U.S. patent application number 10/137516 was filed with the patent office on 2005-08-18 for implantable medical device and patch system and method of use.
This patent application is currently assigned to MEDTRONIC, INC. Invention is credited to Haller, Markus, Heruth, Kenneth T., Hooper, William J., LaPorte, Steve, Lent, Mark S., Olsen, James M., Riff, Kenneth Mark.
Application Number | 20050182389 10/137516 |
Document ID | / |
Family ID | 23103265 |
Filed Date | 2005-08-18 |
United States Patent
Application |
20050182389 |
Kind Code |
A1 |
LaPorte, Steve ; et
al. |
August 18, 2005 |
Implantable medical device and patch system and method of use
Abstract
A system, method and apparatus relating to a therapeutic
substance delivery patch for attachment to a patient such that the
patch is in contact with the patient's skin, wherein the patch
coordinates its delivery of the therapeutic substance to the
patient based on information received relating to the operation of
the implanted device. The information received by the patch may be
received through telemetry from the implanted device, or
alternatively from the patch sensing the action of the implanted
device, or alternatively from the patch sensing the patient's
physiologic reaction to the action taken by the implanted
device.
Inventors: |
LaPorte, Steve; (Arden
Hills, MN) ; Haller, Markus; (Yens, CH) ;
Hooper, William J.; (Lake Elmo, MN) ; Lent, Mark
S.; (Brooklyn Park, MN) ; Riff, Kenneth Mark;
(Orono, MN) ; Heruth, Kenneth T.; (Edina, MN)
; Olsen, James M.; (Plymouth, MN) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MS-LC340
MINNEAPOLIS
MN
55432-5604
US
|
Assignee: |
MEDTRONIC, INC
|
Family ID: |
23103265 |
Appl. No.: |
10/137516 |
Filed: |
April 30, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60287521 |
Apr 30, 2001 |
|
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Current U.S.
Class: |
604/890.1 |
Current CPC
Class: |
A61M 5/14248 20130101;
G16H 20/40 20180101; A61M 2205/3523 20130101; A61B 5/0031 20130101;
A61M 2005/14208 20130101; A61N 1/37217 20130101; A61M 37/0092
20130101; A61M 5/1723 20130101; A61M 5/14244 20130101; A61N 1/37288
20130101; A61N 1/30 20130101; A61N 1/37235 20130101; A61N 1/3702
20130101; A61M 5/14216 20130101; A61B 2560/0271 20130101; G16H
40/63 20180101; A61M 2005/14268 20130101; A61N 1/37258 20130101;
A61N 1/08 20130101 |
Class at
Publication: |
604/890.1 |
International
Class: |
A61K 009/22 |
Claims
What is claimed is:
1. A method of administering a therapeutic substance to a patient
having an implanted medical device, wherein the implanted medical
device generates a signal, the method comprising: attaching a patch
containing the therapeutic substance to the patient so that the
patch is in contact with the skin of the patient; generating a
signal from the implanted medical device; and administering the
therapeutic substance from the patch to the patient in response to
the signal generated by the medical device.
2. The method according to claim 1 wherein the medical device
further comprises a sensor, the method further comprising: sensing
a physiologic characteristic of the patient by the medical device
wherein the signal generated by the medical device represents the
physiologic characteristic.
3. The method according to claim 2 wherein the physiologic
characteristic is selected from the group consisting of
temperature, blood oxygen saturation, activity level, lung wetness,
glucose level, thoracic impedance, EKG, heart rate, respiration
rate, EMG, EEG, blood pressure, intra cerebral ventricular (ICV)
pressure, and position of the patient.
4. The method according to claim 1 wherein the signal generated by
the medical device represents operational information of the
medical device.
5. The method according to claim 1 wherein the attaching a patch
containing the therapeutic substance to the skin of the patient
comprises adhering the patch to the skin.
6. The method according to claim 1 wherein the patch is a
transdermal drug delivery patch.
7. The method according to claim 6 wherein the transdermal drug
delivery patch comprises an iontophoretic transdermal drug delivery
patch.
8. The method according to claim 6 wherein the transdermal drug
delivery patch comprises a sonophoretic transdermal drug delivery
patch.
9. The method according to claim 6 wherein the transdermal drug
delivery patch utilizes a laser to assist in transmission of the
drug through the skin of the patient.
10. The method according to claim 1 wherein the administering the
therapeutic substance to the patient in response to the signal
generated by the medical device comprises administering the
therapeutic substance through a needle attached to the patch.
11. The method according to claim 1 wherein administering the
therapeutic substance to the patient in response to the signal
generated by the implanted medical device comprises directing the
therapeutic substance into an implanted catheter access port
wherein the catheter access port delivers the drug to a selected
location in the body.
12. The method according to claim 11 wherein the selected location
comprises the brain.
13. The method according to claim 11 wherein the selected location
comprises the spinal cord.
14. The method according to claim 11 wherein the selected location
comprises the vascular system.
15. The method according to claim 11 wherein the selected location
comprises the heart.
16. The method according to claim 1 wherein the step of
administering the therapeutic substance to the patient in response
to the signal generated by the medical device comprises
administering a drug to the patient.
17. The method according to claim 1 wherein the step of
administering the therapeutic substance to the patient in response
to the signal generated by the medical device comprises
administering a biologic agent to the patient.
18. The method according to claim 1 wherein the step of
administering the therapeutic substance to the patient in response
to the signal generated by the medical device includes delivery of
a therapeutic substance selected from the group consisting of
anti-arrhythmic drugs, diuretic drugs, vasodilators, muscle
relaxants, pain relieving drugs, analgesics, anti-clotting drugs,
blood thinners, anti-seizure drugs, gene therapeutic substances,
naturitic peptides, insulin, or any other therapeutic substance
whose administration would be improved if the delivery could be
optimally timed to the receipt of information from an implantable
medical device.
19. The method according to claim 1 wherein the medical device is
selected from the group consisting of a nerve stimulator, brain
stimulator, muscle stimulator, infusion pump, drug delivery device,
monitoring device, cochlear implant, oxygen sensing device,
pacemaker, defibrillator, cardioverter,
pacemaker/cardioverter/defibrillator (PCD), left ventricular assist
device and total artificial heart device.
20. A method of administering a therapeutic substance to a patient
having an implanted medical device that is adapted to take an
action on the patient, the method comprising: attaching a patch
containing the therapeutic substance to the patient so that the
patch is in contact with the skin of the patient and a sensor for
sensing a physiologic reaction to the action taken by the medical
device; sensing with the sensor the physiologic reaction to the
action taken by the implanted medical device; and administering the
therapeutic substance to the patient in response to the reaction
sensed by the sensor.
21. The method according to claim 20 wherein the medical device has
an active mode and an inactive mode relating to at least one
activity of the medical device, wherein the step of sensing with
the sensor the patient's physiologic reaction to the action taken
by the medical device comprises determining whether the medical
device is in the active or inactive mode.
22. A method of administering an therapeutic substance to a patient
having an implanted medical device that is adapted to take an
action on the patient, the method comprising: attaching a patch
containing the therapeutic substance to the patient so that the
patch is in contact with the skin of the patient and a sensor for
sensing the action taken by the medical device; sensing with the
sensor the action taken by the implanted medical device; and
administering the therapeutic substance to the patient in response
to the action sensed by the sensor.
23. The method according to claim 22 wherein the medical device has
an active mode and an inactive mode relating to at least one
activity of the medical device, wherein the step of sensing with
the sensor the action taken by the medical device comprises
determining whether the medical device is in the active or inactive
mode.
24. A method of administering an therapeutic substance to a patient
having an implanted medical device that is adapted to take an
action on the patient, the method comprising: attaching a patch
containing the therapeutic substance to the patient so that the
patch is in contact with the skin of the patient and a sensor for
determining if the medical device has taken an action on the
patient; determining with the sensor whether the medical device has
taken an action on the patient; and administering the therapeutic
substance to the patient in response to the determination carried
out in the determining step.
25. The method according to claim 24 wherein the determining step
comprises sensing a parameter relevant to whether the medical
device has taken an action on the patient or a physiologic reaction
of the patient expected in response to the action, and inferring
whether the medical device has taken the action.
26. A method of administering a therapeutic substance to a patient
having an implanted blood pressure monitor, wherein the implanted
blood pressure monitor generates a signal, the method comprising:
attaching a patch containing the therapeutic substance to the
patient so that the patch is in contact with the skin of the
patient; generating a signal from the implanted blood pressure
monitor representing the blood pressure of the patient; and
administering the therapeutic substance from the patch to the
patient in response to the signal generated by the medical
device.
27. The method according to claim 26 wherein the therapeutic
substance is selected from the group consisting of diuretic drugs,
beta blockers, and vasodilators.
28. A method of administering a therapeutic substance to a patient
having an epileptic seizure or in anticipation or prediction of an
epileptic seizure, the patient having an implanted neurostimulator
including deep brain stimulation leads, wherein the implanted
neurostimulator generates a signal, the method comprising:
attaching a patch containing the therapeutic substance to the
patient so that the patch is in contact with the skin of the
patient; generating a signal from the implanted neurostimulator
representing the electric potentials in the brain of the patient;
and administering the therapeutic substance from the patch to the
patient in response to the signal generated by the implanted
neurostimulator.
29. The method according to claim 28 wherein the therapeutic
substance is selected from the group consisting of Phenytoin and
Conantonkin-G.
30. A method of administering a therapeutic substance to a patient
having diabetes, the patient having an implanted glucose monitor,
wherein the implanted glucose monitor generates a signal, the
method comprising: attaching a patch containing the therapeutic
substance to the patient so that the patch is in contact with the
skin of the patient; generating a signal from the implanted glucose
monitor representing glucose level; and administering the
therapeutic substance from the patch to the patient in response to
the signal generated by the implanted glucose monitor.
31. The method according to claim 30 wherein the therapeutic
substance is selected from the group consisting of insulin and
glucagons.
32. A method of administering a narcotic antagonist to a patient
receiving opioids, the patient having an implanted medical device
capable of sensing respiration rate, wherein the implanted medical
device generates a signal, the method comprising: attaching a patch
containing the narcotic antagonist to the patient so that the patch
is in contact with the skin of the patient; generating a signal
from the implanted medical device representing respiration rate;
and administering the narcotic antagonist from the patch to the
patient in response to the signal generated by the implanted
medical device.
33. The method according to claim 32 wherein the opioid comprises
morphine and the narcotic antagonist comprises naloxone.
34. The method according to claim 32 wherein the opioid comprises
fentanyl and the narcotic antagonist comprises naloxone.
35. The method according to claim 32 wherein the opioid comprises
sufentanil and the narcotic antagonist comprises naloxone.
36. The method according to claim 32 wherein the opioid comprises
hydromorphone and the narcotic antagonist comprises naloxone.
37. A method of administering an antiarrythmic drug to a patient,
the patient having an implanted medical device capable of sensing
heart rate, wherein the implanted medical device generates a
signal, the method comprising: attaching a patch containing the
antiarrythmic drug to the patient so that the patch is in contact
with the skin of the patient; generating a signal from the
implanted medical device representing heart rate; and administering
the antiarrythmic drug from the patch to the patient in response to
the signal generated by the implanted medical device.
38. A drug delivery patch capable of administering a therapeutic
substance to a patient based on information received from an
implanted medical device, the patch comprising: a housing
configured for attachment to the patient so that the housing
contacts the patient's skin; a therapeutic substance reservoir
coupled to the housing, the therapeutic substance reservoir having
a reservoir outlet; a power source carried in the housing;
electronics carried in the housing and coupled to the power source,
the electronics comprising a telemetric receiver capable of
receiving a signal generated from the implanted medical device; and
a pump coupled to the electronics and coupled to the reservoir
outlet, the pump configured for pumping a therapeutic substance
from the therapeutic substance reservoir through an infusion outlet
at a programmed rate based on the signal received from the
implanted medical device.
39. A therapeutic substance delivery patch capable of administering
a therapeutic substance to a patient based on information received
from an implanted medical device, the patch comprising: a housing
including reservoir means for containing the therapeutic substance;
attachment means for attaching the patch to the patient so that the
patch is in contact with the patient's skin; communication means
for receiving a signal from the implanted medical device
representing a physiologic condition of the patient; control means
for controlling the functions of the patch through a control signal
wherein the control signal is based at least in part on the signal
from the implanted medical device; and delivery means for
delivering a metered amount of the therapeutic substance to the
patient in response to the control signal.
