Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED SYSTEM AND METHOD OF POSITIONING IMPLANTABLE
MEDICAL DEVICES
This application claims priority to U.S. Provisional Patent Application
60/338,288
filed November 8, 2001, and incorporates the specification and drawings in
their entireties
by reference herein.
This invention relates to implantable medical device systems, and in
particular to a
device and method for the placement and control of an implantable medical
device into
specific cardiovasculature locations such as the distal vasculature system of
the coronary
sinus.
The use of implantable medical electrical stimulation and/or sensing leads is
well
known in the fields of cardiac stimulation and monitoring. Endocardial leads
are placed
through a transvenous route to place one or more sensing and/or stimulation
electrodes in
a desired location within a heart chamber or interconnecting vasculature. In
order to
achieve reliable sensing of the cardiac electrogram and/or to apply
stimulation that
effectively paces, cardioverts, or deftbrillates a cardiovascular structure,
it is necessary to
accurately position the electrode surface against the endocardium,
pericardium, or within
the myocardium, or at a desired location within the venous system. This
precise
positioning may be accomplished using a delivery system that may include a
guide
catheter, stylet, guidewire, steerable sheath, and/or an equivalent delivery
mechanism.
It has long been known that leads and/or other implantable medical devices
(IMD)
may be positioned within the right atrium and/or ventricle to provide
therapies for cardiac
ailments. Recently, it has become more apparent that certain cardiac
disfunctions such as
heart failure may be effectively treated by positioning leads, catheters,
and/or IMDs
adjacent to, or within, the left side of the heart. For example, cardiac
resynchronization
therapy may be accomplished by pacing both the left and right ventricles. Left
ventricular
pacing pulses may be delivered via a lead positioned within the coronary sinus
or a branch
cardiac vein in proximity to the left ventricle. To position a lead or
catheter so this type
of treatment may be provided, a distal end of the device is advanced through
the superior
vena cava, into the right atrium, through the valve of the coronary sinus, and
into the
coronary sinus. The device may be further advanced into a coronary vein
communicating
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with the coronary sinus, such as the cardiac great vein, the middle cardiac
vein, the
posterial lateral cardiac vein, or the anterial lateral cardiac vein as
examples. Additionally,
it may be desirable to locate pacing leads, or other types of leads, at other
locations within
the heart for various reasons. For example, it may be desirable to locate such
leads in the
right ventricular outflow tract (RVOT), the Bundle of His, or the triangle of
Loch, as such
alternates may enhance the effectiveness of the heart therapy delivered to
such sites.
Several common delivery systems have been developed to place electrodes in a
specific location, such as, within the left side of the heart. According to
one approach, a
guide catheter is navigated into the desired location in the vasculature. A
lead is then fed
through the inner lumen of the catheter such that the lead electrodes) are
positioned at
predetermined locations. The guide catheter may then be withdrawn. This type
of
approach is described in commonly assigned U.S. Patent Numbers 6,006,137,
5,246,014,
and 5,851,226 incorporated herein by reference in their entireties.
Another approach to lead placement involves the use of a guide wire that is
steered
into a desired location within the vasculature. The lead body is then tracked
over the wire
and the wire is withdrawn. According to this design, the guide wire passes
through an
inner lumen of the lead for at least a portion of a length of the lead. A
similar approach is
described in commonly assigned U.S. Patent Number 5,902,331 to Bonner et al.,
also
incorporated herein by reference in its entirety. The disclosed system
includes a pusher
mechanism that is adapted to slidably engage a guidewire that has previously
been placed
at a desired implant site. The pusher mechanism couples to a lead body to
allow the
pusher to guide the lead over the guidewire to the desired implant site.
Regardless of which of the above-described delivery systems is utilized, a
significant challenge involves the location and navigation of a guide device,
such as a
catheter or guide wire, into the coronary sinus. Anomalies in the vascular
anatomy, their
small size, and the number of branch veins associated with the anatomy make
locating the
desired path challenging.
One mechanism used to aid in placement of a device within the coronary sinus
involves the use of radiopaque dye. This dye may be injected into the venous
anatomy so
that the chambers of the heart and the related vasculature system are visible
using a
fluoroscopic device. This procedure, sometimes referred to as a "venogram",
allows the
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surgeon to locate the coronary sinus, its distal vasculature, or other
anatomical structure
when performing an implant procedure.
