Medical stent and stent delivery device

Abstract

Medical stent (10, 210), comprehensive: a plastic main body (11) which has a distal end (12) and a proximal end (13) and is formed in a tubular shape along a longitudinal axis (X1) between the distal end (12) and the proximal end (13); a first locking element (55) comprising a first fixed end (56) attached to a distal end face of the main body (11) and a first free end (57) positioned outside an outer circumferential surface of the main body (11) in a radial direction of the main body (11), wherein the first locking element (55) extends from the first fixed end (56) to the first free end (57); a second locking element (75) comprising a second fixed end (76) attached to a proximal end face of the main body (11) and a second free end (77) positioned outside an outer circumferential surface of the main body (11) in a radial direction of the main body (11), wherein the second locking element (75) extends from the second fixed end (76) to the second free end (77); a reinforcing element (30) made of metal, which extends spirally around the longitudinal axis of the main body (11) between the distal end (12) and the proximal end (13) of the main body (11) and is embedded between an inner circumferential surface of the main body (11) and the outer circumferential surface of the main body (11); and a rib (78) extending along the longitudinal axis (X1), which is connected to the second fixed end (76), wherein the reinforcing element (30) comprises: a first section (30a) wound spirally at a position between the first fixed end (56) and the second fixed end (76), a second section (30b) wound in a spiral with a greater slope than the slope of the first section (30a) and a third section (30c) wound in a spiral with a greater slope than the slope of the second section (30b), wherein the third section (30c) is positioned between the rib (78) and the inner circumferential surface of the main body (11).

Description

[TECHNICAL FIELD]

[0001] The present invention relates to a medical stent and a stent delivery device using the medical stent. [STATE OF THE ART]

[0002] It is known that a stent is placed in the bile duct to treat bile duct stenosis. It may be necessary to replace the stent due to obstruction of the indwelling stent.

[0003] When a stent is replaced, the indwelling stent is first removed and retrieved.

[0004] As one of the methods for retrieving a stent, a method for retrieving the removed stent through an endoscopic treatment tool channel is known.

[0005] As the stent is retrieved through the treatment tool channel, an operator grasps the end of the stent with a treatment tool, such as a grasper or snare, and pulls it into the channel. At this point, the end portion of the stent may be bent and overlapped at the grasped portion. Overlapping ends of the stent increase the radial dimension, so the overlapping ends must be radially crimped to pull the stent into the channel.

[0006] The stent described in WO 2014 / 136334 A1 is made of a plastic and a coil. Since there is no coil at the end of this stent, it can be easily squeezed in the radial direction. This means it can be easily pulled into the canal and collected.

[0007] US 2010 / 160847 A1 discloses a cardiovascular conduit system comprising a connector. The connector may include a proximal end suitable for attachment to a cardiovascular organ. The proximal end may include a first plurality of expandable elements, and each element of the first plurality may be deployed from a delivery position to a deployed position. The first plurality of expandable elements may be sized to expand within the cardiovascular organ to secure the connector to the cardiovascular organ. US 5,282,860 A discloses a stent tube comprising an inner tube and an outer tube, with a reinforcing braided element disposed between the inner tube and the outer tube. The inner tube is made of a fluororesin. The inner wall of the stent tube is difficult to clog and has sufficient strength to withstand bending forces.EP 2 803 339 A1 discloses a medical stent comprising a coil formed by winding a wire around an axis. The coil has a substantially tubular outer layer made of a first resin material, which is provided on an outer circumferential side of the coil and arranged coaxially with the coil. Furthermore, the coil has a substantially tubular inner layer made of a second resin material, which is provided on an inner circumferential side of the coil and is also oriented coaxially with the coil. [SUMMARY OF THE INVENTION][PROBLEMS TO BE SOLVED BY THE INVENTION]

[0008] The stent described in Patent Document 1 has a portion where no coil is disposed and a portion where a coil is disposed. When this stent is deployed, if the stent is pushed to penetrate a site of severe stenosis, stress is concentrated at the boundary between two areas with greatly different stiffness, and buckling is likely to occur. Therefore, there is a possibility that the stenosis cannot be penetrated and the stent cannot be deployed. Even if the stent can be deployed, the lumen at the kinked site becomes narrow, requiring replacement early after deployment.

