Catheters and catheter systems

Abstract

To provide a catheter that can be smoothly advanced. [Solution] The antegrade catheter 18 of the catheter system 10 has a cylindrical first marker 26 arranged at the distal end 24a of the first catheter body 24. The first marker is tapered so that its diameter decreases toward the distal end of the first catheter body. The retrograde catheter 20 of the catheter system has a cylindrical second marker 38 arranged at the distal end 36a of the second catheter body 36. The second marker is tapered so that its diameter decreases toward the distal end of the second catheter body.

Description

[Technical Field]

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

[0002] Patent Document 1 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 (stricture) 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 treat it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-279546 Summary of the Invention [Problem to be solved by the invention]

[0005] 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.

[0006] The catheter of Patent Document 1 has an inverse tapered shape in which the radiopaque marker expands in diameter toward the tip of the catheter body, resulting in a large difference in diameter between the tip of the catheter body and the tip of the radiopaque marker. Therefore, when the catheter of Patent Document 1 is used as an antegrade catheter and a retrograde catheter, it is difficult to align and insert the tip of the retrograde catheter with the tip of the catheter inserted via the antegrade approach while checking the tip position of the radiopaque marker under X-ray contrast.

[0007] Furthermore, when the tip of the catheter is inserted into a complex lesion accompanied by calcification, the tip of the catheter may come into contact with the hardened lesion, causing the tip of the catheter to break.

[0008] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0009] (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 outer peripheral surface of the tip of the catheter body having a tapered outer surface that narrows in diameter toward the tip, and the marker being tapered toward the tip of the catheter body.

[0010] With this catheter, the marker allows the position of the catheter tip to be confirmed with high accuracy under radioscopy as the catheter advances along a lumen of a living body. Because both the tip of the catheter body and the marker are tapered toward the tip, the difference in diameter between the tip of the catheter and the marker is small, allowing the position of the catheter tip to be confirmed with even higher accuracy. The marker increases the strength of the catheter tip and also allows the outer diameter of the catheter tip to be made thinner and sharper, thereby improving the catheter's penetration force into the stenosis.

[0011] (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.

[0012] 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 during the rendezvous technique.

[0013] (3) In the catheter according to (1) or (2) above, 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 may be 0.5 mm or less.

[0014] With this configuration, 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, making it possible to accurately confirm the most distal end position of the catheter under radioscopy.

[0015] (4) In the catheter described in any one of (1) to (3) above, the marker has a plurality of grooves provided at least at the tip of the marker, recessed radially inward from the outer peripheral surface of the marker, and provided circumferentially around the axis of the marker, and the cross-sectional shape of the marker perpendicular to the axis of the marker may change from the tip to the base end of the marker.

[0016] (5) In the catheter described in (4) above, the cross-sectional shape of the marker may be changed by the number of grooves at the base end of the marker being less than the number of grooves at the tip end of the marker.

[0017] (6) In the catheter described in (4) or (5) above, the depth of the groove portion relative to the outer surface of the marker at the base end of the marker may be shallower than the depth of the groove portion relative to the outer surface of the marker at the tip end of the marker, thereby changing the cross-sectional shape of the marker.

[0018] (7) In the catheter according to any one of (1) to (6) above, the surface roughness of the outer peripheral surface of the marker may be smaller at the base end of the marker than at the tip end of the marker.

[0019] With this configuration, when the catheter is advanced along a lumen of a living body, the contact resistance between the base end of the marker with the largest diameter and the lumen can be reduced, allowing the catheter to be advanced smoothly.

[0020] (8) 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 advance along the lumen, the catheter system including an antegrade catheter that advances along the lumen to a peripheral side of the living body, and a retrograde catheter that advances along the lumen to a 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 a distal end of the first catheter body, the distal end of the first catheter body being tapered toward the distal end of the first catheter body. a distal end of the retrograde catheter is insertable into the distal end of the antegrade catheter, the retrograde catheter comprises a tubular second catheter body having a second lumen, and a cylindrical second marker comprising a radiopaque material and disposed at the distal end of the second catheter body, the distal end of the second catheter body being tapered toward the distal end of the second catheter body, and the second marker being tapered toward the distal end of the second catheter body.

