Catheter and manufacturing method thereof

Abstract

This catheter has a cylindrical tip member continuing from a tip of a catheter body. A bent part of the tip member, which is a portion fixing the tip of the catheter body and bending when an external force in a bending direction is applied to the tip of the catheter member, is positioned more on the tip side than the most tip part of the catheter body. The catheter has the cylindrical tip member continuing from the tip of the catheter body, and the Young's modulus of the bent part of the tip member, which is the portion fixing the tip of the catheter body and bending when an external force in the bending direction is applied to the tip of the catheter member, is lower than the Young's modulus of a base end of the tip member. This method for manufacturing the catheter has a heat treatment step for performing a heat treatment to fuse a base end of a cylindrical tip member to a catheter body while suppressing the thermal load to an axial direction intermediate part of the tip member more than the thermal load to the base end.

Description

[Technical Field]

[0001] The present disclosure relates to catheters and methods of manufacturing the same. [Background technology]

[0002] Catheters such as balloon catheters, microcatheters, and guiding catheters have a cylindrical tip member that is connected to the tip of the catheter body (for example, at least one of the inner tube of the shaft and the balloon in the case of a balloon catheter) and through which a guidewire passes (see, for example, Patent Document 1). The tip member is more flexible than the tip of the catheter body and has the ability to deform to follow the shape of the guidewire so that it can reach the target position along the guidewire within the body cavity without getting caught on obstacles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-56148 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional catheters, the distal end of the catheter body is fixed, and the bending portion of the distal end member, which is the portion that bends when an external force in the bending direction is applied to the distal end of the distal end member, is located at the very tip of the catheter body. As a result, there is room for improvement in the followability of the distal end member relative to the guidewire.

[0005] An object of the present disclosure is to provide a catheter capable of realizing high followability of a tip member relative to a guide wire, and a method for manufacturing the same. [Means for solving the problem]

[0006] A catheter according to a first aspect of the present disclosure has a tubular tip member connected to the tip of a catheter body, and the bending portion of the tip member, which is the portion that bends when the tip of the catheter body is fixed and an external force in a bending direction is applied to the tip of the tip member, is located further distal than the most distal end of the catheter body.

[0007] In one embodiment of the present disclosure, the catheter has a tapered tip portion of the tip member.

[0008] In one embodiment of the present disclosure, the catheter has the tip member formed of a thermoplastic resin.

[0009] In one embodiment of the present disclosure, the catheter has a tip member made of at least one thermoplastic resin layer.

[0010] In one embodiment of the present disclosure, the catheter has a Young's modulus of the bending portion smaller than a Young's modulus of the proximal end portion of the tip member.

[0011] A catheter according to a second aspect of the present disclosure has a tubular tip member connected to the tip of a catheter body, and the Young's modulus of the bending portion of the tip member, which is the portion that bends when the tip of the catheter body is fixed and an external force in a bending direction is applied to the tip of the tip member, is smaller than the Young's modulus of the base end of the tip member.

[0012] In one embodiment of the present disclosure, the catheter has a Young's modulus of the bending portion of the tip member that is smaller than the Young's modulus of the tip portion of the tip member.

[0013] A catheter manufacturing method according to a third aspect of the present disclosure includes a heat treatment step for fusing the base end of a tubular tip member to the catheter body while suppressing the thermal load on the axial middle portion of the tip member relative to the thermal load on the base end.

[0014] In one embodiment of the present disclosure, in the method for manufacturing a catheter, the heat treatment step includes a heat transfer step of transferring heat to the base end portion via a tubular heat transfer portion that shrinks due to heat.

[0015] As one embodiment of the present disclosure, in the method for manufacturing a catheter, the heat transfer portion absorbs radiation and generates heat.

[0016] As one embodiment of the present disclosure, the method for manufacturing the catheter includes a tip processing step in which the heat treatment step applies a thermal load to the tip portion of the tip member that is greater than the thermal load applied to the axial intermediate portion of the tip member. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a catheter capable of realizing high followability of a distal end member relative to a guide wire, and a method for manufacturing the same. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an external view showing a catheter according to an embodiment. FIG. [Figure 2] FIG. 2 is a longitudinal cross-sectional view showing the distal end of the catheter shown in FIG. 1. [Figure 3] FIG. 3 is a partially enlarged view of FIG. 2. [Figure 4] FIG. 2 is a schematic diagram showing an example of a bending test for confirming the position of a bent portion of the distal end member of the catheter shown in FIG. [Figure 5] 5 is a schematic diagram showing a state of a bent portion when bent by the bending test shown in FIG. 4. FIG. [Figure 6] FIG. 5 is a schematic diagram showing the state of the bending portion of the tip member of a catheter as a comparative example when bent in the bending test shown in FIG. 4. [Figure 7] FIG. 2 is a schematic diagram showing a member for heat treatment used to manufacture the catheter shown in FIG. [Figure 8] FIG. 10 is a partially enlarged view of a catheter according to another embodiment. [Figure 9]9 is a schematic diagram showing the state of the bending portion of the catheter shown in FIG. 8 when bent in the bending test shown in FIG. 4. FIG. [Figure 10] FIG. 5 is a schematic diagram showing the state of the bending portion of the tip member of a catheter as a comparative example when bent in the bending test shown in FIG. 4. [Figure 11] FIG. 10 is a partially enlarged view of a catheter according to another embodiment. [Figure 12] FIG. 10 is a partially enlarged view of a catheter according to another embodiment. [Figure 13] FIG. 10 is a partially enlarged view of a catheter according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a catheter and a method for manufacturing the same according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0020] 1 to 3, a catheter 1 according to this embodiment has a cylindrical distal end member 2 extending along a central axis O, and a catheter main body 3 with a distal end portion 3a connected to the proximal end portion 2a of the distal end member 2. The catheter main body 3 has an elongated shaft portion 4 that is coaxial with the distal end member 2 and has a distal end portion 4a connected to the proximal end portion 2a of the distal end member 2, and a hub 5 with a distal end portion connected to the proximal end portion of the shaft portion 4. The distal end member 2 and the shaft portion 4 are flexible, which allows them to be inserted along a curved guidewire 6 into a lumen such as a vascular passageway or blood vessel in a living body such as a human body, i.e., into a body cavity.

