Guidewire and method for manufacturing the same

Abstract

[Problem] To provide: a guide wire that can be shaped prior to a procedure, can suppress prolapses and kinks that can occur during a procedure, and has improved prolapse resistance and kink resistance; and a method for manufacturing the guide wire. [Solution] A guide wire 100 that comprises a core member 10 comprising a super-elastic alloy and having, in order from the tip thereof, a flat section 11g and a transition section 11f that extends from the base of the flat section 11g towards the base side along the longitudinal direction. The core member 10 has a heat-treated region H that extends from the tip of the flat section 11g to at least part of the transition section 11f.

Description

[Technical Field]

[0001] The present invention relates to a guidewire and a method for manufacturing the guidewire. [Background technology]

[0002] A guidewire is a medical device used to guide various catheters, which are used to treat stenoses that occur in blood vessels such as coronary arteries, to the stenotic site.

[0003] Guidewires must navigate complex curves and branches in blood vessels and pass through stenotic sections. Therefore, the tip of the guidewire must be flexible, resilient to external forces, and kinking-resistant. To meet these requirements, the tip of the guidewire is made of a superelastic alloy such as a Ni-Ti alloy.

[0004] Before inserting a guidewire into a blood vessel, a surgeon may impart a desired shape (shape) to the distal end of the guidewire in order to improve the operability of the guidewire within the blood vessel and the blood vessel selectivity at a bifurcation. Therefore, it is preferable that the distal end of the guidewire be easily shaped. However, if the distal end of a guidewire made of a superelastic alloy has high superelasticity, even if the surgeon applies an external force to the guidewire for shaping, the guidewire will return to its original shape after the external force is removed, making it difficult for the surgeon to impart the guidewire to the desired shape.

[0005] Patent Document 1 listed below discloses a technology in which the tip of a guidewire made of a superelastic alloy is subjected to cold working or heat treatment to reduce the superelasticity and enable shaping of the tip of the guidewire. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2002-503529 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when a guidewire is heat-treated, its rigidity changes suddenly at the boundary between the heat-treated and non-heat-treated portions. Therefore, depending on the location and extent of heat treatment, the distal end of the guidewire experiences a sudden change in longitudinal rigidity at the boundary between the heat-treated and non-heat-treated portions, making it prone to local bending at that boundary. When attempting to advance such a guidewire into a side branch at a bifurcation, prolapse occurs, and the pushing force or torque applied to the proximal end of the guidewire is transmitted only to the prolapsed portion. This makes it difficult for the surgeon to advance the distal end of the guidewire beyond the side branch. If the guidewire cannot be advanced into the side branch, the surgeon must remove the guidewire from the blood vessel and reshape it or exchange it for another guidewire, complicating the procedure. This increases the procedure time and burdens on the surgeon and patient.

[0008] Furthermore, if the superelasticity of the distal end of a guidewire is excessively reduced by heat treatment, the guidewire will be easily kinked due to plastic deformation when it strikes a blood vessel wall or a stenosis and bends within the blood vessel. A kinked guidewire prevents the pushing force or torque applied to the proximal end of the guidewire from being transmitted to the distal end, reducing operability. Furthermore, stress tends to concentrate at the kinked area, making the guidewire more susceptible to breakage. If the guidewire breaks, the surgeon must surgically remove the broken guidewire from the body. To avoid this situation, if the distal end of the guidewire kinks during manipulation within the blood vessel, the surgeon must remove the guidewire from the blood vessel and correct the kink or replace it with another guidewire, making the procedure more complicated. This increases the procedure time and burdens on the surgeon and patient.

[0009] Thus, the guidewire needs to have improved resistance to prolapse and kink in order to enable shaping before the procedure while suppressing prolapse and kinking that may occur during the procedure.

[0010] At least one embodiment of the present invention has been made in consideration of the above-mentioned circumstances, and specifically, an object of the present invention is to provide a guidewire and a method for manufacturing the guidewire that have improved resistance to prolapse and kink, which enable shaping before the procedure while suppressing prolapse and kinking that may occur during the procedure. [Means for solving the problem]

[0011] The guidewire according to this embodiment is a guidewire including a core member made of a superelastic alloy having, in order from the distal end, a flat plate portion and a transition portion extending from the proximal end of the flat plate portion to the proximal end along the longitudinal direction, and the core member has a heat-treated region extending from the distal end of the flat plate portion to at least a part of the transition portion. The flat plate portion has a Martens hardness of 1500 N / mm 2 More than 2500N / mm 2 is .

[0012] A method for manufacturing a guidewire according to this embodiment is a method for manufacturing a guidewire including a core member, and includes a step of cold working a distal end portion of the core member to have a flat plate portion and a transition portion extending from a proximal end of the flat plate portion toward the proximal end along the longitudinal direction, and a step of heat treating at least a portion of the flat plate portion and the transition portion. The flat plate has a Martens hardness of 1500N / mm 2 More than 2500N / mm 2 is . [Effects of the Invention]

[0013] According to one embodiment of the present invention, the heat-treated region of the guidewire extends from the distal end of the flat plate portion to at least a portion of the transition portion. This suppresses abrupt changes in the guidewire's rigidity along the longitudinal axis, which can occur at the boundary between the heat-treated and non-heat-treated portions, improving prolapse resistance. Furthermore, only the cold-worked flat plate portion and transition portion of the core member of the guidewire are heat-treated. That is, the non-cold-worked portion of the core member proximal to the transition portion is not heat-treated, thereby suppressing a significant decrease in superelasticity. This suppresses plastic deformation of the guidewire, improving its kink resistance. The improved prolapse resistance and kink resistance of the guidewire simplify the procedure, eliminating the need for the surgeon to remove the guidewire from the blood vessel and reshape it or replace it with another guidewire. This shortens the procedure time, thereby reducing the burden on the surgeon and the patient. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic plan view of a guidewire according to an embodiment of the present invention. [Figure 2] 1 is a partial cross-sectional view of the guidewire according to the present embodiment in the longitudinal direction as viewed from the thickness direction. FIG. [Figure 3A] FIG. 2 is a schematic perspective view of the distal end of a first core portion of the guidewire according to the present embodiment. [Figure 3B] 3 is a schematic plan view of the distal end portion of a first core portion of the guidewire according to the present embodiment. FIG. [Figure 4A] FIG. 2 is a conceptual diagram showing the state of rigidity of a first core portion of the guide wire according to the present embodiment before heat treatment. [Figure 4B] FIG. 10 is a conceptual diagram schematically illustrating the rigidity when heat treatment is applied to only a part of the flat plate portion in the first core portion of the guide wire according to the present embodiment. [Figure 4C] FIG. 10 is a conceptual diagram schematically illustrating the state of rigidity when heat treatment is applied to a transition portion in addition to the flat plate portion in the first core portion of the guide wire according to the present embodiment. [Figure 5A]FIG. 1 is a schematic diagram of a branch model used in a prolapse resistance test. [Figure 5B] 10A and 10B are diagrams for explaining the shaping shape of the distal end portion of the guide wire. [Figure 6] FIG. 1 is a schematic diagram of a constriction model used in a kink resistance test. [Figure 7] FIG. 10 is a diagram for explaining the bending height in a kink resistance test. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown here are merely examples for embodying the technical concept of the present invention and are not intended to limit the present invention. Furthermore, all other embodiments, examples, and operational techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included within the scope and spirit of the present invention, as well as within the scope of the claims and their equivalents.

[0016] Furthermore, for the convenience of illustration and ease of understanding, the drawings attached to this specification may be represented schematically with the scale, aspect ratio, shape, etc. appropriately changed from the actual product, but these are merely examples and do not limit the interpretation of the present invention.

[0017] For ease of explanation, the directions herein are defined as those when the guidewire 100 is in its natural state (i.e., when it is extended straight without any external force being applied). In FIG. 1 , the "longitudinal direction" refers to the direction in which the guidewire 100 extends, i.e., the direction along the central axis C of the guidewire 100 (the left-right direction in the drawing). The "radial direction" refers to the direction in which the guidewire 100 moves away from or toward the core portion in a cross section (transverse section) of the core portion, the reference axis being the longitudinal direction of the guidewire 100. The "circumferential direction" refers to the rotational direction around the longitudinal direction of the core portion. The "thickness direction" refers to the direction in which the short side of the rectangle of the flat plate portion 11g extends in a cross section (the front-to-back direction in the drawing) when the distal end of the guidewire 100 has a flat plate portion 11g. The "width direction" refers to the direction in which the long side of the rectangle of the flat plate portion 11g extends in a cross section (the up-to-down direction in the drawing) when the distal end of the guidewire 100 has a flat plate portion 11g.

