U.S. patent application number 12/074621 was filed with the patent office on 2008-06-26 for flexible hermetic enclosure for implantable medical devices.
Invention is credited to William L. Athas, Arthur Gwerder, Terrance Ransbury.
Application Number | 20080154327 12/074621 |
Document ID | / |
Family ID | 36926817 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080154327 |
Kind Code |
A1 |
Ransbury; Terrance ; et
al. |
June 26, 2008 |
Flexible hermetic enclosure for implantable medical devices
Abstract
A flexible, hermetically sealed enclosure device allows for the
controlled insertion of an implantable device into the body of a
patient. A series of bellows can be used to interconnect a number
of rigid containers, each containing electronic or other components
necessary for the implantable device. The bellows provide
flexibility, columnar strength, and torqueability (for steering),
while protecting the internal components. The bellows also can be
welded to the containers to form a hermetic seal that can be
electrically continuous, whereby standard wiring and components can
be used without fear of corrosion or contamination. Such an
enclosure can be used with systems such as an intravascular
implantable pacing, drug delivery, or defibrillation system.
Inventors: |
Ransbury; Terrance; (Chapel
Hill, NC) ; Athas; William L.; (Chapel Hill, NC)
; Gwerder; Arthur; (Pleasanton, CA) |
Correspondence
Address: |
STALLMAN & POLLOCK LLP
353 SACRAMENTO STREET, SUITE 2200
SAN FRANCISCO
CA
94111
US
|
Family ID: |
36926817 |
Appl. No.: |
12/074621 |
Filed: |
March 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11088495 |
Mar 24, 2005 |
7363082 |
|
|
12074621 |
|
|
|
|
Current U.S.
Class: |
607/36 |
Current CPC
Class: |
A61N 1/37512 20170801;
A61N 1/37223 20130101; A61N 1/37205 20130101; A61N 1/37518
20170801; A61N 1/3968 20130101; A61N 1/37516 20170801 |
Class at
Publication: |
607/36 |
International
Class: |
A61N 1/375 20060101
A61N001/375 |
Claims
1. A flexible enclosure for implantation in a body, comprising: a
plurality of first means for housing at least one electrical
component wholly within that means, the plurality of first means
configured to be implanted into the body as part of a chronically
implanted device wholly implanted within the body; and a plurality
of second means for interconnecting two of the first means to form
an elongated series of first means and second means, each second
means further having an internal passage through which the
components in adjacent first means may be connected.
2. A flexible enclosure according to claim 1, wherein the flexible
enclosure is adapted to be implanted in the vasculature of the
body.
3. A flexible enclosure according to claim 1, wherein each of the
first means and second means has a diameter in the range of about 3
mm to about 8 mm.
4. A flexible enclosure according to claim 1, wherein each second
means provides for three-dimensional flexing.
5. A mechanical bellows, configured to connect two rigid containers
as part of a flexible enclosure for chronic implantation wholly in
the vasculature of a body, wherein each container is configured to
contain at least one electronic component wholly within that
container, the bellows having an internal passage allowing for
interconnection of components in the rigid containers.
6. A mechanical bellows according to claim 5, wherein the bellows
provides for three-dimensional flexing.
7. A mechanical bellows according to claim 5, wherein the bellows
is formed of a biocompatible material.
8. A mechanical bellows according to claim 5, wherein the bellows
is formed of a material selected from the group consisting of
titanium, nitinol, stainless steel, nickel, and biocompatible
polymers.
9. A mechanical bellows according to claim 5, wherein the bellows
comprises two or more ridge portions.
10. A method of implanting an intravascular device, comprising:
providing an intravascular device including a flexible enclosure
consisting of a plurality of rigid containers, each container
containing at least one component of the intravascular device, and
a plurality of mechanical bellows, each bellows connecting two of
the rigid containers to form an elongated chain of containers and
bellows, each bellows further having an internal passage allowing
for interconnection of the components in the rigid containers;
introducing the intravascular device into the vasculature of a
patient; advancing the intravascular device to a target location
within the vasculature; and anchoring the intravascular device
within the target location.
11. The method of claim 10, further comprising: providing at least
one electrode coupled to the intravascular device; positioning the
at least one electrode within the cardiovascular system.
