Catheter assembly and treatment method

Abstract

To provide a catheter assembly that can simplify treatment by a suction catheter, and a treatment method using the same.SOLUTION: A catheter assembly 10 comprises: a contrast catheter 11 having a three-dimensional shape including a base part curved part 22a, an intermediate curved part 22c, and a tip curved part 22e, in a tip part of a shaft 20; and a dilator 12 comprising the shaft 20 of the contrast catheter 11 in a lumen 34, and comprising a taper part 33 in which the diameter of a tip part is decreased toward a tip. In the contrast catheter 11, the outside diameter of the shaft 20 is 1.4 mm to 2.0 mm. The outside diameter of the dilator 12 is 5.3 mm to 6.5 mm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a catheter assembly used when inserting an aspiration catheter for aspirating thrombi into a blood vessel, and a treatment method using the same. [Background technology]

[0002] Pulmonary embolism is a disease in which a blood clot blocks the pulmonary artery, causing breathing difficulties, etc., and requires treatment to remove the blood clot as soon as possible. A suction catheter with an outer diameter of about 5.3 mm to 8.0 mm is usually used to treat pulmonary embolism.

[0003] Since the outer diameter of the suction catheter is relatively large, a highly supportive guidewire must be inserted into the blood vessel to reach the lesion where the thrombus is located. For this reason, in the treatment of pulmonary embolism using a suction catheter, a contrast catheter with a guidewire inserted therethrough is first delivered to the lesion, and the guidewire is replaced with a highly supportive guidewire while the contrast catheter is still in place. Next, the contrast catheter is removed, and a catheter assembly with a dilator inserted into the lumen of the suction catheter is inserted into the blood vessel and delivered to the lesion along the highly supportive guidewire. Once the suction catheter has been delivered to the lesion, the dilator and guidewire are removed, and suction of the thrombus begins.

[0004] An angiography catheter heading for the pulmonary artery advances into the right atrium of the heart, then passes through the right ventricle and advances into the pulmonary artery. This route is significantly bent within the right atrium and right ventricle, so it may take time for the angiography catheter to reach the lesion. For this reason, as shown in Patent Document 1, a catheter with a curved tip is used as the angiography catheter, making it easier to advance through the bent route. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-178177 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as described above, in order to reach the lesion with a suction catheter that has a relatively large outer diameter and start suction, the procedure is complicated, and there is a need to simplify this procedure.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a catheter assembly that can simplify treatment using a suction catheter, and a treatment method using the same. [Means for solving the problem]

[0008] The catheter assembly (1) of the present invention, which achieves the above-mentioned object, comprises an angiography catheter having a three-dimensional shape at the tip of a shaft including a proximal curved portion, an intermediate curved portion, and a distal curved portion, and a dilator having the shaft of the angiography catheter in an inner cavity and a distal end having a tapered portion whose diameter decreases toward the tip, wherein the shaft of the angiography catheter has an outer diameter of 1.4 mm to 2.0 mm, and the dilator has an outer diameter of 5.3 mm to 6.5 mm.

[0009] (6) A treatment method according to the present invention for achieving the above-mentioned object is a treatment method for aspirating a thrombus using an aspiration catheter, comprising the steps of: inserting a catheter assembly, in which a contrast catheter having an outer shaft diameter of 1.4 mm to 2.0 mm is inserted into the inner cavity of a dilator having an outer diameter of 5.3 mm to 6.5 mm, into the inner cavity of an aspiration catheter having an outer diameter of 6.0 mm to 8.0 mm; inserting the aspiration catheter into a blood vessel with a guidewire inserted into the inner cavity of the contrast catheter until it reaches the lesion; removing the dilator, the contrast catheter, and the guidewire; and commencing aspiration using the aspiration catheter. Effect of the Invention

[0010] The catheter assembly configured as described above can be inserted into a blood vessel as a unit with the catheter assembly having the contrast catheter inserted into the lumen of the dilator and the suction catheter inserted therein, thereby reducing the number of steps in the procedure and simplifying treatment using the suction catheter.

[0011] (2) In the catheter assembly of (1) above, the dilator may have an inner diameter of 1.6 mm to 2.5 mm, which allows the contrast catheter to be smoothly inserted into the lumen of the dilator.