[0021] In this specification, the direction along the central axis O of the tip member 2 is referred to as the axial direction, the direction along a line perpendicular to the central axis O is referred to as the radial direction, the direction circumferentially around the central axis O is referred to as the circumferential direction, a cross section including the central axis O is referred to as a longitudinal cross section, the end that is inserted into the body cavity during treatment is referred to as the tip, and the opposite end, i.e., the end closer to the practitioner, is referred to as the base end.

[0022] The shaft portion 4 is composed of an outer tube 7, an inner tube 8, and a balloon 9. In other words, the catheter 1 is a balloon catheter. However, the catheter 1 is not limited to a balloon catheter, and may be, for example, a microcatheter or a guiding catheter.

[0023] The outer tube 7 has a long cylindrical shape extending in the axial direction. The proximal end of the outer tube 7 is connected to the distal end of the hub 5. The distal end of the outer tube 7 is connected to the proximal end of the balloon 9.

[0024] The balloon 9 has a distal end and a proximal end each having a cylindrical shape extending in the axial direction, and an axially intermediate portion therebetween, which constitutes a cylindrical balloon body 9a expanded in the radial direction. In Figures 1 to 3, the balloon body 9a is shown in a deployed state expanded in the radial direction. Before deployment, the balloon body 9a is in a non-deployed state, folded so that its outer diameter is the same as that of the outer tube 7. The distal end of the balloon 9 is continuous with the distal end of the inner tube 8. More specifically, the inner circumferential surface of the distal end of the balloon 9 is joined to the outer circumferential surface of the distal end of the inner tube 8, for example, by fusion bonding.

[0025] The inner tube 8 has a long cylindrical shape. The most distal end of the inner tube 8 is located closer to the distal end than the most distal end of the balloon 9. The distal end and axially intermediate portion of the inner tube 8 extend in the axial direction. The base end of the inner tube 8 extends radially outward, inclining toward the base end. The most proximal end of the inner tube 8 is joined to the outer peripheral edge of an oval cutout provided in the peripheral surface of the outer tube 7 so as to be in close contact with the entire circumference.

[0026] A communication passage that communicates with the inner cavity of the balloon body 9a is formed between the outer tube 7 and the inner tube 8. By sending a fluid through this communication passage into the inner cavity of the balloon body 9a, the balloon body 9a can be transitioned from the undeployed configuration to the deployed configuration.

[0027] The base end 2a of the tip member 2 is joined by fusion to the tip end 4a of the shaft 4 of the catheter main body 3. More specifically, the inner circumferential surface of the base end 2a of the tip member 2 is joined by fusion to the outer circumferential surface of the tip end of the inner tube 8, and the base end of the base end 2a of the tip member 2 is joined to the tip of the tip end of the balloon 9 by fusion.

[0028] During treatment, the guide wire 6 is passed through the lumen of the distal end member 2 and the inner tube 8. The catheter 1 is a rapid exchange (RX) type in which the base end of the lumen through which the guide wire 6 passes is located at the axially intermediate portion of the shaft portion 4. However, the catheter 1 is not limited to the RX type, and may be, for example, an over-the-wire (OTW) type.

[0029] The outer tube 7, inner tube 8 and balloon 9 can each be formed from a polymeric material such as polyolefin (e.g., polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of two or more of these), polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, fluororesin, or a mixture of two or more of these.

[0030] The outer tube 7, the inner tube 8, and the balloon 9 may each have a single-layer structure or a multi-layer structure. The outer tube 7, the inner tube 8, and the balloon 9 may each have a structure in which the same type of material is connected over the entire length in the axial direction, or a structure in which different types of materials are connected in the axial direction.

[0031] At least the fused portion of the shaft portion 4 to the tip member 2 and the tip member 2 are made of a thermoplastic resin such as a polyamide or polyolefin. The tip member 2 is made of only one thermoplastic resin layer. However, the tip member 2 is not limited to this, and may be made of only two or more thermoplastic resin layers, or may have layers other than the thermoplastic resin layer.

[0032] The tip member 2 has, for example, an inner diameter of 0.42 mm and an outer diameter of 0.56 mm. The tip member 2 can be made of, for example, polyamide elastomer (Grilamid ELG5660 manufactured by EMS).

[0033] The tip portion 2b of the tip member 2 is tapered. More specifically, the outer circumferential surface of the tip portion 2b of the tip member 2 is a linearly inclined surface that slopes radially inward toward the tip side in a vertical cross section. However, the outer circumferential surface of the tapered tip portion 2b of the tip member 2 is not limited to this, and may be, for example, an R-surface that forms a curved line shape such as an arc in a vertical cross section. The tip portion 2b of the tip member 2 is not limited to being tapered.

