JP6724490B2 - Stent delivery system - Google Patents

Description

The present invention relates to a stent delivery system for delivering a stent to be placed in a body to an indwelling position.

For the purpose of treating bile ducts and other luminal organs of the digestive system, various types of stents are inserted and placed in the body. Stents include self-expanding type and balloon-expanding type depending on the type of expansion, and there are covered stents and bare stents depending on the presence/absence of resin coating, which are used properly according to the application. Regarding the shape of the stent, not only a simple cylindrical shape but also various shapes are used. For example, when performing endoscopically guided biliary drainage (EUS-BD), etc., a luminal organ (eg, digestive tract such as stomach or duodenum) and other luminal organs (eg, bile duct or gallbladder) 2) is used for bypass connection, a stent having a flexible portion such as a hook at its end has been proposed in order to prevent migration and perforation into a body lumen (see Patent Document 1).

On the other hand, a self-expanding stent is mounted on the distal end of the stent delivery system, delivered to the indwelling position, and then released from the stent delivery system. As the structure of the stent delivery system, for example, the outer sheath is relatively moved to the proximal end side to expose the distal end of the inner shaft to release the stent mounted between the inner shaft and the outer sheath. Are listed.

JP, 2005-66221, A

When releasing the stent from the stent delivery system, the stent must remain in place on the inner shaft against the axial force generated by the frictional force with the outer sheath. However, in the case of a stent having a flexible portion at the end, the flexible portion is crushed during the discharging operation, or the flexible portion is caught between the outer sheath and the inner shaft, so that the stent can be properly positioned at the intended position. There may be a problem that it cannot be discharged in a different shape.

The present invention has been made in view of such circumstances, and an object thereof is to provide a stent delivery system capable of appropriately releasing a stent having a flexible portion at its end.

In order to achieve the above object, the stent delivery system according to the present invention,
An inner shaft having a first portion having a first outer diameter and a second portion connected to a distal end of the first portion and having a second outer diameter smaller than the first outer diameter. ,
With respect to the inner shaft, from the first state, which is inserted through the first portion and the second portion, and covers the second portion, to the second state in which the second portion is exposed from the distal end. An outer sheath that is relatively movable in the axial direction,
A cylindrical portion housed between the second portion and the outer sheath, and a flexible portion connected to the proximal end of the cylindrical portion and more easily deformed than the cylindrical portion due to a force from the axial direction. And a stent having,
The first portion extends in the axial direction and is opened at a step surface of the first portion formed at a connection position with the second portion and an outer peripheral surface of the first portion, and the flexible portion is formed. It is characterized in that a groove portion for accommodating the portion is formed.

In the stent delivery system according to the present invention, since the groove for accommodating the flexible portion of the stent is formed in the first portion of the inner shaft, even if the stent is subjected to frictional force from the outer sheath at the time of discharge, the flexible stent The part is prevented from undergoing deformation forces. The shape of the groove extending in the axial direction and opening on the step surface and the outer peripheral surface can preferably prevent the problem that the accommodated flexible portion is sandwiched between the outer sheath and the inner shaft.

Also, for example, the first portion of the inner shaft has a metal ring located at a distal end of the first portion,
At least a part of the groove may be formed in the metal ring.

By disposing the metal ring at the distal end of the first portion, the cylindrical portion of the stent comes into contact with the step surface of the metal ring, which is a relatively hard material, during the stent discharging operation, so that the metal ring can be more reliably and It is possible to stably stay in the second portion . Further, the problem that the flexible portion housed in the groove of the metal ring undergoes unexpected deformation due to the frictional force of the outer sheath can be more reliably prevented.

Further, for example, the inner shaft has a resin outer tube having the first outer diameter and the second outer diameter, and is inserted through the outer tube to form a distal end of the outer tube. And an inner tube which is exposed from and constitutes the second portion,
At least a part of the groove may be formed in the outer tube.

