Recoverable drug-loading stent

Abstract

The utility model discloses a recoverable drug-loading stent which comprises a self-expanding stent and a pushing rod, the self-expanding stent is coated with drug, the pushing rod is connected with and drives the self-expanding stent to move, the self-expanding stent comprises a bare stent and a keel, the bare stent comprises a plurality of mesh units, the mesh units are sequentially connected to form a cylindrical structure with the side wall being in a fish scale shape and hollowed out, and the keel is connected with the bare stent. The bare stent can be actively or passively expanded and compressed in the radial direction of the bare stent, the end portion of the end, close to the pushing rod, of the bare stent is designed to be an inclined face opening, the keel is in a rod shape and connected to the bare stent, and the length direction of the keel is parallel to the length direction of the bare stent. The bare stent is of a fish scale-shaped porous structure, has enough radial force, is reliably attached to blood vessels, and meanwhile has good conveying performance, the radial force is enhanced through the regular circulation design of the net structure, and the deformation resistance of the near end can be enhanced through the keel design.

Description

Technical Field

[0001] The utility model belongs to the technical field of medical devices, in particular to a recyclable drug-loaded stent. Background Art

[0002] Coronary artery atherosclerosis is a common cardiovascular disease that seriously affects people's health. Unstable angina or myocardial infarction is an important cause of death from ischemic heart disease. Percutaneous coronary intervention stent implantation and recent drug-assisted balloon therapy are effective treatments for coronary heart disease. However, in-stent restenosis and re-implantation of stents are bottlenecks in current clinical treatment.

[0003] Drug-eluting balloons are effective strategies for interventional treatment. At present, drug-eluting balloons are coated with rapamycin derivatives and paclitaxel. Although drug-eluting balloons avoid permanent stent implantation, they also have many problems. For example, due to the dissection and hematoma in the coronary artery wall that may occur during the operation, only remedial stent treatment can be adopted. Drug-eluting balloons use different drug coatings. The paclitaxel coating has a fast absorption rate, but it takes nearly 60 seconds to keep the balloon expanded to reduce the dissection or hematoma. Longer balloon expansion time will hinder normal blood flow. Rapamycin balloons are a potential drug-eluting balloon that may better improve the treatment effect. Due to the poor tissue affinity of rapamycin, a longer balloon expansion time is required, which limits the application of this type of drug-eluting balloons. Drug-eluting balloons can quickly and evenly deliver anti-proliferative drugs to the blood vessel wall without leaving permanent implants. Currently, they are used for in-stent restenosis, primary lesions of small coronary vessels, and peripheral vascular lesions. However, there are many shortcomings, such as vascular dissection, hematoma, elastic retraction, etc., which may lead to acute complications or affect long-term prognosis, and more adequate lesion pretreatment is needed. Currently, paclitaxel is a commonly used drug balloon coating due to its high tissue affinity and fast release rate. Rapamycin derivative drug balloons theoretically have better therapeutic effects, but have poor tissue affinity and require longer vascular wall adhesion time to promote drug release and absorption. Existing balloon drug-loading release methods limit the use of such drugs.

[0004] Drug-coated stents are conventional bare metal stents that have drugs coated on the stent surface by appropriate methods. The drugs are released under blood flushing and act locally. Current research focuses on stent materials, structural design, coating drugs, and coating processes. Coating drugs are divided into five categories based on their pharmacological effects: antithrombotic drugs, anti-inflammatory drugs, anti-vascular smooth muscle proliferation drugs, anti-vascular smooth muscle migration drugs, and drugs that promote endothelial cell healing. Currently, clinical applications are mainly based on anti-vascular smooth muscle proliferation drugs, such as rapamycin derivatives and paclitaxel. Cocktail-style mixed drug coatings may also appear in the future.

[0005] The design of the drug-coated adaptive stent is different from the current classic DES in that when the drug coating of the polymer film is degraded after 6 months, the buckles between the steel beams of the stent are also opened, thereby enhancing the compliance of the stent in the blood vessel after 6 months. It will not affect the contraction and relaxation of the artery due to blood flow and has potential clinical superiority.

[0006] The permanent implant stent system is mainly a balloon-expandable stent system, which includes a stent and a delivery system. The stent is compressed and loaded on the delivery system balloon. When the stent is delivered to the lesion site, the balloon is pressurized and expanded to release the stent, and the stent remains permanently in the human body. There are many complications of permanent stent implantation, such as late stent thrombosis, late stent poor adhesion, late catch-up phenomenon, restenosis, stent fatigue fracture, and long-term poor endothelial coverage. Covering an ultra-long blood vessel segment with a stent will also affect the endothelial function of the vessel.

[0007] Bioresorbable stents are stent systems that use polymers such as polylactic acid as the matrix. After three stages of blood supply reconstruction, stent degradation and absorption, and vascular repair, the purpose of intervention without implantation is achieved. At present, the domestically produced NeoVas biodegradable stent is used in China. Metal biodegradable stents are metal stents or iron-based stents based on magnesium alloys, with rapamycin derivative coatings. While maintaining a 12-month degradation time, they also take into account radial support durability. Biodegradable stents still have defects such as late stent thrombosis, vascular wall calcification, insufficient local support, and strict requirements for stent storage and transportation.

[0008] The self-expanding stent is a superelastic stent made of a thin-walled nickel-titanium alloy tube that is precisely engraved by laser. It reaches the lesion through a compression-grip delivery catheter, and after the fixation is released, it expands to allow blood to flow freely and supports the lesion. The new generation of drug-coated self-expanding stents have completed clinical trials and have shown certain advantages, but they have not shown the advantages of traditional ball-expandable stents in operation. The main reason is that the operation is not simple.

[0009] Thrombectomy stents are mainly used in intracranial blood vessels. Neurothrombectomy stents are self-expanding stents that can be delivered through a microcatheter into acutely occluded intracranial large vessels. The device is designed to engage the thrombus that causes large vessel occlusion and remove it from the circulation, thereby restoring intracranial blood flow. However, it has poor radial support and is not guided by a guidewire, making it unsuitable for coronary artery treatment.

[0010] It is not difficult to see from the above that the interventional medical devices required for the clinical drug treatment of coronary heart disease need to solve the following technical problems: (1) Ensure that the drug delivery system enters the guide catheter and blood vessels along the guidewire, and that the guidewire can be retained in the central cavity of the drug delivery system; (2) The self-expanding stent structure and material design ensure safe release and recovery; (3) The self-expanding stent structure and material design ensure appropriate radial support force; (4) The stent coating is safe and reliable and will not fall off or break during operation; (5) The drug coating is reliably adhered, does not fall off, and does not adhere to the outer tube; (6) The drug coating has appropriate tissue affinity, which is conducive to release and absorption while avoiding loss; (7) After the coated stent is released, the central cavity can enter the intracavitary imaging catheter along the guidewire; (8) In special cases, after the coated stent is released, other types of balloons or stents can enter the cavity to treat distal lesions.

