U.S. patent application number 11/797328 was filed with the patent office on 2007-10-04 for guide wire.
This patent application is currently assigned to TERUMO KABUSHIKI KAISHA. Invention is credited to Youki Aimi, Yutaka Itou, Jun Iwami, Hiraku Murayama, Akihiko Umeno.
Application Number | 20070232957 11/797328 |
Document ID | / |
Family ID | 30449194 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070232957 |
Kind Code |
A1 |
Murayama; Hiraku ; et
al. |
October 4, 2007 |
Guide wire
Abstract
A guide wire includes a first wire disposed on the distal side,
and a second wire disposed on the proximal side and made from a
material having an elastic modulus larger than that of the first
wire. The first wire and the second wire are joined to each other
by welding. The second wire has, in the vicinity of the welded
portion, a small cross-sectional area portion having a
cross-sectional area smaller than that of a proximal end portion of
the first wire. The outer diameter of the small cross-sectional
area portion is gradually reduced in the direction toward the
distal end. The first wire may be made from a superelastic alloy,
whereas the second wire may be made from a stainless steel. The
first wire and the second wire may be welded to each other by a
butt resistance welding process. Since the change in rigidity of
the guide wire becomes smooth in the longitudinal direction, the
operationality and kink resistance of the guide wire are
improved.
Inventors: |
Murayama; Hiraku;
(Fujinomiya-shi, JP) ; Umeno; Akihiko;
(Fujinomiya-shi, JP) ; Iwami; Jun;
(Fujinomiya-shi, JP) ; Itou; Yutaka;
(Fujinomiya-shi, JP) ; Aimi; Youki;
(Fujinomiya-shi, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
TERUMO KABUSHIKI KAISHA
|
Family ID: |
30449194 |
Appl. No.: |
11/797328 |
Filed: |
May 2, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10635716 |
Aug 7, 2003 |
|
|
|
11797328 |
May 2, 2007 |
|
|
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Current U.S.
Class: |
600/585 |
Current CPC
Class: |
A61M 25/09 20130101;
B21F 15/08 20130101; A61M 25/09033 20130101; A61M 2025/0915
20130101; A61M 2025/09083 20130101 |
Class at
Publication: |
600/585 |
International
Class: |
A61M 25/01 20060101
A61M025/01 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2002 |
JP |
2002-232164 |
Dec 6, 2002 |
JP |
2002-355908 |
May 30, 2003 |
JP |
2003-156011 |
Claims
1. A guide wire comprising: a first wire disposed on the distal
side of said guide wire; and a second wire disposed on the proximal
side from said first wire, said second wire being made from a
material having an elastic modulus larger than that of said first
wire; wherein said first wire and second wire are joined to each
other by welding; and said second wire has, in the vicinity of a
welded portion between said first wire and said second wire, a
small cross-sectional area portion having a cross-sectional area
smaller than a cross-sectional area of a proximal end portion of
said first wire.
2. A guide wire according to claim 1, further comprising a cover
layer disposed over at least said welded portion.
3. A guide wire according to claim 1, wherein said small
cross-sectional area portion has an outer diameter smaller than an
outer diameter of the proximal end portion of said first wire.
4. A guide wire according to claim 1, wherein said small
cross-sectional area portion includes a portion having a
cross-sectional area gradually reduced in the direction toward the
distal end of said guide wire.
5. A guide wire according to claim 1, wherein said small
cross-sectional area portion includes a portion having an
outer-diameter gradually reduced in the direction toward the distal
end of said guide wire.
6. A guide wire according to claim 1, wherein said small
cross-sectional area portion includes a first portion having an
outer diameter gradually reduced in the direction toward the distal
end of said guide wire, and a second portion having an outer
diameter gradually increased in the direction toward the distal end
of said guide wire, said second portion being disposed on said
distal side from said first portion.
7. A guide wire according to claim 6, wherein said small
cross-sectional area portion has a third portion having a nearly
constant outer diameter, said third portion being disposed between
said first portion and said second portion.
8. A guide wire according to claim 6, wherein said first portion
has a length in a range of 0.1 to 1,000 times a length of said
second portion.
9. A guide wire according to claim 7, wherein said first portion
has a length in a range of 0.1 to 1,000 times a length of said
second portion.
10. A guide wire according to claim 1, wherein a flexural rigidity
of the distal end of said second wire is nearly equal to a flexural
rigidity of the proximal end of said first wire.
11. A guide wire according to claim 1, further comprising a step
filling member for filling a stepped portion formed on the outer
periphery of said welded portion.
12. A guide wire comprising: a first wire disposed on the distal
side of said guide wire; and a second wire disposed on the proximal
side from said first wire, said second wire having rigidity higher
than a rigidity of said first wire; wherein said first wire and
said second wire are joined to each other by welding, and a welded
portion formed by welding has a projection projecting in the outer
peripheral direction; and said second wire has, in the vicinity of
a welded portion between said first wire and said second wire, a
small cross-sectional area portion having a cross-sectional area
smaller than a cross-sectional area of a proximal end portion of
said first wire.
13. A guide wire according to claim 12, further comprising a cover
layer disposed over at least said welded portion.
14. A guide wire according to claim 12, wherein said small
cross-sectional area portion has an outer diameter smaller than an
outer diameter of the proximal end portion of said first wire.
15. A guide wire according to claim 12, wherein said small
cross-sectional area portion includes a portion having a
cross-sectional area gradually reduced in the direction toward the
distal end of said guide wire.
16. A guide wire according to claim 12, wherein said small
cross-sectional area portion includes a portion having an
outer-diameter gradually reduced in the direction toward the distal
end of said guide wire.
17. A guide wire according to claim 12, wherein said small
cross-sectional area portion includes a first portion having an
outer diameter gradually reduced in the direction toward the distal
end of said guide wire, and a second portion having an outer
diameter gradually increased in the direction toward the distal end
of said guide wire, said second portion being disposed on said
distal side from said first portion.
18. A guide wire according to claim 17, wherein said small
cross-sectional area portion has a third portion having a nearly
constant outer diameter, said third portion being disposed between
said first portion and said second portion.
19. A guide wire according to claim 17, wherein said first portion
has a length in a range of 0.1 to 1,000 times a length of said
second portion.
20. A guide wire according to claim 18, wherein said first portion
has a length in a range of 0.1 to 1,000 times a length of said
second portion.
21. A guide wire according to claim 12, wherein a flexural rigidity
of the distal end of said second wire is nearly equal to a flexural
rigidity of the proximal end of said first wire.
22. A guide wire according to claim 12, further comprising a step
filling member for filling a stepped portion formed on the outer
periphery of said welded portion.
Description
[0001] This application is a divisional of prior application Ser.
No. 10/635,716 filed on Aug. 7, 2003, the entire content of which
is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a guide wire, particularly
to a guide wire used to guide a catheter in a body lumen such as a
blood vessel.
[0004] 2. Description of the Related Art
[0005] Guide wires are used to guide a catheter in treatment of
cites at which open surgeries are difficult or which require
minimally invasiveness to the body, for example, PTCA (Percutaneous
Transluminal Coronary Angioplasty), or in examination such as
cardio-angiography. A guide wire used in the PTCA procedure is
inserted, with the distal end projecting from the distal end of a
balloon catheter, into the vicinity of a target angiostenosis
portion together with the balloon catheter, and is operated to
guide the distal end portion of the balloon catheter to the target
angiostenosis portion.
