Catheter

Abstract

Provided is a catheter with improved backup force, pushability, and blood vessel selectivity.　A catheter (20) has a tubular body (21) having a lumen (23) extending therethrough in the longitudinal direction, the tubular body (21) comprising: a first small-diameter segment (31) having a curved portion (38) positioned at the tip-end and curving with a central angle of 180° or more; a first tapered segment (32) having an outer diameter gradually increasing, in a taper, from the proximal end of the first small-diameter segment (31) toward the proximal side; a first large-diameter segment (33) having a uniform outer diameter (D2) from the proximal end of the first tapered segment (32) toward the proximal side; a second tapered segment (34) having an outer diameter gradually decreasing, in a taper, from the proximal end of the first large-diameter segment (33) toward the proximal side; a second small-diameter segment (35) having a uniform outer diameter (D3) from the proximal end of the second tapered segment (34) toward the proximal side; a third tapered segment (36) having an outer diameter gradually increasing, in a taper, from the proximal end of the second small-diameter segment (35) toward the proximal side; and a second large-diameter segment (37) having a uniform outer diameter (D4) from the proximal end of the third tapered segment (36) toward the proximal side.

Description

catheter

[0001] The present invention relates to a catheter.

[0002] In the treatment of blood vessels, procedures using catheters are performed (see, for example, Patent Document 1). For example, in a procedure for aspirating a thrombus, in order to deliver a thrombus aspiration catheter to the target location, a blood vessel is first secured by puncturing it through the skin, and a contrast catheter is then inserted into the blood vessel together with a guidewire and delivered to the vicinity of the lesion. Next, the contrast catheter is removed, leaving the guidewire behind. A dilator is attached to the inside of the thrombus aspiration catheter, and the thrombus is delivered along the guidewire to the vicinity of the lesion. After this, the dilator is removed, leaving the thrombus aspiration catheter behind, and the thrombus is aspirated using the thrombus aspiration catheter. For this reason, performing a procedure using a thrombus aspiration catheter requires many steps and a large number of instruments. It is difficult to use a thrombus aspiration catheter from the beginning without a contrast catheter, because the thrombus aspiration catheter has a large outer diameter, making it difficult to bend, resulting in low vascular selectivity.

[0003] WO 2009 / 014723

[0004] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a catheter that can improve backup force, pushability, and vascular selectivity.

[0005] The above object is achieved by the invention described in (1) below. (1) A catheter according to the present invention is a catheter having a tubular body with a lumen penetrating in the longitudinal direction, the tubular body comprising: a first small diameter section having a curved portion located at a distal end and bent at an angle of 180 degrees or more; a first tapered section having an outer diameter that increases in a tapered manner from a proximal end of the first small diameter section in a proximal direction; a first large diameter section having a constant outer diameter from the proximal end of the first tapered section in a proximal direction; a second tapered section having an outer diameter that decreases in a tapered manner from the proximal end of the first large diameter section in a proximal direction; a second small diameter section having a constant outer diameter from the proximal end of the second tapered section in a proximal direction; a third tapered section having an outer diameter that increases in a tapered manner from the proximal end of the second small diameter section in a proximal direction; and a second large diameter section having a constant outer diameter from the proximal end of the third tapered section in a proximal direction.

[0006] The catheter described in (1) above can improve blood vessel selectivity by virtue of the curved portion of the first small diameter section. Furthermore, the catheter can improve its backup force and pushability by virtue of the first large diameter section and the second large diameter section, while improving its blood vessel selectivity by virtue of the second small diameter section between the first large diameter section and the second large diameter section, thereby partially increasing its flexibility. Therefore, the catheter can improve its backup force, pushability, and blood vessel selectivity.

[0007] (2) In the catheter described in (1) above, the first tapered portion may be longer than the second tapered portion and longer than the third tapered portion in the longitudinal direction. This allows the first tapered portion to have a gentler taper, improving the insertability and safety of the living body that is the contact target. Furthermore, because the second tapered portion and the third tapered portion are shorter than the first tapered portion, they are less likely to interfere with the bending of other devices into which the catheter is inserted.

[0008] (3) In the catheter described in (1) or (2) above, the outer diameter of the second small diameter section may be equal to or greater than the outer diameter of the first small diameter section, the outer diameter of the first large diameter section may be greater than the outer diameter of the second small diameter section, and the outer diameter of the second large diameter section may be equal to or greater than the outer diameter of the first large diameter section. This allows the catheter to improve blood vessel selectivity and reachability to a narrow region beyond a wide region by using the thinnest first small diameter section located at the distal end. Furthermore, the catheter can improve pushability and backup force by using the thick second large diameter section located at the proximal end.

