JPH042273B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a material for a core material of a catheter guide wire which is a medical instrument, a core material of a catheter guide wire using the material, and a catheter guide wire using the core material. [Prior Art] In general, a catheter guide wire 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 catheter is inserted into a living body. A medical device that guides a catheter in advance of a catheter to a target site within a blood vessel, particularly a blood vessel. For this reason, the core material of the catheter guidewire is
Elasticity that allows 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 at biological temperature (approximately 37°C) Generally, 18-8
The basic material is stainless steel. However, when a processed Ti/Ni alloy material with simple elastic properties is used as a core material, as the elongation deformation increases, the load required for that deformation also increases almost linearly, resulting in an increase in the amount of stress inside the blood vessel. There was a problem in that the introduction work could not be performed with constant stress, causing physiological pain to both the doctor and the patient. Therefore, in the past, by using an annealed alloy that was improved by annealing a Ti/Ni alloy, the inside of the body (approximately
37°C), the catheter guidewire exhibits increased elongation deformation even under constant stress (hereinafter referred to as superelastic properties), and can reversibly absorb and release energy and reversibly deform and recover its shape. Core material was obtained (Japanese Unexamined Patent Publication No. 171570/1983). [Problems to be Solved by the Invention] However, since the annealed Ti/Ni alloy used as the material for conventional catheter guide wires has only superelastic properties, the tip of the guide wire The disadvantage is that it is difficult to cold bend the section into a desired shape depending on the intended location. In addition, in order to fix the desired shape using such an annealed Ti/Ni alloy, it is necessary to heat-treat the annealed alloy again at a high temperature of 400° C. or higher to add the shape. This makes it difficult to shape the distal end portion in a way that is responsive to clinical practice, and it is necessary to prepare in advance core materials for catheter guide wires having several types of distal end shapes. Therefore, in view of the above-mentioned drawbacks, the first technical problem of the present invention is to provide a material for the core material of a catheter guide wire with excellent cold workability and a material for the core material of a catheter guide wire in order to obtain a core material of a catheter guide wire having a desired shape. An object of the present invention is to provide a catheter guide wire with the following features. A second technical object of the present invention is to provide a core material for a catheter guide wire that substantially exhibits superelastic properties at 37°C and has excellent plasticity against deformation at temperatures below 80°C. An object of the present invention is to provide a catheter guide wire having the following features. A third technical object of the present invention is to effectively utilize the core material of the catheter guide wire to cold bend the distal end of the guide wire into a desired shape depending on the target area. An object of the present invention is to provide a core material for a catheter guide wire that can be used as a core material, and a catheter guide wire equipped with the core material. [Means for Solving the Problems] According to the present invention, in atomic percent, Ni45.0~
Ti including 51.0at%, Fe0.5~5.0at%, balance Ti.
A material for the core material of a catheter guide wire containing a Ni-Fe alloy and having excellent cold workability can be obtained. Further, according to the present invention, the core material of the catheter guide wire has a superelastic alloy material produced by substantially subjecting it to heat treatment at 400 to 1000 °C (preferably 400 to 500 °C), A core material for a catheter guide wire is obtained which is characterized by substantially exhibiting superelastic properties at 37°C and having plasticity against shape deformation at temperatures below 80°C. Further, according to the present invention, there is obtained a core material for a catheter guide wire, wherein at least the distal end portion of the core material is made of the superelastic alloy material. Further, according to the present invention, there is obtained a catheter guide wire characterized in that the core material is coated with a synthetic resin. [Example] Next, an example of the present invention will be described with reference to the drawings. Example 1 First, as listed in Table 1, the present invention alloys Nos. 3 to 5 and No. 9 to 11 having the compositions according to the examples of the present invention (Ti/Ni/Fe alloy compositions) and the conventional alloys of
Conventional alloy No. 1 having a Ti/Ni alloy composition and comparative alloys No. 2, 7, and 8 as comparative examples were produced by high-frequency vacuum melting. In addition, arc melting method,
Electron beam melting or powder metallurgy may also be used. Each alloy No. 1 to 11 having the above composition was solution treated at 900 to 1000°C, then hot forged and hot rolled at about 900°C,
After that, it is drawn to 0.7mmφ by cold working,
It was subjected to strain relief annealing at approximately 900°C and processed to a size of 0.5 mmφ.

