Catheter and catheter system

Abstract

An antegrade catheter (18) of a catheter system (10) is provided with a cylindrical first marker (26) that is disposed at the tip (24a) of a first catheter body (24). The first marker (26) is formed in a reverse tapered shape in which the diameter increases toward the tip of the first catheter body (24). In the axial direction of the first catheter body (24), the axial direction distance (L1) between the leading end (26b) of the first marker (26) and the leading end (24b) of the first catheter body (24) is 0.5 mm or less.

Description

Catheters and catheter systems

[0001] The present invention relates to a catheter and a catheter system to be inserted into a lumen of a living body.

[0002] Japanese Patent Application Laid-Open Publication No. 2010-279546 discloses a catheter system equipped with a radiopaque marker at its tip. The catheter system includes a flexible catheter body and a radiopaque marker embedded in the tip of the catheter body. The radiopaque marker is a cylindrical body made of a metal material.

[0003] When a lesion (stenosis) is found in a patient's lumen, the tip of the catheter is advanced along the lumen under X-ray contrast. The position of the catheter tip is confirmed using a contrast marker, and the tip of the catheter is delivered to the lesion to perform treatment.

[0004] When performing lower limb vascular treatment on a lesion in a patient's lower limb artery, for example, an antegrade catheter is inserted into the blood vessel first using an antegrade approach, and then another retrograde catheter is inserted into the blood vessel using a retrograde approach from the opposite direction to the antegrade catheter. By inserting the tip of the other retrograde catheter into the blood vessel relative to the tip of the antegrade catheter near the lesion, the tips of the antegrade catheter and retrograde catheter are positioned at predetermined positions near the lesion, and a balloon catheter is delivered to the lesion through the antegrade catheter.

[0005] The catheter of JP 2010-279546 A has a contrast marker located at a position away from the tip of the catheter body. Therefore, when the catheter of JP 2010-279546 A is used as an antegrade catheter and a retrograde catheter, it is difficult to align and insert the tip of the retrograde approach catheter with the tip of the catheter inserted by the antegrade approach under X-ray contrast.

[0006] (1) A first aspect of the present invention is a catheter that can be inserted into a lumen of a living body and advanced along the lumen, the catheter comprising: a tubular catheter body having a lumen; and a cylindrical marker that includes a radiopaque material and is disposed at the tip of the catheter body, the marker being formed in an inverted tapered shape that expands in diameter toward the tip of the catheter body, and the distance between the most distal end of the marker and the most distal end of the catheter body in the axial direction of the catheter body being 0.5 mm or less.

[0007] With this catheter, the axial distance between the most distal end of the marker located at the distal end of the catheter and the most distal end of the catheter body is 0.5 mm or less, so that the position of the catheter's distal end can be confirmed with high accuracy under radioscopy when the catheter is advanced along a lumen of a living body. Because the marker is formed in an inverted tapered shape, the marker can be easily identified based on its shape that can be confirmed under radioscopy, and the marker is prevented from falling off the catheter body.

[0008] (2) In the catheter described in (1) above, the catheter may be an antegrade catheter that advances along the lumen toward the peripheral side of the living body, or a retrograde catheter that advances along the lumen toward the central side of the living body and whose tip can be inserted into the tip of the antegrade catheter.

[0009] With this configuration, by providing a marker at the tip of the antegrade catheter or the tip of the retrograde catheter, it is easy to align the tip of the antegrade catheter with the tip of the retrograde catheter.

[0010] (3) In the catheter described in (1) above, the catheter may be an antegrade catheter that advances along the lumen toward the peripheral side of the living body.

[0011] (4) In the catheter described in (3) above, the tip portion of the catheter body may have an inner surface that is part of the lumen and has a reverse tapered shape that expands in diameter toward the tip, and the marker may be arranged along the inner surface.

[0012] With this configuration, when the tip of the retrograde catheter is inserted into the lumen of the tip of the antegrade catheter, the inner surface of the tip of the catheter body can improve the insertability of the tip of the antegrade catheter and the tip of the retrograde catheter into each other.

