Catheter assembly and dilator

Abstract

[Problem] To provide a catheter assembly and a dilator with which, even if a dilator body has a large diameter, it possible to achieve high trackability of a dilator body with respect to a guide wire and high insertability (reduced resistance of insertion of the dilator body when inserted into a body lumen) of the dilator body into a body lumen. [Solution] A catheter assembly 10 comprises a dilator 100 and a catheter 200. A distal end section 130 of the dilator 100 comprises a distal end region 140, a proximal end region 150, and an intermediate region 160 located between the distal end region and the proximal end region. The outer diameter D21 of a proximal end 143 of the distal end region, the outer diameter D41 of the intermediate region, and the outer diameter D31 of a distal end 151 of the proximal end region are each larger than the outer diameter D1 of a main body section. The inner diameter d41 of a distal end 161 of the intermediate region is larger than the inner diameter d3 of the proximal end region. The cross-sectional area of the distal end of the proximal end region is larger than each of the cross-sectional area of the distal end region, the cross-sectional area of the distal end of the intermediate region, and the cross-sectional area of the main body section. When the catheter assembly is in an inserted state, a distal end 211 of a catheter body is located in the proximal end region of the dilator body.

Description

Catheter assembly and dilator

[0001] The present invention relates to a catheter assembly and a dilator.

[0002] Catheter assemblies (e.g., introducer kits) that are used when performing treatment, diagnosis, or the like using various medical devices are known. This type of catheter assembly includes: a catheter having a catheter body with a lumen formed therein; and a dilator having a dilator body inserted through the lumen of the catheter body (see, for example, Patent Document 1).

[0003] In a procedure using a catheter assembly, prior to inserting the catheter into a biological lumen, an operator forms a perforation connecting the biological lumen and the outside of the living body, and places a guide wire across the biological lumen and the outside of the living body through the perforation. The operator inserts the dilator body through the catheter body, in a state where the catheter and the dilator are assembled, inserts the guide wire through the dilator body, and inserts the dilator body and the catheter body into the biological lumen along the guide wire. With the catheter body inserted into the biological lumen, the operator removes the guide wire and the dilator body from the catheter body. In a state where the dilator body is removed from the catheter body, the operator uses the lumen of the catheter body as an access path connecting the biological lumen and the outside of the living body, whereby various medical devices used for treatment and diagnosis can be inserted into the biological lumen.

[0004] By inserting the catheter into the perforation formed in the living body in a state where the dilator body is inserted through the catheter body as described above, the operator can expand the perforation and prevent the dilator body from causing bending or the like of the catheter body.

[0005] The dilator body is required to have followability to a guide wire that has been inserted into a biological lumen prior to the catheter body, and insertability that can reduce the burden on an operator when operating the dilator.

[0006] On the other hand, in recent years, development of catheter assemblies intended for use in relatively thick blood vessels such as arteries of the lower limbs has been progressing (see, for example, Patent Document 2).

[0007] Japanese Patent Publication No. Hei 7-303703, Japanese Patent Publication No. 2022-27860

[0008] The dilator included in the catheter assembly described in Patent Document 2 is larger than dilators intended for use in relatively small blood vessels such as those in the upper limbs. Therefore, the dilator body itself is also made larger in diameter to correspond to the diameter of the blood vessel into which it is inserted.

[0009] When the dilator body is constructed with a large diameter, the amount of material (e.g., resin) used to form the tube wall of the dilator body also increases. As a result, the flexibility of the tip of the dilator body decreases, and the ability of the dilator body to follow the guide wire decreases. In addition, the increased amount of material used to form the tube wall at the tip of the dilator body also leads to an increase in the insertion load of the dilator body.

[0010] Therefore, in catheter assemblies designed for use in relatively large blood vessels such as arteries in the lower extremities, improving the ability to follow the guidewire and the ease of insertion of the dilator body becomes even more difficult.

[0011] The present invention has been made in view of the above problems, and aims to provide a catheter assembly and dilator that can achieve high followability of the dilator body to the guide wire and high insertability of the dilator body into the biological lumen (reduction of insertion resistance of the dilator body when inserting into the biological lumen), even when the dilator body is configured to have a large diameter.

[0012] The present invention can be achieved by any one of the following (1) to (8).

[0013] (1) A dilator comprising a dilator body having a lumen that penetrates between the tip and the base, and a dilator hub connected to the base end of the dilator body and having an opening that communicates with the lumen of the dilator body; a catheter comprising a catheter body having a lumen into which the dilator body can be inserted, and a catheter hub connected to the base end of the catheter body and connectable to the dilator hub, wherein the dilator body comprises a main body portion extending from the dilator hub toward the tip, and a tip portion located toward the tip than the main body portion and having an inclined region that slopes toward the tip, wherein the tip portion comprises a tip region having the inclined region, a base region, and an intermediate region located between the tip region and the base region, wherein the outer diameter of the base end of the tip region, the outer diameter of the intermediate region, and the outer diameter of the tip of the base region are each configured to be larger than the outer diameter of the main body portion, and the inner diameter of the tip of the intermediate region is configured to be larger than the inner diameter of the base region. The catheter assembly is configured such that the cross-sectional area of ​​the tip of the proximal region is larger than the cross-sectional area of ​​the tip region, the cross-sectional area of ​​the tip of the intermediate region, and the cross-sectional area of ​​the main body, and the tip of the catheter body is located in the proximal region when the dilator body is inserted into the lumen of the catheter body.

[0014] (2) The catheter assembly according to (1), wherein the outer diameter of the proximal end of the intermediate region and the outer diameter of the tip of the proximal region are the same, and the intermediate region has a straight portion extending with substantially constant outer and inner diameters.

[0015] (3) The catheter assembly according to (2), wherein the outer diameter of the tip of the tip region is smaller than the outer diameter of the main body, and the inner diameter of the tip of the tip region is smaller than the inner diameter of the main body.

[0016] (4) The catheter assembly according to (2) or (3), wherein the intermediate region comprises a first intermediate region and a second intermediate region located on the proximal end side of the first intermediate region and adjacent to the proximal region, and the inner diameter of the second intermediate region increases from the proximal end to the tip.

[0017] (5) The catheter assembly according to any one of (1) to (4), wherein the proximal region comprises a first proximal region and a second proximal region located on the proximal side of the first proximal region and adjacent to the main body, the outer diameter of the second proximal region is configured to decrease from the tip to the proximal, and the tip of the catheter body is located in the first proximal region when the dilator body is inserted into the lumen of the catheter body.

[0018] (6) The catheter assembly according to any one of (1) to (5), wherein the tip region further has a tip inclined region that is inclined at an acute angle at its very tip.