12. The method of claim 10, wherein the flexible enclosure includes
an electrode positioned on the outside of the flexible enclosure,
the electrode coupled to the intravascular device.
13. The method of claim 10, wherein the anchoring step includes
placing an anchor in contact with the flexible enclosure and
expanding an anchor into contact with a wall of the target
location.
14. A method of implanting an intravascular device, comprising:
providing an intravascular device including a flexible enclosure
consisting of a plurality of rigid containers, each container
containing at least one component of the intravascular device, and
a plurality of mechanical bellows, each bellows connecting two of
the rigid containers to form an elongated chain of containers and
bellows, each bellows further having an internal passage allowing
for interconnection of the components in the rigid containers;
providing instructions for implanting the intravascular device,
comprising: introducing the intravascular device into the
vasculature of a patient; advancing the intravascular device to a
target location within the vasculature; and anchoring the
intravascular device within the target location.
15. The method of claim 14, further comprising: providing at least
one electrode coupled to the intravascular device; positioning the
at least one electrode within the cardiovascular system.
16. The method of claim 14, wherein the flexible enclosure includes
an electrode positioned on the outside of the flexible enclosure,
the electrode coupled to the intravascular device.
17. The method of claim 14, wherein the anchoring step includes
placing an anchor in contact with the flexible enclosure and
expanding an anchor into contact with a wall of the target
location.
Description
PRIORITY
[0001] This is a divisional of U.S. application Ser. No.
11/088,495, filed Mar. 24, 2005.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates to systems and methods for
implanting medical devices into a patient's vasculature, such as to
sense electrical activity and/or electrically stimulate the
heart.
BACKGROUND
[0003] There are a number of medical devices that can have portions
implanted into a patient's vasculature. For example, devices such
as pacemakers, defibrillators, and implanted cardioverter
defibrillators ("ICDs") have been successfully implanted for years
for treatment of heart rhythm conditions. Pacemakers are implanted
to detect periods of bradycardia and deliver electrical stimuli to
increase the heartbeat to an appropriate rate, while ICDs are
implanted in patients to cardiovert or defibrillate the heart by
delivering electrical current directly to the heart. Another
implantable defibrillation device can detect an atrial fibrillation
(AF) episode and deliver an electrical shock to the atria to
restore electrical coordination.
[0004] Next generation defibrillators, ICDs, pacemakers, etc., may
take the form of elongated intravascular devices, such as those
described, for example, in U.S. patent application Ser. No.
10/454,223, entitled "IMPLANTABLE INTRAVASCULAR DEVICE FOR
DEFIBRILLATION AND/OR PACING," filed Jun. 4, 2003; U.S. patent
application Ser. No. 10/453,971, entitled "DEVICE & METHOD FOR
RETAINING A MEDICAL DEVICE WITHIN A VESSEL", filed Jun. 4, 2003; as
well as U.S. patent application Ser. No. 10/862,113, entitled
"INTRAVASCULAR ELECTROPHYSIOLOGICAL SYSTEM AND METHODS," filed Jun.
4, 2004, each of which is hereby incorporated herein by reference.
These devices often contain electric circuitry and/or electronic
components that must be hermetically sealed to prevent damage to
the electronic components and the release of contaminants into the
bloodstream. This can require the use of expensive shielding and
insulating components, which have to be designed in a way to
prevent problems with clotting and obstruction of blood flow.
Further, due to the length of these implantable devices, which in
some cases can be approximately 10-60 cm in length, the devices
must be flexible enough to move through the vasculature while being
sufficiently rigid to protect the internal components. It is
desirable to simplify these devices to allow for the use of
standard components that can lower the cost and complexity of these
devices while still providing the necessary flexibility and
support.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIGS. 1 (a) and (b) are schematic diagrams illustrating
methods of device implantation of the prior art.
[0006] FIG. 2 is a plan view showing an intravascular
electrophysiological device of the prior art.
[0007] FIG. 3 is (a) a plan view and (b) a cross-section showing an
intravascular electrophysiological device in accordance with one
embodiment of the present invention.
[0008] FIG. 4 is (a) a perspective view illustrating the bending
capability of the device of FIG. 4, as well as (b) a plan view and
(c), (d) cross-sectional views of the device of FIG. 4 inserted
into the vascular system of a patient.
