U.S. patent application number 17/400873 was filed with the patent office on 2021-12-02 for delivery system for intracorporeal smooth muscle stimulation.
This patent application is currently assigned to Allotrope Medical, Inc.. The applicant listed for this patent is Allotrope Medical, Inc.. Invention is credited to Jeffrey Paul Castleberry, Albert Yung-Hsiang Huang, Nishant Verma.
Application Number | 20210370062 17/400873 |
Document ID | / |
Family ID | 1000005769995 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210370062 |
Kind Code |
A1 |
Castleberry; Jeffrey Paul ;
et al. |
December 2, 2021 |
DELIVERY SYSTEM FOR INTRACORPOREAL SMOOTH MUSCLE STIMULATION
Abstract
An electrical stimulation system includes a stimulator having at
least one electrode and a power supply. The electrode is
connectable to the power supply, and the power supply delivers
electrical stimulation energy in the form of a capacitive discharge
voltage through the stimulator and electrode to tissue proximate a
target anatomy to induce an observable response in the target
anatomy during a medical procedure.
Inventors: |
Castleberry; Jeffrey Paul;
(Longmont, CO) ; Verma; Nishant; (Houston, TX)
; Huang; Albert Yung-Hsiang; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Allotrope Medical, Inc. |
Houston |
TX |
US |
|
|
Assignee: |
Allotrope Medical, Inc.
Houston
TX
|
Family ID: |
1000005769995 |
Appl. No.: |
17/400873 |
Filed: |
August 12, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16420809 |
May 23, 2019 |
11129990 |
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17400873 |
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PCT/US17/63428 |
Nov 28, 2017 |
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16420809 |
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62511301 |
May 25, 2017 |
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62489389 |
Apr 24, 2017 |
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62426974 |
Nov 28, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/36042 20130101;
A61N 1/36135 20130101; A61N 1/3606 20130101; A61N 1/05 20130101;
A61N 1/3615 20130101; A61N 1/36132 20130101; A61N 1/40 20130101;
A61B 2505/05 20130101; A61N 1/36017 20130101; A61B 5/4041 20130101;
A61N 1/36007 20130101; A61N 1/36034 20170801 |
International
Class: |
A61N 1/36 20060101
A61N001/36; A61N 1/40 20060101 A61N001/40; A61N 1/05 20060101
A61N001/05 |
Claims
1. An electrical power supply for inducing an observable response
in a target anatomy for use with a stimulator having at least one
electrode configured to treat the target anatomy, said electrical
power supply comprising: circuitry connectable to said at least one
electrode and configured to deliver electrical stimulation energy
through said stimulator to tissue proximate the target anatomy,
wherein the stimulation energy comprises a plurality of stimulatory
electrical pulses, each pulse consisting of an undriven capacitive
discharge comprising an initial charge which discharges with an
exponential waveform having a time constant equal to the product of
an uncontrolled tissue resistance and a capacitance of a capacitor
in a closed circuit with the tissue proximate the target
anatomy.
2. An electrical power supply according to claim 1 wherein the
circuitry is configured to elicit a peristaltic response from a
ureter when said at least one electrode is positioned so as to
deliver said stimulation energy to tissue proximate the ureter.
3. An electrical power supply according to claim 1 wherein the
undriven capacitive discharge has a peak voltage in the range from
5V to 500V.
4. An electrical power supply according to claim 3 wherein the peak
voltage is in the range from 6V to 60V.
5. An electrical according to claim 3 wherein the undriven
capacitive discharge has a resultant variable current less than 1
A.
6. An electrical power supply according to claim 4 wherein the
resultant variable current is in the range from 5 mA to 125 mA.
7. An electrical power supply according to claim 5 wherein the
undriven capacitive discharge is greater than 30 .mu.C.
8. An electrical power supply according to claim 6 wherein the
undriven capacitive discharge is in the range from 40 .mu.C to 450
.mu.C.
9. An electrical power supply according to claim 7 wherein each
undriven capacitive discharge has a resultant total energy greater
than 0.05 mJ.
10. An electrical power supply according to claim 8 wherein each
undriven capacitive discharge has a resultant total energy in the
range from 0.05 mJ to 9 mJ.
11. An electrical power supply according to claim 9 wherein each
undriven capacitive discharge has a decay constant duration in the
range from 10 .mu.s to 20 ms.
12. An electrical power supply according to claim 10 wherein the
duration is in the range from 100 .mu.s to 4 ms.
13. An electrical power supply according to claim 11 wherein
consecutive undriven capacitive discharges are delivered at a rate
from 0.1 Hz to 2 Hz.
14. An electrical power supply according to claim 12 wherein the
power supply is configured to deliver consecutive undriven
capacitive discharges are delivered at a rate from 0.5 Hz to 1
Hz.
15. An electrical power supply according to claim 1 wherein the
circuitry is configured to allow a user to adjust parameters of
said undriven capacitive.
16. An electrical power supply according to claim 1 wherein the
parameters of said undriven capacitive discharges are preset.
17. An electrical power supply according to claim 1 wherein the
circuitry is configured to deliver a bipolar capacitive
discharge.
18. An electrical power supply according to claim 1 wherein the
circuitry is configured to deliver a monopolar capacitive discharge
to single electrode and to connect to a dispersive pad.
19. An electrical power supply according to claim 1, wherein the
power supply is a tabletop power supply connected to the electrical
stimulator by a tether cord.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation U.S. patent application
Ser. No. 16/420,809, filed May 23, 2019, which is a continuation of
PCT Application No. PCT/US2017/63428, filed Nov. 28, 2017, claims
the benefit of the following prior provisional applications: U.S.
Provisional No. 62/511,301, filed May 25, 2017; U.S. Provisional
No. 62/489,389, filed Apr. 24, 2017; and U.S. Provisional No.
62/426,974, filed Nov. 28, 2016, the full disclosures of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] This invention relates generally to medical apparatus and
methods, and more particularly to a system for stimulating
contraction of intracorporeal smooth muscles.