[0012] (3) In the catheter assembly of (1) or (2) above, the dilator may have a tapered portion having a longitudinal length of 50 mm to 150 mm. This allows the tapered portion to have a long longitudinal length, and the dimensional and physical property differences between the dilator and the contrast catheter and suction catheter change gradually along the longitudinal direction. The gradual change in dimensional difference along the longitudinal direction reduces the risk of damage to the vascular wall or thrombus detachment when the catheter assembly and suction catheter are inserted into a blood vessel. Furthermore, the gradual change in physical property difference along the longitudinal direction improves the deliverability when the catheter assembly and suction catheter are combined.

[0013] (4) In any of the catheter assemblies (1) to (3) above, the dilator may have an outer diameter of 1.5 mm to 2.1 mm at the tip of the tapered portion. This minimizes the outer diameter of the tapered portion, thereby ensuring the inclination angle of the tapered portion and making it possible to more gently change dimensional differences and physical property differences along the longitudinal direction at the tip of the dilator.

[0014] (5) In any of the catheter assemblies (1) to (4) above, the clearance between the outer surface of the contrast catheter and the inner surface of the dilator may be 0.5 mm or more. This allows the contrast medium to be injected using the gap between the dilator and the contrast catheter, making it unnecessary to remove the guidewire and further reducing the number of steps in the procedure.

[0015] The treatment method configured as described above can deliver the catheter assembly and the suction catheter in an integrated state to the affected area, thereby simplifying the treatment for thrombus aspiration. [Brief description of the drawings]

[0016] [Figure 1] 1 is an overall front view of an intravascular catheter and a dilator, and a suction catheter, which constitute a catheter assembly in this embodiment. FIG. [Diagram 2] FIG. 13 is a front view of the vicinity of the base end of a combination of a suction catheter, a dilator, an angiography catheter, and a guidewire. [Diagram 3] FIG. 2 is a front view of the vicinity of the tip portion of a combination of a suction catheter, a dilator, an angiography catheter, and a guidewire. [Figure 4] 1A and 1B are diagrams showing the tip of a contrast catheter, where (a) is a plan view, (b) is a view taken along the line B in (a), and (c) is a view taken along the line C in (a). [Diagram 5] 1 is a cross-sectional view of the vicinity of the tip of a combination of a suction catheter, a dilator, an angiography catheter, and a guidewire. FIG. [Figure 6] FIG. 13 is a partial cross-sectional view of the state in which the tip of the combination is inserted into the heart. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that dimensions in the drawings may be exaggerated and may differ from actual dimensions for convenience of explanation. In addition, in this specification and the drawings, components having substantially the same functional configurations are given the same reference numerals to avoid duplicated explanation. In this specification, the side of the device that is inserted into the living body is referred to as the "distal side" and the side that is operated is referred to as the "base side".

[0018] The catheter assembly 10 of this embodiment is a medical device used in the treatment of pulmonary embolism, and is used when inserting into a blood vessel an aspiration catheter 13 that is inserted into a pulmonary vein to aspiration thrombus.

[0019] 1, the catheter assembly 10 includes an angiography catheter 11 and a dilator 12. The angiography catheter 11 is inserted into an inner cavity 34 of the dilator 12, and the dilator 12 is inserted into the inside of the suction catheter 13.

[0020] The contrast catheter 11 has a long tubular shaft 20 and a hub 21 provided at the base end of the shaft 20. A tip portion 22 of the shaft 20 has a three-dimensional shape that is bent multiple times.

[0021] The dilator 12 has a long section 30 made of a long tubular member, and a hub 31 provided at the base end of the long section 30. The long section 30 has a constant diameter section 32 having a constant outer diameter along the longitudinal direction, and a tapered section 33 at the tip of the dilator 12, the diameter of which decreases toward the tip. The hub 31 of the dilator 12 has an insertion port 31a through which the contrast catheter 11 can be inserted, and a connection port 31b to which a device such as a syringe for injecting a contrast medium can be connected.

[0022] The suction catheter 13 has a long tubular suction shaft 40 and a hub 41 provided at the base end of the suction shaft 40. The hub 41 has an insertion port 41a through which the contrast catheter 11, the dilator 12, etc. are inserted, and a suction port 41b for connecting a device for suction. In addition, a valve body 41c is provided inside the hub 41, through which the inserted device passes and which prevents the outflow of fluid from the suction shaft 40 side.

