Wire material for medical use and guide wire

Abstract

To provide a wire material for medical use and a guide wire having superior resilience.SOLUTION: A resilience rate after applying a strain amount of 2% by bending each end portion so as to approach each other is 96% or more. The strain amount (%) is (R / (L-R))×100, where R is the wire diameter of the wire material, and L is the distance between both end portions when the end portions are bent so as to approach each other. The resilience rate (%) is (1-θ / 180)×100, where θ is an angle at which two tangent lines drawn from both ends of the wire material after bending intersect.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to medical wires.

Background Art

[0002] When treating stenosis that has occurred in blood vessels such as coronary arteries surrounding the heart, or when treating a site where the inside of the blood vessel has become completely blocked due to the progression of calcification (for example, chronic total occlusion: CTO, etc.), a guide wire for guiding these is inserted into the blood vessel prior to treatment instruments such as balloon catheters.

[0003] For example, a guide wire made of SUS304 has been proposed in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the above guide wire, it is known that there is a correlation between the operability of the guide wire and the difficulty of getting used to it (recoverability). However, no guide wire having excellent recoverability has been proposed.

[0006] An object of the present disclosure is to provide a medical wire and a guide wire having excellent recoverability.

Means for Solving the Problems

[0007] In order to solve the above problems, a medical wire according to one embodiment of the present disclosure is a medical wire made of stainless steel. After bending each end so as to approach each other and applying a strain of 2%, the recovery rate is 96% or more. The strain (%) = (R / (L - R)) × 100 (where R is the wire diameter of the wire and L is the distance between both ends when the ends are bent so as to approach each other), and the recovery rate (%) = (1 - θ / 180) × 100 (where θ is the angle at which two tangents intersect when tangents are drawn from both ends of the bent wire).

[0008] The stainless steel has a tensile strength of 2800 N / mm 2 or more and may be less than 3400 N / mm 2

[0009] The stainless steel may be austenitic stainless steel conforming to ASTM F2581.

[0010] When the wire is bent 180°, no breakage may occur at the bent portion.

[0011] A guide wire according to one embodiment of the present disclosure includes the above medical wire and a coil body provided thereon.

Advantages of the Invention

[0012] The present disclosure can provide a medical wire and a guide wire with excellent resilience.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0014] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited only to the embodiments described in the drawings.

[0015] FIG. 1 is a schematic cross-sectional view of a guide wire 1 according to an embodiment of the present disclosure.

[0016] As shown in FIG. 1, the guide wire 1 includes a core shaft 10, a coil body 20, a tip joint portion 30, and a base end fixing portion 40.

[0017] The core shaft 10 has a tapered round bar shape that tapers from the base end toward the tip end. At the end on the base end side, rotational operations of the guide wire 1 by the user are performed.

[0018] The coil body 20 is formed in a hollow cylindrical shape by spirally winding a single metal wire 21 around the core shaft 10. As the material of the coil body 20, an X-ray impermeable material such as gold, platinum, tungsten, or an alloy containing these elements, or stainless steel, superelastic alloy, cobalt-based alloy, etc. can also be used.

[0019] The tip joint portion 30 constitutes the tip of the guide wire 1 and has a substantially hemispherical shape. As the material of the tip joint portion 30, metals such as silver, gold, or alloys thereof, lead-free solder, brazing material, or adhesive can be used.

[0020] The base end joint 40 secures the base end of the coil body 20 to the core shaft 10. As the material of the base end joint 40, for example, lead-free solders such as Sn-Ag alloy, Sn-Ag-Cu alloy, Au-Sn alloy, Au-Ge, or brazing materials are used.

[0021] The core shaft 10 is made of stainless steel conforming to ASTM F2581 (C: 0.15 - 0.25 mass%, Mn: 9.50 - 12.50 mass%, P: 0.020 mass% Max, S: 0.010 mass% Max, Si: 0.20 - 0.60 mass%, Cr: 16.5 - 18.0 mass%, Ni: 0.05 mass% Max, Mo: 2.70 - 3.70 mass%, N: 0.45 - 0.55 mass%, Cu: 0.25 mass Max, Fe: Bal.).

