U.S. patent application number 11/735826 was filed with the patent office on 2007-08-09 for overmold for a modular implantable medical device.
This patent application is currently assigned to Medtronic, Inc.. Invention is credited to Darren A. Janzig, Paulette C. Olson, Ruchika Singhal, Robert M. Skime, Carl D. Wahlstrand.
Application Number | 20070185539 11/735826 |
Document ID | / |
Family ID | 32512690 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070185539 |
Kind Code |
A1 |
Singhal; Ruchika ; et
al. |
August 9, 2007 |
OVERMOLD FOR A MODULAR IMPLANTABLE MEDICAL DEVICE
Abstract
A modular implantable medical device permits implantable medical
devices to have a smaller profile in order to better fit into
locations within the human body. A modular implantable medical
device separates various functional components of the implantable
medical device into a set of interconnected modules. This
distributed architecture of a modular implantable medical device
may permit the device footprint to be distributed over a larger
area while making the profile smaller, and may permit the overall
shape of the implantable medical device to better match the body
location into which it is to be implanted. An overmold integrates
the modules of a modular implantable medical device into a single
structure. In some embodiments the overmold is flexible and
provides a biocompatible interface from the component modules and
the patient, while restraining potentially harmful intermodule
motion.
Inventors: |
Singhal; Ruchika;
(Minneapolis, MN) ; Janzig; Darren A.;
(Centerville, MN) ; Wahlstrand; Carl D.; (Lino
Lakes, MN) ; Skime; Robert M.; (Coon Rapids, MN)
; Olson; Paulette C.; (Eagan, MN) |
Correspondence
Address: |
SHUMAKER & SIEFFERT, P. A.
1625 RADIO DRIVE
SUITE 300
WOODBURY
MN
55125
US
|
Assignee: |
Medtronic, Inc.
Minneapolis
MN
|
Family ID: |
32512690 |
Appl. No.: |
11/735826 |
Filed: |
April 16, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10730873 |
Dec 9, 2003 |
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11735826 |
Apr 16, 2007 |
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60431854 |
Dec 9, 2002 |
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60471262 |
May 16, 2003 |
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60503945 |
Sep 20, 2003 |
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60503946 |
Sep 20, 2003 |
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60507857 |
Oct 1, 2003 |
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Current U.S.
Class: |
607/36 |
Current CPC
Class: |
A61N 1/37514 20170801;
A61N 1/3758 20130101; A61N 1/37518 20170801; A61N 1/3605 20130101;
A61N 1/3754 20130101 |
Class at
Publication: |
607/036 |
International
Class: |
A61N 1/375 20060101
A61N001/375 |
Claims
1. An implantable medical device comprising: a control module
comprising a housing; and an overmold that at least partially
encapsulates the housing, wherein the overmold comprises a first
component comprising an elastomeric material and a second component
comprising a non-elastomeric material.
2. The implantable medical device of claim 1, wherein the first
component at least partially encapsulates the housing and the
second component is positioned to at least partially surround the
housing.
3. The implantable medical device of claim 1, wherein the overmold
is flexible.
4. The implantable medical device of claim 1, wherein the
elastomeric material comprises silicone.
5. The implantable medical device of claim 1, wherein the
non-elastomeric material comprises at least one of a polysulfone or
a polyurethane.
6. The implantable medical device of claim 1, further comprising a
lead connection module within the overmold for connecting an
external lead to electronics within the control module.
7. The implantable medical device of claim 1, wherein the overmold
comprises a first overmold, the implantable medical device further
comprising a second overmold that at least partially encapsulates a
lead connection module, wherein the second overmold is tethered to
the first overmold.
8. The implantable medical device of claim 1, wherein an edge of
the overmold is tapered to provide a sloped transition between the
implantable medical device and a surface of the patient, and an
angle between the edge of the overmold and the surface of the
patient is greater than approximately 90 degrees.
9. The implantable medical device of claim 8, wherein the angle is
within a range from approximately 120 to approximately 150
degrees.
10. The implantable medical device of claim 1, further comprising a
sloped interface element, separate from the overmold, which
surrounds the overmold and provides a sloped transition between the
implantable medical device and a surface of the patient, wherein an
angle between an edge of the sloped interface element and the
surface of the patient is greater than 90 degrees.
11. The implantable medical device of claim 1, wherein at least one
of the first or second components of the overmold is concave such
that the overmold conforms substantially to a cranium of a
patient.
12. The implantable medical device of claim 1, wherein the overmold
includes an external lead management structure for external leads
being routed away from the implantable medical device.
13. The implantable medical device of claim 1, wherein the overmold
includes a removal assist structure for assisting in removal of the
implantable medical device.
14. The implantable medical device of claim 1, wherein the overmold
includes a through-hole to receive an attachment mechanism for
attaching the implantable medical device to a patient.
15. The implantable medical device of claim 1, wherein the
implantable medical device is adapted to be implanted on a cranium
of a patient, and the overmold includes a cap to cover a hole
through the cranium.
16. The implantable medical device of claim 1, wherein the control
module provides neurostimulation therapy to a patient.
17. The implantable medical device of claim 1, wherein the control
module comprises a first module, the implantable medical device
further comprising a second module interconnected to the control
module.
18. The implantable medical device of claim 17, further comprising
a motion reduction element to reduce motion between the control
module and the second module.
19. An implantable medical device comprising: a control module
comprising a housing; and an overmold that at least partially
encapsulates the housing, wherein the overmold comprises a first
component that at least partially encapsulates the housing and a
second component that is positioned to at least partially surround
the housing and at least partially contact the housing.
20. The implantable medical device of claim 19, wherein the first
component comprises an elastomeric material, and the second
component comprises a non-elastomeric material.
