U.S. patent application number 12/423605 was filed with the patent office on 2009-08-06 for intravascular medical device.
Invention is credited to Kenneth M. Anderson, Charles L. Dennis, Ursula Gebhardt, George J. Klein, Glenn C. Zillmer.
Application Number | 20090198295 12/423605 |
Document ID | / |
Family ID | 38323086 |
Filed Date | 2009-08-06 |
United States Patent
Application |
20090198295 |
Kind Code |
A1 |
Dennis; Charles L. ; et
al. |
August 6, 2009 |
Intravascular Medical Device
Abstract
An implantable medical device is configured so that all of the
major components including a housing and attached leads are
disposed within the vasculature of a patient. A tether extends from
the housing of the device to an implant location where the tether
is secured to tissue outside of the vasculature. In this manner, an
intravascular medical device may be implanted at a location remote
from final placement, delivered via the vasculature and anchored at
the initial entry point.
Inventors: |
Dennis; Charles L.; (Lake
Elmo, MN) ; Klein; George J.; (London, CA) ;
Gebhardt; Ursula; (Sint Lambrechts Woluwe, BE) ;
Anderson; Kenneth M.; (Bloomington, MN) ; Zillmer;
Glenn C.; (Hudson, WI) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MINNEAPOLIS
MN
55432-9924
US
|
Family ID: |
38323086 |
Appl. No.: |
12/423605 |
Filed: |
April 14, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11342734 |
Jan 30, 2006 |
7519424 |
|
|
12423605 |
|
|
|
|
Current U.S.
Class: |
607/4 ; 606/129;
607/36; 607/5 |
Current CPC
Class: |
A61N 1/372 20130101;
A61N 1/37205 20130101 |
Class at
Publication: |
607/4 ; 607/36;
607/5; 606/129 |
International
Class: |
A61N 1/39 20060101
A61N001/39; A61N 1/375 20060101 A61N001/375; A61B 17/00 20060101
A61B017/00 |
Claims
1. An intravascular medical device (IVMD) comprising: an
intravascular housing having a proximal end and a distal end; a
circuit configured to operate the IVMD contained within the
housing; a first lead coupled with the distal end and having a
fixation member at a distal end of the lead; and an elongated
tether coupled with the proximal end of the housing.
2. The IVMD of claim 1 further comprising: an electrode disposed
along the tether and electrically coupled to the housing through
the tether.
3. The IVMD of claim 1, further comprising: an antenna coupled to
the circuit through the proximal end of the housing and attached to
the tether.
4. The IVMD of claim 3, wherein the antenna is disposed within the
tether.
5. The IVMD of claim 1, wherein the tether further comprises a
tether lumen extending through an entirety of the tether.
6. The IVMD of claim 5, wherein the housing further comprises a
housing lumen extending through the housing wherein the housing
lumen is coaxially aligned with the tether lumen.
7. The IVMD of claim 6, wherein the lead further comprises a lead
lumen extending through at least a portion of the first lead and
the lead lumen is coaxially aligned with the housing lumen.
8. The IVMD of claim 1, further comprising a second lead coupled
with the distal end of the housing.
9. The IVMD of claim 8, further comprising: a first tether lumen
extending through the tether; a first housing lumen extending
through the housing: a first lead lumen extending through the first
lead; and a second lead lumen extending through the second
lead.
10. The IVMD of claim 1, further comprising a tether anchor
coupleable with a proximal end of the tether.
11. The IVMD of claim 10, wherein the tether anchor is a T-shaped
member including at least one suturing location.
12. The IVMD of claim 10, wherein the tether anchor is a malleable,
arcuate member having a rod depending from a concave surface,
wherein the proximal end of the tether is coupleable to the
rod.
13. The IVMD of claim 1, wherein the IVMD is a pacemaker.
14. The IVMD of claim 1, wherein the IVMD is a defibrillator.
15. The IVMD of claim 1, wherein the IVMD is a pacemaker and a
defibrillator.
16. The IVMD of claim 1, wherein the housing has a diameter of
approximately 6-7 French.
17. An intravascular medical device, comprising: a housing
deployable within a vascular structure; means for delivering a
therapy; means for securing the housing within the vasculature to a
site exterior to the vasculature.
18. An intravascular medical device (IVMD) system comprising: a
housing deployable within a vasculature structure; means for
delivering therapy; means for securing the housing within the
vasculature to a site exterior to the vasculature; and means for
delivering the housing to an implant location within the vascular
structure.
19. The IVMD system of claim 18, wherein the means for securing
include a tether having a lumen and the means for delivering
include a stylet configured for insertion through the lumen to
direct movement of the housing.
20. The IVMD of claim 18, wherein the means for delivering include
a stylet having means for engaging an exterior of a lead coupled
with the housing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 11/342,734 filed on Jan. 30, 2006 and entitled "Intravascular
Medical Device".
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to medical devices and in
particular, implantable medical devices.
[0004] 2. Description of the Related Art
[0005] Medical devices related to managing, treating and providing
therapy for cardiac conditions have changed and improved
dramatically since their inception. Cardiac pacing, as an example,
originally required an external pulse generator that itself
required external power. While providing life sustaining therapy,
patients were tethered to the power source and of course, power
failures could prove catastrophic. Portable, battery powered
external pulse generators were developed and provided the patient
with the ability to be ambulatory; however, the pulse generator had
to be carried by the patient. Furthermore, pacing leads were
exposed through the patient's tissue and extreme care had to be
exercised to minimize the risk of infection or inadvertent
withdrawal.
[0006] Subsequently, fully implantable, battery powered pulse
generators were provided in a hermetically sealed housing. This
housing was rather large and was typically implanted in the abdomen
of the patient, with leads extending to the heart. The size of such
a device often made it rather uncomfortable and the implantation
procedure was relatively invasive.
[0007] As technology improved, implantable medical devices (IMDs)
have become continuously smaller, while offering increased
longevity, reliability and many more features and therapies.
Epicardial leads that were attached to an external wall of the
heart were replaced with endocardial leads that are implanted
transvenously, thus becoming minimally invasive. With these smaller
devices, the housing was no longer placed in the abdomen but
instead was implanted subcutaneously or sub-muscularly, often in
the pectoral region. A "pocket" is formed underneath the skin or
muscle sufficiently large to receive the housing of the IMD. The
exposed or proximal ends of the leads are then connected to the
housing and the incision is closed. While now routine, this is
still a surgical procedure that requires skill and the appropriate
medical facilities.
[0008] In general, patients are comfortable with these implanted
devices and have a full range of motion, without interference or
hindrance. Some patients feel the housing in the "pocket," which
may be physically and/or psychologically uncomfortable. Physically,
some patients may press against the housing during certain physical
activities making the housing noticeable. Even if not a hindrance
or painful, simply "feeling" the presence of the device may remind
that patient that they have a medical implant and/or medical
condition and this alone may be troubling to that patient. Some
patients develop a habit of pressing against the pocket and hence
against the IMD and often rotating or twisting the IMD. Typically,
IMDs that have one or more leads will have any excess lead length
coiled under (or around) the housing of the IMD. Thus, frequent
patient manipulation may cause portions of the lead(s) to twist or
rub, potentially damaging the lead body or pulling the lead out of
contact with the targeted tissue. This is sometimes referred to as
"twiddlers syndrome."
