Stent for preventing leakage of anastomosis of rectum

Abstract

This invention discloses a stent for preventing anastomotic leakage in the field of medical device technology. The stent includes a stent body, a fixation component and a navigation component fixedly connected to the stent body, and a drug-releasing component embedded in the inner wall of the stent body. This stent can be reduced in size during insertion to facilitate placement through a sheath, while also possessing the characteristics of precise positioning, stable support, aided healing, and biodegradability, thereby effectively reducing the risk of anastomotic leakage, minimizing patient suffering, and reducing surgical costs.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically a stent for preventing leakage at the rectal anastomosis. Background Technology

[0002] Rectal anastomotic leakage is a common and serious complication after rectal surgery, especially low rectal cancer surgery, with an incidence of about 3%-30%. Once it occurs, it can lead to serious consequences, such as abdominal infection, sepsis, and increased risk of reoperation, which greatly affects the patient's postoperative recovery and quality of life.

[0003] For a long time, prophylactic ileostomy has been the most common method for preventing anastomotic leakage in rectum. Its principle is to reduce fecal contamination at the anastomosis site by diverting intestinal contents outside the body, thereby lowering the risk of leakage. However, this method also has many drawbacks, such as stoma complications, psychological burden on patients, the need for a second-stage surgery to reduce leakage, and increased surgical risks and costs.

[0004] With the gradual development of existing technologies, intestinal anastomosis protection stents have been developed that utilize intestinal metal stents to support and isolate the intestinal anastomosis from surrounding intestinal tissue, preventing leakage. For example, the "Rainbow" intestinal protection stent developed by Chenno Medical uses an innovative nickel-titanium alloy. Its flexible structure can quickly conform to the intestinal wall and adapt to intestinal peristalsis. Its outer diameter design reduces the contact area with the anastomosis, providing safer postoperative protection. However, although existing technologies use a segmented structure, they rely on radial self-expansion to support the rectum. During the placement phase, a guidewire and sheath are needed to push the stent to the anastomosis, and then the sheath is pulled to release the stent's expansion support. This process requires precise position control by the surgeon. During the operation, difficulties or even failures may occur due to intestinal tortuosity, anastomotic edema, etc. Postoperative patient activity and intestinal peristalsis may cause stent displacement. If the displacement fails to cover the anastomosis, it will directly lose its leakage prevention function.

[0005] Therefore, it is necessary to propose a stent that can reduce the volume of the stent in the sheath for easy placement and installation, and precisely control the stent's position and orientation to overcome the difficulties in protecting the intestinal anastomosis caused by the complex intestinal environment, in order to prevent leakage at the rectal anastomosis. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a stent for preventing anastomotic leakage. This stent can be reduced in size during the insertion phase to facilitate placement through a sheath, while also possessing the characteristics of precise positioning, stable support, aiding healing, and biodegradability, thereby effectively reducing the risk of anastomotic leakage, reducing patient suffering, and surgical costs.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a stent for preventing leakage at the rectal anastomosis, comprising a stent body, a fixing component and a navigation component fixedly connected to the stent body, and a drug sustained-release component embedded in the inner wall of the stent body;

[0008] The stent body is used to support the intestinal wall of the rectal anastomosis through a flexible structure that can expand, fold, and contract.

[0009] A fixation component is used to position the stent body within the intestine during stent placement.

[0010] A navigation component is used to adjust the position and orientation of the support body without contact during insertion.

[0011] Drug-release components for the stepwise release of drugs that aid in the healing of rectal anastomoses.

[0012] The basic principle of the solution is as follows: the flexible folding and shrinking structure of the stent body reduces its volume during insertion and supports the intestinal wall after insertion; the fixation component is used to initially locate the stent during insertion; the non-contact control of the navigation component precisely adjusts the position and orientation of the stent to ensure coverage of the anastomosis; the drug release component releases the drug in stages to assist in anastomosis healing, and the synergistic effect of multiple components achieves the function of preventing rectal anastomotic leakage.

[0013] The beneficial effects of the basic scheme are: 1. The flexible folding and shrinking structure of the stent body can reduce the volume in the sheath during the insertion stage, making it easier to place and install, and reducing the risk of placement difficulties or failures caused by intestinal tortuosity, anastomotic edema, etc.

[0014] 2. The fixation component works in conjunction with the navigation component to provide initial positioning and precise adjustment of the stent's position and orientation, reducing stent displacement caused by postoperative patient activity and intestinal peristalsis, ensuring that the stent always covers the anastomosis, and guaranteeing leak prevention.

[0015] 3. The drug-releasing component releases the healing-aiding medication in stages, which can specifically promote anastomotic repair, reduce the risk of infection and leakage, and accelerate the patient's postoperative recovery.

[0016] 4. Each component has a clearly defined function and works in concert, improving the reliability and effectiveness of preventing rectal anastomotic leakage in terms of ease of insertion, positioning accuracy, and healing assistance.

[0017] Furthermore, the stent body includes a front shrink cap, a middle folded tube coaxially fixedly connected to the front shrink cap, a rear shrink cone coaxially fixedly connected to the middle folded tube, an isolation membrane covering the outer periphery of the middle folded tube, and a surface-modified polylactic acid-glycolic acid copolymer film covering the outer periphery of both the front shrink cap and the rear shrink cone. The polylactic acid-glycolic acid copolymer film is fixedly connected to the isolation membrane, and both the front shrink cap and the rear shrink cone are composed of a diamond-shaped woven mesh.

