catheter

Abstract

[Problem] To provide a catheter with which a shaft and a hub can be fixed strongly to one another. [Solution] The catheter (10) comprises: a shaft (20) that is a tube body having formed therein a lumen (21) communicating from a forward end to a base end, the shaft (20) being provided with a shaft base end surface (24) wherein the lumen (21) opens, and a shaft external surface (22) that is the outer peripheral surface of the tube body; and a hub (40) attached to the base end of the shaft (20). The hub (40) has a cylindrical housing portion (41) for housing the shaft (20). The housing portion (41) has a hub weld surface (49) welded directly to the shaft external surface (22). At least one among the housing portion (41) and the hub (40) has a plurality of air bubbles formed at positions that are close to the hub weld surface (49).

Description

[Technical field]

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

[0002] In recent years, catheters have been widely used for intraluminal treatment of blood vessels and other lumens because of their minimal surgical invasiveness. A catheter usually has a shaft with a lumen that communicates from the tip to the base end, and a hub that is disposed at the base end of the shaft. The hub has a passage formed therein that communicates with the lumen in order to connect it to a syringe or the like.

[0003] Known methods for fixing the base end of the shaft to the hub include an insert molding method and a bonding method using an adhesive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-180802 [Patent Document 2] Jpn. Jpn. Published No. 63-17486 Summary of the Invention [Problem to be solved by the invention]

[0005] In the insert molding method described in Patent Document 1, the shaft is placed in an injection mold, a part of the shaft is held down with a fixing pin, and the resin for the hub is injection molded at high temperature and pressure. This may cause deformation of the shaft or misalignment in the axial direction of the shaft due to the fixing pin. The deformation of the shaft or misalignment in the axial direction may cause a decrease in the fixing strength between the shaft and the hub.

[0006] Furthermore, in the adhesive bonding method described in Patent Document 2, if the gap between the outer diameter of the shaft and the inner cavity of the shaft receiving portion of the hub is too small, the adhesive cannot flow in and a gap remains between the hub and shaft, which may result in a decrease in the fixing strength between the shaft and the hub. If the gap between the outer diameter of the shaft and the inner cavity of the shaft receiving portion of the hub is too large, it becomes difficult to completely fill the gap between the hub and shaft with adhesive, which may result in a decrease in the fixing strength between the shaft and the hub.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a catheter in which the shaft and hub can be firmly fixed. [Means for solving the problem]

[0008] The catheter according to the present invention, which achieves the above object, is a catheter having a shaft which is a tubular body having a lumen formed therein that communicates from the tip end to the base end, the shaft having a base end surface at which the lumen opens and a shaft outer surface which is the outer peripheral surface of the tubular body, and a hub attached to the base end of the shaft, the hub having a cylindrical housing portion which houses the shaft, the housing portion comprising: The hub and the shaft have a housing surface that melts and shrinks in diameter when fused together, and an outer peripheral surface that is hardly deformed, The shaft has an outer surface and a hub fusion surface that is directly fused to the outer surface of the shaft. At least one of the housing portion and the hub is The outer circumferential surface of the storage portion is different from A plurality of bubbles are formed in the vicinity of the hub fusion surface. Another aspect of the catheter of the present invention that achieves the above-mentioned object is a catheter having a shaft which is a tubular body having a lumen formed from the tip to the base end, the shaft having a base end surface at which the lumen opens and a shaft outer surface which is the outer peripheral surface of the tubular body, and a hub attached to the base end of the shaft, wherein the hub has a cylindrical receiving portion which receives the shaft, the receiving portion having a hub fused surface which is directly fused to the shaft outer surface, and a plurality of air bubbles are formed as shaft air bubbles only in the shaft at a position close to the hub fused surface. Yet another aspect of the catheter of the present invention that achieves the above-mentioned object is a catheter having a shaft which is a tubular body formed with a lumen communicating from the tip to the base end, the shaft having a base end surface at which the lumen opens and a shaft outer surface which is the outer peripheral surface of the tubular body, and a hub attached to the base end of the shaft, wherein the hub has a cylindrical receiving portion which receives the shaft, the receiving portion has a hub fused surface which is directly fused to the shaft outer surface, and a plurality of air bubbles are formed as hub air bubbles only in the hub at a position close to the hub fused surface. Effect of the Invention

[0009] In the catheter constructed as described above, the housing portion and the hub are fused together by the air bubbles so that they can penetrate into each other, thereby enabling the shaft and the hub to be firmly fixed together.

