Tracheoesophageal fistula occlusion stent based on electro-activated polymer and occlusion method

Abstract

The application discloses a trachea-esophagus fistula plugging stent based on an electrically actuated polymer and a plugging method, which comprises a trachea end stent, an esophagus end stent and an intermediate stent, the intermediate stent comprises an intermediate strut and an elastic capsule, the trachea end stent is connected with the esophagus end stent through the intermediate strut, and the elastic capsule is arranged on the outer side of the intermediate strut. In the application, polymer sheet drivers are arranged on the free ends of the trachea end stent and the esophagus end stent, the polymer sheet drivers can be attached to a fistula in a soft contact mode after being excited by electricity, the elastic capsule is arranged, the elastic capsule can be adapted to the inner walls of different types of fistula channels after being inflated, meanwhile, the stability and safety of the plugging stent are ensured, pressure sensors are arranged on the free ends of the polymer sheet drivers, the deformation of the polymer sheet drivers can be controlled under the monitoring of applied voltage, and the attachment degree to the tissues near the fistula is improved.

Description

Technical Field

[0001] This invention relates to the field of minimally invasive technology, and more specifically to a tracheoesophageal fistula closure stent and closure method based on an electro-actuated polymer. Background Technology

[0002] Tracheoesophageal fistula is a condition caused by congenital or acquired factors, such as trauma or esophageal cancer, that leads to a connection between the trachea and esophagus. It often results in serious and difficult-to-treat pulmonary complications such as aspiration pneumonia, and in severe cases, prevents patients from eating orally, significantly reducing their quality of life. Clinical treatment methods include surgical suture repair to close the fistula and mechanical closure devices. Manual suture repair is more invasive, involves more complex procedures, and has a higher incidence of postoperative complications. Mechanical closure devices have some drawbacks.

[0003] However, traditional mechanical sealing methods have the following problems:

[0004] 1. Traditional stents, once inserted, forcibly expand the space inside the trachea and esophagus, causing patients to experience severe discomfort and affecting their daily lives;

[0005] 2. Traditional stents are mostly rigid mechanical structures, lacking adjustability and adaptability. The location and shape of tracheoesophageal fistulas are usually random, and traditional mechanical closure structures cannot be adjusted and adapted to the diversity of tissues inside and near the fistula.

[0006] 3. Traditional stents lack a fixing device when occluding fistulas and do not fit well with the tissues near the fistula. After a period of time, tiny gaps may form, making it impossible to prevent small residues or liquids from seeping into the esophagus and flowing through the fistula to the trachea.

[0007] 4. Traditional rigid stents can cause significant secondary damage to surrounding tissues when their position shifts due to the patient's daily activities.

[0008] Existing patent document CN109758204A discloses an esophagotracheal fistula occlusion stent placement device. This solution features a single-layer structure at both ends of the esophagotracheal fistula occlusion stent, which is relatively lighter than the disc-shaped structure of vascular occluders, reducing the risk of tissue necrosis around the fistula. Furthermore, the esophageal end is larger than the tracheal end, further reducing the risk of the occluder falling into the trachea.

[0009] However, it cannot adjust and adapt to the diversity of tissues inside and near the fistula. At the same time, a patient's violent cough can cause the occlusive stent to shake, affecting its stability. Summary of the Invention

[0010] The technical problem to be solved by this invention is how to make the occlusion stent adaptable to the diversity of tissues inside and near the fistula.

[0011] The present invention solves the above-mentioned technical problems through the following technical means: a tracheoesophageal fistula occlusion stent based on an electro-actuated polymer, comprising a tracheal end stent, an esophageal end stent, and an intermediate stent. The intermediate stent includes a central support column and an elastic bladder. The tracheal end stent is connected to the esophageal end stent through the central support column. The elastic bladder is located outside the central support column. The elastic bladder is connected to the tracheal end stent and the esophageal end stent and surrounds them to form a sealed and adjustable cavity structure. The free ends of the tracheal end stent and the esophageal end stent are each connected to a fixed stent. The fixed stent includes a polymer sheet actuator. A pressure sensor is provided on the side of the free end of the polymer sheet actuator facing the fistula opening.

