U.S. patent application number 10/454871 was filed with the patent office on 2003-10-30 for protection apparatus for implantable medical device.
Invention is credited to Chu, Lung-Hsi, Falco, Anthony D., Firth, Robert A., Mandell, Lee J., Nelson, Richard J., Schulman, Joseph H., Vogel, Martin J..
Application Number | 20030204218 10/454871 |
Document ID | / |
Family ID | 29254711 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030204218 |
Kind Code |
A1 |
Vogel, Martin J. ; et
al. |
October 30, 2003 |
Protection apparatus for implantable medical device
Abstract
A method and apparatus for protecting an electronic implantable
medical device prior to it being implanted in a patient's body. The
apparatus affords protection against electronic component damage
due to electrostatic discharge and/or physical damage due to
improper handling. The apparatus is comprised of a circuit board
having conductive surface means for receiving and releasably
grasping the electrodes of the medical device to support the
device's housing proximate to the surface of the circuit board.
First and second conductive paths are formed on the circuit board
extending between the first and second conductive surfaces for
shunting electrostatic discharge currents to prevent such currents
from passing through the device's electronic circuitry. The
respective shunt paths include oppositely oriented diodes,
preferably comprising diodes which emit light (i.e., LEDs) when
current passes therethrough. Additionally, means are provided to
enable functional testing of the medical device.
Inventors: |
Vogel, Martin J.; (Palmdale,
CA) ; Nelson, Richard J.; (Canyon Country, CA)
; Firth, Robert A.; (Frazier Park, CA) ; Falco,
Anthony D.; (San Dimas, CA) ; Schulman, Joseph
H.; (Santa Clarita, CA) ; Chu, Lung-Hsi;
(Newhall, CA) ; Mandell, Lee J.; (West Hills,
CA) |
Correspondence
Address: |
ALFRED E. MANN FOUNDATION FOR
SCIENTIFIC RESEARCH
PO BOX 905
SANTA CLARITA
CA
91380
US
|
Family ID: |
29254711 |
Appl. No.: |
10/454871 |
Filed: |
June 3, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10454871 |
Jun 3, 2003 |
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10420070 |
Apr 18, 2003 |
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10420070 |
Apr 18, 2003 |
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09844621 |
Apr 26, 2001 |
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6551345 |
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Current U.S.
Class: |
607/36 |
Current CPC
Class: |
H05K 3/301 20130101;
H05K 3/325 20130101; A61N 1/372 20130101; A61N 1/14 20130101; A61N
2001/37294 20130101 |
Class at
Publication: |
607/36 |
International
Class: |
A61N 001/37 |
Claims
What is claimed is:
1. An apparatus for physically and electrically protecting an
electronic medical device having first and second electrodes prior
to it being implanted in a patient's body, said apparatus
comprising: first and second connective surfaces for respectively
electrically contacting the first and second electrodes on the
medical device; at least one elastic element for retaining the
first and second electrodes of the medical device in physical and
electrical contact with said first and second connective surfaces;
first and second circuit paths connected between said first and
second connective surfaces, said first and second circuit paths
respectively including oppositely oriented first and second
unidirectional current devices to thereby serve to protect the
medical device from electrostatic discharge prior to implantation;
and wherein said apparatus is configured to be separated from the
medical device before implantation.
2. The apparatus of claim 1 further including: a circuit board;
said connective surfaces being formed on said circuit board for
contacting the electrodes and supporting the medical device; and
wherein said first and second circuit paths are formed on said
circuit board.
3. The apparatus of claim 2 wherein said circuit board is formed of
polyimide.
4. The apparatus of claim 1 wherein said first and second
unidirectional current devices comprise light emitting diodes.
5. The apparatus of claim 1 additionally comprising: a protection
network electrically connected across said first and second
connective surfaces to suppress electrostatic discharge; and
wherein said protection network comprises a pair of unidirectional
current devices serially connected in opposing polarities.
6. The apparatus of claim 1 additionally comprising a photodiode
coupled between said first and second connective surfaces for
emitting radiation capable of being remotely sensed corresponding
to current flow between the first and second electrodes of the
medical device.
7. The apparatus of claim 1 additionally comprising a current loop
coupled between said first and second connective surfaces for
inductively emitting a field capable of being remotely sensed
corresponding to current flow between the first and second
electrodes of the medical device.
8. The apparatus of claim 1 wherein said at least one elastic
element comprises an O-ring.
9. The apparatus of claim 8 wherein said O-ring is formed of
medical grade silicone.
10. The apparatus of claim 1 wherein said at least one elastic
element comprises a single O-ring.
11. The apparatus of claim 10 further comprising: a circuit board,
wherein said circuit board includes a pair of retaining lips for
capturing said single O-ring; and wherein said medical device is
retainable between said O-ring and said circuit board.
12. The apparatus of claim 1 wherein said first and second
connective surfaces are formed to minimize eddy currents.
13. The apparatus of claim 12 wherein said first and second
connective surfaces are comb-shaped.
14. The apparatus of claim 12 wherein said first and second
connective surfaces are formed from serpentine paths.
15. In combination with a medical device configured to be implanted
in a patient's body, the device including a housing containing
electronic circuitry connected to first and second electrodes
extending exteriorly from the housing, an apparatus for use with
the medical device prior to it being implanted, said apparatus
comprising: a dielectric substrate carrying spaced first and second
connective surfaces, each of said connective surfaces being
configured to electrically contact one of the electrodes of the
medical device; at least one elastic element for retaining the
first and second electrodes of the medical device in physical and
electrical contact with said first and second connective surfaces;
a first shunt circuit carried by said substrate electrically
connected between said first and second connective surfaces; a
second shunt circuit carried by said substrate electrically
connected between said first and second connective surfaces;
wherein said first and second shunt circuits respectively include
oppositely directed first and second diodes to thereby serve to
protect the medical device from electrostatic discharge prior to
implantation to thereby serve to protect the medical device from
electrostatic discharge prior to implantation; and wherein said
apparatus is configured to be separated from the medical device
before implantation.
16. The apparatus of claim 15 wherein said dielectric substrate is
a circuit board is formed of polyimide.