[0018] The side of the guidewire 100 that is inserted into a blood vessel is referred to as the "distal side," and the side opposite the distal side (the side that is held by the surgeon) is referred to as the "proximal side." The portion that includes a certain range from the distal end (the most distal end) along the longitudinal axis is referred to as the "distal portion," and the portion that includes a certain range from the proximal end (the most proximal end) along the longitudinal axis is referred to as the "proximal end."

[0019] In the following description, when ordinal numbers such as "first" and "second" are used, unless otherwise specified, they are used for convenience and do not stipulate any particular order.

[0020] The guidewire 100 according to this embodiment is a medical device that is inserted into a blood vessel to guide a catheter or a stent for intravascular treatment to a stricture. Note that the guidewire 100 can also be inserted into other biological lumens (such as blood vessels, ureters, bile ducts, fallopian tubes, and hepatic ducts) other than blood vessels depending on the purpose of treatment.

[0021] [composition] 1 or 2, the guidewire 100 according to this embodiment includes a long core member 10, a tubular body 20 that covers the periphery of the distal end of the core member 10, a fixing portion 30 that fixes the tubular body 20 to the core member 10, and a coating layer 40 that covers each component including the core member 10. Each component of the guidewire 100 will be described in detail below.

[0022] <Core member> The core member 10 includes a first core portion 11 and a second core portion 12 that is disposed on the base end side of the first core portion 11 and joined to the first core portion 11 .

[0023] The first core portion 11 is a long member extending along the longitudinal direction from the distal end of the second core portion 12 toward the distal end of the guidewire 100. The first core portion 11 includes, in order from the base end of the first core portion 11 toward the distal end, a first joint portion 11a, a first constant outer diameter portion 11b, a first tapered portion 11c, a second constant outer diameter portion 11d, a second tapered portion 11e, a transition portion 11f, and a flat portion 11g, and each portion is integrally formed.

[0024] The first joint portion 11a is a portion to be joined to a second joint portion 12b of the second core portion 12, which will be described later. The outer diameter of the first joint portion 11a is larger than that of the first constant outer diameter portion 11b and is substantially equal to that of the second joint portion 12b. The outer diameters of the first joint portion 11a and the second joint portion 12b are larger than those of the first constant outer diameter portion 11b and the base portion 12a of the second core portion 12. That is, the area of ​​the joint surface 13 between the first joint portion 11a and the second joint portion 12b is larger than that of the first constant outer diameter portion 11b and the base portion 12a. As a result, when the guidewire 100 is bent, stress acting on the joint surface 13 is dispersed to the first constant outer diameter portion 11b and the base portion 12a, which have smaller outer diameters than the joint surface 13, thereby preventing stress concentration at the joint surface 13. Therefore, the core member 10 has high joint strength at the joint surface 13.

[0025] The first constant outer diameter portion 11b extends a predetermined length from the tip of the first joint portion 11a to the base end of the first tapered portion 11c. The outer diameter of the first constant outer diameter portion 11b is substantially constant and is substantially equal to the outer diameter of the base portion 12a of the second core portion 12.

[0026] The first tapered portion 11c extends a predetermined length from the tip of the first constant outer diameter portion 11b to the base end of the second constant outer diameter portion 11d. The first tapered portion 11c has a tapered shape in which the outer diameter gradually decreases from the first constant outer diameter portion 11b toward the tip. The tapered shape of the first tapered portion 11c can be formed by mechanically grinding the first core portion 11 with a grindstone or etching with acid.

[0027] The second constant outer diameter portion 11d extends a predetermined length from the tip of the first tapered portion 11c to the base end of the second tapered portion 11e. The outer diameter of the second constant outer diameter portion 11d is substantially constant and is smaller than the outer diameter of the first constant outer diameter portion 11b.

[0028] The second tapered portion 11e extends a predetermined distance from the tip of the second constant outer diameter portion 11d to the base end of the transition portion 11f. The second tapered portion 11e has a tapered shape in which the outer diameter gradually decreases from the second constant outer diameter portion 11d toward the transition portion 11f. The tapered shape of the second tapered portion 11e can be formed by mechanically grinding the first core portion 11 with a grindstone or etching with acid.

[0029] The transition portion 11f extends a predetermined distance from the tip of the second tapered portion 11e to the base end of the flat portion 11g. As shown in FIG. 3A or 3B, the transition portion 11f has a wedge shape in which the thickness gradually decreases and the width gradually increases from the second tapered portion 11e toward the flat portion 11g. The wedge shape of the transition portion 11f can be formed by subjecting the first core portion 11, which has a circular cross section, to press working, a type of cold working. The cross section of the transition portion 11f, as viewed in a plane perpendicular to the longitudinal axis direction (cross section), is circular at the base end with an outer diameter substantially equal to that of the second tapered portion 11e. However, the cross section gradually changes from circular to rectangular as it moves from the base end toward the tip end, eventually forming a rectangle substantially identical in shape to that of the flat portion 11g at the tip end. The tip end of transition portion 11f has approximately the same thickness and width as the base end of flat plate portion 11g, and forms a continuous surface with flat plate portion 11g. Note that the two-dot chain line in Figure 3B is an imaginary line separating flat plate portion 11g, transition portion 11f, and second tapered portion 11e. The "thickness" of flat plate portion 11g is the length of the short side of the rectangle in a cross-sectional view of flat plate portion 11g, and the "width" of flat plate portion 11g is the length of the long side of the rectangle in a cross-sectional view of flat plate portion 11g.

[0030] The flat plate portion 11g extends a predetermined length from the distal end of the transition portion 11f to the distal end of the guidewire 100. The flat plate portion 11g is formed by press-forming the first core portion 11 having a circular cross-sectional shape. Therefore, the flat plate portion 11g has a rectangular cross-sectional shape. The thickness of the flat plate portion 11g is approximately constant from the distal end of the transition portion 11f to the distal end of the flat plate portion 11g. As shown in FIGS. 3A and 3B, the shape of the flat plate portion 11g viewed from the thickness direction is a rectangle that is rounded at the distal end of the flat plate portion 11g. Therefore, the width of the flat plate portion 11g is approximately constant from the distal end of the transition portion 11f toward the distal end, but becomes smaller in the rounded portion. Note that the width of the flat plate portion 11g may be constant from the distal end of the transition portion 11f to the distal end of the flat plate portion 11g. The cross-sectional shape of the flat plate portion 11g is not limited to a rectangle, but may be a rounded rectangle having rounded corners.

[0031] It should be noted that the structure of the first core portion 11 is not limited to the above. For example, the first core portion 11 may have a constant outer shape or a constant outer diameter from the distal end to the proximal end.

[0032] The second core portion 12 is a long member extending from the base end of the first core portion 11 toward the base end side of the guidewire 100. The second core portion 12 includes, in order from the base end of the second core portion 12 toward the tip side, a base portion 12a and a second joint portion 12b, and these portions are integrally formed.

[0033] The base portion 12a extends a predetermined length from the base end of the second joint portion 12b toward the base end side of the guidewire 100. The outside diameter of the base portion 12a is substantially constant and is substantially equal to the outside diameter of the first constant outside diameter portion 11b.

[0034] The second joint portion 12b is a portion that is joined to the first joint portion 11a. The outer diameter of the second joint portion 12b is larger than the outer diameter of the base portion 12a and equal to the outer diameter of the first joint portion 11a. The first joint portion 11a and the second joint portion 12b can be joined by welding, brazing, or soldering.

[0035] Here, specific examples of dimensions of the guidewire 100 will be described. The overall length of the guidewire 100 in the longitudinal direction is 1000 mm to 4500 mm. The length of the first core portion 11 is 150 mm to 1000 mm. The combined length of the first joint portion 11a and the first constant outer diameter portion 11b is 10 mm to 300 mm. The length of the first tapered portion 11c is 10 mm to 100 mm. The length of the second constant outer diameter portion 11d is 10 mm to 300 mm. The length of the second tapered portion 11e is 10 mm to 100 mm. The length of the transition portion 11f is 1 mm to 20 mm. The length of the flat plate portion 11g is 1 mm to 20 mm.

