Guidewire

Abstract

To provide a guide wire capable of relaxing a rigidity gap on a core shaft, and capable of improving bond strength of first and second shafts.SOLUTION: A guide wire has a core shaft, the core shaft comprises: a first shaft provided at a tip side of the core shaft; and a second shaft which has a tip end part to which a base end part of the first shaft is joined, and is formed of a material different from a material of the first shaft. On an outer peripheral surface of the tip end part of the second shaft, a groove is formed, the groove extending from the tip end of the second shaft to the base end side of the second shaft. The base end part of the first shaft is inserted into the groove on the second shaft.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed herein relates to medical guidewires. [Background technology]

[0002] Methods using catheters are widely used as methods for treating or examining stenosis or occlusion (hereinafter referred to as "lesions") in blood vessels, etc. Generally, a guidewire is used to guide the catheter to the lesion in the blood vessel, etc. The guidewire has a core shaft made of, for example, a metallic material (see, for example, Patent Document 1).

[0003] The core shaft has a stainless steel ribbon and a nickel-titanium alloy core, and the base end of the ribbon and the tip end of the core are joined together. Specifically, the outer circumferential surface of the base end of the ribbon and the outer circumferential surface of the tip end of the core are joined together in a state where they face each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2006-519069 Summary of the Invention [Problem to be solved by the invention]

[0005] In the core shaft of the above-mentioned conventional guidewire, the outer circumferential surface of the proximal end of the ribbon is simply joined to the outer circumferential surface of the distal end of the core, resulting in a large rigidity gap between the joint between the ribbon and the core and the portion distal or proximal to the joint.Furthermore, the joint area between the ribbon and the core cannot be sufficiently secured, resulting in low joint strength between the ribbon and the core.

[0006] This issue is common to guidewires in which different materials are bonded together. In particular, the nickel-titanium alloy core has superelastic properties, which creates a large difference in rigidity between it and the stainless steel ribbon, making bonding the two difficult.

[0007] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0008] The technology disclosed in this specification can be realized, for example, in the following forms.

[0009] (1) The guidewire disclosed in this specification is a guidewire including a core shaft, the core shaft including a first shaft located at the distal end of the core shaft, and a second shaft having a distal end joined to a proximal end of the first shaft and made of a material different from that of the first shaft, wherein a groove is formed on the outer surface of the distal end of the second shaft, extending from the distal end of the second shaft toward the proximal end of the second shaft, the proximal end of the first shaft is inserted into the groove of the second shaft, and at least both sides of the proximal end of the first shaft in the circumferential direction around the axis of the core shaft are joined to the inner wall surfaces of the second shaft that form the groove.

[0010] In this guidewire, as described above, the proximal end of the first shaft is inserted into a groove formed in the outer circumferential surface of the second shaft. Therefore, in this guidewire, the rigidity of the joint between the first and second shafts is reduced by the amount of the groove formed in the second shaft, thereby reducing the rigidity gap in the core shaft compared to conventional configurations in which the outer circumferential surfaces of the shafts are simply joined together. Furthermore, in this guidewire, the proximal end of the first shaft is sandwiched between the inner wall surfaces that form the groove in the second shaft. Therefore, in this guidewire, the joint strength between the first and second shafts can be improved compared to the conventional configurations.

[0011] (2) In the above-described guidewire, in a cross section of the joint portion between the first shaft and the second shaft, the contour line of the portion of the outer circumferential surface of the proximal end of the first shaft that is exposed from the groove of the second shaft is located closer to the circumscribing circle of the second shaft than to the circumscribing circle of the first shaft. In this guidewire, in a cross section of the joint portion, the contour line of the portion of the outer circumferential surface of the proximal end of the first shaft that is exposed from the groove of the second shaft is located closer to the circumscribing circle of the second shaft than to the circumscribing circle of the first shaft. Therefore, with this guidewire, it is possible to suppress a decrease in rotation performance caused by the protrusion of the first shaft relative to the second shaft, compared to a configuration in which the contour line of the portion of the second shaft that is exposed from the groove is located closer to the circumscribing circle of the first shaft.

[0012] (3) In the above-described guidewire, the bottom surface of the groove at the proximal end of the second shaft may be configured to be inclined so as to approach the outer circumferential surface of the second shaft as it approaches the proximal end of the second shaft. In this guidewire, the bottom surface of the groove at the proximal end of the second shaft is inclined so as to approach the outer circumferential surface of the second shaft as it approaches the proximal end of the second shaft. Therefore, with this guidewire, stress concentration caused by the presence of a step between the bottom surface of the groove and the outer circumferential surface of the second shaft can be alleviated compared to a configuration in which the bottom surface of the groove at the proximal end of the second shaft is not inclined.

[0013] (4) In the above guidewire, the bottom surface of the groove in the second shaft may have an inclined portion that approaches the central axis of the second shaft as it approaches the tip of the second shaft. In this guidewire, the bottom surface of the groove in the second shaft has an inclined portion that approaches the central axis of the second shaft as it approaches the tip of the second shaft. Therefore, this guidewire can suppress misalignment of the central axes of the first shaft and the second shaft compared to a configuration in which the bottom surface of the groove in the second shaft does not have the inclined portion.

[0014] (5) In the above guidewire, the length of the proximal end of the first shaft in the depth direction of the groove may be greater than the depth of the groove of the second shaft. This guidewire can suppress a decrease in strength of the proximal end of the first shaft compared to, for example, a configuration in which the length of the proximal end of the first shaft is shorter than the depth of the groove of the second shaft.

