Guide wire

Abstract

Provided is a guide wire having a tip portion which can be easily bent in a specific plane direction for shaping. The guide wire has a core shaft. When the longest diameter is a maximum diameter in the cross section orthogonal to the axial direction of the core shaft, the diameter in a direction orthogonal to the direction of the maximum diameter in the cross section is an orthogonal diameter, and a value obtained by dividing the difference between the maximum diameter and the orthogonal diameter by the maximum diameter is a flatness ratio, and the core shaft has a first specific portion located on the tip side thereof and having a flatness ratio of 7% to 35%. The first specific portion in the axial direction of the core shaft is 5 mm or more.

Description

Technical Field

[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 a "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 a core shaft formed of, for example, a metal material (see, for example, Patent Document 1).

[0003] In many conventional guide wires, the cross-section (a section perpendicular to the axial direction of the core shaft) of the tip of the guide wire is circular.

[0004] In the method using a guide wire, in order to improve the vascular selectivity of the guide wire, a treatment called "shaping" may be performed in which a technician such as a doctor bends the tip of the guide wire to a predetermined angle in advance before inserting the guide wire into a blood vessel or the like. Conventionally, the tip of a guide wire having a circular cross-section is bent by shaping.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In shaping, it may be required that the bending direction of the tip of the guide wire after shaping is limited to a predetermined direction (strictly speaking, the direction along a certain plane along the axial direction of the guide wire. Hereinafter, referred to as the "specific plane direction"). (Sometimes called "two-dimensional shaping"). For example, when performing shaping that bends each of a first portion including the tip of the guide wire and a second portion located on the proximal end side of the guide wire with respect to the first portion, it is required that both the bending direction of the first portion and the bending direction of the second portion are limited to the same specific plane direction.

[0007] In a configuration where the cross section (a cross section orthogonal to the axial direction of the core shaft) of the tip of the guide wire is circular, the ease of deformation of the tip of the guide wire is the same for each deformation direction. Therefore, in this configuration, the tip of the core shaft (and thus the tip of the guide wire) may deform in a direction different from the specific plane direction (sometimes called "three-dimensional shaping"). Therefore, in this configuration, it is not easy to bend the tip of the guide wire in the specific plane direction (or a direction close to the specific plane direction) during shaping.

[0008] This specification discloses a technique capable of solving the above-described problems.

Means for Solving the Problems

[0009] The technique disclosed in this specification can be realized, for example, in the following forms.

[0010] (1) The guide wire disclosed in this specification is a guide wire including a core shaft. In a cross section orthogonal to the axial direction of the core shaft, the diameter with the maximum length is defined as the maximum diameter, the diameter in the direction orthogonal to the direction of the maximum diameter in the cross section is defined as the orthogonal diameter, and when the value obtained by dividing the difference between the maximum diameter and the orthogonal diameter by the maximum diameter is defined as the flatness ratio, the core shaft has a first specific portion located on the tip side of the core shaft and having a flatness ratio of 7% or more and 35% or less, and the length of the first specific portion in the axial direction is 5 mm or more.

[0011] In this guide wire, as described above, the flatness ratio in the first specific portion is 7% or more. The length of the first specific portion in the axial direction is 5 mm or more. Therefore, according to this guide wire, in shaping, the first specific portion can be easily bent in the specific surface direction (specifically, the surface along the axial direction and the direction of the orthogonal diameter) or in a direction close to the specific surface direction.

[0012] Also, in this guide wire, as described above, the flatness ratio of the first specific portion is 35% or less. Therefore, according to this guide wire, while it is possible to easily bend the first specific portion in the specific surface direction in shaping as described above, the rotation performance of the guide wire can be ensured.

[0013] (2) In the above guide wire, the first specific portion may be configured to be formed of a material containing stainless steel. In this guide wire, since the first specific portion is formed of a material containing stainless steel which is easily plastically deformed, the deformation due to shaping is likely to remain without returning to the original state, so shaping can be easily performed.

[0014] (3) In the above guide wire, the core shaft may be configured to have a second specific portion located on the tip side of the core shaft with respect to the first specific portion and having a flatness ratio of 40% or more. This guide wire is particularly suitable for use when the guide wire is in a state where the first specific portion is bent relatively small and the second specific portion located on the tip side of the first specific portion is bent relatively large. 1 first 1 first 2 second

[0015] (4) In the guide wire, the direction of the maximum diameter of the first specific portion and the direction of the maximum diameter of the second specific portion may be parallel to each other. This guide wire is particularly suitable for use when the guide wire is in a state where the first specific portion is bent relatively slightly and the second specific portion located on the tip side of the first specific portion is bent relatively largely.

[0016] (5) In the guide wire, the second specific portion may be formed of a material containing stainless steel. In this guide wire, since the specific portion is formed of a material containing stainless steel which is easily plastically deformed, the deformation due to shaping is likely to remain without returning, so that shaping can be easily performed. 2 Since the specific portion is formed of a material containing stainless steel which is easily plastically deformed, the deformation due to shaping is likely to remain without returning, so that shaping can be easily performed.

[0017] (6) In the guide wire, the core shaft may be located on the proximal end side of the guide wire rather than the first specific portion and have a superelastic portion formed of a material containing a superelastic alloy. According to this guide wire, while it is possible to easily bend the first specific portion in the specific surface direction in shaping as described above, the operability and blood vessel selectivity of the guide wire can be ensured.

[0018] Note that the technology disclosed in this specification can be realized in various forms, for example, in the form of a guide wire or its manufacturing method.

Brief Description of the Drawings

[0019]

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Mode for Carrying Out the Invention

[0020] A. First Embodiment: A-1. Configuration of Guide Wire 100: FIG. 1 is a side view schematically showing the overall configuration of the guide wire 100 in the first embodiment. In FIG. 1, XYZ axes orthogonal to each other for specifying directions are shown, and the overall configuration of the guide wire 100 as viewed in the positive X-axis direction is shown. In FIG. 1, the positive Z-axis side is the tip side (distal side) to be inserted into the body, and the negative Z-axis side is the base end side (proximal side) to be operated by a technician such as a doctor. These points are the same for the figures after FIG. 2. In FIG. 1, for the coil body 20 and the tip-side joint 30 described later, the 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 linear and substantially parallel to the Z-axis direction as a whole, but the guide wire 100 has flexibility to the extent that it can be curved. Hereinafter, for the guide wire 100 and each component member of the guide wire 100, the portion extending from the tip including the tip to the middle toward the base end side is referred to as the "tip portion". Similarly, for the guide wire 100 and each component member of the guide wire 100, the portion extending from the base end including the base end to the middle toward the tip side is referred to as the "base end portion".

