catheter

Abstract

The objective is to provide a catheter that can suppress kinking while providing flexibility to the tip and rigidity to the proximal end. [Solution] The catheter 1 comprises a first coil 111 formed by spirally winding a first strand 111w, wherein the radial thickness t1 of the first strand 111w at the tip portion 111a decreases toward the tip, and a second coil 121 formed by spirally winding a second strand 121w, wherein the base portion 121a is joined to the tip portion 111a of the first coil 111 at a joint portion J, the tip extends toward the tip beyond the tip of the first coil 111, and the radial thickness t22 of the second strand 121w is smaller than the radial thickness t11 of the first strand 111w at the base portion 111b of the first coil 111.

Description

Technical Field

[0001] The present disclosure relates to a catheter.

Background Art

[0002] As a medical device to be inserted into a body cavity such as a blood vessel, a catheter is known. In such a catheter, pushability and body cavity followability are required so that it can be smoothly pushed forward to the end even in a body cavity that is complexly curved.

[0003] As a catheter that achieves both pushability and body cavity followability, a catheter using a double-wound wire has been proposed (see, for example, Patent Document 1). In such a catheter, for example, by arranging a coil portion only on a part of the outer periphery of the braided portion, flexibility is imparted to a part of the catheter, and rigidity is provided to other parts.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-described catheter, the structure of the catheter changes greatly at the end of the coil portion. Due to this structural change, a large rigidity change occurs in the catheter along the long axis direction. As a result, kinks are likely to occur when the catheter is used.

[0006] The present disclosure provides a catheter capable of suppressing the occurrence of kinks.

Means for Solving the Problems

[0007] The catheter of this disclosure comprises a first coil formed by spirally winding a first wire, wherein the radial thickness of the first wire at its tip decreases toward the tip, and a second coil formed by spirally winding a second wire, wherein its base end is joined to the tip of the first coil at a joint, its tip extends toward the tip beyond the tip of the first coil, and the radial thickness of the second wire is smaller than the radial thickness of the first wire at the base end of the first coil. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic longitudinal cross-sectional view showing one embodiment of the present disclosure. [Figure 2] This is a schematic longitudinal cross-sectional view showing an enlarged portion of Figure 1. [Figure 3] This is a partially enlarged schematic longitudinal cross-sectional view illustrating another embodiment of the present disclosure. [Figure 4] This is a partially enlarged schematic longitudinal cross-sectional view illustrating another embodiment of the present disclosure. [Figure 5] This is a partially enlarged schematic longitudinal cross-sectional view illustrating another embodiment of the present disclosure. [Figure 6] This is a partially enlarged schematic longitudinal cross-sectional view illustrating another embodiment of the present disclosure. [Figure 7] This is a partially enlarged schematic longitudinal cross-sectional view illustrating another embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] (1) The catheter of the present disclosure comprises: a first coil formed by spirally winding a first wire, wherein the radial thickness of the first wire at the tip decreases toward the tip; and a second coil formed by spirally winding a second wire, wherein the base end is joined to the tip of the first coil at a joint, the tip extends toward the tip beyond the tip of the first coil, and the radial thickness of the second wire is smaller than the radial thickness of the first wire at the base end of the first coil. This configuration makes it possible to mitigate changes in stiffness at the tip of the first coil in the longitudinal direction. As a result, it is possible to impart flexibility to the tip of the catheter and stiffness to the proximal end while suppressing the occurrence of kinking.

[0010] (2) In the catheter described in (1) above, the width of the second wire in the longitudinal direction may be greater than the thickness of the second wire in the radial direction. This configuration allows the second wire to be arranged such that it is flattened along its long axis. As a result, the outer diameter of the second coil can be reduced compared to a coil with a circular cross-sectional shape, even with the same rigidity.

[0011] (3) In the catheter described in (2) above, the shape of the cross-section of the second wire may be rectangular. This configuration allows the second wire to be arranged such that it is flattened along its long axis. As a result, the outer diameter of the second coil can be reduced compared to a coil with a circular cross-sectional shape, even with the same rigidity.

