U.S. patent application number 16/782809 was filed with the patent office on 2020-06-04 for parasympathetic activation by vagus nerve stimulation.
The applicant listed for this patent is United States Government as Represented by the Department of Veterans Affairs. Invention is credited to Raymond Dieter, Scott Sayers, Sanjay Singh, Donald Thomas, JAMES WALTER.
Application Number | 20200171310 16/782809 |
Document ID | / |
Family ID | 55163798 |
Filed Date | 2020-06-04 |
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United States Patent
Application |
20200171310 |
Kind Code |
A1 |
WALTER; JAMES ; et
al. |
June 4, 2020 |
PARASYMPATHETIC ACTIVATION BY VAGUS NERVE STIMULATION
Abstract
The vagus nerve and branches of the vagus nerve are stimulated
below the laryngeal nerve branch bifurcation in order to induce
desired parasympathetic responses, such as decreased heart rate,
without also triggering any adverse sympathetic responses.
Stimulating surfaces of an open field bipolar electrode are
positioned on or inserted through the pleural membrane overlying
the vagus nerve at a location having substantially no cardiac
sympathetic fibers adjacent to the vagus nerve. The open field
bipolar electrodes can be securable-wire, needle, plate, or any
other type of electrode suitable for being secured to the pleural
membrane using one or more fastening mechanisms. Electrical stimuli
are generated by a stimulator connected to the stimulating surfaces
of the open field bipolar electrode by one or more leads.
Inventors: |
WALTER; JAMES; (Oak Park,
IL) ; Thomas; Donald; (Salinas, CA) ; Sayers;
Scott; (Hinsdale, IL) ; Singh; Sanjay;
(Oakbrook Terrace, IL) ; Dieter; Raymond; (Glen
Ellyn, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United States Government as Represented by the Department of
Veterans Affairs |
Washington |
DC |
US |
|
|
Family ID: |
55163798 |
Appl. No.: |
16/782809 |
Filed: |
February 5, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15328386 |
Jan 23, 2017 |
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PCT/US15/41839 |
Jul 23, 2015 |
|
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16782809 |
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62028108 |
Jul 23, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/36175 20130101;
A61N 1/0558 20130101; A61N 1/0551 20130101; A61N 1/36171 20130101;
A61N 1/37247 20130101; A61N 1/36053 20130101; A61N 1/37235
20130101; A61N 1/36114 20130101 |
International
Class: |
A61N 1/36 20060101
A61N001/36; A61N 1/372 20060101 A61N001/372; A61N 1/05 20060101
A61N001/05 |
Claims
1. An apparatus comprising: a stimulator configured to generate one
or more electric stimuli based at least in part on at least one
stimulating parameter; at least two leads, each of the at least two
leads having a proximal end and a distal end, wherein the proximal
end of each lead is electrically connected to the stimulator; and
at least one stimulating surface at the distal end of each of the
at least two leads, wherein the at least one stimulating surface is
configured to create an electrical field in response to receiving
the one or more electric stimuli generated by the stimulator.
2. The apparatus of claim 1, wherein the at least two leads and the
at least one stimulating surface are provided as components of an
open field bipolar electrode.
3. The apparatus of claim 2, wherein the open field bipolar
electrode comprises one of an epimysial electrode, a fascial
electrode, a needle electrode, a wire electrode and a plate
electrode.
4. The apparatus of claim 1, wherein the at least two leads are
configured to be secured to a pleural membrane of a subject using
one or more of the following: sutures; surgical clips; surgical
glue; barbs; coils; mesh; or corkscrew wire.
5. The apparatus of claim 4, further comprising said one or more of
the following: sutures; surgical clips; surgical glue; barbs;
coils; mesh; or corkscrew wire.
6. The apparatus of claim 1, wherein the at least one stimulating
parameter comprises an electric pulse frequency selected from a
range of 3 Hertz to 20 Hertz.
7. The apparatus of claim 1, wherein the at least one stimulating
parameter comprises an electric pulse duration selected from a
range of 200 .mu.s to 1000 .mu.s.
8. The apparatus of claim 1, wherein the at least one stimulating
parameter comprises an electric current amperage selected from a
range of 1 mA to 12 mA.
9. The apparatus of claim 1, wherein the at least one stimulating
parameter comprises a duty cycle having a 10 second ON period and a
5 second OFF period.
10. The apparatus of claim 1, wherein the at least one stimulating
parameter comprises a duty cycle comprising an ON period of up to
24 hours and an OFF period between 1 second to 2000 seconds.
11. The apparatus of claim 1, wherein each stimulating surface of
the at least one stimulating surface is between 0.5 mm to 5 mm in
length and between 0.5 mm and 1.5 mm in width.
12. The apparatus of claim 1, each stimulating surface of the at
least one stimulating surface is between 0.5 mm to 5 mm in length
and 0.5 mm to 5 mm in width.
13. The apparatus of claim 1, wherein the at least two leads
comprise a first lead and a second lead, wherein the at least one
stimulating surface at the distal end of the first lead comprises a
first stimulating surface, and wherein the at least one stimulating
surface at the distal end of the second lead comprises a second
stimulating surface that is positioned 1 mm to 5 mm away from the
first stimulating surface.
14. The apparatus of claim 1, wherein each of the at least two
leads comprises a conducting wire that is at least partially
surrounded by an insulating surface, and wherein each stimulating
surface of the at least one stimulating surface at the distal end
of each lead is formed at an exposed area where the conducting wire
is not covered by the insulating surface.
15. The apparatus of claim 14, wherein the conducting wire
comprises platinum.
16. The apparatus of claim 1, further comprising at least two
insertion needles, wherein the distal end of each lead of the at
least two leads is coupled to a respective insertion needle of the
at least two insertion needles.
17. The apparatus of claim 1, further comprising at least two caps,
wherein each cap of the at least two caps is placed on the distal
end of a respective lead of the at least two leads.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/328,386, filed Jan. 23, 2017, which is a
U.S. national phase of International Patent Application No.
PCT/US2015/041839, filed Jul. 23, 2015, which claims priority to
and the benefit of the filing date of U.S. Provisional Patent
Application No. 62/028,108, filed Jul. 23, 2014. The entirety of
each of these applications is incorporated herein by reference for
all purposes.
BACKGROUND
Field of the Invention
[0002] The present invention is generally related to treatment of
heart failure and is more specifically related to vagus nerve
stimulation to induce parasympathetic activation.