[0006] A guide wire used to insert a catheter into a blood vessel
complicatedly bent requires appropriate flexibility and restoring
performance against bending, pushability and torque transmission
performance (generically called "operationality") for transmitting
an operational force from the proximal end portion to the distal
side, and kink resistance (often called "resistance against sharp
bending"). To obtain appropriate flexibility as one of the
above-described performances, there has been known a guide wire
configured such that a metal coil having flexibility is provided
around a small-sized core member at the distal end of the guide
wire, or a guide wire including a core member made from a
superelastic material such as an Ni--Ti alloy for improving the
flexibility and restoring performance.
[0007] Conventional guide wires include a core member that is
substantially made from a single material. In particular, to
enhance the operationality of the guide wire, a material having a
relatively high elastic modulus is used as the material of the core
member. The guide wire including such a core member, however, has
an inconvenience that the distal end portion of the guide wire
becomes lower in flexibility. On the other hand, if a material
having a relatively low elastic modulus is used as the material of
the core member for increasing the flexibility of the distal end
portion of the guide wire, the operationality of the proximal end
portion of the guide wire is degraded. In this way, it has been
regarded as difficult to satisfy both requirements associated with
the flexibility and operationality by using a core member made from
a single material.
[0008] A guide wire intended to solve such a problem has been
disclosed, for example, in U.S. Pat. No. 5,171,383, wherein a
Ni--Ti alloy wire is used as a core member, and the distal side and
the proximal side of the alloy wire are heat-treated under
different conditions in order to enhance the flexibility of the
distal end portion of the alloy wire while enhancing the rigidity
of the proximal side of the alloy wire. Such a guide wire, however,
has a problem that the control of the flexibility of the distal end
portion by heat-treatment has a limitation. For example, even if it
is successful to obtain a sufficient flexibility of the distal end
portion of the alloy wire, it may often fail to obtain a sufficient
rigidity on the proximal side of the alloy wire.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a guide
wire capable of making the change in rigidity smooth in the
longitudinal direction of the guide wire, thereby improving the
operationality and kink resistance of the guide wire.
[0010] To achieve the above object, according to a first aspect of
the present invention, there is provided a guide wire including a
first wire disposed on the distal side of the guide wire, and a
second wire disposed on the proximal side from the first wire, the
second wire being made from a material having an elastic modulus
larger than that of the first wire, wherein the first wire and
second wire are joined to each other by welding, and the second
wire has, in the vicinity of a welded portion between the first
wire and the second wire, a small cross-sectional area portion
having a cross-sectional area smaller than a cross-sectional area
of a proximal end portion of the first wire.
[0011] According to a second aspect of the present invention, there
is provided a guide wire including a first wire disposed on the
distal side of the guide wire, and a second wire disposed on the
proximal side from the first wire, the second wire having a
rigidity higher than a rigidity of the first wire, wherein the
first wire and the second wire are joined to each other by welding,
and a welded portion formed by welding has a projection projecting
in the outer peripheral direction, and the second wire has, in the
vicinity of a welded portion between the first wire and the second
wire, a small cross-sectional area portion having a cross-sectional
area smaller than a cross-sectional area of a proximal end portion
of the first wire.
[0012] Each of the guide wires according to the first and second
aspects of the present invention may be further configured as
follows.
[0013] The guide wire preferably includes a cover layer disposed
over at least the welded portion.
[0014] The small cross-sectional area portion preferably has an
outer diameter smaller than an outer diameter of the proximal end
portion of the first wire.
[0015] The small cross-sectional area portion preferably includes a
portion having a cross-sectional area gradually reduced in the
direction toward the distal end of the guide wire.
[0016] The small cross-sectional area portion preferably includes a
portion having an outer-diameter gradually reduced in the direction
toward the distal end of the guide wire.
[0017] The small cross-sectional area portion preferably includes a
first portion having an outer diameter gradually reduced in the
direction toward the distal end of the guide wire, and a second
portion having an outer diameter gradually increased in the
direction toward the distal end of the guide wire, the second
portion being disposed on the distal side from the first
portion.
[0018] The small cross-sectional area portion preferably has a
third portion having a nearly constant outer diameter, the third
portion being disposed between the first portion and the second
portion.
[0019] The first portion preferably has a length in a range of 0.1
to 1,000 times a length of the second portion.
[0020] A flexural rigidity of the distal end of the second wire is
preferably nearly equal to a flexural rigidity of the proximal end
of the first wire.
[0021] The guide wire preferably further includes a step filling
member for filling a stepped portion formed on the outer periphery
of the welded portion.
[0022] An outer peripheral surface of a boundary portion between
the first portion and the second portion may form a continuous
curved plane without any stepped portion.
[0023] Each of an outer peripheral surface of a boundary portion
between the first portion and the third portion and an outer
peripheral surface of a boundary portion between the third portion
and the second portion may form a continuous curved plane without
any stepped portion.
[0024] The first wire may be made from a superelastic alloy.
[0025] The second wire may be made from a stainless steel.
[0026] The second wire may be made from a Co-based alloy.
[0027] The Co-based alloy may be a Co--Ni--Cr alloy.
[0028] Each of a connection end face of the first wire to the
second wire and a connection end face of the second wire to the
first wire may be nearly perpendicular to the axial direction of
the first and second wires.
[0029] The guide wire may further include a spiral coil covering at
least a distal end portion of the first wire.
[0030] The welded portion may be located on the proximal side from
the proximal end of the coil.
[0031] The first wire and the second wire may be welded to each
other by a butt resistance welding process.
[0032] The guide wire may be used in such a manner that the welded
portion be located in a living body.
[0033] As described above, since the guide wire of the present
invention has the first wire disposed on the distal side and the
second wire disposed on the proximal side from the first wire and
made from a material having an elastic modulus larger than that of
the first wire, it is possible to ensure a high rigidity at a
proximal end portion while keeping a high flexibility at a distal
end portion, and hence to enhance the pushability, torque
transmission performance, and trackability of the guide wire.
[0034] Since the first wire and the second wire are joined to each
other by welding, it is possible to enhance the joining strength of
the joining portion (welded portion), and hence to certainly
transmit a torsional torque or pushing force from the second wire
to the first wire.
[0035] Since the small cross-sectional area portion is provided on
the second wire, it is possible to make the change in rigidity of
the welded portion and its neighborhood smooth in the longitudinal
direction, and hence to certainly prevent kink (sharp bending) or
torsion of a portion in the vicinity of the welded portion.
[0036] Since the shape of the small cross-sectional area portion is
contrived, for example, in such a manner that the small
cross-sectional area portion is divided into two parts (first and
second portions) or three parts (first, second, and third
portions), it is possible to enhance the welding strength of the
welded portion, and to relieve or disconcentrate local stress
concentration at the small cross-sectional area portion and hence
to more certainly prevent kink and torsion.
[0037] Accordingly, the present invention can provide a guide wire
excellent in operationality, kink resistance, and torsion
resistance.
[0038] With the configuration that the projection is formed on the
welded portion, it is possible to further enhance the joining
strength of the joining portion (welded portion) and hence to more
certainly transmit a torsional torque or pushing force from the
second wire to the first wire.