[0036] The outer diameters of first joint portion 11a and first constant outer diameter portion 11b are 0.2 mm to 1 mm. The outer diameters of first tapered portion 11c and second constant outer diameter portion 11d are 0.1 mm to 1 mm. The outer diameter of second tapered portion 11e is 0.05 mm to 1 mm. The thickness of transition portion 11f is 0.01 mm to 1 mm, and the width is 0.05 mm to 1 mm. The thickness of flat portion 11g is 0.01 mm to 1 mm, and the width is 0.05 mm to 1 mm.

[0037] The length of the second core portion 12 is 850 mm to 3500 mm. The outer diameter of the second core portion 12 is 0.2 mm to 1 mm.

[0038] The first core portion 11 and the second core portion 12 can be formed from various metal materials, such as superelastic alloys such as Ni-Ti alloys, stainless steels such as SUS302, SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429, and SUS430F, piano wire, and cobalt-based alloys. The first core portion 11 is preferably formed from a material with lower rigidity than the material of the second core portion 12. For example, the first core portion 11 is formed from a Ni-Ti alloy, and the second core portion 12 is formed from stainless steel. The materials for forming the first core portion 11 and the second core portion 12 are not limited to the above examples. The first core portion 11 and the second core portion 12 may also be formed from the same material.

[0039] Furthermore, core member 10 may not be formed from a plurality of members like first core portion 11 and second core portion 12, but may be formed from a single continuous member.

[0040] <Luminous body> The luminal body 20 is a member formed by winding a wire in a spiral shape around the core member 10. In this embodiment, the luminal body 20 is formed by a first coil 21 and a second coil 22 arranged on the base end side of the first coil 21. The first coil 21 is arranged from the tip to the middle part of the first core portion 11. The second coil 22 is arranged from the middle part of the first core portion 11 to the base end side. The luminal body 20 may be formed by one coil. The luminal body 20 may be formed by three or more coils.

[0041] The first coil 21 surrounds the first core portion 11 of the core member 10 and is fixed to the first core portion 11. The first coil 21 is disposed coaxially with the first core portion 11. The length of the first coil 21 is 3 mm to 60 mm.

[0042] The first coil 21 is formed by spirally winding wire so that there is a gap between adjacent wires. The gap between adjacent wires in the first coil 21 is 1 μm to 10 μm. It is preferable that the gaps between adjacent wires in the first coil 21 are equal.

[0043] The second coil 22 surrounds the first core portion 11 of the core member 10 and is fixed to the first core portion 11. The second coil 22 is disposed coaxially with the first core portion 11. The length of the second coil 22 is 10 mm to 400 mm.

[0044] The second coil 22 has a densely wound portion in which the wire is tightly wound in a spiral shape so that there are no gaps between adjacent wire rods, and an loosely wound portion in which the wire is loosely wound in a spiral shape so that there are gaps between adjacent wire rods. In this embodiment, the densely wound portion of the second coil 22 is located at the tip and base ends of the second coil 22, and the loosely wound portion is located between the densely wound portion on the tip side and the densely wound portion on the base side. Note that the second coil 22 may be composed only of a densely wound portion without having an loosely wound portion.

[0045] The base end of the first coil 21 and the tip end of the second coil 22 are partially intertwined. That is, the wire at the base end of the first coil 21 and the wire at the tip end of the second coil 22 are arranged alternately along the longitudinal direction. This prevents the first coil 21 and the second coil 22 from being separated from each other. The length over which the base end of the first coil 21 and the tip end of the second coil 22 are intertwined is 0.1 mm to 2 mm. The winding directions of the first coil 21 and the second coil 22 are the same so that they can be intertwined.

[0046] The outer diameter of the wire material of first coil 21 and second coil 22 is 20 μm to 90 μm, and preferably 30 μm to 70 μm. In this embodiment, the outer diameter of the wire material forming first coil 21 is larger than the outer diameter of the wire material forming second coil 22. Furthermore, the wire material forming first coil 21 and second coil 22 may be not only a single wire material, but also a twisted wire made up of two or more wire materials.

[0047] The wire material of first coil 21 and second coil 22 is not particularly limited, but can be formed of metals such as stainless steel, superelastic alloy, cobalt-based alloy, gold, platinum, tungsten, or alloys containing these. As an example, first coil 21 is made of a platinum-based alloy that is more flexible and has higher contrast than second coil 22, and second coil 22 is made of stainless steel. Suitable platinum-based alloys include Pt-Ir, Pt-Ni, and Pt-W.

[0048] The outer diameters of the first coil 21 and the second coil 22 are preferably constant from the distal end to the proximal end. In this embodiment, the outer diameters of the first coil 21 and the second coil 22 are approximately equal. Therefore, the outer diameter of the luminal body 20 is approximately constant from the distal end to the proximal end. The outer diameters of the first coil 21 and the second coil 22 are 0.15 mm to 2 mm.

[0049] The material forming the wire that constitutes first coil 21 and second coil 22, the outer diameter of the wire, the cross-sectional shape of the wire, the pitch of the wire, and the like can be selected appropriately depending on the purpose of guidewire 100. Furthermore, the cross-sectional shape of the wire is preferably circular, but may be elliptical, polygonal, or the like. The center of the cross section of a wire that does not have a circular cross section may be the center of gravity of the cross section of the wire.

[0050] <Fixed part> The fixing part 30 is a member for fixing the luminal body 20 to the core member 10. In this embodiment, the fixing part 30 has a distal fixing part 31 that fixes the distal end of the luminal body 20 to the core member 10, an intermediate fixing part 32 that fixes the intermediate part of the luminal body 20 to the core member 10, and a proximal fixing part 33 that fixes the proximal end of the luminal body 20 to the core member 10.

[0051] The material forming the fixing portion 30 is a brazing material or a solder material. Examples of the brazing material include gold brazing and silver brazing. Examples of the solder material include Sn—Ag alloy solder and Sn—Pb alloy solder. The material forming the fixing portion 30 may also be an adhesive.

[0052] The distal end fixing portion 31 fixes the distal end of the first coil 21 to the flat plate portion 11g of the first core portion 11. The distal end fixing portion 31 is located at the tip of the guidewire 100, and has a smooth, approximately hemispherical outer surface.

[0053] The intermediate fixing portion 32 fixes the base end portion of the first coil 21 and the tip end portion of the second coil 22 to the second tapered portion 11e of the first core portion 11 via the cylindrical member 32a. The intermediate fixing portion 32 is provided at a position in the first core portion 11 where the base end portion of the first coil 21 and the tip end portion of the second coil 22 are intertwined.

[0054] The tubular member 32a is disposed between the inner peripheral surface of the luminal body 20 and the outer peripheral surface of the core member 10. The tubular member 32a coaxially fixes the luminal body 20 and the core member 10 by reducing the gap between the inner peripheral surface of the luminal body 20 and the outer peripheral surface of the core member 10. In this embodiment, the outer diameter of the distal end of the tubular member 32a is smaller than the outer diameter of the proximal end of the tubular member 32a. This allows the first coil 21, which has a small inner diameter, and the second coil 22, which has a large inner diameter, to be coaxially fixed to the core member 10, as shown in FIG. 2 . The outer diameters of the distal end of the tubular member 32a and the proximal end of the tubular member 32a may be appropriately selected depending on the inner diameters of the first coil 21 and the second coil 22. The tubular member 32a may be formed of a metal or resin material. Note that the guidewire 100 does not necessarily have to include the tubular member 32a.

[0055] The base end fixing portion 33 fixes the base end portion of the second coil 22 to the second constant outer diameter portion 11d of the first core portion 11.

[0056] <Coating layer> The coating layer 40 includes a first coating layer 41, a second coating layer 42, and a third coating layer 43. The coating layer 40 can be formed from a material that can reduce friction between the guidewire 100 and a blood vessel or a catheter. This improves the operability and safety of the guidewire 100.

[0057] The first covering layer 41 covers the outer surface of each part (the tubular body 20, the fixing part 30) provided in the first core part 11 and a part of the first core part 11 (the second constant outer diameter part 11d).

