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Medical Patent Abstract
A storable implantable medical device assembly. An implantable medical
device has a secondary coil operatively coupled to therapeutic componentry.
A container holds the implantable medical device, the container
having a first face. The implantable medical device being arranged
in the container such that the secondary coil is positioned within
a distance of the first face. The distance allows charging of the
implantable medical device without disturbing the container. The
first face of the container having indicia representative of a lateral
location on the first face aligned with the secondary coil of the
implantable medical device. The may then be utilized to place an
external antenna in order to charge the implantable medical device
without disturbing the container.
Medical Patent Claims
A storable implantable medical device assembly. An implantable medical
device has a secondary coil operatively coupled to therapeutic componentry.
A container holds the implantable medical device, the container
having a first face. The implantable medical device being arranged
in the container such that the secondary coil is positioned within
a distance of the first face. The distance allows charging of the
implantable medical device without disturbing the container. The
first face of the container having indicia representative of a lateral
location on the first face aligned with the secondary coil of the
implantable medical device. The may then be utilized to place an
external antenna in order to charge the implantable medical device
without disturbing the container.
Medical Patent Description
FIELD OF THE INVENTION
This invention relates to implantable medical devices and, in particular,
to charging devices, systems and methods for implantable medical
devices.
BACKGROUND OF THE INVENTION
Implantable medical devices for producing a therapeutic result
in a patient are well known. Examples of such implantable medical
devices include implantable drug infusion pumps, implantable neurostimulators,
implantable cardioverters, implantable cardiac pacemakers, implantable
defibrillators and cochlear implants. Of course, it is recognized
that other implantable medical devices are envisioned which utilize
energy delivered or transferred from an external device.
A common element in most of these implantable medical devices is
the need for electrical power in the implanted medical device. The
implanted medical device typically requires electrical power to
perform its therapeutic function whether it be driving an electrical
infusion pump, providing an electrical neurostimulation pulse or
providing an electrical cardiac stimulation pulse. This electrical
power is derived from a power source.
Typically, a power source for an implantable medical device is
a rechargeable power source such as rechargeable batteries and,
in particular, lithium ion batteries. Such batteries can have a
capacity which is exhausted much earlier than the useful life of
the implantable medical device. Electrical power can be transcutaneously
transferred to the implanted medical device to recharge the rechargeable
batteries through the use of inductive coupling. An external power
source temporarily positioned on the surface of the skin of the
patient can recharge the implanted medical device's batteries. In
fact, many systems and methods have been used for transcutaneously
inductively recharging a rechargeable power source used in an implantable
medical device.
Transcutaneous energy transfer through the use of inductive coupling
involves the placement of two coils positioned in close proximity
to each other on opposite sides of the cutaneous boundary. The internal
coil, or secondary coil, is part of or otherwise electrically associated
with the implanted medical device. The external coil, or primary
coil, is associated with the external power source or external charger,
or recharger. The primary coil is driven with an alternating current.
A current is induced in the secondary coil through inductive coupling.
This current can then be used to charge, or recharge, an internal
power source.
BRIEF SUMMARY OF THE INVENTION
Implantable medical devices are commonly shipped from the manufacturer
to a medical facility where implantation of the device is performed.
It is preferable that the implantable medical device not be in a
fully charged state following manufacture and during shipment, storage
and ultimately use. Ultimate battery life can be improved if the
implantable medical device is not fully charged when shipped. Typically,
an implantable medical device can be far from a fully charged and
typically about eighty percent (80%) charged when shipped.
However, implanting an implantable medical device without a full
charge is not desirable. Soon after implantation, it is generally
desirable for the newly implanted medical device to be programmed,
if necessary, utilized while initially implanted in the patient
and monitored by medical personnel soon.
As noted above, inductive charging of the implanted medical device
usually requires placing an external antenna directly on the skin
of the patient at the site of implantation. However, the implantation
site will typically still be recovering from the trauma of implantation
immediately or soon after implantation. The implantation site can
be adversely affected by the external charging unit if charging
of the newly implanted medical device is attempted. Therefore, it
is desirable to put off charging a newly implanted medical device
for as long as possible, or typically one full charge period of
the implanted medical device.
Contrary to conventional shipping techniques designed to ensure
maximum battery life, it is desirable for an implantable medical
device to be fully charged at the time of implantation. This will
allow a maximum amount of time for the implantation site to heal
before transcutaneous charging is attempted.
