Stent delivery system

Abstract

In a stent delivery system 100, a tube stent 10 is equipped with a reduced inner diameter part 12 on the base end side, and a pusher catheter 20 capable of coming into contact with the end face of the reduced inner diameter part 12 is equipped with a hole 22 provided in the radial direction and a thread-like body 52 that is attached by using the hole 22 and that is provided with a knob-like body 54. The reduced inner diameter part 12 is equipped with a hooking hole 14 provided in the radial direction, and an inner diameter that is larger than the longest dimension of the knob-like body 54 and smaller than the sum of the longest dimension of the knob-like body 54 and the outer diameter of a guide wire 30. In a state in which the thread-like body 52 and the knob-like body 54 are inserted into the reduced inner diameter part 12 and the knob-like body 54 is loosely fitted to the hooking hole 14, the guide wire 30 is inserted into the pusher catheter 20 and the reduced inner diameter part 12, and the guide wire 30 maintains the loosely fitted state between the knob-like body 54 and the hooking hole 14.

Description

Stent Delivery System

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

[0002] Among the stents used in stent placement, tube stents are advanced through the body by being pushed by a pusher catheter along a guide wire or inner catheter inserted into the body. Conventionally, tube stents could only be pushed by a pusher catheter and could not be pulled back, so if the stent was positioned incorrectly, the stent had to be removed and then reinserted. Therefore, delivery systems that allow the stent to be pulled back 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, 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, and holds patent rights related to the publications listed below.

[0004] Patent No. 4913251

[0005] In the stent delivery system of Patent Document 1, the pusher catheter has a hole for attaching a filament to its end, and the stent has a hooking hole. The knobby member on the filament is loosely fitted into the hooking hole from inside the stent, and this loose fitting state is maintained by an inner catheter inserted inside the stent. Therefore, the connection between the stent and the pusher catheter is unlikely to be inadvertently released until the inner catheter is pulled out, and when the inner catheter is pulled out, the knobby member comes out of the hooking hole, and the connection between the stent and the pusher catheter is easily released.

[0006] By reducing the outer diameter of a stent, it becomes easier to advance it within the human body and the number of treatable sites can be increased. Therefore, in recent years, stents with smaller outer diameters have been developed. Stents with an outer diameter of less than 5 French (Fr) are considered ultrathin stents, and stents with an outer diameter of 3 French (Fr) or less, i.e., an outer diameter of 1 mm or less, have also appeared. However, a stent with a small outer diameter also has a small diameter of its internal communicating holes (hereinafter referred to as the "inner diameter"). In this case, although it is possible to pass a guidewire through the stent, it is not possible to pass an inner catheter between the inner diameter of the stent and the guidewire, which creates a problem in that the above-mentioned stent delivery system cannot be applied.

[0007] Therefore, an object of the present invention is to provide a stent delivery system that can pull back a stent even if it has a small outer diameter, that makes it difficult for the connection between the stent and the pusher catheter to be inadvertently released, and that makes it easy to release the connection when desired.

[0008] The present invention relates to a stent delivery system comprising a guidewire, a cylindrical tube stent, and a pusher catheter, wherein the tube stent has a small inner diameter portion on the proximal end side, the pusher catheter that can come into contact with an end face of the small inner diameter portion has a hole provided in the radial direction and a filament having a knobby body that is attached using the hole, the small inner diameter portion has an inner diameter that is larger than the longest dimension of the knobby body and smaller than the sum of the longest dimension and the outer diameter of the guidewire, and a hooking hole provided in the radial direction, the filament and knobby body are inserted into the small inner diameter portion, and the guidewire is inserted into the pusher catheter and small inner diameter portion with the knobby body loosely fitted in the hooking hole, and the guidewire maintains a loose fit state between the knobby body and the hooking hole, or a stent delivery system comprising a guidewire, a cylindrical tube stent, and a pusher catheter, wherein the pusher catheter has a small inner diameter portion on the distal end side, The above problem was solved by a stent delivery system characterized in that the tube stent, which can come into contact with the end face of the small inner diameter portion, has a radially formed hole and a filament having a knobby body that is attached using the hole, the small inner diameter portion has an inner diameter that is larger than the longest dimension of the knobby body and smaller than the sum of the longest dimension and the outer diameter of the guide wire, and has a radially formed hooking hole, the filament and knobby body are inserted inside the small inner diameter portion, and the guide wire is inserted into the small inner diameter portion and the tube stent with the knobby body loosely fitted in the hooking hole, and the guide wire maintains a loose fit between the knobby body and the hooking hole.

