Guide wire

Abstract

A guide wire achieves an appropriate range of penetration performance, that is, it can avoid damaging the body cavity and can reliably penetrate even in a relatively hard lesion part. The guide wire includes a mandrel, a coil body covering the mandrel, and a front-end side joint portion that joins the front end of the coil body and the front end of the mandrel. The front-end side joint portion has an outer diameter reduction portion having a substantially truncated cone shape with an outer diameter decreasing in the front-end direction, and a foremost end portion having a substantially spherical segment shape provided at the front end of the outer diameter reduction portion and having an outer diameter decreasing in the front-end direction. The height r1 of the foremost end portion, the outer diameter r2 of the bottom surface of the foremost end portion, and the height r3 of the outer diameter reduction portion satisfy the following formulas (1) and (2). 0.33 < r1 / r2 < 0.63... (1), 2.5 < r3 / r2 < 3.8... (2).

Description

Technical Field

[0001] The technology disclosed in this specification relates to a guide wire for guiding a medical device to a target position in a body cavity. Background Art

[0002] As a method for treating or examining a stenosis or occlusion (hereinafter referred to as a "lesion") in a blood vessel, a method using a catheter is widely performed. Generally, in order to guide a catheter to a lesion in a blood vessel, a guide wire is used. The guide wire includes a mandrel, a coil body covering the mandrel, and a front-side joint portion that joins the front end of the coil body to the front end of the mandrel.

[0003] For example, there is a guide wire aimed at penetrating a relatively hard lesion such as a lesion called Chronic Total Occlusion (abbreviated as "CTO"). Such a guide wire requires high penetration performance to reliably penetrate the lesion. In order to give the guide wire high penetration performance, there is known a guide wire in which the front end portion of the coil body is formed in a tapered shape that gradually tapers forward and the front joint portion is formed in a tapered shape that gradually tapers forward (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: U.S. Patent No. 6,669,652 Specification Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] As described above, a guide wire aimed at penetrating a relatively hard lesion requires high penetration performance. On the other hand, if the penetration performance of the guide wire is too high, there is a high concern of accidentally damaging the blood vessel. Therefore, a guide wire is required to have an appropriate range of penetration performance, that is, it can avoid damaging the blood vessel and can reliably penetrate even a relatively hard lesion. Currently, in a guide wire, no structure has been proposed for giving the guide wire such an appropriate range of penetration performance.

[0009] In this specification, a technology that can solve the above problems is disclosed.

[0010] Solutions to the Problems

[0011] The technology disclosed in this specification can be implemented, for example, in the following manner.

[0012] The guide wire disclosed in this specification includes: a mandrel; a coil body that covers the mandrel; and a front-end side joint that joins the front end of the coil body and the front end of the mandrel. The front-end side joint has: a substantially frustum-shaped outer diameter reducing portion whose outer diameter becomes smaller toward the front end direction; and a substantially spherical segment-shaped foremost end portion that is provided at the front end of the outer diameter reducing portion and whose outer diameter becomes smaller toward the front end direction. The height r1 of the foremost end portion, the outer diameter r2 of the bottom surface of the foremost end portion, and the height r3 of the outer diameter reducing portion satisfy the following formulas (1) and (2).

[0013] 0.33 < r1 / r2 < 0.63…(1)

[0014] 2.5 < r3 / r2 < 3.8…(2)

[0015] According to this guide wire, an appropriate range of penetration performance can be achieved, that is, damage to the body cavity can be avoided, and reliable penetration can be achieved even in a relatively hard lesion part.

[0016] In addition, the technology disclosed in this specification can be implemented in various ways. For example, it can be implemented in the form of a guide wire, its manufacturing method, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an explanatory diagram briefly showing the structure of the guide wire in this embodiment.

[0018] Figure 2 It shows Figure 1 the detailed structure of the front-end side joint of the guide wire shown.

[0019] Figure 3 It is an explanatory diagram showing an evaluation method of the penetration performance of the guide wire.

[0020] Figure 4 It is a graph showing the measurement results of the load received by the membrane when the guide wire is inserted.

[0021] Figure 5 It shows the results obtained in Figure 4 graphs of the measurement results under conditions different from those of the results obtained.

[0022] Figure 6 It shows the results obtained in Figure 4 graphs of the measurement results under the same conditions as those of the results obtained.

[0023] Figure 7 It shows the results obtained in Figure 5 graphs of the measurement results under the same conditions as those of the results obtained.

