U.S. patent application number 10/756552 was filed with the patent office on 2004-07-29 for gastric stimulator apparatus and method for installing.
This patent application is currently assigned to Transneuronix, Inc.. Invention is credited to Gordon, Pat L., Jenkins, David A..
Application Number | 20040147976 10/756552 |
Document ID | / |
Family ID | 30114019 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040147976 |
Kind Code |
A1 |
Gordon, Pat L. ; et
al. |
July 29, 2004 |
Gastric stimulator apparatus and method for installing
Abstract
Apparatus for stimulating neuromuscular tissue of the
gastrointestinal tract and methods for installing the apparatus to
the neuromuscular tissue. The pulse generator is provided with a
switching matrix, and may stimulate the tissue in a time-varying
manner by selecting pairs of electrodes and altering the polarities
thereof while stimulating the tissue. In addition, a real-time
clock allowing a trigger for on and off modes, the time clock could
also allow for a trigger to change parameters. Such parameters that
could be changed are pulse width, amplitude, duty cycle (amount of
time of pulse and time between pulses, or series of pulses),
frequency, polarity, choice of unipolar versus bi-polar, and
electrode on-off. The electrical stimulation utilizes a plurality
of electrodes connected to at least one organ in the
gastrointestinal tract of a patient along a peristaltic flow path
with each of the electrodes being connected at a different location
along the peristaltic flow path. Electrical pulses are provided to
the organ from a first set of the plurality of electrodes and
second electrical pulses are provided to the organ from a second
set of electrodes. The electrical pulses provided are in an
independent non-phased relationship for maintaining therapeutic
regulation of peristaltic flow through the at least one organ in
the gastrointestinal tract while defeating the body's natural
tendency for adaption.
Inventors: |
Gordon, Pat L.; (Wayzata,
MN) ; Jenkins, David A.; (Flanders, NJ) |
Correspondence
Address: |
FITCH EVEN TABIN AND FLANNERY
120 SOUTH LA SALLE STREET
SUITE 1600
CHICAGO
IL
60603-3406
US
|
Assignee: |
Transneuronix, Inc.
|
Family ID: |
30114019 |
Appl. No.: |
10/756552 |
Filed: |
January 13, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10756552 |
Jan 13, 2004 |
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10189120 |
Jul 2, 2002 |
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6684104 |
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10189120 |
Jul 2, 2002 |
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09466731 |
Dec 17, 1999 |
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6542776 |
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60129198 |
Apr 14, 1999 |
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60129199 |
Apr 14, 1999 |
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60129209 |
Apr 14, 1999 |
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Current U.S.
Class: |
607/48 |
Current CPC
Class: |
A61N 1/05 20130101; A61N
1/0558 20130101; A61N 1/36007 20130101 |
Class at
Publication: |
607/048 |
International
Class: |
A61N 001/18 |
Claims
What is claimed is:
1. Method of applying electrical stimulation to the neuromuscular
tissue in the viscera, comprising: providing an electrode
attachment assembly supporting a plurality of electrode pairs
thereon for attachment to the tissue such that the plurality of
electrode pairs are positionable at substantially different
locations thereon; laparoscopically inserting the electrode
attachment assembly through a surgical access opening in the
patient; attaching the electrode attachment assembly to the
neuromuscular tissue such that the plurality of electrode pairs are
spaced apart, thereby forming an electrical interface between each
of the plurality of electrode pairs and the neuromuscular tissue;
and electrically stimulating the tissue in a time-varying manner
with selectable individual pairs of the plurality of electrode
pairs with a pulse generator.
2. Method defined in claim 1, wherein the providing an electrode
attachment assembly comprises providing a first electrode
attachment member configured to pass through the tissue and
supporting a first electrode pair thereon and a second electrode
attachment member configured to pass through the tissue and
supporting a second electrode pair thereon spaced a first distance
apart, and a flexible bridging portion attached to the first and
second electrode attachment members and configured to allow
relative positioning of the first and second electrode attachment
members at differing positions on the neuromuscular tissue of the
viscera of the organ structure, including the gastrointestinal
tract.
3. Method defined in claim 1, wherein the providing an electrode
attachment assembly comprises providing an electrode attachment
member supporting the plurality of electrode pairs on a distal
surface thereon spaced substantially equidistantly apart; and
wherein the attaching the electrode attachment member to the
neuromuscular tissue comprises attaching the distal surface of the
electrode attachment member to the surface of the viscera, thereby
forming an electrical interface between each of the first, second,
third, and fourth electrodes and the neuromuscular tissue.
4. Method defined in claim 2, wherein the plurality of electrode
pairs comprise a first and a second diagonally-oriented electrode
pair, and wherein electrically stimulating the tissue comprises:
applying electrical stimulation across the first
diagonally-oriented electrode pair during a first time period; and
independently applying electrical stimulation across the second
diagonally-oriented electrode pair during a second time period.
5. Method defined in claim 4, further comprising: applying
electrical stimulation across the first diagonally-oriented
electrode pair during a third time period such that the polarity of
each of the electrodes comprising the first diagonally-oriented
electrode pair is reversed from the polarity of the respective
electrodes during the first time period; and independently applying
electrical stimulation across the second diagonally-oriented
electrode pair during a fourth time period such that the polarity
of each of the electrodes comprising the second diagonally-oriented
electrode pair is reversed from the polarity of the respective
electrodes during the second time period.
6. Method defined in claim 2, wherein the plurality of electrode
pairs comprise a first, second, third and fourth adjacent electrode
pairs, and wherein electrically stimulating the tissue comprises:
applying electrical stimulation across the first adjacent electrode
pair during a first time period; applying electrical stimulation
across the second adjacent electrode pair during a second time
period; applying electrical stimulation across the third adjacent
electrode pair during a third time period; and applying electrical
stimulation across the fourth adjacent electrode pair during a
fourth time period, said first, second, third, and fourth time
periods being triggered in an independent non-phased relationship
to one another.
7. Apparatus for electrically stimulating neuromuscular tissue of
the viscera of the organ structure, including the gastrointestinal
tract by applying electrical pulses to the neuromuscular tissue,
the electrical pulses supplied by a pulse generator, comprising:
first and second electrodes electrically connected with the pulse
generator; first electrode-pair attachment member having a body
portion configured to penetrate through the tissue and supporting
the first and second electrodes thereon spaced a first distance
apart; third and fourth electrodes electrically connected with the
pulse generator; second electrode-pair attachment member having a
body portion configured to penetrate through the tissue and
supporting the third and fourth electrodes thereon spaced a second
distance apart; bridging portion attached to the first and second
electrode-pair attachment members and configured to allow relative
positioning of the first and second electrode-pair attachment
members in the tissue such that the first, second, third and fourth
electrodes may be substantially equidistantly spaced apart; and a
pulse generator configured to supply electrical pulses to the
first, second, third, and fourth electrodes in a time-varying
manner with selectable pairs of the electrodes in an independent
non-phased relationship to one another.
8. Apparatus defined in claim 7, wherein the pulse generator
comprises a switching matrix responsive to a controller for
applying the selectable pairs of electrodes with stimulating pulses
of predetermined polarities.
9. Apparatus defined in claim 7, wherein the pulse generator is
configured to apply electrical stimulation between the first
diagonally-oriented electrode pair having a first polarity and the
second diagonally-oriented electrode pair simultaneously having a
second polarity.
10. Apparatus defined in claim 7, wherein the first, second, third,
and fourth electrodes comprise a first and a second
diagonally-oriented electrode pair, and wherein the pulse generator
is configured to apply electrical stimulation across the first
diagonally-oriented electrode pair during a first time period, and
apply electrical stimulation across the second diagonally-oriented
electrode pair during a second time period.
11. Apparatus defined in claim 10, wherein the pulse generator is
further configured to apply electrical stimulation across the first
diagonally-oriented electrode pair during a third time period such
that the polarity of each of the electrodes comprising the first
diagonally-oriented electrode pair is reversed from the polarity of
the respective electrodes during the first time period, and apply
electrical stimulation across the second diagonally-oriented
electrode pair during a fourth time period such that the polarity
of each of the electrodes comprising the second diagonally-oriented
electrode pair is reversed from the polarity of the respective
electrodes during the second time period.
12. Apparatus defined in claim 7, wherein the first, second, third,
and fourth electrodes comprise a first, second, third and fourth
adjacent electrode pair, and wherein the pulse generator is
configured to apply electrical stimulation across the first
adjacent electrode pair during a first time period, apply
electrical stimulation across the second adjacent electrode pair
during a second time period, apply electrical stimulation across
the third adjacent electrode pair during a third time period, and
apply electrical stimulation across the fourth adjacent electrode
pair during a fourth time period.
13. A method for electrically stimulating neuromuscular tissue of
the viscera of the organ structure, including the gastrointestinal
tract, comprising: connecting a plurality of electrodes to at least
one organ in the gastrointestinal tract of a patient along a
peristaltic flow path, each of said plurality of electrodes being
connected at a different location along said peristaltic flow path;
providing electrical pulses to said organ from a first set of said
plurality of electrodes; and providing second electrical pulses to
said organ from a second set of said plurality of electrodes, said
electrical pulses provided by said plurality of electrodes being in
an independent non-phased relationship for maintaining therapeutic
regulation of peristaltic flow through said at least one organ in
said gastrointestinal tract while defeating the body's natural
tendency for adaption.
