Clad wire rod and medical device

Abstract

To provide a clad wire rod in which the flexibility of a core part is improved.SOLUTION: The clad wire rod 1, 1A includes a core part 2, 21A including a plurality of element wires 21, 2A formed of a first material, and an outer layer part 3, 2A formed of a second material and disposed on the outer periphery of the core part 2, 3A. In the clad wire rod 1 and the 1A, the core portion 2 and the 2A may be formed of a twisted wire body obtained by twisting the plurality of element wires 21 and the 21A. In the clad wire rod 1 and the 1A, the first metals may be X-ray impermeable metals. In the clad wire rod 1, 1A, the second material may have at least one of shape memory properties and superelasticity higher than that of the first material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a clad wire used as a material for a medical device and a medical device using the same. [Background technology]

[0002] Conventionally, medical devices such as stents and guidewires made of metal wires have been used to treat stenoses and occlusions in tubular organs of the human body, such as blood vessels and digestive organs. The metal wires used in such medical devices are required to be visible under X-ray fluoroscopy, as well as to have shape restoration and expandability. For example, Patent Document 1 discloses a stent formed of a clad material including a first portion (inner layer) made of a highly visible first composition such as platinum, and a second portion (outer layer) made of a second composition such as a nickel-titanium alloy having superelastic properties, in order to achieve both visibility and restoreability / expandability for the medical device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2006-515779 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional clad materials have the problem that if the core portion is made large enough in cross section to ensure visibility, the flexibility of the core portion is lost, impairing the restorability and expandability of the entire clad material.

[0005] The present disclosure has been made in view of the above circumstances, and aims to provide a clad wire rod having improved flexibility in the core portion. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, first, the present disclosure provides a clad wire having a core portion including a plurality of wires formed of a first metal, and an outer layer portion formed of a second metal and arranged on the outer periphery of the core portion (Disclosure 1).

[0007] According to this disclosure (Disclosure 1), by including multiple wires rather than a single wire in the core portion, the core portion can be made more flexible than a single-wire core portion with the same cross-sectional area, and therefore a clad wire with improved flexibility in the core portion can be provided.

[0008] In the above disclosure (Disclosure 1), the core portion may be formed from a stranded wire body in which a plurality of the wires are stranded together (Disclosure 2).

[0009] According to this disclosure (Disclosure 2), by forming the core portion from a stranded wire body in which a plurality of elemental wires are twisted together, the core portion can be configured from a plurality of elemental wires instead of a single wire.

[0010] In the above disclosures (Disclosures 1 and 2), the first metal may be a metal that is radiopaque (Disclosure 3).

[0011] According to this disclosure (Disclosure 3), when the clad wire is used in a medical device, visibility under X-ray fluoroscopy can be ensured.

[0012] In the above disclosures (Disclosures 1-3), the second metal may be a metal having at least one of shape memory property and superelasticity higher than that of the first metal (Disclosure 4).

[0013] According to this disclosure (Disclosure 4), even if a metal with low flexibility is used for the core portion, it is possible to ensure the shape restoration and expandability of the clad wire.

[0014] Secondly, the present disclosure provides a medical device formed by braiding the clad wires of any one of Disclosures 1 to 4 in a reticulated form (Disclosure 5).

[0015] Third, the present disclosure provides a medical device (Disclosure 6) comprising a core wire and a coil body arranged on the outer periphery of the distal end of the core wire, the coil body being formed by spirally winding any one of the clad wires of Disclosures 1-4. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is an explanatory diagram illustrating a structure of a clad wire according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is an explanatory diagram illustrating a modified example of a clad wire according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is an explanatory diagram showing a stent using the clad wire of the present disclosure. [Figure 4] 1 is an explanatory diagram showing a guide wire using a clad wire according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the embodiments described below, and the described embodiments are merely examples for explaining the technical features of the present disclosure. The shapes and dimensions shown in each drawing are shown merely to facilitate understanding of the contents of the present disclosure, and do not accurately reflect the actual shapes and dimensions.

[0018] As used herein, "distal side" refers to the direction along the axial direction of the clad wire and medical device (stent, guidewire, etc.) and the direction in which the clad wire and medical device advance toward the target site. "Proximal side" refers to the direction along the axial direction of the clad wire and medical device and the opposite direction to the distal side. "Distal" refers to the distal end of any component or part, and "proximal end" refers to the proximal end of any component or part.

