JP2002011102A - Medical guide wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a guide wire, a catheter or a stent combining moderate rigidity and flexibility. SOLUTION: β titanium alloy fine wire is used as given by L/√A=5 to 1,000 when the average crystal grain area A of βphase in the transverse structure is 1-80 μm2 and the average crystal grain length L of β phase in the longitudinal structure is 10-10,000 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medical device used through a catheter inserted into a blood vessel or a digestive tract, such as a medical guidewire or a catheter, and a stent.

[0002]

2. Description of the Related Art In recent years, diagnosis and treatment by inserting a catheter into a blood vessel, a digestive tract, and the like are increasing. Medical devices used through a catheter include a guidewire or catheter operated through the catheter, or a stent placed at a target site through the catheter.

An example of a medical guidewire will be described below.

[0004] A medical guidewire is used as a guide for introducing a catheter when performing minimally invasive treatment or the like. Generally, a medical guidewire is inserted into a blood vessel in a state of protruding from a distal end portion of a catheter.
Therefore, the medical guide wire needs to be able to pass through a meandering blood vessel or a stenosis (passability) and selectively enter a branch point in a desired direction (selectivity, pushability). In addition, the distal end is given a slight bending habit (reshape) and inserted into the catheter, and a slight torsional force is applied from the proximal end side of the medical guide wire, and the distal end is rotated to bend the branch. select. Therefore, the medical guidewire is required to have a one-to-one correspondence (torque transmission) to the twisting operation of the base end portion.

At present, as a medical guide wire, a stainless steel linear body is used as an inner core, and a stainless steel coil is wound around its tip, and a superelastic alloy is used as an inner core and a synthetic resin is coated. Are roughly divided into

However, if a material such as a stainless steel guide wire which is strongly squeezable and easily deforms plastically is used for the inner core, it may damage the blood vessel wall in a meandering lumen or stenosis. There is a concern that the meandering blood vessels may be elongated. Another problem is that the guide wire that is plastically deformed at the time of removal may damage the blood vessel wall. In addition, a guide wire made of stainless steel is extremely poor in transmission of torsional force in a meandering blood vessel, and poor selectivity and operability at a branch portion have been regarded as a problem. On the other hand, the guide wire made of a superelastic alloy has a high torque transmitting property in a meandering blood vessel, but has a problem that its tip cannot be reshaped and its bending resistance in a curved state is weak. Therefore, there has been a demand for a re-shaping guidewire which has a high elasticity and a moderate waist strength, which solves the above-mentioned problems and allows the operator to easily and safely perform the procedure.

As a relatively new inner core material, Japanese Unexamined Patent Publication
No. 63151 proposes a medical guidewire in which an inner core made of a Co-Ni-Cr-Fe alloy is coated with a synthetic resin. However, none of the listed alloys has an elastic modulus of 20.
000kg / mm ² or more and quite high, a material hardly become rigid plastically deformable than stainless steel, when going inserted into a blood vessel that meanders or damage the vessel wall, stretching the vessels are tortuous There is a possibility of doing it.

Further, Japanese Patent Application Laid-Open Nos. 11-276597 and 2000-
No. 297 discloses a Zn-based amorphous alloy,
In Japanese Patent Application Publication No. 0-297, Cu-based shape memory alloys have been proposed, but all of them are materials at the research stage, and include various problems with practical materials.

Further, Japanese Patent Application Laid-Open No. 06-233811 proposes an implant made of a low-modulus titanium alloy.
Expensive Nb and Zr are essential elements, outer diameter 0.5mm
Insufficient strength in straightening while applying tension as the inner core of the guide wire to be drawn below, or in tapering the distal end side. It can be said that the material is not suitable for performing the resin coating process. In addition, in the molding of a core material by hot working, there are problems that crystal grains are coarsened and strength is difficult to obtain, and surface oxidation occurs during molding and a smooth surface is hardly obtained and it is difficult to obtain roundness. ,
In order to obtain the mechanical properties and shape required for the core material of the guide wire, it is necessary to carry out several further processings.

Next, in the catheter, it is possible to insert a wire into the lumen of the catheter so as to have rigidity or to embed the wire in the catheter wall to have rigidity so that the catheter can pass through a meandering blood vessel or a stenosis. (Pushability, passability) is required. Conventionally, such a catheter wire also uses a stainless steel wire, and has the same problem as a medical guidewire.

In the case of an indwelling device such as a stent to be indwelled after dilating a stenotic portion of a blood vessel, a material such as stainless steel or a nickel titanium alloy is conventionally used. As stents using stainless steel, there are a stent in which a stainless steel wire is formed in a zigzag shape, and a stent in which openings of various patterns are provided in a stainless steel pipe. However, it has not yet satisfied both the flexibility for blood vessel permeability and the appropriate rigidity after being placed for suppressing restenosis.