[0013] (5) In the catheter described in (1) above, the catheter may be a retrograde catheter that advances along the lumen toward the central side of the living body, and the tip of the retrograde catheter may be insertable into the lumen of the tip of an antegrade catheter that advances along the lumen toward the peripheral side of the living body, and the outer peripheral surface of the tip of the retrograde catheter may have a tapered outer surface portion that narrows in diameter toward the tip.

[0014] With this configuration, when the tip of the retrograde catheter is inserted into the lumen of the tip of the antegrade catheter, the outer surface portion can improve the insertability of the retrograde catheter relative to the antegrade catheter.

[0015] (6) A second aspect of the present invention is a catheter system including a catheter that can be inserted into a lumen of a living body and advanced along the lumen, the catheter system including an antegrade catheter that advances along the lumen toward the peripheral side of the living body, and a retrograde catheter that advances along the lumen toward the central side of the living body, the antegrade catheter including a tubular first catheter body having a first lumen, and a cylindrical first marker that includes a radiopaque material and is disposed at the distal end of the first catheter body, the first marker being formed in an inverse tapered shape that expands in diameter toward the distal end of the first catheter body, and the distal end of the first marker in the axial direction of the first catheter body is spaced apart from the distal end of the first catheter body. a distal end of the retrograde catheter that is insertable into the distal end of the antegrade catheter, the retrograde catheter comprising a tubular second catheter body having a second lumen, and a cylindrical second marker that includes a radiopaque material and is arranged at the distal end of the second catheter body, the second marker having an inverse tapered shape that expands in diameter toward the distal end of the second catheter body, the distal end of the second marker being arranged proximal to the distal end of the second catheter body, and the distance between the distal end of the second marker and the distal end of the second catheter body in the axial direction of the second catheter body being 0.5 mm or less.

[0016] (7) A third aspect of the present invention is a method for treating a lesion in a lumen using an antegrade catheter that advances along a lumen of a living body toward the peripheral side of the living body and a retrograde catheter that advances along the lumen toward the central side of the living body, wherein the antegrade catheter comprises a tubular first catheter body having a first lumen and a cylindrical first marker that includes a radiopaque material and is arranged at the distal end of the first catheter body, the first marker having an inverse tapered shape that expands in diameter toward the distal end of the first catheter body, and the distance between the distal end of the first marker and the distal end of the first catheter body in the axial direction of the first catheter body is 0.5 mm or less, and the retrograde catheter comprises a tubular second catheter body having a second lumen and a cylindrical first marker that includes a radiopaque material and is arranged at the distal end of the second catheter body. and a cylindrical second marker formed in a direction parallel to the distal end of the second catheter body, the second marker having an inverse tapered shape that expands in diameter toward the distal end of the second catheter body, the most distal end of the second marker being located closer to the proximal end than the most distal end of the second catheter body, the distance between the most distal end of the second marker and the most distal end of the second catheter body in the axial direction of the second catheter body being 0.5 mm or less, and when the antegrade catheter advances to the peripheral side and the retrograde catheter advances to the central side within the lumen of the living body, the positions of the first marker and the second marker are confirmed under radioscopy, thereby aligning the positions of the tip of the antegrade catheter and the tip of the retrograde catheter, and inserting the tip of the retrograde catheter into the tip of the antegrade catheter.

[0017] According to the present invention, a marker is disposed at the distal end of a catheter, and the axial distance between the most distal end of the marker and the most distal end of the catheter body is 0.5 mm or less. This allows the catheter tip position to be accurately confirmed under radioscopy as the catheter is advanced along a lumen of a living body. The marker is formed in an inverted tapered shape, which makes it easy to identify the marker based on its shape as seen under radioscopy and prevents it from falling off the catheter body.

