Dilator kit

Abstract

This dilator kit comprises: a catheter having a lumen; and a dilator, the dilator being accommodated in the lumen of the catheter in an assembled state. The catheter has a tip-side engagement section and a base-side engagement section that respectively engage with the dilator in the assembled state. The dilator has a tip-side engaged section that engages with the tip-side engagement section of the catheter and a base-side engaged section that engages with the base-side engagement section of the catheter in the assembled state. In a separated state in which the catheter and the dilator are separated from each other, the length between the tip-side engaged section and the base-side engaged section of the dilator is greater than the length between the tip-side engagement section and the base-side engagement section of the catheter.

Description

Technical Field

[0001] The present invention relates to a dilator kit.

Background Art

[0002] As a device for assisting the insertion of a catheter into a living tissue, a dilator is known. The dilator is long and has a pointed tip. When inserting a catheter into a living tissue, the dilator is inserted through the catheter, the dilator is accommodated in the lumen of the catheter, and the tip of the dilator is exposed from the tip-side opening of the catheter (hereinafter also referred to as the "assembled state"). The tip portion of the guide wire is previously inserted into the living tissue using a puncture needle or the like, and along this guide wire, the assembled dilator kit is inserted into the living tissue from the tip of the dilator. Since the subcutaneous tissue can be expanded by the tip portion of the dilator, the insertion resistance of the catheter into the living tissue can be reduced. For example, Patent Document 1 discloses a catheter assembly including a catheter and a dilator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when dilating subcutaneous tissue with the tip of the dilator, resistance from the skin and subcutaneous tissue is encountered, so it is necessary to push in with a certain degree of force. In this regard, the technology described in Patent Document 1 has a configuration in which the tip of the catheter is simply aligned with the outer surface of the dilator base which has a substantially constant outer diameter. As a result, the catheter, when subjected to pushing force from the hand, extends in the direction of pushing, or the dilator, when subjected to resistance from the skin, retracts (moves) towards the proximal side within the catheter, which presents a problem as it makes insertion of the catheter into biological tissue difficult.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a dilator kit that allows for easy insertion of a catheter into biological tissue. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a dilator kit is provided comprising a catheter having a lumen and a dilator, wherein in an assembled state the dilator is housed in the lumen of the catheter. In this dilator kit, the catheter has a tip-side engaging portion and a proximal-side engaging portion that engage with the dilator, respectively, in the assembled state, the dilator has a tip-side engaged portion that engages with the tip-side engaging portion of the catheter and a proximal-side engaged portion that engages with the proximal-side engaging portion of the catheter, and in a separated state where the catheter and the dilator are separated, the length between the tip-side engaged portion and the proximal-side engaged portion of the dilator is longer than the length between the tip-side engaged portion and the proximal-side engaged portion of the catheter.

[0008] In this configuration, when the catheter and dilator are separated, the length between the tip-side engaged portion and the proximal-side engaged portion of the dilator is longer than the length between the tip-side engaged portion and the proximal-side engaged portion of the catheter. Therefore, in the assembled state where the dilator is housed in the lumen of the catheter, the catheter is extended longitudinally, and the tip-side engaged portion and the tip-side engaged portion engage, as well as the proximal-side engaged portion and the proximal-side engaged portion engage. Thus, in this dilator kit configuration, the catheter is already extended in the assembled state, which suppresses the extension of the catheter in the pushing direction (longitudinal direction) when subjected to pushing force from the hand during insertion into biological tissue. Furthermore, in the assembled state, since the tip-side engaged portion and the proximal-side engaged portion are engaged, the occurrence of the dilator retracting towards the proximal side within the catheter due to resistance from the skin can be suppressed. As a result, this dilator kit configuration allows for easy insertion of the catheter into biological tissue.

[0009] (2) In the dilator kit of the above form, when the length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the assembled state is defined as the first length, and the length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the separated state is defined as the second length, the difference between the first length and the second length may be within the range of 1 mm or more and 30 mm or less. With this configuration, the difference between the first length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the assembled state and the second length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the separated state (first length - second length) is within the range of 1 mm or more and 30 mm or less. Therefore, it is possible to suppress the elongation of the catheter in the direction of pushing when subjected to pushing force from the hand, and to suppress excessive elongation of the catheter when changing from the separated state to the assembled state.

[0010] (3) In the dilator kit of the above form, the difference between the first length and the second length may be within the range of 5 mm or more and 15 mm or less. With this configuration, the difference between the first length and the second length (first length - second length) is within the range of 5 mm or more and 15 mm or less. Therefore, the elongation of the catheter in the direction of pushing when subjected to pushing force from the hand can be further suppressed, and excessive elongation of the catheter when changing from a separated state to an assembled state can be further suppressed.

[0011] (4) In the dilator kit of the above form, the elastic modulus of the catheter may be smaller than the elastic modulus of the dilator. With this configuration, the elastic modulus of the catheter is smaller than that of the dilator, which improves catheter delivery and facilitates skin dilation by the dilator.

[0012] (5) In the dilator kit of the above form, the catheter has a hollow shaft portion, and the dilator has an elongated body portion, and the body portion of the dilator is provided with a tapered portion whose outer diameter gradually increases from the tip end to the proximal end, and in the assembled state, the inner circumferential surface of the tip portion of the hollow shaft portion and the outer circumferential surface of the tapered portion engage with each other, so that the inner circumferential surface of the tip portion of the hollow shaft portion functions as the tip-side engaging portion, and the outer circumferential surface of the tapered portion functions as the tip-side engaged portion. In this configuration, the inner circumferential surface of the tip of the hollow shaft portion of the catheter and the outer circumferential surface of the tapered portion of the dilator engage with each other. As a result, the inner circumferential surface of the tip of the hollow shaft portion functions as the tip-side engaging portion, and the outer circumferential surface of the tapered portion functions as the tip-side engaged portion. Therefore, by utilizing the lumen (device lumen) that is commonly provided in catheters and the tapered structure at the tip that is often commonly provided in dilators, an engagement structure between the tip-side engaging portion and the tip-side engaged portion can be realized.