[0012]

Accordingly, an object of the present invention is to provide:
It is an object of the present invention to provide a medical guidewire and a catheter having appropriate flexibility while having appropriate rigidity. Another object of the present invention is to provide a stent having both flexibility for blood vessel permeability and appropriate rigidity after being placed for suppressing restenosis.

In order to achieve the above object, the present invention has the following arrangement.

That is, the medical guidewire of the present invention has an average grain area A of β phase of 1 to 8 in the cross-sectional structure.
0 μm ² , the average crystal grain length L of the β phase in the longitudinal sectional structure is 10 to 1000 μm, and L / √A = 5 to 1000
Use titanium alloy fine wire.

In the catheter of the present invention, the average grain area A of the β phase in the cross-sectional structure is 1 to 80 μm ² , the average grain length L of the β phase in the vertical cross section is 10 to 1000 μm, and L Use a β-titanium alloy fine wire with / √A = 5 to 1000.

In the stent of the present invention, the average grain area A of the β phase in the cross-sectional structure is 1 to 80 μm ² , the average grain length L of the β phase in the vertical cross section is 10 to 1000 μm, and L Use a β-titanium alloy fine wire with / √A = 5 to 1000.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the medical guidewire of the present invention, and FIG. 2 is a sectional view showing another embodiment of the medical guidewire of the present invention.

FIG. 3 is a cross-sectional end view showing an embodiment of the catheter of the present invention, FIG. 4 is a cross-sectional end view showing another embodiment of the catheter of the present invention, and FIG. It is a front-end sectional view showing another embodiment.

FIG. 6 is a perspective view showing an embodiment of the stent of the present invention, FIG. 7 is a partially enlarged view showing another embodiment of the stent of the present invention, and FIG. 8 is another embodiment of the stent of the present invention. It is the perspective view which showed the form.

FIG. 9 is an enlarged perspective view conceptually showing a part of the β-titanium alloy fine wire of the present invention in the longitudinal direction.

The medical guidewire 1 shown in FIG. 1 comprises a core material 10 and a covering portion 12 covering almost the entire surface thereof.
The medical guidewire 1 is 150 cm long,
Various lengths of 10 cm to 400 cm are applicable depending on the type. Outer diameter is 0.89mm (0.035 inch)
However, it can be set to 0.1 to 2.0 mm depending on the type. The outer diameter is substantially the same from the distal end to the proximal end, but the distal end may be narrowed.

The core material 10 is formed of a β titanium alloy fine wire described later. The core material 10 has a substantially uniform diameter except for the tip portion, and the tip portion is tapered. The covering portion 12 is formed from a plastic covering layer. Polyethylene as plastic coating layer,
Core material 10 coated with polyvinyl chloride, polyester, polypropylene, polyamide, polystyrene, polyurethane, fluororesin or each elastomer, etc.
Closely adhered to. The coating layer may be a tube made of the above plastic material. Further, it is preferable to apply a lubricating coat to the surface of the covering portion 12. In this case, the lubricating coat can be made hydrophilic to increase the water content, reduce the frictional resistance with blood vessels and the like, and improve the slidability. In addition, slidability can be enhanced by providing a smooth surface with low blood adhesion by applying a silicon coating. Various other processes are possible if the slidability is enhanced.

The β-titanium alloy fine wire used for the core material 10 has a tensile strength greater than that of the superelastic Ni-Ti alloy, and its Young's modulus is about twice that of the Ni-Ti alloy and about half that of stainless steel. It is sticky and has excellent flexibility and resilience, and is excellent in torque transmission.

The β-titanium alloy fine wire used for the core material 10 has a wire diameter of 0.49 mm.
mm. Then, as shown in FIG.
The titanium alloy fine wire has a β-phase crystal grain G in the cross-sectional structure.
Has an average crystal grain area A of 1 to 80 μm ² ,
Average grain length L of β phase in longitudinal section structure is 10 to 1000
μm, and L / ΔA = 5 to 1000.

In the present invention, the reasons for limiting each factor for specifying the shape and size are as follows.

It is extremely difficult to obtain a β-phase having an average grain area A of less than 1 μm ² in the cross-sectional structure by wire drawing, which is not a reality. The average crystal grain area A
If it exceeds 80 μm ² , the strength is undesirably reduced.

If the average crystal grain length L of the β phase in the longitudinal sectional structure is less than 10 μm, there is a drawback that sufficient strength cannot be obtained, and it is difficult to process the average crystal grain length L exceeding 1000 μm.