[0012] (4) In the catheters described in (1) to (3) above, the proximal end of the second coil may be located on the outer circumferential surface of the tip of the first coil. With this configuration, the base end of the second coil can be placed over the outer circumference of the tip end of the first coil, and then the first coil and the second coil can be joined together to easily form a joint.

[0013] (5) In the catheter according to (1) to (4) above, the tip of the first coil may have a frustum-shaped portion whose outer peripheral surface has a reduced diameter toward the tip side. According to this configuration, the rigidity of the tip of the first coil can be gently changed along the longitudinal axis direction. As a result, the occurrence of kinks can be more reliably suppressed.

[0014] (6) In the catheter according to (1) to (5) above, the joint portion may be formed so that there is no gap in the region where the first coil and the second coil abut. According to this configuration, the surface where the first coil and the second coil contact can be made wider. As a result, the first coil and the second coil can be firmly joined.

[0015] (7) In the catheter according to (1) to (6) above, an outer layer covering the second coil is provided, the outer layer has a tapered portion whose outer peripheral surface tapers toward the tip side, and the base end of the tapered portion may be located on the tip side of the tip of the joint portion. According to this configuration, in addition to the gradual change in rigidity at the tip of the first coil in the longitudinal axis direction, the rigidity can also gradually change along the longitudinal axis direction at the tapered portion of the outer layer. As a result, the change in rigidity at the tip of the catheter can be effectively suppressed in multiple stages.

[0016] (8) In the catheter according to (1) to (7) above, a reinforcing member provided inside the first coil and extending along the longitudinal axis direction of the first coil may be provided. According to this configuration, the catheter body can be reinforced, and for example, it is possible to prevent the catheter from breaking due to an external force.

[0017] (9) In the catheter according to (1) to (8) above, the outer surface of the first wire at the tip of the first coil has a curved surface that is a part of a virtual cylindrical surface centered on the longitudinal axis of the first coil, and the joint portion may be formed on the curved surface. According to this configuration, the contact area between the tip of the first coil and the base end of the second wire can be increased, and the joining strength between the first coil and the second coil can be improved.

[0018] In this specification, the "tip side" refers to the direction along the long axis of the catheter (long axis direction), which is the direction in which the catheter advances toward a predetermined site in the body cavity (distal side). The "base end side" refers to the direction along the long axis of the catheter (long axis direction), which is the direction opposite to the tip side (proximal side). The "tip" refers to the end on the tip side of any member. The "base end" refers to the end on the base end side of any member. The "radial direction" refers to the radial direction perpendicular to the long axis direction of the catheter.

[0019] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The present disclosure is not limited only to the embodiments described in the drawings. The dimensions of each part shown in the drawings are the dimensions shown for the purpose of facilitating the understanding of the implementation content, and do not necessarily correspond to the actual dimensions.

[0020] In FIGS. 1 to 7, the left side shown in the figure is the tip side (distal side) inserted deeper into the body, and the right side is the base end side (proximal side, near the hand side) operated by a technician such as a doctor.

[0021] FIGS. 1 and 2 are schematic views showing an embodiment of the present disclosure. As shown in FIG. 1, the catheter 1 includes, for example, a catheter body 10, a tip chip 61, and a base 71.

[0022] The catheter body 10 can be formed, for example, by a first coil 111, a second coil 121, a reinforcing body 21, an outer layer 31, an intermediate layer 41, and an inner layer 51. The catheter body 10 has a lumen 10h radially inside the inner layer 51. In the present embodiment, an outer coil body 11 is formed by the first coil 111 and the second coil 121.

[0023] The first coil 111 is a coil formed by winding the first strand 111w in a spiral shape. The shape of the first strand 111w is not particularly limited. In this embodiment, the cross-sectional shape of the first strand 111w at the base end 111b of the first coil 111 is circular.

[0024] As shown in Figure 2, the first coil 111 is formed such that the radial thickness t1 of the first wire 111w at its tip portion 111a decreases toward the tip. The tip portion 111a of the first coil 111 may have a frustoconical portion (tapered surface) on its outer surface 111g that narrows toward the tip, so that the outer diameter of the first coil 111 gradually tapers toward the tip. This allows the rigidity of the first coil 111 to be changed gradually along the long axis. As a result, kinking of the catheter body 10 can be suppressed more reliably.