17. The apparatus of claim 15 wherein said first and second diodes
each include means for emitting light in response to current
therethrough.
18. The apparatus of claim 17 further including an external monitor
for externally sensing the response of said diodes to an externally
provided activation signal supplied to the electronic
circuitry.
19. The apparatus of claim 18 wherein said externally provided
activation signal is wirelessly supplied to the electronic
circuitry within the medical device.
20. The apparatus of claim 17 additionally comprising: a shipping
container defining a transparent window; and wherein said apparatus
is accommodated in said shipping container with said diodes visible
through said window.
21. The apparatus of claim 15 additionally comprising: a protection
network electrically connected across said first and second
connective surfaces to suppress electrostatic discharge; and
wherein said protection network comprises a pair of unidirectional
current devices serially connected in opposing polarities.
22. The apparatus of claim 15 additionally comprising a photodiode
coupled between said first and second connective surfaces for
emitting radiation capable of being remotely sensed corresponding
to current flow between the first and second electrodes of the
medical device.
23. The apparatus of claim 15 additionally comprising a current
loop coupled between said first and second connective surfaces for
inductively emitting a field capable of being remotely sensed
corresponding to current flow between the first and second
electrodes of the medical device.
24. The apparatus of claim 15 wherein said dielectric substrate
includes a cutout located within said current loop to enable an
externally provided inductive pickup loop to pass through said
current loop and to inductively pick up a signal corresponding to
current flow between the first and second electrodes of the medical
device.
25. The apparatus of claim 15 wherein said at least one elastic
element comprises an O-ring.
26. The apparatus of claim 25 wherein said O-ring is formed of
medical grade silicone.
27. The apparatus of claim 15 wherein said at least one elastic
element comprises a single O-ring.
28. The apparatus of claim 27 wherein said dielectric substrate is
a circuit board that includes a pair of retaining lips for
capturing said single O-ring and wherein the medical device is
retainable between said O-ring and said circuit board.
29. The apparatus of claim 15 wherein said first and second
connective surfaces are formed to minimize eddy currents.
30. The apparatus of claim 29 wherein said first and second
connective surfaces are comb-shaped.
31. The apparatus of claim 29 wherein said first and second
connective surfaces are formed from serpentine paths.
32. A method of protecting an implantable medical device prior to
implantation, the device comprising a housing containing electronic
circuitry connected between first and second electrodes extending
exteriorly from the housing, said method comprising: providing
first and second contacts for electrically contacting the first and
second electrodes; providing at least one elastic element for
retaining the first and second electrodes of the medical device in
physical and electrical contact with said first and second
contacts; providing a first shunt path between said first and
second contacts including a first current device oriented to permit
current therethrough only from said first to said second contact;
and providing a second shunt path between said first and second
contacts including a second current device oriented to permit
current therethrough only from said second to said first contact,
whereby said first and second shunt paths serve to protect the
medical device from electrostatic discharge prior to implantation
to thereby serve to protect the medical device from electrostatic
discharge prior to implantation; and wherein said apparatus is
configured to be separated from the medical device before
implantation.
33. The method of claim 32 additionally comprising the steps of:
providing a substantially rigid substrate for supporting said first
and second contacts, said first shunt path, and said second shunt
path; and configuring said first and second contacts for physically
retaining the housing relative to said substrate.
34. The method of claim 32 additionally comprising the step of
providing an indicator in at least one of said shunt paths to
indicate current therethrough.
35. The method of claim 32 additionally comprising the steps of:
emitting light in said first shunt path to indicate current
therethrough; and emitting light in said second shunt path to
indicate current therethrough.
36. The method of claim 35 further including: providing a shipping
container defining a transparent window; and placing the device in
said shipping container oriented so that light emissions from said
first and second shunt paths are visible through said window.
37. The method of claim 36 further including sterilizing the device
while in said shipping container.
38. The method of claim 36 further including: applying an
activation signal to the device while in said shipping container;
and monitoring the light emissions from said shunt paths in
response to the application of said activation signal.
39. The method of claim 38 wherein said step of applying an
activation signal comprises providing wirelessly communicating
energy to the electronic circuitry in the housing.
40. The method of claim 32 wherein the step of providing first and
second contacts includes forming said contacts to minimize eddy
currents.
41. The method of claim 40 wherein the step of forming said
contacts to minimize eddy currents comprises forming said contacts
in a comb-shaped manner.
42. The method of claim 40 wherein the step of forming said
contacts to minimize eddy currents comprises forming said contacts
in a serpentine manner.
43. In combination with a medical device configured to be implanted
in a patient's body and an external monitor/generator for
functionally testing the medical device, the medical device
including a housing containing electronic circuitry having output
and input capability connected to first and second electrodes
extending exteriorly from the housing, an apparatus for use with
the medical device prior to it being implanted, said apparatus
comprising: a dielectric substrate carrying spaced first and second
connective surfaces, each of said connective surfaces being
configured to electrically contact one of the electrodes of the
medical device; at least one connection element for retaining the
first and second electrodes of the medical device in physical and
electrical contact with said first and second connective surfaces;
a test/protection circuit carried by said substrate electrically
connected between said first and second connective surfaces,
wherein said test/protection circuit is selected from the group of:
(a) a current loop suitable for inductively radiating a variable
magnetic field corresponding to current flowing between the first
and second electrodes of the medical device, wherein said magnetic
field is detectable by the external monitor/generator to thereby
functionally test the output capability of the electronic circuitry
of the medical device; (b) at least one diode to emit light
corresponding to current flowing between the first and second
electrodes of the medical device, wherein the light is detectable
by the external monitor generator to thereby functionally test the
output capability of the electronic circuitry medical device; (c) a
current loop suitable for inductively receiving a variable magnetic
field generated by the external monitor/generator to thereby
functionally test the input capability of the electronic circuitry
of the medical device; and (d) oppositely directed first and second
diodes to thereby serve to protect the medical device from
electrostatic discharge prior to implantation; and wherein said
apparatus is configured to be separated from the medical device
before implantation.
