JP7487527B2 - Endoscopic Catheters - Google Patents

Description

The present invention relates to an endoscopic catheter used to remove a self-expanding stent placed in the body.

In recent years, endoscopic ultrasound-guided biliary drainage (EUS-BD) has been attracting attention as a treatment technique for biliary stricture or obstruction. EUS-BD is performed when treatment such as resection of the biliary stricture or obstruction site is not possible and a transduodenal papilla approach is also difficult. Compared to percutaneous transhepatic biliary drainage, which creates an external fistula, EUS-BD has the advantage of not reducing the patient's quality of life (QOL).

Specifically, EUS-BD is a procedure in which an ultrasound endoscope is inserted into the stomach or duodenum, and while observing ultrasound images in real time, a puncture needle is used to puncture the bile duct or gallbladder through the stomach or duodenal wall, a guidewire is inserted into the bile duct or gallbladder, and a stent is inserted and placed to bypass and connect a hollow organ (e.g., the digestive tract, such as the stomach or duodenum) to another hollow organ (e.g., the bile duct or gallbladder). This procedure makes it possible to perform biliary drainage by implanting a stent inside the body.

For example, the following Patent Document 1 describes a self-expanding covered stent that uses a superelastic material (or shape memory material) such as nickel-titanium (Ni-Ti) alloy as the material for the frame, and when a compressive force is applied in the radial direction, it contracts in the radial direction due to elasticity, and when the compressive force is released, it expands in the radial direction.

Stents placed in the body to bypass luminal organs cause adhesions between the bypassed luminal organs and fistulas due to fibrotic tissue over time. After adhesions between luminal organs and fistulas due to fibrotic tissue are formed, the stent is no longer necessary and may instead cause clogging of fistulas, etc., so removal of the stent may be desired. Endoscopic treatment tools used to remove self-expanding stents placed in the digestive system, including stents for bypassing luminal organs, include endoscopic snares and endoscopic forceps, and an endoscopic snare, for example, is known, as described in Patent Document 2 below.

International Publication No. WO2019/230413 JP 2017-192596 A

However, self-expanding stents are often biased against the surrounding luminal organ walls and fistula walls by their own expansion force, and are therefore left in a firmly fixed state. A stent that is firmly fixed in this way cannot be easily removed, for example, by capturing it with a snare, and there is a risk of damaging the luminal organ walls and fistula walls around the stent if it is pulled out with excessive force.

The present invention was made in consideration of the above problems, and aims to provide an endoscopic catheter that allows for smooth and safe removal of a self-expanding stent placed in the body.

In order to achieve the above object, an endoscopic catheter according to the present invention is an endoscopic catheter used for removing a self-expanding stent placed in a body, comprising:
a catheter tube that can be inserted into a channel of an endoscope;
a snare wire that is exposed distally from the distal end of the catheter tube and expands in diameter to form a loop for capturing the stent;
a cooling water catheter that discharges cooling water introduced through a proximal end of the catheter tube from a distal end disposed distal to the distal end of the catheter tube toward the stent;
The present invention is characterized by having the following:

According to this configuration, when removing a self-expanding stent, the stent can be cooled by releasing cooling water from the distal end of the cooling water catheter toward the stent. Self-expanding stents are generally made of a superelastic material (or shape memory material) such as a nickel-titanium (Ni-Ti) alloy, and have the property that when cooled to a temperature lower than the transformation point, the self-expanding force that expands radially is significantly weakened. Therefore, by cooling the stent, the self-expanding force of the stent can be reduced, and the biasing force on the surrounding luminal organ walls and fistula walls can be reduced, allowing the stent to be removed smoothly and safely.

Furthermore, the catheter for an endoscope according to the present invention may be configured such that the cooling water catheter is inserted so as to be able to advance and retreat through a cooling water catheter lumen formed along the axial direction within the catheter tube.

With this configuration, the distal end of the cooling water catheter can be advanced distally to approach the stent, and can even be inserted into the lumen of the stent. This ensures that cooling water can be reliably discharged from the distal end of the cooling water catheter toward the stent, thereby ensuring that the stent is cooled.

Furthermore, the endoscopic catheter according to the present invention may be configured such that, when the snare wire is exposed distally from the distal end of the catheter tube and expanded in diameter, an extension line extending the axis of the cooling water catheter lumen distally passes through the inside of the loop of the snare wire.

This configuration allows the cooling water catheter to be passed inside the loop of the snare wire, which has been expanded distally from the distal end of the catheter tube. In this way, with the cooling water catheter passed inside the loop of the snare wire, the distal end of the cooling water catheter can be advanced distally to approach the stent and then inserted into the lumen of the stent, allowing the loop to be positioned relative to the stent using the cooling water catheter as a guide, and the stent can be easily captured by the loop of the snare wire.