[0021] According to this catheter system, when the antegrade catheter and the retrograde catheter are advanced along a lumen of a living body and the tip of the retrograde catheter is inserted into the tip of the antegrade catheter, the tip positions of the first and second catheter bodies can be accurately confirmed under radioscopy using the first and second markers. Because the first marker is tapered toward the tip, the difference in diameter between the tip of the first catheter body and the first marker is small. Because the second marker is tapered toward the tip, the difference in diameter between the tip of the second catheter body and the second marker is small. This allows the tip positions of the first and second catheter bodies to be confirmed with even greater accuracy, and the tip of the retrograde catheter can be reliably inserted into the tip of the antegrade catheter. [Effects of the Invention]

[0022] According to the present invention, the catheter is provided with a cylindrical marker disposed at the distal end of the catheter body, and the marker allows the position of the catheter tip to be confirmed with high accuracy under radioscopy when the catheter is advanced along a lumen of a living body. Since both the distal end of the catheter body and the marker are tapered toward the distal end, the difference in diameter between the catheter tip and the marker is small, allowing the position of the catheter tip to be confirmed with even higher accuracy. The marker also enhances the strength of the catheter tip. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a catheter system according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the distal end of the antegrade catheter. [Figure 3] Fig. 3A is a cross-sectional view taken along line IIIA-IIIA in Fig. 2. Fig. 3B is a cross-sectional view taken along line IIIB-IIIB in Fig. 2. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing the distal end of the retrograde catheter. [Figure 5]Fig. 5A is a cross-sectional view taken along line VA-VA in Fig. 4. Fig. 5B is a cross-sectional view taken along line VB-VB in Fig. 4. [Figure 6] FIG. 6 is an explanatory diagram showing the initial state when treatment is performed using the catheter system. [Figure 7] FIG. 7 is an explanatory diagram showing the state in which the distal end of the antegrade catheter has been delivered to the upstream end of the lesion (CTO). [Figure 8] FIG. 8 is an explanatory diagram showing the state in which the tip portion of a retrograde catheter is inserted into the tip portion of an antegrade catheter at a lesion (CTO). [Figure 9] FIG. 9 is an enlarged cross-sectional view showing the distal end of an antegrade catheter according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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) that has occurred in a blood vessel 14 of a living body 12. Specifically, the catheter system 10 is used in lower limb vascular treatment to treat a CTO 16a (chronic total occlusion, lesion) that has occurred in a blood vessel 14 of the lower limb of the living body 12 using 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.

[0025] 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.

[0026] The antegrade catheter 18 is a catheter that advances along the blood vessel 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 the same direction as the blood flow during treatment of the blood vessels in the lower limbs.

[0027] 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 .

[0028] 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 (e.g., polyethylene, polypropylene, ethylene-propylene copolymer), polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate), polystyrene, polyvinyl chloride, polyurethane, polyamide, or various elastomers (e.g., polyolefin elastomers, polyester elastomers, polyurethane elastomers, polyamide elastomers), and the like. These materials may be blended, layered, or arranged in multiple layers in the axial direction. A braided metal reinforcement member (e.g., stainless steel wire) may also 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 a 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 a CTO 16a.

[0029] The distal end 24a of the first catheter body 24 is the end that faces the direction of advancement when the antegrade catheter 18 is inserted and advanced within the blood vessel 14. The distal end 24a of the first catheter body 24 includes a first outer surface portion 28.

[0030] The first outer surface portion 28 is disposed on the outer peripheral surface of the first catheter body 24. The first outer surface portion 28 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 portion 28 is disposed within a predetermined range from the distal end 24b of the first catheter body 24 toward the base end. In other words, the distal end portion 24a of the first catheter body 24 gradually tapers toward the distal end 24b (distal direction, direction of arrow A).

