JPH05293175A - Guide wire for catheter - Google Patents

Abstract

PURPOSE:To provide the guide wire for a catheter which is utilized as an implement for medical treatment and is improved particularly in the material characteristics of a core material and the operability for insertion. CONSTITUTION:The core material 2 of the guide wire 1 having the core material 2 and a coating part 3 clad on the surface of the core material 2 is formed of an Ni-Ti alloy contg. 45 to 52at.% Ni and has the characteristic that the heat quantity of at least either of the calorific value or endothermic quantity arising from the martensite transformation and reverse martensite transformation of the core material 2 is controlled to <=0.80cal/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide wire for a medical catheter, which has improved material characteristics of a core material and improved insertion operability and usability.

[0002]

2. Description of the Related Art A small tubular catheter for inspection or treatment is inserted along a blood vessel in order to inject a drug or the like into a blood vessel of a living body. Introduce to the site.

However, since a living blood vessel is complicatedly curved and branched, when a guide wire is inserted, the insertion is made easy in order to prevent the damage of the blood vessel and prevent pain and insertion trouble. The characteristics of the core material of the wire are extremely important, for example, it is required to have good operability and torque transmission as well as a good usability.

On the other hand, as a guide wire for this purpose, conventionally, a surface of a core material having a thin tip portion and a main body portion having a certain degree of rigidity is covered with a coating portion made of a biocompatible resin such as silicon or Teflon. In addition to plastics, carbon steel, stainless steel, etc. as core materials, in recent years, Japanese Patent Publication No. 24548/1990 and 2454/1990.
No. 9, Japanese Patent Publication No. 24550/1990, Ni-
It has also been proposed to use a superelastic metal body such as a Ti alloy as a core material.

In all of these proposals, shape memory alloys such as Ni--Ti alloys are much more flexible and have a higher elongation than other metal materials such as stainless steel in the region above the transformation temperature. Moreover, the so-called super-elastic function, in which the load does not increase in a certain region range in spite of the increase in strain, becomes a horizontal portion of the load, and a large strain is given by a small load, thereby improving the characteristics as the guide wire. Is intended.

[0006]

However, in the guide wire utilizing the superelastic function disclosed in the above publications, although the load and the displacement tend to increase substantially in the initial stage of the displacement load, Slight distortion, usually 1%
When the load exceeds a certain level, the strain increases while the load remains constant.The horizontal member makes the core material too flexible, and it is difficult for the insertion operator to transmit the intention of the operation to the guide wire. In addition to being inferior, it has been found that the feeling of use is poor and the body is likely to be damaged by buckling.

In order to suppress such excessive deformation, it is necessary to increase the wire diameter. However, the increase in the wire diameter increases the rigidity of the core material main body, makes insertion difficult and increases the cost. T
The i-alloy's original suppleness cannot be utilized.

In Japanese Patent Laid-Open No. 63-171570, the heat treatment conditions of the distal end portion of the guide wire and the main body portion are changed, and in Japanese Laid-Open Patent Publication No. 2-289266, the surface of the superelastic metal having the above characteristics. Each of them discloses a composite of different kinds of materials having other characteristics. However, even with such a composition, the above-mentioned problems are not sufficiently solved, and further, the production thereof is complicated and expensive, and the product It is not suitable for mass production due to the large variation in characteristics.

As a result of various developments based on such a conventional technique, the present invention has a relationship between stress and strain. In the relationship between stress and strain, the rate of increase of stress gradually decreases as the strain increases.
It is preferable to use i alloy, and it is also found that by setting the amount of heat absorption and the amount of heat generated by transformation within a predetermined range, the operability and torque transmission as well as the feeling of use are excellent in addition to the stress-strain characteristics. Therefore, the present invention has been completed, and therefore an object of the present invention is to provide a guide wire for a catheter, which has flexibility and appropriate elasticity, and has improved insertion operability, torque transmission, and usability.

[0010]

SUMMARY OF THE INVENTION The present invention is a guide wire comprising a core material and a coating portion coated on the surface of the core material, wherein the core material is Ni-containing 45 to 52 at% Ni.
This Ni-Ti is formed by a Ti-based alloy.
The system alloy is a guide wire for a catheter in which at least one of the calorific value and the endothermic value associated with the martensitic transformation and the martensite reverse transformation is 0.80 cal / g or less.

Further, in the present invention, the Ni--Ti alloy has the above-mentioned endothermic amount associated with the reverse transformation of martensite,
The guide wire for a catheter is characterized by being 0.6 cal / g or less, and the temperature difference between the starting temperature at which the Ni-Ti alloy starts martensite reverse transformation and the reverse transformation end temperature is 50 ° C. The catheter guide wire characterized by the above, the Ni-Ti based alloy does not substantially generate heat and / or endotherm in the DSC curve, and further the Ni- Ti-based alloy is 3500-500
After applying Young's modulus of 0 kgf / mm ² and strain of 5%,
The catheter guide wire is characterized by having a strain recovery rate of 85% or more that recovers when unloading.

