Guide wire

Abstract

This guide wire comprises a core shaft which has a tip and a base end that is on the opposite side from the tip, and a coil body which is disposed so as to surround a tip part of the core shaft. The coil body is a clad material obtained by bonding together a metal core wire and a coating layer which is made of metal and which covers the outer circumference of the core wire. A tip part of the coil body is an exposed part in which the core wire is exposed from the coating layer.

Description

Guidewire

[0001] The technology disclosed herein relates to a guidewire.

[0002] Methods using catheters are widely used to treat or examine lesions (stenoses or occlusions) in biological lumens such as blood vessels. A guidewire is generally used to guide the catheter to the lesion in the blood vessel or the like. The guidewire includes a long core shaft and a coil body disposed around the core shaft. The coil body may be a clad material including a metal core (core wire) and a metal clad (coating layer) that covers the outer periphery of the core wire (see Patent Document 1).

[0003] Special Publication No. 2002-518109

[0004] This type of guidewire needs to be flexible enough not to damage the inner wall of the biological lumen, and excellent flexibility is particularly required at the tip. In addition, the force applied to the proximal end by a physician or other operator to push the guidewire toward the lesion in the biological lumen must be smoothly transmitted to the tip.

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

[0006] The guide wire disclosed in this specification comprises a core shaft having a tip and a base end opposite the tip, and a coil body arranged to surround the tip of the core shaft, the coil body being a clad material in which a metal core wire and a metal coating layer covering the outer periphery of the core wire are bonded together, and the core wire is exposed from the coating layer at the tip of the coil body.

[0007] 1 is a cross-sectional view schematically showing the configuration of a guide wire according to a first embodiment; FIG. 2 is a diagram schematically showing a cross section of a wire constituting a coil body according to the first embodiment; FIG. 3 is a side view schematically showing a method for manufacturing the coil body according to the first embodiment; and FIG. 4 is a cross-sectional view schematically showing the configuration of a guide wire according to a second embodiment.

[0008] A. First Embodiment: A-1. Configuration of Guidewire 10: FIG. 1 is an explanatory diagram schematically illustrating the configuration of the guidewire 10 of the first embodiment. FIG. 1 shows a longitudinal cross section (YZ cross section) of the guidewire 10. In FIG. 1, the positive Z-axis direction side is the tip end side (distal side) that is inserted into the body, and the negative Z-axis direction side is the base end side (proximal side) that is manipulated by an operator such as a physician. These points also apply to FIG. 2 and subsequent figures. FIG. 1 shows the guidewire 10 as a whole in a linear shape that is approximately parallel to the Z-axis direction. The guidewire 10 has flexibility to the extent that it can be bent. Hereinafter, with respect to the guidewire 10 and each of its constituent members, the tip end and its vicinity will be referred to as the "tip end portion," and the base end and its vicinity will be referred to as the "base end portion."

[0009] The guidewire 10 of this embodiment is a medical device that is inserted into a body lumen, such as a blood vessel, to guide a catheter (not shown) to a lesion (a narrowed or blocked portion) in the body lumen.

[0010] As shown in FIG. 1 , the guidewire 10 includes a core shaft 100 , a coil body 200 , a distal joint portion 300 , and a proximal joint portion 400 .

[0011] (Core Shaft 100) The core shaft 100 is a bendable, long, round bar-shaped member having a distal end 101 and a proximal end 102. The core shaft 100 includes a proximal portion 130, a thin-diameter portion 110 having an outer diameter smaller than that of the proximal portion 130, and a tapered portion 120 connecting the proximal portion 130 and the thin-diameter portion 110. The thin-diameter portion 110, the tapered portion 120, and the proximal portion 130 are arranged in this order from the distal end 101. The tapered portion 120 has an outer diameter that gradually decreases from the proximal portion 130 toward the thin-diameter portion 110. The proximal end of the core shaft 100 is a gripping portion 100G that is gripped by a surgeon such as a doctor. The outer diameter of the thin-diameter portion 110 is, for example, approximately 0.03-0.085 mm, and the outer diameter of the proximal portion 130 is, for example, approximately 0.2-0.9 mm.