[0009] According to the present invention, a tube stent has a small-diameter portion on its proximal end, a pusher catheter that can contact the end face of the small-diameter portion has a hole provided in the radial direction and a filament having a knot that is attached using the hole, the small-diameter portion has a hooking hole provided in the radial direction and an inner diameter that is larger than the longest dimension of the knot and smaller than the sum of the longest dimension of the knot and the outer diameter of the guidewire, and the filament and the knot are inserted into the small-diameter portion and the knot is loosely fitted in the hooking hole, and then the guidewire is inserted into the pusher catheter and the small-diameter portion, and the guidewire maintains the loose fit between the knot and the hooking hole, so that even an extremely thin stent that cannot be passed through an inner catheter can be pulled back, and a stent delivery system can be provided in which the connection between the stent and the pusher catheter is difficult to inadvertently release and can be easily released when desired.

[0010] The stent delivery system may also be configured such that the pusher catheter has a small inner diameter portion at the distal end, and the tube stent that can contact the end face of the small inner diameter portion has a hole formed in the radial direction and a filament having a knobby body that is attached using the hole. With this configuration, when removing the stent after placement, the filament can be easily grasped with forceps or the like, making it easy to remove the stent.

[0011] 1 is a side view of a first embodiment of a stent delivery system of the present invention;

[0012] An embodiment of the present invention will be described below with reference to Figures 1 and 2. However, the present invention is not limited to this embodiment.

[0013] The stent delivery system 100 of the present invention shown in Figure 1 includes a tube stent (stent) 10, a pusher catheter 20, and a guidewire 30. The stent 10 and the pusher catheter 20 are cylindrical. The stent 10 can be made of plastic such as polyethylene or polyurethane, and the pusher catheter 20 can be made of a fluororesin such as PTFE (polytetrafluoroethylene). The guidewire 30 is a wire made primarily of metal with a coating applied to its surface. The stent 10, pusher catheter 20, and guidewire 30 are inserted into an endoscope (not shown) for use.

[0014] The outer diameter of the stent 10 can be any diameter, but the stent delivery system 100 of the present invention is also applicable to ultra-thin stents with an outer diameter of less than 5 Fr. The distal end of the stent 10 may be provided with a tapered portion 15 that narrows toward the distal end. The outer diameter of the pusher catheter 20 may be set to a diameter that allows the end face of the proximal end of the stent 10 to come into contact with the end face of the distal end of the pusher catheter 20. The guidewire 30 is inserted through the pusher catheter 20 so as to penetrate the interior of the pusher catheter 20, and is inserted into the interior of the stent 10. Therefore, the outer diameter of the guidewire 30 may be set to a diameter that allows it to pass through the interior of the stent 10 and the pusher catheter 20.

[0015] The stent 10 has a small inner diameter portion 12 on its proximal end side. The small inner diameter portion 12 is a portion of the stent 10 where the inside diameter is formed to be small. The small inner diameter portion 12 of the stent 10 can be formed by manufacturing a stent 10 having the same inner diameter as the small inner diameter portion 12, inserting a jig into the inside of the stent 10 and stretching the distal end side of the stent 10, or by separately manufacturing the small inner diameter portion 12 and the portion of the stent 10 located distal to the small inner diameter portion 12, which have different inner diameters, and welding them together.

[0016] The stent delivery system 100 is provided with a coupling mechanism 50 between the stent 10 and the pusher catheter 20, utilizing the small inner diameter portion 12 of the stent 10. The coupling mechanism 50 will be described in detail below.

[0017] Figure 2 is an enlarged cross-sectional view of a main portion of the stent delivery system 100. As shown in Figure 2, the stent 10 has a small inner diameter portion 12 on the proximal end side. The small inner diameter portion 12 has an inner diameter that is larger than the longest dimension of the hump-shaped body 54 of the connecting mechanism 50 and smaller than the sum of the longest dimension of the hump-shaped body 54 and the outer diameter of the guidewire 30. The small inner diameter portion 12 also has a locking hole 14 formed in the radial direction. The locking hole 14 may be a through hole or a blind hole, and is formed in a size that allows the hump-shaped body 54 to fit loosely.

[0018] On the other hand, a hole 22 is formed in the radial direction of the pusher catheter 20. The hole 22 is formed to a size that allows a filament 52, which will be described later, to be inserted therethrough, and is preferably formed on the distal end side of the pusher catheter 20 to prevent the filament 52 from becoming longer than necessary.

[0019] A filament 52 of the connecting mechanism 50 is passed through the hole 22. Although not shown in the drawings, the filament 52 may be attached to the pusher catheter 20 by passing the filament 52 through the hole 22, tying a knot, and securing it with a knot. The filament 52 also has a knob 54. The knob 54 may be formed by tying the filament 52, or may be provided by welding a sphere.