[0011] CN113599032A discloses a retractable drug-coated stent, comprising: an inner tube, a middle tube and an outer tube, wherein the proximal ends of the inner tube, the middle tube and the outer tube are connected with a pushing device; the distal end of the inner tube has a tip; a self-expanding stent, the surface of which has spikes, the surface of which is provided with a drug coating, and the self-expanding stent is connected to the distal end of the middle tube; the self-expanding stent has a retracted state, and the self-expanding stent also has an expanded state. The retractable drug-coated stent provided by the present invention has spikes on its surface, which can penetrate calcified lesions and the vascular endothelium, enter the vascular tunica media and adventitia, perform deep drug administration, and improve drug utilization; this drug-coated stent will not remain in the body, and at the same time, this method will not block blood flow, and can also control the drug administration time, and the entire operation process is simple and easy to operate. However, when the spikes of this type of self-expanding stent penetrate calcified lesions, if the spikes are too hard, they are easy to scratch the blood vessels when the stent is released and withdrawn; if the spikes are not hard enough, it is difficult to penetrate the calcified lesions and the vascular intima, enter the vascular media and intima, and perform deep drug delivery. The direction of the spikes on the stent surface is perpendicular to the length of the stent. During the release of the stent along the length direction, if the target blood vessel is severely calcified, it is difficult for the spikes to penetrate the calcified lesions, and there is even a risk of the spikes falling off. In addition, the spike structure has the risk of scratching the blood vessels, so it is not suitable for the treatment of coronary artery stenosis. Its structure limits the application of this stent. Utility Model Content

[0012] In view of the above-mentioned problems existing in the prior art, the purpose of the utility model is to provide a recyclable drug-loaded stent. The bare stent has a fish-scale porous structure, has sufficient radial force, can reliably fit the blood vessel, and has good delivery performance, can smoothly enter and exit the outer tube without damaging the blood vessel; the multiple mesh units of the main body form a coaxial structure in the length direction and the circumferential direction, to ensure that the stent can be reliably expanded in the blood vessel and has sufficient supporting force, reducing the defect of polymer membrane invagination; so that the drug coating on the stent is better attached to the blood vessel. The stent is easy to enter the outer tube and reduce surgical risks. The keel design can enhance the ability of the proximal end to resist deformation and improve the supporting force of the bare stent, while not affecting the overall flexibility and wall adhesion of the bare stent, making the self-expanding stent easier to be pushed by the push rod.

[0013] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0014] A recyclable drug-loaded stent comprises a self-expanding stent and a push rod, wherein the self-expanding stent is coated with drugs, the push rod is connected to and drives the self-expanding stent to move, the self-expanding stent comprises a bare stent and a keel, the bare stent comprises a plurality of mesh units, the plurality of mesh units are sequentially connected to form a cylindrical structure with a hollow fish-scale side wall, the bare stent can actively or passively expand and compress along its radial direction, one end of the bare stent close to the push rod is designed as an inclined opening, the keel is rod-shaped, the keel is connected to the bare stent, and the length direction of the keel is parallel to the length direction of the bare stent.

[0015] As a further improvement of the above technical solution:

[0016] The bare stent is divided into a proximal end, a distal end and a main body along its length direction. The main body is cylindrical and is located between the proximal end and the distal end. The proximal end is closer to the push rod than the distal end, and the end of the proximal end is designed to be an inclined opening.

[0017] The mesh unit is formed by four unit rods connected end to end in sequence to form a parallelogram-like shape, and the unit rods of adjacent mesh units are tightly fitted and connected.

[0018] The four unit rods forming a mesh unit include two types, namely a first unit rod and a second unit rod. The length of the first unit rod is greater than that of the second unit rod. The two first unit rods are two opposite sides of the parallelogram, and the two second unit rods are the other two opposite sides of the parallelogram. In the main body, the angle between the first unit rod and one second unit rod of a mesh unit is 40° to 60°, and the angle between the first unit rod and another second unit rod is 120° to 140°.

[0019] The multiple mesh units of the main body are arranged in multiple rows and columns after being unfolded. The arrangement direction of a row of mesh units is parallel to the direction of the center line of the main body, the arrangement direction of a column of mesh units is not perpendicular to the direction of the center line of the main body, and the mesh units of two adjacent columns are staggered.

[0020] The self-expanding stent also includes an inner coating and an outer coating. The inner surface of the bare stent is connected to the inner coating, and the outer surface is connected to the outer coating. Drugs are coated on the outer surface of the outer coating to form a drug coating.

[0021] The self-expanding stent further comprises a stent distal end display and a stent proximal end display. The stent distal end display is installed at the end of the distal portion away from the main body, and the stent proximal end display is installed at the end of the proximal portion away from the main body.

[0022] The distal end of the stent is visualized as a spring-like shape made of wound filaments.

[0023] The push rod is a rod-shaped structure with a variable diameter, and the outer diameter of the push rod increases sequentially from the end close to the self-expanding stent toward the end far from the self-expanding stent.

[0024] When in use, the drug-loaded stent cooperates with a balloon and an outer tube, the balloon can be inflated, the balloon, the self-expanding stent and the outer tube are sleeved in sequence from the inside to the outside, and the push rod is also located in the outer tube.

[0025] The beneficial effects of the utility model are:

[0026] (1) The bare stent has a fish scale-like porous structure, and the porous surface serves as a carrier for the drug coating. The two are combined to obtain a drug-loaded stent. The drug-loaded stent can be recycled after use. The stent has sufficient radial force and can reliably fit the blood vessel. At the same time, it has good delivery performance and can smoothly enter and exit the outer tube without damaging the blood vessel. The fish scale structure can achieve a smaller rod width, wall thickness and smaller mesh unit area, which is beneficial to improving the flexibility and pushability of the stent. It can also increase the contact area between the bare stent and the polymer film (inner coating and outer coating), and reducing the wall thickness of the bare stent can reduce the extreme difference between the rod width and the polymer film thickness, so that the polymer film is closer to the outer surface of the stent, so that the drug coating on the polymer film is better in contact with the blood vessel, thereby improving the drug absorption rate of the target blood vessel. The fish scale shape is arranged in sequence, which can effectively reduce the friction between the instruments, and help to improve the conductivity of the stent in the blood vessel and the flexibility when passing through curved blood vessels. The drug-loaded stent can be used for coronary arteries and can also be applied to peripheral blood vessels.

[0027] (2) The multiple mesh units of the main body form a coaxial structure in the length direction and the circumferential direction. The regular cyclic design of the mesh structure strengthens the radial force, ensuring that the stent can be reliably expanded in the blood vessel and has sufficient supporting force. The mesh units of the main body are arranged more evenly, making the inner coating and outer coating on the surface of the bare stent smoother and reducing the defect of the polymer film invagination. The mesh units of the main body are mesh structures with uniform area, which can provide uniform radial force in the circumferential direction, so that the stent has better wall adhesion performance in the blood vessel, thereby making the drug coating on the stent better adhere to the blood vessel.

[0028] (3) The proximal and distal ends are designed with oblique openings, and the areas of the multiple mesh units of the proximal and distal ends are different and smaller than the area of ​​the mesh units of the main body. The above combination makes the radial expansion force of the proximal and distal ends smaller than the radial expansion force of the main body, making it easier for the stent to enter the outer tube and reducing surgical risks.

[0029] (4) The keel design can enhance the ability of the proximal end to resist deformation and improve the supporting force of the bare stent, while not affecting the overall flexibility and wall adhesion of the bare stent, making the self-expanding stent easier to be pushed by the push rod.