[0009] As the size and capability of IMDs has greatly improved, use
of these devices has naturally expanded. This results in greater
knowledge and acceptance among the patient population as well as
within the medical community. As a result, caregivers are using
IMDs with more frequency and for new and diverse purposes. For
example, pacemakers are used in patients with various
bradyarrhythmias. In such a patient, the heart's intrinsic pacing
function fails or is deficient and the IMD provides electrical
stimulation to maintain the proper heart rhythm. Such therapy is
well known and is referred to above with the early, external pulse
generators. Recently, the medical community has been using pacing
technology in patient's whose heart rhythm is actually normal.
Heart failure patients often have normal rhythm and conduction;
however, this disease causes the heart to enlarge. As a result the
left and right ventricles are unsynchronized when they contract
even though the depolarization waveform triggering such a
contraction was "timed" properly. Using cardiac resynchronization
therapy (CRT), the left and right ventricles are paced, leading to
a mechanical "resynchronization" of the left and right ventricular
contractions. This not only leads to better immediate hemodynamic
performance, but the heart itself often remodels itself (reducing
in size) leading to an improvement in the disease state.
[0010] Not only are new therapies and treatments developing,
implantable devices are now being used to collect sensor data for a
variety of purposes. For example, implantable loop recorders (ILRs)
are implanted subcutaneously and record cardiac data,
unobtrusively, for extended periods of time. This allows robust
medical data to be collected that, as a practical matter, may be
otherwise unattainable.
[0011] These are merely two examples that illustrate the ever
increasing trend to beneficially use implantable medical devices
with greater frequency and for a wide variety of purposes that
extend well beyond cardiac care. This presents a challenge to some
caregivers who might want to use a given device for their patient
but do not have the necessary surgical qualifications to actually
implant the device. While such a patient may always be referred to
another doctor, this adds cost and burden, some patients may not
follow through, and some caregivers may simply opt for other
treatments in order to maintain their relationship with the
patient.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic illustration of selected internal
components of an intravascular medical device (IVMD) consistent
with the teachings of the present invention.
[0013] FIG. 2 is a schematic illustration of the IVMD including a
tether and a lead.
[0014] FIG. 3 illustrates an electrode incorporated into the
tether.
[0015] FIG. 4 illustrates an IVMD having multiple leads.
[0016] FIG. 5 is a sectional view of a housing of the IVMD.
[0017] FIGS. 6A-6B illustrate an IVMD having a lead and the tether
coupled to a common end of the housing.
[0018] FIGS. 7A-7 illustrate a system for deploying the lead and
housing.
[0019] FIGS. 8A-8D illustrate an IVMD having a tether with a
lumen.
[0020] FIGS. 9A-9D illustrate an IVMD having a tether with a lumen
coaxial with a lumen through the housing and an attached lead.
[0021] FIGS. 9A-9D illustrate multiple lumens.
[0022] FIG. 10 illustrates a housing having multiple housing
portions.
[0023] FIGS. 11A-11B illustrate multiple housing components with a
common tether.
[0024] FIGS. 12A-12D illustrate a mechanism to attach a stylet to a
housing component.
[0025] FIGS. 13A 13B illustrate an IVMD with multiple housing
portions.
[0026] FIG. 14 illustrates an IVMD having multiple housing potions
and multiple tethers.
[0027] FIG. 15 illustrates an interaction of a stylet with both
tethers of FIG. 14.
[0028] FIG. 16 illustrates an IVMD with multiple housing
portions.
[0029] FIG. 17 illustrates an implanted IVMD.
[0030] FIG. 18 illustrates the anatomical relationship between the
subclavian vein and the clavicle.
[0031] FIG. 19 illustrates the anatomical location of the cephalic
vein.
[0032] FIG. 20 illustrates an IVMD implanted in the superior vena
cava having an auxiliary support member further anchoring the
lead.
[0033] FIG. 21A-21J illustrate the insertion and anchoring of an
IVMD.
[0034] FIGS. 22A-22B illustrate a tether anchor.
[0035] FIG. 23 is a flowchart describing a process for implanting
an IVMD.
DETAILED DESCRIPTION
[0036] FIG. 1 illustrates an exemplary intravascular medical device
(IVMD) 10. The IVMD 10 is an implantable medical device that
includes a hermetically sealed housing 12 containing components 18
to control, power, and operate the device. The housing 12 is shaped
and configured to reside entirely within the vasculature anatomy or
within a given organ (e.g., the heart, lungs, kidney, pancreas,
etc.) via the vasculature. In one embodiment, the housing 12 has an
approximate diameter of 6-7 French. The IVMD 10 may have any number
of functional areas including sensing, diagnostic, communications
and therapy delivery. In the illustrated example, the IVMD 10
includes cardiac sensing, pacing and defibrillation as well as the
ability to communicate with an external device through
telemetry.
[0037] The housing 12 includes a proximal header 16 and a distal
header 16. The operative components 18 include a power source 20,
such as a battery. One or more capacitors 22 are provided that
allow charge to be accumulated for rapid discharge to deliver a
defibrillation or cardioversion pulse. A pulse generator 26 is
coupled to the power source 20 and provides electrical stimuli for
cardiac pacing.
[0038] A microprocessor 24, memory 36 (flash, EEPROM, ROM, RAM,
DRAM, harddisk, etc.), analog to digital converter (A/D) 30, analog
signal processor 28, and digital signal processor (DSP) 32 are
positioned within the housing 12. An externally actuated switch 42
is provided and may take the form of a reed switch that is closed
by a magnet. Such a switch 42 may be used to initiate a telemetry
session with IVMD 10.
Alternatively, communication may be initiated directly by an RF
signal or other appropriate transmission medium. A telemetry module
34 provides the ability to transmit and receive data. A reservoir
35 is optionally included. The reservoir may provide a supply of a
deliverable drug (e.g., insulin), genetic material, or biologic.
The IVMD 10 may provide for the release of the material on a given
schedule or based upon sensed need. Some materials, such as
insulin, may be dispersed as needed but are predictably used; that
is, the likelihood of delivery over a given time period is high.
Other material may be delivered on an acute basis. For example, a
dose of a blood thinner, coagulant, anti-coagulant, or adrenaline
is provided and released when necessitated.
[0039] An accelerometer 40 may be utilized to provide an indication
of patient activity for a rate response function and/or a relative
position indicator; that is, physical position of the patient
(e.g., prone). Finally, a sensor array 50 is illustrated. The
sensor array 50 may sense any number of parameters such as
temperature, pressure, velocity or other fluid flow
characteristics, impedance, motion or size (e.g., ultrasound for
wall motion and/or chamber size), oxygenation, glucose, or the
level of any sensed chemical substance. It should be appreciated
that while illustrated as contained within the housing 12, the
sensor array 50 may have appropriate external portions not shown.