In terms of the relationship between the average crystal grain length L and the average crystal grain area A, if L / ＜ A <5, sufficient strength and flexibility cannot be obtained, and L / √A> 1000. Is difficult to process.

The diameter of the β titanium alloy fine wire is 0.01 to 2.
It is preferably 0 mm. If the wire diameter is less than 0.01 mm, substantial strength cannot be obtained. The wire diameter is 2.0
If it exceeds mm, flexibility is impaired even at a low Young's modulus.

As described above, the average grain area A of the β phase in the cross-sectional structure, the average grain length L of the β phase in the vertical structure, and L / ΔA are limited to the specific ranges of the present invention. Accordingly, a flexible and high-strength β-titanium alloy thin medical guide wire having appropriate rigidity can be provided.

As an example of producing the β-titanium alloy fine wire of the present invention, a solution treatment is carried out at a temperature above the β transformation point before cold drawing, and a cold workability is obtained by eliminating the α phase. By making it better, the processed texture of β phase in cold drawing can be more uniformly formed.

The core material 10 of the β titanium alloy fine wire used for the guide wire of the present invention has a tensile strength of 110 kgf / mm ² or more and 200 kgf.
/ mm ² or less, and more preferably 150 kgf / mm ² or more and 180 kgf / mm ² or less. Difficult because insufficient as strength to perform straight out while tensile strength is tensioned or drawn by cold working is less than 110 kgf / mm ² the core material to the desired outer diameter, and the core material having poor straightness Prone. 20
If it exceeds 0 kgf / mm ² , the value of the Young's modulus increases with an increase in tensile strength, and flexibility may be lost.

The β titanium alloy fine wire of the core member 10 is Young's modulus of 5,000 kgf / mm ² or more 10,000kgf / mm ² or less, further,
It is preferably 6,000 kgf / mm ² or more and 8,000 kgf / mm ² or less. When the Young's modulus is less than 5,000 kgf / mm ^2, since the weak waist as a guidewire hardly transmitted to the distal end pushing in hand, if it exceeds 10,000kgf / mm ^2, the torsion in the blood vessels meandering strong waist force Is poorly communicable.

The β-titanium alloy fine wire of the core material 10 has a roundness of 15 μm or less, preferably 5 μm.
m, more preferably 1 μm or less. If the roundness of the cross section exceeds 15 μm, the delicate torsional force of the hand cannot be accurately transmitted to the distal end in a curved blood vessel, and the selectivity at the bifurcation of the blood vessel is poor.

The β-titanium alloy fine wire of the core material 10 has a rigidity of
1,500kgf / mm ² or more 6,000kgf / mm ² or less, preferably, 3,000kgf / mm ² or more 5,000 kgf / mm ² or less. Rigidity is hardly transmitted to the distal torsion torque instantly at hand is less than 1,500kgf / mm ^2, that the torsion torque is reproduced faithfully tip in vascular and a curved exceeds 6,000kgf / mm ² It will be difficult.

Further, the β-titanium alloy fine wire of the core material 10 is 0.1 μm.
2% proof stress is 50 kgf / mm ² or more and 150 kgf / mm ² or less,
Further it is preferably 100 kgf / mm ² or more 130 kgf / mm ² or less. If the 0.2% proof stress is less than 50 kgf / mm ² , a bending habit tends to be formed, and if it exceeds 150 kgf / mm ² , it is difficult for the operator to reshape, and the distal end cannot have the selectivity of the branch portion.

[0038] In addition, beta titanium alloy fine wire bending elastic modulus of the core member 10 is at 6,000kgf / mm ² or more 18,000kgf / mm ² or less, it is further 10,000kgf / mm ² or more 15,000kgf / mm ² or less preferable. Flexural modulus is less likely to hear is pushed in during insertion weak stiffness is less than 6,000kgf / mm ^2, 18,000kgf / mm
Exceeding ² can force the meandering blood vessels straighten and cause damage.

The core 10 preferably has all the characteristics, but may have at least one characteristic.

It is preferable that the core material has two or more characteristics. For example, 110 kgf / mm ² or more 20
0 kgf / mm ² or less in tensile strength or 5,000 kgf / mm ² or more 10,000kg
A titanium alloy having a Young's modulus of not more than f / mm ² and a predetermined roundness, a titanium alloy having a tensile strength having the above numerical range or a rigidity having the Young's modulus and the above numerical range, the predetermined roundness of the cross section and the above numerical range It may be a titanium alloy having a rigidity having the following.

