50 will depend, in part, on the
relative dimensions of the conductor 60 and the ferromagnetic
coating 65 and the heat capacity of the structure of the surgical
tool. For example, the above time periods for heating and cooling
of the handheld surgical tool 50 can be achieved with a tungsten
conductor having a diameter of about 0.375 mm and a ferromagnetic
coating of a Nickel Iron alloy (such as NIRON.TM. available from
Enthone, Inc. of West Haven, Conn.) about the tungsten conductor
about 0.0375 mm thick and two centimeters long.
[0099] One advantage of the present invention is that a sharp edge
is not needed. When power is not being supplied to the surgical
tool, the tool will not inadvertently cut tissue of the patient or
of the surgeon if it is dropped or mishandled. If power is not
being supplied to the conductor wire 66 and coating 65, the
"cutting" portion of the tool may be touched without risk of
injury. This is in sharp contrast to a cutting blade which may
injure the patient or the surgeon if mishandled.
[0100] Other additions may also be placed on the handpiece in
various locations. This may include a sensor stem 12 including a
sensor to report temperature or a light to illuminate the surgical
area.
[0101] Turning now to FIG. 2, a perspective view of an alternate
embodiment of a thermal surgical system 10 is shown. In FIG. 2, the
power source 30 is contained within the foot pedal 20. Depending on
the application and power required, the instrument may even be
entirely battery powered for relatively low power applications. An
alternate embodiment for low power requirements may include the
battery, power adjustment and power delivery, all self-contained in
the handle 51 of the handheld surgical tool 50. Furthermore, a
wireless communication module can be employed to send and receive
information from the handheld surgical tool 50, including status
and control settings that would enable users to monitor system
performance and alter power settings remotely from the handheld
surgical tool 50 itself.
[0102] It is our understanding that this thermal solution may
provide advantages over monopolar and bipolar electrical systems
currently available because the thermal damage may remain very
close to the ferromagnetic surface of the coated region, whereas
monopolar and bipolar electrical tissue ablation may frequently
cause tissue damage for a distance away from the point of contact.
It is our understanding that this method may also overcome
disadvantages of other thermal devices based upon resistive
heating, which may require more time to heat and cool, and thus
present greater patient risk, while potentially having higher power
requirements at the point of heating.
[0103] Furthermore, the thin ferromagnetic coating 65, disposed
along a small segment of the conductor, may reduce the heating of
other non-target material in the body, such as blood when working
within the heart in atrial ablation--which can lead to
complications if a clot is formed. The small thermal mass of the
conductor wire 66, and localization of the heating to a small
region provided by the construction of the tool (i.e. ferromagnetic
coating 65 and adjacent structures) provides a reduced thermal path
for heat transfer in directions away from the location of the
ferromagnetic coating 65. This reduced thermal path may result in
the precise application of heat at only the point desired. As this
technology alone does not employ a spark or an arc like monopolar
or bipolar technology, risks of ignition, such as by anesthetic
gasses within or around the patient by sparks, are also
reduced.
[0104] The thermal surgical tool system 10 may be used for a
variety of therapeutic means--including sealing, "cutting" or
separating tissue, coagulation, or vaporization of tissue. In one
configuration, the thermal surgical tool system 10 may be used like
a knife or sealer, wherein the surgeon is actively "cutting" or
sealing tissue by movement of the ferromagnetic coating 65 through
tissue. The thermal action of the embodiments disclosed here may
have distinct advantages including substantial reduction, if not
elimination, of deep tissue effects compared with those associated
with monopolar and bipolar RF energy devices.
[0105] In another configuration, the ferromagnetic coated conductor
60 may be inserted into a lesion and set to a specific power
delivery or variable power delivery based on monitored temperature.
The thermal effects on the lesion and surrounding tissue may be
monitored until the desired thermal effect is achieved or undesired
effects are noticed. One advantage of the application of the
ferromagnetic coated conductor is that it may be cost-effective
compared to microwave or thermal laser modalities and avoids the
undesired tissue effects of microwave lesion destruction. Thus, for
example, a surgeon can insert the ferromagnetic coated conductor
into a tumor or other tissue to be destroyed and precisely control
the tissue damage that is created by activating the handheld
surgical tool 50.
[0106] Sensors may be used to monitor conditions of the handheld
surgical tool 50, the electrical path, or the tissue, such as an
infrared detector on sensor stem 12. For instance, the temperature
of the device or tissue may be important in performing a procedure.
A sensor in the form of a thermocouple, a junction of dissimilar
metals, thermistor or other temperature sensor may detect or
conduct a measurement of the temperature at or near the
ferromagnetic coating 65 or tissue. The sensor may be part of the
device, such as a thermocouple placed as a part of the conductor,
along, adjacent or near the ferromagnetic coating, or separate from
the handheld surgical tool 50, such as a separate tip placed near
the tissue or ferromagnetic coating 65. Some sensors may measure
indicators that correlate to a desired measurement, but are
indirectly related. For example, temperatures may also be
correlated with tissue effects, seen in FIG. 27. Other useful
conditions to monitor may include, but are not limited to, power
delivered at the coating, tissue color, spectral absorption or
reflection, conductor or tissue temperature range, tissue water
content, proximity between the tissue and the conductor, tissue
type, transferred heat, tissue status, impedance, resistance,
return current, standing wave ratio (SWR), reflected power,
reactance, center frequency, phase shift, voltage, current and
visual feedback (i.e. a camera, fiberoptic or other visualization
device).
[0107] The power supply may be configured to respond to sensor
feedback. Depending on the desired application, the sensor may
provide useful information in regulating or determining the output
of the power supply. In one embodiment, the sensor sends a
temperature reading to the power supply. The power supply may then
increase or decrease power delivery to remain at or near the
desired temperature range. In another embodiment, the sensor
communicates a water content reading to the power supply during
tissue ablation. If the water content drops below a desired level,
the power supply may reduce the power setting as the tissue may be
sufficiently dessicated. Other sensors may provide useful input
that may call for other settings to change on the power supply,
such as waveform, duration, timing or power settings.
[0108] The handheld surgical tool 50 may be configured for repeat
sterilization or single patient uses. More complex devices may be
useful for repeat sterilization, while more simple devices may be
more useful for single patient use.
[0109] A method for treating or cutting tissue may include the
steps of: selecting a surgical tool having a cutting edge and a
conductor disposed adjacent the cutting edge, at least a portion of
which is coated with a ferromagnetic material; cutting tissue with
the cutting edge; and applying oscillating electrical energy to the
conductor to heat the ferromagnetic material and thereby treating
the cut tissue.
[0110] Optional steps of the method may include the steps of:
causing hemostasis within the cut tissue; using the heated
ferromagnetic material to incise tissue; or using the heated
ferromagnetic material to cause vascular endothelial welding.
[0111] Referring now to FIG. 3, a diagram of an embodiment of the
adjustable thermal surgical tool system 10 is shown. The power
delivery to the ferromagnetic coating 65 is controlled by a
modulated high frequency waveform. The modulated waveform allows
power delivery to be controlled in a manner that adjustably
modifies, allows or blocks portions of the waveform based on the
desired power delivery.
[0112] In FIG. 3, an initial waveform 110 is passed through a
modulator 120 receiving commands from a foot pedal 20. The waveform
is created by an oscillator 130 to the desired frequency, and
modulated by the modulator 120, which may include, but is not
limited to, one or more of amplitude, frequency or duty cycle
modulation, including a combination thereof. The resultant signal
is then amplified by an amplifier 140. The amplified signal is sent
across a tuned cable 150, meaning that the cable is tuned to
provide a standing wave with maximum current and minimum voltage at
the location of the ferromagnetic coating 65 of the handheld
surgical tool 50. Alternatively, the cable 150 may not be tuned,
but a circuit may be placed in the handle 51 to impedance match the
ferromagnetic coated conductor 60 as a load to the power source
30.
[0113] The thermal surgical tool system 10 may be tuned by
specifying the location of the ferromagnetic coating 65 with
respect to the amplifier 140 (such as cable length) and tuning the
high frequency signal to approximately a resonant standing wave
such that current is maximized at the location of the ferromagnetic
coating 65.
[0114] It should be recognized that the surgical tool may operate
in a dynamic environment. Thus when used herein, approximately a
standing wave means that a circuit may be tuned such that the
signal may be near an optimal standing wave but may not achieve it,
may only achieve the wave for small amounts of time, or may
successfully achieve a standing wave for longer periods of time.