For example, if used as a pressure sensor, a transducing membrane
will form a part of housing 12 or part of a lead coupled with the
housing 12, either physically or through telemetric connection
(e.g., a body bus). Likewise, any additional component(s) for
sensor array 50 will be included in this manner, as required.
Cardiac data (e.g., electrogram (EGM)) will be sensed via one or
more leads as explained below. In addition, the housing 12 may
include one or more electrodes incorporated into the structure of
the housing 12 (i.e., an active "can").
[0040] As indicated the power source 20 may be a single use
battery. Alternatively, the battery may be rechargeable. As such,
an optional recharging module 25 is illustrated. The recharging
module 25 may receive power from an external source, such as
directed RF energy, which is converted and used to recharge the
battery 20. The RF energy may be collected via one or more antenna
as discussed below, by using the housing 12 as an antenna, or by
incorporating a receiver into the housing 12. Alternatively, or in
addition, the recharging module 25 may use other mechanisms to
generate power. In one embodiment, heat from within the patient is
converted into current. In another embodiment, chemical energy from
cells proximate the implant location is converted into electrical
energy by the charging module 25. The charging module 25 may
convert body motion into electrical energy. Such motion may come
from multiple sources including without limitation gross patient
movement (walking, exercising, etc.), lung motion (breathing),
cardiac contractions, vasculature contraction (pulsitile blood
flow), or fluid flow. The length of the unit provides the ability
to harness mechanical power at one or more flexation points. Such
flexation points may occur along the tether and/or in-between
housing components. In this context, mechanical motion is converted
into electrical energy by various mechanisms such as movement of a
magnetic member within a coil. The charging module 25 may also used
photovoltaic conversion to generate electrical current. A light
collected placed sufficiently close to the surface of the patient's
tissue will receive enough ambient light to provide power. Various
other techniques are available to recharge the battery and are
considered to be within the spirit and scope of the present
invention. The following documents are herein incorporated by
reference in their entirety: U.S. Pat. No. 6,242,827, issued to
Wolf et al. on Jun. 5, 2001; U.S. Pat. No. 6,768,246, issued to
Pelrine et al. on Jul. 27, 2004; US Published Application
2004/0073267, published on Apr. 15, 2004; and US Published
Application 2004/0158294 published on Aug. 12, 2004.
[0041] The module 25 has been described in conjunction with a
traditional rechargeable battery 20 as a mechanism to recharge that
battery. It should be appreciated that to conserve space, the
traditional battery 20 may be eliminated or greatly reduced in size
(due to a decrease in reliance upon the battery). That is, the
various mechanisms described to generate electrical energy from
sources around the IVMD 10 may be used to directly power the IVMD
10, without first storing that energy in a battery. This concept is
applicable to any of the various forms the IVMD 10. In one
embodiment, providing power directly from module 23 is utilized
when the IVMD has low or minimal power consumption requirements
(e.g., periodic sensing). Thus, power is generated for internal
operations and when communication is desired, external power is
provided for e.g., telemetry functions, through inductive coupling
or RF power transmission. Of course, the IVMD 10 may be completely
dependant upon such power conversion for all of its functionality.
Finally, as indicated, a smaller battery or capacitor may be
provided to collect some amount of energy prior to use; either to
mitigate against fluctuation in the source (e.g., movement stops
for a period of time) or to provide an even power supply to
mitigate against power fluctuations; that is, to provide a
relatively stable DC source.
[0042] FIG. 2 illustrates a lead 60 coupled with the distal header
16. One or more electrodes are incorporated into the lead 60. As
illustrated, lead 60 includes a helical affixation member 64 that
allows penetration into tissue to secure the distal portion of the
lead 60 at a specific site. The helical affixation member 64 may
serve as an electrode and/or the distal end of the lead 60,
proximal to the helical member 64, acts as an electrode. A coil
electrode 62 is positioned proximal to the distal end of the lead
60 so that when implanted, the coil electrode creates a
defibrillation vector through an appropriate cardiac path with
another electrode of the IVMD 10. The length of the lead 60 and the
relative position of the electrodes are selected based upon the
type of therapies, sensing and diagnostics provided and the implant
location of the housing 12. The lead 60 may have other functions
instead of or in addition to electrical stimulation or sensing. For
example, a number of non-electrical parameters (e.g., pressure,
temperature, velocity, chemical presence/concentration, etc.) may
be sensed by providing an appropriate sensor. The lead 60 may have
a delivery device to deliver drugs, genetic material, or biologics
from the reservoir 35. Such a delivery device may include a needle
65a for delivery into tissue; a disbursing tip 65b (e.g., a porous
surface for release into a fluid supply or against a larger surface
area); or a variety of other delivery mechanisms.
[0043] The lead 60 is connected to the distal header 16. The
connection may be a permanent, integral formation. That is, the
lead 60 and housing 12 are fabricated to form an integral unit or
the lead 60 is permanently affixed to the housing 12.
Alternatively, the lead 60 is separable from the housing 12, as
explained below. As used throughout, the designations proximal and
distal header 14,16 are used to indicate particular portions of the
housing 12. It should be appreciated, that these portions may
include a header in the traditional sense of an implantable medical
device. That is, a separate portion from the remainder of the
housing that includes various connection mechanisms (e.g., for
receiving a lead connector pin). Alternatively, the terminology may
simply refer to a given end or portion of the housing 12 to
facilitate description.
[0044] A flexible tether 70 extends from and is securely coupled to
the proximal header 14. At a proximal end 74, the tether 70 has an
anchoring point. In the illustrated embodiment, a T-shaped anchor
member 76 is attached to the tether 70 at the anchoring point. The
anchor member 76 includes one or more suture ports 78 extending
through the member 76. As indicated, IVMD 10 is implanted
transvenously and the entire housing 12 resides within the
vasculature or within an organ accessed via the vasculature. The
tether 70 extends from the implanted location of the housing 12,
through the vasculature and is anchored at or near the vasculature
incision or puncture created for implantation. Thus, the tether 70
will fully or partially maintain the position of the IVMD 10. For
example, if implanted in the superior vena cava, with a pacing lead
60 extending from the housing 12 into a cardiac chamber, blood flow
and gravity (generally) will provide force against the housing 12
in a direction towards the heart. With the anchor point fixed, the
housing 12 is prevented from traveling towards the heart and is
thus secured. While suturing has been discussed, other methods of
attaching or anchoring the tether 70 and/or the anchor 76 may be
utilized.
[0045] The anchoring point 74 allows for subsequent identification
and access to the IVMD 10. That is, if the IVMD is replaced or
modified, the anchoring point 74 is located and the IVMD 10 can be
accessed or removed via the tether 70 along the same vasculature
pathway. As such, the anchoring point 74 may optionally include a
radiopaque marker, may be constructed of a biocompatible metal, or
having other identifying mechanisms to aid in determining the
location of the anchor point 74 at a later time via X-ray, MRI, or
other imaging techniques. Alternatively, the anchor point 74 may be
positioned sufficiently close to the surface of the patient's skin
that its location may be felt by applying pressure to the area.