The titanium alloy of the core 10 is made of molybdenum (Mo), vanadium (V), tungsten (W), niobium (Nb), tantalum (Ta), iron (Fe), chromium (Cr), in addition to titanium. ), Nickel (Ni), cobalt (Co), aluminum (Al), zinc (Zn), tin (Sn) and the like are added as appropriate to form a titanium alloy.

Next, the medical guide wire 2 shown in FIG.
Consists of a core material 20 and a covering portion 22 covering the surface of the tip. The medical guidewire 2 has a length of 180 cm, but various lengths of 10 cm to 400 cm are applicable depending on the type. The outer diameter is 0.36mm (0.01
4 inches), but 0.2 to 2.0 mm depending on the type
Can be set to

The core material 20 is formed of a β-titanium alloy fine wire and has a wire diameter of 0.36 mm, but can be set to 0.01 to 2.0 mm depending on the type. β titanium alloy fine wire,
As described above, the average crystal grain area A of the β phase in the cross sectional structure is 1 to 80 μm ² , the average crystal grain length L of the β phase in the vertical cross sectional structure is 10 to 1000 μm, and L / ΔA = 5 ~Ten
00.

The covering portion 22 is formed of a coil, but may be formed of a plastic covering layer. The coiled portion 22 is made of stainless steel and has a length of 1
cm to 50 cm. Coated part 2 by coil
It is preferable that 2 has a tip portion formed of a material having higher X-ray contrast than other portions. The material having higher X-ray contrast than other parts is, for example, gold, platinum, iridium, or an alloy thereof. As the plastic coating layer, the materials described above for the guide wire 1 can be used. The coating layer may be a tube made of the above plastic material. Further, it is preferable to apply a lubricity coat to the surface of the covering portion 22. In this case, the lubricating coat can be made hydrophilic to increase the water content, reduce the frictional resistance with blood vessels and the like, and improve the slidability. In addition, slidability can be enhanced by providing a smooth surface with low blood adhesion by applying a silicon coating. Various other processes are possible if the slidability is enhanced.

The β-titanium alloy fine wire used for the core material 20 has a tensile strength greater than that of the superelastic Ni-Ti alloy, and its Young's modulus is about twice that of the Ni-Ti alloy and about half that of stainless steel. It is sticky and has excellent flexibility and resilience, and is excellent in torque transmission.

As shown in FIG. 2, the same material can be used for the core material 20 from the distal end to the proximal end. In that case,
The outer diameter is changed according to the characteristics required for each part. For example, the part other than the tip is relatively rigid and pushes in at hand. To transmit torque to the tip, the outer diameter is made larger than the tip, and the outer diameter is reduced through two or three or more tapered sections. To show a very flexible tip. It is also possible to use a wire made of a material different from that of the titanium alloy in combination according to the characteristics required for each part. For example, in the case of a medical guidewire in which the core material of the tip portion is made of a Ni-Ti alloy and the core material of the body portion is made of a titanium alloy, the pushability of the body portion and the torque transmission are excellent,
It can have both blood vessel followability and blood vessel passage property due to the extremely excellent restoring property of the Ni-Ti alloy. In addition, in the case of a medical guide wire in which the core material of the distal end portion is made of a titanium alloy and the core material of the main body portion is a stainless steel wire, while having the pushability of the stainless steel wire in the main body portion, it is difficult to kink, The tip has both the tenacity that is not easily plastically deformed and the high torque transmission.

The β titanium alloy fine wire used in the core material 20, the tensile strength is at 110 kgf / mm ² or more 200 kgf / mm ² or less and preferably more 150 kgf / mm ² or more 180 kgf / mm ² or less. Difficult because insufficient as strength to perform straight out while tensile strength is tensioned or drawn by cold working is less than 110 kgf / mm ² the core material to the desired outer diameter, and the core material having poor straightness Prone. If it exceeds 200 kgf / mm ² , the value of the Young's modulus increases with an increase in the tensile strength, and the flexibility may be lost.

The β titanium alloy fine wire of the core material 20 is Young's modulus of 5,000 kgf / mm ² or more 10,000kgf / mm ² or less, further 6,0
It is preferably from 00 kgf / mm ^{2 to} 8,000 kgf / mm ² . If the Young's modulus is less than 5,000 kgf / mm ² , the guide wire has a weak waist, so it is difficult for the push in hand to be transmitted to the tip like a NiTi alloy, and if it exceeds 10,000 kgf / mm ² , the waist is strong and meandering The transmission of the torsional force in the blood vessel becomes poor.

The β-titanium alloy fine wire of the core material 20 has a circularity of 15 μm or less in cross section, preferably 5 μm or less.
μm or less, more preferably 1 μm or less. When the roundness of the cross section exceeds 15 μm, the torque transmission in a curved blood vessel is inferior.