[0012] By setting polymer sheet actuators at the free ends of the tracheal and esophageal stents, they can be applied to the fistula opening in a soft contact manner after being electrically stimulated. The elastic capsule can be adapted to the inner wall of different types of fistula channels after inflation, while also ensuring the stability and safety of the occlusion stent. By setting a pressure sensor at the free end of the polymer sheet actuator, the deformation of the polymer sheet actuator can be controlled under monitored applied voltage, which improves the degree of adhesion to the tissues near the fistula opening.

[0013] As a preferred technical solution, both the tracheal stent and the esophageal stent are equipped with a self-locking device, and the end of the polymer sheet driver extending into the tracheal stent and the esophageal stent can be locked or opened with the self-locking device.

[0014] As a preferred technical solution, the fixation bracket further includes a plastic patch. The end of the polymer patch driver facing away from the fistula is fixed with the plastic patch. The self-locking device includes a rack and a pawl. The end of the polymer patch driver extending into the tracheal end bracket and the esophageal end bracket is fixed with a rack. The tracheal end bracket and the esophageal end bracket are each provided with a guide cavity adapted to the rack. The guide cavity is also elastically connected with a pawl. The pawl is also connected to the elastic capsule through a control line.

[0015] As a preferred technical solution, both the tracheal end support and the esophageal end support are provided with slots adapted to the plastic patch. The self-locking device also includes a limiting spring, a pin, and a stop plate. The pin is located in the guide tube cavity, with one end connected to the inner wall of the guide tube cavity and the other end fixed with the stop plate. The pawl is slidably connected to the pin and elastically connected to the inner wall of the guide tube cavity through the limiting spring. The deformation of the elastic capsule can drive the pawl to engage with the meshing surface of the rack through the control line.

[0016] As a preferred technical solution, the rack is double-toothed, the pawl meshes with one side of the rack, and a pinion is rotatably connected inside the wire cavity, which meshes with the other side of the rack.

[0017] As a preferred technical solution, the polymer sheet driver is provided in several units and is distributed at equal or non-equal angles along the circumference of the tracheal end stent and the esophageal end stent.

[0018] As a preferred technical solution, both the tracheal end stent and the esophageal end stent are provided with air holes that communicate with the cavity. A check device is provided in the air hole. The check device is slidably connected in the air hole. Gas can push the check device to slide in the air hole and form an input airway that communicates with the cavity.

[0019] As a preferred technical solution, the check valve includes a rod-shaped valve, a sealing block, and a spring. One end of the rod-shaped valve is fixed to the intermediate support, and the other end is slidably connected to the sealing block. The sealing block is elastically connected to the intermediate support through the spring.

[0020] As a preferred technical solution, the free end of the plastic patch is fixedly connected to the free end of the polymer sheet driver, the end of the plastic patch facing the fistula is encapsulated with a soft elastic material, and the end of the plastic patch connected to the polymer sheet driver is fixedly connected by a flexible toothed structure.

[0021] A closure method based on the above-mentioned closure stent includes the following steps:

[0022] S1. Locate the specific location of the fistula;

[0023] S2. Fix the occlusion stent to the air inlet at the front end of the guide tube, and insert it into the fistula from the esophageal end under the monitoring of the endoscope.

[0024] S3. Inflate the elastic bladder to expand it, causing it to interfer with the inner wall of the fistula channel and lock the self-locking device with the polymer sheet driver.

[0025] S4. After stabilization, apply electrical excitation to the polymer sheet driver to open the tracheal end stent outward until it fully contacts the tissue near the fistula and then stop the energizing.

[0026] S5. Open the esophageal stent outward; stop the power supply when the esophageal stent fully contacts the tissue near the fistula, creating a self-locking mechanism.

[0027] S6. Reduce the inflation pressure until inflation is complete, then remove the tubing and lead wires.

[0028] The advantages of this invention are:

[0029] (1) In this invention, by setting a polymer sheet actuator at the free end of the tracheal end stent and the esophageal end stent, it can be attached to the fistula in a soft contact manner after being electrically excited. By setting an elastic bladder, it can be adapted to the inner wall of different types of fistula channels after inflation, while also ensuring the stability and safety of the occlusion stent. By setting a pressure sensor at the free end of the polymer sheet actuator, the deformation of the polymer sheet actuator can be controlled under the monitored applied voltage, which improves the degree of attachment to the tissue near the fistula.

