Guide wire

Abstract

This guide wire includes a core shaft, a coil covering the core shaft from the outside, and a coating layer covering the coil. The coating layer has a resin layer covering the surface of the coil. The resin layer includes an outer resin layer positioned outward with respect to the center line of the coil. The thickness of the outer layer portion of the coating layer determined as a value obtained by subtracting the outer diameter of the coil from the outer diameter of the guide wire is 0.006-0.259 mm. Load applied to the leading end of the guide wire is 15 mN or less.

Description

Guidewire

[0001] The technology disclosed herein relates to guidewires.

[0002] A known guidewire includes a wire body and a tubular body covering the outer periphery of the wire body. The tubular body has a helical linear body and a laminated portion (coating layer) covering the linear body (see, for example, Patent Document 1).

[0003] JP 2008-194185 A

[0004] Increasing the thickness of the coating layer improves the lubricity of the guidewire but reduces its flexibility. Conversely, decreasing the thickness of the coating layer improves the flexibility of the guidewire but reduces its lubricity. Therefore, it has not been easy to achieve both lubricity and flexibility in a guidewire with a coating layer.

[0005] This specification discloses a technique that can solve the above-mentioned problems.

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) The guidewire disclosed herein comprises a core shaft, a coil externally covering the core shaft, and a coating layer covering the coil. The coating layer has a resin layer covering the surface of the coil. The resin layer includes an outer resin layer located outside the center line of the coil. The film thickness of the outer layer portion of the coating layer, which is the value obtained by subtracting the outer diameter of the coil from the outer diameter of the guidewire, is 0.006 mm or more and 0.259 mm or less. The tip load of the guidewire is 15 mN or less.

[0008] This guidewire has good smoothness and flexibility because the thickness of the outer layer of the coating layer is within the above range. This guidewire has good flexibility because the tip load of the guidewire is within the above range. Therefore, this guidewire can achieve both smoothness and flexibility.

[0009] (2) In the above guidewire, the covering layer may further have a hydrophilic coating layer that covers the resin layer from the outside. Since the covering layer of this guidewire has the hydrophilic coating layer, the lubricity of the guidewire can be more effectively improved.

[0010] (3) In the above guidewire, the resin layer may include an inner resin layer located inside the center line of the coil, and the thickness of the inner resin layer may be smaller than the thickness of the outer resin layer. Since the thickness of the inner resin layer is smaller than the thickness of the outer resin layer, the guidewire can more effectively achieve both smoothness and flexibility of the guidewire.

[0011] (4) In the above guidewire, the outer surface of the outer resin layer may be smoother than the inner surface of the inner resin layer. Since the outer surface of the outer resin layer is smoother than the inner surface of the inner resin layer, the lubricity of the guidewire can be more effectively improved.

[0012] (5) In the above guidewire, the outer surface of the hydrophilic coating layer may be smoother than the inner surface of the inner resin layer. In this guidewire, the outer surface of the hydrophilic coating layer is smoother than the inner surface of the inner resin layer, which can more effectively improve the slipperiness of the guidewire.

[0013] (6) In the above guidewire, the film thickness may be 0.010 mm or more and 0.119 mm or less. Since the film thickness of the outer layer portion of the resin layer is within the above range, the guidewire has good lubricity and flexibility. Therefore, the guidewire can more effectively achieve both the lubricity and flexibility of the guidewire.

[0014] (7) In the above guidewire, the tip load of the guidewire may be 10 mN or less. Since the tip load of the guidewire is within the above range, the guidewire has good flexibility. Therefore, the guidewire can more effectively achieve both smoothness and flexibility of the guidewire.

[0015] (8) In the above guidewire, the film thickness may be 0.018 mm or more and 0.063 mm or less. Since the film thickness of the outer layer portion of the resin layer is within the above range, the guidewire has good lubricity and flexibility. Therefore, the guidewire can more effectively achieve both the lubricity and flexibility of the guidewire.

[0016] (9) In the above guidewire, the tip load of the guidewire may be 8 mN or less. Since the tip load of the guidewire is within the above range, the guidewire has good flexibility. Therefore, the guidewire can more effectively achieve both smoothness and flexibility of the guidewire.

[0017] (10) In the guidewire, the resin layer may have a first layer covering the surface of the coil and a second layer covering an outer surface of the first layer, thereby achieving both smoothness and flexibility of the guidewire.

[0018] (11) In the above guidewire, the thickness of the first layer may be smaller than the thickness of the second layer. Since the thickness of the first layer is smaller than the thickness of the second layer, the guidewire can more effectively achieve both smoothness and flexibility of the guidewire.

[0019] (12) In the above guidewire, the resin layer may be formed of polyurethane. This guidewire can achieve both smoothness and flexibility.

