Medical device

Abstract

To provide a guide wire that has enhanced rotation followability while keeping flexibility of a coil tip.SOLUTION: A guide wire 10 includes a core shaft 1 and at least one coil body disposed so as to surround the tip side of the core shaft 1. The at least one coil body includes a first coil part 3 and a second coil part 4 disposed closer to a base end part in an axial direction than the first coil part 3. In the second coil part 4, a coating layer 42 formed of a heat-shrinkable tube is formed along the outer peripheral surface. In the first coil part 3, a coating layer formed of a heat-shrinkable tube is not formed.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, guidewires have been used when inserting medical devices such as catheters into tubular organs and internal body tissues, such as blood vessels and the digestive tract, for treatment or examination. Generally, guidewires have a structure in which a coil is attached to the tip of a core wire and the tip is flexible, but at the same time, guidewires are also required to have sufficient torque transmission capability to rotate the tip as intended by the operator by manipulating the proximal portion (base end portion).

[0003] Incidentally, among guidewires, there is a guidewire with a sensor that is attached to a cylindrical casing provided at the tip and that determines the properties of a thrombus by introducing a blood flow or the like into the sensor and measuring the impedance of the blood. In such guidewires, a lead wire extending from the sensor is integrated along the core wire, but even in guidewires including such lead wires, both flexibility and torque transmission are required.

[0004] In order to improve torque transmission, for example, Patent Document 1 discloses a guidewire in which the inside of a coil provided at the tip portion is filled with resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-214054 A Summary of the Invention [Problem to be solved by the invention]

[0006] When the coil is filled with resin as in Patent Document 1, the torque transmitted by the coil itself is weakened due to the loose winding of the coil, and the torque transmission of the guidewire depends on the torque transmission ability of the resin. However, since the torque transmission ability of resin is lower than that of metal, there is a problem that the torque transmission is not improved enough to improve the operability of the guidewire even if the coil is filled with resin. In addition, there is a risk that the flexibility of the tip of the guidewire will be lost due to the coil being filled with resin.

[0007] The present invention has been made in consideration of the above-mentioned points, and has an object to provide a guidewire that has improved rotational tracking ability while maintaining the flexibility of the coil tip. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a guidewire (Invention 1), comprising a core shaft and at least one coil body arranged to surround the tip side of the core shaft, the at least one coil body including a first coil section and a second coil section arranged on the base end side in the axial direction relative to the first coil section, the second coil section having a coating layer made of a heat-shrinkable tube formed along its outer peripheral surface, and the first coil section not having a coating layer made of a heat-shrinkable tube formed thereon.

[0009] According to this invention (Invention 1), by forming a coating layer only on the outer circumferential surface of the base end side of the coil body arranged on the tip side of the core shaft and forming the coating layer with a heat-shrinkable tube, the coil body and the coating layer are in contact with each other without being bonded, thereby making it possible to improve rotational followability while maintaining the flexibility of the tip of the coil provided at the tip of the guidewire. Note that the first coil portion and the second coil portion in the present invention may each be separate coil bodies, or a single coil body may have both.

[0010] In the above invention (Invention 1), it is preferable that the second coil portion has a hydrophilic coating layer formed on the outside of the coating layer (Invention 2).

[0011] In the above inventions (Inventions 1 and 2), a sensor unit may be disposed between the first coil portion and the second coil portion (Invention 3).

[0012] In the above invention (Invention 3), a connection cable that electrically connects the sensor unit to an external device may be disposed inside the at least one coil body (Invention 4). Effect of the Invention

[0013] According to the present invention, it is possible to provide a guidewire that has improved rotational tracking ability while maintaining the flexibility of the coil tip. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram showing the structure of a guidewire according to a first embodiment of the present invention. [Diagram 2] FIG. 6 is an explanatory view showing the structure of a guidewire according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment described below, and the described embodiment is merely an example for explaining the technical features of the present invention. In addition, the shapes and dimensions shown in each drawing are shown only to facilitate understanding of the contents of the present invention, and do not accurately reflect the actual shapes and dimensions.