40. The therapeutic substance delivery patch according to claim 39
wherein the therapeutic substance is selected from the group
consisting of antiarrythmic drugs; diuretic drugs; beta blockers;
vasodilators; muscle relaxants; pain relieving drugs; analgesics;
anti-clotting drugs; blood thinners; anti-seizure drugs; naturitic
peptides; and narcotic antagonists.
41. The therapeutic substance delivery patch according to claim 39
wherein the therapeutic substance is selected from the group
consisting of amiodarone; bumentanide; conantonkin-G; flecainide;
ibutilide; isosorbide; furosemide; metaprolol; naloxone;
nitroglycerine; phenytoin; procainamide; propranolol; insulin;
glucagons; and sotalol.
42. The therapeutic substance delivery patch according to claim 39
wherein the attachment means comprises an adhesive applied to the
housing.
43. A therapeutic substance delivery patch capable of administering
a therapeutic substance to a patient based on information sensed
from an implanted medical device, the patch comprising: a housing
including reservoir means for containing the therapeutic substance;
attachment means for attaching the patch to the patient so that the
patch is in contact with the patient's skin; sensing means for
sensing an action taken by the implanted medical device; control
means for controlling the functions of the patch through a control
signal wherein the control signal is based at least in part on the
sensed action; and delivery means for delivering a metered amount
of the therapeutic substance to the patient in response to the
control signal.
44. A therapeutic substance delivery patch capable of administering
a therapeutic substance to a patient based on sensed physiologic
information, the patch comprising: a housing including reservoir
means for containing the therapeutic substance; attachment means
for attaching the patch to the patient so that the patch is in
contact with the patient's skin; sensing means for sensing a
physiologic reaction to an action taken by the implanted medical
device; control means for controlling the functions of the patch
through a control signal wherein the control signal is based at
least in part on the sensed reaction; and delivery means for
delivering a metered amount of the therapeutic substance to the
patient in response to the control signal.
45. The therapeutic substance delivery patch according to claim 44
wherein the sensing means comprises a sensor capable of sensing
conditions selected from the group consisting of galvanic skin
resistance, temperature, oxygen saturation, blood pressure,
activity level of patient, lung wetness, glucose level, thoracic
impedance, EKG, heart rate, respiration rate, EMG, EEG, ICV
pressure, and position of patient.
46. A therapeutic substance therapy system for delivery of a
therapeutic substance into a human body comprising: (a) an
implanted medical device capable of generating a telemetric signal;
(b) a therapeutic substance delivery patch attached to the patient
so that the patch is in contact with the skin of a patient, the
therapeutic substance delivery patch comprising: (i) a telemetric
receiving antenna for receiving the telemetric signal from the
implanted medical device; (ii) a reservoir capable of holding the
therapeutic substance; and (iii) means for delivering the agent
into the body.
47. A therapeutic substance therapy system for delivery of a
therapeutic substance into a human body comprising: (a) an
implanted medical device capable of generating an electric therapy
signal, the electric therapy signal provided to the patient for
therapeutic reasons; (b) a therapeutic substance delivery patch
attached to the patient so that the patch is in contact with the
skin of a patient, the therapeutic substance delivery patch
comprising: (i) a sensor for sensing the electric therapy signal;
(ii) a reservoir capable of holding the therapeutic substance; and
(iii) means for delivering the agent into the body based at least
in part on the sensed electric therapy signal.
48. A therapeutic substance therapy system for delivery of a
therapeutic substance into a human body comprising: (a) an
implanted medical device capable of generating an electric therapy
signal, the electric therapy signal provided to the patient for
therapeutic reasons wherein the electric therapy signal results in
a physiologic reaction; (b) a therapeutic substance delivery patch
attached to the patient so that the patch is in contact with the
skin of a patient, the therapeutic substance delivery patch
comprising: (i) a sensor for sensing the physiologic reaction to
the electric therapy signal; (ii) a reservoir capable of holding
the therapeutic substance; and (iii) means for delivering the agent
into the body based at least in part on the sensed physiologic
reaction to the electric therapy signal.
Description
RELATED APPLICATIONS
[0001] This application claims priority to provisional U.S.
Application Ser. No. 60/287,521, filed Apr. 30, 2001, which is
incorporated by reference herein.
CROSS REFERENCES
[0002] This application is related to the following co-pending
applications entitled "Permanent Magnet Solenoid Pump For An
Implantable Therapeutic Substance Delivery Device" by Olsen
(attorney docket no. P9740.00); "Low Profile Inlet Valve For A
Piston Pump Therapeutic Substance Delivery Device" by Olsen
(attorney docket no. P9746.00); "Implantable Therapeutic Substance
Delivery Device Having A Piston Pump With An Anti-Cavitation Valve"
by Olsen (attorney docket no. P9851.00); "Closed Loop Drug Delivery
System And Remote Management Thereof" by Thompson (attorney docket
no. P9622.00); and, "Transcutaneous Physiologic Monitoring System
Utilizing Therapeutic Electrical Stimuli From An Implanted Device
As A Signalling Mechanism" by Riff (attorney docket no. P10797.00
being filed on the same date as this application), which are not
admitted as prior art with respect to this application by its
mention in this cross reference section but which are incorporated
by reference herein.
FIELD OF THE INVENTION
[0003] The present invention generally relates to medical devices.
Specifically, the invention relates to a system, method and
apparatus relating to a therapeutic substance delivery patch for
attachment to a patient such that the patch is in contact with the
patient's skin, wherein the patch coordinates its delivery of the
therapeutic substance to the patient based on information received
relating to the operation of an implanted device in the patient.
Such information may be received through telemetry from the
implanted device, or alternatively from the patch sensing the
action of the implanted device, or alternatively from the patch
sensing the patient's physiologic reaction to the action taken by
the implanted device.
BACKGROUND OF THE INVENTION
[0004] Previously, a peripheral memory patch apparatus for
attachment to a patient's skin has been disclosed. U.S. Pat. No.
6,200,265 to Walsh et al., which is incorporated by reference
herein, discloses such a memory patch including a high capacity
memory for storing physiologic data uplinked from an implantable
medical device.
[0005] Furthermore, earlier patents discuss various transdermal
drug delivery devices. For example, U.S. Pat. No. 5,135,480 to
Bannon et al discloses a transdermal drug delivery device. More
specifically, the Bannon invention relates to a transdermal device
having a detachably mounted electrode with a first surface adapted
for contact with human skin and through which a drug substance
contained in the electrode passes to the skin under the influence
of an iontophoretic or electro-osmotic force and a second surface
which is electrically conducting, the electrode has a surface area
in contact with the skin, in use, in the range 0.1 to 30 square
centimeters and a drug dissolved or dispersed in a hydrophilic
medium at a concentration in the range 0.1 to 15% (w/v) based on
the hydrophilic medium.
[0006] Previous disclosures have also included the use of an
implanted medical device as a network device including an ultimate
result of delivering a drug to a patient. European Patent No.
1,022,035 to Arent discloses a network device that can be implanted
in a subject. The device is configured to communicate over an
internal wireless network or over an external computer network. In
one embodiment, the device includes an internal interface in
physiological communication with the subject. The internal
interface is coupled with, and configured to send signals to a
processor. The processor is configured to receive and process the
signals, and is further configured to communicate over a computer
network with another such device. Such devices can be used to
monitor and communicate information regarding a host's
physiological status, monitor and/or control natural and/or
artificial organs, and prosthetic devices, and/or dispense
medication. Drug delivery is accomplished through a separate drug
reservoir and intravenous line or through another implanted
device.
[0007] As can be seen by the above prior art, therapeutic substance
therapy in conjunction with the activities and information obtained
by an implanted medical device is an important consideration in the
overall treatment of a patient. However, there is a need for a
system, apparatus and method wherein a device is affixed to the
body in contact with the skin, wherein such device delivers a
therapeutic substance to the patient while allowing the patient to
remain mobile. While mobility might be achieved by a second
implanted drug delivery device, it is desired to avoid the
complications and invasiveness of a second implanted device for the
storage and delivery of the therapeutic substance.
BRIEF SUMMARY OF THE INVENTION
[0008] A system, method and apparatus relating to a therapeutic
substance delivery patch for attachment to a patient such that the
patch is in contact with the patient's skin, wherein the patch
coordinates its delivery of the therapeutic substance to the
patient based on information received relating to the operation of
the implanted device. The information received by the patch may be
received through telemetry from the implanted device, or
alternatively from the patch sensing the action of the implanted
device, or alternatively from the patch sensing the patient's
physiologic reaction to the action taken by the implanted
device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic of one embodiment of the system
according to the principles of the invention;
[0010] FIG. 2 is a schematic of one embodiment of a therapeutic
substance delivery patch according to the principles of the
invention;
[0011] FIG. 3 is a schematic of one embodiment of the system
according to the invention;
[0012] FIG. 4 is a top perspective partial cutaway view of another
embodiment patch according to the principles of the invention;
[0013] FIG. 5 is a bottom perspective view of the embodiment patch
of FIG. 4;
[0014] FIG. 6 is a top perspective view of the embodiment patch of
FIGS. 4 and 5;
[0015] FIG. 7 shows a permanent magnet solenoid pump of the
embodiment patch shown in FIG. 4;
[0016] FIG. 8 shows an exploded view of the permanent magnet
solenoid pump of FIG. 7 embodiment;
[0017] FIG. 9 shows an exploded view of a pump piston for a
permanent magnet solenoid pump three-coil embodiment for the patch
embodiment of FIG. 4;
[0018] FIG. 10 shows an isometric cross-section view of a pump
piston for a permanent magnet solenoid pump three-coil embodiment
for the patch embodiment of FIG. 4;
[0019] FIG. 11 shows a cross section view of a pump piston for a
permanent magnet solenoid pump three-coil embodiment for the patch
embodiment of FIG. 4;
[0020] FIG. 12 shows an isometric cross-section view of a permanent
magnet solenoid pump two-coil embodiment for the patch embodiment
of FIG. 4;
[0021] FIG. 13 shows a cross section view of a permanent magnet
solenoid pump two-coil embodiment for the patch embodiment of FIG.
4;
[0022] FIGS. 14a and 14b show a pump piston with an alternative
piston fluid path embodiments for the patch embodiment of FIG.
4;
[0023] FIG. 15 shows an outlet valve embodiment for the patch
embodiment of FIG. 4;
[0024] FIG. 16 shows a schematic of a two-coil permanent magnet
solenoid pump embodiment for the patch embodiment of FIG. 4;
[0025] FIG. 17 shows a schematic of a two-coil with permanent
magnet pole pieces permanent magnet solenoid pump embodiment for
the patch embodiment of FIG. 4;
[0026] FIG. 18 shows a schematic of a three-coil permanent magnet
solenoid pump embodiment for the patch embodiment of FIG. 4;
[0027] FIG. 19 shows a schematic of a three-coil with permanent
magnet pole pieces permanent magnet solenoid pump embodiment for
the patch embodiment of FIG. 4;
[0028] FIG. 20 shows a flow diagram of a method for operating a
permanent magnet solenoid therapeutic substance delivery device
embodiment for the patch embodiment of FIG. 4.
[0029] FIG. 21 represents another embodiment patch in
bi-directional communications with an implanted medical device;
[0030] FIG. 22 shows an external programmer or a remote home device
such as used to uplink and downlink data with both patch and the
implanted medical device for the embodiment of FIG. 21;
[0031] FIG. 23 represents one aspect of the remote communication
and monitoring system of the FIG. 21 embodiment;
[0032] FIG. 24 is a schematic block diagram of an automatic atrial
cardioverter and pain alleviating system of the FIG. 21 embodiment
of the present invention employing the automatic delivery of pain
alleviating drug therapy;
[0033] FIG. 25 illustrates another representative therapeutic
substance delivery patch;
[0034] FIG. 26 is a schematic drug delivery system block
diagram;
[0035] FIG. 27 represents a high-level logic flow diagram of the
FIG. 21 embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Preferred embodiments of this invention provide a method,
apparatus or system in which a smart externalized infusion patch
attached to the skin of a patient receives information from an
implantable medical device and infuses a therapeutic substance
based on the information.
[0037] A patch is defined as a device configured to be external to
the body, but also including the possibility of being partly
internal to the body (for example a patch may include a needle that
protrudes through the skin), wherein the device is configured to be
in contact with the skin of the patient. For example, a patch may
be adhered to the skin of the patient, it may be maintained in
contact via a strap such as with a wristwatch, it may be a ring
worn around a patient's finger, or it may be attached via a larger
strap worn around a patient's torso or other body part.