[0021] 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 30, and a base-end-side joint 40.

[0022] The core shaft 10 is a rod-shaped member with a thin diameter at the tip side and a thick diameter at the base end side. The core shaft 10 includes a first core shaft portion 11 including the tip of the core shaft 10 and a second core shaft portion 12 located on the base end side with respect to the first core shaft portion 11. Details of the first core shaft portion 11 will be described later. of 0 The second core shaft portion 12 located on the base end side is provided. Details of the first core shaft portion 11 will be described later.

[0023] The second core shaft portion 12 has a small-diameter portion 120, a large-diameter portion 121, and a tapered portion 122. In FIG. 1, a part of the large-diameter portion 121 of the second core shaft portion 12 is not shown. The second core shaft portion 12 is an example of the superelastic portion of the claims.

[0024] The small-diameter portion 120 of the second core shaft portion 12 is a portion including the tip of the second core shaft portion 12. The small-diameter portion 120 has a rod shape with a circular cross-section. The cross-section is a cross-section (in this embodiment, the XY cross-section) perpendicular to the axial direction of the core shaft 10 (in this embodiment, the Z-axis direction) (the same applies in the second and subsequent embodiments). In this embodiment, the axial direction of the core shaft 10 coincides with the axial direction of the guide wire 100.

[0025] The large-diameter portion 121 of the second core shaft portion 12 is located on the proximal end side of the core shaft 10A with respect to the small-diameter portion 120, and has a rod shape with a circular cross-section whose outer diameter is larger than that of the small-diameter portion 120.

[0026] The tapered portion 122 of the second core shaft portion 12 is located between the small-diameter portion 120 and the large-diameter portion 121. The outer diameter of the tapered portion 122 gradually increases from the boundary position with the small-diameter portion 120 toward the boundary position with the large-diameter portion 121.

[0027] Note that the shape of the cross-section of each part of the second core shaft portion 12 is not particularly limited, and may be a polygon such as a triangle or a quadrilateral, for example.

[0028] As materials for forming the second core shaft portion 12, for example, metal materials, more specifically, stainless steels (such as SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wires, nickel-chromium alloys, cobalt alloys, tungsten, etc. can be mentioned. In this embodiment, it is formed of a material including a superelastic alloy such as a Ni-Ti alloy. In this embodiment, by having a configuration including the second core shaft portion 12 formed of a material including a superelastic alloy, even when the guide wire 100 advances through a bent blood vessel or the like, the deformed second core shaft portion 12 can exhibit the performance of returning to its original shape (sometimes referred to as "recoverability"). Thereby, the operability and blood vessel selectivity of the guide wire 100 can be ensured.

[0029] The coil body 20 is a coil-shaped member formed in a hollow cylindrical shape by spirally winding a single wire. The coil body 20 is arranged so as to surround the outer periphery of the tip portion of the core shaft 10 (specifically, a part of the first core shaft portion 11, the small-diameter portion 120, the tapered portion 122, and the large-diameter portion 121 of the second core shaft portion 12).

[0030] The coil body 20 is composed of, for example, a radiation-permeable alloy such as a metal material, more specifically, stainless steels (such as SUS302, SUS304, SUS316, etc.), a superelastic alloy such as a Ni-Ti alloy, a piano wire, a nickel-chromium alloy, or a cobalt alloy, or a radiation-impermeable alloy such as gold, platinum, tungsten, or an alloy containing these elements (for example, a platinum-nickel alloy). When at least a part of the coil body 20 is formed of a radiation-impermeable material, the operator can grasp the position of the coil body 20 under a fluoroscopic image.

[0031] The tip-side joint portion 30 joins the tip of the core shaft 10 and the tip of the coil body 20. Inside the tip-side joint portion 30, the tip of the core shaft 10 and the tip of the coil body 20 are fixedly embedded. The outer peripheral surface on the tip side of the tip-side joint portion 30 is a smooth surface (for example, a substantially hemispherical surface). The tip-side joint portion 30 is composed 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. By arranging the tip-side joint portion 30 on the tip side with respect to the core shaft 10, the core shaft 10 is prevented from coming into contact with a blood vessel wall or the like, and thus damage to the core shaft 10 is suppressed.

[0032] The base-end side joint portion 40 is a member that joins the base-end side of the core shaft 10 and the base-end side of the coil body 20. The base-end side joint portion 40 is composed of the same material as the above-described tip-side joint portion 30. Note that the base-end side joint portion 40 is not limited to the base-end side of the coil body 20 and may be arranged at any position of the coil body 20.

[0033] A-2. Detailed configuration of the first core shaft portion 11: FIG. 2 is a side view showing an enlarged part of the core shaft 10 in the first embodiment. FIG. 2 shows the configuration of a part of the core shaft 10 (the portion of X1 in FIG. 1) when viewed in the positive X-axis direction. FIG. 3 is a diagram showing the cross-sectional configuration of the core shaft 10 at the position of III-III in FIG. 2, FIG. 4 is a diagram showing the cross-sectional configuration of the core shaft 10 at the position of IV-IV in FIG. 2, and FIG. 5 is a diagram showing the cross-sectional configuration of the core shaft 10 at the position of V-V in FIG. 2. The diagrams from FIG. 3 to FIG. 5 show the cross-sectional configuration of the core shaft 10 when viewed in the negative Z-axis direction.

[0034] The first core shaft portion 11 is a rod-shaped member. In the present embodiment, the first core shaft portion 11 is formed of a material including stainless steel (such as SUS302, SUS304, SUS316, etc.). The first core shaft portion 11 may be called a "ribbon" or a "shaping ribbon". The first core shaft portion 11 is connected (for example, joined by 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) to the tip of the second core shaft portion 12 (the small-diameter portion 120).

[0035] As shown in FIG. 2, the first core shaft portion 11 has a high-flat portion 110, a low-flat portion 112, and a tapered portion 111. Note that the high-flat portion 110 of the first core shaft portion 11 is an example of a second specific portion in the claims, and the low-flat portion 112 of the first core shaft portion 11 is an example of a first specific portion in the claims.