[0013] (6) In the dilator kit of the above form, the catheter further has a first connector provided at the base end of the hollow shaft portion, and the dilator further has a second connector provided at the base end of the main body portion, and in the assembled state, the outer circumferential surface of the first connector and the inner circumferential surface of the second connector engage with each other, so that the outer circumferential surface of the first connector functions as the base end engaging portion and the inner circumferential surface of the second connector functions as the base end engaged portion. In this configuration, the outer circumferential surface of the catheter's first connector and the inner circumferential surface of the dilator's second connector engage with each other, so that the outer circumferential surface of the first connector functions as the proximal end engaging portion and the inner circumferential surface of the second connector functions as the proximal end engaged portion. Therefore, an engagement structure between the proximal end engaging portion and the proximal end engaged portion can be realized by using connectors that are commonly provided in catheters and dilators.

[0014] (7) In the dilator kit of the above form, the hollow shaft portion of the catheter is provided with a tip tapered portion in which both the outer diameter and inner diameter gradually increase from the tip side to the proximal end, and a large diameter portion having a substantially constant outer diameter located on the proximal end side of the tip tapered portion, and in the longitudinal cross section of the hollow shaft portion, when the acute angle formed by the outer circumferential surface of the tip tapered portion and the outer circumferential surface of the large diameter portion is defined as the first acute angle, and the acute angle formed by the inner circumferential surface of the tip tapered portion and the outer circumferential surface of the large diameter portion is defined as the second acute angle, the first acute angle may be larger than the second acute angle. With this configuration, in the longitudinal cross-section of the hollow shaft portion of the catheter, the first acute angle formed by the outer circumferential surface of the tapered tip portion and the outer circumferential surface of the wide-diameter portion is larger than the second acute angle formed by the inner circumferential surface of the tapered tip portion and the outer circumferential surface of the wide-diameter portion. As a result, the wall thickness of the tapered tip portion of the catheter can be gradually reduced from the proximal end to the tip. Consequently, the tip side of the tapered tip portion can be made more flexible compared to the proximal end, and the step difference between the tip of the catheter and the dilator in the assembled state can be reduced.

[0015] Incidentally, the present invention can be realized in various forms. For example, it can be realized in the form of a dilator, a catheter, a dilator kit having a dilator and a catheter, a dilator kit having a medical device other than a dilator and a catheter, methods for manufacturing these, and the like.

Brief Description of the Drawings

[0016] [Figure 1] It is an explanatory diagram illustrating the configuration of a dilator kit. [Figure 2] It is an explanatory diagram illustrating the configuration of the dilator kit in the assembled state. [Figure 3] It is an explanatory diagram illustrating the cross-sectional configuration of the tip side of the dilator kit of FIG. 2. [Figure 4] It is a diagram showing a state where the dilator kit of the present embodiment is inserted into a living tissue. [Figure 5] It is a diagram showing a state where the dilator kit of the comparative example is inserted into a living tissue. [Figure 6] It is a diagram showing a state where the dilator kit of the comparative example is inserted into a living tissue. [Figure 7] It is an explanatory diagram illustrating the configuration of the dilator kit of the second embodiment. [Figure 8] It is an explanatory diagram illustrating the configuration of the dilator kit of the third embodiment. [Figure 9] It is an explanatory diagram illustrating the configuration of the dilator kit of the fourth embodiment. [Figure 10] It is an explanatory diagram illustrating the configuration of the dilator kit of the fifth embodiment. [Figure 11] It is an explanatory diagram illustrating the configuration of the dilator kit of the sixth embodiment. [Figure 12] It is an explanatory diagram illustrating the configuration of the dilator kit of the seventh embodiment.

Modes for Carrying Out the Invention

[0017] <First Embodiment> Figure 1 is an explanatory diagram illustrating the configuration of a dilator kit. Dilator kits 1 and 2 comprise a catheter 1 and a dilator 2. Figure 1 shows dilator kits 1 and 2 in a separated state (hereinafter also referred to as the "separated state"). Figure 1 also shows the lumen formed inside catheter 1 and dilator 2 with dashed lines. The dilator kits 1 and 2 of this embodiment have a configuration described later that allows catheter 1 to be easily inserted into biological tissue.

[0018] In Figure 1, the axis passing through the centers of catheter 1 and dilator 2 is represented by axis O (dotted line). Hereafter, the centers of catheter 1 and dilator 2 in the inserted state will be assumed to coincide with axis O, but the centers of each in the inserted state may differ. Figure 1 also illustrates mutually orthogonal XYZ axes. The X axis corresponds to the longitudinal direction of catheter 1 and dilator 2, the Y axis corresponds to the height direction of catheter 1 and dilator 2, and the Z axis corresponds to the width direction of catheter 1 and dilator 2. The left side of Figure 1 (-X axis direction) is called the "tip side" of catheter 1, dilator 2, and each component, and the right side of Figure 1 (+X axis direction) is called the "proximal end side" of catheter 1, dilator 2, and each component. Furthermore, of the two ends of catheter 1, dilator 2, and each component in the longitudinal direction (X axis direction), the end located on the tip side is called the "tip," and the other end located on the proximal end side is called the "proximal end." Furthermore, the tip and its vicinity are called the "tip," and the proximal end and its vicinity are called the "proximal end." The tip is inserted into the body, while the proximal end is manipulated by a surgeon such as a physician. These points are also common in Figure 1 and subsequent figures.

[0019] The catheter 1 of this embodiment is a guiding catheter for inserting and delivering medical devices such as guidewires and balloon catheters. The catheter 1 has a hollow shaft portion 100 and a first connector 190 provided at the proximal end of the hollow shaft portion 100.

[0020] The hollow shaft portion 100 is a long, tubular member having a tapered tip portion 101 at the tip end and a large-diameter portion 102 at the base end. The tapered tip portion 101 is a part of the hollow shaft portion 100 where both the outer and inner diameters gradually increase from the tip end to the base end. The large-diameter portion 102 is located closer to the base end than the tapered tip portion 101, and is a part of the hollow shaft portion 100 where both the outer and inner diameters are approximately constant in size. In this embodiment, "approximately constant" is synonymous with "generally constant," meaning that it is generally constant while allowing for variations due to manufacturing errors, etc. The outer diameter, inner diameter, and length of the hollow shaft portion 100, the tapered tip portion 101, and the large-diameter portion 102 can be determined arbitrarily.