[0009] (4) In the catheter according to any one of (1) to (3) above, the second small diameter section may have a length in the major axis direction of 60 mm to 140 mm, thereby allowing the second small diameter section between the first large diameter section and the second large diameter section to be appropriately curved.

[0010] (5) The catheter according to any one of (1) to (4) above may be a dilator that can be placed inside the pulmonary artery thrombus aspiration catheter, thereby enabling the pulmonary artery thrombus aspiration catheter to smoothly reach the pulmonary artery from the right atrium via the right ventricle.

[0011] Fig. 1 is a plan view showing a catheter system including a catheter according to the present embodiment; Fig. 2 is a cross-sectional view showing the distal end of the catheter according to the present embodiment; Fig. 3 is a schematic cross-sectional view illustrating an example of use of the catheter according to the present embodiment.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional proportions in the drawings may be exaggerated for convenience of explanation and may differ from the actual proportions. In the following description, the side of the catheter that is operated will be referred to as the "proximal end" and the side that is inserted into the living body will be referred to as the "distal end."

[0013] As shown in Fig. 1, a catheter 20 according to an embodiment of the present invention constitutes a catheter system 10 together with other devices, and is used as a dilator to allow a suction catheter 40 to reach a pulmonary artery 103 in the treatment of pulmonary thrombosis. The catheter system 10 is inserted, for example, from a femoral, knee, or more peripheral vein, and is advanced through an inferior vena cava 100, a right atrium 101, and a right ventricle 102 to the pulmonary artery 103 as shown in Fig. 3.

[0014] As shown in FIG. 1, the catheter system 10 includes a suction catheter 40 , a catheter 20 that is a dilator that can be placed inside the suction catheter 40 , and a guide wire 50 that can be inserted into the catheter 20 .

[0015] The suction catheter 40 has an aspiration tube 42 with an aspiration lumen 41 that aspirates thrombus in the pulmonary artery 103. The inner diameter of the aspiration tube 42 is preferably 4.0 mm to 7.4 mm, more preferably 4.5 mm to 7.0 mm, and in the embodiment, is 6.9 mm. The aspiration catheter 40 is capable of accommodating the catheter 20 in the aspiration lumen 41.

[0016] 1 and 2, the catheter 20 has a tubular body 21 that can be placed in the suction lumen 41 of the suction catheter 40, and a hub 22 fixed to the base of the tubular body 21. The tubular body 21 has an inner cavity 23 that passes through in the longitudinal direction, and an opening 24 is formed at the tip.

[0017] The tube body 21 has, from the tip side, a first thin diameter portion 31, a first tapered portion 32, a first thick diameter portion 33, a second tapered portion 34, a second thin diameter portion 35, a third tapered portion 36, and a second thick diameter portion 37.

[0018] The first narrow-diameter section 31 is located at the distal end of the tube 21 and has a constant outer diameter D1 in the longitudinal direction. The first narrow-diameter section 31 has an arc shape, or a pigtail shape. The first narrow-diameter section 31 has a curved section 38 on the distal side and a straight section 39 located on the proximal side of the curved section 38. The outer diameter D1 of the first narrow-diameter section 31 is preferably 1.0 mm to 3.5 mm, for example 1.8 mm. The curved section 38 is curved at a central angle θ of preferably 180 degrees to 300 degrees, more preferably 180 degrees to 200 degrees. The radius of curvature R of the curved section 38 is preferably 3 mm to 15 mm, for example 7 mm. Note that the radius of curvature R of the curved section 38 may vary rather than be constant along the longitudinal axis. The straight section 39 has an axis that extends linearly and is preferably 2.0 mm to 8.5 mm in length, for example 5.0 mm. The first small diameter portion 31 does not necessarily have to have the straight portion 39 .

[0019] The first tapered portion 32 is formed with an outer diameter that increases in a tapered manner from the base end toward the base end of the first small diameter portion 31. The length L1 of the first tapered portion 32 in the major axis direction is preferably 10 mm to 70 mm, and is, for example, 40 mm.