14. The method of claim 13 comprising providing the first
electrical pulses and the second electrical pulses according to a
real-time clock function.
15. The method of claim 13 further comprising the step of
independently regulating a pulse amplitude, a pulse timing, and a
pulse duration for said electrical pulses for each one of said
plurality of electrodes.
16. A gastric pacemaker for controlling the peristaltic pace of
digestive organs by electrically stimulating neuromuscular tissue
of the viscera of the organ structure, including the
gastrointestinal tract, comprising: a plurality of stimulation
electrodes sequentially positionable on at least one digestive
organ along a peristaltic flow path; controller for controlling
electrical pulse parameters for a first set of said plurality of
stimulation electrodes; said controller controlling electrical
pulse parameters for a second set of said plurality of stimulation
electrodes in an independent non-phased relationship according to a
desired peristaltic flow; and circuitry for providing electrical
pulses to each of the first set and the second set of said
plurality of stimulation electrodes in accordance with a real-time
clock function.
17. A gastric pacemaker as recited in claim 16 further comprising a
sensor electrode connectable to said digestive organ for sensing a
response of said organ to an electrical pulse stimulation.
18. A gastric pacemaker as recited in claim 16, wherein at least
one of said plurality of stimulation electrodes also functions as a
sensing electrode for sensing a response of said organ to an
electrical pulse.
19. A method for electrically stimulating neuromuscular tissue of
the viscera of the organ structure, including the gastrointestinal
tract, comprising: connecting a plurality of electrodes to at least
one organ in the gastrointestinal tract of a patient along a
peristaltic flow path, each of said plurality of electrodes being
connected at a different location along said peristaltic flow path;
providing electrical pulses to said organ from a first set of said
plurality of electrodes; and providing second electrical pulses to
said organ from a second set of said plurality of electrodes for
maintaining therapeutic regulation of peristaltic flow through said
at least one organ in said gastrointestinal tract while defeating
the body's natural tendency for adaption.
20. The method of claim 19, further comprising the step of
providing said first and second electrical pulses according to a
real-time clock function.
21. The method of claim 20, further comprising the step of
providing time-of-day and date information from said real-time
clock function to a programmable calendar.
22. The method of claim 20, wherein said electrical pulses provided
by said plurality of electrodes are in an independent non-phased
relationship.
23. The method of claim 21, wherein said electrical pulses maybe
varied in accordance with said real-time clock function for
enabling a stimulating waveform from said electrical pulses to vary
over periods of time based on a setting of said real-time clock
function.
24. The method of claim 21, wherein said real-time clock functions
serve as a trigger for changing stimulation parameters on a
periodic basis.
25. The method of claim 24, wherein said real-time clock functions
serve as a trigger for changing stimulation parameters on a
periodic basis.
26. The method of claim 25, wherein said stimulation parameter
comprises a pulse width of said electrical pulses.
27. The method of claim 25, wherein said stimulation parameter
comprises an amplitude of said electrical pulses.
28. The method of claim 25, wherein said stimulation parameter
comprises a duty cycle of said electrical pulses.
29. The method of claim 25, wherein said stimulation parameter
comprises a frequency of said electrical pulses.
30. The method of claim 25, wherein said stimulation parameter
comprises a polarity of said electrical pulses.
31. The method of claim 25, wherein said stimulation parameter
comprises activating and deactivating generation of said electrical
pulses for a predetermined length of time.
Description
[0001] This is a continuation-in-part of prior application Ser. No.
09/466,731, filed Dec. 17,1999, which application claims the
benefit of U.S. Provisional Application No. 60/129,198, U.S.
Provisional Application No. 60/129,199, and U.S. Provisional
Application No. 60/129,209, all of which were filed Apr. 14, 1999,
each of which is incorporated by reference in its entirety
herein.
BACKGROUND OF THE INVENTION
[0002] This invention relates to electrical stimulation apparatus
and methods for use in stimulating body organs, and more
particularly to implantable apparatus for stimulating neuromuscular
tissue of the viscera of the organ structure, including the
gastrointestinal tract and methods for installing the apparatus in
a patient.
[0003] The field of electrical tissue stimulation has recently been
expanded to include devices which electrically stimulate the
stomach or intestinal tract with electrodes implanted in the
tissue. These gastric stimulators have been found to successfully
combat obesity in certain studies. Medical understanding as to how
this treatment functions to reduce obesity is currently incomplete.
However, patients successfully treated report achieving normal
cycles of hunger and satiation.
[0004] An apparatus and treatment method for implementing this
therapy was described in U.S. Pat. No. 5,423,872 to Dr. Valerio
Cigaina, which is hereby incorporated by reference in its entirety
herein. The apparatus described in the Cigaina patent stimulates
the stomach antrum pyloricum with trains of stimulating pulses
during an interval of about two seconds followed by an "off"
interval of about three seconds.
[0005] U.S. Pat. No. 5,836,994 to Bourgeois describes a
laparoscopic device which has a needle which passes through the
tissue being stimulated, and a thread attached at one end to the
needle and at the other end to an implantable pulse generator (IPG)
lead. The entire device can be inserted into the body via a
laparoscopic type tube, or trocar, as it is relatively long and
narrow. Many devices are known to be inserted through a trocar by
having a needle attached with a thread to the devices.
[0006] Copending Cigaina U.S. Application PCT/US98/1042, filed on
May 21, 1998, and copending Cigaina U.S. application Ser. No.
09/122,832, filed Jul. 27, 1998, both of which are incorporated by
reference in their entirety herein, describe a novel apparatus
wherein the needle is incorporated into the end of the lead. Once
the electrodes are inserted into the viscera, the electrodes are
fixed in place by partially opposing tines.
[0007] The above apparatus and methods of installation generally
incorporate a pair of electrodes for stimulating the tissue. As
illustrated in FIG. 1, a first electrode 1 and a second electrode 2
are implanted in the patient's tissue 3. When electrical
stimulation is applied to the tissue 3, a pulsed electric field 4
propagates outward from the electrodes 1 and 2 in a direction 5
generally perpendicular to the direction 6 of electrode axis,
typical of a directional dipole.
[0008] Under certain circumstances, it may be necessary to provide
electrical pulses that stimulate a greater area of tissue in order
to obtain the desired tissue response and entrainment. For example,
certain patients may benefit from stimulation over a larger area of
tissue. Thus, there is a need to provide an electrode apparatus
that stimulates tissue over a greater area in a more uniform or
omnidirectional fashion.
[0009] Moreover, variations in the stimulation location, direction,
duration, and intensity over time may be beneficial. It is an
advantage of the invention to provide an apparatus and methods of
stimulation wherein the stimulation patterns may be varied over
time.
[0010] It is also an advantage of the invention to provide an
apparatus and methods of stimulation wherein the electrodes may be
implanted in a minimally invasive manner, such as laparoscopically,
which allows substantially equidistant spacing of the
electrodes.
SUMMARY OF THE INVENTION
[0011] These and other objects of the invention are accomplished in
accordance with the principles of the invention by providing
apparatus and methods for attaching such apparatus to neuromuscular
tissue of the viscera, and particularly, the gastrointestinal
tract. The apparatus includes at least four closely spaced
stimulating electrodes electrically connected to a pulse generator
that supplies electrical stimulating pulses to the neuromuscular
tissue. According to a preferred embodiment, an electrode assembly
includes a first electrode-pair attachment member supporting a
first pair of electrodes and a second electrode-pair attachment
member supporting a second pair of electrodes. Each electrode-pair
attachment member includes first and second anchor members that
secure the electrode attachment member and the electrodes in the
tissue. Such anchor members may be a set of resilient tines which
abut the tissue and prevent relative movement with respect
thereto.
[0012] In the most preferred embodiment, the electrode assembly has
a pair of electrode-pair attachment members arranged in parallel,
each having a respective penetrative mechanism and a severable
connecting member for removably attaching the penetration mechanism
to the electrode attachment member. The first electrode-pair
attachment member pierces the tissue with the first penetrative
mechanism and anchors itself at a first location. The second
electrode-pair attachment member pierces the tissue with the second
penetrative mechanism and anchors itself at a second location, and
in a position substantially parallel to the first electrode-pair
attachment member.
[0013] In another preferred embodiment, the electrode assembly has
the two of electrode-pair attachment members arranged in series.
One penetration mechanism is provided and connected to the one of
the first and second electrode-pair attachment members, and a
bridging portion connect the first and second electrode-pair
attachment members. The penetration member allows the first
electrode-pair attachment member to enter at a first location, pass
through, and exit the tissue at a second location, and subsequently
guides the second electrode-pair attachment member to enter and be
anchored at least partially within the issue at the first location.
The first electrode-pair attachment member subsequently enters at a
third location and anchors itself within the tissue, and in a
position substantially parallel to the second electrode-pair
attachment member. The parallel installation of the first and
second attachment members allows the four electrodes to be
substantially equidistant with respect to each other.
[0014] In yet another preferred embodiment, an electrode attachment
member is provided to install four electrodes at the surface of the
neuromuscular tissue. The electrode attachment member supports the
four electrodes at a distal surface thereof and is configured for
attachment to the surface of the neuromuscular tissue to provide an
electrical interface between the electrodes and the neuromuscular
tissue. The electrode attachment member preferably has a
substantially flat distal surface fabricated from a flexible
material. This flexibility allows the distal surface to
substantially conform to any curvature of the neuromuscular
surface. The flexibility also permits the electrode attachment
member to be reduced in size to a compact form by rolling, folding,
etc. The electrode attachment member may be inserted into the
patient while in the compact form through minimally invasive
laparoscopic or similar surgical access openings. A cylindrical
sleeve member or annular bands may be provided to surround the
electrode attachment member to assist in maintaining it in the
compact form.