[0025] The tip portion 111a of the first coil 111 may be formed into a frustoconical (tapered) shape by, for example, winding a wire 111w spirally to form a coil, and then polishing the outer surface of the coil. In this case, the outer surface of the cross-section of the first wire 111w at the tip portion 111a is formed to include a straight portion and an arc-shaped portion.

[0026] At the tip portion 111a of the first coil 111, the outer surface of the first wire 111w has a curved surface 111c which is part of a virtual cylindrical surface with the major axis Z of the first coil 111 as its central axis. The curved surface 111c is provided at the tip of the tip portion 111a. A joint J with the second coil 121, which will be described later, is formed on the curved surface 111c. The curved surface 111c is provided over a plurality of adjacent first wires 111w in the direction of the major axis of the first coil 111. In this embodiment, the curved surface 111c is provided over two adjacent wires 111w in the direction of the major axis of the first coil 111. The thickness t1 of the first wire 111w having the curved surface 111c is smaller than the thickness t1 of the first wire 111w in the tip portion 111a that does not have the curved surface 111c. In this embodiment, when the cross-sectional shape of the first wire 111w is circular, the outer circumference of the cross-sectional shape of the first wire 111w having a curved surface 111c consists of a straight portion and an arc-shaped portion. By providing the curved surface 111c, the contact area between the tip portion 111a of the first coil 111 and the base portion 121a of the second wire 121 is increased, thereby improving the bonding strength between the first coil 111 and the second coil 121.

[0027] In this embodiment, the first strand 111w having a curved surface 111c is provided with a perpendicular plane 111d that is perpendicular to the curved surface 111c and extends radially outward from the base end of the curved surface 111c. By providing the plane 111d, the contact area between the tip portion 111a of the first coil 111 and the base end portion 121a of the second strand 121 is further increased, thereby further improving the bonding strength between the first coil 111 and the second coil 121.

[0028] The length of the plane 111d in the direction of the thickness t1 of the wire 111w may be the same as the thickness t22 of the second wire 121w. The length of the plane 111d may be greater than the thickness t22 of the second wire 121w. As a result, the sum of the thickness t1 of the first wire 111w having a curved surface 111c and the thickness t22 of the proximal end 121a of the second wire 121 is smaller than the thickness t1 of the wire 111w without a curved surface 111c. Consequently, the rigidity of the catheter body 10 where the joint J is located can be reduced toward the tip.

[0029] The curved surface 111c can be formed by polishing the outer surface of the first coil 111 by a predetermined dimension (a predetermined amount of polishing). Increasing the amount of polishing of the first coil 111 reduces the thickness t1 of the first wire 111w having the curved surface 111c, while increasing the length of the plane 111d in the direction of the thickness t1 of the wire 111w. If the amount of polishing of the first coil 111 is set to 1 / 2 of the thickness t1 of the wire 111w before polishing, the cross-sectional shape of the wire 111w after polishing becomes semicircular.

[0030] The second coil 121 is a coil formed by spirally winding the second strand 121w. The shape of the second strand 121w is not particularly limited. For example, the width t21 of the second strand 121w in the longitudinal direction may be greater than the thickness t22 of the second strand 121w in the radial direction. In this embodiment, the cross-sectional shape of the second strand 121w is rectangular, and its short side is arranged along the radial direction. This allows the second strand 121w to be arranged so that it is flattened along the longitudinal direction. As a result, the outer diameter of the second coil 121 can be reduced compared to a coil with a circular cross-sectional shape of the strand, even with the same rigidity.

[0031] The second coil 121 has its base end 121a joined to the tip end 111a of the first coil 111 at a joint J, and its tip extends further toward the tip than the tip of the first coil 111. The base end 121a of the second coil 121 may be positioned, for example, on the outer circumferential surface 111g of the tip end 111a of the first coil 111. This makes it easy to form the joint J by covering the outer circumference of the tip end 111a of the first coil 111 with the base end 121a of the second coil 121 and then joining the first coil 111 and the second coil 121.