[0003] The field of minimally invasive surgery has been around for
a relatively short amount of time, and only in the last two decades
have even common procedures such as gallbladder removal and
appendix removal shifted to minimally invasive approaches as being
the gold standard. To adapt to this new approach in operating on
patients, instruments need to change from traditional
configurations to distinctly different shapes and parameters. In
addition, interfacing remotely with tissues within the human chest
and abdomen also require procedure changes from not only
traditional methods of repair, but even tissue identification
methods as tactile feedback is largely lost requiring increased
reliance on visual indicators of structures and tissue
consistency.
[0004] The human abdomen and pelvis has two distinct types of
muscle within it. Skeletal muscle is the muscular tissue that can
be voluntarily controlled, and connects bony structures together
for movement. Smooth muscle is under involuntary (autonomic
control) and is found in gastrointestinal tissues such as the
stomach, colon and small intestine. It is also found in parts of
the urologic system such as the ureter and bladder, as well as the
thoracic cavity including the esophagus. In the ureter and
intestines these tissues contract in a pulsatile way under nervous
system control. In the case of the ureter as well as intestines,
the body spontaneously generates the initial signal at the proximal
point (e.g.--the stomach, or the kidney) and then the tissues
naturally continue to propagate this contraction down the entire
length of the organ. On a sub-cellular level, this threshold of
contraction triggering in intestinal tissue is known as the
slow-wave threshold, and initiation begins typically in tissues
known as pacemaker regions. Unique to the ureter, propagation of
the full-length contraction begins at the renal pelvis with a
ring-like contraction at the ureteropelvic junction as a response
to urine filling.
[0005] In a physiologic state, the muscles of the body (smooth and
skeletal) are typically both triggered and controlled by nerves and
nervous tissue. Through electrical signaling, the muscle tissue
responds. This response, as well as the ability to stimulate
muscles through stimulating nerves is used widely in non-invasive
approaches as well as in traditionally open (non-minimally invasive
and non-robotic) procedures with a medical focus almost exclusively
on nerves and skeletal muscle tissue. In the field of Anesthesia,
facial nerve stimulation via electrodes applied manually to the
skin is performed as a way to determine if chemical paralytic
agents are at efficacious levels. In the fields of Orthopedic
surgery and Otolaryngology, handheld stimulators are applied to
nerves in an exposed forearm or hand to identify what muscle it
controls, and in the neck, what muscles are innervated by nerves as
they are being dissected out.
[0006] Smooth muscle electrical stimulation for anatomical
identification in surgery has not been implemented in either open,
minimally invasive or robotic settings. Today, there are other
smooth muscle stimulation applications including implanted devices
that stimulate sacral nerves (and by extension the bladder) to
decrease hyperactivity of the target tissue, and devices implanted
to interrupt nerve signaling to the stomach in an effort to
decrease nausea and vomiting in gastroparesis patients. Otherwise,
electrical smooth muscle stimulation as a way to identify (or to
confirm the identity of) target tissues, or distinguish between
smooth muscle and surrounding tissue, or differentiate between
functional and non-functional tissue by location, or generate a
tissue response is a technique that is neither taught, or applied
in the field of surgery in open, minimally invasive or robotic
approaches.
[0007] During a minimally invasive operation, the surgeon relies
heavily on visual indicators to determine tissue type, expected
textures and density, as well as intracorporeal landmarks to
determine where to and not to make incisions and resections. With
the real time image being projected on a video monitor, there are
many viewing limitations such as a fixed field of view,
two-dimensional image, meanwhile the surgeon needs to be aware of
critical tissues and structures beyond the area projected onto the
video screen. As such, a surgeon is reliant on their physical,
operative capabilities for safe tissue handling, operative
experience for aberrant structures/anatomy, and on their
assistant(s) to safely project a field of view that lets them
operate effectively on the patient's behalf.
[0008] Intestinal tissues are easy to identify and manipulate in
the minimally invasive environment because they are not covered by
other tissues such as peritoneum, and so are other smooth muscle
structures such as the stomach. The ureter poses a different set of
unique challenges in the minimally invasive environment because it
resides behind the peritoneum, traverses anatomic areas such as the
pelvic brim (where it descends under tissue layers, out of
immediate view), and has several other critical structures above
and below it, obscuring it's direct identification, including major
vasculature, colon, and gynecologic anatomy that often require
surgical addressment of their pathology or temporary retraction for
accessibility.
[0009] As such, identification of the ureters can quickly become
challenging in this unique setting, especially in the minimally
invasive environment where the surgeon relies on long instruments
to manipulate and cut critical tissues. Currently there are only
two predominant methods used to both identify and protect the human
ureter in minimally invasive surgery. First, another medical
specialist, a Urologist, may be called in to the operating room to
place stiff plastic stents retrograde through the bladder and into
the ureters to stiffen them in an effort to make them more visible
on the video screen during the operation. The plastic stents are
also brightly colored, so if there is a cut or transection to the
ureter this results in the plastic being seen on the video screen
so that the injury can be addressed during the same operation.
Second, the other method is for the surgeon to perform careful and
meticulous dissection to visibly expose the ureter for
disassociating it from surrounding tissues. This approach can be
risky, especially if there is scarring or inflammation further
obscuring the ureter, where it is difficult to visualize or
identify, and as such, the dissection itself risks injury.
[0010] There exists a need to be able to identify the ureter in
this unique setting of minimally invasive surgery where dissection
can be minimized, and where alternatives such as stent placement
may not be viable or economically preferable options. In tandem,
direct smooth muscle stimulation in a minimally invasive setting in
any of the major cavities (thoracic, abdominal, pelvic) of the body
is a process that can greatly benefit the operating physician in
terms of target tissue identification, reducing procedure time and
patient morbidity, and which is an approach that has not heretofore
been implemented in a surgical setting as an adjunct surgical
technique.
[0011] These objectives are at least partly addressed by the probe
and method described in WO2015/123441, having a common inventor
with the present application. The probe has bipolar electrodes at
its tip which are used to apply a stimulation current to tissue in
the vicinity of the patient's ureter. The location of the ureter
can be visually determined by observing contraction of the ureter
in response to the applied stimulation current. While a significant
advance over prior previous methods for observing and protecting
the ureter as discussed above, the probes and methods described in
WO2015/123441 represent a first generation technology. It would be
desirable to provide improved methods and apparatus which are
compatible with additional procedures and anatomies, with
additional laparoscopic and other surgical tools, and which perform
in a more controlled and efficient manner.