44. The apparatus of claim 43 wherein said at least one connection
element comprises first and second conductive clips mounted on said
dielectric substrate for capturing and retaining the first and
second electrodes of the medical device.
45. The apparatus of claim 43 wherein said at least one connection
element comprises an O-ring.
46. The apparatus of claim 45 wherein said O-ring is formed of
medical grade silicone.
47. The apparatus of claim 43 wherein said at least one elastic
element comprises a single O-ring and said dielectric substrate is
a circuit board that includes a pair of retaining lips for
capturing said single O-ring and wherein the medical device is
retainable between said O-ring and said circuit board.
48. The apparatus of claim 43 wherein said dielectric substrate is
a circuit board is formed of polyimide.
49. The apparatus of claim 43 wherein said diode is a photodiode
suitable for emitting nonvisual light in response to current
therethrough.
50. The apparatus of claim 43 wherein said dielectric substrate has
a substrate cutout surrounded by said current loop to enable an
externally provided inductive pickup loop to pass through said
cutout.
51. The apparatus of claim 50 additionally comprising a
sterilization pouch wherein said sterilization pouch includes a
pouch cutout conforming to said substrate cutout to enable an
externally provided inductive pickup loop to pass through said
substrate and pouch cutouts.
52. The apparatus of claim 43 additionally comprising selection
means for selecting and/or deselecting a desired test/protection
circuit.
53. The apparatus of claim 43 wherein said first and second
connective surfaces are formed to minimize eddy currents.
54. The apparatus of claim 53 wherein said first and second
connective surfaces are comb-shaped.
55. The apparatus of claim 53 wherein said first and second
connective surfaces are formed from serpentine paths.
56. A method of functionally testing an implantable medical device
prior to implantation, the device comprising a housing containing
electronic circuitry connected between first and second electrodes
extending exteriorly from the housing, said method comprising:
providing first and second contacts on a substrate for electrically
contacting the first and second electrodes; providing at least one
connection element for retaining the first and second electrodes of
the medical device in physical and electrical contact with said
first and second contacts; providing a current loop path between
said first and second contacts suitable for emitting a remotely
detectable signal corresponding to current flowing between the
first and second electrodes of the medical device; and wherein said
apparatus is configured to be separated from the medical device
before implantation.
57. The method of claim 56 wherein the step of providing a current
loop path between said first and second contacts is selected from
the group of: (a) providing a current loop between said first and
second contacts suitable for inductively radiating a variable
magnetic field corresponding to current flowing between the first
and second electrodes of the medical device, wherein said magnetic
field is detectable by an external monitor/generator to thereby
functionally test the output capability of the electronic circuitry
of the medical device; (b) providing at least one diode
electrically connected between said first and second contacts to
emit light corresponding to current flowing between the first and
second electrodes of the medical device, wherein the light is
detectable by an external monitor generator to thereby functionally
test the output capability of the electronic circuitry medical
device; and (c) providing a receiving current loop between said
first and second contacts suitable for inductively receiving a
variable magnetic field generated by an external monitor/generator
to thereby functionally test the input capability of the electronic
circuitry of the medical device.
58. The method of claim 56 further including the steps of:
providing a sterilization pouch; placing the device within the
sterilization pouch; and sterilizing the device while in said
sterilization pouch.
59. The method of claim 56 further including the steps of: forming
said current loop path on said substrate having an inner cutout;
providing a sterilization pouch having an outer cutout conforming
to said inner cutout; placing the device within the sterilization
pouch; wherein said conforming inner and outer cutouts enable an
externally provided inductive pickup loop to pass therein and
provide a signal to an externally provided monitor; and sterilizing
the device while in said sterilization pouch.
60. The method of claim 56 further including: applying an
activation signal to the device while in said shipping container;
and monitoring the emissions corresponding to the medical device in
response to the application of said activation signal wherein the
monitoring step is selected from the group of: (a) monitoring
inductively coupled magnetic emissions; (b) monitoring visual light
emissions; (c) monitoring nonvisual light emissions; (d) monitoring
electrostatic emissions; (e) monitoring electromagnetic emissions;
and (f) monitoring capacitive changes.
61. The method of claim 60 wherein said step of applying an
activation signal comprises providing wireless communicating energy
to the electronic circuitry in the housing.
62. The method of claim 60 wherein said step of monitoring the
emissions in response to the application of said activation signal
comprises use of a negative capacity preamp to pick up a signal
from the medical device.
63. The method of claim 56 wherein the step of providing first and
second contacts includes forming said contacts to minimize eddy
currents.
64. The method of claim 63 wherein the step of forming said
contacts to minimize eddy currents comprises forming said contacts
in a comb-shaped manner.
65. The method of claim 63 wherein the step of forming said
contacts to minimize eddy currents comprises forming said contacts
in a serpentine manner.
Description
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/420,070, filed Apr. 17, 2003, which in turn
is a continuation-in-part of U.S. Pat. No. 6,551,345.
FIELD OF THE INVENTION
[0002] This invention relates generally to a method and apparatus
for use with an electronic implantable medical device for
protecting the device from physical and/or electrostatic discharge
damage prior to medically implanting the device in a patient's
body. Moreover, preferred embodiments of the invention afford the
ability to functionally test the device without removing it from
its sterilized shipping container prior to implantation.
BACKGROUND OF THE INVENTION
[0003] Many types of electronic medical devices are known which are
intended for implantation in a patient's body. Although these
devices vary widely in design, they typically include a housing
containing electronic circuitry connected to two or more electrodes
which extend exteriorly from the housing (or one or more electrodes
when the housing is the other electrode). The circuitry can, for
example, include a functional circuit (e.g., a pulse generator), a
power supply circuit (e.g., rechargeable battery), and a
transceiver for wirelessly communicating with an external
controller. Implantable medical devices of this sort are useful in
a variety of applications for stimulating muscle or nerve tissue
and/or monitoring body parameters. See, for example, U.S. Pat. Nos.
