Guide wire and guide wire production method

Abstract

The present invention provides: a guide wire in which the joining strength at the joining interface of cores of differing outer diameters is high; and a guide wire production method. Provided is a guide wire 10 comprising a long core wire 20, wherein: the core wire 20 is provided with a first core 21 and a second core 22 that is joined to the tip end side of the first core 21; the outer diameter of the first core 21 extending toward the base end side from the base end of a joined part 60 where the first core 21 and the second core 22 are joined is smaller than the outer diameter of the second core 22 extending toward the tip end side from the tip end of the joined part 60; and the outer diameter of a joining interface between the first core 21 and the second core 22 is greater than the outer diameters of the base end and the tip end of the joined part 60.

Description

Guide wire and method for manufacturing guide wire

[0001] The present invention relates to a guide wire inserted into a lumen such as a blood vessel and a method for manufacturing a guide wire.

[0002] A guide wire is a device inserted into a blood vessel to guide a catheter or stent for intravascular treatment to a target position.

[0003] An operator first inserts a guide wire into a blood vessel and passes the distal end portion of the guide wire through a stenotic site of the blood vessel. Next, the operator inserts a catheter along the guide wire to the stenotic site to perform diagnosis and treatment. For this reason, guide wires are required to have properties such as vessel selectivity at vessel bifurcations, passability through stenotic sites, pushability, and torque transmissibility.

[0004] Furthermore, in recent years, as disclosed in, for example, Patent Document 1, procedures for treating lower limb arteries by inserting a device through the radial artery have been performed. In such procedures, since the distance from the insertion position of the device into the blood vessel to the lesion position is long, a longer guide wire than conventional ones is required.

[0005] In order for a guide wire to have different characteristics along the longitudinal direction, a core wire formed by joining a plurality of cores having different materials and outer diameters is sometimes used. For example, Patent Document 1 discloses a guide wire including a core wire obtained by joining a distal core made of a nickel-titanium alloy and a proximal core made of stainless steel by friction welding. In addition, Patent Document 2 discloses a method for manufacturing a core wire in which a distal core and a proximal core having a larger outer diameter than the distal core are connected via a tubular member.

[0006] US Patent Publication No. 2016 / 0279391 US Patent Publication No. 2002 / 0032390

[0007] However, the region near the joint of a core wire formed by joining two cores tends to have lower tensile strength compared to the tip and base regions of the joint due to the heat and deformation applied during the joining process. As a result, when the guide wire is subjected to a large load such as bending, kinking or fracture may occur at the joint. In particular, when the outer diameters of the cores being joined are different, stress concentration is likely to occur where the outer diameter changes along the long axis, so it is necessary to ensure sufficient joint strength at the joint.

[0008] The present invention was made to solve the above-mentioned problems, and aims to provide a guide wire and a method for manufacturing a guide wire that have high bonding strength at the joint surface between cores of different outer diameters.

[0009] (1) A guide wire that achieves the above objective is a guide wire having a long core wire, wherein the core wire comprises a first core and a second core joined to the tip side of the first core, wherein the outer diameter of the first core extending from the base end to the base end side of the joint between the first core and the second core is smaller than the outer diameter of the second core extending from the tip to the tip side of the joint, and the outer diameter of the joint surface between the first core and the second core is larger than the outer diameters of the base end and tip of the joint.

[0010] A method for manufacturing a guide wire that achieves the above objective (6) is a method for manufacturing a guide wire that includes a long core wire having a joint that joins a first core and a second core disposed on the tip side of the first core, and includes the steps of: preparing the first core and the second core having a larger outer diameter than the first core; solid-state bonding the tip of the first core and the base end of the second core; and polishing the region including the joint surface of the first core and the second core formed by the solid-state bonding to form the joint, wherein the outer diameter of the joint surface is larger than the outer diameters of the base end and tip of the joint.

[0011] As described above, the guide wire (1) can increase the surface area of ​​the joint between the first core and the second core, where the tensile strength of the core wire tends to decrease compared to other regions. Therefore, the joint strength between the first core and the second core, which have different outer diameters, is improved.

[0012] (2) In the guide wire described in (1) above, the outer diameter of the first core may be 70% to 80% of the outer diameter of the second core. This allows the catheter to be inserted smoothly without bending of the first core, even when a pushing force is applied when inserting the catheter from the proximal end of the guide wire.

[0013] (3) In the guide wire of (1) or (2) above, the joining surface may be located towards the tip of the joint from the center in the longitudinal direction of the joint. This allows the guide wire to have a larger joining surface area, thereby further improving the joining strength between the first core and the second core at the joint.

[0014] (4) In any of the guide wires described in (1) to (3) above, the joint portion may be covered with a first coating layer that covers the first core. As a result, the guide wire is continuously covered with the first coating layer from the first core to the proximal end of the second core, and this prevents the core wire from being exposed in the region from the proximal end to the middle portion of the core wire, thereby suppressing an increase in the insertion resistance of a catheter inserted from the proximal end.

[0015] (5) In any of the guide wires described in (1) to (4) above, the first core and the second core may be made of a nickel-titanium alloy. This allows the guide wire to have the appropriate flexibility and resilience to bending necessary when passing through highly curved blood vessels.

[0016] The guide wire manufacturing method of (6) configured as described above directly joins the first core with a smaller outer diameter and the second core with a larger outer diameter by solid-state bonding, making it easy to form a smooth tapered shape without steps at the joint between the first and second cores. Furthermore, the guide wire manufacturing method allows for a larger joint surface area at the joint between the base core and the intermediate core, where the tensile strength of the core wire tends to decrease compared to other regions. Therefore, it is possible to manufacture a guide wire with improved joint strength between the base core and the intermediate core, which have different outer diameters.

[0017] (7) In the guide wire manufacturing method described in (6) above, the first core and the second core may be made of a nickel-titanium alloy. This makes it possible to manufacture a guide wire that has the appropriate flexibility and resilience to bending required when passing through greatly curved blood vessels.

[0018] (8) In any of the guide wires described in (1) to (5) above, the joint portion may have a maximum inclination angle of 21.8° or less with respect to the long axis of the core wire, and the joint surface may have an outer diameter of 0.65 mm or more. This allows the guide wire to have stable joint strength while suppressing snagging during device insertion.

[0019] This is a front view of the guide wire according to this embodiment. This is a cross-sectional view obtained by cutting the guide wire with a plane along the long axis. This is an enlarged view of the vicinity of the base end joint in Figure 2. This is an enlarged view of the vicinity of the outer surface of the intermediate core covered with the intermediate coating layer in Figure 2. This is an enlarged view of the vicinity of the cylindrical member in Figure 2. This is an explanatory diagram showing the schematic of a friction measuring machine. This is an enlarged front view of the core wire near the base end joint of the base end core and intermediate core, excluding the coating layer. This figure shows the shape of the outer surface of the core wire near the base end joint, with the position in the long axis direction of the core wire as the horizontal axis and the outer diameter of the core wire as the vertical axis. This is an enlarged front view of the core wire near the base end joint of the base end core and intermediate core, excluding the coating layer, for a different shaped base end joint. This figure shows the shape of the outer surface of the core wire near the base end joint, with the position in the long axis direction of the core wire as the horizontal axis and the outer diameter of the core wire as the vertical axis, for a different shaped base end joint. This is an enlarged front view of the core wire near the tip joint of the intermediate core and tip core, excluding the coating layer. This figure shows the outer surface shape of the core wire near the tip joint, with the longitudinal axis of the core wire's position on the horizontal axis and the outer diameter of the core wire on the vertical axis. This figure shows the measured outer diameter along the longitudinal axis near the tip joint of the guide wire. This figure shows the measured outer diameter along the longitudinal axis near the proximal joint of the guide wire. This is an explanatory diagram showing each core wire before the guide wire is joined. This is an enlarged view showing the joining process of the intermediate core and the tip core. This is an enlarged view showing the joining process of the proximal core and the tip core and the formation process of the proximal coating layer and overlapping portion. This is an enlarged front view of the core wire near the proximal joint of a proximal core and an intermediate core, including multiple proximal joints of different shapes. This is a graph showing the measured distance between the center line and the outer surface with respect to the longitudinal axis position near the proximal joint of the core wire. This is an enlarged cross-sectional view showing the relationship between the guide wire and the catheter when evaluating the resistance of a catheter inserted from the proximal end side of the guide wire. This is the result of a tensile test performed on the proximal joint of the guide wire. This is an enlarged front view of the vicinity of the proximal joint of a core wire having a proximal joint of a different shape.

[0020] Embodiments of the present invention will be described below with reference to the drawings. Note that the dimensions in the drawings may be exaggerated for illustrative purposes and may differ from the actual dimensions. Furthermore, in this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals to avoid redundant explanations.