2. Description of the Background Art
[0012] WO2015/123441 is discussed above. See also US2009247817;
U.S. Pat. Nos. 8,954,153; 7,877,152; and 6,292,701.
INCORPORATION BY REFERENCE
[0013] All publications, patents, and patent applications mentioned
in this specification are herein incorporated by reference to the
same extent as if each individual publication, patent, or patent
application was specifically and individually indicated to be
incorporated by reference.
SUMMARY OF THE INVENTION
[0014] The system of the present invention uses brief electrical
impulses applied directly to the target muscle to induce
contractile wave propagation in smooth muscle found in the
thoracic, abdominal or pelvic spaces in the body, such as in tissue
of the ureter. As detailed in the background above, all muscle
tissue fundamentally contracts based on electrical signals that
exist naturally in the body. The systems of the present invention
rely in part on the discovery that in certain smooth muscles, such
as the ureter, the contractile wave propagation does not have to be
unidirectional as it is in natural physiologic cases. The systems
of the present invention function by direct stimulation of smooth
muscle autonomic function, and not on nerve stimulation, to trigger
a contractile muscle response. By stimulating the muscle directly,
the systems and methods of the present invention can achieve a
highly specific response in a target anatomy, such as the
ureter.
[0015] In a first aspect, the present invention provides a method
for inducing an observable response in a targeted anatomy,
typically during a medical procedure. The method comprises
providing an electrical stimulator, typically a probe-type
stimulator having a shaft with at least one electrode at the distal
end thereof. Electrical stimulation energy is delivered from the
stimulator to tissue proximate to the target anatomy, wherein such
stimulation energy comprises a capacitive discharge of an initial
voltage. The target anatomy can be observed by visually or
otherwise detecting a response in the tissue induced by the
stimulation energy, typically a contractile response where the
target anatomy can be observed to move or otherwise change its
orientation in the visual field. In this way, fragile anatomies,
such as the ureter, which are subject to damage may be visualized
and avoided during a surgical procedure. Alternatively, in some
instances, it may be desirable to identify the target anatomy to
facilitate a surgical or other treatment.
[0016] While the methods of the present invention will often
utilize a standalone probe or other device, it will be appreciated
that electrodes and other electrical stimulating elements may be
incorporated into surgical devices so that the surgical device can
itself be used to detect the target anatomy prior to performing a
surgical procedure. In still other instances, it may be possible to
deliver the stimulating energy without using a solid electrode,
such as by using electrically conductive fluids, plasmas, or the
like.
[0017] The capacitive discharge may be "driven," e.g. controlled to
a specific decay shape regardless of tissue resistance, or
"undriven." The preferred embodiment is an undriven capacitive
discharge. By "undriven" capacitive discharge, it is meant that an
initial charge discharges with an exponential waveform having a
time constant equal to the product of controlled capacitance and
uncontrolled tissue resistance, as shown in FIG. 4 with the label
"Capacitor Discharge Wave."
[0018] In exemplary embodiments of the methods herein, the undriven
capacitive discharge will have a peak voltage in the range from 5 V
to 500 V, preferably from 6 V to 60 V. The capacitive discharge
will further preferably have a resultant variable current less than
1 A, usually being in the range from 5 mA to 125 mA. The actual
value will be the result of the voltage and charge combined with
the actual tissue resistance at the point of stimulation. Still
further, the undriven capacitive discharge will usually be greater
than 30 .mu.C, preferably being the range from 40 .mu.C to 450
.mu.C. The undriven capacitive discharge will still further
preferably have a resultant total energy greater than about 0.05
mJ, preferably being in the range from 0.05 mJ to 9 mJ. The actual
value will be the result of the voltage and charge combined with
the actual tissue resistance at the point of stimulation. In still
further instances, the capacitive discharge will usually have a
duration in the range from 10 .mu.s to 20 ms, typically being in
the range from 100 .mu.s to 1.5 ms. Additionally, when the undriven
capacitive discharge is delivered in a continuous string of pulses,
it is usually delivered at a range from 0.1 Hz to 2 Hz, preferably
being from 0.5 Hz to 1 Hz.
[0019] The exemplary target anatomy is the ureter which is to be
protected during a variety of laparoscopic and open surgical
procedures in and near the bladder. Other target anatomies include
the esophagus, stomach, bladder, and intestine due to their smooth
muscle composition in which the procedures may be used to
distinguish between functional and diseased tissue within the
organ, or the like.
[0020] In other specific embodiments of the methods herein, the
parameters of the undriven capacitive discharge will be adjustable
by a user before and during a procedure. In other instances, the
parameters of the undriven capacitive discharge will be preset so
that the user will not be able to adjust such parameters before or
during the procedure. In many instances, the capacitive discharge
will be bipolar, while in other instances the capacitive discharge
may be monopolar, typically being applied by a single electrode
while the patient is wearing a conventional dispersive or grounding
electrode at a location remote from the surgical site (FIG. 9). In
still other instances, the stimulator may comprise a shaft which
may be advanced through a trocar, typical in laparoscopic surgery
or through a working endoscope's working channel, typical of other
endoscopic procedures or through a catheter lumen, typical of other
catheter procedures. In certain alternative instances, a shaft or
other component of the stimulator may be advanced through or
concurrently with a surgical tool, while in still other instances,
the shaft may be grasped and advanced using graspers or other
conventional surgical tools in both open and laparoscopic
procedures. In yet further instances, the shaft or other component
of the stimulator may be advanced by a robot arm or other component
in robotic surgical procedures.
[0021] In a second aspect of the present invention, an electrical
stimulation system comprises a stimulator and a power supply. The
stimulator includes at least one electrode, often comprising two
electrodes for use in bipolar procedures, and the power supply is
connectible to the at least one electrode and configured to deliver
electrical stimulation energy through the stimulator to tissue
proximate a target tissue now anatomy. The stimulation energy
produced by the power supply comprises a capacitive discharge
waveform, and the electrical stimulation system is useful for
inducing observable responses in a target anatomy according to any
of the methods above.
[0022] In specific instances, the power supply is configure to
elicit a peristaltic or contractile response in a ureter when the
at least one electrode is positioned to deliver the stimulatory
energy to tissue proximate the ureter.