[0038] The patch may be attached to the skin of a patient at any
location on the patient where the patch can receive the necessary
information to make a determination to deliver a therapeutic
substance to the patient and advantageously deliver the therapeutic
substance. In a preferred embodiment the patch is near the location
of the implanted device to maximize ability to best receive the
information. However, any patch location is acceptable as long as
the patch is capable of receiving the information.
[0039] Via this remote interaction, the external patch is able to
read cardiac, neurological or other physiological patient data that
is accessed by the implanted medical device, and program the
external patch for therapeutic substance delivery. Among events may
be therapies that combine drug administration and electrical
stimulation for pain, atrial fibrillation (AF), heart failure (HF),
Parkinson disease, epilepsy, etc. by continually or periodically
obtaining physiologic input from the implanted device and then
subsequently controlling the delivery of solutions that have either
narrow therapeutic indices, strict patient compliance requirements,
or rapid delivery versus event detection requirements (e.g.,
ischemia).
[0040] Various preferred embodiments of this system and method may
be used for delivery of anti-arrhythmic drugs, diuretic drugs,
vasodilators, muscle relaxants, pain drugs, anti-clotting drugs,
blood thinners, anti-seizure drugs, naturitic peptides, insulin and
any other therapeutic substance whose administration would be
improved if the delivery could be optimally timed to the receipt of
physiological information from an implantable medical device.
[0041] FIG. 1 is a block diagram of a medical therapy system
including an implanted medical device 30 and a patch 32 for
attachment to the skin of a patient. The implanted medical device
(IMD) 30 may be any implanted medical device for providing a
therapy to a patient or for monitoring physiological information
about a patient or for providing both therapy and monitoring
functions. For example, IMD 30 may be any of the following, but is
not limited to a pacemaker, defibrillator, cardioverter,
pacemaker/cardioverter/defibrillator (PCD), oxygen sensing device,
nerve stimulator, brain stimulator, muscle stimulator, infusion
pump, drug delivery device, monitoring device, left ventricular
assist device or total artificial heart device.
[0042] The IMD 30 may include communication capabilities for
communicating with the patch 32. Such communication capabilities
may include telemetry or any other medical device communication
system.
[0043] IMD 30 may also include a sensor 31 for sensing a
physiological condition of the patient. The sensor 31 may sense
temperature; oxygen saturation; blood pressure; activity level,
lung wetness, glucose level, impedence, EKG, heart rate,
respiration rate, EMG, EEG, position of the patient and any host of
other physiologic conditions that are relevant to the delivery of a
therapeutic substance such as a drug. Many different types of
sensors for sensing the above conditions are known in the art.
[0044] Patch 32 includes a communication module 34, control module
36 and a delivery module 38. Patch 32 may optionally include a
sensor 33 whereby the patch 32 may obtain information regarding the
implanted device and/or physiologic condition by sensing as opposed
to by telemetry, or in combination with telemetric information.
Patch 32 is configured for attachment to the patient's body such
that the patch is in contact with the skin of the patient to
provide for mobility. Attachment of the patch 32 to the skin of the
patient may be through adhesives, straps, or any other means
known.
[0045] Communication module 34 provides telemetry or other
communication capabilities that allow the patch 32 to communicate
with the IMD 30.
[0046] Control module 36 functions to control the operation of the
patch 32 including control of the therapeutic substance delivery
functions.
[0047] Delivery module 38 includes a reservoir for holding the
therapeutic substance and therapeutic substance delivery means for
providing the therapeutic substance to the patient in an
appropriate amount.
[0048] The patch 32 may optionally include the capability to
communicate with systems outside the patient. For example, the
patch 32 may communicate with a network that in turn communicates
with the Internet. Physicians, patients and others may then access
any information deemed useful. Furthermore, data may be downloaded
for storage and review.
[0049] The patch 32 may optionally include the capability to
provide an indication to the patient, doctor or others regarding
the condition of the patient through indicator 40. Indicator 40 may
reside on the patch 32 or it may be located elsewhere and
communicate with the patch through telemetry or any other medical
device communication means.
[0050] One embodiment of the invention resides in a therapy for
administering a therapeutic substance to a patient having an
implanted medical device. The method includes attaching a patch 32
containing the therapeutic substance to the patient's body such
that the patch is in contact with the skin of the patient. The
method further includes generation of a signal from the IMD 30. In
response to the signal generated by the medical device, the patch
then administers the therapeutic substance to the patient.
[0051] Numerous, more specific, example therapies of the above
embodiment of the invention are provided below. It is noted
however, that the inclusion of these examples is not meant to be
limiting to the scope of the present invention. The absence of any
additional examples does not exclude such therapies from being
covered by the claims appended hereto.
[0052] For the disease state of hyper or hypotension the likely
parameter sensed by the implanted medical device is blood pressure.
Blood pressure may be monitored by the implanted Chronicle.RTM.
hemodynamic monitor sold by Medtronic, Inc. Other blood pressure
monitors may also be used.
[0053] When high blood pressure is sensed by the implanted monitor
or other device, such information is sent to the external patch
device by telemetry or other wireless communication. The external
patch device then determines whether to provide a therapeutic
substance to the patient and how much therapeutic substance to
provide.
[0054] Some drugs that may be used to treat hyper or hypotension
include diuretic drugs such as Furosemide and Bumentanide; beta
blockers such as Propranolol and Metaprolol; and vasodilators such
as Nitroglycerine and Isosorbide. However, the scope of this
invention is not limited by the use of the drugs listed here.
Certainly any drugs that have a therapeutic effect on hyper or
hypotension, or that have an effect on any negative effects of the
treatment by the implanted device, or that are developed in the
future, are contemplated for use by this invention.
[0055] For the disease state of epilepsy and the associated
seizures, the likely parameter sensed by the implanted medical
device is the electric potentials of the brain, which is oftentimes
recorded in an electroencephalogram (EEG). Electric potential of
the brain may be measured by electrodes attached to the scalp or in
other locations near the brain. Electric potentials in the brain
may also be measured by deep brain stimulation leads (DBS leads) or
cortical surface electrodes. In this case the likely implanted
medical device is a neurostimulator. However, other implanted
devices that have the capability to sense electric potentials of
the brain may be used.
[0056] When seizure activity is anticipated, predicted or detected
by the implanted medical device such information is sent to the
external patch device by telemetry or other wireless communication.
The external patch device then determines whether to provide a drug
to the patient and how much drug to provide.
[0057] Some drugs that may be used for epilepsy therapy include
Phenytoin and Conantonkin-G. However, the scope of this invention
is not limited by the use of the drugs listed here. Certainly any
drugs that have a therapeutic effect on epileptic seizure activity,
or that have an effect on any negative effects of the treatment by
the implanted device, or that are developed in the future are
contemplated for use by this invention.
[0058] For the disease state of diabetes, including hyperglycemia
and hypoglycemia, the likely parameter sensed is glucose level in
the blood or tissue. Glucose level may be measured through many
well known methods and devices including, for example, the use of
an implanted glucose monitor.
[0059] When the implanted glucose monitor senses hyperglycemia, the
implanted glucose monitor sends such information to the external
patch device by telemetry or other wireless communication. The
external patch device then determines whether to provide insulin or
glucagons to the patient. For the case of hyperglycemia the
external patch device delivers insulin to the patient. For the case
of hypoglycemia the external patch device delivers glucagons to the
patient.
[0060] For the disease state of ischemic heart disease, the likely
parameter sensed is heart rate or arrythmias. Heart rate may be
sensed, for example, by a pacemaker lead.
[0061] When the implanted pacemaker senses a heart rate above a
certain point, the pacemaker sends such information to the external
patch by telemetry or other wireless communication. The external
patch then determines whether to provide nitrates/BNP, biologics or
peptides to the patient.
[0062] For the disease state of myocardial infarction, the likely
parameter sensed by the implanted medical device is abnormalities
in the EKG. EKG may be sensed by many methods and devices known
including, for example, an implanted pacemaker or sensor such as a
Reveal.TM. implanted loop recorder.
[0063] When the implanted pacemaker or monitor senses abnormalities
in the EKG, the implanted device sends such information to the
external patch by telemetry or other wireless communication. The
external patch then determines whether to provide an anticoagulant
such as heparin or Tissue Plasminogen Activator (TPA) or an
anti-arrythmic drug to the patient.
[0064] Another embodiment therapy of the invention, a method of
administering a therapeutic substance to a patient in response to a
sensed reading of the patient's physiologic reaction to an action
taken by an implanted device is provided. The method includes
attaching a patch containing the therapeutic substance to the
patient such that the patch is in contact with the skin of the
patient and a sensor for sensing a physiologic reaction to the
action taken by the medical device. The method further includes
sensing with the sensor the physiologic reaction to the action
taken by the implanted medical device. The method also includes
administering the therapeutic substance to the patient in response
to the reaction sensed by the sensor.
[0065] A more specific example of the above alternative embodiment
therapy relates to respiratory depression in response to delivery
of morphine. In this example, the implanted medical device is an
implanted drug pump such as the Synchromed.RTM. implantable drug
pump made by Medtronic, Inc. The implanted drug pump may be used to
deliver an opioid, such as morphine, fentanyl, sufentanil, and
hydromorphone, to the spinal cord. Patients taking morphine may
experience respiratory depression as a side effect. Therefore, if
the patch senses a respiration rate that is lower than normal, it
may respond by delivering a narcotic antagonist to the patient. The
narcotic antagonist counters the effects of the morphine or other
opioid. An example narcotic antagonist is naloxone. Respiration
depression may also be sensed by the patch by sensing parameters
such as heart rate, temperature, activity, galvanic response, etc.
Note alternatively that respiration rate could also be sensed
directly by the IMD and communicated to the patch for a drug
delivery response.
[0066] Another example therapy in which the patch senses the
physiologic reaction to the action taken by the IMD relates to
bupivicaine drug delivery. In the example of bupivicaine drug
delivery by an implanted drug pump, cardiotoxicity can occur
resulting in a higher, then a very low heart rate. The patch could
detect those higher and then lower heart rates and infuse a
vasodilator such as epinephrine.
[0067] Another embodiment of the invention resides in a therapy for
administering a therapeutic substance to a patient having an
implanted medical device. The method includes attaching a patch 32
containing a therapeutic substance, the patch including a sensor
33, to the patient such that the patch is in contact with the skin
of the patient. The method further includes sensing with the sensor
the action taken by the implanted medical device and administering
the therapeutic substance to the patient in response to the action
sensed by the sensor.
[0068] Another embodiment of the invention resides in a therapy for
administering a therapeutic substance to a patient having an
implanted medical device that is adapted to take an action on the
patient. The method includes attaching a patch containing the
therapeutic substance to the patient such that the patch is in
contact with the skin of the patient. The patch includes a sensor
for determining if the medical device has taken an action on the
patient. The method further includes determining with the sensor
whether the medical device has taken an action on the patient. The
method further includes administering the therapeutic substance to
the patient in response to the determination carried out in the
determining step.
[0069] One embodiment of therapeutic substance delivery patch 32 is
patch 45 shown in FIG. 2. Patch 45 includes an antenna 47 for
telemetry applications, an integrated circuit 49, battery 51, valve
53, drug reservoir 55 and drug propulsion means 57.
[0070] One embodiment system includes patch 59 and implanted
medical device 61. Implanted medical device 61 includes a
therapeutic block 63 and communication block 65. The therapeutic
block 63 is configured to provide some therapy to the patient's
body. Patch 59 includes a communication block 67 for communicating
with the implanted medical device 61, sensing block 69 including a
sensor for the capability of sensing conditions in the body,
therapy control block 71, power management block 73 for managing
the power resources on board the patch, patient control block 75,
and overhead blocks 77.
[0071] Various means for delivering the therapeutic substance from
the reservoir on the patch to the patient are considered for this
invention including, but not limited to, hypodermic needle,
implanted catheter access port and iontophoresis.
[0072] It is also noted that the patch of the invention or a
portion of the patch may be disposable. For example, the
therapeutic substance reservoir could be disposable and replaced
with a new reservoir module after the therapeutic substance is
used.
Detailed Exemplary Embodiment Patch (Patch 130)
[0073] Another embodiment of patch 32 of the present invention will
now be described in conjunction with FIGS. 4-20. FIG. 4 shows a
therapeutic substance delivery patch 130. Patch 130 includes a
housing 141, therapeutic substance reservoir 142, a power source
144, electronics 146, and a permanent magnet solenoid pump 148.