[0046] The tether 70 is intended to secure the position of the IVMD
10 during the life of the implant. Accordingly, the tether material
is constructed of a suitably strong, flexible, biocompatible
material. The length of the tether 70 may include a drug eluting
surface along the entire exterior, a portion of the exterior, or
multiple distinct drug eluting surfaces may be provided. In some
embodiments, the tether 70 may be used to temporarily secure the
IVMD 10 until another anchoring mechanism is enacted (e.g.,
fibrotic growth). In yet another alternative embodiment, the IVMD
10 is intended to degrade within the body or pass harmlessly out of
the body. For example, IVMD 10 may be a chemical sensor and the
tether 70 secures the IVMD 10 at an appropriate location within the
vasculature, counteracting the forces of pulsitile blood flow.
Eventually, the sensor will dissolve and in such an embodiment, the
tether 70 could likewise dissolve. Of course, the tether 70
provides a convenient mechanism to remove any such device thus
providing for temporary implantation of a variety of medical
devices, including pacemakers and defibrillators.
[0047] The tether 70 is provided with an excess length. After
implantation of the lead 60 and housing 12, the desired length of
tether 70 is determined. This final length should include enough
excess to allow for normal movement of the housing 12 within the
vasculature as well as any variations that will occur due to
patient movement, positioning, growth or other physiological
variations. The tether 70 is then cut at the appropriate location
and anchored into place. The T-shaped anchor member 76, if used, is
attached to the cut tether 70, either by suturing, mechanically
clamping or using any other secure coupling mechanism.
[0048] As indicated, excess tether length is provided at the
proximal end of the tether 70 with an expectation that this excess
will trimmed or remain unused. This allows for flexibility during
implantation and minimizes the need to have multiple pre-configured
devices to accommodate different patient sizes and implant
locations. Conversely, a distal portion of the tether 70 will
reliably remain intact. Thus, this portion of the tether 70 may be
used to provide additional structure or functionality.
[0049] As illustrated in FIG. 2, an antenna 72 extends from the
housing 12 and may be contained within or affixed to an outer
portion of the tether 70. Including the antenna 72 within the
tether 70 provides a hermitic enclosure for the antenna 72 and any
exposed feedthrough. The length, size, shape and configuration of
the antenna 72 may vary from the illustrated embodiment and may
extend for a relatively long length as compared to traditional
implantable medical devices. The antenna 72 may be used for
communication and/or as an RF collector to receive power to
recharge the power source 20. Furthermore, while one antenna
structure 72 is illustrated, multiple antennas may be provided to
facilitate different types of communication; to have a different
antenna for transmission versus reception; to provide a separate
power collector, to provide low and high power communication
formats, to provide redundancy or for any number of reasons. One or
more antennas may also be included in the lead body 60.
[0050] FIG. 3 illustrates an alternative embodiment, wherein a
distal portion 80 of the tether 70 functions as a lead having an
electrode 82 for sensing or stimulation. That is, the electrode 82
is electrically coupled to the housing 12 via the distal portion 80
of the tether 70. This electrical coupling may be completely
internal to and distinct from the tether 70 so that the mechanical
properties of the tether 70 may be relied upon without adding
stress or strain to what would be considered a lead body. The
electrodes 62 and 82 may be positioned to facilitate defibrillation
across the vector defined. In another embodiment, the electrode 82
acts as a pacing electrode. In yet another embodiment, element 82
is a sensor such as a pressure sensor. The antenna 72 of FIG. 2 is
not illustrated, though such an antenna may also be provided when
the tether 70 includes one or more electrodes and/or sensors. The
structure of the tether 70 may vary over its length. The distal
portion 80 is not intended to be severed. The proximal portion, in
one embodiment, is intended to be severed; thus, a transition point
84 may be present. The tether 70 may have different materials and
different construction from one portion to another or may have a
unitary construction throughout.
[0051] FIG. 4 illustrates an embodiment having lead 60 and lead 100
extending from the distal header 15. The second lead 100 is
illustrated as having a tined tip 110 for securement as well as a
tip electrode 112 and ring electrode 114. FIG. 4 is meant to
illustrate that multiple leads may depend from the distal header 16
and a variety of electrode and attachment (e.g., tines, helical
tip) configurations may be employed. The use of two such leads is
not meant to be limiting and any number of additional leads may be
provided. Though not illustrated, one or more additional electrodes
may be present on tether 70, as illustrated in FIG. 3.
[0052] FIG. 5 illustrates a sectional view of housing 12. In
particular, multiple connection ports 150, 152, 154 and 156 are
illustrated in the proximal and distal headers 14, 16. Port 150
includes a cavity 160 shaped to receive a male connecting pin from,
e.g., a lead. A set screw 162 is positioned to advance into the
cavity 160 and engage the connecting pin, thus securing the pin in
place. Access to the set screw 162 is gained through a set screw
opening 165 that may include a self sealing material, such as
silicone to reduce fluid entry into the set screw opening after
implantation. The configuration of port 150 is repeated in each of
the illustrated ports 152, 154 and 156. More or fewer ports may be
provided as necessary and alternative configurations may be
employed. When used to received and secure a lead 60, the lead pin
will make contact with one or more electrical connectors disposed
within cavity 160. The tether 70 may also include a connector pin
thus allowing for connection to the housing 12 in the same manner
as a lead. Of course, if the tether 70 includes electrode(s),
antennas or other components appropriate electrical contact is made
via the pin and cavity. In the absence of such components, the
tether is simply mechanically secured within the port 154, 156. As
indicated, the tether 70 may be integrally formed with the proximal
header 14, thus appropriate access to ports 154, 156 (if provided)
is facilitated by the configuration of the tether 70 or by
providing access through a portion of the tether 70.
[0053] FIGS. 6A and 6B illustrate an alternative multiple lead
configuration. In this embodiment, lead 60 is coupled with the
distal header 16. A second lead 100' is coupled with the proximal
header 14 as is the tether 70. In some applications, it may be
desirable to have the second lead 100' extend in the same direction
as the tether 70, and as such, connection to the proximal header 14
is straight forward. Alternatively, and as illustrated, the lead
100' is extended in the same direction as the first lead 60 (i.e.,
distal to the housing 12). When coupled with the proximal header
14, the lead 100' is bent to achieve this configuration. While this
is non-problematic for the lead 100', movement of the housing 12
via the tether 70 (e.g., retracting the housing 12) may be more
difficult. To permit and facilitate such movement, the lead 100' is
bent to provide sufficient excess so that the housing 12 may move
relative to the lead 100' without affecting the tip placement. It
should be appreciated the lead 60, extending from the distal header
16 also includes a certain amount of excess to address normal
movement of housing 12 caused by pulsitile blood flow as well as
some movement caused by withdrawal or retraction of the tether
70.
[0054] The curvature in the lead 100' may simply be imparted during
implant, with the housing 12 remaining separate from the lead 100'
other than at the proximal header 14. Alternatively, as illustrated
in FIG. 6B, a guide member 180 may be provided on an outer portion
of the housing 12. The lead 100' passes through the guide member
180 maintaining the lead 100' in close proximity to the housing
despite the imparted curvature and any resulting bias. In addition,
by appropriately sizing the guide member 180 and providing a
material with a low coefficient of friction (e.g., parylene,
silicone) on the guide member 180 and/or the lead 100', the housing
12 may be slid relative to the lead 100'.