[0010] The housing portion may have a plurality of hub bubbles formed in a position adjacent to the hub fusion surface, so that the hub fusion surface of the housing portion has a complex shape having projections and recesses and is fused to the outer surface of the shaft, thereby enabling the shaft and the hub to be firmly fixed to each other.

[0011] The shaft may have a plurality of shaft bubbles formed in the shaft outer surface adjacent to the shaft fused surface, which is fused to the hub fused surface. As a result, the shaft outer surface is fused to the hub fused surface in a complex shape having projections and recesses. This allows the shaft and the hub to be firmly fixed together.

[0012] Both the hub and the shaft may have a plurality of the air bubbles, and the hub fusion surface and the shaft fusion surface of the shaft outer surface fused to the hub fusion surface may be fused to each other with unevenness, thereby enabling the shaft and the hub to be fixed more firmly. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view showing a catheter according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the hub and the proximal end of the shaft. [Diagram 3] 4 is a cross-sectional view showing the distal end of the hub and the proximal end of the shaft. FIG. [Figure 4] 4 is a cross-sectional view showing the tip portion of the hub before the shaft is fixed thereto. FIG. [Diagram 5] 1A and 1B are cross-sectional views showing the process of fusing a shaft to a hub, where (A) shows the state at the start of fusing and (B) shows the state after fusing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated for convenience of explanation and may differ from the actual ratios. In the following description, the side of the catheter that is operated is referred to as the "base end side," and the side that is inserted into the living body is referred to as the "distal end side."

[0015] As shown in Figs. 1 to 3, a catheter 10 according to an embodiment of the present invention includes a shaft 20 which is a long tubular body, a hub 40 fixed to the base end of the shaft 20, and a flexible anti-kink protector 60 for suppressing bending of the shaft 20. The catheter 10 may be a guiding catheter, an angiography catheter, or a microcatheter other than a catheter supporting a guidewire, or may be a balloon catheter or an imaging diagnostic catheter having an expansion lumen. The catheter 10 may be an over-the-wire (OTW) type in which a guidewire lumen is formed that communicates from the tip of the shaft to the hub, or a rapid exchange (RX) type in which a guidewire lumen is formed only at the tip of the shaft. For example, the guidewire lumen of an RX type balloon catheter is formed from the tip of the shaft to an opening partway in the axial direction of the shaft. The expansion lumen through which a fluid for expanding the balloon of an RX type balloon catheter flows is formed so as to communicate from the balloon to the hub at the base end of the catheter.

[0016] The shaft 20 has a lumen 21 that communicates from the distal end to the proximal end. The shaft 20 has an outer shaft surface 22, an inner shaft surface 23, and a proximal shaft surface 24.

[0017] The shaft outer surface 22 is the radially outer surface of the shaft 20, which is a tube, and extends from the tip to the base end of the shaft 20. The shaft outer surface 22 has a shaft base end side outer surface 25 formed from the base end of the shaft 20 toward the tip to a predetermined position. The shaft base end side outer surface 25 is surrounded and accommodated by the hub 40. The shaft base end side outer surface 25 has a substantially uniform outer diameter along the axis X of the shaft 20. The shaft base end side outer surface 25 has a shaft fused surface 26 fused to the hub 40, and a shaft separation surface 27 disposed on the tip side of the shaft fused surface 26 and separated from the hub 40. The shaft separation surface 27 is not fused to the hub 40 and is separated from the hub 40 with a gap therebetween. A plurality of shaft bubbles 32 are formed in the vicinity of the shaft fused surface 26 of the shaft 20. Each shaft bubble 32 has an inner surface surrounding a closed space.

[0018] The shaft inner surface 23 is the radially inner surface of the shaft 20, which is a tubular body, and extends from the tip end to the base end of the shaft 20.

[0019] The shaft base end surface 24 is a surface facing the base end side at the base end of the shaft 20, and is formed by cutting perpendicularly to the axis X of the shaft 20.

[0020] The shaft 20 in this embodiment has an inner layer 28 that forms the shaft inner surface 23 , an outer layer 29 that forms the shaft outer surface 22 , and a reinforcing body 30 embedded in the shaft 20 .

[0021] Examples of materials constituting the outer layer 29 include polyamide resin, polyester resin, polyolefin resin, polyurethane resin, polyamide elastomer, polyester elastomer, polyurethane elastomer, or a mixture of one or more of these, or a mixture of materials with different hardness. The outer layer 29 may be an arrangement of materials with different hardness so that it becomes softer from the base end to the tip end.