[0023] In preferred embodiments, the power supply is configure to
deliver an undriven capacitive discharge, and the undriven
capacitive discharge has a peak voltage in the range from 5 V to
500 V, preferably in the range from 6 V to 60 V. The undriven
capacitive discharge is further preferably a resultant variable
current less than 1 A, typically being in the range from 5 mA to
125 mA. The actual value will be the result of the voltage and
charge combined with the actual tissue resistance at the point of
stimulation. Still further, the undriven capacitive discharge will
typically be greater than 30 .mu.C, usually being in the range from
40 .mu.C to 450 .mu.C. Usually, each undriven capacitive discharge
will deliver a total resultant energy greater than 0.05 mJ,
typically being in the range from 0.05 mJ to 9 mJ. The actual value
will be the result of the voltage and charge combined with the
actual tissue resistance at the point of stimulation. Still
further, the undriven capacitive discharge will usually have a
duration in the range from 10 .mu.s to 20 ms, usually begin in the
range from 100 us to 1.5 ms. The electrical stimulation system may
be configured to allow for manual or automatic capacitive
discharges at a rate from 0.1 Hz to 2 Hz, typically from 0.5 Hz to
1 Hz.
[0024] The electrical stimulation systems may be configure to allow
for a user to adjust the discharge parameters, but in other
instances may be configured so that all discharge parameters are
preset without the opportunity for user adjustment.
[0025] The stimulator itself may be configured in any of the
arrangements described above with respect to the methods herein. In
particular, the electrodes may be monopolar, bipolar, and the
stimulator may be configured to be advanced through a trocar,
cannula, an endoscope, or a catheter, be advanced through or
concurrently with a surgical tool, be configured to be advanced
using graspers, be configured to be advanced by a robotic arm or
system, and the like.
[0026] Still further, the electrical stimulator may include a
handle, and the power supply may be disposed inside the handle with
power being provided by a rechargeable or other battery.
Alternatively, the power supply may be configured within a tabletop
unit which is connected to the probe or other electrical stimulator
by a tether cord.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1--Images showing the point of stimulation of the
ureter and the subsequent propagating contractions that progress
antegrade and retrograde away from the functional tip of the novel
device.
[0028] FIG. 2--Digital tracking and recognition of the ureter's
pathway and propagating contractile wave using computer vision.
Software system can trace the ureter's path and provide graphic
overlay to represent this path even after the contraction has
subsided.
[0029] FIG. 3--Handle details of system with visual indicators for
power and impulse delivery along with button to deliver
impulse.
[0030] FIG. 4--Monophasic square and capacitor discharge waveforms
of a single stimulating electrical pulse.
[0031] FIG. 5--Sinusoidal, symmetric and asymmetric waveforms along
with monophasic capacitor discharge waveform of a single
stimulating electrical pulse.
[0032] FIG. 6--Bipolar device tip interfacing with ureter for
stimulation. End effector electrodes are separated by nonconductive
material.
[0033] FIG. 7--Bipolar device tip variants with a cathode and anode
component to each.
[0034] FIG. 8--Device integrated into existing electrosurgical tool
and extendable/retractable with a lever on the handle to ensure
clear separation between stimulation impulse delivery and
electrocautery energy delivery into tissues.
[0035] FIG. 9--A monopolar device configuration powered via remote
electrical generator and controller with tethered hand held
component and a dispersive or grounding pad.
[0036] FIG. 10--Device embodiment with smaller end effector that
may be grasped, manipulated or integrated into robotic arms.
[0037] FIG. 11--Device embodiment with stimulator incorporated into
surgical electrosurgical, grasper, and/or dissector tools.
[0038] FIGS. 12A and 12B--Device embodiment with grasper/dissector
tools where the jaws of the distal end of the instrument function
as an anode and cathode.
[0039] FIG. 13--Device embodiment where the handle, button and
instrument shaft with end effector at distal tip are tethered to
and powered by an off-field generator via a plug-in system.
[0040] FIGS. 14A and 14B--Device embodiment with electrodes
separated from each other, having maximal surface area for
optimized impulse delivery into tissues, and distal tip lacking
sharp edges.
DETAILED DESCRIPTION OF THE INVENTION
[0041] With the system of the present invention, electrical
stimulation of the ureter in-vivo at any point along its length in
the body results in a reliable and reproducible bi-directional,
visible contractile wave (FIG. 1) that allows the operator to
quickly and reliably visualize its path on the operating video
screen during minimally invasive surgery, as well as under direct
visualization in an open abdomen operating field. A full-length
contractile wave that propagates from the point of stimulation 1 in
both directions (antegrade 2 and retrograde 3) occurs, no matter at
what point on the ureter the stimulatory effect is applied. This
wave propagation of ureter movement provides direct visual
indication of the structure's location and functionality.
[0042] Especially in cases of tortuous or often non-linear ureter
paths with structures deviating from their natural positions either
temporarily during surgical manipulation or due to a pathologic
state, the visualization of ureter movement and therefore knowledge
visualization of the path the ureter takes is critical to patient
safety as it allows the surgeon to identify and avoid injury of
this structure during surgery. This unique tissue response is
distinctly non-physiologic, as the ureter's smooth muscle
contractile wave propagation is normally unidirectional; emanating
from the kidney and progressing towards the bladder.
[0043] In tandem, the propagation waves of contraction that
progresses bi-directionally (from the point of novel stimulation)
would occur at a velocity of approximately 2 to 6 centimeters per
second. This is a unique characteristic of ureteral tissue
contractile wave propagation. With this understanding, in one
version of the system of the present invention, a computer vision
system can automatically recognize tissue contractions at these
speeds, and digitally project the path the tissue takes on the
video monitor used by the operating physician to see the operative
field (FIG. 2). In this approach, a digital representation of the
ureter's location and path 4 will be on-screen for intuitive
localization of this tissue. This may or may not require the
handheld portion of the system of the present invention to be
connected to a digital processing component off of the surgical
field. The digital tracing of the ureter's path would remain
on-screen for a set amount of time to serve as a visual reminder of
where the structure is while the surgeon continues their operation,
and then disappear to minimize potential obscuring of the operative
field of view.