[0020] (13) The guidewire may further include a distal joint portion that joins a distal end of the core shaft and a distal end of the coil, and the resin layer may cover the distal joint portion. This guidewire can achieve both smoothness and flexibility.

[0021] (14) The guidewire may further include a proximal joint portion that joins the core shaft and a proximal end of the coil. This guidewire can achieve both smoothness and flexibility.

[0022] (15) In the above guidewire, the core shaft may be made of at least one of stainless steel and a Ni—Ti alloy. This guidewire can achieve both smoothness and flexibility.

[0023] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a guidewire, a method for manufacturing a guidewire, etc.

[0024] FIG. 1 is an explanatory diagram showing a schematic view of a guidewire according to a first embodiment; FIG. 2 is an explanatory diagram showing an enlarged view of a portion of the longitudinal cross section of the guidewire according to the first embodiment; FIG. 3 is an explanatory diagram showing an enlarged view of a portion of the longitudinal cross section of the guidewire according to the first embodiment; FIG. 4 is an explanatory diagram showing a method for measuring the tip load of the guidewire; FIG. 5 is an explanatory diagram showing a method for measuring the frictional resistance of the guidewire;

[0025] FIG. 1 is an explanatory diagram schematically illustrating a guidewire 10 according to a first embodiment. FIG. 1 shows a longitudinal cross section of the guidewire 10. The longitudinal cross section is a cross section (YZ cross section) parallel to the longitudinal direction (Z-axis direction) of the guidewire 10. FIG. 1 omits the illustration of a portion of the guidewire 10. In FIG. 1 , the positive Z-axis direction side is the distal end side (distal side) that is inserted into the body, and the negative Z-axis direction side is the proximal end side (proximal side) that is manipulated by a surgeon such as a doctor. FIG. 1 shows the guidewire 10 in a state in which the entire guidewire 10 is linear and substantially parallel to the Z-axis direction. The guidewire 10 is flexible enough to be bent. This also applies to the subsequent figures. In this specification, with regard to the guidewire 10 and each member included in the guidewire 10, the distal end will be referred to as the "distal end," the distal end and its vicinity will be referred to as the "distal portion," the proximal end will be referred to as the "proximal end," and the proximal end and its vicinity will be referred to as the "proximal portion."

[0026] The guidewire 10 is a medical device that is inserted into a biological lumen such as a blood vessel. The guidewire 10 is used, for example, to guide another medical device such as a catheter to a desired position within the biological lumen. The total length of the guidewire 10 is, for example, approximately 1500 mm or more and 3000 mm or less.

[0027] The guidewire 10 includes a core shaft 100 , a coil 200 , a coating layer 300 , an intermediate fixing portion 400 , a distal joint portion 500 , and a proximal joint portion 600 .

[0028] The core shaft 100 is an elongated member extending along the Z-axis direction. The core shaft 100 has a large diameter portion 110, a first tapered portion 120, a small diameter portion 130, and a second tapered portion 140. The large diameter portion 110, the first tapered portion 120, the small diameter portion 130, and the second tapered portion 140 are arranged in this order from the base end to the tip end of the core shaft 100. The outer diameter of the large diameter portion 110 is constant from the base end to the tip end. The outer diameter of the first tapered portion 120 gradually decreases from the base end to the tip end. The outer diameter of the small diameter portion 130 is constant from the base end to the tip end. The outer diameter of the second tapered portion 140 gradually decreases from the base end to the tip end. That is, in the core shaft 100, the portion with the largest outer diameter is the large diameter portion 110, and the portion with the smallest outer diameter is the tip end of the second tapered portion 140. The cross section (XY cross section) at each position of the core shaft 100 may have any shape. The cross section of the core shaft 100 may have, for example, a circular shape. The overall length of the core shaft 100 may have any value.

[0029] There are no particular limitations on the material of the core shaft 100. The core shaft 100 may be formed from, for example, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, piano wire, nickel-chromium alloy, cobalt alloy, tungsten, etc. The surface of the core shaft 100 may be coated with, for example, PTFE, etc.

[0030] 2 is an explanatory diagram showing an enlarged portion of the longitudinal cross section of the guide wire 10 of the first embodiment. The coil 200 is a coil-shaped member formed by helically winding a metal wire 210. The coil 200 extends along the Z-axis direction. The coil 200 covers the core shaft 100 from the outside.

[0031] There are no particular limitations on the material of the coil 200. The coil 200 may be formed from, for example, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, piano wire, platinum, gold, tungsten, cobalt alloy, nickel-chromium alloy, etc.