【table】

[Table] (Workability test) Table 1 shows the hot workability and cold workability of each alloy No. 1 to No. 11 observed during the above hot working and cold working. As a result, the present invention alloys Nos. 3 to 5, Nos. 9 to 11, and comparative alloy No. 2 were found to have better cold workability overall than conventional alloy No. 1. I understand.
In addition, as can be seen from comparative alloys No. 7 and 8, Fe
When the amount of addition exceeds 5.0 at%, not only the hot workability deteriorates, but also the final cold working from 0.7 mmφ to 0.5 mmφ is impossible. That is, Fe within the range of 0.25 to 5.0at%,
Invention alloys No. 3 to 5, No. 9 to Ti/Ni added
11 and comparative alloy No. 2 are better than conventional and comparative alloy No. 2.
It can be seen that the hot workability and cold workability are generally improved compared to No. 1, 7, and 8. (Superelastic property test) Next, each alloy No. processed into a size of 0.5 mmφ.
1 to 11, respectively 900℃, 700℃, 600℃, 500℃
After heat treatment (annealing) at 400°C, 400°C, and 300°C for 1 hour, a tensile test (3% strain) was performed at room temperature (20°C) and body temperature (37°C), and each stress-strain curve was measured. . Note that comparative alloys Nos. 7 and 8 were not subjected to tensile testing because they could not be cold worked. Figure 1 shows the processed materials (unannealed alloy) of conventional alloy No. 1 and invention alloy No. 4, which were measured at room temperature (20°C) under tensile stress.
The stress-strain curves are shown for the 500°C annealed alloy. An example of a commercially available 18-18 stainless steel wire is also shown. As a result, the annealed alloy No. 4 of the present invention, like the annealed alloy No. 1 of the conventional alloy, is a superelastic alloy that maintains supple superelastic properties like rubber, and is resistant to changes in elongation. We were able to recognize the yield stress at which the stress becomes constant. Table 2 shows each alloy No. 1 to 11 at different heat treatment temperatures measured at body temperature (37℃) under stress during tension.
The stress-strain curves of the annealed alloys are shown.

[Table] As a result, in both the conventional alloy and the annealed alloys of the present invention alloys No. 1 to 11, in the cold-worked material, the strain was resolved as soon as the load was removed, but no clear yield point was observed. On the other hand, superelastic properties showing clear yielding were obtained from materials heat-treated at temperatures of approximately 400°C or higher.
In addition, good superelastic properties can be obtained for both the conventional alloy and the invention alloy Nos. 1 to 11 annealed alloys.
It was ~500℃. When the temperature exceeds 600℃, the yield stress level is about half that of the alloy annealed at 400 to 500℃, but on the other hand, the superelastic properties worsen, and the material deteriorates significantly, especially when subjected to repeated motion in tensile tests. Indicated. Therefore, as a material for catheter guidewires, it is recommended to absorb and release reversible energy associated with the loading and removal of deformation stress, including twisting, that occurs during introduction and movement into blood vessels at biological temperature (approximately 37°C). Since a superelastic alloy having superelastic properties that can be deformed and recovered into a desired shape is required, it is found that heat treatment at 400 to 500°C is appropriate for both the conventional alloy and invention alloy Nos. 1 to 11. In addition, in cases where repeated motion is not necessarily required, a superelastic alloy that absorbs and releases energy and reversibly deforms and recovers its shape under low stress levels can be created by heat treatment at 600℃ or higher. You can also get it. (Plasticity test) Next, the degree of residual strain at the time of bending stress release after bending at 90 degrees at 37 °C for the conventional alloy and the alloy materials annealed at 500 °C of the present invention alloys No. 1 to 11. and the degree of residual strain due to heating at 80°C were measured and shown in Table 3.