[0009] FIG. 5 includes (a)-(b) views showing a multi-chamber
pacemaker and (c)-(e) views showing an implantable defibrillator
including components in the interconnected, hermetically sealed
casing in accordance with embodiments of the present invention.
[0010] FIGS. 6(a)-6(f) are diagrams showing a procedure for
implanting a device of FIG. 5.
[0011] FIGS. 7(a)-7(b) show cross-sections of interconnection
methods than can be used in accordance with embodiments of the
present invention.
DETAILED DESCRIPTION
[0012] Systems and methods in accordance with embodiments of the
present invention can provide for hermetic sealing of electronic
and other components in the body of a patient, such as in the
vasculature. Flexible methods of interconnection allow rigid
containers to be moved into position inside the body while
shielding the components internal to those containers from the
bloodstream. The hermetic seal allows standard components to be
used that are not otherwise biocompatible, allowing for simpler and
cheaper devices. Because these methods of interconnection do not
allow for the introduction of water vapor or other materials into
the device, the implanted device will be less susceptible to
corrosion and can improve the lifetime and reliability of the
device.
[0013] There are a number of known techniques for implanting an
elongated, flexible device in the vasculature of a patient. One
such technique will be described with respect to FIGS. 1(a) and
1(b). First, a small incision is formed in the femoral vein and an
introducer 104 is inserted through the incision into the vein to
keep the incision open during the procedure. Next, the device 106
is passed into the introducer 104, and pushed in a superior
direction through the inferior vena cava ("IVC") 102, through the
right atrium 110 towards the superior vena cava ("SVC") 100. With
an end of the device 106 still remaining outside the body, mandrel
112 and lead 116 are attached to the exposed end of the device 106
as shown in FIG. 1(b). Pressure is applied against the mandrel 112
to advance the device 106 into the left subclavian vein ("LSV")
110. Once the device is in the target position, an anchor 118 is
expanded into contact with the walls of the inferior vena cava 108.
The mandrel 112 is detached from the device 106 and removed from
the body.
[0014] Such a device can be implanted in a number of alternative
ways, including methods described in U.S. patent application Ser.
No. 10/862,113, filed Jun. 4, 2004, incorporated by reference
above. For example, the device can be introduced into the venous
system via the femoral vein, introduced into the venous system via
that subclavian vein or the brachiocephalic veins, or into the
arterial system using access through one of the femoral arteries.
Moreover, different components of the intravascular systems may be
introduced through different access sites. For example, a device
may be separately introduced through the femoral vein and a
corresponding lead may be introduced via the subclavian vein.
[0015] An example of a prior device 200 that can be inserted
according to the above-mentioned method is shown in FIG. 2. This
device 200 includes elongate segments 202, 204, 206 defining
interior space for components (not shown) to be housed within the
segments. Each segment is separately enclosed by its own enclosure.
The components within the enclosures are electrically connected by
flex circuits 208, and the enclosures are connected using a
flexible material such as silicone rubber filler to form
articulations 210. The articulations 210 form hinges that bend in
response to passage of the device 200 through curved regions of the
vasculature. Many of these enclosures are coupled together to form
the device body. A polymeric coating 112 may be formed on the
exterior surface of the device.
[0016] A device in accordance with one embodiment of the present
invention can provide the same functionality as the prior device of
FIG. 2, while allowing use of standard components that can reduce
the complexity and cost of the overall device, as well as providing
other advantages. For example, FIGS. 3(a) and 3(b) show one such
flexible structure 300 that can be used in accordance with various
embodiments of the present invention. In this structure, one or
more rigid enclosures 302, or "containers," can be used to contain
electronic components to be implanted inside the vasculature of a
patient. The containers can be used to house electromechanical
parts or assemblies to form sophisticated implantable devices such
as defibrillators, pacemakers, and drug delivery systems. These
containers can be of any appropriate shape, cross-section, and
length, but in this example are shown to have a cylindrical shape
with a diameter of approximately 3-15 mm and a length of
approximately 20 mm to 75 mm. In order to allow for insertion of
the rigid components into the vasculature, it can be desirable to
limit the diameter to less than about 8 mm with a length of no more
than about 70 cm. Given the minimal space allowed for components,
it can be desirable to arrange the device components so as to make
efficient use of the available space. The length of the components
can vary, depending upon the ultimate destination of each component
and the path through which each component must pass, as the amount
of bending and varying size of the path can affect the maximum
component size for different areas of the vasculature.
