JP2001037867A - Medical tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft distal end part capable of easily deforming the distal end part according to a shape of a lesion part of an arrival part by short-time heat treatment without hurting a blood vessel by forming a medical tube of a shape memory alloy mainly composed of TiNi having the Ni concentration less than a prescribed value. SOLUTION: A medical tube is a slender tube composed of a base part 2 and a distal end part 3, and the tube is formed of a shape memory alloy mainly composed of TiNi having the Ni concentration less than a 50.3 atomic percent. This shape memory alloy is small in a transformation temperature change by a heat treatment condition, and when performing recrystallization, a transformation temperature is decided by the alloy composition. Since the transformation temperature is higher than a living body temperature, a distal end part of the tube can be softened by organism temperature. The recrystallization is a short time as a heat treatment temperature is high, and is completed in a treatment temperature of several minutes to about one hour. In a dimension of the base part 2 and the distal end part 3, for example, the respective lengths are 1,200 mm and 300 mm, an external shape is 0.7 mm, and an inside diameter is 0.6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medical tube, and more particularly, to a medical tube made of a shape memory alloy and used for a catheter or the like.

[0002]

2. Description of the Related Art In recent years, angiographic diagnosis in which a catheter is inserted into a blood vessel and a contrast medium is injected, and vascular dilatation surgery using a balloon catheter have been used for diagnosis and treatment of a stenotic blood part, an occluded part, and an aneurysm of a blood vessel. Is being done.

Hitherto, as this kind of catheter, there has been proposed a catheter having a base and a distal end, and at least the base formed of a superelastic alloy tube. By using the superelastic alloy tube for the base, torque transmission and protrusion properties necessary for obtaining good hand operability are ensured, and kink resistance, which is hard to bend, is obtained.

[0004] On the other hand, unlike the base, the distal end of the catheter is required to be soft so as not to damage the blood vessel, to be able to easily enter a bent portion, and to be easily deformable. That is, a medical tube is required to have these different characteristics.

As a solution to this problem, a method is adopted in which the transformation temperature of the distal end is set to be higher than the living body temperature, so that only the distal end is softened at the living body temperature. A method has been proposed that inserts in a small shape and recovers to the shape corresponding to the affected area at the reaching site

[0006] Further, means for realizing these medical tubes include TiN having a Ni concentration of 50.3 atomic percent or more.
It has been utilized that the transformation temperature can be arbitrarily changed depending on the heat treatment conditions using an i-alloy. That is, by using a TiNi alloy having a Ni concentration capable of obtaining a superelastic effect at a living body temperature and heat-treating the tip of the superelastic tube to raise the transformation temperature to at least the living body temperature, It was possible to obtain the effect.

[0007]

However, the above-described conventional means has the following disadvantages. That is, 50.
In the case of a medical tube such as a catheter using a TiNi alloy of 3 atomic percent or more, an aging heat treatment at 400 ° C. or more for several hours or more is required to raise the transformation point to the body temperature or more.

Further, for example, in order to reduce the yield stress at the tip to about half of the base, at least 40
An aging heat treatment at 0 ° C. or more for more than ten hours is required, and when this is manufactured, there has been a problem that a long-time heat treatment causes an increase in cost.

Accordingly, the present invention eliminates the above-mentioned disadvantages,
With a short heat treatment and without damaging the blood vessels,
It is an object of the present invention to provide a medical tube having a soft distal end that can be easily deformed in accordance with the shape of an affected area at an arrival site.

[0010]

According to the present invention, there is provided a medical tube made of a shape memory alloy mainly composed of TiNi having a Ni concentration of less than 50.3 atomic percent and having a base and a softer tip. The base is heat-treated at a relatively low temperature after the final processing to obtain superelasticity or incomplete superelasticity near a living body temperature of 37 ° C. Further, the tip portion can be formed to be softer than the base portion by a recrystallization treatment or an incomplete recrystallization treatment after processing, and a shape memory effect can be obtained.

In addition, Ti of less than 50.3 atomic percent
In a shape memory alloy containing Ni as a main component, a change in transformation temperature due to heat treatment conditions is small. If recrystallization is performed, the transformation temperature is determined by the alloy composition. The transformation temperature is
Since the temperature is higher than the biological temperature, the distal end of the tube can be softened at the biological temperature. The higher the processing temperature, the shorter the recrystallization, and the recrystallization is completed in a processing time of several minutes to about one hour.

That is, the present invention relates to a medical tube comprising an elongated tube having a base and a distal end,
The tube is a medical tube made of a shape memory alloy containing TiNi having a Ni concentration of less than 50.3 atomic percent as a main component.

The present invention also provides the above-mentioned medical tube, wherein the base has at least superelasticity at a living body temperature of about 37 ° C.

Further, the present invention is the medical tube described above, wherein the distal end portion exhibits a shape memory effect at a living body temperature of around 37 ° C.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described.