[0015] (6) In the above guidewire, the length of the proximal end of the first shaft in the depth direction of the groove may be configured to be smaller than the depth of the groove of the second shaft. With this guidewire, it is possible to suppress a decrease in the rotation performance of the guidewire caused by the first shaft protruding relative to the second shaft, compared to, for example, a configuration in which the length of the proximal end of the first shaft is larger than the depth of the groove of the second shaft.

[0016] (7) In the above guidewire, the bottom surface of the groove of the second shaft and the surface of the proximal end of the first shaft facing the bottom surface of the groove may be flat and in surface contact with each other. This guidewire can improve the stability and torque transmission of the proximal end of the first shaft relative to the second shaft, compared to, for example, a configuration in which the proximal end of the first shaft makes point or line contact with the bottom surface of the groove.

[0017] (8) In the above guidewire, the bottom surface of the groove at the distal end of the second shaft may be located on the opposite side of the groove opening relative to the central axis of the second shaft. With this guidewire, the central axes of the base end of the first shaft and the second shaft are closer to each other, which improves the rotation performance of the guidewire, compared to a configuration in which the bottom surface of the groove at the distal end of the second shaft is located on the groove opening side relative to the central axis of the second shaft.

[0018] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a guidewire or a method for manufacturing the same. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a side view schematically illustrating the overall configuration of a guide wire according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the joint portion of the core shaft taken along the line II-II in FIG. 1; [Figure 3] An explanatory diagram showing a part of the manufacturing process of the guidewire. [Figure 4] FIG. 10 is a cross-sectional view showing a joint portion of a core shaft according to a modified example of the first embodiment. [Figure 5] FIG. 10 is an enlarged cross-sectional view showing a longitudinal cross-sectional configuration of a joint portion of a core shaft of a guide wire according to a second embodiment. [Figure 6]FIG. 6 is a cross-sectional view showing a cross-sectional configuration of a joint portion of a core shaft at a position VV in FIG. [Figure 7] FIG. 10 is a side view schematically showing the overall configuration of a guide wire according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] A. First embodiment: A-1. Configuration of guidewire 100: FIG. 1 is a side view schematically illustrating the overall configuration of a guidewire 100 according to a first embodiment. In FIG. 1, mutually orthogonal X, Y, and Z axes are shown for specifying directions, and the overall configuration of the guidewire 100 is shown as viewed in the positive X-axis direction. In FIG. 1, the positive Z-axis direction is the tip end (distal side) inserted into the body, and the negative Z-axis direction is the base end (proximal side) manipulated by an operator such as a doctor. This also applies to FIG. 2 and subsequent figures. In FIG. 1, a cross-sectional (specifically, YZ cross-sectional) configuration of a coil body 20, which will be described later, is shown. In FIG. 1, the guidewire 100 is shown in a state in which it is linearly shaped substantially parallel to the Z-axis direction as a whole, but the guidewire 100 has flexibility to the extent that it can be bent. In the following, the portion of the guidewire 100 and each of its constituent members, including the tip and extending partway from the tip toward the base end, is referred to as the "tip portion." Similarly, for the guidewire 100 and each of its constituent members, the portion including the base end and extending from the base end to the middle of the distal end will be referred to as the "base end portion."

[0021] The guidewire 100 is a medical device that is inserted into a blood vessel or the like to guide a catheter (not shown) to a lesion (a narrowed or blocked area) in the blood vessel or the like. As shown in Fig. 1, the guidewire 100 includes a core shaft 10, a coil body 20, a distal joint 30, and a proximal joint 40.

[0022] The core shaft 10 is a rod-shaped member having a small diameter at the tip end and a large diameter at the base end. The core shaft 10 includes a first shaft 11 including the tip end of the core shaft 10, and a second shaft 12 located on the base end side of the core shaft 10 relative to the first shaft 11. The base end of the first shaft 11 and the tip end of the second shaft 12 are joined by a joint 15. The joint 15 is made of, for example, a metal solder such as silver solder, gold solder, zinc, a Sn-Ag alloy, or a Au-Sn alloy, or an adhesive such as an epoxy adhesive.

[0023] The first shaft 11 is a rod-shaped member. In this embodiment, the first shaft 11 is made of a material including stainless steel (SUS302, SUS304, SUS316, etc.). The first shaft 11 is sometimes called a "ribbon" or a "shaping ribbon."

[0024] Specifically, the first shaft 11 is a round bar member having a circular cross section and an outer diameter that is substantially constant along its entire length. The cross section is a cross section (in this embodiment, an XY cross section) perpendicular to the axial direction (in this embodiment, the Z-axis direction) of the core shaft 10 (the same applies to the second and subsequent embodiments). In this embodiment, the axial direction of the core shaft 10 coincides with the axial direction of the guidewire 100. The shape of the cross section of the first shaft 11 is not particularly limited, and may be, for example, an ellipse or a polygon such as a triangle or a rectangle.

[0025] The second shaft 12 has a second small diameter portion 120, a second large diameter portion 121, and a second tapered portion 122. Note that in Fig. 1, a part of the second large diameter portion 121 of the second shaft 12 is not shown.

[0026] The second thin-diameter portion 120 of the second shaft 12 is a portion that includes the tip of the second shaft 12. The second thin-diameter portion 120 is rod-shaped with a circular cross section.

[0027] The second large diameter portion 121 of the second shaft 12 is located closer to the base end of the core shaft 10 than the second small diameter portion 120, and has a rod-like circular cross section with a larger outer diameter than the second small diameter portion 120.

