JP7718082B2 - Catheter and method of manufacturing the same - Google Patents

Description

The present invention relates to a catheter and a method for manufacturing a catheter.

Catheters have traditionally been used for insertion into tubular organs inside the body, such as blood vessels. Catheters include structures that include an inner layer, a braided body disposed on the outer periphery of the inner layer, and an outer layer disposed on the outer periphery of the braided body, as well as structures that do not have an inner layer and have a braided body disposed on the inner periphery of the outer layer. The braided body functions as a reinforcing material and is formed by weaving together metal wires such as tungsten or stainless steel. The braided body is composed of a first set of multiple wires wound at an angle relative to the axial direction, and a second set of multiple wires wound at an angle relative to the axial direction and intersecting the first set of wires. Patent Document 1 describes a catheter with a braided body disposed between the inner and outer layers.

Japanese Patent Application Laid-Open No. 2000-262625

However, because the metal wires in a braided body have high rigidity, there is a possibility that the two wires may separate or become misaligned in the circumferential direction at their intersections. For this reason, the wire located on the outer periphery of the braided body and the wire located on the inner periphery at the intersection may be welded together. One possible welding method is to irradiate one or both sides of the outer periphery wire with laser light to melt that side, and then allow the irradiated energy of the laser light to penetrate through the melted and solidified part into the inner periphery wire, thereby performing a fillet weld to join the two outer and inner periphery wires.

However, when joining two wires using this type of fillet welding, when laser light is irradiated onto one or both sides of the outer wire to melt it, the width of the laser light irradiated area covers the entire width of the inner wire, so there is a possibility that almost the entire width of the inner wire will be melted by the irradiated energy of the laser light. Furthermore, if the melt depth of the inner wire becomes too great, there is a possibility that the inner wire will be cut. In this case, it is possible to reduce the irradiated energy of the laser light, but this may result in insufficient melting of the outer wire, reducing the joint strength of the two wires and resulting in an insufficient joint between the two wires.

The object of the present invention is to increase the joining strength of multiple wires while avoiding the breakage of each wire when joining the individual wires that form the braid at their intersections by laser welding.

The catheter of the present invention is a catheter equipped with a tubular braid including a first set of metallic wires wound at an angle relative to the axial direction and a second set of metallic wires wound at an angle relative to the axial direction and intersecting with the first set of wires at multiple intersections, wherein at least some of the multiple intersections, two of the wires are welded together by welds formed in corner regions including one of four corners when viewed from the outer periphery, and the welds are formed on the innermost wires only in a portion of the width direction when viewed from the outer periphery.

With the above configuration, when forming a welded portion by irradiating a laser beam, the irradiation energy of the laser beam can be prevented from extending across the entire width of the inner wire adjacent to the intersection. This prevents the inner and outer wires from being cut when joining the braid at the intersection by laser welding, eliminating the need to consider increasing the width or thickness of the wires. Furthermore, the setting range of the laser beam irradiation energy and the range to which the laser beam is irradiated can be set with greater freedom, and the irradiation energy of the laser beam can also be increased, thereby increasing the joining strength of multiple wires.

In the catheter according to the present invention, the corner region can be configured to be formed by an outer corner portion including one of the four corners of the wire on the outer periphery of the partial intersection, and a portion of the wire on the inner periphery adjacent to the outer corner portion in at least one of the radial and longitudinal directions.

In the catheter according to the present invention, the corner region may be configured to be located at a portion of the intersection where an obtuse angle is formed by the two strands.

With the above configuration, the laser beam irradiation range and irradiation position can be set with greater freedom than when the corner region is located in a part where two strands form an acute angle at an intersection. This also makes it easier to reduce the area of each strand that is damaged by the laser beam.

In the catheter according to the present invention, the partial intersections may be configured to include the most distal intersections of the multiple intersections that are located near the tip of the braided body where the cut portion is located.

With the above configuration, the two wires can be welded with high joint strength at the most extreme intersection near the tip where the braided body has its cut end, even though the two wires are more likely to separate and become misaligned. This makes the effect of welding the two wires at the intersection more pronounced.