[0032] Fig. 3 is an explanatory diagram showing an enlarged portion of the longitudinal cross section of the guide wire 10 of the first embodiment. Fig. 3 shows an enlarged view of the coil 200 and the coating layer 300. The coating layer 300 covers the coil 200. The coating layer 300 has a resin layer 310 and a hydrophilic coating layer 320.

[0033] The resin layer 310 covers the surface of the coil 200. The resin layer 310 covers a portion of the tip side of the coil 200 (see FIG. 1). The resin layer 310 also covers the surface of the tip side joint portion 500 (see FIG. 1). The resin layer 310 includes an outer resin layer 310o and an inner resin layer 310i.

[0034] The outer resin layer 310o is a portion of the resin layer 310 located outside the center line 200c of the coil 200. The inner resin layer 310i is a portion of the resin layer 310 located inside the center line 200c of the coil 200. In this specification, the center line 200c is a virtual line located at the center between the outer circumferential line 200oc and the inner circumferential line 200ic of the coil 200 in the longitudinal cross section of the guidewire 10. The outer circumferential line 200oc is a virtual line connecting the outermost portions of the wire 210 in the longitudinal cross section of the guidewire 10. The inner circumferential line 200ic is a virtual line connecting the innermost portions of the wire 210 in the longitudinal cross section of the guidewire 10. A portion of the coating layer 300 located outside the outer circumferential line 200oc of the coil 200 is defined as an outer layer portion 300op.

[0035] There are no particular limitations on the material of the resin layer 310. The resin layer 310 may be formed of, for example, polyurethane, polyester, polyimide, polyamide elastomer, nylon, vinyl chloride, polyethylene, polypropylene, or the like.

[0036] The hydrophilic coating layer 320 covers the outer resin layer 310o of the resin layer 310 from the outside. The hydrophilic coating layer 320 also covers the proximal side of the coil 200, that is, the portion of the coil 200 that is not covered by the resin layer 310 (see FIG. 1). The hydrophilic coating layer 320 also covers the surface of the proximal joint portion 600 (see FIG. 1). The hydrophilic coating layer 320 improves the slipperiness of the guidewire 10 by, for example, absorbing water and swelling in the human body.

[0037] There are no particular limitations on the material of the hydrophilic coating layer 320. The hydrophilic coating layer 320 is formed from, for example, a polymer obtained by polymerizing a monomer such as maleic acid, acrylic acid, methacrylic acid, dimethylacrylamide, carboxybetaine, phosphobetaine, sulfobetaine, methoxyethyl acrylate, hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, hyaluronic acid, polyvinylpyrrolidone, or polyethylene glycol.

[0038] The intermediate fixing portion 400 is a member that joins the core shaft 100 and the coil 200 near the middle of the coil 200 in the Z-axis direction. The distal joint portion 500 is a member that joins the distal end of the core shaft 100 and the distal end of the coil 200. The proximal joint portion 600 is a member that joins the core shaft 100 and the proximal end of the coil 200.

[0039] There are no particular limitations on the materials of the intermediate fixing portion 400, the distal bonding portion 500, and the proximal bonding portion 600. The intermediate fixing portion 400, the distal bonding portion 500, and the proximal bonding portion 600 are formed, for example, from metal solder (Au—Sn alloy, Sn—Ag alloy, Sn—Pb alloy, Pb—Ag alloy, etc.), brazing material (aluminum alloy brazing, silver brazing, gold brazing, etc.), adhesive (epoxy adhesive, etc.), etc. The intermediate fixing portion 400, the distal bonding portion 500, and the proximal bonding portion 600 may be formed from the same material or from different materials.

[0040] The thickness T1 (see FIG. 2 ) of the outer layer portion 300op of the coating layer 300, which is the value obtained by subtracting the outer diameter 200d of the coil 200 from the outer diameter 10d of the guidewire 10, is 0.006 mm or more and 0.259 mm or less. A preferred value for thickness T1 is 0.010 mm or more and 0.119 mm or less. A more preferred value for thickness T1 is 0.018 mm or more and 0.063 mm or less. The tip load of the guidewire 10 is 15 mN or less. A preferred value for the tip load of the guidewire is 10 mN or less. A more preferred value for the tip load of the guidewire is 8 mN or less. In this specification, the outer diameter 200d refers to the radial distance of the guidewire 10 between the outer circumferential line 200oc on one side (positive Y-axis direction) of the core shaft 100 and the outer circumferential line 200oc on the other side (negative Y-axis direction) of the core shaft 100.