[0017] The thickness of the walls of the container also can vary,
depending upon the application and the material being used. It can
be desirable for the walls to be as light as possible, while still
providing for sufficient rigidity. In one example, the container
can be made of a biocompatible material that is capable of
sterilization and is conductive, with a sidewall thickness on the
order of about 0.001'' to 0.005''. Possible materials include
titanium, nitinol, stainless steel, nickel, or alloys thereof, as
well as polymers such as nylon or polyurethane. The sidewall
thickness can vary between containers, as well as within an
individual container in order to accommodate the internal
components, etc.
[0018] Depending upon the material being used, the containers can
be covered by a layer or coating that may be electrically
insulative, particularly if the enclosure material is conductive.
One example of such a coating is ePTFE. It can be desirable to
provide a coating that is anti-thrombogenic (e.g., perfluorocarbon
coatings applied using supercritical carbon dioxide) so as to
prevent thrombus formation on the device. It also can be beneficial
for the coating to have anti-proliferative properties so as to
minimize endothelialization or cellular ingrowth, since minimizing
growth into or onto the device can help minimize vascular trauma
when the device is explanted. The coating can also be selected to
elute anti-thrombogenic compositions (e.g., heparin sulfate) and/or
compositions that inhibit cellular in-growth and/or
immunosuppressive agents. If the enclosure is conductive, this
layer or coating may be selectively applied or removed to leave an
exposed electrode region on the surface of the enclosure where
necessary.
[0019] Any appropriate number of these containers 302 can be
combined using interconnecting bellows 304. Interconnecting
mechanical bellows can be used to connect a number of rigid
containers in order to form a flexible device. For many devices,
this will include a string of at least three containers. The
bellows can be of any appropriate shape, but can preferably have a
shape similar in cross-section to the cross-section of the
container, in order to prevent the occurrence of edges or ridges
that can give rise to problems such as the formation of blood clots
in the vasculature. The bellows can be made of a biocompatible
material similar to the containers. Any coatings used for
electrically insulating the containers and/or making the containers
more hemo-dynamically compatible also can be used with the
bellows.
[0020] The bellows can have a connector portion 306 on each end to
allow the bellows to be connected with a container. A connecting
process such as welding can be used to form a continuous, hermetic
seal between the bellows and the containers. A sleeving 308 or
overmold can be used to form an electrically continuous device, or
to adjust the flexibility and/or steerability of the device. Many
types of welding, using lasers or e-beams, for example, can be used
to create a circular weld about the device, depending upon the
necessary heating and weld thickness. The welding device can form
the weld by rotating about the seam between the bellows and the
containers or shell segments. The resultant weld can enclose the
interior such that an elastomer is no longer needed to seal the
components from the bloodstream.
[0021] By forming a hermetic seal, it is possible to use standard
elements that would not otherwise be able to be implanted into the
vasculature without insulating or shielding in place. For instance,
as shown in the cross-section of FIG. 3(b), electronic or
fiberoptic cabling 312, wiring, or pressure vessels can be used to
transmit signals and/or power between components 310 in separate
implanted containers 302, yet be isolated from the body, passing
through an internal passage in the connecting bellows. Copper and
other materials can be used, which are relatively inexpensive and
good conductors but are not otherwise biocompatible. Without the
hermetic seal, as in prior art devices, it would be necessary to
run insulated wiring through a polymer such as silicone, which is
not hermetic and is porous to water vapor. The water vapor passing
through the silicone can leads to corrosion of the inner electrical
components over time. The ability to use standard wiring and
cabling allows the device to be smaller and less expensive, and
less susceptible to corrosion over time.
[0022] The bellows can have a smooth inner diameter, allowing for
wires and devices to be passed through without damage due to
snagging. The smoothness of the inner surface also allows the
bellows to be bent without pinching or applying pressure points to
the inner components. The inner surface can have any appropriate
shape in cross-section, but can preferably be circular or
elliptical in many embodiments in order to allow for maximum
flexibility in bending direction, as a rectangular bellows would be
biased to four bending directions. The ratio of the length to the
width of the bellows, as well as the shape of the bellows, can
determine the degree of bending relative to the central axis of the
bellows as would be known to one of ordinary skill in the art.