[0021] The first connector 190 is a component used, for example, by the operator to grasp the catheter 1. The first connector 190 has a housing portion 191, a wing portion 192, and a connecting portion 193, extending from the tip end to the proximal end. The housing portion 191 is a cylindrical component having an outer diameter that gradually increases from the tip end to the proximal end. The proximal end of the large-diameter portion 102 of the hollow shaft portion 100 is housed and fixed inside the housing portion 191. The wing portion 192 is a cylindrical component having a pair of wings for the operator to grasp. The connecting portion 193 is a cylindrical component having a disc-shaped projection at its proximal end that protrudes in the circumferential direction (YZ axis direction). A male thread is formed on the outer circumferential surface of the projection of the connecting portion 193 for screwing into the connecting portion 291 of the second connector 290 of the dilator 2. The housing portion 191, the wing portion 192, and the connecting portion 193 may be integrally molded.

[0022] In catheter 1, the lumen of the hollow shaft portion 100 and the lumen of each component of the first connector 190 are in communication, forming a device lumen 1L. The device lumen 1L is the lumen through which medical devices such as guidewires and balloon catheters are inserted into catheter 1. The device lumen 1L is also the lumen through which a dilator 2 is inserted into catheter 1. At the tip of catheter 1, the opening that connects the device lumen 1L to the outside is also called the "tip opening 1a". At the proximal end of catheter 1, the opening that connects the device lumen 1L to the outside is also called the "proximal opening 1b".

[0023] In catheter 1, the hollow shaft portion 100 and the first connector 190 may be formed from, for example, polyamide, polyester, polyurethane, fluororesin such as polytetrafluoroethylene (PTFE), or other known resin materials. The hollow shaft portion 100 of catheter 1 may be a single-layer structure or a multi-layer structure consisting of two or more layers. In the case of a multi-layer structure, the constituent materials of each layer may be the same or different. Furthermore, metal reinforcing members may be embedded in the hollow shaft portion 100 or between each layer. The reinforcing members can be in the form of a coil shape with wires wound spirally, or a mesh shape with wires woven into a network. The first connector 190 may be formed from, for example, known resin materials such as polyamide, polypropylene, polycarbonate, polyacetal, or polyethersulfone.

[0024] The dilator 2 of this embodiment is a device that assists in the insertion of a catheter into biological tissue by expanding the skin, subcutaneous tissue, and blood vessel walls. The dilator 2 has a main body 200 and a second connector 290 provided at the proximal end of the main body 200.

[0025] The main body portion 200 is a long, tubular member having a tapered portion 201 at the tip and a large-diameter portion 202 at the base. The tapered portion 201 is a portion having an outer diameter that gradually increases from the tip to the base. The large-diameter portion 202 is located closer to the base than the tapered portion 201 and is a portion of the main body portion 200 that has an outer diameter of approximately constant size. The outer diameter Φ202 of the large-diameter portion 202 is smaller than the inner diameter Φ102 of the large-diameter portion 102 of the catheter 1. In this embodiment, the inner diameter of the tapered portion 201 and the inner diameter of the large-diameter portion 202 are approximately constant in size.

[0026] The second connector 290 is a component used, for example, for the operator to grasp the dilator 2. The second connector 290 has a connecting portion 291 and a gripping portion 292, extending from the tip end to the proximal end. The connecting portion 291 is a cylindrical component, and a female thread is formed on the inner circumferential surface of the cylinder for screwing into the connecting portion 193 of the first connector 190 of the catheter 1. The connecting portion 291 is assembled to the gripping portion 292 in a manner that allows it to rotate in the circumferential direction. The gripping portion 292 is a cylindrical component, and a plurality of grooves are formed on the outer circumferential surface of the cylinder. The connecting portion 291 and the gripping portion 292 may be integrally molded.

[0027] In the dilator 2, the lumen of the main body 200 and the lumen of each component of the second connector 290 are in communication, forming a guidewire lumen 2L. The guidewire lumen 2L is a lumen through which a guidewire is inserted into the dilator 2. At the tip of the dilator 2, the opening that connects the guidewire lumen 2L to the outside is also called the "tip opening 2a". At the base of the dilator 2, the opening that connects the guidewire lumen 2L to the outside is also called the "base opening 2b".

[0028] In the dilator 2, the main body 200 and the second connector 290 can be formed from known resin materials such as fluororesin, polyamide, or polyester. Here, it is preferable that the material of the dilator 2 be selected such that the elastic modulus of the catheter 1 is smaller than the elastic modulus of the dilator 2. The elastic moduli of the catheter 1 and the dilator 2 can be determined by adopting the elastic modulus in the linear region from the test results obtained in accordance with the "Method for Measuring Breaking Strength" specified in JIS T 3268. Note that since the assembled dilator kits 1 and 2 are used outside the body, the procedure of immersion in an aqueous solution in the "Method for Measuring Breaking Strength" specified in JIS T 3268 is omitted. Note that the elastic modulus of the hollow shaft 100 may be considered as the "elastic modulus of the catheter 1," and the elastic modulus of the main body 200 may be considered as the "elastic modulus of the catheter 1." If the hollow shaft portion 100 and the main body portion 200 are made of a single material, the catalog value of the material making up the hollow shaft portion 100 may be used as the elastic modulus of the catheter 1, and the catalog value of the material making up the main body portion 200 may be used as the elastic modulus of the dilator 2.

[0029] Figure 2 is an explanatory diagram illustrating the configuration of the dilator kit in its assembled state. The guidewire lumen 2L (inner lumen) of dilator 2 is omitted from Figure 2. Figure 3 is an explanatory diagram illustrating the cross-sectional configuration of the tip side of Figure 2. The longitudinal section shown in Figure 3 includes axis O. Using Figures 2 and 3, the usage of dilator kits 1 and 2, and the differences between the separated and assembled states, will be explained.