[0018] FIG. 1 is a diagram showing the overall configuration of a catheter system according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing the tip of an antegrade catheter. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is an enlarged cross-sectional view showing the tip of a retrograde catheter. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4. FIG. 6 is an explanatory diagram showing the initial state when treatment is performed using the catheter system. FIG. 7 is an explanatory diagram showing the state in which the tip of the antegrade catheter has been delivered to the upstream end of the lesion (CTO). FIG. 8 is an explanatory diagram showing the state in which the tip of the retrograde catheter has been inserted into the tip of the antegrade catheter at the lesion (CTO).

[0019] 1 , a catheter system 10 according to this embodiment is used, for example, to treat a lesion 16 (such as a stenosis or an obstruction) occurring in a blood vessel 14 of a living body 12. Specifically, the catheter system 10 is used for lower limb vascular treatment, in which a CTO 16a (chronic total occlusion, lesion) occurring in a blood vessel 14 of the lower limb of the living body 12 is treated by an antegrade approach and a retrograde approach. Note that the catheter system 10 may also be used to treat a lesion 16 in a lumen other than a blood vessel 14, for example, in a biological organ such as a bile duct, trachea, esophagus, urethra, or other organ.

[0020] The catheter system 10 can be inserted into a blood vessel 14 of a living body 12 and advanced along the blood vessel 14. The catheter system 10 includes an antegrade catheter 18 used in an antegrade approach in treating blood vessels in the lower extremities, and another retrograde catheter 20 used in a retrograde approach in treating blood vessels in the lower extremities.

[0021] The antegrade catheter 18 is a catheter that advances along the blood vessels 14 of the living body 12 toward the peripheral side of the living body 12 (toward the ankle, in the direction of arrow A) in treatment of the blood vessels in the lower limbs.

[0022] As shown in FIG. 2, the antegrade catheter 18 includes a tubular first catheter body 24 having a first lumen 22 and a first marker 26 disposed at a distal end 24 a of the first catheter body 24 .

[0023] The first catheter body 24 is formed from a flexible resin material. Specifically, the first catheter body 24 is made of a resin material with a certain degree of flexibility, such as polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polystyrene, polyvinyl chloride, polyurethane, polyamide, or various elastomers such as polyolefin elastomers, polyester elastomers, polyurethane elastomers, and polyamide elastomers. These materials may be blended, layered, or arranged in multiple axial stages, or a reinforcement may be provided. The first lumen 22 is disposed inside the first catheter body 24. The first lumen 22 extends along the first catheter body 24. Because the antegrade catheter 18 is used to treat the CTO 16a, the distal end 24a of the first catheter body 24 is not made of a soft material such as rubber (elastomer), but has a hardness suitable for treating the CTO 16a.

[0024] The distal end 24a of the first catheter body 24 includes a first inner surface portion 28 and a first outer surface portion 30. The first inner surface portion 28 is a part of the first lumen 22 and has a reverse tapered shape that expands in diameter toward the distal end (direction of arrow A). In other words, the first inner surface portion 28 has a tapered shape that gradually reduces in diameter from the distal end 24b of the first catheter body 24 toward the proximal end. The distal end 24a of the first catheter body 24 is the end portion that is in the direction of advancement when the antegrade catheter 18 is inserted into and advanced through the blood vessel 14. The first inner surface portion 28 is disposed within a predetermined range from the distal end 24b of the first catheter body 24 toward the proximal end.

[0025] The first outer surface section 30 is disposed on the outer peripheral surface of the first catheter body 24. The first outer surface section 30 is tapered so that its diameter decreases toward the distal end (direction of arrow A) of the first catheter body 24. The first outer surface section 30 is disposed within a predetermined range from the distal end 24b of the first catheter body 24 toward the proximal end. In other words, the distal end section 24a of the first catheter body 24 gradually tapers toward the distal end 24b (distal direction, direction of arrow A).