[0031] As shown in Fig. 2, the first marker 26 is formed into a cylindrical shape (see Fig. 3A) from a radiopaque metallic material (e.g., gold, platinum, iridium, tungsten, or an alloy thereof). The first marker 26 enables the distal end position (leading end 24b) of the antegrade catheter 18 to be visualized under X-ray (radiography) imaging within the living body 12. In this embodiment, the first marker 26 is formed from a platinum-iridium alloy.

[0032] The first marker 26 is embedded in the distal end portion 24a of the first catheter body 24. The first marker 26 is formed in a tapered shape that reduces 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 outer surface portion 28 of the first catheter body 24. The first outer 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 outer surface portion 28.

[0033] The first outer peripheral surface 30 of the first marker 26 has a plurality of marker grooves 31a. The cross-sectional shape of the first marker 26, which is perpendicular to the axial direction of the first marker 26, changes from the tip end 26a to the base end 26c of the first marker 26.

[0034] As shown in FIGS. 3A and 3B, the multiple marker grooves 31a are spaced apart from one another in the circumferential direction of the first marker 26, centered on the axis of the first marker 26. Each of the marker grooves 31a is recessed radially inward from the first outer peripheral surface 30 of the first marker 26. The number of marker grooves 31a varies from the distal end 26a to the proximal end 26c of the first marker 26. That is, the distal end 26a of the first marker 26 shown in FIG. 3A has the greatest number of marker grooves 31a, while the proximal end 26c of the first marker 26 shown in FIG. 3B has the least number of marker grooves 31a. As a result, the cross-sectional shape of the first marker 26 perpendicular to the axial direction varies from the distal end 26a to the proximal end 26c of the first marker 26.

[0035] 2, the radial depth of the marker groove 31a relative to the first outer peripheral surface 30 of the first marker 26 varies from the distal end 26a to the proximal end 26c of the first marker 26. The depth of the marker groove 31a is deepest at the distal end 26a of the first marker 26, and shallowest at the proximal end 26c of the first marker 26. In other words, the depth of the marker groove 31a gradually decreases from the distal end 26a to the proximal end 26c of the first marker 26, and the cross-sectional shape perpendicular to the axial direction of the first marker 26 varies from the distal end 26a to the proximal end 26c of the first marker 26.

[0036] 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.

[0037] 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.

[0038] In treating the blood vessels of the lower extremities, the retrograde catheter 20 advances toward the central side of the living body 12 (toward the heart, in the direction of arrow B), which is the opposite direction to the blood flow, along the blood vessels 14 of the living body 12. When the retrograde catheter 20 advances toward the central side, the tip 36a of the retrograde catheter 20 can be inserted into the tip 24a of the antegrade catheter 18 (see FIG. 8).

[0039] The retrograde catheter 20 comprises a tubular second catheter body 36 having a second lumen 34 and a second marker 38 disposed at a distal end 36 a of the second catheter body 36 .

[0040] 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 (e.g., polyethylene, polypropylene, ethylene-propylene copolymer), polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate), polystyrene, polyvinyl chloride, polyurethane, polyamide, or various elastomers (e.g., polyolefin elastomers, polyester elastomers, polyurethane elastomers, polyamide elastomers), and the like. These materials may be blended, layered, or arranged in multiple axial layers. A braided metal reinforcing element (e.g., stainless steel wire) may also be included. 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 passageway through which a guidewire 40 can be inserted. Since the retrograde catheter 20 is used to treat a CTO 16a, the tip portion 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 a CTO 16a.

[0041] The tip portion 36a of the second catheter body 36 is the end portion 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. As shown in FIG. 4 , the tip portion 36a of the second catheter body 36 includes a second outer surface portion 42.

[0042] The second outer surface portion 42 is disposed on the outer peripheral surface of the second catheter body 36. The second outer surface portion 42 has a tapered shape that reduces in diameter toward the distal end (direction of arrow B) of the second catheter body 36. The second outer surface portion 42 is disposed within a predetermined range from the distal end 36b of the second catheter body 36 toward the base 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).