[0009] Based on the above circumstances, it is an object of the present invention to provide a stent which does not easily kink during indwelling and whose ends can be easily squeezed during retrieval. [METHODS TO SOLVING THE PROBLEMS]

[0010] A first aspect of the present invention is a medical stent comprising: a plastic main body having a distal end and a proximal end and formed in a tubular shape along a longitudinal axis between the distal end and the proximal end; a first locking element having a first fixed end attached to a distal end side of the main body and a first free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, the first locking element extending from the first fixed end to the first free end;a second locking element having a second fixed end fixed to a proximal end side of the main body and a second free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, the second locking element extending from the second fixed end to the second free end; a metal-made reinforcing element extending spirally around the longitudinal axis of the main body between the distal end and the proximal end of the main body and embedded between an inner peripheral surface of the main body and the outer peripheral surface of the main body; and a rib extending along the longitudinal axis and connected to the second fixed end.

[0011] The reinforcing member includes a first portion spirally wound at a position between the first fixed end and the second fixed end, a second portion spirally wound at a pitch greater than a pitch of the first portion, and a third portion spirally wound at a pitch greater than the pitch of the second portion, and the third portion is positioned between the rib and the inner peripheral surface of the main body.

[0012] Another medical stent of the present invention is a medical stent comprising: a plastic main body having a distal end and a proximal end and formed in a tubular shape along a longitudinal axis between the distal end and the proximal end; a first locking member having a first fixed end fixed to a distal end side of the main body and a first free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, the first locking member extending from the first fixed end to the first free end;a second locking element having a second fixed end fixed to a proximal end side of the main body and a second free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, the second locking element extending from the second fixed end to the second free end; and a metal reinforcement element extending spirally around the longitudinal axis of the main body between the distal end and the proximal end of the main body and embedded between an inner peripheral surface of the main body and the outer peripheral surface of the main body;

[0013] The reinforcing member includes a first portion spirally wound at a position between the first fixed end and the second fixed end, a second portion connected to the first portion at a position between the first fixed end and the second fixed end and spirally wound toward the second fixed end at a pitch greater than a pitch of the first portion, and a third portion connected to the second portion and spirally wound at a position between the proximal end of the main body and the second fixed end at a pitch greater than the pitch of the second portion.

[0014] A second aspect of the present invention is a stent delivery device comprising: a guide catheter comprising a guide tube through which a guide wire can be inserted, and a wire connected to the guide tube; a pusher catheter comprising a first tube having a first lumen through which the wire can be inserted, and a second tube having a second lumen, which is connected to a distal end of the first lumen and through which the guide tube can be inserted; a connecting member having a loop, through which the guide tube can be inserted and which is connected to a distal end of the pusher catheter; and a stent attached to an outer peripheral surface of the guide tube and positioned distal to a distal end of the second tube.

[0015] The stent comprises a plastic main body having a distal end and a proximal end and formed in a tubular shape along a longitudinal axis between the distal end and the proximal end; a first locking element having a first fixed end attached to a distal end side of the main body and a first free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, wherein the first locking element extends from the first fixed end to the first free end; a second locking element having a second fixed end attached to a proximal end side of the main body and a second free end positioned outside an outer peripheral surface of the main body in a radial direction of the main body, wherein the second locking element extends from the second fixed end to the second free end;and a reinforcing member made of metal, which extends spirally around the longitudinal axis of the main body between the distal end and the proximal end of the main body and is embedded between an inner peripheral surface of the main body and the outer peripheral surface of the main body.

[0016] The reinforcing member includes a first portion spirally wound at a position between the first fixed end and the second fixed end, a second portion connected to the first portion at a position between the first fixed end and the second fixed end and spirally wound toward the second fixed end at a pitch greater than a pitch of the first portion, and a third portion connected to the second portion and spirally wound at a position between the proximal end of the main body and the second fixed end at a pitch greater than the pitch of the second portion.

[0017] The main body has a through hole on the outer peripheral surface between the proximal end and the second fixed end, and the loop of the connecting member is inserted into the through hole.