[0012] The core shaft 100 is made of a known material, for example, a metal material, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), a superelastic alloy such as a Ni-Ti alloy, a piano wire, a nickel-chromium alloy, a cobalt alloy, tungsten, etc. The core shaft 100 may be made entirely of the same material, or different portions may be made of different materials.

[0013] (Coil body 200) The coil body 200 is disposed so as to surround the tip portion of the core shaft 100 (specifically, a part of the base portion 130, the tapered portion 120, and the small diameter portion 110). The total length of the coil body 200 is, for example, about 10-500 mm, and the outer diameter of the coil body 200 is, for example, about 0.2-0.9 mm. The outer diameter and inner diameter of the coil body 200 of this embodiment are constant over the entire length.

[0014] The coil body 200 is a coil formed by helically winding a single wire 200W. As shown in Fig. 1, the coil body 200 is a closely wound coil in which adjacent portions of the wire 200W are in contact with each other when no external force is applied. In other words, the coil body 200 is wound so that there is no gap between one turn of the wire 200W and another turn adjacent to it.

[0015] 1 and 2, the wire 200W constituting the coil body 200 includes a metal core wire 210 and a metal coating layer 220 that covers the outer periphery of the core wire 210. The wire 200W is a clad material in which different metals are metallurgically bonded. More specifically, the wire 200W is a clad wire in which the coating layer 220 is metallurgically bonded to the core wire 210 by rolling, and the material of the coating layer 220 is different from the metal material used for the core wire 210.

[0016] 1, the tip of the coil body 200 is an exposed portion 201 where the core wire 210 is exposed from the coating layer 220, and the remaining portion is a coated portion 202 where the core wire 210 is covered by the coating layer 220. The length of the exposed portion 201 is, for example, 3 to 5 mm.

[0017] 2, the interface between the core wire 210 and the coating layer 220 has unevenness over the entire periphery. With this configuration, the core wire 210 and the coating layer 220 are firmly joined together by an anchor effect.

[0018] Preferred examples of the material of the core wire 210 include platinum, gold, silver, tantalum, and copper. From the viewpoint of ensuring visibility of the coil body 200 under radioscopic images, a radiopaque material can be preferably used as the material of the core wire 210.

[0019] Preferred examples of the material for the coating layer 220 include stainless steel (SUS302, SUS304, SUS316, etc.), piano wire, tungsten, cobalt alloy, and titanium alloy.

[0020] The material of the covering layer 220 may be a material having a Young's modulus greater than that of the material of the core wire 210. With this configuration, a higher elastic force can be imparted to the base end of the coil body 200 on which the covering layer 220 is disposed, compared to when the Young's modulus of the material of the covering layer 220 is equal to or lower than that of the material of the core wire 210.

[0021] (Tip Joint Portion 300) The tip joint portion 300 is a member that connects the tip 101 of the core shaft 100 and the tip of the coil body 200. The tip 101 of the core shaft 100 and the tip of the coil body 200 are fixedly embedded inside the tip joint portion 300. The tip surface of the tip joint portion 300 is a smooth surface (e.g., a substantially hemispherical surface). Examples of materials for the tip joint portion 300 include metal solders such as silver solder, gold solder, zinc, Sn—Ag alloy, and Au—Sn alloy, and adhesives such as epoxy adhesives. By disposing the tip joint portion 300 at the tip 101 of the core shaft 100, the core shaft 100 is prevented from contacting a blood vessel wall or the like, and damage to the core shaft 100 is suppressed.

[0022] (Proximal end joint portion 400) The proximal end joint portion 400 is a member that joins the proximal end of the coil body 200 to the core shaft 100. The proximal end of the coil body 200 is joined to the coating layer 220 by the proximal end joint portion 400. Examples of materials for the proximal end joint portion 400 include the same materials as those for the distal end joint portion 300 described above. When the proximal end joint portion 400 is solder, by selecting stainless steel, which has a small potential difference with the solder, as the material for the coating layer 220, corrosion of the joint portion between the coil body 200 and the proximal end joint portion 400 is suppressed even when the guidewire 10 is exposed to an electrolyte (physiological saline).