[0021] In this specification, the direction in which the guidewire extends in its natural state (without any external force applied and in a straight state) is defined as the "long axis direction." In a cross-section perpendicular to the long axis direction of the guidewire, the direction approaching or moving away from the long axis passing approximately through the center of the guidewire is defined as the "radial direction." Furthermore, the end of the guidewire that is inserted into the blood vessel is defined as the tip end, and the end opposite the tip end is defined as the proximal end. Additionally, the portion including a certain range in the long axis direction from the tip (extentmost point) is defined as the "tip," the portion including a certain range in the long axis direction from the proximal end (very proximal end) is defined as the "proximal end," and the portion including a certain range in the long axis direction between the tip and proximal ends is defined as the "intermediate portion."

[0022] In this specification, the range "X to Y" includes X and Y, and means "X or greater and Y or less".

[0023] The guidewire 10 of this embodiment is used in a procedure to treat lower limb arteries by inserting a device including a guidewire and various catheters such as a balloon catheter, stent delivery catheter, and imaging catheter into the radial artery of the arm. The total length of the guidewire 10 in the longitudinal direction is 3000 mm to 6000 mm, for example, 3450 mm to 3550 mm, 3950 mm to 4050 mm, 4450 mm to 4550 mm, and 4950 mm to 5050 mm.

[0024] As shown in Figures 1 and 2, the guide wire 10 comprises a long core wire 20 and a coating layer 70 covering the outer surface of the core wire 20. The core wire 20 is formed by joining three members along the long axis, from the base end to the tip end: a base core 21 (first core), an intermediate core 22 (second core), and a tip core 23 (third core). The coating layer 70 has a base coating layer 71 covering the base end of the core wire 20, an intermediate coating layer 73 covering the middle part of the core wire 20, and a tip coating layer 76 covering the tip of the core wire 20.

[0025] The shape of the tip core 23 of the guide wire 10 is not particularly limited, but may be straight or shaped to be bent at a predetermined angle. The bent shape of the tip core 23 may be, for example, J-shaped.

[0026] The base core 21 extends from the base end of the core wire 20 to the base joint 60 where it is joined to the intermediate core 22. The intermediate core 22 extends from the base joint 60 to the tip joint 65 where it is joined to the tip core 23. The tip core 23 extends from the tip joint 65 to the tip of the core wire 20.

[0027] The base core 21 has a first constant outer diameter section 30 with a constant outer diameter along the long axis, and a first enlarged diameter section 31 with an outer diameter that increases from the tip of the first constant outer diameter section 30 toward the tip. The outer diameter of the first constant outer diameter section 30 is 0.40 mm to 0.60 mm, preferably 0.55 mm to 0.59 mm. The length of the first constant outer diameter section 30 is 800 mm to 2100 mm, and an appropriate length can be selected depending on the total length of the guide wire, for example, 900 mm to 920 mm, 1500 mm to 1520 mm, or 1900 mm to 1920 mm can be selected. The length of the first enlarged diameter section 31 is 0.2 mm to 1.0 mm, preferably 0.3 mm to 0.5 mm.

[0028] The intermediate core 22 has a second enlarged diameter section 40 in which the outer diameter increases from the base end to the tip end, a second constant outer diameter section 41 in which the outer diameter is constant from the tip of the second enlarged diameter section 40 towards the tip end, a first reduced diameter section 42 in which the outer diameter decreases from the tip of the second constant outer diameter section 41 towards the tip end, and a third constant outer diameter section 43 in which the outer diameter is constant from the tip of the first reduced diameter section 42 towards the tip end. The second constant outer diameter section 41 of the intermediate core 22 has a larger outer diameter than the first constant outer diameter section 30 of the base core 21. The third constant outer diameter section 43 of the intermediate core 22 has a smaller outer diameter than the second constant outer diameter section 41 of the intermediate core 22. The third constant outer diameter section 43 has a larger outer diameter than the first constant outer diameter section 30 of the base core 21. The length of the second enlarged diameter section 40 of the intermediate core 22 is 0.2 mm to 3.0 mm, preferably 0.3 mm to 0.4 mm. The outer diameter of the second constant outer diameter section 41 is 0.40 mm to 0.80 mm, preferably 0.75 mm to 0.77 mm. The length of the second constant outer diameter section 41 is 2000 mm to 2800 mm, preferably 2320 mm to 2350 mm. The length of the first reduced diameter section 42 is 55 mm to 80 mm, preferably 65 mm to 75 mm. The outer diameter of the third constant outer diameter section 43 is 0.40 mm to 0.75 mm, preferably 0.68 mm to 0.72 mm. The length of the third constant outer diameter section 43 is 10 mm to 80 mm, preferably 20 mm to 30 mm.

[0029] The tip core 23 has a fourth constant outer diameter section 51 with a constant outer diameter along the long axis, a third reduced diameter section 52 where the outer diameter decreases from the tip of the fourth constant outer diameter section 51 toward the tip, and a fifth constant outer diameter section 53 where the outer diameter remains constant from the tip of the third reduced diameter section 52 toward the tip. The fourth constant outer diameter section 51 of the tip core 23 has approximately the same outer diameter as the third constant outer diameter section 43 of the intermediate core 22. The fifth constant outer diameter section 53 of the tip core 23 has a smaller outer diameter than the fourth constant outer diameter section 51 of the tip core 23. The fifth constant outer diameter section 53 of the tip core 23 has the smallest outer diameter in the core wire 20. The outer diameter of the fourth constant outer diameter section 51 is 0.40 mm to 0.75 mm, preferably 0.68 mm to 0.72 mm. The length of the fourth constant outer diameter section 51 is 15 mm to 200 mm, preferably 20 mm to 40 mm. The length of the third reduced diameter section 52 is 50 mm to 250 mm, preferably 165 mm to 230 mm. The outer diameter of the fifth constant outer diameter section 53 is 0.05 mm to 0.25 mm, preferably 0.15 mm to 0.20 mm. The length of the fifth constant outer diameter section 53 is 5 mm to 40 mm, preferably 10 mm to 30 mm. The tip core 23 does not necessarily have to have the fifth constant outer diameter section 53. The third reduced diameter section 52 may also be formed by a plurality of tapers with different taper angles. For example, the third reduced diameter section 52 can be composed of two tapers: a taper on the base end side and a taper on the tip side where the taper angle is smaller than the taper angle on the base end side.

[0030] The outer diameter of the first constant outer diameter portion 30 of the proximal core 21 is smaller than the outer diameter of the second constant outer diameter portion 41 of the intermediate core 22. The outer diameter of the first constant outer diameter portion 30 of the proximal core 21 can be set to 70% to 80% of the outer diameter of the second constant outer diameter portion 41 of the intermediate core 22. By making the outer diameter of the proximal core 21 smaller than the outer diameter of the intermediate core 22, the guidewire 10 can increase the clearance between the outer surface of the guidewire 10 and the inner surface of the catheter at the proximal core 21, thereby reducing the frictional resistance between the guidewire and the catheter. Furthermore, by setting the outer diameter of the first constant outer diameter portion 30 of the guidewire 10 to 70% or more of the outer diameter of the second constant outer diameter portion 41, the catheter can be smoothly inserted without bending at the proximal end, even when a pushing force is applied when inserting the catheter from the proximal end of the guidewire 10. As described above, by setting the relationship between the outer diameter of the first constant outer diameter portion 30 of the proximal core 21 and the outer diameter of the second constant outer diameter portion 41 of the intermediate core 22, the guidewire 10 can improve the ease of catheter insertion from the proximal end. Furthermore, by making the outer diameter of the proximal core 21 smaller than the outer diameter of the intermediate core 22, the rigidity of the proximal end of the guidewire, which is located outside the body during the procedure, can be reduced. Therefore, the guidewire 10 can be easily held in a bundled state with its proximal end temporarily wrapped around multiple times.

[0031] The base core 21, intermediate core 22, and tip core 23 are all made of metal. The base core 21, intermediate core 22, and tip core 23 are made of various metals and alloys such as superelastic alloys (e.g., nickel-titanium alloys), stainless steel (e.g., all varieties of SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429, SUS430F, SUS302, SUS301, etc.), piano wire, and cobalt alloys. As an example, the base core 21, intermediate core 22, and tip core 23 are all made of nickel-titanium alloy. Another preferred example is that the base core 21 and intermediate core 22 are made of stainless steel, and the tip core 23 is made of nickel-titanium alloy. By appropriately selecting the materials that form the base core 21, intermediate core 22, and tip core 23, the guide wire 10 can have different physical properties along its long axis.