Furthermore, the endoscopic catheter according to the present invention has an operating wire that is inserted so as to be able to advance and retreat through a snare lumen formed in the catheter tube along the axial direction, and that is connected at its distal end to a proximal end of the snare wire,
At the distal end of the snare lumen through which the distal end of the operating wire advances and retreats, the cross-sectional shape of the distal end of the operating wire and the cross-sectional shape of the distal end of the snare lumen may be set so as to regulate rotation of the operating wire about the axial direction as the axis of rotation.

This configuration prevents the position of the snare wire loop, which is expanded distally of the distal end of the catheter tube, from shifting due to rotation of the control wire, and makes it possible to maintain a position that allows the cooling water catheter to pass inside the loop.

Furthermore, in the endoscopic catheter according to the present invention, the cross-sectional shape of the distal end of the control wire and the cross-sectional shape of the distal end of the snare lumen may be elliptical.

This configuration makes it possible to easily shape the cross-sectional shape of the distal end of the control wire and the cross-sectional shape of the distal end of the snare lumen, thereby restricting the rotation of the control wire around the axial direction as the axis of rotation.

Furthermore, in the endoscopic catheter according to the present invention, the temperature of the cooling water may be lower than the transformation point at which the material constituting the stent loses its shape recovery.

With this configuration, the stent can be cooled to a temperature lower than the transformation point at which the material that constitutes the stent loses its shape recovery, making it possible to reliably reduce the self-expansion force of the stent.

1 is an overall view of an endoscopic catheter according to an embodiment of the present invention. 2 is a partially enlarged view showing a configuration in the vicinity of a distal end of an endoscopic catheter according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the vicinity of the distal end of the endoscopic catheter shown in FIG. 2. FIG. 2 is a partially enlarged view of the snare wire and its periphery in the state in which the snare wire is positioned most distally in the endoscopic snare used in the embodiment of the present invention, as viewed in a direction perpendicular to the axial direction and the radial expansion direction of the catheter tube. 5 is a partially enlarged view of the snare wire periphery shown in FIG. 4 as viewed from the radially expanding direction. 1A and 1B are diagrams showing a state in which a connection portion begins to be exposed from a snare lumen and the snare wire is completely expanded distally of the distal end of a catheter tube in an endoscopic snare used in an embodiment of the present invention, in which (a) is a partially enlarged oblique view of the periphery of the distal end of the catheter tube, and (b) is a cross-sectional view of the vicinity of the opening of the snare lumen shown in (a). 1A and 1B are diagrams showing a state in which, in an endoscopic snare used in an embodiment of the present invention, the snare wire is positioned at the most distal side and is completely expanded in diameter distal to the distal end of the catheter tube, in which (a) is a partially enlarged oblique view of the periphery of the distal end of the catheter tube, and (b) is a cross-sectional view of the vicinity of the opening of the snare lumen shown in (a). 1A to 1C are diagrams showing the state after a first procedure for removing a self-expanding stent using an endoscopic catheter according to this embodiment. 13A and 13B are diagrams showing the state after a second procedure for removing a self-expanding stent using the endoscopic catheter of this embodiment. 13A to 13C are diagrams showing the state after a third procedure for removing a self-expanding stent using an endoscopic catheter according to this embodiment. 13A to 13C are diagrams showing the state after a fourth procedure for removing a self-expanding stent using an endoscopic catheter according to this embodiment. 13A to 13C are diagrams showing the state after a fifth procedure for removing a self-expanding stent using an endoscopic catheter according to this embodiment.

Below, an embodiment of the present invention will be described with reference to the drawings. In this specification, the inside of the patient's body is defined as the distal side, and the side closest to the surgeon is defined as the proximal side, based on the surgeon.

First, the configuration of an endoscopic catheter 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is an overall view of an endoscopic catheter according to an embodiment of the present invention. Figure 2 is a partially enlarged view showing the configuration near the distal end of an endoscopic catheter 100 according to an embodiment of the present invention. Figure 3 is a cross-sectional view of the vicinity of the distal end of the endoscopic catheter 100 shown in Figure 2.

The endoscopic catheter 100 in this embodiment is composed of a catheter tube 1 that can be inserted into the channel of an endoscope, an endoscopic snare 10 equipped with a snare wire 40 used to capture a stent, and a cooling water catheter 5 for supplying cooling water.

The catheter tube 1 is made of a flexible tube that can be inserted into the channel of an endoscope. The outer diameter of the catheter tube 1 is set to a dimension that allows it to be inserted into the channel of an endoscope. The material of the catheter tube 1 is not particularly limited as long as it is flexible, and for example, a polymeric material such as polyamide resin or polyamide-based elastomer can be used.

As shown in FIG. 3, the catheter tube 1 has two lumens formed along the axial direction: a snare lumen 1b through which the operating wire 30 of the endoscopic snare 10 is inserted, and a cooling water catheter lumen 1c through which the cooling water catheter 5 is inserted. The snare lumen 1b and the cooling water catheter lumen 1c are formed, for example, at positions where the axial center of the snare lumen 1b and the axial center of the cooling water catheter lumen 1c are arranged on a straight line with the axial center of the catheter tube 1 in between.