[0019] (7) The catheter assembly according to any one of (1) to (6), wherein, when the dilator body is inserted into the lumen of the catheter body, the distance between the tip of the proximal region and the tip of the catheter body is 1 / 2 or more and 4 or less the difference between the outer diameter of the body portion and the inner diameter of the catheter body.

[0020] (8) A dilator comprising: a dilator body having a lumen that penetrates between a tip and a base; and a dilator hub connected to the base end of the dilator body and having an opening that communicates with the lumen of the dilator body, wherein the dilator body has a main body portion extending from the dilator hub toward the tip, and a tip portion located toward the tip than the main body portion and having an inclined region that slopes toward the tip, wherein the tip portion has a tip region having the inclined region, a base region, and an intermediate region located between the tip region and the base region, wherein the outer diameter of the base end of the tip region, the outer diameter of the intermediate region, and the outer diameter of the tip of the base region are each configured to be larger than the outer diameter of the main body portion, the inner diameter of the tip of the intermediate region is configured to be larger than the inner diameter of the base region, and the cross-sectional area of ​​the tip of the base region is configured to be larger than the cross-sectional area of ​​the tip region, the cross-sectional area of ​​the tip of the intermediate region, and the cross-sectional area of ​​the main body portion.

[0021] The dilator body described in (1) above comprises a main body and a tip portion located further forward than the main body and having a sloping region in which the outer diameter decreases toward the tip. By having a tip sloping region, the tip portion can gradually widen a perforation formed in the body from the tip to the proximal end when the dilator body is inserted into a biological lumen. This prevents the perforation formed in the body from being rapidly widened when the dilator body is inserted into a biological lumen. Therefore, the surgeon can reduce the burden on the patient during procedures using a dilator.

[0022] Furthermore, the tip of the dilator body has a tip region with an inclined area, a proximal region, and an intermediate region located between the tip and proximal regions. The outer diameters of the proximal end of the tip region, the intermediate region, and the tip of the proximal region are configured to be larger than the outer diameter of the main body. On the other hand, the inner diameter of the intermediate region is configured to be larger than the inner diameter of the proximal region. As a result, when the guidewire is inserted into the lumen of the dilator body, the contact area between the guidewire and the inner walls of the tip region and the intermediate region is reduced. This improves the ease of inserting the guidewire into the lumen of the dilator body and the maneuverability of the guidewire when it is inserted into the dilator body (maneuverability when moving the guidewire axially relative to the dilator body).

[0023] Furthermore, the cross-sectional area of ​​the tip of the proximal region (the cross-sectional area of ​​the material portion constituting the proximal region) is larger than the cross-sectional areas of the tip region, intermediate region, and tip of the main body. In other words, the intermediate and tip regions located closer to the tip than the proximal region are formed with a smaller cross-sectional area (thinner walls) than the tip of the proximal region. This improves the flexibility of the intermediate and tip regions of the dilator body, which are located closer to the tip than the proximal region at the tip. As a result, the dilator body can improve the followability of the intermediate and tip regions to the guidewire and reduce the insertion load of the intermediate and tip regions. Therefore, even when the dilator body is configured with a large diameter, the catheter assembly can achieve high followability of the dilator body to the guidewire and high insertability of the dilator body into the biological lumen.

[0024] Furthermore, the catheter assembly is configured such that when the dilator body is inserted into the lumen of the catheter body (hereinafter referred to as the "inserted state"), the tip of the catheter body is located in the proximal region. As described above, the proximal region is larger in cross-sectional area than the tip region, the intermediate region, and the tip of the main body, and is thicker than these parts. Therefore, in the inserted state, the catheter assembly can prevent the dilator body from collapsing into a flattened cross-sectional shape near the tip of the catheter body towards the lumen of the dilator body. As a result, in the inserted state, the catheter assembly can prevent a gap from forming between the catheter body and the dilator body when the catheter assembly passes through a bend in the biological lumen, etc.

[0025] Furthermore, since the dilator body is constructed so that the cross-sectional area of ​​the tip of the proximal region is larger than the cross-sectional area of ​​the main body, the flexibility of the main body can be improved. Therefore, the catheter assembly can improve the bending followability of the main body when inserted.

[0026] This figure shows a catheter assembly according to an embodiment. This is a magnified view of a portion of the tip side of the dilator body. This is a cross-sectional view along the axial direction of the dilator body. This is a magnified cross-sectional view of a portion of the tip of the dilator body. This is a magnified cross-sectional view of a portion of the tip of the dilator body. This is a cross-sectional view showing the state in which the dilator is inserted into the lumen of the catheter body. This is a magnified view of the dashed line portion VII shown in Figure 6. This figure shows a modified dilator.

[0027] A catheter assembly 10 and dilator 100 according to an embodiment will be described with reference to Figures 1 to 7.

[0028] <Catheter Assembly 10> The catheter assembly 10 can be used as an introducer kit known in the medical field. When the catheter assembly 10 is used as an introducer kit, the catheter 200 can be used as a sheath introducer.

[0029] As shown in Figures 1 and 6, the catheter assembly 10 includes a dilator 100 and a catheter 200. Figure 6 shows a portion of the axial cross-section of the catheter assembly 10 in the inserted state.

[0030] The operator can insert the dilator body 110 of the dilator 100 into the inside of the catheter hub 230 of the catheter 200 and into the lumen 215 of the catheter body 210, and then detachably fix the dilator hub 170 to the cap member 240 of the catheter 200.

[0031] <Catheter 200> As shown in Figures 1 and 6, the catheter 200 has a catheter body 210 having a lumen 215 into which the dilator body 110 can be inserted, and a catheter hub 230 connected to the proximal end 213 of the catheter body 210 and connectable to the dilator hub 170.

[0032] In this specification, the direction in which the catheter body 210 extends is defined as the "axial direction" and is indicated by arrows X1 and X2. The direction indicated by arrow X1 is defined as the axial tip side, and the direction indicated by arrow X2 is defined as the axial proximal end side. The axial direction of the dilator body 110 (the direction in which the central axis c1 extends) is the same as the axial direction of the catheter body 210, indicated by arrows X1 and X2. Arrows Y1 and Y2 in the figure indicate directions perpendicular to the axial direction.

[0033] The catheter 200 can be used to introduce various medical devices into a biological lumen (e.g., a blood vessel) through the lumen 215 of the catheter body 210. The specific method and procedure of use of the catheter 200 are not particularly limited, but for example, it can be used to create an access route for delivering various medical devices (e.g., stents for aortic implantation, devices used in artificial valve replacement surgery for the treatment of aortic stenosis, devices for the treatment of pulmonary thrombosis, etc.) from the blood vessel in the lower limb to various parts of the body.

[0034] The catheter assembly 10 can be used, for example, in the following procedure.