[0039] With the configuration that the cover layer is made from a
material capable of reducing the friction of the cover layer, it is
possible to improve the sliding resistance of the guide wire in a
catheter and hence to further enhance the operationality of the
guide wire. Since the sliding resistance of the guide wire is
reduced, it is possible to more certainly prevent kink (sharp
bending) and torsion of the guide wire, particularly, in the
vicinity of the welded portion.
[0040] By changing materials used for the cover layer at respective
portions, it is possible to enhance the sliding resistance at each
of the portions and hence to expand the versability for an
operator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] These and other objects, features, and advantages of the
present invention will become more apparent from the following
detailed description in conjunction with the accompanying drawings,
wherein:
[0042] FIG. 1 is a longitudinal sectional view showing a first
embodiment of a guide wire of the present invention;
[0043] FIGS. 2A to 2C are views showing steps of a procedure for
connecting a first wire and a second wire of the guide wire shown
in FIG. 1;
[0044] FIG. 3 is a typical view illustrating an example of how to
use the guide wire of the present invention;
[0045] FIG. 4 is a typical view illustrating the example of how to
use the guide wire of the present invention;
[0046] FIG. 5 is a longitudinal sectional view showing a
modification of a small cross-sectional area portion of the guide
wire of the present invention;
[0047] FIG. 6 is a longitudinal sectional view showing another
modification of a small cross-sectional area portion of the guide
wire of the present invention;
[0048] FIG. 7 is a longitudinal sectional view showing a second
embodiment of the guide wire of the present invention; and
[0049] FIGS. 8A and 8B are perspective views showing further
modifications of the small cross-sectional area portion of a second
wire of the guide wire of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] A guide wire of the present invention will now be described
in detail by way of preferred embodiments shown in the accompanying
drawings.
[0051] FIG. 1 is a longitudinal sectional view of a first
embodiment of a guide wire of the present invention, and FIGS. 2A
to 2C are views showing a procedure for joining a first wire and a
second wire of the guide wire shown in FIG. 1 to each other. For
convenience of description, the right side in FIG. 1 is taken as
the "proximal side" and the left side in FIG. 1 is taken as the
"distal side". It is to be noted that in FIG. 1 (and in FIGS. 5 to
7 to be described later), for easy understanding, the dimension of
the guide wire in the thickness direction is exaggeratedly enlarged
while the dimension of the guide wire in the length direction is
shortened, and therefore, the ratio of the thickness to the length
is significantly different from the actual ratio.
[0052] A guide wire 1 shown in FIG. 1, which is of a type used to
be inserted in a catheter, includes a first wire 2 disposed on the
distal side, a second wire 3 disposed on the proximal side from the
first wire 2, and a spiral coil 4. The entire length of the guide
wire 1 is not particularly limited but is preferably in a range of
about 200 to 5,000 mm. The outer diameter of the guide wire 1 is
not particularly limited but is preferably in a range of about 0.2
to 1.2 mm.
[0053] The first wire 2 is configured as a wire member having
elasticity. The length of the first wire 2 is not particularly
limited but is preferably in a range of about 20 to 1,000 mm.
[0054] According to this embodiment, the first wire 2 has, at its
distal end portion, an outer-diameter gradually reducing portion 22
with its outer diameter gradually reduced in the direction toward
the distal end. In the outer-diameter gradually reducing portion 22
of the first wire 2, therefore, the rigidity (flexural rigidity,
torsional rigidity) is gradually reduced in the direction toward
the distal end. As a result, it is possible to enhance the
flexibility of the distal end portion of the guide wire 1, and
hence to improve the follow-up performance and safety to a blood
vessel and also to prevent sharp-bending and the like.
[0055] In the configuration shown in the figure, the first wire 2
has, nearly over the entire length, a taper shape in which the
outer diameter is continuously, gradually reduced in the direction
toward the distal end. The taper angle of the taper portion of the
first wire 2 may be kept constant or changed along the longitudinal
direction.
[0056] According to this embodiment, the outer-diameter gradually
reducing portion 22 is tapered such that the outer diameter is
continuously reduced with a nearly constant reduction ratio in the
direction toward the distal end. In other words, the taper angle of
the outer-diameter gradually reducing portion 22 is kept nearly
constant along the longitudinal direction. In the outer-diameter
gradually reducing portion 22, therefore, the change in rigidity
becomes more moderate (or smooth) along the longitudinal direction.
Unlike such a configuration, the reduction ratio of the outer
diameter of the outer-diameter gradually reducing portion 22 (taper
angle of the outer-diameter gradually reducing portion 22) may be
changed along the longitudinal direction. For example, portions in
each of which the reduction ratio of the outer diameter is
relatively large and portions in each of which the reduction ratio
of the outer diameter is relatively small may be alternately
repeated by a plurality of numbers. In this case, the
outer-diameter gradually reducing portion 22 may have a portion in
which the reduction ratio of the outer diameter in the direction
toward the distal end becomes zero.
[0057] The outer diameter of a proximal end portion of the first
wire 2 is kept nearly constant along the longitudinal direction.
Unlike the configuration shown in the figure, the outer diameter of
nearly the whole of the first wire 2 may be gradually reduced in
the direction toward the distal end. In other words, nearly the
whole of the first wire 2 may be composed of the outer-diameter
gradually portion 22.
[0058] The material for forming the first wire 2 is not
particularly limited but may be selected from metal materials such
as stainless steels. In particular, alloys having pseudo-elasticity
(for example, superelastic alloys) are preferable, and superelastic
alloys are more preferable. Superelastic alloys are relatively
flexible, good in restoring performance, and less susceptible to
reforming. Accordingly, if the first wire 2 is made from a
superelastic alloy, the guide wire 1 including such a first wire 2
has, at its distal portion, a high flexibility and a high restoring
performance against bending, and a high trackability to a blood
vessel complicatedly curved or bent, to thereby enhance the
operationality of the guide wire 1. Even if the first wire 2 is
repeatedly deformed, that is, curved or bent, the first wire 2 is
no or less plastic deforming because of its high restoring
performance. This prevents degradation of the operationality due to
the plastic deforming of the first wire 2 during use of the guide
wire 1.
[0059] Pseudo-elastic alloys include those of a type in which the
stress-strain curve in a tensile test has any shape, those of a
type in which a transformation point such as As, Af, Ms, or Mf can
be significantly measured or not measured, and those of all types
in which the shape is greatly deformed by stress and then restored
nearly to an original shape by removal of stress.
[0060] Examples of superelastic alloys include Ni--Ti alloys such
as an Ni--Ti alloy containing Ni in an amount of 49-52 atomic %, a
Cu--Zn alloy containing Zn in an amount of 38.5 to 41.5 wt %, a
Cu--Zn--X alloy containing X in an amount of 1 to 10 wt % (X: at
least one kind selected from a group consisting of Be, Si, Sn, Al,
and Ga), and an Ni--Al alloy containing Al in an amount of 36 to 38
atomic %. Of these materials, the Ni--Ti alloy is preferable.
[0061] The distal end of the second wire 3 is joined to the
proximal end of the first wire 2. The second wire 3 is a wire
member having elasticity. The length of the second wire 3 is not
particularly limited but may be in a range of about 20 to 4,800
mm.