The operating wire 30 of the endoscopic snare 10 is inserted through the snare lumen 1b so that it can advance and retreat along the axial direction, and the snare wire 40 expands in diameter on the distal side of the distal end 1a of the catheter tube 1. As will be described in detail later, the cross-sectional shape of the distal end of the snare lumen 1b is a shape that restricts the rotation of the operating wire 30 about the axial direction as the axis of rotation, and is formed, for example, in an elliptical shape. In addition, at the distal end 1a of the tube, the elliptical opening of the snare lumen 1b is arranged so that its major axis direction (long diameter) is perpendicular to the radial direction of the catheter tube 1.

The cooling water catheter 5 is inserted into the cooling water catheter lumen 1c so that it can advance and retreat along the axial direction. When the cooling water catheter 5 is advanced and retreated within the cooling water catheter lumen 1c, the cooling water catheter distal end 5a, which is the distal end of the cooling water catheter 5, can be moved in the axial direction (the direction of the arrow S shown in Figure 2), and the cooling water catheter 5 can be stored within the cooling water catheter lumen 1c and the cooling water catheter distal end 5a can be advanced to the distal side of the catheter tube 1.

A side hole 1e is provided on the proximal side of the catheter tube 1, which leads from the outer peripheral surface of the catheter tube 1 to the cooling water catheter lumen 1c, and the cooling water catheter 5 can be inserted into the cooling water catheter lumen 1c through this side hole 1e. However, the structure for inserting the cooling water catheter 5 into the cooling water catheter lumen 1c is not limited to this.

The proximal end of the cooling water catheter 5 is provided with a connector 1f to which an instrument for injecting cooling water (e.g., a syringe, etc.) can be connected. The cooling water introduced from the proximal end of the cooling water catheter 5 flows through the cooling water catheter 5 and is discharged from the distal end 5a of the cooling water catheter.

The cooling water is discharged from the cooling water catheter 5 in order to facilitate the removal of the self-expanding stent. The self-expanding stent is made of a superelastic material (or shape memory material) such as a nickel-titanium (Ni-Ti) alloy. The composition of the superelastic material used as the material for the self-expanding stent is adjusted to have a transformation point (shape memory temperature) that is slightly lower than body temperature. On the other hand, such superelastic materials are characterized in that a phase transformation occurs at a certain temperature (transformation point), causing a significant change in the internal structure, and when cooled to a temperature lower than the transformation point, the shape recovery is greatly reduced. In other words, a self-expanding stent has the self-expanding force to expand radially near body temperature, but loses its self-expanding force when cooled to a temperature lower than the transformation point.

The present invention focuses on this feature and reduces the self-expansion force of the stent by releasing cooling water to cool the stent, thereby reducing the biasing force of the stent against the surrounding luminal organ walls and fistula walls, allowing the stent to be removed smoothly and safely. It is known that the transformation point at which phase transformation occurs depends on the composition of the superelastic material, and many of the superelastic materials used as materials for self-expanding stents have transformation points in the range of 10 to 30°C, for example. Therefore, by cooling the stent with cooling water cooled to near 0°C, the self-expansion force of the stent can be reliably reduced.

The outer diameter of the cooling water catheter 5 can be set to a dimension that allows it to be inserted into the lumen of the stent to be removed. For example, the inner diameter of the stent when expanded is about 5 to 20 mm, and it is preferable to set the outer diameter of the cooling water catheter 5 smaller than this. If the distal end of the cooling water catheter 5 can be inserted into the lumen of the stent, cooling water can be released with the distal end of the cooling water catheter 5 inserted into the lumen of the stent when the stent is removed, and the stent can be cooled reliably. There are no particular limitations on the material of the cooling water catheter 5 as long as it is flexible, and for example, a polymeric material such as polyamide resin or polyamide-based elastomer can be used.

The endoscopic snare 10 has an operating wire 30 consisting of a flexible wire 30c and a connection portion 30d, a snare wire 40 connected to the connection portion 30d, and an operating portion 50 to which the operating wire proximal end 30a, which is the proximal end of the operating wire 30, is connected.

The endoscopic snare 10 can be used as a treatment tool to capture an object, such as a stent placed in a tubular organ such as the bile duct, by constricting it with a loop 40a (a closed curve whose starting point and ending point are coincident) formed by the snare wire 40, and then to remove it from the body.

The operation wire 30 is composed of a flexible wire 30c which constitutes the majority of the operation wire 30, and a connection part 30d which is connected to the distal end of the flexible wire 30c, and is inserted into the snare lumen 1b of the catheter tube 1. The flexible wire 30c is composed of a torque wire made of a twisted wire made of thin metal wires such as stainless steel. However, the material and structure of the operation wire 30 are not limited to this, and may be, for example, a single metal wire or a resin wire.