[0024] Figure 8It is a graph showing the suitability of the load received by the film in each combination of the most distal end ratio R1 and the outer diameter reduction ratio R2. Detailed implementation

[0025] A. Embodiment:

[0026] A-1. Structure of the guide wire:

[0027] Figure 1 It is an explanatory diagram briefly showing the structure of the guide wire in this embodiment. Figure 1 The longitudinal section (YZ section) of the guide wire 100 is shown. The positive Z-axis direction side is the distal end side (far side) inserted into the body, and the negative Z-axis direction side is the proximal end side (near side) operated by surgical staff such as doctors. And, Figure 1 A part of the illustration of the guide wire 100 is omitted. The same applies to the subsequent figures. In this specification, regarding the guide wire 100 and its respective constituent parts, the end on the distal end side is referred to as the "front end", the front end and its vicinity are referred to as the "distal end part", the end on the proximal end side is referred to as the "proximal end", and the proximal end and its vicinity are referred to as the "proximal end part". Figure 1 In it, a state where the entire guide wire 100 is in a straight line shape substantially parallel to the Z-axis direction is shown, but at least a part of the structure of the guide wire 100 has flexibility to the extent that it can be bent.

[0028] The guide wire 100 is a long medical device with flexibility that is inserted into a blood vessel mainly for the purpose of penetrating a relatively hard lesion part (such as CTO) in the blood vessel. The total length of the guide wire 100 is, for example, about 1500 mm to 2000 mm.

[0029] The guide wire 100 includes a mandrel 10, a coil body 20, a distal side joint 30, a proximal side joint 40, an intermediate joint 50, and a coating 60.

[0030] The mandrel 10 is composed of a thick diameter part 13 having a substantially constant outer diameter, a thin diameter part 11 located on the distal end side with respect to the thick diameter part 13 and having a substantially constant outer diameter smaller than that of the thick diameter part 13, and a tapered part 12 located between the thick diameter part 13 and the thin diameter part 11 and having an outer diameter gradually decreasing from the boundary position with the thick diameter part 13 toward the boundary position with the thin diameter part 11. The shape of the cross section (XY section) at each position of the mandrel 10 can take any shape, such as a circular shape or a flat plate shape. The outer diameter of the thick diameter part 13 is, for example, about 0.2 to 0.8 mm, and the outer diameter of the thin diameter part 11 is, for example, about 0.05 to 0.3 mm.

[0031] As the material for forming the mandrel 10, for example, stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloy, piano wire, etc. are used. The mandrel 10 can be formed entirely of the same material, or can be formed of different materials for each part.

[0032] The coil body 20 is a coil-shaped member formed in a hollow cylindrical shape by closely winding a single wire into a spiral. The coil body 20 is disposed on the outer periphery of the mandrel 10 so as to cover the mandrel 10. In the present embodiment, the coil body 20 covers the thin diameter portion 11 and the tapered portion 12 of the mandrel 10.

[0033] As the material for forming the coil body 20, for example, radiation-transmissive materials such as stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloy, piano wire, etc., or radiation-impermeable materials such as platinum, gold, tungsten, or their alloys are used. The coil body 20 can be formed entirely of the same material, or can be formed of different materials for each part.

[0034] The front-end side joint portion 30 is a member that joins the front end of the coil body 20 to the front end of the mandrel 10. That is, the front end of the coil body 20 and the front end of the mandrel 10 are fixedly installed in such a manner as to be buried inside the front-end side joint portion 30. The base-end side joint portion 40 is a member that joins the base end of the coil body 20 to the mandrel 10. The intermediate joint portion 50 is a member that joins a part between the front end and the base end of the coil body 20 to the mandrel 10. As the material for forming the front-end side joint portion 30, the base-end side joint portion 40, and the intermediate joint portion 50, for example, metal solders (Au-Sn alloy, Sn-Ag alloy, Sn-Pb alloy, Pb-Ag alloy, etc.), brazing materials (aluminum alloy brazing materials, silver brazing materials, gold brazing materials, etc.), adhesives (epoxy-based adhesives, etc.) are used. The materials for forming the front-end side joint portion 30, the base-end side joint portion 40, and the intermediate joint portion 50 can be the same or different. Moreover, for each of the front-end side joint portion 30, the base-end side joint portion 40, and the intermediate joint portion 50, it can be formed entirely of the same material, or can be formed of different materials for each part.