Similarly, any use of "standing wave" without the modifier of
approximate should be understood to be approximate in the context
of the thermal surgical tool.
[0115] One method for achieving such current maximization is to
connect the ferromagnetic coated conductor 60 to a cable 150 that
is effectively an odd multiple of one-quarter wavelengths in length
and connected to the output of the amplifier 140. The design of the
circuit having a resonant standing wave is intended to optimize
power delivery to the ferromagnetic coating. However, in one
embodiment, the power source 30 could be positioned at the location
of (or closely adjacent to) the ferromagnetic coating 65, and
tuning could be achieved with electrical components, all within a
single handheld, battery-powered instrument. Alternatively,
electrical components necessary for impedance matching can be
located at the output stage of the amplifier 140. Further,
electrical components, such as a capacitor or inductor, can be
connected in parallel or series to the ferromagnetic coated
conductor 60 at the location of the connection of the conductor
wire 66 to the cable 150, in order to complete a resonant
circuit.
[0116] Dynamic load issues can be caused by the interaction of the
ferromagnetic coated conductor 60 with various tissues. These
issues may be minimized by the standing current wave (or at least
one standing wave or waveform) being maximized at the load
location. Multiple different frequencies can be used, including
frequencies from 5 megahertz to 24 gigahertz. It is currently
believed that that a waveform, preferably between 40 megahertz to
928 megahertz is desirable.
[0117] In some regulated countries it may be preferable choose
frequencies in the ISM bands such as bands with the center
frequencies of 6.78 MHz, 13.56 MHz, 27.12 MHz, 40.68 MHz, 433.92
MHz, 915 MHz, 2.45 GHz, 5.80 GHz, 24.125 GHz, 61.25 GHz, 122.5 GHz,
245 GHz. In one embodiment, the oscillator 130 uses an ISM Band
frequency of 40.68 MHz, a class E amplifier 140, and a length of
coaxial cable 150, all of which may be optimized for power delivery
to a ferromagnetic coated tungsten conductor 60 with a
ferromagnetic coating 65 consisting of a thickness of between 0.05
micrometer and 500 micrometers, and preferably between 1 micrometer
and 50 micrometers. A useful estimate may be to start the
ferromagnetic coating thickness at 10% of the conductor diameter,
and up to 5 cm long. However, the ferromagnetic coating may be
disposed as far along the length or along multiple regions of the
conductor as where heating may be desired. (The ferromagnetic
coating 65 may be formed from a Nickel Iron (NiFe) alloy, such as
NIRON.TM. from Enthone, Inc. of West Haven, Conn., or other
ferromagnetic coatings, including Co, Fe, FeOFe.sub.2O.sub.3,
NiOFe.sub.2O.sub.3, CuOFe.sub.2O.sub.3, MgOFe.sub.2O.sub.3, MnBi,
Ni, MnSb, MnOFe.sub.2O.sub.3, Y.sub.3Fe.sub.5O.sub.12, CrO.sub.2,
MnAs, Gd, Dy, EuO, magnetite, yttrium iron garnet, aluminum,
PERMALLOY.TM., and zinc.)
[0118] The size of the conductor, size of the ferromagnetic
coating, associated thicknesses, shape, primary geometry,
composition, power supply and other attributes may be selected
based on the type of procedure and surgeon preferences. For
example, a brain surgeon may desire a small instrument in light
handheld package designed for quick application within the brain,
while an orthopedic surgeon may require a larger device with more
available power for operation on muscle.
[0119] The conductor may be formed from copper, tungsten, titanium,
stainless steel, platinum and other materials that may conduct
electricity. Considerations for the conductor may include, but are
not limited to mechanical strength, thermal expansion, thermal
conductivity, electrical conduction/resistivity, rigidity, and
flexibility. It may be desirable to form the conductor wire 66 from
more than one material. Connection of two dissimilar metals may
form a thermocouple. If the thermocouple were placed in the
vicinity or within of the ferromagnetic coating, the thermocouple
provides a temperature feedback mechanism for the device. Further,
some conductors may have a resistivity that correlates to
temperature, which may also be used to measure temperature.
[0120] The tuning of the power source 30 also reduces the amount of
high frequency energy radiating into the patient to near zero, as
voltage is low, and ideally zero, at the location of the
ferromagnetic coating 65. This is in contrast to monopolar devices,
which require a grounding pad to be applied to the patient, or
bipolar devices, both of which pass current through the tissue
itself. The disadvantages of these effects are well known in the
literature.
[0121] In many of these embodiments discussed herein, the
combination of cable length, frequency, capacitance and inductance
may also be used to adjust efficiency and tool geometry by tuning
the power source 30 to deliver maximum power to the ferromagnetic
coating 65, and therefore, maximum heat to the tissue. A tuned
system also provides for inherent safety benefits; if the conductor
were to be damaged, the system would become detuned, causing the
power delivery efficiency to drop, and may even shut down if
monitored by an appropriate safety circuit.
[0122] The amount of power delivered to the patient tissue may be
modified by several means to provide precise control of tissue
effects. The power source 30 may incorporate a modulator 120 for
power delivery as described above. Another embodiment uses
modification of the magnetic field by altering the geometry of the
conductor wire 66 and the ferromagnetic coating 65 through which it
passes, such as would be caused by a magnet. Placement of the
magnet nearby the ferromagnetic coating 65 would similarly alter
the induction effect and thereby change the thermal effect.
[0123] Different forms of modulation may be used to control
delivery of power. Pulse width modulation is based on the principle
that the ferromagnetic coating acts as a thermal integrator.
Amplitude modulation may control power delivery by altering a
continuous waveform so that only the desired power is delivered.
Frequency modulation may "detune the circuit" or change the
standing wave ratio causing losses to occur in transmission such
that the full power is not delivered to the load.
[0124] While modulation has been discussed as a method to control
power delivery, other methods may be used to control power
delivery. In one embodiment, the output power, and correspondingly
the temperature, of the tool is controlled by tuning or detuning
the drive circuit, including the conductor wire 66 and
ferromagnetic coated conductor 60.
[0125] A process of delivering power to a thermally adjustable tool
may include the steps of: selecting a surgical tool comprising a
conductor configured such that an oscillating electrical signal
will have approximately a standing wave with maximum current and
minimum voltage at a load, the load consisting of a ferromagnetic
material coated on the conductor; delivering the oscillating
electrical signal to the load; and causing the electrical signal to
no longer be sent to the load.
[0126] The process may optionally include the steps of: providing a
oscillating electrical signal between the frequencies of 5
megahertz and 24 gigahertz; or providing an oscillating electrical
signal selected from the group of center frequencies of 6.78 MHz,
13.56 MHz, 27.12 MHz, 40.68 MHz, 433.92 MHz, 915 MHz, 2.45 GHz,
5.80 GHz, 24.125 GHz, 61.25 GHz, 122.5 GHz, 245 GHz.
[0127] A method of incising tissue may include the steps of:
selecting a conductor having a ferromagnetic coating disposed on a
portion thereof; disposing the ferromagnetic coating into contact
with the tissue; and delivering an oscillating electrical signal to
the conductor so as to heat the ferromagnetic coating and cut the
tissue.
[0128] The method may optionally include the step of selecting a
power output of the oscillating electrical signal. The power output
may correspond to a temperature range at the ferromagnetic coating
or a desired tissue effect. The temperature range may be selected
for a corresponding tissue effect of cutting, hemostasis, vascular
endothelial welding, tissue vaporization, tissue ablation and
tissue carbonization.
[0129] An alternative method for incising tissue may include the
steps of: selecting a conductor having a ferromagnetic coating
disposed on a portion thereof, which is associated with a plug;
placing the plug into a receptacle configured for power delivery;
disposing the ferromagnetic coating into contact with the tissue;
and delivering an oscillating electrical signal to the conductor
through the plug so as to heat the ferromagnetic coating and incise
the tissue.
[0130] The method may optionally include the steps of: removing the
plug after use; communicating the characteristics of the conductor
and ferromagnetic coating; accessing a computer chip within the
plug; or communicating a resistor value corresponding to
characteristics in a lookup table.
[0131] A method for performing surgery may include the steps of:
selecting a load comprising a conductor with a ferromagnetic
coating; delivering power to the conductor through oscillating
electrical energy from a power source; and matching an impedance of
the load to an impedance of the generator.
[0132] The method may optionally include the steps of: changing the
output impedance of the power source to match the load; altering
the frequency of the oscillating electrical energy; adjusting the
power source to achieve a standing wave in the oscillating
electrical energy; maximizing current at the conductor; choosing
components to achieve a standing wave at the conductor; or
selecting a length of cable to connect the power source to the
electrical conductor to achieve a standing wave at the
conductor.