[0028] The second tapered portion 122 of the second shaft 12 is located between the second small diameter portion 120 and the second large diameter portion 121. The outer diameter of the second tapered portion 122 gradually increases from the boundary position with the second small diameter portion 120 toward the boundary position with the second large diameter portion 121.

[0029] The cross-sectional shape of each part of the second shaft 12 is not particularly limited, and may be a polygon such as a triangle or a rectangle.

[0030] The material of the second shaft 12 is different from the material of the first shaft 11. Examples of materials that can be used to form the second shaft 12 include metal materials, more specifically, superelastic alloys such as Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, and tungsten. In this embodiment, the second shaft 12 is formed from a material containing a superelastic alloy such as Ni-Ti alloys. In this embodiment, the configuration includes the second shaft 12 formed from a material containing a superelastic alloy, so that even when the guidewire 100 is advanced through a curved blood vessel or the like, the second shaft 12 can exhibit the ability to return to its original shape after being deformed (sometimes referred to as "restorability"). This ensures the operability and blood vessel selectivity of the guidewire 100.

[0031] The coil body 20 is a coil-shaped member formed into a hollow cylinder by spirally winding a single wire. The coil body 20 is arranged to surround the outer periphery of the tip end of the core shaft 10 (specifically, the first shaft 11, and a part of the second small diameter portion 120, the second tapered portion 122, and the second large diameter portion 121 of the second shaft 12).

[0032] The coil body 20 is made of, for example, a metal material, more specifically, a radiolucent alloy such as stainless steel (SUS302, SUS304, SUS316, etc.), piano wire, a nickel-chromium alloy, or a cobalt alloy, or a radiopaque alloy such as gold, platinum, tungsten, or an alloy containing these elements (e.g., a platinum-nickel alloy). If at least a portion of the coil body 20 is made of a radiopaque material, the operator can determine the position of the coil body 20 under a radioscopic image.

[0033] The distal end joint 30 joins the distal end of the core shaft 10 and the distal end of the coil body 20. The distal end of the core shaft 10 and the distal end of the coil body 20 are fixedly embedded inside the distal end joint 30. The outer peripheral surface on the distal side of the distal end joint 30 is a smooth surface (e.g., a substantially hemispherical surface). The distal end joint 30 is made of, for example, a metal solder such as silver solder, gold solder, zinc, an Sn—Ag alloy, or an Au—Sn alloy, or an adhesive such as an epoxy adhesive. By arranging the distal end joint 30 on the distal side of the core shaft 10, the core shaft 10 is prevented from coming into contact with a blood vessel wall or the like, thereby suppressing damage to the core shaft 10.

[0034] The base-end joint 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 joint 40 is made of the same material as the above-mentioned tip-end joint 30. Note that the base-end joint 40 is not limited to being located on the base-end side of the coil body 20, and may be located at any position on the coil body 20.

[0035] A-2. Detailed configuration of the joint between the first shaft 11 and the second shaft 12: FIG. 1 shows an enlarged view of the joint portion (portion X1) between the first shaft 11 and the second shaft 12 as viewed in the positive direction of the X axis. FIG. 2 is a diagram showing the cross-sectional configuration of the joint portion taken along line II-II in FIG. 1. FIG. 2 also shows the cross-sectional configuration of the joint portion as viewed in the negative direction of the Z axis. In FIG. 2, R1 denotes a first circumscribing circle of the cross-sectional shape of the first shaft 11, and P denotes the central axis of the first circumscribing circle R1. Furthermore, R2 denotes a second circumscribing circle of the cross-sectional shape of the second small-diameter portion 120 of the second shaft 12 (which overlaps the contour line of the outer shape of the joint portion of the core shaft 10), and Q denotes the central axis of the second circumscribing circle R2. The maximum width (outer diameter) of the base end of the first shaft 11 is, for example, 40 μm or more and 60 μm or less, and the maximum width (outer diameter) of the tip end of the second shaft 12 (second thin diameter portion 120) is, for example, 50 μm or more and 70 μm or less.

[0036] 1, a groove 125 is formed on the outer circumferential surface of the second small diameter portion 120 of the second shaft 12. The groove 125 extends from the tip end of the second shaft 12 (second small diameter portion 120) toward the base end side of the second shaft 12. The groove 125 extends linearly along the axial direction (Z-axis direction) of the core shaft 10.

[0037] As shown in FIG. 2, the inner wall surface of the second shaft 12 (second small diameter portion 120) that forms the groove 125 has a pair of opposing surfaces 125A and a bottom surface 125B.

[0038] The pair of opposing surfaces 125A are wall surfaces arranged to face each other across the central axis Q. In this embodiment, the pair of opposing surfaces 125A are substantially parallel to each other, but may be tapered surfaces that widen from the bottom surface 125B toward the opening. The bottom surface 125B is a surface that connects the ends of the pair of opposing surfaces 125A in the depth direction (positive X-axis direction in FIG. 2). In this embodiment, the bottom surface 125B is a plane that is perpendicular to one radial direction of the second small diameter section 120 (X-axis direction in FIG. 2). Note that, in FIG. 2, the shape of the connecting portion (corner) between each opposing surface 125A and the bottom surface 125B is chamfered in an arc shape, but it may also be angular. The opening width D1 of the groove 125 is wider than the depth D2 of the groove 125. In this embodiment, the opening width D1 of the groove 125 is substantially constant over the entire length of the groove 125, and the depth D2 of the groove 125 is substantially constant over the entire length of the groove 125. The opening width D1 of the groove 125 is, for example, not less than 40 μm and not more than 60 μm, and the depth D2 of the groove 125 is, for example, not less than 20 μm and not more than 40 μm.