[0041] A method for measuring the film thickness T1 will be described. First, the operator measures the outer diameter 10d of the guidewire 10 using a laser outer diameter measuring device. In this case, the outer diameter 10d of the guidewire 10 means the average outer diameter of the guidewire from the tip of the guidewire 10 to a portion separated by an arbitrary length from the tip of the guidewire 10. The arbitrary length is the length of the resin layer 310 in the longitudinal direction of the guidewire 10. The operator obtains the value obtained by subtracting the outer diameter 200d of the coil 200 from the outer diameter 10d of the guidewire 10 as the film thickness T1.

[0042] 4 is an explanatory diagram showing a method for measuring the tip load of guidewire 10. First, the operator sets tubular body 24 above electronic balance 22. At this time, the shortest distance L1 from electronic balance 22 to tubular body 24 is set to 10.5 mm. The operator inserts guidewire 10 into tubular body 24 from above, causing the tip of guidewire 10 to protrude from the lower end of tubular body 24. In this state, the operator presses the tip of guidewire 10 against electronic balance 22, and obtains the load measured by electronic balance 22 as the tip load of guidewire 10.

[0043] 5 is an explanatory diagram showing a method for measuring the frictional resistance of the guidewire 10. First, the operator places the guidewire 10 on the measurement table 33. The operator fixes the proximal end of the guidewire 10 with the fixing portion 32. The operator places the urethane roller 34 on the guidewire 10. A weight 35 with a mass of 100 g is placed on the urethane roller 34. In this state, the operator moves the measurement table 33 and the urethane roller 34 toward the distal end of the guidewire 10, and obtains the load measured by the force gauge 31 as the frictional resistance of the guidewire 10.

[0044] The coating layer 300 will be described in further detail with reference to Fig. 3. The inner surface S1 of the inner resin layer 310i has projections and recesses that conform to the shape of the surface of the coil 200. That is, the inner surface S1 of the inner resin layer 310i has a plurality of projections 313 that protrude radially inward of the guidewire 10.

[0045] The thickness T2 of the inner resin layer 310i is smaller than the thickness T3 of the outer resin layer 310o. In this specification, the thickness T2 of the inner resin layer 310i refers to the distance in the radial direction of the guidewire 10 between the inner circumferential line 200ic of the coil 200 and the inner circumferential line 310ic of the resin layer 310. The inner circumferential line 310ic is an imaginary line connecting multiple convex portions 313 of the resin layer 310 in a vertical cross section of the guidewire 10. In this specification, the thickness T3 of the outer resin layer 310o refers to the distance between the outer circumferential line 200oc of the coil 200 and the outer circumferential line 310oc of the resin layer 310.

[0046] The thickness T3 of the outer resin layer 310o is greater than the thickness T6 of the hydrophilic coating layer 320. In this specification, the thickness T6 of the hydrophilic coating layer 320 refers to the radial distance of the guide wire 10 between the outer circumferential line 310oc of the resin layer 310 and the surface S3 of the hydrophilic coating layer 320.

[0047] The outer surface S2 of the outer resin layer 310o is smoother than the inner surface S1 of the inner resin layer 310i. The outer surface S3 of the hydrophilic coating layer 320 is smoother than the inner surface S1 of the inner resin layer 310i. These are due to the fact that the inner surface S1 of the inner resin layer 310i has irregularities that follow the shape of the surface of the coil 200, as described above.

[0048] The resin layer 310 has a first layer 311 and a second layer 312. The first layer 311 covers the surface of the coil 200. The first layer 311 covers the entire circumference of the wires 210 in a longitudinal cross section of the guidewire 10. The second layer 312 covers the outer surface S4 of the first layer 311. As shown in FIG. 3 , the outer resin layer 310o is formed by a part of the outer side of the first layer 311 and the second layer 312. The inner resin layer 310i is formed by a part of the inner side of the first layer 311. The first layer 311 and the second layer 312 may be formed of the same material or different materials.

[0049] The outer surface S4 of the first layer 311 has projections and recesses that follow the shape of the surface of the coil 200. In other words, the outer surface S4 of the first layer 311 has a plurality of projections 315 that protrude outward in the radial direction of the guide wire 10.

[0050] The thickness T4 of the first layer 311 is smaller than the thickness T5 of the second layer 312. In this specification, the thickness T4 of the first layer 311 refers to the distance in the radial direction of the guidewire 10 between the outer circumferential line 200oc of the coil 200 and the outer circumferential line 311oc of the first layer 311. The outer circumferential line 311oc is a virtual line connecting the multiple convex portions 315 of the first layer 311 in the longitudinal cross section of the guidewire 10. In this specification, the thickness T5 of the second layer 312 refers to the distance in the radial direction of the guidewire 10 between the outer circumferential line 311oc of the first layer 311 and the outer circumferential line 310oc of the resin layer 310.