[0036] Hereinafter, in a cross section (a cross section orthogonal to the axial direction of the core shaft 10 (in the present embodiment, the Z-axis direction), i.e., the XY cross section in the present embodiment), the diameter with the maximum length is referred to as the "maximum diameter", the diameter with the maximum length in the direction orthogonal to the direction of the maximum diameter in the cross section is referred to as the "orthogonal diameter", and the value (%) obtained by dividing the difference between the maximum diameter and the orthogonal diameter by the maximum diameter is referred to as the "flatness ratio".

[0037] The high-flat portion 110 of the first core shaft portion 11 is a portion including the tip of the first core shaft portion 11.

[0038] As shown in FIG. 3, the cross section of the high-flat portion 110 has a flat shape (substantially rectangular or substantially elliptical) with the diameter in the X-axis direction as the major axis and the diameter in the Y-axis direction as the minor axis. In the cross section of the high-flat portion 110, the major axis corresponds to the maximum diameter D11, and the minor axis corresponds to the orthogonal diameter D12.

[0039] The flatness ratio of the high-flatness portion 110 in the cross-section of the first core shaft portion 11 is 40% or more. As a specific example, when the wire diameter (the diameter of the rod-shaped member before flatness processing such as press working to be described later; the same shall apply hereinafter) is 40 μm, in the high-flatness portion 110, the maximum diameter D11 is 57 μm, the orthogonal diameter D12 is 24 μm, and the flatness ratio is 57.9%. The flatness ratio of the high-flatness portion 110 in the cross-section of the first core shaft portion 11 may be other values of 40% or more (the same applies in the third embodiment below).

[0040] As shown in FIG. 2, the low-flatness portion 112 of the first core shaft portion 11 is a portion including the proximal end of the first core shaft portion 11. The low-flatness portion 112 has a connection portion with the tip of the second core shaft portion 12 (the small-diameter portion 120) on the proximal end side of the low-flatness portion 112.

[0041] As shown in FIG. 4, the cross-section of the low-flatness portion 112 has a flat shape (substantially rectangular or substantially elliptical) with the diameter in the X-axis direction as the major axis and the diameter in the Y-axis direction as the minor axis. In the cross-section of the low-flatness portion 112, the major axis corresponds to the maximum diameter D21, and the minor axis corresponds to the orthogonal diameter D22.

[0042] The flatness ratio of the low-flatness portion 112 of the first core shaft portion 11 is 7% or more and 35% or less. As a specific example, when the wire diameter is 40 μm and the flatness ratio is 30.0%, in the low-flatness portion 112, the maximum diameter D21 is 46 μm, and the orthogonal diameter D22 is 32 μm. Also, when the flatness ratio is 7.3%, the maximum diameter D21 is 41 μm, and the orthogonal diameter D22 is 38 μm. When the wire diameter is 75 μm and the flatness ratio is 31.0%, the maximum diameter D21 is 87 μm, the orthogonal diameter D22 is 60 μm, and when the flatness ratio is 7.8%, the maximum diameter D21 is 77 μm, and the orthogonal diameter D22 is 71 μm.

[0043] As shown in FIG. 2, the tapered portion 111 of the first core shaft portion 11 is located between the high-flatness portion 110 and the low-flatness portion 112. The flatness ratio of the tapered portion 111 changes stepwise or gradually from the boundary position with the high-flatness portion 110 toward the boundary position with the low-flatness portion 112.

[0044] Incidentally, the first core shaft portion 11 having a cross section with the above-described flat shape (substantially rectangular or substantially elliptical) can be manufactured, for example, by subjecting a rod-shaped member made of a material containing stainless steel to a flattening process such as press working so that the cross section becomes circular.

[0045] A-3. Effects of the First Embodiment: As described above, the guide wire 100 of the first embodiment includes a core shaft 10. The core shaft 10 has a low flat portion 112 (of the first core shaft portion 11) located on the tip side of the core shaft 10 and having a flatness ratio of 7% or more and 35% or less. The length of the low flat portion 112 of the first core shaft portion 11 in the axial direction (Z-axis direction in this embodiment) of the core shaft 10 is 5 mm or more.

[0046] In the configuration where the cross section of the tip of the guide wire 100 is circular, the ease of deformation of the tip of the guide wire 100 is the same in each deformation direction. Therefore, in this configuration, the tip of the core shaft 10 (and thus the tip of the guide wire 100) may deform in a direction different from the specific surface direction (sometimes referred to as "3D shaping"). Therefore, in this configuration, it is not easy to bend the tip of the guide wire 100 in the specific surface direction (or a direction close to the specific surface direction) during shaping.

[0047] On the other hand, in the guide wire 100 of the first embodiment, as described above, the flatness ratio in the low-flat portion 112 of the first core shaft portion 11 is 7% or more. The length of the low-flat portion 112 of the first core shaft portion 11 in the axial direction of the core shaft 10 is 5 mm or more. Therefore, in the guide wire 100 of the first embodiment, compared with the configuration in which the cross section of the low-flat portion 112 of the first core shaft portion 11 is circular (in other words, the flatness ratio is 0%), in shaping, the bending direction of the low-flat portion 112 tends to be limited to a specific plane direction (specifically, the direction along the plane (in this embodiment, the YZ plane) along the axial direction of the core shaft 10 and the direction of the orthogonal diameter D22). Therefore, according to the guide wire 100 of the first embodiment, in shaping, the low-flat portion 112 of the first core shaft portion 11 can be easily bent in the specific plane direction (or a direction close to the specific plane direction).

[0048] Further, in the configuration where the flatness ratio in the low-flat portion 112 of the first core shaft portion 11 is 40% or more, due to the high flatness ratio (in other words, the difference between the maximum diameter D21 and the orthogonal diameter D22 is large), when the guide wire 100 inserted into a blood vessel or the like is rotated, the tip of the guide wire 100 (around the low-flat portion 112 of the first core shaft portion 11) may bounce back and forth like a whip while contacting the blood vessel wall or the like, which is called a "whip" behavior. As a result, the rotation performance (operability) of the guide wire 100 may decrease.

[0049] In contrast, in the guide wire 100 of the first embodiment, as described above, the flatness ratio of the low-flat portion 112 of the first core shaft portion 11 is 35% or less. Therefore, in the guide wire 100 of the first embodiment, when the guide wire 100 inserted into a blood vessel or the like is rotated, the occurrence of whip is suppressed, and consequently, the decrease in the rotational performance of the guide wire 100 due to the occurrence of whip is suppressed. Therefore, according to the guide wire 100 of the first embodiment, as described above, although it is a configuration in which the low-flat portion 112 of the first core shaft portion 11 can be easily bent in a specific surface direction in shaping, the rotational performance of the guide wire 100 can be ensured.

