STENT DELIVERY APPARATUS

A stent delivery apparatus includes a guide catheter through which a guide wire is inserted, a pusher catheter including a first lumen through which the guide catheter is inserted and a first communication hole communicating with the first lumen, a stent including a second lumen through which the guide catheter is inserted and a second communication hole communicating with the second lumen and disposed on a distal side of the pusher catheter, and a thread that connects the stent and the pusher catheter to each other in a releasable manner, wherein the thread has a first end portion that through the first communication hole, an intermediate portion that through the second communication hole, and a second end portion that extends around a part of the guide catheter located between a proximal end of the stent and a distal end of the pusher catheter.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a stent delivery apparatus.

This application is a continuation application based on a PCT International Application No. PCT/JP2019/012673, filed on Mar. 26, 2019. The content of the PCT International Application is incorporated herein by reference.

Description of Related Art

A stent placement in a bile duct is known as a treatment for bile duct stenosis. Usually, the stent is attached to a stent delivery apparatus and introduced to a target part.

A stent delivery apparatus disclosed in U.S. Pat. No. 6,264,624 includes a stent, a guide catheter, and a pusher catheter. Since the stent is temporarily connected to the pusher catheter by a string, when the pusher catheter is pulled back, the stent is also pulled back to follow the pusher catheter, so that a placement position can be adjusted. When the guide catheter is retracted, the connection by the string is released and the stent can be released.

SUMMARY OF THE INVENTION

In the stent delivery apparatus of U.S. Pat. No. 6,264,624, the stent and the pusher catheter are temporarily connected to each other by the guide catheter passing through a loop formed by the string. Since the loop is located in the stent, the loop reduces a gap between the stent and the guide catheter. As a result, it may interfere with movement of the guide catheter in the stent, which may cause an increase of the force required for releasing the stent.

Based on the above circumstance, an object of the present invention is to provide a stent delivery apparatus in which a force required for releasing a stent is less likely to increase while maintaining a structure capable of pulling back the stent.

Solution to Problem

According to a first aspect of the present invention, a stent delivery apparatus includes: a guide catheter through which a guide wire is insertable; a pusher catheter having a distal end portion, a proximal end portion, and a lumen extending between the distal end portion and the proximal end portion, in which the guide catheter is inserted through the lumen; a stent disposed on a distal side with respect to a distal end of the pusher catheter by insertion of the guide catheter; and a string-shaped connection member having a loop shape and connecting the stent and the pusher catheter to each other in a releasable manner

The pusher catheter has a first communication hole communicating with the lumen on an outer peripheral surface of the distal end portion.

The stent has a distal end opening, a proximal end opening, a stent lumen that makes communication between the distal end opening and the proximal end opening, and a second communication hole provided on an outer peripheral surface on a distal end side with respect to the proximal end opening and communicating with the stent lumen. The stent is disposed such that the proximal end opening is located on the pusher catheter side.

In a state where the stent and the pusher catheter are connected to each other, the connection member has a first end portion that is supported by the pusher catheter through the first communication hole, an intermediate portion that is continued to the first end portion and extends to a space between the stent and the pusher catheter through the second communication hole, and a second end portion that is continued to the intermediate portion and extends around a part of the guide catheter located between a proximal end of the stent and the distal end portion of the pusher catheter.

According to a second aspect of the present invention, a stent delivery apparatus includes: a guide catheter through which a guide wire is insertable; a pusher catheter having a distal end portion, a proximal end portion, and a lumen extending between the distal end portion and the proximal end portion, in which the guide catheter is inserted through the lumen; a stent disposed on a distal side with respect to a distal end of the pusher catheter by insertion of the guide catheter; and a string-shaped connection member having a loop shape and connecting the stent and the pusher catheter to each other in a releasable manner.

One of the stent and the pusher catheter has a communication hole. The stent has a distal end opening, a proximal end opening, and a stent lumen that makes communication between the distal end opening and the proximal end opening. The stent is disposed such that the proximal end opening is located on the pusher catheter side.

In a state where the stent and the pusher catheter are connected to each other, the connection member has a first end portion that is supported by the other of the stent and the pusher catheter, an intermediate portion that is continued to the first end portion and extends to at least a space between the stent and the pusher catheter through the communication hole, and a second end portion that is continued to the intermediate portion and extends around a part of the guide catheter located on a hand side with respect to a proximal end of the stent.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is an overall view of a stent delivery apparatus1of the present embodiment. The stent delivery apparatus includes a stent10and a delivery catheter100.