[0039] As shown in FIG. 2, the outer circumferential surface of the base end of the first shaft 11 has a pair of left and right side circumferential surfaces 11A, an inner circumferential surface 11B, and an outer circumferential surface 11C.

[0040] The pair of left and right side peripheral surfaces 11A are a pair of left and right surfaces sandwiching the central axis Q of the second shaft 12 (second thin diameter portion 120), and each side peripheral surface 11A faces a corresponding opposing surface 125A of the second thin diameter portion 120. In a cross section of the joint between the first shaft 11 and the second shaft 12, the pair of side peripheral surfaces 11A are curved surfaces located on the first circumscribed circle R1. The distance between the pair of side peripheral surfaces 11A continuously narrows as they approach the inner peripheral surface 11B (bottom surface 125B of the second thin diameter portion 120). The inner peripheral surface 11B is a surface facing the bottom surface 125B of the second thin diameter portion 120. In this embodiment, the inner peripheral surface 11B is a flat surface parallel to the bottom surface 125B. The outer peripheral surface 11C is the surface of a portion of the outer peripheral surface of the base end of the first shaft 11 that is exposed to the outside through the groove 125 of the second shaft 12. In a cross section of the joint portion, the outer peripheral surface 11C is a curved surface located on the second circumscribing circle R2.

[0041] The joint 15 joins the outer circumferential surface of the base end of the first shaft 11 to the inner wall surface that constitutes the groove 125 of the second shaft 12. Specifically, a pair of side circumferential surfaces 11A of the first shaft 11 are joined to a pair of opposing surfaces 125A of the second shaft 12 via the joint 15. Furthermore, the inner circumferential surface 11B of the first shaft 11 is joined to the bottom surface 125B of the second shaft 12 via the joint 15. FIG. 2 illustrates a state in which the joint 15 is filled without any gaps between the outer circumferential surface of the base end of the first shaft 11 and the inner wall surface that constitutes the groove 125 of the second shaft 12. However, a partial gap (space) may be formed between the outer circumferential surface of the base end of the first shaft 11 and the inner wall surface that constitutes the groove 125 of the second shaft 12.

[0042] 2 shows a configuration example in which a portion of the side circumferential surface 11A of the first shaft 11 and the opposing surface 125A of the second shaft 12 are in direct contact without a joint 15 therebetween, but as shown in FIG. 3(B) described later, the joint 15 may be interposed entirely between the side circumferential surface 11A of the first shaft 11 and the opposing surface 125A of the second shaft 12. In short, it is sufficient that the side circumferential surface 11A of the first shaft 11 and the opposing surface 125A of the second shaft 12 are inseparably joined. The same applies to the joining between the inner circumferential surface 11B of the first shaft 11 and the bottom surface 125B of the second shaft 12.

[0043] A-3. Manufacturing method: FIG. 3 is an explanatory diagram showing a part of the manufacturing process of the guidewire 100. First, a first material 11P, which is the first shaft 11 before processing, and a second material 12P, which is the second shaft 12 before processing, are prepared. The first material 11P is made of a material containing, for example, stainless steel, and is a rod-shaped member having a circular cross section (see the first circumscribing circle R1 in FIG. 3(A)). The second material 12P is made of a material containing, for example, a Ni-Ti alloy, and is a rod-shaped member having a circular cross section (see the second circumscribing circle R2 in FIG. 3(A)). The outer diameter of the second material 12P is larger than the outer diameter of the first material 11P.

[0044] Next, the first material 11P is press-processed in a direction perpendicular to the central axis P of the first material 11P to form a first material 11Q after primary processing having a pair of flat surfaces 11D, 11D. One of the pair of flat surfaces 11D, 11D (the lower surface in FIG. 3(A)) is the inner circumferential surface 11B described above. Furthermore, the second material 12P is processed, for example, by laser processing, to form a second shaft 12 (second narrow-diameter portion 120) having a groove 125 formed therein.

[0045] Next, as shown in Fig. 3(A), a bonding material 15P is applied to the inner wall surface that forms the groove 125 of the second shaft 12, and then the base end portion of the first material 11P is inserted into the groove 125 and bonded (for example, brazed). As a result, the bonding portion 15 is filled so as to fill the gap between the inner wall surface of the second shaft 12 and the base end portion of the first material 11P (see Figs. 1 and 2).

[0046] FIG. 3(B) shows the cross-sectional configuration of the joint between the first material 11Q and the second shaft 12 after the primary processing. As shown in FIG. 3(B), the first material 11Q has a portion (hereinafter referred to as the protruding portion 13) that protrudes outward from the second circumscribing circle R2 of the second shaft 12 (second small-diameter portion 120). Therefore, by performing a process to remove this protruding portion 13 by cutting or the like, the first shaft 11 having the outer circumferential surface 11C is formed. In other words, the cross-sectional shape of the joint between the first material 11Q and the second shaft 12 is a substantially perfect circle (see FIG. 2).

[0047] Thereafter, the coil body 20, the distal joint portion 30, etc. are attached to the core shaft 10, thereby completing the manufacture of the guidewire 100.