[0050] In addition, in a configuration where the length of the low-flat portion 112 of the first core shaft portion 11 in the axial direction of the core shaft 10 is less than 5 mm, it is difficult to shape the tip portion. In this embodiment, since the length of the low-flat portion 112 of the first core shaft portion 11 in the axial direction of the core shaft 10 is 5 mm or more, it becomes easier to shape the tip portion. Also, if the length of the low-flat portion 112 of the first core shaft portion 11 in the axial direction of the core shaft 10 is excessively long, there is a risk that whip is likely to occur. Therefore, the length of the low-flat portion 112 of the first core shaft portion 11 in the axial direction of the core shaft 10 is preferably, for example, 15 mm or less.

[0051] Further, in the guide wire 100 of the first embodiment, the wire diameter of the strands of the low-flat portion 112 of the first core shaft portion 11 is 40 μm or more. If the wire diameter of the strands is less than 40 μm, regardless of the flatness ratio, the shaping directionality is less likely to be limited to the specific surface direction. Therefore, in this embodiment where the wire diameter of the strands of the low-flat portion 112 of the first core shaft portion 11 is 40 μm or more, compared with a configuration where the wire diameter of the strands is less than 40 μm, the shaping directionality tends to be limited to the specific surface direction. Therefore, according to this embodiment, the rotational performance of the guide wire 100 can be more reliably ensured.

[0052] In the guide wire 100 of the first embodiment, the low-flat portion 112 of the first core shaft portion 11 is formed of a material containing stainless steel. Therefore, in the guide wire 100 of the first embodiment, since the low-flat portion 112 of the first core shaft portion 11 is formed of a material containing stainless steel that is easily plastically deformed, the deformation due to shaping is likely to remain without returning to its original state, so that shaping can be easily performed.

[0053] In the guide wire 100 of the first embodiment, the core shaft 10 has a high-flat portion 110 of the first core shaft portion 11 that is located on the tip side of the core shaft 10 rather than the low-flat portion 112 of the first core shaft portion 11 and has a flatness ratio of 40% or more. Therefore, in the guide wire 100 of the first embodiment, the bending angle due to shaping of the high-flat portion 110 located on the tip side of the guide wire 100 rather than the low-flat portion 112 of the first core shaft portion 11 is likely to be larger than the bending angle due to shaping of the low-flat portion 112 of the first core shaft portion 11. Therefore, the guide wire 100 of the first embodiment is particularly suitable for use when the guide wire 100 is in a state where the low-flat portion 112 of the first core shaft portion 11 is bent relatively small and low flat part 112 the high-flat portion 110 located on the more tip side is bent relatively large.

[0054] In the guide wire 100 of the first embodiment, the direction of the maximum diameter D21 of the low-flat portion 112 of the first core shaft portion 11 and the direction of the maximum diameter D11 of the high-flat portion 110 of the first core shaft portion 11 are parallel to each other. Therefore, as a result, the bending direction due to shaping in the low-flat portion 112 and the high-flat portion 110 of the first core shaft portion 11 tends to be along the directions of the orthogonal diameters D12 and D22 rather than the directions of the maximum diameters D11 and D21, resulting in a substantially the same plane direction. Therefore, the generation of a three-dimensional shape between the low-flat portion 112 and the high-flat portion 110 of the first core shaft portion 11 is suppressed, and thereby, the directivity of the deformation of the guide wire 100 due to shaping can be limited to a specific plane direction (or a direction close to the specific plane direction).

[0055] Further, in the guide wire 100 of the first embodiment, the highly flattened portion 110 of the first core shaft portion 11 is formed of a material containing stainless steel. Therefore, in the guide wire 100 of the first embodiment, since the highly flattened portion 110 of the first core shaft portion 11 is formed of a material containing stainless steel which is easily plastically deformed, the deformation due to shaping is likely to remain without returning, so that shaping can be easily performed.

[0056] Further, in the guide wire 100 of the first embodiment, the core shaft 10 has a second core shaft portion 12 which is located on the proximal end side of the guide wire 100 rather than the low flattened portion 112 of the first core shaft portion 11 and is formed of a material containing a superelastic alloy. In the guide wire 100 of the first embodiment, since the second core shaft portion 12 located on the proximal end side of the guide wire 100 rather than the low flattened portion 112 of the first core shaft portion 11 is formed of a material containing a superelastic alloy, the restorability of the second core shaft portion 12 can be exhibited, and thereby, the operability and blood vessel selectivity of the guide wire 100 can be ensured. Therefore, according to the guide wire 100 of the first embodiment, while it is configured that the low flattened portion 112 of the first core shaft portion 11 can be easily bent in a specific surface direction in shaping as described above, the operability and blood vessel selectivity of the guide wire 100 can be ensured.

[0057] A-4. Performance evaluation of the first embodiment: A-4-1. Evaluation regarding the directivity of shaping: Samples of the guide wire were prepared, and using these samples, an evaluation regarding the directivity of shaping of the guide wire was performed. FIGS. 6 and 7 are explanatory diagrams showing the evaluation results regarding the directivity of shaping in the present embodiment.

[0058] A-4-1-1. Regarding each sample: As shown in FIGS. 6 and 7, for 30 samples of the guide wire (Samples 1, 2, ···, 30) in this performance evaluation, an evaluation regarding the shaping directionality was performed. The 30 samples as a whole have substantially the same configuration as the above-described guide wire 100. Specifically, the 30 samples are guide wires each including a core shaft and a coil body or the like. The core shaft includes a first core shaft portion formed of a material containing stainless steel including its tip, and a second core shaft portion located on the proximal end side of the core shaft with respect to the first core shaft portion and formed of a material containing a superelastic alloy such as Ni-Ti alloy.

[0059] For the 30 samples, at least one of the wire diameter (the diameter having the maximum length in the cross-section (XY cross-section)) and the flatness ratio is different from each other. Specifically, for Samples 1 to 6, the wire diameter is 80 μm, for Samples 7 to 12, the wire diameter is 70 μm, for Samples 13 to 18, the wire diameter is 55 μm, for Samples 19 to 24, the wire diameter is 40 μm, and for Samples 25 to 30, the wire diameter is 30 μm.

