JP2001009041A - Medical guide wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical guide wire which is partially curlable and is so formed as to prevent the easy deformation of a curled shape during the course of insertion. SOLUTION: The guide wire 10 is constituted by using a core wire 11 formed by working an alloy consisting of Ni and Ti as a basic composition to a wire form and subjecting this wire to a heat treatment, then cold working part of the entire length to provide the wire with an easily plastically deformable portion. The heat treatment is preferably a strain age treatment below 350 deg.C and the cold working is preferably forging. More particularly the foremost end 11a' of the core wire 11 is more flatly worked by casting, by which the curling of at the front end of the guide wire is made easy and the easy plastic deformation during the course of its is averted. The curling shape may be maintained until the guide wire is inserted to a desired point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical guidewire used for guiding a distal end of a catheter to a target site when the catheter is inserted into a tubular organ of a human body such as a blood vessel, a ureter, a bile duct, and a trachea. .

[0002]

2. Description of the Related Art In recent years, for examination and treatment of tubular organs of the human body such as blood vessels, ureters, bile ducts, and trachea, a catheter is inserted to administer a drug such as a contrast medium, or tissue is passed through a catheter by forceps or the like. Some of them are collected. When inserting a catheter, first, a relatively thin and flexible guide wire is inserted into the tubular organ, the tip of the guide wire reaches a target location, and then the catheter is inserted along the outer periphery of the guide wire. The guide wire is pulled out.

[0003] As the guide wire, there are used a core wire made of Ti-Ni alloy, stainless steel, or the like, the outer periphery of which is covered with a resin, or a wire in which a coil is attached to the outer periphery of the above-described core wire. The core wire for the guide wire is thin enough to be easily inserted into the target tubular organ, flexible at the distal end so as not to damage the inner wall of the tubular organ, and sufficiently pressed into the tubular organ. What has the rigidity of a main-body part etc. is desired.

Further, in order to guide the distal end of the guide wire at a branch portion of the tubular organ in a target direction, the distal end of the guide wire is previously bent at a predetermined angle into a “F” shape, and the guide wire is bent. By holding and rotating the base side by hand, the leading end is directed to a desired direction, and it is easy to select a course. However, since the shape of the bifurcation of the tubular organ differs depending on the treatment site and the patient, the surgeon bends the tip of the guidewire during surgery so that it can be easily inserted according to the treatment site and the patient. Often used.

As such a guide wire, for example, Japanese Patent Publication No. 4-8065 discloses the use of a core wire made of a Ti-Ni alloy having a predetermined composition and having different annealing temperatures between a tip portion and a substrate portion. . Also, Japanese Patent No. 264046
No. 1 discloses a guide wire having two or more different transformation temperatures on a single seamless shape memory alloy wire having the same composition. Further, JP-A-4-29.
No. 2175 is a guide wire in which a coil is attached to a distal end of a core wire made of stainless steel or the like, and the distal end portion of the core wire has a pair of opposed flat surfaces, and this flat surface is aligned with the longitudinal axis. There is disclosed one that extends at an angle with respect to a flat surface and a non-flat surface so that there is no transition portion having an acute cross section at a contact portion between the flat surface and the non-flat surface.

[0006]

However, in the guide wire disclosed in Japanese Patent Publication No. Hei 4-8065, the tip is
When the heat treatment is performed at 00 to 500 ° C., the tip can be made flexible by the superelastic property, but there is a problem that the tip cannot be bent and the tip cannot be bent.
When the heat treatment is performed at a temperature of 00 ° C. or more, although the tip portion is provided with plasticity and is easily bent, there is a problem that the bent shape of the tip portion changes during insertion.

In the guide wire disclosed in Japanese Patent No. 2,640,461, the tip portion and the substrate portion have different transformation temperatures, so that the tip portion can be made more flexible than the substrate portion. However, there is a problem that the tip portion cannot be bent because it is used in such a case.

Further, in the guide wire disclosed in Japanese Unexamined Patent Publication No. 4-292175, the use of a core wire made of, for example, stainless steel makes it easier to bend the distal end portion, and the rigidity of the substrate portion is higher than that of a superelastic material. Push ability, but the bending angle of the distal end and the shape of the substrate change during insertion, resulting in poor rotation transmission from the hand to the distal end. Was.