Related Art
[0003] Congestive heart failure (CHF) is characterized by a
sustained decrease in the heart's pumping ability usually due to
ventricular contractile dysfunction. CHF results in decreased blood
delivery to the body and an accumulation of blood on the venous
side of the circulatory system. One consequence of CHF is long term
deleterious effects on cardiac function caused by an activation of
both the sympathoadrenal and the renin-angiotensin-aldosterone
system. CHF also causes drops in vagal and parasympathetic
activities, leading to a decrease in the release of acetylcholine
and activation of cardiac muscarinic receptors. On the one hand,
the activation of cardiac muscarinic receptors generally suppresses
atrial pacemaker activity, slows the rate of excitation spreading
from the atrium to the ventricles, and decreases the contractility
and conduction rate of both the atrium and the ventricle.
Meanwhile, the benefits of vagal activity are largely diminished,
such as its antagonistic effects on the release of catecholamines
from sympathetic nerve terminals and anti-inflammatory immune
responses.
[0004] The vagus nerve is part of the automatic nervous system that
controls involuntary bodily functions, including heart rate.
Patients experiencing CHF exhibit a lack of parasympathetic input
to the heart. Thus, vagal nerve stimulation has proven to be an
effective treatment for heart failure. In one recent clinical study
conducted by Schwartz, the right vagus nerve was stimulated using a
cuff electrode. The treatment included application of electric
pulse stimulation at an average frequency of 2 to 4 Hertz and with
currents ranging from 4 to 5 mA to achieve a reduction in heart
rate. The electric pulses were delivered during the refractory
period of the ventricles using higher frequency pulse trains. On
the one hand, the Schwartz study reported a number of positive
outcomes, including improvements in patient symptoms based on New
York Heart Association's (NYHA) functional classification system.
Treated patients, for instance, were able to sustain greater levels
and extent of physical activities, such as longer periods of
walking. Results of the study additionally demonstrated improved
left ventricular end-systolic volume and end-diastolic volume in
patients 3, 6, and 12 months post-implant. However, the study also
revealed a number of negative side effects, particularly ones
associated with the selection of treatment site.
[0005] In the Schwartz study, vagal nerve stimulation was performed
in the neck region of the participating patients, which is
consistent with the prevailing practice. In human beings, vagal
nerve stimulation is typically performed by applying electrical
stimulation to the portion of the vagus nerve that traverses the
neck region. The neck region is a common stimulation site because
the human vagus nerve tends to be more accessible for electrical
stimulation by conventional electrodes in that particular region.
Vagal nerve stimulation in the neck obviates risky surgical
procedures and can be performed under local anesthesia. However,
vagal nerve stimulation in the neck can also cause a litany of
negative side effects. As was reported in the Schwartz study,
stimulating the vagus nerve in the neck region can cause transient
hoarseness, coughing, and pronounced sensation of electrical
stimulation and discomfort. Consequently, for patients treated
according to the Schwartz methodology, the duration of each
continuous stimulation period is limited.
SUMMARY
[0006] To reduce or to avoid the side effects of conventional
treatment methods, the apparatus and method described herein are
directed toward stimulation of the vagus nerve at a select location
other than the neck region. Applications of the apparatus and
methods described herein are highly beneficial for patients with
chronic heart failure and are also beneficial during open heart
surgery, a period when vagal parasympathetic effects on the heart
are reduced. In some embodiments, cardiac branches of the vagus
nerve are stimulated below the laryngeal nerve bifurcation, an area
of the vagus nerve located in the right upper chest below the
branching point of the recurrent laryngeal nerve. In some
embodiments, stimulation is applied to the vagus nerve and caudal
cardiac branch of the vagus nerve below the laryngeal nerve branch
bifurcation from the vagus nerve. Advantageously, stimulating the
vagus nerve and branches of the vagus nerve below the laryngeal
nerve branch bifurcation has been shown to slow the heart rate with
minimal side effects. For example, stimulating the branches of the
vagus nerve below the laryngeal nerve bifurcation results in
parasympathetic activation without disturbing nearby sympathetic
nerve fibers and triggering any adverse sympathetic responses
(e.g., increased heart rate). In addition, some embodiments of the
apparatus and method described herein are directed toward a
minimally invasive means of implanting an electrode in the upper
thorax. For example, vagal stimulation is performed without the
placement of a cuff around the nerve (i.e., cuff electrode).
[0007] Instead, in some embodiments, an open field electrode is
placed on the pleural membrane overlying the vagus nerve or through
the pleural membrane overlying the vagus nerve. In humans, there is
minimal musculature where the vagus nerve is located in the upper
thorax and the vagus nerve and its branches are isolated from
sensory nerves by the tracheal and lungs allowing for vagal
stimulation without discomfort. Thus, in embodiments where the
vagus nerve is stimulated in the upper thorax, open field
electrodes are superior since open field electrodes entail a less
complicated and less invasive implantation procedure than cuff
electrodes. However, use of an open field electrode can stimulate
nearby sympathetic nerve fibers and trigger adverse sympathetic
responses (e.g., increased heart rate). Some embodiments of the
apparatus and method described herein are directed toward the use
of a needle type electrode. In some embodiments, vagal stimulation
in the upper thorax is performed using a securable-wire electrode.
The securable-wire electrode is akin to the needle electrodes used
in earlier studies but offers more clinical utility as it can be
placed closer to the vagus nerve. This is a particularly useful
feature in cases where there is copious fat surrounding the nerve
or where the branches of the vagus nerve are distant from the
pleural membrane. In addition, a securable-wire electrode can be
attached more easily to the pleural membrane.