[0022] The constituent material of the inner layer 28 may be the same as the constituent material of the outer layer 29 described above, or may be a material different from the constituent material of the outer layer 29. The constituent material of the inner layer 28 may be a fluorine-based resin material such as polytetrafluoroethylene resin in order to improve the sliding property of the inner circumferential surface of the shaft 20.

[0023] The reinforcing body 30 reinforces the shaft 20, and is formed by braiding a plurality of reinforcing wires 31 into a cylindrical shape. The reinforcing body 30 may also be formed by winding one or more reinforcing wires 31 in a spiral shape. The material of the outer layer 29 or the inner layer 28 fills the gaps between the plurality of reinforcing wires 31 in the reinforcing body 30. The reinforcing wires 31 are made of a metal such as stainless steel or NiTi.

[0024] The hub 40 has a cylindrical housing portion 41 disposed on the distal side for housing the proximal end of the shaft 20, a hub body 42 disposed on the proximal side of the housing portion 41, wings 52, a threaded projection 53, and an annular projection 54. The hub 40 has a hub lumen 45 that communicates from a hub distal opening 43 formed at the distal end of the housing portion 41 to a hub proximal opening 44 formed at the proximal end of the hub body 42. The hub lumen 45 is defined by a housing surface 46 which is the inner circumferential surface of the housing portion 41, and an adjacent surface 47 which faces the shaft proximal end surface 24. and a hub passage 48 which is the inner circumferential surface of the hub body 42.

[0025] The receiving surface 46 has a hub fused surface 49 directly fused to the shaft fused surface 26 of the shaft base end side outer surface 25, and a hub separation surface 50 facing the shaft separation surface 27 and spaced radially outward. The hub fused surface 49 extends from the base end of the receiving surface 46 toward the tip end. The base end of the hub fused surface 49 is connected to the adjacent surface 47. The hub separation surface 50 extends from the tip of the hub fused surface 49 toward the tip end. A gap between the hub separation surface 50 and the shaft base end side outer surface 25 in the radial direction widens toward the tip end. The hub separation surface 50 that forms a gap between the shaft base end side outer surface 25 may not be provided. A plurality of hub bubbles 55 are formed in the vicinity of the hub fused surface 49 of the receiving portion 41. Each hub bubble 55 has an inner surface that surrounds a closed space.

[0026] The adjacent surface 47 is an annular surface facing the tip side, and is formed approximately perpendicular to the axis X of the shaft 20. The radial outer side of the adjacent surface 47 is connected to the hub fusion surface 49. The radial inner side of the adjacent surface 47 is connected to the tip of the hub passage 48.

[0027] The hub passage 48 extends from the adjacent surface 47 toward the proximal end. The hub passage 48 is tapered with an inner diameter that gradually increases toward the proximal end. The hub passage 48 is preferably coaxial with the receiving surface 46 and the lumen 21. The inner diameter of the tip of the hub passage 48 is preferably approximately the same as the inner diameter of the shaft 20, but is not limited to this. A part of the tapered hub passage 48 may have a luer taper portion 51 that can be connected to a syringe (not shown). A guidewire or a treatment catheter inserted from the hub proximal opening 44 smoothly passes through the hub lumen 45 and the lumen 21 and protrudes from the tip of the catheter 10. This allows the guidewire or the treatment catheter 10 to easily reach the target location, such as a lesion.

[0028] The wings 52 are formed to protrude from two opposing points on the outer circumferential surface of the hub body 42 so that the surgeon can easily grasp and operate the hub 40. The threaded projection 53 is formed on the outer circumferential surface on the base end side of the hub body 42. The threaded projection 53 is engageable with a locking type syringe or the like. The annular projection 54 is a projection formed over 360° on the outer circumferential surface of the housing portion 41. The annular projection 54 is engageable with a groove formed on the inner circumferential surface of the anti-kink protector 60.

[0029] The material of the hub 40 is not particularly limited as long as it is a thermoplastic resin that can be injection molded, but it is preferable for it to be one that is easily permeable to heat or electromagnetic waves, such as polyolefin resin, polyamide resin, polycarbonate resin, polyester resin, etc.