[0023] Each of the tubes of the contrast catheter 11, the dilator 12, and the suction catheter 13 is formed so as to have an outer layer on the outside of an inner layer having a lumen. The inner layer is preferably formed of a low-friction material so that the guide wire 14 can slide easily inside. The low-friction material is, for example, fluororesin such as PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer) or silicone resin, but is not limited thereto. The material constituting the outer layer is not particularly limited, but examples thereof include, in addition to polystyrene, polyolefin, polyurethane, polyester, and polyamide, various thermoplastic elastomers such as styrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, transpolyisoprene-based, fluororubber-based, and chlorinated polyethylene-based, polyether ketone, and polyimide-based, and one or a combination of two or more of these (polymer alloy, polymer blend, laminate, etc.) can be used. Alternatively, among various elastomers, polyester elastomers, polyamide elastomers, etc. can be preferably used. Each tube may also have a reinforcing layer made of a braid between the inner layer and the outer layer.

[0024] 2, the shaft 20 of the angiography catheter 11 is inserted into the lumen of the dilator 12, and the angiography catheter 11 and the dilator 12 form a catheter assembly 10. The catheter assembly 10 is inserted into the inside of the suction catheter 13 through an insertion port 41a of the hub 41 of the suction catheter 13. In addition, a guidewire 14 is inserted into the angiography catheter 11 from the hub 21 to the shaft 20.

[0025] 3, the tip of the long portion 30 of the dilator 12 is exposed distally beyond the tip of the suction shaft 40. The tip 22 of the angiography catheter 11 is exposed distally beyond the tip of the dilator 12. The guidewire 14 protrudes distally beyond the tip of the angiography catheter 11.

[0026] As shown in Figures 4(a) to (c), the tip portion 22 has a base curved portion 22a, a base straight portion 22b, an intermediate curved portion 22c, an intermediate straight portion 22d, a tip curved portion 22e, and a most distal portion 22f.

[0027] The base curved portion 22a extends from the tip of the base portion 23, which is closer to the base end than the tip portion 22, toward the tip side, and is curved within a plane. The base straight portion 22b extends from the tip of the base curved portion 22a in a substantially straight line toward the tip side. The middle curved portion 22c extends from the tip of the base straight portion 22b toward the tip side, and is curved within a plane. The middle curved portion 22c is curved in a direction different from the bending direction of the base curved portion 22a. The middle straight portion 22d extends from the tip of the middle curved portion 22c in a substantially straight line toward the tip side. The tip curved portion 22e extends from the tip of the middle straight portion 22d toward the tip side, and is curved within a plane. The most distal portion 22f extends from the tip of the tip curved portion 22e in a substantially straight line toward the tip side. The lumen of the shaft 20 opens at the tip of the most distal portion 22f. The axis of the most distal portion 22f is not located on an extension of the axis of the intermediate straight portion 22d.

[0028] The angle α1 that base straight portion 22b makes with respect to an extension line extending from the tip side part of base 23 toward the tip side is greater than 0° and less than 90°, and is preferably 40° to 85°, and more preferably 40° to 80°. When angle α1 is less than 90°, it can be easily inserted into a curved path from inside the heart toward the pulmonary artery, and a pushing force can be easily transmitted to the tip side.

[0029] The angle α2 that the intermediate straight portion 22d makes with respect to an extension line extending from the base straight portion 22b toward the tip is not particularly limited, but is approximately parallel or exceeds 0° and is less than 180°, is preferably 100° to 175°, and is more preferably 110° to 170°.

[0030] The angle α3 that the most distal portion 22f makes with respect to an extension line extending from the intermediate straight portion 22d toward the tip direction is not particularly limited, but is greater than 0° and less than 180°, preferably 5° to 80°, and more preferably 10° to 60°. The most distal portion 22f is not positioned coaxially with the intermediate straight portion 22d.

[0031] The axis centers of the tip side portion of the base 23, the base curved portion 22a and the base straight portion 22b, are located on the first plane P1. The axis centers of the intermediate curved portion 22c and the intermediate straight portion 22d are located on the second plane P2. The axis centers of the tip curved portion 22e and the most distal portion 22f are located on the third plane P3. The axis center of the base straight portion 22b located on the first plane P1 may also be located on the second plane P2. The axis center of the intermediate straight portion 22d located on the second plane P2 may also be located on the third plane P3.