[0018] The stent is positioned relative to the pusher catheter by inserting the guide tube into the loop. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall view of a stent delivery device according to a first embodiment of the present invention. Fig. 2 is a side view of a stent according to the first embodiment of the present invention. Fig. Figure 3 is a perspective view of the stent. Fig. Figure 4 is a schematic cross-sectional view of the stent delivery device. Fig. 5 is a schematic diagram showing a process for placing a stent using the stent delivery device. Fig. 6 shows an indwelling stent. Fig. Figure 7 shows a procedure for pulling the stent into an endoscope channel. Fig. 8 is a schematic view showing a structure of a stent according to a second embodiment of the present invention. Fig. 9 is a schematic diagram showing a modified example of the rib. Fig. 10 is a schematic diagram showing a modified example of the rib. Fig. 11 is a schematic diagram showing a modified example of the rib. Fig. 12 is a schematic cross-sectional view of a stent delivery device according to a modified example of the present invention. DESCRIPTION OF EMBODIMENTS

[0019] An embodiment of the present invention will be described with reference to Fig. 1 to 7 described.

[0020] Fig. 1 is an overall view of a stent delivery device 1 of the present embodiment. The stent delivery device includes a medical stent (hereinafter referred to simply as "stent") 10 and a delivery catheter 100.

[0021] Fig. 2 is a side view of the stent 10. The stent 10 of the present embodiment is a bile duct-deposited stent and includes a tubular main body 11 and valves 50 at both ends of the main body 11. The main body has a distal end 12 and a proximal end 13 and extends along the longitudinal axis X1. The distal end 12 is an end portion positioned toward the liver when placed in the bile duct. The proximal end 13 is an end positioned toward the papilla of Vater when placed in the bile duct.

[0022] Fig. 3 is a perspective view of the stent 10, in which the outer layer of the stent 10 is shown transparent. The main body 11 includes an inner plastic layer 20, a metal wire (reinforcing member) 30 wound around the inner layer 20, and an outer plastic layer 40 covering the inner layer 20 and the wire 30. The wire 30 is sandwiched between the inner peripheral surface and the outer peripheral surface of the main body 11.

[0023] The inner layer 20 is a tube formed from a plastic material with a smooth surface and biocompatibility, such as PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxyalkane).

[0024] The wire 30 is spirally wound on the outer peripheral surface of the inner layer 20 and is formed as a whole into a coil shape. By spirally winding the wire 30 between the inner peripheral surface and the outer peripheral surface of the main body 11, buckling of the stent 10 can be suppressed and the flexibility of the stent 10 is improved. The material of the wire 30 is a radiopaque material such as tungsten steel and stainless steel. The wire 30 has a plurality of regions with different winding pitches. Details will be explained later.

[0025] The outer layer 40 is made of a plastic material with elasticity, flexibility, and biocompatibility, such as urethane or polyethylene. The outer layer 40 is also provided in a space between adjacent wires 30 in the longitudinal axis direction X1.

[0026] The flap 50 has a first flap 51 provided on the side of the distal end 12 and a second flap 71 provided on the side of the proximal end 13.

[0027] The first flap 51 has a plurality of first locking elements 55. Each first locking element 55 is an elongated element 57 having a first fixed end 56 and a first free end 57 and extending between the first fixed end 56 and the first free end.

[0028] Each first locking element 55 has a rib 58 extending from the first fixed end 56. The width of the rib 58 is the same as that of the first locking element 55. Each first locking element 55 is attached to the main body 11 by joining the rib 58 to the outer peripheral surface of the main body 11. The ribs 58 can be joined by heat-fusion, adhesive bonding, or the like. By joining the rib 58 to the main body 11, the first fixed end 56 of each first locking element 55 is fixed to the main body 11. The first locking element 55 extends from the first fixed end 56 toward the first free end 57 in a direction gradually away from the side of the proximal end 13 of the main body 11 and the outer peripheral surface of the main body 11.

[0029] The second flap 71 has a similar structure to that of the first flap 51 and includes a plurality of locking elements 75. The second locking element 75 is shorter than the first locking element 55. Each second locking element 75 has a second fixed end 76 and a second free end 77. The rib 78 extends from the second fixed end 76. Each second locking element 75 is attached to the main body 11 by attaching the rib 78 to the outer peripheral surface of the main body 11, and the second fixed end 76 is fixed to the main body 11. The second locking element 75 extends from the first fixed end 76 toward the first free end 77 in a direction gradually away from the side of the distal end 12 of the main body 11 and the outer peripheral surface of the main body 11.

[0030] The number of first locking elements 55 in the first flap 51 and the number of second locking elements 75 in the second flap 71 can be determined as appropriate. In this embodiment, the first flap 51 and the second flap 71 each have four locking elements. The four locking elements 55 are arranged at equal intervals in the circumferential direction of the main body 11.