21. The implantable medical device of claim 19, wherein the control
module comprises a first module, the implantable medical device
further comprising a second module interconnected to the control
module.
22. The implantable medical device of claim 19, further comprising
a sloped interface element, separate from the overmold, which
surrounds the overmold and provides a sloped transition between the
implantable medical device and a surface of the patient, wherein an
angle between an edge of the sloped interface element and the
surface of the patient is greater than approximately 90
degrees.
23. An implantable medical device comprising: a control module
comprising a housing; and an overmold that at least partially
encapsulates the housing; and a sloped interface element separate
from the overmold that at least partially surrounds the overmold
and is tapered to provide a sloped transition between the overmold
and a surface of the patient, wherein an angle between an edge of
the sloped interface element and the surface of the patient is
greater than approximately 90 degrees.
24. The implantable medical device of claim 23, wherein the
overmold is at least partially flexible.
25. The implantable medical device of claim 23, wherein the angle
is within a range from approximately 120 to approximately 150
degrees.
26. The implantable medical device of claim 23, wherein the
overmold comprises a first component that at least partially
encapsulates the housing and a second component that is positioned
to surround the housings, wherein the first component comprises an
elastomeric material, and the second component comprises a
non-elastomeric material.
27. An implantable medical device adapted to be implanted on a
cranium of a patient, the implantable medical device comprising: a
control module comprising a housing; and an overmold that at least
partially encapsulates the housing and comprises a cap to cover a
hole through the cranium.
28. The implantable medical device of claim 27, wherein the
overmold comprises a first component that at least partially
encapsulates the housing and a second component that is positioned
to surround the housing.
29. The implantable medical device of claim 27, wherein overmold
comprises a first component comprising an elastomeric material and
a second component comprising a non-elastomeric material.
Description
RELATED APPLICATIONS
[0001] This is a continuation of U.S. patent application Ser. No.
10/730,873, filed on Dec. 9, 2003, entitled "OVERMOLD FOR A MODULAR
IMPLANTABLE MEDICAL DEVICE" to Singhal et al., the entire content
of which is incorporated herein by reference. U.S. patent
application Ser. No. 10/730,873 in turn claims the benefit of:
1. U.S. Provisional Application entitled "CRANIAL NEUROSTIMULATOR
AND METHOD," Ser. No. 60/431,854, (Attorney Docket No. P-10891.00),
filed on Dec. 9, 2002;
2. U.S. Provisional Application entitled "IMPLANTABLE CRANIAL
MEDICAL DEVICES AND METHODS," Ser. No. 60/471,262, (Attorney Docket
No. P-11462.00), filed on May 16, 2003;
3. U.S. Provisional Application entitled "IMPLANTABLE CRANIAL
MEDICAL DEVICES AND METHODS," Ser. No. 60/503,945, (Attorney Docket
No. P-11696.00), filed on Sep. 20, 2003;
4. U.S. Provisional Application entitled "IMPLANTABLE CRANIAL
MEDICAL DEVICES AND METHODS," Ser. No. 60/503,946, (Attorney Docket
No. P-11697.00), filed on Sep. 20, 2003; and
[0002] 5. U.S. Provisional Application entitled "THIN NEURO
STIMULATION SYSTEM, DEVICE AND METHOD," Ser. No. 60/507,857,
(Attorney Docket No. P-20211.00), filed on Oct. 1, 2003. The entire
content of each of these U.S. Provisional Applications is
incorporated herein by reference.
[0003] The following co-pending and commonly assigned U.S. patent
applications are also incorporated herein by reference in their
entireties:
1. U.S. patent application Ser. No. 10/731,869, entitled "MODULAR
IMPLANTABLE MEDICAL DEVICE," by Wahlstrand et al., filed Dec. 9,
2003;
2. U.S. patent application Ser. No. 10/731,868, entitled
"IMPLANTATION OF LOW-PROFILE IMPLANTABLE MEDICAL DEVICE," by
Singhal et al., filed Dec. 9, 2003;
3. U.S. patent application Ser. No. 10/731,881, entitled "REDUCING
Relative Intermodule Motion in a Modular Implantable MEDICAL
DEVICE," by Wahlstrand et al., filed Dec. 9, 2003;
4. U.S. patent application Ser. No. 10/731,699, entitled "COUPLING
MODULE OF A MODULAR IMPLANTABLE MEDICAL DEVICE," by Janzig et al.,
filed Dec. 9, 2003;
5. U.S. patent application Ser. No. 10/730,877, entitled
"LOW--PROFILE IMPLANTABLE MEDICAL DEVICE," by Janzig et al., filed
Dec. 9, 2003;
6. U.S. patent application Ser. No. 10/731,867, entitled "CONCAVITY
OF AN IMPLANTABLE MEDICAL DEVICE," by Wahlstrand et al., filed Dec.
9, 2003;
7. U.S. patent application Ser. No. 10/730,878, entitled "LEAD
CONNECTION MODULE OF A MODULAR IMPLANTABLE MEDICAL DEVICE," by
Singhal et al., filed Dec. 9, 2003; and
8. U.S. patent application Ser. No. 10/731,638, entitled "MODULAR
IMPLANTABLE MEDICAL DEVICE," by Wahlstrand et al., filed Dec. 9,
2003.
TECHNICAL FIELD
[0004] The invention relates to medical devices, and more
particularly, to implantable medical devices that deliver therapy
to and/or monitor a patient.
BACKGROUND
[0005] Depending on the application for which they are implanted in
a patient, implantable medical devices (IMDs) may include a variety
of electrical and/or mechanical components. Typically, an IMD
includes a rigid housing that houses all of its components, which
are generally fragile, to protect the components from forces to
which they would otherwise be exposed when implanted within the
human body. In order to avoid potentially harmful interactions
between the components and bodily fluids, e.g., corrosion, IMD
housings are typically hermetically sealed. Many IMD housings are
fabricated from Titanium because of its desirable rigidity and
biocompatibility.