[0051] The coating layer 300 as described above can be manufactured, for example, as follows. First, a resin solution, which is a precursor of the first layer 311, is applied to the surface of the coil 200 so as to cover the entire circumference of the wire 210. The precursor of the first layer 311 is dried to volatilize the solvent of the resin solution, thereby forming the first layer 311. The resin solution, which is a precursor of the second layer 312, is applied to the outer surface of the first layer 311 in a thickness greater than that of the first layer 311. The precursor of the second layer 312 is dried to volatilize the solvent of the resin solution, thereby forming the second layer 312. A solution of a material, which is a precursor of the hydrophilic coating layer 320, is applied to the outer surface of the second layer 312. The precursor of the hydrophilic coating layer 320 is dried to volatilize the solvent of the solution, thereby forming the hydrophilic coating layer 320.

[0052] As described above, the guidewire 10 of this embodiment includes the core shaft 100, the coil 200 that covers the core shaft 100 from the outside, and the coating layer 300 that covers the coil 200. The coating layer 300 has a resin layer 310 that covers the surface of the coil 200. The resin layer 310 includes an outer resin layer 310o that is located outside the center line 200c of the coil 200. The film thickness T1 of the outer layer portion 300op of the coating layer 300, which is the value obtained by subtracting the outer diameter 200d of the coil 200 from the outer diameter 10d of the guidewire 10, is 0.006 mm or more and 0.259 mm or less. The tip load of the guidewire 10 is 15 mN or less.

[0053] The guidewire 10 of this embodiment has good smoothness and flexibility because the film thickness T1 of the outer layer portion 300op of the coating layer 300 is within the above-mentioned range. The guidewire 10 of this embodiment has good flexibility because the tip load of the guidewire 10 is within the above-mentioned range. Therefore, the guidewire 10 of this embodiment can achieve both good smoothness and flexibility.

[0054] In the guidewire 10 of this embodiment, the covering layer 300 further has a hydrophilic coating layer 320 that covers the resin layer 310 from the outside. Since the covering layer 300 of the guidewire 10 of this embodiment has the hydrophilic coating layer 320, the lubricity of the guidewire can be more effectively improved.

[0055] In the guidewire 10 of this embodiment, the resin layer 310 includes an inner resin layer 310i located inside the center line 200c of the coil 200, and the thickness T2 of the inner resin layer 310i is smaller than the thickness T3 of the outer resin layer 310o. An increase in the thickness of the inner resin layer reduces the flexibility of the guidewire, but does not significantly affect the lubricity of the guidewire. In other words, it is preferable that the thickness of the inner resin layer is relatively small. In the guidewire 10 of this embodiment, the thickness T2 of the inner resin layer 310i is smaller than the thickness T3 of the outer resin layer 310o, so that both the lubricity and flexibility of the guidewire can be more effectively achieved.

[0056] In the guidewire 10 of this embodiment, the outer surface S2 of the outer resin layer 310o is smoother than the inner surface S1 of the inner resin layer 310i. In the guidewire 10 of this embodiment, the outer surface S2 of the outer resin layer 310o is smoother than the inner surface S1 of the inner resin layer 310i, which more effectively improves the lubricity of the guidewire.

[0057] In the guidewire 10 of this embodiment, the outer surface S3 of the hydrophilic coating layer 320 is smoother than the inner surface S1 of the inner resin layer 310i. In the guidewire 10 of this embodiment, the outer surface S3 of the hydrophilic coating layer 320 is smoother than the inner surface S1 of the inner resin layer 310i, which more effectively improves the lubricity of the guidewire.

[0058] In the guidewire 10 of this embodiment, the thickness T1 is 0.010 mm or more and 0.119 mm or less. Since the thickness T1 of the outer layer portion 300op of the coating layer 300 is within the above-mentioned range, the guidewire 10 of this embodiment has good slipperiness and flexibility. Therefore, the guidewire 10 of this embodiment can more effectively achieve both slipperiness and flexibility of the guidewire.

[0059] In the guidewire 10 of this embodiment, the tip load of the guidewire 10 is 10 mN or less. Since the tip load of the guidewire 10 is within the above range, the guidewire 10 of this embodiment has good flexibility. Therefore, the guidewire 10 of this embodiment can more effectively achieve both guidewire smoothness and guidewire flexibility.

[0060] In the guidewire 10 of this embodiment, the thickness T1 is 0.018 mm or more and 0.063 mm or less. Since the thickness T1 of the outer layer portion 300op of the coating layer 300 is within the above-mentioned range, the guidewire 10 of this embodiment has good slipperiness and flexibility. Therefore, the guidewire 10 of this embodiment can more effectively achieve both slipperiness and flexibility of the guidewire.