[0019] <Clad wire> 1 is an explanatory diagram showing the structure of a clad wire 1 according to one embodiment of the present disclosure, illustrating a cross section of a long clad wire 1. The clad wire 1 according to this embodiment comprises a core 2 including a plurality of wires 21 made of a first metal, and an outer layer 3 made of a second metal and disposed on the outer periphery of the core 2.

[0020] The core portion 2 is formed from a stranded wire body made by twisting together a plurality of wires 21 (seven wires 21 in this embodiment) made of a first metal. Specifically, the stranded wire body made by twisting together a plurality of wires 21 is drawn (drawn using a die) until it reaches a desired diameter, and is formed into a shape that is close to a solid wire that is substantially circular in cross section, thereby forming the core portion 2. During the wiredrawing process, the cross-sectional shapes of the plurality of wires 21 that make up the core portion 2 are changed so that there are no gaps between adjacent wires 21.

[0021] The number of wires 21 constituting the stranded wire body for forming the core portion 2 may be plural, and for example, the stranded wire body can be formed by stranding together about 2 to 100 wires 21.

[0022] The first metal forming the wires 21 constituting the core portion 2 can be selected appropriately depending on the application of the clad wire 1, and examples thereof include gold, tantalum, palladium, platinum, alloys containing these, stainless steel, and nickel-titanium alloys. When a stent is formed from the clad wire 1, the first metal is preferably a metal that is opaque to radiography, and examples thereof include gold, platinum, tungsten, and alloys containing these. When a coil body to be placed at the tip of a guidewire is formed from the clad wire 1, the first metal is preferably a metal that is opaque to radiography, and examples thereof include platinum, tantalum, tungsten, and alloys containing these.

[0023] The outer layer portion 3 is made of a second metal and is arranged on the outer periphery of the core portion 2 so as to cover the core portion 2. Specifically, a tubular material made of the second metal is prepared, and the core portion 2 is inserted into the inner cavity of the tubular member, and wiredrawing is performed until the desired diameter is reached, thereby forming the outer layer portion 3 arranged tightly around the core portion 2.

[0024] The second metal forming the outer layer 3 can be selected appropriately depending on the application of the clad wire 1, and examples thereof include a nickel-titanium alloy, stainless steel, and a cobalt alloy. When a stent is formed from the clad wire 1, the second metal is preferably a metal that has at least one of higher shape memory property and higher superelasticity than the first metal, and examples thereof include a nickel-titanium alloy and an iron-manganese-silicon alloy. When a guidewire is formed from the clad wire 1, examples of the second metal include stainless steel. The second metal may be the same as or different from the first metal, and may be selected appropriately depending on the application.

[0025] The volume ratio of the core portion 2 and the outer layer portion 3 constituting the clad wire 1 can be appropriately determined depending on the application of the clad wire 1, and may be, for example, core portion:outer layer portion=10-90:90-10 (volume ratio), or core portion:outer layer portion=30-70:70-30 (volume ratio).

[0026] In the clad wire 1 of the present disclosure, the core region 2 is formed of multiple wires 21 rather than a single wire, thereby making the core region more flexible than a core region made of a single wire with the same cross-sectional area. This provides a clad wire 1 with improved flexibility of the core region 2. In particular, a clad wire 1 used to form a medical device such as a stent is required to be visible under X-ray fluoroscopy, as well as to have shape recovery and expandability. Therefore, by using a radiopaque first metal forming the core region 2, visibility under X-ray fluoroscopy can be ensured. Even if a radiopaque first metal with low flexibility is used for the core region 2, the shape recovery and expandability of the clad wire 1 can be ensured by using a second metal forming the outer layer 3 that has at least one of shape memory and superelasticity higher than the first metal.

[0027] The clad wire 1 can be manufactured, for example, through the following process. Here, the manufacturing process will be explained on the premise that a platinum-nickel alloy is selected as the first metal and a nickel-titanium alloy is selected as the second metal to manufacture the clad wire 1 that will be used as a stent material.

[0028] First step: A tubular material made of a nickel-titanium alloy is prepared, and an annealing treatment is performed by heating and holding the tubular material at a temperature that can remove the superelasticity of the tubular material, thereby removing the superelasticity of the tubular material.