[0015] Preferred methods for installation in accordance with the
invention include providing an electrode assembly which supports
the four electrodes. A further step may include providing a
surgical access opening in the patient and laparoscopically
introducing the electrode assembly into the patient. A subsequent
step may include attaching the electrode assembly to the
neuromuscular tissue to provide an electrical interface between the
electrode and the tissue.
[0016] Once the electrode assembly has been installed, thereby
orienting the four electrodes to the tissue, it is possible to
begin stimulating the tissue in a novel manner. In a preferred
embodiment, a normal generator is provided to generate the
stimulating pulses, and a switching matrix is provided under
firmware control to control a sequential pair-wise stimulation
sequence.
[0017] The pair-wise stimulation sequences may include a plurality
of options. A first stimulation technique may be a quadrapole
sequence, wherein electrode pairs at diagonally opposite corners
apply a pulse of the same polarity, and adjacent electrodes apply
pulses of opposite polarity. A second stimulation technique may be
a sequential quadrature bipole, wherein stimulation pairs consist
of electrodes at opposite corners that may sequentially stimulate
the tissue. A third stimulation technique may be a sequential
quadrature bipole, wherein stimulation pairs consist of adjacent
electrode pairs that may sequentially stimulate the tissue.
[0018] In a preferred embodiment, the pulse parameters may include
the timing and duration of pulses applied according to one of the
above sequences. In order to vary these parameters during the
treatment period, the neuromuscular stimulator may also include a
real time clock and a programmable calendar for tailoring the
stimulating waveform parameters over the treatment period. The real
time clock supplies data corresponding to the time of day during
the treatment period. The programmable calendar stores parameters
which refer to the shape of the stimulating waveform. Each of the
parameters may be referenced directly or indirectly to the time of
day. Circuitry, such as a control circuit, applies the stimulating
pulses which are defined by the parameters at the appropriate times
of the day during the treatment period.
[0019] The real time clock and the programmable calendar allow the
stimulating waveform to vary over greater periods of time. For
example, the real time clock may supply data corresponding to a
week during the time period. Consequently, the waveform may be
programmed to apply a different waveform during each particular
week in the treatment period. The real time clock may also supply
data corresponding to the day of the week during the treatment
period. Alternatively, the real time clock may supply data
corresponding to a month of the year during the treatment period,
such that the waveform may vary from month-to-month as the
treatment progresses. Moreover, the real time clock may also supply
data corresponding to the day of the month, and/or the day of the
year.
[0020] Although electrode assemblies are illustrated in the form a
pair of elongated bodies or of a patch, certain aspects of the
invention are equally applicable to electrode assemblies having
other shapes and other methods of installation, as well as
alternative four pole stimulation sequences. Briefly summarized,
the present invention relates to approaches and methods for
electrically stimulating neuromuscular tissue of the viscera of the
organ structure, including the gastrointestinal tract by connecting
a plurality of electrodes to at least one organ in the
gastrointestinal tract of a patient connected at a different
location along the peristaltic flow path. Electrical pulses to the
organ are provided from a first set of the plurality of electrodes
and second electrical pulses to the organ are provided from a
second set of electrodes. The electrical pulses provided by the
plurality of electrodes are in an independent non-phased
relationship for maintaining therapeutic regulation of peristaltic
flow through the at least one organ in the gastrointestinal tract
while defeating the body's natural tendency for adaption.
[0021] Further features of the invention, its nature, and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a simplified view of a typical prior art
stimulating electrode pair and associated electric field gradient
pattern.
[0023] FIG. 2 is a simplified view of an apparatus in accordance
with the invention.
[0024] FIG. 3 is a simplified sectional view of a portion of the
apparatus of FIG. 2, illustrating a stage in the installation of
the apparatus in accordance with the invention.
[0025] FIG. 4a is a simplified elevational view of the apparatus of
FIG. 2 and additional apparatus, illustrating a later stage in the
installation of the apparatus in accordance with the invention.
[0026] FIG. 4b is a simplified sectional view of the apparatus of
FIG. 4a, illustrating a later stage in the installation of the
apparatus in accordance with the invention.
[0027] FIG. 5 is a simplified sectional view of the apparatus of
FIG. 2 installed in the patient in accordance with the
invention.
[0028] FIG. 6 is a simplified schematic view of a component of the
apparatus in accordance with the invention.
[0029] FIG. 7a is a simplified schematic view of a component of the
apparatus of FIG. 2 in accordance with an alternative embodiment of
the invention.
[0030] FIG. 7b is a simplified schematic view similar to FIG. 7b in
accordance with another alternative embodiment of the
invention.
[0031] FIG. 8 is a simplified schematic view of a component of the
apparatus of FIG. 2 in accordance with the invention.
[0032] FIG. 9 illustrates a data structure for storing parameters
for the waveform of a stimulating pulse in accordance with the
invention.
[0033] FIG. 10 illustrates another data structure in accordance
with the invention.
[0034] FIG. 11 illustrates yet another data structure in accordance
with the invention.
[0035] FIG. 12 illustrates still another data structure in
accordance with the invention.
[0036] FIG. 13 is a simplified view of the stimulating waveform
propagation provided by the apparatus in accordance with the
subject invention.
[0037] FIG. 14 is a simplified view of an apparatus in accordance
with an alternative embodiment of the invention.
[0038] FIG. 15 is a simplified sectional view of a portion of the
apparatus of FIG. 14, illustrating a stage in the installation of
the apparatus in accordance with the invention.
[0039] FIG. 16a is a simplified elevational view of the apparatus
of FIG. 14 installed in the patient in accordance with the
invention.
[0040] FIG. 16b is a simplified sectional view of the apparatus of
FIG. 16a.
[0041] FIG. 17 is a simplified perspective view of a preferred
embodiment in accordance with the invention.
[0042] FIG. 18 is an elevational view taken from direction 18 of
FIG. 17 of a component of the apparatus in accordance with the
invention.
[0043] FIG. 19 is a simplified sectional view taken from line 19-19
of FIG. 17 of a component of the apparatus in accordance with the
invention.
[0044] FIG. 20 is a simplified view illustrating a stage in the
process of installing the apparatus of FIG. 17 in accordance with
the invention.
[0045] FIG. 21 is a sectional view illustrating the apparatus
installed in accordance with the invention.
[0046] FIG.22 is a view similar to FIG. 21, illustrating an
alternative embodiment in accordance with the invention.
[0047] FIG. 23 is a view of an apparatus according to an alternate
adaption defeating embodiment in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] An improved neuromuscular stimulator is illustrated in FIG.
2, and designated generally with reference number 10. The
stimulator 10 includes an implantable pulse generator 12, a lead
system 14 and an electrode assembly, or implant device 16. The
implantable pulse generator 12 provides a series of electrical
pulses to and/or electrical monitoring of the tissue of the
viscera. It is understood that the viscera may include any organs
of the human torso, and primarily those of the abdominal region.
For example, the principles in accordance with the invention are
applicable to such body organs as the liver, pancreas, and the
gastrointestinal tract (not shown in FIG. 2). Suitable pulse
generators are described in commonly-assigned U.S. Pat. No.
5,423,872 to Cigaina and concurrently-filed Gordon U.S. patent
application Ser. No. 09/466,387, filed Dec. 17, 1999, both of which
are incorporated by reference in their entirety herein. The
implantable pulse generator 12 may be surgically implanted
subcutaneously in the abdominal wall. The electrical stimulation
lead 14 includes a proximal connector end 18 to interface with the
implantable pulse generator 12, a medial lead body portion 20, and
a distal end portion 22, for electrical connection with the
electrode assembly 16.
[0049] According to the preferred embodiment, the electrode
assembly, or implant device, 16 has a bifurcated configuration,
which may include a pair of elongated body portions, such as
substantially identical electrode attachment members 24a and 24b.
Electrode attachment member 24a supports a pair of electrodes A 26
and B 28, and electrode attachment member 24b supports a pair of
electrodes C 30 and D 32.
[0050] Electrodes A 26 and B 28 are spaced apart a distance 34 of
about 0.5 cm to about 2 cm. Similarly, electrodes C 30 and D 32 are
spaced apart a distance 36 of about 0.5 cm to about 2 cm. In a
preferred embodiment, distance 34 and distance 36 are equal. The
electrode assembly 16 may have a bifurcated structure, which is
dimensioned such that the resulting spacings 55 and 57 between
electrodes on opposite electrode attachment members 24a and 24b
after implantation are approximately the same as spacings 34 and
36, thus achieving quadrature symmetry of the four electrodes (see
FIG. 5). This bifurcated structure is preferably achieved by a
bridging portion 25 having a first end portion 23 electrically
connected with the pulse generator 12 and the lead 14, and a pair
of second end portions 27a and 27b, each of which may be connected
to a respective electrode-pair attachment member 24a/24b. Although
FIG. 2 may not necessarily be drawn to scale, second end portions
27a and 27b are preferably dimensioned with sufficient length to
allow the physician to independently install electrode-pair
attachment members 24a and 24b in the tissue.