[0035] The operator connects the dilator 100 to the catheter 200 to form the catheter assembly 10, and then inserts the catheter body 210 into a perforation formed in the body that connects the outside of the body to the lumen of the body into which the catheter body 210 is to be inserted, thereby widening the perforation. The dilator 100 prevents the catheter 200 from bending or breaking when it is inserted into the lumen of the body through the perforation as described above.

[0036] Prior to inserting the catheter 200 together with the dilator 100 into the biological lumen as described above, the surgeon inserts a guidewire, which is positioned between the biological lumen and the outside of the body through a perforation formed in the body, into the dilator body 110, and inserts the dilator 100 and catheter 200 into the biological lumen along the guidewire. After inserting the tip of the dilator body 110 to a predetermined position in the biological lumen, the surgeon withdraws the dilator body 110 from the catheter body 210. The surgeon can use the lumen 215 of the catheter body 210 from which the dilator body 110 has been withdrawn as an access route to deliver various medical devices to a desired position in the biological lumen.

[0037] As shown in Figures 1 and 6, the catheter body 210 has a tip 211 with a tip opening 211a and a base 213 located inside the catheter hub 230.

[0038] The catheter body 210 has a lumen 215 that extends continuously from the tip 211 to the proximal end 213.

[0039] The proximal end 213 of the catheter body 210 is provided with a proximal opening 213a that is positioned to communicate with the inside of the catheter hub 230.

[0040] As shown in Figures 1 and 6, the tip 211 of the catheter body 210 has a tapered shape, with the outer diameter narrowing towards the tip.

[0041] The catheter body 210 can be made of, for example, polyolefins (e.g., polyethylene, polypropylene, polybutene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ionomers, or mixtures of two or more of the foregoing), polyolefin elastomers, crosslinked polyolefins, polyvinyl chloride, polyamides, polyamide elastomers, polyesters, polyester elastomers, polyurethanes, polyurethane elastomers, fluororesins (e.g., polytetrafluoroethylene, tetrafluoroethylene-ethylene copolymers, etc.), polymer materials such as polycarbonate, polystyrene, polyacetal, polyimide, polyetherimide, polyether ether ketone, or mixtures of the foregoing. Further, the catheter body 210 may have a reinforcing member such as a metal wire within the wall thickness of a tubular member formed of a polymer material or a mixture thereof.

[0042] As shown in FIG. 1, a valve body 260 is disposed inside the catheter hub 230. The valve body 260 is configured such that the dilator body 110 or a medical device inserted into a biological lumen can be passed through the valve body 260.

[0043] The valve body 260 prevents the formation of a gap between itself and the dilator body 110 or medical device when the dilator body 110 or medical device is inserted through the valve body 260. By preventing the formation of the aforementioned gap, the valve body 260 prevents blood or liquid such as physiological saline injected into the catheter hub 230 from flowing backward to the proximal end side of the cap member 240 connected to the catheter hub 230.

[0044] The catheter hub 230 has a first port portion 271 and a second port portion 272 that communicate with the interior of the catheter hub 230.

[0045] A tube 281 connected to a three-way stopcock 290 for supplying liquid such as physiological saline into the catheter body 210 can be connected to the first port portion 271.

[0046] A suction device can be connected to the second port portion 272 via a tube 282. The suction device is, for example, a syringe that can be used when performing a procedure for aspirating thrombus or the like in a vein. The arrangement of the second port portion 272 can be omitted as appropriate depending on the intended use of the catheter assembly 10 or the like.

[0047] The catheter 200 has a cap member 240 connected to the proximal end of a catheter hub 230. The cap member 240 is provided with an opening (not shown) that communicates with the inside of the catheter hub 230. An operator can insert the dilator body 110 into the inside of the catheter hub 230 and the lumen 215 of the catheter body 210 by pushing the dilator body 110 from the proximal end side of the cap member 240.

[0048] <Dilator 100> As shown in FIGS. 1 to 5, the dilator 100 includes: a dilator body 110 having a lumen 115 penetrating between a distal end 111 and a proximal end 113; and a dilator hub 170 connected to the proximal end 113 of the dilator body 110 and having an opening 177 communicating with the lumen 115 of the dilator body 110.

[0049] For the dilator body 110, for example, resin materials such as high-density polyethylene, low-density polyethylene, vinyl chloride, polyurethane, polyamide, and polyester; elastomer materials such as polyurethane elastomer, polyamide elastomer, and polyester elastomer; and combinations of two or more of these materials (such as polymer blends) can be used. Further, in the dilator 100, a low-friction resin such as PTFE (polytetrafluoroethylene) may be disposed on the inner surface forming the lumen 115 of the dilator body 110 that is composed of the above materials.

[0050] As shown in FIG. 1, the proximal end 113 of the dilator body 110 is disposed in the lumen 175 of the dilator hub 170. A proximal opening 113a formed at the proximal end 113 of the dilator body 110 communicates with the opening 177 of the dilator hub 170 via the lumen 175 of the dilator hub 170.

[0051] As shown in Figures 1 to 3, the dilator body 110 has a main body portion 120 that extends from the dilator hub 170 toward the tip, and a tip portion 130 that is located toward the tip than the main body portion 120 and has an inclined region 140A that slopes toward the tip.

[0052] The main body portion 120 extends along the axial direction so as to have a substantially constant outer diameter D1 and inner diameter d1. Therefore, the wall thickness t1 of the main body portion 120 is substantially constant along the axial direction.

[0053] Furthermore, as shown in the modified example in Figure 8, the main body portion 120 may be configured to have a first region 120A that is in contact with the base end of the tip portion 130 (the base end 153 of the base end region 150) and extends along the axial direction having a substantially constant outer diameter D1 and inner diameter d1, and a second region 120B that extends from the base end of the first region 120A toward the tip of the dilator hub 170. In this case, the second region 120B has an outer diameter that is larger than the outer diameter D1 of the first region 120A along the axial direction and an inner diameter d1 that is the same as the inner diameter d1 of the first region 120A. The first region 120A has a substantially constant wall thickness t1 along the axial direction. The second region 120B also has a greater wall thickness than the first region 120A. This allows the dilator 100 to be configured to improve the flexibility of the tip end of the main body 120 while increasing the ability of the main body 120 to transmit force toward the tip end 130 (pushyness) when the operator inserts the dilator body 110 into the biological lumen.

[0054] When the main body portion 120 has a first region 120A and a second region 120B, "outer diameter of the main body portion 120" refers to the outer diameter of the first region 120A. Also, "cross-sectional area of ​​the main body portion 120" refers to the cross-sectional area of ​​the first region 120A. When the main body portion 120 has a first region 120A and a second region 120B, the ratio of the axial length of the first region 120A to the axial length of the main body portion 120 (the sum of the axial lengths of the first region 120A and the second region 120B) is in the range of 10% to 40%. For example, the axial length of the first region 120A is 100 mm.