[0018] The beneficial effects of the basic scheme are: 1. The coaxial connection structure of the anterior contraction cap, the middle folded tube and the posterior contraction cone can be adapted to the shape of the rectal anastomosis and the surrounding intestinal tract. The radial support force is provided by the diamond woven mesh to ensure that the stent is stably attached to the intestinal wall and avoid displacement or anastomosis exposure due to unstable support.

[0019] 2. The isolation membrane around the middle folded tube can physically isolate the anastomosis from intestinal contents, reducing the irritation and contamination of the anastomosis by feces and other contaminants; the polylactic acid-glycolic acid copolymer membrane around the anterior contraction cap and posterior contraction cone further enhances the isolation effect, forming a closed protective barrier and reducing the risk of anastomotic infection and leakage.

[0020] 3. The surface-modified polylactic acid-glycolic acid copolymer membrane has good biocompatibility and frictional resistance, which can reduce intestinal mucosal irritation and rejection reaction; it can help the anterior contraction cap to be quickly fixed in the intestinal wall to achieve precise positioning.

[0021] 4. The diamond-shaped woven mesh structure provides the anterior and posterior contractile caps with a certain degree of flexibility and elasticity, adapting to morphological changes caused by intestinal peristalsis and reducing mechanical damage to the intestinal wall. The folding characteristics of the central folded tube, combined with the overall structure, allow for volume reduction during insertion through contraction, facilitating placement via the sheath and improving ease of insertion. The polylactic acid-glycolic acid copolymer membrane is a biodegradable material, and its fixed connection with the isolation membrane provides a structural basis for subsequent gradient degradation, ensuring that each component of the material gradually degrades as needed during the anastomosis healing process, avoiding removal via secondary surgery.

[0022] Furthermore, the folded tube includes several folded layers, each folded layer including a parallel skeleton with edges. The parallel skeletons with edges in the same folded layer form a polygon in the radial direction of the support body. The intersections of the parallel skeletons with edges are all fixedly connected to inclined skeletons. The other end of each inclined skeleton is fixedly connected to the intersection of the parallel skeletons with edges of the adjacent folded layer. Several folded skeletons are also fixedly connected between adjacent inclined skeletons.

[0023] The beneficial effects of the basic design are: 1. The triangular origami pattern grid and multi-layer folding structure design allow the middle fold tube to shrink and fold significantly during the insertion stage, significantly reducing the overall volume of the stent in the sheath, reducing the difficulty of passing through tortuous intestinal tubes or edematous areas of the anastomosis, and improving the ease of insertion; after release, thanks to the material properties and structural memory, it can stably stretch and restore the preset shape, ensuring effective support for the anastomosis.

[0024] 2. The radial polygon formed by the parallel skeleton of the same fold layer provides basic support strength for the middle fold tube, which can resist the radial pressure brought by intestinal peristalsis; the staggered connection of the inclined skeleton and the auxiliary design of the fold skeleton give the structure good flexibility and compliance, which can deform slightly with the movement of the intestine and reduce mechanical damage to the intestinal wall.

[0025] Furthermore, both the support body and the fixing components are made of biodegradable materials. The degradation rate of the front shrink cap and the rear shrink cone is greater than that of the middle folded tube, and the degradation rate of the isolation membrane is less than that of the polylactic acid-glycolic acid copolymer membrane.

[0026] The benefits of the basic approach are: 1. The stent body and fixation components are made of biodegradable materials, eliminating the need for surgical removal after surgery, reducing the pain, risks, and financial burden on patients due to secondary surgery, and improving the convenience and patient acceptance of the treatment process.

[0027] 2. The anterior and posterior shrinkage caps degrade at a faster rate than the middle folded tube. This allows the anterior and posterior shrinkage caps to provide stable positioning and auxiliary support in the critical early stages of anastomotic healing, gradually degrading as healing progresses. The middle folded tube, as the core structure supporting the anastomosis, degrades even more slowly and can provide effective support throughout the entire healing cycle, gradually decomposing only after the anastomosis is completely healed, ensuring a precise match between the support function and the healing process.

[0028] Furthermore, the fixing component includes several fixing rings, all of which are fixedly connected to the outer periphery of the parallel-edge skeleton, and each fixing ring is filled with hydroxypropyl methylcellulose microspheres.

[0029] The beneficial effects of the basic scheme are: 1. The fixing ring is fixedly connected to the outer periphery of the parallel skeleton of the middle folded tube, which can maintain its own shape with the support of the skeleton, while wrapping the corners of the parallel skeleton to avoid abrasion of the isolation membrane or intestinal wall.

[0030] 2. The hydroxypropyl methylcellulose microspheres filled in the fixation ring have good hydrophilicity and swelling properties. After placement, they can gradually absorb water and swell in the intestinal fluid environment, so that the fixation ring and the intestinal wall can form a tight fit. The moderate radial pressure enhances the friction between the stent and the intestinal wall, further preventing the stent from shifting due to patient activity or intestinal peristalsis after surgery, and ensuring that the stent always covers the anastomosis.

[0031] 3. After completing their fixation function, hydroxypropyl methylcellulose microspheres can be gradually absorbed or excreted by the human body as the fixation ring degrades, and will not remain in the body for a long time, thus avoiding the risk of intestinal foreign body reaction or obstruction caused by the long-term presence of the fixation structure.