Accordingly, an object of the present invention is to provide a medical guide wire which can be partially bent at a tip portion, for example, and in which the bent shape is not easily deformed during insertion. It is in.

[0010]

Means for Solving the Problems In order to achieve the above object, a first aspect of the present invention is to form an alloy having a basic composition of Ni and Ti, process it into a linear shape, perform a heat treatment, and then reduce the total length of the alloy. It is intended to provide a medical guidewire having a core wire provided with a portion which is cold-worked to facilitate plastic deformation.

According to the first aspect of the invention, the alloy having the basic composition of Ni and Ti is linearly processed, heat-treated and subjected to the memory treatment or the strain aging treatment. Material core wire can be provided. In addition, since a transition is formed by cold working a part of the entire length of the core wire and the part is easily plastically deformed appropriately, it is possible to perform a habit bending according to the application location of the patient and the like, It is possible to provide a guide wire in which the bent shape is maintained to some extent even after the insertion to a target location.

According to a second aspect of the present invention, there is provided a medical guide wire according to the first aspect, wherein the core wire is subjected to the heat treatment at a temperature of less than 350 ° C. to give strain aging.

According to the second aspect of the present invention, although the shape restoring property is slightly reduced as compared with the memory processing performed by heat treatment at 400 ° C. or higher, the rigidity can be increased. And a medical guidewire excellent in pushability of the medical guidewire can be provided.

According to a third aspect of the present invention, there is provided the medical guide wire according to the first or second aspect, wherein the cold working is performed by forging, and the portion which is easily plastically deformed is flattened. It is.

According to the third aspect of the present invention, it is easy to bend in a direction perpendicular to the flat surface, and it is difficult to bend in a direction along the flat surface.
It is possible to provide a medical guidewire that is not easily deformed during insertion.

According to a fourth aspect of the present invention, there is provided a medical guide wire according to any one of the first to third aspects, wherein the portion which is easily plastically deformed is provided at a distal end portion of the core wire. is there.

According to the fourth aspect of the present invention, when selecting a course at the bifurcation of the tubular organ, the distal end can be bent at an angle corresponding to the application location of the patient.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the plastically deformable portion has a deformation angle of 30 mm after being wound around a 6 mm diameter cylinder for 30 seconds.
The present invention provides a medical guidewire adapted to be ° 80 °.

According to the fifth aspect of the present invention, the medical guide wire has a characteristic of being easily plastically deformed, so that it is possible to perform a curving bending and to be less likely to be deformed during insertion.

According to a sixth aspect of the present invention, there is provided the medical guide wire according to the third aspect, wherein the core wire is covered with a resin.

According to the sixth aspect, the portion flattened by forging can be easily arranged at the center of the resin film at the time of extrusion molding, and the contact area with the resin film increases,
The rotation transmission is improved.

[0022]

1 to 3 show one embodiment of a medical guidewire according to the present invention. FIG. 1 is a side sectional view of the medical guide wire, FIG. 2 is a side sectional view showing a state in which the distal end is bent, and FIG. 3 is an explanatory view showing a method of processing the distal end of the core wire.

The guide wire 10 is mainly composed of a core wire 11 and a resin film 12 covering the outer periphery of the core wire 11.

As the core wire 11, an alloy having a basic composition of Ni and Ti, specifically, a Ni-Ti alloy, Ni-Ti-
An X (X is Fe, Cu, V, Co, etc.) alloy is used.
This alloy is processed into a wire having a predetermined wire diameter by a known method such as hot forging, hot rolling, and cold working. afterwards,
By performing a heat treatment, a memory treatment or a strain aging treatment is performed. The memory treatment is performed at 400 ° C. or higher, preferably 400 to 6
The strain aging treatment can be performed by heat treatment at a temperature of less than 350 ° C., preferably 200 to 340 ° C. When the memory treatment is performed, super elasticity (JIS H70 issued by the Japan Standards Association)
01), which is excellent in flexibility, but tends to have poor pushability due to insufficient rigidity on the base side. On the other hand, when subjected to strain aging treatment, it becomes a material without a transformation point, the flexibility is slightly inferior to superelasticity, but it is better than stainless steel, and the base side rigidity is higher than superelasticity Push ability can be improved.