[0133] A method for treating tissue may include the steps of:
selecting a conductor having a ferromagnetic coating disposed on a
portion thereof; disposing the ferromagnetic coating into contact
with the tissue; delivering an oscillating electrical signal to the
conductor so as to heat the ferromagnetic coating and treat the
tissue; and adjusting a user control to alter the power
delivered.
[0134] A method for cutting may include the steps of: selecting a
conductor, a portion of the conductor having a ferromagnetic
coating disposed thereon; delivering an oscillating electrical
signal to the conductor to cause hysteresis in the ferromagnetic
coating and thereby heat the ferromagnetic coating; and applying
the heated coating to a substance to be cut to thereby cut the
substance.
[0135] Turning now to FIG. 4A, a thermal surgical tool system 10
with connectors which attach to opposing first and second ends of a
wire conductor is shown. The conductors as shown in FIG. 4A may be
formed by heat prevention terminals 280, such as crimp connectors
that provide thermal isolation. One or more heat sinks 282, and
wireless communication devices 286 may also be included. The wire
conductor 220 may be connected to the handheld surgical tool 50 by
terminals 280 and/or a heat sink 282 at opposing first and second
ends of the conductor. Portions of the conductor may extend into
the handle into terminals, while the ferromagnetic coating portion
of the conductor may extend beyond the handle. The terminals 280
may have a poor thermal conductance such that the terminals 280
reduce the heat transfer from the conductor into the handheld
surgical tool 50. In contrast, the heat sink 282 may draw any
residual heat from the terminals 280 and dissipate the heat into
other mediums, including the air. Connectors and connections may
also be achieved by wire bonding, spot and other welding, in
addition to crimping.
[0136] Preventing thermal spread may be desirable because the other
heated portions of the handheld surgical tool 50 may cause
undesired burns, even to the operator of the handheld surgical tool
50. In one embodiment, terminals 280 are used to conduct the
electric current, but prevent or reduce thermal conduction beyond
the ferromagnetic coated conductor.
[0137] The thermal surgical tool may also communicate wirelessly.
In one embodiment, the user interface for monitoring and adjusting
power levels may be housed in a remote, wirelessly coupled device
284. The wirelessly coupled device may communicate with a wireless
module 286 contained within the thermal surgical tool system 10,
including the handheld surgical tool 50, the control system (such
as footpedal 20), and/or the power subsystem 30. By housing the
control interface and display in a separate device, the cost of the
handheld surgical tool 50 portion may be decreased. Similarly, the
external device may be equipped with more processing power, storage
and, consequently, better control and data analysis algorithms.
[0138] Turning now to FIG. 4B, a thermal surgical tool system with
impedance matching network is shown. The impedance matching network
may match the output impedance of the signal source to the input
impedance of the load. This impedance matching may aid in
maximizing power and minimizing reflections from the load.
[0139] In one embodiment, the impedance matching network may be a
balun 281. This may aid in power transfer as the balun 281 may
match the impedance of the ferromagnetic coated conductor terminals
287 to the amplifier cable terminals 283 (shown here as a coaxial
cable connection). In such a configuration, some baluns may be able
to act as a heat sink and provide thermal isolation to prevent
thermal spread from the thermal energy at the ferromagnetic coating
65 transferred by the wire conductor 220 to terminals 287. The
appropriate matching circuitry may also be placed on a ceramic
substrate to further sink heat away or isolate heat away from the
rest of the system, depending on the composition of the
substrate.
[0140] It should be recognized that these elements discussed in
FIGS. 4A and 4B can be used in conjunction with any of the
embodiments shown herein.
[0141] Turning now to FIG. 5A, a longitudinal cross section of the
ferromagnetic coated conductor is shown. As an alternating current
67 is passed through conductor 66, a time varying magnetic field 68
is induced around conductor 66. The time varying magnetic field 68
is resisted by the ferromagnetic coating 65, causing the
ferromagnetic coating 65 to dissipate the inductive resistance to
the time varying magnetic field 68 as heat. Should the
ferromagnetic coating 65 reach it's Curie point, the magnetic
resistive properties of ferromagnetic coating 65 become
substantially reduced, resulting in substantially decreased
resistance to time varying magnetic field 68. As there is very
little mass to the ferromagnetic coating 65, the magnetic field
causes the ferromagnetic coating 65 to quickly heat. Similarly, the
ferromagnetic coating 65 is small in mass compared to conductor 66
and therefore heat will quickly dissipate therefrom due to thermal
transfer from the hot ferromagnetic coating 65 to the cooler and
larger conductor 66, as well as from the ferromagnetic coating 65
to the surrounding environment.
[0142] As is also evident from FIG. 5A, the ferromagnetic coating
may be between a first section (or proximal portion) and a second
section (or distal portion) of the conductor. This may provide the
advantage of limiting the active heating to a small area, instead
of the entire conductor. A power supply may also connect to the
first and second section to include the ferromagnetic coating
within a circuit providing power.
[0143] A method of using the surgical tool may include the steps
of: selecting a conductor and plating a ferromagnetic coating upon
the conductor.
[0144] Optional steps to the method may include: selecting a size
of a conductor having a ferromagnetic coating disposed on a portion
thereof according to a desired procedure; selecting a thermal mass
of a conductor having a ferromagnetic coating disposed on a portion
thereof according to a desired procedure; selecting a conductor
from the group of loop, solid loop, square, pointed, hook and
angled; configuring the oscillating electrical signal to heat the
coating to between 37 and 600 degrees Centigrade; configuring the
oscillating electrical signal to heat the coating to between 40 and
500 degrees Centigrade; causing the coating to heat to between
about 58-62 degrees Centigrade to cause vascular endothelial
welding; causing the coating to heat to between about 70-80 degrees
Centigrade to promote tissue hemostasis; causing the coating to
heat to between about 80-200 degrees Centigrade to promote tissue
searing and sealing; causing the coating to heat to between about
200-400 degrees Centigrade to create tissue incisions; or causing
the coating to heat to between about 400-500 degrees Centigrade to
cause tissue ablation and vaporization. Treatment may include
incising tissue, causing hemostasis, ablating tissue, or vascular
endothelial welding.
[0145] Turning now to FIG. 5B, an electrical equivalent
representation of a FIG. 5A's ferromagnetic coated conductor is
shown. The ferromagnetic coating is represented as a transformer 72
with a dynamic resistance 74. The inductance of the ferromagnetic
coated conductor varies based on the current passing through the
conductor. At a low operating frequency, the inductance of the
coating will have a small impact. At a high operating frequency,
inductance of the coating will have greater effect. Further,
different ferromagnetic coated conductor tip configurations will
have different impedance characteristics. Therefore, it is
necessary to provide a means to match the amplifier output to loads
having different impedances.
[0146] A variety of means are available to achieve desired
impedance matching. A continuously adjustable matching network may
change the matching impedance as the load changes, seeking to keep
it optimal for power transfer to the load. Thus, the generator may
always have optimal power transfer to the load through the network.
This may include adjusting capacitance, inductance or frequency of
the network.
[0147] An advantageous design of the instrument is to employ
minimal power levels from the amplifier necessary to achieve the
desired therapeutic heating range. Continuous monitoring of signal
characteristics, such as return current, standing wave ratio (SWR)
or reflected power, become practical electrical methods both to
maintain temporal heating and cooling properties and to achieve the
desired temperature within a fraction of a second.
[0148] In one embodiment, SWR is monitored. By monitoring and
retuning to optimize SWR, power transfer can be optimized for
various ferromagnetic coated conductor tips.
[0149] Instead of measuring load characteristics, the load may be
pre-characterized. Thus, the output impedance of the amplifier may
be caused to change based on predicted characteristics of the load
found in prior measurements. In one embodiment, the handle or
handpiece cable connector may have a receptacle which may match a
plug with a ferromagnetic coated conductor. The plug may contain
information identifying the predicted load characteristics of the
ferromagnetic coated conductor attached to the plug in a data
module. The data module may then communicate the characterization
to the generator or generator control. Thus the system may predict
and match the load characteristics by the information contained
within the plug. This information may further aid the system in
predicting output power to temperature correlations. Similar
matching can be achieved with a plug that contains an electrical
component, such as a resistor, that is correlated and used to
identify the configuration of the ferromagnetic coated conductor.