The inner shaft, which has a double-tube structure including an inner tube and an outer tube, is easy to manufacture because it is easy to form a stepped surface and a groove by processing the distal end of the outer tube. Further, by forming the groove portion in the outer tube made of a relatively flexible material, even if the flexible portion is long in the axial direction, it is possible to lengthen the groove portion accordingly.

Further, for example, a plurality of the groove portions may be formed in the circumferential direction of the first portion.

By forming a plurality of grooves, even if the flexible portion is provided separately in the circumferential direction of the cylindrical portion, the groove portion can properly accommodate the flexible portion.

One end of the flexible portion is connected to the proximal end of the cylindrical portion, and the other end of the flexible portion is a linear member that is elastically deformable so as to be curved outward from the one end. You may have.

In the conventional stent delivery system, the flexible portion having the linear member has a problem that it is easily crushed at the time of discharge, but by avoiding such a problem by being accommodated in the groove portion opening to the step surface and the outer peripheral surface. it can. Further, in such a delivery system, the step surface comes into contact with the cylindrical portion of the stent, and the cylindrical portion is reliably retained in the second portion of the inner shaft, thereby realizing proper release of the stent.

FIG. 1 is an external view of a stent delivery system according to the present invention. FIG. 2 is an external view showing an example of a stent included in the stent delivery system of FIG. FIG. 3 is a partially enlarged view of the stent delivery system shown in FIG. 1, showing a stent housed in the stent delivery system and its peripheral portion. FIG. 4 shows a portion of the stent delivery system that accommodates the stent, with the stent hidden. FIG. 5 is a cross-sectional view of the stent delivery system shown in FIG. FIG. 6 is an external view of a metal ring included in the stent delivery system shown in FIG. FIG. 7 is a partially enlarged view showing the vicinity of the distal end of the outer tube in the inner shaft included in the stent delivery system shown in FIG.

The stent delivery system of the present invention will be described with reference to the embodiments shown in FIGS.

1 is an external view of a stent delivery system 10 according to an embodiment of the present invention, FIG. 1A shows the stent delivery system 10 in a first state in which a stent 20 is accommodated, and FIG. 2 illustrates the distal end portion of the stent delivery system 10 in a second state that releases In the description of the stent delivery system 10, the direction in which the stent delivery system 10 extends from the proximal end where the operation unit 30 is arranged to the distal end where the distal end tip 80 is arranged is an axial direction. To do.

As shown in FIG. 1, the stent delivery system 10 includes a stent 20, an operating portion 30, an outermost tube 40, an outer sheath 50, an inner shaft 60, a distal tip 80, and the like. The total length of the stent delivery system 10 is, for example, about 300 to 2500 mm, although it varies depending on the placement position of the stent 20, the delivery route, and the like.

As shown in FIG. 1A, the stent 20 is housed near the distal end of the stent delivery system 10. The operator of the stent delivery system 10 brings the stent 20 to the indwelling position in the body in the first state shown in FIG. 1A, and then puts the stent delivery system 10 into the second state shown in FIG. 1B. Thus, the stent 20 is released and placed at the placement position.

The inner shaft 60 extends in the axial direction from an operating portion 30 provided at the proximal end of the stent delivery system 10 to a tip tip 80 provided at the distal end of the stent delivery system 10. In the first state shown in FIG. 1A, the inner shaft 60 is housed inside the outer sheath 50 and the housing of the operation unit 30.

As shown in FIG. 1B, the inner shaft 60 includes a first portion 60a having a first outer diameter and a second portion having a second outer diameter smaller than the outer diameter of the first portion 60a. 60b. In the second state in which the outer sheath 50 has moved to the proximal end side, the second portion 60b at the distal end is exposed.

FIG. 5 is a cross-sectional view of the stent delivery system 10. As shown in FIG. 5, the inner shaft 60 includes a resin outer tube 64 having a first outer diameter and a resin inner tube 62 having a second outer diameter. Has a double tube structure in which the inner tube 62 is inserted. As shown in FIG. 1B and a partially enlarged view of FIG. 4, the distal end of the inner tube 62 is exposed from the distal end of the outer tube 64 to form the second portion 60 b of the inner shaft 60. doing.