[0044] The system of the present invention is also designed in such
a way to function uniquely in the minimally invasive environment,
and can easily be used in surgical procedures where tissues are
visualized directly as well. The system is can either be held by an
operator, or be grasped by an operating assistant (human or
mechanical) as it is a linear device with an extended shaft to
ensure ease of passage through laparoscopic ports that traverse the
human body wall, and serve as airtight access points into the
enclosed abdomen. Shaft length may be as long as 45 centimeters for
use in patients with a larger body habitus. The width of the
instrument shaft will be less than 6 millimeters wide. This allows
the device to function in the thoracic, abdominal and pelvic spaces
to stimulate target tissues in a minimally invasive setting as well
as easily be applicable in open surgeries with a shorter shaft
length for ease of maneuverability. The shaft may be rigid, curved,
flexible or malleable to be shaped by the physician during clinical
use.
[0045] The end of the instrument to be held by the operator or
operating assistant is to be held naturally in a pencil grip, or
palm grip. In one preferred embodiment, this end will be shaped in
a tubular fashion similar to a marker or large pencil. The
actuating button 5 that triggers voltage and current pulse delivery
positioned in such a way to be able to be pressed with the finger
or thumb of either the left or right hand (FIG. 3). Depressing the
button delivers an electrical impulse of short duration, as the
system is designed to trigger the non-physiologic bi-directional
contractile wave propagation of the target smooth muscle such as
the ureter. This ensures that impulse peak will reach the target
voltage and current in the preset impulse width. Impulses may be
delivered by the novel system at set intervals to allow the user to
keep the actuating button depressed while touching the functional
tip of the system to parts of the abdominal wall until target
tissue is close enough to be stimulated for visible
contraction.
[0046] In the preferred embodiment, the system will typically
generate short current pulse(s) of approximately 10 microseconds to
20 milliseconds in total signal duration (but which may be as long
as 500 milliseconds) with single activation. By holding down the
trigger, the system will continue to discharge impulse(s) at 0.5 to
1 hertz increments continually until release. The system's waveform
may vary depending on the embodiment. In embodiments where the
system is likely to be powered and tethered to a power generator,
the waveform may be sinusoidal, 1 to 600 kilohertz in frequency
(preferentially below 100 kilohertz to optimize tissue reactivity),
and with the total signal duration being again in the 10
microsecond to 20 milliseconds range (up to 500 milliseconds) which
would ideal for muscular contraction without resulting in tissue
injury.
[0047] To reduce the risk of tissue injury, the peak voltage of
system will be maintained at or below 500 volts, with the current
at or below 1 ampere with a 550 ohm load setting. The voltage will
typically be at least 5 volts with the same load, as this would not
be sufficient in serving to trigger the contractile wave
propagation in smooth muscle tissue. Unlike other stimulation
systems, these stimulation systems will typically be voltage
controlled to effectively deliver a pulse capable of generating a
visible, smooth muscle contraction. Skeletal nerve stimulation is
typically performed with current as a primary controlled factor
(e.g. current driven) in generating a nerve/skeletal muscle
response as previously described, wherein tissue resistance
experienced is greater than 1000 ohms. These nerve/skeletal muscle
stimulation devices, operating against a lower intracorporeal
tissue resistance, e.g. less than 1000 ohms, will not deliver a
voltage sufficient to elicit a smooth muscle contraction. In
contrast, by using voltage control, the system of the present
invention, assures sufficient voltage is delivered into the lower
tissue resistance found with intracorporeal smooth muscle tissues
to elicit a visible response. When set for an approximately 550 ohm
load, the system of the present invention device can deliver at
least 6 volts, 7 milliamps, with a charge greater than 30
microcoulombs and an energy of greater than 0.05 millijoules with a
capacitor discharge waveform 6 (FIG. 4).
[0048] Voltage and current in the bipolar version of the system can
be safely applied to target tissues without concern of cardiac
arrhythmic stimulation since the electrical impulse travels between
the electrodes only a short distance apart from each other (on the
order of millimeters) and is of an extremely brief duration. In a
monopolar system design, the electrical power is rapidly diffused
from the hand held portion of the device on through the grounding
pad again providing safe passage of the electrical signal.
[0049] The current powering the handheld system in one embodiment
would be DC current, as in one preferred embodiment the system
would be battery powered, single use and fully disposable. In the
tethered system, the expected current would be initially AC with
subsequent signal conversion prior to impulse discharge into target
tissues.
[0050] In this or other embodiments, the impulse may be of a
curvilinear degeneration similar to a capacitor discharge 7
(monophasic). The impulse waveform may also have a square wave
component to it, and as such may form a balanced or unbalanced,
symmetric 8 or asymmetric 9 biphasic waveform. The waveforms
generated by the novel system would not be limited to these, and
may be tailored for targeting different types of target tissues
depending on their response ranges, distance away from impulse
discharge, and thickness/quality/resistance of tissues in between
target tissues and proposed system (FIG. 5).
[0051] In a preferred embodiment, the waveform will be one of a
capacitor discharge as this closely mimics physiologic action
potentials within muscles and nerves. As square wave impulses are
less physiologic in character, application of a square wave for
smooth muscle stimulation requires an increased voltage and is less
preferred. The minimum voltage for smooth muscle stimulation using
a capacitive discharge waveform is typically 6 volts with signal
duration of 2.2 millisecond decay constant (time to 1/e discharge,
or approximately 36.8% of the initial voltage). In contrast,
minimum voltage for smooth muscle stimulation using a square
waveform is typically 15 volts with signal duration of 1000
microseconds Voltage levels also need to be increased as signal
duration decreases. The same requirements are present for symmetric
and asymmetric biphasic waveforms.
[0052] The capacitor discharge waveform has been found to require a
lower voltage than other tested waveforms, resulting lower current
and power requirements than other waveforms. This is particularly
advantageous for battery-driven designs as described herein as well
as for integrating the technology into another instrument where
space for insulating the stimulation wiring may be limited. An
"undriven" capacitor discharge waveform relies on the inherent
discharge of voltage degradation/time constant from capacitors in a
closed circuit and was found to be more efficacious in eliciting
the response than a use of "driven capacitor discharge" waveform
(e.g. matching a specific voltage degradation curve using a
function generator).