FIG. 2is a side view of the stent10. The stent10of the present embodiment is a stent to be placed in a bile duct, and includes a tubular main body11and flaps50attached to both end portions of the main body11. The main body11has a distal end12having a distal end opening12aand a proximal end13having a proximal end opening13a,and extends along a longitudinal axis X1. A stent lumen11aextends between the distal end opening12aand the proximal end opening13aalong the longitudinal axis X1. The distal end12is an end portion that is disposed on a liver side when placed in the bile duct. The proximal end13is an end portion that is disposed on a duodenal papilla side when placed in the bile duct.

FIG. 3is a diagram showing an internal structure of the stent10. The main body11has a resin inner layer20, a metal wire rod30wound around the inner layer20, and a resin outer layer40covering the inner layer20and the wire rod30. The wire rod30is embedded between an inner peripheral surface and an outer peripheral surface of the main body11.

The inner layer20is a tube formed of a resin material such as polytetrafluoroethylene (PTFE) and perfluoroalkoxy alkane (PFA) having a smooth surface and biocompatibility.

The wire rod30is wound in a spiral shape on an outer peripheral surface of the inner layer20, and is formed in a coil shape as a whole. A material of the wire rod30is a material having X-ray impermeableness, such as tungsten steel and stainless steel.

The outer layer40is formed of a resin material such as urethane or polyethylene having elasticity, flexibility, and biocompatibility. The outer layer40is also provided in a gap between the wire rods30adjacent to each other in a direction of the longitudinal axis X1.

A hole (second communication hole)15communicating with the stent lumen11ais formed on an outer peripheral surface of one end portion of the stent10. The hole15is used for a temporary connection (described below) between the stent10and the delivery catheter100.

FIG. 4is a schematic cross-sectional view showing a structure of the stent delivery apparatus1. The delivery catheter100includes a guide catheter80and a pusher catheter90.

The guide catheter80has a tube (guide tube)81through which a guide wire can be inserted, and a traction portion85for moving the tube81.

The tube81is a tubular member made of resin and has a lumen through which a guide wire can be inserted. The tube81is flexible to such an extent that it is deformable when the tube81comes into contact with a living tissue during use of the stent delivery apparatus1. The tube81is an elastic member having a restoring force, and becomes linear due to the restoring force in a state where no external force is applied. The tube81has a small diameter portion82located on a distal end side of the stent delivery apparatus1and a large diameter portion83located on a proximal end side of the stent delivery apparatus1. A part where an outer peripheral surface of the small diameter portion82and the large diameter portion83are connected to each other is formed as a tapered intermediate portion84, and the small diameter portion82and the large diameter portion83are connected to each other without difference in level. As a result, the outer diameter of the tube81gradually increases from the small diameter portion82toward the large diameter portion83.

Outer diameters of the small diameter portion82and the large diameter portion83are smaller than an inner diameter of the stent10. Therefore, the tube81can be inserted into the stent10.

A material of the tube81is made of a fluororesin, a thermoplastic resin, or the like, and the following can be exemplified. The material of the tube81is not particularly limited as long as desired mechanical properties are satisfied.

General-purpose resins such as olefin resins such as polypropylene and polyethylene, copolymer resins thereof, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and polyvinyl alcohol (PVA).

The traction portion85includes a pipe86, a wire87, and an operation part89. The pipe86is a metal tubular member having both ends open in an axial direction. The pipe86is attached to an inside of the tube81coaxially with the tube81. The pipe86is disposed at a proximal end portion of the large diameter portion83.

As a material of the pipe86, a metal such as stainless steel and an engineering resin such as PEEK are exemplary examples, but other materials may be used as long as desired mechanical properties are satisfied.

A distal end portion of the wire87is joined to the pipe86, and a proximal end portion thereof is connected to the operation part89.

As a material of the wire87, the same material as that of the pipe86is an exemplary example. Other materials may be used as long as desired mechanical properties are satisfied.

The pusher catheter90has a single lumen tube91, a multi-lumen tube92, and a grip portion93.

The single lumen tube91is a tubular member having an inner diameter into which the large diameter portion83of the tube81can be inserted. The single lumen tube91has flexibility. A distal end surface of the single lumen tube91is a plane orthogonal to a center line of the single lumen tube91. The distal end surface of the single lumen tube91can support the stent10by abutting on a proximal end of the stent10. A size of a wall thickness of the single lumen tube91is equal to or greater than a difference between an inner radius and an outer radius of the main body11of the stent10(that is, a wall thickness of the stent10). The single lumen tube91has a length for allowing the large diameter portion83of the tube81to be completely accommodated inside the single lumen tube91.