The method for manufacturing a catheter according to the present invention is a method for manufacturing a catheter having a tubular braid including a first set of metallic wires wound at an angle relative to the axial direction and a second set of metallic wires wound at an angle relative to the axial direction and intersecting with the first set of wires at multiple intersections. The method includes a welding step in which a laser beam is irradiated onto a corner region including one of four corners as viewed from the outer periphery at at least some of the intersections, melting and solidifying the corner region to form a weld, thereby welding the two wires together. The weld is formed on the innermost wire only in a portion of the width direction as viewed from the outer periphery.

The above configuration prevents the laser beam irradiation energy used to form the weld from reaching the entire width of the inner wire adjacent to the intersection. This prevents the inner and outer wires from being cut when joining the braid at the intersection by laser welding, eliminating the need to increase the width or thickness of the wires. Furthermore, the setting range of the laser beam irradiation energy and the range to which the laser beam is irradiated can be set with greater flexibility, and the laser beam irradiation energy can also be increased, thereby increasing the joining strength of multiple wires. Furthermore, it is possible to complete the welding process for one intersection at least once.

In the catheter manufacturing method according to the present invention, the corner region can be configured to be formed by an outer corner portion including one of the four corners of the wire on the outer periphery of the partial intersection, and a portion of the wire on the inner periphery adjacent to the outer corner portion in at least one of the radial and longitudinal directions.

In the catheter manufacturing method according to the present invention, the corner region may be configured to be located at a portion of the intersection where an obtuse angle is formed by the two wires.

With the above configuration, the laser beam irradiation range and irradiation position can be set with greater freedom than when the corner region is located in a part where two strands form an acute angle at an intersection. This makes it easier to reduce the area of each strand that is damaged by the laser beam.

In the catheter manufacturing method according to the present invention, the partial intersection includes the most distal intersection of the multiple intersections that is located near the tip of the braided body where the cut portion is located, and the method can include a cutting step in which, after welding the two wires at the partial intersection in the welding step, one or both of the two wires are cut by irradiating them with laser light to form the cut portion.

With the above configuration, the two wires can be welded with high joint strength at the most extreme intersection near the tip where the braided body has its cut, even though the two wires are more likely to separate and become misaligned. This makes the effect of welding the two wires at the intersection more pronounced. Furthermore, by performing the cutting process after the welding process, the outer wire can be prevented from separating from the inner wire due to cutting, and there are no restrictions on the order in which the two wires can be cut. This simplifies the cutting process.

The catheter and catheter manufacturing method of the present invention enable the wires forming the braid to be joined at their intersections by laser welding, while increasing the joining strength of the multiple wires while avoiding the breakage of the individual wires.

1A and 1B are diagrams illustrating a state in which a catheter according to an embodiment is used. FIG. 2 is an overall view of the catheter shown in FIG. 1. FIG. 3 is a perspective view showing the catheter shown in FIG. 2 with a portion of the outer layer of the distal shaft peeled off. FIG. 4 is an enlarged view of part A in FIG. 3 . In a method for manufacturing a catheter according to an embodiment, (a) is a schematic diagram showing a welded portion and a planned cutting line before a braided body cutting step, and (b) is a schematic diagram showing a tip portion of the braided body after cutting. 5A is a schematic diagram corresponding to FIG. 4, showing the irradiated portion before a weld is formed on the braided body, and FIG. 5B is an enlarged view of the intersection including the irradiated portion of FIG. 5A. FIG. 7 is a diagram corresponding to FIG. 6A in a first example of a comparative example. FIG. 5 is a view corresponding to FIG. 4 in another embodiment.

An example of an embodiment of the present invention will be described in detail below with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment.

A guide extension catheter 10, which is a catheter according to one embodiment, will be described using Figures 1 to 6. As shown in Figure 1, the guide extension catheter 10 is used by inserting the lead-out portion of a guiding catheter 100 into a coronary artery 102 and leading a stent delivery catheter 106 out of the distal end P of the lead-out portion. In Figure 1, the guiding catheter 100 is indicated by the area shaded in black. Hereinafter, the guide extension catheter 10 will be referred to as the catheter 10. Because the catheter 10 is used in the state shown in Figure 1, its distal end P must be flexible enough to facilitate insertion into organs such as blood vessels.