[0032] The second coil 121 is formed such that the thickness t22 of the second strand 121w in the radial direction is smaller than the thickness t11 of the first strand 111w in the radial direction at the base end 111b of the first coil 111. In this embodiment, since the cross-sectional shape of the second strand 121 is rectangular, the length of its shorter side corresponds to the thickness t22 of the second strand 121w. Since the cross-sectional shape of the first strand 111w at the base end 111b of the first coil 111 is circular, its diameter corresponds to the thickness t11 of the first strand 111w.

[0033] The joint J between the first coil 111 and the second coil 121 will now be described. The joint J can be formed so that there is no gap in the area where the first coil 111 and the second coil 121 come into contact. That is, the surfaces of the first coil 111 and the second coil 121 facing each other at the joint J may be in contact (joined) so that they match. In this embodiment, the surface of the second wire 121w corresponding to the long side of the rectangle described above is in surface contact with the outer circumferential surface 111g of the first wire 111w. The joint J can be formed, for example, by further polishing the tip portion of the tip 111a of the first coil 111, which is formed into a frustoconical (tapered) shape.

[0034] The reinforcing member 21 is provided inside the first coil 111 and extends along the long axis of the first coil 111. The reinforcing member 21 may be formed, for example, by braiding strands 21w into a mesh. The reinforcing member 21 may also be formed by winding strands 21w in a spiral shape. The shape of the strands 21w is not particularly limited. In this embodiment, the reinforcing member 21 is formed by using strands 21w with a circular cross-section and winding the strands 21w in a spiral shape.

[0035] In a reinforcing body 21 in which strands 21w are wound spirally, adjacent strands of the reinforcing body 21 in the longitudinal direction may be in contact with each other (tightly wound). Alternatively, the strands of the reinforcing body 21 may be spaced apart from each other (sparsely wound). In this embodiment, a sparsely wound reinforcing body 21 is exemplified. This allows for greater flexibility of the tip of the catheter 1 because there is more space between adjacent strands 21w, 21w along the longitudinal direction.

[0036] The catheter 1 is equipped with a reinforcing body 21, which reinforces the catheter body 10 and, for example, prevents the catheter from breaking due to external force.

[0037] The materials forming the strands 111w, 121w, and 21w of the outer coil body 11 and the reinforcing body 21 may have antithrombotic and biocompatible properties. Examples of such materials include stainless steel such as SUS316; superelastic alloys such as Ni-Ti alloys; and radiopaque metals such as platinum and tungsten.

[0038] The outer layer 31 is a component that covers the second coil 121. In the catheter 1, the outer layer 31 covers both the second coil 121 and the first coil 111. The outer peripheral surface 31g of the outer layer 31 is smoothly formed. This allows the catheter 1 to be smoothly advanced within the body cavity.

[0039] In catheter 1, the outer layer 31 has a tapered portion 31a where the outer peripheral surface 31g tapers toward the tip. The base end of the tapered portion 31a may be located between the tip of the second coil 121 and the tip of the joint J. The base end of the tapered portion 31a may be located toward the tip of the second coil 121. In this embodiment, the tip of the tapered portion 31a is located toward the tip of the second coil 121, and the base end p1 of the tapered portion 31a is located between the tip of the second coil 121 and the tip of the joint J. This allows for a gradual change in stiffness along the long axis in the tapered portion 31a of the outer layer 31, in addition to the gradual change in stiffness at the tip portion 111a of the first coil 111 in the long axis direction. As a result, the change in stiffness at the tip of catheter 1 can be effectively suppressed in multiple stages.

[0040] The intermediate layer 41 is a member that covers the reinforcing body 21. The intermediate layer 41 is provided radially inward of the outer layer 31 so as to be in contact with the inner circumferential surface of the outer layer 31, and covers the entire reinforcing body 21. By providing the intermediate layer 41, the reinforcing body 21 can be securely fixed to the outer layer 31.

[0041] The materials forming the outer layer 31 and the intermediate layer 41 may have antithrombotic, flexible, and biocompatible properties. Examples of such materials include resin materials such as polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, and polyurethane elastomer.

[0042] The inner layer 51 is a component positioned to face the lumen 10h of the catheter body 10. The inner layer 51 is provided radially inward of the intermediate layer 41 so as to be in contact with the inner circumferential surface of the intermediate layer 41, and covers the entire inner circumferential surface of the intermediate layer 41.