[0032] The second plane P2 is a plane different from the first plane P1. The angle β of the second plane P2 with respect to the first plane P1 on the distal side of the base curved portion 22a is more than 0° and less than 180°, preferably 30° to 150°, and more preferably 80° to 100°. Since the second plane P2 is different from the first plane P1, the shaped portion 24 having the base curved portion 22a and the intermediate curved portion 22c can have a twisted shape that draws a three-dimensional spiral. Therefore, the distal end portion 22 of the shaft 20 is easily aligned with the inner wall surface of the blood vessel, and the posture within the blood vessel is easily stabilized. In addition, when the proximal end portion of the contrast catheter 11 is rotated in the direction in which the contrast catheter 11 is wound toward the distal end side, the rotational force is efficiently transmitted to the distal end side, making it easy to push the contrast catheter 11 toward the distal end.

[0033] The third plane P3 is a plane different from the first plane P1 and the second plane P2. The third plane P3 may coincide with the second plane P2, but it is preferable that the third plane P3 does not coincide with the second plane P2. By not coinciding with the second plane P2, the opening of the most distal portion 22f can be oriented in a direction different from the curvature of the intermediate curved portion 22c.

[0034] In this embodiment, the distal curved portion 22e is bent from the base end side toward the tip end side away from the first plane P1. Therefore, the most distal end portion 22f extends from the base end side toward the tip opening 31 so as to move away from the first plane P1. The distal curved portion 22e is bent from the base end side toward the tip end side toward the opposite side of the side where the base portion 23 is located with respect to the second plane P2. Therefore, the most distal end portion 22f extends from the base end side toward the tip opening 31 toward the opposite side of the side where the base portion 23 is located with respect to the second plane P2. The distal curved portion 22e may be bent from the base end side toward the tip end side toward the side approaching the first plane P1. The distal curved portion 22e may be bent from the base end side toward the tip end side on a plane parallel to the first plane P1. The distal curved portion 22e may be bent from the base end side toward the tip end side toward the opposite side of the side where the base portion 23 is located from the second plane P2. It should be noted that base straight portion 22b, intermediate straight portion 22d and tip end portion 22f need only be substantially straight and do not have to be formed as strictly straight lines.

[0035] If the minimum radius of curvature at the base curved portion 22a is R1, the minimum radius of curvature at the middle curved portion 22c is R2, and the minimum radius of curvature at the tip curved portion 22e is R3, then R1>R2>R3 is satisfied. That is, R2 is smaller than R1, and R3 is smaller than R2. The minimum radius of curvature is the radius of curvature of the portion with the smallest radius of curvature among the curved portions.

[0036] As shown in Fig. 5, the dilator 12 is inserted into the inner cavity 43 of the suction catheter 13, and the contrast catheter 11 is inserted into the inner cavity 34 of the dilator 12. The inner diameter D1 of the contrast catheter 11 is 0.5mm to 1.0mm, and the outer diameter D2 of the contrast catheter 11 is 1.4mm to 2.0mm. The inner diameter D3 of the dilator 12 is 1.6mm to 2.5mm, the outer diameter D4 of the most distal end of the tapered portion 33 is 1.4mm to 2.5mm, and the outer diameter D5 of the same diameter portion 32 on the proximal side of the tapered portion 33 is 5.3mm to 6.5mm. The inner diameter D6 of the suction catheter 13 is 5.5mm to 7.0mm, and the outer diameter D7 of the suction catheter 13 is 6.0mm to 8.0mm.

[0037] The tapered portion 33 of the dilator 12 has a length along the longitudinal direction of 50 mm to 150 mm, preferably 70 mm to 80 mm. Since the tapered portion 33 is long in the longitudinal direction, the dimensional difference and physical property difference between the dilator 12, the contrast catheter 11 inserted inside the dilator 12, and the suction catheter 13 through which the dilator 12 is inserted change gradually along the longitudinal direction. Since the dimensional difference changes gradually along the longitudinal direction, the risk of damage to the blood vessel wall or thrombus detachment can be reduced when the catheter assembly 10 and the suction catheter 13 are inserted into a blood vessel. Furthermore, since the physical property difference changes gradually along the longitudinal direction, the deliverability can be improved when the catheter assembly 10 and the suction catheter 13 are combined.

[0038] The clearance between the angiography catheter 11 and the dilator 12 is the difference between the inner diameter D3 of the dilator 12 and the outer diameter D2 of the angiography catheter 11, and is greater than 0 mm and less than 1.1 mm, and is preferably 0.5 mm or more in the following cases. This allows the contrast medium to be injected using the space between the angiography catheter 11 and the dilator 12 without removing the guidewire 14 when the catheter assembly 10 and the suction catheter 13 are combined and inserted into a blood vessel. Alternatively, the clearance between the angiography catheter 11 and the dilator 12 may be 0.1 mm or more and less than 0.5 mm. This allows the dilator 12 to support the angiography catheter 11, making it easier to transmit the pushing force to the tip side.