[0031] For the first flap 51 and the second flap 71, the phases on the outer peripheral surface of the main body 11 under which the locking element is mounted may be the same or different. For the first flap 51 and the second flap 71, the number of locking elements may be the same or different.

[0032] The spirally wound wire 30 is mounted between the first fixed end 56 and the distal end 13. The end of the wire 30 on the distal end side is fixed to the main body by a metal ring 35. The wire 30 has a plurality of regions with different winding pitches in the longitudinal axis direction X1. The winding pitch is generally uniform in each region. The first region (first portion) 30a on the most distal side is positioned at least between the first fixed end 56 and the second fixed end 76 and has the smallest winding pitch. The winding pitch of the second region (second portion) 30b adjacent to the first region 30a is larger than the winding pitch of the first region 30a.The winding pitch of the third region (third section) 30c, which is adjacent to the second region 30b and positioned closest to the proximal end side, is larger than the winding pitch of the second region 30b.

[0033] The number of turns per unit length of the wire 30 is greatest in the first region 30a, less in the second region 30b than in the first region 30a, and least in the third region 30c. The value of the winding angle (inclination) of the wire 30 with respect to the longitudinal axis X1 is closest to a right angle in the first region 30a and has the greatest deviation from a right angle in the third region 30c. The value of the winding angle of the second region 30b lies between that of the first region 30a and the third region 30c.

[0034] The boundary between the first region 30a and the second region 30b is positioned between the first fixed end 56 and the second fixed end 76, and between the first free end 57 and the second free end 77 in the longitudinal axis direction X1. The boundary between the second region 30b and the third region 30c is substantially the same as the position of the second fixed end 76 in the longitudinal axis direction X1. In the longitudinal axis direction X1, the second region 30b is longer than the third region 30c.

[0035] The length of the second locking element 75, that is, the length from the second fixed end 76 to the second free end 77, is shorter than the length of the second region 30b in the longitudinal axis direction X1.

[0036] On the main body 11, a through-hole 14 communicating with the interior of the main body 11 is formed on the outer peripheral surface between the first fixed end 56 and the distal end 12, and bile can flow in from the outer peripheral surface of the main body 11. The number and position of the through-holes 14 can be determined as appropriate. Some or all of the through-holes 14 may overlap the rib 58.

[0037] A through-hole 15 communicating with the interior of the main body 11 is formed on the outer peripheral surface of the third portion 30c. The position of the through-hole 15 can be determined as appropriate. Some or all of the through-holes 15 may overlap the rib 78.

[0038] Fig. 4 is a schematic cross-sectional view of the structure of the stent delivery device 1. The delivery catheter 100 includes a guide catheter 80 and a pusher catheter 90.

[0039] The guide catheter 80 has a tube (guide tube) 81 through which a guide wire can be inserted, and a pulling portion 85 for moving the tube 81.

[0040] The tube 81 is a tubular member made of plastic and has a hollow space through which a guide wire can be inserted. The tube 81 is flexible enough to be deformed when the tube 81 comes into contact with a living tissue when the delivery device 1 is used. The tube 81 is 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 inner peripheral surface 81b of the tube 81 is circular in the radial cross-sectional view of the tube 81. The tube 81 has a small-diameter portion 82 positioned on the distal end side of the delivery device 1 and a large-diameter portion 83 positioned on the proximal end side of the delivery device 1.The outer peripheral surface of the small-diameter portion 82 and the outer peripheral surface of the large-diameter portion 83 are connected by a smooth curved surface. As a result, the outer diameter of the tube 81 gradually increases from the small-diameter portion 82 toward the large-diameter portion 83.

[0041] The outer diameters of the small diameter portion 82 and the large diameter portion 83 are smaller than the inner diameter of the stent 10. Therefore, by inserting the tube 81 into the stent 10, the stent 10 can be attached to the tube 81.

[0042] When the diameter of the stent 10 is small or the like, the tube 81 does not need to have a small diameter portion and a large diameter portion, and may have the same diameter in the longitudinal direction.

[0043] The pulling section 85 includes a tube 86, a wire 87, and an actuating section 89. The tube 86 is a tubular metal member with both ends open in the axial direction. The tube 86 is coaxial with the tube 81 and embedded in the wall of the tube 81. The tube 86 is arranged at the proximal end portion of the large-diameter section 83.

[0044] The wire 87 is made of metal, its distal end is welded to the tube 86, and the proximal end portion is connected to the actuating portion 89.