[0022] To manufacture the core shaft 10, the stainless steel steel material (base material) is subjected to wire drawing and straightening, and heat treatment.

[0023] The wire drawing is not particularly limited as long as it can continuously reduce the wire diameter of the steel material, and it may be processing by a die or processing by a roll. The area reduction rate of the wire during processing is preferably, for example, 80 - 97%. Here, the area reduction rate is defined as (1 - d1 2 / d0 2 ) × 100. d0 is the wire diameter of the base material (the wire before processing), and d1 is the wire diameter of the drawn wire (the wire after processing). The straightening is not particularly limited as long as it can correct the wire into a straight line, and it may be implemented by a combination of processing with a plurality of straightening rollers or a stretcher, tension annealing using heat treatment, etc.

[0024] The heat treatment is carried out at 300 - 800°C.

[0025] The wire after heat treatment is cut, and by performing taper processing on the end of this wire so that the outer diameter gradually becomes thinner toward the tip, the core shaft 10 is obtained. Note that the core shaft 10 may be manufactured by wire drawing and heat treatment without performing straightening.

[0026] As described below, the stainless steel wire rod constituting the core shaft 10 has a recovery rate of 96% or more after being bent so that the ends approach each other and a strain amount of 2% is applied. The stainless steel constituting the core shaft 10 has a tensile strength of 2800 N / mm 2 or more and less than 3400 N / mm 2 .

Examples

[0027] Next, various tests conducted to confirm the characteristics of the stainless steel wire rod constituting the core shaft 10 of the present disclosure will be described. The wire types used in the tests are shown in Table 1.

Table 1

[0028] Wire types A1 and A2, which are examples, are wire types made of stainless steel conforming to ASTM F2581. Wire type A3, which is an example, is a wire type composed of stainless steel having a larger nitrogen content and a smaller carbon content compared to ASTM F2581.

[0029] Wire types B1 and B2, which are comparative examples, are wire types composed of SUS304 stainless steel.

[0030] The tensile strengths of each of the wire types A1 - A3, B1, and B2 are the values shown in Table 1. The tensile test is, for example, JIS - Z 2241 "Method of Tensile Test for Metallic Materials". For wire types A1, A2, and A3, tensile tests were performed on a plurality of wire rods each, and the average values of the obtained tensile strengths are described in Table 1.

[0031] For the wire rods of the wire types in Table 1, a recovery evaluation, a bending evaluation, and a rotation performance evaluation were performed.

[0032] <Recovery evaluation> For each of the wire rods of wire types A1 - A3, which are examples, and wire types B1 and B2, which are comparative examples, the residual angle of each wire rod after being bent by the jig 2 shown in FIG. 2 was measured. Figure 2 is a schematic diagram of the jig 2 used for the restoration evaluation.

[0033] The jig 2 is made of, for example, stainless steel, and includes a main body portion 3 and a pushing-in portion 4. The main body portion 3 has a rectangular parallelepiped shape, and a pushing-in groove 3a that opens on two sides is formed. The pushing-in groove 3a has a substantially rectangular parallelepiped shape, and at its end, it has a pushing-in recess 3c configured to have a narrower width in the left-right direction than other parts. The pushing-in portion 4 has a rectangular parallelepiped shape and is configured to be insertable into the pushing-in groove 3a. For example, in FIG. 2, the width of the pushing-in groove 3a in the left-right direction is 50 mm, the depth of the pushing-in groove 3a is 1.0 mm, and the depth (width in the up-down direction in the figure) of the pushing-in recess 3c is 1.5 mm. The width of the pushing-in portion 4 in the left-right direction is configured to be slightly smaller than the width of the pushing-in hole 3a in the left-right direction, and the thickness of the pushing-in portion 4 is 1.0 mm.

[0034] Figure 3 is an explanatory diagram of the restoration evaluation.