[0074] The above components of the patch may be contained within a
single housing member or may be provided in a two member housing
such as shown in FIG. 4. In the embodiment of FIG. 4, housing 141
includes a base portion 110 for positioning adjacent the skin of
the patient (see FIG. 5), as well as two upper housing members 112
and 114.
[0075] Base portion 110 is designed to be positioned adjacent the
exterior of the patient's skin surface. Base portion 110 may be
flat or it may be curved somewhat to fit along the curvatures of
the patient's body at the point of application.
[0076] In one embodiment, base portion 110 includes an adhesive on
the side adjacent the skin surface for attaching the patch to the
patient's skin. Other means for attaching the patch 130 may be
utilized such as a strap or belt.
[0077] The upper housing member 112 forms the reservoir 142
configured for containing a therapeutic substance 136 and may use
geometries such as metal bellows, polymeric bag, and the like. The
therapeutic substance reservoir 142 has a reservoir outlet 152 and
can have a septum 140 for refilling the reservoir 142. The patch
130 operates to infuse the therapeutic substance 136 at a
programmed rate into a patient.
[0078] A therapeutic substance 136 is a product or substance
intended to have a therapeutic effect such as pharmaceutical
compositions, genetic materials, biologics, and other substances.
Pharmaceutical compositions are chemical formulations intended to
have a therapeutic effect such as antispasmodics, analgesics, pain
medications, chemotherapeutic agents, and the like. Genetic
materials are substances intended to have a direct or indirect
genetic therapeutic effect such as genetic vectors, genetic
regulator elements, genetic structural elements, DNA, and the like.
Biologics are substances that are living matter or derived from
living matter intended to have a therapeutic effect such as stem
cells, platelets, hormones, biologically produced chemicals, and
the like. Other substances are substances intended to have a
therapeutic effect yet are not easily classified such as saline
solution, fluoroscopy agents, and the like.
[0079] The power source 144 is carried in the housing member 114 of
housing 141. The power source 144 is selected to operate the
solenoid pump 148 and electronics 146 such as a lithium ion (Li+)
battery, capacitor, and the like. The electronics 146 are coupled
to the power source 144 and typically include memory and a
controller. The controller can be an Application Specific
Integrated Circuit (ASIC) state machine, a gate array, or may
include a microprocessor. The electronics 146 are configured to
control the solenoid pump 148 infusion rate and can be configured
to operate many other features such as patient alarms and the like.
The electronics 146 can also include telemetry circuitry configured
to receive and send information when the therapeutic substance
delivery device 130 is implanted to allow programming of the
infusion rate. In this embodiment, the telemetry antenna 116 is
positioned on the base portion 110. The solenoid pump 148 is
coupled to the electronics 146 and coupled to the therapeutic
substance reservoir outlet 152 and configured for pumping
therapeutic substance 136 from the therapeutic substance reservoir
142 through an infusion needle 154 at a programmed rate.
[0080] Infusion needle 154 is configured for insertion through a
patient's skin for delivery of the therapeutic substance into the
body. In one implementation of the therapy, the patch 130 may be
attached to the patient's skin for about 4-8 days with the needle
inserted through the skin. Various methods known in the art may be
utilized to prevent infection with such a system.
[0081] FIGS. 7-11 show a three coil embodiment of the solenoid
pump. The permanent magnet solenoid pump 148 comprises a pump
cylinder 156, a pump piston 158, a biasing element 160, an inlet
valve 162, an outlet valve 164, a permanent magnet 166, a first
coil 168, and a second coil 170. The solenoid pump 148 is coupled
to the electronics 146, the therapeutic substance reservoir outlet
152, and the needle 154. The solenoid pump 148 is configured for
pumping therapeutic substance 136 from the reservoir 142 through
needle 154 at a programmed rate.
[0082] The pump cylinder 156 has an inlet enclosure 172, an outlet
enclosure 174, a therapeutic substance inlet 176, and an infusion
needle 154. The inlet enclosure 172 transitions the pump cylinder
156 to the therapeutic substance inlet 176. The outlet enclosure
174 transitions the pump cylinder 156 to the infusion needle 154.
The therapeutic substance inlet 176 is coupled to a therapeutic
substance reservoir outlet 152 and coupled to the inlet enclosure
172 on the pump cylinder 156. Some embodiments can include a piston
seal 178 positioned between the pump cylinder 156 and the pump
piston 158 to reduce therapeutic substance 136 flow between the
pump piston 158 and the pump cylinder 156 and provide other
functions. The piston seal 178 can be configured to serve as a
guide for the biasing element 160 and to cushion the pump piston
158 at the end of pump piston 158 retraction for the intake stroke.
The piston seal 178 is manufactured from a resilient material with
good sealing qualities such as synthetic rubber, PTFE, silicone,
and the like.
[0083] The pump piston 158 is moveable within the pump cylinder 156
and has a piston inlet end 180, a piston outlet end 182, and a
piston fluid path 184. The pump piston 158 forms an inlet chamber
186 between the pump piston 158 and the inlet enclosure 172 and a
pumping chamber 188 between the pump piston 158 and the outlet
enclosure 174. The inlet chamber 186 contains the therapeutic
substance 136 that is displaced when the pump piston 158 retracts.
The pumping chamber 188 contains the therapeutic substance 136 that
is displaced when the pump piston 158 is actuated. The piston fluid
path 184 is configured to provide fluid communication between the
inlet chamber 186 and the pumping chamber 188 that is controlled by
the inlet valve 162. The piston fluid path 184 can take a wide
variety of forms such as a central fluid path, a side fluid path, a
partial central and partial side fluid path, and the like.
[0084] The biasing element 160 is positioned in the pump cylinder
inlet chamber 186 between the pump piston 158 and the inlet
enclosure 172. The biasing element 160 exerts force on the pump
piston 158 to expulse therapeutic substance 136 through the
infusion needle 154. In some embodiments, the biasing element 160
exerts substantially the sole force on the pump piston 158 to
expulse therapeutic substance 136 through the infusion needle 154.
The biasing element 160 also provides force to maintain the pump
piston 158 in an actuated position until retracted to seal the
inlet valve 162 against the outlet enclosure 174 to provide
redundant protection against unintended flow of therapeutic
substance 136 to the patient. The biasing element 160 can be one or
more of a wide variety of biasing structures that are selected to
provide the desired biasing force on the pump piston 158. The
desired force of the biasing element 160 in a particular embodiment
is the force required to overcome any frictional losses during the
pump piston 158 expulsion stroke and to generate pressure to open
the outlet valve 164. Some specific embodiments of the biasing
element 160 include a spring, a coil spring, and the like.
[0085] The inlet valve 162 is carried on the pump piston outlet end
182. The inlet valve 162 can be a variety of inlet valves 162 such
as a flapper valve, annular flapper valve, ball valve, reed valve,
duckbill valve, poppet valve, and the like. The outlet valve 164 is
carried in the outlet enclosure 174 and coupled to the infusion
needle 154. The outlet valve 164 improves solenoid pump 148 safety
by substantially preventing unintended flow of therapeutic
substance 136 when the reservoir 142 pressure is greater than the
infusion site 134 pressure. The outlet valve 164 improves solenoid
pump 148 accuracy by maintaining sufficient back pressure to keep
the inlet valve 162 closed during therapeutic substance 136
expulsion through the infusion needle 154 so that addition
therapeutic substance 136 is not infused when the reservoir 142
pressure is greater than the infusion site 134 pressure. The outlet
valve 164 can be a variety of outlet valves 164 such as a flapper
valve, ball valve, reed valve, duckbill valve, poppet valve, and
the like. An outlet valve embodiment is shown in FIG. 15.
[0086] Some embodiments of the solenoid pump 148 can include an
anti-cavitation valve 190 positioned in fluid communication with
the therapeutic substance inlet 176. The anti-cavitation valve 190
substantially prevents therapeutic substance 136 in the inlet
chamber 186 from flowing back through the therapeutic substance
inlet 176 during pump piston 158 retraction. Since the therapeutic
substance 136 cannot flow backwards, pressure in the inlet chamber
186 increases as the pump piston 158 retracts causing the
therapeutic substance 136 to flow through the piston fluid path 184
without causing the pump chamber 188 pressure to drop low enough to
cause dissolved gasses to come out of solution. Also by
substantially preventing the back flow of therapeutic substance 136
through the therapeutic substance inlet 176 during pump piston 158
retraction, piston pump 158 efficiency is improved because wasted
therapeutic substance 136 flow is minimized. The anti-cavitation
valve 190 can be a wide variety of anti-cavitation valves 190 such
as a flapper valve, annual flapper valve, ball valve, reed valve,
duckbill valve, poppet valve, and the like. In addition to
displacing therapeutic substance 136 that operates the inlet valve
162, outlet valve 164, and anti-cavitation valve 190, the pump
piston 158 carries a permanent magnet 166.
[0087] The permanent magnet 166 is at least a first permanent
magnet 166 having a first pole 192 and a second pole 194. The
permanent magnet 166 is carried by the pump piston 158 and acted on
by the magnetic fields created by the coils 167 that include at
least the first coil 168 and at least the second coil 170. When the
first coil 168 and second coil 170 are energized, the coils 167
produce an electromagnetic axial force that acts on the permanent
magnet 166 to impart motion to the pump piston 158. In some
embodiments, there can be more than one permanent magnet 166 such
as a first permanent magnet 166, a second permanent magnet 196, a
third permanent magnet 198 and so forth. Also in some embodiments,
there can be more than a first coil 168 and second coil 170 such as
a third coil 171 and so fourth. When using more than one permanent
magnet 166, like poles are positioned adjacent to one another, and
there are N-1 operational permanent magnets 166 where N is the
number of coils 167 in the range from about 3 to 10. The permanent
magnet 166 is manufactured from a hard ferromagnetic material such
as samarium cobalt, neodymium, ceramic, alnico, and the like. Since
the permanent magnet 166 material is typically not therapeutic
substance compatible or biocompatible, the permanent magnet 166 is
typically isolated from the therapeutic substance 136 by the piston
fluid path 184 and the pump piston 158 sealed is by the piston
inlet end 180 and piston outlet end 182. Positioned in operating
relationship to the permanent magnet 166 are the first coil 168 and
the second coil 170. An alternative solenoid pump 148 embodiment
using two coils 167 is shown in FIGS. 12-13.
[0088] FIGS. 16-19 show block diagram of some of the permanent
magnet solenoid pump 148 permanent magnet 166 and coil 167
embodiments. There is at least a first coil 168 configured around
the pump cylinder 156 positioned adjacent to the first pole 192 of
the permanent magnet 166, and at least a second coil 170 configured
around the pump cylinder 156 positioned adjacent to the second pole
194 of the permanent magnet 166. The first coil 168 and the second
coil 170 can be reversed in relation to the permanent magnet 166,
so the first coil 168 is adjacent to the second pole 194 and the
second coil 170 is adjacent to the first pole 192. Other
embodiments of the permanent magnet solenoid pump 148 can have more
than a first coil 168 and second coil 170 such as a third coil 171
or N operational coils where N is an integer in the range from
about 3 to 10. When the solenoid pump 148 is configured with N
coils there will be N-1 operational permanent magnets 166. The
following discussion will use the term coil 167 to refer a first
coil 168 and a second coil 170, or N coils and permanent magnet 166
to refer to a first permanent magnet 166 or N-1 permanent
magnets.
[0089] The coils 167 are typically wound in opposite directions, so
current flows in opposite directions to generate opposing magnetic
fields. Alternatively, the coils 167 can be wound in the same
direction and the voltage polarity applied to the coils 167 can be
opposing to cause current to flow in opposite directions to
generate opposing magnetic fields. The coils 167 are configured to
create a force in one direction for one permanent magnet pole 192
and in the same direction for the other permanent magnet pole 194.
The coils 167 are energized for pump piston 158 retraction toward
the inlet enclosure 172 to fill the pump chamber 188 from the inlet
chamber 186. Since the coils 167 are not typically compatible with
therapeutic substances or biocompatible, the coils 167 are
typically isolated from the therapeutic substance 136 by the pump
cylinder 156 and isolated from the patient 138 by the housing 141.