As shown in FIG. 5, a guide wire lumen 62a through which a guide wire is inserted is formed inside the inner tube 62. As shown in FIG. 1B, a distal tip 80 is provided on the distal end of the inner shaft 60, and the distal tip 80 has a through hole communicating with the guide wire lumen 62a. The tip 80 is made of resin or the like and has a rounded outer shape so that it can be prevented from being damaged when it comes into contact with the wall of the body lumen.

As shown in FIGS. 1(b) and 4, the first portion 60a of the inner shaft 60 has a metal ring 66 located at the distal end of the first portion 60a. In the embodiment, the outer diameter of the metal ring 66 is the same as the outer diameter of the outer tube 64, but the outer diameter of the metal ring 66 is larger than the second outer diameter of the inner tube 62. There is no particular limitation. The detailed structure of the inner shaft 60 will be described later.

The inner tube 62 and the outer tube 64 have flexibility, and as a material thereof, a thermoplastic resin having a certain degree of rigidity and slidability is preferably used. In this embodiment, the inner tube 62 is made of a highly rigid thermoplastic resin, and the outer tube 64 is made of a thermoplastic resin having excellent slidability. The surface of the outer tube 64 may be coated to improve the slidability with the outer sheath 50 and the rigidity of the inner shaft 60. The outer diameter of the outer tube 64 is about 0.5 to 3.0 mm, but is not particularly limited. The overall length of the inner shaft 60 is substantially the same as the overall length of the stent delivery system 10.

As shown in FIGS. 1A and 4, in the first state, the outer sheath 50 passes through the first portion 60a and the second portion 60b of the inner shaft 60. As shown in FIG. 5 which is a cross-sectional view, a lumen having a diameter substantially equal to or larger than the first outer diameter of the outer tube 64 is formed inside the outer sheath 50, The inner tube 62 and the outer tube 64 of the inner shaft 60 are inserted through the lumen of the outer sheath 50. Further, as shown in FIG. 4, in the second portion 60b of the inner shaft 60 where the outer pipe 64 does not exist, a gap is formed between the outer peripheral surface of the inner pipe 62 and the inner wall of the outer sheath 50, and the gap is formed in the gap. The cylindrical portion 22 (see FIG. 2) of the stent 20 is housed.

The outer sheath 50 is axially movable relative to the inner shaft 60 from the first state shown in FIG. 1A to the second state shown in FIG. 1B. The proximal end of the outer sheath 50 is housed inside the housing 31 of the operation unit 30, and the operation unit 30 operates the operation lever 33 attached to the housing 31 to operate the outer sheath 50 as an inner shaft. 60 relative to the proximal end side. Accordingly, in the stent delivery system 10, from the first state in which the outer sheath 50 covers the second portion 60b of the inner shaft 60 (FIG. 1A), the stent 20 and the second portion 60b are exposed to the second state. (FIG. 1(b)). An outermost tube 40 that further covers the outer circumference of the outer sheath 50 is provided near the operation unit 30. If the operator directly grips the outer sheath 50, the movement of the outer sheath 50 by the operation unit 30 may be hindered, but such a problem can be prevented by covering the outer sheath 50 with the outermost tube 40.

As shown in FIG. 5, the outer sheath 50 has flexibility, and is formed by a resin layer 51 made of a polymer material and a plurality of wire rods embedded in the resin layer 51 and braided in a spiral shape. And a braid 52. The braided body 52 is provided in a portion of the outer sheath 50 excluding the distal end portion that covers the second portion 60b of the inner shaft 60.

As a material forming the resin layer 51, a transparent polymer material that allows the stent 20 inside through the outer sheath 50 to be seen is preferable. For example, polyolefin such as polyethylene and polypropylene, polyvinyl chloride, polyurethane, ethylene-vinyl acetate copolymer, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyamide, polyether polyamide, polyester polyamide, fluorine-based such as polytetrafluoroethylene. Various resin materials such as resins, and various thermoplastic elastomers such as styrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based and polybutadiene-based resins can be used. Two or more of these may be used in combination.