【table】

[Table] The results show that conventional alloy No. 1 has a large superelastic effect, so it returns to almost its original shape as soon as the stress is released at room temperature, making plastic working difficult. Furthermore, when heated to 80°C, even the slightest residual strain was eliminated. Therefore, in order to fix the conventional annealed alloy into a specific shape, it is necessary to heat it to 400 to 500° C. under deformation restraint. Furthermore, although 0.25 at% of Fe was added to comparative alloy No. 2, almost no residual strain was observed, and the results were similar to those of conventional alloy No. 1. On the other hand, the present invention alloy No. 3 with Fe0.5at% addition has
The addition effect was observed, and a residual strain of approximately 50% was obtained at 37°C. Even when heated to 80°C, approximately 10% strain remained. In alloys Nos. 4 to 6 and 9 to 11 of the present invention containing 1.0 at% or more of Fe, almost 100% remained at 37°C, and 90% or more remained even when heated to 80°C. Therefore, the present invention alloy No. 3 with Fe addition of 0.5 at% or more
6 and 9 to 11 were able to obtain plasticity to fix the deformed shape without requiring heat treatment at a very specific temperature of 400 to 500°C as in the past. Moreover, hot water used clinically, etc.
It was also able to maintain its plasticity by maintaining more than 90% of its deformed shape even in an environment of 80°C. Next, as shown in Fig. 2, the alloy of the present invention No. 5 was
For alloy materials annealed at 500℃, 20℃, 40℃, 60℃,
and the stress-strain curve at a temperature of 80℃,
A more detailed observation was made. As a result, it was found that some strain remained even at 40°C, so it was possible to fix the deformed shape even by heating at 40°C when bending at 90°C. It can be seen that this is a material for catheter guide wires with excellent plasticity. This means that the residual strain at 40°C is about 5%, and the strain applied during use of the catheter guide wire is at most 1%.
This is because the amount remains at about 2%, so there is no problem with repeated deformation. In addition, in order to obtain more stable plastic deformation,
It can be easily understood from Fig. 2 that the deformation can be achieved by heating it to 60°C or 80°C. From the above test results, Fe0.5at% or more was added.
By using a superelastic alloy, which is an annealed Ti/Ni/Fe alloy that is heat-treated (annealed) at 400 to 500°C, as the core material of the catheter guide wire,
It can be cold bent (shape deformed) without losing its perfect superelastic properties at body temperature (37°C), and has the plasticity to maintain stable shape deformation even at clinically effective use temperatures (below 80°C). can give. In addition, if the annealing temperature exceeds 500℃,
At room temperature and body temperature, the superelastic properties deteriorate and, conversely, the plasticity increases, so when the deformation stress is small,
If you want more stability of the deformed shape, 500
An annealing temperature exceeding ℃ becomes effective. Example 2 Invention alloy No. 4 shown in Example 1 and conventional alloy No.
1 were butt-jointed with a diameter of 0.7 mm, subjected to strain relief annealing at a temperature of approximately 900°C, and processed to a diameter of 0.5 mm. After heat-treating (annealing) the obtained composite alloy wire at 400°C for 1 hour, a bending test was conducted for each alloy part. The results were similar to those shown in Table 3 of the first example. As a result, the tip of the core material of the catheter guide wire is made of the present invention alloy No. 4,
It can be seen that it is possible to use conventional alloy No. 1 as the substrate. In other words, the tip of the core material is
By configuring a core material that can be easily deformed into a desired shape at a temperature of 80°C or lower and exhibits superelastic properties that prevent the substrate from deforming easily,
A core material for a catheter guide wire that is suitable for clinical use can be obtained. Note that such a composite alloy wire is tapered only at its tip, and then coated over its entire length with a polymer such as urethane. However, when the composite alloy wire in this example is bonded to conventional stainless steel wire, piano wire, etc. to make a catheter guide wire, mechanical restraint such as caulking is required to increase the bonding strength. is preferred. Example 3 As shown in FIG. 3, 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,
Fluororesins, silicone rubber, elastomers, composite materials, and the like 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. Also,
The synthetic resin film 4 is coated with an anticoagulant such as heparin or urokinase, or an anticoagulant material such as silicone rubber, a block copolymer of urethane and silicone (registered trademark Abcosan), or a hydroxyethyl methacrylate-styrene copolymer. It's okay. 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, it is preferable to mix a finely powdered X-ray contrast substance made of a single metal or a compound such as Ba, W, Bi, or Pb into the synthetic resin forming the synthetic resin coating 4. Guidewire 1 being introduced into the blood vessel
It becomes easy to confirm the entire position of the Synthetic resin coating 4
has a substantially uniform outer diameter, as described above. "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 the guide wire substantially 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 closely adhered to the inner core 2 using a 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 at the distal and proximal ends of the inner core 2 or at an appropriate portion of the inner core by adhesion or melt molding. 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. 3 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. That is, the core material 2 of the guide wire in this example has a total length of 1800 mm, a diameter of 0.06 mm at the tip, a diameter of 0.25 mm at the rear end, and a tapered diameter of 120 mm from the tip toward the tip. created something. 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, according to the present invention, since a Ti-Ni-Fe alloy containing a predetermined amount of Fe is used, the core of the catheter guide wire has excellent cold workability. We can provide materials for wood. Since we used a superelastic alloy obtained by annealing the Ti/Ni/Fe alloy, it essentially exhibits superelastic properties at 37°C and also shows plasticity when deformed at temperatures below 80°C. A core material for a catheter guide wire with excellent properties can be provided. Furthermore, since at least the distal end of the core material of the catheter guidewire is made of the above catheter guidewire material, the distal end of the catheter guidewire can be cold bent into a desired shape depending on the target area. A core material can be provided.

[Brief explanation of drawings]

Figure 1 shows the processed material (unannealed alloy) of conventional alloy No. 1 and invention alloy No. 4, which were measured at room temperature (20°C) under tensile stress.
Figure 2 shows the stress-strain curve of the alloy annealed at 500°C.
For annealed alloy materials, 20℃, 40℃, 60℃, and
FIG. 3 is a side view of a catheter guide wire coated with a synthetic resin according to the present invention, which shows stress-strain curves at a temperature of 80°C. 1... Guide wire, 2... Inner core, 2a...
Inner core body part, 4...Synthetic resin.

Claims (1)

[Claims] 1 In terms of atomic percent, Ni45.0 to 51.0 at%,
A material for the core material of catheter guide wires that has excellent cold workability and is made of a Ti/Ni/Fe alloy containing 0.5 to 5.0 at% Fe and the remainder Ti. 2. A core material for a catheter guide wire, characterized in that the alloy according to claim 1 exhibits substantially superelastic properties at 37°C and has plasticity against shape deformation at 80°C or lower. 3. A core material for a catheter guide wire, wherein at least a distal end portion of the core material is made of the superelastic alloy material according to claim 2. 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.