[0030] When using dilator kits 1 and 2, the operator inserts the tip of dilator 2 into the device lumen 1L (inner lumen) of catheter 1 through the proximal opening 1b of catheter 1, pushes dilator 2 forward within the device lumen 1L, and causes the tip of dilator 2 to protrude from the tip opening 1a of catheter 1. In this state, the operator rotates the connection part 291 of dilator 2 in the circumferential direction (Figure 2: black arrow) to screw the connection part 193 of catheter 1 and the connection part 291 of dilator 2 together. As this screwing continues, the inner circumferential surface of the tip of the hollow shaft portion 100 of catheter 1 and the outer circumferential surface of the tapered portion 201 of dilator 2 engage, and the proximal end of the hollow shaft portion 100 of catheter 1 is pulled towards the proximal end together with the connector 190, so that the catheter 100 is stretched in the longitudinal direction, and the proximal end engaging portion 12 and the proximal end engaged portion 22 engage. Then, as shown in Figure 2, the dilator 2 is housed in the device lumen 1L (inner lumen) of catheter 1. Hereafter, this state will also be referred to as the "assembled state".

[0031] In the assembled state, as shown in Figures 2 and 3, the inner circumferential surface of the tip of the hollow shaft portion 100 of the catheter 1 and the outer circumferential surface of the tapered portion 201 of the dilator 2 are engaged. Here, the portion of the catheter 1 that engages with the tip of the dilator 2 is called the "tip-side engaging portion 11". In the examples of Figures 2 and 3, the inner circumferential surface of the tip of the hollow shaft portion 100 of the catheter 1 functions as the tip-side engaging portion 11. Similarly, the portion of the dilator 2 that engages with the tip-side engaging portion 11 of the catheter 1 is called the "tip-side engaged portion 21". In the examples of Figures 2 and 3, the outer circumferential surface of the tapered portion 201 of the dilator 2 functions as the tip-side engaged portion 21.

[0032] Furthermore, in the assembled state, as shown in Figure 2, the outer circumferential surface of the first connector 190 (specifically, the connection part 193) of the catheter 1 and the inner circumferential surface of the second connector 290 (specifically, the connection part 291) of the dilator 2 are engaged. Here, the portion where the proximal end of the catheter 1 engages with the proximal end of the dilator 2 is called the "proximal end engagement portion 12". In the example in Figure 2, the outer circumferential surface of the first connector 190 of the catheter 1 functions as the proximal end engagement portion 12. Similarly, the portion where the proximal end of the dilator 2 engages with the proximal end engagement portion 12 of the catheter 1 is called the "proximal end engaged portion 22". In the example in Figure 2, the inner circumferential surface of the second connector 290 of the dilator 2 functions as the proximal end engaged portion 22.

[0033] Here, in the separated state shown in Figure 1, let L0 be the length in the longitudinal direction (X-axis direction) from the tip-side engaging portion 11 to the proximal-side engaging portion 12 of the catheter 1. Also, in the separated state shown in Figure 1, let La be the length in the longitudinal direction (X-axis direction) from the tip-side engaged portion 21 to the proximal-side engaged portion 22 of the dilator 2. In this case, the length La between the tip-side engaged portion 21 and the proximal-side engaged portion 22 is longer than the length L0 between the tip-side engaged portion 11 and the proximal-side engaged portion 12 (separated state shown in Figure 1: La > L0).

[0034] Therefore, in the assembled state shown in Figure 2, the hollow shaft portion 100 of the catheter 1 is mainly extended in the longitudinal direction indicated by the white arrow. In the assembled state, the length in the longitudinal direction (X-axis direction) from the tip-side engaging portion 11 to the proximal-side engaging portion 12 of the catheter 1 is defined as L1. At this time, the difference (L1-L0) between the length L1 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 in the assembled state and the length L0 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 in the separated state is within the range of 1 mm or more and 30 mm or less. Furthermore, it is more preferable that the difference (L1-L0) between the length L1 in the assembled state and the length L0 in the separated state is within the range of 5 mm or more and 15 mm or less. In the example in Figure 2, the difference (L1-L0) between the length L1 in the assembled state and the length L0 in the separated state is approximately 10 mm. Note that the length L1 in the assembled state corresponds to the "first length," and the length L0 in the separated state corresponds to the "second length."

[0035] Furthermore, as shown in Figure 3, in the longitudinal section of the hollow shaft portion 100 of the catheter 1, the acute angle formed by the outer circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 is defined as the first acute angle θ1. Also, in the same longitudinal section, the acute angle formed by the inner circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 is defined as the second acute angle θ2. In this case, the first acute angle θ1 is larger than the second acute angle θ2 (Figure 3: θ1 > θ2). By establishing this relative size relationship between the first acute angle θ1 and the second acute angle θ2, the wall thickness of the tip tapered portion 101 can be gradually reduced from the base end towards the tip end. In other words, the wall thickness T1 at the tip of the tip tapered portion 101 can be made thinner than the wall thickness T2 at the base end of the tip tapered portion 101.

[0036] Figure 4 shows the insertion of the dilator kit of this embodiment into biological tissue. The dilator kit is pushed forward along a guidewire (not shown) with its tip portion pre-inserted into the biological tissue, and is inserted into the biological tissue. According to the first embodiment described above, in the separated state in which the catheter 1 and the dilator 2 are separated, the length La between the tip-side engaged portion 21 and the proximal-side engaged portion 22 of the dilator 2 is longer than the length L0 between the proximal-side engaged portion 12 and the proximal-side engaged portion 12 of the catheter 1 (separated state shown in Figure 1: La > L0). Therefore, as shown in Figures 2 and 4, in the assembled state in which the dilator 2 is housed in the device lumen 1L of the catheter 1, the tip-side engaged portion 11 and the tip-side engaged portion 21 engage, and the proximal-side engaged portion 12 and the proximal-side engaged portion 22 engage, with the catheter 1 extended in the longitudinal direction. Thus, in the dilator kits 1 and 2 of this embodiment, the catheter 1 is already extended in the assembled state. Therefore, as shown in Figure 4, when the tip of the dilator 2 is pressed against the skin 301 and a pushing force is applied from the hand 302 in order to insert the catheter 1 into biological tissue, the extension of the catheter 1 in the pushing direction (longitudinal direction, in the direction of the black arrow in Figure 4) can be suppressed. Furthermore, in the assembled state shown in Figures 2 and 4, the tip-side engaging portion 11 and the tip-side engaged portion 21 are engaged, and the proximal-side engaging portion 12 and the proximal-side engaged portion 22 are engaged, so the occurrence of the dilator 2 retracting towards the proximal side within the catheter 1 when subjected to resistance from the skin 301 can be suppressed. As a result, the dilator kits 1 and 2 of the first embodiment allow for easy insertion of the catheter 1 into biological tissue.