6,164,284; 6,185,452; 6,208,894; 6,315,721; and 6,472,991; which
primarily relate to such devices that are battery powered, each of
which is incorporated by reference herein in their entirety. Also
see, for example, U.S. Pat. Nos. 5,193,539; 5,193,540; 5,312,439;
5,324,316; and 5,405,367; which primarily relate to such devices
that are RF powered, each of which is incorporated by reference
herein in their entirety.
[0004] To minimize device failure and maximize device reliability,
it is important that an electronic medical device be properly
handled along the entire chain from manufacturing, through shipping
and storage, and on to the medical procedure for implanting the
device in a patient's body. For example, improper handling can
subject the device to physical damage and/or component damage due
to electrostatic discharge (ESD).
SUMMARY OF THE INVENTION
[0005] The present invention is directed to a method and apparatus
for protecting an electronic implantable medical device prior to it
being implanted in a patient's body. More particularly, a method
and apparatus in accordance with the invention affords protection
to the medical device from just after manufacture to just prior to
implantation. Protection is afforded against electronic component
damage due to electrostatic discharge and/or physical damage due to
improper handling.
[0006] Embodiments of the invention are particularly valuable when
used with small fragile medical devices which often comprise an
electronic circuit housing having an axial dimension of less than
60 mm and a lateral dimension of less than 6 mm. The housing
typically contains electronic circuitry which is electrically
connected to first and second electrodes which extend exteriorly
from the housing. See, for example, U.S. Pat. Nos. 6,164,284;
6,185,452; 6,208,894; 6,315,721; and 6,472,991; which primarily
relate to such devices that are battery powered, each of which is
incorporated by reference herein in their entirety. Also see, for
example, U.S. Pat. Nos. 5,193,539; 5,193,540; 5,312,439; 5,324,316;
and 5,405,367; which primarily relate to such devices that are RF
powered, each of which is incorporated by reference herein in their
entirety.
[0007] A preferred apparatus in accordance with the invention is
comprised of a circuit board having first and second connective
surfaces integral to the circuit board. The connective surfaces are
configured using elastic O-rings to receive and releasably grasp
the electrodes of a medical device housing to support the housing
proximate to the surface of the circuit board. First and second
conductive paths are formed on the circuit board extending between
the first and second connective surfaces for shunting electrostatic
discharge currents to prevent such currents from passing through
the device's electronic circuitry. Preferably, the respective shunt
paths include oppositely oriented diodes, preferably comprising
diodes which emit visual light (i.e., LEDs) when current passes
therethrough.
[0008] In accordance with the invention, a medical device is
preferably mounted in the protective apparatus as a late step in
the device manufacturing process. The protection apparatus/device
combination is then placed into a shipping container. The
combination remains engaged until the device is ready for medical
implantation in a patient's body. The shipping container preferably
includes a transparent window through which the light emitting
diodes are visible.
[0009] In a preferred method in accordance with the invention, the
medical device is sterilized, e.g., using steam or ethylene oxide
(ETO), after being placed in the shipping container.
[0010] A significant feature of the invention allows the medical
device to be functionally tested while in the shipping container.
More particularly, exemplary medical devices include (1)
transceivers which permit wireless communication of commands and
data between an external controller and the device electronic
circuitry and (2) battery charging circuits which extract energy
from an external power source, e.g., via an alternating magnetic
field, for charging a device battery. In accordance with the
invention, a medical device can be functionally tested while still
in the shipping container by transmitting a command or activation
signal to the device. If the device is functioning properly, it
will respond in a particular manner, as by outputting a sequence of
pulses whose characteristics (e.g., frequency, pulse width, etc.)
indicate proper operability. This output pulse sequence drives the
protection apparatus LEDs which can be monitored to detect whether
the device is operating within specifications. Additionally, the
device battery can be charged while still in the shipping container
by an external power source.
[0011] In a still further significant aspect of the present
invention, a cutout is provided in the circuit board to permit a
wire loop from an oscilloscope, pulse generator, or the like, to
pass through and inductively measure/induce the electrical
input/output characteristics of the medical device before
implantation. A sealing pouch preferably has a conforming cutout to
facilitate this test while maintaining the medical device in a
sterilized environment. Alternatively and/or additionally, a
photodiode may be placed on the circuit board to emit nonvisual
radiation that may be sensed by an external detection apparatus to
measure the electrical output characteristics of the medical
device. Finally, the output characteristics of the medical device
may be measured using external capacitively coupled plates and/or
one or more coils.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 schematically depicts the structure of an exemplary
electronic implantable medical device of the type intended for use
with the present invention.
[0013] FIG. 2 is a block diagram generally representing the
electronic circuitry typically employed in the exemplary medical
device of FIG. 1.
[0014] FIG. 3 schematically depicts the exemplary medical device of
FIG. 1 used in combination with a protection apparatus in
accordance with the present invention.
[0015] FIG. 4 is an exploded isometric illustration depicting a
protection apparatus in accordance with the present invention.
[0016] FIG. 5 is an isometric illustration depicting a protection
apparatus in accordance with the present invention for
accommodating a medical device to be protected.
[0017] FIG. 6 is an exploded isometric illustration depicting the
manner of placing the protection apparatus and medical device into
an exemplary shipping container.
[0018] FIG. 7 is an isometric view depicting the protection
apparatus and medical device received in the exemplary shipping
container and oriented so that the light emitting diodes (LEDs) of
the apparatus are visible through a container transparent
window.
[0019] FIG. 8 is a block schematic diagram depicting how the
medical device is tested while in the exemplary shipping
container.
[0020] FIGS. 9A and 9B show isometric views of the mounting of the
medical device on a planar surface having a pair of connective
surfaces for making electrical contact with the electrodes of the
medical device and a pair of O-rings for retaining physical and
electrical contact between the medical device's electrodes and the
circuit board's connective surfaces.
[0021] FIGS. 10A and 10B show isometric views of the mounting of
the medical device on a planar surface having a pair of connective
surfaces for making electrical contact with the electrodes of the
medical device and a single O-ring for retaining physical and
electrical contact between the medical device's electrodes and the
circuit board's connective surfaces.