[0048] A-4. Advantages of the first embodiment: As described above, in the core shaft 10, the proximal end of the first shaft 11 is inserted into the groove 125 formed in the outer circumferential surface of the second shaft 12 (see FIG. 2 ). Therefore, according to the present embodiment, the thickness of the second shaft 12 is reduced by the amount of the groove 125 formed in the second shaft 12, and the rigidity of the joint portion between the first shaft 11 and the second shaft 12 is reduced. This reduces the rigidity gap in the core shaft 10 compared to a conventional configuration in which the outer circumferential surfaces of the shafts are simply joined together. Specifically, the rigidity gap between the first shaft 11, the joint portion between the first shaft 11 and the second shaft 12, and the second small-diameter portion 120 of the second shaft 12 is reduced. As a result, for example, damage to the guidewire 100 and a decrease in torque transmissibility due to the rigidity gap can be suppressed.

[0049] At least both sides (a pair of side circumferential surfaces 11A) of the base end of the first shaft 11 in the circumferential direction around the axis of the core shaft 10 are joined to the inner wall surfaces of the second shaft 12 that form the groove 125 (see FIG. 2). That is, the base end of the first shaft 11 is joined while being sandwiched between the inner wall surfaces (a pair of opposing surfaces 125A) that form the groove 125 of the second shaft 12. Therefore, according to the present embodiment, the base end of the first shaft 11 is supported by the pair of opposing surfaces 125A, and a wider joining area can be ensured compared to the conventional configuration, thereby improving the joining strength between the first shaft 11 and the second shaft 12.

[0050] Here, when the second shaft 12 (second material 12P) is extremely thin as in this embodiment, it is extremely difficult to form a hole in the distal end surface of the second material 12P for inserting the proximal end of the first shaft 11. However, even with such a configuration, according to this embodiment, it is possible to improve the joining strength between the first shaft 11 and the second shaft 12 while mitigating the rigidity gap in the core shaft 10.

[0051] In a cross section of the joint between the first shaft 11 and the second shaft 12, the contour line of the portion (outer circumferential surface 11C) of the outer peripheral surface of the base end of the first shaft 11 that is exposed from the groove 125 of the second shaft 12 is located closer to the second circumscribing circle R2 of the second shaft 12 than to the first circumscribing circle R1 of the first shaft 11 (see FIG. 2). Therefore, according to this embodiment, it is possible to suppress a decrease in rotation performance caused by the protrusion of the first shaft 11 relative to the second shaft 12, compared to a configuration in which the contour line of the portion of the second shaft 12 that is exposed from the groove 125 is located closer to the first circumscribing circle R1 of the first shaft 11 (see FIG. 3(B)).

[0052] The rotational performance referred to here means the so-called torque response (the ability of the distal end to follow the rotation of the proximal end), in which when the proximal end of the guidewire 100 is rotated (circumferentially around the axis of the guidewire), the distal end of the guidewire 100 rotates accordingly. The closer the cross-sectional shape of the joint between the first shaft 11 and the second shaft 12 is to a perfect circle, the better the torque response. In this embodiment, as described above, by removing the protruding portion 13 of the first shaft 11, the cross-sectional shape of the joint is made to be approximately a perfect circle, resulting in extremely high torque response.

[0053] The length H of the base end of the first shaft 11 in the depth direction (X-axis direction) of the groove 125 is greater than the depth D2 of the groove 125 of the second shaft 12 (see FIG. 2). Therefore, a decrease in strength of the base end of the first shaft 11 can be suppressed compared to, for example, a configuration in which the length H of the base end of the first shaft 11 is smaller than the depth D2 of the groove 125 of the second shaft.

[0054] The bottom surface 125B of the groove 125 of the second shaft 12 and the inner circumferential surface 11B of the base end of the first shaft 11 are flat and in surface contact with each other (see FIG. 2). Therefore, compared to a configuration in which the base end of the first shaft 11 is in point contact or line contact with the bottom surface 125B of the groove 125, for example, the stability and torque transmissibility of the base end of the first shaft 11 relative to the second shaft 12 can be improved.

[0055] A-5. Modification of the first embodiment: 4 is a diagram showing a cross-sectional configuration of a joint portion of a core shaft in a modified example of the first embodiment. As shown in FIG. 4, in the core shaft 10x of this modified example, the outer circumferential surface 11Cx of the first shaft 11x coincides with the first circumscribed circle R1 of the first shaft 11x. Furthermore, the height H (length in the depth direction of the groove 125) of the base end portion of the first shaft 11x (portion inserted into the groove 125) is greater than the depth D2 of the groove 125. According to this modified example, the base end portion of the first shaft 11x is thicker than in the first embodiment, thereby suppressing a decrease in strength of the first shaft 11x.

[0056] At the distal end of second shaft 12, bottom surface 125B of groove 125 is located on the opposite side (positive X-axis direction side) from the opening of groove 125 with respect to central axis Q of second shaft 12. Therefore, compared to a configuration in which bottom surface 125B of groove 125 is located on the opening side of groove 125 with respect to central axis Q of second shaft 12 (negative X-axis direction side) at the distal end of second shaft 12, the central axes of the base end of first shaft 11x and second shaft 12 are closer to each other, thereby improving the rotation performance of guidewire 100.

