Guidewires

Abstract

To provide a technique for improving access performance of a guide wire.SOLUTION: A guide wire includes: a core shaft; a first coil for covering an outer periphery of the core shaft; and a second coil a part of which is positioned outside the first coil, and in which wires on a distal end side enter a gap between wires on a distal end side of the first coil, and at least a part of wires on a rear end side is positioned outside the first coil.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a guidewire. [Background technology]

[0002] Conventionally, there has been known a guidewire that is inserted into a lumen in the body beforehand in order to place a medical device such as a catheter at a predetermined position in the body. Regarding this guidewire, Patent Document 1 discloses one having a double coil structure with an inner coil and an outer coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2014-233411 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improved accessibility, which is the ease of delivery of a guidewire to a lesion in a blood vessel. The accessibility includes, for example, tip flexibility for moving through a curved blood vessel, lesion passability for passing through a stenosis, rotational tracking for selecting one of branched blood vessels, etc. However, even with the above-mentioned prior art, there is still room for improvement in the accessibility of guidewires. [Means for solving the problem]

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a technique for improving the access performance of a guidewire.

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided a guidewire comprising: a core shaft, a first coil covering an outer periphery of the core shaft, and a second coil a portion of which is positioned outside the first coil, with a distal end strand of wires fitting into gaps between the distal end strands of the first coil and at least a rear end strand of wires of the second coil being positioned outside the first coil.

[0008] According to this configuration, in a guidewire in which a second coil is disposed outside a first coil, the wires at the distal end of the second coil are inserted into the gaps between the wires at the distal end of the first coil, so that the outer diameter of the distal end of the guidewire can be relatively reduced, and in addition, the bending rigidity of the distal end of the guidewire is increased, improving the ability to pass through stenotic areas. In addition, the wires at the rear end of the second coil are located outside the first coil, so that the flexibility of the distal end can be ensured. Therefore, according to this configuration, the accessibility of the guidewire can be improved.

[0009] (2) In the guidewire of the above embodiment, the second coil may be wound in the same direction as the first coil and configured to be able to change the outer diameter of the coil at the rear end, and at least a part of the wire at the rear end may be inserted into the gaps between the wires of the first coil by reducing the outer diameter of the coil at the rear end. According to this configuration, the wire of the second coil at the rear end may be inserted into the gaps between the wires of the first coil, thereby changing the flexibility of the tip of the guidewire. This allows, for example, the flexibility of the tip to be maintained when moving through a curved blood vessel, and the bending rigidity of the tip to be increased at a stenosed portion of the blood vessel, thereby further improving the passage through the stenosed portion.

[0010] (3) In the guidewire of the above aspect, the first coil may have a first strand wound in a spiral shape with gaps in the axial direction, and the second coil may have a second strand wound in a spiral shape with gaps in the axial direction, and the first strand distance may be larger than the second strand diameter and the second strand distance may be larger than the first strand diameter, where the outer diameter of the first strand is the first strand diameter, the distance of the gaps formed in the axial direction of the first strand is the first inter-strand distance, the outer diameter of the second strand is the second strand diameter, and the distance of the gaps formed in the axial direction of the second strand is the second inter-strand distance. With this configuration, when the diameter of the second coil is reduced, the strands of the second coil can be more easily inserted into the gaps of the strands of the first coil.

[0011] (4) In the guidewire of the above embodiment, the second coil may have a tapered portion in which the outer diameter of the coil decreases toward the distal end. According to this configuration, by providing a tapered portion in which the outer diameter decreases toward the distal end between a portion of the second coil in which the second wire fits into the gaps of the first wire and a portion of the second coil in which the second wire does not fit into the gaps of the first wire, a sudden change in bending rigidity in the axial direction of the second coil can be suppressed, and a decrease in access performance can be suppressed.

[0012] (5) In the guidewire of the above aspect, the tip of the core shaft may be provided distally of the tip of the first coil and have an outer diameter larger than the inner diameter of the first coil. This configuration can reduce the possibility that the first coil and the second coil will come off the distal end of the core shaft during use of the guidewire.