[0039] Next, there will be described a treatment method using the catheter assembly 10 and the suction catheter 13 of this embodiment. The catheter assembly 10 and the suction catheter 13 are used for treating pulmonary embolism.

[0040] The contrast catheter 11 is first inserted through the dilator 12 to form the catheter assembly 10. The catheter assembly 10 is formed by inserting the shaft 20 of the contrast catheter 11 through the lumen 34 of the dilator 12 and leaving the tip of the shaft 20 exposed on the tip side beyond the tip of the dilator 12.

[0041] Also, the catheter assembly 10 is inserted into the lumen 43 of the suction catheter 13. The tip of the catheter assembly 10 is exposed distally beyond the tip of the suction catheter 13. Furthermore, the guidewire 14 is inserted into the lumen 24 of the angiography catheter 11, and the tip of the guidewire 14 is exposed distally beyond the tip of the angiography catheter 11.

[0042] First, an insertion path into the blood vessel is secured. To this end, the surgeon percutaneously passes an introducer sheath (not shown) through the femoral vein. The surgeon inserts the combination of the guide wire 14, catheter assembly 10, and aspiration catheter 13 into the vein through the introducer sheath, and advances the catheter assembly 10 and aspiration catheter 13 while leading the guide wire 14.

[0043] 6, the angiography catheter 11 advances from the inferior vena cava 101 into the right atrium 103 of the heart 100, passes through the right ventricle 104, and heads toward the pulmonary artery 102. Because the tip 22 of the angiography catheter 11 has the three-dimensional shape described above, the surgeon can easily push it through the curved path within the heart 100. The surgeon can push the suction catheter 13 together with the dilator 12 and the angiography catheter 11 through the blood vessels, and reach the pulmonary artery 102.

[0044] If contrast is required during insertion of the suction catheter 13, the surgeon can connect a device for injecting a contrast medium, such as a syringe, to the hub 31 of the dilator 12 and inject the contrast medium using the space between the contrast catheter 11 and the dilator 12. This allows the injection of the contrast medium without removing the guidewire 14, simplifying the procedure.

[0045] Once the suction catheter 13 has reached the affected area of ​​the pulmonary artery, the surgeon removes the dilator 12, the contrast catheter 11, and the guidewire 14. Next, the surgeon connects a suction device to the suction port 41b provided in the hub 41 of the suction catheter 13, and starts suctioning the thrombus.

[0046] After the thrombus has been aspirated, the surgeon removes the suction catheter 13 from the blood vessel, completing the procedure.

[0047] As described above, the catheter assembly 10 according to the present embodiment (1) includes an angiography catheter 11 having a three-dimensional shape including a base curved portion 22a, an intermediate curved portion 22c, and a tip curved portion 22e at the tip of the shaft 20, and a dilator 12 having a shaft 20 of the angiography catheter 11 in a lumen 34 and a tip portion having a tapered portion 33 whose diameter decreases toward the tip, the shaft 20 of the angiography catheter 11 having an outer diameter of 1.4 mm to 2.0 mm, and the dilator 12 having an outer diameter of 5.3 mm to 6.5 mm. The catheter assembly 10 thus configured can be inserted into a blood vessel as a unit in a state in which the catheter assembly 10 having the angiography catheter 11 inserted into the lumen 34 of the dilator 12 is inserted into the suction catheter 13, thereby reducing the number of steps in the procedure and simplifying the treatment using the suction catheter 13.

[0048] (2) In the catheter assembly 10 described above in (1), the dilator 12 may have an inner diameter of 1.6 mm to 2.5 mm. This allows the contrast catheter 11 to be smoothly inserted into the lumen of the dilator 12.

[0049] (3) In the catheter assembly 10 of (1) or (2) above, the dilator 12 may have a long-axis length of the tapered portion 33 of 50 mm to 150 mm. This allows the long-axis length of the tapered portion 33 to be increased, and the dimensional and physical property differences between the dilator 12 and the contrast catheter 11 and the suction catheter 13 change gradually along the long-axis direction. Since the dimensional difference changes gradually along the long-axis direction, the risk of damage to the blood vessel wall or thrombus detachment can be reduced when the catheter assembly 10 and the suction catheter 13 are inserted into a blood vessel. Furthermore, since the physical property difference changes gradually along the long-axis direction, the deliverability can be improved when the catheter assembly 10 and the suction catheter 13 are combined.