It may be undesirable to use fluoro visible media during an implant process
for
several reasons. First, some patients experience adverse physical reactions
when exposed
to the fluoro visible dye used to obtain a venogram. In these situations, an
alternative
approach is needed to accomplish lead placement. Moreover, the use of
fluoroscopy
exposes the patient, implant surgeon and assistants to radiation. The use of
protective lead
aprons prevents or limits exposure to the physician and his attending staff,
but their heavy
weight is problematic for long and/or several procedures daily. Additionally,
a
fluoroscope of the type needed for obtaining the fluoro-visible image may not
be
available. Finally, obtaining the venogram adds additional steps to the
implant procedure,
lengthening the time required to complete the procedure, increases the cost of
the
procedure and increases the risk of infection and complications to the
patient.
Another approach to performing catheter placement and cardiac surgery is
disclosed in U.S. Patent No. 6,175,346 incorporated herein by reference in its
entirety.
That patent describes the use of an infrared imagining system that is capable
of
transmitting light into an environment containing opaque or semi-opaque fluids
such as
blood. However, a lead delivery method is not disclosed.
What is needed, therefore, is an alternative system and method for accurately
and
rapidly placing implantable medical leads and sensors at precise locations
within the
vascular system of the body such as within the coronary sinus or a branch vein
without the
need to inject a fluoro visible media into the body and to minimize the use of
fluoroscopy.
SUMMARY OF THE INVENTION
The present invention provides a visual catheter guide system to navigate and
position a medical device within the coronary sinus and branch veins, such as
the cardiac
great vein, the middle cardiac vein, the posterial lateral cardiac vein, the
anterial lateral
cardiac vein and similar other cardiac vasculature. The system enables
continuous visual
imaging of the deployment, location and vascular environment of the catheter
inside the
cardiac network of vasculatory system.
In one aspect of the invention, a shaft adapted to be positioned within the
cardiac
vein or coronary artery incorporates a fiber optic cable suitable for
transmitting light.
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Preferably, an infrared light source transfers infrared light down the cable.
An optical
head assembly coupled to the cable is implemented as a transceiver for the
infrared light.
Further, sensing systems receive the infrared light from the body using
optical assemblies.
An image is generated indicating the position of the distal portion of the
elongated shaft,
in addition to monitoring navigation on a real-time visual basis.
Various systems of lead placement in the coronary sinus are advanced in the
present invention. The vision system, for example, may incorporate an ablation
system for
navigation and placement of an ablation electrode in a human heart. Another
embodiment
includes an implementation of a laser lead extraction system to view and
remove a cardiac
lead from the heart. Further, proper positioning of an ablation catheter prior
to the
application of ablation energy is enabled using the scheme and structure of
the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the present invention will be more readily
understood
from the following detailed description of the preferred embodiments thereof,
when
considered in conjunction with the drawings, in which like reference numerals
indicate
identical structures throughout the several views, and wherein:
FIG. 1 depicts an infrared endoscope system connected to a catheter delivery
system having a distal end positioned in a coronary vein;
FIG. 2 depicts a catheter delivery system of the present invention;
FIG. 3A is a cross section of the catheter delivery system of FIG. 1;
FIG. 3B is a cross section of a first alternative embodiment of the catheter
delivery
system of FIG. 1;
FIG. 3C is a cross section of a second alternative embodiment of the catheter
delivery system of FIG. l;
FIG. 4 is a cross section of an alternative implementation of the catheter
delivery
system of FIG. 1;
FIG. 5 is an alternative delivery system for use with the vision system of
FIG. 1;
and
FIG. 6 depicts an additional alternative embodiment of the present invention.
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DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
As described herein above in the background, the delivery and positioning of
this
left ventricular lead in the coronary sinus vasculature system is problematic.
The claimed
invention allows the rapid, accurate and easy deployment and positioning of a
lead in the
5 coronary sinus, distal coronary sinus, great cardiac vein, the middle
cardiac vein, the
posterial lateral cardiac vein, the anterial lateral cardiac vein or other
distal vasculature.
FIG. 1 illustrates a human heart 10 in cross section with the right atrium 12,
right
ventricle 14, left atrium 16, left ventricle 18, coronary sinus ostium 22 and
superior vena
cava 24 shown.
FIG. 1 further illustrates the catheter guide system 20 shown in FIG. 2
disposed
within the patient's vascular system with the distal section (not shown) of
the catheter
seated within the patient's coronary sinus ostium 22. In this embodiment, the
catheter
guide system 20 has been introduced from the cephalic vein (not shown) and
advanced
through the superior vena cava 24 and into the right atrium 12.