[0032] The coating layer 70 covers the outer surface of the core wire 20 and has a base coating layer 71, an intermediate coating layer 73, and a tip coating layer 76, extending from the base end to the tip end. A cylindrical member 25 is placed at the base end of the tip coating layer 76 to prevent the tip coating layer 76 from peeling off, and the cylindrical member 25 is fixed using a cylindrical fixing member 26.

[0033] The base end coating layer 71 is positioned to cover the base ends of the first constant outer diameter portion 30 and the first enlarged diameter portion 31 of the base end core 21, and the second enlarged diameter portion 40 and the second constant outer diameter portion 41 of the intermediate core 22. The base end coating layer 71 has a base end lubrication layer 72. In the first constant outer diameter portion 30 and the first enlarged diameter portion 31 of the base end core 21, and the second enlarged diameter portion 40 of the intermediate core 22, the base end lubrication layer 72 is positioned on the outer surface of the core wire 22. In the second constant outer diameter portion 41 of the intermediate core 22, the base end lubrication layer 72 is positioned to cover a portion of the outer surface of the intermediate coating layer 73. As a result, as shown in Figure 3, the coating layer 70 has an overlap portion 79 between the base end coating layer 71 and the intermediate coating layer 73, formed by the outer surface of the intermediate coating layer 73 being covered by the base end coating layer 71.

[0034] The intermediate coating layer 73 is positioned to cover the base ends of the second constant outer diameter portion 41, the first reduced diameter portion 42, and the third constant outer diameter portion 43 of the intermediate core 22. The intermediate coating layer 73 has an intermediate resin layer 74 positioned on the outer surface of the intermediate core 22 and a linear body 75 positioned spirally on the outer surface of the intermediate resin layer 74. As shown in Figure 4, the intermediate resin layer 74 has an inner layer 74a that covers the outer surface of the intermediate core 22 and an outer layer 74b that covers the outer surface of the inner layer 74a, and the linear body 75 is positioned on the outer surface of the outer layer 74b.

[0035] The linear body 75 is arranged along substantially the entire length of the intermediate core 22, and is formed by winding the wire that forms the linear body 75 in a spiral manner such that adjacent windings are spaced apart. In a longitudinal section including the long axis of the guide wire 10, the linear body 75 has a convex shape that protrudes radially outward from the outer surface of the intermediate resin layer 74. In a longitudinal section including the long axis of the guide wire 10, the height of the convex shape formed by the linear body 75 from the outer surface of the intermediate resin layer 74 is 0.001 mm to 0.015 mm, preferably 0.005 mm to 0.012 mm. The width of the wire that forms the linear body 75 is 0.1 mm to 1.0 mm, preferably 0.4 mm to 0.9 mm. The spiral pitch is 0.5 mm to 2.0 mm, preferably 1.3 mm to 1.8 mm.

[0036] The middle portion of the guidewire 10, when inserted into the lumen of the catheter, has a portion that is located within the lumen of the catheter and in contact with the inner surface of the catheter, and a portion that extends from the proximal end of the catheter toward the proximal end and is located outside the catheter and is grasped by the operator. Because the guidewire 10 has a linear body 75 in the intermediate coating layer 73, the contact area with the inner surface of the catheter is reduced in the portion located within the lumen of the catheter, thereby reducing frictional resistance during operations such as movement and rotation of the guidewire 10. Therefore, the guidewire 10 can improve the delivery of the catheter. In addition, in the portion of the guidewire 10 located outside the catheter, the operator's fingers can get into the uneven shape formed by the linear body 75, thereby improving the operator's gripping strength. Thus, the operability of the guidewire 10 is improved.

[0037] As shown in Figure 3, an overlapping portion 79 is formed in the second constant outer diameter portion 41 of the intermediate core 22, where a part of the outer surface of the intermediate coating layer 73 is covered by the base end coating layer 71. In the overlapping portion 79, the base end coating layer 71 covers both the intermediate resin layer 74 and the linear body 75 that constitute the intermediate coating layer 73. Therefore, in the longitudinal cross-section of the guide wire 10, the outer surface of the base end coating layer 71 has a convex shape in which the outer surface of the base end coating layer 71 protrudes radially outward, following the outer shape of the linear body 75. In the longitudinal cross-section of the guide wire 10, the height of the base end coating layer 71 from the outer surface of the linear body 75 (thickness of the base end coating layer 71) in the convex portion formed by the linear body 75 and the base end coating layer 71 is 0.001 μm to 1.0 μm.

[0038] The coating layer 70 has an overlapping portion 79, which allows the base coating layer 71 to continuously cover the base core 21 to the base end of the intermediate core 22. As a result, the base coating layer 71 eliminates any exposed portion of the core wire 20 in the region from the base end to the intermediate portion of the core wire 20, thereby suppressing an increase in the insertion resistance of the catheter inserted from the base end of the guide wire 10. Furthermore, since the base coating layer 71 covers the base end of the intermediate coating layer 73 in the overlapping portion 79, it is possible to prevent the tip of the catheter from getting caught on the base end of the intermediate coating layer 73 when inserting the catheter from the base end of the guide wire 10 toward the tip. As a result, the guide wire 10 can suppress peeling of the intermediate coating layer 73 and damage to the catheter inserted from the base end. In addition, the overlapping portion 79 can be easily formed by covering the base end of the intermediate coating layer 73 with the base coating layer 71.

[0039] The tip coating layer 76 is positioned to cover the tip of the fourth constant outer diameter portion 51, the third reduced diameter portion 52, and the fifth constant outer diameter portion 53 of the tip core 23. The tip resin layer 77 covers the tip of the core wire 20, thereby forming the rounded tip of the guide wire 10. The tip coating layer 76 has a tip resin layer 77 positioned on the outer surface of the tip core 23 and a tip lubrication layer 78 positioned on the outer surface of the tip resin layer 77.

[0040] As shown in Fig. 5, the cylindrical member 25 is a cylindrical member that suppresses curling of the distal coating layer 76 coated on the distal core 23. The cylindrical member 25 is in contact with the proximal end of the distal coating layer 76, and is arranged coaxially with the distal core 23 on the radially outer side of the distal core 23. It is preferable that the outer surface of the cylindrical member 25 is not coated with the distal lubricating layer 78. The cylindrical member 25 is fixed to the outer surface of the proximal end portion of the fourth constant outer diameter portion 51 of the distal core 23 by a cylindrical fixing member 26 arranged on the proximal side. The material for forming the cylindrical member 25 is, for example, platinum-iridium alloy, but is not particularly limited as long as it has a thin cylindrical shape, and may be other metallic materials or resin materials. The material for forming the cylindrical fixing member 26 is, for example, solder, but is not particularly limited as long as the cylindrical member 25 can be fixed to the distal core 23, and may be, for example, a brazing material or an adhesive.

[0041] The cylindrical member 25 and the cylindrical fixing member 26 are ground such that corner portions on the proximal side are chamfered, and are inclined so as to be smoothly continuous with the distal core 23.

[0042] The length of the cylindrical member 25 in the major axis direction is, for example, 0.75 mm to 0.85 mm, and the length of the cylindrical fixing member 26 in the major axis direction is, for example, 0.2 mm to 1.5 mm. The outer diameter of the cylindrical member 25 is, for example, 0.83 mm to 0.86 mm.

[0043] The position of the proximal end of the distal coating layer 76 is located more distally than the proximal end of the fourth constant outer diameter portion 51, and the position of the distal end of the intermediate coating layer 73 is located more proximally than the distal end of the third constant outer diameter portion 43. The proximal end of the distal coating layer 76 is covered with the cylindrical member 25 and the cylindrical fixing member 26. For this reason, the core wire 20 has an exposed portion 69 that is not covered with the coating layer 70, the cylindrical member 25 and the cylindrical fixing member 26, extending from the distal end portion of the intermediate core 22 to the proximal end portion of the distal core 23.

[0044] The proximal lubricating layer 72 constituting the proximal coating layer 71 can be formed of a hydrophobic material. The proximal lubricating layer 72 can be formed of, for example, a reaction-curable silicone resin or a composite material containing the same. In addition, lubricating oils containing hydrocarbons, esters, ethers, fluorine, etc., or composite materials of these may also be used.

[0045] The thickness of the proximal lubricant layer 72 is not particularly limited, and may be, for example, 0.001 μm to 1.0 μm.

