Extension catheter

Abstract

Provided is an extension catheter that can be inserted into a catheter and protrude from an opening at the distal end of the catheter, is less likely to become kinked, and can even prevent kickback of the catheter to be used when the extension catheter is inserted.　The extension catheter has: a cylindrical member that has a lumen extending in the longitudinal axis direction and has a proximal-side opening and a distal-side opening; and a linear member that is fixed to the cylindrical member and extends further to the proximal side than the cylindrical member. The cylindrical member has a large-diameter segment, a proximal-side small-diameter segment on the proximal side of the large-diameter segment, and a distal-side small-diameter segment on the distal side of the large-diameter segment with respect to the longitudinal axis direction. A braided tube is disposed on the outside in the radial direction of the cylindrical member on at least a portion of the proximal-side small-diameter segment and on at least a portion of the large-diameter segment of the cylindrical member. In a vertical cross-section in the longitudinal axis direction of the cylindrical member, the diameter of an inscribed circle with respect to the outer edges of the proximal-side small-diameter segment and the distal-side small-diameter segment of the cylindrical member is smaller than the diameter of an inscribed circle with respect to the outer edge of the large-diameter segment of the cylindrical member.

Description

Extension catheter

[0001] The present invention relates to an extension catheter.

[0002] Percutaneous coronary intervention (PCI) is performed to treat ischemic heart diseases such as angina pectoris and myocardial infarction by dilating narrowed portions of the coronary arteries of the heart using intravascular treatment devices such as stents and balloons to increase blood flow. In this procedure, a distal end of a guiding catheter is inserted into the entrance of the coronary artery, and then an extension catheter is inserted through a proximal opening of the guiding catheter, with a portion of the extension catheter protruding from a distal opening of the guiding catheter. Because the outer diameter of the extension catheter is smaller than that of the guiding catheter, the use of the extension catheter facilitates delivery of an intravascular treatment device to an affected area in the coronary artery.

[0003] Various such extension catheters are known, and for example, Patent Document 1 discloses an extension catheter that includes a tubular portion, a first tapered portion located proximally of the tubular portion, and a second tapered portion located proximally of the first tapered portion. Patent Document 1 also discloses that the tubular portion includes a reinforcing layer, and that the reinforcing layer preferably has a braided shape.

[0004] International Publication No. 2020 / 162286

[0005] The diameter of the outer edge of the extension catheter is smaller than that of the guiding catheter, making it easier to deliver the extension catheter to the affected area within the coronary artery. However, the smaller diameter of the outer edge of the extension catheter makes it more susceptible to kinking.

[0006] The present invention has been made in light of the above-mentioned circumstances, and its object is to provide an extension catheter that is inserted into a catheter and can protrude from an opening at the distal end of the catheter, that is resistant to kinking, and that can prevent the catheter from kicking back when used with the extension catheter inserted therein.