[0034] The axially intermediate section 2c of the tip member 2, which is the section connecting the tip section 2b and the base section 2a, has a bending section 10 that bends (i.e., folds) when the tip section 3a of the catheter main body 3 is fixed and an external force F (see Figure 4) in a bending direction is applied to the tip section 2b of the tip member 2. In this way, the bending section 10 of the tip member 2 is located further distal than the most distal section 3b of the catheter main body 3 (i.e., the most distal section of the inner tube 8).

[0035] The position of the bent portion 10 can be confirmed, for example, by a bending test, as shown in Figures 4 and 5. In this bending test, a test device 11 is used, which includes a gripping portion 11a that grips the distal end 3a of the catheter main body 3, a contact surface 11b against which the most distal end 2d of the tip-end member 2 contacts, and a driving portion 11c that moves the gripping portion 11a relatively toward the contact surface 11b at a predetermined speed. This test device 11 can fix the distal end 3a of the catheter main body 3 and apply an external force F in the bending direction to the distal end 2b of the tip-end member 2. The external force F is the radially inward component of the reaction force F' from the contact surface 11b. The test device 11 is, for example, a microautograph in which the gripping portion 11a is composed of a chuck and the driving portion 11c is composed of a load cell. The contact surface 11b is made of, for example, silicone rubber.

[0036] As a test method, for example, as shown in Figure 4, the angle θ at which the central axis O of the tip member 2 is inclined with respect to the contact surface 11b is set to 60 to 80 degrees, and the gripping portion 11a is moved toward the contact surface 11b at a relative speed of 2 mm / min.

[0037] From such a test, the bent portion is the bent portion 10 as shown in Figure 5. Because the Young's modulus of the bent portion 10 is smaller than that of the base end 2a of the tip member 2, the bent portion 10 is located more distal than the most distal portion 3b of the catheter main body 3. In contrast to this embodiment, in the case of a comparative example in which the Young's modulus of the tip member 2 is constant over the entire axial length, the bent portion 10 is located at the most distal portion 3b of the catheter main body 3 as shown in Figure 6. Alternatively, the bent portion 10 is not formed, and the tip member 2 buckles in an accordion-like manner over the entire axial length.

[0038] The bending section 10 of this embodiment can be formed by a heat treatment step in which the base end 2a of the tip member 2 is fused to the catheter body 3 while suppressing the thermal load on the axial intermediate section 2c of the tip member 2 compared to the thermal load on the base end 2a of the tip member 2. In other words, the manufacturing method of the catheter according to this embodiment includes such a heat treatment step.

[0039] The heat treatment step includes a tip processing step of applying a thermal load to the tip portion 2b of the tip member 2 that is greater than the thermal load applied to the axially intermediate portion 2c of the tip member 2. The tip portion 2b of the tip member 2 is formed into a tapered shape by the tip processing step.

[0040] The heat treatment process also includes a heat transfer process in which heat is transferred to the base end 2a of the tip member 2 via a cylindrical first heat transfer part 12 that shrinks due to heat, and to the tip end 2b of the tip member 2 via a cylindrical second heat transfer part 13 that shrinks due to heat (see FIG. 7). This heat transfer process allows a heat load greater than the heat load applied to the axial intermediate part 2c of the tip member 2 to be applied to the base end 2a and the tip end 2b of the tip member 2. In the heat treatment process, mandrels corresponding to the lumens of the tip member 2 and the catheter main body 3 are inserted in advance. In this embodiment, mandrels with outer diameters corresponding to the diameters of the respective lumens are used.

[0041] By suppressing the thermal load on the axial intermediate portion 2c of the tip member 2, it is possible to suppress the thermoplastic resin forming the axial intermediate portion 2c of the tip member 2 from melting and hardening again, changing its composition and becoming harder than before it was melted. In other words, it is possible to suppress the reduction in flexibility (i.e., increase in Young's modulus) of the axial intermediate portion 2c of the tip member 2 due to the thermal load.

[0042] The first heat transfer part 12 absorbs the radiant rays, generates heat, and contracts, thereby transferring heat by contacting the outer peripheral surface of the base end part 2a of the tip member 2. The second heat transfer part 13 absorbs the radiant rays, generates heat, and contracts, thereby transferring heat by contacting the outer peripheral surface of the tip part 2b of the tip member 2.

[0043] The first heat transfer section 12 and the second heat transfer section 13 are each made of, for example, a colored tube, such as black, that easily absorbs laser radiation. The first heat transfer section 12 and the second heat transfer section 13 are connected via a connecting section 14, which is made of, for example, a transparent tube that does not easily absorb laser radiation. Alternatively, the first heat transfer section 12 and the second heat transfer section 13 are arranged separately from each other.

[0044] The tip member 2 itself can be formed by general extrusion molding including coating molding. However, the manufacturing method of the tip member 2 itself is not limited to this. The manufacturing method of the inner tube 8 etc. is not particularly limited either.

[0045] In the catheter 1 of the present embodiment described above, the bending portion 10 of the tip member 2 is located further distal than the most distal portion 3b of the catheter body 3, so that the tip member 2 can easily flexibly deform into a shape that conforms to the curved guide wire 6 during treatment, thereby achieving high followability of the tip member 2 to the guide wire 6.

