Stent Delivery System

Abstract

The present invention provides a stent delivery system that allows for the withdrawal of stents even with small outer diameters, prevents accidental disconnection of the connection between the stent and the pusher catheter, and makes it easy to disconnect the connection when desired. [Solution] The stent delivery system 100 includes a stent 10 and a pusher catheter 20 to which a thread-like body with a knot-like structure is attached. The thread-like body and the knot-like structure are inserted into the large-diameter portion 14 of the stent 10, and with the knot-like structure loosely fitted into the locking hole, the inner catheter 30 is inserted into the pusher catheter 20 and the large-diameter portion 14 of the stent 10, and the inner catheter 30 maintains the loosely fitted state between the knot-like structure and the locking hole.

Description

Technical Field

[0001] The present invention relates to a stent delivery system using a catheter, and particularly to one that uses a plastic tube stent (hereinafter sometimes simply referred to as a "stent") such as polyethylene or polyurethane.

Background Art

[0002] Among the stents used in stent placement procedures, the tube stent advances inside the human body by being pushed by a pusher catheter along a guide wire or an inner catheter inserted into the human body. Conventionally, the tube stent can only be pushed by a pusher catheter and cannot be pulled back. If the positioning of the stent is incorrect, the stent has to be removed and redone. Therefore, delivery systems that can pull back the stent have been developed.

[0003] The applicant of the present invention has developed a stent delivery system that can pull back the stent, has a simple structure, is unlikely to accidentally release the connection state between the stent and the pusher catheter, and is easy to release when the connection state needs to be released, and has patent rights related to the following publications.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the stent delivery system described in Patent Document 1, the pusher catheter has a hole for attaching a thread-like body to its end, and the stent has a hooking hole. The knob-like body provided on the thread-like body is loosely fitted into the hooking hole from the inside of the stent, and this loose fit is maintained by the inner catheter inserted inside the stent. Therefore, the connection between the stent and the pusher catheter is not easily released unintentionally until the inner catheter is withdrawn. When the inner catheter is withdrawn, the knob-like body comes out of the hooking hole, and the connection between the stent and the pusher catheter is easily released.

[0006] Incidentally, by reducing the outer diameter of a stent, it becomes easier for it to advance within the human body and the number of treatable areas can be increased. Therefore, in recent years, stents with smaller outer diameters have been developed. Stents with an outer diameter of less than 5 Fr (French) can be called ultra-fine stents, and stents with an outer diameter of 3 Fr or less, i.e., less than 1 mm, have also appeared. However, stents with smaller outer diameters also have smaller diameters of their internal communication holes (hereinafter referred to as "inner diameter"). In this case, although it is possible to pass a guidewire through the inside of the stent, it is not possible to pass an inner catheter between the inner diameter of the stent and the guidewire, which presents the problem that the stent delivery system described above cannot be applied.

[0007] Therefore, the object of the present invention is to provide a stent delivery system that allows a stent to be withdrawn even if it has a small outer diameter, makes it difficult for the connection between the stent and the pusher catheter to be accidentally released, and makes it easy to release the connection when desired. [Means for solving the problem]

[0008] The present invention comprises a tube stent, a pusher catheter, and an inner catheter. The tube stent has a small diameter portion with an outer diameter of less than 5 Fr at its tip, a large diameter portion with an inner diameter that allows the inner catheter to be inserted at its proximal end, and a locking hole provided in the radial direction of the large diameter portion. The pusher catheter, which can contact the end face of the large-diameter portion, has a hole provided in the radial direction and a thread-like body having a knot-like structure that is attached using the hole. With the filamentous body and the knob-like body inserted into the large-diameter portion, and with the knob-like body loosely fitted in the locking hole, the inner catheter is inserted into the pusher catheter and the large-diameter portion. A stent delivery system characterized in that the inner catheter maintains a loose fit between the knob-like body and the locking hole. Or, It has a tube stent, a pusher catheter, and an inner catheter. The tube stent has a small diameter portion with an outer diameter of less than 5 Fr at its tip, a large diameter portion with an inner diameter into which the inner catheter can be inserted at its proximal end, a hole provided in the radial direction of the large diameter portion, and a thread-like body having a knot-like structure that is attached using the hole. The pusher catheter, which can contact the end face of the large-diameter portion, is provided with a hooking hole in the radial direction. With the filamentous body and the knob-like body inserted into the pusher catheter, and the knob-like body loosely fitted into the locking hole, the inner catheter is inserted into the pusher catheter and the large-diameter portion. The above problem was solved by a stent delivery system characterized in that the inner catheter maintains a loose fit between the knob-like body and the locking hole. [Effects of the Invention]