[0007] The present invention is as follows: [1] An extension catheter that can be inserted into a catheter and protrude from an opening at a distal end of the catheter, the extension catheter comprising: a tubular member having an inner lumen extending in a longitudinal axis direction and having a proximal opening and a distal opening; and a linear member fixed to the tubular member and extending proximally from the tubular member, the tubular member having, in the longitudinal axis direction, a large diameter section, a proximal small diameter section proximal to the large diameter section, and a distal small diameter section distal to the large diameter section, a braided tube being disposed radially outside the tubular member in at least a part of the distal small diameter section and at least a part of the large diameter section, and in a vertical cross section in the longitudinal axis direction of the tubular member, the diameters of inscribed circles of the tubular member with respect to outer edges of the proximal small diameter section and the distal small diameter section are smaller than the diameter of the inscribed circle of the tubular member with respect to the outer edge of the large diameter section. [2] The extension catheter according to [1], wherein a braided tube is disposed on the radially outer side of the tubular member in at least a portion of the large diameter section of the tubular member and the proximal small diameter section of the tubular member. [3] The extension catheter according to [1] or [2], wherein, when the length of the section in which the braided tube is disposed in the longitudinal axis direction of the tubular member is K, the large diameter section is disposed proximally of a K / 2 position in the longitudinal axis direction of the tubular member. [4] The extension catheter according to any of [1] to [3], wherein a hydrophilic coating layer is disposed on the surface of the distal small diameter section of the tubular member. [5] The extension catheter according to [4], wherein a hydrophilic coating layer is not disposed on a portion of the surface of the large diameter section of the tubular member and on the surface of the proximal small diameter section of the tubular member. [6] The extension catheter according to [4], wherein a hydrophilic coating layer is not disposed on the surface of the large diameter section of the tubular member and the surface of the proximal small diameter section of the tubular member. [7] The extension catheter according to [4], wherein a hydrophilic coating layer is disposed on a portion of the surface of the large diameter section of the tubular member.[8] The extension catheter according to any one of [1] to [7], wherein the linear member is fixed to the proximal small diameter section of the tubular member, and in a vertical cross section of the tubular member taken in the longitudinal axis direction, the shape of the outer edge of the distal small diameter section and the large diameter section of the tubular member is circular, and the shape of the outer edge of the proximal small diameter section of the tubular member is elliptical, oval, or egg-shaped. [9] The extension catheter according to any one of [1] to [7], wherein the linear member is fixed to a portion of the large diameter section and the proximal small diameter section of the tubular member, and in a vertical cross section of the tubular member taken in the longitudinal axis direction, the shape of the outer edge of the distal small diameter section of the tubular member is circular, and the shape of the outer edge of the portion of the large diameter section and the proximal small diameter section of the tubular member is elliptical, oval, or egg-shaped.

[10] The extension catheter according to any one of [1] to [9], wherein the Shore D hardness of the large diameter section of the tubular member is greater than the Shore D hardness of the proximal small diameter section of the tubular member and the Shore D hardness of the distal small diameter section of the tubular member.

[0008] The extension catheter according to the present invention comprises a tubular member, a linear member, and a braided tube, and the tubular member has, in the longitudinal direction, a large diameter section, a proximal small diameter section proximal to the large diameter section, and a distal small diameter section distal to the large diameter section. The position of the braided tube and the diameter of the outer edge of the tubular member are appropriately controlled, making it possible to provide an extension catheter that is less likely to kink. Furthermore, because the extension catheter is less likely to kink, it can more easily fit the shape of the catheter into which it is inserted, thereby stabilizing catheter movement and preventing kickback.

[0009] Fig. 1 is a side view showing an embodiment of an extension catheter, and Fig. 2 is a side view showing the extension catheter shown in Fig. 1 inserted into a second catheter with a portion of the extension catheter protruding from an opening at the distal end of the second catheter.

[0010] An embodiment of an extension catheter according to the present invention is an extension catheter that is inserted into a catheter and can protrude from an opening at the distal end of the catheter, the extension catheter comprising: a tubular member having an inner lumen extending in the longitudinal axis direction, the tubular member having a proximal opening and a distal opening; and a linear member fixed to the tubular member and extending proximally from the tubular member, the tubular member having, in the longitudinal axis direction, a large diameter section, a proximal small diameter section proximal to the large diameter section, and a distal small diameter section distal to the large diameter section, a braided tube being disposed radially outside the tubular member for at least a part of the distal small diameter section and at least a part of the large diameter section, and the diameters of the inscribed circles for the outer edges of the proximal small diameter section and the distal small diameter section of the tubular member in a vertical cross section in the longitudinal axis direction of the tubular member are smaller than the diameter of the inscribed circle for the outer edge of the large diameter section of the tubular member.

[0011] The present invention will be described in more detail below based on the embodiments, but the present invention is not limited to the following embodiments. Of course, modifications can be made within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in the drawings for convenience. In such cases, reference should be made to the specification and other drawings. Furthermore, the dimensions of various components in the drawings may differ from actual dimensions, as priority is given to helping understand the features of the present invention.

[0012] In this specification, the proximal side refers to the direction toward the user in the longitudinal direction, and the distal side refers to the opposite side of the proximal side, i.e., the direction toward the treatment target. Furthermore, when each component is divided into two equal parts along the longitudinal axis, the distal portion of each component is referred to as the distal section, and the proximal portion of each component is referred to as the proximal section. The distal end of each component is the most distal end of each component, and the proximal end of each component is the most proximal end of each component. The end of each component refers to the portion including the end of each component and its periphery. That is, the distal end of each component refers to the portion including the distal end of each component and its periphery, and the proximal end of each component refers to the portion including the proximal end of each component and its periphery. The longitudinal axis direction may be designated x, the radial direction y, and the circumferential direction z.