Figure 2 is an overall view of the catheter 10. The catheter 10 is a long member comprising a cylindrical distal shaft 12 and a proximal shaft 50 made of a metal wire and connected to the proximal end of the distal shaft 12. The distal end of the proximal shaft 50 is connected to a circumferential portion of the outer surface of the distal shaft 12. Note that the distal end of the proximal shaft 50 is not limited to being connected to the outer surface of the distal shaft, and may be disposed, for example, between the inner layer 14 and outer layer 30 (described below) of the distal shaft 12. In this embodiment, the "proximal end" refers to the rear side (left side in Figure 2) of the catheter 10 when it is inserted into a blood vessel. The "distal end" refers to the front side (right side in Figure 2) of the catheter 10 when it is inserted into a blood vessel.

Figure 3 is a perspective view showing the catheter 10 with a portion of the outer layer 30 of the distal shaft 12 peeled away. The distal shaft 12 includes an inner layer 14 made of resin, a braided body 16 attached to the outer periphery of the inner layer 14, and an outer layer 30 made of resin attached to the outer periphery of the braided body 16.

The inner layer 14 forms a lumen 15 for inserting another catheter inside. The resin material that makes up the inner layer 14 is not particularly limited, but examples include polytetrafluoroethylene (PTFE). The inner layer 14 is not limited to being a single-layer tube, and may also be a multi-layer tube made of the same or different materials.

The braided body 16 is a tubular body in which a first set of wires 17 and a second set of wires 18 are woven in a mesh pattern. Specifically, the first set of wires 17 is formed from a plurality of metal wires 17 wound around the outside of the inner layer 14, inclined along a first direction relative to the axial direction L of the catheter 10. The second set of wires 18 is formed from a plurality of metal wires 18 wound around the outside of the inner layer 14, inclined along a second direction different from the first direction relative to the axial direction L of the catheter 10, and intersects with the first set of wires 17 at a plurality of intersections 19.

Each of the first and second sets of wires 17, 18 is a metal wire such as tungsten or stainless steel. The cross section of each of the wires 17, 18 perpendicular to the longitudinal direction is rectangular.

The outer layer 30 covers the inner layer 14 and the outer periphery of the braided body 16. The outer layer 30 is thus provided on the outer periphery of the braided body 16. The resin material constituting the outer layer 30 is not particularly limited, but may be, for example, polyether block amide (PEBA), polyethylene (PE), polypropylene (PP), polyamide (PA), polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polyurethane (PU), nylon elastomer, polyester elastomer, ethylene-vinyl acetate resin (EVA), or polyvinyl chloride (PVC). For example, Pebax® manufactured by Arkema may be used as the resin constituting the outer layer 30. The outer surface of the outer layer 30 is preferably coated with a hydrophilic material such as hyaluronic acid, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl alkyl ether, and maleic anhydride copolymer (VEMA). For example, the hydrophilic coating may be applied only to the portion of the outer layer 30 extending from the distal end P to a predetermined position in the longitudinal middle. The outer layer 30 is not limited to a single-layer tube, but may be a multi-layer tube made of the same or different materials. Furthermore, the hardness of multiple longitudinal portions of the outer layer 30 may be varied. For example, if the outer layer 30 is divided into a distal end portion, a middle portion, and a proximal end portion, the hardness of the resin forming the distal end portion may be the lowest, the hardness of the resin forming the proximal end portion may be the highest, and the hardness of the resin forming the middle portion may be intermediate between the hardness of the resins at the distal end and the proximal end portions. This makes the distal end portion of the outer layer 30 softer, thereby preventing damage to blood vessels and improving blood vessel tracking. Furthermore, the hardness of the proximal end portion of the outer layer 30 ensures pushability. Furthermore, by making the hardness of the middle section intermediate between that of the distal end and the proximal end, it is possible to make the middle section less likely to break even if there is a large difference in hardness between the distal end and the proximal end.