[0022] FIG. 11 shows an isometric view of the circuit board and
O-ring mounting apparatus of FIGS. 10A and 10B, additionally
including a photodiode for emitting nonvisual radiation that can be
externally monitored to test the functionality of the medical
device, e.g., while it is still within a sterilized container,
e.g., a pouch.
[0023] FIG. 12 shows a simplified schematic diagram of additional
embodiments of the present invention that include the photodiode of
FIG. 11 and/or a current loop path that may be used to emit an
inductively coupled field to a loop connected to an oscilloscope
probe or the like. Alternatively, a pulse generator of the like may
be used to inductively emit a signal into the loop on the circuit
board and thus verify the functionality of the sensor mode
circuitry in the medical device.
[0024] FIGS. 13A and 13B show the presence of the current loop path
described in reference to FIG. 12 with a cutout for allowing the
oscilloscope probe loop to pass through.
[0025] FIGS. 14A, 14B, and 14C respectively show top, side and
bottom views corresponding to the embodiment of FIGS. 13A and 13B
sealed within a sterile pouch having a compliant cutout formed
thereon. Additionally, the use of an optional breakaway section is
shown to remove the LED portion and thus improve the functionality
of the current loop path (by removing interactions with the LED
path).
[0026] FIG. 15 is a block schematic diagram depicting how the
medical device is tested while in the shipping container includes
one or more of the following techniques: sensing of nonvisual
radiation from the photodiode using a photodetector and a
transconductance amplifier, use of an inductively coupled current
loop path (with an optional breakaway section to electrically
detach the LEDs), capacitive sensing of the circuitry, inductive
sensing of the circuitry (without the current loop path and
cutout), and/or one or more switches, e.g., a single pole double
throw (SPDT) switch, to selectively connect the medical device's
electrodes to the LEDs and/or the inductively coupled current
loop.
[0027] FIGS. 16A-16D are alternative embodiments of that previously
shown in FIG. 10A wherein the connective surfaces are formed with
slots to reduce eddy currents and thereby reduce signal loss to the
implantable medical device of the magnetic and/or electromagnetic
signals while it is held by the protection apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Attention is initially directed to FIG. 1 which
schematically depicts an electronic implantable medical device 20.
The device 20 is intended to be representative of a wide range of
known electronic devices designed to be medically implanted in a
patient's body for a variety of applications. For example only,
such devices can be controlled to selectively stimulate muscle and
nerve tissue and/or monitor and report various body parameters. The
exemplary device 20 is depicted as comprising an elongate housing
22 defined by a peripheral wall 24 enclosing an interior volume 26.
The housing 22 can be variously shaped but, for simplicity herein,
it will be assumed to be cylindrical. Typically such implantable
medical devices are small in size, e.g., preferably having an axial
dimension of less than 60 mm and a lateral dimension of less than 6
mm, and relatively fragile structurally. See, for example, U.S.
Pat. Nos. 6,164,284; 6,185,452; 6,208,894; 6,315,721; and
6,472,991; which primarily relate to such devices that-are battery
powered, each of which is incorporated by reference herein in their
entirety. Also see, for example, U.S. Pat. Nos. 5,193,539;
5,193,540; 5,312,439; 5,324,316; and 5,405,367, which primarily
relate to such devices that are RF powered, each of which is
incorporated by reference herein in their entirety. Reasonable care
must be exercised in handling the devices 20 to prevent physical
damage.
[0029] The exemplary device 20 is depicted as containing electronic
circuitry 30 within the interior volume 26. The circuitry 30 is
connected between first and second electrodes 32, 34 which extend
exteriorly from the housing 22. The circuitry 30 typically includes
sensitive electronic components which can be permanently damaged by
high currents which can be caused, for example, by electrostatic
discharge (ESD). Accordingly, as with many other electronic
devices, it is advisable to exercise appropriate care to avoid
discharging high currents through the circuitry 30. The present
invention is primarily directed to a method and apparatus as
depicted in FIGS. 3-15, for protecting the device 20, from damage
while being shipped, stored, and handled between a late
manufacturing stage and up to the time it is implanted in a
patient's body.
[0030] FIG. 2 is a block diagram which generally depicts the
functional components of typical electronic circuitry 30 employed
in an implantable medical device 20. More particularly, the
electronic circuitry 30 is shown as comprising a power supply 38
which may include a rechargeable battery or a capacitor (not
shown). A charging circuit 40 is connected to the power supply 38
for deriving energy from an external power source to charge the
battery. For example only, the charging circuit 40 can respond to
an alternating, e.g., amplitude modulated or frequency modulated,
magnetic field or RF field to supply a charging current to the
power supply 38. The power supply 38 is depicted as supplying an
operating voltage to a transceiver circuitry 42 and a pulse
generator 44. The transceiver circuitry 42 is configured to
communicate with an external controller (not shown) employing a
suitable form of wireless communication via path 43, typically
radio communication. Commands and data can be supplied via path 43
from the external controller to the transceiver circuitry 42 for
controlling or programming the pulse generator 44. The pulse
generator 44 can in turn provide data to the transceiver circuit 42
via path 45 for communication to the external controller.
[0031] It should be understood that FIG. 2 is intended to only very
generally depict the functionality of the electronic circuitry 30
contained in the device 20. The method and apparatus of the
invention to be described herein, is useful in combination with a
wide variety of medical devices 20, e.g., muscle stimulators,
neural stimulators, physiological sensors, pacemakers, etc.
[0032] Attention is now directed to FIG. 3 which depicts an
electronic protection circuit 60 externally connected between the
device electrodes 32, 34. The protection circuit 60 is comprised of
first and second shunt paths 62, 64 which each include a
unidirectional current device, e.g., a diode. Shunt path 62
contains diode 66 oriented from electrode 32 to electrode 34. Shunt
path 64 contains diode 68 which is oppositely oriented, i.e., from
electrode 34 to electrode 32. The shunt paths 62 and 64 operate to
shunt current spikes which can be caused, for example, by
electrostatic discharge around electronic circuitry 30. Thus, the
shunt paths limit excessive currents and voltage rise across the
medical device 20.