[0016] First Embodiment FIG. 1 is an explanatory diagram showing the structure of a guidewire 10 according to a first embodiment, and is a partial cross-sectional view partially showing a transverse section of the guidewire 10 taken along its axial direction.

[0017] In this specification, the term "distal side" refers to a direction along the axial direction of the guidewire 10, and a direction in which the guidewire 10 advances toward a treatment or examination site. The term "base end side" refers to a direction along the axial direction of the guidewire 10, and a direction opposite to the distal side. The term "distal" refers to an end on the distal side of any member or site, and the term "base end" refers to an end on the base end of any member or site. The term "distal portion" refers to a portion of any member or site that includes the distal end and extends from the distal end toward the base end to the middle of the member, and the term "base end portion" refers to a portion of any member or site that includes the base end and extends from the base end toward the distal end to the middle of the member, etc. In addition, in FIG. 1, the right side of the figure is the "distal side" that is inserted into the body, and the left side of the figure is the "base side" that is operated by a technician such as a doctor.

[0018] As shown in FIG. 1, the guidewire 10 includes a long core shaft 1, a distal tip 2 attached to the distal end of the core shaft 1, a first coil body 3 and a second coil body 4 arranged so as to surround the distal end of the core shaft 1 on the proximal end side of the distal tip 2, a sensor unit 5 arranged between the first coil body 3 and the second coil body 4, and a lead wire (connection cable) 51 that electrically connects the sensor unit 5 to an external device (not shown). The second coil body 4 is arranged on the proximal end side of the axial direction of the guidewire 10 relative to the first coil body 3. The first coil body 3 is an example of the "first coil section" of the present invention, and the second coil body 4 is an example of the "second coil section" of the present invention. That is, in this embodiment, the "at least one coil body" of the present invention includes two coil bodies, the first coil body 3 and the second coil body 4, and the "first coil section" of the present invention is the first coil body 3, and the "second coil section" is the second coil body 4, which are separate coil bodies.

[0019] The guidewire 10 is inserted into a blood vessel for treatment or examination, and a resistance sensor (not shown) for measuring the impedance of blood in the vessel is built into the sensor unit 5. Note that the guidewire to which the present invention is applied is not limited to this, and the present invention can also be applied to a guidewire that is inserted and used in a body lumen other than a blood vessel, such as the digestive tract.

[0020] An axis passing through the center of the guidewire 10 is represented by axis C in FIG. 1, and axis C coincides with the axes passing through the centers of the core shaft 1, first coil body 3, and second coil body 4.

[0021] The core shaft 1 is an elongated member having a circular cross section extending along the axis C, and has a tapered shape in which the diameter is gradually reduced from the base end to the tip. The core shaft 1 has a first shaft portion 11, a second shaft portion 12, a third shaft portion 13, and a fourth shaft portion 14 in this order from the base end to the tip, and each is made of a metal material such as a stainless steel alloy, a nickel-titanium alloy, a nickel-chromium alloy, a cobalt-chromium alloy, or tungsten. The first shaft portion 11, the second shaft portion 12, the third shaft portion 13, and the fourth shaft portion 14 may be made of different materials or the same material. In addition, each of the first shaft portion 11, the second shaft portion 12, the third shaft portion 13, and the fourth shaft portion 14 may be made of a composite material in which a plurality of different materials are combined.

[0022] The first shaft portion 11 is disposed at the most proximal end of the core shaft 1 and extends coaxially with the axis C of the guidewire 10, with its tip welded to the proximal end of the second shaft portion 12. The first shaft portion 11 has a generally cylindrical shape with a generally constant outer diameter from the proximal end to the tip, and the outer diameter of the first shaft portion 11 is, for example, 0.25 mm over the entire length of the first shaft portion 11.

[0023] The second shaft portion 12 is disposed on the distal end side of the first shaft portion 11 and extends coaxially with the axis C of the guidewire 10, with its distal end welded to the proximal end of the third shaft portion 13. The second shaft portion 12 has a tapered shape (approximately a truncated cone shape) that gradually decreases in diameter from the proximal end to the distal end, and the outer diameter of the second shaft portion 12 is, for example, 0.25 mm at the proximal end and 0.16 mm at the distal end.