The multi-lumen tube92is fixed to a proximal end portion of the single lumen tube91. The multi-lumen tube92has a communication passage92afor inserting a guide wire therethrough and a wire lumen92b.The wire87of the guide catheter80is inserted through the wire lumen92b.

The communication passage92ais open to a distal end of the multi-lumen tube92and is open to a side surface of the multi-lumen tube92on the proximal end side with respect to the distal end of the multi-lumen tube92.

The wire lumen92bis open to the distal end and the proximal end of the multi-lumen tube92.

The grip portion93is connected to a proximal end portion of the multi-lumen tube92. The grip portion93has a substantially cylindrical shape having a diameter larger than that of the multi-lumen tube92. Unevenness or the like for preventing slipping may be formed on an outer peripheral surface of the grip portion93.

A through-hole93acommunicating with the wire lumen92bis formed in the grip portion93. The through-hole93ais located on an extension line to the proximal end side of a center line of the multi-lumen tube92. The through-hole93amay not be on the extension line of the center line of the multi-lumen tube92.

The wire87of the guide catheter80is inserted through the through-hole93a.Thus, the wire87and the operation part89extend from the through-hole93a.

The single lumen tube91and the multi-lumen tube92can be suitably used such that the kinds of materials to be blended are the same and only a blending ratio is different. In this case, when both are welded and joined, it is easy to adjust desired bending rigidity while maintaining a joining strength.

As a resin material of the single lumen tube91and the multi-lumen tube92, the same resin as that of the tube81can be used. For example, when a relatively soft elastomer resin and a relatively hard thermoplastic resin are blended and a blending ratio of the thermoplastic resin in the multi-lumen tube92is made higher than that in the single lumen tube91, the bending rigidity of the single lumen tube91is made to be smaller than the bending rigidity of the multi-lumen tube92, and the insertability of the delivery catheter100can be enhanced.

The stent10is made to pass through the tube81projecting from the pusher catheter90. The stent10is attached to the delivery catheter100with the end portion having the hole15located on the pusher catheter90side.

FIG. 5is an enlarged schematic view showing a connection part between the stent10and the delivery catheter100.FIG. 6is a cross-sectional view taken along the line I-I ofFIG. 5. A hole (first communication hole)91acommunicating with an internal space (lumen) is provided at a distal end portion of the single lumen tube91. A thread (connection member)95is made to pass through the hole91a.Since both end portions of the thread95are tied to form a loop shape in a state where the thread passes through the hole91a,the thread is supported by the single lumen tube91and does not come off from the hole91a.

The thread95having a loop shape enters the stent lumen11athrough the proximal end opening13aof the main body11and exits the stent10from the hole15through a space between an inner surface of the stent10and an outer surface of the tube81. The thread95exiting the hole15extends between the proximal end of the stent10and a distal end portion of the pusher catheter90and is disposed around the tube81. That is, the tube81passes through the loop shape of the thread95between the stent10and the pusher catheter90.

In the state shown inFIGS. 5 and 6, the thread95does not come off from the through-hole15unless the tube81comes off from the loop of the thread95. As a result, the stent10and the delivery catheter100are temporarily connected to each other.

In a state where the stent10and the delivery catheter100are temporarily connected to each other, the loop shape formed by the thread95has, as shown inFIGS. 5 and 6, a first end portion95alocked to the hole91aand supported by the pusher catheter90, a first intermediate portion95bextending from the first end portion95ato the hole15through the stent10, a second intermediate portion95cextending from the hole15to a space between the stent10and the pusher catheter90through the outside of the stent10, and a second end portion95ddisposed around the tube81between the stent10and the pusher catheter90. The second end portion95dextends in a circumferential direction of the tube81.

In a state where the stent10and the delivery catheter100are temporarily connected to each other, when the operation part89is pushed in to advance the guide catheter80to the maximum extent, the intermediate portion84of the tube81is exposed from the stent10held by the pusher catheter90.

As a material of the thread95, nylon is an exemplary example.

Dimensional examples of each part of the delivery catheter100are shown below, but the configuration of the present embodiment is not limited to this example.

Overall length of guide catheter80: 2100 mm to 2300 mm

Length of tube81: 350 mm to 450 mm

Length of wire87: 1750 mm to 1850 mm

Overall length of pusher catheter90: 1700 mm to 1800 mm

Overall length of single lumen tube91: 480 mm to 520 mm

Overall length of multi-lumen tube92: 1220 mm to 1280 mm

The operation of the stent delivery apparatus1configured as described above during use will be described with reference to an example of a case in which the stent10is placed in the bile duct.