[0033] As will be discussed hereinafter, the diodes 66, 68
preferably have an audible or light generator associated therewith
to indicate current therethrough. More specifically, preferred
embodiments of the invention are preferably implemented with light
emitting diodes (LEDs). As will be understood hereinafter, it is
preferable for the respective LEDs to produce light of different
colors so that the direction of current flow between electrodes 32
and 34 can be readily determined by an observer.
[0034] FIG. 4 depicts a preferred implementation of a protection
apparatus 70 in accordance with the present invention tailored for
use with the exemplary cylindrical medical device 20. The apparatus
70 is comprised of a substrate or circuit board 72 having an upper
surface 74 and a lower surface 76.
[0035] First and second spring contact clips 80, 82 are provided
for mounting on the circuit board 72. Each clip is essentially
comprised of a cradle portion 84 including spaced first and second
resilient arms 86, 88. The arms 86, 88, together with end finger
90, define a cradle for releasably retaining an electrode 32, 34 of
device 20. The cradle portion 84 is cantilevered by a shank portion
92 which extends to spaced contact fingers 94, 96 and to a post 98.
The clips 80, 82 can be inexpensively formed by a stamping and
bending operation.
[0036] The circuit board 72 has shunt path 62 formed on upper
surface 74 depicted as including path portion 100 and path portion
102. Path portion 100 is comprised of a longitudinal leg 104 and a
lateral leg 106. Similarly, path portion 102 is comprised of a
longitudinal leg 108 and a lateral leg 110. The clips 80 and 82 are
respectively mounted onto the board 72 with the posts 98 extending
into and electrically contacting through plated apertures 114 and
116 in path legs 104 and 108. The through plated apertures extend
and are electrically connected to a second shunt path 64 formed on
the opposite lower surface 76 of circuit board 72. The shunt path
64 on the surface 76 can be shaped identically to the shunt path 62
on upper surface 74 depicted in FIG. 4. The post 98 of clip 80
extending through the aperture 114 electrically interconnects the
first ends of shunt paths 62 and 64. Similarly, the post 98 of clip
82 extending through aperture 116 electrically interconnects the
second ends of shunt paths 62 and 64. Each shunt path includes a
diode as depicted in FIG. 4. More particularly, note that LED 120
is configured to be surface mounted across legs 106 and 110 of
shunt path 62 on board surface 74. Similarly, LED 122 is intended
for corresponding surface mounting in shunt path 64 on board
surface 76. Alternatively, LEDs 120, 122 may be mounted on the same
surface of the circuit board 72.
[0037] FIG. 5 shows the medical device 20 accommodated in the clips
80 and 82 and with the LEDs 120, 122 being mounted on opposite
surfaces 74 and 76 of circuit board 72. In accordance with the
invention, the device 20 is mounted into the clips 80, 82 in a late
stage of the manufacturing process of device 20. Thereafter, the
mated protection apparatus 70 and medical device 20 are placed in a
shipping container 140, as depicted in FIG. 6. Shipping container
140 can be inexpensively formed of molded plastic, and preferably
includes a cavity 142 shaped and dimensioned to accommodate the
mated protection apparatus 70 and medical device 20. In placing the
mated combination in the cavity, circuit board 72 should be
oriented so that the LEDs 120 and 122 face upwardly. A transparent
sheet 150 covers the cavity 142, to define a window through which
the LEDs 120 and 122 are visible as depicted in FIG. 7.
[0038] It is intended that the protection apparatus 70 and medical
device 20 remain mated together in the shipping container 140 for
the full duration of its shelf life from the manufacturing stage to
just prior to medically implanting the device 20 in a patient's
body. After the mated protection apparatus and medical device 20
are placed into the shipping container 140 and the cavity 142
sealed by transparent sheet 150, the device 20 is preferably
sterilized using a known gas, e.g., ethylene oxide (ETO), or steam
process. For its entire life between manufacturing and
implantation, the protection apparatus 70 will protect the medical
device from electronic component damage attributable to
electrostatic discharge (ESD). Moreover, the apparatus 70 protects
device 20 against physical damage because it is firmly retained by
spring clips 80, 82 mounted on the substantially rigid circuit
board 72.
[0039] In accordance with the present invention, the device 20 is
preferably functionally tested while still in its shipping
container 140. More particularly, as depicted in FIG. 8, an
external power source 160 is able to charge the onboard device
battery via the aforementioned charging circuit 40 by generating an
appropriate field, e.g., alternating magnetic field, in close
proximity to the device 20. The power source 160 can be similar or
identical to the power source normally used to charge the battery
after the device is implanted in a patient's body. Similarly, an
external controller 164 can be used to provide commands and receive
data from the medical device 20 while it is still contained within
the shipping container 140. In a particularly useful procedure, the
controller 164 is able to wirelessly communicate a command or
activation signal to the device 20, e.g., via an RF signal. The
controller 164 can be similar or identical to a controller utilized
by the patient or by a medical practitioner to program the device
20 after implantation in the patient's body. The procedure depicted
in FIG. 8 contemplates that the controller 164 provides an
activation signal to the medical device 20 while it is still in the
shipping container 140. The electronic circuitry of the device 20
is designed to respond to the activation signal to cause pulse
generator 44 to output a known pulse sequence between electrodes 32
and 34. This pulse sequence will cause LEDs 120 and 122 to
illuminate in accordance with a pattern having known
characteristics (e.g., frequency, pulse width, etc.). The activity
of the LEDs 120 and 122 can be monitored by monitor 168 to
determine whether the device 20 is operating properly. For example,
if the device 20 is configured to generate monophasic pulses, one
LED will "brightly" light during generation of each pulse and the
other LED will "dimly" light during recharge of the pulse generator
44. Alternatively, if the device 20 is configured to generate a
biphasic pulse, the intensity of the light emitted from each LED
will be approximately the same.
[0040] Thus, it will be appreciated that the protection apparatus
70 in accordance with the present invention offers both electrical
and physical protection of the device 20 during shipping and
handling, and facilitates the testing of the device prior to it
being medically implanted in a patient's body.