[0053] An alternative preferred "Voltage Driven" circuit assures
the voltage, which is the primary influencing factor, elicits a
smooth muscle response and is always within the preferred range and
that the resulting current varies dependent upon the load (tissue)
resistance. Prior art nerve stimulators use a "current driven"
circuit design which causes a significant drop in resulting voltage
when used with low load (tissue) resistance as found with moist,
intracorporal tissues.
[0054] Table 1 below provides exemplary and preferred operational
parameters for tissue stimulation using a monophasic, undriven
capacitor discharge waveform:
TABLE-US-00001 TABLE 1 Broad Preferred Parameter Defined Range
Range V-Voltage, Measured peak voltage, 5 V-500 V 6-60 V Peak
(input) combined with a current not to exceed 1A, across a 550 Ohm
load (tissue) resistance. I-Current, Not to exceed 1A across a
<1A 5 mA-125 mA Peak(output) 550 Ohm load (tissue), the actual
value is the resultant of the voltage, charge and tissue resistance
at the site of stimulation Q-Charge Amount of capacitive >30
.mu.C 40 .mu.C-450 .mu.C (input, charge in the circuit Coulombs =
released at the time of ampere- pulse initiation seconds) E-Energy
Amount of energy >0.05 mJ 0.05 mJ-9 mJ (output) generated per
pulse, the actual value is the resultant of the voltage, charge and
tissue resistance at the site of stimulation T-Time, Decay constant
(time to 1/e 10 .mu.s-20 ms 100 .mu.s-4 ms Duration (input)
discharge or 36.8% of the initial voltage) F-Frequency When button
held down, 0.5-1 Hz 0.5-1 Hz of repetitive continued discharge at
pulses (input)
[0055] Table 2 below provides exemplary and alternative operational
parameters for a voltage-driven tissue stimulation using a
monophasic, square waveform:
TABLE-US-00002 TABLE 2 Broad Preferred Parameter Defined Range
Range V-Voltage, Measured peak voltage, 10 V-500 V 15 V-100 V Peak
(input) combined with a current not to exceed 1A, across a 550 Ohm
load (tissue) resistance. I-Current, Not to exceed 1A across a
<1A 30 mA- Peak (output) 550 Ohm load (tissue), the 200 mA
actual value is the resultant of the voltage, charge and tissue
resistance at the site of stimulation Q-Charge Amount of capacitive
>30 .mu.C >100 .mu.C (input, ampere- charge in the circuit
seconds) released at the time of pulse initiation E-Energy Amount
of energy >0.05 mJ >3.5 mJ (output) generated per pulse, the
actual value is the resultant of the voltage, charge and tissue
resistance at the site of stimulation T-Time, Length of Pulse 10
.mu.s-20 ms 10 .mu.s- Duration (input) 500 ms F-Frequency When
button held down, 0.5-1 Hz 0.5-1 Hz of repetitive continued
discharge at pulses (input)
[0056] In a preferred embodiment, the voltage and current generator
along with all other electrical settings of the system will
typically not be user adjustable, and will be at a locked setting
both to ensure system efficacy, and to ensure patient safety. These
settings, as well as the button, LED(s), and other electronic
components will be set into a printed circuit board inset into the
handle of the system. The system in one preferred embodiment will
be powered by at least one battery (12-Volt or otherwise) not only
for generator requirements, but also to maintain the low-profile,
cylindrical shape of the handle. Having an internal power source
also maintains a stand-alone system that does not require any
cables or cords for grounding or power in this embodiment. As the
system will be intended for single-use, a power-off switch will be
absent, and in one preferred embodiment, the system will be
activated by removing a nonconductive pull-tab that serves as a
physical boundary to completing the circuit in the handle of the
system while being stored before use.
[0057] In a preferred embodiment, the system would provide visual
cues not only of the status of the power source, but also of when
electrical stimulation is applied at the functional tip of the
device. These may be light emitting diodes (LEDs) visible on the
end of the system held by the operator or operating assistant 10.
In one preferred embodiment, one LED will turn on when system is
actuated in such a way that the LED will be on during impulse
delivery and then turn off. A second LED will remain on the
entirety of the time the system is powered, and will turn off when
the DC power source is no longer capable of generating an impulse
of the specified voltage and current.
[0058] The end of the system of the present invention that
interfaces with the smooth muscle target is comprised of no fewer
than two electrodes so that the system is of a bipolar design.
Contacting tissue completes the circuit, and the electrical impulse
is delivered from the body of the system, down the shaft, through
the abdominal wall and through the tissue in a matter triggered by
the operator(s). When the system comes in close enough contact with
target smooth muscle such as the ureter, and the electrical impulse
is sent to that tissue, it will generate a bi-directional full
length contraction of the ureter that will be visible on the video
screen for the operator, or directly in the field of view in an
open surgical procedure.
[0059] With the system of the present invention, there is enough
tissue penetration by the electrical stimulation caused by the
generation of an electrical field to initiate the target tissue
contraction. This effect will then be visible to the operator on
the video monitor even without deep tissue dissection, as the path
of the ureter can be seen as movement translated to the overlying
tissues. The main limitation to visualization in this case is the
thickness of these overlying tissues as the electrical stimulation
has a depth of penetration that likely exceeds visible movement
translation. In addition, the unique setting of minimally invasive
surgery is one where the patient's skeletal muscle is chemically
paralyzed as to allow for maximal expansion of the now-paralyzed
abdominal wall. The paralytic agents used in the operating room do
not affect smooth muscles such as intestines and ureters. As such,
the system of the present invention is extremely specific in
stimulation, and subsequent visual identification of smooth muscles
such as the ureter, since all nearby skeletal muscle is unable to
respond to the system's stimulatory signals. This is a unique
feature and application of our system that would not be obvious to
those skilled in the art.
[0060] Higher voltage pulse stimulation, e.g. higher than 50V,
would be clinically undesirable in extremity, orthopedic, ENT or
other open surgery due to the patient's skeletal muscles and
nervous system response, e.g. an involuntary reflex (jerk, jump or
twitch) on the operating table. Using higher voltage pulse
stimulation as described herein is clinically acceptable in
laparoscopic, robotic, NOTES, or other minimally invasive surgeries
due to the concurrent administration of the paralytic anesthetic
agents, used to relax the skeletal muscles and nerves and by doing
so, suppresses their responses to higher voltage stimulation. As
smooth muscle structures are not affected by these agents, the
visual response from higher voltage stimulation assures it is a
smooth muscle structure that responds, minimizing any confusion as
to the anatomical structured interrogated.