While a 90.degree. bend in one direction might be possible, with an
overall bending range of 180.degree., it might be preferable in
some embodiments to limit the bending range of the bellows to less
than 45.degree. from the central axis, in order to allow for
steering of the device as well as providing some lateral strength
and preventing undesired bending or angling of the containers. In
other embodiments, the bending range of the bellows can be about
360.degree., depending on the length of the bellows, allowing for
the bellows to form a U-shape. In some embodiments, it can be
desirable to bias at least some of the bellows to have
approximately zero bending, such that the bellows will not bend
unless the path in which the bellows is placed requires such
bending. In other embodiments, where the shape of the path is known
for the end location of each bellows, each bellows can be biased or
pre-shaped to a particular shape, curvature, or degree of bending.
This not only helps to control the final shape, but can aid in the
proper positioning of the device.
[0023] The sequence of devices and linking bellows can be repeated
as necessary to make a device of an appropriate length. For
example, FIG. 4(a) shows a device 400 having ten containers 402
connected through bellows 404, to be implanted in the vasculature
as shown in FIG. 4(b). As seen in FIGS. 4(c) and 4(d), the diameter
of a patient's vasculature (from about 10 mm to more than 30 mm)
can be different at a first location 420 than at a second location
430. In this example, the LSV inner diameter at the first location
420 is 12 mm, while the IVC inner diameter at the second location
430 is 20 mm. Having the same outer diameter for each container,
shown in this example to be about 7 mm, means that a larger
percentage of the cross-sectional area of the LSV will be occupied
at the first location than at the second location. In order to
minimize the amount of cross-sectional area occupied by the device
at each point along the LSV, the diameters of each container and/or
bellows can be scaled such that the outer diameters of the
containers decrease from the second location towards the first
location. For example, a container at the second location might
have an outer diameter of 7 mm, while a container at the first
location might have an outer diameter of 5.5 mm. Further, each
individual container and/or bellows can be tapered to fit the
desired space in the body. For example, a container might have an
outer diameter 7 mm at a first end, but taper to an outer diameter
of 6.8 mm at a second end.
[0024] The device can be proportioned to be passed into the
vasculature and to be anchored within the patient's vasculature
with minimal obstruction to blood flow. Suitable sites for the
device can include, but are not limited to, the venous system using
access through the right or left femoral vein or the subclavian or
brachiocephalic veins, or the arterial system using access through
one of the femoral arteries. The housing of device can have a
streamlined maximum cross sectional diameter which can be in the
range of 3-15 mm or less, with a maximum cross-sectional diameter
of 3-8 mm or less in one embodiment. The cross-sectional area of
the device in the transverse direction (i.e. transecting the
longitudinal axis) can preferably be as small as possible while
still accommodating the required components. This area can be in
the range of approximately 79 mm.sup.2 or less, in the range of
approximately 40 mm.sup.2 or less, or between 12.5-40 mm.sup.2,
depending upon the embodiment and/or application.
[0025] The cross-section of the device (transecting the
longitudinal axis) may have a circular cross-section, although
other cross-sections including crescent, flattened, or elliptical
cross-sections may also be used. It can be highly desirable to
provide the device with a smooth continuous contour so as to avoid
voids or recesses that could encourage thrombus formation on the
device.
[0026] As discussed above, the interconnected device can be
implanted using any of a number of implantation techniques. The
ability of the bellows to flex, combined with the lateral strength
of the interconnections, allows for some degree of steering of the
device inside the body. In one embodiment, a bellows mechanism
provides 1:1 torque transmission over the entire length of the
overall device. This amount of torque when combined with the
curvature can provide steerability when navigating the device into
place within the body. In order to further help with the insertion
of the device, the device can be placed inside a flexible and
retractable introducer sheath 406 shown in partial cross-section in
FIG. 4(a). The sheath can be made of any appropriate material, such
as polyurethane or silicone, and can have any appropriate thickness
and inner and outer diameters, such as an inner diameter of up to
24 French (8 mm), with wall thicknesses on the order of 0.005'' and
up. The sheath can be slidably positioned over the device during
the insertion process, retaining any device anchor in a compressed
position where applicable, then pulled from over the device after
insertion. Retraction of the sheath once the device is in place
allows the anchor to expand into contact with the surrounding walls
of the vessel, thereby holding the medical implant in the desired
location. Once deployed, the anchor can be intimate to the vessel
wall, which is distended slightly, allowing the vessel lumen to
remain approximately continuous despite the presence of the anchor
and thus minimizing turbulence or flow obstruction. Any of a number
of anchors can be used such as are known and/or used in the art.