[0032] Furthermore, a polyethylene glycol hydrogel coating is applied to the polylactic acid-glycolic acid copolymer film on the outer periphery of the front shrink cap.

[0033] The beneficial effects of the basic scheme are: 1. After the polyethylene glycol hydrogel coating comes into contact with the intestinal mucosa, the residual aldehyde groups on the surface can form covalent Schiff base bonds with the amino groups of the intestinal wall tissue, generating slight adhesion force in a short time and achieving initial fixation.

[0034] 2. During long-term support, the polyethylene glycol hydrogel coating can form a physical barrier on the surface of the stent, reducing the adhesion of intestinal contents, mucus or tissue to the stent surface, preventing the stent from adhering to the intestinal wall, and ensuring that the stent will not affect its positional stability or cause complications such as intestinal stenosis during the period when it plays a supporting and isolation role.

[0035] Furthermore, the navigation component includes several magnetic beads, which are uniformly embedded circumferentially into the inner walls of the front contraction cap, the middle folded tube, and the rear contraction cone. The magnetic field strength of the magnetic beads is distributed in a gradient along the axial direction of the support body. The inner walls of the front contraction cap and the rear contraction cone are also respectively embedded with tantalum metal blocks.

[0036] The beneficial effects of the basic design are: 1. Magnetic beads are uniformly embedded circumferentially in all parts of the stent body, and the magnetic field strength is distributed in a gradient along the axial direction, providing identifiable magnetic field signal characteristics for the magnetic navigation platform. The comprehensive distribution of magnetic beads in the stent body enables the magnetic navigation platform to adjust the overall posture of the stent, ensuring that the stent can adapt to the natural direction of the rectal intestinal tract after placement, closely adhering to the intestinal wall, and avoiding incomplete anastomotic coverage or excessive local compression due to posture deviation.

[0037] 2. The tantalum metal blocks embedded in the inner walls of the anterior contraction cap and the posterior contraction cone have good CT imaging properties and can form bright marks in CT images, clearly showing the position of both ends of the stent.

[0038] 3. The non-contact magnetic adjustment method reduces reliance on instruments such as guidewires and sheaths, lowering the risk of intestinal damage and bleeding caused by repeated instrument manipulation. At the same time, precise positioning and posture control improve the success rate of stent placement, especially for inexperienced operators, which helps to promote the clinical application of this technology.

[0039] Furthermore, the drug sustained-release component includes a microsphere coating, which is fixedly connected to the outer periphery of the isolation membrane. The microsphere coating includes an outer layer and an inner layer. The outer layer consists of chitosan nanospheres loaded with antibiotics, and the inner layer consists of drug-loaded microspheres loaded with growth factors from polylactic acid-glycolic acid copolymer.

[0040] The beneficial effects of the basic treatment are: the outer layer of chitosan nanospheres encapsulates antibiotics, which can be rapidly released in the early stage of stent placement to inhibit the proliferation of bacteria in the intestine and reduce the risk of anastomotic infection; the inner layer of polylactic acid-glycolic acid copolymer drug-loaded microspheres encapsulates growth factors, which have a slower degradation rate and can continuously release growth factors in the mid-to-late postoperative period to promote the repair and regeneration of anastomotic tissue, forming a progressive treatment effect of anti-infection and promoting healing.

[0041] Furthermore, it also includes a magnetic navigation platform, which comprises a data acquisition module, an analysis module, and a control module;

[0042] The acquisition module is used to acquire position and orientation data of the stent body in the patient's body through the magnetic field strength of the magnetic beads and CT images;

[0043] The analysis module is used for data image fusion processing. It generates a three-dimensional dynamic model of the stent in the patient's body through algorithms and marks the relative coordinates of the target anastomosis position.

[0044] The control module is used to adjust the position and orientation of the support body during the guided insertion stage using electromagnetic fields.

[0045] Furthermore, the acquisition module includes a Helmholtz coil array and a CT imager;

[0046] The Helmholtz coil array, employing a three-dimensional orthogonal coil array architecture, includes three main coils and three auxiliary coils, used to detect and control the positioning and attitude adjustment of the support body through electromagnetic field detection;

[0047] A CT imaging system used to capture bright images of the tantalum metal block-marked stent body within the patient's body.

[0048] The beneficial effects of the basic scheme are: 1. The Mönchs coil array adopts a three-dimensional orthogonal architecture, which can accurately detect the magnetic field strength and gradient distribution of the magnetic beads in the stent body, and realize high-precision capture of the stent's position (such as axial depth, radial offset) and orientation (such as rotation angle, degree of bending) in three-dimensional space; combined with the high-brightness imaging of the tantalum metal block mark by the CT imager, a dual verification of magnetic field signal and anatomical image is formed, further reducing positioning error.

[0049] 2. The three-dimensional orthogonal coil array can not only detect magnetic fields, but also exert a non-contact force on the magnetic beads of the stent body by adjusting the magnetic field it generates, thereby achieving multi-dimensional posture adjustment of the stent (such as fine-tuning the angle to adapt to the direction of the intestinal tract and correcting deviations to align with the anastomosis). The three sets of auxiliary coils can supplement the adjustment blind spots of the main coils, ensuring that the adjustment process is more flexible and stable, especially suitable for complex scenarios such as intestinal tortuosity.