[0046] Furthermore, in the catheter 1 of this embodiment, the tip portion 2b of the tip member 2 is tapered, which improves the passability for advancing within the body cavity along the guide wire 6 during treatment, and also prevents the tip portion 2b of the tip member 2 from becoming deformed by being turned up.

[0047] In the catheter 1 of this embodiment, the tip member 2 is formed from a thermoplastic resin, so that the tip member 2 can be easily joined to the catheter body 3 by fusion bonding.

[0048] In the catheter 1 of this embodiment, the tip member 2 is composed of only at least one thermoplastic resin layer, so that the heat treatment for fusing the tip member 2 to the catheter body 3 can be performed while suppressing the thermal load on the axial middle portion 2c of the tip member 2 compared to the thermal load on the base end portion 2a of the tip member 2, thereby making it possible to easily form the curved portion 10 of the tip member 2.

[0049] In the catheter 1 of this embodiment, the Young's modulus of the bending portion 10 is smaller than the Young's modulus of the base end portion 2a of the distal end member 2, so that the bending portion 10 can be formed with a simple structure.

[0050] Furthermore, the manufacturing method of the catheter of this embodiment can form a curved portion 10 located further distal than the most distal end portion 3b of the catheter body 3 in the tip member 2 through a heat treatment process, thereby realizing high followability of the tip member 2 to the guide wire 6.

[0051] In the method for manufacturing a catheter of this embodiment, the heat treatment step includes a heat transfer step, so that the heat treatment step can be carried out easily.

[0052] In the method for manufacturing the catheter of this embodiment, the first heat transfer section 12 and the second heat transfer section 13 each absorb radiant rays and generate heat, so that the heat transfer step can be carried out easily.

[0053] In the method for manufacturing the catheter of this embodiment, the heat treatment step includes a tip treatment step, so that the tip portion 2b of the tip member 2 can be easily formed into a tapered shape.

[0054] The above-described embodiment is merely an example of the present disclosure, and various modifications are possible, for example, as described below.

[0055] For example, the catheter 1 has a cylindrical tip member 2 connected to the tip portion 3a of the catheter main body 3, and various modifications are possible as long as the bending portion 10 of the tip member 2, which is the part that bends when the tip portion 3a of the catheter main body 3 is fixed and an external force F in the bending direction is applied to the tip portion 2b of the tip member 2, is located further forward than the most distal portion 3b of the catheter main body 3.

[0056] However, it is preferable that the tip portion 2b of the tip member 2 is tapered.

[0057] Moreover, the tip member 2 is preferably made of a thermoplastic resin.

[0058] The tip member 2 is preferably made up of at least one thermoplastic resin layer.

[0059] The Young's modulus of the bending portion 10 is preferably smaller than the Young's modulus of the base end portion 2 a of the distal end member 2 .

[0060] Furthermore, the inner circumferential surface of the distal end portion of the balloon 9 may be joined to the outer circumferential surface of the base end portion 2a of the distal end member 2 by, for example, fusion bonding, instead of or in addition to the outer circumferential surface of the distal end portion of the inner tube 8.

[0061] Alternatively, the catheter 1 has a cylindrical tip member 2 connected to the tip portion 3a of the catheter main body 3, and can be modified in various ways as long as the Young's modulus of the bending portion 10 of the tip member 2, which is the part that bends when the tip portion 3a of the catheter main body 3 is fixed and an external force F in the bending direction is applied to the tip portion 2b of the tip member 2, is smaller than the Young's modulus of the base end portion 2a of the tip member 2.

[0062] The manufacturing method of the catheter can be modified in various ways as long as it includes a heat treatment step in which the base end 2a of the tubular tip member 2 is fused to the catheter body 3 while suppressing the thermal load on the axial middle portion 2c of the tip member 2 compared to the thermal load on the base end 2a of the tip member 2.

[0063] However, the heat treatment step preferably includes a heat transfer step of transferring heat to the base end portion 2a of the tip member 2 via the cylindrical first heat transfer portion 12 that shrinks due to heat.

[0064] Moreover, it is preferable that the first heat transfer portion 12 absorbs radiant rays and generates heat.

[0065] The heat treatment step preferably includes a tip treatment step of applying a thermal load to the tip portion 2b of the tip member 2 that is greater than the thermal load applied to the axially intermediate portion 2c of the tip member 2.

[0066] Next, a catheter 100 according to another embodiment will be described with reference to Fig. 8, which is a partially enlarged view. Note that components common to Figs. 1 and 2 are designated by the same reference numerals as in Figs. 1 and 2, and descriptions thereof will be omitted as they are the same.

[0067] 8, a catheter 100 according to another embodiment has a cylindrical distal end member 102 extending along a central axis O, and a catheter main body 103 having a distal end portion 103a connected to the proximal end portion 102a of the distal end member 102. The catheter main body 103 has an elongated shaft portion 104 having the distal end portion 103a connected to the proximal end portion 102a of the distal end member 102 and coaxial with the distal end member 102, and a hub 5 having a distal end portion connected to the proximal end portion of the shaft portion 104. The distal end member 102 and the shaft portion 104 are flexible, allowing them to be inserted along a curved guidewire 6 into a lumen such as a vasculature, such as a blood vessel, in a living body such as a human body, i.e., a body cavity.