[0062] The second wire 3 is made from a material having an elastic
modulus (Young's modulus or modulus of longitudinal elasticity,
modulus of rigidity or modulus of transverse elasticity, or bulk
modulus) larger than that of the first wire 2. The second wire 3
can thus exhibit an appropriate rigidity (flexural rigidity,
torsional rigidity). As a result, the guide wire 1 becomes firm, to
improve the pushability and torque transmission performance,
thereby enhancing the operationality at the time of insertion of
the guide wire 1.
[0063] The material for forming the second wire 3 is not
particularly limited but may be selected from metal materials, for
example, stainless steels (all kinds specified in SUS, for example,
SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405,
SUS430, SUS434, SUS444, SUS429, SUS430F, and SUS302), piano wire
steels, cobalt alloys, and alloys having pseudo-elasticity.
[0064] In particular, cobalt alloys are preferably used for the
second wire 3. This is because the second wire 3 made from a cobalt
alloy has a high elastic modulus and an appropriate elastic limit.
Such a second wire 3 exhibits a good torque transmission
performance, thereby hardly causing a problem associated with
buckling or the like. Any type of cobalt alloy may be used insofar
as it contains cobalt. In particular, a cobalt alloy containing
cobalt as a main component (that is, a cobalt-based alloy
containing cobalt in an amount [in wt %] being the largest among
the contents of all components of the alloy) is preferably used,
and further, a Co--Ni--Cr alloy is more preferable. The use of the
cobalt alloy having such a composition as the material for forming
the second wire 3 is effective to further enhance the
above-described effects. The cobalt alloy having such a composition
is also advantageous in that since the alloy exhibits plasticity in
deformation at room temperature, the second wire 3 made from such a
cobalt alloy is easily deformable into a desired shape, for
example, during use of the guide wire. A further advantage of the
cobalt alloy having such a composition is as follows: namely, since
the second wire 3 made from such a cobalt alloy has a high elastic
modulus and is cold-formable even if it exhibits a high elastic
limit, the second wire 3 can be thinned while sufficiently
preventing occurrence of buckling, and therefore, can exhibit a
high flexibility and a high rigidity enough to be inserted into a
desired site.
[0065] The Co--Ni--Cr alloy is exemplified by an alloy containing
28-50 wt % of Co, 10-30 wt % of Ni, and 10-30 wt % of Cr, the
balance being Fe. In this alloy, part of any component may be
substituted by another element (substitution element). The
incorporation of such a substitution element exhibits an effect
inherent to the kind thereof. For example, the incorporation of at
least one kind selected from a group consisting of Ti, Nb, Ta, Be,
and Mo further improves the strength of the second wire 3. In the
case of incorporating one or more substitution elements other than
Co, Ni, and Cr, the total content of the substitution elements is
preferably in a range of 30 wt % or less.
[0066] For example, part of Ni may be substituted by Mn, which is
effective to further improve the workability. Part of Cr may be
substituted by Mo and/or W, which is effective to further improve
the elastic limit. Of the Co--Ni--Cr alloys, a Co--Ni--Cr--Mo alloy
is particularly preferable.
[0067] Examples of compositions of the Co--Ni--Cr alloys include
(1) 40 wt % Co-22 wt % Ni-25 wt % Cr-2 wt % Mn-0.17 wt % C-0.03 wt
% Be--Fe (balance), (2) 40 wt % Co-15 wt % Ni-20 wt % Cr-2 wt %
Mn-7 wt % Mo-0.15 wt % C-0.03 wt % Be--Fe (balance), (3) 42 wt %
Co-13 wt % Ni-20 wt % Cr-1.6 wt % Mn-2 wt % Mo-2.8 wt % W-0.2 wt %
C-0.04 wt % Be--Fe (balance), (4) 45 wt % Co-21 wt % Ni-18 wt %
Cr-1 wt % Mn-4 wt % Mo-1 wt % Ti-0.02 wt % C-0.3 wt % Be--Fe
(balance), and (5) 34 wt % Co-21 wt % Ni-14 wt % Cr-0.5 wt % Mn-6
wt % Mo-2.5 wt % Nb-0.5 wt % Ta--Fe (balance). The wording
"Co--Ni--Cr alloy" used herein is the conception including these
Co--Ni--Cr alloys.
[0068] If a stainless steel is used as the material for forming the
second wire 3, the pushability and torque transmission performance
of the guide wire 1 can be further enhanced.
[0069] The first wire 2 and the second wire 3 may be made from
different alloys, and particularly, the first wire 2 is preferably
made from a material having an elastic modulus smaller than that of
the material of the second wire 3. With this configuration, the
distal end portion of the guide wire 1 has a high flexibility, and
the proximal end portion of the guide wire 1 has a high rigidity
(flexural rigidity, torsional rigidity). As a result, the guide
wire 1 has a high pushability and a high torque transmission
performance, thereby enhancing the operationality, and also
exhibits, on the distal side, a high flexibility and a high
restoring performance, thereby improving trackability and safety to
a blood vessel.
[0070] As one preferred combination of materials of the first wire
2 and the second wire 3, the first wire 2 is made from a
superelastic alloy and the second wire 3 is made from a Co--Ni--Cr
alloy or a stainless steel. With this configuration, the
above-described effects become more significant.
[0071] From the viewpoint of enhancing the flexibility and
restoring performance of the distal end portion of the first wire
2, it is preferred to use a Ni--Ti alloy as the superelastic alloy
for forming the first wire 2.
[0072] The coil 4 is a member formed by spirally winding a wire,
particularly a fine wire, and is provided so as to cover the distal
end portion of the first wire 2. In the configuration shown in FIG.
1, the distal end portion of the first wire 2 is disposed in an
approximately axially center portion of the coil 4 in such a manner
as to be not in contact with the inner surface of the coil 4. It is
to be noted that in the configuration shown in FIG. 1, the coil 4
is loosely disposed in such a manner that a slight gap remains
between adjacent spirally wound wire portions in a state that no
external force is applied to the coil 4; however, the coil 4 may be
tightly disposed in such a manner that no gap remains between the
adjacent spirally wound wire portions in a state that no external
force is applied to the coil 4.
[0073] The coil 4 may be made from a metal material such as a
stainless steel, a superelastic alloy, a cobalt alloy, a noble
metal such as gold, platinum, or tungsten, or an alloy containing
such a noble metal. In particular, the coil 4 is preferably made
from a radiopaque material such as a noble metal. If the coil 4 is
made from such a radiopaque material, the guide wire 1 can exhibit
an X-ray contrast performance. This makes it possible to insert the
guide wire 1 in a living body while confirming the position of the
distal end portion of the guide wire 1 under fluoroscopy. The
distal side and proximal side of the coil 4 may be made from
different alloys. For example, the distal side of the coil 4 may be
formed of a coil made from a radiopaque material and the proximal
side of the coil 4 be formed of a coil made from a relatively
radiolucent material such as a stainless material. The entire
length of the coil 4 is not particularly limited but may be in a
range of about 5 to 500 mm.
[0074] The proximal end portion and the distal end portion of the
coil 4 are fixed to the first wire 2 by a fixing material 11 and a
fixing material 12, respectively, and an intermediate portion
(close to the distal end) of the coil 4 is fixed to the first wire
2 by a fixing material 13. Each of the fixing materials 11, 12, and
13 is a solder (brazing material). Alternatively, each of the
fixing materials 11, 12, and 13 may be an adhesive. In addition, in
place of using the fixing material, the coil 4 may be fixed to the
first wire 2 by welding. To prevent damage of the inner wall of a
blood vessel, the leading end surface of the fixing material 12 is
preferably rounded.