In this case, the generator circuit would read the value of the
resistor that identifies the ferromagnetic coated conductor and
automatically adjusts drive settings.
[0150] Instead of a generator having variable tuning, a driver
having fixed output impedance may be employed to drive
ferromagnetic coated conductor tips having input impedances that
are properly matched for optimal power transfer. Because this
matching network is static, it can be constructed in a variety of
ways. One particularly simple method is to use a designated, fixed
length of cable between the generator and the load, placing the
load at the optimal point where maximum power can be transferred.
This approach requires more design effort for the surgical tool but
ultimately creates a physically simpler generator--that is, fewer
parts and a less expensive system to build. Further, a balun may be
used for impedance matching as described above. These approaches
may effectively maintain a constant current through the
ferromagnetic coated conductor.
[0151] In applications where the thermal load is dynamic, due to
the changing thermal conductivity of the surgical environment, a
variety of means are available to achieve and maintain desired
tissue effects. A continuously adjustable amplifier may change the
power level as the thermal load changes, seeking to keep power
transfer to the load adequate to achieve and maintain desired
tissue effects. Through the previously described impedance matching
network, the generator may always have optimal power transfer to
the load through the network. If the changing thermal load changes
the impedance of the ferromagnetic coated conductor, the power
output of the ferromagnetic coating may be maintained by
continuously adjusting the network driving the ferromagnetic
material, as its load, in order to keep the material in an
optimized heating mode. This may include adjusting capacitance,
inductance or frequency of the network.
[0152] Methods similar to those described above for driving
ferromagnetic coated conductors representing loads of varying
impedance can be used to adapt to individual ferromagnetic coated
conductors which change their impedance in changing surgical
environments, including interaction with various tissues and
liquids. Continuous monitoring of signal characteristics, such as
return current, standing wave ratio (SWR) or reflected power,
become practical electrical methods both to maintain temporal
heating and cooling properties and to achieve the desired
temperature within a fraction of a second.
[0153] In one embodiment, SWR is monitored. By monitoring and
retuning to optimize SWR, power transfer can be optimized as the
surgical environment and heat transfer away from the ferromagnetic
coating changes. Rapid retuning, which may be practically
achievable at least at 10 Hz, allows dynamic responsiveness for
temperature as the surgical device is moved in and out of the wet
surgical environment and into the air.
[0154] It should be appreciated that while the figures show a solid
circular cross-section, the conductor cross-section may have
various geometries. For instance, the conductor may be a hollow
tubing such that it reduces thermal mass. Whether solid or hollow,
the conductor may also be shaped such that it has an oval,
triangular, square or rectangular cross-section.
[0155] Turning now to FIG. 6, a close-up, longitudinal
cross-sectional view of a single layer cutting tip with a thermal
insulator 310 is shown. A layer of thermal insulator 310 may be
placed between the ferromagnetic coating 65 and the conductor 66.
Putting a layer of thermal insulator 310 may aid in the quick
heating and cool-down (also known as thermal response time) of the
tool by reducing the thermal mass by limiting the heat transfer to
the conductor 66.
[0156] The thickness and composition of the thermal insulator may
be adjusted to change the power delivery and thermal response time
characteristics to a desired application. A thicker coating of
thermal insulator 310 may better insulate the conductor 66 from the
ferromagnetic coating 65, but may require an increased power
compared with a thinner coating of thermal insulator 310 in order
to induce a magnetic field sufficient to cause the ferromagnetic
coating to heat.
[0157] In the embodiments shown in FIGS. 7A-7G a plurality of
embodiments are shown in which the surgical tip 210 is a tool which
includes a wire conductor 220 which has a portion of its length
coated with a relatively thin layer of ferromagnetic coating 65. As
shown in FIGS. 7A-7G, the ferromagnetic coating 65 may be a
circumferential coating around a wire conductor 220. When the wire
conductor 220 is excited by a high frequency oscillator, the
ferromagnetic coating 65 will heat through induction according to
the power delivered, with an absolute limit provided by its Curie
temperature. Because of the small thickness of ferromagnetic
coating 65 and the tuned efficiency of high frequency electrical
conduction of the wire at the position of the ferromagnetic coating
65, the ferromagnetic coating 65 will heat very quickly (i.e. a
small fraction of a second) when the current is directed through
the wire conductor 220, and cool down quickly (i.e. a fraction of a
second) when the current is stopped.
[0158] Turning now to FIGS. 7A, 7B, 7C, 7D, 7E, 7F AND 7G,
ferromagnetic coated conductor surgical tips 210a, 210b, 210c,
210d, 210e, 210f and 210g are shown. In each of these embodiments,
a portion of wire conductor 220 is bent and coated with
ferromagnetic coating 65 such that the ferromagnetic coating 65 is
only exposed to tissue where the desired heating is to occur. FIGS.
7A and 7B are loop shapes that can be used for tissue cutting or
excision, depending upon the orientation of the tool to the tissue.
FIG. 7A shows a rounded geometry, while FIG. 7B shows a squared
geometry. FIG. 7C shows a pointed geometry for heated tip
applications that can be made very small because the process of
tissue dissection, ablation, and hemostasis requires only a small
contact point. FIG. 7D shows an asymmetric tool with a loop
geometry, where the ferromagnetic coating 65 is only disposed on
one side of the tool. FIG. 7E shows a hook geometry where the
ferromagnetic coating 65 is disposed on the concave portion of the
hook. FIG. 7F shows a hook geometry where the ferromagnetic coating
65 is disposed on the convex portion of the hook. FIG. 7G shows an
angled geometry, which may be used in similar situations as a
scalpel. Use of these various geometries of ferromagnetic coating
65 upon a wire conductor 220 may allow the surgical tip to act very
precisely when active and to be atraumatic when non-active.
[0159] In one representative embodiment, the electrical conductor
may have a diameter of 0.01 millimeter to 1 millimeter and
preferably 0.125 to 0.5 millimeters. The electrical conductor may
be tungsten, copper, other metals and conductive non-metals, or a
combination such as two dissimilar metals joined to also form a
thermocouple for temperature measurement. The electrical conductor
may also be a thin coating of conductor, such as copper, dispersed
around a non-metallic rod, fiber or tube, such as glass or
high-temperature plastic, and the conductive material, in-turn, may
be coated with a thin layer of ferromagnetic material. The magnetic
film forms a closed magnetic path around the electrically
conductive wire. The thin magnetic film may have a thickness about
0.01-50% and preferably about 0.1% to 20% of the cross-sectional
diameter of the wire. Due to the close proximity of the coating to
the wire, a small current can produce high magnetic fields in the
coating and result in significant temperatures. Since the magnetic
permeability of this film is high and it is tightly coupled to the
electrical conductor, low levels of current can result in
significant hysteresis losses.
[0160] It is therefore possible to operate at high frequencies with
low alternating current levels to achieve rapid inductive heating
up to the Curie point. The same minimal thermal mass allows rapid
decay of heat into tissue and/or the conductor with cessation of
current. The tool, having low thermal mass, provides a rapid means
for temperature regulation across a therapeutic range between about
37 degrees Celsius and 600 degrees Celsius, and preferably between
40 and 500 degrees Celsius.
[0161] While Curie point has been previously described as a
temperature cap, instead, here a material with a Curie point beyond
the anticipated therapeutic need may be selected and the
temperature can be regulated below the Curie point.
[0162] While some tip geometries are shown in FIGS. 7A through 7G,
it is anticipated that multiple different geometries of the
ferromagnetic coated conductor 60 may be used.
[0163] Turning now to FIG. 8, a cut-away view of a snare 350 in a
retracted position is shown. A ferromagnetic coating is placed on a
conductor to form a snare loop 355 and then placed within a sheath
360. While retracted, the snare loop 355 may rest within a sheath
360 (or some other applicator, including a tube, ring or other
geometry designed to reduce the width of the snare when retracted).
The sheath 360 compresses the snare loop 355 within its hollow
body. The sheath 360 may then be inserted into a cavity where the
target tissue may be present. Once the sheath 360 reaches the
desired location, the snare loop 355 may be extended outside the
sheath 360, and end up deployed similar to FIG. 9A. In one
embodiment, the conductor 365 may pushed or pulled to cause
extension and retraction of the snare loop 355.