[0030] (5) The drug-loaded stent can be pre-installed in an outer tube in vitro. The drug-loaded stent can be fixed in the outer tube by the pressure between the drug-loaded stent and the outer tube. In the absence of external pulling force, the two will not undergo relative displacement. By relying on various imaging techniques, the position of the stent can be determined in vitro for assembly. At the same time, various instruments can be positioned during the operation without repeated imaging to confirm the position of the instrument, thereby achieving precise positioning and release of the stent. The operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the coordination structure of the drug-loaded stent, the balloon and the outer tube when the mesh units of the utility model are arranged without dislocation.

[0032] Figure 2 It is a schematic diagram of the end surface structure of the self-expanding stent of the utility model.

[0033] Figure 3 It is a schematic diagram of the structure of the drug-carrying stent in which the mesh units of the utility model are arranged without dislocation.

[0034] Figure 4 The utility model is a schematic diagram of the cross-sectional structure of the self-expanding stent passing through the keel.

[0035] Figure 5 The utility model is a schematic diagram of a bare stent in which mesh units are arranged without dislocation, a stent distal end development and a stent proximal end development structure.

[0036] Figure 6 and Figure 7 It is a schematic diagram of the unfolded state of a bare stent in which mesh units of the utility model are staggered mesh units.

[0037] Figure 8 The utility model is a schematic structural diagram of three adjacent mesh units in which the mesh units are staggered arrangement mesh units.

[0038] Fig. 9 The utility model is a schematic diagram of the structure of a self-expanding stent when the mesh units of the utility model are arranged without dislocation and the keel length and the proximal end length of the mesh units are the same.

[0039] Fig.10 It is a schematic diagram of the structure of the self-expanding stent when the mesh units of the utility model are arranged without dislocation and the keel length of the mesh units is greater than the length of the proximal end portion.

[0040] Fig.11 yes Fig. 9 Schematic diagram of the local structure.

[0041] Fig.12 The utility model is a force diagram of a mesh unit in which the mesh unit is arranged in a staggered manner and enters an outer tube under the action of an external force when the mesh unit is stationary.

[0042] Fig.13 The utility model is a force diagram of a mesh unit in which the mesh unit is arranged in a staggered manner and moves when the mesh unit enters an outer tube under the action of an external force.

[0043] Fig.14 It is a schematic diagram of the structure of the U-shaped rods connecting the mesh units of the utility model.

[0044] Fig.15 It is a schematic diagram of the mesh unit structure in which the mesh units are connected by solid S-shaped rods of the utility model.

[0045] Fig.16 It is a schematic diagram of the mesh unit structure in which the mesh units are connected by X-shaped rods in the utility model. DETAILED DESCRIPTION

[0046] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0047] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0048] A retrievable drug-eluting stent, such as Figures 1 to 11 As shown, it includes a self-expanding stent 1, a stent distal end imaging 2, a stent proximal end imaging 3 and a pushing rod 4. The self-expanding stent 1 and the pushing rod 4 are connected.

[0049] The self-expanding stent 1 comprises a bare stent 11, a keel 12, an inner coating 13, an outer coating 14 and a drug coating 15. The bare stent 11 is a cylindrical structure with a hollow side wall. Figure 2 As shown, an inner coating film 13 is connected to the inner surface of the bare stent 11 , and an outer coating film 14 is connected to the outer surface. Drugs are coated on the outer surface of the outer coating film 14 to form a drug coating 15 .

[0050] The bare stent 11 is a porous structure, and the bare stent 11 includes a plurality of mesh units 111, and the plurality of mesh units 111 are sequentially connected to form a fish-scale hollow side wall of the bare stent 11. The bare stent 11 can be actively or passively expanded and compressed along its radial direction, and the radial direction of the bare stent 11 is perpendicular to the length direction or axial direction of the bare stent 11. Due to the expandability and compression of the bare stent 11, when the bare stent 11 expands along its radial direction, the circumference of the bare stent 11 increases, and the cross-sectional area formed by the circumference increases, and the self-expanding stent 1 can expand to the target blood vessel and adhere to the blood vessel wall, so that the drug in the drug coating 15 on the self-expanding stent 1 is released into the blood vessel wall; when the self-expanding stent 1 contracts along its radial direction, the circumference of the self-expanding stent 1 decreases, and the cross-sectional area formed by the circumference decreases, and the self-expanding stent 1 can contract to break away from the contact with the blood vessel, so as to smoothly remove the self-expanding stent 1 from the blood vessel.

[0051] The inner coating film 13 and the outer coating film 14 are sealed together on both sides of the bare stent 11 by hot melting method using a high temperature resistant metal core rod.

[0052] The inner coating 13 and the outer coating 14 may have multiple layers, preferably, the inner coating 13 has 1 to 10 layers, and the outer coating 14 has 2 to 12 layers. It should be noted that the drug coating 15 is only coated on the outer surface of the outermost outer coating 14 .

[0053] In this embodiment, the inner coating film 13 and the outer coating film 14 are made of ePTFE material.

[0054] The drug coating 15 may be one or more layers, and the drug coating 15 includes a drug carrier and a drug that inhibits endothelial hyperplasia. The drug coating 15 is coated on the outer surface of the outer coating film 14 by combining the carrier with the drug by physical and chemical methods. Due to diffusion, penetration and other effects in the body, the drug coating 15 is continuously and stably released at an appropriate concentration, ultimately allowing the drug to exert its maximum efficacy. Preferably, the drug loading density is (1-7) mg / mm 2 . The drug coating 15 is of a rapid release type. During the expansion of the self-expanding stent 1, the drug quickly penetrates into the diseased blood vessels and dissolves in the blood, so that the drug is in direct contact with the diseased blood vessels and is absorbed by them, thereby achieving the purpose of rapid treatment. The drug in this embodiment is rapamycin, and the carrier is urea. The carrier can protect rapamycin and reduce the loss of drug delivery. At the same time, different carriers can be used to control the speed of drug release, thereby achieving a therapeutic effect. The drug coating can be loaded with drugs by dipping, spraying, etc., wherein one or more layers can be composed of a first layer as a carrier, and after the first layer is dried, the second layer and above are a combination of drugs and carriers for repeated drug loading; or the first layer and the second layer and above are drugs and carriers or crystalline drugs, and the drugs are loaded layer by layer by dipping or spraying.

[0055] In addition to preventing thrombosis and restenosis in the stent, medical urea also has the function of a drug carrier, which can smoothly carry the drug to the lesion site and reduce the drug loss during drug delivery. At the same time, it dissolves in the blood during the stent expansion process, so that the drug is in direct contact with the diseased blood vessel and absorbed, achieving the purpose of rapid treatment. In this embodiment, rapamycin and urea are mixed in a ratio of 1:7, and 10ml of methanol solution is added, and ultrasonic vibration is used for 1 hour to mix. After the mixed solution is filtered using a 0.35um filter head, the stent is fixed just below the nozzle. During the spraying process, the stent rotates at a constant speed, and the mixed solution is continuously sprayed out through the sprayer nozzle, and the mixed solution is repeatedly sprayed on the surface of the stent outer coating film layer by layer.

[0056] The self-expanding stent 1 may be symmetrical or asymmetrical, and the length of the self-expanding stent 1 is greater than the diameter of the self-expanding stent 1. In other words, the length of the self-expanding stent 1 is greater than the length perpendicular to the length of the self-expanding stent 1. It should be noted that the length of the self-expanding stent 1 is the length of the bare stent 11.