[0013] Fig. 1 is a side view showing an embodiment of an extension catheter. Fig. 2 is a side view showing the extension catheter shown in Fig. 1 inserted into a second catheter, with a portion of the extension catheter protruding from an opening at the distal end of the second catheter. In Figs. 1 and 2, the right side of the figures is the proximal side, and the left side of the figures is the distal side.

[0014] 1 or 2 , the extension catheter 1A is a catheter that is inserted into the second catheter 2 and can protrude from an opening 2bP at the distal end 2b of the second catheter 2. The second catheter 2 has a lumen extending in the longitudinal axis direction x, and has a proximal end 2a and a distal end 2b. For example, after inserting the distal end of the second catheter 2 into the entrance of a coronary artery, the extension catheter 1A is inserted into the second catheter 2 through the opening 2aP at the proximal end 2a of the second catheter 2, and then the extension catheter 1A is inserted into the coronary artery with a portion of the extension catheter 1A protruding from the opening 2bP at the distal end 2b of the second catheter 2, thereby enabling the delivery of an intravascular treatment device such as a balloon or a stent to an affected area in the coronary artery via the second catheter 2 and the extension catheter 1A.

[0015] The second catheter 2 is preferably a so-called guiding catheter. A guiding catheter is a catheter into whose lumen a therapeutic catheter such as a balloon catheter or a stent delivery catheter is inserted. The therapeutic catheter is preferably one that is inserted into a coronary artery, but may also be one that is inserted into other arteries such as a cerebral artery, or into internal ducts such as veins, pancreatic ducts, bile ducts, ureters, or bronchi.

[0016] The extension catheter 1A has a tubular member 10, a linear member 60, and a braided tube 20. The tubular member 10 has an inner lumen extending in the longitudinal axis direction x, and has a proximal opening 10aP and a distal opening 10bP. A portion of the linear member 60 is fixed to the tubular member 10, and extends proximally beyond the tubular member 10.

[0017] The tubular member 10 has, in the longitudinal axis direction x, a large diameter section 10H, a proximal small diameter section 10La proximal to the large diameter section 10H, and a distal small diameter section 10Lb distal to the large diameter section 10H, and in a vertical cross section of the tubular member 10 in the longitudinal axis direction x, the diameters of the inscribed circles relative to the outer edge of the proximal small diameter section 10La and the distal small diameter section 10Lb of the tubular member 10 are smaller than the diameter of the inscribed circle relative to the outer edge of the large diameter section 10H of the tubular member 10. By providing a large diameter section 10H in a portion of the extension catheter 1A in this way, the rigidity of a portion of the extension catheter 1A can be increased, and at this time, the rigidity of the proximal small diameter section 10La on the proximal side and the distal small diameter section 10Lb on the distal side is lower than the rigidity of the large diameter section 10H, so even if the extension catheter 1A is placed in a bent portion of a blood vessel, the proximal small diameter section 10La and the distal small diameter section 10Lb will bend flexibly. As a result, kinking is less likely to occur. Furthermore, because the extension catheter 1A is less likely to kink, the extension catheter 1A will more easily fit the shape of the catheter into which it is inserted and used, which stabilizes catheter movement and prevents kickback from occurring. Furthermore, when the extension catheter 1A is inserted into a blood vessel, stress concentrates at the boundary between the large diameter section 10H and the proximal small diameter section 10La, but because the rigidity of the proximal small diameter section 10La is smaller than the rigidity of the large diameter section 10H, the tubular member 10 in the proximal small diameter section 10La is more likely to bend. Therefore, by arranging the proximal small diameter section 10La at a bent portion of the blood vessel, the bent tubular member 10 comes into contact with the inner wall of the blood vessel, and the movement of the extension catheter 1A can be stabilized.