[0055] For clarity, lead 60 is not shown in FIG. 6B. It should be
appreciated that more than one lead may be coupled to the proximal
header 14 in the manner illustrated. Furthermore, even if a single
lead is employed, that lead may be coupled as illustrated by the
lead 100' in FIGS. 6A and 6B. This would allow all connections to
be made at one end of the housing 12 while still permitting lead
advancement in a direction opposite to that of the tether 70.
[0056] FIGS. 7A and 7B illustrate a system including a device that
will aid in positioning any of the illustrated leads as well as the
housing 12. A steerable stylet (or catheter) 200 has a handle
portion 202 at a proximal end that includes controls that cause the
stylet to flex or bend to facilitate intravascular navigation. A
releasable clamping member 210 is positioned at or near a distal
end of the stylet 200. The clamping member is illustrated
schematically in FIG. 7B as a sectional taken about the line A-A of
FIG. 7A. Upon actuation of the handle portion 202, the clamping
member 210 opens and closes pivoting arms 212 so that lead 100' (or
tether 70) is gripped or released. In this manner, the lead 100' is
directed to a target location and the clamping member 210 is
opened, releasing the lead 100'. It should be appreciated that the
stylet 200 could be navigated as an over the wire catheter, thus
following a previously positioned guidewire. The clamping of the
lead 100' would remain the same; however, the stylet/catheter 200
would be guided by the guide wire as opposed to being navigated
independently. As indicated, such a device may be used to position
leads coupled with either the proximal head 14 or the distal header
16 and may be used to position the housing 12. To position the
housing 12, the clamping member may be secured to a portion of an
attached lead or to the tether 70. Implantation in this manner will
be facilitated if the clamping occurs relatively close to the
housing 12. Alternatively, a lead extending from the distal header
16 may be gripped at any position distal to the housing 12, so that
advancement of the lead with stylet 200 advances the housing 12 as
well.
[0057] FIGS. 8A-8D illustrate another embodiment wherein a
steerable stylet 250 is used to position the housing 12. FIG. 8C is
a sectional view taken about the line A-A in FIG. 8A and FIG. 8D is
a sectional view taken about the line B-B in FIG. 8A. In this
embodiment, the tether 70 has a lumen 254 sized to receive the
stylet 250. While the T-anchor 76 is illustrated as being coupled
with the tether 70, it should be appreciated that the T-anchor 76
may be attached afterwards and hence is not utilized with the
stylet 250 or the T-anchor 76 includes a throughbore that aligns
with the lumen 254, thereby permitting passage of the stylet 250.
In this embodiment, an abutment 252 is provided on an exterior of
the housing 12, as part of proximate header 14. Thus, as the stylet
250 extends through the lumen 254, the tip of the stylet 250 will
eventually reach and strike the abutment 252. Continued advancement
of the stylet 250 will cause advancement of the housing 12 within a
vasculature pathway. If advanced too far, the tether 70 may be
retracted, thus retracting the housing 12. As such, the housing 12
may be implanted at a target location by using the stylet 250 for
forward advancement of the housing 12 and the tether 70 for any
necessary retraction. Leads (not shown in these figures) may be
implanted with the stylet 200 previously described or similar
mechanisms, if utilized. FIG. 8C also illustrates how the antenna
72 (if included) is positioned outside of the path defined by lumen
254, which is congruent with abutment 252.
[0058] FIGS. 9A-9D are similar to FIGS. 8A-8D. In this embodiment,
the lumen 254 extends through the housing 12 as well as the lead
60. Thus, the stylet 250 may be advanced all the way through the
tether 70, the housing 12 and the lead 60 until it abuts an end of
the lead 60. Thus, navigation of the stylet 250 will direct the
distal end of e.g., lead 60 which pulls the housing 12, ultimately
positioning that component as well.
[0059] FIGS. 9E-9H illustrate an embodiment having multiple lumens
254a, 254b through tether 70, housing 12 and lead(s) 60, with the
second lead not illustrated. In this manner the stylet 250 can be
directed through a specific lumen 254a, 254, to engage a particular
lead separately from another lead. As should be apparent, more than
two lumens 254a, 254b may be provided to permit more than two leads
or other appendages to be directly manipulated by the stylet 250.
Further, the size, spacing and configuration of the lumens 254 may
be varied. In an alternative arrangement, more lumens are provided
through the housing 12 and coupled with a corresponding lead than
are provided through the tether 70. That is, the stylet 250 is
directed through a lumen in the tether 70 and into a larger opening
within the proximal header 14. The tip of the stylet 250 is then
manipulated to manually select from a plurality of lumens each
extending from this opening through the housing 12 to a particular
lead.
[0060] While direct manipulation of the stylet 250 to select a
desired lumen within the housing 12 is one option, alternative
arrangements are available. For example, the tip of the stylet 250
may be sized or shaped to specifically engage only one lumen
through the opening in the proximal header 14. For each such lumen
engaged, the tip may be exchanged or a different stylet 250 may be
utilized. As an example, the largest tip may be inserted through
the common lumen in the tether 70 and will only access the largest
sub-lumen passing through the housing 12. While occluding this
larger opening, the next smaller tip may be utilized, and again a
specific sub-lumen provides the only passage.
[0061] As described, the IVMD 10 may include multiple leads with
each of these leads attached or coupled with the housing 12. Due to
the size and implant location of IVMD 10, particular configuration
of the housing 12 may make attachment of more than two leads
cumbersome. In fact, in embodiments, the use of more than one lead
may be cumbersome. In such a case, the present invention provides
for the use of multiple IVMDs 10, each having one or two leads. The
separate IVMDs 10 are in wireless communication so that their
activities are synchronized. For example, one IVMD may provide
atrial pacing and another may provide ventricular pacing. The
multiple IVMDs 10 may be completely independent and simply
communicate to one another to synchronize timing. Alternatively,
one IVMD 10 may act to control the functions of one or more other
IVMDs. The multiple IVMDs 10 may be implanted through the same
entry point and reside in the same anatomical location or proximate
one another (e.g., both within the superior vena cava but offset
from one another). Alternatively, the multiple IVMDs may be
implanted from different locations and reside remotely from one
another, while retaining wireless communication.
[0062] FIG. 10 illustrates an embodiment wherein housing 12 is
separated into two components 12a, 12b. The housing components 12a,
12b are operatively coupled together with a flexible interconnect
300, which may include one or more wires, cables or fibers for
electrical or data communication. Alternatively, the flexible
interconnect 300 may be a solely a mechanical coupling with each
housing component 12a, 12b operating independently. For example,
each may have separate functions. Alternatively, the housing
components 12a, 12b are mechanically coupled and communicate in a
wireless medium such as RF. Due to their close proximity, they may
also be inductively coupled both for data communication and power
transmission functions. Thus, the flexible interconnect 300 will
mechanically connect the separate housing components 12a, 12b and
may provide electrical, data and/or power couplings. As such, the
flexible interconnect 300 will act like tether 70' as between
housing component 12a and housing component 12b. That is, securing
the proximal end of tether 70' will ultimately retrain housing
component 12b through the flexible interconnect 300.