[0043] As shown in Fig. 4, the second marker 38 is formed into a cylindrical shape from a radiopaque metal material (e.g., gold, platinum, iridium, tungsten, or a mixture thereof) (see Fig. 5A). The second marker 38 enables the distal end position of the retrograde catheter 20 to be visualized within the living body 12 under X-ray (radiography) imaging. In this embodiment, the second marker 38 is formed from a platinum-iridium alloy.

[0044] The second marker 38 is embedded in the distal end portion 36a of the second catheter body 36. The second marker 38 is formed in a tapered shape that reduces in diameter toward the distal end of the second catheter body 36. The second marker 38 is arranged along the second outer surface portion 42 of the second catheter body 36. The second marker 38 and the second outer surface portion 42 of the second catheter body 36 are approximately parallel. A portion of the second marker 38 may be exposed at the second outer surface portion 42.

[0045] The second outer surface 44 of the second marker 38 has a plurality of marker grooves 31b. The cross-sectional shape of the second marker 38, which is perpendicular to the axial direction of the second marker 38, changes from the tip end 38a to the base end 38c of the second marker 38.

[0046] As shown in FIGS. 5A and 5B, the multiple marker grooves 31b are spaced apart from one another in the circumferential direction of the second marker 38, centered on the axis of the second marker 38. Each of the marker grooves 31b is recessed radially inward from the second outer peripheral surface 44 of the second marker 38. The number of marker grooves 31b varies from the distal end 38a to the proximal end 38c of the second marker 38. That is, the distal end 38a of the second marker 38 shown in FIG. 5A has the greatest number of marker grooves 31b, while the proximal end 38c of the second marker 38 shown in FIG. 5B has the least number of marker grooves 31b. As a result, the cross-sectional shape of the second marker 38 perpendicular to the axial direction varies from the distal end 38a to the proximal end 38c of the second marker 38.

[0047] 4, the radial depth of the marker groove 31b relative to the second outer peripheral surface 44 of the second marker 38 varies from the distal end 38a to the proximal end 38c of the second marker 38. The depth of the marker groove 31b is deepest at the distal end 38a of the second marker 38, and shallowest at the proximal end 38c of the second marker 38. In other words, the depth of the marker groove 31b gradually decreases from the distal end 38a to the proximal end 38c of the second marker 38, and as a result, the cross-sectional shape of the second marker 38 perpendicular to the axial direction varies from the distal end 38a to the proximal end 38c of the second marker 38.

[0048] The distal end 38a of the second marker 38 has a distal end 38b that is positioned distalmost (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.

[0049] As shown in Figure 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. A guidewire 40 can be inserted into the second lumen 34 through the second hub 46.

[0050] 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) that has occurred in a blood vessel 14 of a lower limb.

[0051] In FIG. 1, a CTO 16a is present in the blood vessel 14 along its extension direction, and the left side of the CTO 16a is the central side (heart side) and upstream side of the blood flow. The right side of the CTO 16a is the peripheral side (ankle side) and 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.

[0052] The diameter of the antegrade catheter 18 is suited to the diameter of the upstream blood vessel 14a. The diameter of the retrograde catheter 20 is suited to the diameter of the downstream blood vessel 14b. That is, the diameter of the antegrade catheter 18 is larger than the diameter of the retrograde catheter 20, but the diameter of the antegrade catheter 18 may be smaller than the diameter of the retrograde catheter 20 depending on the shape and hardness of the lesion 16. Alternatively, the antegrade catheter 18 may be rendezvoused with a guidewire alone advanced retrogradely, in the opposite direction to the blood flow, or the retrograde catheter 20 may be rendezvoused with a guidewire alone advanced antegradely, in the same direction as the blood flow.

[0053] First, as shown in FIG. 6 , an antegrade approach is performed with an antegrade catheter 18 into a blood vessel 14 in the lower limb of a living body 12. A medical professional (not shown) percutaneously inserts the distal end 24a of the antegrade catheter 18 into the upstream vascular section 14a of the blood vessel 14. The distal end 24a 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 16a. At this time, the medical professional (not shown) can visually confirm the distal end position (leading edge 24b) of the antegrade catheter 18 by visually confirming the first marker 26 on a display or the like under X-ray angiography, thereby performing the procedure. The cylindrical first marker 26 allows the first marker 26 to be visually recognized from any circumferential position of the distal end 24a of the antegrade catheter 18 (see FIG. 3A ).