[0018] In a vertical cross section of the tubular member 10 in the longitudinal axis direction x, the diameter of the inscribed circle relative to the outer edge of the large diameter section 10H of the tubular member 10 may be larger than the diameters of the inscribed circles relative to the outer edges of the proximal small diameter section 10La and the distal small diameter section 10Lb of the tubular member 10. The method for increasing the diameter of the inscribed circle relative to the outer edge of the large diameter section 10H is not particularly limited, and for example, a small diameter tube may be abutted on both ends of a large diameter tube and connected in the longitudinal axis direction x by fusion or the like, or a thick outer layer, described later, may be formed on the outside of the tube in the radial direction y.

[0019] The tubular member 10 may have a proximal small diameter section 10La on the proximal side, a large diameter section 10H, and a distal small diameter section 10Lb on the distal side, arranged consecutively in this order with respect to the longitudinal axis direction x. The diameter of an inscribed circle relative to the outer edge of the large diameter section 10H of the tubular member 10 may be, for example, 1.46 to 2.32 mm. The diameter of an inscribed circle relative to the outer edge of the proximal small diameter section 10La of the tubular member 10 may be, for example, 1.30 to 2.30 mm. The diameter of an inscribed circle relative to the outer edge of the distal small diameter section 10Lb of the tubular member 10 may be, for example, 1.30 to 2.30 mm.

[0020] The diameter of the inscribed circle relative to the outer edge of the proximal small diameter section 10La of the tubular member 10 is preferably smaller than the diameter of the inscribed circle relative to the outer edge of the large diameter section 10H of the tubular member 10 by, for example, 0.5 to 25.0% smaller, more preferably 1.0 to 20.0% smaller, and even more preferably 1.5 to 15.0% smaller.

[0021] The diameter of the inscribed circle relative to the outer edge of the distal small diameter section 10Lb of the tubular member 10 is preferably smaller than the diameter of the inscribed circle relative to the outer edge of the large diameter section 10H of the tubular member 10 by, for example, 0.5 to 25.0% smaller, more preferably 1.0 to 20.0% smaller, and even more preferably 1.5 to 15.0% smaller.

[0022] The length of the tubular member 10 in the longitudinal axis direction x may be, for example, 200 to 400 mm. In the longitudinal axis direction x of the tubular member 10, the length of the large diameter section 10H may be, for example, 3 to 80 mm, the length of the proximal small diameter section 10La may be, for example, 3 to 60 mm, and the length of the distal small diameter section 10Lb may be, for example, 150 to 300 mm. The lengths of the proximal small diameter section 10La and the distal small diameter section 10Lb may be the same, but it is preferable that the proximal small diameter section 10La is shorter than the distal small diameter section 10Lb. In the longitudinal axis direction x of the tubular member 10, the ratio of the length of the proximal small diameter section 10La to the length of the large diameter section 10H (length of the proximal small diameter section 10La / length of the large diameter section 10H) may be, for example, 0.04 to 20 or 0.5 to 10. In the longitudinal axis direction x of the tubular member 10, the ratio of the length of the distal small diameter section 10Lb to the length of the large diameter section 10H (length of the distal small diameter section 10Lb / length of the large diameter section 10H) may be, for example, 1.9 to 100, or 3 to 80.

[0023] 1 and 2, the tubular member 10 has a braided tube 20 disposed on the outside of the tubular member 10 in the radial direction y in at least a portion of the distal small diameter section 10Lb and at least a portion of the large diameter section 10H of the tubular member 10. This ensures the strength of the extension catheter 1A. As shown in FIGS. 1 and 2, the braided tube 20 may be disposed in at least a portion of the large diameter section 10H, but it may also be disposed in the entire large diameter section 10H.

[0024] When the braided tube 20 is disposed on the outside of the tubular member 10 in the radial direction y over the entire large diameter section 10H of the tubular member 10, the braided tube 20 may be disposed on the outside of the tubular member 10 in the radial direction y over at least a part of the proximal small diameter section 10La of the tubular member 10. This allows the pushing force from the proximal side to be transmitted to the tip side of the extension catheter 1A.