[0037] Furthermore, according to the first embodiment described above, the difference between the first length L1 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 of the catheter 1 in the assembled state and the second length L0 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 of the catheter 1 in the separated state (first length L1 - second length L0) is within the range of 1 mm or more and 30 mm or less. Therefore, the elongation of the catheter 1 in the pushing direction when subjected to pushing force from the hand 302 can be suppressed, and excessive elongation of the catheter 1 when changing from the separated state to the assembled state can be suppressed. Moreover, if the difference between the first length L1 and the second length L0 (first length L1 - second length L0) is within the range of 5 mm or more and 15 mm or less, the elongation of the catheter 1 in the pushing direction when subjected to pushing force from the hand 302 can be further suppressed, and excessive elongation of the catheter 1 when changing from the separated state to the assembled state can be further suppressed.

[0038] Furthermore, according to the first embodiment described above, since the elastic modulus of the catheter 1 is smaller than that of the dilator 2, the delivery of the catheter 1 within the biological lumen can be improved, and the insertion of the dilator 2 into the skin 301 (specifically, insertion into the skin hole in which the guidewire is inserted) and the dilation of the skin 301 by the dilator (specifically, dilation of the skin hole in which the guidewire is inserted) can be facilitated.

[0039] Furthermore, according to the first embodiment described above, the inner circumferential surface of the tip of the hollow shaft portion 100 of the catheter 1 and the outer circumferential surface of the tapered portion 201 of the dilator 2 engage with each other, so that the inner circumferential surface of the tip of the hollow shaft portion 100 functions as a tip-side engaging portion 11, and the outer circumferential surface of the tapered portion 201 functions as a tip-side engaged portion 21. Therefore, by utilizing the lumen (device lumen 1L) that is generally provided in the catheter 1 and the tip-side tapered structure that is generally provided in the dilator 2, an engagement structure between the tip-side engaging portion 11 and the tip-side engaged portion 21 can be realized. Furthermore, according to the first embodiment described above, the outer circumferential surface of the first connector 190 of the catheter 1 and the inner circumferential surface of the second connector 290 of the dilator 2 engage with each other, so that the outer circumferential surface of the first connector 190 functions as a proximal end engaging portion 12, and the inner circumferential surface of the second connector 290 functions as a proximal end engaged portion 22. Therefore, by utilizing connectors 190 and 290, which are commonly provided in catheter 1 and dilator 2, an engagement structure between the proximal engagement portion 12 and the proximal engagement portion 22 can be realized.

[0040] Furthermore, according to the first embodiment described above, in the longitudinal cross-section of the hollow shaft portion 100 of the catheter 1, the first acute angle θ1 formed by the outer circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 is greater than the second acute angle θ2 formed by the inner circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 (Figure 3: θ1 > θ2). Therefore, the wall thickness of the tip tapered portion 101 of the catheter 1 can be gradually reduced from the proximal end to the tip end. As a result, the tip end of the tip tapered portion 101 can be configured more flexibly compared to the proximal end, and the step difference ST (Figure 3) between the tip of the catheter 1 and the dilator 2 in the assembled state can be reduced.

[0041] Figures 5 and 6 show the insertion of the comparative example dilator kit into biological tissue. The upper section of Figure 5 shows the changes in the state of the comparative example dilator kit as it is pushed in. The comparative example dilator kit comprises a catheter 1x and a dilator 2x. Catheter 1x is a conventional guiding catheter that does not have a tip tapered portion 101, a tip-side engaging portion 11, and a proximal-side engaging portion 12. Dilator 2x is a conventional dilator that does not have a tip-side engaging portion 21 and a proximal-side engaging portion 22. In the example in Figure 5, dilator 2x has a narrow diameter portion, a wide diameter portion, a wide diameter portion, and a narrow diameter portion from the tip to the proximal end.

[0042] In the comparative example dilator kit, when the dilator 2x is housed within the lumen of catheter 1x, the tip of catheter 1x is simply positioned along the outer surface of the larger diameter portion LD of dilator 2x, as shown by the solid line in the upper section of Figure 5. In this state, when the tip of dilator 2x is pressed against the skin 301 and pushing force is applied from the hand 302 to insert catheter 1x into biological tissue, the catheter 1x will either extend in the pushing direction (longitudinal direction, in the direction of the black arrow in Figure 5), or the dilator 2x, receiving resistance from the skin 301, will retract towards the proximal side within catheter 1x (in other words, the dilator 2x will move in the opposite direction to the black arrow in Figure 5). As a result, the positional relationship between catheter 1x and dilator 2x will be as shown by the dashed line in Figure 5, and catheter 1x will not be inserted into the skin 301 by the same length as the length pushed in by the operator. Furthermore, the change in positional relationship due to the pushing motion increases the step difference ST (upper panel of Figure 5) between the tip of catheter 1x and dilator 2x. As a result, insertion of catheter 1x into biological tissue was difficult with the comparative example dilator kit.

[0043] Furthermore, let's consider the case where the insertion length of catheter 1x into biological tissue is longer than shown in Figure 5. In such a case, as shown in Figure 6, the more proximal end of catheter 1x is grasped with the hand 302. However, as shown in Figure 6, when the proximal end of catheter 1x is grasped with the hand 302, the flexible catheter 1x and dilator 2x bend, and the force is not transmitted. Therefore, when applying pushing force to catheter 1x and dilator 2x, it is necessary to grasp the vicinity of the tip of catheter 1x, as shown in Figure 5, and it can be seen that there is a limit to the insertion length that can be added in a single stroke.

[0044] <Second Embodiment> Figure 7 is an explanatory diagram illustrating the configuration of the dilator kit of the second embodiment. Similar to Figure 3, Figure 7 shows a longitudinal cross-section of the tip side of the dilator kit in its assembled state, including axis O. The upper part of Figure 7 shows an enlarged view of a portion enclosed by a dashed circle. The dilator kits 1 and 2A of the second embodiment are equipped with dilator 2A in place of dilator 2 in the configuration described in the first embodiment.

