U.S. patent application number 10/777254 was filed with the patent office on 2004-08-19 for method and system for endotracheal/esophageal stimulation prior to and during a medical procedure.
Invention is credited to Colson, Michael A., Euler, David E., Hill, Michael R. S., Jahns, Scott E., Keogh, James R., Rakow, Nancy J., Ujhelyi, Michael R..
Application Number | 20040162584 10/777254 |
Document ID | / |
Family ID | 25508387 |
Filed Date | 2004-08-19 |
United States Patent
Application |
20040162584 |
Kind Code |
A1 |
Hill, Michael R. S. ; et
al. |
August 19, 2004 |
Method and system for endotracheal/esophageal stimulation prior to
and during a medical procedure
Abstract
A method of performing a medical procedure, such as surgery, is
provided. A nerve is stimulated in order to adjust the beating of
the heart to a first condition, such as a stopped or slowed
condition. The medical procedure is performed on the heart or
another organ. The stimulation of the nerve is stopped in order to
adjust the beating of the heart to a second condition, such as a
beating condition. The heart itself may also be stimulated to a
beating condition, such as by pacing. The stimulation of the nerve
may be continued in order to allow the medical procedure to be
continued. Systems and devices for performing the medical procedure
are also provided.
Inventors: |
Hill, Michael R. S.;
(Minneapolis, MN) ; Jahns, Scott E.; (Hudson,
WI) ; Keogh, James R.; (Maplewood, MN) ;
Euler, David E.; (Minnetonka, MN) ; Ujhelyi, Michael
R.; (Maple Grove, MN) ; Rakow, Nancy J.; (Oak
Grove, MN) ; Colson, Michael A.; (Chanhassen,
MN) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MS-LC340
MINNEAPOLIS
MN
55432-5604
US
|
Family ID: |
25508387 |
Appl. No.: |
10/777254 |
Filed: |
February 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10777254 |
Feb 12, 2004 |
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09964308 |
Sep 26, 2001 |
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6735471 |
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09964308 |
Sep 26, 2001 |
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09670369 |
Sep 26, 2000 |
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6532388 |
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09670369 |
Sep 26, 2000 |
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09433323 |
Nov 3, 1999 |
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6266564 |
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09433323 |
Nov 3, 1999 |
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09070506 |
Apr 30, 1998 |
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6006134 |
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09070506 |
Apr 30, 1998 |
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08640013 |
Apr 30, 1996 |
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Current U.S.
Class: |
607/3 |
Current CPC
Class: |
A61N 1/3629 20170801;
A61N 1/0556 20130101; A61N 1/36007 20130101; A61N 1/362 20130101;
A61N 1/0517 20130101; A61N 1/0519 20130101; A61N 1/3601 20130101;
A61N 1/36114 20130101; A61N 1/056 20130101; A61N 1/385 20130101;
A61M 5/14276 20130101 |
Class at
Publication: |
607/003 |
International
Class: |
A61N 001/18 |
Claims
We claim:
1. A method of performing a medical procedure, comprising:
esophageal stimulation of a vagal nerve to adjust the beating of a
heart to a first condition; performing the medical procedure on an
organ; reducing esophageal stimulation of the vagal nerve;
epicardial stimulation of the heart to adjust the beating of a
heart to a second condition; reducing epicardial stimulation of the
heart; esophageal stimulation of the nerve a subsequent time in
order to re-adjust the beating of the heart to the first condition;
and continuing the medical procedure.
2. The method of claim 1 wherein the esophageal stimulation is
stopped to achieve the second condition.
3. The method of claim 1 wherein the epicardial stimulation is
stopped to re-adjust the beating of the heart to the first
condition.
4. The method of claim 1 wherein the first condition is a stopped
condition.
5. The method of claim 1 wherein the first condition is a slowed
condition.
6. The method of claim 1 wherein the second condition is a beating
condition.
7. The method of claim 1 further comprising: delivering at least
one drug during the medical procedure.
8. The method of claim 7 wherein the drug is selected from the
group consisting of: a beta-blocker, a cholinergic agent, a
cholinesterase inhibitor, a calcium channel blocker, a sodium
channel blocker, a potassium channel agent, adenosine, an adenosine
receptor agonist, an adenosine deaminase inhibitor, dipyridamole, a
monoamine oxidase inhibitor, digoxin, digitalis, lignocaine, a
bradykinin agent, a serotoninergic agonist, an antiarrythmic agent,
a cardiac glycoside, a local anesthetic, atropine, a calcium
solution, an agent that promotes heart rate, an agent that promotes
heart contractions, dopamine, a catecholamine, an inotrope
glucagon, a hormone, forskolin, epinephrine, norepinephrine,
thyroid hormone, a phosphodiesterase inhibitor, prostacyclin,
prostaglandin, methylxanthine, a P.sub.2-purinoceptor agent, an
ischemia agent, and a delta opioid agonist.
9. The method of claim 8 wherein the drug is naturally
occurring
10. The method of claim 8 wherein the drug is chemically
synthesized.
11. The method of claim 1 wherein the medical procedure is selected
from the group consisting of: surgical procedures, non-surgical
procedures, endoscopic procedures, fluoroscopic procedures, stent
delivery procedures, aortic aneurysm repairs, cranial aneurysm
repairs, delivery of drugs, delivery of biological agents, cardiac
surgery with cardiopulmonary bypass circuits, cardiac surgery
without cardiopulmonary bypass circuits, brain surgery,
cardiograms, heart valve repair, heart valve replacement, MAZE
procedures, transmyocardial revascularization, CABG procedures,
beating heart surgery, vascular surgery, neurosurgery,
electrophysiology procedures, diagnostic ablation of arrhythmias,
therapeutic ablation of arrhythmias, endovascular procedures,
treatment of injuries to the liver, treatment of the spleen,
treatment of the heart, treatment of the lungs, treatment of major
blood vessels, non-invasive procedures, invasive procedures, and
port-access procedures.
12. A device for performing a medical procedure comprising: a
processor; an esophageal nerve stimulation electrode operatively
connected to the processor and arranged on an esophageal tube; and
a cardiac stimulation electrode operatively connected to the
processor, wherein the processor processes output from the nerve
stimulation electrode and adjusts output from the cardiac
stimulation electrode based on output from the nerve stimulation
electrode.
13. The device of claim 12 further comprising: drug delivery means
for delivering at least one drug during the medical procedure.
14. The device of claim 13 wherein the drug delivery means is
selected from the group consisting of: a spray, a cream, an
ointment, a medicament, a pill, a patch, a catheter, a cannula, a
needle and syringe, a pump, and an iontophoretic drug delivery
device.
15. The device of claim 12 wherein the cardiac stimulation
electrode is selected from the group consisting of: clip
electrodes, needle electrodes, probe electrodes, pacing electrodes,
epicardial electrodes, endocardial electrodes, patch electrodes,
intravascular electrodes, balloon-type electrodes, basket-type
electrodes, tape-type electrodes, umbrella-type electrodes,
suction-type electrodes, endoesophageal electrodes, transcutaneous
electrodes, intracutaneous electrodes, screw-type electrodes,
barb-type electrodes, bipolar electrodes, monopolar electrodes,
metal electrodes, wire electrodes and cuff electrodes.
16. The device of claim 12 further comprising: a respiratory
controller for controlling respiration.
17. The device of claim 12 wherein stimulation from the nerve
stimulation electrode occurs in an inverse relationship to
stimulation from the cardiac stimulation electrode.
18. The device of claim 12 further comprising: a drug pump for
delivering at least one drug, the drug pump operatively connected
to the processor wherein the processor adjusts the output of the
drug.
19. The device of claim 12 further comprising: a respiratory
controller for controlling respiration, the respiratory controller
operatively connected to the processor wherein the processor
adjusts the output of the respiratory controller.
20. A method of performing a medical procedure, comprising:
endotracheal stimulation of a vagal nerve to adjust the beating of
a heart to a first condition; performing the medical procedure on
an organ; reducing endotracheal stimulation of the vagal nerve;
esophageal stimulation of the heart to adjust the beating of a
heart to a second condition; reducing esophageal stimulation of the
heart; endotracheal stimulation of the nerve a subsequent time in
order to re-adjust the beating of the heart to the first condition;
and continuing the medical procedure.
21. The method of claim 20 wherein the endotracheal stimulation is
stopped to achieve the second condition.
22. The method of claim 20 wherein the esophageal stimulation is
stopped to re-adjust the beating of the heart to the first
condition.
23. The method of claim 20 wherein the first condition is a stopped
condition.
24. The method of claim 20 wherein the first condition is a slowed
condition.
25. The method of claim 20 wherein the second condition is a
beating condition.
26. The method of claim 20 further comprising: delivering at least
one drug during the medical procedure.
27. The method of claim 26 wherein the drug is selected from the
group consisting of: a beta-blocker, a cholinergic agent, a
cholinesterase inhibitor, a calcium channel blocker, a sodium
channel blocker, a potassium channel agent, adenosine, an adenosine
receptor agonist, an adenosine deaminase inhibitor, dipyridamole, a
monoamine oxidase inhibitor, digoxin, digitalis, lignocaine, a
bradykinin agent, a serotoninergic agonist, an antiarrythmic agent,
a cardiac glycoside, a local anesthetic, atropine, a calcium
solution, an agent that promotes heart rate, an agent that promotes
heart contractions, dopamine, a catecholamine, an inotrope
glucagon, a hormone, forskolin, epinephrine, norepinephrine,
thyroid hormone, a phosphodiesterase inhibitor, prostacyclin,
prostaglandin, methylxanthine, a P.sub.2-purinoceptor agent, an
ischemia agent, and a delta opioid agonist.
28. The method of claim 27 wherein the drug is naturally
occurring
29. The method of claim 27 wherein the drug is chemically
synthesized.
30. The method of claim 20 wherein the medical procedure is
selected from the group consisting of: surgical procedures,
non-surgical procedures, endoscopic procedures, fluoroscopic
procedures, stent delivery procedures, aortic aneurysm repairs,
cranial aneurysm repairs, delivery of drugs, delivery of biological
agents, cardiac surgery with cardiopulmonary bypass circuits,
cardiac surgery without cardiopulmonary bypass circuits, brain
surgery, cardiograms, heart valve repair, heart valve replacement,
MAZE procedures, transmyocardial revascularization, CABG
procedures, beating heart surgery, vascular surgery, neurosurgery,
electrophysiology procedures, diagnostic ablation of arrhythmias,
therapeutic ablation of arrhythmias, endovascular procedures,
treatment of injuries to the liver, treatment of the spleen,
treatment of the heart, treatment of the lungs, treatment of major
blood vessels, non-invasive procedures, invasive procedures, and
port-access procedures.
31. A device for performing a medical procedure comprising: a
processor; an endotracheal nerve stimulation electrode operatively
connected to the processor; and an esophageal cardiac stimulation
electrode operatively connected to the processor, wherein the
processor processes output from the nerve stimulation electrode and
adjusts output from the cardiac stimulation electrode based on
output from the nerve stimulation electrode.
32. The device of claim 31 further comprising: drug delivery means
for delivering at least one drug during the medical procedure.
33. The device of claim 31 wherein the drug delivery means is
selected from the group consisting of: a spray, a cream, an
ointment, a medicament, a pill, a patch, a catheter, a cannula, a
needle and syringe, a pump, and an iontophoretic drug delivery
device.