[0013] (6) According to another aspect of the present invention, there is provided a guidewire comprising a core shaft, a first coil covering an outer periphery of the core shaft, and a second coil covering an outer periphery of the first coil and wound in the same direction as the first coil, the first coil comprising a first strand wound in a spiral shape with a gap in the axial direction, the second coil comprising a second strand wound in a spiral shape with a gap in the axial direction, and wherein, when the outer diameter of the first strand is defined as the first strand diameter, the distance of the gap formed in the axial direction of the first strand is defined as the first inter-strand distance, the outer diameter of the second strand is defined as the second strand diameter, and the distance of the gap formed in the axial direction of the second strand is defined as the second inter-strand distance, the first inter-strand distance is larger than the second inter-strand diameter and the second inter-strand distance is larger than the first inter-strand diameter.

[0014] According to this configuration, in a guidewire in which a second coil is disposed outside a first coil, when the outer diameter of the second coil is reduced, the wires of the second coil can easily enter the gaps between the wires of the first coil. This allows the flexibility of the tip of the guidewire to be changed, and the flexibility of the tip can be maintained when moving through a curved blood vessel, and the bending rigidity of the tip can be increased at a stenosed portion of the blood vessel, thereby improving the ability to pass through the stenosed portion.

[0015] The present invention can be realized in various aspects, for example, a guide wire, a guide This is realized in the form of an endoscope, a catheter manufacturing method, an endoscope, a dilator, etc. It is possible. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of the overall configuration of a guidewire according to a first embodiment. [Diagram 2] FIG. 1 is an explanatory diagram illustrating a vertical cross section of the overall configuration of a guidewire according to a first embodiment. [Diagram 3] FIG. 2 is an explanatory view illustrating a vertical cross section of the distal end portion of the guidewire according to the first embodiment. [Figure 4]FIG. 2 is an explanatory view illustrating a vertical cross section of the distal end portion of the guidewire according to the first embodiment. [Diagram 5] FIG. 2 is an explanatory diagram illustrating a state in which the guidewire of the first embodiment is used. [Figure 6] FIG. 2 is an explanatory diagram illustrating a state in which the guidewire of the first embodiment is used. [Figure 7] 13 is an explanatory view illustrating a vertical cross section of a distal end portion of a guidewire according to a second embodiment. FIG. [Figure 8] 13 is an explanatory view illustrating a vertical cross section of a distal end portion of a guidewire according to a third embodiment. FIG. [Figure 9] FIG. 1 is an explanatory diagram illustrating a guidewire having a coil wire wound in the S direction. [Figure 10] FIG. 13 is an explanatory diagram illustrating a guidewire having a coil wire wound in the Z direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A guidewire is a medical device that is inserted into blood vessels or digestive organs by doctors and other medical professionals for use in treatment or examination.

[0018] Hereinafter, the left side in each of Figs. 1 to 10 will be referred to as the "tip side" of the guidewire and each of the components of the guidewire of the present invention, and the right side will be referred to as the "rear side" of the guidewire and each of the components. The tip side of the guidewire is the side that is inserted into the body first when the guidewire is inserted into the body, and the rear side of the guidewire is the side (proximal side) that is operated by a technician such as a doctor. In addition, the end portion located on the tip side of the guidewire and each of the components of the guidewire will be described as the "tip", and the part including the "tip" and extending from the tip to the middle toward the rear end will be described as the "tip portion". Similarly, the end portion located on the rear end side of the guidewire and each of the components of the guidewire will be described as the "rear end", and the part including the "rear end" and extending from the rear end to the middle toward the tip side will be described as the "rear portion".

[0019] 1 to 10, the left-right direction is referred to as the axial direction of the guidewire and each of its constituent members, and the direction perpendicular to the axial direction is referred to as the radial direction of the guidewire and each of its constituent members.

[0020] Each of Figs. 1 to 10 includes portions in which the relative ratios of the sizes of the guidewire and each of the components of the guidewire are depicted in different relative ratios than in reality, for the sake of convenience of explanation.

[0021] First Embodiment Fig. 1 is an explanatory diagram illustrating the overall configuration of a guidewire 1A of the first embodiment, and Fig. 2 is an explanatory diagram illustrating a vertical cross section of the overall configuration of the guidewire 1A of the first embodiment.

[0022] The guidewire 1A is a medical device that is inserted into a lumen in the body in advance to place a catheter or the like at a predetermined position in the body. The guidewire 1A has a core shaft 10, a first coil 20 that covers the outer periphery of the core shaft 10, and a second coil 30 that covers the outer periphery of the first coil 20.