[0050] 3. The CT imager uses the high-brightness imaging of the tantalum metal block to clearly show the anatomical position of the two ends of the stent in the body, helping the surgeon to intuitively judge the relative relationship between the stent and the anastomosis. Combined with the real-time data of the Helmholtz coil array, the analysis module can quickly generate a three-dimensional dynamic model, reducing the difficulty for the surgeon to interpret complex images, shortening the operation time, and lowering the operation threshold. Attached Figure Description

[0051] Figure 1 This is an isometric view of a stent used to prevent leakage at the rectal anastomosis in an embodiment of the present invention.

[0052] Figure 2 This is a front view of a stent used to prevent leakage at the rectal anastomosis in an embodiment of the present invention.

[0053] Figure 3 for Figure 2 Cross-sectional view along the AA direction.

[0054] Figure 4 This is a schematic diagram of a stent used to prevent leakage at the rectal anastomosis in an embodiment of the present invention, showing its support at the rectal anastomosis.

[0055] Figure 5 This is a schematic diagram of the operation of the magnetic navigation platform.

[0056] The reference numerals in the accompanying drawings include: 1. Polylactic acid-glycolic acid copolymer film; 2. Fixing ring; 3. Separating membrane; 4. Polyethylene glycol hydrogel coating; 5. Front shrink cap; 6. Magnetic bead; 7. Folded skeleton; 8. Inclined skeleton; 9. Edge parallel skeleton; 10. Hydroxypropyl methylcellulose microspheres; 11. Back shrink cone; 12. Tantalum metal block. Detailed Implementation

[0057] The following detailed description illustrates the specific implementation method:

[0058] Example 1

[0059] The basics are as follows: Figures 1 to 5 As shown: A stent for preventing leakage at the rectal anastomosis includes a stent body, a fixation component and a navigation component integrally formed on the stent body, and a drug sustained-release component embedded in the inner wall of the stent body.

[0060] The stent body, through its flexible structure of expansion, folding, and contraction, supports the intestinal wall of the rectal anastomosis. The stent body includes an anterior contraction cap 5, a centrally folded tube coaxially integrally formed from the anterior contraction cap 5, and a posterior contraction cone 11 coaxially integrally formed from the central folded tube. A separating membrane 3 covers the outer periphery of the central folded tube. Both the anterior contraction cap 5 and the posterior contraction cone 11 are covered with a surface-modified polylactic acid-glycolic acid copolymer (PLA) film, which is bonded to the separating membrane 3. Both the anterior contraction cap 5 and the posterior contraction cone 11 are composed of a diamond-shaped woven mesh. A polyethylene glycol hydrogel coating 4 is applied to the PLA film surrounding the anterior contraction cap 5.

[0061] The folded tube includes several folded layers, each folded layer including a parallel frame 9. The parallel frames 9 in the same folded layer form a polygon in the radial direction of the support body. The intersections of the parallel frames 9 are integrally formed with inclined frames 8. The other end of the inclined frames 8 is integrally formed with the intersection of the parallel frames 9 of the adjacent folded layer. Several folded frames 7 are also integrally formed between adjacent inclined frames 8.

[0062] The fixation component is used to position the stent body in the intestine during the placement of the stent body. The fixation component includes several fixation rings 2, each of which is fixedly connected to the outer periphery of the parallel skeleton 9 with its edge. Each fixation ring 2 is filled with hydroxypropyl methylcellulose microspheres 10.

[0063] Both the support body and the fixing components are made of biodegradable materials. The degradation rate of the front shrink cap 5 and the rear shrink cone 11 is greater than that of the middle folded tube, and the degradation rate of the isolation membrane 3 is less than that of the polylactic acid-glycolic acid copolymer membrane.

[0064] The navigation component is used to adjust the position and orientation of the support body without contact during the insertion of the support body. The navigation component includes several magnetic beads 6, which are uniformly embedded circumferentially into the inner walls of the front shrink cap 5, the middle folded tube and the rear shrink cone 11. The magnetic field strength of the magnetic beads 6 is gradient-distributed with the axial direction of the support body. The inner walls of the front shrink cap 5 and the rear shrink cone 11 are also respectively embedded with tantalum metal blocks 12.

[0065] A drug sustained-release component for stepwise sustained release of drugs to aid in the healing of rectal anastomoses. The drug sustained-release component includes a microsphere coating, which is bonded to the periphery of a release membrane 3. The microsphere coating includes an outer layer and an inner layer. The outer layer consists of chitosan nanospheres loaded with antibiotics, and the inner layer consists of drug-loaded microspheres loaded with growth factors from polylactic acid-glycolic acid copolymer.

[0066] It also includes a magnetic navigation platform, which comprises a data acquisition module, an analysis module, and a control module;

[0067] The acquisition module is used to acquire position and orientation data of the stent body in the patient's body through the magnetic field strength of the magnetic bead 6 and CT images. The acquisition module includes a Helmholtz coil array and a CT imager. The Helmholtz coil array adopts a three-dimensional orthogonal coil array architecture, including 3 sets of main coils and 3 sets of auxiliary coils, which are used to detect and control the positioning and orientation adjustment of the stent body through electromagnetic field detection. The CT imager is used to capture bright images of the stent body marked with tantalum metal block 12 in the patient's body.

[0068] The analysis module is used for data image fusion processing. It generates a three-dimensional dynamic model of the stent in the patient's body through algorithms and marks the relative coordinates of the target anastomosis position.

[0069] The control module is used to adjust the position and orientation of the support body during the guided insertion stage using electromagnetic fields.