[0008] Other features and advantages of the present invention will
become more readily apparent to those of ordinary skill in the art
after reviewing the following detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The structure and operation of the present invention will be
understood from a review of the following detailed description and
the accompanying drawings in which like reference numerals refer to
like parts and in which:
[0010] FIG. 1 is a diagram illustrating an example apparatus for
stimulating the vagus nerve according to an embodiment;
[0011] FIG. 2A is a diagram illustrating an example bipolar
electrode lead according to an embodiment;
[0012] FIG. 2B is a diagram illustrating an example bipolar
electrode lead having an insertion needle according to an
embodiment;
[0013] FIG. 2C is a diagram illustrating an example bipolar
electrode lead having a cap according to an embodiment;
[0014] FIG. 3A is a diagram illustrating an example placement of
stimulating surfaces near the vagus nerve according to an
embodiment;
[0015] FIG. 3B is a diagram illustrating an example placement of
stimulating surfaces near the vagus nerve according to an
embodiment;
[0016] FIG. 3C is a diagram illustrating an example placement of
stimulating surfaces near the vagus nerve according to an
embodiment;
[0017] FIG. 3D is a diagram illustrating an example placement of
stimulating surfaces near the vagus nerve according to an
embodiment;
[0018] FIG. 4 is a diagram illustrating an example of the upper
portion of the glossopharyngeal, vagus, and accessory nerves
according to an embodiment; and
[0019] FIG. 5 is a block diagram illustrating an example wired or
wireless processor enabled device that may be used in connection
with various embodiments described herein.
DETAILED DESCRIPTION
[0020] Certain embodiments disclosed herein provide for an
apparatus and a method of stimulating the vagus nerve in the upper
thorax in order to cause parasympathetic activation in patients
suffering from heart failure. For example, the vagus nerve trunk or
alternatively branches of the vagus nerve are stimulated below the
laryngeal nerve bifurcation using open field electrodes (e.g.,
small plate electrode, epimysial electrode, fascial electrode,
needle electrode, securable-wire electrode, etc.). After reading
this description it will become apparent to one skilled in the art
how to implement the invention in various alternative embodiments
and alternative applications. However, although various embodiments
of the present invention will be described herein, it is understood
that these embodiments are presented by way of example only, and
not limitation. As such, this detailed description of various
alternative embodiments should not be construed to limit the scope
or breadth of the present invention as set forth in the appended
claims.
[0021] Introduction
[0022] Use of isolated field electrodes (e.g., cuff electrode) for
vagal stimulation in the neck area has many drawbacks. The
inventors have recognized that vagal stimulation below the
laryngeal nerve bifurcation provides substantial improvement of
many of these drawbacks. However, implantation of an isolated field
electrode below the laryngeal nerve bifurcation is undesirable.
Accordingly, the inventors have recognized that use of an open
field electrode (e.g., small plate electrode, epimysial electrode,
fascial electrode, needle electrode, securable-wire electrode,
etc.) is superior for implantation because open field electrodes
entail a less complicated and less invasive implantation procedure.
However, use of an open field electrode below the laryngeal nerve
bifurcation may cause undesirable stimulation of nearby cardiac
sympathetic nerve fibers that come from the sympathetic chain
ganglia (e.g., from the cervical and stellate sympathetic ganglia)
and thereby trigger adverse sympathetic responses such as increased
heart rate. The inventors have therefore also recognized that the
specific implantation location of the open field electrode
(specifically, the simulating surfaces of the open field electrode)
is paramount for realizing the significant benefits of
parasympathetic activation while minimizing the significant
drawbacks of adverse sympathetic responses triggered by stimulation
of nearby cardiac sympathetic nerve fibers. While the specific
location may vary from patient to patient, the optimal implantation
location is generally between 1 cm and 10 cm below (caudal or
distal to) the laryngeal nerve bifurcation from the vagus
nerve.
[0023] FIG. 1 is a diagram illustrating an example apparatus for
stimulating the vagus nerve 130 according to an embodiment. In some
embodiments, the apparatus is used to stimulate the vagus nerve 130
in the upper thorax. For example, the apparatus can be used to
stimulate the vagus nerve 130 below the laryngeal nerve
bifurcation. The portion of the vagus nerve 130 that is stimulated
may be the main vagus nerve trunk or may be one or more branches of
the vagus nerve 130.
[0024] As shown in FIG. 1, apparatus includes a stimulator 100 and
a bipolar stimulating electrode 110, which may comprise one or more
leads 112A, 112B each having one or more stimulating surfaces 120
arranged in a bipolar configuration. In some embodiments, the leads
112A, 112B are coated with an insulating material, such as
Teflon.RTM. or any other appropriate material. The stimulating
surface 120 on each electrode may comprise an uncoated or
uninsulated portion of the electrode. In alternative embodiments,
the stimulating surface 120 may have a variety of shapes such as a
rectangle, an arrow/point, an oval, a circle, or the like.
Advantageously, the shape of the stimulating surface 120 may be
selectively optimized for the location in which the stimulating
surface 120 is deployed (e.g., on an outer surface of the pleural
membrane or between the vagus nerve and an inner surface of the
pleural membrane). Each of the two leads 112A, 112B comprising the
bipolar stimulating electrode is attached at a proximal end to the
stimulator 100 and in electrical communication with the stimulator
100. In an embodiment, the stimulator 100 is located inside the
body. In an alternative embodiment, the stimulator 100 is located
outside of the body.
[0025] The stimulator 100 comprises a power source for generating
electrical stimuli and a memory 95 for storing operating parameters
and instructions and the like. The stimulator may include
communication interfaces for receiving instructions from a separate
device via a wired or wireless communication link. The power source
may be internal (e.g., battery) or external (e.g., power supply
connected to an external power source such as an electrical grid).
The stimulator 100 comprises a processor configured to control the
operation of the stimulator 100 in accordance with predetermined
instructions or instructions received dynamically in real time. An
example hardware embodiment of stimulator 100 is later described
with respect to FIG. 5.
[0026] FIG. 1 illustrates that the stimulating surfaces 120 in the
bipolar configuration are placed within close proximity of the
vagus nerve 130. In some embodiments, the electrode 110 comprises
an open field electrode. As such, in some embodiments, the
stimulating surfaces 120 can be positioned without an isolating
cuff. According to the embodiments describe herein, the stimulating
surfaces 120 can be placed adjacent to the vagus nerve 130 by
attaching or securing the electrodes to an outer surface of the
pleural membrane in a number of different ways. For example, the
leads 112A, 112B can be secured using sutures, self-securing barbs,
surgical glue, mesh, corkscrew wire, or any other appropriate
fastening mechanisms. Securing means that attach the electrode 110
to physical structures on or near the vagus nerve 130 can be
applied at one or more locations along the leads 112A, 112B and
stimulating surfaces 120 of the electrode 110.
[0027] In some embodiments, apparatus 100 is used to stimulate
branches of the vagus nerve 130 in the upper-thorax as therapy for
patients suffering from heart failure. In some embodiments,
stimulating parameters, including frequencies that range from 4
Hertz to 20 Hertz, are used in order to induce the desired vagal
effects, such as a decrease in heart rate. Stimulating the vagus
nerve 130 with an excessively large current is known to cause
negative side effects (e.g., paraspinal muscle stimulation).