[0006] The size and shape of an IMD housing is dependant on the
sizes and shapes of the components of the IMD. Large components
common to most IMDs include a battery, a telemetry coil, and a
hybrid circuit that includes digital circuits, e.g., integrated
circuit chips and/or a microprocessor, and analog circuit
components. Attempts have been made to reduce the size of the IMD
housing by reducing the size of these components, changing the
shape of these components, and organizing these components within
the IMD housing to avoid empty space within the housing. Despite
these efforts to reduce the size of IMD housings, the size, shape
and rigidity of IMD housings still greatly limits the locations
within the human body where an IMD can be practically
implanted.
[0007] Due to these limitations, an IMD is typically implanted
within the abdomen, upper pectoral region, or subclavicular region
of a patient. Leads or catheters must be used in order to deliver
therapy or monitor a physiological parameter at a location of the
body other than where the IMD is implanted. Implantation and
positioning of leads and catheters can be difficult and
time-consuming from the perspective of a surgeon, particularly
where the IMD is located a significant distance from the treatment
or monitoring site. Moreover, the increased surgical time,
increased surgical trauma, and increased amount of implanted
material associated with the use of leads and catheters can
increase the risk to the patient of complications associated with
the implantation of an IMD.
[0008] For example, IMDs that are used to treat or monitor the
brain, e.g., to deliver deep brain stimulation (DBS) therapy, are
implanted some distance away from the brain, e.g., within the
subclavicular region of patients. The long leads that connect the
implantable medical device to electrodes implanted within the brain
require tunneling under the scalp and the skin of the neck, thereby
requiring increased surgery and a prolonged amount of time under
general anesthesia during the implant procedure. In some cases,
tunneling the leads under the scalp and skin of the neck requires
an additional surgical procedure under general anesthesia. The
lengthy tract along the leads is more susceptible to infection, and
the leads can erode the overlying scalp, forcing removal so that
the scalp can heal. Further, the long leads running under the scalp
and through the neck are more susceptible to fracture due to
torsional and other forces caused by normal head and neck
movements.
SUMMARY
[0009] In general, the invention relates to an overmold for a
modular implantable medical device. Various functional components
of a modular implantable medical device are separated into
interconnected modules. This distributed architecture for the
implantable medical device may permit the device footprint to be
distributed over a larger area while making a profile of the device
smaller. In addition, the multiple modules and the flexible
interconnections between the modules may permit the overall shape
of the implantable medical device to be formed to better match the
body location into which it is to be implanted.
[0010] An overmold integrates the modules of a modular implantable
medical device into a structure. In exemplary embodiments, the
overmold is flexible, e.g., allows intermodule motion, and provides
a biocompatible interface between the component modules and the
patient. In some embodiments, the edge of the overmold forms a
sloped interface that provides a slope from the top of the
implantable medical device to a body surface, such as the cranium.
The sloped interface may be defined by an angle, which may be
greater than 90 degrees, and is preferably approximately equal to
135 degrees. The overmold may be preformed to a concave shape to
better conform to a body surface, such as the cranium. The overmold
may incorporate one or more motion reduction elements to restrict
intermodule motion to certain directions or ranges in order to
protect the structural integrity of interconnections between the
modules.
[0011] The overmold can include elastomeric materials, such as
silicone, and/or non-elastomeric materials such as polysulfone and
polyurethane. Further, the overmold may include one or more
components. For example, a first component may comprise an
elastomeric material and at least partially encapsulates each of
the modules, while a second component comprises a non-elastomeric
material that surrounds, e.g., is located proximate to sides of one
or more modules. The first component may provide biocompatibility,
flexibility and a desired form factor for the modular implantable
medical device. The second component may, for example, provide
structural integrity for the modular implantable medical device,
e.g., restrict intermodule motion, hold the one or more modules
within the first component, and provide through-holes for secure
attachment of the modular implantable medical device to a surface
within the patient, such as the cranium.
[0012] In one embodiment, the invention is directed to an
implantable medical device that includes a plurality of
interconnected modules. Each of the modules comprises a housing.
The implantable medical device further comprises an overmold that
at least partially encapsulates each of the housings.
[0013] In another embodiment, the invention is directed to an
implantable medical device comprising a housing and an overmold
that at least partially encapsulates the housing. The overmold
comprises a first component that at least partially encapsulates
the housing and a second component that is located adjacent to side
surfaces of the housing. The first component comprises an
elastomeric material, and the second component comprises a
non-elastomeric material.
[0014] In another embodiment, the invention is directed to an
implantable medical device. The implantable medical device includes
a plurality of interconnected modules, and each of the modules
comprises a housing. The implantable medical device further
comprises means for integrating the modules into a single structure
that at least partially encapsulates each of the housings.
[0015] In another embodiment, the invention is directed to a method
for fabricating a modular implantable medical device having an
overmold. The method includes fabrication of an overmold,
fabrication of a plurality of modules and interconnection members,
fabrication of a motion reduction element, and combination of the
overmold, motion reduction element and plurality of modules to
construct the modular implantable medical device.
[0016] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other embodiments of the invention will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIGS. 1A and 1B are conceptual diagrams illustrating a
modular implantable medical device implanted in a patient according
to an example embodiment of the present invention.
[0018] FIG. 2 is a schematic diagram illustrating a modular
implantable medical device according to another embodiment of the
present invention.
[0019] FIGS. 3A-3F are schematic diagrams illustrating various
arrangements of modules within a modular implantable medical device
according to various embodiments of the present invention.
[0020] FIGS. 4A-4C are schematic diagrams illustrating the
construction of an overmold of a modular implantable medical device
according to the present invention.