[0024] The third shaft portion 13 is disposed on the distal end side of the second shaft 12 and extends coaxially with the axis C of the guidewire 10, with its distal end welded to the proximal end of the fourth shaft portion 14. The third shaft portion 13 has a tapered shape (approximately a truncated cone shape) that gradually decreases in diameter from the proximal end toward the distal end, and the outer diameter of the third shaft portion 13 is, for example, 0.16 mm at the proximal end and 0.11 mm at the distal end.

[0025] The fourth shaft portion 14 is disposed at the most distal end of the core shaft 1 and extends coaxially with the axis C of the guidewire 10, with its distal end fixed to the distal tip 2. The fourth shaft portion 14 has a generally cylindrical shape with a generally constant outer diameter from the base end to the distal end.

[0026] The outer diameter, length in the direction of axis C, and cross-sectional shape of first shaft portion 11, second shaft portion 12, third shaft portion 13, and fourth shaft portion 14 can be determined arbitrarily.

[0027] The distal tip 2 integrally holds the distal end of the core shaft 10 and the distal end of the first coil body 3, and is disposed at the very distal end of the guidewire 10. The distal tip 2 is formed from any bonding agent, for example, metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, or adhesive such as epoxy adhesive.

[0028] The first coil body 3 is a coil body with a two-layer structure in which an outer coil 32 is disposed outside an inner coil 31, and is disposed outside the fourth shaft portion 14 of the core shaft 1. The tip of the first coil body 3 is soldered to the tip chip 2, and the base end of the first coil body 3 is bonded with an adhesive to a sensor unit 5 described later. No covering layer made of a heat-shrinkable tube is formed on the outer circumferential surface of the first coil body 3. In this embodiment, the outer diameter of the first coil body 3 is about 0.35 mm, and the length in the direction of the axis C is about 30 mm.

[0029] The inner coil 31 is a substantially cylindrical coil formed by spirally winding a wire made of a metal material such as a stainless steel alloy, a nickel-titanium alloy, a nickel-chromium alloy, a cobalt-chromium alloy, tungsten, or platinum, and may be a single-strand coil formed by winding one wire into a single strand, a multi-strand coil formed by winding multiple wires into multiple strands, a single-strand stranded coil formed by winding a strand obtained by twisting multiple wires into a single strand, or a multi-strand stranded coil formed by using multiple strands obtained by twisting multiple wires into multiple strands. In this embodiment, the inner coil 31 is a multi-strand coil formed by winding six stainless steel alloy wires into multiple strands.

[0030] The outer coil 32 is a substantially cylindrical coil formed by spirally winding a wire made of a metal material such as a stainless steel alloy, a nickel-titanium alloy, a nickel-chromium alloy, a cobalt-chromium alloy, tungsten, or platinum, and may be a single-strand coil formed by winding a single wire, a multi-strand coil formed by winding multiple wires, a single-strand stranded coil formed by winding a single strand of a strand made of multiple wires, or a multi-strand stranded coil formed by using multiple strands made of multiple wires and winding each strand multiple times. In this embodiment, the outer coil 32 is a single-strand coil formed by winding a single platinum wire.

[0031] The second coil body 4 has a structure in which a coating layer 42 is disposed on the outside of the coil 41, and is disposed on the outside of the third shaft portion 13 of the core shaft 1. The tip of the second coil body 4 is bonded to the sensor unit 5 described later with an adhesive, and the base end of the second coil body 4 is bonded to the core shaft 1 and the outer tube 6 described later with an adhesive. The coating layer 42 is formed by covering the outer circumferential surface of the coil 41 with a heat-shrinkable tube and shrinking the heat-shrinkable tube by applying heat. That is, the second coil body 4 has a coating layer 42 made of a heat-shrinkable tube formed along the outer circumferential surface of the coil 41. The coating layer 42 is not bonded to the coil 41 except for both ends, and is in contact with the outer circumferential surface of the coil 41 so as to tighten the coil 41 from the outside. In this embodiment, the outer diameter of the second coil body 4 is about 0.34 mm, and the length in the direction of the axis C is about 270 mm.