[0057] B. Second embodiment: B-1. Configuration of guidewire 100a: FIG. 5 is an enlarged cross-sectional view showing the longitudinal cross-sectional configuration of the joint portion of the core shaft 10a of the guidewire 100a according to the second embodiment. The longitudinal cross-section is a cross-section (YZ cross-section in this embodiment) parallel to the axial direction of the core shaft 10a (Z-axis direction in this embodiment). FIG. 5 shows only the longitudinal cross-sectional configuration of the joint portion of the core shaft 10a among the configurations of the guidewire 100a. FIG. 6 is a cross-sectional view showing the transverse cross-sectional configuration of the joint portion of the core shaft 10a at position VV in FIG. 6. FIG. 6 shows the transverse cross-sectional configuration of the joint portion of the core shaft 10a as viewed in the negative Z-axis direction.

[0058] The configuration of the guidewire 100a of the second embodiment is different from the configuration of the guidewire 100 of the first embodiment described above in terms of the configuration of the joint portion of the core shaft 10a. In the following, among the configuration of the guidewire 100a of the second embodiment, the same configuration as the configuration of the guidewire 100 of the first embodiment described above will be denoted by the same reference numerals and description thereof will be omitted as appropriate.

[0059] 5 and 6, the guidewire 100a includes a first shaft 11a including a distal end of a core shaft 10a, and a second shaft 12a located closer to the proximal end of the core shaft 10a than the first shaft 11a. The proximal end of the first shaft 11a and the distal end of the second shaft 12a are joined by a joint 15a (see FIG. 6).

[0060] The second shaft 12a has substantially the same shape as the second shaft 12 of the first embodiment, except that the shape of the groove 125a formed in the second small-diameter portion 120a of the second shaft 12a is different from the shape of the groove 125 formed in the second small-diameter portion 120 of the first embodiment. Specifically, as shown in FIG. 5, the bottom surface (inner wall surface 126a) of the groove 125a at the base end is inclined so as to approach the outer circumferential surface of the second shaft 12a as it approaches the base end of the second shaft 12a. Specifically, the bottom surface of the groove 125a at the base end is inclined linearly with respect to the central axis Qa of the second shaft 12a and reaches the outer circumferential surface of the second shaft 12a. In other words, there is no step between the bottom surface of the groove 125a at the base end and the outer circumferential surface of the second shaft 12a.

[0061] The bottom surface of the groove 125a of the second shaft 12a has an inclined portion that approaches the central axis Qa of the second shaft 12a as it approaches the tip of the second shaft 12a (second small diameter portion 120a). Specifically, the bottom surface of the groove 125a as a whole is linearly inclined so as to approach the central axis Qa of the second shaft 12a as it approaches the tip of the second shaft 12a. Note that, as shown in FIG. 6, in the cross section of the joint portion, the shape of the inner wall surface 126a of the second shaft 12a that constitutes the groove 125a is, for example, U-shaped (arcuate).

[0062] 5, the first shaft 11a is a rod-shaped member, and the base end of the first shaft 11a is housed in the groove 125a of the second shaft 12a. Specifically, the first shaft 11a is disposed along an inner wall surface 126a (bottom surface) that constitutes the groove 125a of the second shaft 12a so as to be linearly inclined with respect to the central axis Qa of the second small diameter portion 120a, and extends so as to approach the central axis Qa of the second small diameter portion 120a.

[0063] As shown in FIG. 6, the outer peripheral surface of the base end of the first shaft 11a has an inner surface 11E and an outer surface 11F. The inner surface 11E is a surface facing the inner wall surface 126a of the second small diameter portion 120a. Specifically, in a cross section of the joint between the first shaft 11a and the second shaft 12a, the inner surface 11E is located on the third circumscribing circle R3 of the first shaft 11a. Reference symbol Pa denotes the central axis of the third circumscribing circle R3. The outer surface 11F is the surface of a portion of the outer peripheral surface of the base end of the first shaft 11a that is exposed to the outside through the groove 125a of the second shaft 12a (see FIG. 5). In the cross section of the joint, the outer surface 11F is a curved surface that is located on the fourth circumscribing circle R4 of the second small diameter portion 120a. Reference symbol Qa denotes the central axis of the fourth circumscribing circle R4. That is, the protruding portion 13a of the first shaft 11a that protrudes outward from the groove 125a of the second shaft 12a is removed (see FIGS. 5 and 6).

[0064] The joint 15a joins the outer circumferential surface of the base end of the first shaft 11a to an inner wall surface 126a that forms the groove 125a of the second shaft 12a. Specifically, the inner surface 11E of the first shaft 11a is joined to the inner wall surface 126a of the second shaft 12a via the joint 15a (see FIG. 6).

[0065] B-2. Advantages of the second embodiment: As described above, in the second embodiment, the base end of the first shaft 11a is inserted into the groove 125a formed in the outer circumferential surface of the second shaft 12a (see FIG. 5, etc.). Therefore, according to the present embodiment, the second shaft 12a is made thinner by the amount of the groove 125a formed in the second shaft 12a, and the rigidity of the joint between the first shaft 11a and the second shaft 12a is low. Therefore, compared to the conventional configuration in which the outer circumferential surfaces of the shafts are simply joined together, the rigidity gap in the core shaft 10a can be alleviated.

[0066] At least both sides (inner surface 11E) of the base end of the first shaft 11a in the circumferential direction around the axis of the core shaft 10a are joined to inner wall surfaces 126a that form the groove 125a of the second shaft 12a (see FIG. 6). That is, the base end of the first shaft 11a is joined while being sandwiched between the inner wall surfaces 126a that form the groove 125 of the second shaft 12a. Therefore, according to this embodiment, the base end of the first shaft 11a is supported by the inner wall surfaces 126a, and a wider joining area can be ensured compared to the conventional configuration, thereby improving the joining strength between the first shaft 11a and the second shaft 12a.