[0030] Next, a method of fusing the shaft 20 and the hub 40 will be described. As shown in FIG. 4, before the shaft 20 is fused to the hub 40, the inner diameter of the housing surface 46 is larger on the tip side than on the base side. Specifically, the inner diameter D1 of the hub tip opening 43 is larger than the inner diameter D2 of the tip and base ends of the hub fused surface 49. The inner diameter D3 of the tip of the hub passage 48 is smaller than the inner diameter D2 of the base end of the hub fused surface 49. The inner diameter D2 of the hub fused surface 49 is approximately equal to the outer diameter of the shaft base end side outer surface 25. The inner diameter D1 of the hub tip opening 43 is, for example, 0.92 mm. The inner diameter D2 of the base end of the hub fused surface 49 is, for example, 0.88 mm. The inner diameter D3 of the tip of the hub passage 48 is, for example, 0.57 mm.

[0031] First, the base end side of the shaft 20 is inserted into the housing portion 41, and the shaft base end surface 24 is brought into contact with the adjacent surface 47. The shaft base end surface 24 may not come into contact with the adjacent surface 47, and there may be a gap between the shaft base end surface 24 and the adjacent surface 47. The base end of the shaft base end side outer surface 25 comes into contact with the base end of the hub fused surface 49. The shaft base end side outer surface 25 may not come into contact with the hub fused surface 49, and there may be a gap between the shaft base end side outer surface 25 and the hub fused surface 49.

[0032] Next, a mandrel (not shown) is inserted into the lumen 21 of the shaft 20, and the shaft proximal outer surface 25 and the housing portion 41 of the hub 40 are heated. As a result, the shaft proximal outer surface 25 and the housing surface 46 are melted, and the hub fusion surface 49 and the shaft fusion surface 26 are fused. The hub fusion surface 49 and the shaft fusion surface 26 may be mixed together to form an integrated structure. The heating method is not particularly limited, and examples include a method of irradiating electromagnetic waves with a wavelength that is transmitted through the hub 40 but not transmitted through the shaft outer surface 22. Since the shaft outer surface 22 is not transparent to electromagnetic waves, the shaft proximal outer surface 25 is heated and melted first. Then, the heat of the shaft proximal outer surface 25 is transferred to the housing portion 41, causing the housing portion 41 to melt.

[0033] Electromagnetic waves include heat, microwaves, visible light, and infrared rays. Infrared rays are near infrared rays with wavelengths of approximately 0.7 μm to 2.5 μm, mid infrared rays with wavelengths of approximately 2.5 μm to 4 μm, or far infrared rays with wavelengths of approximately 4 μm to 1000 μm. They may be near infrared rays, mid infrared rays, or far infrared rays alone or in combination of two or more types, or may include visible light or microwaves.

[0034] The method of irradiating the electromagnetic waves is not particularly limited, and may be a semiconductor solid-state laser such as a neodymium YAG laser, or a fiber laser.

[0035] The term "electromagnetic wave transmission" means that the material appears transparent to the naked eye when exposed to visible light, and that the measured transmittance (hereinafter referred to as "transmittance") is 80% or more, more preferably 85% or more. The transmittance can be measured by irradiating electromagnetic waves of a specific wavelength onto a sheet having a thickness of 0.4 mm to 0.5 mm, which is produced by melt pressing resin pellets, and using a spectroscopic analyzer, for example, a Fourier transform infrared / near infrared spectroscopic analyzer. Therefore, since electromagnetic waves are not limited to visible light, the term "electromagnetic wave transmission" includes being transparent to a specific wavelength even if the material appears colored or opaque to the naked eye.

[0036] Moreover, "not transmitting electromagnetic waves" means that the material appears opaque or colored to the naked eye when exposed to visible light, and also means that the transmittance is less than 80%, preferably less than 10%, and more preferably less than 1%. Therefore, since electromagnetic waves are not limited to visible light, "not transmitting electromagnetic waves" includes being opaque or absorbing to specific wavelengths even if it appears transparent to the naked eye.

[0037] The outer layer 29 may be mixed with a pigment that does not transmit or absorbs heat or electromagnetic waves in an amount of 0.01 wt% or more and less than 10 wt%, preferably 0.05 wt% or more and 5 wt% or less, and more preferably 0.1 wt% or more and 1% or less, based on the entire resin. Alternatively, the outer layer 29 may not contain a pigment or a contrast agent, and the resin forming the outer layer 29 may have low transmittance for a specific wavelength. Alternatively, the outer layer 29 may be mixed with a metal having X-ray contrast properties instead of or together with the pigment.