Additionally, high stimulating currents may induce supraventricular
arrhythmia. In some embodiments, the main vagus nerve trunk or
branches of the vagus nerve 130 are stimulated according to
stimulating parameters that include current amperage ranging from 1
mA to 12 mA. In some embodiments, a stimulating pulse duration of
300 .mu.s is optimal for stimulating the small parasympathetic
fibers in the vagus nerve or its branches that innervate the heart.
In some embodiments, the stimulating pulse duration can range from
200 .mu.s to 1000 .mu.s. In some embodiments, duty cycles of
stimulation are used in order to maintain effective stimulation. In
one embodiment, the duty cycle can comprise a 10 second ON period
and a 5 second OFF period. In some embodiments, the duty cycle can
include a continuous ON period of up to 24 hours and a 1 to 2000
second OFF period for recovery.
[0028] In one embodiment, stimulation of the vagus nerve 130 is
conducted to induce two to ten beats per minute of heart rate
slowing. For example, initial stimulation may be conducted at a low
frequency (e.g., 4 Hz) and a low current (e.g., 1 mA) for a low
duration (e.g., 200 .mu.s) and if the desired reduction in heart
rate is not achieved, higher frequencies, current and duration may
be employed singularly or in any combination until the desired
heart rate reduction is achieved.
[0029] FIG. 2A is a diagram illustrating an example lead 112 of a
bipolar electrode 110 according to an embodiment. In alternative
embodiments, bipolar electrode 110 comprises an open field
electrode, a wire electrode, a needle electrode, an epimysial
electrode, a fascial electrode or any other type of electrode that
can be configured to be positioned on or near the vagus nerve 130.
Although only a single lead 112 is shown in FIG. 2A for the sake of
simplicity, it will be understood that one or more leads 112 may be
employed, with each lead 112 being electrically coupled to the
stimulator 100.
[0030] According to the embodiment illustrated in FIG. 2A, the lead
112 comprises a conducting wire 160 that is at least partially
surrounded by an insulating surface 170. The lead 112 additionally
comprises one or more stimulating surfaces 120 in an exposed area
180 where the conducting wire 160 is not covered by the insulating
surface 170. The exposed area 180, although shown in an interior
portion of the lead 112, can alternatively be positioned at the
distal end of the lead 112. In an embodiment having more than one
stimulating surface 120 on an individual lead 112, the plural
stimulating surfaces 120 may all be positioned in an interior
portion of the lead 112 or one of the stimulating surfaces 120 may
be positioned at the distal end of the lead 112 furthest away from
the stimulator 100.
[0031] In some embodiments, portions of the leads 112 are insulated
by the insulating surface 170 while other portions of the leads 112
are not insulated and create exposed areas 180. In some
embodiments, the exposed areas 180 of the lead 112 comprise
stimulating surfaces 120. For example, each of the leads 112 may
contain at least one stimulating surface 120 in an exposed area
180. However, it may be desirable or necessary in some cases for
each lead 112 to have multiple (i.e., two or more) stimulating
surfaces 120. In some embodiments, the leads 112 and the
stimulating surfaces 120 are positioned at a desired distance apart
from one another. For example, the stimulating surface 120 on a
first lead can be positioned 1 mm to 5 mm away from the stimulating
surface 120 on a second lead.
[0032] Furthermore, in some embodiments, the stimulating surfaces
112 on the leads 112 are relatively small in size. For example, in
order to achieve the desired parasympathetic effects, the vagus
nerve and particularly those fibers that innervate the heart, must
be stimulated with a concentrated electric current. In an
embodiment where the electrode 110 comprises an open field
electrode, the stimulating surfaces 120 are advantageously
relatively small in size in order to produce high charge injection
densities and thereby stimulate the vagus nerve 130 with the lowest
possible current. For example, the stimulating surfaces 120 in such
an embodiment can be between 0.5 mm to 5 mm long and 0.5 mm wide to
5 mm wide (e.g., an area of 0.25 mm.sup.2 to 25 mm.sup.2). In
alternative embodiments, the area of the simulating surfaces 120
may be smaller, for example a length between 0.5 mm to 5 mm long
and the width from 0.5 mm to 1.5 mm wide (e.g., an area of 0.25
mm.sup.2 to 7.5 mm.sup.2). In one embodiment, the stimulating
surfaces 120 areas are cross-sectional areas and the actual area of
exposed stimulating surface would be much greater if multi-stranded
wire were used as the stimulating surface 120.
[0033] In alternative embodiments, the stimulating surfaces 120 are
0.5 mm to 1.5 mm in length and 0.5 mm to 1.5 mm in width. In other
embodiments, the stimulating surfaces 120 are 1 mm to 2 mm in
length and 1 mm to 2 mm in width. Advantageously, a small area of
the stimulating surface 120 generates a contained electric field
and avoids the negative consequences associated with spreading the
electric field.
[0034] According to the embodiments described herein, conducting
wire 160 can be made of any appropriate conductive material that is
both corrosion and fracture resistant (e.g., platinum). In other
words, the stimulating surfaces 120 at the exposed areas 180 of the
leads 112 can be made of any conductive material that is resistant
to corrosion and fracture, such as platinum, 316 LVM stainless
steel, or any suitable equivalent. In some embodiments, the
insulating surface 170 surrounding the conducting wire 160 may
comprise a single enclosure such as a tube. In some embodiments,
post insertion, leads 112 are secured to the pleural membrane 200
surrounding the vagus nerve 130. In some embodiments, leads 112 are
secured to the pleural membrane 200 at its entry point and exit
point through the pleural membrane 200. In some embodiments, the
leads 112 can be secured to the pleural membrane 200 using any
appropriate fastening mechanisms, including but not limited to
surgical clips, sutures, barbs, corkscrew wire, mesh, curved
surfaces (e.g., coils) and the like. In some embodiments, the
insertion needle 190 that is initially attached to the leads 112 is
removed (e.g., cut off) once the leads 112 are secured at an
appropriate position, such as the entry and exit point through the
pleural membrane 200.