34. The device of claim 31 wherein the cardiac stimulation
electrode is arranged on an esophageal tube.
35. The device of claim 31 wherein the nerve stimulation electrode
is arranged on an endotracheal tube.
36. The device of claim 31 further comprising: a respiratory
controller for controlling respiration.
37. The device of claim 31 wherein stimulation from the nerve
stimulation electrode occurs in an inverse relationship to
stimulation from the cardiac stimulation electrode.
38. The device of claim 31 further comprising: a drug pump for
delivering at least one drug, the drug pump operatively connected
to the processor wherein the processor adjusts the output of the
drug.
39. The device of claim 31 further comprising: a respiratory
controller for controlling respiration, the respiratory controller
operatively connected to the processor wherein the processor
adjusts the output of the respiratory controller.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
09/964,308, Sep. 26, 2001, to inventors Hill et al., which is a
continuation-in-part of application Ser. No. 09/670,369, Sep. 26,
2000, to inventors Hill et al., now U.S. Pat. No. 6,532,388, which
is a continuation-in-part of application Ser. No. 09/433,323, Nov.
3, 1999, to inventors Hill and Jonkman, now U.S. Pat. No.
6,266,564, which is a continuation of application Ser. No.
09/070,506, Apr. 30, 1998, U.S. Pat. No. 6,006,134, to inventors
Hill and Jonkman, which is a continuation-in-part of application
Ser. No. 08/640,013, Apr. 30, 1996, now abandoned.
FIELD OF THE INVENTION
[0002] This invention relates to methods for performing a medical
procedure, especially a procedure during which it is necessary to
adjust the beating of the heart. More particularly, this invention
relates to methods and systems of stimulating a nerve in order to
modify the beating of a heart to allow a medical procedure to be
performed or for blood flow to be controlled.
BACKGROUND OF THE INVENTION
[0003] The current leading cause of death in the United States is
coronary artery disease in which the coronary arteries are blocked
by atherosclerotic plaques or deposits of fat. The typical
treatment to relieve a partially or fully blocked coronary artery
is coronary artery bypass graph (CABG) surgery.
[0004] CABG surgery, also known as "heart bypass" surgery,
generally entails using a graph to bypass the coronary obstruction.
The procedure is generally lengthy, traumatic and subject to
patient risks. Among the risk factors involved is the use of a
cardiopulmonary bypass (CPB) circuit, also known as a "heart-lung
machine," to pump blood and oxygenate the blood so that the
patient's heart may be stopped during the surgery.
[0005] Conventional CABG procedures are typically conducted on a
stopped heart while the patient is on a (CPB) circuit. A stopped
heart and a CPB circuit enables a surgeon to work in a bloodless,
still operative field. However, there are a number of problems
associated with CABG procedures performed while on CPB including
the initiation of a systemic inflammatory response due to
interactions of blood elements with the artificial material
surfaces of the CPB circuit and global myocardial ischemia due to
cardioplegic cardiac arrest. For these reasons, avoiding the use of
CPB or cardioplegic cardiac arrest may help minimize post-operative
complications.
[0006] One method, as disclosed in U.S. Pat. No. 5,651,378 to
inventors Matheny and Taylor and in U.S. Pat. No. 5,913,876 to
inventors Taylor et al., for facilitating coronary bypass surgery
on a beating heart and thereby avoid the use of CPB and
cardioplegic cardiac arrest includes stimulating the vagal nerve
electrically in order to temporarily stop or substantially reduce
the beating of the heart. This may be followed by pacing the heart
to start its beating.
[0007] Another method, as disclosed in two published PCT
applications, WO 99/09971 and WO 99/09973, both to inventor Puskas,
involves stopping the beating of the heart during coronary bypass
surgery using electrical stimulation of the vagal nerve in
combination with administration of drugs. Another method, as
disclosed in U.S. Pat. No. 6,060,454 to inventor Duhaylongsod,
involves stopping the beating of the heart during coronary bypass
surgery via the local delivery of drugs to the heart.
[0008] Although it is desirable to stop the heart for a period of
time in order to allow the surgeon to accomplish a required task
without interference from heart movement, i.e. a motionless
operative field, it is undesirable to have the heart stopped for
too long a period of time since the body needs, among other things,
a constant supply of oxygen. In fact, it is particularly important
to maintain sufficient blood flow, and therefore oxygen flow, to
the brain. Stopping the heart for prolonged periods of time may
cause damage to the patient.
[0009] It is thus important to be able to precisely control and
coordinate the amount and duration of stimulation to the vagal
nerve and the heart. One type of electrode arrangement that allows
such precise control is an electrode tube which is suitable for
insertion into a patient's trachea or esophagus. This arrangement
provides a configuration of electrodes which can not only stimulate
a variety of nerve fibers but may also be configured to stimulate
the patient's heart, ventilate the patient's lungs and/or control
pain during stimulation. This electrode arrangement also allows for
sensing or monitoring of various physiological processes.
[0010] It would be desirable therefore to provide a method for
controllably stopping or slowing the heart intermittently for
diagnostic and therapeutic purposes.
[0011] Additionally, it would be desirable to provide a method for
controllably stopping or slowing the heart intermittently in order
to control blood flow.
[0012] Additionally, it would be desirable to provide a method for
controllably stopping or slowing the heart intermittently in order
to perform a medical procedure on the heart or another organ.
[0013] Additionally, it would be desirable to provide a means for
coordinating stimulation of the heart and other body
components.
[0014] Additionally, it would be desirable to provide a means for
evaluating the stimulation output from a variety of electrodes to
determine the best stimulation configuration.
SUMMARY OF THE INVENTION
[0015] One aspect of the present invention provides a method for
evaluating stimulation during a medical procedure. A site is
stimulated with a first electrode arrangement. The stimulation at
the site is then evaluated to provide a first stimulation value.
The first electrode arrangement may comprise one or more electrodes
such as nerve stimulation electrodes, endotracheal electrodes,
endoesophageal electrodes, intravascular electrodes, transcutaneous
electrodes, intracutaneous electrodes, balloon-type electrodes,
basket-type electrodes, umbrella-type electrodes, tape-type
electrodes, suction-type electrodes, screw-type electrodes,
barb-type electrodes, bipolar electrodes, monopolar electrodes,
metal electrodes, wire electrodes, patch electrodes, cuff
electrodes, clip electrodes, needle electrodes, probe electrodes,
cardiac stimulation electrodes, pacing electrodes and epicardial
electrodes.
[0016] The method may also involve stimulating the site with a
subsequent electrode arrangement and evaluating stimulation to
provide a subsequent stimulation value. The first stimulation and
subsequent stimulation values may be continued with the electrode
arrangement associated with the best stimulation value. The
subsequent electrode arrangement may comprise one or more
electrodes such as nerve stimulation electrodes, endotracheal
electrodes, endoesophageal electrodes, intravascular electrodes,
transcutaneous electrodes, intracutaneous electrodes, balloon-type
electrodes, basket-type electrodes, umbrella-type electrodes,
tape-type electrodes, suction-type electrodes, screw-type
electrodes, barb-type electrodes, bipolar electrodes, monopolar
electrodes, metal electrodes, wire electrodes, patch electrodes,
cuff electrodes, clip electrodes, needle electrodes, probe
electrodes, cardiac stimulation electrodes, pacing electrodes and
epicardial electrodes.
[0017] Another aspect of the present invention provides a method of
performing a medical procedure. A nerve is stimulated with a first
electrode arrangement to adjust the beating of a heart to a first
condition. Stimulation is evaluated from the first electrode
arrangement to provide a first stimulation value. The nerve is then
stimulated with a subsequent electrode arrangement and stimulation
is evaluated from the subsequent electrode arrangement to provide a
subsequent stimulation value. A desired electrode arrangement is
selected based on the first stimulation value and the subsequent
stimulation value and the nerve is stimulated with the desired
electrode arrangement. The first and the subsequent electrode
arrangements may comprise one or more electrodes such as nerve
stimulation electrodes, endotracheal electrodes, endoesophageal
electrodes, intravascular electrodes, transcutaneous electrodes,
intracutaneous electrodes, balloon-type electrodes, basket-type
electrodes, umbrella-type electrodes, tape-type electrodes,
suction-type electrodes, screw-type electrodes, barb-type
electrodes, bipolar electrodes, monopolar electrodes, metal
electrodes, wire electrodes, patch electrodes, cuff electrodes,
clip electrodes, needle electrodes, probe electrodes, cardiac
stimulation electrodes, pacing electrodes and epicardial
electrodes.
[0018] The medical procedure may be performed on an organ.
Stimulation of the nerve may then be reduced or stopped to adjust
the beating of a heart to a second condition. The nerve may then be
stimulated a subsequent time to readjust the beating of the heart
to the first condition and the medical procedure then continued.
The nerve may be stimulated, for example, using transvascular
stimulation, endotrachael stimulation, and/or endoesophageal
stimulation. The first condition may be a stopped or slowed
condition. The second condition may be a beating condition. The
heart may be stimulated to adjust the beating of the heart to the
second condition. For example, the heart may be stimulated with a
first cardiac electrode arrangement to adjust the beating of the
heart to the second condition. Stimulation from the first cardiac
electrode arrangement may be evaluated to provide a first cardiac
stimulation value. The heart may then be stimulated with a
subsequent cardiac electrode arrangement and stimulation from this
arrangement may then be evaluated to provide a subsequent cardiac
stimulation value. A desired cardiac electrode arrangement may then
be selected based on the first cardiac stimulation value and the
subsequent cardiac stimulation value and the heart may be
stimulated with the desired cardiac electrode arrangement. The
first and subsequent cardiac electrode arrangements may be one or
more electrodes such as nerve stimulation electrodes, cardiac
stimulation electrodes, clip electrodes, needle electrodes, probe
electrodes, pacing electrodes, patch electrodes, intravascular
electrodes, transcutaneous electrodes, intracutaneous electrodes,
balloon-type electrodes, basket-type electrodes, umbrella-type
electrodes, tape-type electrodes, suction-type electrodes,
screw-type electrodes, barb-type electrodes, bipolar electrodes,
monopolar electrodes, metal electrodes, wire electrodes,
electrodes, epicardial electrodes, endotracheal electrodes and
endoesophageal electrodes.
[0019] The method may also include delivering a drug such as a
beta-blocker, a cholinergic agent, a cholinesterase inhibitor, a
calcium channel blocker, a sodium channel blocker, a potassium
channel agent, adenosine, an adenosine receptor agonist, an
adenosine deaminase inhibitor, dipyridamole, a monoamine oxidase
inhibitor, digoxin, digitalis, lignocaine, a bradykinin agent, a
serotoninergic agonist, an antiarrythmic agent, a cardiac
glycoside, a local anesthetic, atropine, a calcium solution, an
agent that promotes heart rate, an agent that promotes heart
contractions, dopamine, a catecholamine, an inotrope glucagon, a
hormone, forskolin, epinephrine, norepinephrine, thyroid hormone, a
phosphodiesterase inhibitor, prostacyclin, prostaglandin,
methylxanthine, a P.sub.2-purinoceptor agent, an ischemia agent,
and a delta opioid agonist may be delivered during the procedure.
The drug may be naturally occurring or chemically synthesized.
[0020] The nerve may be a nerve such as a vagal nerve, a carotid
sinus nerve, a fat pad.