The size of the flexible wire 30c is not particularly limited, but for example, the flexible wire 30c can have a total length of 1500 to 2500 mm and an outer diameter of about 0.2 to 1.0 mm. The outer diameter of the flexible wire 30c is smaller than the inner diameter of the snare lumen 1b, and the flexible wire 30c can advance and retreat within the snare lumen 1b along an insertion direction that coincides with the axial direction of the snare lumen 1b. The total length of the flexible wire 30c is preferably set to be approximately the same as the total length of the catheter tube 1 or slightly longer than the catheter tube 1, but is not particularly limited. As will be described in detail later, the cross-sectional shape of the distal end of the operating wire 30 is shaped to restrict the rotation of the operating wire 30 around the axial direction as the axis of rotation, and is formed, for example, in an elliptical shape.

The operating section 50 has a tube fixing section 52 and a sliding section 56. The proximal end 1d of the catheter tube 1 is fixed to the tube fixing section 52. A through hole (not shown) is formed inside the tube fixing section 52, and the operating wire 30 inserted into the snare lumen 1b passes through the through hole of the tube fixing section 52 and extends further proximally.

The proximal end 30a of the operation wire 30 (proximal end of the flexible wire 30c) is fixed to the slide portion 56. The slide portion 56 is engaged with the tube fixing portion 52 in a state in which it can move relative to the insertion direction of the operation wire 30 inserted into the snare lumen 1b. Therefore, when the slide portion 56 is slid in the insertion direction relative to the tube fixing portion 52, the operation wire 30 connected to the slide portion 56 can advance and retreat in the insertion direction relative to the catheter tube 1 fixed to the tube fixing portion 52. In other words, when the slide portion 56 is moved proximally, the operation wire 30 moves proximally along the insertion direction in the snare lumen 1b, while when the slide portion 56 is moved distally, the operation wire 30 can move distally along the insertion direction in the snare lumen 1b.

With this configuration, in the endoscopic snare 10, by sliding the slide portion 56 distally and proximally, the snare wire 40 connected to the connection portion 30d at the distal end of the operating wire 30 can be exposed from the distal end 1a of the catheter tube 1, which is the distal end of the catheter tube 1, or the snare wire 40 can be stored inside the catheter tube 1 (inside the snare lumen 1b).

A connection part 30d is provided at the distal end of the operating wire 30. The connection part 30d is, for example, a metal pipe. The distal end of the flexible wire 30c is connected to the proximal end of the connection part 30d, and the end of the wire that constitutes the snare wire 40 is connected to the distal end of the connection part 30d. Note that the method of connecting the flexible wire 30c to the connection part 30d and the method of connecting the connection part 30d to the snare wire 40 can be, for example, brazing, welding, adhesive, or the like, but is not particularly limited.

The snare wire 40 is made of a wire material such as a metal wire having a substantially circular cross-sectional shape. The snare wire 40 is a member in which the wire material is curved or bent to adjust its shape, and both ends of the wire material are fixed to the distal end of the connection part 30d to form a loop 40a. The material of the snare wire 40 can be, for example, a metal such as stainless steel or a nickel-titanium alloy, or a resin, but is not particularly limited. The wire material that is the material of the snare wire 40 may be a solid wire or a twisted wire. The diameter of the wire material that constitutes the snare wire 40 is not particularly limited, but can be, for example, 0.2 to 0.5 mm.

Figure 4 is a partial enlarged view of the snare wire 40 and its periphery in the endoscopic snare 10 shown in Figure 1, viewed from a direction perpendicular to the axial direction of the catheter tube 1 and the radial expansion direction 80, and Figure 5 is a partial enlarged view of the snare wire 40 and its periphery in Figure 4, viewed from the radial expansion direction 80. Figures 4 and 5 show the snare wire 40 positioned at the most distal side, exposed from the snare lumen 1b, and expanded in diameter.

As shown in FIG. 4, the snare wire 40 forms a loop 40a. When the snare wire 40 is exposed from the snare lumen 1b of the catheter tube 1, it expands in a radial expansion direction 80 perpendicular to the axial direction of the catheter tube 1.

The wires constituting the snare wire 40 are connected to the connection section 30d at the snare wire proximal end 40c. On the distal side of the connection section 30d, an expanded diameter section 43 is formed, which is curved in an arc shape so that the opposing wires are convex outward in the expanding direction 80. More specifically, the expanded diameter section 43 expands so that the distance between the opposing wires gradually increases as it moves away from the snare wire proximal end 40c distally. Furthermore, distal to the position where the distance between the opposing wires is maximum, the distance between the opposing wires gradually decreases until it reaches the bent section 44 that connects to the distal end curved section 45.

Distal end curved portion 45 is formed distal to bend 44, protruding distally from the curved shape defined by enlarged diameter portion 43. Distal end curved portion 45 is connected to the opposing wire of enlarged diameter portion 43 at bend 44. In this embodiment, the wire constituting snare wire 40 is shaped as described above to form loop 40a, but the shape of loop 40a formed by snare wire 40 is not limited to this.

It is preferable that the size of the loop 40a formed by the snare wire 40 is sufficiently larger than the outer diameter of the stent to be removed. For example, the distance between the wires that expands the most during expansion (the distance at which opposing wires are farthest apart in the expansion direction 80) can be 10 to 50 mm.