[0035] FIG. 2B is a diagram illustrating an example bipolar
electrode lead 112 having an insertion needle 190 according to an
embodiment. Although only a single lead 112 is shown in FIG. 2B for
the sake of simplicity, it will be understood that one or more
leads 112 may be employed, with each lead 112 being electrically
coupled to the stimulator 100 at the proximal end and connected to
the insertion needle 190 at the distal end. In some embodiments,
the insertion needle 190 is used to position the lead 112 and its
corresponding stimulating surfaces 120 in proximity of the vagus
nerve 130 and the insertion needle 190 is also configured to be
removed once the lead 112 and its corresponding stimulating
surfaces 120 is implanted. For example, in one embodiment, the
insertion needle 190 is used for the initial placement of the one
or more leads 112 and then the insertion needle 190 is removed
(e.g., cut off) after the leads 112 are secured.
[0036] In one embodiment, the insertion needle 190 is configured to
guide the lead 112 and its corresponding stimulating surfaces 120
through the pleural membrane and around the vagus nerve. As will be
discussed in more detail below, in alternative embodiments, the
lead 112 and its corresponding stimulating surfaces 120 may be
positioned and secured on or near an external surface of the
pleural membrane 209. Thus, in certain embodiments, the lead 112
and its corresponding stimulating surfaces 120 can be positioned
and secured without insertion needle 190.
[0037] FIG. 2C is a diagram illustrating an example bipolar
electrode lead 112 having a cap 195 according to an embodiment.
Although only a single lead 112 is shown in FIG. 2C for the sake of
simplicity, it will be understood that one or more leads 112 may be
employed, with each lead 112 being electrically coupled to the
stimulator 100. In some embodiments, such as the one shown in FIG.
2C, a cap 195 can be placed on the terminal or distal end of each
lead 112. The cap 195 may be applied to the lead 112 prior to
insertion of the lead 112 or alternatively may be applied to the
lead 112 after the lead 112 has been positioned and secured. In one
embodiment, the cap 195 is applied to the lead 112 after the lead
112 has been positioned and secured and the insertion needle 190
has been removed.
[0038] FIG. 3A is a diagram illustrating an example placement of
stimulating surface 120 near the vagus nerve 130 according to an
embodiment. Although only a single lead 112 is shown in FIG. 3A for
the sake of simplicity, it will be understood that one or more
leads 112 may be employed, with each lead 112 being electrically
coupled to the stimulator 100 at its proximal end. In some
embodiments described herein, electric stimuli are applied to the
vagus nerve 130 between the vagus nerve 130 and the pleural
membrane 200 that surrounds the vagus nerve. In FIG. 3A, the
stimulating surface 120 is inserted through the pleural membrane
200 and traverses a layer 210 of fat and connective tissue
surrounding the vagus nerve 130. In various embodiments, the
stimulating surfaces 120 are placed in an appropriate position on
or near the vagus nerve 130. As FIG. 3A illustrates, the
stimulating surfaces 120 are positioned between the vagus nerve 130
and the pleural membrane 200. In one embodiment, the stimulating
surfaces 120 are positioned closer to the vagus nerve 130 than the
pleural membrane 200. In one embodiment, the stimulating surfaces
120 are placed as close to the vagus nerve 130 as possible. In an
embodiment where the stimulating surfaces 120 are positioned
between the vagus nerve 130 and an inner surface of the pleural
membrane 200, the size of each stimulating surface 120 can be
relatively smaller with a smaller overall surface area of the
stimulating surface 120 because the electrical stimuli does not
need to penetrate the tissue of the pleural membrane 200 in order
to stimulate the vagus nerve 130.
[0039] FIG. 3A further shows that the leads 112 are secured to the
pleural membrane 200 at one or both of the entry site and exit
site. Different types of fastening means 230 can be used in the
various embodiments described herein (e.g., suture, surgical clips,
barbs, coils, mesh, corkscrew wire, and the like).
[0040] FIG. 3B is a diagram illustrating an example placement of
stimulating surface 120 near the vagus nerve 130 according to an
embodiment. Although only a single lead 112 is shown in FIG. 3B for
the sake of simplicity, it will be understood that one or more
leads 112 may be employed, with each lead 112 being electrically
coupled to the stimulator 100 at its proximal end. As depicted in
FIG. 3B, the vagus nerve 130 is surrounded by the pleural membrane
200. In some embodiments, branches of the vagus nerve 130 are
stimulated beneath the pleural membrane 200. In one embodiment, the
leads 112 and stimulating surfaces 120 of an electrode 110, such as
a securable-wire electrode or bipolar electrode or epimysial
electrode or fascial electrode, are inserted through the pleural
membrane. FIG. 3B depicts the hammock position, wherein the leads
112 are placed under and around the vagus nerve 130. In various
embodiments, the hammock position is used in order to better
maintain the position of the stimulating surfaces 120 proximal to
the vagus nerve 130. In some embodiments, an insertion needle, such
as the one depicted in FIG. 2, is used to guide the leads 112 and
their corresponding stimulating surfaces 120 into and out of the
pleural membrane 200, and to help place the stimulating surfaces
120 in an appropriate position. For example, to achieve the
placement desired for the hammock position, the insertion needle
first enters the pleural membrane 200 at a first side of the vagus
nerve 130, then travels beneath and around a second side vagus
nerve 130 opposite the first side of the vagus nerve 130, and
finally exits the pleural membrane 200 on substantially the same
first side of the vagus nerve 130 where the insertion needle
entered the pleural membrane 200. In some embodiments, the entry
and exit points on the pleural membrane 200 for the leads 112 are
an appropriate distance apart. For example, the leads 112 may enter
and exit the pleural membrane 200 at least 2 cm apart. In some
embodiments, the stimulating surfaces 120 are placed within close
proximity of the vagus nerve 130. For example, in FIG. 3B, the
stimulating surfaces 120 are placed according to the hammock
position and are therefore positioned beneath the vagus nerve
relative to the entry and exit points of the leads 112 through the
pleural membrane 200. In other embodiments, the stimulating
surfaces 120 are placed along the top or sides of the vagus nerve
130 relative to the entry and exit points of the leads 112 through
the pleural membrane 200. In various embodiments, the stimulating
surfaces 120 are placed as close to the vagus nerve 130 as
possible. In an embodiment where the stimulating surfaces 120 are
positioned between the vagus nerve 130 and an inner surface of the
pleural membrane 200, the size of each stimulating surface 120 can
be relatively smaller with a smaller overall surface area of the
stimulating surface 120 because the electrical stimuli does not
need to penetrate the tissue of the pleural membrane 200 in order
to stimulate the vagus nerve 130.