[0063] FIG. 10 also schematically illustrates a simplified tether
70' as compared to the tether 70 illustrated in previous
embodiments. Simplified tether 70' is a generally linear, flexible
member such as wire or cord and may be monofilament or multi-filar.
The simplified tether 70' could be secured to an anchor member such
as the T-anchor 76, which is then secured to tissue. Alternatively,
the simplified tether 70' could be sutured directly to tissue.
[0064] FIGS. 11A and 11B illustrate another embodiment including
multiple housing components 12a and 12b. As shown, housing
component 12a includes the lead 60 extending from a distal end 16.
The tether 70 extends in an opposite direction from the proximal
end 14. A threaded receptacle 310 is axially aligned with a lumen
254 (FIGS. 8-9) through the tether 70. The second housing component
12b includes a through bore 320 sized to receive the tether 70.
Thus, the housing component 12b may be added to or removed from the
component 12a subsequent to implantation of component 12a.
[0065] The housing component 12a includes one or more receiving
channels 314a, 314b that receive corresponding connector pins 312a,
312b. The engagement of connector pins 312 within channels 314
allows for a mechanical coupling as well as optionally providing
for electrical connection through one or all of the connections.
The connector pins 312 are provided with biased protrusions 316a,
316b received within detents 318a, 318b; thus, locking the
connectors pins 312 into the channels 314 when full inserted.
Initial insertion as well as subsequent release of the connector
pins 312 may require retraction of the protrusions 316 internally
via a mechanism that is not illustrated; thus, providing a secure
locking mechanism. Alternatively, the spring bias of the
protrusions 316 may be overcome by applying sufficient force in an
axial direction. Thus, a locking action is formed that will
maintain the connection of the two housing components 12a and 12b
while implanted, but does not require additional components for
engagement and/or disengagement. It should be appreciated that the
size, shape, location, and configuration of the pins 312 and
channels 314 may be varied in numerous ways while remaining within
the spirit and scope of the present invention.
[0066] In FIG. 11B, housing component 12a is coupled with housing
component 12b. Also illustrated is a stylet 322 having a threaded,
tapered tip 326. The stylet 326 is inserted through the lumen 254
with the tether 70. The stylet 326 is advanced until the tip 326
reaches the threaded receptacle 310. Rotation of the stylet 326
then causes the threaded tip 326 to engage the receptacle 310. Once
so engaged, liner movement of the stylet 322 will correspondingly
move the housing component 12a (and 12b if coupled as illustrated).
Furthermore, once fully engaged, rotation of the stylet in a
clockwise (with standard threading) direction will rotate the
housing component 12a. Use of the stylet 322 in this manner allows
for greater positional control of the housing 12a within the
vasculature. While retraction of the tether 70 allows for gross
movements, the engaged stylet 322 permits more precise movement
which facilitates the attachment or detachment of housing component
12b, among other things.
[0067] In one embodiment, the stylet 322 is advanced through the
tether 70 and threaded into the receptacle 310. The housing
receptacle 12b is then advanced over the tether 70 using another
stylet (see e.g., FIG. 13B) to push the housing 12b. When the
housing components 12a, 12b are proximate one another, stylet 322
is used (alone or in combination with tether 70) to hold housing
component 12a in place and rotate housing component 12a to align
with housing component 12b. When so aligned, the housing components
12a, 12b are joined. It should be appreciated that engagement
mechanisms may be provided between housing member 12a, 12b that do
not require specific alignment. That is, a retaining clip, channel
or other member may extend about the circumference of the header of
one housing component and a corresponding component may extend
circumferentially (fully or partially) about the corresponding
header of the other housing component; thus, relative rotational
positioning between the two housing components is irrelevant to
engagement so long as general axial alignment is provided. For
example, rather than having channel 314 discretely received a
single pin 312, the channel 314 may extend circumferentially around
the proximal planar face of the housing component 12a. Thus, the
pin(s) 312 may be received anywhere along this channel 314.
Relative rotation is permitted even when protrusions 316 and detent
318 (which may also be circumferential) are utilized.
Alternatively, the detent(s) 318 may remain discrete and rotation
of the housing components 12a, 12b will cause engagement.
[0068] FIGS. 12A-12D illustrate another embodiment of stylet 322.
FIGS. 12A-12C are side sectional views of a tip portion of the
stylet 322. Initial engagement of the threaded tip 326 may be made
more difficult since the housing component 12a is relatively free
to rotate when implanted. The stylet 322 in the present embodiment
includes an outer sheath 350 and an inner rod member 352. The
threaded tapered tip 324 retracts and extends from the outer sheath
350.
[0069] One or more pins 340 extend from the outer sheath 350, with
two such pins 340a, 340b illustrated. The pins 340 are sized to
easily engage openings 342 (with 342a and 342b illustrated). It
should be appreciated that more openings 342 may be provided than
pins 340 to again ease initial engagement. As illustrated in FIGS.
12A and 12D, the tip 326 is initially retracted within the sheath
350 and the stylet 322 is spaced from housing 12. The stylet 322 is
advanced until the pins 340 engage the openings 342, as shown in
FIG. 12B. Rotation of the stylet 322 may be necessary to achieve
this engagement. Again, the fit of the pin 340 to the opening 342
need not be particularly tight. Subsequent rotation of the stylet
322 will cause the pins 340 to abut a surface of the openings 342.
Subsequently, the rod 352 may be advanced via control at a handle
360 and rotated so that tip 326 is threaded into the receptacle
310, thus achieving a secure engagement so that subsequent
manipulation of the stylet 322 will directly control the housing
12.
[0070] FIGS. 13A and 13B illustrate another embodiment utilizing
multiple housing components 12a, 12b. In this embodiment, the
tether 70 is coupled with housing component 12a and housing
component 12b is slid over the tether 70. A stylet/catheter 400 is
provided that includes a lumen 410 sized to receive the tether 70.
Thus, the stylet 400 is also slid over tether 70 and is used to
push housing component 12b into engagement with housing component
12a. Though not separately shown, it should be appreciated that the
stylet 400 may be releasably secured to housing component 12b so
that advancement, retraction and rotation of the housing component
12b is facilitated. The manner in which stylet 400 is releasably
secured to housing component 12b may vary and may include without
limitation any of the coupling arrangements discussed herein.
[0071] FIG. 14 illustrates an embodiment of a multi component
housing 12, wherein the distal housing component 12b includes a
supplemental tether 450. The supplemental tether 450 may be
permanent or temporary. In either case, the tether 450 may be used
to retract housing component 12b while a device such as stylet 400
is used to advance the housing component 12b. When permanent, the
supplemental tether 450 may be separately sutured at a distal end
for securement or may simply be affixed to the tether 70.