In this embodiment, as shown in FIG. 5, the wire that constitutes the expanded diameter section 43 and the distal curved section 45 is contained within the same plane. Therefore, the surface of the loop 40a formed by the snare wire 40 when expanded (hereinafter referred to as the loop surface) is flat. Also, in this embodiment, the overall shape of the loop 40a is symmetrical with respect to a line perpendicular to the expanding direction 80.

As shown in FIG. 5, the snare wire 40 is connected to the connecting part 30d at the snare wire proximal end 40c such that the loop 40a formed by the snare wire 40 when expanded is inclined with respect to the axial direction of the connecting part 30d when viewed from the expanding direction 80. That is, an imaginary line passing through the snare wire proximal end 40c and the loop surface of the snare wire 40 is not parallel to the axis of the connecting part 30d, and the inclination angle θ between the imaginary line and the axis of the connecting part 30d is set to a predetermined value other than zero. As shown in FIG. 2, this inclination angle θ is set to an angle that allows the cooling water catheter 5 to pass inside the loop 40a of the snare wire 40. Although it varies depending on the size of the loop 40a, the inclination angle θ is set to a range of, for example, 30° to 90°.

Furthermore, the loop 40a of the snare wire 40, which expands at a predetermined inclination angle θ, is set to always expand at a constant inclination in a fixed direction at the distal end 1a of the catheter tube 1. The configuration for achieving this will be described with reference to Figures 6 and 7.

In this embodiment, the cross-sectional shape of the opening of the snare lumen 1b is elliptical. Furthermore, the cross-sectional shape of the connection portion 30d is also elliptical like the opening of the snare lumen 1b. In this embodiment, the opening of the snare lumen 1b is elliptical, but it is sufficient that the snare lumen 1b is elliptical in a part of the distal end of the snare lumen 1b (the position where the connection portion 30d and the distal end of the flexible wire 30c pass through). For example, the opening of the snare lumen 1b may be substantially circular, and the cross-sectional shape of the snare lumen 1b located behind the opening may be elliptical. In addition, the cross-sectional shape of the snare lumen 1b may be elliptical over the entire axial direction of the catheter tube 1.

When the sliding portion 56 shown in FIG. 1 is slid to the most proximal side within the sliding range and the operating wire 30 is moved relative to the catheter tube 1 to the most proximal side, the entire snare wire 40 is pulled into the snare lumen 1b. When the sliding portion 56 shown in FIG. 1 is slid distally from this state, the operating wire 30 is pushed out in the axial direction, and the distal side of the expanded portion 43 of the snare wire 40 is gradually exposed from the snare lumen 1b. When the connection portion 30d begins to be exposed from the snare lumen 1b, the snare wire 40 is in a completely expanded state on the distal side of the tube distal end 1a. At this time, the loop surface of the snare wire 40 is parallel to the major axis direction (major axis) of the elliptical opening of the snare lumen 1b, and further, the loop surface of the snare wire 40 is inclined at a predetermined inclination angle θ with respect to the axis of the connection portion 30d.

At the distal end 1a of the tube, the elliptical opening of the snare lumen 1b is arranged so that its long axis direction (long diameter) is perpendicular to the radial direction of the catheter tube 1. As a result, the loop surface of the snare wire 40 is formed so as to be parallel to the long axis direction of the elliptical opening of the snare lumen 1b, and the diameter can be expanded in a well-balanced manner on the distal side of the distal end 1a of the tube. In addition, as described above, the loop surface is set to be inclined at an inclination angle θ with respect to the axial direction of the connection part 30d. As a result, as shown in FIG. 2, the loop 40a of the snare wire 40 is formed at a position where the extension line L, which extends the axis of the cooling water catheter lumen 1c and the axis of the cooling water catheter 5 to the distal side, passes through the inside of the loop 40a.

Figures 6(a) and 6(b) show the state in which the connection portion 30d begins to be exposed from the snare lumen 1b and the snare wire 40 is completely expanded on the distal side of the tube distal end 1a. Figure 6(a) is a partially enlarged view of the area around the tube distal end 1a viewed obliquely, and Figure 6(b) is a cross-sectional view of the vicinity of the opening of the snare lumen 1b shown in Figure 6(a).

In this embodiment, as shown in FIG. 6(a) and FIG. 6(b), the cross-sectional shape of the opening of the snare lumen 1b is formed into an ellipse. Similarly to the cross-sectional shape of the opening of the snare lumen 1b, the cross-sectional shape of the connection portion 30d is also formed into an ellipse.

The long diameter D3 of the cross section of the connection part 30d is set smaller than the long diameter D1 of the opening of the snare lumen 1b, and the short diameter D4 of the cross section of the connection part 30d is set smaller than the short diameter D2 of the opening of the snare lumen 1b. This allows the connection part 30d to pass through the opening of the snare lumen 1b at the distal end 1a of the tube.