[0045] The main body portion 200A of the dilator 2A has a tip-side engaging portion 21A instead of the tip-side engaging portion 21, a tapered portion 201A instead of the tapered portion 201, and a large-diameter portion 202A instead of the large-diameter portion 202. At the tip of the large-diameter portion 202A, a step is formed in which the wall thickness is raised so that the outer diameter differs at the front and rear. In the assembled state, the dilator kits 1 and 2A of the second embodiment engage with the inner circumferential surface of the tip of the hollow shaft portion 100 of the catheter 1 and the step formed on the outer circumferential surface of the large-diameter portion 202A of the dilator 2A (in the upper blowout of Figure 7). That is, in the dilator 2A, the step formed on the outer circumferential surface of the large-diameter portion 202A functions as the tip-side engaging portion 21A.

[0046] Thus, the configuration of the tip-side engaging portion 21A can be modified in various ways, and it does not have to be formed on the outer circumferential surface of the tapered portion 201A. Furthermore, the tip-side engaging portion 21A may have a configuration different from that described in Figure 7, and for example, it may be formed by winding a wire around the outer circumferential surface of the large-diameter portion 202A. The dilator kits 1 and 2A of the second embodiment described above can also achieve the same effects as the first embodiment described above. In addition, a step that engages with the step of the tip-side engaging portion 21A can be provided on the inner circumferential surface of the tip of the shaft 100 of the catheter 1.

[0047] <Third Embodiment> Figure 8 is an explanatory diagram illustrating the configuration of the dilator kit of the third embodiment. Similar to Figure 3, Figure 8 shows a longitudinal cross-section of the tip side of the dilator kit in its assembled state, including axis O. The dilator kits 1B and 2B of the third embodiment are configured in the same way as the first embodiment, but with catheter 1B instead of catheter 1 and dilator 2B instead of dilator 2.

[0048] The hollow shaft portion 100B of catheter 1B has a tip-side engaging portion 11B instead of the tip-side engaging portion 11, does not have the tip tapered portion 101 described in the first embodiment, and has a large diameter portion 102B instead of the large diameter portion 102. The tip of the large diameter portion 102B has a convex portion formed on its inner circumferential surface that rises inward. The main body portion 200B of dilator 2B has a tip-side engaging portion 21B instead of the tip-side engaging portion 21, a tapered portion 201B instead of the tapered portion 201, and a large diameter portion 202B instead of the large diameter portion 202. The tip of the large diameter portion 202B has a recess formed in the wall thickness portion so that its outer diameter is smaller than that of the other parts. In the third embodiment, the dilator kits 1B and 2B, when assembled, have a convex portion formed on the inner circumferential surface of the hollow shaft portion 100B of catheter 1B and a concave portion formed on the outer circumferential surface of the main body portion 200B of dilator 2B that engages with each other. Specifically, in catheter 1B, the convex portion formed on the inner circumferential surface of the large diameter portion 102B functions as the tip-side engaging portion 11B, and in dilator 2B, the concave portion formed on the outer circumferential surface of the large diameter portion 202B functions as the tip-side engaged portion 21B.

[0049] Thus, the configuration of the tip-side engaging portion 11B and the tip-side engaged portion 21B can be modified in various ways and may be realized by a grooved engagement structure. In the example of Figure 8, a protrusion is formed on the catheter 1B side and a recess is formed on the dilator 2B side, but these may be reversed. Also, although the catheter 1B is configured without a tip tapered portion 101, it may also be configured to have a tip tapered portion 101 and a tip-side engaging portion 11B realized by a grooved engagement structure on the inner circumferential surface of the tip tapered portion 101. The dilator kits 1B and 2B of the third embodiment described above can also achieve the same effects as the first embodiment described above.

[0050] <Fourth Embodiment> Figure 9 is an explanatory diagram illustrating the configuration of the dilator kit of the fourth embodiment. Similar to Figure 3, Figure 9 shows a longitudinal cross-section of the tip side of the dilator kit in the assembled state, including axis O. The dilator kits 1 and 2C of the third embodiment are equipped with dilator 2C in place of dilator 2 in the configuration described in the first embodiment.

[0051] In the dilator 2C, a friction force-applying means 23 is provided on the outer circumferential surface of the tapered portion 201 of the main body portion 200, in the portion that functions as the tip-side engaged portion 21. The friction force-applying means 23 is a member or part that generates frictional force with the tip-side engaged portion 11 (i.e., the inner circumferential surface of the tip of the hollow shaft portion 100). As the friction force-applying means 23, for example, a ring member made of silicone or rubber can be used. Alternatively, the friction force-applying means 23 may be a textured surface provided on the outer circumferential surface of the tapered portion 201. The textured surface can be achieved, for example, by processing the outer circumferential surface of the tapered portion 201 by laser processing or the like.

[0052] Thus, the configuration of the dilator 2C can be modified in various ways, and it may have other configurations, such as the friction force applying means 23 described in Figure 9. The friction force applying means 23 may be provided on the tip-side engaging portion 11 side (i.e., the inner circumferential surface side of the catheter 1) rather than on the tip-side engaging portion 21 side (i.e., the outer circumferential surface side of the dilator 2C). The dilator kit 1,2C of the fourth embodiment described above can also achieve the same effects as the first embodiment described above. Furthermore, with the dilator kit 1,2C of the fourth embodiment, the change in the relative position between the catheter 1 and the dilator 2C when subjected to pushing force from the hand in the assembled state can be further suppressed, so that the catheter 1 can be inserted into biological tissue even more easily.

[0053] <Fifth Embodiment> Figure 10 is an explanatory diagram illustrating the configuration of the dilator kit of the fifth embodiment. Figure 10 shows a longitudinal cross-section of the proximal end of the dilator kit in its assembled state, including axis O. The dilator kits 1D and 2D of the fifth embodiment are configured in the same way as the first embodiment, but with catheter 1D instead of catheter 1 and dilator 2D instead of dilator 2.