The distal end portion 11a of the core wire 11 is tapered by means of etching, machining or the like in order to impart flexibility. However, the shape may be stepped and gradually reduced in diameter.

The foremost portion 11a 'of the core wire 11 is cold worked by forging as shown in FIG. That is, the foremost portion 11a 'is first processed into a columnar shape as shown in FIG. 3A, and is pressed by a pair of dies 13 and 14 as shown in FIG. It is forged into a flat shape as shown in FIG. By this, the most advanced part 1
A transition is formed in 1a ', and plastic deformation is likely to occur. For this reason, as shown in FIG. 2, it is possible to bend the front end portion 11a 'to a desired angle. This habit angle θ
Is appropriately selected depending on the application site and the patient, but is usually selected in the range of 30 to 80 °. In addition, the most advanced part 11
a ′ may be bent at a predetermined angle, for example, θ = 55 °, and may be further bent and adjusted to a desired angle at the time of use.

In this case, the initial thickness t ₁ of the foremost portion 11a ′ and the thickness t ₂ after forging are t ₂ / t ₁ = 0.9 to 0.3.
It is preferable that In addition, as the cold working, in addition to the forging as described above, a method such as tension and torsion can be adopted.

The entire length of the core wire 11 is 1000 to 300
About 0 mm is preferable. Also, the main body 11b of the core wire 11
Is appropriately set in the range of about 0.2 to 1.0 mm according to the purpose. Also, the length A of the tapered tip portion 11a and the tip portion 11a 'of the core wire 11 is
It is preferably about 150 to 700 mm. Furthermore, the most advanced part 1
The length B of 1a 'is preferably about 5 to 30 mm.

The outer periphery of the core wire 11 is covered with a resin film 12. As the resin film 12, for example, polyurethane, polyether block amide, polyethylene, polyvinyl chloride, polyester, polypropylene, polyamide, polystyrene, fluororesin, silicon resin and the like are preferably used. Further, the resin film 12 may contain an X-ray opaque material. As the X-ray opaque material, for example, powders of bismuth, barium sulfate, tungsten and the like are preferably used.

As a method of coating the resin film 12, a method of extruding the resin film 12 around the core wire 11 using an extrusion molding apparatus is preferably adopted. In this case, the conventional core wire 1
In FIG. 1, since the tip portion 11a is formed in a tapered shape, when that portion passes through the extrusion die, a gap is opened between the outer periphery of the core wire 11 and the inner periphery of the die, and the core wire 11 is
However, there has been a problem that the eccentricity tends to be deviated with respect to 2, and thereby the rotation transmission property is reduced. On the other hand, in this embodiment, since the foremost portion 11a 'is flattened and widened, the wide side portions abut against the inner periphery of the die to prevent deviation, and the tip portion 11a of the core wire 11 is moved. It can be positioned at the center of the resin film 12 and has a flattened tip portion 11
Since the contact area between a ′ and the resin film 12 is increased to be more integrated, rotation transmission can be improved.

Further, it is preferable that the outer periphery of the resin film 12 is covered with a hydrophilic resin film (not shown). As the hydrophilic resin film, -OH, -CONH _2, -COOH,
A resin having a hydrophilic group such as —NH ₂ , —COO ⁻ , and —SO ³⁻ , and preferably having a functional group that can be bonded to the surface of the resin film 12 is preferably used. For example, as the resin film 12, a resin having an isocyanate group remaining or a resin having a reactivity with an isocyanate group is used. When a resin having a reactivity with an isocyanate group is used, a compound having an isocyanate group is further reacted. After that, a method of bonding a hydrophilic resin such as polyvinylpyrrolidone or polyethylene glycol via these isocyanate groups is preferably used. A method for forming such a hydrophilic resin film is described in, for example,
184666, JP-A-7-80078, JP-A-7
No. 124263.

According to this guide wire 10, Ni and T
i, which is made of an alloy having a basic composition, is processed into a linear shape, and then subjected to a heat treatment.
When a ′ is cold-worked by forging, a transition is formed in that portion, and plastic deformation is likely to occur.
Therefore, when used by a physician, the distal end of the guidewire 10 should be at an angle that facilitates the insertion of the distal end of the guidewire 10 in accordance with the application location where the guidewire 10 is to be inserted or the shape of the tubular organ that differs for each patient. Can be bent.