[0012]

As described above, the catheter guide wire (hereinafter referred to as the guide wire) of the present invention has a core material of 45 to 52.
made of Ni-Ti alloy containing at% Ni, and N
The amount of heat of at least one of the exothermic or endothermic phenomena associated with the martensitic transformation and the martensitic reverse transformation of the i-Ti alloy is 0.80 cal / g or less. As a result, the stress-strain curve of the core material does not have a sudden change portion that shifts to the horizontal portion that was present in the conventional superelastic metal, and the rate of increase in stress with increasing strain is preferably Ni-Ti.
It becomes a system alloy. Even when the guide wire is inserted into the living body, the insertion state of the distal end portion can be surely transmitted to the operating side (main body portion), that is, the operator's finger, and the operator's intention can be transmitted to the distal end portion. And torque transmissibility are improved, and the usability is excellent. Furthermore, buckling can be suppressed, damage to blood vessels can be reduced, and troubles can be reduced.

[0013]

1 is an enlarged sectional view showing an embodiment of the present invention. A guide wire 1 of the present invention comprises a core material 2 and a covering portion 3 for covering the core material 2. ..

The core material 2 is a linear body of Ni-Ti alloy containing 45 to 52 at% of Ni, and has a relatively rigid main body portion 2A and a thin tip for enhancing flexibility. Part 2
B is integrally formed, and in the present embodiment, the tip portion 2B is a tapered portion whose diameter decreases toward the tip.

The core 2 has a total length of, for example, about 1 to 2 m, and the main body 2A has an appropriate diameter of about 0.2 to 0.5 mm. The tip 2B has a diameter of 0.0
The diameter is about 1 to 0.5 mm and the diameter is gradually reduced from the vicinity of the main body portion 2A toward the tip. Note that a bulge portion can be formed at the tip, and a core material having substantially the same thickness over the entire length can be used when the length is small.

Further, the core material 2 is 45 to 52a as described above.
It is formed of a Ni-Ti alloy containing t% of Ni, but an alloy containing a small amount of a third element may be used for the purpose of improving workability and mechanical properties. The third element is Cu, Fe, V, Mo, Co or the like, and does not impair the characteristics of the Ni-Ti alloy, so the content is preferably about 5 at% or less.

By setting the Ni content in the range of 45 to 52 at%, the core material itself can have preferable elastic characteristics and elastic recovery characteristics. If the Ni content is 45 at% or less, the core cannot have the above characteristics. The desired elasticity cannot be obtained.
On the other hand, if it is 52 at% or more, the characteristics cannot be similarly given, and wire drawing becomes difficult.

Further, the Ni-Ti alloy forming the core material has a heat generation amount or endothermic heat amount of 0.80 in the exothermic or endothermic phenomenon associated with martensitic transformation and martensitic reverse transformation.
It is below cal / g.

This is set based on the results of various tests. In Ni-Ti alloys exceeding 0.80 cal / g, horizontal portions similar to those of conventional superelastic alloys are likely to appear. The department becomes overly flexible when used,
Buckling is also likely to occur. In addition, it includes the transmission of the operating state from the tip to the operator, the insertability of the transmission from the operator, the torque transmissibility, etc., and the feeling of operation that can not be physically expressed in relation to the flexibility. It has been found to be inferior in usability.

With respect to both transformations, it is preferable that the endothermic amount in the reverse martensitic transformation is equal to or less than the above value in view of the use condition, as compared with the case where the calorific value in the martensitic transformation is regulated.

The calorific value and endothermic value are more preferably 0.6 cal / g or less, further preferably 0.4 c.
Al / g or less is preferable. It has been found that the above-mentioned various properties are excellent when the temperature difference between the transformation start temperature and the transformation temperature is 50 ° C or higher, preferably 70 ° C or higher. It is considered that this is because the transformation can be slowed down, the stress change can be reduced, and the stress-strain characteristics can be preferably maintained.

The Ni-Ti alloy having such characteristics can be produced by adjusting the components of the core material, processing, heat treatment conditions and the like. For example, it can be obtained by performing high-strength wire drawing with a working rate of 40% or more, followed by low-temperature heat treatment at 300 to 400 ° C.
By setting a relatively short time of about 0 to 30 seconds,
It can be determined by a test depending on the purpose, such as a slightly elevated temperature.