[0046] The intermediate resin layer 74 and the linear body 75 constituting the intermediate coating layer 73 can be formed of a hydrophobic material. A fluorine-based resin can be used for the inner layer 74a constituting the intermediate resin layer 74. Further, the inner layer 74a contains two types of fluorine-based resins having different compositions. For the two types of resins contained in the inner layer 74a, for example, one can be polytetrafluoroethylene (PTFE) and the other can be fluorinated ethylene propylene (FEP). Further, the inner layer 74a contains a binder in the material for the purpose of improving adhesion to the intermediate core 22. The binder is not particularly limited, and for example, resins such as polysulfone, polyimide, polyether ether ketone, polyarylene ketone, polyphenylene sulfide, polyarylene sulfide, polyamideimide, polyetherimide, polyimide sulfone, polyallyl sulfone, polyallyl ether sulfone, polyester, and polyether sulfone can be used.

[0047] The thickness of the inner layer 74a is not particularly limited, but for example, it is preferably 0.001 mm to 0.015 mm, and more preferably 0.003 mm to 0.009 mm.

[0048] Similar to the inner layer 74a, the outer layer 74b can be formed of a fluorine-based resin. Two types, PTFE and FEP, can be used. The thickness of the outer layer 74b is not particularly limited, but for example, it is preferably 0.002 mm to 0.015 mm, and more preferably 0.003 mm to 0.011 mm.

[0049] A fluorine-based resin material can be used for the linear body 75. As the fluorine-based resin, for example, PTFE, FEP, or the like can be used.

[0050] The tip resin layer 77 constituting the tip coating layer 76 can be formed from a flexible resin. For example, polyethylene, polyolefins such as polypropylene, polyvinyl chloride, polyester (PET, PBT, etc.), polyamide, polyimide, polystyrene, silicone resin, thermoplastic elastomers such as polyurethane elastomer, polyester elastomer, and polyamide elastomer, various rubber materials such as latex rubber and silicone rubber, or composite materials combining two or more of these can be used. Furthermore, it is preferable that the tip resin layer 77 contains radiopaque particles. The material forming the tip resin layer 77 can be, for example, polyurethane containing tungsten fine particles.

[0051] The tip lubrication layer 78 can be formed from a hydrophilic material. As a result, the guidewire 10 becomes lubricated within the body due to the hydrophilic material, reducing frictional resistance and thus providing the high vascular selectivity and high passability through the narrowed area necessary when advancing the guidewire into the narrowed area.

[0052] The hydrophilic material forming the tip lubrication layer 78 can be a cellulosic polymer, a polyethylene oxide polymer, a maleic anhydride polymer (for example, a maleic anhydride copolymer such as a methyl vinyl ether-maleic anhydride copolymer), an acrylamide polymer (for example, a block copolymer of polyacrylamide, polyglycidyl methacrylate-dimethylacrylamide (PGMA-DMAA)), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, etc.

[0053] The thickness of the tip resin layer 77 is not particularly limited, but can be, for example, 0.01 mm to 0.32 mm. The thickness of the tip lubrication layer 78 is not particularly limited, but can be, for example, 0.4 μm to 4.0 μm.

[0054] The length of the guide wire 10 from its base end to the base end position of the overlapping portion 79, that is, the length covered only by the base end coating layer 71, is 920 mm to 1920 mm, or 1080 mm to 2080 mm.

[0055] The length of the overlapping portion 79 is, for example, 100 mm to 250 mm, preferably 150 mm to 200 mm.

[0056] The length of the intermediate coating layer 73 is, for example, 2250 mm to 2650 mm, preferably 2275 mm to 2315 mm.

[0057] The proximal end of the intermediate coating layer 73 is located 2525 mm to 2655 mm from the tip of the core wire 20. This ensures that in a procedure to treat a lower limb artery by inserting the device through the radial artery, the intermediate coating layer 73 of the guidewire 10 is located at the proximal end of the catheter. As a result, the guidewire 10 has a portion where the intermediate coating layer 73 is located inside the catheter lumen and in contact with the inner surface of the catheter, and a portion located outside the catheter and grasped by the operator, thus achieving both catheter delivery and operator maneuverability.

[0058] The guidewire 10 can have its overall length changed while keeping the lengths of the intermediate core 22 and tip core 23 constant by changing the length of the proximal core 21. This allows the overall length of the guidewire 10 to be changed while positioning the intermediate coating layer 73 at the proximal end of the catheter.

[0059] The length of the exposed portion 69 is, for example, 5 mm to 100 mm, preferably 10 mm to 80 mm.

[0060] The length of the tip coating layer 76 is 230 mm to 270 mm, preferably 240 mm to 260 mm.

[0061] The proximal core 21 is set to be 50% or less of the total length of the core wire 20. The guidewire 10 is sometimes used with an over-the-wire type catheter in a procedure to treat the arteries of the lower extremities by inserting a device through the radial artery. In this case, in order to remove the catheter while leaving the tip of the guidewire 10 inside the blood vessel, the proximal end that the operator manipulates must not be fully inserted into the lumen of the catheter, but must remain exposed from the proximal end of the catheter. Therefore, the operator must use a guidewire 10 whose length extending from the proximal end of the catheter is greater than or equal to the length of the catheter, and this length may be more than twice the length of the catheter. If the total length of the guidewire 10 is long, the distance from the operator's position to the tip also increases, making it difficult for the operator's movement and rotational operations to be transmitted to the tip of the guidewire 10. In addition, if the proximal core 21 is long, the distance the catheter moves from the proximal end of the guidewire 10 to the catheter increases, which may impair the ease of catheter insertion. The guidewire 10 maintains catheter insertability while ensuring sufficient length for catheter removal at the proximal end of the catheter by setting the length of the proximal core 21 to 50% or less of the total length of the core wire 20. Furthermore, since the guidewire 10 has sufficiently long intermediate core 22 and tip core 23, which have a larger outer diameter than the proximal core 21, it can be equipped with various performance characteristics necessary for a guidewire, such as vascular selectivity, passage through stenosis, pushability, and torque transmission.

[0062] The frictional resistance of each part of the guide wire 10 was measured using the friction measuring device (Trinity Labs, Tribomaster) 100 shown in Figure 6. The sample to be tested was the base end coating layer 71, the overlapping portion 79, the intermediate coating layer 73, the exposed portion 69, and the tip coating layer 76 of the guide wire 10.

[0063] The friction resistance test method is as follows. First, sample 105 was fixed in petri dish 110 and the entire sample 105 was immersed in water 115. Next, this petri dish 110 was placed on the movable table 111 of the friction measuring machine 100 shown in Figure 6. Then, a terminal 112 made of rubber was brought into contact with sample 105 and a load of 100 g was applied to the terminal 112. The friction resistance value (gf) was measured when the movable table 111 was moved back and forth horizontally 10 times at a sliding speed of 16.7 mm / sec.

[0064] The outer diameter of the guide wire 10, where the frictional resistance was measured, was measured using a thickness gauge at the base end coating layer 71, the overlapping portion 79, the intermediate coating layer 73, the exposed portion 69, and the tip coating layer 76. The outer diameter was calculated by measuring the three points where the frictional resistance was measured and taking the average value as the outer diameter of that portion.

[0065] Table 1 shows the results of the friction resistance test, and Table 2 shows the results of the outer diameter measurement. From Examples 1 to 5, the coating layer 70 of the guide wire 10 is formed such that the friction resistance is lowest at the tip coating layer 76, and increases in the order of overlapping portion 79, intermediate coating layer 73, base end coating layer 71, and exposed portion 69.

[0066]

[0067]

[0068] The overlapping portion 79 has lower frictional resistance than the proximal coating layer 71 and the intermediate coating layer 73. This further reduces the risk of the catheter tip getting caught on the intermediate coating layer 73 and being damaged when the catheter is inserted from the proximal end of the guidewire 10.

[0069] The guide wire 10 has a proximal lubrication layer 72 made of silicone resin in the proximal coating layer 71, giving the proximal end appropriate frictional resistance. Therefore, the guide wire 10 can be securely held by the operator or clip when the operator holds the proximal end for catheter insertion or when it is temporarily wrapped around multiple times and bundled and held with a clip or the like. As a result, the guide wire 10 can prevent the core wire 20 from returning to a straight state and becoming uncontrollable when held.

[0070] Next, the base joint portion 60, to which the base core 21 and the intermediate core 22 are joined, will be described. As shown in Figure 7, the base joint portion 60 has a base diameter expansion portion 27 that tapers in diameter from the base end side to the tip side of the core wire 20. The base diameter expansion portion 27 is formed by the continuation of the first diameter expansion portion 31 of the base core 21 and the second diameter expansion portion 40 of the intermediate core 22, forming a single tapered shape. In the embodiment shown in Figure 7, the entire base joint portion 60 corresponds to the base diameter expansion portion 27. The base joint surface 61 between the base core 21 and the intermediate core 22 is located in the tapered diameter expansion portion 27. As a result, the guidewire 10 exhibits a gradual change in rigidity along its long axis near the proximal joint 60, which joins the proximal core 21 and the intermediate core 22, which have different outer diameters. This suppresses stress concentration at the proximal joint 60 when it bends during catheter insertion from the proximal end of the guidewire 10, thereby improving its kink resistance.