The β-titanium alloy fine wire of the core material 20 has a rigidity of
1,500kgf / mm ² or more 6,000kgf / mm ² or less, preferably, 3,000kgf / mm ² or more 5,000 kgf / mm ² or less. Rigidity is hardly transmitted to the distal torsion torque instantly at hand is less than 1,500kgf / mm ^2, that the torsion torque is reproduced faithfully tip in vascular and a curved exceeds 6,000kgf / mm ² It will be difficult.

Also, the β-titanium alloy fine wire of the core material 20 is 0.1 mm.
2% proof stress is 50 kgf / mm ² or more and 150 kgf / mm ² or less,
Further it is preferably 100 kgf / mm ² or more 130 kgf / mm ² or less. If the 0.2% proof stress is less than 50 kgf / mm ² , bending habit is likely to occur, and if it exceeds 150 kgf / mm ² , it is difficult for the surgeon to reshape and the distal end cannot have the selectivity of the branch portion.

[0052] In addition, beta titanium alloy fine wire bending elastic modulus of the core material 20 is at 6,000kgf / mm ² or more 18,000kgf / mm ² or less, it is further 10,000kgf / mm ² or more 15,000kgf / mm ² or less preferable. Flexural modulus is less likely to hear is pushed in during insertion weak stiffness is less than 6,000kgf / mm ^2, 18,000kgf / mm
Exceeding ² can force the meandering blood vessels straighten and cause damage.

The core 20 preferably has all the characteristics, but may have at least one characteristic.

It is preferable that the core material has two or more of each characteristic. For example, 110 kgf / mm ² or more 20
0 kgf / mm ² or less in tensile strength or 5,000 kgf / mm ² or more 10,000kg
A titanium alloy having a Young's modulus of not more than f / mm ² and a predetermined roundness, a titanium alloy having a tensile strength having the above numerical range or a rigidity having the Young's modulus and the above numerical range, the predetermined roundness of the cross section and the above numerical range It may be a titanium alloy having a rigidity having the following.

The titanium alloy of the core 20 is made of Mo, V, W, Nb, Ta, Fe, Cr, Ni, C
O, Al, Zr, Sn, etc. are added as appropriate to form a titanium alloy.

The titanium alloy of the core material 20 can be manufactured by the method described for the core material 10.

According to the present invention, the core material of the guide wire is
When formed of titanium alloy thin wire, it is difficult to kink, it is possible to have both toughness that is hard to plastically deform and high torque transmission, insertion of guide wire into blood vessels etc., catheter to the outer surface of guide wire Etc. can be reliably and smoothly performed. That is, the distal end portion can be a highly operable guide wire that can respond to the torsion force of the hand portion almost certainly while maintaining high strength and high elasticity. In addition, the tip portion can be shaped by reshaping as required, and the core material has an appropriate waist strength, so that it has good pushability in a stenosis portion and high selectivity in a branch portion.

Next, the catheter 3 shown in FIG. 3 is provided with a balloon 31 at its distal end.
Are connected to the inner tube 32 and the proximal end to the outer tube 34, respectively. The inside of the inner tube 32 is configured as a lumen 33 into which a guide wire is inserted. The space between the inner tube 32 and the outer tube 34 serves as a lumen 35 into which a liquid for expanding the balloon 31 flows.

The core member 30 is provided on the lumen 35, and extends from the proximal end (not shown) of the catheter to the balloon 31.
Near the base end of The distal end of the core member 30 is tapered so that the flexibility of the catheter 3 gradually changes. The base end of the core material 30 is fixed to the base end of the catheter, but may be movable so that the hardness of the catheter 3 can be freely changed. In addition, core material 3
0 may be embedded in the inner tube 32 and / or the outer tube 34.

The β titanium alloy fine wire used for the core material 30 has an average grain area A of β phase of 1 in the cross-sectional structure.
8080 μm ² , the average crystal grain length L of the β phase in the longitudinal section structure is 10-1000 μm, and L / ΔA = 5-1000.

In the present invention, the reasons for limiting the factors for specifying the shape and size are as follows.

It is extremely difficult and unrealistic to obtain a β-phase having an average grain area A of less than 1 μm 2 in the cross-sectional structure by wire drawing. The average crystal grain area A
If it exceeds 80 μm 2, the strength is undesirably reduced.

If the average crystal grain length L of the β phase in the longitudinal sectional structure is less than 10 μm, there is a disadvantage that sufficient strength cannot be obtained, and it is difficult to process the average crystal grain length L exceeding 1000 μm.