[0021] The medical procedure may be surgical procedures,
non-surgical procedures, endoscopic procedures, fluoroscopic
procedures, stent delivery procedures, aortic aneurysm repairs,
cranial aneurysm repairs, delivery of drugs, delivery of biological
agents, cardiac surgery with cardiopulmonary bypass circuits,
cardiac surgery without cardiopulmonary bypass circuits, brain
surgery, cardiograms, heart valve repair, heart valve replacement,
MAZE procedures, revascularization procedures, transmyocardial
revascularization, percutaneous myocardial revascularization, CABG
procedures, anastomosis procedures, beating heart surgery, vascular
surgery, neurosurgery, brain surgery, electrophysiology procedures,
diagnostic procedures, therapeutic procedures, ablation procedures,
ablation of arrhythmias, endovascular procedures, treatment of the
liver, treatment of the spleen, treatment of the heart, treatment
of the lungs, treatment of major blood vessels, non-invasive
procedures, invasive procedures, port-access procedures, imaging
procedures, CAT scan procedures, MRI procedures, gene therapy
procedures, cellular therapy procedures, cancer therapy procedures,
radiation therapy procedures, transplantation procedures, coronary
angioplasty procedures, atherectomy procedures and atherosclerotic
plaque removal procedures.
[0022] Another aspect of the present invention provides a device
for performing a medical procedure. The device includes a first
electrode arrangement operatively arranged on a stimulation tube
and a second electrode arrangement operatively arranged on a
stimulation collar. The first and the second electrode arrangements
may comprise one or more electrodes such as nerve stimulation
electrodes, endotracheal electrodes, endoesophageal electrodes,
intravascular electrodes, transcutaneous electrodes, intracutaneous
electrodes, balloon-type electrodes, basket-type electrodes,
umbrella-type electrodes, tape-type electrodes, suction-type
electrodes, screw-type electrodes, barb-type electrodes, bipolar
electrodes, monopolar electrodes, metal electrodes, wire
electrodes, patch electrodes, cuff electrodes, clip electrodes,
needle electrodes, probe electrodes, cardiac stimulation
electrodes, pacing electrodes and epicardial electrodes. The device
may also include a processor for evaluating stimulation from a set
of electrodes, the pair of electrodes comprising at least one
electrode from the stimulation tube and at least one electrode from
the stimulation collar.
[0023] Another aspect of the present invention provides a system
for performing a medical procedure. The system includes a first
electrode arrangement operatively arranged on a stimulation tube
and a second electrode arrangement operatively arranged on a
stimulation collar, a processor for evaluating stimulation from a
set of electrodes, the pair of electrodes comprising at least one
electrode from the stimulation tube and at least one electrode from
the stimulation collar and a controller for controlling stimulation
from the set of electrodes. The first and the second electrode
arrangements may comprise one or more electrodes such as nerve
stimulation electrodes, endotracheal electrodes, endoesophageal
electrodes, intravascular electrodes, transcutaneous electrodes,
intracutaneous electrodes, balloon-type electrodes, basket-type
electrodes, umbrella-type electrodes, tape-type electrodes,
suction-type electrodes, screw-type electrodes, barb-type
electrodes, bipolar electrodes, monopolar electrodes, metal
electrodes, wire electrodes, patch electrodes, cuff electrodes,
clip electrodes, needle electrodes, probe electrodes, cardiac
stimulation electrodes, pacing electrodes and epicardial
electrodes.
[0024] The system may also include drug delivery means such as a
spray, a cream, an ointment, a medicament, a pill, a patch, a
catheter, a cannula, a needle and syringe, a pump, and an
iontophoretic drug delivery device for delivering drugs during the
medical procedure.
[0025] Another aspect of the present invention provides a method of
performing heart surgery. A nerve is stimulated with a first
electrode arrangement to reduce the beating of a heart. Stimulation
from the first electrode arrangement is evaluated to provide a
first stimulation value. The nerve is then stimulated with a
subsequent electrode arrangement and the stimulation is evaluated
to provide a subsequent stimulation value. A desired electrode
arrangement is selected based on the first stimulation value and
the subsequent stimulation value and the nerve is stimulated with
the desired electrode arrangement. The heart is then operated upon.
Stimulation of the nerve is then stopped and the heart is
stimulated to cause beating of the heart. The nerve is then
re-stimulated to re-inhibit beating of the heart and the surgery is
continued. The heart may also be stimulated with a first cardiac
electrode arrangement to adjust the beating of the heart to the
second condition. Stimulation from the first cardiac electrode
arrangement may be evaluated to provide a first cardiac stimulation
value. The heart may then be stimulated with a subsequent cardiac
electrode arrangement and stimulation from this arrangement may be
evaluated to provide a subsequent cardiac stimulation value. A
desired cardiac electrode arrangement may then be selected based on
the first cardiac stimulation value and the subsequent cardiac
stimulation value and the heart may be stimulated with the desired
cardiac electrode arrangement.
[0026] The foregoing, and other, features and advantages of the
invention will become further apparent from the following detailed
description of the presently preferred embodiments, read in
conjunction with the accompanying drawings. The detailed
description and drawings are merely illustrative of the invention
rather than limiting, the scope of the invention being defined by
the appended claims in equivalence thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a schematic view of one embodiment of a
stimulation system in accordance with the present invention;
[0028] FIG. 2 is a schematic view of one embodiment of an electrode
device in accordance with the present invention;
[0029] FIG. 3 is a schematic view of one embodiment of an electrode
device in accordance with the present invention;
[0030] FIG. 4 is a schematic view of one embodiment of an electrode
device in accordance with the present invention;
[0031] FIG. 5 is a schematic view of one embodiment of an electrode
device in accordance with the present invention;
[0032] FIG. 6 is a schematic view of one embodiment of an electrode
device in accordance with the present invention;
[0033] FIG. 7 is a flow diagram of one embodiment of a method of
evaluating stimulation during a medical procedure in accordance
with the present invention;
[0034] FIG. 8 is a flow diagram of one embodiment of a method of
performing a medical procedure in accordance with the present
invention; and
[0035] FIG. 9 is a timeline view of one embodiment of a system for
controllably stopping or slowing the heart intermittently in a
patient during a medical procedure in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0036] FIG. 1 shows a schematic view of one embodiment of a
stimulation system for performing a medical procedure in accordance
with the present invention at 200. Stimulation system 200 may
include a nerve stimulator 210, and a cardiac stimulator 220.
System 200 may also feature a controller 230 and a breathing
regulator 240. System 200 may also feature pain relieving
electrodes 260 and monitoring electrodes 270.
[0037] In one embodiment, nerve stimulator 210 may be used to
electrically manipulate cardiac rhythm by stimulating the vagus
nerve. This vagal stimulation may produce asystole (slowing or
stopping of the heart's beating.) Once this induced asystole is
stopped, i.e. once the vagal stimulation is stopped, the heart may
be allowed to return to its usual cardiac rhythm. Alternatively,
the heart may be paced with an electrical pacing system, thereby
maintaining a normal cardiac output. Vagal stimulation, alone or in
combination with electrical pacing, may be used selectively and
intermittently to allow a surgeon to perform a medical procedure
during intermittent periods of asystole.
[0038] It is known that stimulation of the vagus nerve can reduce
the sinus rate, as well as prolong AV conduction time or, if
stimulation energies are high enough, induce AV node block. Use of
vagal nerve stimulation to treat supraventricular arrhythmias and
angina pectoris is disclosed in the article "Vagal Tuning" by
Bilgutay et al., Journal of Thoracic and Cardiovascular Surgery,
Vol. 56, No. 1, July, 1968, pp. 71-82. It is also known that
stimulation of the carotid sinus nerve produces a similar result,
as disclosed in the article "Carotid Sinus Nerve Stimulation in the
Treatment of Angina Pectoris and Supraventricular Tachycardia" by
Braunwald et al., published in California Medicine, Vol. 112, pp.
41-50, March, 1970.
[0039] As set forth in "Functional Anatomy of the Cardiac Efferent
Innervation" by Randall et al., in Neurocardiology, edited by
Kulbertus et al, Futura Publishing Co., 1988, direct surgical
excision of the fat pad associated with the SA node affects the
functioning of the SA node without significantly affecting the AV
node. Similarly, excision of the fat pad associated with the AV
node affects functioning of the AV node without significantly
affecting the SA node.
[0040] As set forth in the article "Parasympathetic Postganglionic
Pathways to the Sinoatrial Node", Bluemel et al., Am. J. Physiol.
259, (Heart Circ. Physiol. 28) H1504-H1510, 1990, stimulation of
the fat pad associated with the SA node results in slowing of the
sinus rate without the accompanying prolongation of AV conduction
time which normally results from vagal nerve stimulation. The
article also indicates that stimulation of the fat pad associated
with the AV node is believed to produce corresponding effects
limited to the AV node, i.e., extension of the AV conduction time
without concurrent slowing of the sinus rate.
[0041] As set forth in the article "Neural Effects on Sinus Rate
and Atrial Ventricular Conduction Produced by Electrical
Stimulation From a Transvenous Electrode Catheter in the Canine
Right Pulmonary Artery" by Cooper et al., published in Circulation
Research, Vol. 46, No. 1, January, 1980, pp. 48-57, the fat pads
associated with both the AV node and the SA node may be stimulated
by means of electrodes located in the right pulmonary artery. The
results obtained include both a depression of the sinus rate and a
prolongation of the AV conduction time in response to continuous
stimulation at 2-80 Hz at up to 50 ma.
[0042] Generally in healthy individuals, the SA node functions as
the pacemaker. Normal heart rhythm associated with the SA node is
typically referred to as sinus rhythm. When the SA node fails, the
AV node generally takes over creating a heart rate of approximately
35 to 60 beats per minute. Heart rhythm associated with the AV node
is typically referred to as nodal rhythm. When the AV node itself
is blocked or injured, a new even slower pacemaker site may form at
the junction of the AV node and the His bundle. Heart rhythm
associated with this junction is typically referred to as
junctional escape rhythm. When this junction site is inhibited, the
Purkinje fibers in the His bundle or below may act as a pacemaker
creating a heart rate of approximately 30 beats per minute. Heart
rhythm associated with the Purkinje fibers is typically referred to
as idioventricular rhythm.
[0043] In one embodiment of the present invention, nerve stimulator
210 may be used to electrically manipulate cardiac rhythm by
stimulating the carotid sinus nerve, the fat pad associated with
the SA node, the fat pad associated with the AV node, the junction
of the AV node and the His bundle and/or the Purkinje fibers.
[0044] In one embodiment of the present invention, nerve stimulator
210 may be used alone or in combination with other heart rate
inhibiting agents to temporarily stop or slow the beating heart,
thereby eliminating or reducing heart motion and/or blood flow
during a medical procedure. For example, the present invention may
be used to eliminate or reduce motion in the anastomosis field
during CABG procedures such that a facilitated anastomosis
procedure may be performed safely and effectively. The number of
occasions that the vagal nerve may be stimulated depends on the
type of medical procedure to be performed. Likewise, the type of
medical procedure to be performed will dictate the duration of the
individual electrical stimulations.
[0045] Nerve stimulator 210 may be powered by AC current, DC
current or the may be battery powered either by a disposable or
re-chargeable battery. Nerve stimulator 210 may be configured to
synchronize activation and deactivation of breathing regulator 240
with vagal stimulation, thereby minimizing or eliminating unwanted
heart and chest motion associated with the patient's breathing.