[0035] The coating 60 is disposed on the surface of the front-end side joint portion 30. As the material for forming the coating 60, for example, hydrophobic coating materials such as silicone oil, fluororesin, etc., or hydrophilic coating materials such as polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl alcohol, maleic anhydride copolymer, hyaluronic acid, etc. are used. In addition, in order to improve the penetrability of the guide wire 100 to the lesion portion, the coating 60 is preferably hydrophilic.

[0036] A-2. Detailed structure of the front-end side joint portion 30:

[0037] Figure 2 FIG. is an explanatory diagram showing the detailed structure of the front-end side joint portion 30, and enlargedly shows its longitudinal section (YZ section). The front-end side joint portion 30 has a fixed mounting portion 31, an outer diameter reducing portion 32, and a foremost end portion 33. The fixed mounting portion 31 is a portion that is located at the most proximal end side in the front-end side joint portion 30 and fixedly mounts the front end of the coil body 20 and the front end of the mandrel 10. The outer diameter reducing portion 32 is a portion having a substantially frustum shape that is located on the front end side of the fixed mounting portion 31 in the front-end side joint portion 30 and whose outer diameter becomes smaller toward the front end direction. The foremost end portion 33 is a portion having a substantially spherical segment shape that is provided at the front end of the outer diameter reducing portion 32 and whose outer diameter becomes smaller toward the front end direction.

[0038] The outer diameter of the front end of the outer diameter reducing portion 32 is the same as the outer diameter of the proximal end of the foremost end portion 33. Therefore, the front-end side joint portion 30 smoothly transitions from a shape in which the outer diameter linearly decreases toward the front end direction in the outer diameter reducing portion 32 to a shape in which the outer diameter curvilinearly decreases toward the front end direction in the foremost end portion 33. Also, the cross-sectional shape (XY section) of the outer diameter reducing portion 32 and the foremost end portion 33 is substantially circular.

[0039] In the guide wire 100 of the present embodiment, the height (dimension in the direction from the front end toward the proximal end) r1 of the foremost end portion 33 of the front-end side joint portion 30, the outer diameter r2 of the bottom surface (proximal end surface) of the foremost end portion 33, and the height r3 of the outer diameter reducing portion 32 satisfy the following formulas (1) and (2). In addition, the outer diameter r2 of the bottom surface of the foremost end portion 33 is the same as the outer diameter of the top surface (front end surface) of the outer diameter reducing portion 32. The outer diameter r2 of the bottom surface of the foremost end portion 33 can be, for example, about 0.1 mm to 0.5 mm.

[0040] 0.33 < r1 / r2 < 0.63...(1)

[0041] 2.5 < r3 / r2 < 3.8...(2)

[0042] Hereinafter, "r1 / r2" in the above formula (1) will be referred to as the "foremost end portion ratio R1", and "r3 / r2" in the above formula (2) will be referred to as the "outer diameter reducing portion ratio R2". A larger value of the foremost end portion ratio R1: r1 / r2 indicates that the shape of the foremost end portion 33 is sharp (small surface area), and a larger value of the outer diameter reducing portion ratio R2: r3 / r2 indicates that the shape of the outer diameter reducing portion 32 is sharp. Therefore, it can be said that the guide wire 100 that satisfies the above formulas (1) and (2) has a structure in which the shape of the foremost end portion 33 is neither too blunt nor too sharp, and the shape of the outer diameter reducing portion 32 is also neither too blunt nor too sharp. Since the guide wire 100 has such a structure, as will be described below, it has an appropriate range of penetration performance, that is, it can avoid damaging blood vessels and can reliably penetrate even in a hard lesion portion.

[0043] As a material for forming the front-end side joint portion 30, it is preferable to use a metal solder such as an Au-Sn alloy mainly composed of gold. It is known that such a metal solder mainly composed of gold has relatively high rigidity. If the front-end side joint portion 30 is formed of a metal solder mainly composed of gold, the front-end side joint portion 30 can have appropriate rigidity. Also, since the melting point of a metal solder mainly composed of gold such as an Au-Sn alloy is 400 degrees or lower, when forming the front-end side joint portion 30, a reduction in mechanical strength due to the thermal influence on the mandrel 10 and the coil body 20 can be suppressed. Further, since a metal solder mainly composed of gold such as an Au-Sn alloy has excellent radiation non-transmittance, the visibility of the front-end side joint portion 30 in a radiation fluoroscopic image can be improved.