The cross-sectional major axis D3 of the connection part 30d is set to be sufficiently larger than the minor axis D2 of the opening of the snare lumen 1b. As a result, even if the connection part 30d is rotated in a direction around the axial direction, i.e., in the direction of the arrow R1 in FIG. 6(b), the outer peripheral surface of the connection part 30d abuts against the inner peripheral surface of the snare lumen 1b, restricting the rotation of the connection part 30d. As a result, the loop surface of the snare wire 40 is maintained in a state substantially parallel to the major axis direction of the elliptical opening of the snare lumen 1b.

7(a) and 7(b) show the snare wire 40 positioned at the most distal side, and the snare wire 40 fully expanded at the distal side of the tube distal end 1a. FIG. 7(a) is a partially enlarged view of the periphery of the tube distal end 1a viewed obliquely, and FIG. 7(b) is a cross-sectional view of the vicinity of the opening of the snare lumen 1b shown in FIG. 7(a). The states shown in FIG. 7(a) and 7(b) are the states in which the sliding portion 56 shown in FIG. 1 has been slid to the most distal side within the sliding range, and the operating wire 30 has been moved relative to the catheter tube 1 to the most distal side.

In this embodiment, as shown in Figures 7(a) and 7(b), when the snare wire 40 is positioned at the most distal side, the connection portion 30d is completely exposed from the snare lumen 1b, and the flexible wire 30c located proximal to the connection portion 30d is also exposed from the snare lumen 1b. As shown in Figures 7(a) and 7(b), the cross-sectional shape of the flexible wire 30c is also formed into an ellipse, similar to the cross-sectional shape of the connection portion 30d.

The long diameter D5 of the cross section of the flexible wire 30c is set to be smaller than the long diameter D1 of the opening of the snare lumen 1b. The short diameter D2 of the cross section of the flexible wire 30c is set to be smaller than the short diameter D2 of the opening of the snare lumen 1b. This allows the flexible wire 30c to pass through the opening of the snare lumen 1b at the distal end 1a of the tube.

The cross-sectional major axis D5 of the flexible wire 30c is set to be sufficiently larger than the minor axis D2 of the opening of the snare lumen 1b. As a result, even if the flexible wire 30c is rotated in a direction about the axial direction, i.e., in the direction of the arrow R2 in FIG. 7(b), the outer peripheral surface of the flexible wire 30c abuts against the inner peripheral surface of the snare lumen 1b, restricting the rotation of the flexible wire 30c. As a result, the loop surface of the snare wire 40 is maintained in a state substantially parallel to the major axis direction of the elliptical opening of the snare lumen 1b.

In this embodiment, when the sliding portion 56 is slid to the distal end, a portion of the flexible wire 30c located proximal to the connection portion 30d passes through the opening of the snare lumen 1b and is exposed. However, the flexible wire 30c may be prevented from being exposed from the opening of the snare lumen 1b by, for example, lengthening the axial dimension of the connection portion 30d. In this case, it is only necessary to form the cross-sectional shape of the connection portion 30d into an ellipse, and a flexible wire 30c having any cross-sectional shape can be used.

As described above, in the catheter tube 1 of this embodiment, the cross-sectional shape of the distal end of the operation wire 30 and the cross-sectional shape of the distal end of the snare lumen 1b are elliptical, so that it is possible to regulate the rotation of the operation wire 30 about the axial direction as the axis of rotation. As a result, it is possible to prevent the loop surface of the snare wire 40 from fluctuating due to the rotation of the operation wire 30, and to maintain the loop surface at the distal end 1a of the catheter tube 1 always facing the same direction.

In this embodiment, the cross-sectional shape of the opening of the snare lumen 1b and the cross-sectional shape of the distal end of the operating wire 30 are elliptical because they are easy to manufacture and process, but this is not limited to this, and any shape that can regulate the rotation of the operating wire 30 about the axial direction as the rotation axis may be adopted. Note that "elliptical" in this specification includes not only a mathematically defined elliptical shape, but also a shape that smoothly surrounds the periphery of two approximately circular wires arranged in the same axial direction, such as a shape close to a rounded rectangle.

Below, an example of a procedure for removing the self-expanding stent 110 using the endoscopic catheter 100 of this embodiment will be described with reference to Figures 8 to 12. However, the following procedure is merely an example, and the procedure for removing the self-expanding stent 110 using the endoscopic catheter 100 of this embodiment is not limited to this.

The endoscopic catheter 100 in this embodiment is used to remove a self-expanding stent 110 placed in the body to create a bypass connection between luminal organs. For example, a self-expanding stent 110 that creates a bypass connection between the stomach and the intrahepatic bile duct is placed so as to penetrate the stomach wall 111 and the intrahepatic bile duct wall 112, and both ends of the stent 110 are positioned so as to protrude into the stomach and the intrahepatic bile duct, respectively. The placed self-expanding stent 110 is biased to expand the puncture hole by its self-expanding force that expands radially, which makes it less likely to fall out of the placement position.

