Guide wire

Abstract

To suppress a rigidity gap between a first shaft and a second shaft while improving rotation followability of the first shaft to the second shaft.SOLUTION: A guide wire includes a core shaft, and the core shaft includes a first shaft of a stainless steel alloy on a distal end side of the core shaft and a second shaft which has a distal end part where a proximal end part of the first shaft is joined and has super-elasticity. The second shaft has a tapered part where an outer diameter increases to a proximal end side from a distal end side, and on an outer peripheral surface of the tapered part, a step part having a positioning surface extending in an axial direction of the core shaft is formed. The proximal end part of the first shaft is joined along the positioning surface of the second shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The technology disclosed in this specification relates to a medical guide wire.

Background Art

[0002] As a method for treating or examining a stenosis or occlusion (hereinafter referred to as "lesion") in a blood vessel or the like, a method using a catheter is widely used. Generally, a guide wire is used to guide a catheter to a lesion in a blood vessel or the like. The guide wire includes, for example, a core shaft formed of a metal material.

[0003] The core shaft has a ribbon made of a stainless alloy and a core made of a nickel-titanium alloy, and the base end portion of the ribbon and the tip end portion of the core are joined. In a first specific form, the outer peripheral surface of the base end portion of the ribbon and the outer peripheral surface of the tip end portion of the core are joined in a state of facing each other (see, for example, Patent Documents 1 and 2). In a second specific form, the tip end portion of the core is formed in a cylindrical shape having the same diameter over the entire length, and a flat surface is formed by performing a semi-circular machining on the tip end portion. On the other hand, a flat surface is also formed by performing a semi-circular machining on the ribbon. The flat surfaces of the core and the ribbon are joined (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0006] Furthermore, these challenges are not limited to core shafts in which a stainless steel alloy ribbon and a nickel-titanium alloy core are joined, but are common to guide wires equipped with a core shaft in which a first stainless steel alloy shaft and a second shaft having superelastic properties are joined.

[0007] This specification discloses a technology capable of solving the above-mentioned problems. [Means for solving the problem]

[0008] The technologies disclosed herein can be implemented, for example, in the following forms:

[0009] (1) A guide wire disclosed herein is a guide wire comprising a core shaft, the core shaft comprising a first shaft made of a stainless alloy located on the tip side of the core shaft, and a second shaft having a tip portion to which the base end of the first shaft is joined and which has superelastic properties, the second shaft having a tapered portion whose outer diameter increases from the tip side to the base end side, a stepped portion having a positioning surface extending in the axial direction of the core shaft formed on the outer circumferential surface of the tapered portion, and the base end of the first shaft is joined along the positioning surface of the second shaft.

[0010] In this guidewire, a stepped portion is formed on the outer circumferential surface of the tapered portion of the second shaft, having a positioning surface that extends in the axial direction of the core shaft. The base end of the first shaft is joined along the positioning surface of the second shaft. Therefore, compared to a configuration in which the base end of the first shaft is simply joined to the outer circumferential surface of the tapered portion of the second shaft, the rotational tracking ability of the first shaft relative to the second shaft is improved because the axis of the first shaft is closer to the axis of the second shaft. Moreover, in this guidewire, the stepped portion is formed on the outer circumferential surface of the tapered portion of the second shaft. Therefore, the rigidity of the second shaft near the base end of the stepped portion of the tapered section is higher than the rigidity of the second shaft near the tip of the stepped portion of the tapered section. Therefore, even if a gap occurs between the base end surface of the first shaft and the stepped portion, the decrease in rigidity of the second shaft caused by that gap can be compensated for by the rigidity of the second shaft near the base end of the stepped portion. As described above, this guide wire improves the rotational tracking ability of the first shaft relative to the second shaft while suppressing the rigidity gap between the first and second shafts.

[0011] (2) In the guide wire described above, the first shaft may have a flat opposing surface along the axial direction of the first shaft, and the positioning surface of the second shaft may be a flat surface, and the opposing surface of the first shaft may be joined to the positioning surface of the second shaft. With this guide wire, for example, compared to a configuration in which the curved surfaces of the first shaft and the second shaft are joined together, the joint strength (tensile strength) between the first shaft and the second shaft can be improved by the larger joint area between the first shaft and the second shaft.