[0060] As shown in FIG. 6, Samples 1 to 6 have different flatness ratios from each other. Specifically, the flatness ratio of Sample 1 is 0%, the flatness ratio of Sample 2 is 7.5%, the flatness ratio of Sample 3 is 15%, the flatness ratio of Sample 4 is 23%, the flatness ratio of Sample 5 is 35%, and the flatness ratio of Sample 6 is 38%. Similarly, Samples 7 to 12, Samples 13 to 18, Samples 19 to 24, and Samples 25 to 30 also have different flatness ratios from each other as shown in FIGS. 6 and 7, respectively.

[0061] Note that the maximum diameter and the orthogonal diameter (and thus the flatness ratio) in each sample can be adjusted by changing the press-in amount of the press when manufacturing the first core shaft portion having a cross-section in the above-described shape by subjecting a wire having a circular cross-section to press working. Specifically, the larger the press-in amount of the press, the larger the maximum diameter and the smaller the orthogonal diameter can be (and thus the larger the flatness ratio can be).

[0062] A-4-1-2. Method for specifying the maximum diameter and the orthogonal diameter: The maximum diameter and the orthogonal diameter in each sample are specified, for example, as follows. First, the core shaft of each sample is cut out, and its cut surface is observed in cross-section with an electron microscope at a magnification of, for example, 100,000 times to specify them. In this way, the maximum diameter and the orthogonal diameter at a plurality of different locations (for example, 10 locations) in the first core shaft portion are calculated, and the average value of the maximum diameters at these plurality of locations is taken as the maximum diameter of the first core shaft portion, and the average value of the orthogonal diameters at these plurality of locations is taken as the orthogonal diameter of the first core shaft portion. Alternatively, the measuring method may be one in which a laser or the like is irradiated onto the outer periphery of the core shaft of each sample to extract the outer shape of the core shaft and calculate the maximum diameter and the orthogonal diameter, and is not particularly limited.

[0063] A-4-1-3. Method for evaluating the directionality of shaping: FIG. 8 is an explanatory diagram for explaining a method of measuring the directionality of shaping. Note that in FIG. 8, the low flat portion 112 in the sample including the first core shaft portion 11 of the present embodiment is schematically shown. The directionality of shaping was evaluated as follows. First, as shown in FIG. 8, the tip of the first core shaft portion is curved by 90° along the surface direction A (the YZ plane direction in FIG. 8) along the direction of the orthogonal diameter. Next, a force is applied to the tip of the first core shaft portion along the surface direction B (the XZ plane direction in FIG. 8) that is substantially orthogonal to the surface direction A. If it is curved in the surface direction A (or a surface direction closer to the surface direction A than the surface direction B) at this time, it is determined as "○" (qualified), and if it is curved in the surface direction B (or a surface direction closer to the surface direction B than the surface direction A), it is determined as "×" (unqualified).

[0064] A-4-1-4. Evaluation Results of Shaping Directionality: As shown in FIGS. 6 and 7, for Samples 1, 7, 13, and 19, the evaluation results of shaping directionality were "×". On the other hand, for Samples 2 to 6, 8 to 12, 14 to 18, and 20 to 24, the evaluation results of shaping directionality were "○". This means that by setting the flatness ratio to 7% or more, the shaping directionality tends to be limited to a specific surface direction (surface direction A along the direction of the orthogonal diameter).

[0065] Also, for Samples 25 to 30, the evaluation results of shaping directionality were "×". On the other hand, as described above, for Samples 20 to 24, etc., the evaluation results of shaping directionality were "○". This means that by setting the wire diameter to 40 μm or more, the shaping directionality tends to be limited to a specific surface direction (surface direction A along the direction of the orthogonal diameter), and when the wire diameter is less than 40 μm, regardless of the flatness ratio, the shaping directionality tends to be less likely to be limited to a specific surface direction.

[0066] A-4-2. Evaluation Regarding Rotation Performance: Using the 30 samples used for the above evaluation regarding the shaping direction, an evaluation of the rotation performance of the guide wire was conducted. FIGS. 9 and 10 are explanatory diagrams showing the evaluation results of the rotation performance in this embodiment. FIG. 11 is an explanatory diagram showing an example of the measurement results regarding the rotation performance in this embodiment.

[0067] A-4-2-1. Evaluation Method of Rotation Performance: The rotation performance was evaluated as follows. When the proximal end portion of the guide wire was rotated (in the circumferential direction of the axis of the guide wire), it was evaluated based on whether the distal end portion of the guide wire (in this performance evaluation, the first core shaft portion) rotated before the proximal end portion rotated 180°.

[0068] FIG. 12 is an explanatory diagram for explaining a method of measuring rotational performance. In FIG. 12, a state is shown when the guide wire 100 of the present embodiment is used as a sample. Specifically, first, as shown in FIG. 12, the tip of the first core shaft portion (in the guide wire 100 of the present embodiment, the low flat portion 112) is curved at a curvature radius of 5 mm by 90°, and a guide wire is prepared in a state where the base end side portion is curved at a curvature radius of 70 mm on the side opposite to the tip end portion. A motor M for rotating the guide wire (in the circumferential direction of the axis of the guide wire) is attached to the base end portion of the guide wire. Then, the motor M is driven to rotate the guide wire (in the circumferential direction of the axis of the guide wire). At this time, the tip of the first core shaft portion (in other words, the tip of the guide wire) is photographed with a video camera C, and based on the content of the video, the presence or absence of rotation of the tip of the guide wire (the first core shaft portion) is determined.

[0069] And when rotation of the tip of the guide wire (in this performance evaluation, the first core shaft portion) occurs before the base end portion rotates 180°, it is determined as "○" (qualified), and when no rotation occurs before rotating 180°, it is determined as "×" (unqualified). Note that the smaller the curvature radius at the tip of the first core shaft portion, the greater the tendency for the delay of the rotation angle of the tip portion with respect to the rotation angle of the base end portion to increase. Therefore, the pass / fail criteria for evaluating the rotational performance differ depending on the curvature radius at the tip of the first core shaft portion.

[0070] A-4-2-2. Evaluation result of rotational performance: As shown in FIGS. 9 and 10, in Samples 1 to 4, the evaluation results of the rotational performance were "○". On the other hand, in Samples 5 and 6, the evaluation results of the rotational performance were "×". This means that by making the flatness ratio less than 35%, the rotational performance of the guide wire is improved. As a reason for the improvement of the rotational performance of the guide wire, it is considered that the occurrence of the above-mentioned whip is suppressed because the flatness ratio is sufficiently small.