When removing the stent 110 placed in this manner, first, the endoscope is inserted into the stomach, and then the distal end of the endoscopic catheter 100, with the snare wire 40 in a contracted state and housed in the snare lumen 1b and the cooling water catheter 5 housed in the cooling water catheter lumen 1c, is inserted into the endoscope channel and pushed forward. After the distal end of the endoscopic catheter 100 exits the endoscope channel distal end 120, it is pushed forward further to position the distal end of the endoscopic catheter 100 near the stent 110 to be removed (see FIG. 8).

Next, the sliding portion 56 of the endoscopic snare 10 is slid distally to expose the snare wire 40 to the distal side of the tube distal end 1a and expand the diameter. The snare wire 40 expands in diameter so that the loop surface covers the distal side of the tube distal end 1a (see FIG. 9).

Next, while checking the image captured by the endoscope camera (not shown), the cooling water catheter 5 is pushed distally, and the cooling water catheter distal end 5a is advanced distally of the tube distal end 1a, and brought close to the stent 110 (see FIG. 10). At this time, the cooling water catheter 5 is passed inside the loop 40a of the snare wire 40, which is expanding distally of the tube distal end 1a. The cooling water catheter 5 is further pushed distally, and the cooling water catheter distal end 5a is inserted into the lumen of the stent 110.

With the distal end 5a of the cooling water catheter inserted into the lumen of the stent 110, the slide portion 56 of the endoscopic snare 10 is slid distally to advance the snare wire 40 toward the stent 110. The cooling water catheter 5 is inserted inside the loop 40a of the snare wire 40. Furthermore, the cooling water catheter 5 is inserted into the lumen of the stent 110. With this arrangement, the snare wire 40 advances toward the stent 110 by simply pushing the snare wire 40 distally, and the loop 40a can be easily positioned relative to the stent 110. That is, the cooling water catheter 5 inserted inside the loop 40a serves as a guide, and the snare wire 40 advances toward the stent 110 with the cooling water catheter 5 inserted inside the loop 40a, and the end of the stent 110 can be passed inside the loop 40a (see FIG. 11).

After the loop 40a is hooked on the end of the stent 110 (e.g., the flange at the end of the stent), cooling water cooled to nearly 0°C is released from the distal end of the cooling water catheter 5 to cool the stent 110. Then, the slide portion 56 of the endoscopic snare 10 is slid proximally to pull the stent 110 proximally with the snare wire 40 (see FIG. 12), and the slide portion 56 of the endoscopic snare 10 is further slid proximally to gradually pull the snare wire 40 into the snare lumen 1b and squeeze it, thereby strangulating the stent 110 cooled by the snare wire 40. Note that during the above-mentioned series of procedures, the positions and attitudes of the components constituting the endoscopic catheter 100 may be appropriately controlled, for example, by appropriately changing the positions and attitudes of the catheter tube 1 and the cooling water catheter 5.

When the self-expanding stent 110 is cooled, its self-expanding force is greatly reduced, and even if the stent 110 is deformed, it maintains the deformed shape without recovering its shape. Therefore, by constricting the cooled stent 110 with the snare wire 40, the stent 110 can be easily deformed into a shape that is easy to remove, for example by crushing or bending the stent 110. Furthermore, even if the stent 110 has a hook or other engaging portion for preventing migration, if the engaging portion is made of a superelastic material similar to the stent 110, the engaging portion can be easily deformed by cooling, and the stent 110 can be made into a state that is easy to remove.

Furthermore, while the stent 110 is still being constricted by the snare wire 40, cooling water is released to cool the stent 110 while the endoscopic catheter 100 is moved proximally, allowing the stent 110 to be smoothly and safely removed from its placement position.

After the cooled stent 110 is removed from its placement position, the endoscopic catheter 100 is pulled out of the body through the endoscope channel while the stent 110 is still clamped by the snare wire 40, or the entire endoscope is pulled out of the body, allowing the removed stent 110 to be removed from the body.

The following describes the effects of the present invention.

The endoscopic catheter 100 according to the present invention is used to remove a self-expanding stent 110 placed in the body, and includes a catheter tube 1 that can be inserted into an endoscope channel, a snare wire 40 that is exposed distal to the distal end 1a of the catheter tube 1 and expands in diameter to form a loop 40a for capturing the stent 110, and a cooling water catheter 5 that discharges cooling water introduced through the proximal end from the distal end 5a of the cooling water catheter 5a located distal to the distal end 1a of the catheter tube 1 toward the stent 110.

With this configuration, when removing the self-expanding stent 110, the stent 110 can be cooled by releasing cooling water from the distal end 5a of the cooling water catheter toward the stent 110. By cooling the stent 110, the self-expanding force of the stent 110 can be reduced, and the biasing force on the surrounding luminal organ walls and fistula walls can be reduced, allowing the stent 110 to be removed smoothly and safely.

Furthermore, in the endoscopic catheter 100 according to the present invention, the cooling water catheter 5 may be inserted so as to be able to advance and retreat through the cooling water catheter lumen 1c formed along the axial direction within the catheter tube 1.