[0032] The coil 41 is a generally cylindrical coil formed by spirally winding a wire made of a metal material such as a stainless steel alloy, a nickel-titanium alloy, a nickel-chromium alloy, a cobalt-chromium alloy, tungsten, or platinum, and may be a single-strand coil formed by winding a single wire, a multi-strand coil formed by winding multiple wires, a single-strand stranded coil formed by winding a single strand of a stranded wire made by twisting multiple wires, or a multi-strand stranded coil formed by using multiple strands made by twisting multiple wires and winding each strand multiple times. In this embodiment, the coil 41 is a multi-strand coil formed by winding 16 stainless steel alloy wires in multiple strands.

[0033] The heat-shrinkable tube that forms the coating layer 42 is not particularly limited as long as it is a resin tube that has the property of shrinking when heat is applied, but it is preferable that the resin tube be thin but has excellent strength, and for example, a tube formed by cutting a PET (polyethylene terephthalate) film into a cylindrical shape can be used.

[0034] It is preferable to use a thin-walled tube with a film thickness of 10 μm or less, and more preferably a film thickness of 5 μm or less, as the heat-shrinkable tube for forming covering layer 42. If the film thickness exceeds 10 μm, the rigidity of second coil body 4 on which covering layer 42 is disposed becomes too high, which may impede blood vessel tracking ability.

[0035] The coating layer 42 does not necessarily have to be formed over the entire length of the second coil body 4; for example, there may be portions at the base end or tip end of the second coil body 4 where the coating layer 42 is not formed.

[0036] The sensor unit 5 is configured by, for example, attaching a resistance sensor to the outer peripheral surface of a substantially cylindrical housing, and is disposed between the first coil body 3 and the second coil body 4. The sensor unit 5 is fixed to the core shaft 1 so that the core shaft 1 penetrates the housing along the central axis of the housing. Note that the sensor unit 5 of this embodiment measures the impedance of blood in a blood vessel, but is not limited thereto, and a sensor unit that obtains other information may be used.

[0037] The tip of the sensor unit 5 and the base end of the first coil body 3, and the base end of the sensor unit 5 and the tip of the second coil body 4 are each bonded with an adhesive. Since applying heat to the periphery of the sensor unit 5 may cause damage or failure of the resistance sensor, the sensor unit 5 and the first coil body 3 and the second coil body 4 are fixed by bonding with an adhesive rather than by soldering.

[0038] The lead wire 51 is a connection cable that electrically connects the sensor unit 5 to an external device (not shown), and is arranged so that it is introduced from the sensor unit 5 along the core shaft 1 into the inside of the coil 41 of the second coil body 4, passes from the inside of the coil 41 through the inside of the first outer tube 6a and the second outer tube 6b, and is pulled out from the base end of the guide wire 10 to the outside.

[0039] An outer tube 6 is disposed on the base end side of the second coil body 4 so as to cover the first shaft portion 11 and the second shaft portion 12 of the core shaft 1. The base end of the second coil body 4 is bonded to the tip of the first outer tube 6a using an adhesive, and the base end of the first outer tube 6a is inserted into the tip of the second outer tube 6b and bonded thereto using an adhesive. A connector (not shown) operated by an operator such as a doctor is attached to the base end of the second outer tube 6b by known fastening means such as brazing or bonding with an adhesive.

[0040] The outer tube 6 (first outer tube 6a and second outer tube 6b) is preferably a resin tube with a low friction coefficient and excellent slidability, and for example, a PI (polyimide) tube can be used. In this embodiment, the first outer tube 6a has an outer diameter of about 0.30 mm and a length in the axial direction C of about 20 mm, and the second outer tube 6b has an outer diameter of about 0.35 mm and a length in the axial direction C of about 1600 mm. The outer tube 6 may be made of a single resin material, or may be divided into a plurality of regions and formed using a plurality of resin materials each having different properties.