[0009] According to the present invention, a stent having a small diameter portion with an outer diameter of less than 5 Fr at its tip end has a large diameter portion with an inner diameter that allows an inner catheter to be inserted at its proximal end, and the large diameter portion is provided with a hooking hole in the radial direction. The pusher catheter has a thread-like body with a knot-like body, and the thread-like body and the knot-like body are inserted into the large diameter portion, and the knot-like body is loosely fitted with the hooking hole. The inner catheter is then inserted into the pusher catheter and the large diameter portion, and the inner catheter maintains the loosely fitted state between the knot-like body and the hooking hole. Therefore, even if the stent has a small diameter portion with an outer diameter of less than 5 Fr, the stent can be pulled back, the connection between the stent and the pusher catheter is not easily released unintentionally, and the connection can be easily released when desired. This provides a stent delivery system.

[0010] Furthermore, the stent delivery system may be configured such that a hooking hole is provided in the radial direction of the pusher catheter, and a thread-like body with a knot-like structure is attached to a hole provided in the radial direction of the large-diameter portion of the stent. With this configuration, when removing the stent after placement, the thread-like body is easier to grasp with forceps or the like, making it easier to remove the stent.

[0011] According to the present invention, when a stent is placed in the body, the large-diameter portion can act as a so-called flap, hooking onto the implantation site to prevent the stent from being inserted more than necessary. Furthermore, when removing the stent after implantation, the large-diameter portion is easy to grasp with forceps or the like, making the stent easier to remove.

[0012] Furthermore, if a tapered section is provided between the large-diameter and small-diameter sections, gradually decreasing in diameter from the large-diameter section to the small-diameter section, it becomes easier to insert a guide wire from the large-diameter section through the tapered section to the small-diameter section when it is necessary to insert a guide wire into the inside of the implanted stent, compared to a small-diameter stent without a large-diameter section. [Brief explanation of the drawing]

[0013] [Figure 1]A side view of a first embodiment of the stent delivery system of the present invention. [Figure 2] Enlarged cross-sectional view of the main part shown in Figure 1. [Figure 3] A side view of a second embodiment of the stent delivery system of the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to Figures 1 to 3. However, the present invention is not limited to these embodiments.

[0015] The stent delivery system 100 of the present invention, shown in Figure 1, comprises a tubular stent (stent) 10, a pusher catheter 20, an inner catheter 30, and a guidewire 40. The stent 10, pusher catheter 20, and inner catheter 30 are cylindrical in shape. The stent 10 can be made of plastic such as polyethylene or polyurethane, the pusher catheter 20 can be made of fluororesin such as PTFE (polytetrafluoroethylene), and the inner catheter 30 can be made of fluororesin such as ETFE (ethylene-tetrafluoroethylene copolymer). The guidewire 40 is a wire mainly made of metal with a coating on its surface. The stent 10, pusher catheter 20, inner catheter 30, and guidewire 40 are inserted into an endoscope (not shown) for use.

[0016] The stent 10 includes a small-diameter portion 12 and a large-diameter portion 14. The small-diameter portion 12 is located on the distal end side of the stent 10, and its outer diameter is less than 5 Fr, preferably 3 Fr or less. On the other hand, the large-diameter portion 14 is located on the proximal end side of the stent 10 and has an inner diameter through which the inner catheter 30 can be inserted. When corresponding to a general inner catheter, the outer diameter of the large-diameter portion 14 is 6 Fr or more. However, in the future, if a smaller-diameter inner catheter is developed, the large-diameter portion 14 only needs to have an inner diameter through which the inner catheter can be inserted. The dimensions and shapes of the small-diameter portion 12 and the large-diameter portion 14 are not limited to those shown in the drawings and are arbitrary. For example, they may be curved shapes such as a curved shape or a pigtail shape.