The pump cylinder 156 is manufactured from any therapeutic
substance compatible material that meets design requirements such
as titanium, tantalum, stainless steel, plastic, ceramic, and the
like. The permanent magnet 166 and coils 167 can be inserted into
the pump cylinder 156 along with the pump piston 158 and then the
inlet enclosure 172 and outlet enclosures 174 can be welded to
isolate the permanent magnet 166 and coils 167 from the therapeutic
substance 136. The coil's 167 electromagnetic axial force can be
enhanced with a magnetically permeable yoke 200 and pole pieces
202.
[0090] The magnetically permeable yoke 200 and pole pieces 202,
although not required for operation, enhance the electromagnetic
axial force created by the coils 167. The magnetically permeable
yoke 200 is placed around the coils 167 to improve magnetic
efficiency. The magnetically permeable yoke 200 also shields the
permanent magnet 166 from external high magnetic fields, until the
magnetically permeable yoke 200 becomes saturated, to protect the
permanent magnet 166 from demagnetization. The external high
magnetic field can be created by equipment such as Magnetic
Resonance Imaging (MRI) equipment, magnetic security equipment, and
the like. The pole pieces 202 can be positioned adjacent to one or
more of the permanent magnet's 166 poles. For example, a first pole
piece 204 can be carried on the pump piston 158 between the
permanent magnet 166 and the inlet enclosure 172 to improve
magnetic coupling. A second pole piece 206 can be carried on the
pump piston 158 between the permanent magnet 166 and the outlet
enclosure 174 to improve magnetic coupling.
[0091] When the pump piston 158 is fully positioned toward the
inlet enclosure 172, the maximum pump chamber 188 volume is
created. The pump chamber 188 has a pump chamber 188 volume
comprising a stroke volume and a dead volume. The stroke volume is
in the range from about 0.5 micro liters to about 5.0 micro liters.
The sum of an inlet valve 162 opening pressure and the outlet valve
164 opening pressure exceeds the maximum pressure of the reservoir
142 less the infusion site 134 pressure to substantially prevent
free flow of therapeutic substance 136 to the patient. The dead
volume is less than half the stroke volume in the range from about
0.25 micro liters to about 2.5 micro liters. The solenoid pump's
148 small dead volume compared to the stroke volume improves the
solenoid pump's 148 capability to pass air because of the low
vacuum pressure that is typically generated in the pump chamber
188. The inlet valve 162 and outlet valve 164 opening pressures are
selected to prevent unintended infusion under extreme operating
conditions. Unintended infusion is substantially prevented by
selecting the inlet valve 162 opening pressure and the outlet valve
164 opening pressure so the sum of these pressures is greater than
the maximum pressure difference between the reservoir 142 and the
infusion site 134. For example, unintended infusion is prevented
when the reservoir 142 pressure is high and the ambient pressure
(typically the same as the infusion site 134 pressure) is low that
can occur when the reservoir 142 is full and the patient is exposed
to high temperature at high altitude.
[0092] The solenoid pump's 148 ability to pass air and operate
accurately is a function of the solenoid pump's 148 compression
ratio, the reservoir outlet 152 pressure, the infusion needle 154
pressure, and outlet valve 164 cracking (opening) pressure. For
adiabatic systems with ideal gases, the compression ratio in the
pump chamber 188 can be expressed as 1 CR pc = V pc final V pc
initial ( Equation 1 )
[0093] where CR.sub.pc is the compression ratio in the pump chamber
188, V.sub.pc final is the final volume in the pump chamber 188
calculated by (stroke volume+pump chamber dead volume) where stroke
volume=piston area.times.piston stroke, and V.sub.pc initial is the
initial volume in the pump chamber 188 also known as the pump
chamber dead volume which is also the pump chamber volume remaining
after the pump piston 158 has expulsed the stroke volume. The
compression ratio in the inlet chamber 186 can be expressed as 2 CR
ic = V ic final V ic initial ( Equation 2 )
[0094] where CR.sub.ic is the compression ratio in the inlet
chamber 186 and V.sub.ic is the volume in the inlet chamber 186,
V.sub.ic final=(stroke volume+inlet chamber dead volume), and
V.sub.ic initial=(inlet chamber dead volume). From these
relationships, it is apparent that pump chamber 188 pressure will
be decreasing and inlet chamber 186 pressure will be increasing as
the pump piston 158 retracts. For therapeutic substance 136 to flow
into the pump chamber 188 when gas bubbles are present, the
pressure in the pump chamber 188 during the pump piston 158 stroke
must drop substantially below the inlet chamber 186 pressure. For
therapeutic substance 136 to flow out of the pump chamber 188, the
expulsion pressure must be greater than the infusion needle 154
pressure. Therapeutic substance 136 flows through the outlet valve
164 when P.sub.pc.gtoreq.P.sub.a+P.sub.ovc, where P.sub.pc is the
pressure in the pump chamber 188, P.sub.a is the ambient pressure
at the infusion outlet 154, and P.sub.ovc is outlet valve 164
cracking (opening) pressure. By selecting the appropriate outlet
valve 164 cracking pressure the risk of unintentional infusion can
be substantially eliminated.
[0095] The permanent magnet solenoid pump 148 is designed to be
energy efficient consuming less than about 3.0 Joules per
milliliter (J/ml) at about 137,895 pascals (20 pounds/square inch)
back pressure. The solenoid pump 148 is about 5% to 10% efficient
in terms of electrical energy input and fluid work output. The
energy efficiency of the solenoid pump 148 to a large degree
determines energy efficiency of the therapeutic substance delivery
patch 130 and the size of power source 144 needed. For example,
doubling solenoid pump 148 efficiency can theoretically result in
nearly a 50% reduction in energy consumption and a 50% reduction in
the size of power source 144. Additionally, the solenoid pump 148
can be a wide variety of sizes. The design of the solenoid pump 148
permits small sized configuration such as less than about 20.0 mm
long by about 6.0 mm in diameter with a total volume less than
about 0.5 cc. The small size of the solenoid pump 148 also permit
having a small therapeutic substance delivery patch 130 that can be
more inconspicuously attached to a patient's skin such as under
clothes, including on arms, legs, torso or other areas.
Operation (Patch 130 Embodiment)
[0096] FIG. 20 shows a flowchart of a method for operating a
therapeutic substance delivery patch 130 having a permanent magnet
solenoid pump 148 embodiment. The therapeutic substance 136 is
supplied from a therapeutic substance reservoir 142 to a
therapeutic substance inlet 176. The solenoid pump 148 generally
operates by retracting a pump piston 158 and then actuating the
pump piston 158 while operating valves to deliver therapeutic
substance 136 through an infusion needle 154 at a programmed rate.
This operation is repeated a predetermined number of times at
predetermined intervals to delivery therapeutic substance 136 at
the programmed rate. For example, a solenoid pump 148 with a stroke
volume of 2.0 micro liters would typically be operated from a
maximum of about 10 cycles per second (Hz) to achieve an infusion
rate of 1.2 milliliters per minute to a minimum of about 1.0 cycle
per hour to achieve an infusion rate of about 48 micro liters per
day.
[0097] Retracting the pump piston 158 is initiated when a first
coil 68 for current flow in a first direction is energized 112 and
a second coil 170 for current flow in an opposite direction are
energized 212 to create a electromagnetic axial force. The pump
piston 158 is retracted 214 when the electromagnetic axial forces
acts on a permanent magnet 166 carried on the pump piston 158.
While the pump piston 158 is retracting, an inlet valve 162 is
opened 216 and a biasing element 160 is loaded. A pump chamber 188
is filled with therapeutic substance 136 through the inlet valve
162 while the pump piston 158 is being retracted 214. In an
embodiment having a piston seal 178, during pump piston 158
retraction the piston seal 178 can also be configured to dampen the
shock when the pump piston 158 reaches its fully retracted
position. By dampening this shock, the piston seal 178 can reduce
some wear and noise that occurs when the pump piston 158 reaches
its fully retracted position. In embodiments having an
anti-cavitation valve 190, the anti-cavitation valve 190 prevents
therapeutic substance 136 in the inlet chamber 186 from flowing
back to the therapeutic substance reservoir 142 when the pump
piston 158 retracts. The anti-cavitation valve 190 helps maintain
higher pump chamber 188 pressures during pump piston 158
retraction, which makes it easier to pass air bubbles.
[0098] During pump piston 158 retraction assuming there is
anti-cavitation valve 190 and both the inlet chamber 186 and pump
chamber 188 are filled with therapeutic substance 136, the pressure
in the inlet chamber 186 will increase rapidly due to the
incompressibility of liquids which will cause the therapeutic
substance 136 to flow through the piston fluid path 184 into the
pump chamber 188 without causing the pump chamber 188 pressure to
decrease to the level that would cause gasses to come out of
solution. After the pump piston 158 is retracted, operation of the
solenoid pump 148 continues when the pump piston 158 is
actuated.
[0099] Actuating the pump piston is initiated when the first coil
168 for current flow in the first direction is de-energized 222,
and the second coil 170 for current flow in the opposite direction
is de-energized 222 to collapse the electromagnetic axial force. As
the electromagnetic axial force collapses, the biasing element 160
is unloaded, and the pump piston 158 is actuated by the biasing
element 160 driving the pump piston 158 toward the outlet enclosure
174. While the pump piston 158 is being actuated 226, pressure
generated in the pumping chamber 188 opens the outlet valve 164.
The open outlet valve 164 permits a stroke volume to be expulsed
through the infusion needle 154 while the pump piston 158 is
actuated 226. The therapeutic substance 136 discharged through the
infusion needle 154 is delivered at a programmed rate. In some
embodiments during pump piston actuation 226, the piston seal 178
substantially prevents therapeutic substance 136 from flowing
around the pump piston 158 back into the inlet chamber 186. The
previously discussed method embodiment elements are presented in a
general sequence that is intended to be limiting only when a
particular element is required to be sequence in a certain way for
the entire method embodiment to be practical. Pump piston actuation
226 can be mathematically characterized.
[0100] During piston actuation 226 to expulse therapeutic substance
136, when the pump chamber 188 volume is decreasing and the inlet
chamber 186 volume is increasing the following relationships exist.
The final pressure in the pump chamber 188 can be express as 3 P pc
final = P pc initial CR pc ( Equation 3 )
[0101] where P.sub.pc final is the final pressure in the pump
chamber 188, P.sub.pc initial is the initial pressure in the pump
chamber 188, and CR.sub.pc is the compression ratio in the pump
chamber 188. The final pressure in the inlet chamber 186 can be
expressed as 4 P ic final = P ic initial CR ic ( Equation 4 )
[0102] where P.sub.ic final is the final pressure in the inlet
chamber 186, P.sub.ic initial is the initial pressure in the inlet
chamber 186, and CR.sub.ic is the compression ratio in the pump
chamber 188. Therapeutic substance 136 flows through the outlet
valve 164 when P.sub.pc final.gtoreq.P.sub.a+P.sub.ovc (Equation 5)
where P.sub.ic is the initial pressure in the inlet chamber 186,
P.sub.a is the ambient pressure at the pump outlet, and P.sub.ovc
is outlet valve 164 cracking (opening) pressure. The above
relationships assume that there is an anti-cavitation valve 190,
there is no air in the pump chamber 188, and since liquids are
essential incompressible P.sub.ic decreases as the pump piston 158
is actuated.
[0103] Thus, embodiments of the solenoid pump 148 are disclosed to
increase energy efficiency, increase accuracy, reduce the
residential space requirement, improve therapeutic substance
compatibility, and provide many other improvements. One skilled in
the art will appreciate that the present invention can be practiced
with embodiments other than those disclosed. The disclosed
embodiments are presented for purposes of illustration and not
limitation, and the present invention is limited only by the claims
that follow.
Detailed System Example (IMD 312 and Patch 320)
[0104] A detailed system example different from the examples
provided above including an implanted medical device 30 and
therapeutic substance delivery patch 32 utilized in conjunction
with delivery of therapy by the implanted medical device 30 is
provided in conjunction with FIGS. 21-27.
[0105] FIG. 21 is an illustration of an implantable medical device,
IMD 30, adapted for use to communicate with an externally mounted
therapeutic substance delivery patch 32. The IMD implanted in
patient 10 includes IMD 312. IMD 312 is a pacemaker, implanted
cardioverter/defribillator (ICD) or combined pacemaker/ICD device.