[0068] The balloon 109 has a distal end 109b and a proximal end each having a cylindrical shape extending in the axial direction, and an axially intermediate portion therebetween, which constitutes a cylindrical balloon body 109a expanded in the radial direction. In FIG. 8, the balloon body 109a is shown in a deployed state expanded in the radial direction. Before deployment, the balloon body 109a is in a folded, undeployed state so that its outer diameter is the same as that of the outer tube 7. The distal end 109b of the balloon 109 is disposed across the distal end of the inner tube 108 (the distal end 103a of the catheter body 103) and the proximal end 102a of the tip member 102. More specifically, the inner circumferential surface of the distal end 109b of the balloon 109 is joined to the outer circumferential surface of the distal end 103a of the catheter body 103 by fusion bonding.

[0069] The inner tube 108 has a long cylindrical shape. The most distal end of the inner tube 108, that is, the most distal end 103b of the catheter body 103, is located closer to the proximal end than the most distal end 109d of the balloon 109.

[0070] The proximal end 102a of the tip member 102 is joined by fusion to the distal end 104a of the shaft 104 of the catheter main body 103. More specifically, the proximal end surface of the proximal end 102a of the tip member 102 is joined by fusion to the distal end surface of the most distal end 103b of the catheter main body 103. The tip member 102 and the catheter main body 103 share a central axis O, and the inner surfaces of the tip member 102 and the catheter main body 103 are continuous with no steps and have a substantially uniform inner diameter.

[0071] The layer structure and materials of the distal end member 102, inner tube 108 and balloon 109 can be the same as those of the previous embodiment.

[0072] The axially intermediate section 102c of the tip member 102, which is a section connecting the tip section 102b and the base section 102a, has a bending section 110 which is a section that bends (i.e., folds) when the tip section 103a of the catheter main body 103 is fixed and an external force F (see FIG. 4) in the bending direction is applied to the tip section 102b of the tip member 102. As described above, the bending section 110 of the tip member 102 is located more distally than the most distal section 103b of the catheter main body 103 (i.e., the most distal section of the inner tube 108). The bending section 110 is located more distally than the base section 102a of the tip member 102. The bending section 110 is located more distally than the most distal section 109d of the balloon 109. The bending section 110 of the tip member 102 is located more proximal than the tip section 102b of the tip member 102.

[0073] The position of the bent portion 110 can be confirmed, for example, by a bending test shown as an example in FIGS. 9 and 10. The test described with reference to FIG. 4 determined that the bent portion 110 is the bent portion as shown in FIG. 9. Because the Young's modulus of the bent portion 110 is smaller than that of the proximal end 102a of the distal end member 102, the bent portion 110 is located distal to the most distal end 103b of the catheter main body 103. More specifically, the bent portion 110 is located distal to the proximal end 102a, which is closer to the distal end than the most distal end 109d of the balloon 109. In the comparative example in which the Young's modulus of the distal end member 102 is constant over the entire axial length, in contrast to this embodiment, the bent portion 110 is located distal to the proximal end 102a of the distal end member 102, more specifically, at the proximal end 102a closer to the distal end than the most distal end 109d of the balloon 109, as shown in FIG. 10. Alternatively, the bent portion 110 is not formed, and the distal end member 102 buckles in a bellows-like manner over the entire axial length.

[0074] The bending portion 110 of this embodiment can be formed by a heat treatment process in which the base end 102a of the tip member 102 is fused to the catheter body 103 while suppressing the heat load on the axial middle portion 102c of the tip member 102 compared to the heat load on the base end 102a of the tip member 102.

[0075] The heat treatment process includes a tip processing step of applying a thermal load to the tip portion 102b of the tip member 102 that is greater than the thermal load applied to the axially intermediate portion 102c of the tip member 102. The tip portion 102b of the tip member 102 is formed into a tapered shape by the tip processing step. The tip portion 102b may also be formed into a rounded shape by the tip processing step.

[0076] The heat treatment process also includes a heat transfer process in which heat is transferred to the base end 102a of the tip member 102 via a cylindrical first heat transfer part 12 that shrinks due to heat, and to the tip end 102b of the tip member 102 via a cylindrical second heat transfer part 13 that shrinks due to heat (see FIG. 7). By such a heat transfer process, a heat load greater than the heat load applied to the axial intermediate part 102c of the tip member 102 can be applied to the base end 102a and the tip end 102b of the tip member 102.

[0077] By suppressing the thermal load on the axial intermediate portion 102c of the tip member 102, it is possible to suppress the thermoplastic resin forming the axial intermediate portion 102c of the tip member 102 from melting and hardening again, changing its composition and becoming harder than before it was melted. In other words, it is possible to suppress the reduction in flexibility (i.e., increase in Young's modulus) of the axial intermediate portion 102c of the tip member 102 due to the thermal load.

[0078] The heat treatment process applies heat transfer and a heat-induced contraction force to the balloon tip portion 109b via the first heat transfer portion 12. As a result, the balloon tip portion 109b is fused to the base end portion 102a of the tip member 102 and the tip portion 103a of the catheter body 103. The materials of the balloon tip portion 109b, base end portion 102a, and tip portion 103a melt to form a fused solid. The balloon tip portion 109b forms a structure in which its thickness gradually decreases toward the tip end 109d due to the contraction force of the molten material caused by heat transfer from the first heat transfer portion 12.

[0079] Next, a catheter 200 according to another embodiment will be described with reference to Fig. 11, which is a partially enlarged view. Note that components common to Figs. 1 and 2 are designated by the same reference numerals as in Figs. 1 and 2, and descriptions thereof will be omitted as they are the same.