[0045] The pusher catheter 90 has a single lumen tube (second tube) 91, a multi-lumen tube (first tube) 92 and a grasping portion 93.

[0046] The single-lumen tube 91 is a tubular member having an inner diameter through which the large-diameter portion 83 of the tube 81 can pass. The single-lumen tube 91 has flexibility. The distal end surface of the single-lumen tube 91 is a plane perpendicular to the centerline of the single-lumen tube 91. The distal end surface of the single-lumen tube 91 contacts the proximal end of the stent 10 to support the stent 10. The wall thickness of the single-lumen tube 91 is equal to or greater than the difference between the inner radius and the outer radius of the main body 11 of the stent 10 (i.e., the wall thickness of the stent 10). The single-lumen tube 91 has a length that allows the large-diameter portion 83 of the tube 81 to be completely accommodated within the single-lumen tube 91. The material of the single-lumen tube 91 is not particularly limited, but a plastic is preferred.

[0047] The multi-lumen tube 92 is attached to the proximal end of the single-lumen tube 91. The multi-lumen tube 92 has a guidewire lumen 92a and a wire lumen (first lumen) 92b for inserting the guidewire. The wire 87 of the guide catheter 80 is inserted through the wire lumen 92b.

[0048] The guide wire lumen 92a is open to the distal end of the multi-lumen tube 92 and is open to the side surface of the multi-lumen tube 92 on the side of the proximal end of the distal end of the multi-lumen tube 92.

[0049] The wire lumen 92b is open at the distal end and the proximal end of the multi-lumen tube 92.

[0050] The gripping portion 93 is connected to the proximal end of the multi-lumen tube 92. The gripping portion 93 has a substantially cylindrical shape with a diameter larger than that of the multi-lumen tube 92. The outer peripheral surface of the gripping portion 93 may be formed with unevenness or the like to prevent slippage.

[0051] The gripping portion 93 is formed with a through-hole 93a that communicates with the wire lumen 92b. The through-hole 93a is positioned on an extension line toward the proximal end side of the center line of the multi-lumen tube 92.

[0052] The wire 87 of the guide catheter 80 is inserted through the through-hole 93a. As a result, the wire 87 and the actuating portion 89 extend from the through-hole 93a.

[0053] A hole 91a communicating with the interior is provided at the distal end of the single-lumen tube 91. A thread (connecting element) 95 is passed through the hole 91a. The end of the thread 95 is tied into a loop. The loop thread 95 enters the main body 11 of the stent 10 through the through-hole 15. The tube 81 of the guide catheter 80 passes through the loop of the thread 95 inside the stent 10.

[0054] The operation when the stent delivery device 1 configured as described above is used will now be described.

[0055] The operator guides the guidewire through the channel of the side-view endoscope and inserts it into the bile duct while observing with the endoscope. The operator then manipulates the guidewire under fluoroscopy to penetrate the stenosis in the bile duct and advance the distal end of the guidewire deeper than the stenosis.

[0056] The operator inserts the proximal end of the guidewire protruding from the forceps opening of the endoscope into the distal end opening of the tube 81 of the stent delivery device 1, to which the stent 10 is mounted. The guidewire enters the lumen of the single-lumen tube 91 through the proximal opening of the tube 81. Furthermore, the operator causes the distal end portion of the guidewire to enter the guidewire lumen 92a and protrude from the side opening at the proximal end of the guidewire lumen 92a.

[0057] The operator inserts the stent delivery device 1, through which the guidewire is guided into the channel of the endoscope, into the channel of the endoscope and protrudes the distal end of the stent delivery device 1 from the distal end of the channel. The operator manipulates a rising base of the endoscope to direct the distal end of the stent delivery device 1 toward the papilla of Vater and allow the stent delivery device 1 to enter the bile duct along the guidewire.

[0058] As it is in Fig. As shown in Figure 5, an insertion resistance occurs as the distal end of the stent delivery device 1 approaches the stenosis site St in the bile duct Bd. Due to such insertion resistance, a compressive force acts on the stent 10 in the longitudinal axis direction X1. This force is concentrated at the site of the stent 10 where the structure changes significantly.

[0059] Since the wire 30 in the stent 10 has the first region 30a, the second region 30b, and the third region 30c, the above-described force acts in a distributed manner at the boundary between the first region 30a and the second region 30b and at the boundary between the second region 30b and the third region 30c. As a result, kinking during deployment of the stent 10 is preferably prevented.