[0058] The second coating layer 42 covers a portion of the core member 10 that is located closer to the base end than the luminal body 20. The second coating layer 42 covers the base end portion (first tapered portion 11c, first constant outer diameter portion 11b) of the first core portion 11 and the outer surface of the second core portion 12. In other words, the second coating layer 42 covers the portion of the core member 10 that is located closer to the base end than the luminal body 20, excluding the first joint portion 11a and the second joint portion 12b.

[0059] The third covering layer 43 covers the outer surfaces of the first bonding portion 11a and the second bonding portion 12b.

[0060] The second covering layer 42 may cover the entire portion of the core member 10 located on the proximal side of the luminal body 20. In this case, the third covering layer 43 is not provided. Alternatively, the second covering layer 42 may not cover a portion of the portion of the core member 10 located on the proximal side of the luminal body 20. In this case, the third covering layer 43 may be provided on the portion not covered by the second covering layer 42.

[0061] The first coating layer 41 can be formed of a hydrophilic polymer. Examples of the hydrophilic polymer that forms the first coating layer 41 include cellulose-based polymers, polyethylene oxide-based polymers, maleic anhydride-based polymers (e.g., maleic anhydride copolymers such as methyl vinyl ether-maleic anhydride copolymers), acrylamide-based polymers (e.g., polyacrylamide, glycidyl methacrylate-dimethylacrylamide block copolymers), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, and derivatives thereof.

[0062] The second coating layer 42 and the third coating layer 43 can be made of a low-friction material, such as polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyesters (PET, PBT, etc.), polyamides, polyimides, polyurethanes, polystyrene, polycarbonates, silicone resins, fluorine-based resins (PTFE, ETFE, etc.), or composite materials thereof.

[0063] The materials forming the first coating layer 41, the second coating layer 42, and the third coating layer 43 are not limited to those described above. The first coating layer 41, the second coating layer 42, and the third coating layer 43 may each be formed of different materials along the longitudinal direction of the core member 10. For example, the material covering the distal end of the first core portion 11 in the second coating layer 42 may be different from the material covering the proximal end of the first core portion 11. Furthermore, the first coating layer 41, the second coating layer 42, and the third coating layer 43 may each include multiple layers. Furthermore, any of the first coating layer 41, the second coating layer 42, and the third coating layer 43 may not be provided.

[0064] The guidewire 100 according to this embodiment is heat-treated to enable shaping of the distal end. The heat treatment is performed on at least a portion of the flat plate portion 11g and the transition portion 11f of the first core member 11. That is, the guidewire 100 according to this embodiment has a heat-treated region H that extends continuously along the longitudinal direction from the distal end of the flat plate portion 11g to at least a portion of the transition portion 11f. One end of the heat-treated region H of the guidewire 100 coincides with the distal end of the flat plate portion 11g, and the other end is located on the transition portion 11f. In this specification, the heat-treated region H refers to a region in which an oxide coating is formed on at least a portion of the circumferential direction of the outer surface of the first core member by heat treatment. Therefore, the guidewire 100 has an oxide coating formed on the outer surface along the longitudinal direction from the distal end of the flat plate portion 11g to at least a portion of the transition portion 11f. In this specification, the heat-treated length refers to the entire length of the heat-treated region H along the longitudinal direction of the guidewire 100. The heat treatment length of the guide wire 100 is longer than the length along the longitudinal direction of the flat plate portion 11g.

[0065] The guidewire 100 has a heat-treated region H that extends continuously from the distal end of the flat portion 11g to at least a portion of the transition portion 11f, thereby suppressing abrupt changes in the rigidity of the guidewire 100 along its longitudinal axis. FIGS. 4A to 4C are diagrams schematically illustrating the rigidity of the distal end of the first core portion 11 after heat treatment of the guidewire 100. In FIGS. 4A and 4C, the dots on the outer surface of the first core portion 11 represent the rigidity, with denser dots representing lower rigidity and sparser dots representing higher rigidity. The two-dot chain lines in FIGS. 4A to 4C are imaginary lines separating the flat portion 11g, the transition portion 11f, and the second tapered portion 11e. As shown in FIG. 4A, the flat portion 11g of the guidewire 100 has a thin, flat plate shape. Therefore, the rigidity of the flat portion 11g is low and constant along its longitudinal axis. On the other hand, the transition portion 11f has a wedge shape in which the thickness gradually increases and the width gradually decreases from the flat portion 11g toward the second tapered portion 11e. Therefore, the rigidity of the transition portion 11f is equal to that of the flat portion 11g at the distal end and gradually increases from the distal end toward the proximal end. Here, when the first core portion 11 is heat-treated, the rigidity of the heat-treated portion of the first core portion 11 decreases. Therefore, as shown in FIG. 4B , when only a portion of the flat portion 11g is heat-treated, a sudden change in rigidity occurs in the flat portion 11g at the proximal end of the heat-treated region H. Alternatively, when only the flat portion 11g is heat-treated, a sudden change in rigidity occurs in the first core portion 11 at the boundary between the flat portion 11g and the transition portion 11f. The guidewire 100 is prone to bending and prolapse at points where the rigidity suddenly changes along the longitudinal axis. In this embodiment, as shown in Fig. 4C, the entire length of the flat portion 11g is preferably heat-treated, and a portion of the transition portion 11f is also preferably heat-treated, thereby suppressing abrupt changes in the rigidity of the guidewire 100 along its longitudinal axis and improving its prolapse resistance.

[0066] Here, prolapse refers to a state in which, with the tip of the guidewire 100 inserted from the main trunk to the side branch, the portion of the guidewire 100 proximal to the tip is locally bent, and the bent portion deviates distally from the branch from the main trunk to the side branch. When the guidewire 100 is in this state, the pushing force or torque applied to the proximal end of the guidewire 100 is transmitted only up to the bent portion, making it difficult for the surgeon to advance the tip of the guidewire 100 beyond the side branch. Furthermore, the tip of a catheter advanced along the guidewire 100 is guided toward the bent portion, making it difficult for the surgeon to advance the catheter into the side branch.

[0067] The proximal end of the heat-treated region H of the guidewire 100 is preferably located in the transition portion 11f. That is, the proximal end of the heat-treated region H of the guidewire 100 is preferably not located in the second tapered portion 11e. When the second tapered portion 11e, which is not cold-worked, is heat-treated, the superelasticity is reduced and the guidewire 100 is prone to plastic deformation. As a result, the guidewire 100 is prone to kinking in a blood vessel. In this embodiment, as shown in FIG. 4C , only the cold-worked flat portion 11g and the transition portion 11f are heat-treated. This suppresses plastic deformation of the guidewire 100 due to a reduction in superelasticity, improving kink resistance.

[0068] In the guidewire 100, it is preferable that the ratio of the length along the longitudinal direction of the transition portion 11f from the distal end to the proximal end of the heat-treated region H to the length along the longitudinal direction of the transition portion 11f be 10% or more and 100% or less. This allows the guidewire 100 to be shaped while improving its resistance to prolapse and kink. If the heat-treated length is longer than the above range, the first core portion 11 will undergo heat treatment in a portion that is not cold-worked, such as the second tapered portion 11e. If the first core portion 11 undergoes heat treatment in a portion that is not cold-worked, its superelasticity will decrease and it will be more susceptible to plastic deformation. As a result, the guidewire 100 will be more susceptible to kinking in a blood vessel. If the heat-treated length is shorter than the above range and only the flat portion 11g is heat-treated, a sudden change in rigidity will occur in the first core portion 11 at the boundary between the flat portion 11g and the transition portion 11f, making prolapse more likely to occur.

[0069] More preferably, the guidewire 100 has a ratio of the longitudinal length from the distal end of the transition portion 11f to the proximal end of the heat-treated region H to the longitudinal length of the transition portion 11f of 55% or more and 65% or less. This allows the guidewire 100 to be shaped while further improving its resistance to prolapse and kink. If the longitudinal length from the distal end of the transition portion 11f to the proximal end of the heat-treated region H exceeds 65% of the longitudinal length of the transition portion 11f, the length of the portion of the transition portion 11f where the rigidity has been reduced by the heat treatment will be longer. Therefore, when the guidewire 100 is pushed with its distal end inserted from the main trunk to the side branch, the pushing force is not transmitted to the distal end of the guidewire 100, and the guidewire 100 is bent at the transition portion 11f located in the main trunk, making prolapse more likely to occur. On the other hand, if the length along the longitudinal direction from the distal end of transition portion 11f to the proximal end of heat-treated region H is less than 55% of the length along the longitudinal direction of transition portion 11f, the length of the portion of transition portion 11f where the rigidity is high will be long. Furthermore, because the proximal end of heat-treated region H is located at the distal end of transition portion 11f, which has low rigidity, the rigidity of guidewire 100 will change suddenly at the proximal end of heat-treated region H, making prolapse more likely to occur. By setting the length along the longitudinal direction of heat-treated region H from the distal end of transition portion 11f to the proximal end of heat-treated region H to be 55% or more and 65% or less of the length along the longitudinal direction of transition portion 11f, the prolapse resistance and kink resistance of guidewire 100 can be further improved.