An operator allows the guide wire to pass through a channel of a side-viewing endoscope and inserts the guide wire into the bile duct while observing it with the endoscope. Subsequently, the operator operates the guide wire under fluoroscopy to break through a stenotic part in the bile duct, and moves a distal end portion of the guide wire to the liver side from the stenotic part.

The operator inserts a proximal end portion of the guide wire projecting from a forceps opening of the endoscope into a distal end opening of the tube81of the stent delivery apparatus1to which the stent10is attached. The guide wire enters the lumen of the single lumen tube91through the proximal end opening of the tube81. Further, the operator allows the proximal end portion of the guide wire to enter the wire lumen92aand to project from a proximal end side opening of the wire lumen92a.

The operator inserts the stent delivery apparatus1through which the guide wire is made to pass into the channel of the endoscope and allows a distal end portion of the stent delivery apparatus1to project from a distal end of the channel. The operator operates a raising base of the endoscope to direct the distal end of the stent delivery apparatus1toward the duodenal papilla and allows the stent delivery apparatus1to enter the bile duct along the guide wire. In a state where the stent10is positioned on the pusher catheter90by the thread95, a distal end portion of the large diameter portion83of the tube81projects from the distal end of the stent10. As shown inFIG. 4, since a difference between the outer diameter of the large diameter portion83and the inner diameter of the stent10is small, there is no large gap between the stent10and the tube81, and an operation for breaking through the stenotic part is easy.

When a distal end portion of the stent10breaks through the stenotic part and the flap50on the distal end side moves to the liver side from the stenotic part, the operator advances and retracts the stent delivery apparatus1to determine a placement position of the stent10. In the stent delivery apparatus1, since the stent10and the delivery catheter100are temporarily connected to each other as described above, the stent10can be pulled back by retracting the stent delivery apparatus1. Therefore, the position of the stent10can be easily adjusted.

After the placement position of the stent10is determined, the operator pulls the operation part89toward a hand side while holding the pusher catheter90. Then, the wire87and the tube81retract, but the stent10does not retract because it is in contact with the pusher catheter90. When the tube81retracts and comes off from the loop of the stent10and thread95(second end portion95d), the connection between the stent10and the delivery catheter100is released and the stent10is placed at a desired position in the bile duct.

After the placement of the stent10, as shown inFIG. 7, the flap50is placed on the liver side from a stenotic part St and near a duodenal papilla Dp outside the bile duct, so that the placement position is suitably held.

As described above, in the stent delivery apparatus1of the present embodiment, since the stent10and the delivery catheter100are temporarily connected to each other, the position of the stent10can be easily adjusted by the pull-back operation, and the stent can be placed at a desired position.

Further, in a state where the stent10and the delivery catheter100are temporarily connected to each other, the second end portion95dextending in the circumferential direction of the tube81is located between the stent10and the pusher catheter90. On the other hand, in the stent10, only a portion of the thread95extends along the longitudinal axis in the gap between the stent10and the tube81. Therefore, when the tube81is retracted with respect to the stent10, the thread95is less likely to generate a large frictional resistance.

As described above, the stent delivery apparatus1of the present embodiment realizes a structure in which an operation force required for releasing the stent is less likely to increase even when a difference between an inner diameter dimension of the stent10and an outer diameter dimension of the tube81is small.

A second embodiment of the present invention will be described with reference toFIGS. 8 and 9. In the following description, the same reference numerals will be given to the same configurations as those described above, and a duplicate description thereof will be omitted.

FIG. 8is an enlarged schematic view showing a connection part between the stent10and the delivery catheter100in a stent delivery apparatus1A of the present embodiment.FIG. 9is a cross-sectional view taken along the line II-II ofFIG. 8.

As shown inFIGS. 8 and 9, the second intermediate portion95cof the thread95extends between two threads of the first intermediate portion95b.That is, the second end portion95dpasses through the loop shape of the thread95, and a boundary portion96connecting the second intermediate portion95cand the second end portion95dis also located between the two threads of the first intermediate portion95b.

In a side view from a direction orthogonal to the longitudinal axis of the delivery catheter100, the boundary portion96is located between the proximal end of the stent10and the distal end portion of the pusher catheter90and crosses a space between the two threads of the first intermediate portion95b.

The stent delivery apparatus1A of the present embodiment also has the same effect as the stent delivery apparatus1of the first embodiment.