[0075] According to this embodiment, since the first wire 2 is
partially covered with the coil 4, the contact area of the first
wire 2 with the inner wall of a catheter used together with the
guide wire 1 is small, with a result that it is possible to reduce
the sliding resistance of the guide wire 1 in the catheter. This is
effective to further improve the operationality of the guide wire
1.
[0076] In this embodiment, the wire having a circular shape in
cross-section is used for the coil 4; however, the cross-sectional
shape of the wire used for the coil 4 may be another shape such as
an elliptic shape or a quadrilateral shape (especially, rectangular
shape).
[0077] In the guide wire 1, the first wire 2 and the second wire 2
are joined to each other by welding. A welded portion (joining
portion) 14 between the first wire 2 and the second wire 3 has a
high joining strength, thereby allowing the guide wire 1 to
certainly transmit a torsional torque or pushing force from the
second wire 3 to the first wire 2.
[0078] In this embodiment, a connection end face 21 of the first
wire 2 to the second wire 3 and a connection end face 31 of the
second wire 3 to the first wire 2 are each formed into a plane
nearly perpendicular to the axial (longitudinal) direction of both
the wires 2 and 3. This significantly facilitates working for
forming the connection end faces 21 and 31, to achieve the
above-described effects without complicating the steps for
producing the guide wire 1.
[0079] It is to be noted that each of the connection end faces 21
and 31 may be tilted relative to the plane perpendicular to the
axial (longitudinal) direction of both the wires 2 and 3, or formed
into a recessed or raised shape.
[0080] The method of welding the first wire 2 and the second wire 3
to each other is not particularly limited but is generally
exemplified by spot welding using laser or butt resistance welding
such as butt seam welding. In particular, to ensure a high joining
strength of the welded portion, butt resistance welding is
preferable.
[0081] The second wire 3 of the guide wire 1 has, in the vicinity
of the welded portion 14, a small cross-sectional area 32 with its
cross-sectional area being smaller than that of a proximal end
portion 23 of the first wire 2. In other words, in a portion from
the connection end face 31 to a specific position on the proximal
side, that is, in the small cross-sectional area portion 32, the
cross-sectional area of the second wire 3 is smaller than that of
the proximal end portion 23 of the first wire 2. In this
embodiment, the outer diameter of the small cross-sectional area
portion 32 is smaller than that of the proximal end portion 23 of
the first wire 2, and therefore, the cross-sectional area of the
small cross-sectional area portion 32 is smaller than that of the
proximal end portion 23. In other words, the area of the connection
end face 31 is smaller than that of the connection end face 21.
[0082] Since the second wire 3 is made from a material having an
elastic modulus larger than that of the first wire 2 as described
above, if the outer diameter of the distal end portion of the
second wire 3 is the same as that of the proximal end portion 23 of
the first wire 2, the rigidity (flexural rigidity, torsional
rigidity) of the guide wire 1 is rapidly changed between both sides
of the welded portion 14. On the contrary, according to the present
invention, the small cross-sectional area portion 32 is provided at
the distal end portion of the second wire 3, and the rigidity
(flexural rigidity, torsional rigidity) of the small
cross-sectional area portion 32 is made small. Accordingly, the
change in rigidity (flexural rigidity, torsional rigidity) of the
welded portion 14 and its neighborhood becomes moderate (smooth)
along the longitudinal direction, to thereby enhance the
operationality of the guide wire 1.
[0083] According to this embodiment, the small cross-sectional area
portion 32 includes a portion in which the outer diameter is
gradually reduced in the direction toward the distal end, that is,
the cross-sectional area is gradually reduced in the direction
toward the distal end. Accordingly, the rigidity (flexural
rigidity, torsional rigidity) of the small cross-sectional area
portion 32 is gradually reduced from the proximal end to the distal
end thereof, that is, in the direction toward the distal end of the
guide wire 1, to thereby make the change in rigidity (flexural
rigidity, torsional rigidity) of the guide wire 1 more moderate
(smooth) along the longitudinal direction.
[0084] In the configuration shown in the figure, the small
cross-sectional area portion 32 has, over the entire length, the
taper shape with its outer diameter gradually reduced in the
direction toward the distal end; however, the small cross-sectional
area portion 32 may have a portion having a constant outer diameter
(cross-sectional area), for example, on the distal end side, and
may further have, on the distal side from the outer-diameter
constant portion, a portion with its outer diameter gradually
increased in the direction toward the welded portion 14. Even in
this case, the same effect as that described above can be obtained.
It is to be noted that modifications of the small cross-sectional
area portion 32 will be fully described in detail.
[0085] The length of the small cross-sectional area portion 32
(denoted by character L in FIG. 1) is not particularly limited but
is preferably in a range of about 3 to 1,000 mm, more preferably,
about 3 to 300 mm. If the length L is within the above range, the
change in rigidity (flexural rigidity, torsional rigidity) of the
welded portion 14 and its neighborhood can be made more moderate
(smooth) along the longitudinal direction.
[0086] In the small cross-sectional area portion 32, the flexural
rigidity of the distal end (connection end face 31) of the second
wire 3 is preferably nearly equal to the flexural rigidity of the
proximal end (connection end face 21) of the first wire 2. With
this configuration, the change in rigidity of the welded portion 14
and its neighborhood can be made more moderate (smooth) along the
longitudinal direction. In addition, letting the geometrical moment
of inertia (determined only by the shape and dimension of the
connection end face 31) of the connection end face 31 be 12 and the
Young's modulus of the material of the second wire 3 be E.sub.2,
the flexural rigidity of the distal end of the second wire 3 is
expressed by E.sub.2I.sub.2. On the other hand, letting the
geometrical moment of inertia (determined only by the shape and
dimension of the connection end face 21) of the connection end face
21 be I.sub.1 and the Young's modulus of the material of the first
wire 2 be E.sub.1, the flexural rigidity of the distal end of the
first wire 2 is expressed by E.sub.1I.sub.1.
[0087] The guide wire 1 in this embodiment has a step filling
member 6 for filling a stepped portion formed on the outer
periphery of the welded portion 14. The stepped portion, which is
formed on the outer periphery of the welded portion 14 due to the
fact that the outer diameter of the distal end of the second wire 3
is smaller than that of the proximal end of the first wire 2, is
filled with the step filling member 6, to thereby prevent the
reduction in sliding performance of the guide wire 1 due to the
presence of the stepped portion.
[0088] In the configuration shown in the figure, the step filling
member 6 covers the small cross-sectional area portion 32. The
outer diameter of the member 6 is kept nearly constant along the
longitudinal direction, and the inner diameter of the member 6 is
gradually reduced in the direction toward the distal end. As a
result, the outer diameter of a portion, including the welded
portion 14 and the small cross-sectional area portion 32, of the
guide wire 1 is kept nearly constant along the longitudinal
direction. This is effective to more certainly eliminate adverse
effect of the stepped portion exerted on the sliding performance of
the guide wire 1.
