Note: Descriptions are shown in the official language in which they were submitted.
CA 02488710 2011-05-20
STEERABLE SUPPORT SYSTEM WITH EXTERNAL RIBS/SLOTS
THAT TAPER
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BACKGROUND OF THE INVENTION
The present invention is generally related to medical devices, kits, and
methods. More specifically, the present invention provides a system for
accessing stenosis,
partial occlusions, or total occlusions in a patient's body.
Cardiovascular disease frequently arises from the accumulation of
atheromatous material on the inner walls of vascular lumens, particularly
arterial lumens of
the coronary and other vasculature, resulting in a condition known as
atherosclerosis.
Atheromatous and other vascular deposits restrict blood'flow and can cause
ischemia which,
in acute cases, can result in myocardial infarction or a heart attack.
Atheromatous deposits
can have widely varying properties, with some deposits being relatively soft
and others being
fibrous and/or calcified. In the latter case, the deposits are frequently
referred to as plaque.
Atherosclerosis occurs naturally as a result of aging, but may also be
aggravated by factors
such as diet, hypertension, heredity, vascular injury, and the like.
Atherosclerosis can be treated in a variety of ways, including drugs, bypass
surgery, and a variety of catheter-based approaches which rely on
intravascular widening or
removal of the atheromatous or other material occluding the blood vessel.
Particular
catheter-based interventions include angioplasty, atherectomy, laser ablation,
stenting, and
the like. For the most part, the catheters used for these interventions must
be introduced over
a guidewire, and the guidewire must be placed across the lesion prior to
catheter placement.
Initial guidewire placement, however, can be difficult or impossible in
tortuous regions of the
vasculature. Moreover, it can be equally difficult if the lesion is total or
near total, i.e. the
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lesion occludes the blood vessel lumen to such an extent that the guidewire
cannot be
advanced across.
For these reasons, it is desired to provide devices, kits, and methods which
can
access small, tortuous regions of the vasculature. In particular, it is
desired to provide
systems which can access partial occlusions, total occlusions, stenosis, blood
clots, or
thrombotic material. At least some of these objectives will be met by the
devices and
methods of the present invention described hereinafter and in the claims.
SUMMARY OF THE INVENTION
The present invention provides a hollow guidewire working channel system.
The system optionally includes a deflectable distal tip that can allow the
hollow guidewire
working channel to be steered through the body lumen. The guidewire system of
the present
invention typically includes an elongate body comprising a proximal end and a
distal end. A
deflectable distal tip can be coupled to the distal end of the elongate body.
The guidewire
system optionally includes at least one pull wire that can extend through the
elongate body to
couple to the distal tip. The pull wire is offset from a longitudinal axis of
the distal tip and
elongate body, such that axial manipulation of the pull wire deflects the
distal tip in a desired
direction. By torquing or twisting a proximal end of the hollow guidewire
working channel,
the deflected tip can be steered and advanced through the tortuous regions of
the vasculature.
The hollow guidewire system can be used as a support or access system an can
be navigated to and positioned at the target site, with or without the use of
a separate
guidewire. The hollow guidewire provides the flexibility, maneuverability,
torqueability
(usually 1:1), and columnar strength necessary for accurately advancing
through the tortuous
vasculature either over a standard guidewire or on its own. The hollow
guidewire working
channel has superior strength and rigidity characteristics that are not found
in conventional
balloon angioplasty or infusion catheters. The hollow guidewire system
provides superior
physical support for other interventional devices inserted within its lumen as
compared to
polymeric catheter devices. The hollow guidewire system allows the support of
devices used
for the dottering (i.e., trying to poke through) of occlusions or stenoses
while retaining the
desirable characteristics of flexibility, trackability, and torqueability.
The hollow guidewire system can act as a working channel inside of which
other interventional devices can be delivered to the target site, such as a
rotating guidewire or
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drive shaft, infusion guidewire, clot maceration guidewire, normal guidewires
of varying
stiffness, and the like.