[0060] In the stent 10, the rib 78 attached to the third region 30c extends parallel to the longitudinal axis X1 of the stent 10. The rib 78 performs a bone-like function in the third region 30c and reinforces the anti-kinking effect described above.

[0061] Since the width of the rib 78 is smaller than the width of the second locking element 75, the volume per unit length of the rib 78 is smaller than that of the second locking element 75. This prevents the third region 30c from becoming too hard and reduces the insertability and followability of the rounding of the bile duct.

[0062] When the first flap 51 moves deeper than the stenosis site St, the operator continues to move and retracts the stent delivery device 1 to determine the deployment position of the stent 10. With the stent delivery device 1, the stent 10 will not detach from the pusher catheter 90 as long as the tube 81 passes through the loop of the suture 95. Therefore, the stent 10 can be retracted by retracting the stent delivery device 1. This allows the position of the stent 10 to be easily adjusted.

[0063] After the placement position of the stent 10 has been determined, the operator pulls the actuating section 89 toward the hand while holding the pusher catheter 90. Then, the wire 87 and the tube 81 retract, but the stent 10 does not retract because it is in contact with the pusher catheter 90. When the tube 81 retracts and comes out of the stent 10 and the thread 95, the thread 95 detaches the stent 10 from the pusher catheter 90, and the stent 10 is placed at a desired position within the bile duct, as shown in Fig. 6 is shown.

[0064] After the placement of the stent 10, the first flap 51 is placed at the back of the stenosis site St and the second flap 71 is placed near the Vater's papilla Dp outside the bile duct so that the placement position is preferably maintained.

[0065] Next, the procedure is described when the indwelling stent is collected via the endoscope channel.

[0066] The operator inserts a side-endoscope near the papilla of Vater and extends a retrieval tool, such as a grasping forceps or a loop, from the channel. Next, the operator holds the proximal end of the stent 10 with the retrieval tool.

[0067] The operator retracts the retrieval tool holding the stent 10. When the stent 10 reaches the channel opening at the distal end of the side endoscope, the stent 10 is pulled into a channel 111 of the endoscope 110 while being folded over at the location held by the retrieval tool 120, as shown in Fig. 7. Since the portion held by the collector 120 (holding portion) is the third region 30c or the second region 30b, and the portion to be folded is a portion closer to the proximal end 13 than the holding portion, the portion to be folded always becomes the third region 30c or the second region 30b, and the first region 30a is not folded. That is, when the stent 10 of the present embodiment is retrieved via the channel of the endoscope, the third region 30c or the second region 30b, each having a larger winding pitch of the wire 30 than the first region 30a, is folded and slightly squeezed, and the stent 10 is slightly squeezed and drawn into the channel 111.Since, as described above, the volume per unit length of the rib 78 is smaller than that of the second locking member 75, the rib 78 is less likely to prevent the third portion 30c from being squeezed.

[0068] To ensure that the stent 10 operates as described above at the time of retrieval, it is necessary to place either the second portion 30b or the third portion 30c in the entire portion at the proximal end side of the position closest to the distal end of the interval that can be held by the retrieval tool 120 in the stent 10. As long as this condition is met, the arrangement order and length of the second portion and the third portion can be appropriately determined.

[0069] A second embodiment of the present invention will be described with reference to Fig. 8. In the following description, the embodiments that correspond to those already described are given the same reference numerals and a duplicate description is omitted.

[0070] Fig. Figure 8 is a schematic diagram schematically showing the structure of the stent 210 of the present embodiment. In the stent 210, the winding pitch of the wire 30 is determined such that the first region 30a, the third region 30c, and the second region 30b are positioned in this order from the distal end side.

[0071] The second fixed end 76 of the second locking element 75 is positioned at the proximal end of the third region 30c. The rib 78 extends from the distal end portion of the third region 30c toward the distal end portion and is attached to the third region 30c. That is, the rib 78 is connected to the second fixed end 76 of the second locking element 75, and the rib 78 extends from the second fixed end 76 toward the side of the distal end 12.

[0072] Although the stent 210 of the present embodiment has a different structure from that of the stent 10 of the first embodiment, it exhibits substantially the same effect. That is, since the third region 30c with the largest winding pitch is appropriately reinforced by the rib 78, the third region 30c exhibits a good balance between kink resistance and crushability at the time of collection.