[0080] 11 , a catheter 200 according to another embodiment has a cylindrical distal end member 202 extending along a central axis O, and a catheter main body 203 having a distal end portion 203a located on the proximal side of the proximal end portion 202a of the distal end member 202. The catheter main body 203 has a long shaft portion 204 that is coaxial with the distal end member 202 and has the distal end portion 203a separated from the proximal end portion 202a of the distal end member 202 by a gap, and a hub 5 that has a distal end portion connected to the proximal end portion of the shaft portion 204.

[0081] The balloon 209 has a distal end 209b and a proximal end each having a cylindrical shape extending in the axial direction, and the axially intermediate portion between them constitutes a cylindrical balloon main body 209a that expands radially. The distal end 209b of the balloon 209 covers the distal end of the inner tube 208 (the distal end 203a of the catheter main body 203). The distal end 209b extends beyond the most distal end 203b toward the distal side via an inclined portion 209e. The inclined portion 209e tapers in diameter toward the distal end. The distal end surface of the most distal end portion 209d of the balloon 209 is joined to the proximal end surface of the proximal end 202a of the distal end member 202 by fusion welding.

[0082] The tip member 202 has a two-layer structure consisting of an inner layer 211 and an outer layer 212. The inner layer 211 is made of a harder material than the outer layer 212. A material can be selected that is less likely to soften when inserted into the body and that prevents a decrease in the slidability of the guide wire. One example of such a material is high-density polyethylene. The outer layer 212 is made of a material that is more flexible than the inner layer 211, thereby preventing damage to living tissue such as blood vessels. One example of such a material is a polyamide elastomer. The tip member 202 may have a three-layer structure with an intermediate layer between the inner layer 211 and the outer layer 212. The tip member 202 may be a single layer. In the case of a single layer, the material used for the inner layer 211 can be used.

[0083] The layer structure and materials of the inner tube 208 and the balloon 209 can be the same as those in the above-described embodiment.

[0084] The axially intermediate portion 202c of the distal end member 202, which is a portion connecting the distal end portion 202b and the proximal end portion 202a, has a bending portion 210 which is a portion that bends (i.e., folds) when the proximal end portion 202a is fixed and an external force F (see FIG. 4) in the bending direction is applied to the distal end portion 202b of the distal end member 202. As such, the bending portion 210 of the distal end member 202 is located more distally than the most distal end portion 203b of the catheter main body 203 (i.e., the most distal end of the inner tube 208). The bending portion 210 of the distal end member 202 is located more distally than the proximal end portion 202a of the distal end member 202. The bending portion 210 of the distal end member 202 is located more proximal than the distal end portion 202b of the distal end member 202.

[0085] The bending portion 210 of this embodiment can be formed by a heat treatment process in which the base end 202a of the tip member 202 is fused to the tip end 209b of the balloon 209 while suppressing the heat load on the axial middle portion 202c of the tip member 202 compared to the heat load on the base end 202a of the tip member 202.

[0086] The heat treatment process includes a tip processing step of applying a thermal load to the tip portion 202b of the tip member 202 that is greater than the thermal load applied to the axially intermediate portion 202c of the tip member 202. The tip portion 202b of the tip member 202 is formed into a tapered shape by the tip processing step. The tip portion 202b may also be formed into a rounded shape by the tip processing step.

[0087] The heat treatment step also includes a heat transfer step of transferring heat to the base end 202a of the tip member 202 via a cylindrical first heat transfer part 12 that shrinks due to heat, and transferring heat to the tip end 202b of the tip member 202 via a cylindrical second heat transfer part 13 that shrinks due to heat (see FIG. 7). By such a heat transfer step, a heat load greater than the heat load applied to the axial intermediate part 202c of the tip member 202 can be applied to the base end 202a and the tip end 202b of the tip member 202.

[0088] In the heat treatment step, heat is transferred to the balloon tip portion 209b via the first heat transfer section 12, and a heat-induced contraction force is applied to the balloon tip portion 209b. As a result, the balloon tip portion 209b is fused to the tip portion 203a of the catheter body 203. The materials of the balloon tip portion 209b and the tip portion 203a melt to form a fused solid.

[0089] Next, a catheter 300 according to another embodiment will be described with reference to Fig. 12, which is a partially enlarged view. Note that components common to Figs. 1 and 2 are designated by the same reference numerals as in Figs. 1 and 2, and descriptions thereof will be omitted as they are the same.

[0090] 12, a catheter 300 according to another embodiment has a cylindrical tip member 302 extending along a central axis O and a catheter main body 303 with a tip section 303a located between a proximal end 302a and a distal end 302b of the tip member 302. The tip member 302 has a catheter main body covering section 322 that covers the distal end 303a of the catheter main body 303 and fixes it thereto by fusion, and a balloon tip covering section 332 that continues from the catheter main body covering section 322 and covers at least a portion of the distal end 309b of the balloon 309 and fixes it thereto by fusion. The outer diameter of the balloon tip covering section 332 is larger than the outer diameter of the catheter main body covering section 322. The balloon tip covering section 332 continues to the catheter main body covering section 322 via a tapered transition section.

[0091] The balloon 309 has a cylindrical distal end 309b and a proximal end each extending in the axial direction, and the axially intermediate portion between them constitutes a cylindrical balloon body 309a that expands radially. The distal end 309b of the balloon 309 is joined to the distal end of the inner tube 308 (the distal end 303a of the catheter body 303) by fusion welding. At least a portion of the distal end 309b of the balloon 309 is disposed so as to be sandwiched between the proximal end 302a of the tip member 302 and the catheter body 303.

