Guide wire
The guidewire design addresses the stiffness gap by using a first wire with varying cross-sectional areas and a second wire with a higher modulus, reducing the rigidity gap and improving durability and flexibility.
Patent Information
- Application Number
- JP2024099229
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-06-20
- Publication Date
- 2026-01-08
AI Technical Summary
Known guidewires have a stiffness gap near the interface between the first and second wires, which can be improved.
A guidewire design with a first wire having a first large-area and first small-area portion, and a second wire with a higher elastic modulus, where the second small-area portion is joined to the first small-area portion, and the distance from the joint surface to the tip of the second large-area portion is longer than to the base end of the first large-area portion, reducing the rigidity gap.
The guidewire design effectively reduces the rigidity gap near the joint surface, enhancing durability and flexibility, as demonstrated by improved rotation durability and bending test results.
Smart Images
Figure 2026001753000001_ABST
Abstract
Description
[Technical Field]
[0001] The technology disclosed herein relates to guidewires. [Background technology]
[0002] A known guidewire includes a distal portion (first wire) made of a first metallic material and a proximal portion (second wire) made of a second metallic material different from the first metallic material. The proximal end of the distal portion and the distal end of the proximal portion are joined together. The diameter of the proximal end of the distal portion is smaller than the diameter of the distal end, and the diameter of the distal end of the proximal portion is smaller than the diameter of the proximal end of the proximal portion (see, for example, Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Patent No. 7023115 Summary of the Invention [Problem to be solved by the invention]
[0004] Known guidewires have room for reducing the stiffness gap near the interface between the first and second wires.
[0005] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]
[0006] The technology disclosed in this specification can be realized, for example, in the following forms.
[0007] (1) A guidewire disclosed in this specification comprises a first wire and a second wire. The first wire has a first large-area portion and a first small-area portion. The first large-area portion has a constant cross-sectional area in the axial direction of the guidewire. The first small-area portion is located proximally of the first large-area portion. The cross-sectional area of the first small-area portion is smaller than the cross-sectional area of the first large-area portion. The second wire is located proximally of the first wire and is formed of a material having a higher elastic modulus than the material of the first wire. The second wire has a second large-area portion and a second small-area portion. The cross-sectional area of the second large-area portion is constant in the axial direction of the guidewire. The second small-area portion is located distally of the second large-area portion. The cross-sectional area of the second small-area portion is smaller than the cross-sectional area of the second large-area portion. The distal end of the second small-area portion is joined to the proximal end of the first small-area portion. The distance from the joint surface between the first small area portion and the second small area portion to the tip of the second large area portion is longer than the distance from the joint surface to the base end of the first large area portion.
[0008] In this guide wire, the distance from the joint surface to the tip of the second large area section is longer than the distance from the joint surface to the base end of the first large area section, thereby reducing the rigidity gap near the joint surface between the first wire and the second wire.
[0009] (2) The guidewire may not include a tube that covers only a specific portion of the guidewire from the base end of the first large-area section to the tip of the second large-area section. This guidewire can reduce the rigidity gap near the joint surface between the first wire and the second wire.
[0010] (3) In the above guidewire, the distance from the joint surface to the base end of the first large-area section may be three-quarters or less of the distance from the joint surface to the tip end of the second large-area section. In this guidewire, the distance from the joint surface to the tip end of the second large-area section is sufficiently longer than the distance from the joint surface to the base end of the first large-area section, so that the rigidity gap near the joint surface between the first wire and the second wire can be effectively reduced.