Examples of such anchors are given in U.S. patent application Ser.
No. 10/862,113, incorporated herein by reference above.
[0027] In addition to the ability of the bellows to bend away from
the central or long axis of the device, the bellows also allow for
flexibility along the central axis of the device. The ability to
flex along the central axis provides shock absorption in the long
axis as well as 3-dimensional flexing. Shock absorption can help to
protect the device and internal components during the implant
process by minimizing the motion of the implanted device. Further,
shock absorption can provide a 1:1 torque ratio for steering during
the implant process. The shock absorption also can help during the
life of the device, as the natural movement of the body of a
patient can induce some stress on the device.
[0028] In order to further reduce stresses on the device, an
overmold (such as shown in FIGS. 3 and 4) of a material such as
silicone or polyurethane can be formed around the bellows to
provide rigidity and columnar strength. An overmold sleeving can
decrease the flexibility of the device where more rigidity is
desired. An overmold sleeving also can be more flexible than the
bellows such that the bellows are the primary limiting factor on
flexibility. The overmold also can function to prevent the
occurrence of ridges, edges, and valleys that could otherwise be
present on the outside surface of the bellows. Making the outer
surface of the bellows relatively smooth prevent the occurrence of
turbulence and clotting of the blood that could otherwise result
from a rippled bellows surface. If the device is not being
implanted into the vascular system, overmolding might not be
necessary.
[0029] FIGS. 5(a) and (b) show a plan view and a diagram,
respectively, of a multi-chamber pacemaker 500 including electronic
components contained in a hermetically sealed, flexible enclosure
in accordance with one embodiment of the present invention. As can
be seen, the pacemaker includes in section 502 a multi-chamber
pacer 508 in electrical communication with a first battery 504 and
a second battery 506. Methods for making and using implantable
pacemakers and the components therein are known in the art and will
not be discussed in detail herein. FIGS. 5(c), (d), and (e) shown a
plan view and diagrams, respectively, of an implantable
defibrillator that including electronic components contained in a
hermetically sealed, flexible enclosure in accordance with another
embodiment of the present invention. This exemplary defibrillator
includes in section 512 an anchor 514 followed by three capacitors
516, 518, 520 in electrical communication with an output module
522. In section 524, the device includes a charger 526 in
electrical communication with the output module 522 and a pair of
batteries 528, 530, which in turn are in electrical communication
with a control battery 532 and a control module 534. Methods for
making and using defibrillators and the components therein also are
known in the art and will not be discussed in detail herein.
[0030] There can be a number of ways to connect the containers and
bellows, such as is shown in the example of FIG. 7(a). In this
example, a collar 700 is used to connect the bellows 702 to a
container (not shown) opposite the bellows. The bellows can be
connected to the collar 700 by any appropriate mechanism, such as a
laser weld at a point of connection 704. These bellows can have a
wall thickness on the order of about 0.002'' in one example, formed
of a material such as nickel. Another example is shown in FIG.
7(b), where a titanium cutoff ring 710 is connected to the bellows
712 via a laser weld 716. A balloon seal 714 can be placed over the
bellows 712 in place of an overmold. The balloon seal 714 can be
capable of expanding to fill gaps between the seal and the bellows,
as well as to apply pressure to the bellows to ensure the seal
remains in place during implantation. Other materials can be placed
over the bellows in place of an overmold, such as a covered braid
material that is capable of flexing while assisting device
steerability. The volume between the covered braid and the bellows
can be filed with a solid material to adjust the flexibility of the
device. Other approaches are possible, such as using a molded
bellows that has a sufficiently smooth exterior such that an
overmold or other overlying material is not needed.