[0041] FIG. 3C is a diagram illustrating an example placement of
stimulating surface 120 near the vagus nerve 130 according to an
embodiment. Although only a single lead 112 is shown in FIG. 3C for
the sake of simplicity, it will be understood that one or more
leads 112 may be employed, with each lead 112 being electrically
coupled to the stimulator 100 at its proximal end. As shown in FIG.
3C, the leads 112 and stimulating surfaces 120 may be positioned on
and secured directly to an exterior surface of the pleural membrane
200. In certain areas of the human body, such as in the upper
thorax, the pleural membrane 200 is situated within close proximity
of the vagus nerve 130. For instance, the fat and tissue layer 210
between the pleural membrane 200 and the vagus nerve 130 can be
minimal in this location. Thus, in certain embodiments, the
stimulating surfaces 120 do not need to be inserted through the
pleural membrane 200 in order to position the stimulating surfaces
120 close enough to the vagus nerve 130 to expose the vagus nerve
130 to adequate electric stimuli. FIG. 3C shows that the leads 112
and corresponding stimulating surfaces 120 are placed on and
secured to the pleural membrane 200 without penetrating its
surface. Additionally, the stimulating surfaces 112 remain outside
the pleural membrane 200. In some embodiments, the vagus nerve 130
is stimulated through the pleural membrane 200 while the leads 112
and corresponding stimulating surfaces 120 are placed and secured
without penetrating the pleural membrane 200. In some embodiments,
avoiding the insertion of the leads 112 and corresponding
stimulating surfaces 120 through the pleural membrane 200 expedites
and simplifies the implantation process. In an embodiment where the
stimulating surfaces 120 are positioned on or near the outside
surface of the pleural membrane 200, the size of each stimulating
surface 120 can be relatively larger with a larger overall surface
area of the stimulating surface 120 because the electrical stimuli
needs to penetrate the tissue of the pleural membrane 200 in order
to stimulate the vagus nerve 130.
[0042] FIG. 3D is a diagram illustrating an example placement of
stimulating surface 120 near the vagus nerve 130 according to an
embodiment. Although only a single lead 112 is shown in FIG. 3D for
the sake of simplicity, it will be understood that one or more
leads 112 may be employed, with each lead 112 being electrically
coupled to the stimulator 100 at its proximal end. Some of the
embodiments described herein are directed towards the use of leads
112 where the stimulating surfaces 120 are located on the distal
tips of the leads 112. In some embodiments, needle electrodes 110
having a pointed or small disk shape stimulating surface 120 are
used to stimulate the vagus nerve 130. In some embodiments, the
vagus nerve 130 is stimulated using needle electrodes 110 that are
insulated except for regions or areas around the distal tip of the
leads 112. As shown in FIG. 3D, the lead 112 comprises a tip 240
and a corresponding stimulating surface 120 that together comprise
a needle-like structure. The needle-like structure is inserted
through the pleural membrane 130 such that the stimulating surface
120 at the distal tip of the lead 112 is positioned near the vagus
nerve 130.
[0043] In some embodiments, such as shown in FIGS. 3A, 3B, and 3D,
the vagus nerve 130 is stimulated by applying electric stimuli
between the vagus nerve 130 and the pleural membrane 200. In other
embodiments, such as shown in FIG. 3C, the vagus nerve 130 is
stimulated by applying electric stimuli through the pleural
membrane 200. Although not shown in FIG. 3D, it is understood that
in cases where the vagus nerve 130 is sufficiently close to the
pleural membrane 200 (e.g., minimal intervening fat and connective
tissue layer 210), the needle electrodes 110 may not fully
penetrate the pleural membrane 200. Otherwise stated, in some
embodiments, the vagus nerve is stimulated by needle electrodes 110
that are placed substantially on top of the pleural membrane 200
and secured to the pleural membrane 200 by fasteners 230. In an
embodiment where the stimulating surfaces 120 are positioned
between the vagus nerve 130 and an inner surface of the pleural
membrane 200, the size of each stimulating surface 120 can be
relatively smaller with a smaller overall surface area of the
stimulating surface 120 because the electrical stimuli does not
need to penetrate the tissue of the pleural membrane 200 in order
to stimulate the vagus nerve 130. However, in an embodiment where
the stimulating surfaces 120 are positioned on or near the outside
surface of the pleural membrane 200, the size of each stimulating
surface 120 can be relatively larger with a larger overall surface
area of the stimulating surface 120 because the electrical stimuli
needs to penetrate the tissue of the pleural membrane 200 in order
to stimulate the vagus nerve 130.
[0044] In one embodiment, when the stimulating surface 120 is
positioned between the vagus nerve 130 and the inner surface of the
pleural membrane 200, a wire electrode or needle electrode is
employed. In an alternative embodiment, when the stimulating
surface 120 is positioned on or near the outer surface of the
pleural membrane 200, a plate or fascial or epimysial electrode is
employed.
[0045] In one embodiment, when the leads 112 and corresponding
stimulating surfaces 120 are positioned adjacent to the vagus nerve
130, the stimulating surfaces 120 may be on the top or bottom or
medial or lateral sides of the vagus nerve 130. In one embodiment,
a lateral location relative to the vagus nerve 130 may be
beneficial to reduce the risk of atrial arrhythmia due to
stimulation.
[0046] FIG. 4 is a diagram illustrating an example upper portion of
the glossopharyngeal, vagus, and accessory nerves according to an
embodiment. As depicted in FIG. 4, several branches of the vagus
nerve extend to the heart. However, sympathetic nerve fibers are
found near the main trunk of the vagus nerve. Thus, some of the
embodiments described herein are directed toward stimulation of the
branches of the vagus nerve. In some embodiments, stimulator 100 is
used to stimulate branches of the vagus nerve. In particular, in
certain embodiments, stimulator 100 is used to stimulate the caudal
cardiac branch of the vagus nerve. FIG. 4 further shows that
stimulation of the vagus nerve in one embodiment takes place below
the recurrent laryngeal nerve bifurcation 500. In particular, some
of the embodiments described herein are directed towards
stimulating the vagus nerve below the laryngeal nerve bifurcation
500 as heart failure therapy, since application of electric stimuli
to that site is associated with minimal complications and side
effects. In some embodiments, an apparatus (e.g., stimulator 100)
is used to stimulate the vagus nerve below the laryngeal nerve
bifurcation 500 in order to induce desired vagal effects, such as a
decrease in heart rate. In some embodiments, electric stimuli are
applied to the vagus nerve at any location 510 distal to the
laryngeal nerve bifurcation 500. In some embodiments, a precise
point on the vagus nerve 130 below the laryngeal nerve bifurcation
500 where electric stimuli are optimally applied is determined on
an individual basis. For example, depending on the individual
patient, the vagus nerve 130 can be optimally stimulated at a
location that is between 1 cm and 10 cm below (caudal or distal to)
the laryngeal nerve bifurcation 500.
