JPH11128363A - Production of catheter guide wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a catheter guide wire having the high pliability and torque transmittability of a TiNi based alloy and having high reliability. SOLUTION: The catheter guide wire consists of a core wire 2 consisting of a TiNi alloy wire having a superelastic characteristic in a temp. range of 0 to 40 deg.C and a coating material 1 coating this core wire from the outer side. The sectional area of at the front end part of the core wire 2 is made finer than the other parts by etching. For example, the TiNi alloy wire 2 of 0.6 mm in diameter is etched by 15 mm at the front end to 0.2 mm in diameter and is subjected to 'Teflon (R)' coating. The front end working method is not restricted to the etching treatment and is executable by a cutting and grinding method and swaging as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a catheter / guidewire.

[0002]

2. Description of the Related Art It is known that a TiNi alloy exhibits a remarkable shape memory effect accompanying a reverse transformation of a thermoelastic martensitic transformation. At the same time, it is known that a pseudoelastic effect is also exhibited.

[0003] The pseudoelastic effect means that when a stress is applied at a temperature higher than the reverse transformation completion temperature (hereinafter abbreviated as Af) of the same alloy, apparently several percent to 10% of plastic deformation is caused. It is the property of completely returning to the original at the time of loading. Here, the pseudoelastic effect is also called a superelastic effect.

[0004] On the other hand, a conventional catheter guide wire has a torque transmitting property and a suppleness by a combination of a stainless steel or piano wire heli-carbane and a straight wire.

[0005]

However, in such a structure, there is a problem in that the friction between the catheter and the guide wire / helical carnet is large. Further, since the bending strain limit is about 0.2%, it is difficult to bend before use and cannot be used repeatedly.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive and highly reliable catheter which simplifies the structure of a guide wire, has high flexibility (particularly, flexibility at the tip) and large torque transmission. -To provide a method for manufacturing a guide wire.

According to the present invention, the cross-sectional area of the tip portion of a core wire made of a TiNi alloy wire having superelastic properties in a temperature range of 0 ° C. to 40 ° C. is determined by a group consisting of etching, cutting and grinding, and swaging. A method of manufacturing a catheter / guide wire, characterized in that at least one of the methods is used to make it thinner than other parts, and the obtained core wire is coated from the outside with an outer peripheral member.

[0008]

As is well known, when a catheter guide wire is inserted into a blood vessel, it must be inserted along the blood vessel without being damaged. For this reason, the catheter / guide wire according to the present invention includes a core wire made of a TiNi alloy wire and an outer peripheral member coated with the core wire from the outside. In the method for manufacturing a catheter / guide wire according to the present invention, the cross-sectional area of the distal end portion of the core wire is at least one selected from the group consisting of etching, cutting and grinding, and swaging.
One way is to make it thinner than the other. Thus, the distal end of the catheter guidewire is configured to maintain some strength and durability. In the present invention,
Since the tip of the core wire is thinned by the above-mentioned method of shaving or melting, the TiNi alloy wire is not distorted, and no post-treatment such as heat treatment for removing the distortion is required, and the desired superelasticity is stably obtained. A catheter guide wire having characteristics can be obtained. Further, the tip portion may be processed into a semicircular shape for elderly people and the like.

[0009]

Next, the present invention will be described based on embodiments.

[0010] Ti-51.0a heat-treated after wire drawing
FIG. 2 shows a stress-strain curve of the t% Ni alloy (cold working ratio: 40%).

Although the embodiment shows the case where the tensile temperature is 0 ° C. to 40 ° C., the alloy wire can be almost completely restored to the elongation strain of 5% at the same time when the stress is unloaded. I have. In particular, the effect is remarkable at 10 ° C to 40 ° C.

On the other hand, in view of the fact that the stainless steel wire has an elastic limit of about 0.2%, it can be seen that the alloy wire is far superior in flexibility.

The heat treatment conditions after the wire drawing are determined by taking into account the transformation temperature, the cold working ratio, and the pseudoelastic effect temperature range of the same alloy. For a Ti-51.0 at% Ni alloy, a φ0.5 to φ0.7 wire with a cold working rate of 40%, 37
The above characteristics can be obtained at 0 ° C. × 1 m / 10 minutes (furnace leveling 1 m).

The heat-treated alloy wire was tapered at its tip to maintain its flexibility.

In this embodiment, the processing method is HF: HNO
₃ : Etching was performed by dipping in a solution of H ₂ O = 1: 1: 1.

It is necessary to determine the diameter of the tip portion narrowed by etching depending on the use site of the catheter and the purpose (for the heart, brain, etc., or for children, the elderly, etc.).

The method of processing the tip portion is not limited to the above-described etching process, but can be performed by a cutting grinding method or swaging.

The obtained alloy wire was coated with Teflon as shown in FIG. 1 to prevent friction with the catheter, direct contact with the human body and damage to the inserted blood vessel. The coating material 1 may be made of polyethylene or the like, but the coating amount must be determined according to the inner diameter of the catheter.

In this embodiment, the TiNi alloy wire 2 having a diameter of 0.6 mm was etched at a tip of 15 mm as shown in FIG. 1 to have a diameter of 0.2 mm, and was coated with Teflon. As a result, the tip part was completely restored to 5% bending at 30 ° C. For twisting, twisting the end of the 1.5 m wire operated the tip with at least 30 grams of force.

It has been found that such a function is hardly impaired by repetition. FIG. 3 shows the results of the repeated measurement at 30 ° C. In FIG. 3, N indicates the number of repetitions.

[0021]

As described above, according to the present invention, it is possible to provide an inexpensive and highly reliable catheter guide wire since the structure of the guide wire is simplified, and the guide wire has high flexibility and large torque transmission. became. Further, in the present invention, the tip portion of the core wire is subjected to etching, cutting and grinding, or any of swaging methods,
Since it is thinner than the other parts, the dimensional stability is good, and T is compared with the method of stretching and thinning the metal wire, which is generally considered to be performed for tapering the metal wire.
No strain is applied to the iNi alloy wire, no post-treatment such as heat treatment for removing strain is required, and a catheter / guide wire having desired superelastic properties can be stably obtained.

The alloy according to the present invention is composed of Ni: 5
A 0.5-51.0 at% TiNi alloy is preferred,
Ni: 50.3 to 52.0 at% TiNi alloy is also possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a catheter / guide wire according to an embodiment of the present invention.

FIG. 2 shows Ti-51.0 at% Ni used in the present invention.
It is a stress F-strain (epsilon) curve diagram of the alloy wire in 0-40 degreeC.

FIG. 3 shows a catheter guide wire shown in FIG.
FIG. 4 is a stress σ-strain ε curve diagram when repeated at 0 ° C.

[Explanation of symbols]

 1 Coating material 2 TiNi alloy wire

Claims (1)

[Claims] 1. A cross-sectional area of a tip portion of a core wire made of a TiNi alloy wire having a superelastic property in a temperature range of 0 ° C. to 40 ° C. is at least one selected from the group consisting of etching, cutting and grinding, and swaging. A method for manufacturing a catheter / guide wire, comprising narrowing the obtained core wire from the other portion by one of the methods and coating the obtained core wire from the outside with an outer peripheral member.