[0054] 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.

[0055] After the tip 24a of the antegrade catheter 18 is delivered to the upstream end of the CTO 16a, a retrograde approach is performed to deliver the tip 36a of the retrograde catheter 20 to the CTO 16a along the downstream blood vessel portion 14b; however, a retrograde approach may be performed first to deliver the tip 36a of the retrograde catheter 20 to the CTO 16a, and then the tip 24a of the antegrade catheter 18 may be delivered to the upstream end of the CTO 16a.

[0056] As shown in FIG. 1 , the distal end 36a of the retrograde catheter 20 is percutaneously inserted into the downstream blood vessel portion 14b 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 36b of the retrograde catheter 20, the distal end 36a of the retrograde catheter 20 is advanced centrally (in the direction of arrow B) along the guidewire 40 toward the CTO 16a. 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 36a of the retrograde catheter 20 advances toward the distal end 24a of the antegrade catheter 18.

[0057] The distal end 36a of the retrograde catheter 20 is delivered along the downstream blood vessel portion 14b to the downstream end of the CTO 16a. The downstream end of the CTO 16a has a recessed portion 50 that is 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, which is located closest to the upstream blood vessel portion 14a.

[0058] As shown in Figure 7, by further advancing the distal end 36a of the retrograde catheter 20, the distal end 36a advances from the depression 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 depression 50 toward the protrusion 48. As the retrograde catheter 20 advances, the perforation 52 penetrates all the way to the upstream end (protrusion 48) of the CTO 16a.

[0059] If the upstream end of the CTO 16a is convex (projecting portion 48) toward the central side, it may be difficult to excavate the CTO 16a toward the peripheral side with the antegrade catheter 18. On the other hand, if the downstream end of the CTO 16a is concave (depressed portion 50) toward the central side, it may be easy to excavate the CTO 16a toward the central side with the retrograde catheter 20, and it may also be easy to advance the CTO 16a or the vicinity of the center of the blood vessel 14.

[0060] 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 edge 24b of the antegrade catheter 18 and the leading edge 36b of the retrograde catheter 20 are positioned on a straight line at the CTO 16a.

[0061] As shown in FIG. 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 edge 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 a perforation 52 has been 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 tapered first outer surface portion 28 facilitates insertion of the antegrade catheter 18 into the perforation 52.

[0062] 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 using the balloon catheter. Note that 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). Alternatively, the antegrade catheter 18 may be removed while the antegrade guidewire (not shown) is left in place, and a guiding catheter with a larger inner and outer diameter than the antegrade catheter 18 may be inserted. A treatment catheter such as a balloon catheter may then be inserted into the guiding catheter and delivered to the CTO 16a, thereby treating the lesion 16.

[0063] Note that 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 14a or downstream blood vessel 14b near the CTO 16a. Alternatively, 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 makes it easier to push the retrograde catheter 20 in. If the perforation 52 is penetrated in this way, it is not necessary to advance the retrograde catheter 20 to the position where it should be inserted into the distal end 24a of the antegrade catheter 18.

[0064] This embodiment has the following advantages.

[0065] As shown in FIG. 1 , the antegrade catheter 18 includes a cylindrical first marker 26 disposed at the distal end 24a of the first catheter body 24, and the outer peripheral surface of the distal end 24a of the first catheter body 24 has a tapered first outer surface portion 28 that tapers toward the distal end. The first marker 26 is tapered toward the distal end of the first catheter body 24. This allows the distal end position of the antegrade catheter 18 to be accurately confirmed under fluoroscopy using the first marker 26 when the antegrade catheter 18 is advanced along the blood vessel 14 (lumen) of the living body 12. Because the distal end 24a of the first catheter body 24 and the first marker 26 are both tapered toward the distal end, the difference in diameter between the distal end of the antegrade catheter 18 and the first marker 26 is small, allowing the distal end position of the antegrade catheter 18 to be confirmed with even greater accuracy.