[0047] FIG. 5 is a block diagram illustrating an example wired or
wireless processor enabled device 550 that may be used in
connection with various embodiments described herein. For example
the system 550 may be used with the stimulator 100, as previously
described with respect to FIG. 1. The system 550 can be a
conventional personal computer, computer server, personal digital
assistant, smart phone, tablet computer, or any other processor
enabled device that is capable of wired or wireless data
communication. Other computer systems and/or architectures may be
also used, as will be clear to those skilled in the art.
[0048] System 550 preferably includes one or more processors, such
as processor 560. Additional processors may be provided, such as an
auxiliary processor to manage input/output, an auxiliary processor
to perform floating point mathematical operations, a
special-purpose microprocessor having an architecture suitable for
fast execution of signal processing algorithms (e.g., digital
signal processor), a slave processor subordinate to the main
processing system (e.g., back-end processor), an additional
microprocessor or controller for dual or multiple processor
systems, or a coprocessor. Such auxiliary processors may be
discrete processors or may be integrated with the processor
560.
[0049] The processor 560 is preferably connected to a communication
bus 555. The communication bus 555 may include a data channel for
facilitating information transfer between storage and other
peripheral components of the system 550. The communication bus 555
further may provide a set of signals used for communication with
the processor 560, including a data bus, address bus, and control
bus (not shown). The communication bus 555 may comprise any
standard or non-standard bus architecture such as, for example, bus
architectures compliant with industry standard architecture
("ISA"), extended industry standard architecture ("EISA"), Micro
Channel Architecture ("MCA"), peripheral component interconnect
("PCI") local bus, or standards promulgated by the Institute of
Electrical and Electronics Engineers ("IEEE") including IEEE 488
general-purpose interface bus ("GPIB"), IEEE 696/S-100, and the
like.
[0050] System 550 preferably includes a main memory 565 and may
also include a secondary memory 570. The main memory 565 provides
storage of instructions and data for programs executing on the
processor 560. The main memory 565 is typically semiconductor-based
memory such as dynamic random access memory ("DRAM") and/or static
random access memory ("SRAM"). Other semiconductor-based memory
types include, for example, synchronous dynamic random access
memory ("SDRAM"), Rambus dynamic random access memory ("RDRAM"),
ferroelectric random access memory ("FRAM"), and the like,
including read only memory ("ROM").
[0051] The secondary memory 570 may optionally include a internal
memory 575 and/or a removable medium 580, for example a floppy disk
drive, a magnetic tape drive, a compact disc ("CD") drive, a
digital versatile disc ("DVD") drive, etc. The removable medium 580
is read from and/or written to in a well-known manner. Removable
storage medium 580 may be, for example, a floppy disk, magnetic
tape, CD, DVD, SD card, etc.
[0052] The removable storage medium 580 is a non-transitory
computer readable medium having stored thereon computer executable
code (i.e., software) and/or data. The computer software or data
stored on the removable storage medium 580 is read into the system
550 for execution by the processor 560.
[0053] In alternative embodiments, secondary memory 570 may include
other similar means for allowing computer programs or other data or
instructions to be loaded into the system 550. Such means may
include, for example, an external storage medium 595 and an
interface 570. Examples of external storage medium 595 may include
an external hard disk drive or an external optical drive, or and
external magneto-optical drive.
[0054] Other examples of secondary memory 570 may include
semiconductor-based memory such as programmable read-only memory
("PROM"), erasable programmable read-only memory ("EPROM"),
electrically erasable read-only memory ("EEPROM"), or flash memory
(block oriented memory similar to EEPROM). Also included are any
other removable storage media 580 and communication interface 590,
which allow software and data to be transferred from an external
medium 595 to the system 550.
[0055] System 550 may also include an input/output ("I/O")
interface 585. The I/O interface 585 facilitates input from and
output to external devices. For example the I/O interface 585 may
receive input from a keyboard or mouse and may provide output to a
display. The I/O interface 585 is capable of facilitating input
from and output to various alternative types of human interface and
machine interface devices alike. The I/O interface 585 may also be
adapted to generate electrical stimuli and send the electrical
stimuli to one or more electrodes (not shown) for delivery to
stimulating surfaces (not shown). The I/O interface 585 may
generate electrical stimuli from an internal or external power
source such as a battery (now shown) or power supply (not shown)
connected to an electrical grid.
[0056] System 550 may also include a communication interface 590.
The communication interface 590 allows software and data to be
transferred between system 550 and external devices (e.g.
printers), networks, or information sources. For example, computer
software or executable code may be transferred to system 550 from a
network server via communication interface 590. Examples of
communication interface 590 include a modem, a network interface
card ("NIC"), a wireless data card, a communications port, a PCMCIA
slot and card, an infrared interface, and an IEEE 1394 fire-wire,
just to name a few. The communication interface 590 advantageously
can receive instructions regarding the parameters for electrical
stimuli to be generated by the I/O interface 585. Such parameters
may include but are not limited to the stimulating frequency,
current amperage and duration, just to name a few.
[0057] Communication interface 590 preferably implements industry
promulgated protocol standards, such as Ethernet IEEE 802
standards, Fiber Channel, digital subscriber line ("DSL"),
asynchronous digital subscriber line ("ADSL"), frame relay,
asynchronous transfer mode ("ATM"), integrated digital services
network ("ISDN"), personal communications services ("PCS"),
transmission control protocol/Internet protocol ("TCP/IP"), serial
line Internet protocol/point to point protocol ("SLIP/PPP"), and so
on, but may also implement customized or non-standard interface
protocols as well.