[0020] As shown in the figure, the filament 52 and the knot 54 attached to the pusher catheter 20 are inserted into the small-diameter inner portion 12 of the stent 10, and the guide wire 30 is inserted into the pusher catheter 20, the small-diameter inner portion 12 of the stent 10, and the inside of the stent 10, with the knot 54 loosely fitted into the locking hole 14. In this way, the guide wire 30 maintains a loose fit between the knot 54 and the locking hole 14. For ease of explanation, the sizes of the small-diameter inner portion 12 of the stent 10, the pusher catheter 20, the guide wire 30, and the knot 54 are exaggerated in Figure 2.

[0021] Because the stent delivery system 100 has the above configuration, when placing the stent 10 in the body, the stent 10 can be pulled back by pulling the pusher catheter 20. At this time, the guidewire 30 maintains a loose fit between the knobby member 54 and the locking hole 14, making it difficult for the connection between the stent 10 and the pusher catheter 20 to be inadvertently released. Furthermore, when it is desired to release the connection between the stent 10 and the pusher catheter 20, the guidewire 30 is pulled out, causing the knobby member 54 to move into the small inner diameter portion 12 of the stent 10, thereby releasing the connection between the stent 10 and the pusher catheter 20. This provides a stent delivery system that makes it easy to release the connection between the stent 10 and the pusher catheter 20. In particular, the stent delivery system 100 can be applied to ultra-thin stents with an outer diameter of less than 5 Fr, which cannot be passed through an inner catheter.

[0022] Also, as shown in the drawings, the filament 52 may have an extension 56 that extends beyond the hooking hole 14 when viewed from the pusher catheter 20. With this configuration, the filament 52 and the extension 56 are sandwiched between the small inner diameter portion 12 of the stent 10 and the guidewire 30 on both sides of the hooking hole 14, preventing the knot 54 from completely extending outside the hooking hole 14 of the stent 10. Furthermore, when the guidewire 30 is pulled out, the knot 54 naturally moves inside the small inner diameter portion 12 of the stent 10, allowing the connection between the stent 10 and the pusher catheter 20 to be reliably and easily released.

[0023] Although not illustrated, the basic configuration is the same as that of the stent delivery system 100, and the small inner diameter portion 12 and the hooking hole 14 may be provided at the distal end of the pusher catheter 20, the hole 22 may be provided at the proximal end of the stent 10, and the filament 52 having the knobby member 54 may be attached using the hole 22. That is, the reference numeral 20 in Fig. 2 may be the stent and the reference numeral 10 may be the pusher catheter. With this configuration, after the stent 10 has been placed, the filament 52 can be easily grasped with forceps or the like when removing the stent 10, making it easy to remove the stent 10.

[0024] As described above, according to the present invention, it is possible to provide a stent delivery system that can pull back a stent even if it has a small outer diameter, that makes it difficult for the connection between the stent and the pusher catheter to be inadvertently released, and that makes it easy to release the connection when desired.

[0025] REFERENCE SIGNS LIST 10 Tube stent 12 Small inner diameter portion 14 Hook-up hole 20 Pusher catheter 22 Hole 30 Guide wire 52 Filament 54 Knob 100 Stent delivery system

Claims

1. A stent delivery system comprising a guidewire, a cylindrical tube stent, and a pusher catheter, wherein the tube stent has a small inner diameter portion on its proximal end, the pusher catheter that can come into contact with the end face of the small inner diameter portion has a radial hole and a filament having a knobby body that is attached using the hole, the small inner diameter portion has an inner diameter that is larger than the longest dimension of the knobby body and smaller than the sum of the longest dimension and the outer diameter of the guidewire, and has a radially formed hooking hole, the filament and knobby body are inserted inside the small inner diameter portion, and with the knobby body loosely fitted in the hooking hole, the guidewire is inserted inside the pusher catheter and small inner diameter portion, and the guidewire maintains a loose fit between the knobby body and the hooking hole.

2. A stent delivery system comprising a guidewire, a cylindrical tube stent, and a pusher catheter, wherein the pusher catheter has a small inner diameter portion at its tip end, the tube stent that can come into contact with the end face of the small inner diameter portion has a radial hole and a filament having a knobby body that is attached using the hole, the small inner diameter portion has an inner diameter that is larger than the longest dimension of the knobby body and smaller than the sum of the longest dimension and the outer diameter of the guidewire, and has a radially formed hooking hole, the filament and knobby body are inserted inside the small inner diameter portion, and with the knobby body loosely fitted in the hooking hole, the guidewire is inserted into the small inner diameter portion and the tube stent, and the guidewire maintains a loose fit between the knobby body and the hooking hole.

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