[0164] Turning now to FIG. 9A a side view of a snare 350 in an
extended position is shown. Once extended, the snare 355 loop may
be used in several different ways. In one embodiment, the snare
loop 355 may be placed substantially around the target tissue, such
that the tissue is within the snare loop 355. The ferromagnetic
coating may then be caused to be inductively heated as discussed
above. The snare loop 355 is then retracted back into the sheath
360 such that the target tissue is separated and removed from
tissue adjacent the target tissue. The desired temperature range or
power level may be selected for hemostasis, increased tissue
separation effectiveness or other desired setting. For example, in
one embodiment, the snare 350 is configured for nasal cavity polyp
removal.
[0165] In another use, the snare 350 may be configured for tissue
destruction. Once within the desired cavity, the snare may be
extended such that a portion of the snare loop 355 touches the
target tissue. The snare loop 355 may then be inductively heated
such that a desired tissue effect occurs. For example, in one
embodiment, the sheath may be placed near or in the heart and the
snare loop 355 inductively heated to cause an interruption of
abnormal areas of conduction in the heart, such as in atrial
ablation.
[0166] Turning now to FIG. 9B, an alternate embodiment of a snare
351 is shown. The applicator may be a ring 361 instead of a sheath
as in FIG. 9A. Similar to the sheath, the ring 361 may be used to
force the loop into an elongated position. Various devices could be
used to hold the ring in place during use.
[0167] A method of separating tissue may include the steps of:
selecting a conductor having a ferromagnetic coating disposed on a
portion thereof; placing the portion of the conductor having the
ferromagnetic coating within a tube; inserting the tube into a
cavity; deploying the portion of the conductor having the
ferromagnetic coating within the cavity; and delivering an
oscillating electrical signal to the conductor so as to heat the
ferromagnetic coating while the heated ferromagnetic coating is in
contact with a target tissue.
[0168] Optional steps may include: deploying step further comprises
placing the ferromagnetic coating substantially around the target
tissue; retracting the ferromagnetic coating portion of the
conductor into the tube; causing hemostasis in the target tissue;
forming the conductor into a bent geometry such that a portion of
the conductor remains within the tube; and touching a ferromagnetic
covered portion of the bent geometry to the target tissue.
[0169] A method of removing tissue may include the steps of:
selecting a conductor having at least one portion having a
ferromagnetic conductor disposed thereon; and placing the
ferromagnetic conductor around at least a portion of the tissue and
pulling the ferromagnetic conductor into contact with the tissue so
that the ferromagnetic conductor cuts the tissue.
[0170] Optional steps may include: using a conductor having a
plurality of ferromagnetic conductors in an array or passing an
oscillating electrical signal through the conductor while the
ferromagnetic material is in contact with the tissue.
[0171] Turning now to FIG. 10A, a close-up view of a cutting tip
with a loop geometry and linear array of coatings is shown. While
the above embodiments have disclosed a continuous ferromagnetic
coating on a conductor, in another embodiment, there are more than
one coating separated by gaps on a single conductor. This is termed
a linear array of ferromagnetic elements (an example of a parallel
array of ferromagnetic elements can be seen in FIGS. 18A-18C).
[0172] In one embodiment, a loop geometry 270a may have multiple
ferromagnetic coatings 65, 65', and 65'' which are separated by
gaps on a wire conductor 220. In another embodiment shown in FIG.
10B, a close up view of a cutting tip with an alternate hook
geometry 270b and linear array of ferromagnetic coatings 65 and 65'
is shown on a wire conductor 220. The linear array may include the
advantage of allowing flexibility in building a desired thermal
geometry.
[0173] The conductor 220 which may be formed of an alloy having
shape memory, such as Nitinol (nickel titanium alloy). A Nitinol or
other shape memory alloy conductor can be bent into one shape at
one temperature, and then return to its original shape when heated
above is transformation temperature. Thus, a physician could deform
it for a particular use at a lower temperature and then use the
ferromagnetic coating to heat the conductor to return it to its
original configuration. For example, a shape memory alloy conductor
could be used to form snare which changes shape when heated.
Likewise, a serpentine shape conductor can be made of Nitinol or
other shape memory alloy to have one shape during use at a given
temperature and a second shape at a higher temperature. Another
example would be for a conductor which would change shape when
heated to expel itself from a catheter or endoscope, and then
enable retraction when cooled.
[0174] In another embodiment, the ferromagnetic coatings may be
formed in such a way that an individual coating among the linear
array may receive more power by tuning the oscillating electrical
energy. The tuning may be accomplished by adjusting the frequency
and/or load matching performed by the power source to specific
ferromagnetic coatings.
[0175] Frequency response of individual coatings may be affected by
altering the physical characteristics of the individual coatings.
These physical characteristics may include composition, thickness,
length and proximity to other coatings. By altering the physical
characteristics of each coating, the individual coatings may
consume more power at an optimum frequency for that coating. Other
coatings may dissipate less or no power at the same frequency. Thus
it may be possible to address individual elements according to the
frequency output by the generator.
[0176] Turning now to FIG. 11, a cut-away view of a snare tool 370
with a linear array of coatings in a retracted position is shown.
In some embodiments, some ferromagnetic coatings may lack the
elasticity to effectively bend into a retracted position.
Therefore, individual coating segments 375 may be separated by gaps
380 such that the conductor 365 may be flexed while the coating
segments 375 may remain rigid.
[0177] Similarly, the snare tool 370 may be extended, as seen in
FIG. 12. The gaps 380 between the coating segments 375 may be
adjusted such that the heating effect will be similar in the gaps
380 as the coating segments. Thus, the snare tool 370 with linear
array may act similar to the snare with flexible coating in FIGS. 8
and 9.
[0178] Turning now to FIG. 13, a cross-sectional view of a single
layer cutting tip in the ferromagnetic-coated region is shown. The
ferromagnetic coating 65 is disposed over a wire conductor 220. The
ferromagnetic coating 65 provides several advantages. First, the
ferromagnetic coating 65 is less fragile when subjected to thermal
stress than ferrite beads, which have a tendency to crack when
heated and then immersed in liquid. The ferromagnetic coated
conductor 60 has been observed to survive repeated liquid immersion
without damage. Further, the ferromagnetic coating 65 has a quick
heating and quick cooling quality. This is likely because of the
small amount of ferromagnetic coating 65 that is acted upon by the
magnetic field, such that the power is concentrated over a small
area. The quick cooling is likely because of the small amount of
thermal mass that is active during the heating. Also, the
composition of the ferromagnetic coating 65 may be altered to
achieve a different Curie temperature, which would provide a
maximum self-limiting thermal ceiling attribute to the device.
[0179] Turning now to FIGS. 14A, 14B and 15, a multilayer surgical
tool tip is shown. A cross section of 14A along the 221 line may
result in FIG. 14B which shows alternating layers of wire conductor
220 and 220' and ferromagnetic coating 65 and 65'. Heating capacity
may be increased by layering thin layers of alternating conductor
220 and 220' material and ferromagnetic coating 65 and 65', while
still maintaining quick heating and cooling advantages. FIG. 15
shows an axial cross-sectional view from FIG. 14A along the 390
line. The alternating layers of conductor 220 and 220', and
ferromagnetic coating 65 and 65' may also be seen.
[0180] Turning now to FIG. 16, a flattened side cylindrical
geometry is shown. The flat surface 180 can be manufactured to
cause a thin plating 182 of ferromagnetic coating on the conductor
66 relative to the thicker plating around the rest of the conductor
66. This thin plating 182 may result in selective first onset
heating in this flat surface 180. Inductive heating may be
proportional to flux density within the magnetically permeable
coating. In one embodiment, an asymmetrically thinned coating has a
small cross sectional thickness and will generate higher hysteresis
losses in the form of heat. Thus, a therapeutic temperature may be
achieved with yet lower power at the flat surface 180 with higher
flux density 192 compared to a cooler opposite side with a
diminished flux density 190. An advantage is that fast temporal
response and distributed optimal heating at the tissue interface
may be enhanced.
[0181] Turning now to FIG. 17, the ferromagnetic coating 65 may
also be configured to focus the temperature increase on the outside
of the ferromagnetic coating 65, further reducing the time needed
to cool the ferromagnetic coating 65 in a relatively high power
application. An example of such a configuration is shown in FIG.
17, wherein the fields generated by the current flow 230 and 230'
(the arrows) may have a cancelling effect with respect to each
other within the ferromagnetic coating 65, keeping the
ferromagnetic material between the looped conductor 441 cooler than
the ferromagnetic material at the perimeter.