[0058] Software and data transferred via communication interface
590 are generally in the form of electrical communication signals
605. These signals 605 are preferably provided to communication
interface 590 via a communication channel 600. In one embodiment,
the communication channel 600 may be a wired or wireless network,
or any variety of other communication links. Communication channel
600 carries signals 605 and can be implemented using a variety of
wired or wireless communication means including wire or cable,
fiber optics, conventional phone line, cellular phone link,
wireless data communication link, radio frequency ("RF") link, or
infrared link, just to name a few.
[0059] Computer executable code (i.e., computer programs or
software) is stored in the main memory 565 and/or the secondary
memory 570. Computer programs can also be received via
communication interface 590 and stored in the main memory 565
and/or the secondary memory 570. Such computer programs, when
executed, enable the system 550 to perform the various functions of
the present invention as previously described.
[0060] In this description, the term "computer readable medium" is
used to refer to any non-transitory computer readable storage media
used to provide computer executable code (e.g., software and
computer programs) to the system 550. Examples of these media
include main memory 565, secondary memory 570 (including internal
memory 575, removable medium 580, and external storage medium 595),
and any peripheral device communicatively coupled with
communication interface 590 (including a network information server
or other network device). These non-transitory computer readable
mediums are means for providing executable code, programming
instructions, and software to the system 550.
[0061] In an embodiment that is implemented using software, the
software may be stored on a computer readable medium and loaded
into the system 550 by way of removable medium 580, I/O interface
585, or communication interface 590. In such an embodiment, the
software is loaded into the system 550 in the form of electrical
communication signals 605. The software, when executed by the
processor 560, preferably causes the processor 560 to perform the
inventive features and functions previously described herein.
[0062] The system 550 also includes optional wireless communication
components that facilitate wireless communication over a voice and
over a data network. The wireless communication components comprise
an antenna system 610, a radio system 615 and a baseband system
620. In the system 550, radio frequency ("RF") signals are
transmitted and received over the air by the antenna system 610
under the management of the radio system 615.
[0063] In one embodiment, the antenna system 610 may comprise one
or more antennae and one or more multiplexors (not shown) that
perform a switching function to provide the antenna system 610 with
transmit and receive signal paths. In the receive path, received RF
signals can be coupled from a multiplexor to a low noise amplifier
(not shown) that amplifies the received RF signal and sends the
amplified signal to the radio system 615.
[0064] In alternative embodiments, the radio system 615 may
comprise one or more radios that are configured to communicate over
various frequencies. In one embodiment, the radio system 615 may
combine a demodulator (not shown) and modulator (not shown) in one
integrated circuit ("IC"). The demodulator and modulator can also
be separate components. In the incoming path, the demodulator
strips away the RF carrier signal leaving a baseband receive audio
signal, which is sent from the radio system 615 to the baseband
system 620.
[0065] If the received signal contains audio information, then
baseband system 620 decodes the signal and converts it to an analog
signal. Then the signal is amplified and sent to a speaker. The
baseband system 620 also receives analog audio signals from a
microphone. These analog audio signals are converted to digital
signals and encoded by the baseband system 620. The baseband system
620 also codes the digital signals for transmission and generates a
baseband transmit audio signal that is routed to the modulator
portion of the radio system 615. The modulator mixes the baseband
transmit audio signal with an RF carrier signal generating an RF
transmit signal that is routed to the antenna system and may pass
through a power amplifier (not shown). The power amplifier
amplifies the RF transmit signal and routes it to the antenna
system 610 where the signal is switched to the antenna port for
transmission.
[0066] The baseband system 620 is also communicatively coupled with
the processor 560. The central processing unit 560 has access to
data storage areas 565 and 570. The central processing unit 560 is
preferably configured to execute instructions (i.e., computer
programs or software) that can be stored in the memory 565 or the
secondary memory 570. Computer programs can also be received from
the baseband processor 610 and stored in the data storage area 565
or in secondary memory 570, or executed upon receipt. Such computer
programs, when executed, enable the system 550 to perform the
various functions of the present invention as previously described.
For example, data storage areas 565 may include various software
modules (not shown) that are executable by processor 560.
[0067] Various embodiments may also be implemented primarily in
hardware using, for example, components such as application
specific integrated circuits ("ASICs"), or field programmable gate
arrays ("FPGAs"). Implementation of a hardware state machine
capable of performing the functions described herein will also be
apparent to those skilled in the relevant art. Various embodiments
may also be implemented using a combination of both hardware and
software.
[0068] Furthermore, those of skill in the art will appreciate that
the various illustrative logical blocks, modules, circuits, and
method steps described in connection with the above described
figures and the embodiments disclosed herein can often be
implemented as electronic hardware, computer software, or
combinations of both. To clearly illustrate this interchangeability
of hardware and software, various illustrative components, blocks,
modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall system.
Skilled persons can implement the described functionality in
varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a
departure from the scope of the invention. In addition, the
grouping of functions within a module, block, circuit or step is
for ease of description. Specific functions or steps can be moved
from one module, block or circuit to another without departing from
the invention.
[0069] Moreover, the various illustrative logical blocks, modules,
and methods described in connection with the embodiments disclosed
herein can be implemented or performed with a general purpose
processor, a digital signal processor ("DSP"), an ASIC, FPGA or
other programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. A general-purpose
processor can be a microprocessor, but in the alternative, the
processor can be any processor, controller, microcontroller, or
state machine. A processor can also be implemented as a combination
of computing devices, for example, a combination of a DSP and a
microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration.
[0070] Additionally, the steps of a method or algorithm described
in connection with the embodiments disclosed herein can be embodied
directly in hardware, in a software module executed by a processor,
or in a combination of the two. A software module can reside in RAM
memory, flash memory, ROM memory, EPROM memory, EEPROM memory,
registers, hard disk, a removable disk, a CD-ROM, or any other form
of storage medium including a network storage medium. An exemplary
storage medium can be coupled to the processor such the processor
can read information from, and write information to, the storage
medium. In the alternative, the storage medium can be integral to
the processor. The processor and the storage medium can also reside
in an ASIC.
[0071] The above description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
invention. Various modifications to these embodiments will be
readily apparent to those skilled in the art, and the generic
principles described herein can be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
it is to be understood that the description and drawings presented
herein represent a presently preferred embodiment of the invention
and are therefore representative of the subject matter which is
broadly contemplated by the present invention. It is further
understood that the scope of the present invention fully
encompasses other embodiments that may become obvious to those
skilled in the art and that the scope of the present invention is
accordingly not limited.
* * * * *