[0044] A-3. Method for manufacturing the guide wire 100:

[0045] The guide wire 100 of the present embodiment can be manufactured, for example, by the following method. First, a mandrel 10 having a shape processed by mechanical grinding or the like and a coil body 20 formed by winding a coil wire are prepared. The mandrel 10 is inserted into the hollow portion of the coil body 20 to form a front-end side joint portion (30), a base-end side joint portion 40, and an intermediate joint portion 50 that join the coil body 20 and the mandrel 10. Further, when forming the front-end side joint portion 30, the general shape is arranged using, for example, a soldering iron or the like, thereby forming a precursor of the outer diameter reducing portion 32 and the foremost end portion 33. Thereafter, the surfaces of the precursor of the outer diameter reducing portion 32 and the foremost end portion 33 are polished using, for example, a device such as LEUTOR, thereby forming the outer diameter reducing portion 32 and the foremost end portion 33 having shapes that satisfy the above formulas (1) and (2). For example, by the above method, the guide wire 100 having the above structure can be manufactured.

[0046] Examples

[0047] The penetration performance of the guide wire was evaluated. In the evaluation, 30 types of guide wires having the same main structure as the guide wire 100 of the above-described present embodiment and different values of the foremost end portion ratio R1: r1 / r2 and the outer diameter reducing portion ratio R2: r3 / r2 of the front-end side joint portion 30 were used. Further, in each guide wire, the outer diameter r2 of the bottom surface of the foremost end portion 33 was in the range of 0.1 mm to 0.5 mm.

[0048] Figure 3It is an explanatory diagram showing an evaluation method for the penetration performance of a guide wire. A film ME with a thickness of approximately 0.85 mm, which simulates a hard lesion such as a chronic total occlusion (CTO), is placed on a force analyzer FA for measuring load. A guide wire GW with a length of approximately 1.5 mm is inserted into the film ME from the tip at a constant speed, and the loads applied to the film ME when the penetration depth d of the guide wire GW is 0.1 mm and 0.6 mm respectively are measured by the force analyzer FA. The state where the penetration depth d is 0.1 mm is a state in which substantially the entire frontmost part 33 of the front-side joint portion 30 is inserted into the film ME, and the state where the penetration depth d is 0.6 mm is a state in which substantially the entire frontmost part 33 of the front-side joint portion 30 and the outer diameter reduction portion 32 are inserted into the film ME. The load when the penetration depth d is 0.1 mm represents the ease of penetration of the tip of the guide wire GW into the lesion. That is, the smaller the load when the penetration depth d is 0.1 mm, the easier it is for the tip of the guide wire GW to penetrate into the lesion. Also, the load when the penetration depth d is 0.6 mm represents the ease of further penetration of the tip of the guide wire GW into the lesion after penetrating into the lesion. That is, the smaller the load when the penetration depth d is 0.6 mm, the easier it is for the guide wire GW to penetrate deeper after penetrating into the lesion.

[0049] Also, based on a qualitative evaluation assuming clinical conditions, appropriate ranges RA(0.1) and RA(0.6) of the loads when the penetration depths d are 0.1 mm and 0.6 mm respectively are set. That is, using a simulated lesion that simulates a CTO, a penetration test of the dura mater on the surface of the simulated lesion and an operability test of the guide wire GW within the simulated lesion are conducted, and based on the evaluation by doctors, appropriate ranges RA(0.1) and RA(0.6) of the loads corresponding to a penetration performance that is neither too low nor too high are set.

[0050] Figures 4 to 7 It is a graph showing the measurement results of the load applied to the film ME when the guide wire GW is inserted. Figure 4 and Figure 5 show the relationship between the frontmost part ratio R1: r1 / r2 and the load when the penetration depth d is 0.1 mm and when the penetration depth d is 0.6 mm, Figure 6 and Figure 7 show the relationship between the outer diameter reduction portion ratio R2: r3 / r2 and the load when the penetration depth d is 0.1 mm and when the penetration depth d is 0.6 mm. The measured values of each guide wire are plotted with the value of the frontmost part ratio R1: r1 / r2 or the outer diameter reduction portion ratio R2: r3 / r2 set on the horizontal axis and the load set on the vertical axis, and the regression lines derived from each measurement result are shown. Also, the above-mentioned appropriate load ranges RA(0.1) and RA(0.6) are shown, the plots within this range are shown as black dots, and the plots outside this range are shown as black triangles.