[0011] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a guidewire and a method for manufacturing the guidewire. [Brief explanation of the drawings]
[0012] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating a guide wire according to an embodiment. [Figure 2] FIG. 1 is an explanatory diagram showing the periphery of a joint surface between a first wire and a second wire; [Figure 3] An explanatory diagram conceptually showing the rigidity of the guidewire near the joint surface. [Figure 4] An explanatory diagram conceptually showing the rigidity of the guidewire near the joint surface. [Figure 5] An explanatory diagram conceptually showing the rigidity of the guidewire near the joint surface. [Figure 6] An explanatory diagram showing the rotation durability test method [Figure 7] Example image showing the results of a guidewire bending test [Figure 8] Example image showing the results of a guidewire bending test DETAILED DESCRIPTION OF THE INVENTION
[0013] (Basic configuration of guidewire 10) FIG. 1 is an explanatory diagram schematically illustrating a guidewire 10 according to an embodiment. FIG. 1 shows a side view of a core shaft 100 and longitudinal cross sections of a coil 200, a distal joint 300, and a proximal joint 400. In FIG. 1, mutually orthogonal X, Y, and Z axes are shown to identify directions. In this embodiment, a longitudinal cross section is a cross section (YZ cross section) parallel to the longitudinal direction (Z-axis direction) of the guidewire 10, and a transverse cross section is a cross section (XY cross section) perpendicular to the longitudinal direction of the guidewire 10. A portion of the guidewire 10 is not shown in FIG. 1. In FIG. 1, the positive Z-axis side corresponds to the distal end (distal side) that is inserted into the body, and the negative Z-axis side corresponds to the proximal end (proximal side) that is manipulated by the operator. FIG. 1 illustrates a state in which the guidewire 10 as a whole is linear and substantially parallel to the Z-axis direction. The guidewire 10 is flexible enough to be bent. These points also apply to the subsequent figures. In this specification, for the guide wire 10 and each component of the guide wire 10, the distal end is referred to as the "tip," the distal end and its vicinity are referred to as the "tip portion," the proximal end is referred to as the "proximal end," and the proximal end and its vicinity are referred to as the "proximal end portion."
[0014] The guidewire 10 is a medical device that is inserted into a biological lumen such as a blood vessel. The guidewire 10 is used, for example, to guide another medical device such as a catheter to a desired position within the biological lumen. The total length of the guidewire 10 is, for example, approximately 1500 mm or more and 3000 mm or less.
[0015] The guidewire 10 includes a core shaft 100, a coil 200, a distal joint 300, and a proximal joint 400.
[0016] The core shaft 100 is an elongated member extending along the Z-axis direction. The core shaft 100 includes a first wire 110 and a second wire 120.
[0017] The first wire 110 is a portion of the core shaft 100 that includes the tip. The first wire 110 has a base end 111, a tip end 116, and an intermediate portion 118. The tip end 116, the intermediate portion 118, and the base end 111 are arranged in this order from the tip side to the base end side of the core shaft 100. The tip end 116 is a portion that includes the tip of the first wire 110. The outer diameter of the tip end 116 is constant from the tip to the base end. The intermediate portion 118 is a portion located between the tip end 116 and the base end 111. The outer diameter of the intermediate portion 118 gradually increases from the tip to the base end. The base end 111 is a portion that includes the base end of the first wire 110. The outer diameter of the base end 111 will be described later.
[0018] The second wire 120 is a portion located closer to the base end than the first wire 110. A tip 120d of the second wire 120 is joined to the base end 110p of the first wire 110.
[0019] The second wire 120 is formed of a material having a higher elastic modulus than the material of the first wire 110. The materials of the first wire 110 and the second wire 120 are not particularly limited, except that the second wire 120 is formed of a material having a higher elastic modulus than the material of the first wire 110. The first wire 110 and the second wire 120 are each formed of stainless steel (SUS302, SUS304, SUS316, etc.), a superelastic alloy such as a Ni-Ti alloy, piano wire, a nickel-chromium alloy, a cobalt alloy, tungsten, etc. In this embodiment, the material of the first wire 110 is, for example, a Ni-Ti alloy, and the material of the second wire 120 is, for example, a stainless steel or a cobalt-chromium alloy. Details of the core shaft 100 will be described later.
[0020] The coil 200 is a coil-shaped member formed into a hollow cylinder. The coil 200 extends along the Z-axis direction. The coil 200 covers the core shaft 100 from the outside. The material of the coil 200 is not particularly limited. The coil 200 is formed from, for example, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, piano wire, platinum, gold, tungsten, cobalt alloy, nickel-chromium alloy, etc.
[0021] The distal joint portion 300 is a member that joins the distal end of the core shaft 100 and the distal end of the coil 200. The proximal joint portion 400 is a member that joins the core shaft 100 and the proximal end of the coil 200. The materials of the distal joint portion 300 and the proximal joint portion 400 are not particularly limited. The distal joint portion 300 and the proximal joint portion 400 are formed, for example, from metal solder (Au—Sn alloy, Sn—Ag alloy, Sn—Pb alloy, Pb—Ag alloy, etc.), brazing material (aluminum alloy brazing, silver brazing, gold brazing, etc.), adhesive (epoxy adhesive, etc.), etc. The distal joint portion 300 and the proximal joint portion 400 may be formed from the same material or from different materials.