[0030] (2) In this invention, the entire occlusion stent has no hard parts, and at the same time, it does not forcibly expand the space of the trachea and esophagus, does not compress the esophagus, reduces pain, and improves the patient's quality of life.

[0031] (3) In this invention, the rack and polymer plate driver can be limited by the slot so that they can move along the axis of the intermediate support. The polymer plate driver can be limited by the pawl, rack and pinion in the self-locking device. Due to the unidirectional nature of the pawl, the polymer plate driver can be prevented from being displaced due to the patient's cough after the airbag is blocked. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the occlusion support structure provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the fixed support structure provided in an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the intermediate support structure provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the plastic patch structure provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the pressure sensor structure provided in an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the internal structure of the tracheal end support provided in an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of a rack structure provided in an embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the bending state of the plastic patch provided in an embodiment of the present invention;

[0040] Figure 9 A schematic diagram of the pawl located in the meshing plane provided in an embodiment of the present invention;

[0041] Figure 10This is a schematic diagram of the initial state structure of the pawl provided in an embodiment of the present invention;

[0042] Figure 11 This is a schematic diagram of the internal structure of the pores provided in an embodiment of the present invention;

[0043] Figure 12 A schematic diagram of the spring structure provided in an embodiment of the present invention;

[0044] Figure 13 This is a schematic diagram of the airbag inflation change provided in an embodiment of the present invention;

[0045] Figure 14 This is a schematic diagram of the fistula wall structure provided in an embodiment of the present invention;

[0046] Figure 15 This is a schematic diagram of the insertion of the occlusion stent provided in an embodiment of the present invention;

[0047] Figure 16 This is a schematic diagram of the installation of the sealing bracket provided in an embodiment of the present invention;

[0048] Reference numerals: 1. Fixed bracket; 11. Polymer sheet driver; 111. Pressure sensor; 12. Plastic patch; 2. Tracheal end bracket; 21. First slot; 22. Bracket base wire cavity; 23. First wire hole; 3. Esophageal end bracket; 31. Second slot; 32. Second wire hole; 4. Self-locking device; 41. Rack; 42. Pinion; 43. Pad; 44. Pin; 45. Abutment; 46. Limiting spring; 47. Control line; 5. Intermediate bracket; 51. Intermediate support; 52. Elastic bladder; 6. Check valve; 61. Rod valve; 62. Sealing block; 63. Spring. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] See Figure 1 , one A tracheoesophageal fistula occlusion stent based on an electrically actuated polymer includes a tracheal end stent 2, an esophageal end stent 3, and an intermediate stent 5. (See reference...) Figure 2 , Figure 3The intermediate stent 5 includes an intermediate support column 51 and an elastic capsule 52. The tracheal end stent 2 is connected to the esophageal end stent 3 through the intermediate support column 51. The elastic capsule 52 is located outside the intermediate support column 51 and is connected to the tracheal end stent 2 and the esophageal end stent 3, forming a sealed and adjustable cavity structure. The intermediate support column 51 has multiple inflation holes, which communicate with the cavity. The free ends of the tracheal end stent 2 and the esophageal end stent 3 are both connected to a fixed support 1. (See reference...) Figure 4 The mounting bracket 1 includes a polymer plate driver 11. Of course, the polymer plate driver 11 can also be other electrically actuated polymers, see [reference]. Figure 5 A pressure sensor 111 is provided on the side of the free end of the polymer sheet driver 11 facing the fistula. By setting the polymer sheet driver 11 on the free end of the tracheal end stent 2 and the esophageal end stent 3, it can be attached to the fistula in a soft contact manner after being electrically excited. With the setting of the elastic bladder 52, it can be adapted to the inner wall of different types of fistula channels after inflation, while also ensuring the stability and safety of the occlusion stent. By setting the pressure sensor 111 on the free end of the polymer sheet driver 11, the deformation of the polymer sheet driver 11 can be controlled under the monitored applied voltage, which improves the degree of attachment to the tissue near the fistula.