Nerve stimulator 210 may be connected to a surgeon controlled
switch box. A switch may be incorporated in or on one of the
surgeon's instruments, such as surgical site retractor, or any
other location easily and quickly accessed by the surgeon for
regulation of the nerve stimulator 210 by the surgeon. The switch
may be, for example, a hand switch, a foot switch, or a
voice-activated switch comprising voice-recognition
technologies.
[0046] A visual and/or audible signal used to alert a surgeon to
the completion or resumption of stimulation may be incorporated
into nerve stimulator 210. For example, a beeping tone or flashing
light that increases in frequency as the stimulation period should
end or begin may be used.
[0047] Nerve stimulator 210 may be slaved to cardiac stimulator 220
or cardiac stimulator 220 may be slaved to nerve stimulator 210.
For example, the output of cardiac stimulator 220 may be off
whenever the output of nerve stimulator 210 is on. Software
controlling cardiac stimulator 220 may be designed to automatically
commence cardiac pacing if the heart does not resume beating within
a pre-determined interval after cessation of vagal nerve
stimulation. In addition, the software controlling nerve stimulator
210 may be designed to automatically stop vagal nerve stimulation
if the heart has been stopped for too long.
[0048] The application of an electrical stimulus to the right or
left vagal nerve may include, but is not limited to bipolar and/or
monopolar techniques. Nerve stimulation electrodes may be
positioned within the body of a patient, positioned on the skin of
a patient and/or in combinations thereof. Electrical stimulation
may be carried out on the right vagal nerve, the left vagal nerve
or to both nerves simultaneously or sequentially. The present
invention may include various electrodes, suitable for vagal nerve
stimulation to temporarily stop or slow the beating heart alone or
in combination with other heart rate inhibiting agents.
[0049] Various techniques such as ultrasound, fluoroscopy and
echocardiography may be used to facilitate positioning of
electrodes. In one embodiment of the present invention, the
location of the vagal nerve stimulation electrodes is chosen to
elicit maximum bradycardia effectiveness while minimizing current
spread to adjacent tissues and vessels and to prevent the induction
of post stimulation tachycardia. Furthermore, a non-conductive
material such as plastic may be employed to sufficiently enclose
the electrodes of all the configurations to shield them from the
surrounding tissues and vessels, while exposing their confronting
edges and surfaces for positive contact with selected tissues.
[0050] Nerve stimulation electrodes of nerve stimulator 210 may be,
for example, endotracheal electrodes or esophageal electrodes.
Stimulation electrodes may also be electrodes on a sheath or
introducer. The sheath or introducer may or may not be splittable.
The sheath or introducer may comprise various materials including
polymeric materials and metallic materials. The sheath or
introducer may be used, for example, with therapeutic or diagnostic
catheters. For example, one type of catheter the sheath or
introducer may be used with is a venous catheter. The sheath or
introducer may comprise one or more electrodes. The electrodes may
be arranged, for example, on the surface of the sheath or
introducer in a longitudinal pattern or in a circumferential
pattern. These electrodes may comprise an electrically conducting
material, for example, metal paint, metal tape, metal strips, metal
buttons, metal foil, metal wire and/or conductive plastic. The
electrodes may be used in a monopolar and/or bipolar arrangement.
For example, two electrodes on the sheath or introducer may be used
in a bipolar fashion or one electrode on the sheath or introducer
may be used in a monopolar fashion in combination with an external
skin electrode. The sheath comprising one or more electrodes may be
used with a variety of different medical instruments, e.g.,
catheters, probes, sensors, needles and the like, to provide the
stimulation, pacing, pain control and/or sensing capabilities to
the instrument.
[0051] Nerve stimulation electrodes may also be electrodes on a
cannula. The cannula may comprise various materials including
polymeric materials and metallic materials. In addition, to
stimulation, the cannula may be used, for example, for therapeutic
or diagnostic purposes. The cannula may comprise one or more
balloons. One or more electrodes may be arranged, for example, on
the surface of the cannula in a longitudinal pattern or in a
circumferential pattern. The electrodes may also be arranged on one
or more balloons attached to the cannula. The electrodes may
comprise an electrically conducting material, for example, metal
paint, metal tape, metal strips, metal buttons, metal foil, metal
wire and/or conductive plastic. The electrodes may be used in a
monopolar and/or bipolar arrangement. For example, two electrodes
on the cannula may be used in a bipolar fashion or one electrode on
the cannula may be used in a monopolar fashion in combination with
an external skin electrode.
[0052] FIG. 2 shows one embodiment of an electrode device
comprising endotracheal electrodes in accordance with the present
invention at 10A. Electrode device 10A may comprise a tube 100
suitable for insertion through a patient's nose or mouth and into
the patient's trachea.
[0053] Electrode device 10A may include a first electrode
arrangement attached to tube 100. This electrode arrangement may be
used to accomplish stimulation on such body components as nerves,
muscles, the heart, and the lungs. This stimulation may be used to
controllably stop or start an organ such as the heart or lungs or
to ease pain. The electrode arrangement may also be used to sense
or monitor physiological functions.
[0054] Tube 100 may comprise a flexible, non-electrically
conducting tube having a proximal end 11 and a distal end 12. Tube
100 may be made of a material selected for its stiffness and
flexibility to allow tube 100 to conform readily to the shape of
the patient's trachea with minimal trauma to tissue. For example,
silicone rubber, polyurethane or other polymers or materials may be
used. The outer diameter and length of tube 100 may vary depending
upon size of the patient for whom it is intended. Lubricating gels
or creams may be used during placement of the device. These
lubricating gels or creams may or may not be conductive. Tube 100
may include a biocompatible coating, for example, a slip coating
for easier insertion.
[0055] Tube 100 may also include main lumen 20 for transporting
gases to and from the lungs. Main lumen 20 runs from the proximal
end of tube 100 to the distal end of tube 100. Tube 100 may be
connected at proximal end 11 to a breathing regulator, which
injects and withdraws air from the lungs. Proximal end 11 may
include a standard tracheal tube adapter for anesthesia gas
connection. Proximal end 11 may include a stop which engages the
face of the patient so as to prevent further insertion when the
distal end is in the proper location.
[0056] An inflatable cuff 13 may be located near distal end 12 of
tube 100. Inflatable cuffs are typically used on tracheal tubes to
prevent air from escaping by passing between the tube and the
trachea wall. Inflatable cuffs may also be used to stabilize the
location of electrodes in the trachea. Inflatable cuff 13 is shown
in an deflated condition in FIG. 2 and can be inflated by use of a
cuff-inflating conduit 15, which may be attached to a source of
compressed gas (e.g., air) or fluid (e.g., saline). Cuff-inflating
conduit 15 may be a lumen which communicates with the interior of
the cuff through a port in the tube. Inflatable cuff 13 may be made
of a very soft rubber-like material well known in the catheter art.
A check valve may be used to control inflation and deflation of the
cuff. Tube 100 may or may not include one or more cuffs. A single
inflation lumen in communication with multiple cuffs may be used to
inflate the cuffs or each cuff may have its own inflation lumen.
Tube 100 may include positioning marks or other positioning
technologies.
[0057] Associated with tube 100 is an arrangement of electrodes 16.
These electrodes may comprise an electrically conducting material,
for example, metal paint, metal tape, metal strips, metal buttons,
metal foil, metal wire and/or conductive plastic. The electrodes
may be ring electrodes, wire electrodes, button electrodes and/or
foil electrodes. The electrodes may be used in a monopolar and/or
bipolar arrangement. For example, two electrodes on tube 100 may be
used in a bipolar fashion or one electrode on tube 100 may be used
in a monopolar fashion in combination with an external skin
electrode. The electrodes may be arranged parallel to the axis of
tube 100 and/or the electrodes may be arranged circumferentially to
the axis of tube 100. Tube 100 may comprise one or more electrodes.
The electrodes may be located proximal to an inflatable cuff,
distal to an inflatable cuff, on one or more inflatable cuffs
and/or combinations thereof. For example, in FIG. 2, electrode
arrangement 16 comprises an array of electrodes located on the
outer surface of inflatable cuff 13. Placement of electrodes on an
inflatable cuff may help the electrodes make improved contact with
the inner surface of the trachea when the cuff is inflated.
[0058] FIG. 3 shows one embodiment of an electrode device
comprising endotracheal electrodes in accordance with the present
invention at 10B. Electrode device 10B may comprise tube 100, for
example, as described above, and a collar 101. Collar 101 may be
suitable for external placement on a portion of the body such as,
for example, around the neck. Electrode device 10B may include a
first electrode arrangement attached to tube 100 and a second
electrode arrangement attached to collar 101. These electrode
arrangements may be used to accomplish stimulation on such body
components as nerves, muscles, the heart, and the lungs. This
stimulation may be used to controllably stop or start an organ such
as the heart or lungs or to ease pain. The electrodes may also be
used to sense or monitor physiological functions.
[0059] Collar 101 may comprise a flexible, non-electrically
conducting material selected for its stiffness and flexibility to
allow collar 101 to conform readily to the shape of the patient's
neck. The collar may be adjustable to allow it to fit appropriately
the neck size of the patient for whom it is intended. Associated
with collar 101 is an arrangement of electrodes 116. These
electrodes may comprise an electrically conducting material, for
example, metal paint, metal tape, metal strips, metal buttons,
metal foil, metal wire and/or conductive plastic. The electrodes
may be wire electrodes, button electrodes and/or foil electrodes.
The electrodes may be arranged circumferentially around the neck of
a patient. Collar 101 may comprise one or more electrodes.
Conductive gels or creams may be used in combination with the
collar to help improve electrical contact of electrodes 116 with
the body of the patient.
[0060] FIG. 4 shows one embodiment of an electrode device
comprising endotracheal electrodes in accordance with the present
invention at 10C. Electrode device 10C may comprise tube 100, for
example, as described above, and one or more external electrodes
102. Electrodes 102 may be suitable for external placement on a
portion of the body such as, for example, on the neck or chest.
Electrode device 10C may include a first electrode arrangement
attached to tube 100 and a second electrode arrangement external to
the patient's body, for example external electrode 102. Electrode
arrangement 102 may comprise one or more typical external
electrodes, for example skin or patch electrodes. The first and
second electrode arrangements may be used to accomplish stimulation
on such body components as nerves, muscles, the heart, and the
lungs. This stimulation may be used to controllably stop or start
an organ such as the heart or lungs or to ease pain. The electrodes
may also be used to sense or monitor physiological functions.
[0061] In FIG. 4, tube 100 is shown comprising an arrangement of
metal wire electrodes 16 located on the outer surface of inflatable
cuff 13. In this particular embodiment, electrodes 16 are shown as
wires that run from a location between the two tube ends 11 and 12
toward distal end 12 in a direction parallel to the tube's central
axis. Each electrode wire may have a first portion, located between
proximal end 11 and distal end 12, and insulated against electrical
contact. Each electrode may also have a second wire portion located
on outer surface of cuff 13. Each second wire portion located on
outer surface of cuff 13 is uninsulated and capable of forming an
electrical contact. This contact may be formed with a body
component, such as, for example adjacent muscles or nerves.
[0062] Tube 100 comprising at least two electrodes may be used in a
bipolar fashion without the use of one or more external electrodes.