[0050] (4) In any of the catheter assemblies 10 described above in (1) to (3), the dilator 12 may have an outer diameter of 1.5 mm to 2.1 mm at the tip of the tapered portion 33. This minimizes the outer diameter of the tapered portion 33, thereby ensuring the inclination angle of the tapered portion 33 and making it possible to more gently change the dimensional differences and physical property differences along the longitudinal direction at the tip of the dilator 12.

[0051] (5) In any of the catheter assemblies 10 described above in (1) to (4), the clearance between the outer surface of the angiography catheter 11 and the inner surface of the dilator 12 may be 0.5 mm or more. This allows the contrast medium to be injected using the gap between the dilator 12 and the angiography catheter 11, making it unnecessary to remove the guidewire, and further reducing the number of steps in the procedure.

[0052] The (6) treatment method according to this embodiment is a treatment method for aspirating a thrombus with an aspiration catheter 13, and includes the steps of inserting the catheter assembly 10, in which an angiography catheter 11 with an outer diameter of 1.4 mm to 2.0 mm in the shaft 20 is inserted into the inner cavity 34 of a dilator 12 with an outer diameter of 5.3 mm to 6.5 mm, into the inner cavity 43 of the aspiration catheter 13 with an outer diameter of 6.0 mm to 8.0 mm, and inserting the aspiration catheter 13 into a blood vessel and advancing it to a lesion in a state in which a guidewire 14 is inserted into the inner cavity 24 of the angiography catheter 11, removing the dilator 12, the angiography catheter 11, and the guidewire 14, and starting aspiration with the aspiration catheter 13. The treatment method thus configured can simplify the treatment for thrombus aspiration because the catheter assembly 10 and the aspiration catheter 13 can be delivered to the lesion in an integrated state.

[0053] The present invention is not limited to the above-described embodiment, and various modifications can be made by those skilled in the art within the technical concept of the present invention. [Explanation of symbols]

[0054] 10 Catheter assembly 11 Contrast Catheter 12 Dilator 13 Suction catheter 14 Guidewire 20 Shaft 21 Hub 22 Tip 22a Base curve 22b Base straight part 22c Middle curve 22d Middle straight section 22e Tip curve 22f cutting edge section 23 Base 24 lumen 30 Long section 31 Hub 31a Insertion port 31b Connection port 32 Same diameter part 33 Tapered section 34 Lumen 40 Suction shaft 41 Hub 41a Insertion port 41b Suction port 41c Valve body 43 Lumen

Claims

1. a contrast catheter having a three-dimensional shape including a base curved portion, an intermediate curved portion, and a tip curved portion at a tip portion of a shaft; a dilator having the shaft of the contrast catheter in an inner lumen and a tapered portion having a tip portion whose diameter decreases toward the tip, The contrast catheter has an outer diameter of the shaft of 1.4 mm to 2.0 mm; The dilator is a catheter assembly having an outer diameter of 5.3 mm to 6.5 mm.

2. 2. The catheter assembly according to claim 1, wherein the dilator has an inner diameter of 1.6 mm to 2.5 mm.

3. 3. The catheter assembly according to claim 1, wherein the length of the tapered portion of the dilator in the major axis direction is 50 mm to 150 mm.

4. 3. The catheter assembly according to claim 1, wherein the dilator has an outer diameter of 1.5 mm to 2.1 mm at the tip of the tapered portion.

5. 3. The catheter assembly according to claim 1, wherein a clearance between an outer surface of the angiography catheter and an inner surface of the dilator is 0.5 mm or more.

6. A method for aspirating a thrombus using a suction catheter, comprising: a step of inserting a contrast catheter having an outer diameter of 1.4 mm to 2.0 mm into the inner cavity of a dilator having an outer diameter of 5.3 mm to 6.5 mm, and then inserting the catheter assembly into the inner cavity of an aspiration catheter having an outer diameter of 6.0 mm to 8.0 mm, and, with a guidewire inserted into the inner cavity of the contrast catheter, inserting the aspiration catheter into a blood vessel and advancing it to a lesion; removing the dilator, the contrast catheter, and the guidewire; initiating suction with the suction catheter; The method of treatment comprising:

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