[0092] The tip member 302 has a two-layer structure consisting of an inner layer 311 and an outer layer 312. The materials for each layer can be those used in the previous embodiments. For the inner layer 311, a material that is highly compatible with the material that forms the outer surface of the catheter body 303 and / or the material that forms the inner surface of the tip portion 309b of the balloon 309 can be suitably selected. The tip member 302 may have a three-layer structure with an intermediate layer between the inner layer 311 and the outer layer 312. The tip member 302 may be a single layer. In the case of a single layer, the material used for the inner layer 311 can be used.

[0093] The axially intermediate section 302c of the tip member 302, which is a continuous section from the tip section 302b to the most distal section 303b of the catheter main body 303, has a bending section 310 that bends (i.e., folds) when the tip section 303a of the catheter main body 303 is fixed and an external force F (see FIG. 4) in the bending direction is applied to the tip section 302b of the tip member 302. As such, the bending section 310 of the tip member 302 is located more distally than the most distal section 303b of the catheter main body 303 (i.e., the most distal section of the inner tube 308). The bending section 310 of the tip member 302 is located more proximal than the tip section 302b of the tip member 302.

[0094] The bending portion 310 of this embodiment can be formed by a heat treatment process in which the base end 302a of the tip member 302 is fused to the tip portion 303a of the catheter body 303 and the tip portion 309b of the balloon 309 while suppressing the heat load on the axial middle portion 302c of the tip member 302 compared to the heat load on the base end 302a of the tip member 302.

[0095] The heat treatment process includes a tip processing step of applying a thermal load to the tip portion 302b of the tip member 302 that is greater than the thermal load applied to the axially intermediate portion 302c of the tip member 302. The tip portion 302b of the tip member 302 is formed into a rounded shape by the tip processing step. The tip portion 302b may also be formed into a tapered shape by the tip processing step.

[0096] The heat treatment process also includes a heat transfer process in which heat is transferred to the base end 302a of the tip member 302 via a cylindrical first heat transfer part 12 that shrinks due to heat, and to the tip end 302b of the tip member 302 via a cylindrical second heat transfer part 13 that shrinks due to heat (see FIG. 7). By such a heat transfer process, a heat load greater than the heat load applied to the axial intermediate part 302c of the tip member 302 can be applied to the base end 302a and the tip end 302b of the tip member 302.

[0097] In the heat treatment step, heat is transferred to the proximal end 302a of the distal end member 302 via the first heat transfer section 12, and a heat-induced contraction force is applied to the proximal end 302a of the distal end member 302. As a result, the proximal end 302a of the distal end member 302 is individually fused to the balloon distal end 309b and the catheter main body distal end 303a.

[0098] Next, a catheter 400 according to another embodiment will be described with reference to Fig. 13, which is a partially enlarged view. Note that components common to Figs. 1 and 2 are designated by the same reference numerals as in Figs. 1 and 2, and descriptions thereof will be omitted as they are the same.

[0099] 13, a catheter 400 according to another embodiment has a cylindrical distal end member 402 extending along a central axis O, and a catheter main body 403 with a most distal portion 403b located between a proximal end 402a and a distal end 402b of the distal end member 402. The distal end 403a of the catheter main body 403 has a portion with a narrow outer diameter at a step 413, and terminates at the most distal portion 403b via a narrow diameter portion 403c that maintains the narrow outer diameter toward the distal end. The outer surface of the narrow diameter portion 403c is covered with and fused to the inner surface of the distal end member 402.

[0100] The balloon 409 has a distal end 409b and a proximal end each having a cylindrical shape extending in the axial direction, and the axially intermediate portion between them constitutes a cylindrical balloon main body 409a that expands in the radial direction. The distal end 409b of the balloon 409 is fused to and covers at least a portion of the proximal end 402a of the distal end member 402. The distal end 409b of the balloon 409 and the distal end 403a of the catheter main body 403 are arranged to sandwich the proximal end 402a of the distal end member 402. The outer diameter of the distal end 409b of the balloon 409 smoothly and without any steps with the outer diameter of the distal end member 402.

[0101] The tip member 402 has a two-layer structure consisting of an inner layer 411 and an outer layer 412. The materials for each layer can be those used in the previous embodiments. For the inner layer 411, a material that is highly compatible with the material that constitutes the outer surface of the catheter main body 403 can be suitably selected. For the outer layer 412, a material that is highly compatible with the material that constitutes the inner surface of the tip portion 409b of the balloon 409 can be suitably selected. The tip member 402 may have a three-layer structure with an intermediate layer between the inner layer 411 and the outer layer 412. The tip member 402 may be a single layer. In the case of a single layer, the material used for the inner layer 411 can be used.

[0102] The axially intermediate section 402c of the tip member 402, which is a continuous section from the tip section 402b to the most distal section 403b of the catheter main body 403, has a bending section 410 that bends (i.e., folds) when the tip section 403a of the catheter main body 403 is fixed and an external force F (see FIG. 4) in the bending direction is applied to the tip section 402b of the tip member 402. As described above, the bending section 410 of the tip member 402 is located more distally than the most distal section 403b of the catheter main body 403 (i.e., the most distal section of the inner tube 408). The bending section 410 is located more distally than a portion 402e of the tip member 402 that is closer to the distal end than the most distal section 403b of the catheter main body 403 (i.e., the most distal section of the inner tube 408). The bending section 410 of the tip member 402 is located more proximal than the tip section 402b of the tip member 402.

