U.S. patent application number 10/842158 was filed with the patent office on 2004-12-30 for adjustable stylet.
This patent application is currently assigned to Synovis Life Technologies, Inc.. Invention is credited to Soukup, Thomas.
Application Number | 20040267162 10/842158 |
Document ID | / |
Family ID | 26894763 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040267162 |
Kind Code |
A1 |
Soukup, Thomas |
December 30, 2004 |
Adjustable stylet
Abstract
An adjustable stylet includes a core wire having a portion
surrounded by a compression member preferably comprised of a flat
wire spring. Depending upon the configuration, compression or
relaxation of the compression member in response to forces at the
tip or handle of the stylet results in adjustments to the
characteristics of the stylet. In a first embodiment, the stiffness
of the stylet is adjustable. In a second embodiment, the length of
the stylet is adjustable. In a third embodiment, both the stiffness
and the length of the stylet are adjustable.
Inventors: |
Soukup, Thomas; (Plymouth,
MN) |
Correspondence
Address: |
INTELLECTUAL PROPERTY GROUP
FREDRIKSON & BYRON, P.A.
200 SOUTH SIXTH STREET
SUITE 4000
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Synovis Life Technologies,
Inc.
|
Family ID: |
26894763 |
Appl. No.: |
10/842158 |
Filed: |
May 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10842158 |
May 10, 2004 |
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09843040 |
Apr 25, 2001 |
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6755794 |
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60199428 |
Apr 25, 2000 |
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Current U.S.
Class: |
600/585 |
Current CPC
Class: |
A61M 2025/0915 20130101;
A61M 25/09 20130101 |
Class at
Publication: |
600/585 |
International
Class: |
A61B 005/00 |
Claims
What is claimed is:
1. An adjustable stylet for use within a lumen of an intravascular
device comprising: a core wire having a blunt distal end and a
proximal end and having an outer diameter of less than 0.020 inches
and a relatively uniform beam strength over an axial length of said
core wire; a compression member having a distal end operably
secured to said core wire and a proximal end axially movable along
said core wire, said compression member comprising a flat wire
space wound around at least a portion of said core wire with a wide
dimension of said flat wire oriented axially and an axial spacing
between successive windings of said compression member; a handle
operably mounted proximate said proximal end of said core wire,
said handle axially movable to operably engage said proximal end of
said compression member such that said axial spacing between at
least a portion of said successive windings is adjusted by movement
of said handle, whereby a stiffness of said stylet is adjusted by
operation of said handle.
2. The adjustable stylet of claim 1 wherein said compression member
is secured to said core wire proximate said blunt distal end of
said core wire.
3. The adjustable stylet of claim 1 further comprising a rigid tube
member operably positioned around said core wire between said
proximal end of said compression member and said handle to transfer
axial force applied by said handle to said compression member.
4. The adjustable stylet of claim 1 wherein said flat wire is a
stainless steel wire having an aspect ratio of at least 2:1 and
having a narrow cross-sectional dimension of less than 0.003
inches.
5. The adjustable sylet of claim 1 wherein said blunt end is
comprised of a ball welded to said distal end of said core
wire.
6. The adjustable stylet of claim 1 wherein said handle is slidable
relative to said core member.
7. The adjustable stylet of claim 1 wherein said handle includes a
handle member secured to said core wire proximate said proximal end
and a moveable member operably engaged with said handle member such
that said moveable member is axially moveable relative to said
handle member within a distance determined by said handle member,
said moveable member including a proximal portion extending
distally beyond said handle member for operably engaging said
proximal end of said compression member.
8. The adjustable stylet of claim 7 wherein said moveable member
and said handle member include structure such that said moveable
member is slidable relative to said handle member.
9. The adjustable stylet of claim 7 wherein said moveable member
and said handle member include structure such that said moveable
member is screwable relative to said handle member.
10. The adjustable stylet of claim 7 wherein at least one of said
moveable member and said handle member includes structure to
releasably position said moveable member relative to said handle
member at multiple axial locations.
11. The adjustable stylet of claim 1 wherein said core wire
comprises a wire having a uniform cross-sectional diameter.
12. The adjustable stylet of claim 1 wherein said core wire
comprises a solid wire.