[0066] The first marker 26 made of a radiopaque material (metal material) can increase the strength of the tip of the first catheter body 24. This allows the antegrade catheter 18 to be advanced along the blood vessel 14 of the living body 12, and when the tip of the antegrade catheter 18 enters a complex lesion accompanied by calcification, the tip can effectively puncture the hardened lesion 16 (CT0 16a). When the tip of the antegrade catheter 18 comes into contact with the lesion 16, damage to the tip portion 24a of the first catheter body 24 is prevented.

[0067] The retrograde catheter 20 includes a cylindrical second marker 38 disposed at the distal end 36a of the second catheter body 36, and the outer peripheral surface of the distal end 36a of the second catheter body 36 has a tapered second outer surface portion 42 that tapers in diameter toward the distal end. The second marker 38 is tapered toward the distal end of the second catheter body 36. This allows the second marker 38 to accurately confirm the distal end position of the retrograde catheter 20 under fluoroscopy when the retrograde catheter 20 is advanced along the blood vessel 14 (lumen) of the living body 12. Because the distal end 36a of the second catheter body 36 and the second marker 38 are both tapered toward the distal end, the difference in diameter between the distal end of the retrograde catheter 20 and the second marker 38 is small, allowing the distal end position of the retrograde catheter 20 to be confirmed with even greater accuracy.

[0068] The second marker 38, made of a radiopaque material (metallic material), increases the strength of the tip of the second catheter body 36. This allows the retrograde catheter 20 to be advanced along the blood vessel 14 of the living body 12, and when the tip of the retrograde catheter 20 enters a complex lesion accompanied by calcification, the tip can effectively puncture the hardened lesion 16 (CT0 16a). When the tip of the retrograde catheter 20 comes into contact with the lesion 16, damage to the tip 36a of the second catheter body 36 is prevented.

[0069] As shown in Figure 7, by providing a first marker 26 at the tip of the antegrade catheter 18 and a second marker 38 at the tip of the retrograde catheter 20, it is easy to align the tip of the antegrade catheter 18 with the tip of the retrograde catheter 20.

[0070] As shown in Fig. 2, 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. Therefore, 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. As shown in Fig. 4, 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. Therefore, 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.

[0071] The first marker 26 has a plurality of marker grooves 31a provided at least at the tip of the first marker 26, recessed radially inward from the first outer peripheral surface 30 of the first marker 26, and provided in the circumferential direction of the first marker 26 centered on the axis of the first marker 26. The cross-sectional shape of the first marker 26 perpendicular to the axis of the first marker 26 changes from the tip end 26a to the base end 26c of the first marker 26. As a result, the marker grooves 31a form recesses and protrusions on the first outer peripheral surface 30 of the first marker 26, and the recesses or protrusions overlap more in the circumferential direction of the first marker 26 at the tip end 26a than at the base end 26c of the first marker 26. As a result, the distal end 26a of the first marker 26 is more visible under X-ray imaging than the proximal end 26c, and the orientation of the antegrade catheter 18 having the first marker 26 can be easily determined, making it easier to distinguish between the antegrade catheter 18 and the retrograde catheter 20 when they rendezvous.

[0072] The second marker 38 has a plurality of marker grooves 31b provided at least at the tip of the second marker 38, recessed radially inward from the second outer peripheral surface 44 of the second marker 38, and provided in the circumferential direction of the second marker 38 centered on the axis of the second marker 38. The cross-sectional shape of the second marker 38 perpendicular to the axis of the second marker 38 changes from the tip end 38a to the base end 38c of the second marker 38. As a result, the marker grooves 31b form recesses and protrusions on the second outer peripheral surface 44 of the second marker 38, and the recesses or protrusions overlap more in the circumferential direction of the second marker 38 at the tip end 38a than at the base end 38c of the second marker 38. As a result, the distal end 38a of the second marker 38 is more visible under X-ray imaging than the proximal end 38c, and the orientation of the retrograde catheter 20 having the second marker 38 can be easily determined, making it easier to distinguish between the antegrade catheter 18 and the retrograde catheter 20 when they rendezvous.