[0071] In addition, in FIG. 11, as an example of the measurement results of the rotation performance of the guide wire in this performance evaluation, the measurement results of Samples 1, 3, and 5 are shown. In Sample 1, the input rotation angle (the rotation angle of the proximal end portion of the guide wire) and the output rotation angle (the rotation angle of the distal end portion of the guide wire) have a substantially linear correspondence relationship with a slope close to 1. That is, when the proximal end portion of the guide wire is rotated, the distal end portion rotates at substantially the same rotation angle as the rotation angle of the proximal end portion. Therefore, in Sample 1, since the rotation of the distal end portion of the guide wire occurs before the proximal end portion rotates 180°, Sample 1 was determined to be "○". Also, in Sample 3, since the rotation of the distal end portion occurred before the proximal end portion rotated by a rotation angle smaller than 180°, Sample 3 was determined to be "○". Further, in Sample 5, since the rotation of the distal end portion occurred before the proximal end portion rotated by a rotation angle larger than 180°, Sample 5 was determined to be "×".

[0072] Also, in Samples 7 to 30, the evaluation results of the rotation performance were "○". This means that when the strand diameter is less than 80 μm, it is easy to ensure sufficient rotation performance regardless of the flattening ratio, and the problems related to the rotation performance as described above are likely to occur when the strand diameter is 80 μm or more.

[0073] In addition, the results of the performance evaluations (evaluations related to the shaping directionality and rotation performance) in the second to fourth embodiments and the modification examples described later are also the same as the results of the performance evaluation in the first embodiment.

[0074] B. Second Embodiment: B-1. Configuration of Guide Wire 100A: FIG. 13 is a side view schematically showing the overall configuration of the guide wire 100A in the second embodiment. FIG. 13 shows the overall configuration of the guide wire 100A as viewed in the positive X-axis direction. FIG. 14 is a side view showing an enlarged part of the core shaft 10A in the second embodiment. FIG. 14 shows the configuration of a part (the part X2 in FIG. 13) of the core shaft 10A as viewed in the positive X-axis direction. FIG. 15 is a cross-sectional view showing the cross-sectional configuration of the core shaft 10A at the position XV-XV in FIG. 14. FIG. 15 shows the cross-sectional configuration of the core shaft 10A as viewed in the negative Z-axis direction.

[0075] As shown in FIGS. 13 and 14, the configuration of the guide wire 100A in the second embodiment is different in the shape of the first core shaft portion 11A as compared with the configuration of the guide wire 100 in the first embodiment described above. Hereinafter, for the configurations that are the same as those of the guide wire 100 in the first embodiment described above among the configurations of the guide wire 100A in the second embodiment, the description thereof will be appropriately omitted by attaching the same reference numerals.

[0076] As shown in FIGS. 13 and 14, the core shaft 10A in the second embodiment includes a first core shaft portion 11A including the tip of the core shaft 10A, and a second core shaft portion 12 located on the base end side of the core shaft 10A with respect to the first core shaft portion 11A.

[0077] As shown in FIG. 15, the cross section (XY cross section in this embodiment) of the first core shaft portion 11A has an oval shape (substantially rectangular or substantially elliptical) with the diameter in the X-axis direction as the major axis and the diameter in the Y-axis direction as the minor axis. In the cross section of the first core shaft portion 11A, the major axis corresponds to the maximum diameter D31 (the diameter having the maximum length in the cross section (XY cross section in this embodiment) orthogonal to the axial direction of the core shaft 10A), and the minor axis corresponds to the orthogonal diameter D32 (the diameter having the maximum length in the direction orthogonal to the direction of the maximum diameter in the cross section orthogonal to the axial direction of the core shaft 10A).

[0078] The first core shaft portion 11A of the second embodiment is a rod-shaped member. The flatness ratio of the first core shaft portion 11A is 7% or more and 35% or less. As a specific example, when the wire diameter of the first core shaft portion 11A is 40 μm and the flatness ratio is 30.0%, the maximum diameter D31 is 46 μm and the orthogonal diameter D32 is 32 μm. When the flatness ratio is 7.3%, the maximum diameter D31 is 41 μm and the orthogonal diameter D32 is 38 μm. The flatness ratio of the first core shaft portion 11A may be other values that are 7% or more and 35% or less. The maximum diameter D31 and the orthogonal diameter D32 when the wire diameter is changed are the same as those described in the first embodiment. The first core shaft portion 11A of the present embodiment is an example of the first specific part of the claims.

[0079] The shape of the cross-section of the first core shaft portion 11A of the second embodiment is uniform over the entire length in the axial direction (in this embodiment, the Z-axis direction) of the first core shaft portion 11A.

[0080] B-2. Effects of the second embodiment: As described above, the guide wire 100A of the second embodiment includes a core shaft 10A. The core shaft 10A has a first core shaft portion 11A that is located on the tip side of the core shaft 10A and has a flatness ratio of 7% or more and 35% or less. The length of the first core shaft portion 11A in the axial direction (in this embodiment, the Z-axis direction) of the core shaft 10A is 5 mm or more.

[0081] In the guide wire 100A of the second embodiment, as described above, the flatness ratio of the first core shaft portion 11A is 7% or more and 35% or less. Therefore, in the guide wire 100A of the second embodiment, for the same reason as in the case of the first embodiment, compared with the configuration in which the cross section of the first core shaft portion 11A is circular, in shaping, the bending direction of the first core shaft portion 11A tends to be limited to the specific surface direction (specifically, the direction along the axial direction of the core shaft 10A and the direction of the orthogonal diameter D32 (in this embodiment, the YZ plane)). Therefore, according to the guide wire 100A of the second embodiment, in shaping, the first core shaft portion 11A can be easily bent in the specific surface direction (or a direction close to the specific surface direction). Further, in the guide wire 100A of the second embodiment, as described above, the flatness ratio of the first core shaft portion 11A is less than 35%. Therefore, according to the guide wire 100A of the second embodiment, while it is a configuration in which the first core shaft portion 11A can be easily bent in the specific surface direction in shaping as described above, for the same reason as in the case of the first embodiment, the rotational performance of the guide wire 100A can be ensured.

[0082] In a configuration where the length of the first core shaft portion 11A in the axial direction of the core shaft 10A is less than 5 mm, it is difficult to shape the tip portion. In this embodiment, by setting the length of the first core shaft portion 11A in the axial direction of the core shaft 10A to 5 mm or more, it becomes easier to shape the tip portion. Further, if the length of the first core shaft portion 11A in the axial direction of the core shaft 10A is excessively long, there is a risk that whip is likely to occur. Therefore, the length of the first core shaft portion 11A in the axial direction of the core shaft 10A is preferably, for example, 15 mm or less.