[0038] The pigment is not particularly limited as long as it is a pigment that develops a white, black, blue, red, or yellow color, or a mixture thereof, but a black pigment, such as carbon black, is preferred as it easily absorbs electromagnetic waves. The X-ray contrast medium is, for example, a compound of gold, bismuth, or tungsten, and is more preferably in powder form.

[0039] For example, as shown in FIG. 5(A), when infrared laser L is irradiated to fuse the shaft 20 and the hub 40, electromagnetic waves transmitted through the hub 40, which is transparent to the wavelength of the irradiated infrared laser L, are absorbed by the opaque resin or pigment of the outer layer 29 of the shaft 20, mainly generating heat. As a result, the resin of the outer layer 29 melts and transfers heat H to the housing part 41 of the hub 40, and at least a part of the housing surface 46 melts. As shown in FIG. 5(B), the melted housing surface 46 contracts in diameter and comes into close contact with the shaft base end side outer surface 25, and is fused to the shaft base end side outer surface 25. As a result, the hub fusion surface 49 and the shaft fusion surface 26 are fused and formed. At this time, the housing surface 46 melts and contracts in diameter, but the outer peripheral surface of the housing part 41 does not melt because almost no heat is transferred thereto, and is hardly deformed. Therefore, due to the diameter reduction of the housing surface 46, the material constituting the housing surface 46 flows to fill the gap between it and the shaft base-side outer surface 25, and as a result, the length along the axis X of the housing portion 41 is reduced. This allows the housing portion 41 and the shaft base-side outer surface 25 to be well fused with no gaps. In addition, the shaft base-end surface 24 and the adjacent surface 47 are also melted and fused with each other due to the heat generated by the outer layer 29. Note that the shaft base-end surface 24 does not have to be fused to the adjacent surface 47.

[0040] When the shaft base end side outer surface 25 and the housing surface 46 are fused, as shown in FIG. 3, shaft bubbles 32 are formed near the shaft fused surface 26 of the shaft 20, and hub bubbles 55 are formed near the hub fused surface 49 of the housing portion 41. The bubbles are generated by evaporation of the material, mixing of air, and the like. The shaft fused surface 26 and the hub fused surface 49 are formed by the formation of the shaft bubbles 32 and the hub bubbles 55, which have unevenness and are mixed in a complex manner and penetrate into each other. Therefore, the hub 40 and the shaft 20 are fixed with a high bonding force. The hub fused surface 49 and the shaft fused surface 26 may be mixed together to form an integrated structure. Note that only one of the shaft bubbles 32 or the hub bubbles 55 may be formed. Even in this case, the hub fused surface 49 and the shaft fused surface 26 are mixed in a complex manner and are formed by being mixed into each other. Therefore, the hub 40 and the shaft 20 are fixed with a high bonding force.

[0041] The hub separating surface 50 located at the tip of the hub fusion surface 49 is not fused to the shaft separating surface 27, and a gap is maintained between the hub separating surface 27 and the shaft fusion surface 27. When the entire hub fusion surface 49 located on the base end side of the hub separating surface 50 is fused to the shaft fusion surface 26, the irradiation of the infrared laser L is stopped. This completes the fixing of the hub 40 and the shaft 20.

[0042] As described above, the catheter 10 of this embodiment is a tubular body in which a lumen 21 is formed that connects from the tip to the base end, and the catheter 10 has a shaft 20 that has a shaft base end surface 24 where the lumen 21 opens and a shaft outer surface 22 that is the outer peripheral surface of the tubular body, and a hub 40 attached to the base end of the shaft 20, the hub 40 has a cylindrical accommodating portion 41 that accommodates the shaft 20, the accommodating portion 41 has a hub fused surface 49 that is directly fused to the shaft outer surface 22, and at least one of the accommodating portion 41 or the hub 40 has a plurality of air bubbles formed in a position close to the hub fused surface 49.

[0043] In the catheter 10 configured as described above, the housing 41 and the hub 40 are fused together by a plurality of air bubbles so that they penetrate into each other. This allows the shaft 20 and the hub 40 to be firmly fixed together. This prevents the shaft 20 from coming off the hub 40 in cases where a high pressure of the contrast medium injected into the catheter 10 acts on the inside of the catheter 10 or where a tensile force acts between the hub 40 and the shaft 20 when the shaft 20 is pulled out of the body.