[0055] The tip portion 130 has a tip region 140 having an inclined region 140A, a base region 150, and an intermediate region 160 located between the tip region 140 and the base region 150.

[0056] As shown in Figures 2 and 3, the inclined region 140A has a first tapered portion 145 extending from the base end 143 of the tip region 140 toward the tip, a second tapered portion 146 extending from the tip of the first tapered portion 145 toward the tip, and a tip inclined region 147 extending from the tip of the second tapered portion 146 toward the tip.

[0057] As shown in Figures 3 and 4, the inclined region 140A is configured such that its outer and inner diameters gradually decrease toward the tip. Also, as shown in Figure 4, the tip inclined region 147 is configured such that the wall thickness of the inclined region 140A gradually decreases toward the tip.

[0058] For example, the first tapered portion 145 can be configured to have a longer axial length than the second tapered portion 146. Also, the first tapered portion 145 and the second tapered portion 146 can each be configured to have a longer axial length than the tip inclined region 147.

[0059] As shown in Figures 3 and 4, the tip 111 (the tip 141 of the tip region 140) of the dilator body 110 has a tip opening 111a that connects the lumen 115 to the outside.

[0060] As shown in Figure 5, the tip region 140 and the intermediate region 160 are adjacent in the axial direction. Therefore, the base end 143 of the tip region 140 and the tip 161 of the intermediate region 160 are located at the same position in the axial direction.

[0061] As shown in Figure 5, the intermediate region 160 and the base region 150 are adjacent in the axial direction. Therefore, the base end 163 of the intermediate region 160 and the tip 151 of the base region 150 are located at the same position in the axial direction.

[0062] As shown in Figure 5, the base region 150 and the main body 120 are adjacent in the axial direction. Therefore, the base end 153 of the base region 150 and the tip 121 of the main body 120 are located at the same position in the axial direction.

[0063] As shown in Figure 5, the outer diameter D21 of the base end 143 of the tip region 140, the outer diameter D41 of the intermediate region 160, and the outer diameter D31 of the tip 151 of the base region 150 are each configured to be larger than the outer diameter D1 of the main body 120.

[0064] As shown in Figures 1 to 3, the tip region 140 includes an inclined region 140A, so its outer diameter gradually decreases towards the tip. In this configuration, the base end 143, which has the largest outer diameter in the tip region 140, has a larger outer diameter than the tip 121 of the main body 120.

[0065] As shown in Figure 5, the intermediate region 160 has an outer diameter D41 that is substantially constant along the axial direction. Therefore, in this embodiment, the outer diameter D42 of the base end 163 of the intermediate region 160, which will be described later, is the same size as the outer diameter of the intermediate region 160.

[0066] The intermediate region 160 is configured such that the outer diameter D41 of each axial part of the intermediate region 160 is larger than the outer diameter D1 of the main body 120.

[0067] As shown in Figure 5, the base region 150 includes a second base region 150B whose outer diameter gradually decreases toward the base end in the axial direction. Therefore, the outer diameter D32 of the base end 153 of the base region 150 is the same as the outer diameter D1 (outer diameter D1 of the main body 120) of the tip 121 of the main body 120, which is located at the same position in the axial direction as the base end 153 of the base region 150. In this configuration, the outer diameter D31 of the tip 151, which has the largest outer diameter in the base region 150, is larger than the outer diameter D1 of the main body 120.

[0068] As shown in Figure 5, the inner diameter d41 of the tip 161 of the intermediate region 160 is configured to be larger than the inner diameter d3 of the base region 150.

[0069] As shown in Figure 5, the intermediate region 160 includes a second intermediate region 160B in which the inner diameter gradually decreases toward the base end in the axial direction. On the other hand, the inner diameter d3 of the base end region 150 is substantially constant along the axial direction. In this configuration, the intermediate region 160 is configured such that the inner diameter d41 of the tip 161, which has the largest inner diameter in the intermediate region 160, is larger than the inner diameter d3 of the base end region 150.

[0070] The cross-sectional area of ​​the tip 151 of the base region 150 is configured to be larger than the cross-sectional area of ​​the tip region 140, the cross-sectional area of ​​the tip 161 of the intermediate region 160, and the cross-sectional area of ​​the main body 120.

[0071] In this specification, the relative sizes of the cross-sectional areas of each part of the dilator body 110 are equivalent to the relative sizes of the wall thicknesses of each part of the dilator body 110. In other words, the larger the value of "(outer diameter of the dilator body 110 - diameter of the lumen 115 (= cross-sectional area of ​​the tube wall)) / 2 = wall thickness" obtained from the cross-sectional view of each part of the dilator body 110 perpendicular to the axis, the larger the cross-sectional area. In the following, the relative sizes of the cross-sectional areas of each part of the dilator body 110 will be replaced with the relative sizes of the wall thicknesses t1, t2, t3, and t4 of each part shown in Figure 5.

[0072] In this embodiment, the thickness t3 of the tip 151 of the base region 150 is greater than the thickness t2 of the tip region 140 (thickness at any position in the tip region 140), the thickness t4 of the tip 161 of the intermediate region 160, and the thickness t1 of the main body portion 120 (thickness at any position in the main body portion 120, or, if the main body portion 120 has the aforementioned first region 120A and second region 120B, the thickness at any position in the first region 120A).

[0073] The base region 150 has a second base region 150B, as described later, in which the inner diameter is constant in the axial direction and the outer diameter gradually decreases toward the base end. The first base region 150A, located toward the tip of the second base region 150B in the base region 150, has a constant outer diameter and inner diameter. Therefore, the tip 151 of the base region 150 where the first base region 150A is located has the greatest wall thickness in the base region 150.

[0074] The base end 153 of the base region 150 is located at the same position in the axial direction as the main body portion 120. Therefore, the thickness of the base end 153 of the base region 150 is the same as the thickness t1 of the main body portion 120. Also, the base end 163 of the intermediate region 160 is located at the same position in the axial direction as the tip 151 of the base region 150. Therefore, the thickness of the base end 163 of the intermediate region 160 is the same as the thickness of the tip 151 of the base region 150.

[0075] As shown in Figure 6, the catheter assembly 10 is configured such that, in the insertion state, the tip 211 of the catheter body 210 is located in the proximal region 150 of the dilator body 110.

[0076] When inserted, the catheter assembly 10 is positioned such that the portion located more towards the tip 211 of the catheter body 210 is exposed.

[0077] As shown in Figure 5, the outer diameter D42 of the base end 163 of the intermediate region 160 and the outer diameter D31 of the tip 151 of the base end region 150 are approximately the same.

[0078] The intermediate region 160 has a straight section 165 that extends with a substantially constant outer and inner diameter.