[0026] 2, the first marker 26 is formed into a cylindrical shape (see FIG. 3) from a radiopaque material (e.g., gold, platinum, tungsten, or a mixture thereof). The first marker 26 enables the distal end position (leading end 24b) of the antegrade catheter 18 to be visible under X-ray (radiography) imaging within the living body 12.

[0027] The first marker 26 is embedded in the distal end 24a of the first catheter body 24. The first marker 26 is formed in an inverse tapered shape that expands in diameter toward the distal end of the first catheter body 24 (in the direction of arrow A). The first marker 26 is arranged along the first inner surface portion 28 of the first catheter body 24. The first inner surface portion 28 of the first catheter body 24 and the first marker 26 are approximately parallel. A portion of the first marker 26 may be exposed at the first inner surface portion 28. The inverse tapered shape of the first marker 26 prevents the first marker 26 from falling off from the distal end 24a of the first catheter body 24 toward the distal end (in the direction of arrow A).

[0028] The distal end 26a of the first marker 26 has a distal end 26b that is positioned distally (in the direction of arrow A). The distal end 26b of the first marker 26 is positioned proximal to the distal end 24b of the first catheter main body 24 (in the direction of arrow B). In the axial direction of the first catheter main body 24 (in the direction of arrows A and B), the axial distance L1 between the distal end 26b of the first marker 26 and the distal end 24b of the first catheter main body 24 is 0.5 mm or less. That is, the distal end 26b of the first marker 26 is positioned within 0.5 mm proximal to the distal end 24b of the first catheter main body 24 (in the direction of arrow B). The distal end 26b of the first marker 26 is not exposed to the outside from the distal end 24b of the first catheter main body 24. The axial length of the first marker 26 is, for example, approximately 0.5 mm to 1.0 mm along the extension direction of the first catheter main body 24.

[0029] 1, the proximal end of the first catheter body 24 is provided with a first hub 32. The first hub 32 is cylindrical. The proximal end of the first hub 32 is open.

[0030] In treating the blood vessels of the lower limbs, the retrograde catheter 20 advances along the blood vessel 14 of the living body 12 toward the central side of the living body 12 (toward the heart, in the direction of arrow B). When the retrograde catheter 20 advances toward the central side, the distal end 36a of the retrograde catheter 20 can be inserted into the distal end 24a of the antegrade catheter 18.

[0031] The retrograde catheter 20 comprises a tubular second catheter body 36 having a second lumen 34 and a second marker 38 disposed at a tip portion 36 a of the second catheter body 36 .

[0032] The second catheter body 36 is formed from a flexible resin material. Specifically, the second catheter body 36 is made of a resin material with a certain degree of flexibility, such as polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polystyrene, polyvinyl chloride, polyurethane, polyamide, or various elastomers such as polyolefin elastomers, polyester elastomers, polyurethane elastomers, and polyamide elastomers. These materials may be blended, layered, or arranged in multiple axial stages, or a reinforcing member may be provided. The diameter of the second catheter body 36 is smaller than the diameter of the first catheter body 24. The second lumen 34 is disposed inside the second catheter body 36. The second lumen 34 extends along the second catheter body 36. The second lumen 34 is a passage through which a guidewire 40 can be inserted. Since the retrograde catheter 20 is used to treat the CTO 16a, the tip 36a of the second catheter body 36 is not made of a soft material such as rubber (elastomer material) but has a hardness suitable for treating the CTO 16a.

[0033] 4, the distal end portion 36a of the second catheter body 36 includes a second inner surface portion 42 and a second outer surface portion 44. The second inner surface portion 42 is part of the second lumen 34 and has a reverse tapered shape that expands in diameter toward the distal end (in the direction of arrow B). In other words, the second inner surface portion 42 has a tapered shape that gradually reduces in diameter from the distal end 36b of the second catheter body 36 toward the proximal end.

[0034] The distal end 36a of the second catheter body 36 is the end that faces the direction of advancement (the direction of arrow B) when the retrograde catheter 20 is inserted and advanced into the blood vessel 14. The second inner surface portion 42 is disposed within a predetermined range from the distal end 36b of the second catheter body 36 toward the base end.