[0041] It is important that medical devices intended for
implantation in a patient's body be biocompatible, i.e., that they
employ materials which do not produce deleterious effects on the
living tissue. This requirement dictates a choice of appropriate
biocompatible materials. In order to avoid compromising
biocompatibility, it is preferable that the contact clips 80, 82
which physically contact the electrodes 32, 34 of the device 20
also be formed of an appropriate biocompatible material, e.g.,
platinum.
[0042] FIGS. 9A and 9B show isometric views of the mounting of the
medical device 20 on a planar surface 200 having a pair of
connective surfaces 202, 204 for making electrical contact with the
electrodes 32, 34 of the medical device 20 and a pair of O-rings
206, 208 (preferably formed from medical grade silicone) for
physically retaining and maintaining electrical contact between the
medical device's electrodes 32, 34 and the circuit board's
connective surfaces 202, 204. In this embodiment, the use of
O-rings 206, 208 functionally replace the previously described use
of clips 80, 82 while further minimizing any potential for damage
to protective gloves worn by medical practitioners when working
with the sterilized and packaged medical device 20. The O-rings
206, 208 are easily rolled onto the ends of the circuit board 72
until they hold the medical device 20 into contact with the
connective surfaces 202, 204. Since the package must be subject to
high temperatures for sterilization purposes, the planar surface
20, e.g., circuit board 72, is formed of polyimide or like material
that can withstand the temperatures associated with sterilization.
The connective surfaces are preferably formed from a biocompatible
material, e.g., platinum or gold plated nickel on copper to provide
a surface that will minimize electrical resistance to the medical
device's electrodes while maintaining biocompatible safety should
the gold or platinum slough off onto the electrodes 32, 34. FIG.
9B, in particular, shows two optional means that may be used to
stabilize the position of the medical device 20 on the connective
surfaces. In this example, connective surface 202' is shown with a
recess, e.g., a concave portion, and connective surface 204' is
shown with a notched portion, each of which are exemplary of
optional techniques for stabilizing the medical device's position.
Clearly, each of these techniques could be used on both ends of the
medical device and the use of different techniques for each
electrode is primarily for illustrative purposes to minimize the
number of provided figures.
[0043] FIGS. 10A and 10B (a variation of that already shown and
described in relation to FIGS. 9A and 9B) show isometric views of
the mounting of the medical device 20 on a planar surface 200
having a pair of connective surfaces 202, 204 for making electrical
contact with the electrodes 32, 34 of the medical device 20 with a
single O-ring 210 for retaining physical and electrical contact
between the medical device's electrodes and the circuit board's
connective surfaces 202, 204. In this embodiment, the circuit board
72 is formed with a pair of opposing retaining lips 212, 214 for
retaining/capturing opposing ends of the O-ring 210. In operation,
the O-ring 210 is typically initially captured by the two retaining
lips 212, 214 and when the medical device 20 is available it is
slipped between the O-ring 210 and the circuit board 72 from the
outside end 216 of the circuit board 72 until its electrodes 32, 34
line up with the connective surfaces 202, 204. Due to the
relatively large size of the connective surfaces 202, 204 to the
electrodes 32, 34, this positioning is easily performed.
Optionally, a stop may be placed on connective surface 204 at
location 218 to block further inner movement of the medical device
20 during insertion into the protection apparatus 70' (see FIG.
10A). Alternatively, the medical device 20 may be placed on the
circuit board 72 and the single O-ring 210 may be stretched and
captured between the two retaining lips 212, 214. Functionally,
e.g., as pertaining to protection and test features, the apparatus
described in relation to FIGS. 9A, 9B, 10A, and 10B performs as
previously described in relation to FIGS. 4 and 5.
[0044] FIGS. 3-8, 10A and 10B, primarily show a protection
apparatus whose output drivers may also be functionally tested
(generally in response to received communication signals) by
visually (or automatically, see monitor 168 in FIG. 8) monitoring
the response of its LEDs 120 and 122 when the medical device 20 is
commanded to generate stimulation pulses. While this is an
effective functional test, its capability to measure actual
performance characteristics, e.g., the milliamp output, of the
medical device 20 is limited. Accordingly, FIGS. 11-15 are
primarily directed to alternative embodiments that additionally
provide the capability to measure, albeit, indirectly the
performance characteristics of the medical device 20 prior to
implantation. The requirement to indirectly measure these
characteristics is dictated by the requirement that the medical
device 20 be maintained within a sterile package before
implantation. The description of various techniques follows,
including (1) the use of a photodiode and associated photodetector
(and transconductance amplifier) to provide a relatively linear
measurement of the output of the medical device, (2), the use of an
inductive current loop with an associated cutout in the circuit
board of the protection apparatus to accept a receiving inductive
pickup loop, e.g., connected to an oscilloscope or the like, to
measure the output of the medical device, (3) the use of an
inductive current loop with an associated cutout in the circuit
board of the protection apparatus to accept a transmitting
inductive current loop driven by an external pulse generator or the
like to provide an input signal, e.g., a simulated neuro-muscular
signal, and thus allow the sense circuitry of the medical device to
be tested, etc. These techniques may be used in various
combinations but what is significant is that they all provide
test/measurement capabilities while the medical device is still
within its sterile delivery package, e.g., a pouch.
[0045] FIG. 11 shows an isometric view of circuit board 72 and
O-ring mounting apparatus of FIGS. 10A and 10B, additionally
including a photodiode 220 (also see FIG. 12) for emitting
nonvisual, e.g., ultraviolet or infrared, radiation (light) that
can be externally monitored to test the functionality of the
medical device 20, e.g., while it is still within a sterilized
delivery package, e.g., a pouch. As shown in FIG. 15, an external
monitor/generator 222 may include a photodetector 224 that is
sensitive to nonvisual radiation 226 emitted by the photodiode 220.
When the photodetector 224 is used in combination with a
transconductance amplifier 228 or the like, the nonvisual radiation
226 which was generated in an essentially linear relationship with
the current passed through the photodiode 224 is converted to an
output signal 230 which essentially linearly corresponds to the
output of the medical device 20 through its electrodes 32, 34. This
output signal 230 may then be measured with an oscilloscope,
automated test equipment, or the like, to confirm that the medical
device 20 is performing within specifications (before
implantation).