[0070] The specific implementation process is as follows: Although the existing intestinal anastomosis protection stent adopts a segmented structure, it supports the rectum in a radially self-expanding manner. During the placement stage, a guidewire and sheath are needed to push the stent to the anastomosis, and then pull the sheath or even push to release the stent for expansion and support. This process requires the operator to accurately control the position. During the operation, placement may be difficult or fail due to intestinal tortuosity, anastomotic edema, etc. Postoperative patient activity and intestinal peristalsis may cause the stent to shift, losing its role in preventing leakage.

[0071] During the insertion phase, the stent body is first inserted into the intestine in a folded and retracted state through the sheath. The triangular origami-patterned grid structure of the folded tube plays a crucial role in this process. Its multi-layered folds, consisting of parallel edge skeletons 9, inclined skeletons 8, and folded skeletons 7, can significantly shrink. The folded skeleton 7 undergoes elastic deformation at its center, causing the inclined skeletons 8 to overlap along the inclined direction. Adjacent parallel edge skeletons 9 move closer together, resulting in radial contraction and significantly reducing the overall volume of the stent body. The inwardly folded inclined skeletons 8 and folded skeletons 7 form inner retaining teeth, which, in conjunction with guide wires or guide posts with retaining grooves, allow for relatively precise and stable delivery of the stent body to the target area for release. This, combined with the anterior retraction cap... The contractile properties of the rhomboid woven mesh of the anterior contraction cap 5 and the posterior contraction cone 11 allow the stent body to pass smoothly through the tortuous intestinal tract or anastomotic edema area, reducing the difficulty of placement. In this embodiment, the anterior contraction cap 5 and the posterior contraction cone 11 can be made of a blend of polybutylene adipate (PBAT) and polylactic acid (PLA). The middle folded tube is preferably made of polylactic acid-glycolic acid copolymer (PLGA, lactic acid to glycolic acid ratio 7:3). The separator 3 can be made of a composite membrane of polycaprolactone (PCL) and chitosan. The polylactic acid-glycolic acid copolymer membrane is preferably made of PLGA with low glycolic acid content (e.g., 9:1 ratio). Figure 1 , Figure 2 and Figure 3 As shown.

[0072] Meanwhile, the magnetic beads 6 embedded in the inner walls of the front contraction cap 5, the middle folded tube and the rear contraction cone 11 in the navigation component have a gradient distribution of magnetic field strength along the axial direction. Their magnetic field signals are accurately detected by the Helmholtz coil array of the magnetic control navigation platform. The tantalum metal blocks 12 in the front contraction cap 5 and the rear contraction cone 11 are highlighted by the CT imager. The data of the two are fused and processed by the analysis module to generate a three-dimensional dynamic model and mark the relative coordinates of the anastomosis.

[0073] Once the stent reaches the target position, the sheath pulls to release the stent, which then gradually expands under the stimulation of the intestinal environment. The anterior contraction cap 5 expands first. The polyethylene glycol hydrogel coating 4 on the outer periphery of the anterior contraction cap 5 forms a temporary covalent bond with the amino groups of the intestinal wall tissue through the surface aldehyde groups, generating a slight adhesive force to assist in the initial positioning. Then, the sheath releases the folded tube, and its folded layers unfold layer by layer. The radial polygon formed by the parallel skeleton 9 provides basic support strength. The hydroxypropyl methylcellulose microspheres 10 filled in the fixing ring 2 connected to the outer periphery of the parallel skeleton 9 absorb water and expand in the intestinal fluid, so that the fixing ring 2 fits tightly with the intestinal wall. The friction is enhanced by moderate radial pressure to prevent the stent body from shifting due to patient movement or intestinal peristalsis. The misaligned connection of the inclined skeleton 8 and the folded skeleton 7 give the structure flexibility, so that it can conform to the shape of the intestinal wall and resist the radial pressure of intestinal peristalsis, forming stable support. Finally, the rhomboid woven mesh of the posterior contraction cone 11 unfolds and assists in fixing the position of the two ends of the stent body through radial force. Subsequently, during the long-term support process, the polyethylene glycol hydrogel coating 4 forms a physical barrier to prevent the stent body from adhering to the intestinal wall for a long time and ensure positional stability.

[0074] In the support phase, the various components of the stent work together to construct a protective and healing environment. The isolation membrane 3 on the periphery of the central folded tube is fixedly connected to the surface-modified polylactic acid-glycolic acid copolymer membrane on the periphery of the anterior and posterior contraction cones 11, forming a closed barrier that physically isolates the anastomosis from intestinal contents, reducing the risk of fecal contamination. The biocompatibility of the polylactic acid-glycolic acid copolymer membrane reduces intestinal wall irritation, and the difference in degradation rate between it and the isolation membrane 3 ensures that the isolation function continues until the later stage of anastomosis healing. The drug-release component gradually takes effect in this stage. In the microsphere coating connected to the periphery of the isolation membrane 3, the outer layer of chitosan nanospheres loaded with antibiotics first releases the drug, rapidly inhibiting intestinal bacterial growth and reducing the risk of infection; the inner layer of polylactic acid-glycolic acid copolymer drug-loaded microspheres loaded with growth factors continuously releases growth factors as the material slowly degrades, promoting anastomotic tissue repair and regeneration, forming a progressive therapeutic effect of anti-infection and promoting healing. Figure 4 As shown.