[0072] FIG. 15 is an embodiment similar to that of FIG. 14. In this
embodiment, the stylet 400 includes an outwardly extending tab 460.
As the stylet 400 is rotated (in either direction), the tab 460
will engage the secondary tether 450, causing the housing component
12b, to rotate with the stylet 400. Thus, the stylet 400 is used to
advance and rotate the housing component 12b, without any other
coupling required and the secondary tether 450 is used to retract
the housing component 12b.
[0073] More than two housing components may be coupled together to
form or modify the IVMD 10. As previously indicated, different
parts of the same device may be separated between housing
components. Alternatively or in addition, subsequent housing
components may be added to provide additional therapies,
diagnostics, capabilities or power. For example, an IVMD 10 may be
implanted with a single use (i.e., non-rechargeable) battery. At a
later point, another housing component may be added that includes a
power supply to replace the depleted or soon to be depleted single
use battery. Thus, the useful lifetime of a given device may be
extended with a relatively minor procedure. An IVMD 10 may
initially be implanted having pacing functions and a later module
may be added that provides defibrillation therapies. FIG. 16
illustrates one embodiment of IVMD 10 having four joined housing
components 12a, 12b, 12c and 12d. It should be appreciated that any
number may be joined using any combination of the embodiments
discussed herein. It should further be appreciated that each such
component need not have the same size and shape. This will depend
upon the components included in any given section of housing 12 and
may take advantage of variations in the vasculature anatomy.
[0074] The IVMD 10 may also be accessed post implant to add
components (as discussed above) or to exchange components. That is,
rather than simply adding a housing component 12 having an
additional battery 20, a housing portion 12 having the battery 20
is first removed over the tether 70 and a new housing portion 12 is
added. In this manner, the lead(s) 60 may remain in place, while
other portions of the device are removed, replaced or otherwise
manipulated. To that end, it should be appreciated that the distal
header 16 may take the form of a full or partial housing component
12 that remains in place and is tethered to allow other housing
components to be manipulated. Alternatively, the tether 70 may be
coupled with a distal portion of the lead(s) or lead connector.
Thus, the entire housing 12 may be added/removed while the lead(s)
remains implanted and tethered. Finally, it should be appreciated
that the IVMD may provide a variety of functions including sensing,
diagnostics and/or therapy. Thus, accessing the IVMD 10 via the
tether 70 allows for other components to be exchanged without
removing the entirety of the device. For example, chemical sensors
may become depleted of a source material or catalyst and replaced
in this manner. Similarly, longer term drug eluting member or drug
reservoirs may be replaced. Such reservoirs may contain traditional
pharmaceuticals and/or genetic materials or biologics. The IMVD 10
may be used to deliver such agents (e.g., gene therapy) to a target
tissue location. When necessary, the IVMD 10 is re-supplied without
requiring complete extraction or the implantation of another
device.
[0075] FIG. 17 illustrates an IVMD 10 implanted within the
subclavian vein 504 and extending into the superior vena cava 506
of a heart 500. The lead 60 is illustrated as being an atrial
pacing lead and a distal tip 64 is affixed within the right atrium
502. Multiple additional leads may be included. The tether 70
extends from the proximal header 14 of the housing 12 through the
subclavian vein 504. The proximal end 74 of the tether 70 exits the
subclavian vein 504 at an initial entry point 600. The proximal end
74 is secured to tissue surrounding the initial entry point 600, by
e.g., the T-shaped anchor 76 which is sutured to the tissue. As
pulsitile blood flow, directed towards the heart 500, and patient
movement will cause movement of the housing 12, a sufficient amount
of slack material is provided along the length of the tether
70.
[0076] The position of housing 12 illustrated in FIG. 17 is
non-limiting. If desired, the housing 12 may be positioned closer
to the initial entry point 600, thereby increasing the length of
the lead 60. Conversely, the housing 12 may be positioned closer to
or even within the heart 500, increasing the length of the tether
70 and decreasing the necessary length of the lead 60. FIG. 18
illustrates the position of the heart 500 relative to the
subclavian vein 504 as well as the clavicle 620. In some
embodiments, it may be desirable to position the housing 12 within
the superior vena cava 506 below (towards the heart 500) the
clavicle 620. This avoids any potential for "subclavian crush"
wherein leads or components within the vasculature are compressed
between the clavicle and the first rib (not illustrated). The size
and nature of a given IVMD 10 will determine whether this is or is
not a concern. Due to its size, shape and material properties, this
will generally not affect the tether 70. Furthermore, implantation
via the subclavian vein 504 is only one entry site and others may
be utilized.
[0077] As illustrated in FIG. 17, the initial entry point 600 may
be positioned quite distant relative to the location of the housing
12. FIG. 19 illustrates the position of the cephalic vein 660 which
flows into the subclavian vein 504 and is accessible along the arm
665 of the patient. Thus, the initial entry point 600 may be made
in the cephalic vein 660 with the tether 70 then anchored to tissue
in the arm 665.
[0078] After implantation, it may be necessary or desirable to
access the IVMD 10. The proximal end 74 of the tether 70 is located
and, e.g., the subclavian vein 504 is accessed. The housing 12 may
be moved or removed/explanted via the tether 70 and any associated
leads 60 can likewise be moved, explanted, tested or otherwise
manipulated. In addition, components may be added or replaced on
housing 12 without requiring removal. As identification of the
proximal end 74 of the tether 70 facilitates such procedures, the
proximal end 74 may include a radiopaque marker for identification
with various imaging technologies, such as X-ray imaging or
fluoroscopy. Of course, the entirety of the tether 70 may likewise
be radiopaque. Alternatively, or in addition thereto, the proximal
end 74 may be felt by applying pressure in the area. The
configuration and anchoring of the proximal end 74 will determine
whether this is possible and a balance is selected between patient
perception of the proximal end, and the ability to locate the
tether 70 manually, and the ease or pressure required to locate the
tether manually 70. As yet another alternative, the subclavian vein
504 (or any vein/artery with a tether 70) is accessed via a new
puncture distal to the proximal end 74. The tether 70 is then
located and manipulated. This may involve severing the tether 70
and if appropriate, reattaching or re-anchoring the tether 70.
[0079] As illustrated in FIG. 17, the IVMD 10 is secured at two
locations; the first being where the proximal end 74 of the tether
70 is sutured and the second where the lead 60 is affixed to the
atrial wall. In some embodiments, the nature of the lead 60 (or the
absence thereof) may permit the distal end of that lead 60 or the
housing 12 to move freely and remain unsecured. For example, lead
60 may include a pressure sensor or temperature sensor. While such
sensors may still include an attachment mechanism, it is possible
to permit them to remain unattached. In addition to having the
tether 70 anchored and having one or more leads 60 anchored, the
flow of blood is directed towards the heart; which generally
assists with maintaining the position of housing 12 as this flow
generates force against the anchored portion of the tether 70. This
represents a relatively simple implantation procedure in that
additional retention mechanisms are not required.