[0051] It should be noted that there are several polymer sheet actuators 11, which are distributed at equal or non-equal angles along the circumference of the tracheal end stent 2 and the esophageal end stent 3. The number of polymer sheet actuators 11 can be adjusted according to the size of the fistula. In this embodiment, four are provided on both the tracheal end stent 2 and the esophageal end stent 3, and they are connected at equal angles along the tracheal end stent 2 and the esophageal end stent 3 with an interval angle of 90°. When the elastic airbag is inflated, its shape is larger in the middle and smaller at both ends. Of course, it can be cylindrical, but it is not limited to this.

[0052] See Figure 5 , Figure 7 The fixing bracket 1 also includes a plastic patch 12, which is fixed to the end of the polymer sheet driver 11 away from the fistula opening. The free end of the plastic patch 12 and the free end of the polymer sheet driver 11 can also be integrally formed. The end of the plastic patch 12 facing the fistula opening is encapsulated with a soft elastic material. The end of the plastic patch 12 connected to the polymer sheet driver 11 is fixedly connected by a flexible tooth structure. The polymer sheet driver 11 is provided with a flexible tooth structure. The main body of the plastic patch 12 is aluminum or hard plastic to ensure that it can provide sufficient restraint force after deformation and will not bend back. The flexible tooth structure can generate a large friction force under the influence of interaction force, which can better ensure the self-locking of the polymer sheet driver 11 and the plastic patch 12.

[0053] To address the unknown nature of the tissue near the fistula, the pressure sensor 111 installed on the polymer sheet driver 11 can collect pressure change signals as the polymer sheet driver 11 approaches the tissue near the fistula, thereby determining the degree of contact in real time and thus determining the position where the disconnect voltage triggers self-locking.

[0054] See Figure 7 , Figure 8 , Figure 9 , Figure 10 Both the tracheal stent 2 and the esophageal stent 3 are equipped with a self-locking device 4. One end of the polymer sheet actuator 11 extending into the tracheal stent 2 and the esophageal stent 3 can be locked or unlocked with the self-locking device 4. The self-locking device 4 includes a rack 41, a pinion 42, a pawl 43, a pin 44, a stop 45, a limiting spring 46, and a control line 47. One end of the polymer sheet actuator 11 extending into the tracheal stent 2 and the esophageal stent 3 is fixedly connected to the rack 41 via a plastic patch 12. Both the tracheal stent 2 and the esophageal stent 3 have... The device has a guide tube cavity 42 adapted to the rack 41. A pawl 43 is elastically connected within the guide tube cavity 42. The pawl 43 is also fixedly connected to the elastic capsule 52 via a control line 47. Slots adapted to the plastic patch 23 are provided on both the tracheal end support 2 and the esophageal end support 3. A pin 44 is disposed within the guide tube cavity 42, one end of which is connected to the inner wall of the guide tube cavity 42, and the other end is fixed with a stop plate 45. The stop plate 45 limits the travel of the pawl 43. The pawl 43 is slidably connected to the pin 44 and is connected to the guide tube cavity 42 near the tracheal end support via a limiting spring 46. The inner wall of one side of the axis of the scaffold 2 or the esophageal end stent is elastically connected. Under normal conditions, under the elastic action of the limiting spring 46, the pawl 43 is not located in the meshing plane with the rack 41, but abuts against the abutment 45. When the elastic capsule 52 deforms and enlarges, the central protrusion can pull the pawl 43 into the meshing surface with one side of the rack 41 through the control line 47. The rack 41 is double-toothed. The pawl 43 meshes with one side of the rack 41. A pinion 42 is also rotatably connected in the wire cavity 42. The pinion 42 meshes with the other side of the rack 41. The pin 44 is equipped with There is a protrusion, and a section of the protrusion on the meshing plane is notched. The pawl 43 is provided with a groove larger than the protrusion to ensure that the pawl 43 can smoothly enter or exit the notch. The tracheal end support 2 and the esophageal end support 3 are both provided with wire holes 23 that are compatible with the control line 47. The wire holes 23 are connected to the wire cavity 42. During the inflation process, the elastic bladder 52 expands outward in the middle, thereby driving one end of the control line 47 to move. The other end of the control line 47 pulls the pawl 43 to engage in the other side (meshing plane) of the double toothed rack 41.