[0043] The inner layer 51 is provided with a function to enhance sliding properties with medical devices such as guide wires inserted into the lumen 10h. Examples of materials that form the inner layer 51 include resin materials such as polytetrafluoroethylene (PTFE), FEP (fluorinated ethylene propylene), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

[0044] The tip 61 is a component provided at the tip of the catheter 1. The tip 61 has an opening 61a at its tip and a lumen 61h that communicates with the lumen 10h. Specifically, the base end of the tip 61 is fixed to the tip of the catheter body 10. The tip 61 may be formed in a rounded shape toward the tip, for example, to facilitate the movement of the catheter 1 within the body cavity.

[0045] The material forming the tip 61 may have antithrombotic properties, be biocompatible, and be flexible. Examples of such materials include resin materials such as polyurethane and polyurethane elastomer.

[0046] Methods for joining the tip 61 and the catheter body 10 include, for example, a method of welding the resin material of the tip 61 and / or the catheter body 10 while heating it, and a method of bonding the tip 61 and the catheter body 10 with an adhesive.

[0047] The base 71 is a component used by the operator to manipulate the catheter 1. The base 71 is connected to the proximal end of the catheter body 10. The base 71 has, for example, an opening 71a at its proximal end and a lumen 71h that communicates with the lumen 10h. The shape of the base 71 is not particularly limited. The base 71 can be formed, for example, in a shape that is easy for the operator to manipulate.

[0048] In this embodiment, a lumen L is formed by the lumen 61h of the tip 61, the lumen 10h of the catheter body 10, and the lumen 71h of the base 71. A medical device, such as a guidewire, is inserted through the lumen L.

[0049] The usage of catheter 1 will now be described. Catheter 1 can be used, for example, for intravascular treatment of cerebrovascular tissue. Specifically, the proximal end of a guidewire that has been previously inserted into the blood vessel is inserted into the opening 61a of catheter 1, and catheter 1 is advanced along the guidewire to the treatment site. At this time, because kinking is unlikely to occur due to the gradual change in rigidity at the tip of catheter 1, catheter 1 is smoothly delivered to the periphery while following the blood vessel.

[0050] Next, after withdrawing the guidewire from the body, a predetermined procedure is performed, such as injecting a drug solution into the affected area or aspirating body fluids through the lumen L of catheter 1. Alternatively, catheter 1 may be used as a guide to deliver the concomitant device to the affected area. After the predetermined procedure is completed, catheter 1 may be withdrawn from the body while reinserting the guidewire into the opening 71a. This completes the procedure using catheter 1.

[0051] As described above, the catheter 1 has the above configuration, which makes it possible to mitigate changes in rigidity at the tip 111a of the first coil 111 in the longitudinal direction. As a result, it is possible to provide flexibility to the tip of the catheter 1 and rigidity to the proximal end while suppressing the occurrence of kinking. This allows the catheter 1 to be smoothly advanced to the periphery.

[0052] This disclosure is not limited to the configurations of the embodiments described above, but is intended to include all modifications within the meaning and scope of the claims as indicated by the claims. Some of the configurations of the embodiments described above may be deleted or replaced with other configurations, or other configurations may be added to the configurations of the embodiments described above.

[0053] In the embodiments described above, a catheter 1 comprising a first coil 111, a second coil 121, a reinforcing body 21, an outer layer 31, an intermediate layer 41, an inner layer 51, a tip 61, and a base 71 was described. The catheter of this disclosure only needs to comprise at least the first coil and the second coil. The reinforcing body, outer layer, intermediate layer, inner layer, tip, and base can each be optionally provided. For example, a catheter without a reinforcing body may also exist.

[0054] In the embodiments described above, a catheter 1 was described in which the outer circumferential surface 111g of the tip portion 111a of the first coil 111 is frustoconical (tapered), as a catheter in which the radial thickness t1 of the first wire 111w decreases toward the tip. As shown in Figure 3, for example, the tip portion 112a of the first coil 112 may be formed such that the diameter of the first wire 112w gradually decreases toward the tip (see catheter 1A).