[0083] In addition, in the guide wire 100A of the second embodiment, the first core shaft portion 11A is formed of a material containing stainless steel. Therefore, in the guide wire 100A of the second embodiment, since the first core shaft portion 11A is formed of a material containing stainless steel that is prone to plastic deformation, the deformation due to shaping is likely to remain without returning to its original state, so shaping can be easily performed.

[0084] In addition, in the guide wire 100A of the second embodiment, the core shaft 10A is located on the proximal end side of the guide wire 100A with respect to the first core shaft portion 11A, and has a second core shaft portion 12 formed of a material containing a superelastic alloy. Therefore, according to the guide wire 100A of the second embodiment, while it is possible to easily bend the first core shaft portion 11A in a specific surface direction in shaping as described above, for the same reasons as in the case of the first embodiment, the operability and blood vessel selectivity of the guide wire 100A can be ensured.

[0085] C. Third Embodiment: C-1. Configuration of the guide wire 100B: FIG. 16 is a side view schematically showing the overall configuration of the guide wire 100B in the third embodiment. FIG. 17 is a cross-sectional view showing the cross-sectional configuration of the core shaft 10B at the position of XVII-XVII in FIG. 16. FIG. 18 is a cross-sectional view showing the cross-sectional configuration of the core shaft 10B at the position of XVIII-XVIII in FIG. 16. The configuration of the guide wire 100B of the third embodiment is different from the configuration of the guide wire 100 of the first embodiment described above in the configuration of the core shaft 10B. Hereinafter, for the 3 configuration of the guide wire 100 B of the embodiment, for the configurations that are the same as those of the guide wire 100 of the first embodiment described above, the description thereof will be appropriately omitted by attaching the same reference numerals.

[0086] As shown in FIG. 16, the core shaft 10B of the third embodiment is a rod-shaped member with a small diameter at the tip side and a large diameter at the base end side. The core shaft 10B includes a first core shaft portion 11B including the tip of the core shaft 10B, and a second core shaft portion 12 located on the base end side of the core shaft 10B with respect to the first core shaft portion 11B. The core shaft 10B has the first core shaft portion 11B and the second core shaft portion 12 integrally formed. In the present embodiment, the core shaft 10B is formed of a material including stainless steel (such as SUS302, SUS304, SUS316, etc.).

[0087] As shown in FIGS. 17 and 18, the first core shaft portion 11B has a high flat portion 110B, a tapered portion 111B, and a low flat portion 112B having a cross section with the same shape as the high flat portion 110, the tapered portion 111, and the low flat portion 112 of the first core shaft portion 11 in the first embodiment.

[0088] C-2. Effects of the Third Embodiment: The guide wire 100B of the third embodiment includes a core shaft 10B. The core shaft 10B has a low flat portion 112B (of the first core shaft portion 11B) located on the tip side of the core shaft 10B and having a flatness ratio of 7% or more and 35% or less. The length of the low flat portion 112B of the first core shaft portion 11B in the axial direction (in the Z-axis direction in the present embodiment) of the core shaft 10B is 5 mm or more.

[0089] Therefore, according to the guide wire 100B of the third embodiment, for the same reason as in the case of the first embodiment, while it is a configuration in which the low flat portion 112B of the first core shaft portion 11B can be easily bent in a specific surface direction in shaping, the rotational performance of the guide wire 100B can be ensured.

[0090] Also, in the guide wire 100B of the third embodiment, the wire diameter of the low flat portion 112B of the first core shaft portion 11B is 40 μm or more. Therefore, according to this embodiment, for the same reason as in the first embodiment, the rotational performance of the guide wire 100B can be more reliably ensured.

[0091] Also, in the guide wire 100B of the third embodiment, in the low flat portion 112 of the first core shaft portion 11B B the maximum diameter D51 (or wire diameter) is 80 μm or more.

[0092] Also, in the guide wire 100B of the third embodiment, the low flat portion 112B of the first core shaft portion 11B is formed of a material containing stainless steel. Therefore, in the guide wire 100B of the third embodiment, since the low flat portion 112B of the first core shaft portion 11B is formed of a material containing stainless steel which is easily plastically deformed, the deformation by shaping is likely to remain without returning, so that shaping can be easily performed.

[0093] Also, in the guide wire 100B of the third embodiment, the core shaft 10B is located on the tip side of the core shaft 10B rather than the low flat portion 112B of the first core shaft portion 11B, and has a high flat portion 110B (of the first core shaft portion 11B) with a flatness ratio of 40% or more. Therefore, for the same reason as in the first embodiment, the guide wire 100B of the third embodiment bends the low flat portion 112B of the first core shaft portion 11B relatively small, low flat part 112B and is particularly suitable for using the guide wire 100B in a state where the high flat portion 110B located on the tip side is bent relatively large.

[0094] Also, in the guide wire 100B of the third embodiment, the direction of the maximum diameter D51 of the low flat portion 112B of the first core shaft portion 11B and the direction of the maximum diameter D51 of the high flat portion 110B of the first core shaft portion 11B are parallel to each other. Therefore, for the same reason as in the case of the first embodiment, the directionality of the deformation of the guide wire 100B by shaping can be limited to a specific surface direction (or a direction close to the specific surface direction).

[0095] Also, in the guide wire 100B of the third embodiment, the high flat portion 110B of the first core shaft portion 11B is formed of a material containing stainless steel. Therefore, in the guide wire 100B of the third embodiment, since the high flat portion 110B of the first core shaft portion 11B is formed of a material containing stainless steel that is easily plastically deformed, the deformation by shaping is likely to remain without returning to its original state, so shaping can be easily performed.

[0096] D. Fourth Embodiment: D-1. Configuration of Guide Wire 100C: FIG. 19 is a side view schematically showing the overall configuration of the guide wire 100C in the fourth embodiment. FIG. 20 is a cross-sectional view showing the cross-sectional configuration of the core shaft 10C at the position XX-XX in FIG. 19. The configuration of the guide wire 100C in the fourth embodiment is different from the configuration of the guide wire 100A in the second embodiment described above in the configuration of the core shaft 10C. Hereinafter, for 4 the guide wire 100 of the embodiment C among the configurations, for the configurations that are the same as those of the guide wire 100A in the second embodiment described above, the description thereof will be appropriately omitted by attaching the same reference numerals.