[0071] The base joint surface 61 is located towards the tip of the base joint 60, relative to the central position in the longitudinal direction. Since the base joint surface 61 is the part that joins the metals forming the base core 21 and the intermediate core 22, the area near the base joint surface 61 tends to have lower tensile strength of the core wire 20 compared to other areas (for example, the first constant outer diameter portion 30 of the base core 21 and the second constant outer diameter portion 41 of the intermediate core 22). The guide wire 10 improves the joint strength because the base joint surface 61 is located towards the tip of the base joint 60, relative to the central position in the longitudinal direction of the base joint 60, which expands in diameter toward the tip. The position of the base joint surface 61 in the base joint 60 in the longitudinal direction is 0.3 mm to 2.0 mm toward the base from the tip of the base joint 60, which is the tip of the second expanding diameter portion 40 of the intermediate core 22.

[0072] A more detailed description of the base joint 60 will be given based on Figure 8. The area A in the figure corresponds to the first enlarged diameter portion 31 and the second enlarged diameter portion 40, and includes the base joint surface 61. On the base end side of the first enlarged diameter portion 31, there is a base-side recess 62 that is recessed radially inward from the first constant outer diameter portion 30 of the base core 21 (area B in the figure). The base-side recess 62 (area B in the figure) has a depth greater than 0 mm and 0.06 mm or less, and a length in the longitudinal direction greater than 0 mm and 2.0 mm or less. By having the base-side recess 62, the base joint 60 can distribute the stress applied to the base joint surface 61 when the vicinity of the base joint 60 is curved. As a result, the kink resistance of the guide wire 10 at the base joint 60 is improved. The base joint 60 is assumed to be the area C in the figure, which includes the first enlarged diameter portion 31, the second enlarged diameter portion 40, and the base-side recess 62. The length of the base joint portion 60 in the longitudinal direction (range C in the figure) is 0.5 mm to 5.0 mm. Note that the base joint portion 60 does not necessarily have a base-side recess 62.

[0073] The proximal joint 60 has a tapered diameter that expands continuously from the proximal core 21, which has a smaller outer diameter, to the intermediate core 22, which has a larger outer diameter, with a first expanded diameter section 31 and a second expanded diameter section 40, and has a smooth outer surface without any steps. As a result, the guidewire 10 can prevent the catheter, which is inserted from the proximal end of the guidewire 10, from getting caught as it advances from the proximal core 21, which has a smaller outer diameter, through the proximal joint 60 to the intermediate core 22, which has a larger outer diameter.

[0074] Another shape of the base joint portion 60 will be described. As shown in Figure 9, the base joint portion 60 may have a shape that protrudes radially such that the outer diameter at the base joint surface 61 is larger than the outer diameter of the base core 21 and the outer diameter of the intermediate core 22. In this case, the base joint portion 60 has a base projection portion 28 that protrudes radially outward. The base core 21 has a first constant outer diameter portion 30 and a first enlarged diameter portion 31 that expands in diameter from the tip of the first constant outer diameter portion 30 to the base joint surface 61, and the intermediate core 22 has a fourth reduced diameter portion 46 that decreases in diameter from the base joint surface 61 toward the tip side and a second constant outer diameter portion 41 that extends from the tip of the fourth reduced diameter portion 46 toward the tip side. The base end projection 28 is provided between the first constant outer diameter portion 30 of the base end core 21 and the second constant outer diameter portion 41 of the intermediate core 22, and is formed by the first enlarged diameter portion 31 of the base end core 21 and the fourth reduced diameter portion 46 of the intermediate core 22. The base end joint surface 61 is located at the top of the base end projection 28 or at a portion of the intermediate core 22 with a larger outer diameter than the second constant outer diameter portion 41. In the longitudinal section of the guide wire 10, the length of the base end projection 28 in the longitudinal direction is 0.1 mm to 0.7 mm, and the height from the outer surface of the second constant outer diameter portion 41 of the intermediate core 22 is 0.001 mm to 0.04 mm. The base end joint 60 has a base end enlarged diameter portion that tapers in diameter from the base end side to the tip side of the core wire 20. In the embodiment shown in Figure 9, the first enlarged diameter portion 31 of the base end joint 60 corresponds to the base end enlarged diameter portion. The tip of the base end enlarged portion is continuous with the base end of the base end projection 28.

[0075] In Figure 10, area A in the figure corresponds to the first enlarged diameter portion 31 and the fourth reduced diameter portion 46, and includes the base end joint surface 61. The core wire 20 has a base end recess 62 on the base end side of the first enlarged diameter portion 31, which is recessed radially inward from the first constant outer diameter portion 30 of the base end core 21 (area B in the figure). The core wire 20 also has a tip end recess 63 on the tip side of the fourth reduced diameter portion 46, which is recessed radially inward from the second constant outer diameter portion 41 of the intermediate core 22 (area C in the figure). The base end recess 62 has a depth greater than 0 mm and 0.06 mm or less, and a length in the longitudinal direction (area B in the figure) greater than 0 mm and 2.0 mm or less. The tip end recess 63 has a depth greater than 0 mm and 0.03 mm or less, and a length in the longitudinal direction (area C in the figure) greater than 0 mm and 2.0 mm or less. The base joint 60 has a base-side recess 62 and a tip-side recess 63, which allows the stress on the base joint surface 61 to be distributed when the vicinity of the base joint 60 is curved. As a result, the guide wire 10 has improved kink resistance at the base joint 60. The base joint 60 is defined as being in the range D in the figure, including the first enlarged diameter portion 31, the fourth reduced diameter portion 46, the base-side recess 62, and the tip-side recess 63. The length of the base joint 60 in the longitudinal direction is 1.0 mm to 5.0 mm. Note that the base joint 60 does not necessarily have a base-side recess 62 and a tip-side recess 63.

[0076] In Figure 9, the embodiment shown by the solid line and the embodiment shown by the dashed line differ in the depth of the base-side recess 62 from the outer surface of the first constant outer diameter portion 30. The base-side recess 62 is formed in the manufacturing process of the base-end joint portion 60, which will be described later, and its depth may change depending on the manufacturing conditions.

[0077] Because the guide wire 10 has a base end projection 28, the area of ​​the base end joint surface 61 between the base end core 21 and the intermediate core 22 is increased in the base end joint 60, where the tensile strength of the core wire 20 tends to decrease compared to other areas, thus improving the joint strength.

[0078] Next, the detailed shape of the tip joint 65 will be described. As shown in Figure 11, the tip joint 65 that joins the intermediate core 22 and the tip core 23 has a tip projection 29 that protrudes radially outward. The intermediate core 22 has a third expanding diameter portion 44 that expands in diameter from the tip of the third constant outer diameter portion 43 toward the tip, and the tip core 23 has a second reducing diameter portion 50 that reduces in diameter from the tip of the third expanding diameter portion 44 toward the tip. The tip projection 29 is provided between the third constant outer diameter portion 43 of the intermediate core 22 and the fourth constant outer diameter portion 51 of the tip core 23, and is formed by the tip of the third expanding diameter portion 44 and the base end of the second reducing diameter portion 50. The tip joint surface 66 between the intermediate core 22 and the tip core 23 is located at the top of the tip projection 29. The tip joint surface 66 is the part where the metals forming the intermediate core 22 and the tip core 23 are joined together. Therefore, the area near the tip joint surface 66 tends to have lower tensile strength of the core wire 20 compared to other areas (for example, the third constant outer diameter portion 43 of the intermediate core 22 and the fourth constant outer diameter portion 51 of the tip core 23). Because the tip joint surface 66 is located at the top of the tip projection 29, the area of ​​the tip joint surface 66 is increased, thus improving the joint strength.

[0079] The tip joint 65 has the same diameter at the third constant outer diameter portion 43 of the intermediate core 22 located on the proximal end side and the fourth constant outer diameter portion 51 of the tip core 23 located on the tip side. As a result, the rigidity of the guidewire 10 does not change abruptly along the longitudinal axis near the tip joint 65, so stress concentration at the tip joint 65 when bending in a blood vessel is suppressed, and kink resistance is improved.