[0055] See Figure 6The tracheal stent 2 includes a tracheal stent base, a first slot 21, a stent base wire cavity 22, and a first wire hole 23. The top of the end of the tracheal stent 2 facing away from the intermediate stent 5 has an annular first slot 21, and four stent base wire cavities 22 and first wire holes 23 are formed in its circumferential inner wall. The esophageal stent 3 includes an esophageal stent base, a second slot 32, and a second wire hole 33. The top of the end of the esophageal stent base facing away from the intermediate stent 5 has an annular second slot 32, and four stent base wire cavities 22 and second wire holes 32 are formed in its circumferential inner wall.

[0056] See Figure 11 , Figure 12 Both the tracheal end support 2 and the esophageal end support 3 have air holes that communicate with the cavity. A check device 6 is provided in the air hole. The check device 3 is slidably connected in the air hole. Gas can push the check device 3 to slide in the air hole and form an input airway communicating with the cavity. The check device 6 includes a rod-shaped valve 61, a sealing block 62, and a spring 63. One end of the rod-shaped valve 61 is fixed to the intermediate support 5, and the other end is slidably connected to the sealing block 62. The sealing block 62 is elastically connected to the intermediate support 5 through the spring 63. In this embodiment, an air hole and a check device 6 are provided on the tracheal end support 2. Under normal conditions, the sealing block 62 is pressed against the inner wall of the air hole under the action of the spring 63. When the air pressure is large enough to overcome the elastic force of the spring 63, the sealing block 62 is pushed out of the air hole. At this time, the sealing block 62 is still placed in the rod-shaped valve 61, but an input airway is formed, so that gas can be input into the elastic airbag 52.

[0057] It should be noted that in this embodiment, both the tracheal end stent 2 and the esophageal end stent 3 are cylindrical structures made of corrosion-resistant and biocompatible materials, which are friendly to the inner wall tissues of the trachea and esophagus, avoiding secondary damage. The control line 47 is wrapped with a plastic material. Each polymer sheet driver 11 is connected to a wire. When the polymer sheet driver 11 is energized, it bends. When the occlusal stent is placed into the fistula channel, the polymer sheet drivers 11 at the ends of the tracheal end stent 2 and the esophageal end stent 3 are in contact with the fistula opening. After the wires are removed, the polymer chip driver 11 will bend back after being de-energized. At this time, the rack 41 is limited by the pawl 43, and the plastic patch 12 blocks the bending of the polymer chip driver 11 through the toothed structure, keeping it in a bent state. When it needs to be retracted, the elastic bladder 52 is deflated. Under the tension of the limiting spring 46, the pawl 43 disengages from the engagement plane and re-locks onto the side of the abutment 45. Then the rack 41 drives the plastic patch 12 to move closer to the middle support 5, and the polymer chip driver 11 is reset.

[0058] See Figure 13 , Figure 14 , Figure 15 , Figure 16The usage method includes the following steps:

[0059] S1. Locate the specific location of the fistula;

[0060] S2. Fix the occlusion stent to the air inlet at the front end of the guide tube, and insert it into the fistula from the esophageal end under the monitoring of the endoscope.

[0061] S3. Inflate the elastic bladder 52 to expand it, causing it to press against the inner wall of the fistula channel, and lock the self-locking device 4 with the polymer sheet driver 11.

[0062] S4. After stabilization, apply electrical excitation to the polymer sheet actuator 11, and stop the energizing when the polymer sheet actuator 11 at the tracheal end stent 2 opens outward until it fully contacts the tissue near the fistula.

[0063] S5. Open the esophageal stent 3 outward; stop the power supply when the polymer sheet driver 11 of the esophageal stent 3 fully contacts the tissue near the fistula, thus generating self-locking.