With this configuration, the cooling water catheter distal end 5a can be advanced distally to approach the stent 110, and can even be inserted into the lumen of the stent 110. This allows the cooling water to be reliably discharged from the cooling water catheter distal end 5a toward the stent 110, ensuring that the stent 110 is cooled.

Furthermore, in the endoscopic catheter 100 according to the present invention, when the snare wire 40 is exposed distally from the distal end 1a of the catheter tube 1 and expanded in diameter, an extension line L (see FIG. 2) extending the axis of the cooling water catheter lumen 1c distally may be set to pass inside the loop 40a of the snare wire 40.

This configuration allows the cooling water catheter 5 to be passed inside the loop 40a of the snare wire 40, which has expanded distally from the tube distal end 1a. With the cooling water catheter 5 passed inside the loop 40a of the snare wire 40, the cooling water catheter distal end 5a is advanced distally to approach the stent 110 and then inserted into the lumen of the stent 110, allowing the loop 40a to be positioned relative to the stent 110 using the cooling water catheter 5 as a guide, and the stent 110 to be easily captured by the loop 40a of the snare wire 40.

Furthermore, the endoscopic catheter 100 according to the present invention has a control wire 30 that is inserted so as to be able to advance and retreat within the snare lumen 1b formed along the axial direction within the catheter tube 1 and is connected at its distal end to the snare wire proximal end 40c, and the cross-sectional shape of the distal end of the control wire 30 and the cross-sectional shape of the distal end of the snare lumen 1b may be set so as to restrict the rotation of the control wire 30 about the axial direction as the axis of rotation at the distal end of the snare lumen 1b through which the distal end of the control wire 30 advances and retreats.

This configuration prevents the position of the loop 40a of the snare wire 40, which has expanded distally from the distal end 1a of the tube, from shifting due to rotation of the control wire 30, and makes it possible to maintain a position that allows the cooling water catheter 5 to pass inside the loop 40a.

Furthermore, in the endoscopic catheter 100 according to the present invention, the cross-sectional shape of the distal end of the operating wire 30 and the cross-sectional shape of the distal end of the snare lumen 1b may be elliptical.

This configuration makes it possible to easily shape the cross-sectional shape of the distal end of the operating wire 30 and the cross-sectional shape of the distal end of the snare lumen 1b, thereby restricting the rotation of the operating wire 30 around the axial direction as the axis of rotation. As a result, it is possible to prevent the loop surface of the snare wire 40 from fluctuating as the operating wire 30 rotates, and to maintain the loop surface always facing the same direction relative to the distal end of the snare lumen 1b.

Furthermore, in the endoscopic catheter according to the present invention, the temperature of the cooling water may be lower than the transformation point at which the material constituting the stent 110 loses its shape recovery.

With this configuration, the stent 110 can be cooled to a temperature lower than the transformation point at which the material constituting the stent 110 loses its shape recovery, thereby reliably reducing the self-expansion force of the stent 110.

The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

LIST OF SYMBOLS 1 Catheter tube 1a Tube distal end 1b Snare lumen 1c Cooling water catheter lumen 1d Tube proximal end 1e Side hole 1f Connector 5 Cooling water catheter 5a Cooling water catheter distal end 10 Endoscope snare 30 Operation wire 30a Operation wire proximal end 30c Flexible wire 30d Connection section 40 Snare wire 40a Loop 40c Snare wire proximal end 43 Expanded section 44 Bending section 45 Distal end curved section 50 Operation section 52 Tube fixing section 56 Slide section 80 Diameter expansion direction 100 Endoscope catheter 110 Stent 111 Stomach wall 112 Intrahepatic bile duct wall 120 Endoscope channel distal end

Claims (3)

A catheter for endoscopy used for removing a self-expanding stent placed in a body, comprising:
a catheter tube that can be inserted into a channel of an endoscope;
a snare wire that is exposed distally from the distal end of the catheter tube and expands in diameter to form a loop for capturing the stent;
a cooling water catheter that discharges cooling water introduced through a proximal end of the catheter tube from a distal end disposed distal to the distal end of the catheter tube toward the stent;
having
The cooling water catheter is inserted into a cooling water catheter lumen formed in the catheter tube along the axial direction so as to be capable of advancing and retreating,
a catheter for an endoscope, wherein when the snare wire is exposed distally from the distal end of the catheter tube and expanded in diameter, an extension line extending the axis of the cooling water catheter lumen distally is set to pass inside the loop of the snare wire . a control wire that is inserted so as to be able to advance and retreat within a snare lumen that is formed in the catheter tube along the axial direction and that is connected at its distal end to a proximal end of the snare wire;
The endoscopic catheter according to claim 1, characterized in that at the distal end of the snare lumen through which the distal end of the operating wire advances and retreats, the cross-sectional shape of the distal end of the operating wire and the cross-sectional shape of the distal end of the snare lumen are set so as to regulate rotation of the operating wire about the axial direction as a rotation axis. 3. The catheter for an endoscope according to claim 2 , wherein the cross-sectional shape of the distal end portion of the operating wire and the cross-sectional shape of the distal end portion of the snare lumen are elliptical.