[0089] The material for forming the step filling member 6 is not
particularly limited, and may be generally selected from resin
materials and metal materials. To reduce adverse effect of the
member 6 exerted on the rigidity of the guide wire 1, the member 6
is preferably made from a relative soft material such as solder,
plastic, or wax. The shape of the step filling member 6 is not
limited to that shown in the figure but may be any shape such as a
coil shape.
[0090] In this embodiment, the welded portion 14 is located on the
proximal side from the proximal end of the coil 4, but the welded
portion 14 may be located on the distal side from the proximal end
of the coil 4.
[0091] If the rigidity of the first wire 2 is smaller than that of
the second wire 3, the size of the connection end face 31 may be
larger than that of the connection end face 21.
[0092] FIGS. 5 and 6 are longitudinal sectional views showing
modifications of the small cross-sectional area portion of the
guide wire of the present invention.
[0093] A small cross-sectional area portion 32 according to a
modification shown in FIG. 5 has a first portion 32A with its outer
diameter gradually reduced in the direction toward the distal end,
and a second portion 32B with its outer diameter gradually
increased in the direction toward the distal end, wherein the
second portion 32B is disposed on the distal side from the first
portion 32A. The outer peripheral surface of a boundary portion
between the first portion 32A and the second portion 32B has a
continuous curved plane without substantial stepped portion (smooth
plane). With this configuration, it is possible to prevent or
relieve stress concentration at the boundary portion, and hence to
more certainly prevent torsion or kink, that is, to improve the
kink resistance.
[0094] The maximum outer diameter of the second portion 32B is
located at a connection end face 31 (the distal end of a second
wire 3), and is nearly equal to the outer diameter of a connection
end face 21 (the proximal end of a first wire 2). Accordingly, as
compared with the configuration shown in FIG. 1, the small
cross-sectional area portion 32 shown in FIG. 5 is advantageous in
enlarging the area of a welded surface of a welded portion 14,
thereby improving the welding strength. As a result, when a
torsional torque or pushing force is applied from the second wire 3
to the first wire 2, it is possible to more certainly prevent
breakage of the welded portion 14 due to stress concentration at
the welded portion 14 or lacking of the welding strength of the
welded portion 14.
[0095] In the small cross-sectional area portion 32, letting the
length of the first portion 32A be L.sub.A and the length of the
second portion 32B be L.sub.B, the length L.sub.A is longer than
the length L.sub.B. In other words, the taper angle of the first
portion 32A is smaller than that of the second portion 32B.
[0096] The length L.sub.A of the first portion 32A is preferably in
a range of about 0.1 to 1,000 times, more preferably, 1.0 to 1,000
times, most preferably, 1.0 to 50 times the length L.sub.B of the
second portion 32B. With this configuration, it is possible to
suppress stress concentration at the welded portion 14, and hence
to realize smooth transition of rigidity.
[0097] A small cross-sectional area portion 32 according to another
modification shown in FIG. 6 has a third portion 32C located
between a first portion 32A and a second portion 32B. The third
portion 32C has a nearly constant outer diameter, which may be
smaller than each of the outer diameters of the first portion 32A
and the second portion 32B. In other words, the third portion 32C
is preferably the minimum outer-diameter portion of the small
cross-sectional area portion 32. Other configurations of this
modification are the same as those of the previous modification
shown in FIG. 5.
[0098] The small cross-sectional area portion 32 shown in FIG. 6
has not only the same function and effect as those of the small
cross-sectional area portion 32 shown in FIG. 5, but also the
following additional function and effect: namely, since the minimum
outer-diameter portion of the small cross-sectional area portion 32
may be taken as the third portion 32C continuously extending for a
specific length (denoted by character L.sub.C), it is possible to
more certainly relieve stress concentration at the minimum
outer-diameter portion of the small cross-sectional portion 32 as
compared with the configuration shown in FIG. 5. As a result, when
a torsional torque or pushing force is applied from the second wire
3 to the first wire 2, it is possible to more certainly prevent
torsion, kink, breakage, and the like of the minimum outer-diameter
portion of the small cross-sectional area portion 32.
[0099] The third portion 32C preferably has rigidity nearly equal
to that of a portion in the vicinity of the proximal end portion 23
of the first wire 2. Since the outer diameter of the third portion
32C is set such that the rigidity of the third portion 32C is
nearly equal to the portion in the vicinity of the proximal end
portion 23 of the first wire 2, it is possible to realize smooth
transition of rigidity from the small cross-sectional area portion
32 to the proximal end portion 23 of the first wire 2.
[0100] Each of the outer peripheral surface of a boundary portion
between the first portion 32A and the third portion 32C and the
outer peripheral surface of a boundary portion between the third
portion 32C and the second portion 32B forms a continuously curved
plane without substantial stepped portion (smooth plane). With this
configuration, the above-described effect of preventing or
relieving stress concentration at the boundary portion can be
obtained.
[0101] The relationship among a length L.sub.A of the first portion
32A, a length L.sub.B of the second portion 32B, and a length
L.sub.Cof the third portion 32C is not particularly limited but is
preferably set to a relationship of
L.sub.B.ltoreq.L.sub.C.ltoreq.L.sub.A or
L.sub.B.ltoreq.L.sub.A.ltoreq.L.sub.C, more preferably
L.sub.B<L.sub.C.ltoreq.L.sub.A.
[0102] In this embodiment, the length L.sub.A of the first portion
32A is preferably in a range of about 0.1 to 1,000 times, more
preferably, 0.1 to 10 times the length L.sub.B of the second
portion 32B. With this configuration, it is possible to suppress
stress concentration at the welded portion 14, and hence to realize
smooth transition of rigidity.
[0103] To sufficiently obtain an effect of relieving stress
concentration at the minimum outer-diameter portion while keeping
the strength of the small cross-sectional area portion 32, the
length L.sub.C of the third portion 32C is preferably in a range of
about 0.1 to 200 mm, more preferably, about 1 to 50 mm.
[0104] The outer periphery of the small cross-sectional area
portion 32 shown in each of FIGS. 5 and 6 may be covered with the
above-described step filling member 6. With this configuration, the
above-described effect of eliminating the degradation of the
sliding performance of the guide wire 1 due to the presence of the
stepped portion can be obtained.
[0105] The procedure of joining the first wire 2 and the second
wire 3 to each other by butt seam welding as one example of butt
resistance welding will be described with reference to FIGS. 2A to
2C. FIGS. 2A to 2C show steps 1 to 3 of the procedure of joining
the first wire 2 and the second wire 3 to each other by butt seam
welding.
[0106] In the step 1, the first wire 2 and the second wire 3 are
fixed (mounted) to a butt welder (not shown).
[0107] In the step 2, the connection end face 21 on the proximal
side of the first wire 2 and the connection end face 31 on the
distal side of the second wire 3 are butted to each other while a
specific voltage is applied thereto by the butt welder. With this
operation, a fused layer (welded surface) is formed at the contact
portion, whereby the first wire 2 and the second wire 3 are
strongly joined to each other.
[0108] In the step 3, a projection at the joining portion (welded
portion 14), which is formed by deformation upon butt resistance
welding, is removed. A portion, on the proximal side from the
welded portion 14, of the second wire 3, that is, the distal end
portion of the second wire 3 is ground, to form the small
cross-sectional area portion 32 having a desired shape as shown in
FIGS. 1, 5, or 6, that is, the small cross-sectional area portion
32 with its outer diameter gradually reduced in the direction
toward the distal end.