[0023] The core shaft 10 is a long member with a length of about 500 mm to 5000 mm. The cross section of the core shaft 10 is a circle with a diameter of about 0.2 mm to 1.0 mm. The outer diameter of the core shaft 10 is smaller at the tip side than at the rear end side. The core shaft 10 has a core straight portion 11 whose outer diameter is approximately constant in the axial direction, and a core taper portion 12, which is located at the rear end side of the core straight portion 11 and whose outer diameter gradually decreases toward the tip side. The core shaft 10 has an engagement portion 13 at the tip end of the core straight portion 11. The engagement portion 13 is a portion formed so that the radial size is larger than the inner diameters of the first coil 20 and the second coil 30. By providing the engagement portion 13, it is possible to reduce the possibility that the first coil 20 and the second coil 30 will come off the tip side of the core shaft 10 during use of the guide wire 1A. For example, a metal material can be used for the core shaft 10. Examples of metallic materials include martensitic stainless steel, ferritic stainless steel, precipitation hardened stainless steel, austenitic stainless steel, NiTi alloys, and platinum alloys.

[0024] A tip tip 40 is provided at the tip of the core shaft 10. The tip side of the tip tip 40 is formed into a spherical shape. The tip tip 40 is formed integrally with the tip joint portion 50. The tip tip is formed from a metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, etc.

[0025] Fig. 3 is an explanatory diagram illustrating a vertical cross section of the distal end portion of the guidewire 1A according to the first embodiment. Fig. 3 shows a state in which the first coil 20 and the second coil 30 are not reduced in diameter and the rear end side of the second wire 31 is not inserted into the first wire 21.

[0026] The first coil 20 is a cylindrical member that covers the outer periphery of the tip of the core shaft 10. The first coil 20 is composed of a first strand 21 that is wound in a continuous spiral shape in the axial direction. The cross section of the first strand 21 is circular, and the outer diameter of the first strand 21 is defined as a first strand diameter 22. The first strand diameter 22 is, for example, about 0.020 mm to about 0.15 mm. The first strand 21 is wound so as to have gaps in the axial direction. The axial distance of the gaps formed in the first strand 21 is defined as a first inter-strand distance 23. The first inter-strand distance 23 is, for example, about 0.020 mm to about 0.15 mm. For example, a metal material can be used for the first coil 20. Examples of the metal material include martensitic stainless steel, ferritic stainless steel, precipitation hardened stainless steel, austenitic stainless steel, NiTi alloy, and platinum alloy.

[0027] The second coil 30 is a cylindrical member that covers the outer periphery of the first coil 20. The second coil 30 is composed of a second strand 31 that is wound in a continuous spiral shape in the axial direction. The cross section of the second strand 31 is circular, and the outer diameter of the second strand 31 is defined as a second strand diameter 32. The second strand diameter 32 is, for example, about 0.020 mm to about 0.15 mm. The second strand 31 is wound so as to have gaps in the axial direction. The axial distance of the gaps formed in the second strand 31 is defined as a second strand distance 33. The second strand distance 33 is, for example, about 0.020 mm to about 0.15 mm. The second coil 30 has a coil taper portion 34 whose inner diameter and outer diameter gradually decrease toward the tip side. The coil taper portion 34 is provided on the rear end side of the tip joint portion 50. The second coil 30 has a coil straight portion 35, the outer diameter and inner diameter of which are substantially constant in the axial direction, located rearward of the coil taper portion 34. For example, a metal material can be used for the second coil 30. Examples of the metal material include martensitic stainless steel, ferritic stainless steel, precipitation hardened stainless steel, austenitic stainless steel, NiTi alloy, and platinum alloy.

[0028] The tip joint 50 is a portion where the tip of the core shaft 10, the tip of the first coil 20, and the tip of the second coil 30 are joined. In the tip joint 50, the second wire 31 is inserted into the gap between the first wire 21 and fixed. The inner rear end joint 51 is a portion where the core shaft 10 and the rear end of the first coil 20 are joined. The outer rear end joint 52 is a portion where the core shaft 10 and the rear end of the second coil 30 are joined, which is provided on the rear end side of the inner rear end joint 51. The tip joint 50, the inner rear end joint 51, and the outer rear end joint 52 are formed by metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, etc.