[0079] The straight section 165 is composed of a portion that extends in the intermediate region 160 with a constant outer and inner diameter. In this embodiment, the straight section 165 is composed of the first intermediate region 160A, which will be described later.

[0080] As shown in Figures 4 and 5, the outer diameter D22 of the tip 141 of the tip region 140 (the tip 111 of the dilator body 110) is smaller than the outer diameter D1 of the main body 120, and the inner diameter d2 of the tip 141 of the tip region 140 is smaller than the inner diameter d1 of the main body 120.

[0081] In this embodiment, the tip of the tip region 140 is provided with a tip inclined region 147 that is sharply inclined toward the tip side, so that the inner diameter d2 of the tip 141 of the tip region 140 is approximately the same size as the diameter of the tip opening 111a.

[0082] As shown in Figures 5 and 6, the intermediate region 160 includes a first intermediate region 160A and a second intermediate region 160B located on the base end side of the first intermediate region 160A and adjacent to the base end region 150.

[0083] The inner diameter of the second intermediate region 160B increases from the base to the tip.

[0084] As mentioned above, the straight portion 165 of the intermediate region 160 has a constant outer diameter in the axial direction. In addition, the inner diameter is constant in the first intermediate region 160A, and in the second intermediate region 160B, the inner diameter increases from the base end to the tip. Therefore, in the intermediate region 160, the wall thickness is constant in the axial direction in the first intermediate region 160A, and the wall thickness gradually increases towards the base end in the second intermediate region 160B.

[0085] As shown in Figures 5 and 6, the base region 150 has a first base region 150A and a second base region 150B located on the base side of the first base region 150A and adjacent to the main body 120.

[0086] The outer diameter of the second proximal region 150B is configured to decrease from the tip towards the proximal end.

[0087] The base region 150 has a constant inner diameter d3 along the axial direction. The first base region 150A has a constant outer diameter along the axial direction, while the second base region 150B has an outer diameter that decreases from the tip towards the base. Therefore, in the base region 150, the wall thickness is constant in the axial direction in the first base region 150A, and the wall thickness gradually decreases towards the base in the second base region 150B.

[0088] As shown in Figures 6 and 7, the catheter assembly 10 is configured such that, in the insertion state, the tip 211 of the catheter body 210 is located in the first proximal region 150A.

[0089] As shown in Figure 7, when the catheter assembly 10 is inserted, it is positioned such that the inner surface of a predetermined range of the catheter body 210, from the tip 211 to the proximal end, is in contact with the outer surface of the first proximal region 150A.

[0090] The outer diameter of the second proximal region 150B gradually decreases from the tip to the proximal end. Also, the inner diameter d5 of the catheter body 210 is approximately constant along the axial direction. Therefore, when the catheter body 210 is inserted, the inner surface of the catheter body 210 does not come into contact with the outer surface of the second proximal region 150B, which is located more proximal than the first proximal region 150A. As a result, when the catheter body 210 is inserted, a gap g is formed between the second proximal region 150B and the catheter body 210.

[0091] As shown in Figure 4, the tip region 140 further has a tip inclined region 147 at its very tip, which is inclined at an acute angle.

[0092] The term "tip" above refers to a predetermined range from the position including the tip 141 of the tip region 140 (the tip 111 of the dilator body 110) toward the base end. Furthermore, the term "acute angle" above refers to an acute angle, as shown in Figure 4 (the angle between the inner wall surface of the tip 141 of the tip region 140 and the inclined region 140A).

[0093] As shown in Figure 7, the catheter assembly 10 can be configured such that, in the inserted state, the distance (axial distance) L1 between the tip 151 of the proximal region 150 and the tip 211 of the catheter body 210 is at least half and no more than four times the difference between the outer diameter D1 of the main body portion 120 and the inner diameter d5 of the catheter body 210 (outer diameter D1 - inner diameter d5).

[0094] The following describes examples of dimensions for each part of the catheter assembly 10. These examples are merely illustrative and do not limit the scope of the present invention.

[0095] The outer diameter D1 of the main body 120 (see Figure 5) can be set to, for example, 3.0 mm to 8.0 mm.

[0096] The inner diameter d1 of the main body 120 (see Figure 5) can be set to, for example, 1.0 mm to 4.0 mm.

[0097] The wall thickness t1 of the main body 120 (see Figure 5) can be set to, for example, 0.5 mm to 3.5 mm.

[0098] Furthermore, if the main body 120 has the aforementioned first region 120A and second region 120B, the axial length of the first region 120A can be configured, for example, 50 mm to 200 mm, and the axial length of the second region 120B can be configured, for example, 250 mm to 600 mm. In this case, the outer diameter of the first region 120A (outer diameter D1 of the main body 120) can be configured, for example, 3.0 mm to 6.0 mm, and the outer diameter of the second region 120B can be configured, for example, 5.0 mm to 8.0 mm. In addition, the inner diameter of the first region 120A (inner diameter d1 of the main body 120) and the inner diameter of the second region 120B can be configured, for example, 1.0 mm to 4.0 mm. Furthermore, the thickness of the first region (thickness t1 of the main body portion 120) can be set to, for example, 0.5 mm to 3.0 mm, and the thickness of the second region can be set to, for example, 0.5 mm to 3.5 mm.

[0099] The outer diameter D21 (see Figure 5) of the base end 143 of the tip region 140 can be set to, for example, 5.0 to 8.3 mm.

[0100] The outer diameter D22 of the tip 141 of the tip region 140 (see Figure 4) can be set to, for example, 1.2 mm to 2.0 mm.

[0101] The inner diameter d2 of the tip 141 of the tip region 140 (see Figure 4) can be set to, for example, 0.9 mm to 1.5 mm.

[0102] The thickness t2 of the tip region 140 (see Figures 4 and 5) can be configured such that, for example, the thickness transitions in the inclined region 140A from 0.15 mm to 2.0 mm, in the first tapered portion 145 and the second tapered portion 146 from 0.3 mm to 2.0 mm, and in the tip inclined region 147 from 0.15 mm to 0.3 mm.

[0103] The outer diameter D31 (see Figure 5) of the tip 151 of the base region 150 can be set to, for example, 5.0 mm to 8.3 mm.

[0104] The inner diameter d3 of the base region 150 (see Figure 5) can be set to, for example, 1.0 mm to 4.0 mm.

[0105] The thickness t3 of the tip 151 of the base region 150 (see Figure 5) can be set to, for example, 1.5 mm to 3.0 mm.

[0106] The outer diameter D41 of the intermediate region 160 (see Figure 5) can be set to, for example, 5.0 mm to 8.3 mm. The outer diameter D42 of the base end 163 of the intermediate region 160 (see Figure 5) can be formed to be the same size as the outer diameter D41 of the intermediate region 160.