[0075] During stent placement, the navigation component adjusts the precise position of the stent via the control module of the magnetic navigation platform. The gradient magnetic field of the magnetic bead 6 and the CT imaging of the tantalum metal block 12 continuously provide dual positioning signals. Based on this, the control module applies force to the magnetic bead 6 through the electromagnetic field formed by the Helmholtz coil array, non-contactly adjusting the position and orientation of the stent to ensure precise alignment with the anastomosis. Figure 5 As shown.

[0076] As the anastomosis gradually heals, the biodegradable material of the stent body degrades according to a preset gradient. The anterior shrinkage cap 5 and the posterior shrinkage cone 11 degrade at a faster rate and gradually decompose after completing the initial positioning assistance. The middle folded tube, as the core support structure, degrades more slowly and continues to provide support until the anastomosis is completely healed. In the end, all structural components degrade into harmless products that are absorbed by the human body, while non-degradable small components, such as magnetic beads, are naturally excreted and excreted without the need for a second surgery to remove them.

[0077] In summary, this patent achieves convenient insertion through a folding structure, ensures precise positioning and stable support through magnetic navigation and fixation components, creates a favorable healing environment through an isolation barrier and stepwise drug release, and avoids secondary trauma by combining gradient biodegradable materials. It comprehensively solves the problems of difficult insertion, inaccurate positioning, and the need for secondary surgery in traditional stents, effectively reduces the risk of rectal anastomosis leakage, and improves the quality of postoperative recovery for patients.

[0078] Specific experimental procedure: I. Experimental objective

[0079] 1. To verify the advantages of the stent of the present invention in terms of ease of insertion, postoperative displacement rate, leakage prevention effect, drug sustained release performance and degradation compatibility.

[0080] 2. Quantitatively compare the clinical limitations of traditional metal stents (using the "Rainbow" intestinal protection stent as a reference).

[0081] II. Experimental Materials

[0082] 1. Experimental group: 15 groups of the biodegradable magnetic navigation stent of the present invention; Control group: 15 groups of "Rainbow" intestinal protection stent with nickel-titanium alloy self-expanding structure.

[0083] 2. Testing equipment: controllable sheath, magnetic navigation platform, intestinal peristalsis simulator.

[0084] 3. Simulated environment: 10 groups of isolated porcine intestinal tube models with preserved intestinal curvature and mucus layer after being soaked in artificial intestinal fluid, and 10 groups of SD rats weighing 250±20g.

[0085] III. Experimental Procedure

[0086] 1. Placement convenience test: Both sets of stents were retracted and inserted into an 8mm diameter sheath, and pushed to the target anastomosis (marked point) in a simulated intestinal tract (including 3 bends ≥90°). The placement time, number of operations, and success rate of passing through bends were recorded.

[0087] Magnetic navigation assistance: The experimental group used a magnetic control platform to adjust the attitude in real time, while the control group relied on manual adjustment via guidewire.

[0088] 2. Postoperative displacement and support stability: After stent release, simulated intestinal peristalsis (the robotic arm periodically squeezes the intestinal tract at a frequency of 0.5 Hz) was used to measure the stent displacement distance and the rate of change in anastomotic coverage area over 24 hours (CT scan reconstruction).

[0089] 3. Leakage prevention effect: A standard 2mm defect is created at the anastomosis site, and after the stent is covered, simulated fecal fluid (containing fluorescently labeled E. coli) is injected. The leakage rate and bacterial infection amount (colon count per unit area) are tested after 72 hours.

[0090] 4. Degradation and tissue compatibility: The scaffold was implanted into the rat colon, and samples were taken periodically for observation. The scaffold degradation cycle, anastomosis healing rate (histological score), and inflammatory response (IL-6 level) were recorded.

[0091] IV. Experimental Results

[0092] As shown in the table below:

[0093] Table 1. Experimental Data

[0094] Test metrics experimental group control group Improvement effect Insertion time (min) 3.2±0.8 8.5±1.6 Reduced by 62.4% Success rate through bending 100% 73.3% An increase of 26.7% 24-hour displacement distance (mm) 0.7±0.3 4.2±1.1 Reduced by 83.3% Anastomosis coverage maintenance rate 98.5±1.2% 82.7±5.3% An increase of 15.8% 72h leakage rate 0% 13.5% Completely leak-proof Bacterial infection load (CFU / cm²) 1.2×10³±0.3×10³ <![CDATA[1.1×10 5 ±0.4×10 5 ]]> Reduced by 99% Degradation cycle (days) Front / back cap: 18±2; center tube: 50±5 Surgical removal is required. No need for a second surgery Anastomosis healing rate (day 7) 92.3±3.1% 68.7±6.9% An increase of 23.6%

[0095] Note: Data are expressed as mean ± standard deviation; healing rate = percentage of samples with histological score ≥ 8 (out of 10).

[0096] V. Experimental Conclusions

[0097] Insertion performance: The folded structure in the experimental group reduced the volume inside the sheath by 42%, and with the real-time attitude adjustment of magnetic navigation, the insertion time was shortened by 62%, and the success rate of passing through complex intestinal folds reached 100% (compared to only 73% in the control group).

[0098] Anti-displacement mechanism: The expansion anchoring of the fixed ring 2 and magnetic navigation positioning keep the displacement distance of the experimental group within 1mm (control group > 4mm), and the anastomosis coverage area maintenance rate > 98%, avoiding the leakage failure caused by displacement of traditional stents.