FIG. 1 is a perspective view of a medical tube according to a first embodiment of the present invention. In FIG. 1, a medical tube 1 is an elongated tube composed of a base portion 2 and a distal end portion 3, and exhibits superelasticity or incomplete superelasticity at a living body temperature near 37 ° C. The distal end portion 3 is soft, can be deformed without damaging the blood vessel, and can easily enter a bent portion. The dimensions of the base 2 and the tip 3 are, for example, 1200 mm and 300 mm, respectively, in length.
The outer diameter is 0.7 mm and the inner diameter is 0.6 mm.

Next, a specific manufacturing method of the medical tube will be described. 50 atomic percent Ni, balance T
The alloy having the composition i was subjected to hot working and cold working to obtain a tube material having an outer diameter of 0.7 mm and an inner diameter of 0.6 mm. Thereafter, the tube was heat-treated using a running furnace.

Table 1 shows the working ratios and heat treatment conditions of the invention products 1 and 2 produced under different cold working conditions and heat treatment conditions. In addition, Table 2 shows the heat treatment conditions for the tips of Invention 3, Invention 4, and Invention 5 produced by changing the heat treatment conditions to further treat Invention 1 at the tip.

[0020]

[Table 1]

[0021]

[Table 2]

Next, a second embodiment of the present invention will be described.

FIG. 2 is an explanatory view showing a tip heat treatment method according to a second embodiment of the present invention. Inventive product 3,
The invention product 4 and the invention product 5 are inserted into the furnace chamber 6 at a predetermined temperature covered with the refractory material 5 through the hole 7 formed in a part of the furnace wall, with the distal end portion of one end of the tube 4 extending over 300 mm. ,
Heat treatment is performed at a predetermined temperature and time.

FIG. 3 is a graph showing the stress in a three-point bending test at 37 ° C. of a medical tube according to a second embodiment of the present invention.
It is a figure showing a distortion curve. The invention 1 obtained in the first embodiment exhibits superelastic properties, and when used for a catheter, torque transmission necessary for obtaining good hand operability,
Protruding properties and kink resistance that is hard to bend were obtained.

The invention product 2 shows imperfect superelasticity showing a residual strain of 0.08 mm, and the yield stress is
It is smaller than Invention 1 and has more flexible characteristics. Thus, by changing the working ratio and the heat treatment conditions, it is possible to impart different stress-strain characteristics to the base 2.

The stress of the invention product 3 at the time of pushing it in by 1 mm is about 40% of that of the base of the invention 1, and the tip is softer than the base. It can easily enter and easily deform.

The invention product 4 is completely recrystallized, and the invention product 5 is in a state where the recrystallization has not completely occurred. % And 46%, showing a softness different from that of the inventive product 3. Thus, by adjusting the heat treatment conditions, different stress-strain characteristics at the tip can be provided.

The stress value (37 ° C.) between the base and the tip of the invention when the tip was pushed in by 1 mm was obtained by changing the heat treatment temperature and the treatment time of an alloy tube having a composition of 50 atomic percent of Ni and the balance of Ti. Table 3 shows the stress values of comparative examples in which alloy tubes having a composition of 51 atomic percent balance of Ni and Ti were subjected to a long-term aging heat treatment at 400 ° C. to 500 ° C. for up to 200 hours.

[0029]

[Table 3]

It can be seen that the Ni 50 atomic percent alloy can form the tip more softly and can provide a large difference in rigidity between the base and the tip.

In the above embodiment, an alloy having a composition of 50 atomic percent Ni and the balance of Ti has been described.
Can be used in a similar manner. At this time, since the transformation temperature varies depending on the Ni concentration, the stress-
The strain characteristics also change with the Ni concentration.

[0032]

As described above, according to the present invention,
When used in catheters and the like, it has excellent torque transmission necessary to obtain hand operability, and excellent protruding properties, and has a base that has kink resistance that is difficult to bend and has softness that does not damage blood vessels, and It is possible to provide a medical tube having a flexible distal end portion which can easily enter a bent portion and can be easily deformed by a short heat treatment.

[Brief description of the drawings]

FIG. 1 is a view showing a medical tube according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a heat treatment method for the distal end portion of the medical tube according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of stress-strain characteristics of the medical tube according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Medical tube 2 Base 3 Tip 4 Tube 5 Refractory material 6 Furnace room 7 holes

Claims (3)

[Claims] 1. A medical tube comprising an elongated tube having a base and a tip, wherein the tube has a NiNi concentration of less than 50.3 atomic percent.
1. A medical tube comprising a shape memory alloy mainly composed of: 2. The medical tube according to claim 1, wherein the base has at least superelasticity at a living body temperature near 37 ° C. 3. The medical tube according to claim 1, wherein the distal end portion exhibits a shape memory effect at a living body temperature near 37 ° C.