[0041] The guidewire 10 is coated with a hydrophilic coating agent to facilitate smooth movement within a blood vessel. Examples of the hydrophilic coating agent that can be used include coating agents using hydrophilic materials such as cellulose-based polymers, polyethylene oxide-based polymers, maleic anhydride-based polymers (e.g., maleic anhydride copolymers such as methyl vinyl ether-maleic anhydride copolymers), acrylamide-based polymers (e.g., polyacrylamide, polyglycidyl methacrylate-dimethylacrylamide block copolymers), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, and hyaluronate.

[0042] In this embodiment, a first hydrophilic coating layer 7 is formed on the outer peripheral surface of the guidewire 10 from the distal tip 2 through the first coil body 3 and sensor unit 5 to the distal end of the second coil body 4 (at a position approximately 5 mm from the proximal end of the sensor unit 5), and a second hydrophilic coating layer 8 is formed on the outer peripheral surface of the second coil body 4 on the proximal side of the portion where the first hydrophilic coating layer 7 is formed, to the outer tube 6. That is, in the first coil body 3, the first hydrophilic coating layer 7 is formed directly on the outer peripheral surface of the outer coil 32, and in the second coil body 4, the first hydrophilic coating layer 7 or the second hydrophilic coating layer 8 is formed on the outside of the coating layer 42 formed along the outer peripheral surface of the coil 41.

[0043] The first hydrophilic coating layer 7 is formed to have a thickness smaller than that of the second hydrophilic coating layer 8. In this embodiment, the second hydrophilic coating layer 8 has a thickness of about 2-3μ, while the first hydrophilic coating layer 7 has a thickness of 1μ or less. This ensures flexibility of the distal end of the guidewire 10, that is, the portion from the distal tip 2 to the first coil body 3. Note that in FIG. 1, it is shown as if there are gaps between the first hydrophilic coating layer 7 and the first coil body 3, and between the second hydrophilic coating layer 8 and the first outer tube 6a, but in reality, such gaps are not formed, and the outer circumferential surfaces of the first coil body 3, the sensor unit 5, the second coil body 4, the first outer tube 6a, and the second outer tube 6b are coated with the first hydrophilic coating layer 7 or the second hydrophilic coating layer 8. In addition, the second hydrophilic coating layer 8 does not have to be formed over the entire length of the second outer tube 6b.

[0044] In the guidewire 10 as described above, among the coil bodies arranged on the distal end side of the core shaft 1, the coating layer 42 is formed only on the outer circumferential surface of the coil 41 of the second coil body 4, and the coating layer 42 is formed of a heat-shrinkable tube, so that the second coil body 4 and the coating layer 42 are in a state of being in contact with each other without being bonded, thereby improving the rotational followability while maintaining the flexibility of the coil tip provided at the distal end of the guidewire 10. This is because the coating layer 42 covers the second coil body 4 in a tightening manner, so that a compressive pressure is applied in the radial and longitudinal directions of the coil 41, and the adhesion between the wires constituting the coil 41 increases. The increased adhesion between the wires increases the torque transmission and leads to improved rotational followability. On the other hand, since the coating layer made of a heat-shrinkable tube is not formed along the outer circumferential surface of the first coil body 3, the movement is not restricted, and the flexibility of the coil tip is maintained. Generally, the torque transmission performance of a coil body differs depending on the direction of rotation, but by covering the second coil body 4 with a covering layer 42 made of a heat-shrinkable tube, this difference can be reduced.

[0045] Furthermore, when coating with a hydrophilic coating agent, the adhesion of the coating agent is improved when the coating is applied onto a covering layer (heat-shrinkable tubing) rather than directly onto the outer surface of the coil, and this is expected to further improve the sliding characteristics of the guidewire.

[0046] <Second embodiment> 2 is an explanatory diagram showing the structure of a guidewire 10A according to the second embodiment, and is a partial cross-sectional view partially showing a cross section along the axial direction of the guidewire 10A. In the following, differences from the first embodiment will be mainly described, and descriptions of structures similar to those of the first embodiment will be omitted.