[0061] To ensure successful target tissue stimulation, and remain
as a potential stand-alone system, the functional tip of the system
of the present invention will have no fewer than two electrodes
spaced a minimum of 1 millimeter apart. The electrodes will be
insulated from each other and the remainder of the system, and
separated proximally in one embodiment by nonconductive, synthetic,
polymer based material to prevent electrical arcing. In one
preferred embodiment, these electrodes are connected to the circuit
board and the power source in the handle of the system via
conductive wires that are individually shielded to prevent
electrical shorting or arcing not only to each wire, but to the
shaft of the system as well. The shaft of the system would be
constructed of a stiff, nonconductive tubular material such as
polyamide, or of an insulated metal (such as stainless steel with
polymer coating) to prevent unintended electrical signal
transfer.
[0062] The human ureter is on average 3 millimeters wide, and as
such the electrodes on the tip of the system of the present
invention will in one preferred embodiment be spaced approximately
3 millimeters apart and oriented perpendicularly to the linear
pathway of the ureter 11. This results in an electrical stimulation
that traverses the ureter in a transverse plane, with an electrical
field generated between the electrode tips of the bipolar
arrangement, and as such triggers the smooth muscle in a plane that
matches physiologic signal propagation (FIG. 6).
[0063] With further reference to FIG. 5, excitatory current for
smooth muscle stimulation according to the present invention may be
delivered with a variety different waveforms or shapes as viewed on
an oscilloscope. The described waveforms may all be adjusted to
elicit a ureter contractile response as well as smooth muscle
contraction in other organs and parts of the body.
[0064] A sinusoidal waveform 12 suitable for smooth muscle
stimulation according to the present invention would typically have
a frequency below 100 kHz (frequencies above that value are
typically ineffective and potentially injurious). This waveform can
be adjusted to parameters that are non-injurious and are optimized
for smooth muscle stimulation allowing for ease of instrument
integration.
[0065] Symmetric, balanced waveforms 8 (FIG. 5) with defined
positive and negative components in the form of matched square
waves may also be used for smooth muscle stimulation according to
the present invention. An exemplary wave would have a positive
square pulse followed by an equal negative square pulse, providing
a fully controlled, balanced waveform that would avoid a
deleterious buildup of net charge, avoiding potential burns and
injury to the engaged tissue.
[0066] An asymmetric, balanced waveform 9 (FIG. 5) having defined
positive and negative components, e.g. one square wave and a
capacitor discharge waveform as the balancing component, may also
be used for smooth muscle stimulation according to the present
invention. Such a balanced waveform would also minimize or avoid
and buildup of net charge. Such biphasic impulses would preferably
have an active phase that has a positive amplitude with current
traveling through the cathode into the tissue, where the balancing
phase would have current return through the anode. Such an
asymmetric, balanced waveform could be optimized not only for
smooth muscle stimulation but also for nerve stimulation (as
neurons respond more readily to negative current signals).
[0067] Additionally, monophasic waveforms 7 (FIG. 5), such as the
capacitor discharge and square wave signals described previously,
when discharged in brief bursts, would be effective in eliciting
target tissue contraction, have a net charge that can be optimized
into a set impulse duration, and present minimum risk of injury to
target tissues.
[0068] In other aspects, a functional tip of the system of the
present invention may be devoid of angular points, needles or
cutting edges as to avoid iatrogenic injury, and also to allow the
system to be used as a blunt dissector or probe. The tip may be a
pair of electrodes configured with rounded external features 13,
consist of a ring and a point electrode 14 for a streamlined,
atraumatic tip that has an omnidirectional ability to stimulate
target tissues, or be physically separated in a Y configuration 15,
all in the case of bipolar design among any other potential
configurations designed to fit through a 5 mm trocar shaft (FIG.
7). The surface areas of the electrodes will be adequate to
maintain appropriate current density for desired stimulation of
target tissues. In any possible permutation of tip design, there
will always be the ability for the electrons to flow from one
electrode to another when the circuit is completed via tissue
contact, thus resulting in the desired tissue response. The bipolar
design would in one embodiment ensure safe electrical impulse
control and localization.
[0069] Systems of the present invention may be mounted in tandem,
or integrated into a camera system used in minimally invasive
surgery or robotic surgery. The system of the present invention may
also be implemented with a flexible, malleable, steerable, and/or
rigid linear or curved shaft in such a way as to be used in
endoscopic procedures, catheter-based percutaneous procedures,
natural orifice surgical approaches, or otherwise incorporated into
robotic systems used in procedure or operating rooms. The shaft of
the instrument may either have a flexible neck segment, or be
completely flexible. The system of the present invention may also
be combined with other existing surgical instruments either as an
interchangeable tip that may be advanced or retracted on demand by
the user, or remain in place as an integrated part of the existing
instrument that may then be activated by the user, or may be
incorporated into the instrument's existing features.
[0070] To increase surgeon efficiency and to provide a closer to
real-time method of detection of the ureter, the systems of the
present invention may also be integrated into electrosurgical and
other instrument used in open or minimally invasive surgery, such
as graspers, scissors, suction irrigators or other dissection
instruments. Such embodiments will usually have stimulation
controls separate from the deployment and activation mechanisms
used for cutting or cauterizing effects of the electrosurgical tool
as to ensure the physician can safely distinguish between
stimulation and treatment. In one embodiment, a probe with the
bipolar tip 16 may be reversibly extended from the functional end
of the electrosurgical instrument with a lever 17, and a button
depressed to generate the stimulatory effect. This would ensure a
purposeful and safe distinction between stimulation and cut/cautery
(FIG. 8). In another embodiment, the bipolar tip is implemented by
each of the two fingers of a grasper acting as the individual
electrodes spatially separated during use to mimic the required
separation distance for proper use.