In terms of the relationship between the average grain length L and the average grain area A, if L / ＬA <5, sufficient strength and flexibility cannot be obtained, and L / √A> 1000. Is difficult to process.

The diameter of the β-titanium alloy fine wire is 0.01 to 2.
It is preferably 0 mm. If the wire diameter is less than 0.01 mm, substantial strength cannot be obtained. The wire diameter is 2.0
If it exceeds mm, flexibility is impaired even at a low Young's modulus.

In the present invention, by limiting to the above range, a flexible and high-strength β-titanium alloy fine wire having appropriate rigidity can be obtained, and a catheter provided with a core material 30 using the fine wire. No. 3 has a waist, is easy to push in, and has a flexibility to be easily inserted into a meandering blood vessel.

The method of using the catheter 3 is as follows. In the catheter 3 in a state where the balloon 31 is collapsed and folded, a guide wire is inserted into the lumen 33 of the inner tube 32 from the base end thereof, protrudes from the distal end side of the balloon 31, and extends to the target blood vessel having a stenosis. Is inserted and placed first, and then the catheter 3 is inserted along the guide wire to the target blood vessel. Generally, since the inner tube 32 and the outer tube 34 of the catheter 3 are made of a soft plastic material, it is difficult for the pushing force to be transmitted to the distal end portion, but the catheter 3 of the present invention has a moderate rigidity. However, since the core member 30 is a flexible β-titanium alloy thin wire, the pushing force is easily transmitted, and the insertion can follow the meandering blood vessel. After being inserted into the target blood vessel, a liquid (contrast agent) is injected into the lumen 35 from the proximal end of the catheter 3 to expand the stenosis, and the folded balloon 3 is expanded to push the stenosis. spread.

The catheter 4 shown in FIG. 4, which is another embodiment of the present invention, has a balloon 41 provided at the distal end thereof. 44 are respectively connected. The inside of the inner tube 42 becomes a lumen 43 into which a guide wire can be inserted. The lumen 43 communicates with an opening 47 provided at a predetermined distance from the distal end. The space between the inner pipe 42 and the outer pipe 44 is
It becomes a lumen 45 into which a liquid for expanding the balloon 41 flows.

The core member 40 is provided in the lumen 45, and its position extends from the proximal end (not shown) of the catheter to the vicinity of the proximal end of the balloon 41 via the opening 47. The distal end portion of the core member 40 is tapered so that the flexibility of the catheter 4 gradually changes. The base end of the core member 40 is fixed to the base end of the catheter, but may be movable so that the hardness of the catheter 4 can be freely changed. The core member 40 includes the inner tube 42 and / or the outer tube 4.
4 may be embedded.

The β titanium alloy fine wire used for the core material 40 has an average crystal grain area A of β phase of 1 in the cross-sectional structure.
8080 μm ² , the average crystal grain length L of the β phase in the longitudinal section structure is 10-1000 μm, and L / ΔA = 5-1000.

In the present invention, by limiting the content to the above range, a flexible and high-strength β-titanium alloy fine wire having appropriate rigidity can be obtained, and a catheter provided with a core material 40 using the fine wire. No. 4 has a waist, is easy to push in, and has a flexibility that can be inserted into a meandering blood vessel.

The method of using the catheter 4 is basically the same as that of the catheter 3 except that the insertion state of the guide wire is different. The catheter 4 in a state where the balloon 41 is collapsed and folded is inserted with the guide wire in a state where the guide wire is inserted into the inner tube 42 from the opening 47 and protrudes from the distal end side of the balloon 41, and is used for a purpose having a stenosis portion. After inserting and placing the guide wire first from around the blood vessel,
Later, the catheter is inserted along the guide wire to the target blood vessel. Generally, the inner tube 42 and the outer tube 4 of the catheter 4
4 is made of a flexible material, so that it is difficult for the pressing force to be transmitted to the tip, but it has a core material 40 which is a flexible β-titanium alloy fine wire while having appropriate rigidity. The pushing force is easily transmitted by reinforcing the vicinity of 47, and can be inserted while following a meandering blood vessel. After being inserted into the target blood vessel, a liquid (contrast agent) is injected into the lumen of the outer tube 44 and the inner tube 42 from the proximal end of the catheter 4 to expand the stenosis, and the folded balloon 41 is expanded. Then, the stenosis is spread. When the catheter needs to be replaced, for example, when the expanded outer diameter of the balloon 41 does not match the diameter of the blood vessel, the inserted catheter 4 is pulled out while the guide wire remains in the target blood vessel, and another catheter 4 is removed. Into the lumen 43 through a guide wire.