Many thin walled polymeric based catheters do not have sufficient
maneuverability or torqueability to be advanced through tortuous body lumens
on their own
and must be navigated to an occlusion over a standard guidewire. In order for
these
polymeric catheters to be used as working channels, to physically support
devices inserted
within the catheter lumen intended to penetrate or otherwise treat such
lesions, the wall
thickness must be increased, which results in a reduction of the size of the
inner lumen. In
contrast, the hollow guidewire working channel of the present invention
typically has a thin
wall construction while still providing sufficient torqueability and
maneuverability to be
advanced through the body lumen, either over a standard guidewire or on its
own.
Consequently, the thin coil walls allows the lumen of the working channel to
be maximized.
This allows larger diameter devices to be inserted into the lumen than can be
inserted into
conventional polymeric based catheters. The larger lumen of the hollow
guidewire working
channel allows devices such as clot macerators and other larger devices to be
delivered to the
target lesion. Additionally, the larger diameter lumen of the hollow guidewire
allows for
infusion of clot dissolving or other fluids, and for aspiration of debris
stirred up in the clot
maceration process.
Unlike conventional infusion and catheter devices, the hollow guidewire
working channel can have a tip which has the same diameter as the rest of the
elongate body.
Additionally, a radio-opaque marker can be positioned on the extreme distal
tip of the
catheter. This allows the user to precisely identify the position of the
distal tip of the device.
Identification of the precise location of the extreme distal tip is
advantageous as it allows
devices inserted into the working channel to be positioned precisely at the
front surface of the
occlusion or stenosis.
In some embodiments, the distal tip will optionally have ribs or slots to
facilitate deflection in the desired direction. The ribs can be even or
tapered.
In use, the hollow guidewire can be advanced through the vasculature to the
lesion. Flexing or deflecting the distal tip controls the position and
orientation of the devices
disposed within the lumen and can avoid perforating the body lumen wall. For
example, if
the hollow guidewire is navigated to the lesion and the distal tip of the
hollow guidewire
system is pointed in a direction toward the vessel wall, the direction of the
distal tip can be
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changed by deflecting the tip and torquing and twisting the proximal end of
the hollow
guidewire system.
These and other aspects of the invention will be further evident from the
attached drawings and description of the embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a steerable guidewire system of the present invention;
Figure 2 shows a port assembly of the present invention;
Figure 3 is a cross sectional view of the distal tip along line 3-3;
Figure 4 shows a distal tip having ribs;
Figure 5 shows an alternative distal tip having tapered ribs;
Figures 6-8 illustrate a method of advancing the guidewire system through a
body lumen; and
Figures 9-10 illustrate advancing through a bifurcated body lumen.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
Figure 1 shows a steerable guidewire system 10 of the present invention. The
steerable guidewire system 10 includes an elongate body 12 having a proximal
portion 14 and
a distal portion 16. The elongate member 14 preferably has the flexibility,
pushability, and
torqueability to allow a user to advance the hollow guidewire directly through
a tortuous
blood vessel to the target site. Because of the high columnar strength of the
elongate body 12
there is typically no need for a separate guidewire. Most embodiments of the
steerable
guidewire system 10 includes a deflectable tip which provides improves the
directional
control of the hollow guidewire system and any device disposed within the
lumen of the
system.
Steerable guidewire 10 is typically sized to be inserted through coronary,
neuro, or peripheral arteries and can have a variety of diameters. The outer
diameter of the
hollow guidewire is typically between approximately 0.014 inches and 0.039
inches and
preferably between approximately 0.021 inches and 0.039 inches. The length of
the hollow
guidewire 10 may be varied to correspond to the distance between the
percutaneous access
site and the target site. For example, for a target site within the heart that
is being accessed
through the femoral artery, the hollow guidewire will typically have a length
of
approximately 190 cm. It should be noted however, that other embodiments of
the hollow
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guidewire 10 may have dimensions that are larger or smaller than the above
described
embodiments and the present invention is not limited to the above recited
dimensions.
The proximal end of the guidewire 10 can be coupled to a port assembly 18.