[0051] As Figure 4 andFigure 5 As shown, at any moment when the penetration depth d is 0.1 mm and 0.6 mm, it is confirmed that the larger the value of the tip ratio R1: r1 / r2, the smaller the load. Since it is considered as described above that if the value of the tip ratio R1: r1 / r2 is large, the shape of the tip 33 is sharp, the load received by the film ME from the guide wire GW is small. Similarly, as Figure 6 and Figure 7 shown, at any moment when the penetration depth d is 0.1 mm and 0.6 mm, it is confirmed that the larger the value of the outer diameter reduction ratio R2: r3 / r2, the smaller the load. Since it is considered as described above that if the value of the outer diameter reduction ratio R2: r3 / r2 is large, the shape of the outer diameter reduction portion 32 is sharp, the load received by the film ME from the guide wire GW is small.

[0052] Figure 8 is a graph showing the suitability of the load received by the film ME in each combination of the tip ratio R1 and the outer diameter reduction ratio R2. In this graph, the measured values of each guide wire are plotted with the value of the tip ratio R1: r1 / r2 set on the horizontal axis and the value of the outer diameter reduction ratio R2: r3 / r2 set on the vertical axis. For each combination of the tip ratio R1 and the outer diameter reduction ratio R2, a black dot is used to show the plot where the load is within the above-mentioned appropriate load ranges RA(0.1) and RA(0.6) at either of the penetration depths d of 0.1 mm and 0.6 mm, and a black triangle is used to show the plot where the load is outside the above-mentioned appropriate load range at one or both of the penetration depths d of 0.1 mm and 0.6 mm. As Figure 8 shown, if the value of the tip ratio R1: r1 / r2 is greater than 0.33 and less than 0.63, and the value of the outer diameter reduction ratio R2: r3 / r2 is greater than 2.5 and less than 3.8, then at either of the penetration depths d of 0.1 mm and 0.6 mm, the load is within the appropriate range. That is, it can be said that the penetration performance of the guide wire GW is within the appropriate range without satisfying the above-mentioned formulas (1) and (2).

[0053] Thus, in the guide wire 100, if the height r1 of the tip 33 of the front-side joint portion 30, the outer diameter r2 of the bottom surface of the tip 33, and the height r3 of the outer diameter reduction portion 32 satisfy the above-mentioned formulas (1) and (2), an appropriate range of penetration performance can be achieved, that is, damage to blood vessels can be avoided, and reliable penetration can be achieved even in a relatively hard lesion portion.

[0054] B. Variation:

[0055] The technology disclosed in this specification is not limited to the above-described embodiments, and can be deformed in various ways without departing from its gist. For example, the following deformations can also be made.

[0056] The structure of the guide wire 100 in the above-described embodiment is merely an example and can be variously deformed. For example, in the above-described embodiment, the mandrel 10 is composed of a thin-diameter portion 11, a tapered portion 12, and a thick-diameter portion 13, but the mandrel 10 may not have at least one of these three portions, or may have other portions in addition to these three portions.

[0057] In the guide wire 100 of the above-described embodiment, a proximal-side engagement portion 40 and an intermediate engagement portion 50 are provided, but at least one of them may be omitted.

[0058] In the guide wire 100 of the above-described embodiment, the coating 60 covers the surface of the distal-side engagement portion 30, but the coating 60 may also cover the surfaces of the coil body 20 and the mandrel 10. Additionally, the coating 60 may be omitted.

[0059] In the above-described embodiment, the coil body 20 covers the thin-diameter portion 11 and the tapered portion 12 of the mandrel 10, but the portion of the mandrel 10 covered by the coil body 20 can be arbitrarily changed. For example, the coil body 20 may only cover the thin-diameter portion 11 of the mandrel 10, or the coil body 20 may cover a part or all of the thick-diameter portion 13 in addition to covering the thin-diameter portion 11 and the tapered portion 12 of the mandrel 10.

[0060] In the above-described embodiment, the coil body 20 is formed into a hollow cylindrical shape by closely winding a single wire. However, the coil body 20 may also be formed into a hollow cylindrical shape by sparsely winding a single wire, or may be formed into a hollow cylindrical shape by winding a plurality of wires in a spiral. And it may be formed into a hollow cylindrical shape by winding a single stranded wire formed by stranding a plurality of wires in a spiral, or may be formed into a hollow cylindrical shape by winding a plurality of stranded wires formed by stranding a plurality of wires in a spiral.