Next, in a catheter 5 shown in FIG. 5, which is another embodiment, a balloon 51 is provided at the distal end thereof. Each is connected to a body 54.

The core member 50 is provided in the inner space of the tubular body 54 and the balloon 51. The core member 50 connected to the distal end side of the balloon 51 further extends inside the coil 58 and is fixed to the coil 58 at the most distal end. Guide member 56
Is constituted by a core material 50 and a coil 58 covering the core material. The core material 50 is provided at a position inside the tubular body 54.
The outer diameter becomes narrower toward the tip through the tapered portion. The outer diameter of the core member 50 of the guide member 56 is further reduced toward the distal end portion via the tapered portion. The base end of the core material 50 is fixed to the base end of the catheter. The space between the core material 50 and the tubular body 54 is a balloon 51
Becomes a lumen 55 for inflowing a liquid for expanding the pressure.

The β titanium alloy fine wire used for the core material 50 has an average crystal grain area A of β phase of 1 in the cross-sectional structure.
8080 μm 2, the average crystal grain length L of the β phase in the longitudinal section structure is 10-1000 μm, and L / ΔA = 5-1000.

In the present invention, by limiting the content to the above range, a flexible and high-strength β-titanium alloy fine wire having appropriate rigidity can be obtained, and a catheter provided with a core material 50 using the fine wire. 5 has a waist, is easy to push in, and has flexibility that can be inserted following a meandering blood vessel. In addition, the example in which the entire length of the core material 50 uses the β titanium alloy thin wire has been described.
By means of bonding or the like, another material, for example, a highly flexible wire such as a NiTi alloy wire may be used. Further, the base end of the core material 50 may be a highly rigid wire such as a stainless steel wire by means such as joining.

The catheter 5 is inserted using a guide member 56 like a guide wire. That is, the catheter 5 with the balloon 51 collapsed and folded is inserted into a target blood vessel having a stenosis. The catheter 5 is
Since the core member 50 is a flexible β-titanium alloy fine wire while having appropriate rigidity, the pushing force is easily transmitted, and the insertion can be performed while following a meandering blood vessel. After being inserted into the target blood vessel, a contrast agent is injected into the lumen 55 from the proximal end of the catheter 5 to expand the stenosis, and the folded balloon 51 is expanded to expand the stenosis.

Next, the stent 6 shown in FIG. 6 is a cylindrical body in which the β titanium alloy fine wires 60 are formed in a mesh shape.
The state is changed from the contracted state as shown in (a) to the state expanded by the balloon (FIG. 6B). In the expanded state, resistance to external pressure is high to prevent reocclusion of the stenosis.

The stent 6 may have a structure in which the β-titanium alloy fine wire 70 is formed in a curved shape in the circumferential direction as shown in FIG.

The β titanium alloy fine wire used for the stent 6 has an average crystal grain area A of β phase in the cross-sectional structure.
1 to 80 μm ² , the average crystal grain length L of the β phase in the longitudinal section structure is 10 to 1000 μm, and L / ΔA = 5 to 1000.

In the present invention, the reasons for limiting each factor for specifying the shape and size are as follows.

It is extremely difficult and unrealistic to obtain a β-phase having an average crystal grain area A of less than 1 μm ² in the cross-sectional structure by wire drawing. The average crystal grain area A
If it exceeds 80 μm 2, the strength is undesirably reduced.

If the average crystal grain length L of the β phase in the longitudinal sectional structure is less than 10 μm, there is a disadvantage that sufficient strength cannot be obtained, and it is difficult to process the average crystal grain length L exceeding 1000 μm.

In terms of the relationship between the average grain length L and the average grain area A, if L / ＬA <5, sufficient strength and flexibility cannot be obtained, and L / √A> 1000. Is difficult to process.

The diameter of the β-titanium alloy fine wire is 0.01 to 2.
It is preferably 0 mm. If the wire diameter is less than 0.01 mm, substantial strength cannot be obtained. The wire diameter is 2.0
If it exceeds mm, flexibility is impaired even at a low Young's modulus.

In the present invention, by limiting the content to the above range, a flexible and high-strength β-titanium alloy fine wire having appropriate rigidity can be obtained. Therefore, the stent made of the β-titanium alloy fine wire has both flexibility for passing through a blood vessel and appropriate rigidity after being placed for suppressing restenosis. That is, if the stent is hard, it is difficult to pass through a curved blood vessel. However, the stent of the present invention uses a flexible titanium alloy fine wire, and thus easily passes through a bent blood vessel. On the other hand, after the stent is expanded and deployed, acute occlusion can be prevented because of high resistance to external pressure. Furthermore, since it is softer than stainless steel and does not have too high a resistance to external pressure, stimulation to a living body is small.