[0073] 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 embodiments, and it is possible to change the combination of components, make various changes to each component, and remove them without departing from the gist of the present invention.

[0074] Some changes are shown below, but not all, and further changes are possible. Two or more of these changes may be combined as appropriate.

[0075] The shape of the rib of the second locking element is not limited to the narrow shape described above. For example, as in the Fig. 9, even if the width is the same as that of the second locking element 75 and the inside is partially hollowed out, the volume per unit length can be made smaller than that of the second locking element. By forming the rib 278 thinner than the second locking element 75, as shown in Fig. 10, the volume per unit length can be made smaller than that of the second locking element.

[0076] As it is in Fig. 11, a plurality of ribs 78 may be connected by an annular connecting portion 80 extending in the circumferential direction of the main body 11. In this way, the plurality of second locking elements can be attached while maintaining the positional relationship in the circumferential direction of the main body. This structure can be applied to the first flap.

[0077] By providing a plastic layer to cover the ribs, the connection between the ribs and the main body can be strengthened.

[0078] Since the distal end side of the stent does not need to be squeezed at the time of retrieval, the shape of the rib of the first locking element does not necessarily have to be the same as that of the second locking element.

[0079] If the stent is not pre-attached to the delivery catheter, it may have a structure that does not have a through-hole 15.

[0080] The delivery catheter in the present invention is not limited to having the structure described above. Fig. Figure 12 shows another embodiment of the stent delivery device. The delivery catheter 300 of the Fig.The stent delivery device 1A shown in Figure 12 comprises a guide catheter 280 and a pusher catheter 290. The pusher catheter 290 consists only of a single-lumen tube and does not have a multi-lumen tube. The guide catheter 280 has a small-diameter portion 82 and a large-diameter portion 83 and does not have a pulling portion. The large-diameter portion 83 extends within the pusher catheter 290 and protrudes from the proximal opening 291 of the pusher catheter 290.

[0081] In the stent delivery device 1A, the guide wire, which has entered from the opening 281 at the distal end of the guide catheter 280, passes through the guide catheter 280 and protrudes from the proximal opening 282. The stent delivery device 1A requires a longer guide wire than that of the stent delivery device 1, but has the same effect as the stent delivery device 1. [INDUSTRIAL APPLICABILITY]

[0082] The present invention can be applied to stents and stent delivery devices. [DESCRIPTION OF REFERENCE NUMBERS] 1, 1A Stent delivery device 10, 210 Medical stent 30 wire (reinforcing element) 30a First Region (First Section) 30b Second Region (Second Section) 30c Third Region (Third Section) 55 First locking element 56 First fixed end 57 First free end 75 second locking element 76 Second fixed end 77 Second free end 78 rib 80 guiding catheters 81 tubes (guide tubes) 87 wire 90 pusher catheters 91 Single lumen tubes (second tube) 92 multi-lumen tubes (first tube) 95 thread (connecting element)