[0057] like Figure 4 and 5 As shown, the bare stent 11 can be divided into three parts along its length direction, namely, the proximal portion 1-1, the distal portion 1-2 and the main body 1-3, wherein the main body 1-3 is located between the proximal portion 1-1 and the distal portion 1-2, and the proximal portion 1-1 is closer to the push rod 4 than the distal portion 1-2. In order to further achieve the stability of the self-expanding stent 1 of the present application during deployment and contraction, the main body 1-3 of the self-expanding stent 1 can be arranged concentrically with the proximal portion 1-1 and the distal portion 1-2, respectively, to increase the contact area between the distal stent and the circumferential direction of the blood vessel, which is conducive to better adhesion of the stent. The main body 1-3 and the proximal portion 1-1 of the stent can also be designed with an eccentric oblique opening, which is conducive to the recovery of the stent. In this embodiment, the self-expanding stent 1 is open at both ends and has an oblique opening. In other words, the proximal portion 1-1 and the distal portion 1-2 are designed with an eccentric oblique opening relative to the main body 1-3.

[0058] When the proximal portion 1-1 and the distal portion 1-2 are designed as eccentric bevels relative to the main body 1-3, the cross-section of the self-expanding stent 1 is a trapezoid, and further, an isosceles trapezoid, in the cross-section passing through the straight line where the keel 12 (the specific introduction of the keel 12 is described below) and the center line of the main body 1-3. The main body 1-3 is cylindrical, and its outer surface is a cylindrical outer surface. In the cross-section, the main body 1-3 is rectangular, and the proximal portion 1-1 and the distal portion 1-2 are both triangular. The length direction of the bare stent 11 is parallel to the center line direction of the main body 1-3. The proximal portion 1-1 is connected to the push rod 4.

[0059] All existing types of recyclable stents or drug-eluting stents with mesh structures have the same problem, that is, when the mesh unit is compressed by external force, radial compression force occurs due to the reduction in the height of the mesh unit. In the process of retrieving the stent, the proximal core wire needs to be pulled to recycle the stent into the outer tube. At this time, excessive radial compression force will increase the friction between the stent and the outer tube, thereby increasing the risk of surgery. During the expansion process of the stent, the outer tube needs to be withdrawn. At this time, the height of the mesh unit increases and radial expansion force occurs. Due to its own radial force, the stent will gradually expand to the target blood vessel and adhere to the blood vessel. If the radial expansion force is too large at this time, the outer tube withdrawal force will be too large, increasing the risk of clinical use. If the radial expansion force is too small, the stent is prone to displacement, thereby affecting the stent's wall adhesion performance. Therefore, the design structure of the stent must ensure that the stent has a suitable radial force and has good delivery performance.

[0060] The mesh units 111 may be in various shapes and connected in various ways. In this embodiment, the mesh units 111 include mesh units with staggered arrangement and mesh units with non-staggered arrangement.

[0061] For staggered arrangement of mesh units, each mesh unit 111 includes a plurality of unit rods 1111, such as Figures 6 to 8 As shown, specifically, each mesh unit 111 is surrounded by a plurality of unit rods 1111, and each mesh unit 111 is surrounded by four unit rods 1111 connected end to end in sequence to form a quadrilateral. The unit rods 1111 of adjacent mesh units 111 are closely fitted and connected, which is equivalent to the mesh unit 111 formed by the independent unit rods 1111 connecting the fish body with the scales, which is equivalent to the connection between the scales by connecting the mesh units 111 through the unit rods 1111, which can provide axial tension during the radial compression of the self-expanding stent 1, and can smoothly enter the inner cavity of the outer tube 5 like fish scales, reduce the friction with the outer tube 5, and compensate for the shortening rate of the mesh unit 111 during the release and expansion of the stent. The mesh units 111 are arranged in sequence in the length direction and circumferential direction of the bare stent 11 through the unit rods 1111 to form a mesh support body similar to fish scales. The shortening rate refers to: the axial length of the self-expanding stent 1 deployed in the human body lumen is recorded as l1, and the axial length of the self-expanding stent 1 in the compressed state in the outer tube 5 is recorded as l2. Generally, l1 is smaller than l2, and the ratio of the difference between the two lengths to l2 is called the stent shortening rate.

[0062] The unit rod 1111 can be a straight rod or a non-straight rod, and the shape of the mesh unit 111 is a parallelogram or a parallelogram-like shape. The four unit rods 1111 that form a mesh unit 111 include two types, such as Figure 8 As shown, they are respectively a first unit rod 11111 and a second unit rod 11112, the length of the first unit rod 11111 is greater than the length of the second unit rod 11112, the two first unit rods 11111 are two opposite sides of the parallelogram, and the two second unit rods 11112 are the other two opposite sides of the parallelogram. In the main body 1-3, the angle A between the first unit rod 11111 and the second unit rod 11112 of a mesh unit 111 is in the range of 40° to 60°, the angle B between the first unit rod 11111 and the other second unit rod 11112 is in the range of 120° to 140°, and the length X of the first unit rod 11111 is 2 to 6 mm.

[0063] Different from the cross or Y-shaped intersection of the existing meshes, in the main body 1-3, the intersection of adjacent mesh units 111 of the fish scale structure of the present application is in a T-shape. Figure 6 and 7 As shown, after deployment, the multiple mesh units 111 of the main body 1-3 are arranged in multiple rows and columns. The dotted line in the figure is the center line of the bare stent 11, and the arrangement direction of the multiple mesh units 111 in the same row is parallel to the direction of the center line of the main body 1-3. Figure 7 The multiple mesh units 111 filled with the middle cross-section line are in the same row and are adjacent to each other in sequence. Figure 6The plurality of mesh units 111 filled with black are in the same column and are adjacent to each other in sequence. The arrangement direction of the mesh units 111 in one column is not perpendicular to the center line direction of the main body 1 - 3 .

[0064] The multiple mesh units 111 in each column are connected in sequence, and the mesh units 111 in two adjacent columns are arranged in a staggered manner. Specifically, in the multiple mesh units 111 in each column, two adjacent mesh units 111 are connected by their respective second unit rods 11112, that is, the second unit rod 11112 of each mesh unit 111 is connected to the second unit rod 11112 of the mesh unit 111 adjacent to the mesh unit 111, and the two second unit rods 11112 connected to each other are arranged in parallel and are flush end to end. The mesh units 111 in two adjacent columns are connected by their respective first unit rods 11111. Specifically, the connection between two adjacent mesh units 111 in a column of mesh units 111 is aligned with the middle of a first unit rod 11111 of a mesh unit 111 in the adjacent column. The alignment is as shown in FIG. Figure 8 At O shown in the figure, the alignment is equivalent to dividing a first unit rod 11111 into two sections, wherein the length of one section accounts for 50-80% of the length of the entire first unit rod 11111, and taking the alignment as the vertex and the two sections as the two sides forming an angle, the angle C of the angle ranges from 170° to 180°. That is, the first unit rod 11111 of a mesh unit 111 connects the first unit rods 11111 of two mesh units 111 in an adjacent row.