[0023] A-2. Method for Manufacturing Coil Body 200: An example of a method for manufacturing the coil body 200 will be described below.

[0024] First, a metal core material 510, which will be the material for the core wire 210, is inserted into a metal pipe material 530, which will be the material for the coating layer 220. Next, the core material 510 and the pipe material 530 are subjected to a drawing process (wire drawing process) to obtain a composite material 500. The composite material 500 is a clad material in which the core material 510 and the pipe material 530 are joined by rolling. More specifically, as shown in FIG. 3 , the pipe material 530 with the core material 510 inserted therein is passed through a die hole 561 of a die 560 and drawn, thereby forming a thin wire-like composite material 500 having an outer diameter smaller than that of the original pipe material 530. During the compression process of the core material 510 and the pipe material 530, which have different hardnesses, unevenness is formed at the interface between the core material 510 and the pipe material 530, resulting in a complex, intricate shape, which firmly joins the two. A plurality of dies having different die hole diameters may be prepared, and the core material 510 and the pipe material 530 may be passed through the dies having the die hole diameters in order from the largest to the smallest, thereby gradually reducing the outer diameter of the composite material 500 (block wire drawing process). A tension (back tension) may be applied to the core material 510 and the pipe material 530 in the direction opposite to the drawing direction.

[0025] Next, the obtained composite material 500 is cut to a required length, and a portion of the outer layer is removed to form the wire 200W in which a portion of the core wire 210 is exposed from the coating layer 220. The process of removing the portion of the outer layer may be performed by a physical process such as cutting using a grinder, or by a chemical process such as electrolytic polishing.

[0026] Thereafter, the wire 200W is wound into a predetermined shape and other necessary processes are carried out, and the coil body 200 is completed.

[0027] In the past, in order to achieve both flexibility at the tip end and rigidity at the base end of the coil body, a method of joining multiple wires with different properties by, for example, welding or brazing has been used to manufacture the wires that make up the coil body. In such cases, there has been a problem in that the wires are prone to breakage at the joints.

[0028] In this embodiment, the wires 200W constituting the coil body 200 are formed from the composite material 500, which is a clad material, and therefore the wires 200W have no joints. This makes it possible to prevent breakage of the wires 200W, and to obtain a coil body 200 with high durability.

[0029] A-3. Operation of the Guidewire 10: The guidewire 10 advances while rotating inside a biological lumen when the operator rotates the gripping portion 100G. When passing through a curved portion of a biological lumen, the guidewire 10 rotates while curving to follow the curved shape of the biological lumen. The distal end of the coil body 200 has the core wire 210 exposed from the coating layer 220, and is thinner and more flexible than the portion other than the distal end. This reduces the risk of the distal end of the guidewire 10 damaging the biological lumen. The portion of the coil body 200 other than the distal end is covered by the coating layer 220, ensuring a certain level of rigidity compared to the distal end without the coating layer 220. This allows the force applied to the proximal end by an operator such as a physician to push the guidewire 10 toward a lesion in the biological lumen to be smoothly transmitted to the distal end.

[0030] In particular, by making the Young's modulus of the coating layer 220 larger than that of the core wire 210, a high elastic force can be imparted to the proximal end of the coil body 200 where the coating layer 220 is disposed, which allows the force that pushes the guidewire 10 toward the lesion in the biological lumen to be transmitted more smoothly to the distal end.

[0031] Since the core wire 210 is radiopaque, visibility under radioscopic images can be sufficiently ensured at both the tip end where the core wire 210 is exposed from the covering layer 220 and the base end where the core wire 210 is covered by the covering layer 220.

[0032] A-4. Effects of the Embodiment: As described above, according to the present embodiment, the guidewire 10 includes a core shaft 100 having a distal end 101 and a proximal end 102 opposite the distal end 101, and a coil body 200 arranged to surround the distal end of the core shaft 100, the coil body 200 being a clad material in which a metal core wire 210 and a metal coating layer 220 covering the outer periphery of the core wire 210 are bonded to each other, and the core wire 210 is exposed from the coating layer 220 at the distal end of the coil body 200.