[0099] Promoting active healing: Outer layer antibiotics: 85% release rate within 24 hours, infection level reduced to 1% of the control group; Inner layer growth factors: sustained release period of 28 days, anastomotic healing rate increased by 23.6% on day 7.

[0100] Degradation safety: The gradient degradation design (pre-degradation of the anterior / posterior cap, followed by the middle tube support and final degradation of the isolation membrane) perfectly matches the healing cycle, eliminating the need for a second surgery for removal and resulting in no chronic inflammatory response (IL-6 level is only 1 / 3 of the control group).

[0101] Example 2

[0102] Unlike the embodiments described above, the stent body can be shaped into different forms by using a segmented weaving process, including the anterior contraction cap 5, the middle folded tube, and the posterior contraction cone 11, without affecting their flexible support. The shape of the stent body components can also be reshaped to fit the characteristics of the gastrointestinal anastomosis. The anterior contraction cap 5 is designed as a rounded-edge trumpet shape (the anterior contraction cap 5 of the stent body used in the intestine is hemispherical), with a trumpet opening diameter slightly larger than the intestinal diameter, facilitating a close fit to the wider interface connecting the stomach and intestine. The middle folded tube is a spindle shape with a slightly thicker middle section (the middle folded tube of the stent body used in the intestine is a cylindrical shape with a uniform diameter), with smooth transitions at both ends connecting the anterior contraction cap 5 and the posterior contraction cone 11, adapting to the natural changes in the intestinal diameter around the gastrointestinal anastomosis. The posterior contraction cone 11 maintains its cone shape but with a gentler taper and a rounded surface to reduce mechanical stimulation to the distal intestine.

[0103] During insertion, the stent body is folded and retracted and then inserted into the gastrointestinal anastomosis area through the sheath. The trumpet-shaped anterior contraction cap 5 folds and flattens, while the triangular origami pattern grid of the spindle-shaped middle folded tube shrinks significantly. Combined with the gentle conical contraction of the posterior contraction cone 11, the overall volume is significantly reduced, allowing it to pass smoothly through the connection channel between the stomach and intestines, reducing insertion resistance caused by gastrointestinal tortuosity and anastomotic edema. As the sheath is pulled to release the stent body, the navigation component is activated. The magnetic field signals generated by the magnetic beads 6 on the inner walls of the anterior contraction cap 5, the middle folded tube, and the posterior contraction cone 11 are precisely captured by the Helmholtz coil array of the magnetic control navigation platform. The tantalum metal block 12 at the edge of the flared opening of the anterior contraction cap 5 and the end of the posterior contraction cone 11 are highlighted by the CT imager. The data from both are fused by the analysis module to generate a three-dimensional dynamic model, marking the relative coordinates of the gastrointestinal anastomosis. The control module uses the magnetic field to act on the magnetic beads 6 to adjust the position and orientation of the stent body without contact, ensuring that the flared anterior contraction cap 5 is aligned with the gastric side interface and that the middle section of the middle folded tube covers the core area of ​​the anastomosis. Figure 1 and Figure 2 As shown.

[0104] As the sheath is pulled, the trumpet-shaped anterior contraction cap 5 unfolds, its edges fitting the junction between the stomach and intestine. Its diamond-shaped woven mesh provides radial support, preventing gaps from forming on the gastric side edge of the anastomosis due to uneven pressure. The polyethylene glycol hydrogel coating 4 on the outer periphery of the anterior contraction cap 5 first forms temporary covalent bonds with the amino groups of the gastric wall tissue through surface aldehyde groups, aiding in initial positioning. Subsequently, it forms a smooth physical barrier, preventing long-term adhesion to the gastric wall and reducing the erosion of the stent body surface by gastric juice. The folded layers of the spindle-shaped folded tube unfold, and the radial polygon formed by the parallel edges of the skeleton 9 forms in the middle section. The stronger support, combined with the misaligned connection of the inclined skeleton 8 and the flexibility of the folded skeleton 7, allows it to closely fit the intestinal wall morphology of the anastomosis area, resisting the axial thrust caused by gastric peristalsis. Within the fixing ring 2 (which is more densely distributed in the middle section of the spindle shape) connected to the outer periphery of the parallel skeleton 9 of the middle folded tube, hydroxypropyl methylcellulose microspheres 10 absorb water and swell in the gastrointestinal fluid, making the fixing ring 2 closely fit the intestinal wall. The friction is enhanced by moderate radial pressure, which counteracts the tendency of the stent body to shift due to gastric peristalsis. The posterior contraction cone 11 unfolds smoothly, assisting in fixing the distal position of the stent body.

[0105] During the subsequent prolonged support process, the isolation membrane 3 on the outer periphery of the folded tube unfolds in a spindle shape, tightly connecting with the surface-modified polylactic acid-glycolic acid copolymer membranes on the outer periphery of the anterior contraction cap 5 and the posterior contraction cone 11, forming a closed barrier to isolate the anastomosis from gastric juice and intestinal contents, reducing the irritation and contamination of the anastomosis by digestive juices. The biocompatibility of the polylactic acid-glycolic acid copolymer membrane reduces gastrointestinal mucosal irritation, and the difference in degradation rate between it and the isolation membrane 3 ensures that the isolation function continues until the anastomosis heals. The drug-releasing component plays a targeted role. In the microsphere coating on the outer periphery of the isolation membrane 3, the outer layer of chitosan nanospheres loaded with antibiotics, due to their acid-resistant design, stably releases antibiotics in the gastric juice environment, inhibiting gastric flora infection. The inner layer of polylactic acid-glycolic acid copolymer drug-loaded microspheres loaded with growth factors slowly degrades with the material, continuously releasing growth factors to promote anastomotic tissue repair, combined with... Figure 3 and Figure 4 As shown.