13. The adjustable stylet of claim 1 wherein said core wire
comprises: a first core wire segment and a second core wire
segment; and a length adjustment member secured between adjacent
ends of said first and second core wire segments, said length
adjustment member comprising a space wound wire with an axial
spacing between successive windings of said length adjustment
member such that an axial force applied to at least one end of said
length adjustment member decreases said axial spacing between at
least a portion of said successive windings of said length
adjustment member.
14. An adjustable stylet for use within a lumen of an intravascular
device comprising: a first core wire and a second core wire, each
core wire having an outer diameter of less than 0.020 inches and a
relatively uniform beam strength over an axial length of said core
wire; and a compression member secured between adjacent ends of
said first and second core wires, said compression member
comprising a space wound wire with an axial spacing between
successive windings of said compression member such that an axial
force applied to at least one end of said compression member
decreases said axial spacing between at least a portion of said
successive windings.
15. The adjustable stylet of claim 14 wherein said compression
member is a flat stainless steel wire having an aspect ratio of at
least 2:1 and having a narrow dimension of less than 0.003
inches.
16. The adjustable stylet of claim 14 wherein each of said adjacent
ends of said first and second core wires are centerless ground and
said compression member overlaps and is secured to said centerless
ground portion of said adjacent ends.
17. The adjustable stylet of claim 14 further comprising a cover
tube surrounding at least a portion of said compression member and
secured at only one end to one of said first and second core
wires.
18. An adjustable stylet for use within a lumen of an intravascular
device comprising: a core wire having a blunt distal end and a
proximal end and having an outer diameter of less than 0.020 inches
and a relatively uniform beam strength over an axial length of said
core wire; compression means for adjusting a stiffness of said
stylet, said compression means having a distal end operably secured
to said core wire and a proximal end axially movable along said
core wire; handle means for engaging said compression means to
effect adjustment of said compression means, said handle means
operably mounted proximate said proximal end of said core wire.
19. The adjustable stylet of claim 18 further comprising a rigid
tube member operably positioned around said core wire between said
proximal end of said compression means and said handle means to
transfer axial force applied by said handle means to said
compression means.
20. The adjustable stylet of claim 18 wherein said core wire
comprises a solid wire having a uniform cross-sectional diameter.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of patent
application having U.S. Ser. No. 09/843,040, filed Apr. 25, 2001,
which is a continuation of provisional U.S. patent application
filed Apr. 25, 2000 and assigned Ser. No. 60/199,428, the entire
disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
intravascular leads and catheters. More specifically, the present
invention relates to an adjustable stylet for use in positioning
such leads and catheters.
BACKGROUND OF THE INVENTION
[0003] Stylets and guidewires are used to control the manner in
which intravascular leads and catheters are introduced into the
veins or arteries of the body. Although both kinds of devices are
often thought of as simply very small wires, the purpose and
operation of stylets is significantly different as compared to
guidewires.
[0004] Conventional intravascular procedures typically involve an
initial step of introducing and routing a guidewire through a
patient's vascular system to provide a rail or track along which
additional intravascular devices may be introduced. Once a
guidewire is in place, a sheath is routed over at least a portion
of the guidewire to provide a larger opening into the vein or
artery and sometimes to protect the inside walls of the vessels
along the route of the guidewire. With the sheath in place, the
guidewire may be removed or may remain in place as additional
intravascular devices such as intravascular leads and catheters are
introduced into the patient's vascular system.
[0005] To better accomplish the purpose of a guidewire of providing
a track along the patient's vascular system for other intravascular
devices, it is desirable that the guidewire have a region at the
tip of the guidewire, referred to as the distal end, that is
extremely flexible. Preferably, the guidewire has the ability to
vary the flexibility of the distal tip and/or deflect the distal
tip so as to aid in routing the guidewire through the patient's
vascular system. U.S. Pat. Nos. 4,215,703, 4,456,017, 4,719,924,
4,886,067 and 5,060,660 describe designs for guidewires that use an
internal tensioning member or pull wire to alter the
characteristics of the non-expandable distal tip and/or to deflect
the distal tip. U.S. Pat. Nos. 4,271,845 4,822,345, 5,605,162,
5,762,615, 5,851,203, 5,957,903 and 6,183,420 describe various
designs for guidewires with adjustable stiffness by moving a core
member axially within the distal region of the guidewire. U.S. Pat.