FIG. 1 still further shows catheter guide system 20 coupled to a system 100
for
transferring infrared light to the distal end of the catheter, capturing the
reflected light, and
displaying an image for use by an implanting physician. This catheter uses
technology
disclosed in U.S. Patent No. 6,178,346, incorporated herein by reference, to
transmit light
through opaic fluids such as blood. System 100 includes a laser diode 106 and
infrared
camera 112. Light reflected from within the coronary sinus is received by an
optical head
40 (located distally on catheter 20) and is transmitted via optical fibers in
lumens
contained in catheter 20 to beamsplitter 116. Thereafter, the light is passed
through
camera optics 114 to a sensing device such as infrared camera 112. There, the
light is
detected by the infrared camera sensor 110 and converted to an electronic
signal. This
signal is relayed via camera cable 118 to an image-processing unit 120. This
unit uses
known image processing techniques to enhance the image created by the
reflected and
scattering light to provide a view of the cardiac vasculature. The image
processing unit
120 is connected with electrical cable 122 to the central processing unit or
CPU 130,
which reconfigures the signals and transmits these signals through an
electrical cable 122
to a video processor 126 which processes the signals for video imaging. A
video console
124 and video recorder 128 may also be coupled to the video processor 126.
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The system of FIG. 1 may be used to position catheter guide system 20 within
the
coronary sinus and branch veins such as the cardiac great vein, the middle
cardiac vein,
the posterial lateral cardiac vein, or the anterial lateral cardiac vein.
Using a light having
wavelengths starting in the 1.5-1.8 micron range, structures may be visualized
at a
distance of 4-5 millimeters through blood. Wavelengths of approximately 2.1
microns
would also be suitable for this embodiment. This region permits viewing
arterial
structures about 10 millimeters through blood. Higher wavelength regions
(e.g., 3.8-4.4,
4.7-5.3, and 7-10) would generate more accurate images but also result in more
rigid
catheter designs because of the larger-sized optical fibers required in this
embodiment.
As shown in FIG. 2, in one embodiment, the invention includes a guide catheter
system 20 such as disclosed in U.S. Patent No. 6,021,340, incorporated herein
by
reference in its entirety. The catheter includes an elongated shaft 31, a
distal shaft section
36, a proximal shaft section 34, an inner lumen 32 and a control handle 30 on
the proximal
end of the shaft 31. A port 38 is provided in the distal end of the catheter
shaft 36 that is
in fluid communication with the inner lumen 32. The distal shaft section 36 is
controllable
in a 3D manner via the proximal handle 30 as described in the '340 patent. The
catheter
shaft 31 contains optical fibers to transmit infrared light from the vision
system 100 to a
lens 40 and transmits reflected light back to the vision system 100 for
processing and
displaying vasculature structures. Catheter 20 may optionally contain distally
located
sense/pace electrodes for the verification and confirmation of proper
location.
FIG. 3A shows a cross sectional view of the guide catheter system 20 of FIGS.
1
and 2. The catheter body 52 contains several lumens 50 containing optical
fibers for the
transmission of infrared light from a proximal source 106 to a lens 40 on the
distal end of
the catheter and for the reflected light to be returned to the infrared camera
112. A pacing
or defibrillation lead 62 is shown in a central lumen 56. The catheter guide
system 20 is
used to deliver the distal end of the catheter to a desired location and then
a lead is
threaded through lumen 56 to deliver the lead to the proper location. This
method allows
the use of very small diameter lead systems because a stylet lumen is not
required in the
lead body construction.
FIG. 3B shows an alternative cross sectional view of the guide catheter system
20
of FIGS. 1 and 2. The catheter body 52 contains several lumens 50 containing
optical
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fibers for the transmission of infrared light from a proximal source 106 to
the distal end of
the catheter and for the reflected light to be returned to the infrared camera
112. A guide
wire 54 is shown in a central lumen 56. This method allows the distal end of a
guide wire
to be positioned in the correct location, a lead body is tracked over the wire
and the wire is
then withdrawn.
FIG.3C shows a cross sectional view of the guide catheter system 20 of FIGS.1
and 2 containing an alternative embodiment of catheter body construction. The
catheter
body 52 contains a single lumen 50 containing optical fibers for the
transmission of
infrared light from a proximal source 106 to the distal end of the catheter.
At the distal
end of the catheter 38 an active pixel sensor is positioned to receive light
reflected from
the coronary sinus vasculature system. The active pixel sensor is as
substantially
described in U.S. Patent Nos. 6,204,524, 6,243,131, and published application
No.
2001/0055832. The '524 and '131 patents and '832 application are incorporated
herein by
reference in their entireties. Lumen 58 contains several insulated electrical
wires 60 for
providing power to the sensor and return signals depicting the field of view
of the active
pixel sensor. A guide wire 54 is shown in a central lumen 56. The operation of
delivering
a lead via a properly positioned guide wire is as described above. This
catheter design
allows for a smaller, more flexible catheter design allowing it to reach
smaller and more
distal vasculature. Additionally, larger optical fibers may be used to allow a
larger
wavelength infrared light source (i.e., 3.8 4.4, 4.7-5.3, and 7-10 microns) to
be used
providing for images with improved clarity and increased accuracy.