[0182] Turning now to FIGS. 18A-18D, several surgical tip 194
geometries are demonstrated. In FIG. 18A, a surgical tip 194a with
a single small diameter electrically conductive wire plated with
the thin film magnetic material 196 is shown. In FIG. 18B, the
surgical tip 194b with two small diameter electrically conductive
wires plated with the thin film magnetic material 196' is shown. In
FIG. 18C, a surgical tip 194c with three small diameter
electrically conductive wires plated with the thin film magnetic
material 196'' are shown. It is thus contemplated that a tip
geometry may consist of a plurality of small diameter electrically
conductive wires plated with the thin film magnetic material. Such
a design maintains the temporal heat responsiveness (rapid onset,
rapid offset) essential to the dynamic surgical environment due to
minimal mass of the ferromagnetic coated conductor. It is thus
possible to configure a flat tine with two or more spaced wires as
a practical monothermal or multithermal tool. Further, the tips
194a, 194b and 194c may also be exchangeable as seen in FIG. 18D,
which has a receptacle 198 for the tips 194 in FIGS. 18A-18C. It
will be appreciated that the generator system may be configured to
adjust the power jointly delivered to two or more of the conductors
and that a user control (as shown in other figures) can be provided
for that purpose.
[0183] The ferromagnetic coating 65 can be used to contact the
tissue directly, or, a non-stick coating, such as TEFLON (PTFE), or
similar material, could be applied over the ferromagnetic coating
and conductor to prevent sticking to the tissue. Alternatively, the
ferromagnetic coating could be coated with another material, such
as gold, to improve biocompatibility, and/or polished, to reduce
drag force when drawing through tissue. The ferromagnetic coating
could also be coated by a thermally-conductive material to improve
heat transfer. In fact, a single coating may be selected to have
multiple desirable properties.
[0184] Turning now to FIGS. 19 to 22, the ferromagnetic coated
conductor may be attached to a primary geometry. The primary
geometry may provide an attachment surface or an internal site for
the conductor with a ferromagnetic coating. Thus the advantages of
the ferromagnetic coating on a conductor may be combined with the
advantages of the primary geometry and its corresponding material.
The primary geometry may be selected for various reasons, including
but not limited to, material strength, rigidity, heat conduction,
resistance to thermal heat transfer, surface area, or additional
functionality.
[0185] As used herein, a primary geometry means a structure to
which a ferromagnetic coated conductor may be attached and which
defines the shape of the tool. For example, a primary geometry
could be a scalpel, tines of forceps, the face of a spatula, or a
ball shape at the end of a probe. The conductor geometry,
therefore, may be disposed upon the primary geometry, may extend
through a hole in the primary geometry, and/or be embedded in the
primary geometry. For example, a primary geometry may be a scalpel,
while the conductor geometry may be the serpentine shape of a
ferromagnetic coated wire upon the primary geometry.
[0186] Turning now to FIGS. 19A and 19B, a cold cutting scalpel 223
with alternate inductive ferromagnetic thermal function is shown.
The cold cutting scalpel 223 may be used for cutting through the
application of a blade having a cutting edge and having a secondary
thermal function activated when required, such as for coagulation.
In the embodiments shown in FIGS. 19A and 19B, this is achieved by
placing a ferromagnetic coated wire conductor 220 upon the side of
a scalpel shaped primary geometry, which can cut or incise tissue
without activation of the conductor or ferromagnetic coating 65.
The cold cutting scalpel 223 may be used classically to make
incisions in tissue. However, if the patient begins to bleed, the
cold cutting scalpel 223 operator may activate the ferromagnetic
coated conductor and place the side of the cold cutting scalpel 223
(and correspondingly, the ferromagnetic coated conductor) upon the
bleeding tissue. The thermal effect may then cause the tissue to
seal and cease bleeding. After deactivation of the ferromagnetic
coated conductor, the scalpel operator may then return to making
incisions with the benefits of a cold cutting scalpel.
[0187] There are several advantages to use of such a cold cutting
scalpel 223. The dual-use tool does not require the cold cutting
scalpel 223 operator to remove one tool and replace it with
another, causing risk of further damage and delay. Due to the
ferromagnetic coating 65, the cold cutting scalpel 223 may also
have a quick thermal response time (the heat-up and cool-down time)
in the region of the ferromagnetic coating 65 such that the cold
cutting scalpel 223 may be used on the targeted area and reduce
waiting time. In cases where it may be desirable to heat the entire
cold cutting scalpel, thermal response time may be further reduced
by removing a center portion 222 of the blade, (as seen in FIG.
19B), resulting in a non-contiguous portion of the blade that may
occur between or adjacent to the conductor path. Removing the
center portion 222 of the blade may further reduce the thermal mass
and correspondingly the thermal response time.
[0188] In one embodiment, related to FIG. 19B, the ferromagnetic
coating may be limited to a part of the scalpel, such as the tip of
the cold cutting scalpel 223. This limiting would cause only the
tip to heat, while the remaining portions of the primary geometry
would remain at a lower temperature. This limiting of the heating
to a portion of the primary geometry in proximity to the
ferromagnetic coating may provide a higher degree of accuracy and
usefulness in smaller spaces. Similarly, the ferromagnetic coated
wire conductor 220 may form a pattern, such as a zigzag or
serpentine pattern, across the surface of the cold cutting scalpel
223 to increase the heating coverage of the surface.
[0189] Scalpel effects may also be enhanced by the thermal effects
of the ferromagnetic coated wire conductor 220. In one embodiment,
the scalpel may have multiple parts with different temperature
ranges addressable to each part. For example, energy to the scalpel
blade may be used to cut, while energy to the sides of the blade
may be used to coagulate tissue walls. In another embodiment, the
ferromagnetic coated wire conductor 220 may be activated to provide
additional cutting ability when moving through more difficult
tissue. In another embodiment, the ferromagnetic coated conductor
may be activated to provide a more smooth cutting process in
conjunction with the scalpel blade. A user control may be used to
select a power setting to be delivered by a power source, which may
be correlated with a desired temperature or tissue effect.
[0190] The power supply may address individual coatings and their
associated conductors in a number of different ways. In one
embodiment, the conductors have individual power lines, but share a
common ground. In another embodiment, the conductors have
individual power and ground lines. Another embodiment uses
frequency modulation to address individual coatings. One digital
embodiment uses three conductors. One conductor is used for
communication about which coating should receive power, while the
other two are the power and ground signals. An alternative digital
circuit removes the communication circuit and instead sends a
precursor identification signal on the power line such that the
circuit can identify and direct the power to the correct circuit.
In fact, these technologies are not mutually exclusive, but may be
combined and used together. For example, the combination of
circuits may be advantageous where some circuits require less power
than other circuits.
[0191] Turning now to FIG. 20A, a thermal surgical tool with a
spatula shaped geometry is shown. The spatula 224 may have a
ferromagnetic coating 65 on a wire conductor 220 that follows the
perimeter of the spatula shape as shown. In an alternate
embodiment, the ferromagnetic coated portion of the wire conductor
220 may form a pattern across the surface of the geometry such that
the surface is more evenly covered by the ferromagnetic coated
portion of the wire conductor 220.
[0192] A spatula geometry may be useful for various tissue effects
and procedures. In one embodiment, the spatula is used for
hemostasis or tissue welding during surgery. After an incision has
been made, if needed, the spatula may be applied to the incised
tissue to achieve hemostasis or even tissue welding. In another
embodiment, the spatula pressed into tissue and thermal energy is
used for tissue ablation.
[0193] Turning now to FIG. 20B, the thermal surgical tool with a
spatula shaped geometry is shown in forceps form. The spatula
forceps 225 may be used in combination such that each spatula has a
separate power control or the forceps may have a power control in
common. In other embodiments, the forceps may also only be heated
on one spatula of the forceps. Such a tool can be used to clamp
vessels to stop blood flow, and then cause hemostasis and cutting
of the vessels with heat.
[0194] Turning now to FIGS. 20C and 20D, a side view of FIG. 20A is
shown in two different embodiments. The ferromagnetic coating and
wire conductor may be attached to the primary geometry in several
ways. In one embodiment shown in 20C, the ferromagnetic coating 65
and conductor may be attached to the surface of the primary
geometry. Alternatively in 20D, the ferromagnetic coating 65 and
conductor may be embedded within the primary geometry. Depending
upon the desired effect, the tools depicted in FIGS. 20A, 20B, 20C
and 20D can be applied to tissue in such a manner that the side of
the tool on which the ferromagnetic coated conductor 65 is located
can contact the tissue, or the opposite side can be applied to the
tissue.