[0029] Second step: Seven platinum-nickel alloy wires 21 are prepared and twisted together to form a single twisted wire. Pressure is applied to the outer periphery of the twisted wire to process it until it reaches the desired diameter, forming a core material with a shape similar to a single wire that is roughly circular in cross section.

[0030] Step 3: The core material obtained in Step 2 is inserted into the tubular material obtained in Step 1, and pressure is applied from the outside of the tubular material until the desired diameter is reached, thereby forming a clad wire. Annealing may be performed each time during the processing process, if necessary.

[0031] Step 4: The clad wire obtained in Step 3 is subjected to a heat treatment to impart superelasticity by heating and holding it at a temperature that can impart superelasticity to the nickel-titanium alloy tubular material, thereby forming the clad wire 1 that will be used as the material for the stent.

[0032] <Modification> A modified example of a clad wire 1 according to an embodiment of the present disclosure will be described. As shown in Fig. 2, the modified clad wire 1A includes a core 2A including a plurality of wires 21A formed of a first metal, and an outer layer 3A formed of a second metal different from the first metal and arranged on the outer periphery of the core 2A. Unlike the clad wire 1 described above, the plurality of wires 21A constituting the core 2A of the clad wire 1 have a substantially circular cross-sectional shape, and there are gaps between each wire 21A and the adjacent wire 21A and between each wire 21A and the outer layer 3A.

[0033] If the core of the clad wire is made up of multiple wires, it will be more flexible to bending than a core made of a single wire, regardless of whether there are gaps between the wires. Therefore, there may be no gaps between the multiple wires 21 as in the clad wire 1 described above, or there may be gaps between the multiple wires 21A as in the modified clad wire 1A.

[0034] <Medical devices using clad wire> The clad wire of the present disclosure can be used in a variety of medical devices. Figure 3 is an explanatory diagram showing a stent 4 using a clad wire 1. The stent 4 is a medical device formed by braiding a plurality of metal wires 41 in a mesh pattern, and the clad wire 1 described above can be used as this metal wire 41.

[0035] 4 is an explanatory diagram showing a guide wire 5 using the clad wire 1. The guide wire 5 includes a core wire 51 and a coil body 52 arranged on the outer periphery of the distal end of the core wire 51. A distal tip 53 is provided at the distal end of the core wire 51, and the distal end of the coil body 52 is fixed to the core wire 51 via the distal tip 53 and the proximal end of the coil body 52 via a fixing portion 54. The coil body 52 is formed by spirally winding the clad wire 1 described above.

[0036] The clad wire according to the present disclosure and a medical device using the same have been described above with reference to the drawings. The present disclosure is not limited to the above-described embodiments and various modifications are possible. For example, the core portion of the clad wire may be formed using multiple stranded wire bodies each formed by stranding multiple wires together. Specifically, the core portion may be formed by preparing seven stranded wire bodies each formed by stranding seven wires together and twisting these seven stranded wire bodies together. The diameters of the multiple wires forming the core portion may all be the same, or some may have different diameters. A medical device formed using the clad wire according to the present disclosure may be a lead wire for a pacemaker, a stent retriever, or an embolic coil.

Claims

1. a core portion (2, 2A) including a plurality of wires (21, 21A) formed of a first metal; The clad wire (1, 1A) comprises an outer layer portion (3, 3A) formed of a second metal and arranged on the outer periphery of the core portion (2, 2A).

2. The clad wire (1, 1A) according to claim 1, wherein the core portion (2, 2A) is formed from a stranded wire body in which a plurality of the wires (21, 21A) are stranded together.

3. The clad wire (1, 1A) according to claim 1 or 2, wherein the first metal is a metal that is radiopaque.

4. The clad wire (1, 1A) according to any one of claims 1 to 3, wherein the second metal is a metal having at least one of shape memory property and superelasticity higher than that of the first metal.

5. A medical device (4) formed by braiding the clad wire (1, 1A) according to any one of claims 1 to 4 in a mesh form.

6. a core wire (51); a coil body (52) arranged on the outer periphery of the distal end side of the core wire (51), A medical device (5), wherein the coil body (52) is formed by spirally winding the clad wire (1, 1A) according to any one of claims 1 to 4.

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