For example, tube 100 may be used without the use of collar 101 or
external electrode 102. Tube 100 comprising one or more electrodes
may be used in a monopolar fashion with the use of one or more
external electrodes, for example collar 101 or external electrode
102. In addition, electrodes of devices 10A, 10B and 10C, for
example, may comprise any means capable of forming electrical
contact with, for example, nerve stimulator 210, such as connecting
plugs, alligator clips or insulated wires with bared ends.
[0063] FIG. 5 shows one embodiment of an electrode device
comprising esophageal electrodes in accordance with the present
invention at 10D. Electrode device 10D may comprise a tube 103
suitable for insertion through a patient's nose or mouth and into
the patient's esophagus. Electrode device 10D may comprise one or
more external electrodes 102. Electrodes 102 may be suitable for
external placement on a portion of the body such as, for example,
on the neck or chest. Electrode device 10D may include a first
electrode arrangement attached to tube 103 and a second electrode
arrangement external to the patient's body, for example external
electrode 102. Electrode arrangement 102 may comprise one or more
typical external electrodes, for example skin or patch electrodes.
The first and second electrode arrangements may be used to
accomplish stimulation on such body components as nerves, muscles,
the heart, and the lungs. This stimulation may be used to
controllably stop or start an organ such as the heart or lungs or
to ease pain. The electrodes may also be used to sense or monitor
physiological functions.
[0064] Tube 103 may comprise a flexible, non-electrically
conducting tube having a proximal end 31 and a distal end 32. Tube
103 may be made of a material selected for its stiffness and
flexibility to allow tube 103 to conform readily to the shape of
the patient's esophagus with minimal trauma to tissue. For example,
silicone rubber, polyurethane or other polymers or materials may be
used. The outer diameter and length of tube 103 may vary depending
upon size of the patient for whom it is intended. Lubricating gels
or creams may be used during placement of the device. These
lubricating gels or creams may or may not be conductive. Tube 103
may include a biocompatible coating, for example, a slip coating
for easier insertion. Tube 103 may include positioning marks or
other positioning technologies.
[0065] Associated with tube 103 is an arrangement of electrodes 16.
These electrodes may comprise an electrically conducting material,
for example, metal paint, metal tape, metal strips, metal buttons,
metal foil, metal wire and/or conductive plastic. The electrodes
may be ring electrodes, wire electrodes, button electrodes and/or
foil electrodes. The electrodes may be used in a monopolar and/or
bipolar arrangement. For example, two electrodes on tube 103 may be
used in a bipolar fashion or one electrode on tube 103 may be used
in a monopolar fashion in combination with an external skin
electrode 102. The electrodes may be arranged parallel to the axis
of tube 103 and/or the electrodes may be arranged circumferentially
to the axis of tube 103. Tube 103 may comprise one or more
electrodes. The electrodes may be located proximal to an inflatable
cuff or hole, distal to an inflatable cuff or hole, on one or more
inflatable cuffs and/or combinations thereof. For example, in FIG.
5, electrode arrangement 16 comprises an array of wire electrodes
wrapped around the outer surface of tube 103 and arranged around
multiple holes 14.
[0066] One or more holes 14 in tube 103 in the area of the
electrodes 16 provides a means of ensuring better electrical
contact with the esophageal wall and electrodes 16 when suction is
introduced through suction conduit 18. Suction conduit 18 may be
attached to a vacuum source. Suction conduit 18 may be a lumen
which communicates with one or more holes 14 through a port in tube
103. A variety of securing means besides holes 14 may be used for
improving electrical contact between electrodes and esophageal
wall, for example suction pods or a sticky biocompatible substance
may be used.
[0067] FIG. 6 shows one embodiment of an electrode device
comprising esophageal electrodes in accordance with the present
invention at 10E. Electrode device 10E may comprise a tube 103
suitable for insertion through a patient's nose or mouth and into
the patient's esophagus. Electrode device 10D may comprise one or
more external electrodes 102 as described above.
[0068] As shown in FIG. 6, an inflatable cuff 13 may be located
near distal end 32 of tube 103. Inflatable cuff 13 may be used to
stabilize the location of electrodes in the esophagus. Inflatable
cuff 13 is shown in an inflated condition in FIG. 5 and can be
inflated and deflated by use of a cuff-inflating conduit 15, which
may be attached to a source of compressed gas (e.g., air) or fluid
(e.g., saline). Cuff-inflating conduit 15 may be a lumen which
communicates with the interior of the cuff through a port in the
tube. Inflatable cuff 13 may be made of a very soft rubber-like
material well known in the catheter art. A check valve may be used
to control inflation and deflation of the cuff. Tube 103 may or may
not include one or more cuffs. A single inflation lumen in
communication with multiple cuffs may be used to inflate the cuffs
or each cuff may have its own inflation lumen. Placement of
electrodes 16 on inflatable cuff 13 may help the electrodes make
improved contact with the inner surface of the esophagus when the
cuff is inflated. Tube 103 may include positioning marks or other
positioning technologies.
[0069] Tube 103 comprising at least two electrodes may be used in a
bipolar fashion without the use of one or more external electrodes.
For example, tube 103 may be used without the use of external
electrode 102. Tube 103 comprising one or more electrodes may be
used in a monopolar fashion with the use of one or more external
electrodes, for example external electrode 102. In addition,
electrodes of devices 10D and 10E, for example, may comprise any
means capable of forming electrical contact with, for example,
nerve stimulator 210, such as connecting plugs, alligator clips or
insulated wires with bared ends.
[0070] System 200 may also include cardiac stimulator 220 which may
be used to stimulate the heart as desired. As with nerve stimulator
210, cardiac stimulator 220 may be intermittently stopped and
started to allow the surgeon to perform individual steps of a
medical procedure.
[0071] Cardiac stimulator 220 may further comprise a conventional
ventricular demand pacer or dual chamber (atrial-ventricular)
pacer. Cardiac stimulator 220 may be powered by AC current, DC
current or may be battery powered either by a disposable or
re-chargeable battery. Cardiac stimulator 220 may be configured to
synchronize activation and deactivation of breathing regulator 240
with pacing, thereby minimizing or eliminating unwanted heart and
chest motion associated with the patient's breathing. Cardiac
stimulator 220 may also comprise any conventional pacing device
suitable for ventricular demand pacing.
[0072] Cardiac stimulator 220 may be combined in a single unit with
a switch box. Cardiac stimulator 220 may comprise a surgeon
controlled switch box. A switch may be incorporated in or on one of
the surgeon's instruments, such as surgical site retractor, or any
other location easily and quickly accessed by the surgeon for
regulation of the cardiac stimulator by the surgeon. The switch may
be, for example, a hand switch, a foot switch, or a voice-activated
switch comprising voice-recognition technologies. A single switch
may be used to regulate both cardiac stimulator 220 and nerve
stimulator 210.
[0073] A visual and/or audible signal used to prepare a surgeon for
the resumption of pacing may be incorporated into cardiac
stimulator 220. For example, a beeping tone or flashing light that
increases in frequency as the pacing period ends may be used. A
single signaling method or device may be used for both cardiac
stimulator 220 and nerve stimulator 210.
[0074] Cardiac stimulator 220 may comprise any type of electrodes
suitable for stimulating the heart, for example, non-invasive
electrodes, e.g., clips, or invasive electrodes, e.g., needles or
probes may be used. Cardiac stimulation electrodes may be
positioned through a thoracotomy, sternotomy, endoscopically
through a percutaneous port, through a stab wound or puncture,
through a small incision in the chest, placed on the chest or in
combinations thereof. The present invention may also use various
electrodes, catheters and electrode catheters suitable for pacing
the heart, e.g., epicardial, endocardial, patch-type,
intravascular, balloon-type, basket-type, umbrella-type, tape-type
electrodes, suction-type, pacing electrodes, endotracheal
electrodes, esophageal electrodes, transcutaneous electrodes,
intracutaneous electrodes, screw-type electrodes, barb-type
electrodes, bipolar electrodes, monopolar electrodes, metal
electrodes, wire electrodes, catheter sheath electrodes, introducer
electrodes, cannula electrodes and cuff electrodes. The electrodes
may comprise an electrically conducting material, for example,
metal paint, metal tape, metal strips, metal buttons, metal foil,
metal wire and/or conductive plastic. Guided or steerable catheter
devices comprising electrodes may be used alone or in combination
with the electrodes.
[0075] Cardiac stimulator 220 may be capable of producing specific
pacing and stimulation regimes. For example, cardiac stimulator 220
may be capable of sensing and treating electromechanical
dissociation (EMD) of the heart as disclosed in U.S. Pat. No.
6,253,108 to inventors Rosborough and Deno and/or cardiac
stimulator 220 may be capable of sensing and treating
tachyarrhythmia of the heart using specific pacing and/or
stimulation regimes. In some patients, EMD and/or tachyarrhythmia
may occur during and/or post the medical procedure. The pacing and
stimulation regimes may be specific for periods before the
procedure, during the procedure and post the procedure. The pacing
and stimulation regimes may also be specific for patient recovery,
if the patients do not respond following a period of cardiac
asystole.
[0076] Nerve stimulator 210 and/or cardiac stimulator 220 may be
slaved to a robotic system or a robotic system may be slaved to
nerve stimulator 210 and/or cardiac stimulator 220. Breathing
regulator 240 and other components may also be slaved to such a
system. Computer- and voice-controlled robotic systems that
position and maneuver endoscopes and/or other surgical instruments
for performing microsurgical procedures such as anastomoses through
small incisions may be used by a surgeon to perform precise and
delicate maneuvers. These robotic systems may allow a surgeon to
perform a variety of microsurgical procedures including endoscopic
CABG. Endoscopic CABG may allow multiple occluded coronary arteries
to be bypassed without a thoracotomy or mini-thoracotomy. Heart
valve repair and replacement may also be other surgical
applications for these robotic systems. In general, robotic systems
may include head-mounted displays which integrate 3-D visualization
of surgical anatomy and related diagnostic and monitoring data,
miniature high resolution 2-D and 3-D digital cameras, a computer,
a high power light source and a standard video monitor.
[0077] System 200 may also include a breathing regulator 240. In
one embodiment, the breathing regulator 240 may be used to
stimulate the phrenic nerve in order to provide a diaphragmatic
pacemaker. Breathing regulator 240 may comprise one or more
electrodes for supplying electrical current to the phrenic nerve to
control breathing during vagal and/or cardiac stimulation and/or
destimulation. Electrodes used to stimulate the phrenic nerve may
be, for example, non-invasive, e.g., clips, or invasive, e.g.,
needles or probes. The application of an electrical stimulus to the
phrenic nerve may include, but is not limited to bipolar and/or
monopolar techniques. Different electrode positions are accessible
through various access openings, for example, in the cervical or
thorax regions. Nerve stimulation electrodes may be positioned
through a thoracotomy, sternotomy, endoscopically through a
percutaneous port, through a stab wound or puncture, through a
small incision, placed on the skin or in combinations thereof. The
present invention may include various electrodes, catheters and
electrode catheters suitable for phrenic nerve stimulation to
control breathing.