[0109] Alternatively, the small cross-sectional area portion 32
having a desired shape (with its outer diameter gradually reduced
in the direction toward the distal end) may be previously prepared
by grinding the distal end portion of the second wire 3, and then
welded to the first wire 2 by the butt resistance welding
process.
[0110] FIGS. 3 and 4 are views showing the operational state of the
guide wire 1 of the present invention during use in the PTCA
process.
[0111] In FIGS. 3 and 4, reference numeral 40 denotes an aortic
arch, 50 is a right coronary artery of a heart, 60 is an ostium of
the right coronary artery 50, and 70 is a target angiostenosis
portion. Further, reference numeral 30 denotes a guiding catheter
for certainly guiding the guide wire 1 from an arteria fermoralis
into the right coronary artery 50, and 20 is a balloon catheter
having at its distal end an expandable and contractible balloon 201
for dilating the target angiostenosis portion 70.
[0112] As shown in FIG. 3, the guide wire 1 is moved in such a
manner that the distal end thereof projecting from the distal end
of the guiding catheter 30 is inserted in the right coronary artery
50 through the ostium 60 of the right coronary artery 50. The guide
wire 1 is further advanced, and is stopped when the distal end
thereof passes the target angiostenosis portion 70 in the right
coronary artery 50. In this state, an advance path of the balloon
catheter 20 is ensured. At this time, the welded portion 14 of the
guide wire 1 is located in the living body, more specifically, in
the vicinity of the distal portion of the aortic arch 40.
[0113] As shown in FIG. 4, the balloon catheter 20 is inserted
around the guide wire 1 from the proximal side of the guide wire 1.
The balloon catheter 20 is then advanced in such a manner that the
distal end thereof projects from the distal end of the guiding
catheter 30, goes ahead along the guide wire 1, and enters the
right coronary artery 50 from the ostium 60 of the right coronary
artery 50. The balloon catheter 20 is stopped when the balloon 201
reaches a position corresponding to that of the target
angiostenosis portion 70.
[0114] A fluid for inflating the balloon 201 is injected in the
balloon catheter 20 from the proximal side of the balloon catheter
20, to inflate the balloon 201, thereby dilating the target
angiostenosis portion 70. As a result, deposits such as cholesterol
adhering on the arterial wall of the target angiostenosis portion
70 are physically compressed against the arterial wall, to
eliminate blocking of blood flow.
[0115] FIG. 7 is a longitudinal sectional view showing a second
embodiment of the guide wire of the present invention. The second
embodiment of the guide wire of the present invention will now be
described with reference to FIG. 7, principally, about differences
from the previous embodiment, with the description of the same
features omitted.
[0116] According to a guide wire 1' in this embodiment, a first
wire 2 has an outer-diameter gradually reducing portion 22 and an
outer-diameter gradually reducing portion 24 provided on the
proximal side from the outer-diameter gradually reducing portion
22. In this way, the first wire 2 may have outer-diameter gradually
reducing portions at a plurality of positions.
[0117] In this embodiment, a welded portion 14 has a projection 15
projecting in the outer peripheral direction. The formation of such
a projection 15 is effective to enlarge a joining area between the
first wire 2 and the second wire 3, and hence to significantly
enhance the joining strength. This is advantageous in more
certainly transmitting a torsional torque or pushing force from the
second wire 3 to the first wire 2.
[0118] The formation of the projection 15 may make the welded
portion 14 between the first wire 2 and the second wire 3 easily
visible under fluoroscopy. As a result, it is possible to easily,
certainly recognize the advancing state of the guide wire 1' and a
catheter in a blood vessel or the like by checking the fluoroscopic
image, and hence to shorten the operation time and to improve the
safety.
[0119] As described above, the first wire 2 and the second wire 3
are generally made from materials having different elastic moduli.
Accordingly, because of provision of the projection 15, an operator
can easily, certainly, recognize a portion, at which the elastic
modulus is relatively largely changed, of the guide wire 1'. This
enhances the operationality of the guide wire 1', to shorten the
operation time and improve the safety.
[0120] The height of the projection 15, which depends on the outer
diameters of the first wire 2 and the second wire 3, is not
particularly limited, but is preferably in a range of 0.001 to 0.3
mm, more preferably, 0.005 to 0.05 mm. If the height of the
projection 15 is less than the lower limit, it may fail to
sufficiently obtain the above-described effects depending on the
materials of the first wire 2 and the second wire 3. If the height
of the projection 15 is more than the upper limit, since the inner
diameter of a lumen, in which the guide wire 1 is to be inserted,
of a balloon catheter is fixed, the outer diameter of the second
wire 3 on the proximal side must be thin relative to the height of
the projection 15, with a result that it may become difficult to
ensure sufficient physical properties of the second wire 3.
[0121] In the configuration shown in FIG. 7, each of one side
(upper side in FIG. 7) and the other side (lower side in FIG. 7) of
the projection 15 is formed into an approximately circular-arc
shape in longitudinal cross-section, and the welded portion 14 is
located on the maximum outer-diameter portion of the projection 15.
This is advantageous in enlarging an area of the welded surface of
the welded portion 14, thereby obtaining a higher joining strength
(welding strength).
[0122] According to the present invention, the shape of the
projection 15 and the position of the welded portion 14 relative to
the projection 15 are not limited to those described above. For
example, each of one side and the other side of the projection 15
may be formed into a non-circular (non-circular arc) such as a
trapezoidal or triangular shape in longitudinal cross-section. The
proximal side and the distal side of the projection 15 may be
formed into shapes asymmetric to each other with respect to the
welded surface (connection end face 21, 31) of the welded portion
14. The axial position of the welded surface of the welded portion
14 relative to the projection 15 is not necessarily located at the
central portion as shown in FIG. 7 but may be located at a position
offset to the proximal side (second wire 3 side) or on the distal
side (first wire 2 side). With this configuration, it is possible
to prevent or relieve stress concentration at the welded portion
14, and hence to more certainly prevent breakage of the welded
portion 14 due to stress concentration at the welded portion 14
when a torsional torque or pushing force is applied from the second
wire 3 to the first wire 2.
[0123] The guide wire 1' has a cover layer 7 on the outer surface
(outer peripheral surface) side. In this way, the guide wire of the
present invention may be configured to have a cover layer that
covers the whole or part of the outer surface (outer peripheral
surface). Such the cover layer 7 is formed for satisfying various
purposes, one of which is to reduce the friction (sliding friction)
of the guide wire 1' for improving the sliding performance of the
guide wire 1', thereby enhancing the operationality of the guide
wire 1'.
[0124] To satisfy the above-described purpose, the cover layer 7 is
preferably made from a material capable of reducing the friction of
the guide wire 1'. With this configuration, since the friction
resistance (sliding resistance) of the guide wire 1' against the
inner wall of a catheter used together with the guide wire 1' is
reduced, the sliding performance of the guide wire 1' is improved,
to enhance the operationality of the guide wire 1' in the catheter.
Further, since the sliding resistance of the guide wire 1' is
reduced, it is possible to more certainly prevent, at the time of
movement and/or rotation of the guide wire 1' in the catheter, kink
(sharp bending) or torsion of the guide wire 1', particularly, in
the vicinity of a welded portion of the guide wire 1'.