[0012] (3) In the above guide wire, the axis of the second shaft may be configured to be on the same plane as the positioning surface. With this guide wire, for example, compared to a configuration in which the positioning surface does not reach the axis of the second shaft, the rotational tracking ability of the first shaft relative to the second shaft can be effectively improved by the fact that the axis of the first shaft is closer to the axis of the second shaft.

[0013] Furthermore, the technologies disclosed herein can be implemented in various forms, for example, in the form of guide wires and methods for manufacturing them. [Brief explanation of the drawing]

[0014] [Figure 1] A schematic side view showing the overall configuration of the guide wire in the embodiment. [Figure 2] This figure shows the cross-sectional configuration of the joint between the first shaft 11 and the second shaft 12. [Figure 3] This diagram shows the configuration of the joint between the guide wire 100 according to this embodiment and the guide wires 100a and 100b according to Comparative Examples 1 and 2. [Figure 4] Explanatory diagram showing performance evaluation by tensile strength test. [Modes for carrying out the invention]

[0015] A. Embodiments: A-1. Configuration of guide wire 100: Figure 1 is a schematic side view showing the overall configuration of the guidewire 100 in this embodiment. Figure 1 shows mutually orthogonal XYZ axes for determining direction, and shows the overall configuration of the guidewire 100 when viewed in the positive X-axis direction. In Figure 1, the positive Z-axis side is the tip side (distal side) that is inserted into the body, and the negative Z-axis side is the proximal end (proximal side) that is manipulated by a surgeon such as a physician. These points are the same for Figures 2 and onward.

[0016] In FIG. 1, regarding the coil body 20 described later, a cross-sectional (specifically, YZ cross-sectional) configuration is shown. In FIG. 1, the guide wire 100 is shown in a state where it is generally in a straight line substantially parallel to the Z-axis direction as a whole, but the guide wire 100 has flexibility such that it can be curved. In the following, for the guide wire 100 and each component member of the guide wire 100, a portion including the tip and extending halfway from the tip toward the proximal end side is referred to as the "tip portion". Similarly, for the guide wire 100 and each component member of the guide wire 100, a portion including the proximal end and extending halfway from the proximal end toward the tip side is referred to as the "proximal end portion".

[0017] The guide wire 100 is a medical device inserted into a blood vessel or the like, for example, to guide a catheter (not shown) to a lesion (stenosis or occlusion) in a blood vessel or the like. As shown in FIG. 1, the guide wire 100 includes a core shaft 10, a coil body 20, a tip-side joint portion 30, and a proximal end-side joint portion 40. In this embodiment, the axial direction of the core shaft 10 coincides with the axial direction of the guide wire 100.

[0018] The core shaft 10 is a rod-shaped member with a thin diameter on the tip side and a thick diameter on the proximal end side. The core shaft 10 includes a first shaft 11 including the tip of the core shaft 10 and a second shaft 12 located on the proximal end side of the core shaft 10 with respect to the first shaft 11. The proximal end portion of the first shaft 11 and the tip portion of the second shaft 12 are joined by a joint portion 15 (see the X1 portion described later in FIG. 1). The joint portion 15 is formed of, for example, a metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, or an adhesive such as an epoxy-based adhesive.

[0019] The first shaft 11 is a rod-shaped member. In the present embodiment, the first shaft 11 is formed of a material including stainless steel (such as SUS302, SUS304, SUS316, etc.). The first shaft 11 may be called a "ribbon" or a "shaping ribbon". Incidentally, the maximum width (outer diameter) of the proximal end of the first shaft 11 is, for example, 40 μm or more and 60 μm or less. The shape of the first shaft 11 will be described later.

[0020] The second shaft 12 has a straight portion 120 and a tapered portion 122. In FIG. 1, part of the straight portion 120 is not shown.

[0021] The straight portion 120 of the second shaft 12 is a portion including the proximal end of the second shaft 12. The straight portion 120 is a portion of a round bar with substantially the same outer diameter over the entire length. The straight portion 120 has a rod shape with a circular cross section.

[0022] The tapered portion 122 of the second shaft 12 is located on the tip side with respect to the straight portion 120. The outer diameter of the tapered portion 122 gradually increases from the tip of the second shaft 12 toward the boundary position with the straight portion 120.

[0023] Incidentally, the shape of the cross section of each part of the second shaft 12 is not particularly limited, and may be, for example, a polygon such as a triangle or a quadrilateral. The cross section is a cross section (in the present embodiment, the XY cross section) orthogonal to the axial direction of the core shaft 10 (in the present embodiment, the Z-axis direction). In the present invention, the tapered portion 122 is the foremost end of the second shaft 12, and the foremost end portion of the tapered portion 122 is formed in a planar shape, but the shape of the foremost end portion of the tapered portion 122 is not particularly limited. That is, for example, the foremost end portion may have a needle-like pointed shape.