Furthermore, the distal end of the distal shaft 12 is provided with a distal tip 31 (Figure 2) formed from a portion of the outer layer 30 and made of resin with radiopaque metal powder mixed in. In Figure 2, the distal tip 31 is shown as a sandy area at the tip of the distal shaft 12. For example, bismuth oxide (Bi), tungsten (W), barium sulfate, etc. are used as the metal powder. By forming the distal tip 31 in this way by mixing radiopaque metal powder into the resin of the outer layer 30, the flexibility of the distal end of the distal shaft 12 is maintained, while the operator can more easily recognize the distal end position of the distal shaft 12 under X-ray fluoroscopy.

The two wires 17, 18 are welded together at a weld formed in one corner region at at least some of the multiple intersections 19. This will be explained in more detail using Figures 4 to 6. The following explanation will focus on the tip of the braid 16 located on the distal end side of the distal shaft 12.

Figure 4 is an enlarged view of portion A in Figure 3. In the example of Figure 4, of the multiple intersections 19 at the tip of the braid 16 located on the distal end side of the distal shaft 12, two wires 17, 18 are welded at the most distal intersection 19 located near the tip having the cut portion 20. Multiple most distal intersections 19 are present at multiple circumferential positions near the tip of the braid 16. The braid 16 forms approximately diamond-shaped mesh holes at the portions where two adjacent wires 17 of a first set and two adjacent wires 18 of a second set are combined. Furthermore, around each intersection 19, the two wires 17, 18 form two diagonal obtuse angles (angles E1, E2 in Figure 4) and two diagonal acute angles (angles E3, E4 in Figure 4).

The two wires 17, 18 are joined by a weld 36 at the leading-edge intersection 19. Specifically, as shown in the leading-edge intersection 19 at the vertically middle portion in Figure 4, the weld 36 is formed in a corner region including the first angle P1a among the four corners P1a, P2, P3, and P4 of the outer wire 17. The corner region is formed by the outer-edge corner portion including the first angle P1a among the four corners P1a, P2, P3, and P4 of the outer wire 17 at the leading-edge intersection 19, and a portion of the inner wire 18 adjacent to the outer-edge corner portion in at least one of the radial and longitudinal directions. In Figure 6(b) described below, before the weld 36 is formed, the outer-edge corner portion including the first angle P1a is indicated by a horizontal stripe Q1, and the portion of the inner wire 18 adjacent to the outer-edge corner portion in the longitudinal direction is indicated by a vertical stripe Q2. In Figure 4, the weld 36 is indicated by a sandy area. The weld 36 is formed by melting the outer corner portion and the portion of the inner wire 18 adjacent to the outer corner portion, which then mix and solidify. This weld 36 welds the two wires 17, 18. Furthermore, the weld 36 is formed only partially along the boundary line M with the most distal intersection 19 of the inner wire 18 when viewed from the outer side as shown in Figure 4, but not along the entire direction. As a result, the weld 36 is formed only partially across the width of the inner wire 18 when viewed from the outer side. Therefore, when the braid 16 is joined at the intersection 19 by laser welding, as described below, it is possible to prevent the wires 17, 18 from being cut and to increase the joining strength of the two wires 17, 18.

Furthermore, the corner region forming the weld 36 is located at the tip intersection 19, where the two strands 17, 18 form an obtuse angle E1.

Next, a method for manufacturing the catheter 10 will be described using Figures 5 and 6. Figure 5 shows a method for manufacturing a catheter according to an embodiment, with (a) being a schematic diagram showing the welded portion and the planned cutting line before the braided body 16 is cut, and (b) being a schematic diagram showing the tip of the braided body 16 after cutting. Figure 6(a) is a schematic diagram corresponding to Figure 4, showing the irradiated portion 38 before the welded portion is formed on the braided body 16, and Figure 6(b) being an enlarged view of the intersection 19 including the irradiated portion 38 in Figure 6(a).

First, an "arrangement step" is performed in which the braid 16 is arranged on the cylindrical surface 14a, which is the outer peripheral surface of the inner layer 14. At this time, the inner layer 14 may be extruded into a long cylindrical shape using a resin extruder or the like onto a metal core wire or a shaft portion having a cylindrical outer peripheral surface that constitutes a jig. A braiding machine may be used to arrange the braid 16 on the outer periphery of the inner layer 14. The braiding machine winds a first set of multiple strands 17 around the cylindrical surface 14a of the inner layer 14 in a first direction inclined with respect to the axial direction of the inner layer 14, and winds a second set of multiple strands 18 around the cylindrical surface 14a of the inner layer 14 in a second direction inclined with respect to the axial direction of the inner layer 14 and intersecting the first direction. At this time, the braid 16 is arranged so that it extends almost to the tip of the inner layer 14.