[0051] Each electrode-pair attachment member 24a and 24b includes
penetration mechanism 38a and 38b to pass through the tissue in
which the electrodes A 26, B 28, C 30, D 32 are desired to be
implanted. Each of penetration mechanisms 38a and 38b may include a
noncutting curved portion 40a and 40b, a noncutting linear portion
41a and 41b, and a distal cutting end portion 42a and 42b. Each
penetration mechanism 38a and 38b is respectively connected to the
electrode attachment member 24a and 24b by a connecting or
"quick-release" mechanism 44a and 44b. Connecting elements 44a and
44b and elongated body portions 24a/24b are preferably formed from
a silicone material, e.g., a surgical-grade silicone or other
biocompatible material having similar stress characteristics.
Connecting elements are manufactured having flexibility
characteristics to permit relative movement of the penetration
mechanism 38a/38b with respect to elongated body portions 24a/24b.
The length of connecting elements are adjusted to permit angling
and flexibility without harming the electrical conduction
components located within the elongated body portions 24a/24b.
Preferably connecting elements 44a/44b are radiopaque, and may be
severed by the physician during the implantation process to
separate the penetration mechanism 38a/38b from the electrode
attachment member 24a/24b. As will be described in greater detail
hereinbelow, a preferred means of severing the connecting members
44a/44b may include the use of endoscopically introduced scalpel or
scissors.
[0052] Electrodes A 26 and B 28 as well as C 30 and D 32 may be
anchored with respect to the patient's tissue by securing
mechanisms, such as securing members 46. Securing members 46 are
preferably fabricated from a biocompatible material, such as, for
example, silicone, and may consist of first tines 48a/48b and
second tines 50a/50b. Generally, both the first 48a/48b and second
tines 50a/50b each define a set of at least two in number;
preferably each set of tines are three to five in number. In the
preferred embodiment, first tines 48a/48b may be leading tines,
that is, tines 48a/48b are preferably flexible and define an obtuse
angle .alpha. with respect to the direction of travel 52. This
configuration aids in the passage of electrode attachment member
24a/24b in the direction 52, while inhibiting movement in the
opposite direction. Preferably, the first tines 48a/48b have a
diameter of about 1 mm and a length of about 3 mm and may enter the
tissue (e.g., at the "entrance" site), may penetrate the thickness
of the tissue to be stimulated, and exit on the opposite side
(e.g., the "exit" site of the tissue). Once through the tissue,
first tines 48a/48b may provide contact with the exit site of the
tissue, and inhibit movement of the electrode attachment member
24a/24b opposite to direction 52.
[0053] Second tines 50a/50b may define an acute angle .beta. with
direction 52. In operation, second tines 50a/50b do not penetrate
the thickness of the tissue to be stimulated. Rather, they may
provide contact with the entrance site of the tissue, and therefore
inhibit movement of electrode positioning member in direction 52.
This configuration is useful in securing electrode attachment
member 24a/24b in the implanted tissue to prevent dislodgement
after installation by locking or anchoring the tissue between first
tines 48a/48b and second tines 50a/50b, as will be described in
greater detail hereinbelow. The distance between the first tines
48a/48b and the second tines 50a/50b may vary as deemed necessary
by the physician, and may depend on the desired distance 34/36
between the electrodes and the thickness of the tissue to be
stimulated. Preferably, the linear portion 41a/41b of penetration
mechanism 38a/38b may have a length that is at least equal to the
distance between first tines 48a/48b and second tines 50a/50b.
[0054] The base materials for the electrodes A 26,18 28 and C 30, D
32 may include any material typically used for electrodes such as,
e.g., stainless steel, platinum, platinum-iridium alloys, iridium
oxide, titanium and the like. The electrodes A 26,18 28 and C 30, D
32 may be in an uncoated state or may be coated with materials such
as iridium oxide or titanium nitride, or the electrodes may be
platinized or carbonized. Each of the conductors A 26,18 28, C 30,
D 32 are respectively electrically connected to a distinct
conductor 52/54/56/58, each of which is connected electrically to
the pulse generator 12 at the proximal end. The conductors may be
surrounded by an electrically insulative material to isolate the
non-common conductors from each other, as necessary, and to isolate
the conductors 52/54/56/58 from the physiological environment. The
lead body 20 may include a plurality of conductive coils (not
shown) isolated within an electrically insulative material such as
silicone elastomer. The lead body 20 may utilize a coaxial or
parallel conductor design. The conductive coils of the lead body
may electrically connect the proximal terminations of the lead 18
to their corresponding distal electrode or electrodes A 26,18 28, C
30, D 32.
Installation of the Preferred Embodiment
[0055] The above-described configuration of the electrodes and
electrode assembly provides for a simple, minimally-invasive
installation procedure in accordance with the invention. According
to an early stage of the invention, the approximate location of the
gastrointestinal tissue is located by the physician. An incision is
made in the patient in the surface of the skin above the operative
site. According to a preferred embodiment, an obturator device may
be used to provide the incision and install a trocar. The process
of insufflation may be used, wherein an inert gas such as carbon
dioxide is introduced under pressure, to enlarge the body cavity
and provide improved visualization and access within the body
cavity. A series of trocars may be installed through the patient's
skin which allow access for surgical instrumentation while
maintaining insufflation pressure. A laparoscope or similar remote
viewing apparatus may be inserted through one of the trocars in
order to allow viewing of the process of attachment of the
electrode assembly to the tissue, such as the stomach tissue, in
this example.
[0056] The electrode assembly 16 is preferably passed through the
trocar in a compacted form. The bridging portion 25 is preferably
flexible, which facilitates the process of placing the electrode
assembly in the compacted form. For example, the electrode
attachment members 24a/24b may be placed in approximation with one
another. The electrode assembly 16 may be contained within a sleeve
that is passed through a trocar. It is contemplated that the sleeve
may be omitted when the electrode assembly is passed through the
trocar or other access opening.
[0057] After trocar passage, the electrode assembly may be freed
from the sleeve by mechanical means. For example, mechanical
grasping apparatus, such as a grasper, may be used to hold the
electrode assembly with grasping jaws to remove the electrode
assembly from an end portion of the sleeve. According to an
alternative embodiment, the electrode assembly is pushed out of the
sleeve by advancing an apparatus, such as a blunt instrument, a
plunger, a blunt dissection device, or a balloon catheter
device.
[0058] A stage of attachment of the electrode assembly to the
tissue follows. The attachment may be achieved in several ways. As
illustrated in FIG. 3, the penetration mechanism 38 passes through
the tissue S. More particularly, distal cutting end portion 42a
pierces the tissue S at entrance site V of the outer stomach wall
in the case of a gastric stimulator and is advanced as indicated by
the arrow. First tines 48a, as described above, are angled to
facilitate passage as shown into the tissue. Tines 48a are
preferably resilient and may deflect towards parallelism with the
electrode attachment member 24a during insertion. Preferably,
forceps, such as endoscopic forceps, may be used by the physician
to advance the electrode mounting member 24a into the tissue. As
illustrated in FIG. 3, cutting end portion 42a preferably enters
the tissue S at entrance site V at an angle to facilitate exiting
the surface N, as will be described in greater detail below.
[0059] As illustrated in FIGS. 4(a) and 4(b), electrode mounting
member 24a is advanced such that connecting member 44a and first
tines 48a pass through the tissue S and subsequently protrude from
the outer surface N at the exit site U of the tissue S.
[0060] Electrode attachment member 24a may be sufficiently flexible
in order to pass the member in the tissue S at location V and
subsequently exit at location U at the same surface N. First tines
48a may resiliently move towards the undeflected position, such as
illustrated in FIG. 2, above, and inhibit movement of electrode
attachment member 24a out of the tissue S. Second tines 50a may be
axially spaced from first tines 48a such that they abut the
entrance site V of the tissue S and inhibit further movement of
electrode attachment member 24a into the tissue S. In this
position, the tissue S is located between the two sets of tines 48a
and 50a. Moreover, the electrode attachment member 24 is
effectively anchored in place by tines 48a and 50a. Electrodes A 26
and B 28 are thus positioned in the tissue S.
[0061] The penetrating mechanism 38 may be separated from the
electrode attachment member 24a by severing the connecting member
44a. Preferably, a cutting instrument, such as endoscopic scissors
54, may be used to sever connecting member 44a. A grasping
mechanism, such as endoscopic graspers 56, may be used to hold
penetrating mechanism during the severing of connecting member 44a,
and during removal thereof from the operative site.
[0062] As illustrated in FIG. 5, the electrode attachment member
24b (illustrated in dashed line) is shown installed in tissue S.
Second end portions 27a and 27b of bridging structure 25 are
sufficiently long to allow the physician to maneuver and install
electrode-pair attachment member 24b in the tissue S with
penetrating mechanism 38b. The installation of electrode attachment
member 24b is performed substantially as described in FIGS. 3-4
with respect to electrode attachment member 24a. First tines 48b
are positioned adjacent the exit site Y of the tissue, and second
tines 50b are positioned adjacent the entrance site Z. Following
installation, electrode attachment member 24b is substantially
parallel to electrode attachment member 24a, and electrodes A 26,18
28 are spaced apart from electrodes C 30, D 32 by substantially
equal distances 55 and 57, such as, 0.5 cm to 2.0 cm, which are
substantially the same distance as distance 34 and 36, shown in
FIG. 2.