During shipment and storage, an implantable medical device is usually
contained in a sterile environment in a storage container, such
as a box. This would help to prevent contamination of the implantable
medical device with germs, for example, and would help prevent subsequent
infection of the patient upon implantation. Removal of the implantable
medical device from the sterile environment of the shipping and/or
storage container could subject the implantable medical device to
the risk of contamination.
However, as noted above, charging of implantable medical device
usually requires very close placement of an external antenna to
the secondary coil of the implantable medical device in order to
achieve effective inductive coupling. Such close placement is extremely
difficult with the implantable medical device contained in the sterile
environment of the shipping and/or storage container.
Thus, medical practitioners are often faced with a dilemma of removing
the implantable medical device from the sterile environment of the
container and being able to implant a fully charged medical device,
or ensuring that the implantable medical device remains sterile
but only being able to implant a partially charged medical device
which could limit early use of the medical device or subject the
already traumatized implantation site to the additional trauma of
an external antenna soon after implantation.
In one embodiment, the present invention provides a storable implantable
medical device assembly. An implantable medical device has a secondary
coil operatively coupled to therapeutic componentry. A container
for holding the implantable medical device has a first face. The
implantable medical device is arranged in the container with the
secondary coil positioned within a distance of the first face allowing
charging of the implantable medical device without disturbing the
container. The container has indicia representative of a lateral
location on the first face aligned with the secondary coil of the
implantable medical device. Thus, the indicia may be utilized to
place an external antenna in order to charge the implantable medical
device without disturbing the container.
In another embodiment, the present invention provides a shipping
container for an implantable medical device having a secondary coil
operatively coupled to therapeutic componentry. A container for
holding the implantable medical device has a first face. The container
is configured to hold the implantable medical device in the container
with the secondary coil positioned within a distance of the first
face allowing charging of the implantable medical device without
disturbing the container. The container has indicia representative
of a lateral location on the first face aligned with the secondary
coil of the implantable medical device. Thus, the indicia may be
utilized to place an external antenna in order to charge the implantable
medical device without disturbing the container.
In another embodiment, the present invention provides a method
of supplying an implantable medical device assembly having a secondary
coil operatively coupled to therapeutic componentry. The implantable
medical device is held in a container having a first face. The implantable
medical device is arranged in the container with the secondary coil
positioned within a distance of the first face with the distance
allowing charging of the implantable medical device without disturbing
the container. Indicia on the container is positioned on the container
representative of a lateral location on the first face aligned with
the secondary coil of the implantable medical device. The implantable
medical device is charged without disturbing the container.
In a preferred embodiment, a center of the secondary coil and the
indicia are centered on the first face of the container.
In a preferred embodiment, the indicia is placed on the first face
of the container.
In a preferred embodiment, the indicia is placed on at least one
face of the container adjacent to the first face.
In a preferred embodiment, the indicia is placed on a plurality
of faces of the container adjacent to the first face.
In a preferred embodiment, an interior of the container holding
the implantable medical device is sterile.
In a preferred embodiment, the container is an internal container
contained within an outer container.
In a preferred embodiment, the indicia is positioned inside an
outer layer of the container and with at least a portion of the
outer container covering at least a portion of the indicia being
transparent.
In a preferred embodiment, the indicia is represented by the implantable
medical device and transparency of at least a portion of the first
face of the container.
In another embodiment, the present invention provides a storable
implantable medical device assembly. An implantable medical device
has a secondary coil operatively coupled to therapeutic componentry.
A container for holding the implantable medical device in the container
with the secondary coil positioned within a distance of the first
face allowing charging of the implantable medical device without
disturbing the container. The implantable medical device is located
in a predetermined position within the container. Thus, an external
antenna may be placed with respect to the predetermined position
in order to charge the implantable medical device without disturbing
the container.
In another embodiment, the present invention provides a shipping
container for an implantable medical device having a secondary coil
operatively coupled to therapeutic componentry. A container holds
the implantable medical device with the secondary coil positioned
within a distance of the first face allowing charging of the implantable
medical device without disturbing the container. The implantable
medical device is located in a predetermined position within the
container. Thus, an external antenna may be placed with respect
to the predetermined position in order to charge the implantable
medical device without disturbing the container.