[0061] In the guidewire 10 of this embodiment, the tip load of the guidewire 10 is 8 mN or less. Since the tip load of the guidewire 10 is within the above range, the guidewire 10 of this embodiment has good flexibility. Therefore, the guidewire 10 of this embodiment can more effectively achieve both guidewire smoothness and guidewire flexibility.

[0062] In the guidewire 10 of this embodiment, the resin layer 310 has a first layer 311 that covers the surface of the coil 200 and a second layer 312 that covers the outer surface S4 of the first layer 311. The guidewire 10 of this embodiment can achieve both good guidewire slipperiness and good guidewire flexibility.

[0063] In the guidewire 10 of this embodiment, the thickness T4 of the first layer 311 is smaller than the thickness T5 of the second layer 312. If the thickness of the first layer is increased, the flexibility of the guidewire will decrease, but the lubricity of the guidewire will not be significantly affected. In other words, it is preferable that the thickness of the first layer is relatively small. In the guidewire 10 of this embodiment, the thickness T4 of the first layer 311 is smaller than the thickness T5 of the second layer 312, and therefore, the lubricity and flexibility of the guidewire can be more effectively achieved.

[0064] In the guidewire 10 of this embodiment, the resin layer 310 is made of polyurethane. The guidewire 10 of this embodiment can achieve both good guidewire lubricity and good guidewire flexibility.

[0065] The guidewire 10 of this embodiment further includes a distal joint 500 that joins the distal end of the core shaft 100 and the distal end of the coil 200, and the resin layer 310 covers the distal joint 500. The guidewire 10 of this embodiment can achieve both good guidewire smoothness and good guidewire flexibility.

[0066] The guidewire 10 of this embodiment further includes a proximal joint 600 that joins the core shaft 100 and the proximal end of the coil 200. The guidewire 10 of this embodiment can achieve both good guidewire smoothness and flexibility.

[0067] In the guidewire 10 of this embodiment, the core shaft 100 is formed of at least one of stainless steel and a Ni—Ti alloy. The guidewire 10 of this embodiment can achieve both smoothness and flexibility of the guidewire.

[0068] Examples of this embodiment are described below. Nine guidewire samples (SA1 to SA9) with different film thicknesses were prepared, and performance evaluations were performed on each sample. The resin layer of each sample used in this performance evaluation was made of polyurethane. Samples SA1 to SA8 have coating layers formed from a resin layer and a hydrophilic coating layer. Sample SA9 has a coating layer formed from a hydrophilic coating layer. Tables 1 and 2 are tables showing the performance evaluation results. Figures 6 and 7 are graphs showing the performance evaluation results.

[0069]

[0070]

[0071] In this performance evaluation, the thickness T1 of the guide wire 10, the tip load of the guide wire 10, and the frictional resistance of the guide wire 10 were measured according to the measurement method described above (see FIGS. 2 and 3).

[0072] Table 1 shows the film thickness T1 and tip load of samples SA1 to SA8. Fig. 6 is a scatter plot showing the measured values ​​of film thickness T1 and tip load of samples SA1 to SA8. Fig. 6 shows multiple points indicating the measured values ​​of each sample and an approximation line calculated based on the multiple points. The vertical axis of Fig. 6 represents the guidewire tip load (mN), and the horizontal axis of Fig. 6 represents the guidewire film thickness T1 (mm).

[0073] Table 2 shows the film thickness T1 and frictional resistance of samples SA1 to SA3, SA8, and SA9. Figure 7 is a scatter plot showing the measured film thickness T1 and frictional resistance of samples SA1 to SA3, SA8, and SA9. Figure 7 shows multiple points representing the measured values ​​of each sample and an approximation curve calculated based on the multiple points. The vertical axis of Figure 7 represents the frictional resistance (mN) of the guidewire, and the horizontal axis of Figure 7 represents the film thickness T1 (mm) of the guidewire.

[0074] As shown in Table 1 and Figure 6, the smaller the guidewire thickness T1, the smaller the guidewire tip load tends to be. In other words, there is a proportional relationship between the guidewire thickness T1 and the guidewire tip load. The guidewire thickness T1 correlates with the amount of resin material covering the coil. In other words, the smaller the guidewire thickness T1 of the sample, the less resin material covering the coil, and therefore the greater the flexibility of the guidewire. When the guidewire tip load is y and the guidewire thickness T1 is x, the approximate straight line shown in Figure 6 can be expressed as the following equation (1): y = 35.763x + 5.7407 (R ２ = 0.9641) ... (1) Based on equation (1), it was found that the thickness T1 when the guidewire tip load was 15 mN was 0.259 mm, the thickness T1 when the guidewire tip load was 10 mN was 0.119 mm, and the thickness T1 when the guidewire tip load was 8 mN was 0.063 mm. The lower the tip load, the better the flexibility of the guidewire tip. When the tip load was 15 mN or less, i.e., the thickness T1 was 0.259 mm or less, the flexibility of the guidewire tip was good. When the tip load was 10 mN or less, i.e., the thickness T1 was 0.119 mm or less, the flexibility of the guidewire tip was even better. When the tip load was 8 mN or less, i.e., the thickness T1 was 0.063 mm or less, the flexibility of the guidewire tip was best. In other words, the smaller the thickness T1, the better the flexibility of the guidewire.