[0021] FIGS. 5A-5B are schematic diagrams illustrating the
interaction of components of an overmold according to the present
invention.
[0022] FIG. 6 is a schematic diagram illustrating the degrees of
motion present in a modular implantable medical device.
[0023] FIG. 7 is a schematic diagram illustrating motion reduction
within various degrees of motion within a modular implantable
medical device.
[0024] FIG. 8A-C are schematic diagrams illustrating example
embodiments of modular implantable medical devices having lead
management features.
[0025] FIG. 9 is a schematic diagram illustrating an example
embodiment of a modular implantable medical device having an access
loop for removal.
[0026] FIG. 10 is a schematic diagram illustrating a perspective
view of an example embodiment of a modular implantable medical
device having a triangular module arrangement.
[0027] FIG. 11 is a schematic diagram illustrating a perspective
view of an example embodiment of a modular implantable medical
device having an inline module arrangement.
[0028] FIG. 12 is a schematic diagram illustrating side view of a
modular implantable medical device having an inline module
arrangement.
[0029] FIG. 13 is a schematic diagram illustrating an exploded view
of a modular implantable medical device having a triangular module
arrangement.
[0030] FIG. 14 is a flowchart illustrating a method of constructing
an implantable medical device with an overmold according to the
present invention.
DETAILED DESCRIPTION
[0031] FIGS. 1A and 1B are conceptual diagrams illustrating a
modular implantable medical device 101 implanted within a patient
100. By constructing modular implantable medical device 101 as a
set of distributed modules connected together as described herein,
modular implantable medical device 101 may be implanted at
locations for which implantation of conventional implantable
medical devices has been deemed undesirable, thus permitting the
implantable medical device 101 to be implanted near a monitoring
and/or therapy delivery location. In the example illustrated within
FIGS. 1A-1B, modular implantable medical device 101 is implanted
under the scalp of the patient 100 in order to locate the device
101 close to the location to which therapy is to be delivered via
leads 102, i.e., the brain of patient 100. The low profile and the
shape of modular implantable medical device 101 as described herein
can reduce the risk of infection and skin erosion associated with
implantation of matter beneath the scalp, and may provide a
cosmetically acceptable profile when implanted beneath the
scalp.
[0032] Modular implantable medical device 101 may deliver
stimulation to the brain of patient 100 to, for example, provide
deep brain stimulation (DBS) therapy, or to stimulate the cortex of
the brain. Cortical stimulation may involve stimulation of the
motor cortex. Modular implantable medical device 101 may be used to
treat any nervous system disorder including, but not limited to,
epilepsy, pain, psychological disorders including mood and anxiety
disorders, movement disorders (MVD), such as, but not limited to,
essential tremor, Parkinson's disease, and neurodegenerative
disorders.
[0033] However, modular implantable medical device 101 is not
limited to delivery of stimulation to the brain of patient 100, and
may be employed with leads 102 deployed anywhere in the head or
neck including, for example, leads deployed on or near the surface
of the skull, leads deployed beneath the skull such as near or on
the dura mater, leads placed adjacent cranial or other nerves in
the neck or head, or leads placed directly on the surface of the
brain. Moreover, modular implantable medical device 101 is not
limited to implantation under the scalp of patient 100. Indeed,
modular implantable medical device 101 may be implanted anywhere
within patient 100. For example, modular implantable medical device
101 can be implanted within the neck of patient 100, and deliver
stimulation to the vagus nerve or the cervical region of the spinal
cord.
[0034] Modular implantable medical device 101 may alternatively be
implanted within a pectoral region or the abdomen of patient 100 to
act as a diaphragmatic pacer, or to provide any of the monitoring
and therapy delivery functions known in the art to be associated
with cardiac pacemakers. Further, modular implantable medical
device 101 may be implanted in the upper buttock region and deliver
spinal cord, urological or gastrological stimulation therapy, or
may be configured to be implanted within the periphery, e.g.,
limbs, of patient 100 for delivery of stimulation to the muscles
and/or peripheral nervous system of patient 100. As is the case
with cranial implantation, the modularity of implantable medical
device 101 may enable implantation at some of these example
locations for which implantation of conventional implantable
medical devices is generally deemed undesirable.
[0035] Modular implantable medical device 101 is not limited to
embodiments that deliver stimulation. For example, in some
embodiments modular implantable medical device 101 may additionally
or alternatively monitor one or more physiological parameters
and/or the activity of patient 100, and may include sensors for
these purposes. Where a therapy is delivered, modular implantable
medical device 101 may operate in an open loop mode (also referred
to as non-responsive operation), or in a closed loop mode (also
referred to as responsive). Modular implantable medical device 101
may also provide warnings based on the monitoring.
[0036] As discussed above, the ability of a modular implantable
medical device 101 according to the invention to be implanted close
to a region within patient 100 to be monitored enables the use of
shorter leads 102. Shorter leads 102 may advantageously improve the
accuracy of such sensors by reducing noise attributable to leads
102. Shorter leads 102 may also advantageously reduce the negative
affects of imaging techniques such as magnetic resonance imaging
"MRI" on a person implanted with implantable medical device
101.
[0037] Additional alternate embodiments for implantable medical
devices implemented according to principles of the present
invention may also include non-electrical based therapies such as
targeted introduction of fluids and similar therapeutic materials
using pumps and reservoirs of material. One skilled in the art will
recognize that any number of implantable devices may be possible
without deviating from the spirit and scope of the present
invention as recited within the attached claims.
[0038] FIG. 2 is a schematic diagram illustrating a modular
implantable medical device 201 according to another embodiment of
the present invention. In this example embodiment, implantable
medical device 201 is arranged in a triangular configuration.
