A new type of stent graft

Abstract

The present invention provides a coated stent, including a support frame and a film body, the support frame is a wavy or mesh structure surrounded by multiple elastic support rods, including a proximal support frame, a lumbar support frame, and a distal support frame from near to far, and the lumbar support frame is a hollow tube as a whole. The film body includes film A and film B, film A is a microporous or non-porous structure, and its pore size or node distance does not exceed 60μm, and at least covers the inner surface of the support rod of the lumbar support frame; film B is a microporous structure, and its pore size or node distance is greater than the pore size or node distance of film A, and film B at least covers the outer surface of the edge area of ​​the proximal support frame and / or the distal support frame. The present invention realizes that after the coated stent is implanted into the target tissue, the lumen diameter can be effectively maintained for a long time, taking into account the long-term fixation safety, and is suitable for implantation via percutaneous minimally invasive interventional approach. Compared with similar products on the market, it has higher safety and better long-term shunt effectiveness.

Description

Technical Field

[0001] The present invention relates to the field of passive device treatment for heart failure, and in particular to a coated stent with a differential endothelialization function design that meets the requirements of percutaneous minimally invasive interventional implantation. Background Art

[0002] Heart failure is the final result of various cardiovascular events and the cumulative effect of various cardiac abnormalities. In some heart diseases, there will be a significant difference in the pressure between the left and right atria. For example, patients with pulmonary hypertension have persistent high right atrial pressure, and the right atrial pressure needs to be reduced, otherwise it will lead to right heart enlargement and right heart failure, and eventually lead to decreased heart pumping function. Once cardiovascular patients have clinical manifestations of heart failure, it indicates a poor prognosis. The more severe the heart failure, the higher the risk of death. Heart failure is an abnormal change in the structure and function of the heart caused by various reasons, which makes the ventricular contraction ejection and (or) diastolic filling function send disorder, thus causing a group of complex clinical syndromes, the main manifestations of which are decreased activity tolerance (dyspnea, fatigue) and fluid retention (pulmonary congestion, systemic congestion and peripheral hematoma).

[0003] Atrial septostomy is a palliative method for treating complex heart diseases. It is an interventional method to establish communication between the left and right atria of the patient, allowing the blood in the left and right atria to mix, adjusting the hemodynamics to a relatively stable state, transferring the pressure between the left and right atria, relieving the heart load, and preventing the patient from experiencing heart failure.

[0004] The commonly used puncture sheath in clinical practice generally uses a puncture sheath to puncture and create a hole in the atrial septum, coronary sinus, etc., and uses a balloon to expand the defect. However, this puncture technique usually cannot accurately control the size of the hole, and the defect closes naturally after surgery, and there is a phenomenon of postoperative puncture retraction, which causes the hole to close quickly due to endothelialization and lose its shunt function.

[0005] In order to solve the problem that the size of the hole cannot be controlled by ostomy, NOYA developed by Denor Medical TM The adjustable atrial shunt device can perform radiofrequency ablation to create a hole in the atrial septum. This device is an active interventional medical device, but NOYA TM The device does not place an implant at the hole-making position after radiofrequency ablation, so there is no support for the atrial septum tissue at the shunt hole position, which makes the shunt hole area very likely to gradually close; secondly, the shunt device adopts a grid structure, and the inner surface of the shunt hole formed after radiofrequency ablation is uneven, which has the risk of thrombosis. In addition, active devices involve energy source input, which is difficult to take into account and balance with the safety and effectiveness of clinical treatment. At the same time, the cost of active devices is high and the cost of surgery is expensive.

[0006] Similarly, to solve the above problems, the foreign company V-Wave developed an atrial septal shunt (Ventura, a single-phase shunt device) to support the shunt hole formed by the interventional method and avoid postoperative hole retraction. Among them, the I-generation product is equipped with a valve. Although it can play a one-way shunt role, it was found during the 12-month follow-up that the shunt hole was completely blocked in 14% of the cases and restenosis occurred in 36% of the cases. In response to the problems of the I-generation product, V-Wave later improved and developed the II-generation product, which removed the valve in the shunt hole, but the product still has the following problems: 1) The Niti alloy frame is also designed with a polymer membrane that is easy for endothelial to climb over, which leads to blockage of the shunt hole (we previously referred to this design to trial-produce samples, and found in exploratory animal experiments that the shunt hole was blocked after 4 months); 2) The stent is designed to be hourglass-shaped, a) only the waist is attached to the atrial septum tissue, and the left and right discs are not in contact with the atrial septum tissue. The stent of this design has no clamping force on the atrial septum and is prone to shaking under the flushing of blood flow; b) The stent goes deep into the atrium, occupies the volume of the atrium, is not easy to endothelialize, and will affect the hemodynamics in the atrium.