[0080] As indicated, the subclavian vein 504 and superior vena cava
506 are not the only potential implant locations. A variety of
other locations will be able to utilize blood flow and gravity in
combination with the tether 70 to secure IVMD 10. Of course, IVMD
10 may be implanted in other locations wherein this effect is not
available or sufficient. In addition, there may be other reasons to
further secure various portions of IVMD 10. In one embodiment,
retractable members are provided that expand against a vessel wall
to secure the IVMD 10. The retractable members are collapsed for
subsequent movement or explanation. Such structures are illustrated
in published PCT application WO 2004/110263 which is herein
incorporated by reference.
[0081] FIG. 20 illustrates an IVMD 10 implanted in substantially
the same position as illustrated in FIG. 17. In this embodiment, an
expansion member 700 is expanded within the superior vena cava 506.
Expansion member 700 presses the lead 60 against an interior wall
of the vessel, further securing the lead 60 in place. Expansion
member 700 may be a self expanding member made from shape-memory
material or from material having a spring force that is restrained
by e.g., a catheter until deployed. Alternatively, expansion member
700 is mechanically expanded by a balloon catheter or similar
deployment mechanism. The use of such a member is generally not
required when both ends of the IVMD are secured and blood flow is
not pulling against an implanted lead. Such an expansion member may
be useful when the lead 60 is otherwise unsecured or IVMD 10 is
positioned in a location where blood flow or other forces might
negatively affect the implant. It should be appreciated that the
expansion member 700 may be used for one or more leads, the housing
12, the tether 70 or any combination thereof.
[0082] FIGS. 21A-21J schematically illustrate implantation of the
IVMD 10. In FIG. 21A, a needle 810 is used to percutaneously pierce
and enter a vessel 802, such as for example the subclavian vein or
cephalic vein. The needle 810 passes through the skin 800; in some
cases access to the vein 802 may require piercing muscle or other
tissue. Care is taken with the percutaneously puncture so that the
needle does not pass entirely through the vessel 802 and into the
underlying tissue 804.
[0083] With the needle 810 positioned within the vessel 802, a
guidewire 815 is passed through the needle 810 and into the vessel,
as shown in FIG. 21B. While retaining the guidewire 815 in place,
the needle 810 is withdrawn as illustrated in FIG. 21C. A
deployment catheter 820 is inserted (FIG. 21D) into the vessel 802
over the guidewire 815. A dilation catheter may be used to expand
the original puncture or the tissue may be cut if the opening is
insufficient. Depending upon the configuration of the IVMD 10, the
guidewire 815 and/or the deployment catheter 820 may be directed to
the final implant location for a lead and/or for the housing of the
IVMD 10. Alternatively, if a stylet or other external mechanism is
utilized, the deployment catheter 820 need only provide access to
the vessel 802 and the length of penetration is selected as
desired.
[0084] The IVMD 10 passes through the catheter 820 and enters the
vessel 802. Again, multiple embodiments have been presented and the
order of entry of certain components will vary accordingly. In this
example, the lead 60 is directed first towards the implant site by
e.g., a stylet directed through the lead or a stylet gripping an
external portion of the lead; neither of which are illustrated in
this figure. Trailing the lead 60 is the housing 12 followed by the
tether 70. When the housing 12 and lead 60 are positioned, the
tether 70 will include an excess amount exiting the incision site
as illustrated in FIG. 21F. If additional intravascular securement
mechanisms are utilized, they are deployed and configured. The
tether 70 is cut (FIG. 21G) at sever point 830 with a sufficient
amount of excess provided so that upon anchoring, enough slack
remains to allow expected movement of the IVMD 10 within the
vasculature. The cut tether now has a new proximal end 840.
[0085] The new proximal end 840 is secured. As discussed, there are
multiple methods to attach the tether 70. As illustrated, the
T-anchor 76 is mechanically attached to the new proximal end 840
(FIG. 21H). The T-anchor 76 is then secured with sutures 850 to
tissue proximate the incision site (FIG. 21I). The puncture or
incision through the vessel 802 will heal around the tether 70 and
if necessary, this process may be aided by additional suturing or
other techniques. The T-anchor 76 will remain below the surface 860
of the skin 800, with the actual depth/distance from the surface
860 determined by the medical practitioner, the depth of the
incision, and the site of implant. It should be appreciated that
the anchor 76 may be affixed to skin tissue, muscle or even the
vasculature wall. The final position of the anchor 76 may therefore
be subcutaneous or submuscular. As illustrated in FIG. 21J, the
anchor 76 may be secured some distance from the vessel 802. This
may require an additional minor incision, but allows the anchor
point to be selected disparate from the puncture through the vessel
802.
[0086] FIGS. 22A and 22B are side elevational sectional views that
illustrate an external vasculature anchor 900 (EV anchor). As
previously discussed, the T-anchor 76 is sutured or otherwise
attached to tissue external to the vessel 802. The EV anchor 900 is
configured for direct attachment to an external wall of the vessel
802. The EV anchor 900 has an arcuate attachment pad 902 with a
tether connection rod 904 depending therefrom. A tether attachment
opening 906 is provided at a distal end of the rod 904 so that the
tether 70 is coupleable to the rod 904. The rod 90 penetrates the
vessel 802 (though the drawings are not meant to be to scale) and
serves as the anchor for the tether 70. The arcuate attachment pad
902 is large in comparison to the rod 904 so that the force
generated against the vessel 802 is dispersed over a larger surface
area.
[0087] The EV anchor 900 includes an interior concave surface 910
that is placed in contact with the vessel wall. This surface 910 is
subdivided into a first region 915 proximate the rod and the
remainder of the surface 920. Various drug eluting or traditional
coatings may be applied to the interior surface 910. For example,
in the first region 915, where the rod 904 enters the vessel 802,
adhesives, steroids, coagulants or other materials are provided to
facilitate the closure and healing of the puncture. The second
region 920 may be utilized for more adhesion or simply mechanical
support. The attachment pad 902 is meant to generally conform to
the shape of the exterior wall of the vessel 802. To that end, the
pad 902 may be flexible or malleable. Furthermore, while
illustrated as extending about less the half the circumference of
the vessels 802, it should be appreciated that the pad 902 may
extend about a greater portion of the vessel 802 and may completely
surround the vessel 802.
[0088] FIG. 23 is a flowchart with an overview of the steps for
implanting the IVMD 10 consistent with the teachings of the present
invention and as described in greater detail above. The appropriate
point of entry (e.g., subclavian vein) is identified and a
percutaneous puncture is made (1000). If necessary, this opening is
enlarged and any necessary catheter, guidewire or stylet is
utilized to insert, deliver and attach the housing, leads and any
other intravascular components of the IVMD 10 (1010). The tether 70
extends from the now delivered housing 12 to the entry site and
excess tether is cut and discarded (1020). Finally, the tether is
secure external to the vessel so as to anchor the IVMD 10
(1030).
[0089] While various embodiments have been shown and described, the
present invention is not meant to be limited by these embodiments.
Furthermore, the embodiments may be combined in numerous ways
without departing from the teachings of the present invention, even
when not specifically illustrated. Variations and modifications may
be made without departing from the spirit and scope of the present
invention.
* * * * *