[0025] 1 , when the length of the section of the tubular member 10 in which the braided tube 20 is disposed in the longitudinal axis direction x of the tubular member 10 is K, the large diameter section 10H may be disposed proximal to the K / 2 position in the longitudinal axis direction x of the tubular member 10. In other words, the distal end of the large diameter section 10H may be located proximal to the K / 2 position in the longitudinal axis direction x of the tubular member 10. This can prevent kinking.

[0026] As shown in FIGS. 1 and 2 , the tubular member 10 may have an outer layer 40 on the outside of the braided tube 20 in the radial direction y. By providing the outer layer 40, the braided tube 20 can be protected and reinforced. The outer layer 40 may be made of a resin. The resin preferably contains, for example, a polyamide resin, a polyester resin, a polyurethane resin, a polyolefin resin, a vinyl chloride resin, a silicone resin, a natural rubber, or a combination thereof. The outer layer 40 more preferably contains a polyamide resin, a polyurethane resin, or a combination thereof. The resin may contain an elastomer having rubber elasticity. For example, the polyamide resin may contain a polyamide elastomer, and the polyurethane resin may contain a polyurethane elastomer.

[0027] The outer layer 40 may be a single layer, or may have a structure in which multiple layers are stacked in the radial direction y of the tubular member 10. When the outer layer 40 has a stacked structure, adjacent layers in the radial direction y of the tubular member 10 may contain different types of resins or may contain the same type of resin.

[0028] A hydrophilic coating layer may be disposed on the outer side in the radial direction y of the tubular member 10. Disposing the hydrophilic coating layer reduces frictional resistance during delivery. When the tubular member 10 has an outer layer 40, the hydrophilic coating layer may be disposed on the outer side of the outer layer 40 in the radial direction y.

[0029] The hydrophilic coating layer is preferably disposed on at least a portion of the surface of the distal small diameter section 10Lb of the tubular member 10, and more preferably disposed on the entire surface of the distal small diameter section 10Lb of the tubular member 10. This can reduce resistance during delivery.

[0030] When a hydrophilic coating layer is disposed on the surface of the distal small diameter section 10Lb of the tubular member 10, the hydrophilic coating layer may also be disposed on the surface of the large diameter section 10H of the tubular member 10. In this case, the hydrophilic coating layer may be disposed on the entire surface of the large diameter section 10H of the tubular member 10, but it is preferable that the hydrophilic coating layer be disposed on only a portion of the surface of the large diameter section 10H of the tubular member 10. Disposing the hydrophilic coating layer on only a portion of the surface of the large diameter section 10H of the tubular member 10 reduces resistance during delivery, and not disposing the hydrophilic coating layer on only a portion of the surface of the large diameter section 10H of the tubular member 10 increases frictional resistance when the guide extension catheter kicks back, improving backup force.

[0031] When a hydrophilic coating layer is disposed on the surface of the distal small diameter section 10Lb of the tubular member 10, it is preferable that the hydrophilic coating layer is not disposed on a portion of the surface of the large diameter section 10H of the tubular member 10 and on the surface of the proximal small diameter section 10La of the tubular member 10. This increases the frictional resistance when the guide extension catheter kicks back, improving the backup force.

[0032] When a hydrophilic coating layer is disposed on the surface of the distal small diameter section 10Lb of the tubular member 10, it is preferable that the hydrophilic coating layer is not disposed on the entire surface of the large diameter section 10H of the tubular member 10 and on the surface of the proximal small diameter section of the tubular member 10. This increases the frictional resistance when the guide extension catheter kicks back, further improving the backup force.

[0033] The method for forming the hydrophilic coating layer is not particularly limited. For example, the hydrophilic coating layer can be disposed on the outer side of the cylindrical member 10 in the radial direction y by immersing the cylindrical member 10, which may have the outer layer 40, in a hydrophilic coating agent or by applying a hydrophilic coating agent to the outer surface of the cylindrical member 10. Examples of the hydrophilic coating agent include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether-maleic anhydride copolymer, as well as hydrophilic polymers made from any combination of these. The hydrophilic coating agent may contain a drug or an additive.

[0034] A portion of the linear member 60 is fixed to the tubular member 10. The position of the linear member 60 fixed to the tubular member 10 is not particularly limited, and may be, for example, the distal end of the linear member 60.