[0067] In a cross section of the joint between the first shaft 11a and the second shaft 12a, the contour line of the portion (outer surface 11F) of the outer peripheral surface of the base end of the first shaft 11a that is exposed from the groove 125a of the second shaft 12a is located closer to the fourth circumscribing circle R4 of the second shaft 12a than to the third circumscribing circle R3 of the first shaft 11a (see FIG. 6). Therefore, according to this embodiment, it is possible to suppress a decrease in rotation performance caused by the protrusion of the first shaft 11a relative to the second shaft 12a, compared to a configuration in which the contour line of the portion of the second shaft 12a that is exposed from the groove 125a is located closer to the third circumscribing circle R3 of the first shaft 11a.

[0068] The bottom surface of the groove 125a of the second shaft 12a has an inclined portion that inclines toward the central axis Qa of the second shaft 12a as it approaches the tip of the second shaft 12a (see FIG. 5). As a result, according to this embodiment, stress concentration caused by the presence of a step between the bottom surface of the groove 125a and the outer circumferential surface of the second shaft 12a can be alleviated, compared to a configuration in which the bottom surface of the groove 125a at the base end of the second shaft 12a is not inclined. In particular, in this embodiment, since there is no step between the bottom surface of the groove 125a at the base end and the outer circumferential surface of the second shaft 12a, stress concentration can be alleviated more effectively.

[0069] The bottom surface of the groove 125a of the second shaft 12a has an inclined portion that is inclined toward the central axis Qa of the second shaft 12a as it approaches the tip of the second shaft 12a. As a result, according to this embodiment, misalignment of the central axes of the first shaft 11a and the second shaft 12a is suppressed compared to a configuration in which the bottom surface of the groove 125a of the second shaft 12a does not have the inclined portion, and as a result, deterioration in rotation performance due to axis misalignment can be suppressed.

[0070] C. Third embodiment: 7 is a side view schematically showing the overall configuration of a guidewire 100b according to the third embodiment. The configuration of the guidewire 100b according to the third embodiment differs from the configuration of the guidewire 100 according to the first embodiment in that the guidewire 100b according to the third embodiment includes an inner coil body 50. In the following, among the configuration of the guidewire 100b according to the third embodiment, the same configuration as the configuration of the guidewire 100 according to the first embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0071] The inner coil body 50 is a protector for protecting the distal end portion of the core shaft 10 (specifically, the first shaft 11 and a part of the second small diameter portion 120 and the second tapered portion 122 of the second shaft 12). The inner coil body 50 is housed within the coil body 20 and is arranged so as to surround the outer periphery of the distal end portion of the core shaft 10. The distal end of the inner coil body 50 is joined to the distal joint portion 30, the proximal end of the inner coil body 50 is joined to the second tapered portion 122 of the second shaft 12 via a proximal joint portion 53, and the intermediate portion of the inner coil body 50 is joined to the second tapered portion 122 of the second shaft 12 via an intermediate joint portion 52.

[0072] The inner coil body 50 is a coil-shaped member formed into a hollow cylinder by helically winding a single wire. The inner coil body 50 is made of, for example, a metal material, more specifically, a radiolucent alloy such as stainless steel (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 radiopaque alloy such as gold, platinum, tungsten, or an alloy containing these elements (for example, a platinum-nickel alloy).

[0073] According to this embodiment, in the guidewire 100b including the inner coil body 50, the rigidity gap in the core shaft 10 can be alleviated while improving the rotational followability.

[0074] D. Variations: 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.

[0075] The configurations of the guidewires 100, 100a, and 100b in the above-described embodiments are merely examples, and various modifications are possible. For example, in the above-described embodiments, the first shafts 11 and 11a and the second shafts 12 and 12a may have substantially the same outer diameter over their entire lengths.

[0076] In the above embodiment, the grooves 125, 125a may extend in a direction inclined with respect to the central axes Q, Qa of the second small diameter portions 120, 120a, or may extend spirally around the central axes Q, Qa, for example.

[0077] In the first embodiment, the groove 125 may have a U-shaped or V-shaped cross section. Furthermore, in the first embodiment, the inner wall surface of the groove 125 may have an inclined portion that approaches the central axis Q as it approaches the tip of the second small-diameter portion 120. This can suppress misalignment of the central axes P and Q of the first shaft 11 and the second shaft 12. Furthermore, in the first embodiment, the bottom surface of the base end of the groove 125 may be inclined so as to approach the outer circumferential surface of the second shaft 12 as it approaches the base end of the second shaft 12. This can alleviate stress concentration caused by the presence of a step between the bottom surface of the groove 125 and the outer circumferential surface of the second shaft 12. In the first embodiment, at least one of the bottom surface 125B of the groove 125 of the second shaft 12 and the inner circumferential surface 11B of the base end of the first shaft 11 may be a non-flat surface (e.g., a curved surface) and may be in point contact or line contact with each other. Furthermore, the bottom surface 125B of the groove 125 may be located on the opening side of the groove 125 with respect to the central axis Q of the second shaft 12 at the tip end of the second shaft 12.