[0097] As shown in FIG. 19, the core shaft 10C of the fourth embodiment is a rod-shaped member having a small diameter at the tip end side and a large diameter at the base end side. The core shaft 10C of the fourth embodiment includes a first core shaft portion 11C including the tip end of the core shaft 10C, and a second core shaft portion 12 located on the base end side of the core shaft 10C with respect to the first core shaft portion 11C. The core shaft 10C has the first core shaft portion 11C and the second core shaft portion 12C integrally formed. In the present embodiment, the core shaft 10C is formed of a material including stainless steel (SUS302, SUS304, SUS316, etc.).

[0098] As shown in FIG. 20, the first core shaft portion 11C has a cross section having the same shape as the first core shaft portion 11A in the second embodiment.

[0099] D-2. Effects of the Fourth Embodiment: The guide wire 100C of the fourth embodiment includes a core shaft 10C. The core shaft 10C has a first core shaft portion 11C located on the tip end side of the core shaft 10C and having a flatness ratio of 7% or more and 35% or less. The length of the first core shaft portion 11C in the axial direction (Z-axis direction in the present embodiment) of the core shaft 10C is 5 mm or more.

[0100] In the guide wire 100C of the fourth embodiment, as described above, the flatness ratio in the first core shaft portion 11C is 7% or more and 35% or less. Therefore, according to the guide wire 100C of the fourth embodiment, for the same reasons as in the second embodiment and the 1 case of the embodiment, while it is a configuration in which the first core shaft portion 11C can be easily bent in a specific surface direction in shaping , ga the rotational performance of the guide wire 100C can be ensured.

[0101] Also, in the guide wire 100C of the fourth embodiment, the first core shaft portion 11C is formed of a material containing stainless steel. Therefore, in the guide wire 100C of the fourth embodiment, since the first core shaft portion 11C is formed of a material containing stainless steel which is prone to plastic deformation, the deformation due to shaping is likely to remain and not return to its original state, so shaping can be easily performed.

[0102] E. Modification Examples: The technology disclosed in this specification is not limited to the above-described embodiments, and can be deformed into various forms without departing from the gist thereof. For example, the following modifications are also possible.

[0103] The configurations of the guide wires 100 and 100A in the above-described embodiments are merely examples, and can be variously deformed.

[0104] For example, in the above-described first embodiment, the direction of the maximum diameter D21 of the low-flattened portion 112 of the first core shaft portion 11 and the direction of the maximum diameter D11 of the high-flattened portion 110 of the first core shaft portion 11 may not be parallel to each other.

[0105] Also, in the above-described embodiments, the guide wires 100, 100A, 100B, and 100C may not be provided with the tip-side joint portion 30.

[0106] Also, the materials of the respective members constituting the guide wires 100, 100A, 100B, and 100C in the above-described embodiments are merely examples, and can be variously deformed.

Explanation of Reference Numerals

[0107] 10: Core shaft (of the first embodiment) 10A: Core shaft (of the second embodiment) 10B: Core shaft (of the third embodiment) 10C: Core shaft (of the fourth embodiment) 11: First core shaft portion (of the first embodiment) 11A: First core shaft part (of the second embodiment) 11B: First core shaft part (of the third embodiment) 11C: First core shaft part (of the fourth embodiment) 12: Second core shaft part 20: Coil body 30: Tip-side joint part 40: Base-end side joint part 100: Guide wire (of the first embodiment) 100A: Guide wire (of the second embodiment) 100B: Guide wire (of the third embodiment) 100C: Guide wire (of the fourth embodiment) 110: High-flat part of the first core shaft part (of the first embodiment) 110B: High-flat part of the first core shaft part (of the third embodiment) 111: Taper part of the first core shaft part (of the first embodiment) 111B: Taper part of the first core shaft part (of the third embodiment) 112: Low-flat part of the first core shaft part (of the first embodiment) 112B: Low-flat part of the first core shaft part (of the third embodiment) 120: Small-diameter part of the second core shaft part 121: Large-diameter part of the second core shaft part 122: Taper part of the second core shaft part

Claims

1. A guide wire comprising a core shaft, wherein the core shaft has a flat portion formed by subjecting a rod-shaped member having a circular cross-section and a strand diameter of 40 μm or more to pressing, in the flat portion, when the diameter having the maximum length in a cross-section orthogonal to the axial direction of the core shaft is defined as the major diameter, the diameter having the maximum length in a direction orthogonal to the major diameter direction in the cross-section is defined as the orthogonal diameter, and the value obtained by dividing the difference between the major diameter and the orthogonal diameter by the major diameter is defined as the flatness ratio, the core shaft has a first specific portion located on the tip side of the core shaft and having a flatness ratio of 7.5% or more and 35% or less, the core shaft has a second specific portion located on the tip side of the core shaft relative to the first specific portion and having a flatness ratio greater than that of the first specific portion, the direction of the major diameter of the first specific portion and the direction of the major diameter of the second specific portion are parallel to each other, the first specific portion is formed of a material containing stainless steel, the core shaft is located between the second specific portion and the first specific portion, and has a tapered portion in which the flatness ratio gradually changes from the boundary position with the second specific portion toward the boundary position with the first specific portion, a guide wire.

2. The guide wire according to claim 1, wherein the flatness ratio of the second specific portion is 40% or more, a guide wire.

3. The guide wire according to claim 1 or claim 2, wherein the contour of the cross-section of the first specific portion includes an arc, a guide wire.

4. The guide wire according to any one of claims 1 to 3, wherein the contour of the cross-section of the first specific portion includes two parallel lines, a guide wire.

5. The guide wire according to any one of claims 1 to 4, wherein the cross-section of the first specific portion is substantially elliptical, a guide wire.

6. The guide wire according to any one of claims 1 to 5, wherein the second specific portion is formed of a material containing stainless steel, a guide wire.

7. The guide wire according to any one of claims 1 to 6, wherein the core shaft is located on the proximal side of the guide wire relative to the first specific portion, A guide wire having a superelastic portion formed of a material including a superelastic alloy. Guide wire. **Claim 8** The guide wire according to any one of claims 1 to 7, A coil body, and A distal end side joint that joins the distal end of the core shaft and the distal end of the coil body, and further includes: A guide wire (however, excluding the case where there is a reinforcing portion that reinforces the first specific portion on the surface of the first specific portion, which is a reinforcing portion on the proximal side of the proximal end of the distal end side joint).

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