Next, the "welding process" is performed. In the welding process, the two wires 17, 18 are welded by irradiating the intersection 19, which is the most distal intersection and is located at the bottom of FIG. 5(a), next to the planned cutting line indicated by the dashed line in FIG. 5(a), with a laser. At this time, the laser light is irradiated onto a corner region, including one corner toward the axial center of the braid 16, out of the four corners of the intersection 19 to be irradiated with the laser. In FIGS. 5(a) and 5(b), the laser light irradiation region is indicated by multiple circles with no filled-in interiors.

More specifically, as shown in Figure 6, the intersection 19 before irradiation with laser light is rhomboidal with four corners P1, P2, P3, and P4. The laser light is applied to the irradiation area (within circle H in Figure 6(a)) so as to irradiate the outer corner portion, including corner P1, located at the axial center of the braid 16, of the four corners P1, P2, P3, and P4 of the intersection 19, and the irradiated portion 38 formed by the outer corner portion and a longitudinally adjacent portion of the inner wire 18. As a result, the portions of the two wires 17, 18 included in the irradiated portion 38 and the radially adjacent portion of the inner wire 18 to the outer corner portion melt and solidify, forming a weld 36 (Figure 4), which joins the two wires 17, 18. Therefore, the corner region that forms the weld 36 is formed by the outer corner portion of the outer wire 17, which includes the first angle P1a of the intersection 19, and the portion of the inner wire 18 that is adjacent to the outer corner portion in both the radial and longitudinal directions. However, the corner region may also be formed by the outer corner portion and the portion of the inner wire 18 that is adjacent to the outer corner portion in only one of the radial and longitudinal directions.

As described above, the laser beam irradiates the irradiation area, and the outer and inner wires 17 and 18 are partially melted and liquefied, and then solidified to become one body. In this example, only a portion of the inner wire 18 melts in the width direction, eliminating the risk of cutting the inner wire 18. The laser beam irradiation energy can be set high to irradiate the corner area. This increases the amount of melting of the two wires 17 and 18 irradiated with the laser beam. When the molten wires 17 and 18 solidify to form the weld 36, the two wires 17 and 18 are more likely to be strongly joined at the weld 36. Furthermore, because the welds of each wire 17 and 18 do not extend across the entire width of each wire, cutting of each wire 17 and 18 is prevented. The above describes a case where two wires 17, 18 are joined by a weld 36 at an intersection 19 where the first set of wires 17 is arranged on the outer periphery and the second set of wires 18 is arranged on the inner periphery. However, even at an intersection 19 where the second set of wires 18 is arranged on the outer periphery and the first set of wires 17 is arranged on the inner periphery, the two wires 17, 18 can be joined in the same way by a weld 36, simply by reversing the positions.

After the "welding process," the "cutting process" is performed. In the "cutting process," the braid 16 is cut along the cutting line indicated by the dashed line in Figure 5(a). At this time, of the two wires 17, 18 extending in two directions from each of the intersections at the most distal ends where the welds are formed toward the tip, the portions close to the intersection 19 where the welds are formed are cut by irradiating them with laser light. Specifically, in Figure 5(a), laser light is irradiated onto each of the wires 17, 18 along the cutting line. In Figure 5(a), the cut portions of the first set of wires 17 are indicated by black circles, and the cut portions of the second set of wires 18 are indicated by black squares. By irradiating each of the wires 17, 18 along the cutting line with laser light, the portions irradiated by the laser light melt, and the corresponding wires 17, 18 are cut by this melting. This results in the braid 16 cut along the cutting line, as shown in Figure 5(b). The excess portion distal to the cutting line is then removed. Therefore, the intersection 19 where the welded portion of the braided body 16 in Figure 5(a) is formed becomes the most distal intersection 19 near the tip having the cut portion 20 in the braided body 16 in Figure 5(b).