[0063] FIG. 6 illustrates a preferred embodiment of circuitry in
pulse generator 12 for applying stimulation pulses to the
electrodes A 26, B 28, C 30, and D 32. In accordance with this
embodiment, each electrode A 26, B 28, C 30, and D 32 is connected
respectively to a lead 52/54/56/58. A typical generator well-known
in the art, such as generator 70, is provided to generate the
electrical pulse stimulation of the electrodes. These pulses are
generated in a predetermined sequence under firmware control as
will be described in greater detail below. Switching matrix 72
receives instructions from generator 70 and applies the stimulating
pulse to the appropriate set of electrodes with appropriate
polarity to stimulate the tissue.
[0064] Each individual switch of matrix 72 is normally open and can
be connected either to the positive or negative output terminals of
the generator or left open during a stimulation pulse as controlled
by the timing sequence processor.
[0065] FIG. 7a illustrates another embodiment of the circuitry in
pulse generator 12. As described with respect to FIG. 6, above,
each electrode A 26, B 28, C 30, and D 32 is respectively connected
to a lead 52/54/56/58. Four triple-pole outputs (corresponding to
open, +polarity, and -polarity) 74/76/78/80 operate under firmware
control of the timing sequence processor 82 on line 83. Voltage
source 84 may be current-controlled or voltage-controlled.
[0066] FIG. 7b illustrates another alternative embodiment of the
circuitry in pulse generator 12. Electrodes A 26 and D 32 are both
connected to a lead 53 on a first conduction path. Similarly,
electrodes B 28 are C 30 are connected to a lead 57 on a second
conduction path. The number of switches may thus be reduced from
four independent switches to a pair of double-pole switches 75a/75b
which operate in tandem to provide a quadrapole.
Stimulation Techniques and Programming
[0067] The generator 70 (FIG. 6) in concert with the timing
sequence processor 83 (FIG. 7) may be programmed to provide
stimulation pulses to the tissue. The variations in pulses allow
the four electrodes, electrode A 26, electrode B 28, electrode C
30, and electrode D 32 to stimulate the tissue individually, and in
any combination. The ability to vary the stimulation applied to
tissue, such as that of the stomach, is important to entrain the
tissue. A characteristic of this tissue, as distinguished from
heart tissue, is that the stomach tissue may become fatigued by
constant stimulation. Thus the ability to change the direction and
intensity of stimulation may prevent or reduce such fatigue. In the
description of the stimulation techniques and sequences which
follows, it is presumed that there are four electrodes which may be
independently controlled to stimulate the tissue. The four
electrodes are substantially equidistantly spaced with respect to
one another, thereby forming a substantially square configuration,
with each electrode located at one of four "corners" (see, e.g.,
electrodes A 26, B 28, C 30, and D 32 in FIG. 5). In order to
simplify the following discussion, the term "adjacent electrode
pairs" shall refer to electrodes located in adjoining corners of
the configuration, e.g., electrodes A 26 and B 28 are adjacent
pairs, and electrodes A 26 and C 30 are likewise adjacent pairs.
The term "diagonal electrode pairs" or "opposite electrode pairs"
shall refer to electrodes located in opposite corners of the
configuration, which are spaced further apart than adjacent pairs.
For example, electrodes A 26 and D 32 are diagonal pairs, and
electrodes B 28 and C 30 are likewise diagonal pairs.
[0068] An option for programming the electrodes is a quadrapole
stimulation configuration. In this case, first diagonal electrode
pairs of electrodes A 26 and D 32 may have a positive voltage,
while second diagonal electrode pairs of electrodes B 28 and C 30
may simultaneously have a negative voltage. Similarly, first
diagonal electrode pairs of electrodes A 26 and D 32 may have a
negative voltage, while second diagonal electrode pairs of
electrodes B 28 and C 30 may simultaneously have a positive
voltage.
[0069] Another option may be a sequential quadrature bipole
configuration. According to this option, a sequence involving two
sets of pulses is defined. A first diagonal electrode pair is
defined by electrodes positioned diagonally opposite to each other,
e.g., electrode A 26 and electrode D 32 defining a first diagonal
electrode pair and electrode B 28 and electrode C 30 defining a
second diagonal electrode pair. During the first set of pulses in
the sequence, electrical stimulation is applied across the first
diagonal electrode pair, i.e., electrode A 26 applies a positive
pulse and electrode D 32 simultaneously applies a negative pulse.
During the second set in the sequence, electrical stimulation is
applied across the second diagonal electrode pair, i.e., electrode
B 28 applies a positive pulse and electrode C 30 applies a negative
pulse. Typically, this sequence of two sets of pulses may be
repeated several times during the treatment period. A variation of
the above sequential quadrature bipole sequence may involve four
sets of pulses in the sequence. The first and second sets of pulses
in the sequence, are the same as described above, i.e., in the
first set of pulses applied across the first diagonal electrode
pair, electrode A 26 is positive and electrode D 32 is negative;
and during the second set applied across the second diagonal
electrode pair, electrode B 28 is positive and electrode C 30 is
negative. During the third set of pulses in the sequence,
electrical stimulation is applied across the first diagonal
electrode pair such that electrode D 32 is now positive and
electrode A 26 is simultaneously negative. During the fourth set in
the sequence, electrical stimulation is applied across the second
diagonal electrode pair such that electrode C 30 is positive and
electrode B 28 is negative. This sequence of four sets of pulses
may be repeated several times during the treatment period.
[0070] Another alternative option with regard to applied pulses is
a sequential semi-quadrature bipole. This option is a sequence of
four steps of applied pulses. In the first step, electrical
stimulation is applied across a first adjacent electrode pair such
that electrode A 26 is positive and simultaneously electrode B 28
is negative. In the second step, electrical stimulation is applied
across a second adjacent electrode pair such that electrode B 28
switches to positive and simultaneously electrode D 32 is negative.
During the third step, electrical stimulation is applied across a
third adjacent electrode pair such that electrode D 32 switches to
positive and simultaneously electrode C 30 is negative. During the
fourth step, electrical stimulation is applied across a fourth
adjacent electrode pair such that electrode C 30 switches to
positive, and electrode A 26 is negative. The sequence of four
steps may be repeated during treatment. An alternative sequential
semi-quadrature bipole sequence also involves four steps in the
sequence. In the first step, electrical stimulation is applied
across a first adjacent electrode pair such that electrode A 26 is
positive and simultaneously electrode B 28 is negative. In the
second step, electrode B 28 remains negative and simultaneously
electrode D 32 is positive. During the third step, electrode D 32
remains positive and simultaneously electrode C 30 is negative.
During the fourth step, electrode C 30 remains negative, and
electrode A 26 is positive. This sequence may also be repeated
during the treatment.
[0071] The above-described sequences, i.e., quadrapole, sequential
quadrature bipole, and the sequential semi-quadrature bipole, all
utilize the placement of four electrodes in the tissue, and the
ability to vary the placement and polarity of the pulses. In
addition, another parameter that may be varied is the pulse timing
scheme, which concerns the duration in which the sequences are
applied to the tissue. According to one timing scheme, pulses
having a 40 Hz (25 milliseconds) interval are applied in a burst
lasting approximately 2 seconds. According to a second timing
scheme, a train of pulses is applied, wherein the pulses are closer
than the 40 Hz interval pulse train described above.
[0072] According to a third timing scheme, each step in the
sequence is applied and held for a specified duration, separated by
a specified duration in which no stimulating pulses are applied. A
typical timing sequence may involve a two-second period in which
pulses may be applied, and a three-second period in which no pulses
are applied. For example, for the sequential quadrature bipole
sequence, electrode A 26 is positive and electrode D 32 is negative
for a two second interval of pulses. No pulses are applied for
three seconds, and then electrode B 28 is positive and electrode C
30 is negative for a subsequent two second interval of pulses. An
additional three second period follows in which no pulses are
applied, and the sequence may repeat.
[0073] The fourth timing scheme allows a great deal of flexibility
wherein both the sequence type and the duration of specific steps
may vary over the treatment period. Timing features and data
structures for storing pulse parameters are described in Gordon
U.S. patent application Ser. No. 09/466,387, filed Dec. 17, 1999,
which is incorporated by reference in its entirety herein. The
timing features of generator 12 are illustrated in FIG. 8. By using
a crystal 92 to control oscillator 94 (which may be either internal
component of processor 96 or a separate component), accuracy is
achieved by a real-time clock counter 98. Typically, a 32 or 100
kilohertz crystal clock may be used to provide timing. Stimulation
pulse width is typically 100 to 500 microseconds (10 to 50
oscillations of 100 kilohertz clock), and the pulse interval may be
25 milliseconds or 2500 clock oscillations. The "on time," i.e.,
the period in which the pulses are applied, may be two seconds
(200,000 oscillations) for this waveform, and the "off time," i.e.,
the period in which no pulses are applied, may be three seconds. It
is useful to synchronize time inside the processor 96. A
programmable storage device, such as programmable calendar 100, can
be programmed to store the parameters that define the above pulse
train. The parameters are output on line 97 for use by the
generator 70 (FIG. 6) or the timing sequence processor 82 (FIG. 7)
or control circuit in determining the wave shape of the stimulating
pulse. The parameters correspond to particular times during the
treatment. Medical observations suggest that food intake, digestion
and other gastrointestinal functions are circadian, that is, they
operate on a 24 hour daily cycle. There are certain periods during
the day when gastric functions are less active than other times of
the day. The programmable calendar 100 can therefore provide
increased stimulation at certain hours of the day, and decreased
stimulation at other hours of the day. Among other benefits, device
longevity may be increased due to the energy saving of this
programming. Thus the electrode assembly 16 may deliver stimulation
pulses for a fraction of each hour while the patient is awake. The
programmability of calendar 100, described below, allows the
application of longer-term circadian variations which may likewise
be beneficial to the patient and extend battery life.