The amount of heat absorbed and the amount of heat generated in the transformation are DSC.
It can be calculated from the curve. FIG. 2 is an example of a DSC curve in the above-mentioned martensite reverse transformation obtained by performing differential scanning calorimetry on a part of a sample collected from the core material according to the present invention, and this DSC curve is JIS-H7101.
-1989 "Method of measuring transformation point of shape memory alloy". In this example, the sample is used without applying a special heat treatment to the core material,
A product manufactured by Rigaku Denki Co., Ltd. was used as a DSC measuring device (differential scanning calorimeter).

In the measurement, it is preferable to adjust the baseline in advance so that it becomes a straight line parallel to the temperature axis.

The DSC curve of the Ni-Ti alloy according to the present invention is much flatter than the DSC curve of the superelastic Ni-Ti alloy having the remarkable peak shown in FIG. I understand. This is considered to be due to the wide transformation temperature range.

For example, from the DSC curve of FIG. 2, in order to obtain the endothermic amount in the martensite reverse transformation, the area enclosed by the endothermic peak curve portion and the baseline is obtained,
It is shown as the value divided by the sample weight, and the unit is cal / g
Is used. In the present invention, when the peak occurs at two or more places, each peak is evaluated and the maximum part is shown.

When there is a difference between the baselines before and after the peak as shown in FIG. 4, the endothermic peak curve portion is calculated from the area of the shaded area surrounded by a straight line between the two points apart from each baseline.

Further, the martensite reverse transformation start temperature (As
The temperature) is represented by the intersection of the base line and the peak extension line obtained by extending the end portion of the peak curve portion, and the end temperature is similarly defined.

The calorific value of the martensitic transformation is also determined by the area of the portion surrounded by the base line, as in the case of the endothermic value.

In the Ni--Ti alloy of the present invention, DS
In connection with the C curve being substantially flattened, the Ms
Point (Martensite Transformation Start Temperature) and Mf Point (Martensite Transformation End Temperature), As Point (Martensite Reverse Transformation Start Temperature) and As Point (Martensite Reverse Transformation End Temperature)
Is defined as the point where the change starts and ends from the baseline.

Further, the Ni-Ti alloy according to the present invention may include those having a characteristic that substantial heat generation and / or endothermic phenomenon does not appear in the DSC curve as shown in FIG. The heat generation and heat absorption of the Ni-Ti alloy are substantially zero. The characteristics of the Ni-Ti alloy in which the DSC curve does not show substantial exothermic and / or endothermic phenomena are those that do not cause transformation, or that the transformation is extremely slow and the transformation temperature is wide, and the JIS standard In the measuring method of, it means a curve change that cannot be grasped substantially.

Such a material can be seen as a material which has been subjected to strong work hardening and heat treatment at a relatively low temperature. Since such material has a relatively large elasticity, it has a predetermined strain range. It can be used to obtain greater strength at. In addition, such a product can be reduced in size, and thereby the flexibility can be improved rather, which is often preferable.

The Ni-Ti alloy has a Young's modulus of 35.
The characteristics can be further improved by adjusting the amount to be from 00 to 5000 kgf / mm ² . The Young's modulus is defined as the slope of the proportional region that appears initially at the time of load application in the applied-strain diagram. By setting the Young's modulus to such a value, in relation to the heat generation amount and the heat absorption amount, after applying a load that imparts 5% elongation deformation, the permanent strain remaining when the load is reduced is 15%. It is easy to set the ratio to 10% or less, that is, the recovery rate against deformation is 85% or more, preferably 90% or more.

The Ni-Ti alloy is used as the core material 2 as a single wire or as a plurality of single wires by a method such as twisting. Further, those formed by twisting are configured so that the Ni-Ti alloy can exhibit the above-mentioned characteristics in the state of being the core material 2.

When the twisted wire is used, for example, the twisted wire material is thinned into a predetermined dimension at a predetermined processing rate by mechanical processing such as a wire drawing machine and heat-treated to obtain a surface thereof. Unevenness is eliminated by the processing,
In addition, it is possible to enhance the Young's modulus, which is the effect of the stranded wire, and the recovery effect due to the large elasticity.

On the surface of the core material 2, there is formed the covering portion 3 which is covered with a human body-compatible resin such as polyurethane, nylon, silicon, or Teflon that is compatible with the human body. When forming the covering portion 3, it is preferable to avoid high temperature and long time treatment so as not to impair the characteristics of the core material 2.

The present invention will be further described below by using the test results of the present invention.

Test Example-1 Table 1 shows 9 kinds of 5 having different wire diameters of about 0.4 mm.
Sample A made of 0.9 at% Ni-Ti alloy fine wire
I (Samples A to E are example products, others are comparative example products)
The results of measuring the load values at 3%, 5%, and 7% elongation by a tensile test, the recovery rate when unloading after giving 7% elongation, and the Young's modulus were measured, and The result of measuring the heat absorption amount associated with the transformation, the operability, the torque transmission property, and the suitability for use at the same time are shown.