[0195] Turning now to FIGS. 21A, 21B and 21C, a thermal surgical
tool with a ball shaped geometry is shown. In one embodiment, a
horizontally wrapped ball 226 or a vertically wrapped ball 231 may
be internally or externally wrapped with a wire conductor 220 with
a ferromagnetic coating 65 as seen in FIG. 21A and FIG. 21C. In
another embodiment, shown in FIG. 21B, a ball geometry 227 may
contain a wire conductor 220 with a ferromagnetic coating prepared
in another shape, such as a horseshoe shape. In the embodiments, a
ball-shaped heating element may be formed which can be used to
coagulate or provide a therapeutic effect over a large surface area
of tissue. The ball may also be effective in tissue ablation, as it
may radiate thermal energy in most, if not all, directions.
[0196] Turning now to FIG. 22A, a thermal surgical tool with a
pointed geometry is shown. The pointed tool 228 may have a
ferromagnetic coating 65 on a wire conductor 220 that follows the
perimeter of the pointed tool shape as shown. In an alternate
embodiment, the ferromagnetic coated portion of the wire conductor
220 may form a pattern across the point surface of the geometry
such that the point surface is more evenly covered by the
ferromagnetic coated portion of the wire conductor 220. The pointed
tool 228 may be particularly useful for making incisions that
penetrate layers of tissue, providing a means for coagulation while
cutting, such as coagulation of tissue around the site of trocar
insertion for laparoscopic surgery.
[0197] Turning now to FIG. 22B, the thermal surgical tool with a
pointed geometry is shown in forceps form. The pointed forceps 229
may be used in combination such that each pointed geometry has a
separate power control or the forceps may have a power control in
common. Such a tool can be configured for achieving hemostasis and
cutting in small vessel ligation.
[0198] While some primary geometries have been shown in singular
form, the primary geometries may be used in combination. This may
include two or more of the same primary geometry or differing
primary geometries, including forceps applications. Each primary
geometry may be commonly controlled for power or have separate
power controls for each primary geometry. Furthermore, solid
primary geometries may be altered similar to the scalpel primary
geometry shown above such that portions of the primary geometries
may be removed to reduce thermal mass and correspondingly, thermal
response time.
[0199] While some of the primary geometries have been shown to have
symmetrical construction, the primary geometries may have
asymmetrical or directional construction such that only a portion
of the primary geometry would be active. This may be accomplished
by placing the ferromagnetic coating only on the portion of
conductor wire residing on the area of the primary geometry desired
to be active. For example, the spatula geometry may be configured
to be active in one area if the ferromagnetic coated conductor is
not symmetrically positioned on the spatula structure. This
activation of only a part of the primary geometry may be further
enhanced by providing a pattern, such as a zigzag or serpentine
pattern, on the desired active portion of the geometry, such as a
surface.
[0200] In another embodiment, a portion of the primary geometry may
be activated. By using multiple conductors with a ferromagnetic
coating 65 attached to different portions of a primary geometry, a
portion of the primary geometry may be selectively activated. For
example, a scalpel geometry 232 may be divided into a tip portion
234 and a face portion 236 as shown in FIG. 22C. A scalpel operator
may then choose whether to activate only the tip or the tip in
conjunction with the face of the scalpel geometry, depending on the
surface area desired. Similarly, in a forceps application, the
forceps may be divided into inside and outside portions. If the
forceps operator desires to remove something that may be surrounded
by the forceps, such as a polyp, the internal portions may be
activated while the external portions remain deactivated. If
opposing sides of a void need to be sealed, the outside surfaces of
the forceps may be activated.
[0201] By using multiple conductors with a ferromagnetic coating 65
attached to different portions of a primary geometry and separately
controlled power sources, different portions of the primary
geometry may be activated at the same time for different uses or
effects. For example, an edge portion of a primary geometry may be
activated for cutting while the blade portion may be activated for
hemostasis.
[0202] A method of treating tissue may thus include the steps of:
selecting a primary geometry having a conductor disposed thereon,
the conductor having a ferromagnetic coating disposed on a portion
thereof; disposing the ferromagnetic coating into contact with the
tissue; and delivering an oscillating electrical signal to the
conductor so as to heat the ferromagnetic coating and treat the
tissue.
[0203] Optional steps of the method may include choosing a primary
geometry selected from the group of scalpel, spatula, ball and
pointed geometry. Treating of the tissue may include incising,
causing hemostasis, ablating or vascular endothelial welding.
[0204] A method for tissue destruction may include the steps of
selecting a conductor having a ferromagnetic coating disposed on a
portion thereof; and delivering an oscillating electrical signal to
the conductor so as to heat the ferromagnetic coating and destroy
tissue.
[0205] Optional steps of the method may include monitoring the
tissue and ceasing delivery of the oscillating electrical signal to
the conductor when the desired tissue destruction has occurred or
undesired tissue effects are to be prevented.
[0206] A method for forming a surgical instrument may include the
steps of: selecting a primary geometry; coating a conductor with
ferromagnetic material; and disposing the conductor on the primary
geometry.
[0207] Optional steps of the method may include providing
electrical connections on the conductor configured for receiving
oscillating electrical energy.
[0208] Turning now to FIG. 23A, a catheter 270 having a conductor
220 which is at least partially coated with ferromagnetic material
disposed around the tip of the catheter is shown. Depending upon
the therapeutic effect desired, the location of the coil of
ferromagnetic coating 65 could instead be inside the catheter tip,
or a single loop of ferromagnetic coated conductor having a
circumference which approximates that of the catheter central
channel 260 could be located at the end of the catheter tip.
[0209] In FIG. 23B, another ferromagnetic coated catheter 270 is
shown. While in some embodiments the conductor may be a wire, coil,
or annular structure, a ferromagnetic coated catheter 270 could
also be formed which would serve as an alternate conductor 250 with
a ferromagnetic coating 65. In this embodiment, the catheter could
consist of two coaxial conductors, separated by an insulator. At
the distal tip of the catheter 270, a conductive coating can be
applied such that a continuous electrical path is created by the
coaxial conductors. The ferromagnetic coating can be dispersed
about the external diameter surface near the distal tip of the
catheter, as shown in FIG. 23B, or, upon the end of the catheter,
on the annular surface connecting the coaxial conductors. This
would allow the ferromagnetic coated catheter 270 to perform other
functions, such as irrigation, aspiration, sensing, or, to allow
viewing access via optical fibers, through a central channel 260,
as is common in many interventional as well as open and minimally
invasive surgical procedures. Furthermore, the central lumen of the
catheter could be used to provide access to other sensing
modalities, including, but not limited to, impedance and pH.
[0210] Turning now to FIG. 24, a side view of an alternate
embodiment of a ferromagnetic coated conductor surgical tool
catheter tip 288 is shown. In one embodiment, the conductor may
consist of a ferromagnetic coated conductor positioned on a
substrate 285 forming a body with a central channel. The
ferromagnetic coating may consist of a plated ferromagnetic coating
275 on top of a conductor 289. The plating may be placed on the
outside of the substrate 285 such that the thermal effects are
directed externally. This may allow the catheter tip to apply
thermal tissue effects to tissue walls.
[0211] In another embodiment, the inside of the substrate may
contain the conductor 289 and ferromagnetic coating 275 such that
the thermal effects are directed internally. An internal coating
may allow delivery of a meltable solid to a desired area, such as
in fallopian tube sealing and osteosynthesis applications.
[0212] Alternatively, the ferromagnetic coating 275 may surround
the entrance to the central channel 260, such that the thermal
effects may be directed in front of the tip. Having the thermal
energy be directed in front of the central channel 260 entrance may
aid in taking a tissue sample or removal of material, such as a
polyp.
[0213] The plating may be accomplished through multiple methods.
The substrate 285 may be extruded, molded or formed from various
materials including high temperature thermoplastic, glass, or other
suitable substrate material. The actual plating may be accomplished
through electroplating, electroless plating, vapor deposition, or
etching, or some combination thereof. Thus through the plating
process, a catheter tip 288 may be formed with a ferromagnetic
coating 275 on a conductor 280 with a continuous path.
[0214] The catheter may also have multiple channels. One channel
may be a deployment channel for the ferromagnetic coated conductor.
Another channel may be used for one or more sensors or sources, or
even each sensor or source in its own channel--such as a
temperature sensor, illumination source and endoscope. Other
channels may include delivery, irrigation or aspiration of
substances, including those associated with treatment, such as in
osteosynthesis or fallopian tube sealing. In fact, the
ferromagnetic coating may aid in the melting of such substances and
the coating may be directed at one or more specific channels rather
than the catheter at large.