The braided body 52 is configured by braiding a plurality of metal wire rods, and forms a tubular body as a whole. In this braided body 52, each wire has a spirally wound shape. The material of the wire material constituting the braided body 52 is, for example, a simple metal such as gold, silver, platinum, copper, iridium, nickel, titanium, tungsten, iron, aluminum, tin, zinc, stainless steel, nichrome steel, nickel-titanium. Examples of the alloy include alloys and titanium-based alloys. Above all, it is preferable to use stainless steel such as SUS304 and SUS316 from the viewpoints of workability, strength, and corrosion resistance.

FIG. 2 is an external view of the stent 20 contained in the stent delivery system 10. The stent 20 is a self-expanding stent that expands from its contracted state by its own elastic force. Further, in the embodiment, as the stent 20, a covered stent for interluminal organ bypass that bypass-connects the stomach or duodenum and the bile duct or gallbladder will be described as an example, but the use and detailed shape of the stent 20 will be described below. Not limited to. For example, the stent contained in the stent delivery system 10 may be a bare stent.

The stent 20 has a cylindrical portion 22 and flexible portions 24, 28 connected to the proximal and distal ends of the cylindrical portion 22.

The cylindrical portion 22 has a frame portion 22a formed by axially connecting zigzag annular struts with a bridge, and a cover film 22b that covers the outer peripheral surfaces of the frame portion 22a and the cylindrical frame portion 22a. The frame portion 22a is made of, for example, a super elastic alloy such as a nickel titanium alloy or a cobalt chromium alloy, a shape memory alloy, or the like, but may be made of another metal or resin.

The material of the cover film 22b is not particularly limited, but a polymer material that is soluble in an organic solvent and has low toxicity is preferable. Examples of the polymer material used for the cover film 22b include non-biodegradable polymers and biodegradable polymers, and non-biodegradable polymers such as polyurethane and silicone resin are particularly preferable.

The axial length of the cylindrical portion 22 is appropriately determined depending on the application of the stent 20, but may be, for example, 10 to 200 mm. Further, the outer diameter of the cylindrical portion 22 when expanded is also appropriately determined depending on the place where the stent 20 is to be placed, and may be, for example, about φ2 to 20 mm. The outer diameter of the cylindrical portion 22 when the diameter is reduced (when housed in the stent delivery system 10) is 1/2 of the outer diameter when the diameter is expanded (when released from the stent delivery system 10). It is about 1/10.

The flexible portion 24 connected to the proximal end of the cylindrical portion 22 is more flexible than the cylindrical portion 22 and is more easily deformed than the cylindrical portion 22 with respect to a force from the axial direction. The flexible portion 24 has a plurality of linear members 25 extending from the proximal end of the cylindrical portion 22. A base end 25a, which is one end of the linear member 25, is connected to the frame part 22a of the cylindrical part 22, and a tip 25b, which is the other end, is curved outward from the base end 25a. Is growing.

As shown in FIG. 3 and the like, while the linear member 25 is accommodated in the stent delivery system 10, the linear member 25 is accommodated in the groove portion 67 with the distal end 25b extended in the axial direction. When released from the stent delivery system 10 as shown in FIG. 1B, the distal end 25b of the linear portion elastically deforms from the proximal end 25a so as to curve in the outer diameter direction, and the state shown in FIG. And is placed in the body.

A round tip protector 26 is connected to the tip 25b of the linear member 25. The tip protector 26 is connected to the tips 25b of the two linear members 25. The flexible portion 24 connected to the proximal end of the cylindrical portion 22 has a total of eight linear members 25 connected at substantially equal intervals along the circumferential direction of the cylindrical portion 22. The number of 25 is not particularly limited.