Modular implantable medical device 201 includes three modules: a
control module 210, a power source module 211, and a recharge
module 212. Each of modules 210-212 includes a respective housing.
Modular implantable medical device 201 also contains a set of lead
connection modules 213 that permits external leads 102 (FIGS. 1A
and 1B) to be connected to control module 210 as needed. The
distribution of functional components of modular implantable
medical device 201 into modules permits modular implantable medical
device 201 to possess a thin profile by spreading the components
over a larger surface area.
[0039] Control module 210 includes control electronics for
controlling the monitoring and/or therapy delivery functions of
modular implantable medical device 201, such as a microprocessor,
and may include therapy delivery circuitry. Power source module 211
includes a power source that provides energy to control module 210,
which in some embodiments is a rechargeable power source such as a
rechargeable battery and/or capacitor. Recharge module 212 includes
a recharge coil for inductively receiving energy to recharge a
rechargeable power source within power source module 211.
[0040] In some embodiments, one or modules may be coupled by
coupling modules (not shown). A coupling module may be flexible,
and may include a lumen to carry a conductor or a fluid between
modules of a modular implantable medical device. In some
embodiments, a coupling module is made of a flexible material such
as silicone or a flexible polymer. In other embodiments a coupling
module is hermetic and made of substantially less flexible
material, such as titanium or stainless steel, and the flexibility
of a coupling module is provided by the configuration and/or
construction the coupling module.
[0041] A coupling module may be flexible in a plurality of
directions to provide modules of a modular implantable medical
device with multiple degrees of freedom of motion with respect to
each other. In exemplary embodiments, a coupling module provides at
least three degrees of motion, and the degrees of motion provided
include rotational motion.
[0042] Additional details regarding modules 210, 211 and 212,
additional or alternative modules for a modular implantable medical
device, the interconnection of modules within a modular implantable
medical device, and lead connection modules 213 may be found in
commonly assigned U.S. patent application Ser. No. 10,731,869,
entitled "MODULAR IMPLANTABLE MEDICAL DEVICE," and filed on Dec. 9,
2003; commonly assigned U.S. patent application Ser. No.
10/731,699, entitled "COUPLING MODULE OF A MODULAR IMPLANTABLE
MEDICAL DEVICE," and filed on Dec. 9, 2003; and commonly assigned
U.S. patent application Ser. No. 10/730,878, entitled "LEAD
CONNECTION MODULE OF A MODULAR IMPLANTABLE MEDICAL DEVICE," and
filed on Dec. 9, 2003.
[0043] As illustrated in FIG. 2, modular implantable medical device
201 includes an overmold 214. Overmold 214 at least partially
encapsulates modules 210-212. Further, as will be described in
greater detail below, lead connection modules 213 may be formed in
overmold 214. Overmold integrates modules 210-212 into a structure.
Overmold 214 may provide a flexible structure that permits the
device 501 to conform to a variety of implant locations.
[0044] In some embodiments, overmold 214 may be curved to match the
shape of the location within a patient in which the device is being
implanted. For example, implantation of modular implantable medical
device 201 under the scalp of a patient may be accomplished if
overmold 214 is concave to substantially conform to the shape of
the cranium of the patient. Concavity of modular implantable
medical devices is described in greater detail in a
commonly-assigned U.S. patent application Ser. No. 10/731,867,
entitled "CONCAVITY OF AN IMPLANTABLE MEDICAL DEVICE," and filed on
Dec. 9, 2003. Any number of shapes may be used to match a
particular implantable medical device 201 to an implantation
location for a device.
[0045] Overmold 214 may comprise a solid biocompatible elastomeric
material that is soft and flexible such as silicone. In some
embodiments, overmold 214 comprises two or more materials, and two
or more components. For example, overmold may comprise one or more
elastomeric components formed of an elastomeric material, such as
silicone, and one or more non-elastomeric components formed of a
non-elastomeric material, such as polysulfone, or a polyurethane
such as Tecothane.RTM., which is commercially available from
Hermedics Polymer Products, Wilmington, Mass. The one or more
elastomeric components may provide the overall shape and
flexibility of modular implantable medical device 201, while the
non-elastomeric components may provide structural integrity for
modular implantable medical device 201, restrict intermodule motion
within modular implantable medical device 201 to certain ranges,
and form a part of the lead interconnection modules 213. Further
detail regarding reduction of intermodule motion within modular
implantable medical devices may be found in a commonly-assigned
U.S. patent application Ser. No. 10/731,881, entitled "REDUCING
RELATIVE INTERMODULE MOTION IN A MODULAR IMPLANTABLE MEDICAL
DEVICE," and filed on Dec. 9, 2003.
[0046] FIGS. 3A-3F are schematic diagrams illustrating various
arrangements of multiple modules within a modular implantable
medical device 301 according to various embodiments of the present
invention. In each of these embodiments, modular implantable
medical device 301 has three modules as discussed above in
reference to FIG. 2: a control module 210, a power source module
211, and a recharge module 212. These modules may be arranged into
a variety of configurations, including those illustrated, a lead
connection module s long as any required interconnections needed
between the modules, e.g., coupling modules, may be routed within
the device. The various embodiments include triangular
configurations, in such as those shown in FIGS. 3A-C, and inline
configurations, such as those shown in FIGS. 3D-F. The set of lead
connection devices 313 may be located in various locations within
the device as well.
[0047] In some embodiments, such as those illustrated in FIGS. 3A-C
and 3E-F, an overmold 322 at least partially encapsulates each of
modules 210, 211 and 212. In other embodiments, such as that
illustrated in FIG. 3D, at least one of the modules of modular IMD
301 is located outside of overmold 322. Module 212 located outside
of overmold may, as shown in FIG. 3D, be tethered to overmold 322,
allowing module 212 to be freely positioned some significant
distance from overmold 322. Additional details relating to
configurations of modules within a modular implantable medical
devices and tethering of modules of an implantable medical device
may be found in a U.S. patent application Ser. No. 10/731,869,
entitled "MODULAR IMPLANTABLE MEDICAL DEVICE," and filed on Dec. 9,
2003.