[0035] As shown in FIG. 3(a), the pushing-in portion 4 is removed from the pushing-in groove 3a of the main body portion 3, and a wire X cut to a predetermined length (for example, 50 mm) is inserted into the pushing-in groove 3a. At this time, the end of the wire X is inserted into the pushing-in recess 3c and abutted against the end face 3B forming the pushing-in recess 3c. As shown in FIG. 3(b), the pushing-in portion 4 is inserted into the pushing-in groove 3a and pushed in until the wire X reaches a predetermined length (the pushing-in amount L (mm, the distance between the end face 3B and the end face 4A of the pushing-in portion 4)). As a result, the wire X is bent so that its respective ends approach each other. After holding the pushed-in state of the pushing-in portion 4 for about 10 seconds, the pushing-in portion 4 is removed from the pushing-in groove 3a, and the wire X is taken out. As a result, strain is added to the entire wire X. Strains were added to the wire X with the pushing-in amounts L (mm) being 30, 25, 20, 17.5, 15, 12.5, 10, and 7.5. Note that the pushing-in amount L corresponds to the distance of the portion on the side opposite to the side where the respective ends face each other when the wire X is bent so that the respective ends approach each other.

[0036] As shown in FIG. 4, tangents are drawn from both ends of the wire X, and the angle (residual angle θ) at which the two tangents intersect is measured, and the restoration rate is calculated. The restoration rate is calculated by (1 - θ / 180) × 100. The results of the residual angle and the restoration rate are shown in Table 2.

Table 2

[0037] Table 3 shows the amount of strain with respect to the amount of indentation for each wire diameter. The amount of strain (%) is calculated by (R / (L - R)) × 100. Here, R is the wire diameter of the wire material, and L is the amount of indentation L (Fig. 3(b)).

Table 3

[0038] Table 4 shows a list of the recovery rates according to the amount of strain for each wire type based on Tables 2 and 3. The description is omitted for the amount of strain of 1.1 or less.

Table 4

[0039] Fig. 5 is a graph showing the transition of the recovery rate according to the amount of strain for each wire type based on Table 4. As shown in Fig. 5, the recovery rates of wire types A1 - A3 at the amount of strain of 0 - 2% are 96% or more. That is, since the residual angle when a strain of 0 - 2% is applied to the wire material is smaller than about 7°, the recoverability is good, and a decrease in the rotational operability in the body lumen can be suppressed.

[0040] <Bending evaluation> Each wire material of wire types A1 - A3 as examples and wire types B1 and B2 as comparative examples was bent by about 180° to evaluate the occurrence of breakage.

[0041] Fig. 6 is an explanatory diagram of the bending test.

[0042] As shown in Fig. 6(a), forces F are applied to both ends of a wire rod Z cut to a predetermined length (e.g., 100 mm), the wire rod Z is bent as shown in Fig. 6(b), and the wire rod Z is bent at about 180° and held for several seconds (e.g., 10 seconds) as shown in Fig. 6(c). Then, the presence or absence of breakage in the bent portion of the wire rod Z is evaluated.

[0043] Table 5 shows the results of the presence or absence of breakage for each wire type.

Table 5

[0044] As shown in Table 5, breakage occurred in wire type A3 which is an example, but no breakage occurred in wire types A1 and A2 which are examples. For this reason, when it is assumed that the wire rod used as the core shaft of the guide wire bends at a relatively small radius of curvature, it is preferable to use wire types A1 and A2 rather than wire type A3. In addition, when it is assumed that the medical wire rod used as the core shaft of the guide wire bends at a relatively large radius of curvature, or when the medical wire rod used for applications other than the guide wire is assumed to bend at a relatively large radius of curvature, any of the wire rods in the examples may be used.

[0045] <Rotational operability evaluation> The rotational performance of the wire rods of wire types A1 and A2 which are examples and wire types B1 and B2 which are comparative examples was evaluated using the second jig 5 shown in Fig. 7. Fig. 7 is a schematic diagram of the second jig 5 used for the rotational performance evaluation.

[0046] The second jig 5 includes a wire insertion part 5A, an input part 5B, and an output part 5C. The wire insertion part 5A is made of resin (for example, a transparent acrylic plate), and a groove 6 is formed therein. The groove 6 opens at both ends of the substantially rectangular wire insertion part 5A. The width of the groove 6 is 1.0 mm. The groove 6 has a plurality of arc parts 6A, 6A, 6B, 6C. Each arc part 6A has the same radius of curvature. The arc parts 6B, 6C have a radius of curvature larger than that of each arc part 6A. In the present embodiment, the radius of curvature of the arc part 6A is 20 mm. The input part 5B has a substantially cylindrical shape and is rotatably provided, and the base end of the wire Y is connected thereto. The output part 5C has a substantially cylindrical shape and is rotatably provided, and the tip of the wire Y is connected thereto. When the radius of curvature of the arc part 6A is 20 mm, the length L between the input part 5B and the output part 5C is configured to be 390 mm. When the radius of curvature of the arc part 6A is 20 mm, the length L between the input part 5B and the output part 5C is configured to be 420 mm.