[0071] In an embodiment of the system of the present invention
where the device is connected to a power generator 18 either on or
off of the surgical field (i.e.--paired or connected to another
electrosurgical instrument platform), the functional tip of the
device may also be an atraumatic single electrode 19. Since the
patient will already have a grounding pad 20 attached to their body
for the other electrosurgical instrument(s) usage, stimulation of
target tissues can be performed in a monopolar fashion as the
circuit will be completed through the body. In this version, the
functional tip of the device would preferentially be the cathode.
If desired in an embodiment, the functional tip of the device may
remain bipolar (even if integrated into a monopolar electrosurgical
instrument platform) for more focused impulse delivery that may
require less energy and power (FIG. 9). In either embodiment, the
stimulatory signal may be triggered on the hand held component of
the system via a switch, or using an alternate switch such as a
foot pedal.
[0072] With an understanding of the novel, defined energy
parameters and system functional tip requirements, the system of
the present invention may be integrated into minimally invasive, or
open surgical devices and systems that are either inherently
powered, or may have attachments to power them for this stimulatory
function. In an automated, or robotic setting where the care
provider is operating at a console or otherwise in an indirect
fashion, the system of the present invention may be place into or
onto one arm of the operating equipment in a reversible or
irreversible fashion based on hardware design. It may also be a
separate component 21 that is grasped by the robotic platform (FIG.
10). In this embodiment, the tip configuration would be similar to
the hand held version of the system, but the shaft length may be
shortened to allow for greater intracorporeal maneuverability
(especially when operating in spaces such as the pelvis). If the
operating equipment already requires a grounding pad be placed on
the patient, the functional tip of the system of the present
invention may be constructed in a monopolar fashion with a single
electrode tip. Stimulation initiation would be triggered either
with a hand controller or foot controller based on the surgeon
interface. An audio and/or visual cue would also be present to
inform the operator that an electrical impulse was being
delivered.
[0073] With power profiles intended for smooth muscle stimulation,
the system of the present invention is not only applicable in
generating non-physiologic, visible contractile response to the
ureters, but also for other structures that contain smooth muscle
tissues. In assisting placement of gastric pacer electrodes within
key parts of the stomach wall, the system can first be used to
ensure that the intended innervated (or poorly innervated) sections
of the stomach can and will respond to electrical stimuli as
expected. The system can then be used to facilitate accurate
placement of more permanent electrodes into and onto the
stomach.
[0074] In cases of intestinal diseases such as Hirschprung's where
the colon lacks innervation to certain portions, an intracorporeal
stimulator may be used to determine at what level and what part(s)
of the colon do and do not respond to excitable stimuli. This can
assist the operator(s) in determination to what level, and at what
level any potential surgical intervention may need to be done, and
may allow for more precise resections and maximal tissue
preservation. The same approach may also be used for the smooth
muscle portions of the esophagus to identify functionally
responsive and less responsive tissues or sections.
[0075] There is also the ability for the system to assist in
identification of the location and pathways that nervous tissue may
take as well in the intracorporeal setting such as the obturator
nerve in pelvic procedures where the tissue planes are distorted
due to tumor or scarring. With the tissue penetrating signal from
the system, nervous tissue can also be stimulated in a
non-paralyzed setting, and thus let the operator(s) know where
nervous tissue that they may want to avoid is located even without
direct visualization.
[0076] As shown in FIG. 11, the stimulators of the present
invention may be incorporated into surgical instruments, such as
powered electrosurgical tools and/or grasper/dissector tools. When
incorporated into electrosurgical/electrocautery tools, the
stimulators may have an end effector 22 on or at a distal region or
tip of a shaft that is insulated and may be parallel or
incorporated with the other electromechanical components of the
instrument. The end effector may be either fixed in place, or more
preferably be able to be extended and retracted with a lever 23 or
other actuating mechanism. This provides the surgeon with the
flexibility of having multiple powered surgical instrument features
in a single device, and would increase operating efficiency since
there would not be a need to do an instrument exchange multiple
times during an operation.
[0077] As shown in FIGS. 12A and 12B, the stimulators of the
present invention may alternatively be incorporated into
grasper/dissector tools where the jaws 24 function as the anode and
the cathode thus permitting the effector end of the instrument to
deliver the stimulatory electrical impulses as well as to provide
the desired surgical function. In this embodiment, the novel
stimulator's power and impulse generation component 25 may be
reversibly or irreversibly attached. The stimulator may also be
integrated into or grasped by a robotic surgical platform's
instruments. Since the surgeon would be operating the robotic
platform from a console, the stimulator would typically be grasped,
manipulated and otherwise positioned by the robotic surgical
platform's arms.
[0078] As shown in FIG. 13, a handheld component 26 may be powered
via an off-field, programmable electrical generator. Advantage of
using such remote generators include that they are commonly present
in most operating rooms and able to convert line voltage into
programmable waveforms and adjustable signal intensities. When
powered a remote generator, the hand-held component be made
lighter, have a thinner profile, and be more cost efficient since
enclosed batteries and circuit components will no longer need to be
fully housed in the handle. Powering the systems of the present
invention with a generator could also facilitate user adjustable
impulse frequency, intensity, waveform and signal duration changes
made while the non-tethered embodiment will often have fixed
features.
[0079] As shown in FIGS. 14A and 14B, an end effector may be
bipolar allowing the system of the present invention to operate in
a stand-alone mode or be powered with a remote generator,
potentially eliminating the need for a grounding or dispersive pad
attachment to the patient. The tip will typically have a diameter
no wider than 6 mm to allow for introduction through a working
channels or lumen of other instruments, trocars, and the like. The
end effector of such bipolar instruments may have two blunt/flat
electrodes physically separated by nonconductive material and/or
space. This ensures the delivered electrical impulse is optimally
delivered into target tissues. Depending on the embodiment, the
electrodes may encompass part of the circumference of the distal
tip 27 (FIG. 14B) of the device, or otherwise follow the contours
of the device end 28 (FIG. 14A) to minimize angles, allow for safe
maneuvering around delicate tissues, and have been optimized for
manufacturability.
[0080] The system described may be applied in any minimally
invasive process where the instruments are inserted through the
body wall towards target tissues (as well as applied in open thorax
or abdomen procedures). The minimally invasive processes may be
either performed by (an) operator(s) handling the instruments
directly as they stand next to the patient in the operating room,
or by (an) operator(s) interfacing with a surgical system that
interfaces with the patient.
* * * * *