In the "cutting process," excess wire is removed, and then an outer layer 30 made of resin is molded around the outer periphery of the braid 16 and inner layer 14 to form the distal shaft 12. The proximal shaft 50 is then joined to the distal shaft 12 to form the catheter 10.

According to the catheter 10 and its manufacturing method, the two wires 17, 18 are welded together by a weld 36 formed in a corner region including one of the four corners of the intersection 19 at the most distal end. Furthermore, the weld 36 is formed only in a portion of the width of the inner wire when viewed from the outer periphery. This prevents the laser beam energy from reaching the entire width of the inner wire adjacent to the intersection 19 when the weld 36 is formed by laser beam irradiation. This prevents the inner and outer wires 17, 18 from being cut when the braid 16 is joined at the intersection 19 by laser welding, eliminating the need to increase the width or thickness of the wires. Furthermore, the laser beam irradiation energy and the laser beam irradiation range can be set with greater flexibility, and the laser beam irradiation energy can be increased, thereby increasing the joining strength of the two wires 17, 18. This increases the bonding strength of the multiple wires 17, 18 while avoiding cutting of the individual wires 17, 18. Furthermore, according to the above-described method for manufacturing the catheter 10, it is possible to complete the welding process for each intersection 19 at least once.

Furthermore, the corner region where the weld 36 is formed is located in the portion of the intersection 19 where the two wires 17, 18 form an obtuse angle. This allows for greater flexibility in determining the laser beam irradiation range and irradiation position compared to when the corner region where the weld is formed is located in the portion where the two wires form an acute angle. This also makes it easier to reduce the area of each wire 17, 18 that is damaged by the laser beam. In this example, of the two corners P1a, P3 that form an obtuse angle at the most distal intersection, the two wires 17, 18 are welded in the corner region on the side of corner P1a, opposite the cut portion 20 of each wire 17, 18. Alternatively, of the two corners P1a, P3 that form an obtuse angle at the most distal intersection, the two wires 17, 18 may be welded in the corner region on the side of corner P3, which is on the same side as the cut portion 20 of each wire 17, 18.

Furthermore, the intersection 19 where the weld 36 is formed is the most distal intersection 19 of the multiple intersections 19, located near the tip of the braid 16 where the cut portion 20 is located. As a result, at the most distal intersection near the tip of the braid 16 where the cut portion 20 is located, the two wires 17, 18 are more likely to separate and become misaligned, but the two wires 17, 18 can be welded with high joint strength. This makes the effect of welding the two wires 17, 18 at the intersection 19 more pronounced.

Furthermore, according to the catheter manufacturing method of this example, after welding the two wires at the intersection 19 in the welding process, a cutting process is performed in which both wires 17, 18 are cut by irradiating them with laser light to form the cut portion 20. This prevents the wire on the outer periphery of the intersection from separating from the wire on the inner periphery due to cutting, and does not restrict the order of cutting when both wires are cut near the intersection. Specifically, when two wires are not welded at the intersection but are cut adjacent to the intersection, the order of cutting is restricted so that the wire on the inner periphery at the intersection is cut after the wire on the outer periphery. This is because if the cutting order were reversed, the outer wire would be less strongly pressed against the inner periphery, making it easier for the outer wire to separate from the inner wire at the intersection. On the other hand, according to the manufacturing method of this example, the order of cutting is not restricted, thereby simplifying the cutting process. After welding the two wires at the intersection in the welding process, a cutting process may be performed in which only one of the two wires 17, 18 is cut by irradiating it with laser light to form a cut portion. In this case, for example, the intersections having cut portions may be arranged alternately in the first and second axial rows around the circumference of the braid.