In addition, the boundary portion96is located between the two threads of the first intermediate portion95b,and the second intermediate portion95cis held by the first intermediate portion95b.As a result, a tension generated by pulling the first intermediate portion95bin the longitudinal direction during the pull-back operation of the stent10makes the second intermediate portion95chard to loosen when the stent10and the delivery catheter100are connected to each other.

Further, since the second intermediate portion95cis hard to loosen, it is possible to prevent a situation in which a part of the second end portion enters the stent to increase the frictional resistance.

A third embodiment of the present invention will be described with reference toFIGS. 10 to 13.

FIG. 10is an enlarged schematic view showing a connection part between the stent10and the delivery catheter100in a stent delivery apparatus1B of the present embodiment.FIG. 11is a cross-sectional view taken along the line III-III ofFIG. 10, in which the thread95is slightly slackened in order to facilitate understanding of the disposition of the thread.

The single lumen tube91of the pusher catheter90has a hole91bcommunicating with the lumen on the proximal end side with respect to the hole91a.The second intermediate portion95cof the thread95extends from the hole15of the stent10to the hole91b.The thread95enters the inside of the single lumen tube91through the hole91band is disposed around the tube81. That is, the second end portion95dof the present embodiment is located in the pusher catheter90.

In the stent delivery apparatus1B of the present embodiment, an inner diameter of the pusher catheter90is larger than the inner diameter of the stent10. Therefore, in a case where the second end portion95dis disposed in the pusher catheter90, a frictional resistance is less likely to occur than in a case where the second end portion95dis disposed in the stent10. Therefore, the stent delivery apparatus1B of the present embodiment also has the same effect as the stent delivery apparatus1of the first embodiment.

FIG. 12is an enlarged schematic view showing a connection part between the stent10and the delivery catheter100in a modification example of the stent delivery apparatus1B.FIG. 13is a cross-sectional view taken along the line IV-IV ofFIG. 12, in which the thread is slightly slackened as inFIG. 11.

In the modification example, the first end portion95aof the thread95is located in the hole91b.According to this, the first intermediate portion95bextends from the hole91bto the hole15of the stent10. The second intermediate portion95cextends from the hole15to the hole91a.The thread95enters the inside of the single lumen tube91through the hole91aand is disposed around the tube81. Also in the modification example, since the second end portion95dis located in the pusher catheter90, the same effect as that of the stent delivery apparatus1B is obtained.

As described above, the present invention is characterized in that the second end portion95dextending in the circumferential direction of the tube81is not disposed in the stent10.

Although each embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the above-described embodiment, and it is possible to change the combination of components, to make various modifications to the components, and to delete the components without departing from the spirit of the present invention.

Hereinafter, some modifications are shown as examples, but the present invention is not limited thereto, and other modifications may be made.

In the first embodiment and the second embodiment, a positional relationship between the first communication hole and the second communication hole may be reversed. That is, the second communication hole may be provided in the pusher catheter and the first communication hole may be provided in the stent.

In this case, while the first end portion of the connection member is disposed in the stent and placed in the body, the connection member is located in the duodenum. Therefore, the stent can be extracted from the bile duct by pulling the connection member.

A method of forming the connection member into a loop shape is not limited to a method of connecting the end portions, and another method such as joining the end portions by welding or adhesion may be used.

The first end portion passed through the first communication hole may be fixed to an outer or inner surface of the pusher catheter or the stent. Further, the first end portion of the connection member does not necessarily have to pass through the first communication hole. For example, the first end portion may be fixed directly to the outer or inner surface of the pusher catheter or the stent. In this case, it is natural that the first communication hole may not be provided.

The flap of the stent is not limited to the aspect in which a separate member is attached to the main body as in the above example. For example, the flap may be formed by making a notch in the main body and bending a part of the main body. In this case, when the notch is made to reach the stent lumen, a communication hole is formed along with the formation of the flap. Therefore, the communication hole may be used as the first communication hole or the second communication hole.

In a case where the first communication hole is provided in the stent, the loop-shaped connection member may be configured to pass through the outside of the pusher catheter and enter the pusher catheter through the second communication hole. In this case, while the connection member does not have the first intermediate portion and the second intermediate portion, the second end portion is located in the pusher catheter. Therefore, an effect that the operation force required for releasing the stent is less likely to increase is obtained.

The stent in the present invention is not limited to the aspect in which the above-described structure is provided. That is, the stent in the present invention may be a so-called pigtail type stent in which at least one end portion is rounded in a loop shape by coming-off of the tube81, and it is not essential to include the flap50.