[0064] S6. Reduce the inflation pressure until inflation is complete, then remove the tubing and leads;

[0065] S7. During recovery, reconnect the air pipe, push open the rod-shaped valve 61 of the check valve 6, the elastic bladder 52 releases air, the pulling force on the pawl 43 disappears, the pawl 43 is pushed out of the engagement plane again, the self-locking is released, and the sealing bracket can be pulled out.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tracheoesophageal fistula occlusion stent based on an electro-actuated polymer, comprising a tracheal end stent, an esophageal end stent, and an intermediate stent, characterized in that, The intermediate stent includes a central support column and an elastic bladder. The tracheal end stent is connected to the esophageal end stent via the central support column. The elastic bladder is located outside the central support column and is connected to and encloses the tracheal end stent and the esophageal end stent to form a sealed and adjustable cavity structure. The free ends of both the tracheal end stent and the esophageal end stent are connected to fixed stents. Each fixed stent includes a polymer sheet actuator, and a pressure sensor is located on the side of the polymer sheet actuator facing the fistula. Both the tracheal end stent and the esophageal end stent are equipped with self-locking devices. The ends of the polymer sheet actuator extending into the tracheal end stent and the esophageal end stent can be locked or unlocked by the self-locking devices. The fixed stent also includes a plastic patch, and a plastic patch is fixed to the end of the polymer sheet actuator facing away from the fistula. The self-locking device includes a rack and pinion, and the polymer sheet actuator extends into the tracheal end stent and the esophageal end stent. Each end of the tube-end support is fixedly connected to a rack. Both the tracheal and esophageal end supports have guide tube cavities adapted to the racks. A pawl is elastically connected within each guide tube cavity, and the pawl is connected to an elastic bladder via a control line. Both the tracheal and esophageal end supports have slots adapted to the plastic patch. The self-locking device includes a limiting spring, a pin, and a stop. The pin is located within the guide tube cavity, with one end connected to the inner wall of the cavity and the other end fixed to the stop. The pawl is slidably connected to the pin and elastically connected to the inner wall of the guide tube cavity via the limiting spring. Deformation of the elastic bladder allows the pawl to engage with the rack's meshing surface via the control line. The rack is double-toothed, with the pawl meshing with one side of the rack. A pinion is rotatably connected within the guide tube cavity, meshing with the other side of the rack. Both the tracheal and esophageal end supports have guide tube holes adapted to the control line, and these holes communicate with the guide tube cavity.

2. The tracheoesophageal fistula occlusion stent based on an electro-actuated polymer according to claim 1, characterized in that, The polymer sheet driver is provided in several units and is distributed at equal or non-equal angles along the circumference of the tracheal end stent and the esophageal end stent.

3. The tracheoesophageal fistula occlusion stent based on an electro-actuated polymer according to claim 1, characterized in that, Both the tracheal end support and the esophageal end support have air holes that communicate with the cavity. A check device is installed in the air hole. The check device is slidably connected in the air hole. Gas can push the check device to slide in the air hole and form an input airway that communicates with the cavity.

4. A tracheoesophageal fistula occlusion stent based on an electro-actuated polymer according to claim 3, characterized in that, The check valve includes a rod-shaped valve, a sealing block, and a spring. One end of the rod-shaped valve is fixed to the intermediate support, and the other end is slidably connected to the sealing block. The sealing block is elastically connected to the intermediate support through the spring.

5. A tracheoesophageal fistula occlusion stent based on an electro-actuated polymer according to claim 1, characterized in that, The free end of the plastic patch is fixedly connected to the free end of the polymer sheet driver. The end of the plastic patch facing the fistula is encapsulated with a soft elastic material. The end of the plastic patch connected to the polymer sheet driver is fixedly connected by a flexible toothed structure.

6. A closure method based on the closure stent as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Locate the specific location of the fistula; S2. Fix the occlusion stent to the air inlet at the front end of the guide tube, and insert it into the fistula from the esophageal end under the monitoring of the endoscope. S3. Inflate the elastic bladder to expand it, causing it to interfer with the inner wall of the fistula channel and lock the self-locking device with the polymer sheet driver. S4. After stabilization, apply electrical excitation to the polymer sheet actuator, and stop the energizing when the polymer sheet actuator at the tracheal stent end opens outward until it fully contacts the tissue near the fistula. S5. Open the esophageal stent outward; stop energizing when the polymer sheet driver at the end of the esophageal stent fully contacts the tissue near the fistula, thus creating a self-locking mechanism. S6. Reduce the inflation pressure until inflation is complete, then remove the tubing and lead wires.

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