[0046] FIGS. 13A and 13B show the presence of a current loop path
232 (also shown in FIG. 12) with a cutout 234 for allowing an
inductive pickup loop 236, e.g., an oscilloscope probe loop, to
pass through and thus inductively measure the current being passed
between electrodes 32, 34 of the medical device 20 (via connective
surfaces 202, 204 and feedthrough/back side connection path 238.
Optionally, a resistor element 240, e.g., on the order of 250 ohms,
is used to simulate body tissue and to avoid/limit interactions
with LEDs 120, 122. Also, see FIG. 15 where photodiode 220 is
essentially replaced by a short circuit and monitor/generator 222
measures/detects the operation of medical device 20 through
inductive pickup loop 236.
[0047] FIGS. 14A, 14B, and 14C respectively show top, side and
bottom views of the embodiment of FIGS. 13A and 13B sealed within a
sterile pouch 242 having a compliant, and thus somewhat smaller
cutout 244 formed thereon. Inductive pickup loop 236 may thus pass
through sterile pouch cutout 244 which in turn is within cutout
234, without breaking the sterile seal of pouch 242.
[0048] Ideally, however, the LEDs 120, 122 are not present when the
current loop path 232 is used. Accordingly, an optional breakaway
portion path 246 may be implemented on the circuit board 72 to
permanently disconnect the LEDs 120, 122 when they are no longer
needed. Thus, in this mode the LEDs 120, 122 would be used as an
initial "go/no go" test and then, as a final before implantation
test, the LEDs 120, 122 would be disconnected via breakaway portion
path 246 before final measurement testing via current loop path
232. Alternatively, a single pole double throw (SPDT) switch 248
could be used to alternatively enable LEDs 120, 122 or current loop
path 232 (see FIG. 15). Such a switch could either be a discrete
device soldered to the circuit board 72 or could be one or more
metallic appendages that extend from the circuit board 72 to form
one or more electrical switches to create the functional equivalent
of switch 248.
[0049] As an additional alternative (see FIG. 15), a pair of
capacitive plates 250, 252 coupled to the monitor/generator 222
could be used to detect operation of the medical device 20.
Alternatively, capacitive plates 250, 252 could be replaced with
one or more coils or a surrounding coil to similarly detect
operation of the medical device 20. In such a case, element 240 may
be replaced with an inductor. Since such alternatives would tend to
block passage of an RF signal into the medical device (needed for
RF powered stimulators), this alternative is best used with a
battery powered stimulator.
[0050] Finally, the previously referenced implantable medical
devices (see, for example, U.S. Pat. Nos. 6,164,284; 6,185,452;
6,208,894; 6,315,721; and 6,472,991) may also be able to operate as
a sensor and thus sense neuro-muscular signals via its electrodes
32, 34. To test functionality of such devices operating as a
sensor, one must provide an electrical signal to electrodes 32, 34
and communicate (typically via an RF signal) with the medical
device 20 to confirm proper detection of the input voltage signal.
In this mode (see FIG. 15), the monitor/generator 222 operates as a
pulse generator and puts out various programmable frequency and
amplitude signals through pickup loop 236 which is inductively
provided through current loop path 232 to electrodes 32, 34 of the
medical device 20. In response, medical device 20 communicates with
controller 164 to determine functionality of the medical device 20.
Optionally, controller 164 may communicate with monitor/generator
222 (shown as a dashed path) to coordinate comparisons of the
expected and actual received signals.
[0051] In the previously shown examples, e.g., FIGS. 1A, 11, and
13, the connective surfaces are shown as solid plated surfaces.
This configuration can result in heating of the connective surfaces
and some loss of the magnetic/electromagnetic signals being sent to
the implantable device 20 from power source 160 and/or controller
164 (see FIGS. 8 and 15), e.g., resulting from eddy currents on the
connective surfaces, when the implantable medical device 20 is held
by the protection apparatus 70 (and in particular 70', 70" or
70'"). Accordingly, FIGS. 16A-16D are alternative embodiments of
that previously shown, e.g., in FIG. 1A, wherein the connective
surfaces are formed with slots or serpentine paths to reduce eddy
currents and thereby reduce signal loss to the implantable medical
device 20 of the magnetic and/or electromagnetic signals while it
is held by the protection apparatus 70. In particular, FIGS. 16A
and 16B show connective surfaces 202' and 204' formed as
comb-shaped connective surfaces having a plurality of slots 260 to
minimize eddy currents. Alternatively, FIGS. 16C and 16D show
connective surfaces 202" and 204" formed from serpentine paths that
similarly form slots 260 in the surface to minimize eddy
currents.
[0052] Although a specific embodiment of the invention has been
described, it is recognized that variations and modifications will
readily occur to those skilled in the art coming within the
intended spirit and scope of the present invention as defined by
the appended claims. For example, while the aforedescribed
apparatus 70 shown in FIG. 4 is particularly suited for use with
the exemplary small, cylindrical device of FIG. 1, the present
invention includes the use of the aforedescribed protection
circuitry with other differently shaped medical devices having two
or more electrodes. In such cases, the mounting means would be
adjusted accordingly to accommodate the particular device. In
particular, the O-ring embodiments of FIGS. 9A, 9B, 10A, 10B, 11,
13A, 13B, 14A, 14B and 14C are particularly adapt at retaining
non-cylindrical, e.g., square, triangular, hexagonal, etc., shaped
medical devices in the protection apparatus of the present
invention. Additionally, it should be noted that while current loop
path 232 is shown graphically as a single loop (see, e.g., FIG.
13A), this is primarily to simplify the graphical depiction of this
path and embodiments are intended to also include multi-looped
paths. Advantageously, multi-looped embodiments will facilitate
transmission and/or reception of inductively radiated signals.
Finally, it is noted that a negative capacity preamp, i.e., an
amplifier having a capacitor for negative feedback, could be used
within the monitor/generator to pick up an electrostatic signal
from the medical device and/or the medical device/protection
apparatus combination and thus detect/monitor the operation of the
medical device.
* * * * *