[0215] Turning now to FIG. 25, an endoscope 240 with a viewing
channel 262 of rod lens type or organized fiber bundle type aside a
light emitting source 266 is shown. A loop coagulator/cutter 264 is
shown which consists of the ferromagnetic coated conductor 65. Such
an adaptation is contemplated in snare applications such as colon
polypectomy or sealing and cutting applications in various
laparoscopic procedures. Other sensing modalities include near
field tumor cell detection or infrared heat monitoring. Tool
configurations similar to the described endoscope 240 can be
embodied in tools that can be delivered to target tissue through
the lumen of a catheter.
[0216] In one embodiment, tumor cells are caused to be tagged with
materials that fluoresce when exposed to ultra-violet light. The
endoscope 240 may contain a light source, 266, and sensor or optics
within the channel 262 that return the detected florescence. The
ferromagnetic coating 65 portion of the endoscope 240 may then be
directed at the tagged tissue for destruction.
[0217] In another embodiment, materials are deposited around target
tissue or bone in a solidified condition. Once delivered, the
materials are melted to conformation at the site by activation by
the endoscope 240 described above. Examples of use of this
embodiment include fallopian tube sealing and osteosynthesis.
Furthermore, such materials could be removed by melting with the
same or similar endoscope 240, and aspirated through a central
lumen of the endoscope 240. In yet further applications, materials
may be delivered in liquid form, and cured by a thermal heating
process induced by the endoscope 240.
[0218] Alternatively, the conductor may be part of a bundle of
fibers. The fibers may be contained within a catheter or otherwise
bundled together. The conductor may have a ferromagnetic coating,
while the other fibers may have other purposes that include visual
observation, sensing, aspiration, or irrigation.
[0219] A method of tissue ablation may include the steps of:
selecting a catheter with a ferromagnetic covered conductor;
causing the ferromagnetic covered conductor to touch tissue to be
ablated; and delivering power to the ferromagnetic covered
conductor.
[0220] Optional steps may include: directing the catheter to the
tissue through the aid of an endoscope; selecting a ferromagnetic
coated conductor disposed on the catheter; selecting a
ferromagnetic coated conductor contained within the catheter;
causing the ferromagnetic coated conductor to be deployed from the
catheter; or touching the ferromagnetic coated conductor to the
tissue to be ablated.
[0221] A method of delivering a substance into a body may include
the steps of: selecting a catheter with a ferromagnetic coated
conductor; placing a substance in the catheter; inserting the
catheter into a body; and causing power to be sent to the
ferromagnetic coated conductor.
[0222] Optional steps may include: selecting a substance for
osteosynthesis; selecting a substance for fallopian tube sealing;
or melting the substance in the catheter.
[0223] A method of treating tissue may include the steps of:
selecting a catheter with a ferromagnetic coated conductor; placing
the catheter in contact with tissue; and selecting a power setting.
The temperature range may correspond to a temperature range or
desired tissue effect. The desired tissue effect may be selected
from the group of vascular endothelial welding, hemostasis,
searing, sealing, incision, ablation, or vaporization. In fact, the
power setting may correspond to a desired tissue effect.
[0224] Turning now to FIG. 26, a tissue ablation tool 290 is shown.
In typical applications of tissue ablation, an arm or tine 295 is
inserted into undesired tissue. One or more tips 300 may be
activated such that the tissue temperature is raised to a desired
level for a desired amount of time. After the activation has
succeed in holding a temperature for a desired amount of time, or
undesired effects are noticed, the one or more tips 300 may be
deactivated and removed from the tissue.
[0225] In one embodiment, a conductor 220 may be contained in one
or more arms or tines 295 with tips 300 that may contain
ferromagnetic coatings 65. The tips 300 may be inserted into tissue
and temperature controlled until tissue destruction occurs or one
or more undesired tissue effects occur. The tissue effects may be
monitored through sensors in the tines 295 or externally.
[0226] Sensors may be placed in multiple ways. In one embodiment,
the sensor is placed in the tine and away from a ferromagnetic
coated tip 300. In another embodiment, one tip 300 may have a
ferromagnetic coating, while an alternate tip 300 may have no
coating, but a sensor contained within. The sensor may monitor
tissue effects or some other indicator indicative of the
temperature of the ferromagnetic coated tip, properties of the
associated tissue, or some desired characteristic and may include
various sensors, cameras and remote imaging. In another embodiment,
the temperature may be monitored through external imaging.
[0227] The sensor may thus form part of a feedback loop. By
monitoring one or more tissue effects, the ablation tool may
self-adjust power settings. This self-adjustment may allow the
system to operate below the Curie point and still maintain a
desired tissue effect and/or temperature range.
[0228] In the case where more than one tip 300 is used, the tips
300 with a ferromagnetic coating 65 may be individually controlled
such that the thermal profile is concentrated in the desired area.
This may also allow a second tine to monitor tissue effects, while
a primary tine is used to perform the thermal function.
[0229] The power supply may individually address each tine. In one
embodiment, the power supply monitors each tine for temperature. As
tissue is destroyed, the water content of the tissue may decrease.
As water content decreases, the tissue may not require the same
amount of thermal energy. Thus, as tissue is destroyed, the power
supply may monitor temperature and send less power or no power to
tips 300 that show evidence of temperature spikes or changes.
[0230] While a diagram has been shown of a multi-tip tissue
ablation tool in FIG. 26, a single tissue ablation tool may be made
in a configuration similar to FIG. 7C.
[0231] Turning now to FIG. 27, a temperature spectrum is disclosed.
Tissue may react differently at different temperatures with a
tissue treatment element (such as a ferromagnetic coated conductor)
and thus temperature ranges will result in different treatments for
tissue. Specific tissue treatments are somewhat variable due to
inconsistencies including tissue type and patient differences. The
following temperatures have been found to be useful. Vascular
endothelial welding may be optimal at 58-62 degrees Centigrade.
Tissue hemostasis without sticking may be achieved at 70-80 degrees
Centigrade. At higher temperatures, tissue searing and sealing may
occur more quickly, but coagulum may build-up on the instrument.
Tissue incision may be achieved at 200 degrees Centigrade with some
drag due to tissue adhesion at the edges. Tissue ablation and
vaporization may occur rapidly in the 400-500 degree Centigrade
range. Thus, by controlling the temperature the "treatment" of
tissue which the device delivers can be controlled, be it vascular
endothelial welding, tissue incision, hemostasis, tissue
carbonization, tissue vaporization or tissue ablation. According to
the spectrum disclosed above, power delivery settings corresponding
to the desired temperature range may be included in the power
delivery switch. In one embodiment, the foot pedal may have several
stops that indicate to the surgeon the likely tip temperature range
of the current setting.
[0232] Besides the advantages of uses in tissue, the surgical tool
may also be self-cleaning. In one embodiment, when activated in
air, the tool may achieve a temperature sufficient to carbonize or
vaporize tissue debris.
[0233] It will be appreciated that the thermal surgical tool system
in accordance with the present invention will have a wide variety
of uses. Not only can it be used on humans, it can also be use to
cut tissue of other animals, such as in the context of a
veterinarian or simply cutting tissues or biomaterials, such as
those used for implantation, into smaller pieces for other
uses.
[0234] Certain embodiments of the surgical system may have broad
application within surgery as well. A loop geometry may have
advantages in cutting, coagulation and biopsy applications. A blade
geometry may have advantages for cutting and hemostasis
applications. The point geometry may have advantages in dissection
and coagulation applications, and in particular, neurodissection
and coagulation. However, the application of a geometry may be
further configured and tailored to an application by diameter,
length, material characteristics and other characteristics
discussed above.
[0235] While the present invention has been described principally
in the area of surgical tools and the treatment of live tissue
(though it can be used on dead tissue as well), it will be
understood that a tool made in accordance with the present
invention and the methods discussed herein may have other uses. For
example, a cutting tool could be formed for butchering meat.
Whether the meat is fresh or frozen, the tool can be useful. For
example, a cutting blade which is heated to a high temperature will
cut through frozen meat. However, when power is no longer supplied,
the "cutting" edge is safe to the touch. Likewise, cutting meat
with a hemostasis setting would slightly sear the exterior of the
meat, locking in juices. Other uses of the instruments discussed
herein will be understood by those skill in the art in light of the
present description.
[0236] There is thus disclosed an improved thermally adjustable
surgical tool. It will be appreciated that numerous changes may be
made to the present invention without departing from the scope of
the claims.
* * * * *