The linear member 25 is made of an elastically deformable material, for example, the same material as the frame portion 22a of the cylindrical portion 22. The length of the linear member 25 is not particularly limited, but is preferably selected within a range of 10 to 50 mm, for example. Further, the wire diameter of the linear member 25 is preferably smaller than the wire diameter of the struts forming the frame portion 22a. The tip protection portion 26 may be made of the same material as the linear member 25, or may be made of a radiopaque material. When the tip protector 26 is made of a radiopaque material, the tip protector 26 functions as an X-ray marker.

The flexible portion 28 connected to the distal end of the cylindrical portion 22 is similar to the flexible portion 24 connected to the proximal end of the cylindrical portion 22 except that its connecting position and shape are symmetrical.

When the stent 20 is placed so as to bypass between the luminal organs, the flexible portions 24 and 28 of the stent 20 spread in the outer diameter direction and come into contact with the inner wall of the luminal organ. By supporting, the migration of the stent 20 can be effectively prevented. Further, the flexible portions 24 and 28 serve as a cushioning portion that prevents the distal end or the proximal end of the relatively hard cylindrical portion 22 from strongly contacting the body lumen during and after the stent 20 is placed. It works and prevents the problem of the stent 20 damaging the body lumen.

The method for manufacturing the stent 20 shown in FIG. 2 is not particularly limited, but for example, by processing a tube-shaped or pipe-shaped base material with a YAG laser or the like, the frame portion 22a and the flexible portions 24 and 28 connected to both ends thereof are formed. It can be manufactured by integrally molding and then covering only the frame portion 22a with the cover film 22b. In this case, the curved shape of the linear member 25 is formed by giving a habit after processing. The linear members 25 forming the flexible portions 24 and 28 may be formed separately from the frame portion 22a and then fixed to the distal end and the proximal end of the frame portion 22a by welding or the like.

FIG. 3 is a partially enlarged view showing a peripheral portion of the stent 20 accommodated in the stent delivery system 10 in the first state shown in FIG. Note that, in FIG. 3, the outer sheath 50 is seen through for ease of explanation. As shown in FIG. 3, the cylindrical portion 22 of the stent 20 is housed between the second portion 60 b of the inner shaft 60 and the outer sheath 50. Further, the flexible portion 28 (distal end flexible portion) connected to the distal end of the cylindrical portion 22 is also housed between the second portion 60b and the outer sheath 50, like the cylindrical portion 22.

On the other hand, the flexible portion 24 connected to the proximal end of the stent 20 is housed in the groove portion 67 formed in the first portion of the inner shaft 60. FIG. 4 shows the storage portion of the stent 20 shown in FIG. 3 with the stent 20 hidden. As shown in FIG. 4, a groove portion 67 extending in the axial direction is formed in the first portion 60a of the inner shaft 60.

The groove portion 67 is formed across the metal ring 66 arranged at the distal end of the first portion 60a and the outer tube 64 located on the proximal end side of the metal ring 66. The groove portion 67 is open to the step surface 66b of the first portion 60a formed at the connection position with the second portion 60b and the outer peripheral surface of the first portion 60a, and the flexible portion 24 of the stent 20 is The groove 67 is housed inside the groove 67 through the opening of the step surface 66b.

As shown in FIG. 6, which is a perspective view of the metal ring 66, a ring groove portion 66 a which is a distal end portion of the groove portion 67 is formed so as to open to the outer peripheral surface of the metal ring 66. A plurality of ring groove portions 66a (four in the embodiment) are formed in the circumferential direction of the metal ring 66, and the ring groove portions 66a are arranged at substantially equal intervals in the circumferential direction. The ring groove portion 66a extends linearly in the axial direction from the end surface on the distal end side of the metal ring 66 which is the step surface 66b to the end surface on the proximal end side of the metal ring 66.