[0080] A more detailed description of the tip joint portion 65 will be given based on Figure 12. The area A in the figure corresponds to the third enlarged diameter portion 44 and the second reduced diameter portion 50, and includes the tip joint surface 66. As described above, the tip projection portion 29 is formed by the third enlarged diameter portion 44 and the second reduced diameter portion 50, and its projection height is 0.001 mm to 0.1 mm, with reference to the outer surface of the core wire 20 of the third constant outer diameter portion 43 of the intermediate core 22. The core wire 20 has a base-end recess 67 on the base end side of the third enlarged diameter portion 44 that is recessed radially inward from the third constant outer diameter portion 43 of the intermediate core 22 (area B in the figure). The tip side of the second reduced diameter portion 50 has a tip-end recess 68 that is recessed radially inward from the fourth constant outer diameter portion 51 of the tip core 23 (area C in the figure). The base-side recess 67 and the tip-side recess 68 are both greater than 0 mm from the core wire 20 and 0.05 mm or less, and their length in the longitudinal direction is greater than 0 mm and 2.2 mm or less. The tip joint 65 has a base-side recess 67 and a tip-side recess 68, which allows the stress on the tip joint surface 66 to be distributed when the vicinity of the base joint 60 is curved. As a result, the guide wire 10 has improved kink resistance at the tip joint 65. The tip joint 65 is defined as the area D in the figure, including the third enlarged diameter portion 44, the second reduced diameter portion 50, the base-side recess 67, and the tip-side recess 68. The length in the longitudinal direction of the tip joint 65 (area C in the figure) is 0.5 mm to 6.0 mm. Note that the tip joint 65 does not necessarily have a base-side recess 67 and a tip-side recess 68.

[0081] The tip joint 65, by including the tip projection 29, increases the area of ​​the tip joint surface 66 between the intermediate core 22 and the tip core 23, which is important in the tip joint 65 where the tensile strength of the core wire 20 tends to decrease compared to other areas, thereby improving the joint strength. As a result, the guide wire 10, at the tip portion inserted into the blood vessel, can have sufficient pushability and torque transmission to follow the curved blood vessel and pass through stenotic lesions.

[0082] An example of a guide wire 10 actually manufactured to have the dimensions described above is shown in Figures 13 and 14. In Figure 13, the area F is the fifth constant outer diameter portion 53 of the tip core 23, the area J is the portion of the tip core 23 covered by the tip coating layer 76, the area K is the portion of the tip core 23 covered by the cylindrical member 25 and the cylindrical fixing member 26, the area L is the exposed portion of the tip core 23, the area M is the tip protrusion 29, the area N is the exposed portion of the intermediate core 22, the area O is the portion of the intermediate core 22 from the tip covered by the intermediate coating layer 73 to the base end of the first reduced diameter portion 42, and the area P is the second constant outer diameter portion 41 of the intermediate core 22. In Figure 14, the area Q in the figure is the portion of the second constant outer diameter portion 41 of the intermediate core 22 that is covered by the overlapping portion 79, the area R in the figure is the portion of the second constant outer diameter portion 41 of the intermediate core 22 that is covered only by the base end coating layer 71, the area S in the figure is the base end joint portion 60, and the area T in the figure is the portion of the first constant outer diameter portion 30 of the base end core 21.

[0083] Next, the manufacturing process of the guide wire 10 will be described. As shown in Figure 15, when manufacturing the guide wire 10, a tip core 23 covered in a tip coating layer 76, an intermediate core 22 covered in an intermediate coating layer 73, and a base core 21 are prepared in advance. The tip coating layer 76 can be formed by covering the tip resin layer 77 and the tip lubrication layer 78, and arranging a cylindrical member 25 and a cylindrical fixing member 26 on the base end side of the tip coating layer 76. The intermediate coating layer 73 can be formed by covering the outer surface of the intermediate core 22 with an intermediate resin layer 74, and further arranging a linear body 75 on the outer surface of the intermediate resin layer 74. The intermediate coating layer 73 is not formed at the tip and base ends of the intermediate core 22.

[0084] Next, the intermediate core 22 and the tip core 23 are joined together. First, as shown in Figure 16(a), the tip of the intermediate core 22 and the base of the tip core 23 are abutted together. As mentioned above, the tip of the intermediate core 22 is not covered by the intermediate coating layer 73, so the intermediate core 22 can be abutted directly against the tip core 23. Next, as shown in Figure 16(b), the intermediate core 22 and the tip core 23 are solid-state joined at the tip joining surface 66, and at the same time, radially protruding portions are formed around the tip joining surface 66.

[0085] As shown in Figure 16(c), the protruding portion formed during joining is removed by polishing the area around the tip joint surface 66, leaving the tip projection 29. At this time, the aforementioned base-side recess 67 and tip-side recess 68 may be formed on the base-side and tip-side of the tip projection 29, respectively. This forms the tip joint 65 between the intermediate core 22 and the tip core 23. In this way, since the guide wire 10 directly joins the end faces of the intermediate core 22 and the tip core 23, the change in rigidity along the long axis near the tip joint 65 is gentler compared to joining via other members such as tubular members. As a result, stress concentration at the base joint 60 during bending in a blood vessel is suppressed, and kink resistance is improved. Furthermore, since the guide wire 10 can have a smooth outer surface without creating steps near the tip joint 65, the movement of the catheter inserted along the guide wire 10 can be made smoother.

[0086] Next, the base core 21 and the intermediate core 22 are joined. First, as shown in Figure 17(a), the tip of the base core 21 and the base end of the intermediate core 22 are abutted together. As mentioned above, the base end of the intermediate core 22 is not covered by the intermediate coating layer 73, so the intermediate core 22 can be abutted directly against the base core 21. Next, as shown in Figure 17(b), the base core 21 and the intermediate core 22 are solid-state joined at the base joint surface 61, and at the same time, radially protruding portions are formed around the base joint surface 61.

[0087] As shown in Figure 17(c), the base core 21 and the intermediate core 22 are joined by polishing the area around the base joint surface 61 to remove the protruding portion formed during joining, thereby forming a continuous tapered shape between the first enlarged diameter portion 31 of the base core 21 and the second enlarged diameter portion 40 of the intermediate core 22. At this time, the aforementioned base-side recess 62 and tip-side recess 63 are formed on the base end side of the first enlarged diameter portion 31 and on the tip side of the second enlarged diameter portion 40, respectively. This forms the base joint portion 60 between the base core 21 and the intermediate core 22. In this way, since the guide wire 10 directly joins the end faces of the base core 21 and the intermediate core 22, the change in rigidity along the long axis direction near the base joint portion 60 can be made gentler compared to when joining via other members such as tubular members. As a result, the guide wire 10 has improved kink resistance. Furthermore, it is easy to form the base joint portion 60 in a tapered shape. Furthermore, since the guidewire 10 can have a smooth outer surface without creating any steps near the proximal joint 60, the movement of the catheter inserted along the guidewire 10 can be made smoother.

[0088] The base joint portion 60 can also be polished to have a radially protruding portion such that the outer diameter of the base joint surface 61 is larger than the outer diameter of the base core 21 and the outer diameter of the intermediate core 22, resulting in the shape shown in Figure 9.

[0089] The method for solid-state bonding of the base joint 60 and the tip joint 65 is not particularly limited and includes, for example, friction bonding, room temperature pressure bonding, high-temperature pressure bonding, explosive bonding, and electromagnetic pulse bonding, but high-temperature pressure bonding is preferred. This allows the base joint 60 and the tip joint 65 to achieve higher bonding strength.

[0090] Next, a base end coating layer 71 is formed on the outer surface of the base end core 21. The base end coating layer 71 is formed by applying the material that forms the base end coating layer 71 (base end lubrication layer 72) onto the outer surface of the base end core 21 and heating and drying it. As shown in Figure 17(d), the material that forms the base end coating layer 71 is applied beyond the base end joint surface 61, which is the tip of the base end core 21, to the second enlarged diameter portion 40 of the intermediate core 22 and the base end of the intermediate coating layer 73. As a result, an overlapping portion 79 is formed on the coating layer 70 in the portion on the outer surface of the intermediate coating layer 73.

[0091] The guide wire 10 is completed when the base core 21, intermediate core 22, and tip core 23 are joined together, and the base coating layer 71 and overlapping portion 79 are formed.

[0092] The core wire 20 of the guide wire 10 is formed by joining a base core 21, an intermediate core 22, and a tip core 23. Therefore, by appropriately selecting and combining the materials that form the base core 21, intermediate core 22, and tip core 23, and the material that forms the coating layer 70, a guide wire 10 with desired physical properties and surface characteristics along the long axis can be easily manufactured. Furthermore, by processing the outer shape of the base joint 60 and tip joint 65 of the guide wire 10 to a desired shape, it is easy to adjust the change in stiffness along the long axis near the joint. Moreover, since the lengths of the base core 21, intermediate core 22, and tip core 23 can be shorter than when the core wire 20 is formed from a single continuous wire, the guide wire 10 can be manufactured in a small space even if the total length is long.