[0035] The position of the tubular member 10 to which the linear member 60 is fixed is not particularly limited, and may be, for example, the proximal end of the tubular member 10, the proximal small diameter section 10La of the tubular member 10, or a part of the large diameter section 10H of the tubular member 10 and the proximal small diameter section 10La.

[0036] When the linear member 60 is fixed to the proximal small diameter section 10La of the tubular member 10, in a vertical cross section of the tubular member 10 in the longitudinal axis direction x, the shape of the outer edge of the distal small diameter section 10Lb and the large diameter section 10H of the tubular member 10 is circular, and the shape of the outer edge of the proximal small diameter section 10La of the tubular member 10 may be elliptical, oval, or egg-shaped.

[0037] When the linear member 60 is fixed to a portion of the large diameter section 10H of the tubular member 10 and the proximal small diameter section 10La, in a vertical cross section in the longitudinal axis direction x of the tubular member 10, the shape of the outer edge of the distal small diameter section 10Lb of the tubular member 10 may be circular, and the shapes of the outer edges of the portion of the large diameter section 10H and the proximal small diameter section 10La of the tubular member 10 may be elliptical, oval, or egg-shaped. In this case, the shape of the outer edge of the large diameter section 10H of the tubular member 10 to which the linear member 60 is not fixed may be circular.

[0038] The tubular member 10 may have a tubular portion and a proximal tapered portion located proximal to the tubular portion. When the tubular member 10 has a tubular portion and a proximal tapered portion, the large diameter section 10H, the proximal small diameter section 10La, and the distal small diameter section 10Lb are preferably arranged in the tubular portion. When the tubular member 10 has a tubular portion and a proximal tapered portion, a portion of the linear member 60 may be fixed to the proximal tapered portion of the tubular member 10.

[0039] The Shore D hardness of the large diameter section 10H of the tubular member 10 may be the same as or smaller than either the Shore D hardness of the proximal small diameter section 10La of the tubular member 10 or the Shore D hardness of the distal small diameter section 10Lb of the tubular member 10, but is preferably greater than the Shore D hardness of the proximal small diameter section 10La of the tubular member 10 and the Shore D hardness of the distal small diameter section 10Lb of the tubular member 10. By increasing the Shore D hardness of the large diameter section 10H of the tubular member 10 and providing small-diameter, flexible sections with low Shore D hardness on the distal and proximal sides of the large diameter section 10H, the proximal small diameter section 10La and the distal small diameter section 10Lb can bend appropriately starting from the large diameter section 10H, fitting to the shape of the bent portion of the blood vessel and stabilizing the guide extension catheter and making it less susceptible to kickback.

[0040] The Shore D hardness of the large diameter section 10H of the tubular member 10 is preferably greater than the Shore D hardness of the proximal small diameter section 10La of the tubular member 10 by, for example, 3 HS or more, more preferably 5 HS or more, and even more preferably 7 HS or more.

[0041] The Shore D hardness of the large diameter section 10H of the tubular member 10 is preferably greater than the Shore D hardness of the distal small diameter section 10Lb of the tubular member 10 by, for example, 3 HS or more, more preferably 5 HS or more, and even more preferably 7 HS or more.

[0042] The Shore D hardness of the large diameter section 10H of the tubular member 10 may be, for example, 20 to 87 HS. The Shore D hardness of the proximal small diameter section 10La of the tubular member 10 may be, for example, 20 to 87 HS. The Shore D hardness of the distal small diameter section 10Lb of the tubular member 10 may be, for example, less than 75 HS. The Shore D hardness can be measured based on ISO 868:2003 Plastic Durometer Hardness Test Method using a Type D durometer.

[0043] The cylindrical member 10 may be any resin tube, preferably containing a fluororesin, and more preferably made of a fluororesin. Fluororesin has excellent chemical resistance, non-stick properties, and low friction. The fluororesin preferably contains, for example, polytetrafluoroethylene, ethylene tetrafluoroethylene, fluorinated ethylene propylene, or a combination thereof.

[0044] The extension catheter 1A may have a radiopaque ring. The distal end 20b of the braided tube 20 may be disposed inside the radiopaque ring in the radial direction y. This allows the position of the distal end 20b of the braided tube 20 to be confirmed under X-ray fluoroscopy.