In another embodiment, the present invention provides a method
of supplying an implantable medical device assembly having a secondary
coil operatively coupled to therapeutic componentry. The implantable
medical device is held in a container with the secondary coil positioned
within a distance of the first face allowing charging of the implantable
medical device without disturbing the container. The implantable
medical device is located in a predetermined position within the
container. An external charging antenna is positioned with respect
to the predetermined position. The implantable medical device is
charged without disturbing the container.
In a preferred embodiment, the predetermined position results in
the secondary coil being laterally centered on the first face of
the container.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates an implantable medical device implanted in a
patient;
FIG. 2 is a block diagram of an implantable medical device;
FIG. 3 is a detailed block diagram of an implantable medical device
implanted subcutaneously and an associated external charging device
in accordance with an embodiment of the present invention;
FIG. 4 is a cross-sectional side view of an implantable medical
device implanted subcutaneously and an associated bracket for use
with an external antenna;
FIG. 5 is a cross-section of a container holding implantable medical
device in accordance with an embodiment of the present invention;
FIG. 6 is a top view of the embodiment illustrated in FIG. 5;
FIG. 7 is a cross-section similar to FIG. 5 with external antenna
positioned to charge implantable medical device; and
FIG. 8 illustrates an alternative embodiment with the charging
location centered on the face of the container.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows implantable medical device 16, for example, a drug
pump, implanted in patient 18. The implantable medical device 16
is typically implanted by a surgeon in a sterile surgical procedure
performed under local, regional, or general anesthesia. Before implanting
the medical device 16, a catheter 22 is typically implanted with
the distal end position at a desired therapeutic delivery site 23
and the proximal end tunneled under the skin to the location where
the medical device 16 is to be implanted. Implantable medical device
16 is generally implanted subcutaneously at depths, depending upon
application and device 16, of from 1 centimeter (0.4 inches) to
2.5 centimeters (1 inch) where there is sufficient tissue to support
the implanted system. Once medical device 16 is implanted into the
patient 18, the incision can be sutured closed and medical device
16 can begin operation.
Implantable medical device 16 operates to infuse a therapeutic
substance into patient 18. Implantable medical device 16 can be
used for a wide variety of therapies such as pain, spasticity, cancer,
and many other medical conditions.
The therapeutic substance contained in implantable medical device
16 is a 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 intrathecal antispasmodics,
pain medications, chemotherapeutic agents, and the like. Pharmaceutical
compositions are often configured to function in an implanted environment
with characteristics such as stability at body temperature to retain
therapeutic qualities, concentration to reduce the frequency of
replenishment, 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 may or may not be intended
to have a therapeutic effect and are not easily classified such
as saline solution, fluoroscopy agents, disease diagnostic agents
and the like. Unless otherwise noted in the following paragraphs,
a drug is synonymous with any therapeutic, diagnostic, or other
substance that is delivered by the implantable infusion device.
Implantable medical device 16 can be any of a number of medical
devices such as an implantable therapeutic substance delivery device,
implantable drug pump, cardiac pacemaker, cardioverter or defibrillator,
as examples.
In FIG. 2, implantable medical device 16 has a rechargeable power
source 24, such as a Lithium ion battery, powering electronics 26
and therapy module 28 in a conventional manner. Therapy module 28
is coupled to patient 18 through one or more therapy connections
30, also conventionally. Rechargeable power source 24, electronics
26 and therapy module 28 are contained in hermetically sealed housing
32. Secondary charging coil 34 is attached to the exterior of housing
32. Secondary charging coil 34 is operatively coupled through electronics
26 to rechargeable power source 24. In an alternative embodiment,
secondary charging coil 34 could be contained in housing 32 or could
be contained in a separate housing umbilically connected to electronics
26. Electronics 26 help provide control of the charging rate of
rechargeable power source 24 in a conventional manner. Magnetic
shield 36 is positioned between secondary charging coil 34 and housing
32 in order to protect rechargeable power source 24, electronics
26 and therapy module 28 from electromagnetic energy when secondary
charging coil 34 is utilized to charge rechargeable power source
24.
Rechargeable power source 24 can be any of a variety power sources
including a chemically based battery or a capacitor. In a preferred
embodiment, rechargeable power source is a well known lithium ion
battery.