FIG. 4 depicts an alternative method of lead placement in the coronary sinus
(see
FIGS. 1, 2, 3B and 3C). In this method, a guide wire is advanced into the
coronary sinus
ostium and advanced through the vasculature system to the proper location for
pacing and
defibrillation lead placement as is well known in the art. The guide wire 314
is advanced
under visual control by the system shown in FIG. 2 and herein described above.
After
guide wire placement, an over the wire pacing or defibrillation lead 306 can
be inserted
and then the lead passed over the guide wire 314 through lumen 322 until it is
properly
positioned. The guide wire 314 enters the distal end of the lead 306 through
lumen 322 at
the lead distal tip 324 and exits the side of the lead 306 via exit port 316.
After the lead is
properly positioned, the guide wire 314 can then be retracted from the lead
306.
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FIG. 5 depicts another embodiment, whereby the vision system described above
is
incorporated into an ablation system as described in U.S. Patent No. 6,325,797
for
accurate location of the ablation electrode in a human heart 10. The '797
patent describes
a catheter assembly and method for treatment of cardiac arrhythmia, for
example, atrial
fibrillation, by electrically isolating a vessel, such as a pulmonary vein
204, from a
chamber, such as the left atrium 16. The catheter assembly includes a catheter
body 202
and at least one electrode 208. The distal portion of the catheter 202 extends
from an
intermediate portion (inserted from the inferior vena cava 200) and forms a
substantially
closed loop transverse to the longitudinal axis with the at least one
electrode 208 disposed
along the loop. With this configuration, the loop is axially directed into
contact with the
chamber wall about the pulmonary vessel ostium 204. Upon energization, the
electrode
ablates a continuous lesion pattern about the vessel ostium 204, thereby
electrically
isolating the vessel from the chamber. In the herein described embodiment,
additional
lumens filled with optical fibers may be employed as described above to allow
the
visualization of the location of the catheter 202 via a lens 206 located at
the distal end of
catheter 202. The visualization will allow the proper positioning of the
ablation
electrodes) in a fixed and proper location (for example, the pulmonary vein
ostium 204).
FIG. 6 depicts yet another embodiment incorporating the vision system as
described above into a lead extraction device as substantially described in
U.S. Patent Nos.
5,423,806 and 5,674,217, both to Wahlstrom, et al. which utilizes laser light
to separate an
implanted object, such as a pacemaker lead, from fibrous scar tissue and
thereby permit
the implanted object to be extracted from a body. The extraction device
features a catheter
406 having a central lumen 414 dimensioned so a pacemaker lead will ftt
within. The
catheter 406 is thereby guided by the lead. The catheter 406 has at least one
optical fiber
412 to emit laser light 402 from the distal end 408 and thereby separate the
lead from
fibrous scar tissue. Through such catheters the lead may be separated along
its length, as
well as separated at its distal end from fibrous scar tissue, thereby
permitting the lead to be
readily extracted from the body. In the herein described embodiment,
additional fibers
412 may be employed as described above to allow the visualization of the
location and the
rapid positioning of the catheter in relation to the fibrous scar tissue or
bone that may be
holding the lead body in a fixed location.
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The present invention provides a system and method for utilizing an infrared
imaging system for placing leads or any other device within the coronary
sinus, branch
cardiac veins and/or specific locations in the heart. Although several
specific
embodiments are discussed herein for exemplary purposes, it will be understood
other
types of catheters may be utilized. For example, systems and methods such as
disclosed in
U.S. Patent Nos. 6,122,552 and 5,639,276 incorporated herein by reference may
usefully
employ the current invention. The current invention may additionally be
incorporated into
a guide wire or a lead itself.
The preceding specific embodiments are illustrative of the practice of the
invention. It is to be understood, therefore, that other expedients known to
those of skill in
the art or disclosed herein may be employed. In the following claims, means-
plus-
function clauses are intended to cover the structures described herein as
performing the
recited function and not only structural equivalents but also equivalent
structures. For
example, although a nail and a screw may not be structural equivalents in that
a nail
employs a cylindrical surface to secure wooden parts together, whereas a screw
employs a
helical surface, in the environment of fastening wooden parts, a nail and a
screw are
equivalent structures.
It is therefore to be understood that, within the scope of the appended
claims, the
invention may be practiced otherwise than as specifically described without
actually
departing from the spirit and scope of the present invention.