[0070] Furthermore, the guidewire 100 according to this embodiment has a distal end that is both shaping-capable and shape-retaining. Shapeability is a property that allows the surgeon to shape the distal end of the guidewire 100. Shaping the distal end of the guidewire 100 to a desired shape improves the operability of the guidewire 100 within blood vessels and blood vessel selectivity at bifurcations. The shape imparted to the guidewire 100 by shaping depends on the inner diameter and shape of the patient's blood vessels. Therefore, it is preferable that the guidewire 100 can be easily shaped into a desired shape. In other words, excellent shapeability is required.

[0071] Shape retention refers to the property of maintaining the shape imparted to the distal end of the guidewire 100 by shaping during manipulation of the guidewire 100 within a blood vessel. Generally, the shape imparted to the guidewire 100 by shaping is a curved shape, and the radius of curvature is large relative to the inner diameter of the blood vessel. Therefore, the guidewire 100 deforms to fit the inner diameter and shape of the blood vessel. The guidewire 100 may be unintentionally bent into a U-shape when its distal end strikes the blood vessel wall at a bifurcation or gets caught on a stent. Furthermore, the guidewire 100 may be intentionally bent into a U-shape when passing through a stenosis to prevent blood vessel perforation. Thus, the distal end of the guidewire 100 is subjected to external forces that may deform the distal end during manipulation within a blood vessel. If the guidewire 100 has low resilience against external forces, it will undergo plastic deformation and will be unable to maintain the shape imparted by shaping by the surgeon, resulting in reduced operability and blood vessel selectivity. If the distal end of the guidewire is deformed, the surgeon must remove the guidewire from the blood vessel and reshape it. If the guidewire is deformed to the extent that reshaping is difficult, it must be replaced with another guidewire. This extends the procedure time and increases the burden on the surgeon and the patient. Therefore, it is preferable that the guidewire 100 has the restorability to return to the shape given by the surgeon's shaping once the external force is removed, even if it is deformed by the application of an external force during operation inside the blood vessel. In other words, the guidewire 100 is required to have excellent shape retention.

[0072] A guide wire 100 that has both shapeability and shape retention properties can be obtained by controlling the elastic deformation power and Martens hardness of the tip of the guide wire 100 made of a Ni-Ti alloy within a specified range.

[0073] The elastic deformation power and Martens hardness are calculated from the load-displacement curve obtained by an instrumented indentation hardness test on the flat plate portion 11g of the guide wire 100. The elastic deformation power is the ratio of the work load of the elastic deformation to the total work load (the sum of the work load of the plastic deformation and the work load of the elastic deformation). The Martens hardness is the value obtained by dividing the test load by the surface area penetrated by the indenter in the instrumented indentation hardness test.

[0074] A material with a high elastic deformation power has high shape recovery due to its superelasticity. Therefore, even if an external force is applied, the flat plate portion 11g of the guidewire 100 formed from a material with a high elastic deformation power is likely to return to its original shape when the external force is removed. Therefore, the higher the elastic deformation power, the lower the shaping ability of the flat plate portion 11g and the higher its shape retention. On the other hand, a material with a low elastic deformation power is more susceptible to plastic deformation. Therefore, the flat plate portion 11g formed from a material with a low elastic deformation power is likely to undergo plastic deformation when an external force is applied and maintain its shape even when the external force is removed. Therefore, the lower the elastic deformation power, the higher the shaping ability of the flat plate portion 11g but the lower its shape retention.

[0075] A material with a high Martens hardness is hard. Therefore, the flat plate portion 11g of the guidewire 100 formed from a material with a high Martens hardness is less likely to deform due to an external force. Therefore, the higher the Martens hardness, the lower the shape-formability of the flat plate portion 11g and the higher its shape-retention ability. On the other hand, the flat plate portion 11g of the guidewire 100 formed from a material with a low Martens hardness is more likely to undergo plastic deformation even with a small external force applied within a blood vessel. Therefore, the lower the Martens hardness, the higher the shape-formability of the flat plate portion 11g and the lower its shape-retention ability.

[0076] The magnitude of the external force that guidewire 100 receives inside a blood vessel is smaller than the external force applied by the surgeon for shaping. Therefore, the distal end of guidewire 100 can be deformed by the large force applied by the surgeon for shaping, but has physical properties that allow it to recover to the shape at the time of shaping without plastic deformation by the small force applied during the procedure, thereby providing both shaping ability and shape retention.

[0077] The Martens hardness has a greater effect on shaping ability and shape retention than the elastic deformation power. Therefore, controlling only the elastic deformation power will not improve both shaping ability and shape retention, and it is particularly necessary to appropriately control the Martens hardness.

[0078] The flat plate portion 11g of the guide wire 100 according to this embodiment has a Martens hardness of 1500 N / mm 2 More than 2500N / mm 2 It is made of the following Ni-Ti alloy.

[0079] The distal end of the guidewire 100, whose flat plate portion 11g has a Martens hardness within the above range, has physical properties that allow it to be deformed by the large force applied by the surgeon for shaping, but to return to its original shape without plastic deformation when subjected to small forces applied during the procedure. This allows the guidewire 100 to be shaped by the surgeon, and it can also return to its original shape even when subjected to external forces within the blood vessel that could deform the distal end. Therefore, the guidewire 100 can maintain the high operability and vascular selectivity imparted by shaping, even during the procedure. Furthermore, the surgeon does not need to remove the guidewire 100 from the blood vessel to reshape it or exchange it for another guidewire, simplifying the procedure. This shortens the procedure time and reduces the burden on the surgeon and patient.

[0080] The flat plate portion 11g of the guide wire 100 has a Martens hardness of 1500 N / mm 2 More than 2100N / mm 2 The flat plate portion 11g of the guide wire 100 preferably has a Martens hardness of 1500 N / mm or less. 2 More than 2100N / mm 2 By setting the thickness within the following range, the flat plate portion 11g of the first core portion 11 becomes more flexible, and the shaping ability is further improved.

[0081] In addition, in the guidewire 100, the distal end of the core member 10 is preferably heat-treated so that the Martens hardness of the flat plate portion 11g falls within the above range.

[0082] The flat plate portion 11g is formed by press-forming the tip of the first core portion 11 made of a Ni-Ti alloy. The flat plate portion 11g after press-forming has reduced superelasticity compared to the Ni-Ti alloy before press-forming due to strain introduced by the processing. Therefore, the flat plate portion 11g after press-forming has a lower elastic deformation power and poor shape retention. By subjecting the flat plate portion 11g after press-forming to heat treatment, the strain is removed from the flat plate portion 11g, improving its superelasticity. As a result, the flat plate portion 11g has a higher elastic deformation power and improved shape retention. The flat plate portion 11g after press-forming is harder due to work hardening compared to the Ni-Ti alloy before press-forming. Therefore, the flat plate portion 11g after press-forming has a higher Martens hardness and poor shapeability. By subjecting the flat plate portion 11g after press-forming to heat treatment, the flat plate portion 11g becomes softer. As a result, the Martens hardness of the flat plate portion 11g is reduced, improving shaping ability. In this way, by subjecting the pressed flat plate portion 11g to heat treatment, the elastic deformation power and Martens hardness of the distal end portion of the guidewire 100 made of a Ni-Ti alloy can be controlled within a predetermined range. This allows the guidewire 100 to have both shaping ability and shape-retaining ability.

[0083] Various conditions can be appropriately set when heat treating the tip portion of the core member 10. For example, the heat treatment temperature is in the range of 300° C. to 650° C., and the time is in the range of 3 to 60 minutes.