FIG. 3 illustrates an alternative embodiment of implantable medical
device 16 situated under cutaneous boundary 38. Implantable medical
device 16 is similar to the embodiment illustrated in FIG. 2. However,
charging regulation module 42 is shown separate from electronics
26 controlling therapy module 28. Again, charging regulation and
therapy control is conventional. Implantable medical device 16 also
has internal telemetry coil 44 configured in conventional manner
to communicate through external telemetry coil 46 to an external
programming device (not shown), charging unit 50 or other device
in a conventional manner in order to both program and control implantable
medical device and to externally obtain information from implantable
medical device 16 once implantable medical device has been implanted.
Internal telemetry coil 44, rectangular in shape with dimensions
of 1.85 inches (4.7 centimeters) by 1.89 inches (4.8 centimeters)
constructed from 150 turns of 43 AWG wire, is sized to be larger
than the diameter of secondary charging coil 34. Secondary coil
34 is constructed with 182 turns of 30 AWG wire with an inside diameter
of 0.72 inches (1.83 centimeters) and an outside diameter of 1.43
inches (3.63 centimeters) with a height of 0.075 inches (0.19 centimeters).
Magnetic shield 36 is positioned between secondary charging coil
34 and housing 32 and sized to cover the footprint of secondary
charging coil 34.
Internal telemetry coil 44, having a larger diameter than secondary
coil 34, is not completely covered by magnetic shield 36 allowing
implantable medical device 16 to communicate with the external programming
device with internal telemetry coil 44 in spite of the presence
of magnetic shield 36.
Rechargeable power source 24 can be charged while implantable medical
device 16 is in place in a patient through the use of external charging
device 48. In a preferred embodiment, external charging device 48
consists of charging unit 50 and external antenna 52. Charging unit
50 contains the electronics necessary to drive primary coil 54 with
an oscillating current in order to induce current in secondary coil
34 when primary coil 54 is placed in the proximity of secondary
coil 34. Charging unit 50 is operatively coupled to primary coil
by cable 56. In an alternative embodiment, charging unit 50 and
antenna 52 may be combined into a single unit. Antenna 52 may also
optionally contain external telemetry coil 46 which may be operatively
coupled to charging unit 50 if it is desired to communicate to or
from implantable medical device 16 with external charging device
48. Alternatively, antenna 52 may optionally contain external telemetry
coil 46 which can be operatively coupled to an external programming
device, either individually or together with external charging unit
48.
FIG. 4 is cross-sectional view of implantable medical device 16
implanted in patient 18 approximately one centimeter under cutaneous
boundary 38 creating bulging area 110, an area of the body of patient
18 in which the skin of patient 18 is caused to bulge slightly due
to the implantation of implantable medical device 16. Bulging area
110 is an aid to locating the position of external antenna 52 relative
to secondary coil 34. Bracket 84 can be positioned roughly in the
area where implantable medical device 16 is implanted. Opening 108
in bracket 84 can aid is establishing the location of implantable
medical device. Bracket 84 can be roughly centered over bulging
area 110. After external antenna 52 is coupled to bracket 84, then
primary coil 54 can be generally centered on implantable medical
device 16.
However, secondary coil 34 may not be centered with respect to
implantable medical device 16. This can occur due to a variety of
reasons such as the need for operatively coupling secondary coil
34 to charging regulation module 42. Connections to make this operative
coupling may require physical space on one side of internal antenna
68 which may cause secondary coil 34 not to be centered on implantable
medical device 16. It is also possible that the attachment of internal
antenna 68 to housing 32 can cause secondary coil 34 not to be centered
on implantable medical device 16. Regardless of the cause, if secondary
coil 34 is not centered on implantable medical device 16, then centering
bracket 84 on bulging area 110 may not optimally position primary
coil 54 with respect to secondary coil 34. Any offset in the position
of primary coil 54 and secondary coil 34 may not result in the most
efficient energy transfer from external antenna 52 to implantable
medical device 16.
Inductive coupling between primary coil 54 of external antenna
52 and secondary coil of implantable medical device 16 is accomplished
at a drive, or carrier, frequency, f.sub.carrier, in the range of
from eight (8) to twelve (12) kiloHertz. In a preferred embodiment,
the carrier frequency f.sub.carrier, of external antenna 54 is approximately
nine (9) kiloHertz unloaded.
However, implantable medical device 16 is shipped to the implantation
location and, possibly, stored before implantable medical device
16 can be implanted into patient 16. A preferred embodiment of the
present invention (see FIG. 5) allows implantable medical device
16 to be shipped, and possibly, stored in a partially charged state,
or even a completely discharged state. Container 120 holds implantable
medical device 16 securely utilizing packing material 122 and 124.