[0031] Although the embodiments are described with respect to
bellows as are well known in the literature, there may be a number
of other expansion joints and/or flexible and expansible vessels
that can be used to connect containers in accordance with
embodiments of the present invention. These devices can be made of
any appropriate biocompatible material, or made of any appropriate
material such as metal or polymers that are coated to be
biocompatible.
[0032] Embodiments in accordance with the present invention are
described primarily with respect to intravascular
electrophysiological systems that may be used for a variety of
functions, although any of a number of other implantable systems
known and used in the art can benefit from a hermetically sealed,
flexible enclosure as described herein. In general, elements of
these systems include at least one device body and typically, but
optionally, at least one lead coupled to the body. One or more
retention devices can facilitate retention of the device body
and/or leads or other elements within the vasculature. Components
such as mandrels, stylets, and/or guidewires can be used to
facilitate implantation of the system. Other components that can be
used with such devices include those described, for example, in
U.S. patent application Ser. No. 10/862,113, filed Jun. 4, 2004,
which is incorporated by reference above.
[0033] Implantable devices can include components known in the art
to be necessary to carry out the system functions. For example, a
device can include one or more pulse generators, including
associated batteries, capacitors, microprocessors, and circuitry
for generating electrophysiological pulses for defibrillation,
cardioversion and/or pacing. A device also can include detection
circuitry for detecting arrhythmias or other abnormal activity of
the heart. The specific components can depend upon the application
for the device, such as whether the device is intended to perform
defibrillation, cardioversion, and/or pacing along with its sensing
functions.
Applications
[0034] Intravascular electrophysiological systems of the type
described herein are adaptable for use in a variety of
applications, including single chamber atrial or ventricular
pacing, dual chamber (atrial and ventricular) pacing, bi-atrial
pacing for the suppression of atrial fibrillation, bi-ventricular
pacing for heart failure patients, cardioversion for ventricular
tachycardia, ventricular defibrillation for ventricular
fibrillation, and atrial defibrillation. The system may be adapted
to perform multiple functions for use in combinations of these
applications. The system may be implanted for permanent use, or it
may be implanted for temporary use until more permanent
interventions can be used.
[0035] In general, the system is responsive to fast and/or
irregular heartbeats detected using sensing electrodes positioned
on the device body and/or leads. Typically, at least two primary
sensors will be positioned across the heart so as to provide a
macroscopic view of the electrical activity of the heart. Common
locations for these primary sensors will include a position below
the heart such as the inferior vena cava, and a position above the
heart such as the superior vena cava or the left subclavian vein.
Data obtained from these sensors may be optionally supplemented
with localized data from more closely spaced sensors at particular
areas of interest, such as the right atrium. This data can bring
into focus the nature of the abnormal activity detected by the
primary sensors, and can allow the system to be programmed to
differentiate between electrical activity requiring delivery of
corrective defibrillation or pacing pulses, and electrical activity
that can resolve without intervention.
[0036] The system should be programmed to deliver sufficient energy
to disrupt the aberrant electrical activity and restore the heart
to its normal rhythm. Energy pulses of approximately 1 J to 50 J
may be used for ventricular defibrillation, whereas pulses in the
range of 0.1 J to 40 J may be needed for atrial defibrillation.
Pacing pulses may be delivered in the range of 0.1 to 10 Volts,
with 0.1 to 2.0 millisecond pulse widths. The system may be
programmed to deliver a specific amount of energy or to determine
the appropriate energy level. Generally speaking, the system may be
implanted to include electrodes in any vessel and/or chamber of the
heart arranged to distribute energy through the heart in a manner
sufficient to control the aberrant electrical activity of the
heart.
[0037] An enclosure device in accordance with various embodiments
of the present invention can be implanted using any of a number of
implantation techniques. Many of these implantation methods are
preferably carried out under fluoroscopic visualization. Although
various methods described herein introduce the device into the
venous system via the femoral vein, the device and components may
alternatively be introduced into the venous system via that
subclavian vein or the brachiocephalic veins, or into the arterial
system using access through one of the femoral arteries. Moreover,
different components of the intravascular systems may be introduced
through different access sites. For example, a device may be
separately introduced through the femoral vein and a corresponding
lead may be introduced via the subclavian vein.