[0107] The inner diameter d41 of the tip 161 of the intermediate region 160 (see Figure 5) can be set to, for example, 4.0 mm to 6.3 mm.

[0108] The thickness t4 (see Figure 5) of the tip 161 of the intermediate region 160 can be set to, for example, 0.5 mm to 2.0 mm.

[0109] The distance L1 (see Figure 7) between the tip 151 of the proximal region 150 and the tip 211 of the catheter body 210 in the inserted state can be set to, for example, 1.0 mm to 10.0 mm. For example, if the distance L1 is 8.0 mm, the outer diameter D1 of the main body portion 120 can be 6 mm, and the inner diameter d5 of the catheter body 210 can be 8.3 mm.

[0110] The inner diameter d5 of the catheter body 210 (see Figure 5) can be set to, for example, 5.0 mm to 8.3 mm.

[0111] The effects and advantages of this embodiment will be described below.

[0112] The catheter assembly 10 comprises a dilator 100 comprising a dilator body 110 having a lumen 115 penetrating between a tip 111 and a proximal end 113, and a dilator hub 170 connected to the proximal end 113 of the dilator body 110 and having an opening 177 communicating with the lumen 115 of the dilator body 110; and a catheter 200 comprising a catheter body 210 having a lumen 215 into which the dilator body 110 can be inserted, and a catheter hub 230 connected to the proximal end 213 of the catheter body 210 and connectable to the dilator hub 170. The dilator body 110 comprises a main body portion 120 extending from the dilator hub 170 toward the tip, and a tip portion 130 located toward the tip of the main body portion 120 and having an inclined region 140A that slopes toward the tip. The catheter assembly 10 has a tip region 140 having 47, a proximal region 150, and an intermediate region 160 located between the tip region 140 and the proximal region 150. The outer diameter D21 of the proximal end 143 of the tip region 140, the outer diameter D41 of the intermediate region 160, and the outer diameter D31 of the tip 151 of the proximal region 150 are each configured to be larger than the outer diameter D1 of the main body 120. The inner diameter d41 of the tip 161 of the intermediate region 160 is configured to be larger than the inner diameter d3 of the proximal region 150. The cross-sectional area of ​​the tip 151 of the proximal region 150 is configured to be larger than the cross-sectional area of ​​the tip region 140, the cross-sectional area of ​​the tip 161 of the intermediate region 160, and the cross-sectional area of ​​the main body 120. In the inserted state, the catheter assembly 10 is configured such that the tip 211 of the catheter body 210 is located in the proximal region 150 of the dilator body 110.

[0113] As described above, the dilator body 110 has a main body portion 120 and a tip portion 130 located further forward than the main body portion 120 and having a sloping region 140A whose outer diameter decreases towards the tip. By having a sloping region 140A, the tip portion 130 can gradually widen a perforation formed in the body from the tip side to the proximal side when the dilator body 110 is inserted into a biological lumen. This prevents the perforation formed in the body from being rapidly widened when the dilator body 110 is inserted into a biological lumen. Therefore, the operator can reduce the burden on the patient during procedures using the catheter assembly 10.

[0114] Furthermore, the tip portion 130 of the dilator body 110 has a tip region 140 with an inclined region 140A, a base region 150, and an intermediate region 160 located between the tip region 140 and the base region 150. The outer diameter D21 of the base end 143 of the tip region 140, the outer diameter D41 of the intermediate region 160, and the outer diameter D31 of the tip 151 of the base region 150 are all configured to be larger than the outer diameter D1 of the main body portion 120. On the other hand, the inner diameter d41 of the tip 161 of the intermediate region 160 is configured to be larger than the inner diameter d3 of the base region 150. As a result, when a guide wire is inserted into the lumen 115 of the dilator body 110, the contact area between the guide wire and the inner surface of the intermediate region 160 is reduced. As a result, the catheter assembly 10 can improve the ease of inserting the guidewire into the lumen 115 of the dilator body 110, and improve the operability of the guidewire when it is inserted into the lumen 115 of the dilator body 110 (operability when moving the guidewire axially relative to the dilator body 110).

[0115] Furthermore, the dilator body 110 is configured such that the cross-sectional area of ​​the tip 151 of the proximal region 150 is larger than the cross-sectional area of ​​the tip region 140, the cross-sectional area of ​​the tip 161 of the intermediate region 160, and the cross-sectional area of ​​the main body 120. As a result, the intermediate region 160 and the tip region 140, which are located closer to the tip than the proximal region 150, are formed with a smaller cross-sectional area (thinner walls) than the tip 151 of the proximal region 150. This improves the flexibility of the intermediate region 160 and the tip region 140 located closer to the tip than the proximal region 150, and reduces the insertion load. Therefore, the dilator body 110 improves the ability of the intermediate region 160 and the tip region 140 to follow the guidewire. As a result, even when the dilator body 110 is configured with a large diameter, the catheter assembly 10 can achieve high followability of the dilator body 110 to the guidewire and high insertability of the dilator body 110 into the biological lumen. The dilator body 110 has improved followability with respect to the guide wire, making it easier for the intermediate region 160 and the tip region 140 to deform along the guide wire. This effectively prevents damage to biological tissue caused by contact between the tip 111 and biological tissue.

[0116] Furthermore, the catheter assembly 10 is configured such that, in the inserted state, the tip 211 of the catheter body 210 is located in the proximal region 150 of the dilator body 110. As mentioned above, the cross-sectional area of ​​the proximal region 150 is larger than the cross-sectional area of ​​the tip region 140, the cross-sectional area of ​​the tip 161 of the intermediate region 160, and the cross-sectional area of ​​the main body portion 120. In other words, the proximal region 150 is thicker than the tip region 140, the tip of the intermediate region 160, and the main body portion 120. Therefore, in the inserted state, the catheter assembly 10 can suppress the deformation of the dilator body 110 into a flattened cross-sectional shape by collapsing toward the lumen 115 side of the dilator body 110 at the proximal region 150 (near the tip 211 of the catheter body 210). As a result, when the catheter assembly 10 is inserted, it is possible to prevent a gap from forming between the tip 211 of the catheter body 210 and the dilator body 110 when the catheter assembly 10 passes through a bend in the biological lumen or the like.

[0117] Furthermore, since the dilator body 110 has a cross-sectional area at the tip 151 of the proximal region 150 that is larger than the cross-sectional area of ​​the main body 120, the flexibility of the main body 120 can be improved. As a result, the catheter assembly 10 can improve the flexibility of the main body 120 in the inserted state (particularly the flexibility to follow the curved course of the blood vessel and the guide wire at the tip of the main body 120).

[0118] Furthermore, the outer diameter D42 of the base end 163 of the intermediate region 160 and the outer diameter D31 of the tip 151 of the base end region 150 are the same, and the intermediate region 160 has a straight portion 165 that extends with a substantially constant outer and inner diameter.