[0022] (Detailed configuration of core shaft 100) 2 is an explanatory diagram showing the vicinity of a joint surface CS between the first wire 110 and the second wire 120. The base end 111 of the first wire 110 has a first large-area portion 112 and a first small-area portion 114. The second wire 120 has a second large-area portion 122 and a second small-area portion 124.
[0023] The first large-area portion 112 is a part of the first wire 110. The cross-sectional area of the first large-area portion 112 is constant in the axial direction of the guidewire 10. The first small-area portion 114 is a part of the first wire 110. The first small-area portion 114 is located closer to the proximal end than the first large-area portion 112. The first small-area portion 114 is adjacent to the first large-area portion 112 in the axial direction of the guidewire 10. The cross-sectional area of the first small-area portion 114 is constant in the axial direction of the guidewire 10 and is smaller than the cross-sectional area of the first large-area portion 112. The cross-sectional area of the first small-area portion 114 at the portion where the cross-sectional area is constant may be, for example, 0.4 to 0.9 times the cross-sectional area of the first large-area portion 112, or 0.5 to 0.8 times the cross-sectional area of the first large-area portion 112. The base end of the first small area portion 114 is equal to the base end 110p of the first wire 110. The outer shape of the cross section of the first large area portion 112 is, for example, circular. The outer shape of the cross section of the first small area portion 114 is, for example, circular. The outer diameter of the first large area portion 112 is constant from the tip to the base end. The outer diameter of the first small area portion 114 is smaller than the outer diameter of the first large area portion 112 and is constant from the tip to the base end.
[0024] The second large-area portion 122 is a part of the second wire 120. The cross-sectional area of the second large-area portion 122 is constant in the axial direction of the guidewire 10. The second small-area portion 124 is a part of the second wire 120. The second small-area portion 124 is located more distally than the second large-area portion 122. The second small-area portion 124 is adjacent to the second large-area portion 122 in the axial direction of the guidewire 10. The cross-sectional area of the second small-area portion 124 is constant in the axial direction of the guidewire 10 and is smaller than the cross-sectional area of the second large-area portion 122. The cross-sectional area of the second small-area portion 124 at the portion where the cross-sectional area is constant may be, for example, 0.4 to 0.9 times the cross-sectional area of the second large-area portion 122, or 0.5 to 0.8 times the cross-sectional area of the second large-area portion 122. The tip of the second small-area portion 124 is equal to the tip 120d of the second wire 120. The tip of the second small-area portion 124 is joined to the base end of the first large-area portion 112, for example, by welding. A joint surface CS is formed by joining the tip of the second small-area portion 124 and the base end of the first large-area portion 112. The outer shape of the cross section of the second large-area portion 122 is, for example, circular. The outer shape of the cross section of the second small-area portion 124 is, for example, circular. The outer diameter of the second large-area portion 122 is constant from the tip to the base end. The outer diameter of the second small-area portion 124 is smaller than the outer diameter of the second large-area portion 122 and is constant from the tip to the base end.
[0025] In this embodiment, the length of the second small-area portion 124 in the axial direction of the guidewire 10 is longer than the length of the first small-area portion 114 in the axial direction of the guidewire 10. In other words, the distance L2 from the joining surface CS to the distal end of the second large-area portion 122 is longer than the distance L1 from the joining surface CS to the proximal end of the first large-area portion 112. The distance L1 may be three-quarters or less of the distance L2, or may be one-half or less of the distance L2.
[0026] When the specific portion SP in the guidewire 10 is defined as the portion from the proximal end of the first large-area portion 112 to the distal end of the second large-area portion 122, the guidewire 10 does not include a tube that covers only the specific portion SP. The specific portion SP in the guidewire 10 may be exposed to the outside. Alternatively, the guidewire 10 may include a tube that covers the specific portion SP and a portion of the core shaft 100 that is distal to the specific portion SP. Alternatively, the guidewire 10 may include a tube that covers the specific portion SP and a portion of the core shaft 100 that is proximal to the specific portion SP.