[0078] In the first embodiment, the pair of opposing surfaces 125A constituting the groove 125 may open such that the distance between them increases toward the opening of the groove 125. Also, in the first embodiment, the opening width D1 of the groove 125 may be the same as the depth D2 of the groove 125, or may be narrower than the depth D2. Also, in the first embodiment, the opening width D1 of the groove 125 may increase toward the tip of the second thin diameter portion 120, and the depth D2 of the groove 125 may increase toward the tip of the second thin diameter portion 120. In each of the above embodiments, the first shafts 11, 11x, 11a are joined to the inner wall surfaces constituting the grooves 125, 125a of the second shafts 12, 12a, but they do not have to be joined and may simply be in contact, for example. In each of the above embodiments, the length in the depth direction of the groove 125 in the proximal end portion of the first shaft 11, 11x, 11a may be smaller than the depth D2 of the groove 125, 125a in the second shaft 12, 12a. This configuration can suppress a decrease in the rotation performance of the guidewire 100, 100a, 100b caused by the first shaft 11, 11x, 11a protruding relative to the second shaft 12, 12a.

[0079] In the first embodiment, in the cross section of the joint portion, the outer circumferential surface 11C may be located inside the second circumscribed circle R2 or outside the second circumscribed circle R2. However, as long as the outer circumferential surface 11C is located closer to the second circumscribed circle R2 than the first circumscribed circle R1, it is possible to suppress a decrease in rotation performance caused by the first shaft 11 protruding relative to the second shaft 12. Furthermore, the first embodiment may be provided with a configuration equivalent to the inner coil body 50 in the second embodiment.

[0080] In the second embodiment, the bottom surface of the groove 125a of the second shaft 12a may extend substantially parallel to the central axis Qa of the second shaft 12a. The bottom surface of the groove 125a of the second shaft 12a may include the inclined portion only in part. For example, the bottom surface of the groove 125a of the second shaft 12a may have an inclined portion and parallel portions located on the distal and proximal sides of the inclined portion and substantially parallel to the central axis Qa of the second shaft 12a. In the second embodiment, the cross section of the groove 125a may be rectangular or V-shaped.

[0081] In the above-described embodiment, the guidewires 100, 100a, and 100b may not necessarily include the distal joint portion 30.

[0082] The materials of the components constituting the guidewires 100, 100a, and 100b in the above-described embodiments are merely examples and can be modified in various ways. The manufacturing method of the guidewires 100 and 100a in the above-described embodiments is merely an example and other manufacturing methods are also possible. [Explanation of symbols]

[0083] 10, 10a, 10x: Core shaft 11, 11a, 11x: First shaft 11A: Side circumferential surface 11B: Inner circumferential surface 11C, 11Cx: Outer circumferential surface 11D: Flat surface 11E: Inner surface 11F: Outer surface 11P, 11Q: First material 12, 12a: Second shaft 12P: Second material 13, 13a: Protruding portion 15, 15a: Joint portion 15P: Joint material 20: Coil body 30: Tip-side joint portion 40, 53: Base-side joint portion 50: Inner coil body 52: Intermediate joint portion 100, 100a, 100b: Guidewire 120, 120a: Second narrow-diameter portion 121: Second wide-diameter portion 122: Second tapered portion 125,125a: Groove 125A: Opposing surface 125B: Bottom surface 126a: Inner wall surface D1: Opening width D2: Depth

Claims

1. A guidewire comprising a core shaft, the core shaft includes a first shaft located at a distal end side of the core shaft, and a second shaft having a distal end portion to which a proximal end portion of the first shaft is joined and made of a material different from that of the first shaft; a groove extending from the tip of the second shaft toward the base end of the second shaft is formed on an outer circumferential surface of the tip end of the second shaft, the proximal end of the first shaft is inserted into the groove of the second shaft; In a cross section of a joint portion between the first shaft and the second shaft, a portion of the first shaft where the outer diameter is maximum is covered by the groove of the second shaft. Guide wire.

2. 2. The guidewire of claim 1, In a cross section of a joint portion between the first shaft and the second shaft, a contour line of a portion of an outer circumferential surface of the base end portion of the first shaft that is exposed from the groove of the second shaft is located closer to a circumscribing circle of an outer shape of the second shaft than to a circumscribing circle of an outer shape of the first shaft. Guide wire.

3. The guide wire according to claim 1 or 2, a bottom surface of the groove of the second shaft at the base end portion thereof is inclined so as to approach the outer circumferential surface of the second shaft as it approaches the base end of the second shaft; Guide wire.

4. The guidewire according to any one of claims 1 to 3, a bottom surface of the groove of the second shaft having an inclined portion inclined toward the central axis of the second shaft as it approaches the tip end of the second shaft; Guide wire.

5. The guidewire according to any one of claims 1 to 4, a length of the base end portion of the first shaft in a depth direction of the groove is greater than a depth of the groove of the second shaft; Guide wire.

6. The guidewire according to any one of claims 1 to 4, a length of the base end portion of the first shaft in a depth direction of the groove is smaller than a depth of the groove of the second shaft; Guide wire.

7. A guidewire having a core shaft, the core shaft includes a first shaft located at a distal end side of the core shaft, and a second shaft having a distal end portion to which a proximal end portion of the first shaft is joined and made of a material different from that of the first shaft; a groove extending from the tip of the second shaft toward the base end of the second shaft is formed on an outer circumferential surface of the tip end of the second shaft, the proximal end of the first shaft is inserted into the groove of the second shaft; a bottom surface of the groove of the second shaft and a surface of the base end portion of the first shaft facing the bottom surface of the groove are flat and in surface contact with each other; Guide wire.

8. The guidewire according to any one of claims 1 to 7, At the tip end of the second shaft, the bottom surface of the groove is located on the opposite side of the central axis of the second shaft from the opening of the groove. Guide wire.

Images