[0024] The second shaft 12 is formed from a material including an alloy having superelastic properties (for example, a Ni-Ti alloy). In this embodiment, the configuration includes a second shaft 12 made of a material including a superelastic alloy, which allows the deformed shape of the second shaft 12 to return to its original shape (sometimes called "restorability") even when the guidewire 100 is advanced through a curved blood vessel, thereby ensuring the operability and blood vessel selectivity of the guidewire 100. The maximum width (outer diameter) of the tip of the second shaft 12 (tapered portion 122) is, for example, 50 μm or more and 70 μm or less. The difference between the outer diameter of the tip and the outer diameter of the base of the tapered portion 122 is, for example, 5 μm or more and 10 μm or less.

[0025] The coil body 20 is a coil-shaped member formed into a hollow cylindrical shape by spirally winding a single wire. The coil body 20 is arranged to surround the outer circumference of the tip of the core shaft 10 (specifically, the first shaft 11 and part of the tapered portion 122 and straight portion 120 of the second shaft 12).

[0026] The coil body 20 is made of, for example, a metallic material, more specifically, a radiopaque alloy such as stainless steel (SUS302, SUS304, SUS316, etc.), piano wire, nickel-chromium alloy, or cobalt alloy, or a radiopaque alloy such as gold, platinum, tungsten, or alloys containing these elements (e.g., platinum-nickel alloy). If at least a portion of the coil body 20 is made of a radiopaque material, the operator can determine the position of the coil body 20 under radiographic imaging.

[0027] The tip-side joint 30 connects the tip of the core shaft 10 to the tip of the coil body 20. The tips of the core shaft 10 and the coil body 20 are fixed to the inside of the tip-side joint 30 so as to be embedded within it. The outer peripheral surface of the tip-side joint 30 is a smooth surface (for example, a substantially hemispherical surface). The tip-side joint 30 is made of a metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, or an adhesive such as an epoxy adhesive. By positioning the tip-side joint 30 on the tip side of the core shaft 10, the core shaft 10 is prevented from coming into contact with the blood vessel wall or the like, thereby suppressing damage to the core shaft 10.

[0028] The base-side joint 40 is a member that connects the base end of the core shaft 10 to the base end of the coil body 20. The base-side joint 40 is made of the same material as the tip-side joint 30 described above. Note that the base-side joint 40 is not limited to the base end of the coil body 20, but may be positioned at any position on the coil body 20.

[0029] A-2. Detailed configuration of the joint between the first shaft 11 and the second shaft 12: Figure 1 shows an enlarged view of the joint portion (X1 portion) between the first shaft 11 and the second shaft 12 in a view in the positive X-axis direction. Figure 2 shows the cross-sectional configuration of the joint portion between the first shaft 11 and the second shaft 12. Figure 2(A) shows the cross-sectional configuration of the joint portion at position IIA-IIA in Figure 1, and Figure 2(B) shows the cross-sectional configuration of the joint portion at position IIB-IIB in Figure 1.

[0030] As shown in Figures 1 and 2, the first shaft 11 is a round bar member with a substantially circular cross-section and a substantially uniform outer diameter along its entire length. Specifically, as shown in Figure 2, the outer circumferential surface of the first shaft 11 has a pair of first outer circumferential surfaces 11A, 11A and a pair of second outer circumferential surfaces 11B, 11B. The pair of first outer circumferential surfaces 11A, 11A are positioned symmetrically with respect to the central axis Q of the first shaft 11. Each first outer circumferential surface 11A is an arc curved surface along the circumscribed circle M centered on the central axis Q of the first shaft 11. The pair of second outer circumferential surfaces 11B, 11B are positioned symmetrically with respect to the central axis Q of the first shaft 11 in a direction (Y-axis direction) perpendicular to the opposing direction (X-axis direction) of the pair of first outer circumferential surfaces 11A, 11A. Each second outer circumferential surface 11B is flatter than the first outer circumferential surface 11A. Specifically, each second outer surface 11B is a substantially flat surface, substantially parallel to the central axis Q of the first shaft 11, and extends along the entire length of the first shaft 11.