[0017] The stent 10 may include a tapered portion 13 that gradually decreases in diameter from the large-diameter portion 14 toward the small-diameter portion 12 between the large-diameter portion 14 and the small-diameter portion 12, or may include a distal taper portion 15 that gradually decreases in diameter toward the distal end side from the small-diameter portion 12. The stent 10 having such a shape can be formed by hot working or stretching a cylinder having the outer diameter of the large-diameter portion 14, or by welding a cylinder having the outer diameter of the small-diameter portion 12, a cylinder having the outer diameter of the large-diameter portion 14, and a hollow tapered portion 13.

[0018] The inner catheter 30 is inserted into the pusher catheter 20 so as to penetrate the inside of the pusher catheter 20 and is inserted into the large-diameter portion 14 of the stent 10. The pusher catheter 20 is formed with an outer diameter such that the end face on the distal end side can contact the end face on the proximal end side of the large-diameter portion 14 of the stent 10. The guide wire 40 is inserted into the inner catheter 30 and the stent 10 so as to penetrate the inside of the inner catheter 30 and the stent 10.

[0019] As shown in FIG. 2, the large-diameter portion 14 of the stent 10 is provided with a latching hole 16 in the radial direction thereof. The latching hole 16 is provided with a size such that a knob-shaped body 52 described later can be loosely fitted. On the other hand, the pusher catheter 20 is provided with a hole 22 in the radial direction thereof. The hole 22 is provided with a size such that a filamentous body 50 described later can be inserted therethrough, and it is preferably provided on the tip side of the pusher catheter 20 in order to prevent the filamentous body 50 from becoming overly long.

[0020] The filamentous body 50 is passed through the hole 22. Although the illustration description is omitted, the filamentous body 50 may be attached to the pusher catheter 20 by passing the filamentous body 50 through the hole 22, tying a knot, and securing the knot. Further, the filamentous body 50 has a knob-shaped body 52. The knob-shaped body 52 may be formed by tying the filamentous body 50 or may be provided by welding a sphere.

[0021] As shown in the figure, with the filamentous body 50 and the knob-shaped body 52 attached to the pusher catheter 20 inserted into the inside of the large-diameter portion 14 of the stent 10 and the knob-shaped body 52 being loosely fitted with the latching hole 16, the inner catheter 30 is inserted into the inside of the pusher catheter 20 and the large-diameter portion 14 of the stent 10. Thereby, the inner catheter 30 maintains the loosely fitted state between the knob-shaped body 52 and the latching hole 16. In FIG. 2, for convenience of explanation, the sizes of the large-diameter portion 14 of the stent 10, the pusher catheter 20, the inner catheter 30, and the knob-shaped body 52 are exaggeratedly shown.

[0022] Since the stent delivery system 100 has the above configuration, even if the stent 10 has a small diameter section 12 with an outer diameter of less than 5 Fr, the stent 10 can be pulled back by pulling the pusher catheter 20 when the stent 10 is placed in the body. At that time, the inner catheter 30 maintains a loose fit between the knob-shaped body 52 and the locking hole 16, so the connection between the stent 10 and the pusher catheter 20 is not easily released unintentionally. Furthermore, when it is desired to release the connection between the stent 10 and the pusher catheter 20, the inner catheter 30 is withdrawn, causing the knob-shaped body 52 to move into the large diameter section 14 of the stent 10, and the connection between the stent 10 and the pusher catheter 20 is released. Therefore, a stent delivery system is provided that makes it easy to release the connection between the stent 10 and the pusher catheter 20.