Nos. 5,938,623 and 6,039,743 describe a guidewire with adjustable
stiffness that is controlled by running electricity through a
memory metal wire tip. U.S. Pat. No. 5,341,817 describes a
guidewire extension arrangement in which a smaller inner extension
can be pushed out of a larger core segment to extend the distal end
of the guidewire. U.S. Pat. Nos. 4,846,174 and 5,338,301 describe
guidewires with a core member that can be extended to axially
stretch an angioplasty balloon at the distal tip. In a similar
manner, U.S. Pat. Nos. 3,841,308 and 4,759,748 describe catheters
that utilize a core member to axially stretch a coiled section at
the distal end of the catheter for purposes of controlling delivery
of a fluid.
[0006] In contrast to the guidewire which serves as a track over
which other intravascular devices are routed, a stylet is used
within an internal lumen of an intravascular device both to push
that device through the vascular system and to steer the device as
it is being pushed. Although some intravascular devices are
designed to steer themselves using internal pull wires, almost all
leads, most catheters and some guidewires have an inner channel or
lumen into which a stylet is inserted. In addition to pushing the
intravascular device through the vascular system by engaging the
distal end of the device, the stylet also serves to deflect the
distal end of the intravascular device so as to steer the distal
end through the vascular system. Unlike the lead, catheter or
guidewire, which has a distal region that is flexible and floppy,
the stylet must be stiffer and more rigid so as to enable the
stylet to push the lead or catheter through the patient's vascular
system. Conventionally, stylets having different bends on the
distal end are used at different points of advancing the lead or
catheter to a desired location. For straight segments of a vessel a
straight stylet is used, whereas a stylet with a curved distal tip
is used to navigate the lead or catheter through a curved portion
of a vessel. U.S. Pat. No. 2,118,631 shows an early stylet formed
of coils of flat wire welded to plugs at both ends that could be
bent by the physician into either a straight or curved
configuration at its distal end prior to insertion into the lumen
of a catheter or the like. In a more recent type of stylet, an
operator controls the direction of deflection of the tip of the
stylet while it is in place in the lumen, which in turn controls
the direction of the cardiac lead or catheter as it is moved along
the veins or arteries. An example of a stylet with such a
deflecting tip is shown in U.S. Pat. No. 5,824,031. Other examples
of steerable stylets can be found in U.S. Pat. No. 5,873,842 and
PCT Publ. No. WO 00/22981.
[0007] The more control and flexibility an operator has over an
intravascular device, the easier it is to operate that device. In
the case of stylets, the physical demands of engaging the distal
end of a lumen of an intravascular device so as to push that device
through the vascular system impose constraints on the beam strength
of the device that are much different than the constraints
encountered for a guidewire, catheter or lead. Most guidewires are
constructed from a tapered core wire with a coiled round wire
wrapped around this tapered core wire in order to achieve the
necessary flexibility in the distal region of the guidewire.
Stylets, on the other hand, are generally constructed of a solid
wire of uniform diameter without any coils around this wire in
order to achieve the necessary strength and rigidity required over
the entire length of the device so as to function as a stylet.
Because of these differences, the techniques for improving control
and flexibility that have been utilized for guidewires, catheters
and leads are not generally applicable for the design of stylets.
It would be desirable to provide for a stylet with improved
flexibility and control without the need for changing stylets
during a procedure to obtain different orientations of the distal
tip of the stylet.
SUMMARY OF THE INVENTION
[0008] The present invention is an adjustable stylet. The stylet
includes a core wire having a portion surrounded by a compression
member preferably comprised of a flat wire spring. Depending upon
the configuration, compression or relaxation of the compression
member in response to forces at the tip or handle of the stylet
results in adjustments to the characteristics of the stylet. In a
first embodiment, the stiffness of the stylet is adjustable. In a
second embodiment, the length of the stylet is adjustable. In a
third embodiment, both the stiffness and the length of the stylet
are adjustable.
[0009] Unlike most guidewires that are so flexible the guidewire
will fall over when grasped only by the ends, the stylet in
accordance with the present invention requires a much greater
rigidity such that the stylet forms an arc that generally stands up
and does not fall over when the stylet is grasped only by the ends.
The present invention utilizes a core wire that has a relatively
uniform beam strength over its axial length so as to provide the
necessary rigidity and strength required for a stylet. The
compression member augments the characteristics of the core wire in
a manner that is adjustable so as to also be able to more closely
emulate the desired characteristics of an adjustable guidewire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of an adjustable stiffness stylet in a
relaxed state.