[0054] The first connector 190D of catheter 1D has a proximal engagement portion 12D in place of the proximal engagement portion 12, and a connecting portion 193D in place of the connecting portion 193. The connecting portion 193D is a cylindrical member, and a cylindrical projection t protruding from the outer surface of the proximal end of the cylinder is provided. The second connector 290D of dilator 2D has a proximal engagement portion 22D in place of the proximal engagement portion 22, and a connecting portion 291D in place of the connecting portion 291. The connecting portion 291D is a cylindrical member, and an L-shaped groove m is formed on the inner surface of the cylinder.

[0055] To assemble the dilator kits 1D and 2D of the fifth embodiment, the following procedure is performed. First, the operator inserts the projection t of the first connector 190D of the catheter 1D into the groove m of the second connector 290D of the dilator 2D, and pushes the projection t along the groove m toward the proximal end. Then, the operator rotates the second connector 290D together with the connecting part 291D fixed to it at the abutment of the groove m, thereby fitting the projection t into the back of the L-shaped groove m. In this way, in the assembled state, the groove m formed on the inner circumferential surface of the second connector 290D of the dilator 2D and the projection t formed on the outer circumferential surface of the first connector 190D of the catheter 1D are engaged. In other words, in catheter 1D, the projection t formed on the outer circumferential surface of the connection portion 193D functions as the proximal end engagement portion 12D, and in dilator 2D, the groove m formed on the inner circumferential surface of the connection portion 291D functions as the proximal end engagement portion 22D.

[0056] Thus, the configuration of the proximal engagement portion 12D and the proximal engaged portion 22D can be modified in various ways, and may be implemented in a configuration different from the so-called Luer lock structure described in the first embodiment. In the example of Figure 10, a groove m is formed on the dilator 2D side and a projection t is formed on the catheter 1D side, but these may be reversed. Also, a notch formed in a cylindrical member can be used instead of the groove m. The dilator kit 1D, 2D of the fifth embodiment described above can also achieve the same effects as the first embodiment described above.

[0057] <Sixth Embodiment> Figure 11 is an explanatory diagram illustrating the configuration of the dilator kit of the sixth embodiment. Similar to Figure 3, Figure 11 shows a longitudinal cross-section of the tip side of the dilator kit in its assembled state, including axis O. The dilator kits 1E and 2 of the sixth embodiment are equipped with catheter 1E in place of catheter 1, in the configuration described in the first embodiment.

[0058] Catheter 1E has a hollow shaft portion 100E instead of the hollow shaft portion 100. In the longitudinal section shown in Figure 11, the first acute angle θ1 is equal to the acute angle formed by the outer circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102, and the second acute angle θ2 is equal to the acute angle formed by the inner circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 (Figure 11: θ1=θ2). Therefore, the wall thickness of the tip tapered portion 101 of catheter 1E is generally uniform from the proximal end to the tip. In other words, the wall thickness T1 at the tip of the tip tapered portion 101 and the wall thickness T2 at the proximal end of the tip tapered portion 101 are generally equal. Thus, the configuration of catheter 1E can be modified in various ways, and the wall thickness of the tip tapered portion 101 may be made generally uniform. The dilator kits 1E and 2 of the sixth embodiment described above can also achieve the same effects as those of the first embodiment described above.

[0059] <Seventh Embodiment> Figure 12 is an explanatory diagram illustrating the configuration of the dilator kit of the seventh embodiment. Similar to Figure 3, Figure 12 shows a longitudinal cross-section of the tip side of the dilator kit in its assembled state, including axis O. The dilator kits 1F and 2 of the seventh embodiment are equipped with catheter 1F in place of catheter 1, in the configuration described in the first embodiment.

[0060] Catheter 1F has a hollow shaft portion 100F instead of the hollow shaft portion 100. In the longitudinal section shown in Figure 12, the first acute angle θ1 formed by the outer circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 is smaller than the second acute angle θ2 formed by the inner circumferential surface of the tip tapered portion 101 and the outer circumferential surface of the large diameter portion 102 (Figure 12: θ1 < θ2). Therefore, the wall thickness of the tip tapered portion 101 of catheter 1F gradually increases from the proximal end to the tip. In other words, the wall thickness T1 at the tip of the tip tapered portion 101 can be made thicker than the wall thickness T2 at the proximal end of the tip tapered portion 101. Thus, the configuration of catheter 1E can be modified in various ways, and the wall thickness of the tip tapered portion 101 may be gradually increased from the proximal end to the tip. The dilator kits 1F and 2 of the seventh embodiment described above can also achieve the same effects as those of the first embodiment described above.

[0061] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0062] [Example 1] The first to seventh embodiments described above show an example of the configuration of a dilator kit. However, the configuration of the dilator kit can be modified in various ways. For example, the difference (L1-L0) between the length L1 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 in the assembled state and the length L0 between the tip-side engaging portion 11 and the proximal-side engaging portion 12 in the separated state may be less than 1 mm or greater than 30 mm. For example, the elastic modulus of the catheter may be greater than the elastic modulus of the dilator. For example, the elastic modulus of the catheter and the elastic modulus of the dilator may be the same.

[0063] [Differentiation 2] The first to seventh embodiments described above show examples of the configurations of catheters 1, 1B, 1D, 1E, and 1F. However, the configuration of catheter 1 can be modified in various ways. For example, the tapered tip portion 101 may be omitted. For example, the tip of the hollow shaft portion 100 may be provided with a radiopaque marker portion. For example, catheter 1 may be configured as a catheter other than a guiding catheter. In this case, catheter 1 may be configured as a multi-lumen catheter having multiple lumens. For example, the tip and proximal ends of the hollow shaft portion 100 may be made of different materials and have different elastic moduli. In this case, it is preferable that at least the tip end of the hollow shaft portion 100 has an elastic modulus smaller than that of the dilator 2.

[0064] [Difference 3] The first to seventh embodiments described above show examples of the configurations of dilators 22A, 2B, 2C, and 2D. However, the configuration of the dilator 2 can be modified in various ways. For example, a smaller diameter portion may be provided on the tip side of the tapered portion 201, and an enlarged diameter portion or a second larger diameter portion than the larger diameter portion 202 may be provided on the proximal end side of the larger diameter portion 202. For example, the tip and proximal ends of the main body portion 200 may be made of different materials and have different elastic moduli. In this case, it is preferable that at least the tip side of the main body portion 200 has an elastic modulus greater than that of the catheter 1.