Further, the flattened front end portion 11a '
As shown in FIG. 2, it is easy to bend in a direction perpendicular to the flat surface, but hard to bend in a direction along the flat surface. For this reason, during insertion of a tubular organ such as a blood vessel,
It is possible to prevent a 'from further bending laterally with respect to the initial bending direction, and to easily maintain the bending shape. Further, as described above, the leading edge portion 11
Since a ′ is flattened, the rotation operation on the hand side is easily transmitted to the foremost end portion 11a ′, and selection of the course at the bifurcation of the tubular organ becomes easy.

FIG. 4 shows another example of the core wire 11 applied to the guide wire according to the present invention. This core wire 1
In 1, the flat part 11c is formed by forging only the base side of the foremost part 11a '. And in this flat part 11c, it is easy to carry out plastic deformation.
Thus, cold working such as forging may be performed in the middle of the core wire 11. More specifically, for example, a portion that is easily plastically deformed by cold working may be provided at the rear end of the core wire 11. According to this, the rear end of the guide wire is bent, so that the bent portion is gripped. The guide wire can be easily pushed and rotated.

The guide wire according to the present invention is not limited to the type in which the core wire 11 is covered with the resin film 12, but may be applied to the type in which a coil is mounted on the outer periphery of the core wire 11. In this case, the tip 11a of the core wire 11
Is processed into a tapered shape or a stepped shape, and the foremost portion 11a 'is cold-worked by means of forging or the like as described above.
1a, a coil is mounted on the outer periphery, and the base side of the coil is brazed or adhered to the base side of the tip 11a.
Preferably, a round head is formed at the tip of a ′, and the tip of the coil is brazed or adhered to the head at the foremost part 11a ′. As the coil, an X-ray opaque material made of platinum, gold, tungsten, an alloy thereof or the like is preferably adopted.

[0036]

EXAMPLES Test Example 1 A wire having a wire diameter of 0.5 mm was formed by a conventional method using a Ti-Ni alloy. After heat treating the wire at various temperatures of 300 to 600 ° C. for 30 seconds, the bending stiffness value was measured by the method shown in FIG. That is, after the wire 1 to be measured is laid over the two fulcrums 15 arranged at an interval of 30 cm, the center of the fulcrum 15 of the wire 1 is pushed into the pushing member 17.
Then, the load (kg) in a state of being pushed in by 1 mm from above was measured to obtain a bending rigidity value.

Further, the longitudinal stiffness (Young's modulus) was obtained from the bending stiffness value by the following equation 1, and the relationship between the heat treatment temperature and the longitudinal stiffness was graphed in FIG.

[0038]

(Equation 1)

As shown in FIG. 6, the heat treatment at 300 ° C. (strain aging treatment) tends to have higher rigidity than the case without heat treatment. Further, it can be seen that the stiffness of the heat treatment temperature of 400 ° C. or higher (shape memory treatment) is significantly lower than that of the case without heat treatment or the heat treatment at 300 ° C. or 350 ° C. Therefore, it is understood that by performing the strain aging treatment at less than 350 ° C., the rigidity of the base side of the guide wire can be maintained and the pushability can be improved.

Test Example 2 Using a Ti—Ni alloy, a wire diameter of 0.15 mm was obtained by a conventional method.
Was formed. This wire was heat-treated at 300 ° C. for 30 seconds to perform a strain aging treatment. This wire was forged to produce various wires having a thickness of 0.12 mm to 0.08 mm. The bending stiffness value was measured for each wire made of the unforged one and the forged one in the same manner as in Test Example 1.

FIG. 7 shows the results. In FIG. 7, a polygonal line a shows the above measurement result, and a polygonal line b is a result of a theoretical value calculated based on the following mathematical formula 2. As described above, the polygonal line a indicating the actual measurement result is replaced by the polygonal line b indicating the theoretical value.
In comparison, the rigidity tends to decrease as the plate thickness decreases.

[0042]

(Equation 2)

As described above, in the case where the wire rod subjected to the strain aging treatment is forged, the rigidity tends to be lower than the theoretical value as the thickness is reduced. In other words, the transitions in the strain-aged state are arranged regularly, but when the material in this state is subjected to cold working, the transitions are generated randomly and the regularity of the transitions is lost, and the rigidity of the material itself is also reduced. It will fall. This means that the foremost part of the guidewire can be made more flexible by forging.