[0106] The navigation components can maintain precise positioning at all times via a magnetically controlled navigation platform, ensuring that the stent body always covers the anastomosis. As the anastomosis heals, the biodegradable materials degrade according to a preset gradient. The posterior contraction cone 11 degrades faster, while the anterior contraction cap 5 and the spindle-shaped folded tube, as the core support and protective structure, degrade more slowly, providing continuous support until the anastomosis is completely healed. Ultimately, all components degrade into harmless products, eliminating the need for a second surgery. Figure 5 As shown.

[0107] In summary, by adapting the shape design to the gastrointestinal anastomosis site and coordinating with the original functional components, it achieves an integrated effect of convenient insertion, precise positioning, stable support, isolation and protection, and drug-assisted healing. It can effectively adapt to the anatomical characteristics and physiological activities of the gastrointestinal tract and reduce the risk of gastrointestinal anastomosis leakage.

[0108] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0109] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A stent for preventing leakage of a rectal anastomosis, characterized by: The stent body includes a fixation component and a navigation component fixedly connected to it, and a drug release component is embedded in the inner wall of the stent body. The stent body is used to support the intestinal wall of the rectal anastomosis through a flexible structure that can expand, fold, and contract. The support body includes a front shrink cap (5), a middle folded tube is coaxially fixed to the front shrink cap (5), a rear shrink cone (11) is coaxially fixed to the middle folded tube, an isolation membrane (3) is wrapped around the middle folded tube, and a surface-modified polylactic acid-glycolic acid copolymer film is wrapped around the front shrink cap (5) and the rear shrink cone (11). The polylactic acid-glycolic acid copolymer film is fixedly connected to the isolation membrane (3), and the front shrink cap (5) and the rear shrink cone (11) are both composed of a diamond woven mesh. The folded tube includes several folded layers, each including a parallel frame (9). The parallel frames (9) in the same folded layer form a polygon in the radial direction of the support body. The intersections of the parallel frames (9) are all fixedly connected to inclined frames (8). The other end of the inclined frames (8) is fixedly connected to the intersection of the parallel frames (9) of the adjacent folded layers. Several folded frames (7) are also fixedly connected between the adjacent inclined frames (8). A fixation component is used to position the stent body within the intestine during stent placement. The fixing component includes several fixing rings (2), all of which are fixedly connected to the outer periphery of the parallel skeleton (9) with edges, and each fixing ring (2) is filled with hydroxypropyl methylcellulose microspheres (10). A navigation component is used to adjust the position and orientation of the support body without contact during insertion. The navigation component includes several magnetic beads (6), which are uniformly embedded circumferentially into the inner walls of the front contraction cap (5), the middle folded tube and the rear contraction cone (11). The magnetic field strength of the magnetic beads (6) is distributed in a gradient with the axial direction of the support body. The inner walls of the front contraction cap (5) and the rear contraction cone (11) are also respectively embedded with tantalum metal blocks (12). Drug-release components for the stepwise release of drugs that aid in the healing of rectal anastomoses.

2. The stent for preventing leakage of a rectal anastomosis according to claim 1, characterized by: The support body and fixing components are all made of biodegradable materials. The degradation rate of the front shrink cap (5) and the rear shrink cone (11) is greater than that of the middle folded tube, and the degradation rate of the isolation membrane (3) is less than that of the polylactic acid-glycolic acid copolymer membrane.

3. The stent for preventing leakage of a rectal anastomosis according to claim 1, wherein: The polylactic acid-glycolic acid copolymer film on the outer periphery of the front shrink cap (5) is coated with a polyethylene glycol hydrogel coating (4).

4. The stent for preventing leakage of a rectal anastomosis according to claim 3, characterized by: The drug sustained-release component includes a microsphere coating, which is fixedly connected to the periphery of the isolation membrane (3). The microsphere coating includes an outer layer and an inner layer. The outer layer is a chitosan nanosphere loaded with antibiotics, and the inner layer is a polylactic acid-glycolic acid copolymer drug-loaded microsphere loaded with growth factors.

5. The stent for preventing leakage at the rectal anastomosis according to claim 4, characterized in that: It also includes a magnetic navigation platform, which comprises a data acquisition module, an analysis module, and a control module; The acquisition module is used to acquire the position and orientation data of the stent body in the patient's body through the magnetic field strength of the magnetic bead (6) and CT images; The analysis module is used for data image fusion processing. It generates a three-dimensional dynamic model of the stent in the patient's body through algorithms and marks the relative coordinates of the target anastomosis position. The control module is used to adjust the position and orientation of the support body during the guided insertion stage using electromagnetic fields.

6. The stent for preventing leakage of a rectal anastomosis according to claim 5, characterized by: The acquisition module includes a Helmholtz coil array and a CT imager; The Helmholtz coil array, employing a three-dimensional orthogonal coil array architecture, includes three main coils and three auxiliary coils, used to detect and control the positioning and attitude adjustment of the support body through electromagnetic field detection; A CT imager was used to capture a bright image of the scaffold body marked with a tantalum metal block (12) in the patient's body.

Images