[0125] Examples of the materials capable of reducing the friction
of the guide wire 1' include polyorefins such as polyethylene and
polypropylene, polyvinyl chloride, polyesters (such as PET and
PBT), polyamide, polyimide, polyurethane, polystyrene,
polycarbonate, silicone resins, fluorocarbon resins (such as PTFE
and ETFE), silicone rubbers, various kinds of elastomers (for
example, thermoplastic elastomers such as polyamide-based elastomer
and polyester-based elastomer), and composite materials thereof. In
particular, a fluorocarbon resin or a composite material thereof is
preferable, and PTFE is more preferable.
[0126] According to this embodiment, a hydrophilic material or a
hydrophobic material can be also used as another preferred example
of the material capable of reducing the friction of the guide wire
1'. In particular, the hydrophilic material is preferable.
[0127] Examples of the hydrophilic materials include a cellulose
based polymer, a polyethylene oxide based polymer, a maleic
anhydride based polymer (for example, a maleic anhydride copolymer
such as methylvinylether-maleic anhydride copolymer), an acrylic
amide based polymer (for example, polyacrylic amide or polyglycidyl
methacrylate-dimethyl acrylic amide [PGMA-DMAA] block copolymer),
water-soluble nylon, polyvinyl alcohol, and polyvinyl
pyrolidone.
[0128] In many cases, the hydrophilic material can exhibit a
lubricating performance in a wet (water-absorbing) state. The use
of the cover layer 7 made from such a hydrophilic material is
effective to reduce the friction resistance (sliding resistance) of
the guide wire 1' against the inner wall of a catheter used
together with the guide wire 1', to improve the sliding performance
of the guide wire 1', thereby enhancing the operationality of the
guide wire 1' in the catheter.
[0129] The provision of the cover layer 7 is effective to omit or
simplify the above-described step filling member 6. To be more
specific, since the cover layer 7 is formed in such a manner as to
cover a stepped portion in the vicinity of the welded portion 14,
even if the step filling member 6 is omitted or simplified, it is
possible to sufficiently prevent degradation of the sliding
performance of the guide wire 1' due to the presence of the stepped
portion.
[0130] The cover layer 7 may be formed in such a manner as to the
whole or part of the guide wire 1' in the longitudinal direction;
however, the cover layer 7 is preferably formed in such a manner as
to cover the welded portion 14, that is, formed at a portion
including the welded portion 14.
[0131] The cover layer 7 covers the small cross-sectional area
portion 32 and the projection 15, and has a substantially uniform
outer diameter. The term "substantially uniform outer diameter"
used herein contains an outer diameter smoothly changed within such
a range as not to cause any inconvenience in use of the guide
wire.
[0132] The thickness (in average) of the cover layer 7 is not
particularly limited but is preferably in a range of about 1 to 20
.mu.m, more preferably, about 2 to 10 .mu.m. If the thickness of
the cover layer 7 is less than the lower limit, the effect obtained
by formation of the cover layer 7 may be not sufficiently achieved
and the cover layer 7 may be often peeled. If the thickness of the
cover layer 7 is more than the upper limit, the physical properties
of the wire may be obstructed and the cover layer 7 may be often
peeled.
[0133] According to the present invention, the outer peripheral
surface of the guide wire body (including the first wire 2, the
second wire 3, and coil 4) may be subjected to a treatment (such as
chemical treatment or heat treatment) for improving the adhesion
characteristic of the cover layer 7, or may be provided with an
intermediate layer for improving the adhesion characteristic of the
cover layer 7.
[0134] The cover layer 7 may have a nearly constant composition or
different compositions at respective portions. For example, the
cover layer 7 may have a first region (first cover layer) for
covering at least the coil 4 and a second region (second cover
layer) on the proximal side from the first region, wherein the
first cover layer and the second cover layer be made from different
materials. Although the first cover layer and the second layer may
be formed so as to be continuous to each other in the longitudinal
direction as shown in the figure, the proximal end of the first
cover layer may be separated from the distal end of the second
cover layer, or the first cover layer may be partially overlapped
to the second cover layer.
[0135] FIGS. 8A and 8B are perspective views showing further
modifications of the small cross-sectional area portion of the
second wire of the guide wire of the present invention.
[0136] A small cross-sectional area portion 32 of a second wire 3
shown in FIG. 8A has an outer diameter, which is kept constant and
is equal to that of a portion on the proximal side from the small
cross-sectional area portion 32. The small cross-sectional area
portion 32 has a hollow portion 321 with its inner diameter
gradually increased in the direction toward the distal end. That is
to say, the hollow portion 321 is formed into a conical or
truncated conical shape. Since such a hollow portion 321 is formed,
the cross-sectional area of the small cross-sectional area portion
32 is smaller than that of a proximal end portion 23 of a first
wire 2 and is gradually reduced in the direction toward the distal
end, with a result that the rigidity (flexural rigidity, torsional
rigidity) of the small cross-sectional area portion 32 is gradually
reduced in the direction toward the distal end. According to the
present invention, such a small cross-sectional area portion 32
having the shape shown in FIG. 8A has the same effect as that
obtained in each of the previous embodiments. The small
cross-sectional area portion 32, in which the cross-sectional area
can be gradually reduced without changing the outer diameter by the
presence of the hollow portion 321, has another advantage in
eliminating the need of provision of the step filling member 6
because no stepped portion is formed at a welded portion 14 between
the proximal portion 23 of the first wire 2 and the small
cross-sectional area portion 32. The hollow portion 321 may be
formed into a pyramid or truncated pyramid shape. In this case, the
welding may be performed in a state that part of the proximal end
portion 23 of the first wire 2 is inserted in the hollow portion
321 of the second wire 3. With this configuration, since the change
in rigidity becomes smoother between both sides of the welded
portion 14, it is possible to further improve the kink
resistance.
[0137] A small cross-sectional area portion 32 of a second wire 3
shown in FIG. 8B has a truncated pyramid shape, more specifically,
a truncated hexagonal pyramid shape, wherein the dimension of the
polygonal shape (regular hexagonal shape) in cross-section is
gradually reduced in the direction toward the distal end. As a
result, the cross-sectional area of the small cross-sectional area
portion 32 is gradually reduced in the direction toward the distal
end, with a result that the rigidity (flexural rigidity, torsional
rigidity) thereof is gradually reduced in the direction toward the
distal end. Such a small cross-sectional area portion 32 shown in
FIG. 8B has the same effect as that obtained in each of the
previous embodiments.
[0138] In the above-described embodiments, each of the composing
elements of the guide wire may be replaced with a composing element
having any other configuration exhibiting the similar effect, and
may be provided with any other additional element.
[0139] While the preferred embodiments of the present invention
have been described using specific terms, such description is for
illustrative purposes only, and it is to be understood that changes
and variations may be made without departing from the spirit or
scope of the following claims.
[0140] The entire disclosure of Japanese Patent Application No.
2002-232164 filed on Aug. 8, 2002, Japanese Patent Application No.
2002-355908 filed on Dec. 6, 2002 and Japanese Patent Application
No. 2003-156011 filed on May 30, 2003 including specification,
claims, drawings, and summary are incorporated herein by reference
in its entirety.
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