JPH042274B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a core material of a catheter guide wire, which is a medical instrument, and a catheter guide wire.

[Prior Art] In general, a catheter guidewire is introduced into a blood vessel by a Seldinger needle punctured from a blood vessel site, and then the Seldinger needle is removed from the guidewire, a catheter is attached to the rear end of the guidewire, and the pulse of the living body is measured. A medical device used to guide a catheter in advance of a catheter to a target site within a vessel, particularly a blood vessel.

For this reason, the core material of Catheter Guide Wide is
It is composed of a tip section with a complex shape and a matrix section with a linear shape.
°C), it has elastic properties that allow reversible energy absorption and release as well as reversible shape deformation and recovery when loading and removing deformation stress, including twisting, that occurs during introduction and movement into blood vessels. Generally, Ti/Ni alloy is used as the basic material because it is required.

However, Ti・
In catheter guide wires that use a Ni-based alloy material as the core material, as the elongation deformation increases, the load required for deformation increases almost linearly, so the work of introducing it into the blood vessel requires constant stress. This poses a problem in that it cannot be performed and causes physiological pain to both the doctor and the patient.

Therefore, in the past, Ti/Ni alloys were usually
~40% cold working followed by heat treatment at 400-500°C produces an improved annealed material, which in vivo (approximately 37°C)
Obtained a core material for a catheter guide wire that exhibits increased elongation and deformation even under constant stress (hereinafter referred to as superelastic properties) and is capable of reversibly absorbing and releasing energy and reversibly deforming and recovering its shape. (Japanese Unexamined Patent Publication No. 171570/1983).

[Problems to be Solved by the Invention] However, the rigidity of catheter guide wire core materials using conventional annealed Ti/Ni alloy materials is approximately 1/2 that of core materials using stainless steel wire. It is difficult to guide the catheter to a desired site within the human body against stress such as muscle contraction. That is, operations at hand, e.g.
The torque transmittance for transmitting twisting and the rigidity for transmitting pushing were insufficient.

Therefore, in view of the above-mentioned drawbacks, the technical problem of the present invention is to provide a core material for a catheter guide wire that maintains flexibility in the tip part and maintains rigidity in the substrate part at least at body temperature (37°C). An object of the present invention is to provide a catheter guide wire.

[Means for Solving the Problems] According to the present invention, in the core material of a catheter guide wire made of a superelastic alloy, at least a part of the surface excluding the blood vessel introduction tip is covered with an inorganic coating. A core material for a catheter guide wire is obtained.

Further, according to the present invention, the inorganic coating is made of Ni.
A core material for a catheter guide wire, which is characterized by being a coating, is obtained.

Further, according to the present invention, the core material of a catheter guide wire having a distal end portion and a substrate portion has a clad structure surrounding the substrate portion, and
A core material for a catheter guide wire is obtained, in which the tip portion has superelastic properties.

[Example] Next, an example of the present invention will be described with reference to the drawings.

-First Example- In this example, a core material of a catheter guide wire will be described in which the tip portion maintains flexibility while the substrate portion maintains rigidity under body temperature (37° C.).

Preparation process First, in atomic percent, Ni51at%, the balance
A Ti-51at%Ni alloy consisting of Ti was obtained by high frequency vacuum melting. Note that arc melting, electron beam melting, or powder metallurgy may also be used.

The obtained Ti/Ni alloy was solution-treated at 900 to 1000°C, then hot forged and hot rolled at about 900°C, and then cold worked (final cold working rate 50
%), it was processed into a wire rod with a size of 0.5 mmφ.

Superelasticity treatment process The entire wire rod of 0.5mmφ was heat-treated (annealed) at 400°C for 10 minutes under tension to impart linearity and superelasticity.

Initial superelastic property test Body temperature of heat-treated wire (No. 2) (37℃)
The stress-strain curve at a strain of 3% (elongation) at the bottom was measured. In addition, as a comparative example, 18-8
A stainless steel wire (No. 1) was also measured. The results are shown in FIG.

As a result, in the heat-treated wire rod (No. 2), even when 3% strain was applied, the strain completely disappeared as soon as the load was released. In other words, the wire rod (No. 2) has superelastic properties that facilitate reversible absorption and release of energy and reversible shape deformation and recovery by heat treatment and load/removal. I understand. In the 18-8 stainless steel wire (No. 1) of the comparative example, permanent deformation remains completely at a strain of 3%, and the superelastic properties seen in annealed Ti/Ni alloys are not observed.