Test Example 3 Using a Ti—Ni alloy, a wire having a wire diameter of 0.5 mm was formed by an ordinary method. This wire was heat-treated at 300 ° C. for 30 seconds and subjected to a strain aging treatment (sample).
One that has been heat-treated for 0 seconds and subjected to shape memory processing (sample),
Heat treated at 300 ° C. for 30 seconds and subjected to strain aging treatment, further forged and rolled to a thickness of 0.25 mm (sample), and a wire diameter of 0.5 made of stainless steel (SUS631).
mm wires (samples) were prepared.

The amount of permanent deformation of each of these wires was measured by the method shown in FIG. That is, as shown in FIG.
m, 18mm, wound around each cylinder of 22mm for 30 seconds,
Thereafter, the wire 1 was left to measure the deformation angle (°) as shown in FIG.

FIG. 9 shows the result. As shown in FIG. 9, it can be seen that the sample subjected to the shape memory processing hardly permanently deforms and cannot be habitually bent. Further, it can be seen that the sample subjected to the strain aging treatment is more easily deformed than the above-mentioned sample, but is still hard to bend. The sample, which is a forged product, is much easier to deform than the sample, and it can be seen that the sample can be habitually bent.
It can be seen that the sample made of stainless steel is significantly deformed and can be easily bent.

However, even if the distal end of the sample made of stainless steel can be bent, the plastic changes again during the insertion of the tubular organ. There is a problem that the shape is not maintained and the operability of the course selection is impaired.

Therefore, it is preferable that the material of the distal end portion of the guide wire is a material that can be bent flexibly and does not easily plastically deform during insertion, and a sample that is a forged product is most suitable. I knew it was there.

When various experiments were repeated, the amount of permanent deformation of the distal end of the guide wire was 6 mm in diameter.
Deformation angle after winding for 30 seconds around a cylinder of 30 to 80 °
Was found to be preferable.

[0050]

As described above, according to the medical guidewire of the present invention, the core wire obtained by processing an alloy having a basic composition of Ni and Ti into a linear shape and performing a heat treatment is used. It is hard to be permanently deformed, and a part of the entire length of the core wire is cold-worked to form a transition, and that part is easily plastically deformed appropriately. It is possible to provide a guide wire that is capable of maintaining its bent shape to some extent even after inserting it to a target location.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a medical guidewire according to the present invention.

FIG. 2 is a side cross-sectional view showing a state where the distal end portion of the medical guide wire is bent in a curved manner.

FIG. 3 is an explanatory view showing a method of processing a tip portion of a core wire.

FIG. 4 is a partial sectional view showing another embodiment of the medical guidewire according to the present invention.

FIG. 5 is an explanatory view showing a method for measuring a bending rigidity value.

FIG. 6 is a table showing a relationship between a heat treatment temperature and a bending rigidity value of a Ti—Ni alloy wire.

FIG. 7 is a table showing a relationship between a plate thickness and a bending stiffness value when a strain-aged Ti—Ni alloy wire is further forged.

FIG. 8 is an explanatory diagram showing a method of measuring a deformation angle.

FIG. 9 is a table showing the results of measuring the deformation angles of various wires.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Medical guide wire 11 Core wire 11a Tip part 11a 'Foremost part 11b Body part 11c Flat part 12 Resin film

Claims (6)

[Claims] 1. A core wire made of an alloy having a basic composition of Ni and Ti, processed into a linear shape, subjected to a heat treatment, and then provided with a portion provided with a portion that is easily cold-worked to be plastically deformed. A medical guidewire, comprising: 2. The medical guidewire according to claim 1, wherein the core wire is subjected to the heat treatment at a temperature of less than 350 ° C. to give strain aging. 3. The cold working is performed by forging, and the part which is easily plastically deformed is flattened.
A medical guidewire as described. 4. The medical guidewire according to claim 1, wherein the portion that is easily plastically deformed is provided at a tip of the core wire. 5. The portion which is easily plastically deformed has a deformation angle of 30 to 30 mm after being wound around a cylinder having a diameter of 6 mm for 30 seconds.
The medical guidewire according to any one of claims 1 to 4, wherein the angle is set to 80 °. 6. The medical guidewire according to claim 3, wherein the core wire is covered with a resin.