[0048] FIGS. 4A-4C are schematic diagrams illustrating an overmold
422 of a modular implantable medical device 401. FIG. 4A
illustrates that the modular implantable medical device 401
comprises a set of modules 410-412, and a set of motion reduction
elements 421 within overmold 422, such as motion reduction fibers
connecting modules 410 and 411. Modules 410 and 411 are also
coupled by a coupling module 423.
[0049] Because overmold 422 and coupling module 423 are flexible,
overmold 422 and coupling module 423 may not provide sufficient
motion reduction for the modules 410-412. Specifically, excessive
relative motion between modules 410 and 411 may compromise the
structural integrity of coupling module 424, which may lead to
failure of modular implantable medical device 401. Motion reduction
elements 421 are used to provide sufficient structural integrity to
the device 401 once implanted into the patient 100 by restricting
relative motion between modules 410 and 411 to certain directions
or within certain ranges. Additional details regarding motion
reduction elements 421 are described in co-pending and commonly
assigned U.S. patent application Ser. No. 10/731,881, entitled
"REDUCING RELATIVE INTER-MODULE MOTION IN A MODULAR IMPLANTABLE
MEDICAL DEVICE," and filed on Dec. 9, 2003.
[0050] FIG. 4B illustrates that the overmold 422 may include two or
more components, each component made of a different material. In
particular, FIG. 4B illustrates the overmold 422 includes an
elastomeric component 430 and a non-elastomeric component 431. The
non-elastomeric component 431 is typically shaped to surround at
least one of modules 410-412, i.e., is located proximate to sides
of at least one of modules 410-412. In some embodiments, a
plurality of individual non-elastomeric components 431 surround
respective modules 410-412. In other embodiments, a non-elastomeric
component 431 surrounds a plurality of modules 410-412 to integrate
the surrounded modules in a common, semi-rigid structure.
[0051] The one or more non-elastomeric components 431 may be used
to contain one or more modules within elastomeric component 430.
Specifically, the one or more non-elastomeric components 431 may be
formed to hold modules 410-412 within respective positions within
elastomeric component 430. Elastomeric component 430 may, as shown
in FIG. 4B, at least partially encapsulate each of modules 410-412
and provide an desired form factor for a modular implantable
medical device. In some embodiments, non-elastomeric elements 431
are fitted into an elastomeric component 430 to form the overmold
422 before the electronic modules 410-412 are inserted into
respective locations within overmold 422 where they will be
contained by non-elastomeric elements 431.
[0052] Generally, overmold 422 provides a number of functions in
including attaching to modules and other elements to provide a
smooth interface surface for the device as it interacts with the
patient, and protecting electrical connections and feed thru wires
needed to connect modules to external leads.
[0053] Overmold 422 may be constructed from a durometric specific
material to provide a clinically desirable device. In addition, a
material used to construct the overmold 422 may possess a thermal
conductivity characteristic to either act as a heat sink if needed
to dissipate heat from modules 410-412, or a material to act as an
insulator to shield the patient 100 from any excess heat from
modules 410-412. Because the implantable medical device 401 may be
constructed from a large number of modules to perform a desired
task, the materials selected for used in constructing the overmold
422 may vary as needed by each embodiment.
[0054] In embodiments in which overmold 422 is constructed of
components 431 and 432, the device 401 may be fabricated by
integrating components 431 and 432 to form the overmold 422,
constructing the modules 410-412 and their respective connection
modules 423, and constructing any motion reduction elements 421.
Once all of these components are fabricated, the motion restriction
elements 421 may be combined with the overmold 422, and the
interconnected modules 410-412 may be inserted into the overmold
422 into respective positions where they are contained by
components 431.
[0055] FIG. 4C illustrates that the overmold 422 provides sloped
interface 441 between the modules within the device 401 and the
patient's body components. In embodiments in which the device 401
is implanted within tight spaces, such as under the scalp, the
sloped interface 441 provides a smooth transition between the body
and the device modules 410-412. Protrusions are known to cause
possible stress points for tissue that is located over implanted
devices, which can, for example, lead to skin erosion in the case
of a device implanted under the scalp. As such, the sloped
interface 441 attempts to minimize the transition from the modules
410-412 and the edge of the device 401 to eliminate these points of
stress. An angle of interface 442 from the patient's body and the
sloped interface 441 is greater than 90 degrees. Angle 442 may be
between 120 and 150 degrees, is preferably between 130 and 140
degrees, and is most preferably approximately 135 degrees.
[0056] FIGS. 5A-5B are schematic diagrams illustrating the
interaction of components of an implantable medical device that are
part of an overmold. FIG. 5A provides a side cross-sectional view
of an overmold 522 that includes an elestomeric component 530 and a
non-elastomeric component 531 that interfaces with a control module
610. The non-elastomeric component 531 is shaped to mate with and
surround the module 510, and may provide motion reduction for the
module. Specifically, the non-elastomeric component 531 may be
mechanically connected to at least one other module of a modular
implantable medical device, e.g., to non-elastomeric components
that surround other modules of an implantable medical device, by a
motion reduction element 521. In other words, the overmold 522
encapsulates a plurality of modules in this embodiment, and each of
the modules may be surrounded by a non-elastomeric component 531
that is connected to other non-elastomeric components by motion
reduction elements 521.