[0047] Using the second jig 5, the followability (following angle) of the output part 5C when the input part 5B is rotated clockwise was measured. The results are shown in FIGS. 8 and 9. FIG. 8 is a graph showing the relationship between the hand angle and the tip angle in the rotation performance evaluation of wire types A1 and B2 with a wire diameter of 0.34 mm. FIG. 9 is a graph showing the relationship between the hand angle and the tip angle in the rotation performance evaluation of wire types A2 and B1 with a wire diameter of 0.42 mm.

[0048] As shown in FIG. 8, the wire type A1 which is an example has rotation followability close to ideal (IDEAL), and the wire type B2 which is a comparative example has a worse initial rotation followability than the wire type A1 which is an example. As shown in FIG. 9, the wire type A2 which is an example has rotation followability close to ideal (IDEAL), and the wire type B1 which is a comparative example has a generally poor rotation followability. Thus, the wires made of stainless steel of wire types A1 and A2 have excellent rotation followability. Since the guide wire 1 in FIG. 1 includes the core shaft 10 made of the stainless steel, a guide wire 1 having excellent rotation followability can be provided.

[0049] Note that the present disclosure is not limited to the configurations of the above-described embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0050] For example, in the above embodiment, the medical wire was the core shaft 10 of the guide wire 1, but it may be a wire constituting the coil body 20, or a wire used for other medical instruments, for example, a wire constituting a reinforcing member (for example, a cylindrical wire mesh, a coil body) used for reinforcing a catheter. By using the medical wire of the above embodiment to form the coil body 20 or the reinforcing member of the catheter, the resilience after bending the coil body 20 or the reinforcing member can be improved. Also, for medical members composed of coils or hollow bodies manufactured using the wire, when performing rotational operations in complexly intertwined blood vessels, excellent rotational followability can be exhibited as described above.

Explanation of Reference Numerals

[0051] 1 Guide wire 10 Core shaft

Claims

1. A guidewire including a medical wire that is a core shaft, The medical wire is cut to a length of 50 mm, and each end of the medical wire is bent so as to approach each other, a strain of 2% is applied, and the medical wire is held in this state for 10 seconds, so that the recovery rate after the strain is applied is 96% or more, the wire diameter is 0.42 mm or less, and austenitic stainless steel conforming to ASTM F2581 is used. The austenitic stainless steel has a tensile strength of 2800 N / mm ２ More than 3400N / mm ２ is less than When the medical wire cut to 100 mm is bent 180°, no breakage occurs at the bent portion of the guidewire. Distortion amount (%) = (R / (L-R)) x 100 (R is the diameter of the wire, L is the distance between both ends when bent so that they approach each other), and recovery rate (%) = (1-θ / 180) x 100 (θ is the angle at which two tangents drawn from both ends of the bent wire intersect).

2. A catheter having a cylindrical braid or coil body using medical wire as a reinforcing body, The medical wire is cut to a length of 50 mm, and each end of the medical wire is bent so as to approach each other, a strain of 2% is applied, and the medical wire is held in this state for 10 seconds, so that the recovery rate after the strain is applied is 96% or more, the wire diameter is 0.42 mm or less, and austenitic stainless steel conforming to ASTM F2581 is used. The austenitic stainless steel has a tensile strength of 2800 N / mm ２ More than 3400N / mm ２ is less than When the medical wire cut to 100 mm is bent 180°, no breakage occurs in the bent portion of the guidewire. Distortion amount (%) = (R / (L-R)) x 100 (R is the diameter of the wire, L is the distance between both ends when bent so that they approach each other), and recovery rate (%) = (1-θ / 180) x 100 (θ is the angle at which two tangents drawn from both ends of the bent wire intersect).

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