The stent 8 shown in FIG. 8 is a cylindrical body in which a β titanium alloy thin wire 80 is formed in a zigzag shape and covered with a plastic covering material 82 having good biocompatibility. As shown in FIG. The stent 8 is inserted from a femoral artery via a sheath for treatment of an aortic aneurysm or the like. The stent 8, which is previously configured to have an outer diameter substantially equal to the inner diameter of the blood vessel, is contracted so as to fit within the inner diameter of the sheath when inserted through the sheath. It returns to its original shape and is placed in the aorta.

[0088]

Next, examples of the present invention will be described together with comparative examples. Solution treated at 850 ℃ for 10 minutes Ti-15V-3Cr-
A β-titanium alloy wire of 3Sn-3Al (β transformation point: about 760 ° C) is heated in an oxygen-containing atmosphere at 700 ° C to form an oxide film on the β-titanium alloy wire, and then drawn by a roller die. Then, using a hole die, wire drawing to 0.5mm,
Further, aging treatment was performed to precipitate a fine α phase in the β phase. The average crystal grain area A (μm ² ) of the β phase in the cross-sectional structure of each of Examples and Comparative Examples,
Phase average grain length L (μm), L / ΔA, tensile strength (k
gf / mm ² ) and Young's modulus (kgf / mm ² ) are shown in Table 1 below. In addition, the wire diameter D after cold drawing of the β titanium alloy wire of each Example and Comparative Example was all unified to 0.5 mm, and after each cold drawing, aged at 450 ° C. for 1 to 24 hours. Processing has been applied.

As a reference example, a superelastic Ni-Ti alloy (Reference Example 1) and a stainless steel SUS304 (Reference Example 2) were used to measure mechanical properties.

[0090]

[Table 1]

[0091]

The medical guide wire according to the present invention has a low stiffness and a high strength β titanium alloy fine wire and has a moderate waist strength and a flexibility. Further, since it has a high elasticity and high strength inner core capable of reshaping, it is excellent in torque transmission property, pushability, and selectivity in branching, has good operability, and can be used safely.

The catheter of the present invention has low waist modulus and high strength β-titanium alloy fine wire, has appropriate waist strength, and also has flexibility, and has excellent pushability and passability.

The stent of the present invention has both low flexibility and high strength β-titanium alloy fine wire for flexibility for passage of blood vessels and moderate rigidity after being placed for suppressing restenosis. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the medical guidewire of the present invention.

FIG. 2 is a sectional view showing another embodiment of the medical guidewire of the present invention.

FIG. 3 is a cross-sectional end view showing an embodiment of the catheter of the present invention.

FIG. 4 is a sectional front view showing another embodiment of the catheter of the present invention.

FIG. 5 is a cross-sectional end view showing another embodiment of the catheter of the present invention.

FIG. 6 is a perspective view showing an embodiment of the stent of the present invention.

FIG. 7 is a partially enlarged view showing another embodiment of the stent of the present invention.

FIG. 8 is a perspective view showing another embodiment of the stent of the present invention.

FIG. 9 is an enlarged perspective view conceptually showing a part of the β-titanium alloy thin wire of the present invention in the longitudinal direction.

[Explanation of symbols]

 1, 2: medical guide wire 10, 20: core material 3, 4, 5: catheter 30, 40, 50: core material 6, 7, 8: stent

Continuing from the front page (72) Inventor Ichiro Nagao 142-254 Fukuzou, Kozo-cho, Nishi-ku, Kobe City, Hyogo Prefecture F-term (reference) 4C081 AC08 BB07 CA022 CA032 CA042 CA162 CA212 CA232 CB012 CB052 CG03 DA16 DB08 DC03

Claims (3)

[Claims] The average grain area A of the β phase in the cross-sectional structure is 1 to 80 μm ² , the average grain length L of the β phase in the vertical structure is 10 to 1000 μm, and L / √A = 5-1000
A medical guidewire using a β-titanium alloy fine wire, characterized in that: 2. The average crystal grain area A of the β phase in the cross-sectional structure is 1 to 80 μm ² , the average crystal grain length L of the β phase in the vertical structure is 10 to 1000 μm, and L / √A = 5-1000
A catheter using a β-titanium alloy fine wire, characterized in that: 3. The average crystal grain area A of the β phase in the cross-sectional structure is 1 to 80 μm ² , the average crystal grain length L of the β phase in the vertical structure is 10 to 1000 μm, and L / √A = 5-1000
Stent using β-titanium alloy fine wire characterized by being