[0038] One such technique will be described with respect to FIGS.
6(a)-6(f) for implanting the device of FIG. 5. First, a small
incision is formed in the femoral vein and an introducer 604 is
inserted through the incision into the vein to keep the incision
open during the procedure. Next, the device 606 is passed into the
introducer 604, and pushed in a superior direction through the
inferior vena cava 602 ("IVC"), through the right atrium 614
towards the superior vena cava 600 ("SVC"). With an end of the
device 606 still remaining outside the body, mandrel 612 and lead
616 are attached to the exposed end of the device 606 as shown in
FIG. 6(b). Pressure is applied against the mandrel 612 to advance
the device 606 into the left subclavian vein ("LSV") 610.
[0039] Referring to FIG. 6(c), once the device 606 is in the target
position, the anchor 618 is expanded into contact with the walls of
the inferior vena cava 608. The anchor can self-expand and/or be
expanded using an inflation tool, such as a balloon passed into the
anchor's central lumen and subsequently inflated. When the anchor
is expanded, the radial force engages the device 606 and secures
the device 606 against the vessel wall. The mandrel 612 then can be
detached from the device 606 and removed from the body.
[0040] A steerable guidewire or stylet 620 can be attached to the
free end 622 of the lead 626 or inserted into a lumen in the lead
626, which can be used to carry the free end 622 of the lead
through the introducer 604 and into the IVC 602, such that the lead
616 folds over on itself as shown in FIG. 6(e). The free end 622 is
steered into the right ventricle 624 ("RV") using the stylet 620,
and is fixed in place using a helical screw member at the free end
622 or another attachment feature. The stylet 620 then can be
removed, leaving the lead 626 positioned in the right ventricle 624
as shown in FIG. 6(f). As an alternative, the free end 622 of lead
626 can be steered into the middle cardiac vein.
[0041] It should be pointed out that many of the device
configurations, components, retention devices and methods,
implantation methods and other features are equally suitable for
use with other forms of intravascular implants. Such implants might
include, for example, implantable neurostimulators, artificial
pancreas implants, diagnostic implants with sensors that gather
data such as properties of the patient's blood (e.g. blood glucose
level) and/or devices that deliver drugs or other therapies into
the blood from within a blood vessel. More particularly, fully
implantable intravascular systems may be used for administering
drugs including hormones, chemotherapeutic agents, pharmaceuticals,
synthetic, recombinant or natural biologics, and other agents
within the body. Generally speaking, the systems include drug
reservoirs and associated components (e.g. batteries, electronics,
motors, pumps, circuitry, telemetric components, sensors) that are
anchored in the vasculature and programmed to administer drugs into
the bloodstream or directly into certain organs or tissues. Drug
delivery microtubules may extend from the device body and into
surrounding vessels in a similar way that the leads in the
embodiments described above extend from the device body. These
microtubules may be positioned within the vasculature to deliver
drugs directly into the bloodstream, and/or they may extend from
the device through the vascular into or near a body organ. For
example, by directing drugs to a particular aortic branch (e.g.
hepatic artery, renal artery, etc), an intravascular delivery
device can achieve target delivery of therapeutic drugs to specific
organs including the brain, liver, kidneys etc.
[0042] In some embodiments, such intravascular drug delivery
systems may be controlled remotely using telemetry or via internal
intelligence that may be responsive to in-situ sensing of
biological, physical or biochemical parameters.
[0043] It also should be pointed out that, although the embodiments
have been described in the context of intravascular implants,
alternative embodiments may be used to house medical devices
implanted elsewhere in the body, including subcutaneous pockets,
body organs, or other body cavities.
[0044] Various embodiments of systems, devices and methods have
been described herein. These embodiments are given only by way of
example and are not intended to limit the scope of the present
invention. It should be appreciated, moreover, that the various
features of the embodiments that have been described may be
combined in various ways to produce numerous additional
embodiments. Moreover, while various materials, dimensions, shapes,
implantation locations, etc. have been described for use with
disclosed embodiments, others besides those disclosed may be
utilized without exceeding the scope of the invention.
[0045] All prior applications and patents referred to herein,
including for purposes of priority, are incorporated herein by
reference.
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