FIG. 7 is a partially enlarged view showing the vicinity of the distal end of the outer tube 64 of the inner shaft 60. The outer pipe groove portion 64 a, which is the proximal end portion of the groove portion 67, is formed so as to open to the outer peripheral surface of the outer pipe 64. Similar to the ring groove portion 66a shown in FIG. 6, a plurality of outer pipe groove portions 64a (four in the embodiment) are formed in the circumferential direction of the outer pipe 64, and each outer pipe groove portion 64a is substantially equally spaced in the circumferential direction. It is located in. The outer tube groove portion 64 a is open to the outer tube distal end surface 64 b which is the end surface of the outer tube 64 on the distal end side that contacts the metal ring 66, and communicates with the ring groove portion 66 a of the metal ring 66. On the outer peripheral surface of the inner tube 62 adjacent to the end surface on the distal end side of the outer tube 64, there is a ring installation portion 62b for installing the metal ring 66.

As shown in FIG. 3, the linear member 25 that constitutes the flexible portion 24 of the stent 20 has two grooves connected by the tip protecting portion 26 as one set, and the groove portion 67 adjacent to the proximal end side of the cylindrical portion 22. , One set each. A portion of the linear member 25 on the base end 25a side is housed in the ring groove portion 66a, and a portion of the linear member 25 on the tip end 25b side is housed in the outer pipe groove portion 64a. When the stent delivery system 10 is in the first state, the opening on the outer peripheral surface side of the groove portion 67 is covered by the outer sheath 50, so that a line having a tendency to curve in the outer diameter direction as shown in FIG. Even in the case of the linear member 25, the linear member 25 is stretched by elastic deformation to be housed in the groove portion 67, and its restoration is pressed by the outer sheath 50, so that the linear member 25 is preferably housed in the groove portion 67.

The depth of the groove portion 67 is preferably larger than the wire diameter of the linear member 25 and the thickness of the tip protecting portion 26, and is not more than the thickness of the outer tube 64 shown in FIG. 5, but is not particularly limited. Further, the depth and width of the ring groove portion 66a and the outer pipe groove portion 64a may be the same or different.

The material of the metal ring 66 is not particularly limited as long as it is a metal or alloy harder than the resin forming the outer tube 64, and may be stainless steel, gold, platinum, tungsten, or the like, and gold, platinum, tungsten, or the like. The X-ray opaque material is preferable because the metal ring 66 functions as an X-ray opaque marker. The metal ring 66 can be manufactured by preparing a plate-shaped or columnar material, and then machining this to form the ring groove portion 66a or casting the metal ring 66 having the shape shown in FIG. However, the method for producing the metal ring 66 is not particularly limited.

The method of forming the outer tube groove portion 64a shown in FIG. 7 is not particularly limited, and the outer tube groove portion 64a can be formed by, for example, cutting or heat-processing the distal end portion of the outer tube 64. When the depth of the outer pipe groove portion 64a is the same as the thickness of the outer pipe 64, the outer pipe groove portion 64a can be formed by cutting the distal end portion of the outer pipe 64 into the width of the groove portion. The metal ring 66 is fixed to the ring installation portion 62b of the inner tube 62 by, for example, adhesion, but the method of fixing the metal ring 66 is not particularly limited.

Thus, in the stent delivery system 10, the flexible portion 24 on the proximal end side of the stent 20 is accommodated in the groove portion 67 formed in the first portion 60a of the inner shaft 60. Therefore, when the stent 20 is released, even if the stent 20 receives a frictional force from the outer sheath 50 that relatively moves toward the proximal end side, it is possible to prevent a problem that the flexible portion 24 receives an excessive deforming force.

Further, since the groove portion 67 is open to the step surface 66b and extends along the axial direction, a part of the linear member 25 forming the flexible portion 24 has an inner shaft having a first outer diameter. The problem of being sandwiched between the first portion 60a of 60 and the outer sheath 50 is prevented, deformation of the linear member 25 is prevented, and smooth relative movement of the outer sheath 50 is realized. Furthermore, since the flexible portion 24 is inserted into the groove portion 67 through the opening of the step surface 66b, even when the cylindrical portion 22 receives a force toward the proximal end side during the discharging operation, The proximal end face of the barrel 22 is suitably pressed against the distal end face of the metal ring 66, allowing the barrel 22 to remain in the second portion 60b. Therefore, in the stent delivery system 10, the releasing operation of the stent 20 can be smoothly performed without crushing the flexible portion 24.