[0119] The straight portion 165 of the intermediate region 160 extends with a substantially constant outer and inner diameter, and therefore has a substantially constant cross-sectional area (wall thickness) along the axial direction. As a result, the intermediate region 160 located between the tip region 140 and the base region 150 of the dilator body 110 can smooth out the change in rigidity between the tip region 140 and the base region 150. This improves the followability of the dilator body 110 to the preceding guidewire between the tip region 140, the intermediate region 160, and the base region 150, thereby reducing the insertion resistance of the dilator body 110 into the biological lumen.

[0120] Furthermore, the outer diameter D22 of the tip 141 of the tip region 140 is smaller than the outer diameter D1 of the main body 120, and the inner diameter d2 of the tip 141 of the tip region 140 is smaller than the inner diameter d1 of the main body 120.

[0121] Since the outer diameter D22 of the tip 141 of the tip region 140 of the dilator body 110 is smaller than the outer diameter D1 of the main body 120, the resistance to insertion of the tip 141 of the tip region 140 into the biological lumen can be reduced when the dilator body 110 is inserted into the biological lumen. Furthermore, since the inner diameter d1 of the main body 120 of the dilator body 110 is larger than the inner diameter d2 of the tip 141 of the tip region 140, the wall thickness t1 of the main body 120 can be reduced, and an increase in the rigidity of the main body 120 can be suppressed. As a result, when the catheter assembly 10 is inserted, a decrease in the ability to follow the guidewire can be suppressed at a position near the tip 211 of the catheter body 210 (particularly at a position near the proximal end 153 of the proximal region 150). Furthermore, since the inner diameter d2 of the tip 141 of the tip region 140 of the dilator body 110 is smaller than the inner diameter d1 of the main body portion 120, the contact area of ​​the guide wire in contact with the inner surface of the main body portion 120 can be reduced. As a result, the dilator body 110 can suppress the increase in the resistance of inserting the guide wire into the dilator body 110, thereby improving the operator's operability.

[0122] Furthermore, the intermediate region 160 has a first intermediate region 160A and a second intermediate region 160B located on the base end side of the first intermediate region 160A and adjacent to the base end region 150, and the inner diameter of the second intermediate region 160B increases from the base end to the tip.

[0123] The dilator body 110 has an inner diameter of the second intermediate region 160B that increases from the base to the tip. Therefore, when a guidewire is inserted from the tip opening 111a of the dilator body 110, the guidewire can be smoothly moved from the second intermediate region 160B towards the base region 150. This improves the ease of inserting the guidewire into the lumen 115 of the dilator body 110.

[0124] Furthermore, the proximal region 150 has a first proximal region 150A and a second proximal region 150B located on the proximal side of the first proximal region 150A and adjacent to the main body 120. The outer diameter of the second proximal region 150B is configured to decrease from the tip to the proximal end, and the catheter assembly 10 is configured such that, in the insertion state, the tip 211 of the catheter body 210 is located in the first proximal region 150A.

[0125] The dilator body 110 is configured such that the outer diameter of the second proximal region 150B decreases from the tip to the proximal end. Therefore, when the dilator body 110 is moved towards the proximal end in order to remove it from the catheter hub 230, the dilator body 110 can be smoothly moved along the inside of the valve body 260 located inside the catheter hub 230. This prevents damage to the valve body 260 when the dilator body 110 is removed from the catheter 200. In addition, in the inserted state, the tip 211 of the catheter body 210 is located in the first proximal region 150A, which is located closer to the tip than the second proximal region 150B, where the outer diameter decreases from the tip to the proximal end. Therefore, the catheter assembly 10 can more effectively suppress deformation of the dilator body 110 into a flattened cross-sectional shape by collapsing toward the lumen 115 of the dilator body 110 near the tip 211 of the catheter body 210 when inserted.

[0126] Furthermore, the tip region 140 has an acutely inclined tip region 147 at its very tip.

[0127] The dilator body 110 has a sharply inclined tip region 147 at its very tip, which reduces insertion resistance when inserting it into perforations formed in the patient's skin or into a biological lumen. Furthermore, because the dilator body 110 has a tip inclined region 147, it can improve the ability of the leading edge (tip 111) to follow the guidewire.

[0128] Furthermore, the catheter assembly 10 is configured such that, in the inserted state, the distance L1 between the tip 151 of the proximal region 150 and the tip 211 of the catheter body 210 is at least half and no more than four times the difference between the outer diameter D1 of the main body portion 120 and the inner diameter d5 of the catheter body 210 (outer diameter D1 - inner diameter d5).

[0129] The catheter assembly 10 is configured such that the distance L1 is at least half and no more than four times (outer diameter D1 - inner diameter d5), so that even if the position of the tip 211 of the catheter body 210 shifts axially when inserted into a biological lumen in the insertion state, or due to the bending of the dilator body 110, the tip 211 of the catheter 200 can be positioned in the proximal region 150. When the catheter assembly 10 is configured such that the distance L1 is at least half half (outer diameter D1 - inner diameter d5), even if the position of the tip 211 of the catheter body 210 shifts axially when inserted into a biological lumen in the insertion state, or due to the bending of the dilator body 110, the tip 211 of the catheter body 210 can be effectively prevented from moving beyond the tip 151 of the proximal region 150. Therefore, the catheter assembly 10 can more effectively prevent a gap from forming between the inner surface of the tip 211 of the catheter body 210 and the outer surface of the dilator body 110 due to deformation of the dilator body 110, which would otherwise reduce the ease of insertion into a biological lumen. Furthermore, when the distance L1 is four times or less of (outer diameter D1 - inner diameter d5), the catheter assembly 10 can smooth out the physical changes between the intermediate region 160, the proximal region 150 located between the proximal end 163 of the intermediate region 160 and the tip 211 of the catheter body 210, and the vicinity of the tip 211 of the catheter body 210 when inserted. This improves the flexibility of the proximal region 150, which is located closer to the tip than where the tip 211 of the catheter body 210 is located. Therefore, the catheter assembly 10 can improve its ability to follow the guidewire when inserted.