[0074] A plurality of pulse train parameters may be stored in
memory associated with the programmable calendar 100. Sample data
110 for a treatment period is shown in FIG. 9. The data 110 may be
for a 24-hour period, such as "day one" 112, which may include
calendar information 114. The pulse trains may be stored as cycles
116. For example, pulse train parameters may include start times
118, stop times 120, the pulse width 122, the pulse interval 124,
the duration of the applied pulses (the "on" period) 126, or the
duration period in which no pulses are applied (the "off" period)
128, and the voltage of the pulse or the pulse height 130. The
polarity of each of the electrodes A 26, B 28, C 30 and D 32 may be
specified, as fixed polarities, or alternatively as a sequence of
polarities, during this interval. As shown in FIG. 9, electrode A
26 may be designated with a positive polarity 132, electrode D 32
may be designated with a negative polarity 138, and electrodes B 28
and C 30 may be inactive during this cycle, data points 134 and
136. The programmable calendar 100 receives data from the clock 98
concerning the time-of-day and the date. Programmable calendar 100
can obtain the associated parameters from the data 110 and supply
them to the processor 96, accordingly. The "date" associated with
the treatment may vary, depending on the expected duration of the
treatment. For example, in data format 140 (FIG. 10), the data may
correspond to the day of week (e.g., "day one" 142 through "day
seven" 144). Each of the data structures for day one 142 through
day seven 144 may be similar to data 110. The programmable calendar
100 may function on a seven-day cycle wherein programmable calendar
accesses day one after day seven in a continuous loop 146. Thus,
each day of the week could have a particular sequence of
stimulating pulse train parameters. As a result, the pulse train is
programmed to stimulate the stomach tissue in the same way on the
same day of each week.
[0075] As illustrated in FIG. 11, the data format 150 may refer to
a simple, numbered day in a periodic sequence of days, such as the
numbered days of the year (i.e., "day one" 152 through "day 365"
154), or the numbered days within a month (e.g., "day one" through
"day 31", not shown). The calendar 100 would then cycle back to the
first data point as indicated by arrow 156. As illustrated in FIG.
12, the data format 160 may be hierarchical and thus may recognize
intermediate time periods, such as weeks 162 and/or months (not
shown) within a treatment period. For example, it may recognize
that the treatment is at "week two" 164 or "week three" 166, in
addition to the elapsed number of days. The calendar 100 could be
programmed to so that the pulse generator 10 is turned off for a
number of weeks. The generator may then be turned on one day a
week. During the next week, the generator may be turned on for two
days a week, etc. Each sequence of cycles (see FIG. 9) within a
given "on" day, could also be different from the previous "on"
day.
[0076] FIG. 13 illustrates the propagation of stimulation waves
provided by placement of electrodes A 26, B 28, C 30, and D 32 in
the tissue. The tissue stimulation 180 propagate generally radially
outwardly, e.g., directions 182/184/186/188, from the electrodes.
In contrast with the substantially one-dimensional propagation (see
FIG. 1) of the prior art, the electrodes in accordance with the
invention generate stimulating pulses which cover a larger area of
tissue. This may result in better entrainment of muscle tissue
stimulated thereby. Moreover, the sequential stimulation of
electrodes A 315, B 317, C 319 and D 321, e.g., the quadrapole,
sequential quadrature bipole, or sequential semi-quadrature bipole
sequences described above, may be used to vary the direction of the
stimulation, e.g., propagation in directions 182 and 184, followed
by propagation in directions 186 and 198. This may be helpful to
stimulate tissue which responds to stimulation in preferred
directions.
Alternative Embodiment
[0077] An alternative embodiment of the neuromuscular stimulation
electrode system is illustrated in FIG. 14, and designated
generally with reference number 200. The stimulator 200 is
substantially similar to stimulator 10 with the differences noted
herein, and includes an implantable pulse generator 212, a lead
system 214, and an electrode assembly 216. The electrical
stimulation lead 214 includes a proximal connector end 218 to
interface with the implantable pulse generator 212, a medial lead
body portion 220, and a distal end portion 222, for electrical
connection with the electrode assembly 216.
[0078] According to the alternative embodiment, the electrode
assembly 216 does not have the bifurcated configuration of
electrode assembly 16, having electrode attachment members 24a/24b
in parallel (FIG. 2). In contrast, electrode assembly 216 may
include a pair of substantially identical electrode attachment
members 224a and 224b arranged in a series configuration. A
bridging portion 225 may connect electrode attachment member 224a
with electrode attachment member 224b. Bridging portion 225 is not
necessarily represented to scale; however, it is understood that
bridging portion 225 is sufficiently long to permit the physician
to maneuver and install electrode-pair attachment members 224a and
224b, as described in greater detail hereinbelow. Moreover,
electrode assembly 216 includes a single penetration mechanism 238
to pass through the tissue in which the electrodes A 226, B 228, C
230, D 232 are desired to be implanted. Penetration mechanism 238
may include a curved portion 240 and a distal cutting end portion
242. Penetration mechanism 238 is connected to the electrode
attachment member 224a by a connecting member 244, substantially
identical to connecting member 44 (FIG. 2).
[0079] Electrodes A 226 and B 228, and electrodes C 230 and D 232
may be anchored with respect to the patient's tissue by securing
members 246. Securing members 246 substantially similar to securing
members 46 may consist of first tines 248a/248b and second tines
250b. In the preferred embodiment, first tines 248a/248b may be
leading tines, that is, tines 248a/248b define an obtuse angle with
respect to the direction of travel 252 and 253, respectively. This
configuration aids in the passage of electrode attachment member
224a in the direction 252 and electrode attachment member 224b in
the direction 253, while inhibiting movement in the opposite
direction.
[0080] Second tines 250b may define an acute angle with direction
253. In operation, second tines 250b do not penetrate the thickness
of the tissue to be stimulated, but may provide contact with the
entrance site of the tissue, and therefore inhibit movement of
electrode positioning member in direction 253. In the preferred
embodiment, the second tines may be omitted from electrode
attachment member 224a. As will be described in greater detail
below, electrode attachment member 224a passes through tissue
twice. Therefore, second tines, which generally remain at the
entrance side of the tissue as described above, would inhibit the
passage of electrode attachment member 224a entirely though the
tissue or may cause tearing or other injury to the tissue.
Consequently, second tines may be omitted from electrode attachment
member 224a. If it desired to provide additional anchoring to the
tissue, an anchor sleeve 251 may be provided. Anchor sleeve
preferably is a frusto-conical portion attached to electrode
attachment member 224a at its smaller end portion. It extends
radially outward from electrode attachment member 224a may be
typically oriented at an acute angle with respect to the direction
of travel 252. In this orientation, anchor sleeve 251 provides
resistance to movement of electrode attachment member 224a in
direction 252. Anchor sleeve 251 is preferably resilient. Anchor
sleeve 251 has the ability to flip "inside-out" towards parallelism
with the electrode attachment member 224a in response to a
predetermined contact force of the electrode attachment member with
the tissue 5, allowing relative movement of the electrode
attachment member 224a in direction 252 through tissue, and to
subsequently resiliently return to the position illustrated in FIG.
14.
[0081] As described above with respect to conductors 52/54/56/58,
each of the electrodes A 226, B 228, C 230, and D 232 are
respectively electrically connected to a distinct conductor
252/254/256/258, each of which is connected electrically to the
pulse generator 212 at the proximal end. Alternatively, the
electrodes may be connected via two conductors to the generator
212, to create a permanent quadrapole.
Installation of the Alternative Embodiment
[0082] The stimulator 200 is installed substantially as described
above with respect to FIGS. 3-5 in a simple, minimally-invasive
installation procedure. According to an early stage of the
invention, the approximate location of the gastrointestinal tissue
is located by the physician. An incision is made in the patient in
the surface of the skin above the operative site. A series of
trocars may be installed through the patient's skin which allow
access for surgical instrumentation while maintaining insufflation
pressure. The electrode assembly 216 may be contained within a
sleeve that is passed through a trocar. It is contemplated that the
sleeve may be omitted when electrode assembly is passed through the
trocar or other access opening. After trocar passage, the electrode
assembly may be freed from the sleeve by mechanical means.
[0083] A stage of attachment of the electrode 216 assembly to the
tissue follows. The attachment may be achieved in several ways. As
illustrated in FIG. 15, the penetration mechanism 238 passes
through the tissue S. More particularly, distal cutting end portion
242 pierces the tissue S at the outer surface N at entrance site V
and is advanced as indicated by the arrow. First tines 248a, as
described above, are angled to facilitate passage as shown into the
tissue. Tines 248a are preferably resilient and may deflect towards
parallelism with the electrode attachment member 22/1a during
insertion. Preferably, forceps, such as endoscopic forceps, may be
used by the physician to advance the electrode attachment member
224a into the tissue.
[0084] As electrode attachment member 224a is further advanced
through tissue S, anchor sleeve 251 abuts the tissue at entrance
side V. (The initial configuration of anchor sleeve 251 is
illustrated in dashed line.) Upon further advancement of sleeve 251
into tissue S with increased contact force applied by the
physician, anchor sleeve 251 resiliently flips into a backwardly
oriented configuration towards parallelism with electrode
attachment member 22/1a as indicated by the pair of curved arrows
(this backward configuration is illustrated in solid line in FIG.