[0093] Next, the inclination angle of the base joint portion 60 and the outer diameter of the base joint surface 61 will be described. As shown in Figure 18, the base joint portion 60 can be formed such that its outer diameter monotonically increases from the base end side to the tip side of the core wire 20. In this case, the base joint portion 60 corresponds to the configuration shown in Figure 7, which has a base diameter expansion portion 27 that tapers in diameter from the base end side to the tip side of the core wire 20. Alternatively, the base joint portion 60' can be formed to have a base projection portion 28' whose outer diameter at the base joint surface 61' is larger than the outer diameters of the intermediate core 22 and the base core 21. Or, the base joint portion 60'' can be formed to have a base projection portion 28'' whose outer diameter at the base joint surface 61'' is even larger than the base projection portion 28'. In these cases, the base joint portion 60 corresponds to the configuration shown in Figure 9, which has a base projection portion 28 that protrudes radially outward. Thus, the presence or absence of the base end projection 28 and the outer diameter of the base end joint surface 61 can be adjusted by polishing after solid-phase bonding. Since the length in the longitudinal direction of the radially protruding portion shown in Figure 17(b) formed during solid-phase bonding is constant, as the outer diameter of the base end joint surface 61 of the base end joint 60 increases, the maximum inclination angle of the surface with respect to the longitudinal direction increases. In other words, as the outer diameter of the base end joint surface 61 of the base end joint 60 increases, the maximum inclination angle of the base end enlarged diameter portion (base end enlarged diameter portion 27 and first enlarged diameter portion 31) with respect to the longitudinal direction increases.

[0094] The samples used in the following evaluations and tests consisted of a nickel-titanium alloy for both the base core 21 and the intermediate core 22. The outer diameter of the base core 21 was 0.55 to 0.59 mm, and the outer diameter of the intermediate core was 0.75 to 0.77 mm.

[0095] Regarding the shape of the base joint 60, as shown in Figure 19, the distance between the center line of the sample and the outer surface was measured at 0.1 mm intervals along the long axis of the sample, and the difference ΔR between the center line and the outer surface at the measurement point adjacent to the tip side was calculated. The maximum value of the difference ΔR at the base joint 60 is defined as the inclination amount of the base joint 60. The angle of the base joint 60 changes continuously along the long axis, and by measuring the inclination amount, the angle of the base joint 60 at the steepest position with respect to the long axis can be calculated.

[0096] The relationship between the resistance felt by the proximal junction 60 of the catheter inserted from the proximal end of the guidewire 10 and the amount of inclination of the proximal junction 60 was evaluated. The evaluation was performed with the guidewire 10 inserted into the lumen 121 of the catheter 120, as shown in Figure 20. The inner diameter of the catheter 120 used in this evaluation was 1.0 mm. In this state, the catheter 120 was moved toward the tip, and the resistance felt by the evaluator's fingertip as the tip surface 120a of the catheter 120 passed through the proximal junction 60 of the guidewire 10 was evaluated. Three evaluators were used. The evaluation results are shown in Table 3. Each symbol indicates that the evaluator evaluated the catheter as being able to pass through with no resistance at all, "○" as being able to pass through smoothly with some resistance, and "△" as being able to pass through smoothly with some resistance.

[0097]

[0098] From the results in Table 3, it can be seen that if the inclination of the proximal joint 60 of the guidewire 10 is 0.040 mm or less, the catheter 120 can pass through the proximal joint 60 smoothly. An inclination of 0.040 mm of the proximal joint 60 corresponds to an inclination angle of 21.8° with respect to the long axis of the proximal joint 60. In other words, it is preferable that the maximum inclination angle of the proximal joint 60 with respect to the long axis of the guidewire 10 is 21.8° or less.

[0099] A tensile test was performed to investigate the joint strength of the base joint 60. The tensile test was conducted using an autograph with a distance of 150 mm between the two gripping chucks and a test speed of 10 mm / min. The guide wire 10 was fixed to the chucks so that the base joint 60 was positioned in the center of the two chucks, and the test was conducted until the sample broke.

[0100] The results of the tensile test are shown in Figure 21. Among the plotted points, the × marks represent the test results for a guide wire 10 having a base joint 60 that does not have a base projection 28 at the base joint 60, and whose outer diameter tapers (monotonically increases) from the base end side to the tip side of the core wire 20. Among the plotted points, the ○ marks represent the test results for a guide wire 10 having a base projection 28 at the base joint 60. As shown in this figure, when the outer diameter of the base joint surface 61 is less than 0.65 mm, the rate of change of tensile strength with respect to the outer diameter of the base joint surface 61 is large, whereas when the outer diameter of the base joint surface 61 is 0.65 mm or more, the rate of change of tensile strength with respect to the outer diameter of the base joint surface 61 is small. Thus, the guide wire 10 achieves stable joint strength at the base joint 60 by having an outer diameter of 0.65 mm or more at the base joint surface 61. Therefore, it is preferable that the base end joint surface 61 has an outer diameter of 0.65 mm or more, regardless of whether or not there is a base end projection 28.

[0101] Next, another shape of the base joint 60 will be described. As shown in Figure 22, the base joint 90 that joins the base core 21 and the intermediate core 22 expands in diameter from the base end side to the tip side of the core wire 20. The surface of the base joint 90 has a curved shape that is convex radially outward in the longitudinal cross-section of the guide wire 10. In this case, the area of ​​the base joint surface 91 is larger than that of the base joint surface 61 of the base joint 60 which has a linear shape in the longitudinal cross-section of the guide wire 10, so the joint strength between the base core 21 and the intermediate core 22 can be increased.

[0102] As described above, the (1) guide wire 10 according to this embodiment is a guide wire 10 comprising a long core wire 20, the core wire 20 comprising a first core 21 (base end core 21) and a second core 22 (intermediate core 22) joined to the tip side of the first core 21, the outer diameter of the first core 21 extending from the base end to the base end side of the joint portion 60 (base end joint portion 60) between the first core 21 and the second core 22 is smaller than the outer diameter of the second core 22 extending from the tip side to the tip side of the joint portion 60, and the outer diameter of the joint surface 61 (base end joint surface 61) between the first core 21 and the second core 22 is larger than the outer diameters of the base end and tip of the joint portion 60. The guide wire 10 configured in this way (1) allows for a larger area of ​​the joint surface 61 at the joint 60 between the first core 21 and the second core 22, where the tensile strength of the core wire 20 tends to decrease compared to other regions. As a result, the joint strength between the first core 21 and the second core 22, which have different outer diameters, is improved.

[0103] (2) In the guide wire 10 described in (1) above, the outer diameter of the first core 21 may be 70% to 80% of the outer diameter of the second core 22. This allows the catheter to be inserted smoothly without bending of the first core 22, even when a pushing force is applied when inserting the catheter from the proximal end of the guide wire 10.

[0104] (3) In the guide wire 10 of (1) or (2) above, the joining surface may be located towards the tip of the joint 60 from the center in the longitudinal direction. This allows the guide wire 10 to have a larger area of ​​the joining surface 61, thereby further improving the joining strength between the first core 21 and the second core 22 at the joint 60.

[0105] (4) In any of the guide wires 10 described in (1) to (3) above, the joint portion 60 may be covered with a first coating layer 71 (proximal coating layer 71) that covers the first core 21. As a result, the guide wire 10 is continuously covered with the first coating layer 71 from the first core 21 to the proximal end of the second core 22, so that the core wire 20 is not exposed in the region from the proximal end to the middle portion of the core wire 20, thereby suppressing an increase in the insertion resistance of a catheter inserted from the proximal end.

[0106] (5) In any of the guide wires 10 described in (1) to (4) above, the first core 21 and the second core 22 may be made of a nickel-titanium alloy. This allows the guide wire 10 to have the appropriate flexibility and resilience to bending necessary when passing through a blood vessel with a large curve.