[0011] FIG. 2 is a side view of the adjustable stiffness stylet of
FIG. 1 in a compressed state.
[0012] FIG. 3 is a side view of an alternative embodiment of the
adjustable stiffness stylet.
[0013] FIG. 4 is a partial side view of an adjustable length
stylet.
[0014] FIG. 5 is a cutaway partial side view of the adjustable
length stylet of FIG. 4.
[0015] FIGS. 6a, 6b and 6c are side views of the component pieces
of the adjustable length stylet of FIG. 4.
[0016] FIGS. 7 and 8 show cutaway partial sides views of alternate
embodiments of the handle for the adjustable stiffness stylet of
FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Referring to FIG. 1, an adjustable stiffness stylet 10
comprises a stylet core wire 12, a space wound flat wire spring or
compression member 14, a sliding handle 16 located at a proximal
end 18 of the core wire 12 and a tip 20 of the core wire 12.
Preferably, the compression member 14 is welded, crimped or
otherwise secured to the core wire 12 near the tip 20. Preferably,
the space wound compression member 14 has an inner diameter (I.D.)
that is just slightly larger than the outer diameter (O.D) of the
core wire 12. Optionally, a cover tube (not shown) may be secured
over the exterior so long as the tube does not interfere with the
movement of compression member 14.
[0018] As the sliding handle 16 is pushed toward the tip 20, the
handle 16 makes contact with the proximal end of compression member
14 but does not slide over compression member 14. Compression
member 14 is compressed in response and the overall flexibility of
the stylet 10 begins to stiffen. As more force is applied to the
handle 16, the open windings of compression member 14 close and the
stiffness of stylet 10 is increased as shown in FIG. 2. When the
desired stiffness is achieved, the operator may advance stylet 10
without altering the stiffness by applying force to the proximal
end 18 of the core wire 12 without displacing the position of
handle 16 relative to the compression member 14. Alternatively,
handle 16 may be provided with locking mechanisms to lock the
handle 16 in a given position relative to core wire 12, or proximal
end 18 of the core wire 12 may be equipped with a separate handle.
Handle 16 preferably is slide operated along the longitudinal axis
of core wire 12, although it will be understood that handle 16 also
could operate in a screw manner (as shown in FIG. 7) or ratchet
manner (as shown in FIG. 8) along the longitudinal axis of core
wire 12.
[0019] FIG. 3 shows an alternate embodiment of an adjustable stylet
22 in which a rigid tube 24 is located between the handle 16 and
the compression member 14. In this case, compression member 14 is
secured to the tip 20 of the core wire 12 and the resulting stylet
has a flexible tip portion corresponding to the length of the core
wire 12 surrounded by compression member 14. As the handle 16 is
pushed toward the tip 20, the tube 24 is pushed into the proximal
end of the compression member 14 and the space wound coils of
compression member 14 are compressed, thereby increasing the
stiffness of the stylet 22.
[0020] Referring now to FIG. 4, a second embodiment of an
adjustable stylet 30 comprises a proximal core wire 32, a
compression member 34 (FIG. 5), a distal core wire 36 and a cover
tube 38. The cover tube 38 is welded to the proximal core wire 32,
but not to the distal core wire 36. The compression member 34 is
preferably a space wound flat wire spring that is welded, crimped
or otherwise secured to the adjacent ends of the proximal core wire
32 and the distal core wire 36. As shown in FIGS. 6b and 6c, the
stylet core wire is preferably centerless ground at the adjacent
ends of the proximal core wire 32 and distal core wire 36 to all
several turns of the compression member 34 to be centered on each
core wire 32, 36.
[0021] Preferably, the distal core wire segment 36 is relatively
short in comparison to the proximal core wire 32, although the
lengths of the core wire segments 32 and 36 may be various lengths.
In this embodiment, the compression member 34 is compressed and the
overall effective length of the stylet 30 is shortened in response
to a compressive force exerted at the distal end of the distal core
wire 36. The ability of the stylet 30 to adjust in length reduces
the need for stocking and maintaining a variety of different length
stylets.
[0022] In a third embodiment, the stylet 30 is used as the core
wire 12 of the stylet 10 to combine both of the adjustable
qualities of the present invention in a single embodiment.