[0035] The second outer surface portion 44 is disposed on the outer peripheral surface of the second catheter body 36. The second outer surface portion 44 is tapered so that its diameter decreases toward the distal end (direction of arrow B) of the second catheter body 36. The second outer surface portion 44 is disposed within a predetermined range from the distal end 36b of the second catheter body 36 toward the proximal end. In other words, the distal end portion 36a of the second catheter body 36 gradually tapers toward the distal end 36b (distal end direction, direction of arrow B).

[0036] The second marker 38 is formed into a cylindrical shape from a radiopaque material (e.g., gold, platinum, tungsten, or a mixture thereof) (see FIG. 5 ). The second marker 38 enables the distal end position of the retrograde catheter 20 to be visualized in the living body 12 under X-ray (radiography) imaging.

[0037] The second marker 38 is embedded in the distal end 36a of the second catheter body 36. The second marker 38 is formed in an inverse tapered shape that widens in diameter toward the distal end of the second catheter body 36. The second marker 38 is arranged along the second inner surface 42 of the second catheter body 36. The second marker 38 and the second inner surface 42 of the second catheter body 36 are approximately parallel. A portion of the second marker 38 may be exposed at the second inner surface 42. The inverse tapered shape of the second marker 38 prevents the second marker 38 from falling off from the distal end 36a of the second catheter body 36 toward the distal end (direction of arrow B).

[0038] The distal end 38a of the second marker 38 has a distal end 38b that is positioned distally (in the direction of arrow B). The distal end 38b of the second marker 38 is positioned proximal (in the direction of arrow A) to the distal end 36b of the second catheter main body 36. In the axial direction of the second catheter main body 36 (in the direction of arrows A and B), the axial distance L2 between the distal end 38b of the second marker 38 and the distal end 36b of the second catheter main body 36 is 0.5 mm or less. That is, the distal end 38b of the second marker 38 is positioned within 0.5 mm proximal (in the direction of arrow A) from the distal end 36b of the second catheter main body 36. The distal end 38b of the second marker 38 is not exposed to the outside from the distal end 36b of the second catheter main body 36. The axial length of the second marker 38 is, for example, approximately 0.5 mm to 1.0 mm along the extension direction of the second catheter main body 36.

[0039] 1, the proximal end of the second catheter body 36 is provided with a second hub 46. The second hub 46 is cylindrical. The proximal end of the second hub 46 is open. The guide wire 40 can be inserted into the second lumen 34 through the second hub 46.

[0040] Next, a description will be given of a case where a lower limb blood vessel treatment is performed using the catheter system 10. Fig. 1 is a schematic cross-sectional view showing the peripheral portion of a CTO 16a (lesion 16) when the CTO 16a occurs in a blood vessel 14 of the lower limb.

[0041] In FIG. 1 , a CTO 16a occurs in the blood vessel 14 along the extension direction of the blood vessel 14, and the left side of the CTO 16a is the central side (heart side) and the upstream side of the blood flow. The right side of the CTO 16a is the peripheral side (ankle side) and the downstream side of the blood flow. Hereinafter, the blood vessel 14 upstream (left) of the CTO 16a will be referred to as the upstream blood vessel portion 14a, and the blood vessel 14 downstream (right) of the CTO 16a will be referred to as the downstream blood vessel portion 14b. The upstream blood vessel portion 14a is an artery with a relatively large diameter. The downstream blood vessel portion 14b is a peripheral blood vessel with a smaller diameter than the upstream blood vessel portion 14a.

[0042] The diameter of the antegrade catheter 18 is adapted to the diameter of the upstream blood vessel 14 a. The diameter of the retrograde catheter 20 is adapted to the diameter of the downstream blood vessel 14 b. In other words, the diameter of the antegrade catheter 18 is larger than the diameter of the retrograde catheter 20.