[0020] The first large diameter portion 33 is formed with a constant outer diameter D2 from the base end of the first tapered portion 32 toward the base end. The first large diameter portion 33 has an axis that extends substantially linearly. The outer diameter D2 of the first large diameter portion 33 is preferably 4.3 mm to 6.9 mm, and is, for example, 6.8 mm. The length L2 of the first large diameter portion 33 in the major axis direction is preferably 3 mm to 20 mm, and is, for example, 10 mm.

[0021] The second tapered portion 34 is formed with an outer diameter that tapers downward from the base end of the first large diameter portion 33 toward the base end. The length L3 of the second tapered portion 34 in the major axis direction is preferably 5 mm to 30 mm, and is, for example, 15 mm.

[0022] The second narrow diameter section 35 is formed with a constant outer diameter D3 from the base end of the second tapered section 34 toward the base end. The second narrow diameter section 35 has an axis that extends in a substantially straight line. The outer diameter D3 of the second narrow diameter section 35 is preferably 3.5 mm to 6.9 mm, and is, for example, 4.8 mm. The length L4 of the second narrow diameter section 35 in the major axis direction is preferably 60 mm to 140 mm, and is, for example, 100 mm.

[0023] The third tapered portion 36 is formed with an outer diameter that increases in a tapered manner from the base end of the second small diameter portion 35 toward the base end. The length L5 of the third tapered portion 36 in the major axis direction is preferably 5 mm to 25 mm, and is, for example, 15 mm.

[0024] The second large diameter portion 37 is formed with a constant outer diameter D4 from the base end of the third tapered portion 36 toward the base end. The second large diameter portion 37 has an axis that extends substantially linearly. The outer diameter D4 of the second large diameter portion 37 is preferably 4.3 mm to 6.9 mm, and is, for example, 6.8 mm. The length L6 of the second large diameter portion 37 in the major axis direction is preferably 870 mm to 1270 mm, and is, for example, 970 mm.

[0025] The outer diameter D3 of the second thin diameter portion 35 is preferably equal to or larger than the outer diameter D1 of the first thin diameter portion 31. The outer diameter D2 of the first thick diameter portion 33 is preferably larger than the outer diameter D1 of the first thin diameter portion 31 and larger than the outer diameter D3 of the second thin diameter portion 35. The outer diameter D4 of the second thick diameter portion 37 is preferably equal to or larger than the outer diameter D2 of the first thick diameter portion 33. Therefore, the following formula (1) holds true.

[0026] D1≦D3<D2≦D4...Formula (1)

[0027] The inner diameter of the tip of the tube 21 is preferably 0.5 mm to 2.0 mm, for example 1.1 mm, and the inner diameter of the base of the tube 21 is preferably 0.5 mm to 2.5 mm, for example 2.2 mm. Alternatively, the inner diameter of the tube 21 may be approximately constant in the longitudinal direction.

[0028] The material of the tube body 21 may be, for example, high-density polyethylene, low-density polyethylene, vinyl chloride, polyurethane, polyamide, polyester, as well as urethane elastomer, polyamide elastomer, polyester elastomer, etc., and a coil wire or braided wire may be embedded to reinforce the metal wire, and the inner surface may have a low-friction resin such as PTFE (polytetrafluoroethylene).

[0029] When the catheter 20 is placed in the suction lumen 41 of the suction catheter 40, the tip of the suction catheter 40 is preferably located on the outer peripheral surface of the first large-diameter portion 33. The catheter 20 fills the space between the suction catheter 40 and the guidewire 50, thereby increasing the rigidity of the catheter system 10 and improving its pushability.

[0030] To ensure high reachability, the guidewire 50 preferably has a distal end with higher rigidity than a typical guidewire 50. For example, the guidewire 50 may be a wire obtained by removing the flexible distal end (within a range of 40 mm from the distal end toward the proximal end) of a Glidewire Advantage (registered trademark) manufactured by Terumo Corporation.

[0031] Next, an example of a method of using the catheter 20 according to this embodiment will be described. As shown in Fig. 3 , the catheter 20 is used in combination with the suction catheter 40 and the guidewire 50 to deliver the suction catheter 40 to the pulmonary artery 103.

[0032] Next, an example of a method of using the catheter 20 according to this embodiment will be described. As shown in Fig. 3 , the catheter 20 is used in combination with the suction catheter 40 and the guidewire 50 to deliver the suction catheter 40 to the pulmonary artery 103.