In accordance with conventional practice in the art, IMD 312 is
housed within a hermetically sealed biologically inert outer casing
which may itself be conductive so as to serve as an indifferent
electrode in the IMD's pacing cardioversion/sensing circuit. One or
more pacemaker leads collectively identified with reference number
314 are electrically coupled to NID 312 in a conventional manner
and extend into the patient's heart 316 via vein 318. Disposed
generally near the distal end of leads 314 are one or more exposed
conductive electrodes for receiving electrical cardiac signals
and/or for delivering electrical pacing and/or
cardioversion/defibrillati- on stimuli to heart 316. As will be
appreciated by those of ordinary skill in the art, leads 314 may be
implanted with distal ends situated in the atrium and/or ventricle
of heart 316.
[0106] In this embodiment of the invention, patch 32 is patch 320.
As depicted in FIG. 21, patch 320 is linked via telemetry
transmission 321 to IME 312.
[0107] FIG. 22 is a variation of FIG. 21 in which programmer 322 is
shown in communication with implanted medical device 312 and patch
320. Specifically, programming unit 322 is in telemetry or wireless
communication with implanted medical device 312 and patch 320 via
uplink and downlink communication channels 323 and 323',
respectively. Programmer 322 described herein with reference to
FIG. 21 is disclosed in more detail in U.S. Pat. No. 5,345,362
issued to Thomas J. Winkler entitled "Portable Computer Apparatus
with Articulating Display Panel" which patent is hereby
incorporated herein by reference in its entirety.
[0108] FIG. 23 is another embodiment of the present invention
wherein data is communicated using various media to transfer
information from IMD 312 and patch 320 via programmer, IRM or
equivalent device 322. As discussed hereinabove data from IMD 312
and patch 320 is uplinked to device 322 from which it may be
directed to a PC 324 or server 326 using, for example, a modem, an
ISDN line, fiber optic, cable, infrared, bluetooth-enabled or
equivalent direct or wireless communication systems. Server 326 is
also accessible directly to qualified users at station 328.
Further, server 326 may be accessible via Internet 330 to remote
users 332.
[0109] With this exemplary communication network, caregivers,
physicians and other qualified personnel may be able to access and
review or reprogram the operations of IMD 312 and patch 320
remotely. For example, user 328 may use a LAN1 or other secure
lines to access server 326 from which either current or stored data
relating to the operation of IMD 312 and patch 320 could be
obtained for evaluation and adjustment, or remote patient
monitoring. Similarly, remote users at station 332 may be able to
access operational and functional data of IMD 312 and patch 320 via
Internet 330.
[0110] One of the aspects of this embodiment of the present
invention is the use of a transdermally operable patch 320. It is
similar to the electrotransport drug delivery system disclosed in
Design Patent No. 384,745 to Lattin et al. Further, a similar
device is disclosed in U.S. Pat. No. 5,995,869 to Cormier et al.
Additionally, electrotransport delivery device with voltage
boosting circuit is disclosed in U.S. Pat. No. 6,035,234 to Riddle
et al. And an electrotransport device and method of setting the
output using the same drug delivery device is disclosed in U.S.
Pat. No. 6,086,572 to Johnson et al. which patent applications are
incorporated herein by reference in their entireties. Any of these
therapeutic substance delivery patches as well as others may be
used within the scope of the present invention.
[0111] The present invention implements a highly adaptable
communication link between the implanted device and the drug
delivery device disclosed in the prior art. The communication
system as indicated hereinabove without limitation could be
telemetry or as substantially described in U.S. Pat. Nos. 5,683,432
and 5,843,139, or an equivalent medical device communication system
such as the one disclosed in U.S. Pat. No. 4,987,897 to Funke which
patent is herein incorporated by reference in its entirety.
Accordingly, the present invention provides a closed-loop drug
delivery system that operates in data communications with an
implanted device to attenuate the impact of shock and other
discomfort resulting from IMD therapy.
[0112] Referring now to FIG. 24, a fully implantable atrial
cardioverter system 312 embodying the present embodiment of the
invention in association with a schematically illustrated human
heart 316 in need of atrial fibrillation monitoring and potential
cardioversion of the atria 516, 518 and an external programmer 322
are shown. The atrial cardioverter system 312 is capable of the
sequential initiation of delivery of a pain alleviating analgesic
at therapeutic levels followed by delivery of atrial cardioversion
electrical energy pulses or shocks of sufficient amplitude and
duration to effectively cardiovert the heart 316 in atrial
fibrillation. The portions of the heart 316 illustrated in FIG. 23
are the right ventricle (RV) 512, the left ventricle 514, the right
atrium (RA) 516, the left atrium 518, the superior vena cava (SVC)
520, the CS 521 including the coronary sinus (CS) ostium or opening
524, the left ventricular free wall 526 and the inferior vena cava
527.
[0113] The system 330 generally includes an enclosure 532, for
hermetically sealing the internal circuit elements, battery,
telemetry antenna, a bipolar RV lead 534, and a RA-CS lead 536. The
enclosure 532 and leads 534 and 536 are arranged to be implanted
beneath the skin of a patient so as to render the atrial
cardioverter system 330 fully implantable.
[0114] The RV lead 534 preferably comprises an endocardial bipolar
lead having electrodes 538 and 540 arranged for establishing
electrical contact with the right ventricle 512 of the heart 316.
The electrodes 538 and 540 permit bipolar sensing of ventricular
depolarizations or R-waves in the right ventricle 512. As
illustrated, the lead 534 is preferably fed through the SVC 520,
the right atrium 516, and then into the right ventricle 512 to
lodge the electrodes 538, 540 in the apex thereof as
illustrated.
[0115] The RA-CS lead 536 generally includes a tip or CS
cardioverting electrode 544 and a proximal ring or RA cardioverting
electrode 546 as shown in U.S. Pat. No. 5,165,403, for example. As
illustrated, the RA-CS lead 536 is flexible and arranged to be
passed down the superior vena cava 520, into the right atrium 516,
into the coronary sinus ostium 524. The CS electrode 544 is
advanced into the coronary sinus channel 521 of the heart near the
left side thereof so that the first or tip electrode 544 is within
the coronary sinus channel 521 either within the coronary sinus 522
adjacent the left ventricle 514 and beneath the left atrium 518 or
most preferably within the great cardiac vein 523 adjacent the left
ventricle 514 and beneath the left atrium 518. The electrodes 544
and 546 are spaced apart such that when the CS electrode 544 is
positioned as described above, the RA electrode 546 is in the right
atrium 516. The CS electrode 544 together with the RA electrode 546
provides bipolar sensing of heart activity in the atria 516 and
518.
[0116] The CS electrode 544 and the RA electrode 546 also provide
for the delivery of defibrillating electrical energy to the atria.
Because the CS electrode 544 is located beneath the left atrium 518
near the left ventricle 514 and the RA electrode 546 is within the
right atrium 516, the cardioverting electrical energy, when applied
between these electrodes will be substantially confined to the
atria 516 and 518 of the heart 316. As a result, the electrical
energy applied to the right ventricle 512 and left ventricle 514
when the atria are cardioverted or defibrillated will be minimized.
This greatly reduces the potential for ventricular fibrillation of
the heart to be induced as a result of the application of
cardioversion electrical energy of the atria of the heart.
[0117] Further electrode systems and cardioversion pathways have
been disclosed and are suitable for use in the practice of the
present invention. One such atrial cardioversion electrode system
is disclosed in the article "Safety and Feasibility of Transvenous
Cardioversion in Atrial Tachycardia", by Blanc et al., published in
Cardiac Pacing, edited by Gomez, Future Pub. Co., 1985, pp
1526-1529. This electrode system employs a single lead with
electrodes located in the right atrium and in the pulmonary artery.
Delivery of atrial cardioversion shocks between an RV electrode and
a subcutaneous electrode is disclosed in U.S. Pat. No. 5,292,338.
Delivery of atrial defibrillation pulses between a coronary sinus
electrode and a subcutaneous electrode is also disclosed in U.S.
Pat. No. 5,314,430.
[0118] A further suitable atrial cardioversion electrode system is
disclosed in U.S. Pat. No. 5,549,642 incorporated herein by
reference in its entirety. The electrode system disclosed therein
includes an RA/SVC electrode (alone or optionally coupled to a
subcutaneous electrode) and a CS electrode. The elongated RA/SVC
electrode appears to provide atrial defibrillation thresholds in
the range of about 1.0 Joule or less across a substantial portion
of the patient population which represents a substantial
improvement over the RA or SVC to CS/great vein electrode system
employed in the above-referenced '403 patent.
[0119] Any of the above atrial cardioversion electrode systems and
associated atrial and/or ventricular leads may be used in the
practice of the present invention. However, even an approximately
1.0 joule cardioversion shock can be painful to a substantial
portion of the population, particularly since atrial fibrillation
episodes repeat frequently, requiring frequent cardioversion.
[0120] Within the enclosure 532, the system 330 includes a
ventricular sense amplifier 550 coupled to the RV lead 534 to
receive electrical signals in the ventricle across the bipolar
electrode pair 538, 540 and an R-wave detector 552 to detect the
R-waves therefrom. The ventricular sense amplifier 550 and the
R-wave detector 552 form a first detecting means that senses
R-waves in the electrogram transmitted to ventricular sense
amplifier by the RV lead 534. The R-wave detector 552 is of the
type well known in the art, which provides an output pulse upon the
occurrence of an R-wave being sensed during a cardiac cycle of the
heart. The delivery of the atrial defibrillation shock or pulse is
timed from the R-wave employing the ventricular timer 564 as
described below.
[0121] The lead and electrode systems in certain embodiments of the
above-referenced '338, '403 and '430 and '642 patents include an RV
defibrillation electrode positioned on an RV lead inserted into the
right ventricle and a pair of ventricular sense electrodes.
Alternatively, in the atrial cardioversion system depicted in FIG.
24, common ventricular pacing leads having bipolar screw-in
ventricular electrodes of this type may be employed as pace/sense
electrodes 538, 540.
[0122] An atrial sense amplifier 554 is coupled to the RA-CS lead
536 to receive electrical signals or P-waves across the right
atrium 516. The atrial sense amplifier 554 forms a second detecting
means for detecting P-wave atrial activity of the heart picked up
by the CS electrode 544 and RA electrode 546 of the RA-CS lead 536.
The P-wave output signal of the atrial sense amplifier 554 is
coupled to an analog to digital converter 560 which converts the
analog signal representative of the atrial activity of the heart to
digital samples for further processing to determine if atrial
fibrillation is present and if the atrial cardioversion shock is
effective in converting the atria to a normal atrial rate.
[0123] The enclosure 532 of the atrial cardioverter system 330
further include a microcomputer 562 that is preferably implemented
in a manner disclosed in the above-referenced '338 patent and
further as described hereinafter with respect to the flow diagram
of FIG. 27. The implementation of the microcomputer 562 in
accordance with this embodiment of the present invention results in
a plurality of functional stages and RAM/ROM 582 for storing
operating algorithms and programmable parameters as well as
accumulated operating data for subsequent telemetry out to the
external programmer 322.
[0124] The circuitry includes the ventricular timer 564 for timing
various intervals that recur in each QRST cycle as well as the
R-wave synchronization time interval, an interval set stage 566 for
selecting time intervals to be timed out in the ventricular timer
564, a delay timer 565 for timing out further delay times set in
interval set stage 566 for the delivery of the pain alleviating
therapy, an optional patient warning device 567 and warning set
register 563, a cardioversion energy level set stage 569, an atrial
fibrillation detector 570, a charge delivery control stage 572, an
analgesic delivery control stage 590, and a computation stage
580.
[0125] The microcomputer 562 is arranged to operate in conjunction
with RAM/ROM memory 582 which may be coupled to the microcomputer
562 by a multi-bit address bus and a bi-directional multiple-bit
data bus. This permits the microcomputer 562 to address desired
memory locations within the memory for executing write or read
operations. During a write operation, the microcomputer 562 stores
data, such as time intervals or operating parameters in the memory
582 at the addresses defined by multiple-bit data bus. During a
read operation, the microcomputer 562 obtains data from the memory
at the storage locations identified by the multiple-bit addresses
provided over the address bus and receives the data from the memory
582 over the bi-directional data bus. Data related to the
detections of atrial fibrillation and the deliveries of the
therapies may be recorded in the RAM memory 582 for interrogation
and telemetry out to the external programmer 322 in a manner well
known in the art.