The temperatures shown in Table 1 of Samples A to I are the heat treatment temperatures of the core material, and in a 2 m long furnace at this temperature,
Passing and cooling at a speed of 15 m / min. Figure 5
13 shows a stress-strain diagram for each thin wire.

With respect to these core materials, the 5% strain recovery rate in the tensile test was 85% or more, and the value at the 5% strain amount was naturally higher than the above value, and was in a range that could be sufficiently used. Moreover, as a result, none of the products of the present invention has a region where the load is constant, and the strain and the stress are almost correlated, and the load is higher than that of the comparative product.

The amount of heat absorption is calculated and measured as described above from the measurement by the above-mentioned JIS of the differential scanning calorimeter (DSC measuring device).

Further, the operability, the torque transmission property, and the feeling of use were measured with a single wire of Ni--Ti alloy from the tip side.
The measurement is performed by using a guide wire in which the diameter of the core is continuously reduced by a taper portion having a length of mm and the tip is about 0.08 to 0.1 mm and the core material is uniformly coated with a silicon resin.

[0043]

[Table 1]

The operability, torque transmission and usability are measured by
The guide wire was inserted into a tube having a length of 1 m which was deformed into a continuous wave type (pitch: 30 mm, height: 5 mm), and the ease of insertion at that time was determined by a feeling test by a therapist. ○ means good, Δ means a little bad, and × means bad.

Further, the torque transmissibility when rotated after being inserted is also tested and is similarly displayed. Regarding the torque transmissibility, the torsional response is poor, and the one having a large time difference between the twisting to the tip is defective.

Furthermore, the feeling of use is a measurement of the feeling when using them comprehensively, and was measured at the same time as the above-mentioned operability and torque transmissibility tests, and also an animal test. During these measurements, the presence or absence of damage due to buckling was also confirmed. In addition, those that do not buckle are indicated by ○, and those that tend to buckle are indicated by Δ.

As is clear from the table, the guide wires A to E having a calorific value of the endothermic phenomenon of 0.80 cal / g or less obtained by the DSC measurement have good operability and usability, and are inserted. There was little buckling associated with. Further, the heat generation amount due to the martensitic transformation in the samples A to E was also measured in the same manner, but the heat amount was smaller than each heat absorption amount.

[0048]

As described above, in the guide wire of the present invention, by adopting the Ni-Ti type alloy having a small amount of transformation heat as the core material, the insertion operability and the torque transmission property as well as the usability are improved. The physical distress of the patient,
The operation time can be shortened and the doctor's burden on the operation can be reduced.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing an embodiment of the present invention.

FIG. 2 is an example of a DSC curve of a Ni—Ti alloy according to the present invention.

FIG. 3 is an example of a DSC curve of a Ni—Ti alloy according to the present invention.

FIG. 4 is an example of a DSC curve of superelastic metal.

FIG. 5 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 6 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 7 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 8 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 9 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 10 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 11 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 12 is a diagram illustrating a stress-strain curve in a tensile test.

FIG. 13 is a diagram illustrating a stress-strain curve in a tensile test.

[Explanation of symbols]

 1 Guide wire 2 Core material 3 Cover part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Jun Matsuda 4-17-1, Ikenomiya, Hirakata-shi, Osaka, Japan Inside Hirakata factory of Seisei Co., Ltd. No. 17-1 Nihon Seisen Co., Ltd. Hirakata Plant (72) Inventor Takeyasu Yamada 8-4-302 Wakamatsu, Funabashi City, Chiba Prefecture (72) Teruo Hashimoto 3-9-2 East, Kuki City, Saitama Prefecture (72) ) Inventor Kazunori Kamishohara 2-15-15 Kasuga-cho, Nerima-ku, Tokyo

Claims (5)

[Claims] 1. A guide wire comprising a core material and a coating portion coated on the surface of the core material, wherein the core material is 45 to 52.
The Ni-Ti alloy is formed from a Ni-Ti alloy containing at% Ni, and the Ni-Ti alloy has a calorific value or an endothermic calorific value of 0.80 cal / A guide wire for a catheter of g or less. 2. The guide wire for a catheter according to claim 1, wherein the endothermic amount of the Ni-Ti alloy due to the reverse transformation of martensite is 0.60 cal / g or less. 3. The Ni-Ti alloy according to claim 1, wherein the temperature difference between the start temperature at which the reverse transformation of martensite starts and the end temperature of the reverse transformation is 50 ° C. or more.
A guide wire for a catheter as described above. 4. The guide wire for a catheter according to claim 1, wherein the Ni—Ti alloy does not substantially generate heat and / or absorb heat in a DSC curve. 5. The Ni-Ti alloy is 3500-50.
The Young's modulus of 00 kgf / mm ² and the strain recovery rate that recovers when the load is unloaded after applying a load of 5% of the strain is 85% or more, 5. Guide wire for catheters.