[0043] First, as shown in FIG. 6 , an antegrade approach is performed with the antegrade catheter 18 to the blood vessel 14 in the lower limb of the living body 12. A medical professional (not shown) percutaneously inserts the distal end 24 a of the antegrade catheter 18 into the upstream vascular section 14 a of the blood vessel 14. The distal end 24 a of the antegrade catheter 18 is advanced distally (in the direction of arrow A) along a guidewire (not shown) within the blood vessel 14 toward the CTO 16 a. At this time, the medical professional (not shown) can visually confirm the distal end position (distal end 24 b) of the antegrade catheter 18 while performing the procedure by visually confirming the first marker 26 on a display or the like under X-ray angiography. The cylindrical first marker 26 allows the first marker 26 to be visually recognized from any circumferential position of the distal end 24 a of the antegrade catheter 18 (see FIG. 3 ).

[0044] As shown in Figure 7, the tip 24a (leading edge 24b) of the antegrade catheter 18 is delivered along the upstream blood vessel 14a to the upstream end of the CTO 16a. The upstream end of the CTO 16a has a protruding portion 48 that is convex toward the upstream blood vessel 14a (in the direction of arrow B). The leading edge 24b of the antegrade catheter 18 comes into contact with the protruding portion 48. A medical professional (not shown) can confirm the position of the tip 24a of the antegrade catheter 18 on a display or the like using the first marker 26.

[0045] After the tip 24a of the antegrade catheter 18 is delivered to the upstream end of the CTO 16a, a retrograde approach is performed in which the tip 36a of the retrograde catheter 20 is delivered to the CTO 16a along the downstream vascular section 14b.

[0046] As shown in FIG. 1 , the distal end 36 a of the retrograde catheter 20 is percutaneously inserted into the downstream blood vessel portion 14 b of the blood vessel 14. At this time, a guidewire 40 is inserted through the second lumen 34 of the retrograde catheter 20. With the distal end of the guidewire 40 protruding distally (in the direction of arrow B) from the distal end 36 b of the retrograde catheter 20, the distal end 36 a of the retrograde catheter 20 is advanced centrally (in the direction of arrow B) along the guidewire 40 toward the CTO 16 a. The direction of advancement of the antegrade catheter 18 (first direction, toward the periphery) is opposite to the direction of advancement of the retrograde catheter 20 (second direction, toward the central). In other words, the distal end 36 a of the retrograde catheter 20 advances toward the distal end 24 a of the antegrade catheter 18.

[0047] The distal end 36a of the retrograde catheter 20 is delivered to the downstream end of the CTO 16a along the downstream blood vessel portion 14b. The downstream end of the CTO 16a has a recessed portion 50 recessed toward the upstream blood vessel portion 14a. The distal end 36b of the retrograde catheter 20 is inserted into the recessed portion 50 and contacts the bottom of the recessed portion 50. The bottom is located at the most upstream blood vessel portion 14a side of the recessed portion 50.

[0048] As shown in Figure 7, by further advancing the distal end 36a of the retrograde catheter 20, the distal end 36a advances from the recessed portion 50 into the interior of the CTO 16a. The distal end 36a (leading edge 36b) of the retrograde catheter 20 excavates the CTO 16a, forming a perforation 52. The perforation 52 is formed from the bottom of the recessed portion 50 toward the protruding portion 48. As the retrograde catheter 20 advances, the perforation 52 penetrates all the way to the upstream end (protruding portion 48) of the CTO 16a.

[0049] Because the upstream end of the CTO 16a is convex (projecting portion 48) toward the central side, it is difficult to excavate the CTO 16a toward the peripheral side with the antegrade catheter 18. On the other hand, because the downstream end of the CTO 16a is concave (depressed portion 50) toward the central side, it is easy to excavate the CTO 16a toward the central side with the retrograde catheter 20, and it is also easy to advance the CTO 16a or the vicinity of the center of the blood vessel 14.