[0078] Phrenic nerve stimulation electrodes may be intravascular,
patch-type, balloon-type, basket-type, umbrella-type, tape-type,
cuff-type, suction-type, screw-type, barb-type, bipolar, monopolar,
metal, wire, endotracheal electrodes, esophageal electrodes,
intravascular electrodes, transcutaneous electrodes, catheter
sheath electrodes, introducer electrodes, cannula electrodes or
intracutaneous electrodes. The electrodes may comprise an
electrically conducting material, for example, metal paint, metal
tape, metal strips, metal buttons, metal foil, metal wire and/or
conductive plastic. Guided or steerable catheter devices comprising
electrodes may be used alone or in combination with the nerve
stimulation electrodes. For example, a catheter comprising one or
more wire, metal strips or metal foil electrodes or electrode
arrays may be used. The catheter may comprise, for example, a
balloon that may be inflated with air or liquid to press the
electrodes firmly against a vessel wall that lays adjacent the
phrenic nerve.
[0079] Phrenic nerve stimulation electrodes may be oriented in any
fashion along a device, including longitudinally or transversely.
Various techniques such as ultrasound, fluoroscopy and
echocardiography may be used to facilitate positioning of the
electrodes. If desired or necessary, avoidance of obstruction of
blood flow may be achieved with notched catheter designs or with
catheters that incorporate one or more tunnels or passageways.
[0080] In another embodiment, the breathing regulator may comprise
a connector that interfaces with a patient's respirator, and sends
a logic signal to activate or deactivate the respirator to control
breathing during vagal and/or cardiac stimulation and/or
destimulation.
[0081] System 200 may also include electrodes for relieving pain
such as indicated at 260. In one embodiment, pain-relieving
electrodes may be used to stimulate the spinal cord. Pain relieving
electrodes 260 may comprise one or more electrodes for supplying
electrical current to control pain during vagal and/or cardiac
stimulation and/or destimulation. Electrodes used to relieve pain
may be, for example, non-invasive, e.g., clips, or invasive, e.g.,
needles or probes. The application of an electrical stimulus to
relieve pain may include, but is not limited to bipolar and/or
monopolar techniques. The electrodes may comprise an electrically
conducting material, for example, metal paint, metal tape, metal
strips, metal buttons, metal foil, metal wire and/or conductive
plastic. Different electrode positions are accessible through
various access openings, for example, in the cervical or thorax
regions. Nerve stimulation electrodes may be positioned through a
thoracotomy, sternotomy, endoscopically through a percutaneous
port, through a stab wound or puncture, through a small incision,
placed on the skin or in combinations thereof. The present
invention may include various electrodes, catheters and electrode
catheters suitable for the control of pain.
[0082] Pain relieving electrodes 260 may be intravascular,
patch-type, balloon-type, basket-type, umbrella-type, tape-type,
cuff-type, suction-type, screw-type, barb-type, bipolar, monopolar,
metal, wire, endotracheal, endoesophageal, intravascular,
transcutaneous or intracutaneous electrodes. Guided or steerable
catheter devices comprising electrodes may be used alone or in
combination with the nerve stimulation electrodes. For example, a
catheter comprising one or more wire, metal strips or metal foil
electrodes or electrode arrays may be used. The catheter may
comprise, for example, a balloon that may be inflated with air or
liquid to press the electrodes firmly against a vessel wall that
lays adjacent the nerve or portion of the spine to be
stimulated.
[0083] Pain relieving electrodes may be oriented in any fashion
along the device, including longitudinally or transversely. Various
techniques such as ultrasound, fluoroscopy and echocardiography may
be used to facilitate positioning of the electrodes. If desired or
necessary, avoidance of obstruction of blood flow may be achieved
with notched catheter designs or with catheters that incorporate
one or more tunnels or passageways.
[0084] System 200 may also include sensing electrodes 270 to
monitor one or more sites of stimulation. Sensing electrodes may be
the same electrodes used for nerve stimulation, cardiac stimulation
or pain relieving and/or they may be positioned adjacent one or
more of the sites of stimulation described above.
[0085] System 200 may also include controller 230. Controller 230
may be used to gather information from nerve stimulator 210 and
cardiac stimulator 220. Controller 230 may also be used to control
the stimulation levels and stimulation duration of nerve stimulator
210 and cardiac stimulator 220. Controller 230 may also gather and
process information from the various components of system 200, in
particular sensing electrodes 270. This information may be used to
adjust stimulation levels and stimulation times of nerve stimulator
210, cardiac stimulator 220, breathing regulator 240 and/or pain
relieving electrodes 260. This adjustment may be based, for
example, on data received from monitoring electrodes 270.
[0086] System 200 may incorporate one or more switches to
facilitate regulation of the various components by the surgeon. One
such switch is indicated schematically at 250. The switch may be,
for example, a hand switch, a foot switch or a voice-activated
switch comprising voice-recognition technologies. The switch may be
incorporated on one of the surgeon's instruments, such as surgical
site retractor, or any other location easily and quickly accessed
by the surgeon.
[0087] System 200 may also incorporate means for indicating the
status of various components to the surgeon such as feedback means
280. These feedback means may comprise a display, a numerical
display, gauges, a monitor display or audio feedback. Feedback
means 280 may also comprise one or more visual and/or audible
signals used to prepare a surgeon for the start or stop of nerve
stimulation and/or cardiac stimulation. Alternatively, the feedback
means may be incorporated on one of the surgeon's instruments, such
as surgical site retractor, or any other location easily and
quickly accessed by the surgeon.
[0088] FIG. 7 shows a flow diagram of one embodiment of the present
invention at 300. Stimulation from at least one electrode of a
first electrode arrangement may begin at block 310. In one
embodiment of the invention, the first electrode arrangement may be
located on tube 100 of device 10. At block 320, stimulation from at
least one electrode of a second electrode arrangement is begun. In
one embodiment of the invention, the second electrode arrangement
may be located on collar 101 of device 10. At block 330, data is
gathered regarding the stimulation. For example, data may be
gathered from sensing electrodes 270. Alternatively, one or more of
the electrodes delivering stimulation may also deliver data to be
gathered (i.e. may act as both stimulation and sensing electrodes.)
At block 340, the stimulation is evaluated based on the data
gathered at block 330. In one embodiment of the invention, the
stimulation may be compared to a previously decided value of
stimulation. If the stimulation is satisfactory, the stimulation
may be continued using the first and second electrode arrangement
from blocks 310, 320 (block 350). Alternatively, if the stimulation
is not satisfactory, the process may be repeated as designated by
loop 365 and another first electrode arrangement is chosen (block
310) followed by another second electrode arrangement (block 320)
and further evaluation (blocks 330, 340). This process may repeated
until the most satisfactory stimulation is received.
[0089] FIG. 8 shows a flow diagram of one embodiment of the present
invention. The patient is prepared for a medical procedure at
500.
[0090] At block 510, a nerve that controls the beating of the heart
is stimulated. Such a nerve may be for example a vagal nerve. In
one embodiment of the invention, at block 510, the routine
described in FIG. 3 occurs until the electrode pairing resulting in
the most satisfactory stimulation is achieved.
[0091] During the procedure 500, one or more of a variety of
pharmacological agents or drugs may be delivered (Block 515). These
drugs may produce reversible asystole of a heart while maintaining
the ability of the heart to be electrically paced. Other drugs may
be administered for a variety of functions and purposes as
described below. As seen in FIG. 4, drugs delivered at Block 515
may be administered at the beginning of the procedure,
intermittently during the procedure, continuously during the
procedure, or following the procedure.
[0092] Drugs, drug formulations or compositions suitable for
administration to a patient during a medical procedure may include
a pharmaceutically acceptable carrier or solution in an appropriate
dosage. There are a number of pharmaceutically acceptable carriers
that may be used for delivery of various drugs, for example, via
direct injection, intravenous delivery, intramuscular delivery,
oral delivery, topical delivery, hypodermal delivery, suppository
delivery, transdermal delivery, epicardial delivery,
intraparenteral delivery and/or inhalation delivery.
Pharmaceutically acceptable carriers include a number of solutions,
preferably sterile, for example, water, saline, Ringer's solution
and/or sugar solutions such as dextrose in water or saline. Other
possible carriers that may be used include a oil, sodium citrate,
citric acid, amino acids, lactate, mannitol, maltose, glycerol,
sucrose, ammonium chloride, sodium chloride, potassium chloride,
calcium chloride, sodium lactate, and/or sodium bicarbonate.
Carrier solutions may or may not be buffered.
[0093] Drug formulations or compositions may include antioxidants
or preservatives such as ascorbic acid. Other preservatives include
benzalkonium chloride, methyl-paraben, propyl-paraben, and
chlorbutanol. They may also be in a pharmaceutically acceptable
form for parenteral administration, for example to the
cardiovascular system, or directly to the heart, such as
intracoronary infusion or injection. Drug formulations or
compositions may comprise agents that provide a synergistic effect
when administered together. A synergistic effect between two or
more drugs or agents may reduce the amount that normally is
required for therapeutic delivery of an individual drug or agent.
Two or more drugs may be administered, for example, sequentially or
simultaneously. Drugs may be administered via one or more bolus
injections and/or infusions or combinations thereof. The injections
and/or infusions may be continuous or intermittent. Drugs may be
administered, for example, systemically or locally, for example, to
the heart, to a coronary artery and/or vein, to a pulmonary artery
and/or vein, to the right atrium and/or ventricle, to the left
atrium and/or ventricle, to the aorta, to the AV node, to the SA
node, to a nerve and/or to the coronary sinus. Drugs may be
administered or delivered via intravenous, intracoronary and/or
intraventricular administration in a suitable carrier. Examples of
arteries that may be used to deliver drugs to the AV node include
the AV node artery, the right coronary artery, the right descending
coronary artery, the left coronary artery, the left anterior
descending coronary artery and Kugel's artery. Drugs may be
delivered systemically, for example, via oral, transdermal,
intranasal, suppository or inhalation methods. Drugs also may be
delivered via a pill, a spray, a cream, an ointment or a medicament
formulation.
[0094] Drugs may be delivered via a drug delivery device that may
comprise a catheter, such as a drug delivery catheter or a guide
catheter, a patch, such as a transepicardial patch that slowly
releases drugs directly into the myocardium, a cannula, a pump
and/or a hypodermic needle and syringe assembly. A drug delivery
catheter may include an expandable member, e.g., a low-pressure
balloon, and a shaft having a distal portion, wherein the
expandable member is disposed along the distal portion. A catheter
for drug delivery may comprise one or more lumens and may be
delivered endovascularly via insertion into a blood vessel, e.g.,
an artery such as a femoral, radial, subclavian or coronary artery.
The catheter can be guided into a desired position using various
guidance techniques, e.g., flouroscopic guidance and/or a guiding
catheter or guide wire techniques.
[0095] Drugs may be delivered via an iontophoretic drug delivery
device placed on the heart. In general, the delivery of ionized
drugs may be enhanced via a small current applied across two
electrodes. Positive ions may be introduced into the tissues from
the positive pole, or negative ions from the negative pole. The use
of iontophoresis may markedly facilitate the transport of certain
ionized drug molecules. For example, lidocaine hydrochloride may be
applied to the heart via a drug patch comprising the drug. A
positive electrode could be placed over the patch and current
passed. The negative electrode would contact the heart or other
body part at some desired distance point to complete the circuit.
One or more of the electrodes may also be used as nerve stimulation
electrodes 210 or as cardiac stimulation electrodes 220.