[0031] A stepped portion 125 is formed on the outer circumferential surface of the tip of the tapered portion 122 of the second shaft 12. The stepped portion 125 is a recessed portion on the side of the central axis O of the second shaft 12 (core shaft 10) relative to the outer circumferential surface 122A of the tapered portion 122. The stepped portion 125 extends from the tip of the tapered portion 122 (second shaft 12) to partway along the tapered portion 122 in the direction along the central axis O of the second shaft 12 (Z-axis direction).

[0032] Specifically, the stepped portion 125 has a positioning surface 125A and a stepped surface 125B (see Figure 1). The positioning surface 125A is a surface that extends in the direction along the central axis O of the second shaft 12 (Z-axis direction). The positioning surface 125A extends from the tip of the tapered portion 122 (second shaft 12) to partway along the tapered portion 122 in the direction along the central axis O of the second shaft 12 (Z-axis direction). The positioning surface 125A is a surface that is more parallel to the central axis O of the second shaft 12 than the outer circumferential surface 122A of the tapered portion 122 (a surface with a gentler inclination angle). In addition, the positioning surface 125A is a surface that is flatter than the outer circumferential surface 122A of the tapered portion 122. In this embodiment, the positioning surface 125A is a surface that is substantially parallel to the central axis O of the second shaft 12 and is substantially flat.

[0033] Furthermore, as shown in Figure 2, when viewed in the direction along the central axis O of the second shaft 12 (Z-axis direction), the positioning surface 125A is located on the central axis O (axis) of the second shaft 12. That is, the cross-sectional shape of the tip of the tapered portion 122 is approximately semicircular. Note that, for example, the stepped portion 125 can be formed by laser processing the tapered portion 122.

[0034] One of the second outer peripheral surfaces 11B of the first shaft 11 is joined to the positioning surface 125A of the tapered portion 122 of the second shaft 12. This one of the second outer peripheral surfaces 11B is an example of an opposing surface in the claims. The gap between the first outer peripheral surface 11A of the first shaft 11 and the stepped portion 125 of the second shaft 12 is filled with a joint 15 (see portion X1 in Figure 1 and Figure 2).

[0035] In a view along the central axis O of the second shaft 12 (in the Z-axis direction), at the joint between the first shaft 11 and the second shaft 12, the central axis Q of the first shaft 11 is located on the inner side of the circumscribed circle M of the tapered portion 122 of the second shaft 12. Therefore, compared to a configuration where, for example, the central axis Q of the first shaft 11 is located on the outer side of the circumscribed circle M, the rotational tracking ability of the first shaft 11 relative to the second shaft 12 is improved by the fact that the central axis Q of the first shaft 11 is closer to the central axis O of the second shaft 12.

[0036] When viewed in the direction along the central axis O of the second shaft 12 (Z-axis direction), more than 90% of the first shaft 11 is positioned on the inner circumference side of the circumscribed circle M at the joint between the first shaft 11 and the second shaft 12. As a result, the rotational tracking ability of the first shaft 11 relative to the second shaft 12 is improved, to the extent that the cross-sectional shapes of the first shaft 11 and the second shaft 12 become closer to a perfect circle.

[0037] In a view along the central axis O of the second shaft 12 (in the Z-axis direction), the cross-section of the first shaft 11 is symmetrical with respect to the central axis Q. Therefore, compared to a configuration in which the cross-section of the first shaft 11 is asymmetrical with respect to the central axis Q, the rotational tracking ability of the first shaft 11 relative to the second shaft 12 is improved due to the greater degree of freedom in the deformation direction of the first shaft 11.

[0038] A-3. Effects of this embodiment: As described above, in the guide wire 100 according to this embodiment, a stepped portion 125 is formed on the outer circumferential surface of the tapered portion 122 of the second shaft 12, having a positioning surface 125A that extends in a direction along the central axis O of the core shaft 10 (see Figures 1 and 2). The base end of the first shaft 11 is joined along the positioning surface 125A of the second shaft 12. Therefore, compared to a configuration in which the base end of the first shaft 11 is simply joined to the outer circumferential surface of the tapered portion 122 of the second shaft 12, the rotational tracking ability of the first shaft 11 relative to the second shaft 12 is improved by the amount that the central axis Q of the first shaft 11 is closer to the central axis Q of the second shaft 12. Moreover, in this embodiment, the stepped portion 125 is formed on the outer circumferential surface of the tapered portion 122 of the second shaft 12. Therefore, the rigidity of the second shaft 12 near the base end of the stepped portion 125 of the tapered portion 122 is higher than the rigidity of the second shaft 12 near the tip of the stepped portion 125 of the tapered portion 122. Therefore, even if a gap S occurs between the base end surface of the first shaft 11 and the stepped portion 125 (stepped surface 125B), the decrease in rigidity of the second shaft 12 caused by the gap S can be compensated for by the rigidity of the second shaft 12 near the base end of the stepped portion 125. As described above, according to this embodiment, it is possible to improve the rotational tracking ability of the first shaft 11 relative to the second shaft 12 while suppressing the rigidity gap between the first shaft 11 and the second shaft 12.