15).
[0085] While in this backward facing configuration, electrode
attachment member 22/1a may be advanced through the tissue such
that electrode attachment member 22/1a exits the surface N of the
tissue S at exit site U. Further advancement allows bridging
portion 225 to exit the tissue S at exit site U. First tines 248b
pass through the tissue S until electrodes C 230 and D 232 are
positioned in tissue S, as illustrated in FIGS. 16(a) and 16(b).
Penetrating mechanism 238 is positioned such that cutting end
portion 242 may pierce the tissue at the surface N at entrance site
Y. Advancement of electrode positioning member 22/1a allows first
tines 248a to pass through the tissue S until electrodes A 226 and
B 228 are positioned in tissue S, and penetration mechanism 238 and
first tines 248a pass through the tissue S at exit site Z. Anchor
sleeve 251 returns to its forward facing configuration to anchor
electrode attachment member 22/1a between first tines 248a and
anchor sleeve 251. Penetration mechanism 238 may be removed from
electrode assembly 216 by severing connecting member 244, as
described above with respect to FIG. 4.
Second Alternative Embodiment
[0086] Another alternative embodiment of a neuromuscular stimulator
is illustrated in FIG. 17, and designated generally with reference
number 300. The stimulator apparatus and method of installation are
substantially described in Jenkins U.S. patent application Ser. No.
09/466,532, filed Dec. 17, 1999, which is incorporated by reference
in its entirety herein. The stimulator 300 includes an implantable
pulse generator 312, a lead system 314 and an electrode assembly
316. The implantable pulse generator 312 provides a series of
electrical pulses to the neuromuscular tissue of the viscera. The
electrical stimulation lead 314 includes a proximal connector end
318 to interface with the implantable pulse generator 312, a medial
lead body portion 320, and a distal end 322, for electrical
connection with the electrode assembly 316.
[0087] Four electrodes, i.e., "electrode A" 315, "electrode B" 317,
"electrode C" 319, and "electrode D" 321 are installed in contact
with the surface of the stomach tissue, or other viscera. In a
preferred embodiment, the electrodes A 315, B 317, C 319, and D 321
are supported by an electrode attachment member 324, which may be
attached to the stomach by sutures or staples. As will be described
in greater detail below, the electrodes A 315, B 317, C 319, and D
321 and electrode attachment member, or patch 324 may be inserted
to the body cavity laparoscopically through a trocar or other
minimally invasive surgical access opening to fit through the
restrictive diameter of the trocar, patch 324 is preferably made
from a flexible material so it can be folded during passage through
the trocar.
[0088] As illustrated in FIGS. 18 and 19, the stimulation
electrodes A 315, B 317, C 319, and D 321 and the electrode
attachment member, such as patch 324, are adjacent the distal end
portion 322 of the lead 314. The stimulation electrodes may be
fabricated from a metallic or other conductive material, attached
to or partially embedded within the patch 324. The electrodes are
exposed at the distal surface 326 of the patch 324, which may be
attached to the surface of the tissue being stimulated.
[0089] The patch is provided with substantially flat distal surface
326, which will generally refer to the configuration of the surface
as relatively broad in relation to the thickness 328 or depth of
the patch 324 as a whole. In a preferred embodiment, patch 324 has
a diameter of, for example, about 1 to 3 cm and a thickness of, for
example, about 3 to 5 mm. The distal surface 326 may be, e.g.,
substantially planar, curved (e.g., convex, concave, or another
appropriate curvature). Alternatively, the distal surface 326 may
be flexible to conform to the surface of the tissue to which it is
to be attached, etc. The electrodes A 315, B 317, C 319, and D 321
are supported by the patch 324, and positioned adjacent the distal
surface 326 in order to provide an electrical interface between the
electrodes A 315, B 317, C 319, and D 321 and the surface of the
tissue being stimulated. The interface, e.g., the interface surface
area, between the electrodes and the tissue being stimulated is
sufficient to allow for the use of a low impedance stimulation.
Each electrode may be of a shape suitable for providing this
surface area.
[0090] The patch 324 may be constructed from a flexible material,
such as, e.g., silicone elastomer or similar material. The base
materials for the electrode 16 may include, e.g., platinum,
platinum-iridium alloys, titanium, and the like. The electrodes A
315, B 317, C 319, and D 321 may be in an uncoated state or may be
coated with materials such as iridium oxide or titanium nitride, or
the electrodes may be platinized or carbonized. In a preferred
embodiment, the patch has a substantially circular configuration.
It is understood that patch 324 may be fabricated in any suitable
configuration, such as, for example, oval, square, rectangular,
etc. The electrodes 315/317/319/321 may be distributed around the
distal surface 326 substantially equidistantly from the center of
the distal surface 326. For example, if an array of electrodes is
being used for multiple stimulation vectors, and eccentric
placement of the electrodes may be preferred to phase the
stimulating pulses, and consequently the contractions. The
arrangement of the patch 324 supporting electrodes A 315, B 317, C
319, and D 321 provides an advantage to the physician in that the
orientation of the electrodes with respect to one another, i.e.,
equidistant, is fixed prior to installation. Therefore, the
physician is spared the task of installing individual electrodes,
thereby reducing the time required for electrode installation.
[0091] With continued reference to FIG. 19, the implantable
electrical stimulation lead 314 includes a plurality of distinct
conductors 330, each of which is connected electrically to a
corresponding electrode or electrodes A 315, B 317, C 319, and D
321 on the distal end. Alternatively, two conductors may be
provided in the lead. This configuration may be used to connect the
four electrodes to provide a permanent quadrapole, for example, as
illustrated in FIG. 7b. The conductors may be surrounded by an
electrically insulative material 332 to isolate the non-common
conductors from each other, as necessary, and to isolate the
conductor 330 from the physiological environment. In a preferred
embodiment, the portion 322 may be configured with an angled
portion 323, wherein the lead may be initially oriented
perpendicular to the distal surface 326 of electrode attachment
member 324 and subsequently be oriented substantially parallel to
the surface 326. This configuration facilitates laparoscopic
installation, as described above. The lead body 320 may include a
plurality of conductive coils (not shown) isolated within an
electrically insulative material such as silicone elastomer. The
lead body 320 may utilize a coaxial or parallel conductor design.
The conductive coils of the lead body shall electrically connect
the proximal terminations of the lead to their corresponding distal
electrode or electrodes 316.
[0092] With continued reference to FIG. 18, the patch 324 is
constructed to allow attachment to the surface of the tissue being
stimulated. In a preferred embodiment, the patch material is
selected to allow sutures or staples to pass directly therethrough
to permit the attachment to the tissue. Alternatively, it is
contemplated that the patch may be provided with a plurality of
pre-formed openings or apertures (not shown) to permit the passage
therethrough of sutures or staples.
[0093] According to the preferred embodiment, the patch is
flexible. The flexibility of the patch permits the patch to be
reduced to a compact form by rolling or folding. The patch 324 may
be inserted in a compact form into a patch holder, such as an
introduction sleeve.
Installation of the Second Alternative Embodiment
[0094] The above-described configuration of the electrodes and
electrode attachment member provides for a simple,
minimally-invasive installation procedure in accordance with the
invention. According to an early stage of the invention, the
approximate location of the gastrointestinal tissue is located by
the physician. An incision is made in the patient in the surface of
the skin above the operative site. According to a preferred
embodiment, an obturator device may be used to provide the incision
and install a trocar. The process of insufflation may be used,
wherein an inert gas such as carbon dioxide is introduced under
pressure, to enlarge the body cavity and provide improved
visualization and access within the body cavity. A series of
trocars may be installed through the patient's skin which allow
access for surgical instrumentation while maintaining insufflation
pressure. A laparoscope or similar remote viewing apparatus may be
inserted through one of the trocars in order to allow viewing of
the process of attachment of the electrode attachment member to the
surface of the tissue, such as the stomach tissue 5, in this
example.
[0095] The electrode attachment member, e.g., patch 324 is provided
in compact form in the introduction sleeve. In the case of the
electrodes positioned on the elongated electrode attachment member
224, the patch could be contained to a width of 1 cm or less. The
distal patch 324 within a sleeve is passed through a trocar. It is
contemplated that the sleeve may be omitted when patch 324 is
passed through the trocar or other access opening.
[0096] After trocar passage, the patch 324 may be freed from the
sleeve by mechanical means. For example, mechanical grasping
apparatus, such as a grasper, may be used to hold the patch with
grasping jaws to remove the patch 324 from an end portion of the
sleeve.
[0097] The patch 24 is returned to its open, uncompacted form, as
illustrated in FIG. 20. The grasper 670 may be used to position the
patch 324 adjacent the surface of the viscera S of the stomach.
More particularly, the distal surface 326 of the patch 324 is
placed adjacent the tissue such that the exposed portions of the
electrodes A 315, B 317, C 319, and D 321 are near the surface of
the viscera in order to provide an electrical interface between the
electrodes and the surface of the gastrointestinal tissue. The
interface is sufficient to allow for a low impedance stimulation.
Typical impedances may range from about 300 to 800 ohms, with
stimulating voltages in the range of 2.5 to 5.0 volts and
stimulating currents in the range of about 4 to 6 milliamps. The
voltages and currents are dependent upon the stimulating pulse
widths and frequency.