[0045] When the extension catheter 1A has the outer layer 40 on the outer side of the tubular member 10 in the radial direction y and on the outer side of the braided tube 20 in the radial direction y, the radiopaque ring may be disposed between the braided tube 20 and the outer layer 40 in the radial direction y of the tubular member 10. This makes it possible to suppress opening of the end of the braided tube 20, and therefore prevents the braided tube 20 from being exposed from the outer surface of the outer layer 40.

[0046] The radiopaque ring is a ring containing a radiopaque material, and may be a ring made of a radiopaque material, preferably including, for example, lead, barium, iodine, tungsten, gold, platinum, iridium, platinum-iridium alloy, stainless steel, titanium, cobalt-chromium alloy, palladium, tantalum, or a combination thereof.

[0047] The braided tube 20 preferably has a mesh structure in which wires are woven so as to cross each other. The wires may be solid wires or twisted wires. The braided tube 20 may be made up of one or more wires.

[0048] The wires of the braided tube 20 preferably include metal wires, fibers, or a combination thereof, more preferably metal wires. The metal wires preferably include, for example, stainless steel, titanium, nickel-titanium alloys, nickel-chromium alloys, cobalt-chromium alloys, tungsten alloys, or a combination thereof, more preferably stainless steel. The fibers preferably include, for example, polyarylate fibers, aramid fibers, ultra-high molecular weight polyethylene fibers, polyparaphenylene benzobisoxazole fibers (PBO fibers), carbon fibers, or a combination thereof. The fibers may be monofilaments or multifilaments.

[0049] The wires of the braided tube 20 may contain a radiopaque material, which allows the position of the braided tube 20 to be confirmed under X-ray fluoroscopy. The radiopaque material preferably contains, for example, lead, barium, iodine, tungsten, gold, platinum, iridium, platinum-iridium alloy, stainless steel, titanium, cobalt-chromium alloy, palladium, tantalum, or a combination thereof.

[0050] The shape of the cross section perpendicular to the longitudinal axis direction x of the wire of the braided tube 20 is not particularly limited, and may be, for example, a circle, an ellipse, an oval, an egg, a D-shape, a triangle, a rectangle, a polygon, or a combination thereof. The braided tube 20 may also be made of a round wire or a flat wire. A flat wire is a wire material with both sides scraped off from a round wire.

[0051] The diameter of the wire of the braided tube 20 is, for example, preferably 5 to 110 μm, more preferably 10 to 100 μm, and even more preferably 15 to 90 μm. The diameter of the wire refers to the maximum length (maximum width) of the wire in a cross section perpendicular to the longitudinal axis direction x of the wire of the braided tube 20.

[0052] The linear member 60 may have a lumen extending in the longitudinal axis direction x, but is preferably solid and does not have a lumen, which allows the thickness of the linear member 60 to be reduced.

[0053] The linear member 60 may be made of any material, including, but not limited to, a metal, as long as it can push the tubular member 10 distally and pull it back proximally. The metal preferably includes, for example, stainless steel, titanium, a nickel-titanium alloy, a cobalt-chromium alloy, a tungsten alloy, or a combination thereof, and more preferably includes stainless steel.

[0054] The shape of the linear member 60 in a cross section perpendicular to the longitudinal axis direction x is preferably, for example, a square, rectangle, trapezoid, circle, D-shape, ellipse, egg shape, or oval shape, and more preferably a rectangle. The shape of the linear member 60 in a cross section perpendicular to the longitudinal axis direction x may be the same regardless of the position in the longitudinal axis direction x, or may be different depending on the position in the longitudinal axis direction x.

[0055] The wire diameter of the linear member 60 is, for example, preferably 100 to 650 μm, more preferably 150 to 600 μm, and even more preferably 200 to 550 μm. The wire diameter of the linear member 60 refers to the maximum length (maximum width) of the linear member 60 in a cross section perpendicular to the longitudinal axis direction x of the linear member 60. The wire diameter of the linear member 60 may be the same regardless of the position in the longitudinal axis direction x, or may be different depending on the position in the longitudinal axis direction x, and may have, for example, a portion that tapers from the proximal side to the distal side.