[0084] The heat treatment has the effect of softening the flat plate portion 11g that has been hardened by cold working, making it easier to deform, and the effect of removing strain from the flat plate portion 11g whose superelasticity has been reduced by strain introduced by cold working, thereby appropriately improving the superelasticity. Therefore, the heat treatment is particularly effective as a method of imparting shaping ability and shape retention to the guide wire 100.

[0085] The flat plate portion 11g of the guidewire 100 according to this embodiment is preferably formed from a Ni-Ti alloy having an elastic deformation power of 50% to 59%. By setting the elastic deformation power of the flat plate portion 11g of the guidewire 100 to a range of 50% to 59%, the flat plate portion 11g of the first core portion 11 can be deformed by a large force applied by the surgeon for shaping, but has appropriate superelasticity that allows it to recover to the shape at the time of shaping without plastic deformation by a small force applied during the procedure, thereby improving shaping ability and shape retention.

[0086] [Action and effect] As described above, the guide wire 100 of this embodiment comprises a core member 10 having, in order from the tip side, a flat portion 11g and a transition portion 11f extending from the base end of the flat portion 11g toward the base end along the longitudinal direction, and the core member 10 has a heat treatment region H extending from the tip of the flat portion 11g to at least a portion of the transition portion 11f.

[0087] With this configuration, the heat-treated region H of the guidewire 100 extends from the distal end of the flat plate portion 11g to at least a portion of the transition portion 11f. This suppresses abrupt changes in stiffness along the longitudinal axis that can occur at the boundary between the heat-treated and non-heat-treated portions, improving prolapse resistance. Furthermore, in the guidewire 100, only the cold-worked flat plate portion 11g and the transition portion 11f of the core member 10 are heat-treated. In other words, the non-cold-worked portion of the core member proximal to the transition portion is not heat-treated, thereby suppressing a significant decrease in superelasticity. This suppresses plastic deformation of the guidewire, improving its kink resistance. The improved prolapse resistance and kink resistance of the guidewire simplify the procedure, eliminating the need for the surgeon to remove the guidewire 100 from the blood vessel and reshape it or replace it with another guidewire 100. This shortens the procedure time, thereby reducing the burden on the surgeon and the patient.

[0088] Furthermore, the guide wire 100 of this embodiment may have a ratio of the length along the longitudinal direction of the transition portion 11f from the tip of the transition portion 11f to the base end of the heat treatment region H to the length along the longitudinal direction of the transition portion 11f of 10% or more and 100% or less.

[0089] With this configuration, the guidewire 100 can be shaped before a procedure, while improving prolapse resistance and kink resistance.

[0090] In addition, the guide wire 100 according to this embodiment has a Martens hardness of 1500 N / mm 2 More than 2500N / mm 2 It may be configured as follows:

[0091] With this configuration, the guidewire 100 can be deformed by the large force applied by the surgeon for shaping, but can restore its original shape without plastic deformation when subjected to small forces applied during the procedure. In other words, the guidewire 100 has both shaping and shape-retention properties while being resistant to prolapse and kinking. This allows the guidewire 100 to be shaped by the surgeon and restore its original shape even when subjected to external forces that may deform the distal end within the blood vessel. Therefore, the guidewire 100 can maintain the high operability and vascular selectivity imparted by shaping during the procedure. Furthermore, the surgeon does not need to remove the guidewire 100 from the blood vessel to reshape it or exchange it for another guidewire, simplifying the procedure. This shortens the procedure time and reduces the burden on the surgeon and patient.

[0092] Furthermore, the guidewire 100 according to this embodiment has a Martens hardness of 1500 N / mm 2 More than 2100N / mm 2 It may be configured as follows:

[0093] With this configuration, the guidewire 100 has a more flexible flat portion 11g of the first core portion 11 at the tip of the core member 10, and therefore has prolapse resistance and kink resistance while also having improved shaping ability.

[0094] In addition, the guide wire 100 of this embodiment may have a ratio of the length along the longitudinal direction of the transition portion 11f from the tip of the transition portion 11f to the base end of the heat treatment region H to the length along the longitudinal direction of the transition portion 11f of 55% or more and 65% or less.

[0095] By subjecting the guide wire 100 to heat treatment for 55% to 65% of the transition portion 11f from the tip, the difference in physical properties that arises due to the coexistence of high-rigidity and low-rigidity portions in the transition portion 11f can be suppressed, thereby further improving prolapse resistance.

[0096] In addition, the manufacturing method of the guide wire 100 of this embodiment includes a step of cold-working the tip of the core member 10 so that it has a flat portion 11g and a transition portion 11f extending from the base end of the flat portion 11g toward the base end along the longitudinal direction, and a step of heat-treating at least a portion of the flat portion 11g and the transition portion 11f.

[0097] The guidewire 100 manufactured by the above method is heat-treated at least in part of the core member 10, namely, the flat plate portion 11g, which has a constant rigidity, and the transition portion 11f, which has a rigidity that gradually increases from the distal end to the proximal end. This prevents a sudden change in rigidity along the longitudinal direction of the guidewire 100, which may occur at the boundary between the heat-treated and non-heat-treated portions. Furthermore, in the guidewire 100, only the cold-worked flat plate portion 11g and the transition portion 11f of the core member 10 are heat-treated. In other words, the non-cold-worked portion of the core member proximal to the transition portion is not heat-treated, thereby preventing a significant decrease in superelasticity. This reduces plastic deformation of the guidewire, improving its kink resistance. The improved prolapse resistance and kink resistance of the guidewire simplify the procedure, as the surgeon does not need to remove the guidewire 100 from the blood vessel to reshape it or exchange it for another guidewire 100. This reduces the procedure time and reduces the burden on the surgeon and the patient. [Example]

[0098] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples.

[0099] The "guidewire manufacturing," "evaluation method," and "evaluation results" of the guidewires of the examples and comparative examples will be described in detail below with reference to Tables 1 to 4. Table 1 shows the manufacturing conditions for Examples 1 to 16, and Table 2 shows the manufacturing conditions for Comparative Examples 1 to 4. Note that the "heat treatment ratio" in Tables 1 and 2 refers to the ratio of the length along the longitudinal direction from the tip of transition portion 11f to the base end of heat treatment region H to the length along the longitudinal direction of transition portion 11f.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Guidewire manufacturing] The manufacture of guidewire 100 according to Examples and Comparative Examples will be described below. In each Example and Comparative Example, the heat treatment carried out in step 3 was carried out at a temperature in the range of 300°C to 650°C for a time in the range of 3 minutes to 60 minutes.

[0103] Example 1 (Process 1) The tip of the first core portion 11 (Ni content 54 mass % to 57 mass %) made of Ni-Ti alloy was tapered so that the outer diameter gradually decreased from the base end side toward the tip end side. The outer diameter of the tip end was 80 μm. (Process 2) The first core portion 11 was pressed over a range of 16 mm from the tip toward the base end to form the flat plate portion 11g and the transition portion 11f. At this time, the range of 9 mm from the tip toward the base end of the guide wire 100 was the flat plate portion 11g, which was formed into a uniform flat plate shape with a thickness of 27 μm. The range of 7 mm from the base end of the flat plate portion 11g toward the base end was the transition portion 11f, which had a wedge shape with an increasing thickness toward the base end. (Step 3) The first core portion 11 pressed in step 2 was subjected to heat treatment over a range of 10.3 mm from the tip to the base end. (Step 4) A tubular body 20 consisting of a first coil 21 and a second coil 22 was disposed around the flat plate portion 11g of the first core member 11 and a part of the second constant outer diameter portion 11d. The first coil 21 was a coil having a length of 28 mm to 32 mm and formed by winding a platinum alloy wire (outer diameter: 0.340 mm to 0.350 mm, wire diameter: 58 μm to 60 μm). The second coil 22 was a coil having a length of 210 mm to 220 mm and formed by winding a stainless steel wire (outer diameter: 0.340 mm to 0.350 mm, wire diameter: 38 μm to 40 μm). The tip of the first coil 21 was fixed to the flat plate portion 11g of the first core member 11 with silver brazing. The base end of the first coil 21 and the tip end of the second coil 22 were fixed to the second tapered portion 11e of the first core portion 11 with Sn-Ag alloy solder via a metal cylindrical member 32a. The base end of the second coil 22 was fixed to the second constant outer diameter portion 11d of the first core portion 11 with Sn-Ag alloy solder. (Step 5) The first core portion 11 and the second core portion 12 were joined by butt resistance welding. (Step 6) The outer surfaces of the first coil 21, the second coil 22, and part of the second constant outer diameter portion 11d were coated with a hydrophilic polymer to form a first coating layer 41. The outer surfaces of the first constant outer diameter portion 11b, the first tapered portion 11c, and the second core portion 12 of the first core portion 11 were coated with a fluorine-based resin to form a second coating layer 42. The outer surfaces of the first joint portion 11a and the second joint portion 12b were coated with a silicone resin to form a third coating layer 43.