[0029] Fig. 9 is an explanatory diagram illustrating a guidewire 110 having a coil wire 112 wound in the S direction. Fig. 10 is an explanatory diagram illustrating a guidewire 110 having a coil wire wound in the Z direction.

[0030] As shown in Fig. 9, one angle with respect to central axis 111 of guidewire 110 is set to 0 degrees to 90 degrees, and the other angle is set to 0 degrees to -90 degrees. In this case, the winding direction of the coil in which wires 112 of the coil are inclined with respect to central axis 111 of guidewire 110 and the angle A they form is set to 0 degrees to 90 degrees is set to S direction. On the other hand, as shown in Fig. 10, the winding direction of the coil in which wires 112 of the coil are inclined with respect to central axis 111 of guidewire 110 and the angle A they form is set to 0 degrees to -90 degrees is set to Z direction. The winding direction of both first coil 20 and second coil 30 is the S direction.

[0031] Fig. 4 is an explanatory diagram illustrating a vertical cross section of the distal end portion of the guidewire 1A according to the first embodiment. Fig. 4 shows a state in which the rear end side of the second wire 31 enters into the gap in the axial direction of the first wire 21 as a result of the diameter of the second coil 30 being reduced.

[0032] The first coil 20 and the second coil 30 are both wound in the S direction. Therefore, for example, when the rear end side (position of the outer rear end joint portion 52) of the guidewire 1A is rotated clockwise (in the direction of the CW arrow in FIG. 3) relative to the front end side (position of the front tip 40) to be twisted, both the first coil 20 and the second coil 30 are contracted in the radial direction (in the direction of the D arrow in FIG. 3). Here, the inner circumference of the first coil 20 is in contact with the outer circumferential surface of the core shaft 10, so that the amount of contraction in the radial direction is small. In addition, the first strand diameter 22 of the first coil 20 is approximately the same as the second inter-strand distance 33 of the second coil 30. In addition, the second strand diameter 32 of the second coil 30 is approximately the same as the first inter-strand distance 23 of the first coil 20. In addition, the first strand diameter 22 and the second strand diameter 32 are approximately the same. As a result, the total length of the first wire diameter 22 and the first inter-wire distance 23 is substantially the same as the total length of the second wire diameter 32 and the second inter-wire distance 33. With the above configuration, when the rear end side (position of the outer rear end joint part 52) ​​of the guidewire 1A is rotated clockwise relative to the tip side (position of the tip tip 40), the second wires 31 contract in the direction of the arrow D in Figure 3, whereby the second wires 31 enter the gaps between the first wires 21, and the first wires 21 and the second wires 31 engage with each other.

[0033] Fig. 5 is an explanatory diagram illustrating a state in which the guidewire 1A of the first embodiment is in use. Fig. 5 shows a state in which the guidewire 1A inserted into a blood vessel is in contact with a stenosed portion 100 of the blood vessel.

[0034] Since the winding direction of the first coil 20 in this embodiment is the S direction, when the operator of the guidewire 1A grips the rear end of the guidewire 1A and rotates the guidewire 1A clockwise (in the direction of the CW arrow in FIG. 5) in a state in which the guidewire 1A is in contact with a stenosed portion 100 of a blood vessel and receives resistance as shown in FIG. 5, the first coil 20 shrinks in the radial direction. Conversely, when the operator of the guidewire 1A grips the rear end of the guidewire 1A and rotates the guidewire 1A counterclockwise, the first coil 20 expands in the radial direction. Here, in the guidewire 1A of the first embodiment, the first coil 20 has a substantially constant inner diameter in the axial direction, and the inner circumference of the first coil 20 is in contact with the outer circumferential surface of the core shaft 10. Therefore, when the operator rotates the guidewire 1A clockwise, the amount by which the first coil 20 shrinks in the radial direction is small.

[0035] The winding direction of the second coil 30 is the S direction. Therefore, when the operator of the guidewire 1A grasps the rear end portion of the guidewire 1A and rotates the guidewire 1A clockwise in a state in which the guidewire 1A is in contact with a stenosed portion 100 of a blood vessel and receives resistance as shown in Fig. 5, the second coil 30 contracts in the radial direction (the direction of the arrow D in Fig. 5). Conversely, when the operator of the guidewire 1A grasps the rear end portion of the guidewire 1A and rotates the guidewire 1A counterclockwise, the second coil 30 expands in the radial direction.