[0057] A through hole 551 may be located through overmold 522,
e.g., through elastomeric component 530 and non-elastomeric
component 531, to provide an attachment point for the implantable
medical device. In some embodiments, the implantable medical device
may be secured in place using bone screws or similar attachment
devices that secure the device to the patient. Such through holes
551 permit the device to be mechanically attached to the patient
once the device is positioned at a desired location.
[0058] In addition, elastomeric component 530 is shown as
completely encapsulating the modules and components within FIG. 5.
However, in some embodiments, elastomeric component 530, like
non-elastomeric component 531, may merely surround the module 510
but not cover the top of the module. Such an arrangement may render
the profile of the overall device smaller. In such an alternate
embodiment, a surface across the overmold and the electronics
module 510 may minimize transition discontinuities to minimize
profile changes that may interact with a patient after
implantation. In other embodiments, one or both components 530 and
531 cover a top of module 510, or fully encapsulate module 510.
[0059] FIG. 5B illustrates a top view of the overmold 522 having an
elastomeric component 530 that covers a non-elastomeric component
531 that surrounds the control module 510. The through hole 551
used as an attachment point is shown as part of the non-elastomeric
component 531 that is covered by the elastomeric component 530. The
shape of the non-elastomeric component 531 and control module 510
are shown as being rectangular in this embodiment. However, one
skilled in the art will recognize that any shape for the
non-elastomeric component 531 and control module 510 may be used
without deviating from the spirit and scope of the present
invention. Further, the shape of non-elastomeric component 531 need
not be the same as that the shape of the component that it
surrounds. The modules may be restrained within the overmold 522
using many restraint mechanisms known in the arts including
attachment elements, adhesives, snap rings, and similar
elements.
[0060] While the overmold 522 described above may be constructed
from two different materials, a softer, more flexible elastomeric
component 530 and one or more harder, more rigid non-elastomeric
components 531, one skilled in the art may recognize that an
overmold 522 may include a single component made of either class of
material to provide the surface smoothing, module integration, and
structural module restraint features described herein.
[0061] Finally, the overmold 522 may include several additional
features unrelated to the above functions regarding the restraint
and interconnection of multiple modules. In one embodiment,
radio-opaque markers 561 and 562 may be imbedded within the
overmold 522 to assist in determining an exact location of an
implantable medical device within a patient. These radio-opaque
markers 561 and 562 typically possess a non-symmetrical shape to
permit registration and orientation of the device 501 from imaging
of the markers. These radio-opaque markers may be constructed using
barium and similar materials that permit such imaging. A telemetry
and/or recharge coil may be embedded directly within the overmold
522. Therapeutic agents, such as anti-infection and
anti-inflammatory agents may be impregnated within the overmold 522
to assist in complications that may arise from implantation and use
of the implanted medical device.
[0062] FIG. 6 is a schematic diagram illustrating degrees of
intermodular motion that may be present in modular implantable
medical device. For any two modules within a distributed medical
device, motion between the two modules may include pitch motion
601, yaw motion 602, and roll motion 603. For the motion reduction
elements discussed above, one or more of these three degrees of
motion may be limited to prevent mechanical failures of
interconnections between the modules during use of a modular
implantable medical device. Specifically, modules of a modular
implantable medical device may be connected by connector modules,
which may be compromised by excessive intermodule motion. Such
interconnect members are described in greater detail in commonly
assigned U.S. patent application Ser. No. 10/731,881, entitled
"REDUCING RELATIVE INTERMODULE MOTION IN A MODULAR IMPLANTABLE
MEDICAL DEVICE," and filed on Dec. 9, 2003.
[0063] FIG. 7 is a schematic diagram illustrating motion reduction
within various degrees of motion within a modular implantable
medical device. For any two modules 701-702 within an implantable
medical device, a connector module 721 may be used between the
modules 701-702 to connect elements within these modules 701-702.
Motion reduction elements 722 and 723 may be used to reduce
inter-modular motion, and in some cases, to limit inter-modular
motion to a range of motion.
[0064] Motion reduction elements 722 and 723 may be formed as part
of non-elastomeric components 531 of an overmold 522 associated
with each of modules 701 and 702. As shown in FIG. 7, motion
reduction elements 722 and 723 allow free inter-modular motion
within one of the degrees within a range. In some embodiments, one
non-elastomeric component includes one or more motion reduction
elements 722. In other embodiments, two non-elastomeric components
531 include motion reduction elements 722 and 723, respectively,
which interact to reduce inter-modular motion.
[0065] A modular implantable medical device may include any number
of motion reduction elements, which may take any of a variety of
shapes. In some embodiments, motion reduction elements may be used
in all axes to maximize the amount of motion reduction provided.
The implantable medical device having multiple modules typically
requires sufficient motion reduction to prevent undue mechanical
stresses on interconnection connection member 721 between the
modules 701-702 that may not be provided by a flexible overmold
522.
[0066] Additional details regarding the set of motion reduction
elements 521 are described in co-pending and commonly assigned U.S.
patent application Ser. No. 10/731,881, entitled "REDUCING RELATIVE
INTER-MOLDULE MOTION IN A MODULAR IMPLANTABLE MEDICAL DEVICE," and
filed on Dec. 9, 2003.
[0067] FIG. 8A is a block diagram illustrating an example
embodiment of a modular implantable medical device 801 having a
tethered lead interconnect site 861 according to the present
invention. An overmold 822 of implantable medical device 801 at
least partially encapsulates and connects a plurality of modules
810-812 while not encapsulating lead connection modules 813 that
are part of tethered lead interconnect site 861. In such
embodiments, the implantation of device 801 would not require the
insertion of external leads into the overmold 822. In addition, the
external leads may be located a distance away from the device 801.
Such an arrangement may assist in the management of the external
leads as they are placed within the patient and routed to a device
implantation location. Further, location of leads and connection
site 861 away from overmold 822 may make it less likely that the
leads will be damaged during a surgical explant procedure.