[0104] The guidewires of Examples 2 to 10 were manufactured as follows: In manufacturing the guidewires of Examples 2 to 10, steps 1, 2, and 4 to 6 were performed in the same manner as in Example 1, and step 3 was performed as follows.

[0105] Example 2 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 11.7 mm from the tip to the base end.

[0106] Example 3 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 12.5 mm from the tip to the base end.

[0107] Example 4 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 12.5 mm from the tip to the base end.

[0108] Example 5 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 13.3 mm from the tip to the base end.

[0109] Example 6 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 13.6 mm from the tip to the base end.

[0110] Example 7 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 13.7 mm from the tip to the base end.

[0111] Example 8 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 13.8 mm from the tip to the base end.

[0112] Example 9 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 14.4 mm from the tip to the base end.

[0113] Example 10 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 16.0 mm from the tip to the base end.

[0114] Comparative Examples 1 to 4 were produced as follows: Steps 1, 2, and 4 to 6 of Comparative Examples 1 and 2 were produced in the same manner as in Example 1, and step 3 was produced as follows.

[0115] Comparative Example 1 In step 3, the first core portion 11 pressed in step 2 was heat-treated in a range of 18.9 mm from the tip to the base end.

[0116] Comparative Example 2 In step 3, the first core portion 11 pressed in step 2 was subjected to heat treatment in a range of 20.6 mm from the tip to the base end.

[0117] Comparative Example 3 In step 3, the first core portion 11 pressed in step 2 was subjected to heat treatment in a range of 7.2 mm from the tip to the base end.

[0118] Comparative Example 4 In step 3, the first core portion 11 cold worked in step 2 was heat treated in a range of 9.3 mm from the tip to the base end.

[0119] [Evaluation method] The guide wires of Examples 1 to 16 and Comparative Examples 1 to 4 were evaluated as follows.

[0120] <Measurement of elastic deformation power and Martens hardness> -Device- Shimadzu Dynamic Ultra-Micro Stiffness Meter DUH-211S -Measurement conditions- Measuring indenter: Triangular indenter (inter-edge angle 115°) Equipment accessories (Triangular 115) ·Environmental conditions: temperature 22±1℃ - Measurement method and procedure - Test method: Load-unload test (compliant with "Instrumented indentation hardness" ISO14577-1) Indentation depth: 0.5 μm ·Holding time: 0 seconds Measurement location: 10 arbitrary points on the cross section parallel to the plane seen from the thickness direction of the flat plate portion 11g -Calculation method- The elastic deformation power and Martens hardness of the guidewires of each Example and Comparative Example were average values ​​of measurements taken at 10 arbitrary points on a cross section parallel to a plane viewed from the thickness direction of the flat plate portion 11g. The elastic deformation power was expressed as one decimal place, and the Martens hardness was expressed as an integer.

[0121] <Shapeability test> The shaping test was carried out as follows. First, a 5 mm portion of the tip of the guidewire 100 was sandwiched between a silicone rubber plate placed on a substantially horizontal surface and a stainless steel round bar (φ0.7 mm), and the round bar was pressed down with a load of 100 g. Next, the guidewire 100 was pulled out vertically from the silicone rubber plate, and the shape of the tip of the guidewire 100 was visually observed. The evaluation was carried out by assigning "Good" to the tip of the guidewire 100 that was significantly deformed after the test compared to before the test, "Average" to the tip that was deformed but only to a small extent, and "Poor" to the tip that was not deformed.

[0122] <Shape retention test> The shape retention test was performed as follows. The guidewire 100 was deformed and shaped with a curvature radius of 3.5 mm from a position 2 mm to a position 7 mm from the tip. The shaped guidewire 100 was inserted into a U-shaped passage with a curvature radius of 15 mm, rotated left and right alternately a total of 10 times, and then pulled out to confirm the shape of the tip of the guidewire 100. The evaluation was performed as follows: when a perpendicular line was drawn from the tip of the guidewire 100 to the central axis C, if the distance between the foot of the perpendicular line on the central axis C before the test and the foot of the perpendicular line after the test was within 1 mm, the shape was deemed to have been retained and marked with a "Good"; if the distance was greater than 1 mm, the shape was deemed not to have been retained and marked with a "Poor"; it should be noted that the smaller the curvature radius of the U-shaped passage, the greater the external force the guidewire 100 was subjected to, making it more difficult for it to retain its shape during shaping.

[0123] <Prolapse resistance test> The prolapse resistance test was performed as follows. First, a branching model 200 was prepared, which was made of a silicone resin tube as shown in FIG. 5A. The branching model 200 included a main trunk 210 and multiple side branches 220 arranged along the longitudinal direction of the main trunk 210. The main trunk 210 had an inner diameter of 3 mm, and the side branches 220 had an inner diameter of 2 mm. In FIG. 5A, the angles θ (θ1 to θ7) at the distal end formed between the central axis of the main trunk 210 and the central axis of the side branches 220 were θ1 = 90°, θ2 = 100°, θ3 = 110°, θ4 = 120°, θ5 = 130°, θ6 = 140°, and θ7 = 150°.

[0124] Next, the distal end of the guidewire 100 was shaped. As shown in FIG. 5B, the guidewire 100 was deformed by approximately 135° in the same direction at the first bending point P1, located 1 mm from the distal end, and the second bending point P2, located 5 mm from the distal end. Next, the guidewire 100 was inserted into each side branch 220 through the insertion port 200a of the branch model 200 filled with water. The maximum angle θ of the side branches 220 into which the guidewire 100 could be inserted was recorded. A small maximum angle θ into which the guidewire 100 could be inserted indicates that prolapse is likely to occur. Therefore, the evaluation was performed on the side branches 220 into which the guidewire 100 could be inserted, with a "×" if the maximum angle θ was θ≦100°, a "△" if the angle θ was 100°<θ≦110°, and a "◯" if the angle θ was 110°<θ≦120°.

[0125] <Kink resistance test> The kink resistance test was performed as follows. As shown in Figure 6, a stenosis model 300 was prepared, consisting of a tube with an inner diameter of 2.5 mm and one end blocked. The distal end of the guidewire 100 was shaped into the shape shown in Figure 5B. The distal end of the guidewire 100 was inserted into the open end of the stenosis model 300, which was filled with water, and abutted against the blocked end, as shown by the two-dot dashed line in Figure 6. Next, the guidewire 100 was pushed 10 mm toward the distal end while applying torque, and the distal end of the guidewire 100 was bent into a U-shape, as shown by the solid line in Figure 6. The guidewire 100 was then pulled 10 mm in the longitudinal direction to return to its unbent U-shape. This procedure was performed a total of three times. Torque was applied to the guidewire 100 by the tester by rotating it once while holding the proximal end of the guidewire 100. The guidewire 100 was removed from the stenosis model 300, and the bending height L of the guidewire 100 was confirmed using a digital microscope. As shown in FIG. 7, the "bending height L" refers to the length from the tip of the guidewire 100 before shaping (in a straight state) to the tip of the guidewire 100 after the kink resistance test, on a plane passing through the central axis C of the guidewire 100 when the guidewire 100 is in its natural state. The evaluation was made as "Good" when the bending height L of the guidewire 100 after the kink resistance test was less than 4 mm, and as "Poor" when the bending height L was 4 mm or more.

[0126] [Evaluation results] Table 3 shows the evaluation results of Examples 1 to 10, and Table 4 shows the evaluation results of Comparative Examples 1 to 4. In the tables, "ND" means not measured.

[0127] [Table 3]

[0128] [Table 4]

[0129] <Shape forming test and shape retention test> As shown in Table 3, the guide wires 100 of Examples 1, 2, 4 to 6, and 8 to 10 were either "good" or "fair" in both the shape-formability test and the shape-retention test. The guide wires 100 of Examples 1, 2, 4 to 6, and 8 to 10 had a Martens hardness of 1500 N / mm 2 More than 2500N / mm 2 The elastic deformation power of the flat plate portion 11g was 50% to 59% (condition 2).