On the other hand, regarding rigidity, the heat-treated wire rod (No. 2) has a tensile strength of approximately 3% strain.
While it is 50Kgf/mm ² , the 18-8 stainless steel wire (No. 1) shows about 100Kgf/mm ² .
This means that the heat-treated wire rod (No. 2)
Although it has superelastic properties, it lacks rigidity and is weak compared to conventional stainless steel wire.

Ni coating treatment process Next, the entire surface of the wire that has been subjected to multiple heat treatments is coated with Ni by electroplating (No. 3), stainless steel by vapor deposition plating (No. 4), and silicon carbide (SiC) by sputtering. (No. 5), sputtering titanium nitride (No. 6), 25-50μ
Each layer was coated to a thickness of m.

Intermediate superelastic property test The stress-strain curve at body temperature (37°C) was measured for each of the coated wire rods (Nos. 3 to 6). The results are shown in FIG.

As a result, coated wire rods (No. 3 to 6)
All of the wires exhibited curves similar to those of the 18-8 stainless steel wire (No. 1), and were found to have high rigidity.

Tip Treatment Step Each of the coated wire rods (Nos. 3 to 6) was cut into a 2 m length from the end surface, and the coating was removed only from a length of about 50 mm from the end surface. A chemical method using aqua regia was used for removal. Note that mechanical methods such as polishing may also be used.

Final superelastic property test The stress-strain curve at body temperature (37°C) was measured for each film-removed tip of the coated wire (Nos. 3 to 6). the result,
Superelastic properties similar to those of the heat-treated wire rod (No. 2) in the initial superelasticity test were observed.

It can be seen that this makes it possible to obtain a single core material in which the tip part has superelasticity and the remaining matrix part has high rigidity.

-Second Example- This example relates to a core material of a catheter guide wire having a clad structure.

Preparation process The Ti/Ni alloy wire with a size of 5.0mmφ obtained in the preparation process of the first example was used with an inner diameter of 5.1mm.
It is inserted into an 18-8 stainless steel pipe with a diameter of 6.0 mm and a core made of Ti/Ni alloy and the outer skin made of stainless steel.

Swaging process The clad wire is swaged.
After making it 0.7 mmφ, the wire was made 0.5 mmφ by cold working to obtain a clad wire.

Superelasticity treatment step The obtained clad wire was heat treated at 400°C for 10 minutes to impart superelasticity.

Shell superelastic property test The stress-strain curve of the heat-treated clad wire (No. 7) at body temperature (37°C) was measured. The results are shown in FIG.

As a result, a heat-treated clad wire (No.
7) exhibited a curve similar to that of the 18-8 stainless steel wire (No. 1) and was found to have high rigidity.

Tip Treatment Step As in the first example, the outer sheath of the heat-treated clad wire (No. 7) was removed from the end face by approximately 50 mm to expose the core from the outer sheath.
A chemical method using aqua regia was used for removal.

Core superelasticity test The core of the heat-treated clad wire (not shown) was tested for stress at body temperature (37℃).
Strain curves were measured. As a result, it was found that the wire rod had the same superelastic properties as the wire rod (No. 2) subjected to the heat treatment of the first example.

In addition, the core is chemically treated (fluoric acid),
Tapering was performed and the entire length was then coated with a polymer such as polyurethane.

-Third Embodiment- As shown in FIG. 2, the synthetic resin coating 4 has a substantially uniform outer diameter including the tip. especially,
This synthetic resin coating 4 has a substantially uniform outer diameter. As the synthetic resin coating 4, polyethylene,
Polyvinyl chloride, polyester, polypropylene, polyamide, polyurethane, polystyrene,
Fluororesin, silicone rubber, or their respective elastomers and composite materials are preferably used. Preferably, the synthetic resin coating 4 is flexible to the extent that it does not interfere with the curvature of the inner core 2, and the outer surface is smooth without any irregularities. In addition, the synthetic resin coating 4 may include anticoagulants such as heparin and urokinase, silicone rubber, and block copolymers of urethane and silicone (registered trademark).
It may also be coated with an antithrombotic material such as Abcosan), hydroxyethyl methacrylate-styrene copolymer, etc. Furthermore, the friction properties of the guide wire 1 can be reduced by forming the synthetic resin coating 4 from a resin having a low friction surface such as fluorine resin, and by applying a lubricant such as silicone oil to the outer surface of the synthetic resin coating 4. You may let them. Furthermore, in the synthetic resin forming the synthetic resin coating 4, Ba, W, Bi, Pb
X in fine powder form made of simple metals or compounds such as
It is preferable to mix a radiographic contrast substance, and by doing so, it becomes easy to confirm the entire position of the guide wire 1 being introduced into the blood vessel. As described above, the synthetic resin coating 4 has a substantially uniform outer diameter. "Substantially uniform" does not necessarily mean that it is completely uniform, but may have a slightly narrower diameter at the tip. In this way, by making it almost uniform up to the tip,
Damage that the tip of the guide wire may cause to the inner wall of the blood vessel can be reduced.