[0033] First, the surgeon punctures a vein in the thigh or other part of the body through the skin to secure the blood vessel. Next, the surgeon inserts the catheter 20 into the aspiration lumen 41 of the aspiration catheter 40, and inserts the catheter system 10, with the guidewire 50 inserted into the lumen 23 of the catheter 20, into the blood vessel. The tip of the aspiration catheter 40 is located on the outer circumferential surface of the first large-diameter portion 33.

[0034] The opening angle α when the guidewire 50 travels from the inferior vena cava 100 through the right atrium 101 and the right ventricle 102 to the pulmonary artery 103 varies depending on the individual patient, but is, for example, approximately 90 to 180 degrees. Therefore, it is preferable that the bending portion 38 into which the guidewire 50 is inserted is stretched by the rigidity of the guidewire 50 and deformed to an angle θ of less than 180 degrees, preferably 100 to 170 degrees, and more preferably 130 to 140 degrees. Therefore, by placing the guidewire 50 inside the first small-diameter section 31 of the catheter 20, the surgeon can easily reach the guidewire 50, the catheter 20, and the aspiration catheter 40 from the inferior vena cava 100 through a wide region (e.g., the right atrium 101 or the right ventricle 102) to a narrow region (e.g., the pulmonary artery 103) located beyond the wide region. As the guidewire 50, catheter 20 and aspiration catheter 40 travel from the inferior vena cava 100 through the right atrium 101 and right ventricle 102 to the pulmonary artery 103, the tricuspid valve may evert.

[0035] The surgeon can bend the bending portion 38 of the catheter 20 by 180 degrees or more by moving the tip of the guidewire 50 proximally beyond the bending portion 38. This allows the surgeon to use the greatly bent bending portion 38 to appropriately select a tortuous blood vessel and push the catheter 20 to the lesion. Therefore, the catheter 20 has high blood vessel selectivity due to the first small-diameter section 31 including the bending portion 38. Furthermore, the catheter 20 has a pigtail shape suitable for pulmonary artery angiography, allowing stable engagement with the target position and good angiography.

[0036] When the curved portion 38 reaches the left pulmonary artery 103, for example, the second narrow-diameter portion 35 is preferably located between the vicinity of the exit of the right ventricle 102 and the area between the left and right branches of the pulmonary artery 103. Note that the second narrow-diameter portion 35 may be located between the junction of the inferior vena cava 100 and the right atrium 101 and the origin of the pulmonary artery 103.

[0037] The catheter 20 has a first large-diameter section 33 and a second large-diameter section 37, and therefore can be placed with an appropriate clearance in the aspiration lumen 41, which has a large inner diameter for aspiration of thrombi. Furthermore, the catheter 20 has a large first large-diameter section 33 and a large second large-diameter section 37, which improves backup force and pushability. Furthermore, the catheter 20 has a second small-diameter section 35, which is thinner than the first large-diameter section 33 and the second large-diameter section 37, between the thick and hard-to-bend first large-diameter section 33 and the second large-diameter section 37, and therefore is more easily bent, improving vascular selectivity and operability.

[0038] After placing the suction catheter 40 at an appropriate position, the surgeon removes the guide wire 50 and the catheter 20, leaving behind the suction catheter 40. The surgeon can then use the suction catheter 40 to aspirate the thrombus.

[0039] As described above, the catheter 20 according to this embodiment is a catheter 20 having a tubular body 21 with a lumen 23 penetrating in the longitudinal direction, and the tubular body 21 has a first small diameter section 31 with a curved section 38 located at the distal end and curved at a central angle of 180 degrees or more, a first tapered section 32 with an outer diameter that increases in a tapered manner from the proximal end of the first small diameter section 31 toward the proximal end, and a first tapered section 32 with a constant outer diameter D2 from the proximal end of the first tapered section 32 toward the proximal end. The catheter 20 has a first large-diameter section 33 having a first large-diameter section 31, a second tapered section 34 having an outer diameter that tapers down from the proximal end of the first large-diameter section 33 in the proximal direction, a second small-diameter section 35 having a constant outer diameter D3 from the proximal end of the second tapered section 34 in the proximal direction, a third tapered section 36 having an outer diameter that tapers down from the proximal end of the second small-diameter section 35 in the proximal direction, and a second large-diameter section 37 having a constant outer diameter D4 from the proximal end of the third tapered section 36 in the proximal direction. This allows the catheter 20 to improve blood vessel selectivity by the bending portion 38 of the first small-diameter section 31. Furthermore, the catheter 20 improves backup force and pushability by the first large-diameter section 33 and the second large-diameter section 37, while partially increasing flexibility by the second small-diameter section 35 between the first large-diameter section 33 and the second large-diameter section 37, thereby improving blood vessel selectivity. Therefore, the catheter 20 can improve backup force, pushability, and vascular selectivity.