[0065] When the self-expanding stent 1 is in a natural state (not subjected to radial compression force and radial expansion force), Figure 8 As shown, the acute angle D between the length direction of the first unit rod 11111 of the mesh unit 111 of the main body 1-3 and the straight line direction parallel to the center line of the main body 1-3 is 20° to 60°, and the dotted line in the figure is a straight line parallel to the center line of the main body 1-3.

[0066] In this solution, the mesh units arranged without dislocation include mesh units connected by U-shaped rods, mesh units connected by S-shaped rods, and mesh units connected by X-shaped rods.

[0067] U-shaped rods connect the mesh units such as Fig.14 As shown, it includes four unit rods 1111 and four connecting rods 1112, the unit rods 1111 are straight rod-shaped structures, and the connecting rods 1112 are U-shaped rod-shaped structures. The four unit rods 1111 are arranged in a rhombus structure, the four unit rods 1111 are respectively located on the four sides of the rhombus, and the four connecting rods 1112 are respectively located on the four vertices of the rhombus. In other words, each unit rod 1111 is connected to a connecting rod 1112 at both ends, and each connecting rod 1112 connects two adjacent unit rods 1111 of the same mesh unit 111.

[0068] Furthermore, adjacent mesh units 111 share a connecting rod 1112. For the mesh units 111 in the middle of the bare stent 11 that are not at the edge, each connecting rod 1112 is shared by four mesh units 111 that are adjacent in sequence. These four mesh units 111 form a rhombus-like structure, and the shared connecting rod 1112 is located at the center of the rhombus. Specifically, the "U"-shaped opening direction of the connecting rod 1112 is consistent with the circumference of the self-expanding stent 1, and the "U"-shaped opening directions of all connecting rods 1112 are consistent. For the connecting rods 1112 in the middle of the bare stent 11 that are not at the edge, each connecting rod 1112 connects eight unit rods 1111, and the connection points of these eight unit rods 1111 and the connecting rod 1112 are symmetrically arranged on the connecting rod 1112, specifically, with the center line of the connecting rod 1112 (i.e., the center line of the "U"-shaped opening) as the symmetry axis.

[0069] The line connecting two opposite vertices of a rhombus where a mesh unit 111 is located is parallel to the length direction of the self-expanding stent 1, and the other two opposite vertices are on the same circumference line of the self-expanding stent 1. The line connecting two acute angles of the rhombus where each mesh unit 111 of the main body 1-3 is located is parallel to the length direction of the self-expanding stent 1. The regular cyclic design of the mesh structure of the bare stent 11 formed in this way strengthens the radial force, ensuring that the self-expanding stent 1 can be reliably expanded in the blood vessel and has sufficient supporting force.

[0070] The area of ​​the rhombus formed by one mesh unit 111 is 1.5 to 8.0 mm 2 .like Fig.14 As shown, the rod bending angle α is 20° to 70°, that is, the acute angle between two adjacent unit rods 1111 of a mesh unit 111 is 20° to 70°.

[0071] The connecting rod 1112 can provide axial tension during the expansion of the self-expanding stent 1 to compensate for the shortening of the mesh unit 111 during the expansion of the self-expanding stent 1. In other words, the reduction in the axial length of the rhombus can be compensated during the expansion of the self-expanding stent 1.

[0072] like Fig.15 As shown, the connecting rod 1112 connecting the S-shaped rod mesh units is S-shaped.

[0073] like Fig.16 As shown, the connecting rod 1112 connecting the mesh units with the X-shaped rod is X-shaped, and the figure surrounded by the mesh units 111 is a diamond shape.

[0074] The design of the mesh unit 111 itself and the interconnected relationship makes the self-expanding stent 1 easier to compress, more adaptable to small blood vessels, and easier to be received in the outer tube 5. It is beneficial to evenly distribute the mesh wires (i.e., unit rods 1111) in each section of the bare stent 11 and around its cross section, so as to provide uniform support and better expansion effect. Compared with the ordinary quadrilateral structure, such a fish scale structure can make the stent mesh unit 111 form a coaxial structure in the length direction and the circumferential direction. Thereby, the mesh arrangement of the main body 1-3 of the stent is flatter, and at the same time, the polymer film on the surface of the bare stent 11 can be flatter, reducing the defect of the polymer film sinking.

[0075] In addition, due to process limitations, if the mesh unit 111 is set to some other shapes (such as a parallelogram whose side length is parallel to the blood vessel length and is not staggered), the stability of the bare stent 11 is poor, and a larger rod width and wall thickness of the bare stent 11 are required (the rod width of the bare stent 11 refers to the length of the unit rod 1111, and the wall thickness of the bare stent 11 refers to the diameter of the unit rod 1111) to improve stability, that is, the unit rod 1111 needs to be longer and the diameter is larger. Since the rod width of the stent is increased, the area of ​​the mesh unit is also increased. For small stents suitable for coronary arteries, excessive mesh unit area leads to poor radial expandability of the bare stent 11. In other words, the same expansion amplitude requires a larger radial force. The design of the fish scale structure can achieve a small rod width and a small stent wall thickness, or even a smaller mesh structure, which is beneficial to improving the flexibility and pushability of the stent.

[0076] In addition, if the mesh unit 111 is smaller in area, the contact area between the bare stent 11 and the polymer film (the inner coating film 13 and the outer coating film 14) can be increased, and reducing the wall thickness of the bare stent 11 can reduce the range between the rod width and the polymer film thickness, so that the polymer film is closer to the outer surface of the stent, so that the drug coating on the polymer film is in better contact with the blood vessel, and the drug absorption rate of the target blood vessel is improved. Moreover, the mesh units 111 are arranged in sequence like fish scales, which can effectively reduce the friction between the devices, and help improve the conductivity of the self-expanding stent 1 in the blood vessel and the flexibility when passing through the curved blood vessel.

[0077] Each mesh unit 111 of the main body 1-3 is a mesh structure with uniform area and regular arrangement, which can provide uniform circumferential force, so that the self-expanding stent 1 has better wall adhesion performance in the blood vessel, so that the drug coating 15 on the self-expanding stent 1 is better attached to the blood vessel. The mesh units 111 on the proximal portion 1-1 are mesh structures with different area sizes, and the mesh units 111 on the distal portion 1-2 are also mesh structures with different area sizes. The area of ​​the mesh units 111 of the proximal portion 1-1 and the distal portion 1-2 is smaller than the area of ​​the mesh units 111 of the main body 1-3, so as to adapt to the oblique design at both ends, so the radial expansion force of the proximal portion 1-1 and the distal portion 1-2 is smaller than the radial expansion force of the main body 1-3. When the self-expanding stent 1 enters the outer tube 5, the proximal portion 1-1 contacts the outer tube 5 first. The smaller radial expansion force of the proximal portion 1-1 can reduce the friction between the self-expanding stent 1 and the outer tube 5 during the loading process, thereby reducing the loss of the drug coating 15 and reducing the pulling force of the push rod 4 on the self-expanding stent 1 during the loading process. In addition, since the proximal portion 1-1 and the distal portion 1-2 are designed with eccentric bevels, this shape makes it easier for the self-expanding stent 1 to enter the outer tube 5. In addition, the design that the area of ​​the mesh unit 111 of the proximal portion 1-1 and the distal portion 1-2 is smaller than the area of ​​the mesh unit 111 of the main body 1-3 can reduce the "dog bone" effect of the self-expanding stent 1 during the pre-loading process and the expansion process.