Implantable medical device 16 is positioned with secondary coil
34 located distance 126 away from one face 128 of container 120.
Distance 126 is selected such that implantable medical device 16
can be charged using external antenna 52 positioned near or against
face 128 on container 120 without opening the sterile portion of
container 120 or removing implantable medical device 16 from container
120. In a preferred embodiment, distance 126 has the same guidelines
as the distance implantable medical device 16 is implanted below
the skin surface, or from 1 centimeter (0.4 inches) to 2.5 centimeters
(1 inch). Of course, distance 126 could be greater or less than
these dimensions depending upon charging requirements and cushioning
requirements. Generally, charging conditions in container 120 are
not as stringent as charging conditions in an implanted condition
so, in appropriate circumstances, the requirements on distance 126
may be relaxed.
As shown in FIG. 4, secondary coil 34 is not centered on implantable
medical device 16. In FIG. 6 indicia 130 on face 128 of container
120 is indicative of the center of secondary coil 34 (shown by dashed
lines although not visible in FIG. 6). Indicia 130 may be any marking
which would indicate the approximate laterally centered location
of secondary coil 34 on face 128. Indicia 130 is shown as cross
hairs but may also be any other suitable indicia, as for example,
a bulls eye or outline or shadow of antenna 52. Indicia 130 may
be applied to face 128 or may be formed into face 128, painted or
marked on face 128. Indicia 130 may appear separate or may be incorporated
into other markings or designs on face 128. It is also possible
that indicia 128 is not actually on face 128 but could be located
on adjacent sides of container 120, for example, but still giving
an indication of the approximate lateral (to face 128) location
of secondary coil 34. It is only important that indicia 130 be visible
enough to allow a user to properly located external antenna 52 in
order to charge implantable medical device 16.
FIG. 7 illustrates container 120 holding implantable medical device
16 with external antenna 52 containing primary coil 54 properly
positioned with respect to indicia 130 on, or near, face 128 to
be able to properly charge implantable medical device 16 without
disturbing the sterile environment of implantable medical device
16.
In a preferred embodiment, the center of indicia 130, i.e., the
indication of the center of secondary coil 34, be nearly exactly
the center of face 128 of container 120 as shown in FIG. 8. Making
the center of indicia 130 also the center of face 128 eliminates
the possibility of misalignment if a box lid is attached incorrectly
to the rest of container, for example.
Alternatively, with implantable medical device 16 having been located
in a predetermined position within container 120, e.g., with secondary
coil 34 laterally centered on face 128, indicia 130 may be completely
omitted. Knowing that secondary coil 34 is centered on face 128
of container 120, external antenna 52 may simply be positioned laterally
centered on face 128 of container 120, i.e., matching the predetermined
location of implantable medical device 16, and secondary will be
properly positioned for charging. In this alternative, indicia 130
in FIG. 8 would be eliminated.
Although implantable medical device 16 has been illustrated as
being held in a single container 120, it is to be recognized and
understood that other configurations are possible and contemplated
to be within the scope of the present invention. For example, implantable
medical device 16 could be contained in a smaller, sterile container
which in turn is shipped in a larger container providing, for example,
cushioned during shipment. Implantable medical device 16 could still
be charged by opening the larger container without disturbing the
sterile container and charging implantable medical device 16 therein.
In this case, indicia 130 could be represented on either the larger
container, the smaller container or some combination as long as
external antenna can be properly located for charging.
It is also contemplated that other, non-standard forms of indicia
130 could be utilized. For example, sterile container 120, or a
sub-container, could be transparent and indicia 130 could be located
within container 120, or sub-container, and could even be implantable
medical device 16 itself or evidenced on implantable medical device
16.
It is recognized that implantable medical device 16 could be shipped
or stored fully discharged, partially charged or essentially fully
charged. Charging, full or partial, could still be desired, as for
example, topping off the charge of implantable medical device 16
before implantation.
It is also recognized and understood that secondary coil 34 could
be separate from, completely apart from or only semi-attached to
the remainder of implantable medical device 16. In this case, the
positioning and indicia 130 would still apply to the portion of
the apparatus or assembly containing secondary coil 34 or to secondary
coil 34 separately.
Thus, embodiments of the external power source for an implantable
medical device having an adjustable magnetic core and system and
method related thereto 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. |