[0056] The extension catheter 1A may further include a handle member 70 fixed to the proximal end of the tubular member 10. An operator can grasp the handle member 70 to move the linear member 60 distally or proximally. The handle member 70 preferably contains a resin. The resin is preferably, for example, a polyolefin resin. The polyolefin resin preferably contains, for example, polyethylene, polypropylene, or a combination thereof.

[0057] This application claims the benefit of priority based on Japanese Patent Application No. 2024-52174, filed on March 27, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-52174 are incorporated herein by reference.

[0058] 1A Extension catheter 2 Second catheter 2a Proximal end of second catheter 2b Distal end of second catheter 2aP Opening at proximal end of second catheter 2bP Opening at distal end of second catheter 10 Cylindrical member 10a Proximal end of tubular member 10aP Proximal opening of tubular member 10b Distal end of tubular member 10bP Distal opening of tubular member 10H Large diameter section of tubular member 10La Proximal small diameter section of tubular member 10Lb Distal small diameter section of tubular member 20 Braided tube 20a Proximal end of braided tube 20b Distal end of braided tube 40 Outer layer 60 Linear member 60b Distal end of linear member 70 Handle K Length in the longitudinal direction of the tubular member in the section where the braided tube is arranged

Claims

1. An extension catheter that is inserted into a catheter and can protrude from an opening at the distal end of the catheter, comprising: a tubular member having an inner lumen extending in the longitudinal direction and having a proximal opening and a distal opening; and a linear member fixed to the tubular member and extending proximally from the tubular member, the tubular member having, in the longitudinal direction, a large diameter section, a proximal small diameter section proximal to the large diameter section, and a distal small diameter section distal to the large diameter section, a braided tube being disposed radially outside the tubular member for at least a part of the distal small diameter section and at least a part of the large diameter section, and in a vertical cross section of the tubular member in the longitudinal direction, the diameters of the inscribed circles for the outer edges of the proximal small diameter section and the distal small diameter section of the tubular member are smaller than the diameter of the inscribed circle for the outer edge of the large diameter section of the tubular member.

2. The extension catheter according to claim 1, wherein a braided tube is disposed radially outside said tubular member in at least a portion of said large diameter section of said tubular member and said proximal small diameter section of said tubular member.

3. The extension catheter according to claim 1, wherein when the length of the section in which the braided tube is disposed in the longitudinal axis direction of the tubular member is K, the large diameter section is disposed proximally of a position K / 2 in the longitudinal axis direction of the tubular member.

4. The extension catheter according to claim 1, wherein a hydrophilic coating layer is disposed on the surface of said distal small diameter section of said tubular member.

5. The extension catheter according to claim 4, wherein a hydrophilic coating layer is not provided on a portion of the surface of said large diameter section of said tubular member and on the surface of said proximal small diameter section of said tubular member.

6. The extension catheter according to claim 4, wherein a hydrophilic coating layer is not provided on the surface of said large diameter section of said tubular member and on the surface of said proximal small diameter section of said tubular member.

7. The extension catheter according to claim 4, wherein a hydrophilic coating layer is disposed on a portion of the surface of said large diameter section of said tubular member.

8. The extension catheter according to claim 1, wherein said linear member is fixed to said proximal small diameter section of said tubular member, and in a vertical cross section taken along the longitudinal axis of said tubular member, the outer edges of said distal small diameter section and said large diameter section of said tubular member have a circular shape, and the outer edge of said proximal small diameter section of said tubular member has an elliptical, oval or egg shape.

9. The extension catheter according to claim 1, wherein the linear member is fixed to a portion of the large diameter section and the proximal small diameter section of the tubular member, and in a vertical cross section taken along the longitudinal axis of the tubular member, the shape of the outer edge of the distal small diameter section of the tubular member is circular, and the shape of the outer edge of the portion of the large diameter section and the proximal small diameter section of the tubular member is elliptical, oval, or egg-shaped.

10. The extension catheter of claim 1, wherein the Shore D hardness of the large diameter section of the tubular member is greater than the Shore D hardness of the proximal small diameter section of the tubular member and the Shore D hardness of the distal small diameter section of the tubular member.

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