[0039] Figure 3 is an explanatory diagram showing the configuration of the joint portion between the guide wire 100 according to this embodiment and the guide wires 100a and 100b according to Comparative Examples 1 and 2. The guide wire 100a of Comparative Example 1 differs from the guide wire 100 according to this embodiment in that the second shaft 12a does not have a tapered portion and a stepped portion, and the first shaft 11 is joined to the arc-shaped outer surface 125Aa of the second shaft 12a. The guide wire 100b of Comparative Example 2 differs from the guide wire 100 according to this embodiment in that the second shaft 12b does not have a tapered portion, a stepped portion 125b is formed on the straight portion of the second shaft 12b, and the first shaft 11 is joined along the positioning surface 125Ab of the stepped portion 125b. Note that the length L of the joint portion is the same for all of the guide wires 100, 100a, and 100b.

[0040] Figure 4 is an explanatory diagram showing performance evaluation by tensile strength testing. Figure 4 shows graphs showing the results of tensile strength tests performed on each sample of guide wire 100 and guide wire 100b under the same conditions. The horizontal axis of the graph is the displacement at which the sample breaks (displacement of the sample length from the beginning of the test (mm)), and the vertical axis is the tensile load (N) applied to the first shaft and the second shaft in the sample. Graph G1 shows the results for guide wire 100, and graph G1b shows the results for guide wire 100b. According to Figure 4, it can be seen that the tensile strength of guide wire 100 is approximately 1.5 times higher than that of guide wire 100b. As shown in Figures 3(A) and 3(C), a gap S may occur between the first shaft and the stepped portion in both guide wire 100 and guide wire 100b. However, the thickness D2 near the base end of the stepped portion 125 in the guide wire 100 is greater than the thickness D2b near the base end of the stepped portion 125b in the guide wire 100b. Therefore, it is considered that the tensile strength of the guide wire 100 is improved compared to the guide wire 100b.

[0041] Rotational performance tests were conducted on both guidewire 100 and guidewire 100a under identical conditions. The results showed that guidewire 100 exhibited improved rotational performance (rotational tracking ability) compared to guidewire 100a. As shown in Figures 3(A) and 3(B), the distance ΔY1 between the central axis Q of the first shaft 11 and the central axis O of the second shaft 12 in guidewire 100 is shorter than the distance ΔY1a between the central axis Q of the first shaft 11 and the central axis Oa of the second shaft 12a in guidewire 100a. Therefore, it is considered that guidewire 100 exhibited improved rotational performance compared to guidewire 100b.

[0042] Stiffness measurements were performed on samples using both guidewire 100 and guidewire 100a. The results showed that in guidewire 100, the stiffness increased continuously with distance from the tip of the sample. On the other hand, in guidewire 100a, the stiffness decreased midway through the distance from the tip of the sample, indicating the existence of a stiffness gap. In guidewire 100, the first shaft 11 is joined to the stepped portion 125 of the second shaft 12. Therefore, the thickness gap ΔY2 between the first shaft 11 and the joint portion between the first shaft 11 and the second shaft 12 is smaller than the thickness gap ΔY2a between the first shaft 11 and the joint portion between the first shaft 11 and the second shaft 12a in guidewire 100a. For this reason, it is considered that the stiffness gap is suppressed in guidewire 100 compared to guidewire 100b.

[0043] In this embodiment, the flat surfaces of the first shaft 11 and the second shaft 12 are joined together. Therefore, according to this embodiment, compared to a configuration in which the curved surfaces of the first shaft 11 and the second shaft 12 are joined together, the joint strength (tensile strength) between the first shaft 11 and the second shaft 12 can be improved by the larger joint area between the first shaft 11 and the second shaft 12.