[0098] Attachment of the patch to the viscera may be achieved in
several ways. As illustrated in FIG. 20, a stapling apparatus, such
as endoscopic stapler or suture applying apparatus 680, may be
used. Stapler 680, as is known in the art, may be sized and
configured for insertion through the trocar or other minimally
invasive surgical access opening, and remotely actuable by the
physician. The stapler 680 applies at least one or more staples or
sutures 682 to attach the patch to the viscera. The installed patch
324 is illustrated in FIG. 21. Distal surface 326 is illustrated in
a substantially planar configuration. However, because patch 324
may be flexible, the distal surface 326 may curve to conform to the
surface of the viscera S.
[0099] FIG. 22 illustrates an alternative embodiment of the
apparatus in accordance with the invention. Electrode assembly 416
is substantially identical to electrode attachment member 316
described above with respect to FIGS. 17-20, with the differences
noted herein. In particular, electrode assembly 416 is provided
with a corkscrew-type attachment member 450. The corkscrew 450 may
be easily applied to the tissue by rotating the electrode assembly
416 with respect to the tissue. According to this embodiment, the
angled portion, referred to as angled portion 323 of apparatus 300,
may be omitted from lead 414 in order to facilitate the rotational
mounting of electrode assembly 416. Alternatively, the corkscrew
attachment member may be used to directly pierce the tissue S with
rotation, such that the concentric rings of the corkscrew
attachment member 450 provide sufficient anchoring against removal
of the electrode assembly 416 from the tissue S.
Alternate Adaption Defeating Embodiment
[0100] With reference to FIG. 23, another alternative embodiment of
a neuromuscular stimulator utilizes the described real-time clock
and calendar functionality to assist in defeating the body's
natural tendency for adaption. Although, at first an electrical
stimulation may produce very good results, over time the body
"adapts" so that therapeutic results are no longer achieved. By
changing the electrical stimulation parameters on a periodic basis,
the body's stimulation input is constantly changing, and hence, the
body cannot adapt. Therefore, it would be desirable if the
implantable stimulator could make this change automatically, so
that the patient does not have to visit the doctor. While the
patient could have a patient programmer, to make parameter changes
on a periodic basis, this would be less desirable, as there would
be no record of the patient input, compliance could be poor (the
patient may not program any changes), or the patient could put in
parameters which are not therapeutic. Thus, the above-described
calendar and time clock capabilities make possible systems and
methods implementing an automatic change in stimulation parameters
on a periodic basis. As a further enhancement to automatic
selectable algorithms for defeating adaption, devices and methods
should allow for two or more sets of electrodes that could be
attached at different locations on the neuromuscular tissue of the
viscera of the organ structure, including the gastrointestinal
tract.
[0101] For example, one of a plurality of electrode sets could be
on and one off, for the duration of, e.g., one month, and then this
could be switched for another month, and, in a third month, maybe
both could be on at the same time. The switching of on-off between
electrodes, or sets of electrodes, can be triggered by the time
clock. In addition, a real-time clock allowing a trigger for on and
off modes, the time clock could also allow for a trigger to change
parameters. Such parameters that could be changed are pulse width,
amplitude, duty cycle (amount of time of pulse and time between
pulses, or series of pulses), frequency, polarity, choice of
unipolar versus bi-polar, and electrode on-off.
[0102] The IGS stimulator 400 of FIG. 23 is substantially similar
to stimulator 10 with the differences noted herein, and includes an
implantable pulse generator 412, a lead system 414, and an
electrode assembly 416. The electrical stimulation lead 414
includes a proximal connector end 418 to interface with the
implantable pulse generator 412, a medial lead body portion 420,
and a distal end portion 422, for electrical connection with the
electrode assembly 416.
[0103] According to the alternative embodiment, the electrode
assembly 416 includes a plurality or a multiplicity of pairs of
substantially identical electrode attachment members 424a, 424b,
424c, and 424d arranged in a series configuration positioned at
various different locations along the neuromuscular tissue of the
viscera of the organ structure, including the gastrointestinal
tract. A bridging portion 425 may connect electrode attachment
member 424a with electrode attachment member 424b. The electrode
assembly 416 includes a single penetration mechanism 438 to pass
through the tissue in which the electrodes A 426, B 427, C 428, D
429, E 430, F 431, G 432, H 433 are desired to be implanted.
Penetration mechanism 438 is connected to the electrode attachment
member 424a by a connecting member 444.
[0104] The penetration mechanism 438 may include a curved portion
440 and a distal cutting end portion 442. Electrodes A 426 and B
427, electrodes C 428 and D 429, electrodes E 430 and F 431, and
electrodes G 432 and H 433 may be anchored with respect to the
patient's tissue by securing members 446. Securing members 446
substantially similar to securing members 46 may consist of first
tines 448a/448b/448c/448d and second tines 450a/450b. The first
tines 448a/448b/448c/448d may be leading tines, that is, tines
448a/448b/448c/448d define an obtuse angle with respect to the
direction of travel 452 and 453, respectively. This configuration
aids in the passage of electrode attachment members
424a/424b/424c/424d in the direction 452 and electrode attachment
members 424a/424b/424c/424d in the direction 453, while inhibiting
movement in the opposite direction. Second tines 450b may define an
acute angle with direction 453. In operation, second tines 450b do
not penetrate the thickness of the tissue to be stimulated, but may
provide contact with the entrance site of the tissue, and therefore
inhibit movement of electrode positioning member in direction 453.
If it desired to provide additional anchoring to the tissue, an
anchor sleeve 451 may be provided.
[0105] The electrodes 426-433 are separated over a sufficient
length such that they can be connected at different locations,
positioned along the curvature of a human stomach. Thus the
electrodes 426-433 can be implanted on different organs which
require peristaltic flow of material, e.g., stomach, colon,
intestines, bowels, etc., from which the pacemaker can control
different electrodes implanted on different organs. In the
configurations contemplated, the use of plural or multiple
electrodes positioned at multiple sites either on the same organ or
on different organs facilitates the enhanced performance discussed
herein. The responses of different patients to different electrical
stimuli may be adjusted. The response of an organ in the
gastrointestinal tract to different electrical stimulations at
different regions of an organ may also be monitored such that the
appropriate program algorithm may be implemented in software for
use with the pacemaker for stimulation in independent non-phased
modes of operation for maintaining therapeutic regulation while
defeating the body's natural tendency for adaption.
[0106] By using a crystal controlled oscillator (which may be
either internal component of the information processor (CPU 44) or
a separate component), accuracy is achieved by a real-time clock
counter 46. Typically, a 32 to 100 kilohertz crystal clock may be
used to provide timing. Stimulation pulse width is typically 100 to
500 microseconds (10 to 50 oscillations of 100 kilohertz clock),
and the pulse interval may be, e.g., 25 milliseconds or 2500 clock
oscillations. It is useful to synchronize time inside the
processor. The variations in pulsing algorithms allow the eight
electrodes, e.g., electrodes A 426, B 427, C 428, D 429, E 430, F
431, G 432, H 433, to stimulate the tissue individually, and in any
combination. The ability to vary the stimulation applied to tissue,
such as that of the stomach, is important to entrain the tissue.
The characteristic of the stomach tissue addressed herein is that
such neuromuscular tissue may become adapted to constant
stimulation due to the body's natural tendency toward adaption.
Thus the ability to change the location, direction, and intensity
of stimulation may prevent adaption. Consequently, the waveform may
be programmed to apply differing waveforms and/or at differing
locations during each particular week in the treatment period. The
real time clock may also supply data corresponding to the day of
the week during the treatment period. Alternatively, the real time
clock may supply data corresponding to a month of the year during
the treatment period, such that the waveform may vary from
month-to-month as the treatment progresses. Moreover, the real time
clock may also supply data corresponding to the day of the month,
and/or the day of the year.
[0107] The electrode switching circuitry and the software
algorithms establish the function of each electrode and the
polarity of the electrode. The switching circuitry is controlled by
the microprocessor CPU 44 and is programmable. In the preferred
embodiment, the electrode switching circuitry will enable a pair of
electrodes to be used for sensing, and a pair or pairs of
electrodes to be used for stimulation. The stimulation and sensing
may utilize the same electrodes. During the stimulation period, the
electrode switching circuitry can change the polarity of the
stimulation electrodes to create multi-phasic pulses, alternating
polarity between pulses or a series of pulses, and different
stimulation vectors. Likewise, the switching circuitry can enable
different pairs of sensing electrodes to sample gastric electrical
activity at various sensing locations or along different vectors.
Complex sensing patterns can be invoked to differentiate slow wave
propagation direction and intervals. Complex switching schemes and
various pulsing algorithms can be stored in memory and be activated
as a program. The switching software would be designed to ensure
that each configuration would have at least one bipolar pair to
complete the electrical circuit.
[0108] The memory is used to store information and programs for the
IGS stimulator 400. The memory receives the sensed information
about the intrinsic gastric activity from the microprocessor,
analyzes that information to determine if the activity is normal
according to a selected algorithm(s), and provides that analysis
output to the microprocessor to initiate the therapy in accordance
with the particular programming selected. Multiple programs may be
stored in memory to establish specific profiles of IGS stimulator
400 activation, response, and performance. The memory may also be
used to store various parameters that indicate device performance,
gastric activities, and therapies administered.
[0109] The foregoing is merely illustrative of the principles of
this invention and various modifications can be made by those
skilled in the art without departing from the scope and spirit of
the invention.
* * * * *