[0023] Furthermore, when the stent 10 is placed in the body, the large-diameter portion 14 can act as a flap, preventing the stent 10 from being inserted into the implantation site more than necessary. Also, when removing the stent 10 after implantation, the large-diameter portion 14 is easy to grasp with forceps or the like, making it easier to remove the stent 10. Moreover, if the stent delivery system 100 is configured to have a tapered portion 13 between the large-diameter portion 14 and the small-diameter portion 12, it is easier to insert the guide wire 50 from the large-diameter portion 14 through the tapered portion 13 into the small-diameter portion 12 when it is necessary to insert the guide wire 40 into the implanted stent 10, compared to a small-diameter stent without a large-diameter portion 14.

[0024] Furthermore, as shown in the figure, the filamentous body 50 may be configured to have an extension portion 54 that extends beyond the locking hole 16 when viewed from the pusher catheter 20. With this configuration, the filamentous body 50 and the extension portion 54 are sandwiched between the tube stent 10 and the inner catheter 30 before and after the locking hole 16, so that the knob-like body 52 does not completely protrude outside the stent 10. In addition, when the inner catheter 30 is withdrawn, the knob-like body 52 naturally tries to return to the inside of the stent 10, so that the connection between the stent 10 and the pusher catheter 20 can be reliably and easily released.

[0025] Although a diagrammatic explanation is omitted, the basic configuration is the same as that of the stent delivery system 100, with a locking hole 16 provided radially in the pusher catheter 20, a hole 22 provided radially in the large diameter portion 14 of the stent 10, and a thread-like body 50 with a knob-like body 52 attached using the hole 22 in the large diameter portion 14. With this configuration, when removing the stent 10 after placement, the thread-like body 50 is easier to grasp with forceps or the like, making it easier to remove the stent 10.

[0026] As shown in the stent delivery system 100a in Figure 3, a configuration is also possible in which there is no tapered section between the small-diameter portion 12a and the large-diameter portion 14a of the stent 10a. Such a stent 10a is formed by welding a cylinder having the outer diameter of the small-diameter portion 12a and a cylinder having the outer diameter of the large-diameter portion 14a.

[0027] As described above, the present invention provides a stent delivery system that allows even a stent with a small outer diameter to be retracted, makes it difficult for the connection between the stent and the pusher catheter to be unintentionally released, and makes it easy to release the connection when desired. [Explanation of Symbols]

[0028] 10 Tube Stent 12 Small diameter section 13 Tapered section 14 Large diameter section 16 Latch hole 20 Pusher Catheter 22 holes 30 Inner Catheter 50 filamentous bodies 52 Nodular bodies 100 Stent Delivery System

Claims

1. It has a tube stent, a pusher catheter, and an inner catheter. The tube stent has a small diameter portion with an outer diameter of less than 5 Fr at its tip end, a large diameter portion with an inner diameter into which the inner catheter can be inserted at its proximal end, and a locking hole provided in the radial direction of the large diameter portion. The pusher catheter, which can contact the end face of the large-diameter portion, has a hole provided in the radial direction and a thread-like body having a knot-like structure that is attached using the hole. With the filamentous body and the knob-like body inserted into the large-diameter portion, and with the knob-like body loosely fitted in the locking hole, the inner catheter is inserted into the pusher catheter and the large-diameter portion. The inner catheter is characterized by maintaining a loose fit between the knob-shaped body and the locking hole. Stent delivery system.

2. It has a tube stent, a pusher catheter, and an inner catheter. The tube stent has a small diameter portion with an outer diameter of 3Fr or less at its tip, a large diameter portion with an inner diameter into which the inner catheter can be inserted at its proximal end, a hole provided in the radial direction of the large diameter portion, and a thread-like body having a knot-like structure that is attached using the hole. The pusher catheter, which can contact the end face of the large-diameter portion, is provided with a hooking hole in the radial direction. With the filamentous body and the knob-like body inserted into the pusher catheter, and the knob-like body loosely fitted into the locking hole, the inner catheter is inserted into the pusher catheter and the large-diameter portion. The inner catheter is characterized by maintaining a loose fit between the knob-shaped body and the locking hole. Stent delivery system.

3. The stent delivery system according to claim 1 or 2, further comprising a tapered portion between the large-diameter portion and the small-diameter portion, which gradually decreases in diameter from the large-diameter portion to the small-diameter portion.

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