[0096] The two divisions of the autonomic nervous system that
regulate the heart have opposite functions. First, the adrenergic
or sympathetic nervous system increases heart rate by releasing
epinephrine and norepinephrine. Second, the parasympathetic system
also known as the cholinergic nervous system or the vagal nervous
system decreases heart rate by releasing acetylcholine.
Catecholamines such as norepinephrine (also called noradrenaline)
and epinephrine (also called adrenaline) are agonists for
beta-adrenergic receptors. An agonist is a stimulant biomolecule or
agent that binds to a receptor.
[0097] Beta-adrenergic receptor blocking agents compete with
beta-adrenergic receptor stimulating agents for available
beta-receptor sites. When access to beta-receptor sites are blocked
by receptor blocking agents, also known as beta-adrenergic
blockade, the chronotropic or heart rate, inotropic or
contractility, and vasodilator responses to receptor stimulating
agents are decreased proportionately. Therefore, beta-adrenergic
receptor blocking agents are agents that are capable of blocking
beta-adrenergic receptor sites.
[0098] Since beta-adrenergic receptors are concerned with
contractility and heart rate, stimulation of beta-adrenergic
receptors, in general, increases heart rate, the contractility of
the heart and the rate of conduction of electrical impulses through
the AV node and the conduction system.
[0099] Drugs, drug formulations and/or drug compositions that may
be used according to this invention may include any naturally
occurring or chemically synthesized (synthetic analogues)
beta-adrenergic receptor blocking agents. Beta-adrenergic receptor
blocking agents or .beta.-adrenergic blocking agents are also known
as beta-blockers or .beta.-blockers and as class 11
antiarrhythmics.
[0100] The term "beta-blocker" appearing herein may refer to one or
more agents that antagonize the effects of beta-stimulating
catecholamines by blocking the catecholamines from binding to the
beta-receptors. Examples of beta-blockers include, but are not
limited to, acebutolol, alprenolol, atenolol, betantolol,
betaxolol, bevantolol, bisoprolol, carterolol, celiprolol,
chlorthalidone, esmolol, labetalol, metoprolol, nadolol,
penbutolol, pindolol, propranolol, oxprenolol, sotalol, teratolol,
timolol and combinations, mixtures and/or salts thereof.
[0101] The effects of administered beta-blockers may be reversed by
administration of beta-receptor agonists, e.g., dobutamine or
isoproterenol.
[0102] The parasympathetic or cholinergic system participates in
control of heart rate via the sinoatrial (SA) node, where it
reduces heart rate. Other cholinergic effects include inhibition of
the AV node and an inhibitory effect on contractile force. The
cholinergic system acts through the vagal nerve to release
acetylcholine, which, in turn, stimulates cholinergic receptors.
Cholinergic receptors are also known as muscarinic receptors.
Stimulation of the cholinergic receptors decreases the formation of
cAMP. Stimulation of cholinergic receptors generally has an
opposite effect on heart rate compared to stimulation of
beta-adrenergic receptors. For example, beta-adrenergic stimulation
increases heart rate, whereas cholinergic stimulation decreases it.
When vagal tone is high and adrenergic tone is low, there is a
marked slowing of the heart (sinus bradycardia). Acetylcholine
effectively reduces the amplitude, rate of increase and duration of
the SA node action potential. During vagal nerve stimulation, the
SA node does not arrest. Rather, pacemaker function may shift to
cells that fire at a slower rate. In addition, acetylcholine may
help open certain potassium channels thereby creating an outward
flow of potassium ions and hyperpolarization. Acetylcholine also
slows conduction through the AV node.
[0103] Drugs, drug formulations and/or drug compositions that may
be used according to this invention may include any naturally
occurring or chemically synthesized (synthetic analogues)
cholinergic agent. The term "cholinergic agent" appearing herein
may refer to one or more cholinergic receptor modulators or
agonists. Examples of cholinergic agents include, but are not
limited to, acetylcholine, carbachol (carbamyl choline chloride),
bethanechol, methacholine, arecoline, norarecoline and
combinations, mixtures and/or salts thereof.
[0104] Drugs, drug formulations and/or drug compositions that may
be used according to this invention may include any naturally
occurring or chemically synthesized cholinesterase inhibitor. The
term "cholinesterase inhibitor" appearing herein may refer to one
or more agents that prolong the action of acetylcholine by
inhibiting its destruction or hydrolysis by cholinesterase.
Cholinesterase inhibitors are also known as acetylcholinesterase
inhibitors. Examples of cholinesterase inhibitors include, but are
not limited to, edrophonium, neostigmine, neostigmine
methylsulfate, pyridostigmine, tacrine and combinations, mixtures
and/or salts thereof.
[0105] Drugs, drug formulations and/or drug compositions that may
be used according to this invention may include any naturally
occurring or chemically synthesized (synthetic analogues)
P.sub.2-purinoceptor agents. The term "P.sub.2-purinoceptor agent"
appearing herein may refer to one or more P.sub.2-purinoceptor
modulators, mediators, agonists and/or antagonists disclosed in
U.S. Pat. No. 5,874,420 to inventor Pelleg. P.sub.2-purinoceptors
are specific cell surface receptors found on vagal nerve terminals.
Vagal tone may be modulated (increased or decreased) by the
administration of one or more P.sub.2-purinoceptor agents which
activate or block these P.sub.2-purinoceptor receptors. Examples of
P.sub.2-purinoceptor agents include, but are not limited to,
P.sub.2-purinoceptor agonists, P.sub.2-purinoceptor antagonists,
pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS),
Reactive Blue 2, Cibacron Blue, adenosine 5'-triphosphate (ATP),
ATP analogues, capsaicin and combinations, mixtures and/or salts
thereof.
[0106] There are ion-selective channels within certain cell
membranes. These ion selective channels include calcium channels,
sodium channels and/or potassium channels. Therefore, other drugs,
drug formulations and/or drug compositions that may be used
according to this invention may include any naturally occurring or
chemically synthesized calcium channel blocker. Calcium channel
blockers inhibit the inward flux of calcium ions across cell
membranes of arterial smooth muscle cells and myocardial cells.
Therefore, the term "calcium channel blocker" appearing herein may
refer to one or more agents that inhibit or block the flow of
calcium ions across a cell membrane. The calcium channel is
generally concerned with the triggering of the contractile cycle.
Calcium channel blockers are also known as calcium ion influx
inhibitors, slow channel blockers, calcium ion antagonists, calcium
channel antagonist drugs and as class IV antiarrhythmics. A
commonly used calcium channel blocker is verapamil.
[0107] Administration of a calcium channel blocker, e.g.,
verapamil, generally prolongs the effective refractory period
within the AV node and slows AV conduction in a rate-related
manner, since the electrical activity through the AV node depends
significantly upon the influx of calcium ions through the slow
channel. A calcium channel blocker has the ability to slow a
patient's heart rate, as well as produce AV block. Examples of
calcium channel blockers include, but are not limited to,
amiloride, amlodipine, bepridil, diltiazem, felodipine, isradipine,
mibefradil, nicardipine, nifedipine (dihydropyridines), nickel,
nimodinpine, nisoldipine, nitric oxide (NO), norverapamil and
verapamil and combinations, mixtures and/or salts thereof.
Verapamil and diltiazem are very effective at inhibiting the AV
node, whereas drugs of the nifedipine family have a lesser
inhibitory effect on the AV node. Nitric oxide (NO) indirectly
promotes calcium channel closure. NO may be used to inhibit
contraction. NO may also be used to inhibit sympathetic outflow,
lessen the release of norepinephrine, cause vasodilation, decrease
heart rate and decrease contractility. In the SA node, cholinergic
stimulation leads to formation of NO.
[0108] Other drugs, drug formulations and/or drug compositions that
may be used according to this invention may include any naturally
occurring or chemically synthesized sodium channel blocker. Sodium
channel blockers are also known as sodium channel inhibitors,
sodium channel blocking agents, rapid channel blockers or rapid
channel inhibitors. Antiarrhythmic agents that inhibit or block the
sodium channel are known as class I antiarrhythmics, examples
include, but are not limited to, quinidine and quinidine-like
agents, lidocaine and lidocaine-like agents, tetrodotoxin,
encainide, flecainide and combinations, mixtures and/or salts
thereof. Therefore, the term "sodium channel blocker" appearing
herein may refer to one or more agents that inhibit or block the
flow of sodium ions across a cell membrane or remove the potential
difference across a cell membrane. For example, the sodium channel
may also be totally inhibited by increasing the extracellular
potassium levels to depolarizing hyperkalemic values, which remove
the potential difference across the cell membrane. The result is
inhibition of cardiac contraction with cardiac arrest
(cardioplegia). The opening of the sodium channel (influx of
sodium) is for swift conduction of the electrical impulse
throughout the heart.
[0109] Other drugs, drug formulations and/or drug compositions that
may be used according to this invention may include any naturally
occurring or chemically synthesized potassium channel agent. The
term "potassium channel agent" appearing herein may refer to one or
more agents that impact the flow of potassium ions across the cell
membrane. There are two major types of potassium channels. The
first type of channel is voltage-gated and the second type is
ligand-gated. Acetylcholine-activated potassium channels, which are
ligand-gated channels, open in response to vagal stimulation and
the release of acetylcholine. Opening of the potassium channel
causes hyperpolarization, which decreases the rate at which the
activation threshold is reached. Adenosine is one example of a
potassium channel opener. Adenosine slows conduction through the AV
node. Adenosine, a breakdown product of adenosine triphosphate,
inhibits the AV node and atria. In atrial tissue, adenosine causes
the shortening of the action potential duration and causes
hyperpolarization. In the AV node, adenosine has similar effects
and also decreases the action potential amplitude and the rate of
increase of the action potential. Adenosine is also a direct
vasodilator by its actions on the adenosine receptor on vascular
smooth muscle cells. In addition, adenosine acts as a negative
neuromodulator, thereby inhibiting release of norepinephrine. Class
III antiarrhythmic agents also known as potassium channel
inhibitors lengthen the action potential duration and
refractoriness by blocking the outward potassium channel to prolong
the action potential. Amiodarone and d-sotalol are both examples of
class III antiarrhythmic agents.
[0110] Potassium is the most common component in cardioplegic
solutions. High extracellular potassium levels reduce the membrane
resting potential. Opening of the sodium channel, which normally
allows rapid sodium influx during the upstroke of the action
potential, is therefore inactivated because of a reduction in the
membrane resting potential. The present invention may be combined
with conventional CPB, the induced asystole as described by this
invention may serve as a substitute for conventional cardioplegic
arrest. For example, the combination of drugs and vagal stimulation
may be used as a cardioplegic agent in a variety of medical
procedures.
[0111] Drugs, drug formulations and/or drug compositions that may
be used according to this invention may include any naturally
occurring or chemically synthesized (synthetic analogues) ischemia
agents. The term "ischemia agent" appearing herein may refer to one
or more agents that protect one or more organs and/or tissues from
ischemic damage. For example, delta opioid receptor modulators,
mediators, agonists and/or antagonists as disclosed in U.S. Pat.
No. 6,103,722 to inventors Schultz and Gross and in U.S. Pat. No.
5,656,420 to inventor Chien have been used in ischemia
protection.