[0068] In alternate embodiments shown in FIGS. 8B-8C, overmold 822
may possess mechanical structures such as grooves 832, an
externally attached pouch 833, or an integrated containment cavity
834 to contain and/or route the external leads away from the
implantable medical device 801 in an efficient manner. In some
embodiments, the external leads may possess a minimum length to
provide a particular electrical characteristic for the implantable
medical device 801. This minimum length may be greater than a
distance needed by a particular patient for some implantation
locations. These mechanical structures that assist in external lead
management may accommodate any extra lead material that needs to be
part of the device 801 in some implantation embodiments. Because
the overmold may be spread over an area surrounding the modular
device, the overmold may cover holes in the cranium formed to allow
external leads to access the brain. Additional structures,
including one or more cap structures 835 that secure a lead as it
passes through the hole in the cranium may be an integral part of
the overmold connector module 822.
[0069] Additional details regarding the lead connection modules
described in co-pending and commonly assigned U.S. patent
application Ser. No. 10/730,878, entitled "LEAD CONNECTION MODULE
OF A MODULAR IMPLANTABLE MEDICAL DEVICE," and filed on Dec. 9,
2003.
[0070] FIG. 9 is a block diagram illustrating an example embodiment
of a modular implantable medical device 901 having an access loop
971 for removal according to the present invention. Access loop 971
may be mechanically coupled to, or formed as a part of overmold
connector module 922. This access loop 971 may be used to assist in
the removal of the implantable medical device 901 at a point in
time when the device 901 is no longer needed by the patient, or at
a point in time when a particular device 901 needs to be replaced.
The device 901 may be encapsulated within the patient 100 with scar
tissue fibers such that physical effort will be required to remove
the device 901 from its implantation location. This access loop 971
provides a clinician a removal assist structure to physically
manipulate the implantable medical device 901 during its removal.
This access loop 971 may also be useful during implantation of the
device 901 as well as it provides a handle to manipulate the device
901 without handing the overmold 922 and its related modules. One
skilled in the art will recognize that alternate embodiments for
the access loop that may include removal handles, a strip cord and
a reinforced opening within the overmold connector module to
provide a mechanism to grasp the device to assist in removal.
[0071] FIG. 10 is a schematic diagram illustrating an example
embodiment of a modular implantable medical device 1001 having a
triangular module arrangement according to the present invention.
In this embodiment, a triangular arrangement of modules is shown
with a overmold 1022 that at least partially encapsulates all of
the modules. Lead interconnection modules 1013 are located between
the modules at a common location. Overmold 1022 provides a slope
interface 1041.
[0072] FIG. 11 is a schematic diagram illustrating an example
embodiment of a modular implantable medical device 1101 having an
inline module arrangement according to the present invention. In
this embodiment, an inline arrangement of modules is shown with an
overmold 1122 that at least partially encapsulates all of the
modules. A lead interconnection module 1113 is located on one side
of the overmold 1122. Overmold 1122 provides a slope interface
1141.
[0073] FIG. 12 is a schematic diagram illustrating side view of a
multi-module implantable medical device having an inline module
arrangement according to the present invention. The side view of
the device 1201 shows an underside of the device 1202 that possess
a curved shape to permit implantation at a location having a curved
body structure.
[0074] FIG. 13 is a schematic diagram illustrating an exploded view
of a modular implantable medical device 1301 having a triangular
module arrangement according to the present invention. In this
embodiment, yet another triangular arrangement of modules is shown
with an overmold 1322 at least partially encapsulating all of the
modules. A slope interface element 1341 is shown surrounding the
overmold 1322. In this embodiment, the slope interface element 1341
is shown as a separate physical structure, such as a flexible band,
an o-ring, removable flexible flange, or a tapered outer contour
element that surrounds the overmold 1322, rather than a tapered
portion of overmold 1322. Slope interface element 1341 provides a
desired sloped interface between the edge of the implantable
medical device and the patient. In some embodiments, the shape and
contour of slope interface element 1341 may be modified at the time
of implantation to obtain a desired shape, or slope interface
elements 1341 may be selected at the time of implantation from a
variety of slope interface elements to provide a desired slope
interface for a particular patient.
[0075] FIG. 14 is a flowchart illustrating a method of constructing
an implantable medical device with an overmold according to the
present invention. An implantable medical device 401 may be
fabricated by constructing the overmold 422 (1401) from a first and
second component. As discussed above, overmold 422 may comprise two
or more materials, and two or more components. For example,
overmold may comprise one or more elastomeric components formed of
an elastomeric material, such as silicone, and one or more
non-elastomeric components formed of a non-elastomeric material.
Once the overmold 422 is completed, the modules 410-412 with their
respective connector modules 423 are constructed (1402). Next, any
motion reduction elements 421 included in the device 401 are
constructed. Once all of these components are fabricated, the
motion restriction elements 421 may be combined with the overmold
422 (1403) and the interconnected modules 410-412 may be inserted
(1404) into the overmold 422. From the combination of these
components, the device 401 is formed.
[0076] While the above embodiments of the present invention
describe a overmold for a modular implantable medical device, one
skilled in the art will recognize that the invention is not so
limited. For example, in some embodiments an implantable medical
device comprises a single housing and an overmold that at least
partially encapsulates the housing. It is to be understood that
other embodiments may be utilized and operational changes may be
made without departing from the scope of the present invention as
recited in the attached claims.
[0077] As such, the foregoing description of the exemplary
embodiments of the invention has been presented for the purposes of
illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms
disclosed. Many modifications and variations are possible in light
of the above teaching. It is intended that the scope of the
invention be limited not with this detailed description, but rather
by the claims appended hereto.
* * * * *