[0027] 3 to 5 are explanatory diagrams conceptually illustrating the rigidity of the guidewire near the joint surface CS. FIG. 3 conceptually illustrates the rigidity of the guidewire 10 of the embodiment near the joint surface CS. FIG. 4 conceptually illustrates the rigidity of the guidewire 10 of the embodiment near the joint surface CS (hereinafter referred to as "Aspect X"), which is similar to the guidewire 10 of the embodiment except that the distances L1 and L2 are equal. FIG. 5 conceptually illustrates the rigidity of the guidewire 10 of the embodiment near the joint surface CS (hereinafter referred to as "Aspect Y"), which is similar to the guidewire 10 of the embodiment except that the guidewire 10 does not have the first small-area portion 114 and the second small-area portion 124. In other words, the guidewire of Aspect Y is a guidewire in which the portions corresponding to the first large-area portion 112 and the second large-area portion 122 of the guidewire 10 of the embodiment are directly joined to each other. The sum of the distances L1 and L2 in the guidewire 10 of the embodiment is equal to the sum of the distances L1 and L2 in the guidewire of Aspect X.
[0028] The rigidity of each portion of the guidewire in the axial direction is proportional to the cross-sectional area of the core shaft when the cross-sectional shapes of the core shaft at each portion are similar to each other. In other words, the smaller the cross-sectional area of the core shaft in the axial direction of the guidewire, the lower the rigidity of that portion. As shown in FIG. 3 , in the guidewire 10 of the embodiment, the rigidity of the first small-area portion 114 is relatively lower than the rigidity of the first large-area portion 112, and the rigidity of the second small-area portion 124 is relatively lower than the rigidity of the second large-area portion 122. Therefore, the guidewire 10 of the embodiment has a smaller rigidity gap near the joint surface CS than the guidewire of aspect Y. Similarly, as shown in FIG. 4 , in the guidewire of aspect X, the rigidity of the first small-area portion 114 is relatively lower than the rigidity of the first large-area portion 112, and the rigidity of the second small-area portion 124 is relatively lower than the rigidity of the second large-area portion 122. Therefore, the guidewire of aspect X, like the guidewire 10 of the embodiment, has a reduced rigidity gap near the joint surface CS compared to the guidewire of aspect Y.
[0029] Furthermore, in the guidewire 10 of the embodiment, the distance L2 is longer than the distance L1. In other words, in the guidewire 10 of the embodiment, the length of the portion of the second wire 120 where the rigidity is relatively low is longer compared to the guidewire of aspect X. Therefore, in the guidewire 10 of the embodiment, the change in rigidity near the joint surface CS is more gradual compared to the guidewire of aspect X, and the rigidity gap near the joint surface CS is reduced.
[0030] The core shaft 100 can be manufactured by, for example, the following manufacturing method. First, an operator prepares a first wire rod made of a first material to be used as the first wire 110, and a second wire rod made of a second material to be used as the second wire 120. The second material has a higher elastic modulus than the first material. For example, a Ni-Ti alloy is used as the first material, and stainless steel is used as the second material. The operator grinds the ends of the first wire rod and the second wire rod, respectively, using, for example, a centerless grinding machine. This produces the first wire 110 having a first large-area portion 112 and a first small-area portion 114, and the second wire 120 having a second large-area portion 122 and a second small-area portion 124. The operator then joins the base end of the first small-area portion 114 of the first wire 110 to the tip end of the second small-area portion 124 of the second wire 120 by welding. Thereafter, the worker can manufacture the core shaft 100 by, for example, appropriately removing burrs near the joint surface CS between the first small-area portion 114 and the second small-area portion 124. In the above manufacturing method, the worker may grind the first wire rod and the second wire rod after welding the first wire rod and the second wire rod. In the above manufacturing method, the worker may impart superelasticity to the Ni-Ti alloy by, for example, performing heat treatment on the Ni-Ti alloy after grinding the first wire rod and the second wire rod.