In addition, the inner shaft 60, which disposes the metal ring 66 at the distal end of the first portion 60a, can stably receive the force from the cylindrical portion 22 in the discharging operation of the stent 20, so that the stent 20 can be discharged. It is possible to perform the operation smoothly. Furthermore, by forming the groove portion 67 over both the metal ring 66 and the outer tube 64, the flexible portion 24 that is long in the axial direction can be properly accommodated, and by forming the groove portion only by the metal ring. The problem of reducing the flexibility of the inner shaft can also be avoided.

Although the features of the present invention have been described above with reference to the exemplary embodiments, the present invention is not limited to the specific modes shown in these exemplary embodiments, and it goes without saying that various other exemplary embodiments are included. For example, in the stent delivery system 10, as shown in FIG. 4, a part of the groove portion 67 is formed in the metal ring 66, but the metal ring 66 is not arranged at the distal end of the first portion 60a, and the groove portion is not formed. May be composed of only the outer pipe groove portion 64a formed in the outer pipe 64.

Further, the stent delivery system according to another embodiment may have a groove portion that accommodates the flexible portion 28 on the distal end side of the stent 20. In that case, the shape of the groove portion that accommodates the flexible portion 28 may be symmetrical with respect to the groove portion 67, and the formation position of such a groove portion may be the second portion 60b of the inner shaft 60. Alternatively, the tip 80 may be used.

DESCRIPTION OF SYMBOLS 10... Stent delivery system 20... Stent 22... Cylindrical part 22a... Frame part 22b... Cover film 24, 28... Flexible part 25... Linear member 25a... Base end 25b... Tip 26... Tip protecting part 30... Operation part 31... Housing 33... Operating lever 40... Outermost tube 50... Outer sheath 52... Braided body 60... Inner shaft 60a... First part 60b... Second part 62... Inner tube 62a... Guide wire lumen 62b... Ring installation part 64... Outer Tube 64a... Outer tube groove 64b... Outer tube distal end surface 66... Metal ring 66a... Ring groove 66b... Step surface 67... Groove 80... Tip

Claims (5)

An inner shaft having a first portion having a first outer diameter and a second portion having a second outer diameter smaller than the first outer diameter and connected to a distal end of the first portion. ,
With respect to the inner shaft, from the first state, which is inserted through the first portion and the second portion, and covers the second portion, to the second state in which the second portion is exposed from the distal end. An outer sheath that is relatively movable in the axial direction,
A cylindrical portion housed between the second portion and the outer sheath; and a flexible portion connected to the proximal end of the cylindrical portion and more easily deformed than the cylindrical portion due to a force from the axial direction. And a stent having,
The first portion extends in the axial direction and is opened at a step surface of the first portion formed at a connection position with the second portion and an outer peripheral surface of the first portion, and the flexible portion is formed. A groove is formed to accommodate the entire part ,
The stent delivery system , wherein when the cylindrical portion moves proximally in the axial direction with respect to the inner shaft, the cylindrical portion contacts the step surface and is held by the second portion . The first portion of the inner shaft has a metal ring disposed at a distal end of the first portion,
The stent delivery system according to claim 1, wherein at least a part of the groove is formed in the metal ring. The inner shaft has a resin outer tube having the first outer diameter and the second outer diameter, is inserted through the outer tube, and is exposed from a distal end of the outer tube. An inner tube that constitutes the second portion,
The stent delivery system according to claim 1, wherein at least a part of the groove is formed in the outer tube. The stent delivery system according to any one of claims 1 to 3, wherein a plurality of the groove portions are formed in the circumferential direction of the first portion. One end of the flexible portion is connected to the proximal end of the cylindrical portion, and the other end of the flexible portion is a linear member that is elastically deformable so as to be curved outward from the one end. The stent delivery system according to any one of claims 1 to 4, further comprising:

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