The outer diameter of the synthetic resin coating is 0.25 to 1.04 mm, preferably 0.30 to 0.64 mm, and the thickness of the core material 2 on the main body portion 2a is 0.03 to 0.30 mm, preferably 0.05 to 0.20 mm.

Further, it is preferable that the synthetic resin coating 4 is tightly adhered to the inner core 2 by synthetic resin, and is also fixed to the distal end and the proximal end of the inner core 2. Alternatively, the synthetic resin coating 4 may be formed of a hollow tube and fixed to the inner core 2 by adhesion or melt molding at the distal and proximal ends of the inner core 2 or at an appropriate portion of the inner core. The tip of the guide wire 1 (the tip of the synthetic resin coating 4) has a curved surface such as a hemispherical shape as shown in FIG. 2 in order to prevent damage to the blood vessel wall and improve the operability of the guide wire 1. It is preferable that

Furthermore, it is preferable that a lubricating substance is fixed to the surface of the synthetic resin coating 4. A lubricating substance refers to a substance that has lubricating properties when wet. Specifically, there are water-soluble polymer substances or derivatives thereof.

An example as a guide wire will be specifically described.

As core material 2, the total length is 1800mm and the diameter of the tip is
0.06mm, rear end diameter is 0.25mm, 120mm from tip
We created one in which the diameter is tapered toward the tip.

Furthermore, the entire outer surface of the core material is coated with polyurethane containing 45% by weight of fine tungsten powder (particle size of about 3 to 4 μm) so that the overall outer diameter is almost uniform.
A synthetic resin film was formed. Then, a solution of 5.0% by weight of the maleic anhydride ethyl ester copolymer dissolved in tetrahydrofuran was applied to the surface of the synthetic resin coating formed from the above polyurethane to dissolve the maleic anhydride ethyl ester copolymer. fixed and formed a lubricious surface.

This guidewire has an overall length of approximately 1800mm
mm, the overall diameter is 0.36 mm.

[Effects of the Invention] As can be seen from the above description, the present invention provides a catheter guide wire in which the tip portion maintains flexibility while the substrate portion maintains rigidity at least under body temperature (37°C). A core material and a catheter guide wire can be provided.

[Brief explanation of drawings]

Figure 1 shows the stress measured at body temperature (37°C) under tensile stress in a Ti/Ni alloy containing 51 at% Ni.
FIG. 2 is a cross-sectional view of a catheter guide wire coated with a synthetic resin according to a third embodiment of the present invention. No. 1...18-8 stainless steel wire, No. 2...Tip portion subjected to heat treatment at 400°C for 10 minutes related to the first embodiment of the present invention, No. 3...First embodiment of the present invention Wire rod coated with Ni by electroplating,
No. 4... Wire rod coated with stainless steel by vapor deposition plating related to the first embodiment of the present invention, No. 5...
Wire rod coated with silicon carbide (SiC) by sputtering according to the first embodiment of the present invention, No.
No. 6: Wire rod coated with titanium nitride by sputtering according to the first embodiment of the present invention, No. 7: Clad wire subjected to heat treatment at 400° C. for 10 minutes according to the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Catheter guide wire, 2... Core material, 2a... Core material main body part, 4...
Synthetic resin coating.

Claims (1)

[Scope of Claims] 1. A catheter guide wire characterized in that, in the core material of the catheter guide wire made of a superelastic alloy, at least a part of the surface excluding the blood vessel introduction tip is covered with an inorganic coating. Core material. 2. A core material for a catheter guide wire, wherein the inorganic coating according to claim 1 is a Ni coating. 3. The core material of a catheter guide wire according to claim 1, wherein the inorganic coating has an alloy clad structure. 4. A catheter guide wire characterized in that the core material according to any one of claims 1 to 3 is coated with a synthetic resin.