Claims

[1] Medical stent (10, 210), comprising: a plastic main body (11) having a distal end (12) and a proximal end (13) and formed in a tubular shape along a longitudinal axis (X1) between the distal end (12) and the proximal end (13); a first locking element (55) having a first fixed end (56) fixed to a distal end side of the main body (11) and a first free end (57) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the first locking element (55) extending from the first fixed end (56) to the first free end (57); a second locking element (75) having a second fixed end (76) fixed to a proximal end side of the main body (11) and a second free end (77) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the second locking element (75) extending from the second fixed end (76) to the second free end (77); a reinforcing element (30) made of metal, which extends spirally around the longitudinal axis of the main body (11) between the distal end (12) and the proximal end (13) of the main body (11) and is embedded between an inner peripheral surface of the main body (11) and the outer peripheral surface of the main body (11); and a rib (78) extending along the longitudinal axis (X1) and connected to the second fixed end (76), wherein the reinforcing element (30) comprises: a first section (30a) spirally wound at a position between the first fixed end (56) and the second fixed end (76), a second section (30b) spirally wound with a greater pitch than a pitch of the first section (30a) and a third section (30c) spirally wound with a greater pitch than the pitch of the second section (30b), wherein the third portion (30c) is positioned between the rib (78) and the inner peripheral surface of the main body (11). [2] Medical stent (10, 210), comprising: a plastic main body (11) having a distal end (12) and a proximal end (13) and formed in a tubular shape along a longitudinal axis (X1) between the distal end (12) and the proximal end (13); a first locking element (55) having a first fixed end (56) fixed to a distal end side of the main body (11) and a first free end (57) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the first locking element (55) extending from the first fixed end (56) to the first free end (57); a second locking element (75) having a second fixed end (76) fixed to a proximal end side of the main body (11) and a second free end (77) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the second locking element (75) extending from the second fixed end (76) to the second free end (77); and a reinforcing element (30) made of metal, which extends spirally around the longitudinal axis of the main body (11) between the distal end (12) and the proximal end (13) of the main body (11) and is embedded between an inner peripheral surface of the main body (11) and the outer peripheral surface of the main body (11), wherein the reinforcing element (30) comprises: a first section (30a) spirally wound at a position between the first fixed end (56) and the second fixed end (76), a second section (30b) which is connected to the first section (30a) at a position between the first fixed end (56) and the second fixed end (76) and is spirally wound with a greater pitch than a pitch of the first section (30a) towards the second fixed end (76), and a third section (30c) connected to the second section (30b) and spirally wound at a position between the proximal end of the main body (11) and the second fixed end (76) with a greater pitch than the pitch of the second section (30b), further comprising a rib (78) connected to the second fixed end (76) and extending at least partially linearly from the second fixed end (76) toward the proximal end (13) of the main body (11) along the longitudinal axis (X1). [3] Medical stent (10, 210) according to claim 2, wherein the rib (78) is attached to the main body (11), a volume per unit length of the rib (78) is smaller than that of the second locking element (75) and the rib (78) is positioned closer to the proximal end (13) of the main body (11) than a boundary between the second portion (30b) and the third portion (30c). [4] The medical stent (10, 210) of claim 1, wherein a length of the second portion (30b) is greater than a length of the third portion (30c) in a direction along the longitudinal axis (X1) of the main body (11). [5] The medical stent (10, 210) of claim 1, wherein a length from the second fixed end (76) to the second free end (77) is smaller than a length of the second portion (30b) in a direction along the longitudinal axis (X1) of the main body (11). [6] Stent delivery device (1, 1A) comprising: a guide catheter (80) comprising a guide tube (81) through which a guide wire can be inserted, and a wire connected to the guide tube (81); a pusher catheter (90) comprising a first tube (92) having a first lumen through which the wire (87) can be inserted, and a second tube (91) having a second lumen connected to a distal end of the first lumen and through which the guide tube (81) can be inserted; a connecting element (95) with a loop through which the guide tube (81) can be inserted and which is connected to a distal end of the pusher catheter (90); and a stent (10, 210) attached to an outer peripheral surface of the guide tube (81) and positioned distal to a distal end of the second tube (91), wherein the stent (10, 210) comprises a plastic main body (11) having a distal end (12) and a proximal end (13) and formed in a tubular shape along a longitudinal axis (X1) between the distal end (12) and the proximal end (13), a first locking element (55) having a first fixed end (56) fixed to a distal end side of the main body (11) and a first free end (57) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the first locking element (55) extending from the first fixed end (56) to the first free end (57), a second locking element (75) having a second fixed end (76) fixed to a proximal end side of the main body (11) and a second free end (77) positioned outside an outer peripheral surface of the main body (11) in a radial direction of the main body (11), the second locking element (75) extending from the second fixed end (77) to the second free end (77), and a reinforcing element (30) made of metal, which extends spirally around the longitudinal axis of the main body (11) between the distal end (12) and the proximal end (13) of the main body (11) and is embedded between an inner peripheral surface of the main body (11) and the outer peripheral surface of the main body (11), the reinforcing element (30) comprises: a first section (30a) spirally wound at a position between the first fixed end (56) and the second fixed end (76), a second section (30b) which is connected to the first section (30a) at a position between the first fixed end (56) and the second fixed end (76) and is spirally wound with a greater pitch than a pitch of the first section (30a) towards the second fixed end (76), and a third section (30c) connected to the second section (30b) and spirally wound at a position between the proximal end (13) of the main body (11) and the second fixed end (76) with a pitch greater than the pitch of the second section (30b), the main body (11) has a through hole on the outer peripheral surface between the proximal end (13) and the second fixed end (76), the loop of the connecting element (95) is inserted into the through hole and the stent (10, 210) is positioned relative to the pusher catheter (90) by inserting the guide tube (81) into the loop.

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