[0036] Fig. 6 is an explanatory diagram illustrating a state in which the guidewire of the first embodiment is in use, showing a state in which the guidewire 1A passes through a stenosed portion 100 of a blood vessel.

[0037] The first coil 20 and the second coil 30 are both wound in the S direction. Therefore, for example, as shown in FIG. 5, when the operator of the guidewire 1A grips the rear end of the guidewire 1A and rotates the guidewire 1A clockwise in a state where the guidewire 1A is in contact with a stenosed portion 100 of a blood vessel and receives resistance, both the first coil 20 and the second coil 30 are contracted in the radial direction. Here, the inner circumference of the first coil 20 is in contact with the outer circumferential surface of the core shaft 10, so that the amount of contraction in the radial direction is small. In addition, the first strand diameter 22 of the first coil 20 is approximately the same as the second inter-strand distance 33 of the second coil 30. In addition, the second strand diameter 32 of the second coil 30 is approximately the same as the first inter-strand distance 23 of the first coil 20. In addition, the first strand diameter 22 and the second strand diameter 32 are approximately the same. As a result, the total length of the first strand diameter 22 and the first inter-strand distance 23 is substantially the same as the total length of the second strand diameter 32 and the second inter-strand distance 32.

[0038] With the above configuration, as shown in FIG. 6, when the first coil 20 and the second coil 30 are contracted in the radial direction by the rotation of the guidewire 1A, the second wire 31 enters and engages with the gaps of the first wire 21 from the tip side, starting from the tip joint 50 where the first wire 21 and the second wire 31 are fixed in an engaged state. Here, the length of the portion where the second wire 31 enters the gaps of the first wire 21 is defined as the coil diameter reduction length 36. As the operator of the guidewire 1A rotates the guidewire 1A clockwise, the second wire 31 enters the gaps of the first wire 21 from the tip side toward the rear end side, and the coil diameter reduction length 36 becomes longer. The operator can stop the second wire 31 from entering the gaps of the first wire 21 by stopping the rotation of the guidewire 1A. Furthermore, when the operator rotates the guidewire 1A counterclockwise, the second wires 31 come out of the gaps in the first wires 21 from the rear end side toward the front end side, thereby shortening the coil reduced diameter length 36. As the second wires 31 enter the gaps in the first wires 21, the outer diameter of the guidewire 1A temporarily decreases.

[0039] As shown in FIG. 6, the operator can pass the guidewire 1A through the stenosis 100 of the blood vessel with the second wire 31 entering the gaps of the first wire 21. The second wire 31 enters the gaps of the first wire 21, temporarily reducing the outer diameter of the guidewire 1A, making it easier for the guidewire 1A to pass through the stenosis. In addition, the first wire 21 and the second wire 31 engage with each other, temporarily increasing the bending rigidity and torque transmission performance of the tip of the guidewire 1A, making it easier to pass through the stenosis. The operator can adjust the coil contraction length 36 depending on the degree of stenosis and the length of the stenosis of the blood vessel. Even after the second coil 30 has been contracted once, the operator can expand the second coil 30 again by rotating the guidewire 1A counterclockwise, thereby increasing the flexibility of the guidewire 1A. For example, the second coil 30 is contracted to pass the guidewire 1A through the stenosis 100, and then when the guidewire 1A is pulled out from the body, the second coil 30 is expanded in diameter to increase flexibility, thereby making it easier for the guidewire 1A to move within the blood vessel. In addition, since the first wire 21 and the second wire 31 are fixed to the tip joint 50 in an engaged state, it is possible to reduce the possibility that the first coil 20 and the second coil 30 will come off the tip joint 50 when the guidewire 1A gets caught in the stenosis and resistance is generated when the guidewire 1A is pulled out in a usage situation such as that shown in Fig. 5 or Fig. 6.

[0040] <Second embodiment> Fig. 7 is an explanatory diagram illustrating a vertical cross section of a distal end portion of a guidewire 1B according to a second embodiment. Fig. 7 shows a state in which the second wires 31 enter the gaps between the first wires 21 as a result of the first coil 20 and the second coil 30 being reduced in diameter.