[0073] The depth of the marker groove 31a, relative to the first outer peripheral surface 30 of the first marker 26, at the base end 26c of the first marker 26 is shallower than the depth of the marker groove 31a, relative to the first outer peripheral surface 30 of the first marker 26, at the tip end 26a of the first marker 26. The cross-sectional shape of the first marker 26 changes from the tip to the base end of the first marker 26. The depth of the marker groove 31b, relative to the second outer peripheral surface 44 of the second marker 38, at the base end 38c of the second marker 38 is shallower than the depth of the marker groove 31b, relative to the second outer peripheral surface 44 of the second marker 38, at the tip end 38a of the second marker 38. The cross-sectional shape of the second marker 38 changes from the tip end 38a of the second marker 38 to the base end 38c of the second marker 38.

[0074] As a result, the marker groove 31a is deeper at the distal end 26a than at the proximal end 26c of the first marker 26, so the distal end 26a of the first marker 26 is more visible under X-ray imaging than the proximal end 26c of the first marker 26, and the orientation of the antegrade catheter 18 having the first marker 26 can be easily determined. As the marker groove 31b is deeper at the distal end 38a than at the proximal end 38c of the second marker 38, the distal end 38a of the second marker 38 is more visible under X-ray imaging than the proximal end 38c of the second marker 38, and the orientation of the retrograde catheter 20 having the second marker 38 can be easily determined. Therefore, when the antegrade catheter 18 and the retrograde catheter 20 rendezvous, the antegrade catheter 18 and the retrograde catheter 20 can be more easily distinguished.

[0075] 3A and 3B, the number of marker grooves 31a at the proximal end 26c of the first marker 26 is smaller than the number of marker grooves 31a at the distal end 26a of the first marker 26, so that the cross-sectional shape of the first marker 26 changes from the distal end 26a to the proximal end 26c of the first marker 26. The number of marker grooves 31b at the proximal end 38c of the second marker 38 is smaller than the number of marker grooves 31b at the distal end 38a of the second marker 38, so that the cross-sectional shape of the second marker 38 changes from the distal end 38a to the proximal end 38c of the second marker 38. This allows the orientation (direction) of the distal end 26a and proximal end 26c of the first marker 26 to be identified based on the number of marker grooves 31a, making it easy to identify the orientation of the antegrade catheter 18. The orientation (direction) of the distal end 38a and proximal end 38c of the second marker 38 can be identified based on the number of marker grooves 31b, making it easy to identify the orientation of the retrograde catheter 20. Therefore, when the antegrade catheter 18 and the retrograde catheter 20 rendezvous, the antegrade catheter 18 and the retrograde catheter 20 can be more easily identified.

[0076] A first marker 62 of a catheter system 60 according to a modified example shown in Fig. 9 has first and second surfaces 641, 642 with different surface roughness on a first outer peripheral surface 64. Below, an antegrade catheter 68 having a first marker 62 and a first catheter body 66 as shown in Fig. 9 will be described, but a similar configuration can also be applied to a retrograde catheter having a second marker.

[0077] The first marker 62 is provided on a first outer surface portion 661 of the first catheter body 66 and is embedded in the first outer surface portion 661. A first outer peripheral surface 64 of the first marker 62 is exposed to the outside of the first catheter body 66. The first and second surfaces 641, 642 are provided circumferentially outward of the first outer peripheral surface 64 of the first marker 62.

[0078] The first surface 641 is provided, for example, on the first outer peripheral surface 64 in a range from the tip end 62a to near the base end of the first marker 62. The surface roughness of the first marker 62 gradually decreases from the tip end 62a to the base end 62b of the first marker 62. The surface roughness of the first surface 641 may be approximately uniform in the axial direction of the first marker 62.