[0130] On the other hand, as shown in Table 3, the guidewire 100 of Example 3 obtained a result of "good" in the shape retention test but an "unacceptable" result in the shape formability test. It is presumed that the guidewire 100 of Example 3 was unable to be shaped because its Martens hardness was greater than the upper limit of Condition 1 and was harder than Examples 1, 2, and 4 to 10. Furthermore, as shown in Table 3, the guidewire 100 of Example 7 obtained a result of "good" in the shape formability test but an "unacceptable" result in the shape retention test. It is presumed that the guidewire 100 of Example 7 was easily plastically deformed because its Martens hardness was less than the lower limit of Condition 1 and was softer than Examples 1 to 6 and 8 to 10. Furthermore, the elastic deformation power of the guidewire 100 of Example 3 was less than the lower limit of Condition 2, while the elastic deformation power of Example 7 was greater than the upper limit of Condition 2. It is presumed that Examples 1, 2, 4 to 6, and 8 to 10 had moderate superelasticity compared to Examples 3 and 7, and therefore had improved shaping ability and shape retention.

[0131] As described above, the guidewire 100 in which the flat plate portion 11g was formed from a Ni-Ti alloy that satisfied the above conditions 1 and 2 had both shape-forming ability and shape-retaining ability.

[0132] Furthermore, as shown in Table 3, the guidewires 100 of Examples 4 and 8 received a "△" in the shaping test, while the guidewires 100 of Examples 1, 2, 5 to 7, 9, and 10 received a "◯" in the shaping test. The guidewires 100 of Examples 4 and 8 received a "◯" in the shaping test. The Martens hardness of the Ni-Ti alloy in the flat plate portion 11g was 1500 N / mm 2 More than 2100N / mm 2 or less (Condition 3). The guidewires 100 of Examples 4 and 8 had Martens hardness greater than the upper limit of Condition 3, and therefore were presumably harder to shape than the guidewires 100 of Examples 1, 2, 5 to 7, 9, and 10.

[0133] As described above, the guidewire 100 in which the flat plate portion 11g was formed from a Ni-Ti alloy that satisfied the above condition 3 was even more excellent in both shapeability and shape retention.

[0134] <Prolapse resistance test> As shown in Table 3, the guidewires 100 of Examples 1 to 10 received either a "good" or a "fair" result in the prolapse resistance test. On the other hand, as shown in Table 4, the guidewires 100 of Comparative Examples 3 and 4 both received an "unacceptable" result in the prolapse resistance test. In the guidewires 100 of Examples 1 to 10, the ratio of the length along the longitudinal direction from the distal end of the transition portion 11f to the proximal end of the heat-treated region H to the length along the longitudinal direction of the transition portion 11f (heat treatment ratio) is 10% or more and 100% or less (condition 4). In contrast, the guidewires 100 of Comparative Examples 3 and 4 both had heat treatment ratios less than the lower limit of condition 4, and the heat treatment was applied only to a small portion of the distal end of the flat plate portion 11g and the transition portion 11f. Therefore, it is presumed that the guide wires 100 of Comparative Examples 3 and 4 had a sudden change in rigidity near the boundary between the flat portion 11g and the transition portion 11f, as shown in Figure 4B, resulting in a decrease in prolapse resistance.

[0135] Furthermore, as shown in Table 3, the guidewires 100 of Examples 5 and 6 received a result of "good" in the prolapse resistance test. On the other hand, the guidewires 100 of Examples 1 to 4 and Examples 7 to 10 received a result of "fair" in the prolapse resistance test. In both of the guidewires 100 of Examples 5 and 6, the ratio of the length along the longitudinal direction from the distal end of the transition portion 11f to the proximal end of the heat-treated region H to the length along the longitudinal direction of the transition portion 11f was 55% or more and 65% or less (Condition 5). In contrast, the guidewires 100 of Examples 1 to 4 had a heat treatment ratio smaller than the lower limit of Condition 5, and the proximal end of the heat-treated region H was located at the distal end of the transition portion 11f, which has low rigidity. Therefore, it is presumed that the guidewires 100 of Examples 1 to 4 experienced a sudden change in rigidity at the proximal end of the heat-treated region H, resulting in a decrease in prolapse resistance. Furthermore, the guidewires 100 of Examples 7 to 10 have a heat treatment ratio greater than the upper limit of Condition 5, and the length of the portion in transition section 11f where the rigidity is reduced by the heat treatment is long. Therefore, it is presumed that the guidewires 100 of Examples 7 to 10 have difficulty in transmitting the pushing force to the tip of the guidewire 100, resulting in reduced prolapse resistance.

[0136] As described above, a guide wire 100 in which the ratio of the length along the longitudinal direction of the transition portion 11f from the tip of the transition portion 11f to the base end of the heat treatment region H satisfies the above condition 4, and more preferably satisfies the above condition 5, has excellent resistance to prolapse.

[0137] <Kink resistance test> As shown in Table 3, the guidewires 100 of Examples 1 to 10 received a kink resistance test result of "good." On the other hand, the guidewires 100 of Comparative Examples 1 and 2 received a kink resistance test result of "poor." In all of the guidewires 100 of Examples 1 to 10, the ratio of the length along the longitudinal direction from the tip of the transition portion 11f to the base end of the heat-treated region H to the length along the longitudinal direction of the transition portion 11f was 10% or more and 100% or less (Condition 4). In contrast, in Comparative Examples 1 and 2, the heat treatment ratio was greater than the upper limit of Condition 4, and even the non-cold-worked portions were heat-treated. Since the core member 10 is made of a Ni-Ti alloy, when the non-cold-worked portions are heat-treated, the superelasticity is reduced and the core member 10 becomes susceptible to plastic deformation. Therefore, it is presumed that the guidewires 100 of Comparative Examples 1 and 2 had reduced kink resistance.

[0138] As described above, the guidewire 100 in which the heat treatment ratio in the transition portion 11f satisfied the above condition 4 was excellent in kink resistance.

[0139] This application is based on Japanese Patent Application No. 2020-183260, filed on October 30, 2020, the disclosure of which is incorporated herein by reference in its entirety. [Explanation of symbols]

[0140] 10 core members, 11 first core portion (11a first joint portion, 11b first constant outer diameter portion, 11c first tapered portion, 11d second constant outer diameter portion, 11e second tapered portion, 11f transition portion, 11g flat portion), 12 second core portion (12a base portion, 12b second joint portion), 13 joint surface, 20 luminal body, 21 First coil, 22 second coil, 30 Fixed part, 31 Tip fixing part, 32 intermediate fixing portion (32a cylindrical member), 33 Proximal fixation part, 40 coating layer, 41 first coating layer, 42 second coating layer, 43 third coating layer, 100 guidewire, C center axis, H Heat treatment area.

Claims

1. A guidewire including a core member made of a superelastic alloy having, in order from a distal end, a flat plate portion and a transition portion extending from a proximal end of the flat plate portion toward the proximal end along a longitudinal direction, the core member has a heat treatment region extending from a tip of the flat portion to at least a portion of the transition portion; The guide wire, wherein the flat plate portion has a Martens hardness of 1500 N / mm 2 or more and 2500 N / mm 2 or less.

2. The guide wire according to claim 1, wherein the ratio of the length along the longitudinal direction from the tip of the transition portion to the base end of the heat treatment region to the length along the longitudinal direction of the transition portion is 10% or more and 100% or less.

3. The Martens hardness is 1500 N / mm ２ More than 2100N / mm ２ 2. The guidewire of claim 1, wherein:

4. The guide wire according to claim 2 or 3, wherein the ratio of the length along the longitudinal direction from the tip of the transition portion to the base end of the heat treatment region to the length along the longitudinal direction of the transition portion is 55% or more and 65% or less.

5. A method of manufacturing a guidewire having a core member, comprising: a step of cold working the distal end portion of the core member so as to have a flat portion and a transition portion extending from a base end of the flat portion toward the base end along the longitudinal direction; and performing heat treatment on at least a portion of the flat plate portion and the transition portion, The method for manufacturing a guidewire, wherein the flat plate portion has a Martens hardness of 1500 N / mm 2 or more and 2500 N / mm 2 or less.

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