[0041] The guidewire 1B of the second embodiment differs from the guidewire 1A of the first embodiment in that it has an intermediate joint 53. The portions other than the intermediate joint 53 are common to the guidewire 1A of the first embodiment. The intermediate joint 53 is provided between the tip joint 50 and the inner rear end joint 51, and fixes the core shaft 10 and a part of the first wire 21. The intermediate joint 53 is formed of a metal solder such as silver solder, gold solder, zinc, a Sn-Ag alloy, or a Au-Sn alloy.

[0042] Since the intermediate joint 53 fills the gaps of the first wires, the second wires 31 do not enter the gaps of the first wires 21 at the portion where the intermediate joint 53 is provided. Therefore, as shown in FIG. 7, when an operator rotates the guidewire 1B clockwise, the second wires 31 enter the gaps of the first wires 21 only at the portion on the tip side of the intermediate joint 53. Since the guidewire 1B has the intermediate joint 53, it is possible to set the maximum length of the coil reduced diameter length 36. This makes it possible to set the length of the portion where the bending rigidity increases when the second wires 31 enter the gaps of the first wires 21, and it is possible to maintain the flexibility of the guidewire 1B at the rear end side of the intermediate joint 53.

[0043] <Third embodiment> Fig. 8 is an explanatory diagram illustrating a vertical cross section of a distal end portion of a guidewire 1C according to a third embodiment. Fig. 8 shows a state in which the second wires 31 enter the gaps between the first wires 21 as a result of the first coil 20 and the second coil 30 being reduced in diameter.

[0044] The guidewire 1C of the third embodiment differs from the guidewire 1A of the first embodiment in that the first strand diameter 22 is smaller than the second strand distance 23, the second strand diameter 32 is smaller than the first strand distance 23, and the first strand diameter 22 is smaller than the second strand diameter 32. The parts other than the strand diameters and strand distances of the first coil 20 and the second coil 30 are common to the guidewire 1A of the first embodiment. Due to the above configuration, the total length of the first strand diameter 22 and the first strand distance 23 is different from the total length of the second strand diameter 32 and the second strand distance 33. In the configuration of the guidewire 1C as well, it is possible for the second strand 31 to enter the gaps between the first strands 21. Since the first wire diameter 22 is smaller than the second inter-wire distance 33, and the second wire diameter 32 is also smaller than the first inter-wire distance 23, the first wire 21 and the second wire 31 do not engage with each other. Even when the second wire 31 fits into the gaps in the first wire 21, a gap is formed between the first wire and the second wire.

[0045] Even with the above configuration, the outer diameter of the tip portion of the guidewire 1C can be temporarily reduced by the second wires 31 entering the gaps between the first wires 21. This makes it easier for the guidewire 1C to pass through a stenosed portion of a blood vessel. Furthermore, since the first wires 21 and the second wires 31 are not engaged with each other, the flexibility of the tip portion can be maintained even in a state in which the second wires 31 enter the gaps between the first wires 21.

[0046] <Variation 1> Either the first strand diameter 22 of the first coil 20 or the second strand diameter 32 of the second coil 30 may be larger. Regardless of which is larger, if the second strand distance 33 is larger than the first strand diameter 22 and the second strand distance 33 is larger than the second strand distance 32, one coil strand can enter the axial gap of the other coil strand. Also, even if the second strand distance 33 is smaller than the first strand diameter 22, a part of the first strand 21 can enter the axial gap of the second strand 31. Similarly, even if the first strand distance 33 is smaller than the second strand diameter 32, a part of the second strand 31 can enter the axial gap of the first strand 21. Also, the total length of the first strand diameter 22 and the first strand distance 23 and the total length of the second strand diameter 32 and the second strand distance 33 may be the same or different.

[0047] <Variation 2> A plurality of intermediate joints 53 may be provided. For example, two intermediate joints 53 may be provided between the tip joint 50 and the inner rear end joint 51. In this case, the coil diameter reduction length 36 is set by the intermediate joint 53 closer to the tip. The intermediate joint 53 may also join the core shaft 10 and the second wire 31 of the second coil 30. The second wire 31 in the portion fixed by the intermediate joint 53 is not reduced in diameter, so that the second wire 31 in that portion can be prevented from entering the axial gap of the first wire 21. The intermediate joint 53 may also join the core shaft 10, the first wire 21, and the second wire 31 so as to be integrated with each other.