[0040] In addition, in the longitudinal direction, the first tapered portion 32 is longer than the second tapered portion 34 and longer than the third tapered portion 36. This makes the first tapered portion 32 have a gentler tapered slope, improving the ease of insertion and the safety of the living body that is the contact target. Furthermore, because the second tapered portion 34 and the third tapered portion 36 are shorter than the first tapered portion 32, they are less likely to interfere with the bending of another device (e.g., a suction catheter 40) into which the catheter 20 is inserted.

[0041] Furthermore, the outer diameter D3 of the second small diameter section 35 is equal to or greater than the outer diameter D1 of the first small diameter section 31, the outer diameter D2 of the first large diameter section 33 is greater than the outer diameter D3 of the second small diameter section 35, and the outer diameter D4 of the second large diameter section 37 is equal to or greater than the outer diameter D2 of the first large diameter section 33. As a result, the catheter 20 can improve blood vessel selectivity by using the first small diameter section 31, which is the thinnest section at the distal end, and can also improve reachability to narrowed regions (e.g., the pulmonary artery 103) beyond wide regions (e.g., the right atrium 101 and the right ventricle 102). Furthermore, the catheter 20 can improve pushability and backup force by using the high rigidity of the second large diameter section 37, which is the thickest section at the proximal end.

[0042] The length of the second small diameter section 35 in the longitudinal direction is 60 mm to 140 mm, which allows the catheter 20 to appropriately curve the second small diameter section 35 between the first large diameter section 33 and the second large diameter section 37.

[0043] The catheter 20 is also a dilator that can be placed inside the pulmonary artery thrombus aspiration catheter 40. This allows the catheter 20, which is a dilator, to smoothly guide the pulmonary artery thrombus aspiration catheter 40 from the right atrium 101 through the right ventricle 102 to the pulmonary artery 103.

[0044] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. For example, the catheter 20 does not have to be a dilator. The outer catheter housing the catheter 20 does not have to be a suction catheter 40.

[0045] This application is based on Japanese Patent Application No. 2024-82487, filed on May 21, 2024, the disclosures of which are incorporated herein by reference in their entirety.

[0046] REFERENCE SIGNS LIST 10 Catheter system 20 Catheter 21 Tubular body 23 Lumen 24 Opening 31 First narrow diameter section 32 First tapered section 33 First wide diameter section 34 Second tapered section 35 Second narrow diameter section 36 Third tapered section 37 Second wide diameter section 38 Curved section 39 Straight section 40 Aspiration catheter (pulmonary artery thrombus aspiration catheter) 41 Aspiration lumen 42 Aspiration tubular body 50 Guidewire 100 Inferior vena cava 101 Right atrium 102 Right ventricle 103 Pulmonary artery

Claims

1. A catheter having a tubular body with a lumen penetrating in the longitudinal direction, wherein the tubular body has: a first small diameter section located at the tip and having a curved section that bends at a central angle of 180 degrees or more; a first tapered section having an outer diameter that tapers from the base end of the first small diameter section toward the base end; a first large diameter section having a constant outer diameter from the base end of the first tapered section toward the base end; a second tapered section having an outer diameter that tapers from the base end of the first large diameter section toward the base end; a second small diameter section having a constant outer diameter from the base end of the second tapered section toward the base end; a third tapered section having an outer diameter that tapers from the base end of the second small diameter section toward the base end; and a second large diameter section having a constant outer diameter from the base end of the third tapered section toward the base end.

2. A catheter according to claim 1, wherein the first tapered portion is longer than the second tapered portion and longer than the third tapered portion in the longitudinal direction.

3. A catheter as described in claim 1 or 2, characterized in that the outer diameter of the second thin diameter section is equal to or greater than the outer diameter of the first thin diameter section, the outer diameter of the first thick diameter section is greater than the outer diameter of the second thin diameter section, and the outer diameter of the second thick diameter section is equal to or greater than the outer diameter of the first thick diameter section.

4. A catheter according to claim 1 or 2, characterized in that the length of the second narrow diameter section in the major axis direction is 60 mm to 140 mm.

5. The catheter according to claim 1 or 2, which is a dilator that can be placed inside a pulmonary artery thrombus aspiration catheter.

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