[0107] The method for manufacturing the guide wire 10 according to this embodiment (6) is a method for manufacturing the guide wire 10 which includes a long core wire 20 having a joint portion 60 that joins a first core 21 (base end core 21) and a second core 22 (intermediate core 22) arranged on the tip side of the first core 21, and includes the steps of: preparing a first core 21 and a second core 22 having a larger outer diameter than the first core 21; solid-state bonding the tip of the first core 21 and the base end of the second core 22; and polishing a region including the joint surface 61 (base end joint surface 61) between the first core 21 and the second core 22 formed by solid-state bonding to form a joint portion 60 (base end joint portion 60) in which the outer diameter of the joint surface 61 is larger than the outer diameters of the base end and tip of the joint portion 60. The method for manufacturing the guide wire 10 described in (6) above directly joins the first core 21, which has a smaller outer diameter, and the second core 22, which has a larger outer diameter, by solid-state bonding. This makes it easy to form a smooth, step-free tapered shape at the joint 60 between the first core 21 and the second core 22. Furthermore, the method for manufacturing the guide wire 10 allows for a larger joint surface area at the joint 60 between the base core 21 and the intermediate core 22, where the tensile strength of the core wire 20 tends to decrease compared to other regions. This makes it possible to manufacture a guide wire 10 with improved joint strength between the base core 21 and the intermediate core 22, which have different outer diameters.

[0108] (7) In the method for manufacturing the guidewire 10 described in (6) above, the first core 21 and the second core 22 may be made of a nickel-titanium alloy. This makes it possible to manufacture a guidewire 10 that has the appropriate flexibility and resilience to bending required when passing through greatly curved blood vessels.

[0109] (8) In any of the guide wires 10 described in (1) to (5) above, the joint portion 60 has a maximum inclination angle of 21.8° or less with respect to the long axis of the core wire 20, and the joint surface 61 may have an outer diameter of 0.65 mm or more. This allows the guide wire 10 to have stable joint strength while suppressing snagging during device insertion.

[0110] When two cores are connected by a tubular member, a step is created on the outer surface at the end of the tubular member, which can cause the tip of the catheter, inserted from the proximal end of the guidewire, to get caught and break the catheter.

[0111] Furthermore, the region near the joint of a core wire formed by joining two cores tends to have lower tensile strength compared to the tip and base regions of the joint due to the heat and deformation applied during the joining process. If the joint strength is insufficient, the guide wire may kink or break at the joint when subjected to a large load such as bending. For this reason, it is necessary to ensure sufficient joint strength at the core joint of the guide wire.

[0112] The present invention provides a guidewire that allows for smooth insertion of a catheter from the proximal end to the distal end and has sufficiently high bonding strength at the core joint, and therefore employs the following solutions.

[0113] (9) The guide wire 10 is a guide wire 10 that includes a long core wire 20, the core wire 20 includes a base core 21, an intermediate core 22 joined to the tip side of the base core 21, and a tip core 23 joined to the tip of the intermediate core 22, the base joint portion 60 that joins the base core 21 and the intermediate core 22 includes an enlarged diameter portion 27 (base enlarged diameter portion 27) that tapers in diameter from the base side to the tip side of the core wire 20, and the tip joint portion 65 that joins the intermediate core 22 and the tip core 23 includes a protruding portion 28 (tip protruding portion 28) that protrudes radially outward. In the guide wire 10 configured in this way (9), since the base joint portion 60 that joins the base core 21 and the intermediate core 22, which have different outer diameters, includes an enlarged diameter portion 27 (base enlarged diameter portion 27), it is possible to create no steps on the outer surface and to make the change in rigidity along the long axis direction gradual. Furthermore, because the tip joint 65 of the guide wire 10, where the intermediate core 22 and the tip core 23 meet, includes a protruding portion 28, the area of ​​the tip joint surface 66 can be increased at the tip joint 65 between the intermediate core 22 and the tip core 23, where the tensile strength of the core wire 20 tends to decrease compared to other areas, thus improving the joint strength. As a result, the guide wire 10 allows for smooth insertion of the catheter from the proximal end to the tip end, and sufficient joint strength between the cores can be ensured.

[0114] (10) In the guide wire 10 described in (9) above, the outer diameter of the proximal core 21 extending from the proximal end of the proximal joint 60 toward the proximal end may be smaller than the outer diameter of the intermediate core 22 extending from the tip of the proximal joint 60 toward the tip. This allows the guide wire 10 to have a larger clearance between the outer surface of the guide wire 10 and the inner surface of the catheter at the portion of the proximal core 21, thereby reducing the frictional resistance between the guide wire and the catheter. Furthermore, by making the outer diameter of the proximal core 21 smaller than the outer diameter of the intermediate core 22, the rigidity of the proximal end of the guide wire that is outside the body during the procedure can be reduced, so that the proximal end can be easily held in a bundled state after being temporarily wrapped around multiple times.

[0115] (11) In the guide wire 10 described in (10) above, the outer diameter of the proximal core 21 may be 70% to 80% of the outer diameter of the intermediate core 22. This allows the catheter to be inserted smoothly without bending of the first core 21, even when a pushing force is applied when inserting the catheter from the proximal end of the guide wire 10.

[0116] (12) In any of the guide wires 10 described in (9) to (11) above, the outer diameter of the proximal end and the outer diameter of the tip of the tip joint 65 may be approximately equal. This prevents the guide wire 10 from undergoing a sudden change in rigidity along the longitudinal axis near the tip joint 65, thereby suppressing stress concentration at the tip joint 65 in curved sections within blood vessels and improving kink resistance.

[0117] (13) In any of the guidewires 10 described in (9) to (12) above, the length of the proximal core 21 may be 50% or less of the total length of the core wire 20. This allows the guidewire 10 to maintain catheter insertability while ensuring sufficient length on the proximal side of the catheter for catheter removal. Furthermore, since the guidewire 10 can ensure sufficient length of the intermediate core 22 and the tip core 23, which are larger in outer diameter than the proximal core 21, it can be equipped with various performance characteristics necessary for a guidewire 10, such as vascular selectivity, passability in stenotic areas, pushability, and torque transmission.

[0118] (14) In any of the guide wires 10 described in (9) to (13) above, the proximal core 21, intermediate core 22, and tip core 23 may be made of a nickel-titanium alloy. This allows the guide wire 10 to have the appropriate flexibility and resilience to bending necessary when passing through greatly curved blood vessels.

[0119] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical framework of the present invention.

[0120] This application is based on Japanese Patent Application Nos. 2025-56108 and 2025-56109, filed on March 28, 2025, and Japanese Patent Application No. 2025-151112, filed on September 11, 2025, and the disclosures therein are referenced and incorporated as a whole.

[0121] 10 Guide wire 20 Core wire 21 Base core 22 Intermediate core 23 Tip core 25 Cylindrical member 27 Base diameter enlarged section 28 Base projection 29 Tip projection 30 First constant outer diameter section 31 First diameter enlarged section 40 Second diameter enlarged section 41 Second constant outer diameter section 42 First reduced diameter section 43 Third constant outer diameter section 44 Third diameter enlarged section 46 Fourth reduced diameter section 50 Second reduced diameter section 51 Fourth constant outer diameter section 52 Third reduced diameter section 53 Fifth constant outer diameter section 60 Base joint section 61 Base joint surface 65 Tip joint section 66 Tip joint surface 69 Exposed section 70 Coating layer 71 Base coating layer 72 Base lubrication layer 73 Intermediate coating layer 74 Intermediate resin layer 75 Linear body 76 Tip coating layer 77 Tip resin layer 78 Tip lubrication layer 79 Overlapping portion 90 Base end joint portion

Claims

1. A guide wire having a long core wire, wherein the core wire comprises a first core and a second core joined to the tip side of the first core, the outer diameter of the first core extending from the base end to the base end side of the joint between the first core and the second core is smaller than the outer diameter of the second core extending from the tip end to the tip side of the joint, and the outer diameter of the joint surface between the first core and the second core is larger than the outer diameters of the base end and tip end of the joint.

2. The guide wire according to claim 1, wherein the outer diameter of the first core is 70% to 80% of the outer diameter of the second core.

3. The guide wire according to claim 1 or 2, wherein the joining surface is located on the tip side of the central position in the longitudinal direction of the joining portion.

4. The guide wire according to claim 1 or 2, wherein the joint portion is covered by a first coating layer that covers the first core.

5. The guide wire according to claim 1 or 2, wherein the first core and the second core are formed of a nickel-titanium alloy.

6. A method for manufacturing a guide wire, comprising a long core wire having a joint portion that joins a first core and a second core disposed on the tip side of the first core, the method comprising: a step of preparing the first core and the second core having a larger outer diameter than the first core; a step of solid-state bonding the tip of the first core and the base end of the second core; and a step of polishing a region including the joint surface of the first core and the second core formed by the solid-state bonding to form the joint portion in which the outer diameter of the joint surface is larger than the outer diameters of the base end and tip of the joint portion.

7. The method for manufacturing a guide wire according to claim 6, wherein the first core and the second core are formed of a nickel-titanium alloy.

8. The guide wire according to claim 1 or 2, wherein the joint portion has a maximum inclination angle of 21.8° or less with respect to the long axis direction of the core wire, and the joint surface has an outer diameter of 0.65 mm or more.

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