[0023] FIGS. 7 and 8 show alternate embodiments for the handle of
the adjustable stiffness stylet of FIG. 1 in partial
cross-sectional views. In FIG. 7, the proximal end of the stylet
core wire 39 is threaded to accept a threaded handle 40. The
stiffness of the stylet 10 is increased by compressing the
compressive member 14 through turning of the threaded handle 40
clockwise to move the handle 40 away from the threaded proximal end
of the stylet core wire 39. Similarly, the stiffness of the stylet
10 may be decreased by decompressing the compressive member 14
through turning the threaded handle 40 counterclockwise toward the
threaded proximal end of the stylet core wire 39.
[0024] Referring now to FIG. 8, the proximal end 18 of the core
wire 12 of the adjustable stiffness stylet 10 is welded or
otherwise secured to the bottom part 41 of a multi-piece handle 42
that has a tongue 43. The tongue 42 engages slots 44 of the top
part 45 of a multi-piece handle 42, which has an aperture 46 whose
inside diameter is slightly larger than the outside diameter of the
stylet core wire 12 to allow the stylet core wire 12 to freely
slide through the top part 45 of the multi-piece handle 42. The
stiffness of the stylet 10 is accomplished through compression of
the compressive member 14 by pulling the bottom part 41 of the
multi-piece handle 42 toward the proximal end of the core wire 18
in relation to the top part 45 of the multi-piece handle 42.
Correspondingly, the stiffness of the stylet 10 can be decreased
through relieving compression of the compressive member 14 by
pushing the bottom part 41 of the multi-piece handle 42 away from
the proximal end of the core wire 18 in relation to the top part 45
of the multi-piece handle 42. Once the desired stiffness of the
stylet 10 has be accomplished by placement of the top part 45 and
bottom part 41 of the multi-piece handle 42, the tongue 43 on the
bottom part 41 engages a slot 44 on the top part 45 of the
multi-piece handle 42 to maintain the chosen stiffness.
[0025] The core wire 12 is preferably a stainless steel wire having
an outer diameter of less than 0.020 inches and preferably in a
range between 0.005 and 0.018 inches and in the preferred
embodiment approximately 0.014 inches. Above this range, the
diameter of the core wire is generally too large to effectively
serve as a stylet for insertion in the lumens of most intravascular
devices. The physical characteristics of core wire 12 must be
suitable for use as a stylet, as opposed to use as a guidewire.
Most importantly, the core wire 12 should have a relatively uniform
beam strength over its axial length so as to provide the necessary
rigidity and strength required for a stylet. By relatively uniform
it is understood that manufacturing tolerances or even minor
variations in beam strength of less than about +/-10% would be
considered relatively uniform in terms of the beam strength of the
core wire. The tensile strength of the wire should be at least 150K
psi and preferably in a range between 200K psi and 400K psi.
Alternative wires suitable for core wire 12 include MP35N, AC10
tungsten, or Nintonal. With existing technologies for wound wire or
braided wire, it is not possible to utilize such wires for the core
wire 12 in accordance with the present invention because these
wires do no exhibit the desired characteristics. As such, the core
wire 12 is preferably a solid round wire having a relatively
uniform cross-sectional diameter over its axial length.
[0026] The compression member 14 is preferably a flat or ribbon
wire made of stainless steel or a similar material. The compression
member preferably has an aspect ratio of at least 2:1. While the
wider cross-sectional dimension of the flat wire can vary anywhere
above the lower range of the aspect ratio, preferably the narrow
cross-sectional dimension of the flat wire is less than 0.003
inches.
[0027] In the embodiment of the adjustable length stylet 30, the
principle advantage of this feature is its use in those situations
where the length of stylet must be held to very tight tolerances.
Typically, the stylet 30 is inserted into an intravascular device
within a sterile field prior to insertion in the patient's vascular
system with the proximal ends of the stylet 30 and intravascular
device locked together with a Luer lock or the like. In some
applications, such as neurological applications, the tolerances for
the match between the length of the lumen of the intravascular
device and the length of the stylet 30 must be within less than
0.010 inches. The ability to adjust the length of the stylet 30
reduces the need for tight tolerance matches between these lengths,
thereby affording more interchangeability between stylets and
intravascular devices.
* * * * *