[0078] In this embodiment, the bare stent 11 is made of nickel-titanium NITI material, and the fish-scale structure is made by a laser cutting process.

[0079] The stent distal end development 2 and the stent proximal end development 3 are respectively installed at the two ends of the bare stent 11. Specifically, the stent distal end development 2 is installed at the end of the distal end 1-2 away from the main body 1-3, and the stent proximal end development 3 is installed at the end of the proximal end 1-1 away from the main body 1-3. Obviously, the stent proximal end development 3 is closer to the push rod 4 than the stent distal end development 2. The stent distal end development 2 and the stent proximal end development 3 are not transparent to X-rays. When the clinician monitors the development that is not transparent to X-rays through vascular imaging equipment such as DSA (digital subtraction angiography), the position of the self-expanding stent 1 in the blood vessel and whether the self-expanding stent 1 is in an expanded or compressed state can be monitored and determined by checking the position of the development, because the distance between the stent distal end development 2 and the stent proximal end development 3 when the self-expanding stent 1 is in an expanded state is less than the distance between the stent distal end development 2 and the stent proximal end development 3 when the self-expanding stent 1 is in a compressed state. Preferably, the stent distal end development 2 is a spring-shaped development filament, and the development filament material is preferably platinum tungsten alloy. The developing filament is wound into a spring shape and has elasticity, which can prevent the self-expanding stent 1 from being directly pressed against the blood vessel wall due to misoperation when the self-expanding stent 1 is out of the outer tube 5, causing damage to the blood vessel. The stent proximal end developing 3 can be a spring shape wound by the developing filament or a precious metal developing point with strong developing properties. In this embodiment, the proximal end developing 3 uses a platinum-iridium ring, which is a cylindrical ring structure, and the bare stent 11, the push rod 4, and the platinum-iridium ring can be welded and fixed by a brazing process.

[0080] The keel 12 is connected to the bare stent 11. Specifically, the keel 12 is a rod-shaped structure. The length direction of the keel 12 is consistent with or parallel to the length direction of the bare stent 11. The cross-section of the keel 12 is preferably circular, and the diameter of the keel 12 is greater than the diameter of the unit rod 1111, that is, the keel 12 is thicker than the unit rod 1111. The two ends of the keel 12 do not exceed the two ends of the bare stent 11, and the length of the keel 12 can be equal to or less than the length of the bare stent 11. When the keel 12 is arranged on the entire length of the self-expanding stent 1, the pushing performance of the self-expanding stent 1 can be further enhanced. At this time, the length of the keel 12 is equal to the sum of the lengths of the proximal portion 1-1, the distal portion 1-2 and the main body 1-3. This structure adds reinforcing ribs to the self-expanding stent 1, reduces the pushing resistance of the drug-loaded stent in the outer tube 5, and increases the radial supporting force of the self-expanding stent 1. When the length of the keel 12 is less than the length of the bare stent 11, only one section of the bare stent 11 is connected with the keel 12 instead of the entire length. Preferably, the keel 12 is connected to the proximal portion 1-1. This design can enhance the ability of the proximal portion 1-1 to resist deformation and improve the support force of the bare stent 11. Moreover, since the design of only having the keel 12 in the length direction of the bare stent 11 does not affect the overall flexibility and wall adhesion of the bare stent 11. Preferably, the length of the keel 12 is the same or similar to the length of the proximal portion 1-1, and the keel 12 is only connected to the proximal portion 1-1. In this way, the bare stent 11 still has good flexibility in the blood vessel, and enhances the support and rigidity of the proximal portion 1-1 of the stent to resist deformation, thereby enhancing the delivery performance of the self-expanding stent 1 in the outer tube 5 (the introduction of the outer tube 5 is described below).

[0081] Preferably, the length of the keel 12 is 4 to 12 mm. The shape of the keel 12 can also be a quadrilateral cross section at one end and a circular cross section at the other end; or a quadrilateral cross section in the middle and a circular cross section at both ends. The portion with a quadrilateral cross section has a length of 0.2 mm to 0.6 mm and a width of 0.2 mm to 0.6 mm. The portion with a circular cross section can be a variable cross section, one end of which is smoothly connected to the portion with a quadrilateral cross section, and the diameter of the other end is 0.06 mm to 0.12 mm. It should be noted that the cross section of the keel 12 can be set to other shapes as needed.

[0082] The keel 12 passes through the mesh unit 111, which is equivalent to occupying the area of ​​the original mesh unit 111, or the keel 12 re-divides the mesh unit 111 it passes through to form a new mesh unit. The new mesh units include three types: the first mesh unit 11-1, the second mesh unit 11-2 and the third mesh unit 11-3. The area of ​​the third mesh unit 11-3, the area of ​​the second mesh unit 11-2 and the area of ​​the first mesh unit 11-1 decrease in sequence, and the distance between the first mesh unit 11-1 and the keel 12, the distance between the second mesh unit 11-2 and the keel 12, and the distance between the third mesh unit 11-3 and the keel 12 increase in sequence. Preferably, the area of ​​the second mesh unit 11-2 is 0.6 to 5.5 mm larger than the area of ​​the first mesh unit 11-1. 2 The area of ​​the third mesh unit 11-3 is 1.5 to 6.0 mm larger than the area of ​​the second mesh unit 11-2. 2 Before use, the drug-loaded stent needs to be loaded into the outer tube 5 , and under the pulling force of the push rod 4 , the first mesh unit 11 - 1 , the second mesh unit 11 - 2 and the third mesh unit 11 - 3 are compressed in sequence or simultaneously.

[0083] The setting of the keel 12 improves the radial bearing capacity of the bare stent 11, and the maximum strain during the compression process is effectively reduced, thereby improving the compressibility of the bare stent 11. In addition, the proximal portion 1-1 is connected to the push rod 4. Because the proximal portion 1-1 is designed with an eccentric bevel, the excessive dispersion of force during the pushing process of the push rod 4 will cause the mesh unit 111 of the proximal portion 1-1 to deform greatly. The design of the connection of different mesh area sizes can make most of the core wire pushing force concentrated on the position of the keel. Due to the setting of the keel 12, most of the pushing force of the push rod 4 is concentrated on the keel 12, reducing the deformation of the mesh unit 111 of the proximal portion 1-1. At the same time, the deformation of the proximal portion 1-1 is small, the absorbed pushing force is small, and the pushing force of the push rod 4 can be mostly used to overcome the friction force. Therefore, the setting of the keel 12 also reduces the requirement for the size of the pushing force of the push rod 4.

[0084] The push rod 4 is rod-shaped. Preferably, the push rod 4 can be designed with a variable diameter, and the outer diameter of the push rod 4 increases from the end close to the self-expanding stent 1 to the end away from the self-expanding stent 1. The diameter of the end of the push rod 4 connected to the self-expanding stent 1 is small, ensuring that the end is soft enough and has a smaller curvature radius, so that it can better adapt to tortuous blood vessels. The end of the push rod 4 away from the self-expanding stent 1 has a large diameter, so that the end has a certain hardness, providing support strength when pushing in the outer tube 5. Preferably, the push rod 4 is stepped, that is, it includes multiple sections of straight rods with different diameters.