[0050] A medical professional (not shown) confirms the relative positions of the first marker 26 of the antegrade catheter 18 and the second marker 38 of the retrograde catheter 20 under X-ray fluoroscopy, and aligns the first marker 26 and the second marker 38 so that they are positioned on a straight line along the extension direction (direction of arrows A and B) of the blood vessel 14. By aligning the positions of the first marker 26 and the second marker 38, the leading end 24b of the antegrade catheter 18 and the leading end 36b of the retrograde catheter 20 are positioned on a straight line at the CTO 16a.

[0051] As shown in Figure 8, by bringing the distal end 24a of the antegrade catheter 18 and the distal end 36a of the retrograde catheter 20 closer to each other, the distal end 24a (leading end 24b) of the antegrade catheter 18 advances along the perforation 52 into the CTO 16a. Inside the CTO 16a, the distal end 36a of the retrograde catheter 20 is inserted into the first lumen 22 of the distal end 24a of the antegrade catheter 18. At this time, because the perforation 52 is formed in the CTO 16a, the distal end 24a of the antegrade catheter 18 is smoothly inserted into the CTO 16a along the perforation 52. The distal end 24a of the antegrade catheter 18 expands the perforation 52 radially outward. The first outer surface portion 30 facilitates insertion of the antegrade catheter 18 into the perforation 52.

[0052] After the distal end 24a of the antegrade catheter 18 is placed at a predetermined position inside the CTO 16a, the retrograde catheter 20 is removed. A balloon catheter (not shown) is inserted into the first lumen 22 of the antegrade catheter 18 and delivered to the CTO 16a. The CTO 16a is treated with the balloon catheter. Alternatively, an antegrade guidewire (not shown) may be inserted into the first lumen 22 of the antegrade catheter 18, the antegrade catheter 18 may be removed, the antegrade guidewire may be left in place, and the balloon catheter may be delivered to the CTO 16a along the antegrade guidewire (not shown).

[0053] The insertion of the distal end 36a of the retrograde catheter 20 into the distal end 24a of the antegrade catheter 18 is not limited to being performed inside the CTO 16a. The distal end 36a of the retrograde catheter 20 may be inserted into the distal end 24a of the antegrade catheter 18 in the upstream blood vessel portion 14a or the downstream blood vessel portion 14b near the CTO 16a. Alternatively, by inserting only the guidewire 40 into the distal end 24a of the antegrade catheter 18 and arranging the guidewire 40, the first marker 26, and the second marker 38 coaxially, the retrograde catheter 20 can be easily pushed in and penetrate the perforation 52, so that the retrograde catheter 20 does not need to be advanced to the position where it is inserted into the distal end 24a of the antegrade catheter 18.

[0054] As described above, in the embodiment of the present invention, the axial distance L1 between the most distal end 26b of the first marker 26 disposed at the distal end 24a of the antegrade catheter 18 and the most distal end 24b of the first catheter body 24 is 0.5 mm or less, so that when the antegrade catheter 18 is advanced toward the peripheral side (direction of arrow A) along the blood vessel 14, the distal end position (most distal end 24b) of the antegrade catheter 18 can be accurately confirmed under X-ray angiography. The axial distance L2 between the most distal end 38b of the second marker 38 disposed at the distal end 36a of the retrograde catheter 20 and the most distal end 36b of the second catheter body 36 is 0.5 mm or less, so that when the retrograde catheter 20 is advanced toward the central side (direction of arrow B) along the blood vessel 14, the distal end position (most distal end 36b) of the retrograde catheter 20 can be accurately confirmed under X-ray angiography. Because the first and second markers 26, 38 are formed in an inverted tapered shape, the first and second markers 26, 38 are easy to identify based on the shape that can be seen under X-ray imaging, and the first and second markers 26, 38 are effectively prevented from falling off the first and second catheter bodies 24, 36.