[0033] According to the above configuration, the core wire 210 is exposed from the coating layer 220 at the distal end of the coil body 200, resulting in a thin and flexible structure. This reduces the risk of the distal end of the guidewire 10 damaging the biological lumen. In the portion of the coil body 200 excluding the distal end, the outer periphery of the core wire 210 is covered with the coating layer 220, ensuring a certain level of rigidity. This allows the force pushing the guidewire 10 toward the lesion in the biological lumen to be smoothly transmitted to the distal end.

[0034] The coil body 200 has irregularities at the interface between the core wire 210 and the covering layer 220. With this configuration, the core wire 210 and the covering layer 220 are firmly joined together.

[0035] The core wire 210 is radiopaque. With this configuration, it is possible to ensure sufficient visibility of the coil body 200 under a radioscopic image.

[0036] The Young's modulus of the coating layer 220 is greater than that of the core wire 210. With this configuration, a high elastic force can be imparted to the portion of the coil body 200 where the coating layer 220 is disposed. This allows the force that pushes the guidewire 10 toward the lesion in the biological lumen to be transmitted more smoothly to the distal end.

[0037] B. Second Embodiment A second embodiment will be described with reference to Fig. 4. In the guidewire 10A of this embodiment, the configuration of the coil body 200A is different from that of the first embodiment. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0038] The guidewire 10A of this embodiment includes a core shaft 100, a coil body 200A, a distal joint portion 300, and a proximal joint portion 400. The distal end of the coil body 200A is an exposed portion 201A where the core wire 210 is exposed from the coating layer 220, and the remaining portion is a coated portion 202A where the core wire 210 is covered by the coating layer 220. The outer diameter D1 of the exposed portion 201A is smaller than the outer diameter D2 of the coated portion 202A. The other configurations of the coil body 200A are similar to those of the first embodiment.

[0039] In this embodiment, as in the first embodiment, the exposed portion 201A of the coil body 200A has a thin and flexible structure, and a certain level of rigidity is ensured in the covered portion 202A, which allows the force that pushes the guidewire 10 toward the lesion in the biological lumen to be smoothly transmitted to the distal end.

[0040] C. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment and can be modified into various forms without departing from the gist thereof. For example, the following modifications are also possible. (1) The coil body may have a portion whose diameter decreases from the base end to the tip end. Alternatively, the inner diameter of the exposed portion of the coil body may be larger than the inner diameter of the coated portion. (2) In the above-described embodiment, the coil body includes one coating layer. The coil body may include two or more coating layers. (3) In the above-described embodiment, the coil body 200 is illustrated as being formed by helically winding one strand 200W. The coil body may be a multi-strand coil formed by helically winding multiple strands. (4) The wire diameter of the portion of the core wire exposed from the coating layer may be smaller than the wire diameter of the portion covered by the coating layer.

Claims

1. A guide wire (10) comprising: a core shaft (100) having a tip (101) and a base end (102) opposite to the tip (101); and a coil body (200) disposed to surround the tip portion of the core shaft (100), wherein the coil body (200) is a clad material in which a metal core wire (210) and a covering layer (220) made of metal and covering the outer periphery of the core wire (210) are joined to each other, and a tip portion of the coil body (200) is an exposed portion (201) where the core wire (210) is exposed from the covering layer (220).

2. The guide wire (10) according to claim 1, wherein the coil body (200) has irregularities at the interface between the core wire (210) and the covering layer (220).

3. The guide wire (10) according to claim 1 or 2, wherein the core wire (210) has radiation impermeability.

4. The guide wire (10) according to any one of claims 1 to 3, wherein the Young's modulus of the covering layer (220) is greater than the Young's modulus of the core wire (210).

5. The guide wire (10A) according to any one of claims 1 to 4, wherein in the coil body (200A), an outer diameter (D1) of the exposed portion (201A) is smaller than an outer diameter (D2) of a covered portion (202A) which is a portion excluding the exposed portion (201A).

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