[0055] In the embodiments described above, a catheter 1 in which the cross-sectional shape of the second wire 121w is rectangular was described. As shown in Figure 4, for example, the cross-sectional shape of the second wire 123w of the second coil 123 may be circular (see catheter 1B). As shown in Figure 5, the cross-sectional shape of the second wire 124w of the second coil 124 may be elliptical (see catheter 1C).

[0056] In the embodiments described above, a catheter 1 was described in which the tip of the tapered portion 31a of the outer layer 31 is located more to the tip than the tip of the second coil 121, and the base end p1 of the tapered portion 31a is located between the tip of the second coil 121 and the tip of the joint J. As shown in Figure 6, for example, the base end p5 of the tapered portion 35a of the outer layer 35 may be located more to the tip than the tip of the second coil 125 (see catheter 1D).

[0057] In the embodiments described above, a catheter 1 in which the base end of the curved surface 111c is continuous with the flat surface 111d was described. As shown in Figure 7, the tip portion 116a of the first coil 116 may have the base end 116e of the curved surface 116c continuous with the tip of the frustoconical tapered surface.

Claims

1. A first coil (111) formed by winding a first strand (111w) in a spiral shape, wherein the radial thickness (t1) of the first strand (111w) at the tip (111a) decreases toward the tip, A catheter (1, 1A, 1B, 1C, 1D, 1E) comprising: a second coil (121) formed by spirally winding a second strand (121w), the base end (121a) of the first coil (111) being joined to the tip end (111a) of the first coil (111) at a joint (J), the tip extending toward the tip side beyond the tip of the first coil (111), and the radial thickness (t22) of the second strand (121w) being smaller than the radial thickness (t11) of the first strand (111w) at the base end (111b) of the first coil (111).

2. The catheter (1, 1A, 1C, 1D, 1E) according to claim 1, wherein the width (t21) of the second wire (121w) in the longitudinal direction is greater than the thickness (t22) of the second wire (121w) in the radial direction.

3. The catheter (1, 1A, 1D, 1E) according to claim 2, wherein the cross-sectional shape of the second strand (121w) is rectangular.

4. The catheter (1, 1A, 1B, 1C, 1D, 1E) according to any one of claims 1 to 3, wherein the proximal end (121a) of the second coil (121, 123, 124, 125, 126) is located on the outer circumferential surface (111g) of the tip (111a) of the first coil (111, 112, 113, 114, 115, 116).

5. The catheter (1, 1B, 1C, 1D, 1E) according to any one of claims 1 to 4, wherein the tip portions (111a, 115a, 116a) of the first coil (111, 115, 116) have a frustoconical portion on which the outer surface (111g) tapers toward the tip.

6. The catheter (1, 1A, 1B, 1C, 1D, 1E) according to any one of claims 1 to 5, wherein the joint (J) is formed such that there is no gap in the area where the first coil (111, 112, 115, 116) and the second coil (121, 123, 124, 125, 126) come into contact.

7. The device comprises outer layers (31, 35) that cover the second coils (121, 123, 124, 125, 126), The outer layers (31, 35) have tapered portions (31a, 35a) on their outer circumferential surfaces (31g) that narrow towards the tip. The catheter (1, 1A, 1B, 1C, 1D, 1E) according to any one of claims 1 to 6, wherein the proximal ends (p1, p5) of the tapered portions (31a, 35a) are located on the tip side of the joint portion (J).

8. A catheter (1, 1A, 1B, 1C, 1D, 1E) according to any one of claims 1 to 7, comprising a reinforcing member (21) provided inside the first coil (111, 112, 113, 114, 115, 116) and extending along the longitudinal axis of the first coil (111, 112, 113, 114, 115, 116).

9. At the tip portions (111a, 112a, 115a, 116a) of the first coil (111, 112, 115, 116), the outer surface of the first strand (111w, 112w, 115w, 116w) has a curved surface (111c, 112c, 115c, 116c) which is a part of a virtual cylindrical surface with the major axis (Z) of the first coil (111, 112, 115, 116) as its central axis. The catheter (1, 1A, 1B, 1C, 1D, 1E) according to any one of claims 1 to 8, wherein the joint (J) is formed on the curved surface (111c, 112c, 115c, 116c).

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