[0044] Additionally, in the housing portion 41, a plurality of hub bubbles 55 are formed in a position close to the hub fusion surface 49. As a result, the hub fusion surface 49 of the housing portion 41 has a complex shape having projections and recesses and is fused to the shaft outer surface 22. This allows the shaft 20 and the hub 40 to be firmly fixed together.

[0045] Furthermore, in the shaft 20, a plurality of shaft bubbles 32 are formed in the shaft outer surface 22, which is fused to the hub fused surface 49, at positions adjacent to the shaft fused surface 26. As a result, the shaft outer surface 22 is fused to the hub fused surface 49 with a complex shape having projections and recesses. This allows the shaft 20 and the hub 40 to be firmly fixed together.

[0046] In addition, both the hub 40 and the shaft 20 have a plurality of bubbles, and the hub fusion surface 49 and the shaft fusion surface 26 of the shaft outer surface 22 fused to the hub fusion surface 49 are fused to each other with unevenness, so that they fit into each other. This allows the shaft 20 and the hub 40 to be fixed even more firmly.

[0047] The present invention is not limited to the above-described embodiment, and various modifications can be made by those skilled in the art within the technical spirit of the present invention. For example, the shaft 20 may be heated by high-frequency induction heating, which utilizes electromagnetic induction to heat the shaft. The conductor that is electromagnetically induced is, for example, the reinforcing member 30.

[0048] This application is based on Japanese Patent Application No. 2020-95666 filed on June 1, 2020, the disclosures of which are hereby incorporated by reference in their entirety. [Explanation of symbols]

[0049] 10 Catheter 20 Shaft 21 Lumens 22 Shaft outer surface 23 Shaft inner surface 24 Shaft base end face 25 Shaft base end outer surface 26 Shaft fusion surface 27 Shaft separation surface 28 Inner Layer 29 Outer layer 30 Reinforcement 32 Shaft bubble (bubble) 40 Hub 41 Storage unit 42 Hub body 43 Hub tip opening 44 Hub base end opening 45 Hub bore 46 Storage area 47 Adjacent Surface 48 Hub Passage 49 Hub fusion surface 50 Hub separation surface 55 Hub bubble (bubble) 60 Anti-kink protector

Claims

1. a shaft that is a tubular body having a lumen formed therein that communicates from the tip end to the base end, the shaft having a base end surface where the lumen opens and a shaft outer surface that is an outer circumferential surface of the tubular body; a hub attached to a proximal end of the shaft, The hub has a cylindrical housing portion that houses the shaft, the housing portion has a housing surface that melts and shrinks in diameter when the hub and the shaft are fused together, and an outer peripheral surface that is hardly deformed, and the housing surface has a hub fusion surface that is directly fused to the outer surface of the shaft, A catheter characterized in that a plurality of air bubbles are formed in at least one of the containing portion and the hub at a position adjacent to the hub fused surface which is different from the outer peripheral surface of the containing portion.

2. The catheter according to claim 1, wherein the containing portion has a plurality of hub bubbles formed in a position adjacent to the hub fused surface.

3. 3. The catheter according to claim 1, wherein the shaft has a plurality of shaft bubbles formed in the outer surface of the shaft that is fused to the hub fused surface at positions adjacent to the shaft fused surface.

4. The catheter according to claim 1, characterized in that both the hub and the shaft have a plurality of the air bubbles, and the hub fusion surface and the shaft fusion surface of the shaft outer surface fused to the hub fusion surface are fused to each other with unevenness so that they interdigitate with each other.

5. A shaft having a tubular body with a lumen formed therein that communicates from the tip to the base end, the shaft having a base end surface where the lumen opens and a shaft outer surface which is the outer peripheral surface of the tubular body; a hub attached to a proximal end of the shaft, The hub has a cylindrical housing portion that houses the shaft, The housing portion has a hub fusion surface that is directly fused to the shaft outer surface, A catheter characterized in that a plurality of bubbles are formed as shaft bubbles only in the shaft at a position adjacent to the hub fused surface.

6. A shaft having a tubular body with a lumen formed therein that communicates from the tip to the base end, the shaft having a base end surface where the lumen opens and a shaft outer surface which is the outer peripheral surface of the tubular body; a hub attached to a proximal end of the shaft, The hub has a cylindrical housing portion that houses the shaft, The housing portion has a hub fusion surface that is directly fused to the shaft outer surface, A catheter characterized in that a plurality of bubbles are formed as hub bubbles only in the hub at a position adjacent to the hub fused surface.

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