[0048] <Modification 3> The outer circumferential surface of the core shaft 10 and the inner periphery of the first coil 20 do not need to be in contact with each other. For example, by adjusting the coil configuration, such as the wire diameter of the first coil 20 and the angle A between the central axis of the guidewire and the wires of the coil shown in Fig. 9 or 10, the amount by which the first coil 20 shrinks in the radial direction can be made smaller than the amount by which the second coil 30 shrinks in the radial direction when the guidewire is rotated. This allows the second wires 31 to enter the axial gaps of the first wires 21 even when the outer circumferential surface of the core shaft 10 and the inner periphery of the first coil 20 do not contact each other.

[0049] <Variation 4> The winding direction of the first coil 20 and the second coil 30 may be the Z direction. In this case, for example, by rotating and twisting the rear end side (position of the outer rear end joint 52) ​​of the guidewire 1A counterclockwise with respect to the tip side (position of the tip tip 40), both the first coil 20 and the second coil 30 are contracted in the radial direction. Also, in a state in which the guidewire 1A is in contact with a stenosed portion 100 of a blood vessel and receives resistance as shown in FIG. 5, when the operator of the guidewire 1A grips the rear end portion of the guidewire 1A and rotates the guidewire 1A counterclockwise, both the first coil 20 and the second coil 30 are contracted in the radial direction. Conversely, when the operator of the guidewire 1A grips the rear end portion of the guidewire 1A and rotates the guidewire 1A clockwise, both the first coil 20 and the second coil 30 are expanded in the radial direction. Even when the first coil 20 and the second coil 30 are wound in the Z direction, the same effects as when the first coil 20 and the second coil 30 are wound in the S direction can be achieved.

[0050] <Variation 5> The first coil 20 and the second coil 30 may be cylindrical members formed by winding multiple wires in a spiral shape in the axial direction. For example, multiple wires may be formed into one strand, and the strand may be wound in a spiral shape to form a coil, with the wires of the other coil entering into gaps formed in the axial direction of the strand. [Explanation of symbols]

[0051] 1A, 1B, 1C...Guidewire 10...Core shaft 11...Core straight section 12...Core taper section 13...Engagement part 20…First coil 21…First wire 22…First wire diameter 23…First inter-wire distance 30…Second coil 31…Second wire 32…Second wire diameter 33…Second inter-wire distance 34…Coil taper section 35…Coil straight section 36…Coil contraction length 40…Tip 50...Tip joint 51…Inner rear end joint 52...Outer rear end joint 53...Middle joint 100...Stenosis 101...Vessel wall 110...Guide wire 111...Center axis of guide wire 112…Coil wire A: Angle between the central axis of the guidewire and the coil wire CW: Rotation direction of the guide wire D: The direction in which the second wire shrinks

Claims

1. A guidewire comprising: A core shaft; A first coil covering an outer periphery of the core shaft; a second coil, a portion of which is located outside the first coil, with a wire at a front end side entering a gap between the wires at a front end side of the first coil, and at least a portion of a wire at a rear end side of the second coil being located outside the first coil, The second coil is wound in the same direction as the first coil, and is configured so that the outer diameter of the coil on the rear end side is changeable, and by reducing the outer diameter of the coil on the rear end side, at least a part of the wire on the rear end side can be inserted into the gaps between the wires of the first coil. Guidewire.

2. 2. The guidewire of claim 1, The first coil has a first wire wound in a spiral shape with a gap in the axial direction, the second coil has a second wire wound in a spiral shape with a gap in the axial direction, The outer diameter of the first wire is defined as a first wire diameter, a distance between the gaps formed in the axial direction of the first wires is defined as a first inter-wire distance; The outer diameter of the second wire is defined as a second wire diameter, When the distance of the gap formed in the axial direction of the second wire is defined as the second inter-wire distance, The first inter-wire distance is greater than the second inter-wire diameter, The second inter-wire distance is greater than the first inter-wire diameter. Guidewire.

3. The guidewire according to claim 1 or 2, The second coil has a tapered portion in which the outer diameter of the coil decreases toward the tip side. Guidewire.

4. The guidewire according to any one of claims 1 to 3, The tip of the core shaft is provided on the tip side of the tip of the first coil and has an outer diameter larger than an inner diameter of the first coil. Guidewire.

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