[0075] As shown in Table 2 and Figure 7, the greater the thickness T1 of the guidewire, the smaller the frictional resistance of the guidewire. In other words, there is an inverse proportional relationship between thickness T1 of the guidewire and frictional resistance of the guidewire. When thickness T1 of the guidewire is small, the surface of the coating layer has irregularities that follow the shape of the coil surface. In other words, it is thought that the greater the thickness T1 of the guidewire, the smaller the irregularities on the surface of the coating layer, and therefore the higher the lubricity of the guidewire. When the friction coefficient of the guidewire is y and thickness T1 of the guidewire is x, the approximation curve shown in Figure 7 can be expressed as the following equation (2): y = 6.0876 / x ０．６９２(R ２ = 0.8956) ... (2) Based on equation (2), it was found that the film thickness T1 when the frictional resistance was 200 mN was 0.006 mm, the film thickness T1 when the frictional resistance was 150 mN was 0.010 mm, and the film thickness T1 when the frictional resistance was 100 mN was 0.018 mm. The smaller the frictional resistance value, the better the guidewire's slipperiness. When the frictional resistance value is 200 mN or less, i.e., when the film thickness T1 is 0.006 mm or more, the guidewire's slipperiness is good. When the frictional resistance value is 150 mN or less, i.e., when the film thickness T1 is 0.010 mm or more, the guidewire's slipperiness is even better. When the frictional resistance value is 100 mN or less, i.e., when the film thickness T1 is 0.018 mm or more, the guidewire's slipperiness is best. In other words, the larger the film thickness T1, the better the guidewire's slipperiness.

[0076] As described above, to improve the flexibility of a guidewire, the thickness T1 must be reduced. On the other hand, to improve the lubricity of a guidewire, the thickness T1 must be increased. Therefore, in order to study the value of thickness T1 that can achieve both flexibility and lubricity of a guidewire, the inventors prepared nine samples (SA1 to SA9) with different thicknesses and measured the tip load and frictional resistance values, obtaining the data shown in Figures 6 and 7 . The results in Figures 6 and 7 indicate that when the thickness T1 of the guidewire is 0.006 mm or more and 0.259 mm or less, both the lubricity and flexibility of the guidewire can be achieved. The results in Figures 6 and 7 indicate that when the thickness T1 of the guidewire is 0.010 mm or more and 0.119 mm or less, both the lubricity and flexibility of the guidewire can be achieved more effectively. The results in Figures 6 and 7 indicate that when the thickness T1 is 0.018 mm or more and 0.063 mm or less, both the lubricity and flexibility of the guidewire can be achieved most effectively.

[0077] 8 is an explanatory diagram schematically illustrating a guidewire 10a according to a second embodiment. In the following, among the components of the guidewire 10a according to the second embodiment, components common to the guidewire 10 according to the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0078] The coating layer 300 of the guidewire 10a of the second embodiment has a resin layer 310a and a hydrophilic coating layer 320a. The resin layer 310a covers the entire coil 200 from the proximal end to the distal end. The resin layer 310a also covers the distal joint 500. The resin layer 310a also covers the proximal joint 600. The hydrophilic coating layer 320a covers the resin layer 310a from the proximal end to the distal end. Like the guidewire 10 of the first embodiment, the guidewire 10a of the second embodiment can achieve both guidewire smoothness and guidewire flexibility.

[0079] 9 is an explanatory diagram showing an enlarged portion of a longitudinal cross section of the guidewire 10b of the third embodiment. In the following, among the components of the guidewire 10b of the third embodiment, components common to the guidewire 10 of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0080] The coating layer 300 of the guidewire 10b of the third embodiment includes a resin layer 310b and a hydrophilic coating layer 320. The resin layer 310b is formed of a single layer. That is, while the resin layer 310 of the guidewire 10 of the first embodiment is formed of two layers, a first layer 311 and a second layer 312, the resin layer 310b of the guidewire 10b of the third embodiment is formed of a single layer.