Figure 7 is a diagram corresponding to Figure 6 of a first comparative example. In this first comparative example, two wires 17, 18 on the outer and inner sides are joined by fillet welding at the intersection 19. Specifically, at the intersection 19, laser light is irradiated to both widthwise sides of the outer wire 17, which are circular areas indicated by T1 and T2 in Figure 7, to melt both sides, and the irradiation energy of the laser light penetrates through the melted and solidified portion into the inner wire 17. This joins the two wires 17, 18 that form the intersection 19. For example, as shown in Figure 7, the center of the irradiation area is positioned approximately in the longitudinal center of both widthwise ends of the outer wire 17 at the intersection 19. Furthermore, the width of the laser light irradiated area covers almost the entire width of each wire 17, 18. As a result, the entire width of the outer peripheral side surface 18a of the inner wire 18 forming the intersection 19, adjacent to the intersection 19 in the longitudinal direction of the wire 18, may be melted by the irradiation energy of the laser light. As a result, in the first comparative example, if the melt depth of the inner wire 18 forming the intersection 19 becomes large, the inner wire 18 may be cut in the width direction near the intersection 19. On the other hand, in the first comparative example, if the irradiation energy of the laser light is reduced, the risk of cutting the inner wire 18 can be reduced, but the outer wire 17 may not be melted sufficiently, reducing the joint strength between the two wires 17, 18 and potentially resulting in insufficient joining of the two wires 17, 18. According to the embodiment, this problem can be resolved.

In another embodiment, although not shown, at least one of the first and second sets of wires forming the braid may have a circular cross section. In this case, the two wires are laser-welded by irradiating the intersection from the outer periphery with a laser beam. In this case, as with the embodiment shown in Figures 1 to 6, the strength of the bond between the multiple wires is increased while preventing the individual wires from being cut. Furthermore, even when circular wires are used, the amount of melting of the wires can be roughly the same as when only rectangular cross-section wires are used, thereby achieving a welding strength similar to that of a configuration using only rectangular cross-section wires. Furthermore, when a circular cross-section wire is used for the outer periphery, the side of the outer periphery wire can be significantly reduced in the width direction. Therefore, compared to the first comparative example, a large gap is less likely to form between the inner periphery of the circular cross-section outer wire at the weld and the outer periphery of the inner periphery wire.

In each of the above embodiments, the intersection where two wires are welded in the braid 16 is limited to the most extreme intersections 19, 19a located near the tip where the braid has a cut portion. However, in addition to the most extreme intersections 19, 19a, two wires 17, 18 may also be welded in corner regions at other intersections. For example, two wires may be welded in corner regions at two or more rows of intersections spaced apart in the axial direction L at the tip of the braid 16. This increases the rigidity of the braid 16 at the tip. The rigidity of multiple regions may be varied by varying the number of intersections where two wires are welded in corner regions in multiple regions spaced apart in the axial direction L of the braid.

In addition, in each example of the above embodiment, the two wires are welded in a corner region that includes only one of the two corners P1a, P3 that form an obtuse angle at the intersection, but the two wires may also be welded in a corner region that includes only one of the two corners P2, P4 that form an acute angle at the intersection.

Figure 8 is a diagram corresponding to Figure 4 of another embodiment. In this example, unlike the configurations of Figures 1 to 6, two strands 17, 18 are welded at the leading-edge intersection 19 by welds 36a to 36d formed in four corner regions. Each corner region is formed by an outer-circumferential corner portion including one of the four corners P1a, P2, P3, and P4 of the outer-circumferential strand 17, and a portion of the inner-circumferential strand 18 adjacent to the outer-circumferential corner portion in at least one of the radial and longitudinal directions. Welds 36a to 36d are then formed in the four corner regions. In Figure 8, welds 36a to 36d are indicated by sandy areas. The two strands 17, 18 are welded by these four welds 36a to 36d. Furthermore, the welds 36a-36d are formed on only a portion of the inner wire 18 in the direction along the boundary lines M1 and M2 with the intersection 19 when viewed from the outer periphery as shown in Figure 8, and are not formed along the entire direction along these boundary lines M1 and M2. As a result, the welds 36a-36d are formed on only a portion of the width of the inner wire 18. While the above describes an intersection 19 where the wire 17 is arranged on the outer periphery and the wire 18 is arranged on the inner periphery, the same applies to an intersection 19 where the wire 18 is arranged on the outer periphery and the wire 17 is arranged on the inner periphery.