[0085] The material of the push rod 4 can be selected from 304V stainless steel wire or nickel-titanium alloy, which has good flexibility and resilience, and is convenient for pushing the self-expanding stent 1 to move in a curved blood vessel. Furthermore, the outer surface of the push rod 4 can be coated with a polymer material with a low friction coefficient, which is beneficial to reducing the friction of the push rod. The polymer material with a low friction coefficient includes but is not limited to one or more of polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) plastics.

[0086] Furthermore, a support spring is sleeved on the outside of one end of the push rod 4 connected to the self-expanding stent 1, and both ends of the support spring are connected to the push rod 4. The support spring plays a role in strengthening the support strength of the end of the push rod 4 with a smaller diameter, thereby improving the delivery performance of the push rod 4. The material of the support spring can be selected from 304V stainless steel wire or a platinum-containing alloy. In addition, a twister 8 can be designed at the end of the push rod 4 away from the self-expanding stent 1. The twister 8 is provided with a knob, and the size of its inner cavity can be increased or decreased by adjusting the knob. The push rod 4 is fixed in the inner cavity of the twister 8. During the operation, the twister 8 can be operated at the proximal end to control the drug-loaded stent, which is convenient for the use of instruments during the operation.

[0087] Fig.12 and 13 The force diagrams of the self-expanding stent 1 with staggered mesh units when it is stationary and in motion are shown respectively, wherein the center line of the main body 1-3 is the force direction when the self-expanding stent 1 is recovered. Fig.12 and 13 It is not difficult to see that when the self-expanding stent 1 of the present application is designed to be recovered to DE, when the push rod 4 applies an axial tension T to the self-expanding stent 1, due to the unique fish-scale mesh unit and the dual design of meshes of different sizes, part of the mesh units can be compressed into the outer tube 5 first, and the other part of the mesh units can be expanded outside the outer tube 5, which will generate a horizontal dynamic friction force Ff. The contact between the mesh unit 111 and the outer tube 5 will generate a pressure Ft perpendicular to the mesh unit 111, and the supporting force Ft is decomposed into a radial expansion component force F1=Ftsin∠a and an axial compression force F2=Ftcos∠a. When T>Ff+F2, the self-expanding stent 1 can move relative to the inner cavity of the outer tube 5; when the self-expanding stent 1 is stationary, a static friction force f=F2 is generated.

[0088] Based on the above structure, the working process and principle of the utility model are as follows: when in use, the drug-loaded stent cooperates with the balloon 6, the outer tube 5 and the guide wire 7, such as Figure 1As shown. The balloon 6 can be inflated. The balloon 6 is sleeved in the inner circle of the self-expanding stent 1, and the end of the balloon 6 close to the push rod 4 is also connected to the push rod 4, that is, the same end of the self-expanding stent 1 and the balloon 6 is connected to the push rod 4 to achieve the synchronous movement of the self-expanding stent 1 and the balloon 6. The existing self-expanding stent can be recovered into the guide tube before complete release, and cannot be recovered after complete release. Some thrombectomy stents can be released and recovered repeatedly, but both of these stents are delivered to the lesion position through the guide catheter, and there is no guide wire in the central cavity. For intra-coronary operations, it is very unsafe to have no guide wire that can enter the instrument at any time. This solution uses a method pre-set in the balloon 6 or a short microcatheter as a loader to form a rapid exchange system along the guide wire to ensure that the guide wire is always in the central cavity of the system. A guide wire cavity is provided in the center of the balloon 6 for the guide wire 7 to pass through. The guide wire cavity is not connected to the inside of the balloon 6. The guide wire 7 is pre-installed in the guide wire cavity of the balloon 6, that is, the guide wire 7 passes through the guide wire cavity.

[0089] The outer tube 5 is a tubular structure. Before use, the drug-loaded stent needs to be loaded into the outer tube 5. During loading, an external force pulls the push rod 4, and the push rod 4 passes through the outer tube 5. The push rod 4 pulls the self-expanding stent 1 and the balloon 6, so that the self-expanding stent 1 and the balloon 6 move as a whole toward the inner direction of the outer tube 5. One end of the proximal portion 1-1 of the self-expanding stent 1 first contacts one end of the outer tube 5. Due to the oblique design of the proximal portion 1-1, the self-expanding stent 1 can smoothly enter the outer tube 5. After entering the outer tube 5, the self-expanding stent 1 is in a compressed state, and the balloon 6, the self-expanding stent 1 and the outer tube 5 are equivalent to being sequentially sleeved from the inside to the outside, and the push rod 4 is also located in the outer tube 5.

[0090] In order to locate the outer tube 5, the balloon 6 and monitor the relative positions of the outer tube 5, the balloon 6 and the self-expanding stent 1, the outer tube 5 and the balloon 6 are also provided with a developer. Specifically, one end of the outer tube 5 is connected to the outer tube developer 5-1, the outer tube developer 5-1 is cylindrical, and the outer tube developer 5-1 is coaxially connected to the outer tube 5. Both ends of the balloon 6 are also provided with developers, namely, the balloon distal end developer 6-1 and the balloon proximal end developer 6-2, and the balloon proximal end developer 6-2 is closer to the push rod 4 than the balloon distal end developer 6-1. Similar to the stent distal end developer 2, the balloon distal end developer 6-1 is a spring-shaped developer filament, which is elastic and can prevent the balloon distal end developer 6-1 from directly hitting the blood vessel wall due to misoperation when it comes out of the outer tube 5, causing damage to the blood vessel.

[0091] The self-expanding stent 1 has two states: compression and expansion. When the self-expanding stent 1 is located in the outer tube 5, it is in a compressed state due to the limitation of the outer tube 5. When loading, the position of the self-expanding stent 1 and the balloon 6 pulled into the outer tube 5 is: the outer tube development 5-1, the stent distal development 2 and the balloon distal development 6-1 are flush. In this way, the relative positions of the self-expanding stent 1, the balloon 6 and the outer tube 5 are maintained in a suitable state. It can be seen that the drug-loaded stent can be pre-installed in the outer tube 5 in vitro, the outer diameter of the self-expanding stent 1 is larger than the inner diameter of the outer tube 5, and the drug-loaded stent 1 can be fixed in the outer tube 5 by the pressure between itself and the outer tube 5. In the absence of external pulling, the two will not be relatively displaced.

[0092] During the operation, after the outer tube 5 and the balloon 6 installed in the outer tube 5 and the drug-loaded stent are transported to the lesion position, the outer tube 5 is withdrawn to move the outer tube 5 relative to the self-expanding stent 1. The self-expanding stent 1 is gradually released from the restriction of the outer tube 5 and can expand to its original diameter, and is in an expanded state. The self-expanding stent 1 expands to the target lesion position and adheres to the blood vessel wall and allows the drug to be absorbed by the blood vessel wall. Then the balloon 6 is inflated to ensure that the self-expanding stent 1 adheres to the wall. The balloon 6 is alternately expanded 5 times with an interval of 30-60s, aiming to enhance the wall adhesion of the self-expanding stent 1 and promote the absorption of the drug coated on the self-expanding stent 1 by the vascular endothelium. As the time of the self-expanding stent 1 adhering to the blood vessel wall increases, the drug is continuously absorbed by the blood vessel and diffuses to the endothelium, the middle membrane and the outer membrane of the blood vessel, and deep drug administration is performed to improve the utilization rate of the drug. During the process, the setting of the keel 12 improves the stability of the self-expanding stent 1, and at the same time improves the anchoring effect of the self-expanding stent 1 in the blood vessel, reducing the risk of displacement of the self-expanding stent 1. After the drug is released, the outer tube 5 is pushed to the vicinity of the proximal end 1-1 of the self-expanding stent 1, and the pushing rod 4 is pulled to retract the self-expanding stent 1 into the outer tube 5, and then the outer tube 5 and the self-expanding stent 1 are withdrawn from the patient's body. It can be seen that the drug-loaded stent will not remain in the blood vessel, and this method will not block blood flow, and can also prolong the drug administration time. The entire operation process is simple and easy to operate.