[0112] Although it is desirable to stop the heart for a period of
time in order to allow the surgeon to accomplish a required task
without interference from heart movement, stopping the heart for
prolonged periods of time may cause damage to various organs and
tissues from ischemia or lack of oxygen. Opioid receptor activation
on organs and tissues which possess delta opioid receptors has been
shown to elicit a protective effect during periods of ischemia.
Delivering an ischemia agent such as a delta opioid agonist to the
patient may protect certain organs and tissues such as cardiac
and/or brain tissue of the patient from ischemic damage caused by
intermittent periods of cardiac asystole. Examples of delta opioid
agonists include, but are not limited to, TAN67(-), DPDPE,
BW373U86, DADLE, SB219825, SNC80 and SIOM and combinations,
mixtures and/or salts thereof.
[0113] Drugs, drug formulations and/or drug compositions that may
be used during according to this invention may comprise one or more
of any naturally occurring or chemically synthesized beta-blocker,
cholinergic agent, cholinesterase inhibitor, calcium channel
blocker, sodium channel blocker, potassium channel agent,
adenosine, adenosine receptor agonist, adenosine deaminase
inhibitor, dipyridamole, monoamine oxidase inhibitor, digoxin,
digitalis, lignocaine, bradykinin agents, serotoninergic agonist,
antiarrythmic agents, cardiac glycosides, local anesthetics,
P.sub.2-purinoceptor agents, ischemia agents, delta opioid agonists
and combinations or mixtures thereof. Digitalis and digoxin both
inhibit the sodium pump. Digitalis is a natural inotrope derived
from plant material, while digoxin is a synthesized inotrope.
Dipyridamole inhibits adenosine deaminase, which breaks down
adenosine. Drugs, drug formulations and/or drug compositions
capable of reversibly suppressing autonomous electrical conduction
at the SA and/or AV node, while still allowing the heart to be
electrically paced to maintain cardiac output may be used according
to this invention.
[0114] In one embodiment, the cardiac asystole produced in
accordance with the present invention is reversible, e.g.,
chemically such as by the administration of atropine or by natural
forces. Beta-adrenergic stimulation or administration of calcium
solutions may be used to reverse the effects of a calcium channel
blocker such as verapamil. Agents that promote heart rate and/or
contraction may be used in a preferred embodiment of the present
invention. For example, dopamine, a natural catecholamine, is known
to increase contractility. Positive inotropes are agents that
specifically increase the force of contraction of the heart.
Glucagon, a naturally occurring hormone, is known to increase heart
rate and contractility. Glucagon may be used to reverse the effects
of a beta-blocker since its effects bypass the beta receptor.
Forskolin is known to increase heart rate and contractility. As
mentioned earlier, epinephrine and norepinephrine naturally
increase heart rate and contractility. Thyroid hormone,
phosphodiesterase inhibitors and prostacyclin, a prostaglandin, are
also known to increase heart rate and contractility. In addition,
methylxanthines are known to prevent adenosine from interacting
with its cell receptors.
[0115] Typically, vagal nerve stimulation prevents the heart from
contracting. This non-contraction must then be followed by periods
without vagal nerve stimulation during which the heart is allowed
to contract.
[0116] At Block 520, a medical procedure may be performed or begun.
Such a procedure may be for example surgery on the heart.
Alternatively, the procedure may be surgery performed on another
organ of the body.
[0117] The term "medical procedure" may mean any one or more
medical or surgical procedures such as, for example cardiac
surgery, performed with or without cardiopulmonary bypass (CPB)
circuits, heart valve repair, heart valve replacement, MAZE
procedures, revascularization procedures, transmyocardial
revascularization (TMR) procedures, percutaneous myocardial
revascularization (PMR) procedures, CABG procedures, anastomosis
procedures, non-surgical procedures, fluoroscopic procedures,
beating heart surgery, vascular surgery, neurosurgery, brain
surgery, electrophysiology procedures, diagnostic and therapeutic
procedures, ablation procedures, ablation of arrhythmias,
endovascular procedures, treatment of the liver, spleen, heart,
lungs, and major blood vessels, aneurysm repair, imaging procedures
of the heart and great vessels, CAT scans or MRI procedures,
pharmacological therapies, drug delivery procedures, gene
therapies, cellular therapies, cancer therapies, radiation
therapies, genetic, cellular, tissue and/or organ manipulation or
transplantation procedures, coronary angioplasty procedures,
placement or delivery of coated or noncoated stents, atherectomy
procedures, atherosclerotic plaque manipulation and/or removal
procedures, procedures where bleeding needs to be precisely
controlled, procedures that require precise control of cardiac
motion and/or bleeding.
[0118] When the medical procedure comprises one or more medical
devices, e.g., coated stents, these devices may be coated with one
or more radioactive materials and/or biological agents such as, for
example, an anticoagulant agent, an antithrombotic agent, a
clotting agent, a platelet agent, an anti-inflammatory agent, an
antibody, an antigen, an immunoglobulin, a defense agent, an
enzyme, a hormone, a growth factor, a neurotransmitter, a cytokine,
a blood agent, a regulatory agent, a transport agent, a fibrous
agent, a protein, a peptide, a proteoglycan, a toxin, an antibiotic
agent, an antibacterial agent, an antimicrobial agent, a bacterial
agent or component, hyaluronic acid, a polysaccharide, a
carbohydrate, a fatty acid, a catalyst, a drug, a vitamin, a DNA
segment, a RNA segment, a nucleic acid, a lectin, an antiviral
agent, a viral agent or component, a genetic agent, a ligand and a
dye (which acts as a biological ligand). Biological agents may be
found in nature (naturally occurring) or may be chemically
synthesized.
[0119] The medical procedure may be non-invasive, minimally
invasive and/or invasive. The medical procedure may entail a
port-access approach, a partially or totally endoscopic approach, a
sternotomy approach or a thoracotomy approach. The medical
procedure may include the use of various mechanical stabilization
devices or techniques as well as various robotic or imaging
systems.
[0120] In one method, the heart may be temporarily slowed or
intermittently stopped for short periods of time to permit the
surgeon to accomplish the required surgical task and yet still
allow the heart itself to supply blood circulation to the body. For
example, stimulation of the vagus nerve in order to temporarily and
intermittently slow or stop the heart is described in U.S. Pat. No.
6,006,134 entitled "Method and Device for Electronically
Controlling the Beating of a Heart Using Venous Electrical
Stimulation of Nerve Fibers," Dec. 21, 1999, to inventors Hill and
Junkman. This patent is assigned to Medtronic, Inc. and is
incorporated herein by reference.
[0121] After a time, the medical procedure or one phase of the
procedure is completed at 520. After some phase of the medical
procedure is performed, cardiac contractions are allowed to occur
(Block 530) Cardiac contractions may need to occur intermittently
during the procedure to ensure adequate blood flow. In one
embodiment, the stimulation from the nerve stimulation electrodes
is stopped or slowed enough to allow the heart to contract. For
example, the vagal nerve stimulation is removed, thereby allowing
cardiac contractions to occur.
[0122] In another embodiment, the heart may be stimulated to ensure
that cardiac contractions occur (Block 535). For example, cardiac
stimulation electrodes may be used to apply pacing pulses to the
heart to encourage the heart to contract normally. In particular,
the pacing pulses may be applied to the ventricle as is well known
in the field. In one embodiment of the invention, the routine
described in FIG. 3 may take place at this time to evaluate the
stimulation from cardiac stimulation electrodes until the most
satisfactory pairing of stimulating electrodes is determined.
[0123] The present invention permits the heart to be stilled for
selected and controllable periods of time in order to permit
cardiac or other medical procedure to be performed. While such a
period of stillness is desired, it must not last too long,
otherwise insufficient blood and oxygen is delivered to organs.
Thus, it is necessary to have the periods when the heart is beating
(Blocks 530, 535).
[0124] If additional medical procedures or additional stages of
medical procedures need to be performed, the heart may again be
stilled using the methods of stilling the heart described above.
Therefore from Block 530 or Block 535, the method may be repeated
(Block 540). For example, the heart may again be prevented from
contracting by stimulation of the vagal nerve (Block 510). Again,
the stimulation electrodes may be evaluated using the routine of
the present invention to find the optimal stimulation arrangement.
Additional drugs may be delivered or the drugs previously
administered may continue to be administered.
[0125] Additional surgery, additional steps in the medical
procedure or additional medical procedures may again be performed
(Block 520) while the heart is still. Then, this stage of stillness
may be followed by another stage when the stimulation is removed
(Block 530) and the heart is allowed to contract. Again, the heart
may be stimulated to encourage contractions (Block 535). Again, the
stimulation electrodes may be evaluated using the routine of the
present invention to find the optimal stimulation arrangement.
[0126] This cycle may be repeated until the procedure, such as the
surgery, is completed. After the procedure is completed, step 535
may be performed until the heart is beating normally. At the
procedure's end, one or more of a variety of pharmacological agents
or drugs may be delivered or may continue to be delivered for
example to alleviate pain or aid in recuperation. Other drugs may
be administered for a variety of functions and purposes as
described above.
[0127] For example, a surgical procedure at 520 may require several
stitches to be made by the surgeon. The surgeon may stimulate the
vagal nerve at 510 to stop the heart. Then the surgeon may make the
first stitch at 520. The surgeon may then reduce or halt
stimulation at 530 and allow the heart to contract. The surgeon may
also pace the heart at 535. Then at 540, the surgeon may return to
510 to inhibit contractions of the heart. At 520, the surgeon will
then make the second stitch. This process may be repeated (the loop
designated by 540 may be repeated) until all the required stitches
have been made.
[0128] FIG. 9 is a timeline showing the relation of the vagal nerve
stimulation to the cardiac stimulation in one embodiment of the
present invention.
[0129] Point 610 indicates a point before the medical procedure has
begun. At this point 610, both nerve stimulation and cardiac
stimulation are off. At point 610, the heart is beating regularly.
Then nerve stimulation is turned on to inhibit beating of the
heart. At point 610, the stimulation electrodes used to stimulate
the nerve may be evaluated according to the method of the present
invention. During phase 601, the vagal nerve stimulation is on and
the cardiac stimulation is off. This is the condition of the two
types of stimulation at step 520 described above.
[0130] Point 611 is a representative point during phase 601. At
point 611, the contractions of the heart are stilled or
substantially slowed. Then during phase 602 the vagal stimulation
is turned off (as described at step 530) and the cardiac
stimulation may be turned on (as described at 535). Point 612 is a
representative point during phase 602. At point 612, the
contractions are allowed and/or may be induced. At point 612, the
stimulation electrodes used to stimulation the nerve may be
evaluated according to the method of the present invention.
[0131] During phase 603, the vagal nerve stimulation is again
turned on and the cardiac stimulation is turned off. Then during
phase 604 the vagal stimulation is again turned off and the cardiac
stimulation may again be turned on. The method of the present
invention may be repeated as necessary until a point is reached,
represented by point 615, when the necessary medical procedures are
completed. At this point 615, nerve stimulation is off although
cardiac stimulation may be left on in order to pace the heart to
its normal rhythm.
[0132] It will be appreciated by those skilled in the art that
while the invention has been described above in connection with
particular embodiments and examples, the invention is not
necessarily so limited, and that numerous other embodiments,
examples, uses, modifications and departures from the embodiments,
examples and uses are intended to be encompassed by the claims
attached hereto. The entire disclosure of each patent and
publication cited herein is incorporated by reference, as if each
such patent or publication were individually incorporated by
reference herein.
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