[0065] [Differentiation Example 4] The configurations of catheters 1, 1B, 1D, 1E, 1F and dilators 22A, 2B, 2C, 2D in the first to seventh embodiments, and the configurations of catheters 1, 1B, 1D, 1E, 1F and dilators 22A, 2B, 2C, 2D in the modified examples 1 to 3, may be combined as appropriate. For example, the tip configuration described in any of the second, third, fourth, sixth, and seventh embodiments may be combined with the proximal configuration described in the fifth embodiment. For example, the catheters of the second to fifth embodiments may have a configuration having a first acute angle θ1 and a second acute angle θ2 as described in either the sixth or seventh embodiment.

[0066] The catheters of the first to seventh embodiments are dilator kits comprising a catheter having a lumen and a dilator, wherein in the assembled state the dilator is housed in the lumen of the catheter, and the catheter in the assembled state is supported by the dilator in an extended state (for example, within a range of 1 mm or more and 30 mm or less, preferably within a range of 5 mm or more and 15 mm or less) relative to the separated state in which the catheter and the dilator are separated. Therefore, when the catheter is subjected to pushing force from the hand during insertion into biological tissue, the extension of the catheter in the pushing direction (longitudinal direction) can be suppressed. As a result, the catheter of the assembled dilator kit can be easily inserted into biological tissue.

[0067] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate. [Explanation of Symbols]

[0068] 1, 1B, 1D, 1E, 1F… Catheter 1x…Catheter (Example) 22A,2B,2C,2D…Dilator 2x…Dilator (Example Example) 11,11B...Tip side engaging part 12,12D…Proximal side engaging part 21,21A,21B...Tip side engaged part 22,22D…Proximal side engaged part 23...Means for imparting friction 100, 100B, 100E, 100F... Hollow shaft section 101... Tapered tip 102,102B…Large diameter part 190, 190D…First connector 191... Detention Unit 192...Wing section 193, 193D… Connection part 200, 200A, 200B... Main unit 201, 201A, 201B... Tapered section 202202A,202B…Large diameter part 290, 290D…Second connector 291, 291D… Connection part 292...Gripping part

Claims

1. A dilator kit comprising a catheter having a lumen and a dilator, wherein in the assembled state the dilator is housed in the lumen of the catheter, In the assembled state, the catheter The dilator has a tip-side engaging portion and a base-side engaging portion that engage with each other, The dilator, in the assembled state, The tip-side engaged portion engages with the tip-side engaging portion of the catheter, The catheter has a proximal end engaging portion that engages with the proximal end engaging portion, In the separated state where the catheter and the dilator are separated, the length between the tip-side engaging portion and the proximal-side engaging portion of the dilator is longer than the length between the tip-side engaging portion and the proximal-side engaging portion of the catheter. The catheter has a hollow shaft portion, The dilator has an elongated main body, The main body of the dilator is provided with a tapered portion whose outer diameter gradually increases from the tip to the base end, and a larger diameter portion located closer to the base end than the tapered portion, which has a step in which the outer diameter differs between the front and rear. In the assembled state, the inner circumferential surface of the tip of the hollow shaft portion and the step engage with each other, so that the inner circumferential surface of the tip of the hollow shaft portion functions as the tip-side engaging portion, and the step functions as the tip-side engaged portion. A dilator kit that exposes the tip of the dilator through the tip-side opening of the catheter.

2. A dilator kit comprising a catheter having a lumen and a dilator, wherein the dilator is housed in the lumen of the catheter in an assembled state, In the assembled state, the catheter The dilator has a tip-side engaging portion and a base-side engaging portion that engage with each other, The dilator, in the assembled state, The tip-side engaged portion engages with the tip-side engaging portion of the catheter, The catheter has a proximal end engaging portion that engages with the proximal end engaging portion, In the separated state where the catheter and the dilator are separated, the length between the tip-side engaging portion and the proximal-side engaging portion of the dilator is longer than the length between the tip-side engaging portion and the proximal-side engaging portion of the catheter. The catheter has a hollow shaft portion, The dilator has an elongated main body, The main body of the dilator is provided with a tapered portion whose outer diameter gradually increases from the tip end to the base end. The inner circumferential surface of the hollow shaft portion and the outer circumferential surface of the main body portion are provided with a protrusion on one side and a recess that engages with the protrusion on the other side. In the assembled state, the inner circumferential surface of the hollow shaft portion and the outer circumferential surface of the main body portion engage with each other, so that the inner circumferential surface of the hollow shaft portion functions as the tip-side engaging portion, and the outer circumferential surface of the main body portion functions as the tip-side engaged portion. A dilator kit that exposes the tip of the dilator through the tip-side opening of the catheter.

3. A dilator kit according to claim 1 or claim 2, The length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the assembled state is defined as the first length. When the length between the tip-side engaging portion and the proximal-side engaging portion of the catheter in the separated state is defined as the second length, A dilator kit in which the difference between the first length and the second length is within the range of 5 mm or more and 15 mm or less.

4. A dilator kit according to any one of claims 1 to 3, A dilator kit wherein the elastic modulus of the catheter is smaller than the elastic modulus of the dilator.

5. A dilator kit according to any one of claims 1 to 4, The catheter further has a first connector provided at the proximal end of the hollow shaft portion, The dilator further has a second connector provided at the base end of the main body, In the assembled state, the outer circumferential surface of the first connector and the inner circumferential surface of the second connector engage with each other, so that the outer circumferential surface of the first connector functions as the base end engaging portion and the inner circumferential surface of the second connector functions as the base end engaged portion, in a dilator kit.

6. A dilator kit according to any one of claims 1 to 5, The hollow shaft portion of the catheter has, Both the outer and inner diameters are gradually widened from the tip to the base, forming a tapered tip section. A larger diameter portion having a substantially constant outer diameter is provided, which is located closer to the base end than the aforementioned tapered tip portion. In the longitudinal section of the hollow shaft portion, The acute angle formed by the outer circumferential surface of the tapered tip portion and the outer circumferential surface of the large diameter portion is defined as the first acute angle. When the acute angle formed by the inner circumferential surface of the tapered tip portion and the outer circumferential surface of the large diameter portion is defined as the second acute angle, A dilator kit in which the first acute angle is larger than the second acute angle.

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