[0031] (Effects of this embodiment) As described above, the guidewire 10 of this embodiment includes a first wire 110 and a second wire 120. The first wire 110 has a first large-area portion 112 and a first small-area portion 114. The first large-area portion 112 has a constant cross-sectional area in the axial direction of the guidewire 10. The first small-area portion 114 is located closer to the proximal end than the first large-area portion 112. The cross-sectional area of the first small-area portion 114 is smaller than the cross-sectional area of the first large-area portion 112. The second wire 120 is located closer to the proximal end than the first wire 110 and is formed of a material having a higher elastic modulus than the material of the first wire 110. The second wire 120 has a second large-area portion 122 and a second small-area portion 124. The cross-sectional area of the second large-area portion 122 is constant in the axial direction of the guidewire 10. The second small-area portion 124 is located closer to the tip than the second large-area portion 122. The cross-sectional area of the second small-area portion 124 is smaller than the cross-sectional area of the second large-area portion 122. The tip of the second small-area portion 124 is joined to the base end of the first small-area portion 114. The distance L2 from the joint surface CS between the first small-area portion 114 and the second small-area portion 124 to the tip of the second large-area portion 122 is longer than the distance L1 from the joint surface CS to the base end of the first large-area portion 112.
[0032] In the guide wire 10 of this embodiment, the distance L2 from the joint surface CS to the tip of the second large area portion 122 is longer than the distance L1 from the joint surface CS to the base end of the first large area portion 112, thereby reducing the rigidity gap near the joint surface CS between the first wire 110 and the second wire 120.
[0033] The guidewire 10 of this embodiment does not include a tube that covers only the specific portion SP, which is from the base end of the first large-area portion 112 to the tip end of the second large-area portion 122 of the guidewire 10. The guidewire 10 of this embodiment can reduce the rigidity gap near the joint surface CS between the first wire 110 and the second wire 120.
[0034] In the guidewire 10 of this embodiment, the distance L1 from the joint surface CS to the base end of the first large-area portion 112 is three-quarters or less of the distance L2 from the joint surface CS to the tip of the second large-area portion 122. In the guidewire 10 of this embodiment, the distance L2 from the joint surface CS to the tip of the second large-area portion 122 is sufficiently longer than the distance L1 from the joint surface CS to the base end of the first large-area portion 112, so the rigidity gap near the joint surface CS between the first wire 110 and the second wire 120 can be effectively reduced.
[0035] (Performance evaluation) Performance evaluation of the guidewire 10 of this embodiment will be described below. As a first performance evaluation, the rotation durability of a plurality of guidewire 10 samples having different distances L1 and wire diameters at the specific portion SP was evaluated. As a second performance evaluation, a bending test was conducted on the guidewire 10 of this embodiment and the guidewire of aspect Y described above.
[0036] First, the method of the rotational durability test will be described. FIG. 6 is an explanatory diagram illustrating the method of the rotational durability test. FIG. 6 shows a guidewire 10, a jig 20, and a rotator 22. The jig 20 is a cylindrical member. The jig 20 has a semicircular shape with a radius R when viewed in a direction intersecting the direction in which the jig 20 extends. In this performance evaluation, the radius R was 15 mm. The evaluator inserted the guidewire 10 from one end of the hollow portion of the jig 20 and pushed the guidewire 10 forward until the joint surface CS between the first wire 110 and the second wire 120 reached the midpoint between the one end and the other end of the hollow portion. In this state, the evaluator rotated the guidewire 10 using the rotator 22 and measured the number of rotations of the guidewire 10 until the first wire 110 and the second wire 120 broke, thereby evaluating the rotational durability. The multiple guide wire 10 samples used to evaluate rotational durability all had a first wire 110 made of Ni-Ti alloy and a second wire 120 made of SUS302, the wire diameters of the first large area portion 112 and the second large area portion 122 were each 0.34 mm, and the distance L2 was 20 mm.
[0037] Next, the bending test method will be described. The evaluator visually confirmed the shape of the guidewire when the guidewire was bent by fixing the portion of the guidewire on the first wire 110 side in the axial direction and the portion of the guidewire on the second wire 120 side in the axial direction.
[0038] Table 1 shows the results of the rotation durability test.
[0039] [Table 1]
[0040] Table 1 shows the effects of the distance L1 and the wire diameter at the specific portion SP on the rotation durability of the guidewire 10. The numbers in the table indicate the number of rotations of the guidewire 10 until the first wire 110 and the second wire 120 break. The results of the rotation durability test revealed that the guidewire 10 has extremely good rotation durability. That is, referring to Table 1, it is clear that the rotation durability of the guidewire 10 is extremely good when the wire diameter of the specific portion SP is 0.28 mm and the distance L1 is 7 mm or more and 10 mm or less.