[0103] The bending portion 410 of this embodiment can be formed by a heat treatment process in which the base end 402a of the tip member 402 is fused to the tip portion 403a of the catheter main body 403, and further the tip portion 409b of the balloon 409 is fused to the base end 402a of the tip member 402, while suppressing the heat load on the axial middle portion 402c of the tip member 402 compared to the heat load on the base end 402a of the tip member 402.

[0104] The heat treatment process includes a tip processing step of applying a thermal load to the tip portion 402b of the tip member 402 that is greater than the thermal load applied to the axially intermediate portion 402c of the tip member 402. The tip portion 402b of the tip member 402 is formed into a rounded shape by the tip processing step. The tip portion 402b may also be formed into a tapered shape by the tip processing step.

[0105] The heat treatment step also includes a heat transfer step of transferring heat to the tip member 402 covering the small diameter portion 403c of the catheter main body 403 and the tip portion 409b of the balloon 409 via a cylindrical first heat transfer part 12 that shrinks due to heat, and transferring heat to the tip portion 402b of the tip member 402 via a cylindrical second heat transfer part 13 that shrinks due to heat (see FIG. 7). By this heat transfer step, a larger heat load can be applied to the tip member 402 covering the tip portion 403a of the catheter main body 403 and to the tip portion 402b.

[0106] In the heat treatment step, heat is transferred to the tip member 402 covering the tip portion 403a of the catheter main body 403 and the tip portion 409b of the balloon 409 via the first heat transfer section 12, and a contracting force due to heat is applied. The tip member 402 covering the tip portion 403a of the catheter main body 403 is fused to the tip portion 403a of the catheter main body 403. The balloon tip portion 209b is fused to the base end 402a of the tip member 402. [Explanation of symbols]

[0107] 1 catheter 2 Tip member 2a Proximal end of distal end member 2b Tip of tip member 2c Axial intermediate portion of tip member 2d The most distal end of the tip 3 Catheter body 3a Tip of the catheter body 3b The most distal part of the catheter body 4 Shaft section 4a Tip of shaft 5 Hub 6 Guidewire 7 Outer tube 8 Inner tube 9. Balloon 9a Balloon body 10 Bend 11 Test equipment 11a Gripping part 11b Contact surface 11c Drive unit 12 First heat transfer section 13 Second heat transfer section 14 Connection part 100 catheters 102 Tip member 102a Proximal end 102b Tip 102c middle part 103 Catheter body 103a Tip 103b Cutting edge section 104 Shaft section 104a Tip 108 Inner tube 109 Balloon 109a Balloon body 109b Tip 109d Cutting edge section 110 Bend 200 catheters 202 Tip member 202a Proximal end 202b Tip 202c middle part 203 Catheter body 203a Tip 203b Cutting edge section 204 Shaft 208 Inner tube 209 Balloon 209a Balloon body 209b Tip 209d Cutting edge section 209e Slope 210 Bend 211 Inner layer 212 Outer layer 300 catheters 302 Tip member 302a Proximal end 302b Tip 302c Axial middle section 303 Catheter body 303a Tip 303b Cutting edge section 308 Inner tube 309 Balloon 309a Balloon body 309b Tip 310 Bend 311 Inner layer 312 Outer layer 322 Catheter body covering part 332 Balloon tip covering part 400 catheters 402 Tip Part 402a Proximal end 402b Tip 402c Axial intermediate section 402e Part 403b Cutting edge section 403 Catheter body 403a Tip 403b Cutting edge section 403c narrow diameter section 408 Inner tube 409 Balloon 409a Balloon body 409b Tip 410 Bend 411 Inner layer 412 Outer layer 413 Step F external force F' reaction force O center axis θ angle

Claims

1. a cylindrical tip member connected to the tip of the catheter body; a bending portion that fixes the distal end portion of the catheter body and bends when an external force in a bending direction is applied to the distal end portion of the tip member, the distal end member is formed only from a thermoplastic resin and has a distal end portion, a proximal end portion, and an intermediate portion that connects the distal end portion and the proximal end portion, and the outer diameter of the distal end member is uniform throughout the portion including the intermediate portion and the proximal end portion, excluding the distal end portion; a catheter in which the bending portion is formed in the intermediate portion located distally of the most distal end portion of the catheter body and distally of the base end portion of the tip member, because the Young's modulus of the bending portion located in the intermediate portion of the tip member is smaller than the Young's modulus of the base end portion and the tip portion of the tip member.

2. The catheter of claim 1 , wherein the distal end of the tip member is tapered.

3. The catheter according to claim 1 or 2, wherein the tip member is made of at least one thermoplastic resin layer.

4. A method for manufacturing a catheter according to any one of claims 1 to 3, comprising the steps of: A method for manufacturing a catheter, comprising a heat treatment step of fusing the base end of the cylindrical tip member to the catheter body while suppressing the thermal load on an axial intermediate portion of the tip member compared to the thermal load on the base end.

5. The method according to claim 4 , wherein the heat treatment step includes a heat transfer step of transferring heat to the base end portion through a tubular heat transfer portion that shrinks due to heat.

6. The method of claim 5 , wherein the heat transfer portion absorbs radiation and generates heat.

7. The method according to any one of claims 4 to 6, wherein the heat treatment step includes a tip treatment step of applying a thermal load to the tip portion of the tip member that is greater than the thermal load applied to the axial intermediate portion of the tip member.

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