[0126] Detection of atrial fibrillation may be accomplished in
atrial fibrillation detector 570, in conjunction with computation
stage 580, of microcomputer 562 from the digitized P-waves detected
by atrial sense amplifier 554 using any of the various atrial
fibrillation detection methodologies known to the art. Generally,
atrial fibrillation may be detected in response to an extended
series of high rate (e.g. 240 BPM or greater) atrial
depolarizations or P-waves. If greater specificity for atrial
fibrillation is desired, analysis of regularity of rate waveform
morphology may also be employed.
[0127] Termination of atrial fibrillation may be detected in
response to a decrease in the rate of atrial depolarizations and/or
an increase in their regularity.
[0128] Appropriate detection methodologies are disclosed in the
article "Automatic Tachycardia Recognition", by Arzbaecher et al.,
published in PACE, Vol. 7, May-June 1984, part II, pages 541-547
and in PCT Application No. US92/02829, Publication No. WO 92/18198
by Adams et al., both incorporated herein by reference in their
entireties. In the PCT application, careful synchronization of the
high voltage atrial defibrillation pulse to the ventricles to avoid
induction of ventricular tachycardia or fibrillation is also
discussed.
[0129] In addition, in the context of devices which automatically
detect the occurrence of atrial fibrillation, the patient may
optionally be warned of the detection of atrial fibrillation to be
ready for the delivery of the atrial cardioversion shock through
operation of the warning device 567. In this alternate variation of
the embodiment of the invention, a warning may be provided to the
patient of the diagnosis of atrial fibrillation and the
commencement of delivery of the pain alleviation drug therapy. The
warning may be effected in the manner described in U.S. Pat. No.
5,332,400 incorporated herein by reference in its entirety, but is
preferably effected by energizing a piezoelectric crystal
oscillator that oscillates at an audible frequency intense enough
for the patient to hear it and take precautions, if necessary. The
patient may also optionally be provided with a limited function
programmer 322 for use in communicating a command to the
microcomputer 562 to prevent delivery of the cardioversion shock
until the patient feels the effects of the pain alleviation
therapy, at which time the patient may employ the programmer 322 to
enable delivery of the cardioversion shock, subject to
re-verification of the presence of the atrial fibrillation.
[0130] In this regard, the system 330 also includes the warning set
register 563, the delay timer 565, and the warning device 567 that
are utilized for generating the warning alarm for the patient when
the atrial fibrillation detector 570 determines that the atria are
in fibrillation. The warning device 567 may constitute an audible
alarm sounding piezoelectric crystal oscillator for warning the
patient that atrial fibrillation has been detected and that
cardioverting electrical energy will be applied to the patient's
atria.
[0131] If a programmer 322 is provided, it may also optionally
include a patient activated command signal to initiate the delivery
of the pain alleviating and cardioversion therapies in response to
symptomatic atrial fibrillation. In this context as well, the
ability to use the programmer 322 to delay the delivery of the
cardioversion pulse until the patient has felt the effects of the
pain alleviating therapy is believed valuable.
[0132] After the fibrillation detection warning is delivered to the
patient, or after the patient requests cardioversion therapy by
means of the programmer 322, register 563 is set to indicate that
the patient has received the fibrillation detection warning or has
requested therapy. Immediately thereafter, the delay timer 565
starts timing the warning delay period and initiates communication
to drug delivery system 320 via RF transmitter 592 and antenna 594.
The delay period defines a time interval from when the patient
receives the warning or requests therapy to when the patient should
first expect to receive the cardioverting electrical energy. The
delay time is preferably programmable between one minute and twenty
minutes to afford sufficient time to permit the pain alleviating
therapy to take effect and for the patient to prepare for receiving
the atrial cardioverting electrical energy. A second warning may
optionally be given slightly before delivery of the cardioversion
pulse, if desired. If the patient does not perceive the analgesic
effect of the pain alleviating therapy during the warning delay,
the patient may use the programmer 322 to reset the delay timer 565
to delay delivery of the cardioversion pulse until timer 565
expires. Alternatively, the programmer may instead allow the
patient to delay delivery of the pulse until the patient perceives
the analgesic effect, and allow delivery of the cardioversion
therapy only following a patient initiated enable signal to the
implanted device indicating that therapy may be delivered. As yet
another alternative, the programmer may be employed to simply abort
the therapy during the warning delay, which may be especially
useful if therapy was initially requested by the patient, and the
patient's symptoms have subsided.
[0133] A warning system as described above, including apparatus
specifically dedicated to providing the warning may not be
necessary if the patient can independently feel the analgesic take
effect.
[0134] FIG. 5 illustrates a representative electrotransport
delivery device that may be used in conjunction with the present
invention. Device 320 comprises an upper housing 346, a circuit
board assembly 348, a lower housing 356, anode electrode 357,
cathode electrode 359, anode reservoir 362, cathode reservoir 364
and skin-compatible adhesive 367. Upper housing 346 has lateral
wings 345, which assist in holding device 320 on a patient's skin.
Upper housing 346 is preferably composed of an injection moldable
elastomer (e.g., ethylene vinyl acetate). Printed circuit board
assembly 348 comprises an integrated circuit 349 coupled to
discrete components 352, antenna 354 and battery 350. Circuit board
assembly 348 is attached to housing 346 by posts (not shown in FIG.
25) passing through openings 343a and 343b, the ends of the posts
being heated/melted in order to heat stake the circuit board
assembly 348 to the housing 346. Lower housing 356 is attached to
the upper housing 346 by means of adhesive 367, the upper surface
372 of adhesive 367 being adhered to both lower housing 356 and
upper housing 346 including the bottom surfaces of wings 345.
[0135] Shown (partially) on the underside of circuit board assembly
348 is a button cell battery 350. Other types of batteries may also
be employed to power device 320.
[0136] The device 320 is generally comprised of battery 350,
electronic circuitry 349, 352, 354, electrodes 357, 359, and
hydrogel drug reservoirs 362, 364, all of which are integrated into
a self-contained unit. The outputs (not shown in FIG. 25) of the
circuit board assembly 348 make electrical contact with the
electrodes 359, and 357 through openings 358, 358' in the
depressions 360, 360' formed in lower housing 356, by means of
electrically conductive adhesive strips 366, 366'. Electrodes 357
and 359, in turn, are in direct mechanical and electrical contact
with the top sides 368, 368' of drug reservoirs 362 and 364. The
bottom sides 370', 370 of drug reservoirs 362, 364 contact the
patient's skin through the openings 365', 365 in adhesive 367.
[0137] Device 320 optionally has a feature, which allows the
patient to self-administer a dose of drug by electrotransport. Upon
depression of push button switch 342, the electronic circuitry on
circuit board assembly 348 delivers a predetermined DC current to
the electrode/reservoirs 357, 362 and 359, 364 for a delivery
interval of predetermined length. The push button switch 342 is
conveniently located on the top side of device 320 and is easily
actuated through clothing. A double press of the push button switch
342 within a short time period, e.g., three seconds, is preferably
used to activate the device for delivery of drug, thereby
minimizing the likelihood of inadvertent activation of the device
320. Preferably, the device transmits to the user a visual, tactile
and/or audible confirmation of the onset of the drug delivery
interval by means of LED 344 becoming lit, TENs-like stimulation
via electrodes 357 and 359 and/or an audible sound signal from,
e.g., a "beeper". Drug is delivered through the patient's skin by
electrotransport, e.g., on the arm or body, over the predetermined
delivery interval.
[0138] Anodic electrode 357 is preferably comprised of silver and
cathodic electrode 359 is preferably comprised of silver chloride.
Both reservoirs 362 and 364 are preferably comprised of polymeric
gel materials. Electrodes 357, 359 and reservoirs 362, 364 are
retained by lower housing 356.
[0139] A liquid drug solution or suspension is contained in at
least one of the reservoirs 362 and 364. Drug concentrations in the
range of approximately 1.times.10.sup.-4 M to 1.0 M or more can be
used, with drug concentrations, in the lower portion of the range
being preferred. Typically, the reservoir containing the drug will
also contain the selected countersensitizing agent, in an amount
and concentration effective to provide the flux necessary to reduce
or prevent sensitization of the skin or mucosa.
[0140] FIG. 26 shows a simplified schematic block diagram of drug
delivery system 320 integrated circuit 349. Microprocessor 372
under control of a program contained in RAM/ROM 374 (interconnected
via bi-directional bus 379) receives commands from IMD 312 through
receiver 378 and antenna 354. Upon a command to initiate drug
delivery, the microprocessor 372 initiates drug delivery through
drug delivery control block 380, which initiates iontophoretic drug
delivery through two electrodes (not shown). Timer 377 times the
length of time for drug delivery under control of intervals stored
in RAM/ROM 374 previously programmed via programmer 322 (not shown
in FIG. 26). Upon timer 377 time out, a signal is sent to IMD 312
from transmitter block 376 and antenna 354 using the same telemetry
system described herein above.
[0141] The infusion of various analgesic drugs or agents (or,
simply "analgesics") including opiates (i.e. morphine sulfate,
hydromorphone) and non-opiates (i.e. alpha-2 adrenergic agonists
and neuron specific calcium channel blocking agents) have
demonstrated rapid and effective analgesia following
administration. Dependent upon the specific analgesic administered,
it is also reported that the onset of pain suppression occurs in a
couple of minutes to one hour, and the duration of analgesia may
range from 4-24 hours. The delay in analgesia onset is not
problematic, since rapid cardioversion is not necessary for atrial
fibrillation as opposed to ventricular fibrillation. Time to
analgesia can be utilized by the system 330 to re-verify the
continuation of atrial fibrillation, charge storage capacitors to
deliver the cardioversion shock, and ensure ventricular sensing to
allow cardioversion shock synchronization with the R-wave of the
cardiac cycle.
[0142] A first alternative embodiment of the invention may employ
the drug delivery system 320 for delivery of a cardioversion or
defibrillation threshold reducing agent such as D-sotalol,
Procainamide or Quinidine as an alternative to, or in conjunction
with, delivery of the pain alleviating therapy discussed above. The
reduction of defibrillation threshold in such case would provide
the possibility of a reduced amplitude, less painful cardioversion
pulse. The delivery of a threshold reducing agent thus can be
employed as a pain alleviating therapy or as part of a pain
alleviating therapy. In a more complex embodiment, two separate
drug delivery systems might be employed to allow delivery of the
threshold reducing agent alone or in conjunction with an
analgesic.
[0143] A second alternative embodiment of the invention may employ
the drug delivery system 320 for delivery of diuretic and blood
pressure regulating agents such as Thiazide diuretics
(hydrochlorothiazide, chlorthalidone), usually adequate for mild
heart failure, loop diuretics (furosemide, bumetanide, ethacrynic
acid) reserved for severe volume overload or thiazide-resistant
edema. Additionally, ACE inhibitors have been shown to prevent or
slow the progression of heart failure in patients with symptomatic
and asymptomatic left ventricular dysfunction. Currently, four
agents are used for the treatment of CHF (Congestive Heart
Failure): captopril, enalapril, lisinopril, and quinapril. The
implementation of ID 312 of this embodiment would use the Medtronic
Chronicle.TM. CHF monitoring system such as described in U.S. Pat.
Nos. 5,535,752 and 6,155,267, incorporated herein by reference in
their entireties. The IMD 312, as described in the '267 patent,
would monitor chronic data representative of at least one
physiological parameter. The chronic data is monitored to detect
changes in state of the at least one physiological parameter. Data
associated with detected changes in state is stored within IMD 312.
The detection of changes in state of the at least one physiological
parameter is performed by establishing a baseline (e.g., a center
reference line and upper and lower control limits), and then
determining if the chronic data being monitored satisfies
predetermined, preprogrammed conditions (e.g., conditions based on
the center reference line and the upper and lower control limits)
indicative of a change in state of the at least one physiological
parameter. If data occurs outside of these predetermined limits,
the IMD 312 sends telemetry signals to drug delivery system 320 to
initiate the delivery of the appropriate drug as described herein
above.
[0144] A third alternative embodiment may utilize the drug delivery
system 320 as the patient activator/programmer 322 by incorporating
the features and function as described in U.S. Pat. No. 5,987,356
incorporated herein by reference in its entirety.
[0145] FIG. 27 depicts a flow chart of an operation of the system
shown in FIG. 24 in accordance with the present invention. At step
S100, which continues at all times (except during the delivery of
atrial cardioversion shock), atrial activity of the heart is
sensed. At step 102, the atrial fibrillation detection algorithm is
invoked in atrial fibrillation detector 570. If it is detected,
then in step S104, the IMD 330 transmits a signal to the drug
delivery system 320 via drug delivery control 590, RF transmitter
592 and antenna 594 to initiate delivery at S105 of a programmed
bolus of the pain alleviating drug from drug dispenser 320.