[0047] 2, the guidewire 10A includes a long core shaft 1, a distal tip 2 attached to the distal end of the core shaft 1, and a coil body 9 arranged so as to surround the distal end side of the core shaft 1 on the proximal end side of the distal tip 2. The guidewire 10A differs from the guidewire 10 of the first embodiment in that it includes only one coil body 9 at the distal end of the core shaft 1, that it does not include a sensor unit or lead wires, that it is not coated with a hydrophilic coating agent, and that the core shaft 1 on the proximal end side is not covered with an outer tube.

[0048] The coil body 9 has a first coil portion 91 and a second coil portion 92 arranged closer to the base end in the axial direction than the first coil portion 91. The first coil portion 91 corresponds to the first coil body 3 in the first embodiment, and is a portion of the coil 90 of the coil body 9 where a coating layer made of a heat-shrinkable tube is not formed on the outer circumferential surface of the coil 90. The second coil portion 92 corresponds to the second coil body 4 in the first embodiment, and is a portion of the coil 90 of the coil body 9 where a coating layer 921 made of a heat-shrinkable tube is formed on the outer circumferential surface of the coil 90. That is, in this embodiment, the "at least one coil body" of the present invention is realized by a single coil body called the coil body 9, and the first coil portion 91 and the second coil portion 92 of the coil body 9 correspond to the "first coil portion" and the "second coil portion" of the present invention, respectively.

[0049] The coil 90 is a substantially cylindrical coil formed by spirally winding a wire made of a metal material such as a stainless steel alloy, a nickel-titanium alloy, a nickel-chromium alloy, a cobalt-chromium alloy, tungsten, or platinum, and may be a single-strand coil formed by winding a single wire, a multi-strand coil formed by winding multiple wires, a single-strand stranded coil formed by winding a single strand of a stranded wire made by twisting multiple wires, or a multi-strand stranded coil formed by using multiple strands of stranded wires made by twisting multiple wires and winding each strand multiple times. In this embodiment, the coil 90 is a multi-strand coil formed by winding 16 stainless steel alloy wires in multiple strands, but the tip side of the coil 90, i.e., the portion corresponding to the first coil portion 91, is loosely wound, and the base end side of the coil 90, i.e., the portion corresponding to the second coil portion 92, is densely wound. The outer surface of the core shaft 1 located on the proximal side of the coil 90 is provided with a lubricating coating (not shown), such as a PTFE coating or a hydrophilic coating, like a typical guidewire.

[0050] The guidewire 10A of this embodiment does not have a sensor unit, but may have a sensor unit similar to that of the guidewire 10 of the above embodiment, for example, on the base end side of the second coil portion 92. In that case, like the guidewire 10, the lead wire may be arranged along the core shaft 1, or the base end side of the core shaft 1 may be covered by an outer tube together with the lead wire.

[0051] Although the guidewire according to the present invention has been described above with reference to the drawings, the present invention is not limited to the above-described embodiment and various modifications can be made. [Explanation of symbols]

[0052] 10 Guidewire 1 Core shaft 2 Tip 3 First coil body 31 Inner coil 32 Outer coil 4 Second coil body 41 Coil 42 Covering layer 5 Sensor unit 51 Lead Wire 6 Outer tube 7 First hydrophilic film layer 8 Second hydrophilic film layer 10A Guidewire 9 Coil body 91 First coil section 92 Second coil section

Claims

1. A medical device having a first coil portion and a second coil portion disposed on the proximal side in the axial direction with respect to the first coil portion and being separate from the first coil portion. A coating layer made of a heat-shrinkable tube is formed along the outer peripheral surface of the second coil portion. The first coil portion has no coating layer made of a heat-shrinkable tube.

2. The medical device according to Claim 1, wherein a sensor unit is disposed between the first coil portion and the second coil portion.

3. The medical device according to Claim 2, wherein a connection cable for electrically connecting the sensor unit and an external device is disposed inside the second coil portion.

4. The medical device according to any one of Claims 1 to 3, wherein the second coil portion has a hydrophilic coating layer formed outside the coating layer.

5. The medical device according to any one of Claims 1 to 3, wherein the proximal end of the first coil portion is located on the distal side with respect to the distal end of the second coil portion.

6. The medical device according to any one of Claims 1 to 3, comprising a core shaft disposed inside the first coil portion and the second coil portion.

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