[0041] 7 and 8 are example images showing the results of a bending test of a guidewire. FIG. 7 shows the results of a bending test of the guidewire 10 of the above embodiment. FIG. 8 shows the results of a bending test of a guidewire of a configuration similar to the guidewire 10 of the above embodiment (the above-mentioned configuration Y) except that it does not have the first small-area portion 114 and the second small-area portion 124. In the bending test of the guidewire, the guidewire 10 of the embodiment and the guidewire of configuration Y both use a Ni-Ti alloy as the material for the first wire 110 and SUS302 as the material for the second wire 120.
[0042] 7 and 8, the guidewire 10 of the embodiment has a more gently curved shape overall than the guidewire of aspect Y. In other words, it was confirmed that the guidewire 10 of the embodiment has a reduced rigidity gap compared to the guidewire of aspect Y, and the curvature at each position near the joint surface CS is more constant.
[0043] (Variation) The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.
[0044] The guidewire 10 in the above embodiment is merely an example and can be modified in various ways. For example, the guidewire does not need to include a coil.
[0045] The material of the guidewire 10 in the above embodiment is merely an example.
[0046] The distance from the joining surface to the base end of the first large area portion does not necessarily have to be three-quarters or less of the distance from the joining surface to the tip end of the second large area portion.
[0047] The cross-sectional area of the first small area section may be constant in the axial direction of the guidewire, or may have a tapered section in which the cross-sectional area gradually increases from the joint surface toward the base end of the first large area section, or may have a section in which the cross-sectional area is constant from the joint surface toward the base end of the first large area section and a tapered section in which the cross-sectional area gradually increases from the tip of the constant section toward the base end of the first large area section.
[0048] The cross-sectional area of the second small-area section may be constant in the axial direction of the guidewire, or may have a tapered section in which the cross-sectional area gradually increases from the joint surface toward the tip of the second large-area section, or may have a section in which the cross-sectional area is constant from the joint surface toward the tip of the second large-area section and a tapered section in which the cross-sectional area gradually increases from the base end of the constant section toward the tip of the second large-area section.
[0049] The value obtained by subtracting the volume of the second small-area portion from the product of the distance from the joint surface between the first small-area portion and the second small-area portion to the tip of the second large-area portion and the area of the cross-section of the second large-area portion may be greater than the value obtained by subtracting the volume of the first small-area portion from the product of the distance from the joint surface to the base end of the first large-area portion and the area of the cross-section of the first large-area portion. Also, the value obtained by subtracting the volume of the second small-area portion from the product of the distance from the joint surface between the first small-area portion and the second small-area portion to the tip of the second large-area portion and the area of the cross-section of the second large-area portion may be three-quarters or less, or one-half or less, of the value obtained by subtracting the volume of the first small-area portion from the product of the distance from the joint surface to the base end of the first large-area portion and the area of the cross-section of the first large-area portion.
Claims
1. A guidewire (10), A first wire (110), a first large area portion (112) whose cross-sectional area is constant in the axial direction of the guide wire (10); a first wire (110) having a first small area portion (114) located proximal to the first large area portion (112), the first small area portion (114) having a cross-sectional area smaller than the cross-sectional area of the first large area portion (112); a second wire (120) located on the proximal side of the first wire (110) and made of a material having a higher elastic modulus than the material of the first wire (110), a second large area portion (122) whose cross-sectional area is constant in the axial direction of the guide wire (10); a second wire (120) having a second small area portion (124) located distally of the second large area portion (122), the second small area portion (124) having a cross-sectional area smaller than the cross-sectional area of the second large area portion (122); Equipped with The tip of the second small area portion (124) is joined to the base end of the first small area portion (114), A guide wire (10), wherein a distance (L2) from a junction (CS) between the first small area portion (114) and the second small area portion (124) to the tip of the second large area portion (122) is longer than a distance (L1) from the junction (CS) to the base end of the first large area portion (112).
2. 2. The guidewire (10) of claim 1, A guidewire (10) that does not have a tube that covers only a specific portion (SP) of the guidewire (10) from the base end of the first large area portion (112) to the tip of the second large area portion (122).
3. A guidewire (10) according to claim 1 or claim 2, A guide wire (10) in which the distance (L1) from the joining surface (CS) to the base end of the first large area portion (112) is less than three-quarters of the distance (L2) from the joining surface (CS) to the tip end of the second large area portion (122).
Citation Information
Patent Citations
Mechanisms for improving stiffness transition across dissimilar metal weld joints
JP7023115B2