[0146] The charge delivery control 572 may be commanded to start
charge up of the charge storage capacitors, but it is preferred to
delay capacitor charge up until the end of the delay for the
analgesic to take effect and commence capacitor charge up during
the analgesic time course, that is, the time period that the
analgesia effect is expected to continue. At S107 the patch 520
transmits a confirmation of drug delivery completion back to the
IMD 312. Optional warning steps for the patients to show the status
of the detection, drug delivery and cardioverter status may be
included but are not shown in the flow chart of FIG. 7.
[0147] A delay timer 565 is loaded and enabled to time out the
delay for the analgesia effect to take place in steps S106 and
S108. During this delay, the continuation of the atrial
fibrillation episode may be verified in steps S100 and S102 and the
algorithm may optionally be halted at that point. However, since
atrial fibrillation bouts reoccur and since the bolus of pain
alleviating drug is already delivered, reconfirmation at the end of
the delay times is sufficient to determine whether or not to
deliver the cardioversion shock therapy.
[0148] When the delay timer 565 times out in step S108, the delay
timer 565 is reset for the analgesic time course and is started in
step S110. The atrial fibrillation detection is re-verified in step
S112 during the analgesic time course. If it only re-verified after
the analgesic time course times out, then it is necessary to repeat
steps S104-S114 until it is re-verified during an analgesic time
course.
[0149] Then, in step S116, a charge delivery control 572 is
commanded to enable the storage capacitor charge circuit 574 to
charge the high voltage output capacitors up to the cardioversion
energy set in level stage 569. The microcomputer 562 then sets a
synchronization time interval in interval set stage 566 from an
R-wave detected by R-wave detector 552. The ventricular timer 564
then provides a blanking signal to the ventricular and atrial sense
amplifiers 550 and 554. Both operations may be performed in step
S118. Re-verification of continued atrial fibrillation may also be
performed between steps S116 and S118.
[0150] At the expiration of the synchronization time interval in
ventricular timer 564, a command is applied through the charge
delivery control to operate a discharge circuit 576 to discharge
the atrial cardioversion shock via electrodes 544 and 546. After
the atrial cardioversion shock is delivered, the atrial and
ventricular sense amplifiers are again enabled, and the presence or
absence of atrial fibrillation is again tested in step S112. If the
episode is terminated, then the algorithm loops back to step
S100.
[0151] If the episode is not terminated, the steps of FIG. 27 may
be repeated. After a certain number of attempts, the available
therapies may be exhausted. Whether or not the therapies are
successful, the patient will likely have been advised to contact
the attending physician. The event history of the episodes and
delivered therapies are recorded in RAM 582 for subsequent
telemetry out and analysis by the physician in a manner well known
in the art in order to assist in reprogramming therapies.
[0152] Thus, the methodological sequence to provide the pain
alleviating therapy to counter the pain induced by delivery of
atrial cardioversion energy includes the initial detection of
atrial fibrillation, optional warning to the patient, drug infusion
therapy to produce analgesia, time out to allow analgesia to take
effect and the charge storage capacitors to be charged,
reverification of atrial fibrillation, delivery of the
cardioversion energy, and verification that successful atrial
defibrillation has taken place. Should successful atrial
cardioversion not take place, the steps of FIG. 27, would be
reinitiated, except that analgesic drug delivery would not be
repeated unless the analgesic time course time had timed out in
order to prevent drug overdose.
[0153] Depending on the analgesic employed, it may also be
desirable to include a further timer to inhibit delivery of a
further analgesic bolus timed from the previous delivery for a
further time delay to prevent drug overdose. Such a timer may take
into account the cumulative amount of analgesic delivered over a
set time period.
[0154] In addition, it may be desirable to provide the patient with
the option of using programmer 322 to temporarily program the
delivery of an increased quantity of analgesic, if the desired
analgesia effect is not achieved at the permanently programmed
setting. A time and date record of such patient programmed
increases may be kept in the system memory for review by the
physician, and the repetitive use of the programmer may be
inhibited.
[0155] A physiologic monitoring system consisting of an implantable
therapeutic device (e.g., pacemaker or ICD) and an
externally-applied external monitor incorporating: 1) electrodes
for detecting the electrical behavior of the implanted device, 2) a
controller, 3) a power source, and 4) a radio transmitter for
sending information to an external receiving system. The external
monitoring system is constantly monitoring the therapeutic
electrical output of the implantable device and decoding the
electrical behavior according to pre-set algorithms to uniquely
infer what the implanted device is sensing. The radio transmitter
in the external monitor ten sends the decoded data to an external
receiver, which subsequently sends it on to a patient monitoring
system. This invention allows an external monitor to receive
physiologic data without using telemetry simply by monitoring the
easily-detected electrical therapy (e.g., pacing or high voltage
cardioversion/defibrillation delivered by the implanted device.
[0156] Implanted devices like pacemakers and ICDs are constantly
sensing their associated physiological environment. For example,
pacemakers and ICD's are always sensing native electrical activity
in the atria and ventricles, associated data such as activity or
respiration, and derived parameters such as presence or absence of
capture, lead integrity problems, and the like. In order to know
what an implanted device is sensing, radio telemetry, typically in
the 175 KHz range, is widely used to interrogate the memory in the
device. This requires a sophisticated instrument such as a
programmer which is capable of interacting with the implanted
device along with computational capabilities to decode the data in
the telemetry stream. Another method of determining what the device
is sensing is to use a "Patient Alert" type feature, where the
device actually generates an audible tone when certain sensed
conditions are fulfilled (such as a lead problem). This requires
the patient to listen for the tone, decide what the tone means, and
contact a health care worker.
[0157] The following are examples of detection by the electrodes:
1) Detection of arrhythmias, 2) Detection of device malfunction,
such as lead failure or misprogramming, 3) Detection of underlying
physiologic parameters such as hemodynamics and other sensed
parameters.
[0158] The therapeutic electrical output of a therapeutic
implantable device like a pacemaker or an ICD is easily detectable
from the skin surface using ECG electrodes and a standard ECG
preamplifier which are well known in the art. The therapeutic
electrical output from a pacemaker consists of pacing pulses in the
1-5 volt range, which can be detected by skin electrodes as several
millivolt signals. The high voltage defibrillation output from an
implantable defibrillator consists of ramp waveforms in the
hundreds of volts range, which again can be easily detected as
several volt signals on the skin surface. The therapeutic
electrical output of a therapeutic implantable device occurs as a
response to a set of sensed conditions. It is frequently possible
to create a 1-1 mapping between a specific type of therapeutic
electrical output and the sensed conditions that leads to that
output, based on the characteristics of the specific implanted
device and the way it is programmed. As a very simple example,
ventricular pacing in a VVI pacemaker occurs when no intrinsic
ventricular electrical signal is detected by the pacemaker during a
pre-set time interval. Therefore, detecting a regular set of
ventricular pacing stimuli can be taken as evidence that there are
no intrinsic ventricular depolarizations occurring, without having
to measure intrinsic ventricular activity independently.
Implantable therapeutic devices have evolved considerably in
complexity from VVI pacing, and there are now specific therapeutic
algorithms built into most devices which occur in response to a
particular set of sensed conditions. For example, Rate Drop
Response is a particular type of pacing which is easily recognized
by a rapid start of regular pacing, at a relatively high rate (such
as 120 bpm), followed by a gradual fallback in pacing rate over the
next several minutes. This particular algorithm is activated by a
specific set of trigger criteria, including a fall in the intrinsic
ventricular rate through a specific rate window over a specific
time window. Therefore, the specific therapeutic electrical
"signature" generated by the Rated Crop Response algorithm, which
is easily detectable at the skin surface, allows the external
device to determine that a specific type of intrinsic rate change
occurred and to send this information to a patient monitoring
system. Similarly, an ICD may be programmed to deliver a burst of
autodecremental anti-tachycardia pacing (ATP) if a ventricular
arrhythmia of a certain rate is detected. The external monitor can
easily detect the specific pattern of auto-decremental ATP as a
"signature" of a ventricular arrhythmia and, similarly, identify
this arrhythmia and send the detection to an external patient
monitoring system. There are many other examples of unique
therapeutic electrical "signatures" which can be used by the
external monitoring system to generate a specific diagnosis. In
addition to detecting physiologic conditions such as arrhythmias,
this device could also detect potential malfunctions or problems
with the implanted device. For example, ventricular safety pacing
occurs in response to a sensed beat during a pacemaker refractory
period. The safety pace is easily recognizable by its
characteristic coupling interval from the previous pace. Frequent
ventricular safety pacing sometimes indicates a lead insulation
problem. Therefore, the detection of frequent ventricular safety
pacing could initiate a transmission of "possible ventricular lead
problem." If the monitor also detected intrinsic electrical
activity of the heart (e.g. easily detected ORS complexes),
relationships between the therapeutic electrical output of the
device and the detected intrinsic rhythm could add additional
richness to the detection scheme. For example, a dissociation
between ventricular pacing spikes and intrinsic ventricular beats
could indicate loss of capture. Detecting this pattern could
generate the message "possible loss of capture." Another potential
use is to detect underlying physiologic conditions that the
implanted device responds to. For example, future implantable
therapeutic devices may incorporate hemodynamic sensors or ischemia
sensors. It is conceivable that the implanted device may respond
with a specific therapeutic electrical intervention, based on the
data from these sensors. For example, an implantable pacemaker may
be programmed to undergo a certain type of pacing rate fallback if
ischemia is detected. This specific behavior could be decoded as
indicative of sensed ischemia. Referring to FIG. 1, electrodes are
applied to the patient (at left) and connected to the EKG
preamplifier on the external monitoring system. The EKG
preamplifier sends the amplified signal to the Algorithm Decoder.
The Algorithm Decoder typically contains either an Analog to
Digital Converter (ACD) or an analog sense amplifier with
comparator circuitry in order to detect therapeutic electrical
signals. The output from the ADC or comparator is then sequentially
fed to the Algorithm Decodeer circuitry, which compares the
incoming signal with a set of patterns stored in the Algorithm
Storage RAM. The Algorithm Storage RAM contains the specific
therapeutic patterns tat are used to decode the therapeutic
electrical signals into specific patterns. This RAM would be
customized for the specific implantable device and the specific
programming; for example, VT at a certain rate might be programmed
to cause the implantable device to initiate a specific type of ATP.
This information would then be loaded into the Algorithm Storage
RAM. The diagram shows how the radio transmitter could also
function as a receiver to program the Algorithm Storage RAM. The
Algorithm Storage RAM would also contain a PLA that translates each
detected therapeutic electrical pattern into a simple signal that
is then sent to the radio transmitter for transmission to the
receiving system. As in the example above, autodecremental ATP in
response to a detected VT might generate a "10001000" radio signal,
while a defibrillation shock might general a "11111111" radio
signal, which the receiver would decode into the appropriate sensed
rhythm. In the example given above, other conditions such as excess
ventricular safety pacing, dissociation between pacing and
intrinsic beats, or a specific rate fallback behavior indicating
ischemia would also generate unique identifying codes. Also noted
in the diagram is a controller, which would typically consist of a
microprocessor and its associated software or microcode required to
operate the entire device. In addition, the figure demonstrates a
power source (e.g., battery, which could be rechargeable), which
supplies power to all of the electronics in the monitor.
[0159] One embodiment method includes: 1) Using the therapeutic
electrical output of an implanted device to discern sensed
conditions that initiated the therapeutic electrical intervention.
2) Having an external cutaneous device detect the therapeutic
electrical output of an implanted device that allows the external
device to discern the sensed conditions of the implanted device. 3)
Use of an algorithm decoder to translate therapeutic electrical
stimuli into specific sensed conditions based on the specific
characteristics of the implanted device and its associated
programming. 4) Use of a radio link to download specific algorithm
information into the algorithm decoder. 5) Detecting implantable
device malfunction through external decoding of therapeutic
electrical interventions. 6) Detecting underlying physiologic
states (e.g., ischemia) through external decoding of therapeutic
electrical interventions.
[0160] Thus, embodiments of the Implantable Medical Device And
Patch System And Method Of Use are disclosed. One skilled in the
art will appreciate that the present invention can be practiced
with embodiments other than those disclosed. The disclosed
embodiments are presented for purposes of illustration and not
limitation, and the present invention is limited only by the claims
that follow.
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