[0093] As can be seen from the above, during the compression of the mesh unit 111, the bare stent 11 will generate radial force due to the reduction in the height of the mesh unit 111. When the self-expanding stent 1 is pulled back into the outer tube 5, excessive radial force will increase the friction between the self-expanding stent 1 and the outer tube 5, which is not conducive to the delivery of the self-expanding stent 1 and increases the risk of surgery. During the expansion process of the self-expanding stent 1, the outer tube 5 needs to be withdrawn. Due to its own radial force, the self-expanding stent 1 will gradually expand to the target blood vessel and adhere to the blood vessel. If the radial force is too large, the withdrawal force of the outer tube 5 will be too large, increasing the risk of clinical use. If the radial expansion force is too small, the self-expanding stent 1 is prone to displacement, thereby affecting the wall adhesion performance of the self-expanding stent 1. Therefore, the design structure of the self-expanding stent 1 must ensure that there is a suitable radial force and at the same time have good delivery performance (that is, the friction with the outer tube 5 cannot be too large). The above design of this solution enables the self-expanding stent 1 to have sufficient radial force and good delivery performance.

[0094] The bare stent 11 is made of metal material, mainly medical grade stainless steel such as 316L, 304, 306 stainless steel, NITI memory alloy material, Mg-based alloy, titanium-based alloy, CoCr-based alloy material such as L605, MP35N, Phynox, etc.

[0095] The materials of the inner coating film 13 and the outer coating film 14 may also be selected from TPU, PU, ​​PTFE, Pebax, nylon, etc.

[0096] The carrier can also be liposome, butylated hydroxytoluene, polylactic acid-glycolic acid copolymer, polylactic acid, mineralized calcium phosphate, a mixture of polylactic acid, and a mixture of the above polymers.

[0097] The main choices of organic polymer materials are: polyethylene and its derivatives, polypropylene and its derivatives, polyfluorine derivatives, polylactic acid and its derivatives, mixtures of polyethylene, polypropylene, polylactic acid and their derivatives; also include biostable materials, biodegradable materials, bioabsorbable materials, etc.

[0098] The main choices of drug materials are: rapamycin and its derivatives, paclitaxel and other anti-proliferative and anti-inflammatory drugs or mixed preparations, etc.

[0099] Finally, it is necessary to explain here that the above embodiments are only used to further illustrate the technical solution of the utility model in detail and cannot be understood as limiting the protection scope of the utility model. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the utility model belong to the protection scope of the utility model.

Claims

1. A recyclable drug-eluting stent, characterized in that: The invention comprises a self-expanding stent (1) and a pushing rod (4), wherein the self-expanding stent (1) is coated with drugs, the pushing rod (4) is connected to and drives the self-expanding stent (1) to move, the self-expanding stent (1) comprises a bare stent (11) and a keel (12), the bare stent (11) comprises a plurality of mesh units (111), the plurality of mesh units (111) are sequentially connected to form a cylindrical structure with a hollow fish-scale-like side wall, the bare stent (11) can actively or passively expand and compress along its radial direction, the end of the bare stent (11) close to the pushing rod (4) is designed as an inclined opening, the keel (12) is rod-shaped, the keel (12) is connected to the bare stent (11), and the length direction of the keel (12) is parallel to the length direction of the bare stent (11).

2. The drug-loaded stent according to claim 1, characterized in that: The bare stent (11) comprises a proximal portion (1-1), a distal portion (1-2) and a main body (1-3) along its length direction. The main body (1-3) is cylindrical and is located between the proximal portion (1-1) and the distal portion (1-2). The proximal portion (1-1) is closer to the push rod (4) than the distal portion (1-2), and the end of the proximal portion (1-1) is designed to be an inclined opening.

3. The drug-loaded stent according to claim 2, characterized in that: The mesh unit (111) is formed by four unit rods (1111) connected end to end in sequence to form a parallelogram-like shape, and the unit rods (1111) of adjacent mesh units (111) are tightly fitted and connected.

4. The drug-loaded stent according to claim 3, characterized in that: The four unit rods (1111) that form a mesh unit (111) include two types, namely a first unit rod (11111) and a second unit rod (11112); the length of the first unit rod (11111) is greater than the length of the second unit rod (11112); the two first unit rods (11111) are two opposite sides of the parallelogram; the two second unit rods (11112) are the other two opposite sides of the parallelogram; in the main body (1-3), the angle between the first unit rod (11111) and one second unit rod (11112) of a mesh unit (111) is 40° to 60°, and the angle between the first unit rod (11111) and another second unit rod (11112) is 120° to 140°.

5. The drug-loaded stent according to claim 4, characterized in that: The plurality of mesh units (111) of the main body (1-3) are arranged in multiple rows and columns after being unfolded, the arrangement direction of a row of mesh units (111) is parallel to the direction of the center line of the main body (1-3), the arrangement direction of a column of mesh units (111) is not perpendicular to the direction of the center line of the main body (1-3), and two adjacent columns of mesh units (111) are staggered.

6. The drug-loaded stent according to claim 1, characterized in that: The self-expanding stent (1) further comprises an inner coating film (13) and an outer coating film (14); the inner surface of the bare stent (11) is connected to the inner coating film (13), and the outer surface of the bare stent (11) is connected to the outer coating film (14); and the outer surface of the outer coating film (14) is coated with drugs to form a drug coating (15).

7. The drug-loaded stent according to claim 2, characterized in that: The self-expanding stent (1) further comprises a stent distal end display (2) and a stent proximal end display (3), wherein the stent distal end display (2) is mounted at an end of the distal portion (1-2) away from the main portion (1-3), and the stent proximal end display (3) is mounted at an end of the proximal portion (1-1) away from the main portion (1-3).

8. The drug-loaded stent according to claim 7, characterized in that: The distal end imaging (2) of the stent is in the shape of a spring wound with imaging filaments.

9. The drug-loaded stent according to claim 1, characterized in that: The push rod (4) is a rod-shaped structure with a variable diameter, and the outer diameter of the push rod (4) increases gradually from the end close to the self-expanding stent (1) toward the end far from the self-expanding stent (1).

10. The drug-loaded stent according to claim 1, characterized in that: When in use, the drug-loaded stent cooperates with the balloon (6) and the outer tube (5), the balloon (6) can be inflated, the balloon (6), the self-expanding stent (1) and the outer tube (5) are sequentially sleeved from the inside to the outside, and the push rod (4) is also located inside the outer tube (5).

Images