[0044] In this embodiment, the central axis O of the second shaft is located on the same plane as the positioning surface 125A. Therefore, according to this embodiment, compared to a configuration in which, for example, the positioning surface 125A does not reach the central axis O of the second shaft 12, the rotational tracking ability of the first shaft 11 relative to the second shaft 12 can be effectively improved by the fact that the central axis Q of the first shaft 11 is closer to the central axis O of the second shaft 12.

[0045] B. Variations: The technologies disclosed herein are not limited to the embodiments described above and can be modified in various forms without departing from their essence, for example, the following modifications are possible.

[0046] The configuration of the guide wire 100 in the above embodiment is merely an example and can be modified in various ways. In the above embodiment, the first shaft 11 may have a tapered shape in which the outer diameter gradually increases from the tip to the base. In the cross-sectional shape of the first shaft 11, one of the pair of second outer surfaces 11B, 11B may not be a flat surface but an arc surface similar to the first outer surface 11A. The cross-sectional shape of the first shaft 11 is not particularly limited and may be, for example, circular, elliptical, triangular, or quadrilateral polygon.

[0047] The second shaft 12 may be configured such that, for example, a portion with substantially the same outer diameter along its entire length is provided at the tip of the tapered portion 122. The shape of the cross-section of the second shaft 12 is not particularly limited and may be, for example, an ellipse, a triangle, a quadrilateral, or other polygon. The stepped portion 125 may be formed, for example, between the tip and base end of the tapered portion 122, or it may be formed from the middle of the tapered portion 122 to the base end. The positioning surface 125A may also be inclined with respect to the central axis O of the second shaft 12. For example, the positioning surface 125A may be inclined to approach the central axis O of the second shaft 12 as it approaches the tip, or it may be inclined to move away from the central axis O of the second shaft 12 as it approaches the tip. Furthermore, when viewed in the direction along the central axis O of the second shaft 12, the positioning surface 125A may be offset with respect to the central axis O (axis) of the second shaft 12. The positioning surface 125A is not limited to a flat surface; it may also be a U-shaped or V-shaped groove, for example.

[0048] In the above embodiment, the guide wire 100 does not necessarily have to include at least one of the coil body 20, the tip-side joint 30, and the base-side joint 40.

[0049] The materials of each component constituting the guide wire 100 in the above embodiment are merely examples and can be modified in various ways. Furthermore, the manufacturing method of the guide wire 100 in the above embodiment is merely an example and can be manufactured by other methods. [Explanation of Symbols]

[0050] 10: Core shaft 11: First shaft 11A: First outer surface 11B: Second outer surface 12,12a,12b: Second shaft 15: Joint 20: Coil body 30: Tip-side joint 40: Base-side joint 100,100a,100b: Guide wire 120: Straight section 122: Tapered section 122A,125Aa: Outer surface 125: Stepped section 125A,125Ab: Positioning surface 125B: Stepped surface 125b: Stepped section

Claims

1. A guide wire having a core shaft, The core shaft comprises a first shaft made of stainless steel alloy located at the tip of the core shaft, and a second shaft having a tip portion to which the base end of the first shaft is joined, and which has superelastic properties. The second shaft has a tapered section in which the outer diameter increases from the tip end to the base end, A stepped portion is formed on the outer circumferential surface of the tapered portion, having a positioning surface that extends in the axial direction of the core shaft. The base end of the first shaft is joined along the positioning surface of the second shaft, The positioning surface extends from the tip of the tapered portion to partway along the tapered portion. Guide wire.

2. A guide wire comprising a core shaft, The core shaft comprises a first shaft made of stainless steel alloy located at the tip of the core shaft, and a second shaft having a tip portion to which the base end of the first shaft is joined, and which has superelastic properties. The second shaft has a tapered section in which the outer diameter increases from the tip end to the base end, A stepped portion is formed on the outer circumferential surface of the tapered portion, having a positioning surface that extends in the axial direction of the core shaft. The portion of the tapered section in which the stepped portion is formed includes a portion in which the outer diameter of the second shaft increases from the tip side to the base end side. The base end of the first shaft is joined along the positioning surface of the second shaft. Guide wire.

3. A guide wire according to claim 1 or claim 2, The first shaft has a flat opposing surface along the axial direction of the first shaft, The positioning surface of the second shaft is a flat surface. The opposing surface of the first shaft is joined to the positioning surface of the second shaft, Guide wire.

4. A guide wire according to claim 1 or claim 2, The axis of the second shaft is located on the same plane as the positioning surface. Guide wire.

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