The port assembly can be a three-armed port assembly. As shown in Figure 2,
the port
assembly can include a first arm 20 that houses a steering pull wire 22 that
can control the
steering of the distal end of the elongate body 12. A second arm 24 can be
used to house a
drive shaft 30 (Figure 1). A third arm 26 can be used to aspirate or infuse
the target site. For
example, the third arm 26 can be coupled to a vacuum or a medical fluid
source.
Referring again to Figure 1, the hollow guidewire typically has an helically
wound elongated shaft 12 which defines an axial lumen that can be used for
infusion or
aspiration and that can receive a rotating guidewire, infusion guidewire, clot
maceration
guidewire, normal guidewires of varying stiffness, devices for treating
lesions, and the like.
The elongated shaft includes a proximal tube 14, an intermediate elongate,
coil body 31, and
a distal flexible tip 28. In some embodiments the intermediate elongate body
31 is made of a
stainless steel or nitinol, while the distal tip 28 is composed of stainless
steel or nitinol. As
shown, the intermediate coil 31 is threadedly engaged with the proximal
portion and distal tip
28 and the distal end of the elongate body 12. It will be appreciated,
however, that the
intermediate elongate body 12, intermediate coil 31, and distal tip 28 can be
connected to
each other by any other conventional means, e.g. solder, adhesive, or the
like.
In some embodiments the distal tip is approximately one half centimeter in
length and steerable in one direction. In other embodiments, the distal tip 28
can be steerable
in two directions, three directions, four directions, or the like. A devices
for treating lesions
can be disposed within the lumen of the elongate body so that it can be
axially moved and
rotated to remove material from the body lumen (not shown). A radio-opaque
marker such as
platinum-iridium 33 can be positioned at the distal tip to improve visibility
under
fluoroscopy.
Referring now to Figure 3, a cross section of one embodiment of the steerable
guidewire working channel system 10 is shown. An inner tube 32 and outer tube
34 are
positioned around the intermediate coil 36 and at least a portion of the
distal tip 28 to provide
a flexible, structural support which prevents liquids from moving between the
blood vessel
and the axial lumen of the elongate member 12. The outer tubing 34 can be
shaped to have
an elbow opening 35 (Figure 1) that facilitates bending of the distal tip 28
in the direction of
the elbow opening 35. The inner tube 32 is typically polyimide tubing having a
0.001 inch
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thick wall and may be coated with Teflon to improve movement of devices
through the
inner tubing 32. The active pull wire(s) 22 can be positioned between the
inner tube 32 and
the coils 36 to provide for deflection or steering of the distal tip 28.
Deflection of the distal tip is controlled by the user actuated pull wire 22.
The
pull wire 22 typically extends from the port assembly 18 through the elongate
body 12 and
connects to the distal end of the tip 32. The pull wire 22 can extend parallel
and offset from a
longitudinal axis of the elongate body, such that axial actuation of the pull
wire can deflect
the distal tip in the direction of the pull wire 22. As shown in phantom in
Figure 3, in some
embodiments a plurality of pull wires 22 can be positioned around the
longitudinal axis of the
elongate body to provide a distal tip that is deflectable in multiple
directions.
In an exemplary embodiment, the pull wire 22 has a diameter between 0.003
inches and 0.007 inches and is composed of 304SS Hyteri. The pull wire
preferably can
withstand more than 400 kpsi of tensile force. It should be appreciated
however, that the pull
wire can be modified to have a smaller or larger diameter and can be made from
an
alternative material. For example, the pull wire can be comprised of a strip
of stainless steel
that can be moved axially to steer the distal tip. In one configuration, the
pull wire 22 is
soldered or otherwise connected to the distal end of flexible tip 38 and the
remainder of the
reinforcing wire 22 extends proximally to the housing port assembly 18. To
reduce the
profile of the distal tip 28 and to increase the area of contact between the
distal tip and the
pull wire, the distal end of the pull wire can be flattened.
Manipulation of the proximal end of the reinforcing wire 22 allows the user to
deflect or steer the distal tip 18 without permanently impairing the inner
structure of the
guidewire 10. The deflectable distal tip provides a user with greater
intraluminal control of
navigating and steering the hollow guidewire to the target site. In other
configurations, the
reinforcing wire is 22 can be soldered or otherwise connected to both the
distal end and to the
junction between the coil 36 and distal tip 38. Therefore, if the tip 38
breaks, the attached
reinforcing wire 22 can prevent the tip 38 from detaching from the system 10.