[0079] The second surface 642 is disposed in the proximal direction of the first surface 641 and, together with the first surface 641, constitutes the first outer peripheral surface 64. The second surface 642 extends from the proximal end 62b of the first marker 62 toward the distal end. The second surface 642 is disposed only in the vicinity of the proximal end 62b of the first marker 62. The surface roughness of the second surface 642 may be smaller than the surface roughness of the first surface 641 or may be the same as the surface roughness of the first surface 641. In other words, the surface of the second surface 642 may be smoother than the surface of the first surface 641, and the surfaces of the second surface 642 and the first surface 641 may be approximately uniform.

[0080] The modified example has the following effects.

[0081] 9 , when the antegrade catheter 68 is advanced along the blood vessel 14 of the living body 12, if the surface roughness of the first surface 641 increases from the second surface 642 disposed at the base end 62b of the tapered first marker 62 having the largest diameter to the tip end 62a of the first marker 62, the contact resistance between the first outer surface portion 661 at the base end of the first catheter main body 66 and the blood vessel 14 can be reduced accordingly. Therefore, the antegrade catheter 68 (first catheter main body 66) can be advanced smoothly along the blood vessel 14.

[0082] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0083] 10, 60...catheter system 12... Living organisms 14...Vessel 18, 68...antegrade catheter 20...Retrograde catheter 22...1st lumen 24, 66...First catheter body 26, 62...First marker 28, 661...first outer surface part 34...2nd lumen 36...Second catheter body 38...Second marker 40...Guidewire 42…Second outer surface part

Claims

1. A catheter that can be inserted into a lumen of a living body and advanced along the lumen, The catheter comprises: a tubular catheter body having a lumen; a cylindrical marker including a radiopaque material and disposed at the distal end of the catheter body; Equipped with The outer peripheral surface of the distal end portion of the catheter body has a tapered outer surface portion whose diameter decreases toward the distal end, A catheter, wherein the marker is formed in a tapered shape toward the distal end of the catheter body.

2. The catheter of claim 1, The catheter is 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.

3. The catheter according to claim 1 or 2, A catheter, wherein 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 is 0.5 mm or less.

4. The catheter according to claim 1 or 2, The marker has a plurality of grooves provided at least at the tip of the marker, recessed radially inward from the outer circumferential surface of the marker, and provided in the circumferential direction of the marker centered on the axis of the marker, A catheter in which the cross-sectional shape of the marker, perpendicular to the axis of the marker, changes from the tip to the base end of the marker.

5. The catheter according to claim 4, A catheter in which the number of grooves at the base end of the marker is less than the number of grooves at the tip end of the marker, thereby changing the cross-sectional shape of the marker.

6. The catheter according to claim 4, A catheter in which the depth of the groove portion relative to the outer surface of the marker at the base end of the marker is shallower than the depth of the groove portion relative to the outer surface of the marker at the tip end of the marker, thereby changing the cross-sectional shape of the marker.

7. The catheter according to claim 1 or 2, A catheter in which the surface roughness of the outer peripheral surface of the marker is smaller at the base end of the marker than at the tip end of the marker.

8. 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 includes an antegrade catheter that advances along the lumen toward the peripheral side of the living body; a retrograde catheter that advances along the lumen toward the central side of the living body; Equipped with The antegrade catheter comprises: a first tubular catheter body having a first lumen; a cylindrical first marker including a radiopaque material and disposed at a distal end of the first catheter body; Equipped with the distal end portion of the first catheter body is tapered toward the distal end of the first catheter body, the first marker is tapered toward the distal end of the first catheter body, the distal end of the retrograde catheter is insertable into the distal end of the antegrade catheter; The retrograde catheter comprises: a second tubular catheter body having a second lumen; a second marker having a cylindrical shape and including a radiopaque material and disposed at the distal end of the second catheter body; Equipped with the distal end portion of the second catheter body is tapered toward the distal end of the second catheter body, A catheter system, wherein the second marker is formed in a tapered shape toward the distal end of the second catheter body.

Images