[0130] Furthermore, the dilator 100 comprises a dilator body 110 having a lumen 115 penetrating between the tip 111 and the base 113, and a dilator hub 170 connected to the base 113 of the dilator body 110 and having an opening 177 communicating with the lumen 115 of the dilator body 110. The dilator body 110 has a main body portion 120 extending from the dilator hub 170 toward the tip, and a tip portion 130 located toward the tip than the main body portion 120 and having an inclined region 140A that slopes toward the tip. The tip portion 130 has a tip region 140 having a tip inclined region 147, and a base region 15 The structure comprises a tip region 140 and an intermediate region 160 located between the tip region 140 and the base region 150. The outer diameter D21 of the base end 143 of the tip region 140, the outer diameter D41 of the intermediate region 160, and the outer diameter D31 of the tip 151 of the base region 150 are each configured to be larger than the outer diameter D1 of the main body 120. The inner diameter d41 of the tip 161 of the intermediate region 160 is configured to be larger than the inner diameter d3 of the base region 150. The cross-sectional area of ​​the tip 151 of the base region 150 is configured to be larger than the cross-sectional area of ​​the tip region 140, the cross-sectional area of ​​the tip 161 of the intermediate region 160, and the cross-sectional area of ​​the main body 120.

[0131] According to the dilator 100 described above, even when the dilator body 110 is configured with a large diameter, it is possible to achieve high followability of the dilator body 110 with respect to the guide wire and high insertability of the dilator body 110 into the biological lumen. As for the large-diameter dilator body 110, for example, one in which the maximum outer diameter of the tip portion 130 is configured to be 7.8 mm to 8.3 mm is particularly preferred.

[0132] Although the catheter and dilator according to the present invention have been described above through embodiments, the present invention is not limited to what has been described herein and can be modified as appropriate based on the claims.

[0133] The structure of each part and the arrangement of components described in the specification may be changed as appropriate, and the use of additional components shown in the figures may be omitted or other additional components may be used as appropriate.

[0134] This application is based on Japanese Patent Application No. 2025-044201, filed on 19 March 2025, the disclosures of which are incorporated herein by reference.

[0135] 10 Catheter assembly 100 Dilator 110 Dilator body 111 Tip of dilator body 111a Tip opening 113 Proximal end of dilator body 115 Lumen of dilator body 120 Body part 121 Tip of body part 130 Tip part 140 Tip region 140A Inclined region 141 Tip of tip region 143 Proximal end of tip region 145 First tapered section 146 Second tapered section 147 Inclined tip region 150 Proximal region 150A First proximal region 150B Second proximal region 151 Tip of proximal region 153 Proximal end of proximal region 160 Intermediate region 160A First intermediate region 160B Second intermediate region 161 Tip of intermediate region 163 Proximal end of intermediate region 165 Straight section 170 Dilator hub 175 Lumen of the dilator hub 200 Catheter 210 Catheter body 211 Tip of the catheter body 211a Tip opening 215 Lumen of the catheter body 230 Catheter hub D1 Outer diameter of the main body D21 Outer diameter of the proximal end of the tip region D22 Outer diameter of the tip of the tip region D31 Outer diameter of the tip of the proximal region D32 Outer diameter of the proximal end of the proximal region D41 Outer diameter of the intermediate region D42 Outer diameter of the proximal end of the intermediate region L1 Distance between the tip of the proximal region and the tip of the catheter body in the inserted state c1 Central axis of the dilator body d1 Inner diameter of the main body d2 Inner diameter of the tip of the tip region d3 Inner diameter of the proximal region d41 Inner diameter of the tip of the intermediate region d5 Inner diameter of the catheter body t1 Wall thickness of the main body t2 Wall thickness of the tip region t3 Wall thickness of the tip of the proximal region t4 Wall thickness of the tip of the intermediate region

Claims

1. A dilator comprising: a dilator body having a lumen penetrating between the tip and the base; a dilator hub connected to the base end of the dilator body and having an opening communicating with the lumen of the dilator body; a catheter comprising: a catheter body having a lumen into which the dilator body can be inserted; and a catheter hub connected to the base end of the catheter body and connectable to the dilator hub; wherein the dilator body comprises: a main body portion extending from the dilator hub toward the tip; and a tip portion located toward the tip than the main body portion and having an inclined region inclined toward the tip; wherein the tip portion comprises: a tip region having the inclined region; a base region; and an intermediate region located between the tip region and the base region; wherein the outer diameter of the base end of the tip region, the outer diameter of the intermediate region, and the outer diameter of the tip of the base region are each larger than the outer diameter of the main body portion; and the inner diameter of the tip of the intermediate region is configured to be larger than the inner diameter of the base region. The catheter assembly is configured such that the cross-sectional area of ​​the tip of the proximal region is larger than the cross-sectional area of ​​the tip region, the cross-sectional area of ​​the tip of the intermediate region, and the cross-sectional area of ​​the main body, and the tip of the catheter body is located in the proximal region when the dilator body is inserted into the lumen of the catheter body.

2. The catheter assembly according to claim 1, wherein the outer diameter of the proximal end of the intermediate region and the outer diameter of the tip of the proximal region are the same, and the intermediate region has a straight portion extending with substantially constant outer and inner diameters.

3. The catheter assembly according to claim 2, wherein the outer diameter of the tip of the tip region is smaller than the outer diameter of the main body, and the inner diameter of the tip of the tip region is smaller than the inner diameter of the main body.

4. The catheter assembly according to claim 2 or 3, wherein the intermediate region comprises a first intermediate region and a second intermediate region located on the proximal end side of the first intermediate region and adjacent to the proximal region, and the inner diameter of the second intermediate region increases from the proximal end to the tip.

5. The catheter assembly according to claim 1, wherein the proximal region comprises a first proximal region and a second proximal region located on the proximal side of the first proximal region and adjacent to the main body, the outer diameter of the second proximal region is configured to decrease from the tip to the proximal, and the tip of the catheter body is located in the first proximal region when the dilator body is inserted into the lumen of the catheter body.

6. The catheter assembly according to claim 1, wherein the tip region further has a tip-inclined region that is inclined at an acute angle at its very tip.

7. The catheter assembly according to claim 1, wherein, when the dilator body is inserted into the lumen of the catheter body, the distance between the tip of the proximal region and the tip of the catheter body is at least half and no more than four times the difference between the outer diameter of the body portion and the inner diameter of the catheter body.

8. A dilator comprising: a dilator body having a lumen that penetrates between a tip and a base; and a dilator hub connected to the base end of the dilator body and having an opening that communicates with the lumen of the dilator body, wherein the dilator body has a main body portion extending from the dilator hub toward the tip, and a tip portion located toward the tip than the main body portion and having an inclined region that slopes toward the tip, wherein the tip portion has a tip region having the inclined region, a base region, and an intermediate region located between the tip region and the base region, wherein the outer diameter of the base end of the tip region, the outer diameter of the intermediate region, and the outer diameter of the tip of the base region are each configured to be larger than the outer diameter of the main body portion, the inner diameter of the tip of the intermediate region is configured to be larger than the inner diameter of the base region, and the cross-sectional area of ​​the tip of the base region is configured to be larger than the cross-sectional area of ​​the tip region, the cross-sectional area of ​​the tip of the intermediate region, and the cross-sectional area of ​​the main body portion.

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