A more
complete description of the hollow guidewire can be found in commonly owned
U.S. Patent
No. 6, 059,767.
30,
As shown in Figures 4 and 5 the distal tip 28 can be manufactured to have ribs
or partial circumferential slots 32 formed on at least one side of the distal
tip. As shown in
Figure 4 the ribs can extend evenly along one side of the distal tip to
provide means for
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deflecting or flexing of the distal tip in the direction of the ribs. It
should be appreciated, the
size of the distal tip can be varied so as to accommodate larger and smaller
body lumens. In
the exemplary embodiment shown, there are thirty ribs formed in the distal
tip. It should be
appreciated that any number of ribs can be created on the distal tip to
facilitate steering.
While not shown, in other embodiments, the ribs 32 can be formed on opposite
sides of the
distal tip 28 so as to facilitate deflecting in two directions. Such ribs 32
can be spaced from
the opposite ribs so as to not detrimentally effect the structural strength of
the distal tip.
Additionally, as mentioned above some embodiments of the distal tip 28 can be
steerable in
four directions or more. Consequently, ribs can be formed in a plurality of
places on the
distal tip and additional pull wires can be added to facilitate steering in
multiple directions.
Figure 5 shows an alternative embodiment of the distal tip 28 of the guidewire
system 10. The ribs 32a, 32b can be tapered towards a distal end of the tip to
provide better
control the steering of the distal tip. The tapered ribs provide a larger bend
radius at the
proximal end of the tip 28 while having a smaller bending radius at the distal
end.
Alternatively, the ribs can be tapered toward a proximal end of the tip (not
shown) to provide
another variation to the steering of the distal tip. With such a variation,
there will be a larger
bending radius at the distal end of the tip and a smaller bending radius at
the proximal end of
the tip 28.
In use, the guidewire can be introduced into the body lumen using
conventional delivery techniques. The distal tip can be deflected and/or
rotated to navigate
through the body lumen to the occlusion. To deflect the distal tip 28, a user
will axially move
the pull wire 22 until the distal tip is deflected in the desired direction.
In exemplary
embodiments, the distal tip is deflectable between approximately 5 degrees and
10 degrees.
It should be appreciated however, that in other embodiments it may be possible
to steer the
distal tip up to 180 degrees. For example, as illustrated in Figure 6, as the
hollow guidewire
is being advanced through the body lumen, the distal tip 28 may contact a
curved portion of
the body lumen wall. As shown in Figure 7, to get past the curved, tortuous
portion of the
body lumen, the user can then activate the pull wire to deflect the distal tip
to change the
direction of advancement (as shown by the dotted line). To continue
advancement, the user
can twist or torque the proximal end of the hollow guidewire system until the
distal tip is
clear of the body lumen wall and aligned with the body lumen (Figure 8).
Thereafter, the
user can push the proximal end of the hollow guidewire system and continue
advancement
through the body lumen to the lesion. When the lesion has been reached, the
device within
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the lumen of the hollow guidewire system can be advanced out of the hollow
guidewire
system to treat the lesion.
In another method, the deflectable distal tip allows deflection of the distal
tip
to steer the hollow guidewire system through the correct branch vessel of the
body lumen.
As shown in Figure 9, if the guidewire is advanced in its current orientation,
the hollow
guidewire will be advanced down the right branch vessel. In order to be moved
up through
the left branch vessel, the tip can be deflected and twisted (if needed) to
move the hollow
guidewire into alignment with the left branch vessel. Accordingly, in the
orientation of the
hollow guidewire shown in Figure 10, advancement of the hollow guidewire will
move the
hollow guidewire into the left branch vessel.
While the above is a complete description of the preferred embodiments of the
invention, various alternatives, modifications, and equivalents may be used.
Therefore, the
above description should not be taken as limiting the scope of the invention
which is defined
by the appended claims.
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