[0081] The guidewire 10b of the third embodiment can achieve both smoothness and flexibility, similar to the guidewire 10 of the first embodiment. Furthermore, in the guidewire 10b of the third embodiment, the resin layer 310b is formed of a single layer. Therefore, the guidewire 10b is free from the risk of peeling between the first and second layers, which can occur when the guidewire 10b is formed of two or more layers, and the durability of the guidewire 10b can be improved.

[0082] 10 is an explanatory diagram showing an enlarged portion of a longitudinal cross section of a guidewire 10c according to a fourth embodiment. In the following, among the components of the guidewire 10c according to the fourth embodiment, components common to the guidewire 10 according to the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0083] The thickness T6c of the hydrophilic coating layer 320c in the guidewire 10c of the fourth embodiment is greater than the thickness T6 of the hydrophilic coating layer 320 in the first embodiment. In the guidewire 10c of the fourth embodiment, the thickness T3 of the outer resin layer 310o is smaller than the thickness T6c of the hydrophilic coating layer 320c. The guidewire 10b of the fourth embodiment, like the guidewire 10 of the first embodiment, can achieve both guidewire smoothness and guidewire flexibility.

[0084] The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0085] The guidewire in the above embodiment is merely an example, and various modifications are possible. For example, the guidewire may include a multi-filament coil made up of two or more coils overlapping each other in the radial direction of the guidewire.

[0086] The guidewire does not necessarily have to have a hydrophilic coating layer.

[0087] In the guidewire, the thickness of the inner resin layer does not necessarily have to be smaller than the thickness of the outer resin layer.The resin layers in the guidewire do not necessarily have to include the inner resin layer.

[0088] In the guidewire, the surface of the inner resin layer may be smoother than the surface of the outer resin layer.In the guidewire, the surface of the inner resin layer may be smoother than the surface of the hydrophilic coating layer.

Claims

1. A guidewire (10) comprising: a core shaft (100); a coil (200) externally covering the core shaft (100); and a coating layer (300) covering the coil (200), wherein the coating layer (300) has a resin layer (310) covering the surface of the coil (200), and the resin layer (310) includes an outer resin layer (310o) located outside a center line (200c) of the coil (200); wherein a film thickness (T1) of an outer layer portion (300op) ​​of the coating layer (300), which is the value obtained by subtracting the outer diameter (200d) of the coil (200) from the outer diameter (10d) of the guidewire (10), is 0.006 mm or more and 0.259 mm or less; and a tip load of the guidewire (10) is 15 mN or less.

2. A guide wire (10) according to claim 1, wherein the covering layer (300) further comprises a hydrophilic coating layer (320) that covers the resin layer (310) from the outside.

3. A guide wire (10) according to claim 2, wherein the resin layer (310) includes an inner resin layer (310i) located inside the center line (200c) of the coil (200), and the thickness (T2) of the inner resin layer (310i) is smaller than the thickness (T3) of the outer resin layer (310o).

4. A guide wire (10) according to claim 3, wherein the outer surface (S2) of the outer resin layer (310o) is smoother than the inner surface (S1) of the inner resin layer (310i).

5. A guide wire (10) according to claim 3 or claim 4, wherein the outer surface (S3) of the hydrophilic coating layer (320) is smoother than the inner surface (S1) of the inner resin layer (310i).

6. A guidewire (10) according to any one of claims 1 to 5, wherein the thickness (T1) is 0.010 mm or more and 0.119 mm or less.

7. A guide wire (10) according to any one of claims 1 to 6, wherein the tip load of the guide wire (10) is 10 mN or less.

8. A guidewire (10) according to any one of claims 1 to 7, wherein the thickness (T1) is 0.018 mm or more and 0.063 mm or less.

9. A guide wire (10) according to any one of claims 1 to 8, wherein the tip load of the guide wire (10) is 8 mN or less.

10. A guide wire (10) according to any one of claims 1 to 9, wherein the resin layer (310) has a first layer (311) covering the surface of the coil (200) and a second layer (312) covering the outer surface (S4) of the first layer (311).

11. A guidewire (10) according to claim 10, wherein the thickness (T4) of the first layer (311) is smaller than the thickness (T5) of the second layer (312).

12. A guidewire (10) according to any one of claims 1 to 11, wherein the resin layer (310) is formed from polyurethane.

13. A guide wire (10) according to any one of claims 1 to 12, further comprising a tip-side joint (500) that joins the tip of the core shaft (100) and the tip of the coil (200), and the resin layer (310) covers the tip-side joint (500).

14. A guidewire (10) according to any one of claims 1 to 13, further comprising a proximal joint (600) joining the core shaft (100) and the proximal end of the coil (200).

15. A guidewire (10) according to any one of claims 1 to 14, wherein the core shaft (100) is formed from at least one of stainless steel and a Ni-Ti alloy.

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