In this example, unlike the above-described embodiments, the two wires 17, 18 are welded at the intersection 19 by welds 36a-36d formed in the four corner regions, thereby increasing the weld strength. Furthermore, the strength against forces acting from multiple directions to separate the two wires 17, 18 can be increased. In this example, the remaining configuration and operation are the same as those shown in Figures 1-6.

In this example, the two wires 17, 18 are welded together using welds 36a-36d formed in the four corner regions of one intersection 19. However, the two wires 17, 18 may also be welded together using welds formed in only two or three of the four corner regions. Also, by varying the number of welds depending on the position of the intersection 19, the rigidity of the braided body can be varied.

In each of the above embodiments, the catheter of the present invention and the catheter manufactured by the manufacturing method of the present invention are described as guide extension catheters, but this is not limited to this and various catheters having a braided body on the inside of the outer layer can also be used.

10 Guide extension catheter (catheter), 12 Distal shaft, 14 Inner layer, 14 Cylindrical surface, 15 Lumen, 16 Braided body, 17, 18 Wire, 18a Outer peripheral side surface, 19 Intersection, 20 Cutting portion, 21 Wire, 22 Gap, 30 Outer layer, 31 Distal tip, 36, 36a to 36d Welded portion, 38 Irradiated portion, 50 Proximal shaft, 100 Guiding catheter, 102 Coronary artery, 106 Stent delivery catheter.

Claims (5)

A catheter comprising a tubular braid including a first set of metallic wires wound at an angle to an axial direction, and a second set of metallic wires wound at an angle to the axial direction and intersecting the first set of wires at multiple intersections,
At least some of the plurality of intersections are welded to each other by a weld formed in a corner region including one of four corners when viewed from the outer periphery,
the welded portion is formed on only a portion of the wire on the inner circumferential side in the width direction when viewed from the outer circumferential side ,
the corner region is located at a portion where an obtuse angle is formed by the two wires at the partial intersection,
the partial intersections include a most distal intersection among the plurality of intersections, the most distal intersection being arranged in the vicinity of a tip end having a cut portion of the braided body;
The corner region is one of two corners where an obtuse angle is formed at an intersection of the leading ends of the two wires, and the corner region is the corner region on the corner side opposite to the leading ends of the two wires.
catheter. The catheter of claim 1,
The corner region is formed by an outer circumferential corner portion including one of four corners of the wires on the outer circumferential side of the partial intersection, and a portion of the wires on the inner circumferential side adjacent to the outer circumferential corner portion in at least one of the radial direction and the longitudinal direction.
catheter. A method for manufacturing a catheter having a tubular braid including a first set of metallic wires wound at an angle to an axial direction, and a second set of metallic wires wound at an angle to the axial direction and intersecting the first set of wires at a plurality of intersections,
a welding process in which a corner region including one of four corners as viewed from an outer periphery of at least some of the plurality of intersections is irradiated with laser light to melt and solidify the corner region to form a weld, thereby welding the two wires together,
the welded portion is formed on only a portion of the wire on the inner circumferential side in the width direction when viewed from the outer circumferential side ,
the corner region is located at a portion where an obtuse angle is formed by the two wires at the partial intersection,
the partial intersections include a most distal intersection among the plurality of intersections, the most distal intersection being arranged in the vicinity of a tip end having a cut portion of the braided body;
The corner region is one of two corners where an obtuse angle is formed at an intersection of the leading ends of the two wires, and the corner region is the corner region on the corner side opposite to the leading ends of the two wires.
A method for manufacturing a catheter. 4. The method for manufacturing a catheter according to claim 3 ,
The corner region is formed by an outer circumferential corner portion including one of four corners of the wires on the outer circumferential side of the partial intersection, and a portion of the wires on the inner circumferential side adjacent to the outer circumferential corner portion in at least one of the radial direction and the longitudinal direction.
catheter. 5. The method for manufacturing a catheter according to claim 3 or 4 ,
the partial intersections include a most distal intersection among the plurality of intersections, the most distal intersection being arranged in the vicinity of a tip end having a cut portion of the braided body;
a cutting step of cutting one or both of the two wires by irradiating them with laser light so as to form the cut portion after welding the two wires at the partial intersection portion in the welding step,
A method for manufacturing a catheter.