[0055] By placing the first marker 26 at the tip 24a of the antegrade catheter 18 and the second marker 38 at the tip 36a of the retrograde catheter 20, it is easy to align the tip 24a (leading edge 24b) of the antegrade catheter 18 with the tip 36a (leading edge 36b) of the retrograde catheter 20.

[0056] In treating blood vessels in the lower extremities, when the distal end 36a of the retrograde catheter 20 is inserted into the first lumen 22 of the distal end 24a of the antegrade catheter 18, the first inner surface portion 28 of the first catheter body 24 allows the distal end 36a of the retrograde catheter 20 to be smoothly inserted into the first lumen 22. This improves the insertability of the distal end 24a of the antegrade catheter 18 and the distal end 36a of the retrograde catheter 20.

[0057] In lower limb vascular treatment, when the tip portion 36a of the retrograde catheter 20 is inserted into the first lumen 22 of the tip portion 24a of the antegrade catheter 18, the second outer surface portion 44 of the retrograde catheter 20 can improve the insertability of the retrograde catheter 20 into the first lumen 22.

[0058] The present invention is not limited to the above disclosure, and various configurations may be adopted without departing from the spirit of the present invention. For example, the lesion 16 does not have to be a typical CTO 16a, but may be a severe stenotic lesion where a certain amount of blood flow is observed, or may be a mild stenotic lesion to reduce the burden on the patient.

Claims

1. A catheter that is inserted into a lumen of a living organism and can advance along the lumen, The aforementioned catheter is A tubular catheter body having a lumen, A cylindrical marker containing a radiopaque material and positioned at the tip of the catheter body, Equipped with, The marker is formed in an inverse taper shape that widens in diameter toward the tip of the catheter body. A catheter in which the distance between the leading edge of the marker and the leading edge of the catheter body in the axial direction of the catheter body is 0.5 mm or less.

2. In the catheter according to claim 1, The catheter is an antegrade catheter that advances along the lumen toward the distal side of the living body, or a retrograde catheter that advances along the lumen toward the central side of the living body, with its tip being insertable into the tip of the antegrade catheter.

3. In the catheter according to claim 1, The catheter is an anterograde catheter that advances along the lumen toward the distal side of the living body.

4. In the catheter according to claim 3, The tip portion of the catheter body is part of the lumen and has an inversely tapered inner surface that widens in diameter toward the tip. A catheter in which the marker is positioned along the inner surface.

5. In the catheter according to claim 1, The catheter is a retrograde catheter that advances along the lumen toward the central side of the living body, The tip of the retrograde catheter is insertable into the lumen of the tip of the antegrade catheter, which advances along the lumen toward the distal side of the living body. A catheter wherein the outer circumferential surface of the tip of the retrograde catheter has a tapered outer surface portion that decreases in diameter toward the tip.

6. A catheter system comprising a catheter that is inserted into a lumen of a living organism and can advance along the lumen, The catheter system includes an antegrade catheter that advances along the lumen toward the distal side of the living body, A retrograde catheter that advances along the lumen toward the central side of the living body, Equipped with, The aforementioned anterograde catheter is A tubular first catheter body having a first lumen, A tubular first marker, comprising a radiopaque material and positioned at the tip of the first catheter body, Equipped with, The first marker is formed in an inverse taper shape that widens toward the tip of the first catheter body, The distance between the leading edge of the first marker and the leading edge of the first catheter body in the axial direction of the first catheter body is 0.5 mm or less. The tip of the retrograde catheter is insertable into the tip of the antegrade catheter. The aforementioned retrograde catheter is A tubular second catheter body having a second lumen, A tubular second marker, comprising a radiopaque material and positioned at the tip of the second catheter body, Equipped with, The second marker is formed in an inverse taper shape that widens toward the tip of the second catheter body, The leading edge of the second marker is positioned proximal to the leading edge of the second catheter body. A catheter system in which the distance between the leading edge of the second marker and the leading edge of the second catheter body in the axial direction of the second catheter body is 0.5 mm or less.