[0061] The materials of the respective components in the above-described embodiment are merely examples and can be variously deformed. And the manufacturing method of the guide wire in the above-described embodiment is merely an example and can be variously deformed. For example, in the above-described embodiment, the outer-diameter reducing portion 32 and the foremost end portion 33 in the distal-side engagement portion 30 are integrally formed, but after forming the outer-diameter reducing portion 32, a precursor of the foremost end portion 33 may be formed at the front end of the outer-diameter reducing portion 32 using metal solder or the like, and the foremost end portion 33 may be formed by grinding this precursor. And in the above-described embodiment, the outer-diameter reducing portion 32 and the foremost end portion 33 having a predetermined shape are formed by grinding, but the outer-diameter reducing portion 32 and the foremost end portion 33 may also be formed by other known methods (such as casting).

[0062] In the above-described embodiment, a guide wire for guiding a catheter to a target position in a blood vessel has been described as an example. However, the technology disclosed in this specification can equally be applied to a guide wire for guiding a medical device to a target position in a body cavity (such as a blood vessel, digestive tract, urinary tract, etc.).

[0063] Explanation of symbols

[0064] 10—mandrel, 11—thin diameter portion, 12—tapered portion, 13—thick diameter portion, 20—coil body, 30—front end side joint portion, 31—fixed mounting portion, 32—outer diameter reducing portion, 33—frontmost end portion, 40—base end side joint portion, 50—intermediate joint portion, 60—coating, 100—guide wire, FA—force analyzer, GW—guide wire, ME—membrane.

Claims

1. A guide wire, characterized in that, Comprising: A mandrel; A coil body that covers the above-mentioned mandrel; and A front-end side joint that joins the front end of the above-mentioned coil body and the front end of the above-mentioned mandrel, The above-mentioned front-end side joint has: A substantially frustum-shaped outer diameter reducing portion whose outer diameter becomes smaller toward the front end direction; and A substantially spherical segment-shaped foremost end portion that is provided at the front end of the above-mentioned outer diameter reducing portion and whose outer diameter becomes smaller toward the front end direction, The height r1 of the above-mentioned foremost end portion, the outer diameter r2 of the bottom surface of the above-mentioned foremost end portion, and the height r3 of the above-mentioned outer diameter reducing portion satisfy the following formulas (1) and (2): 0.33＜r1 / r2＜0.63…(1) 2.5＜r3 / r2＜3.8…(2)。 2. The guide wire according to claim 1, characterized in that It further comprises a coating that covers the above-mentioned front-end side joint.

3. The guide wire according to claim 2, characterized in that The above-mentioned coating and the above-mentioned front-end side joint jointly and completely surround the front end of the above-mentioned coil body and the front end of the above-mentioned mandrel.

4. The guide wire according to claim 1, characterized in that It further comprises a base-end side joint that joins the base end of the above-mentioned coil body and the above-mentioned mandrel.

5. The guide wire according to claim 1, characterized in that It further comprises an intermediate joint that joins a part between the front end and the base end of the above-mentioned mandrel and the above-mentioned coil body.

6. The guide wire according to claim 1, characterized in that The above-mentioned mandrel has: A first part having a substantially constant first outer diameter; A second part that is located on the front-end side with respect to the above-mentioned first part and has a substantially constant second outer diameter smaller than the above-mentioned first outer diameter; and A third part that is located between the above-mentioned first part and the above-mentioned second part and whose outer diameter gradually becomes smaller from its boundary position with the above-mentioned first part toward its boundary position with the above-mentioned second part.

7. The guide wire according to claim 6, characterized in that It further comprises a base-end side joint that joins the base end of the above-mentioned coil body and the above-mentioned first part.

8. The guide wire according to claim 7, characterized in that The above-mentioned base-end side joint is located on the above-mentioned first part adjacent to the above-mentioned third part.

9. The guide wire according to claim 6, characterized in that It further comprises an intermediate joint that joins a part between the front end and the base end of the above-mentioned second part and the above-mentioned coil body.

10. The guide wire according to claim 1, characterized in that The front end of the above-mentioned coil body and the front end of the above-mentioned mandrel are buried in the above-mentioned front-end side joint.

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