[0007] In addition, the atrial flow regulator (AFR) provided by Oclutech is made of nickel-titanium wires woven up and down using existing technology, and has a movable grid structure, which results in: a) the device has little support for the shunt hole position, causing the shunt hole to retract or gradually close. Among them, in the animal experiment of the AFR product, one pig had a shunt hole blocked at the third day of follow-up, and another pig was also found to have a shunt hole blocked at the 28th day of follow-up.

[0008] b) The length of the AFR product's disk after being compressed into the sheath is much longer than its natural length after being released from the sheath, and the reversible deformation of existing implantable membranes is limited, so a coating design (the membrane and wire in all areas are fixedly connected) cannot be used; this results in a high metal coverage rate in the product, and direct contact between the nickel-titanium alloy wire and blood, which leads to the precipitation of nickel ions and ultimately causes the risk of toxicity, sensitization and teratogenicity, and poor biocompatibility; it is also prone to complications such as thrombus formation on the disk surface.

[0009] c) The threads of the AFR product are restricted in position. When the waist of the AFR product is placed at the target position, due to the mutual entanglement between the threads, the left and right discs are difficult to adapt to the uneven shape of the mouth, forming a pore area, which makes it impossible to fully fit the target position.

[0010] In addition, the Neovasc Reducer device developed by NEOVASC is a minimally invasive procedure that inserts the Neovasc Reducer into the jugular vein. TMThe device is implanted in the coronary sinus of the heart and relieves angina by reducing the blood pumping rate from the coronary sinus of the heart and allowing some blood to flow back to the ventricular wall to increase the blood supply to the heart. TM The device is thinner in the middle, measuring 3mm, and thicker at both ends, measuring 13mm, with a dumbbell shape as a whole. The shunt hole in the middle of the device is small, measuring only 3mm, and the blood flowing through the coronary sinus is venous blood with a slow blood flow rate, which can easily cause the device, especially the shunt hole in the middle, to occlude due to endothelial creeping.

[0011] Therefore, it is urgently needed in the market to design and develop a covered stent with differential endothelialization function, which can ensure that the size of its luminal channel is effectively maintained for a long time without stenosis or even blockage, while taking into account the safety of long-term fixation and being suitable for percutaneous minimally invasive implantation. Summary of the invention

[0012] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a coated stent, so that after the coated stent is implanted in the target tissue, the size of the lumen channel of the lumbar support frame can be effectively maintained for a long time without stenosis or even blockage, while taking into account the safety of long-term fixation and meeting the series functions of percutaneous minimally invasive interventional implantation. Compared with similar products on the market, it is safer and more effective in long-term shunting.

[0013] The object of the present invention is achieved through the following technical solutions:

[0014] A novel coated stent comprises a support frame and a film body, wherein the support frame is a wavy or mesh structure surrounded by multiple elastic support rods, and the support frame comprises a proximal support frame, a lumbar support frame and a distal support frame from near to far, and the lumbar support frame is hollow tubular as a whole, and the film body comprises at least film A and film B, wherein film A is a microporous structure or a non-porous structure, and the pore size or node distance of film A does not exceed 60 μm, and film A at least covers the inner surfaces of all support rods of the lumbar support frame, wherein the inner surfaces are all surfaces of the support rods in contact with fluid; film B is a microporous structure, and the pore size or node distance of film B is greater than the pore size or node distance of film A, and film B at least covers the outer surfaces of the edge areas of all support rods of the proximal support frame and / or the distal support frame, wherein the outer surfaces are all surfaces of the support rods in contact with target tissues.

[0015] The purpose of this application can be further achieved through the following technical solutions:

[0016] In one embodiment, the film A is a non-porous structure, and the film A covers the inner and outer surfaces of all the support rods of the lumbar support frame; the film B is a microporous structure, and the pore size or node distance of the film B does not exceed 200 μm, and the film B covers the inner and outer surfaces of the edge part or all of all the support rods of the proximal support frame and / or the distal support frame. The film A and the film B are an integrated seamless connection structure.

[0017] In a preferred embodiment, the pore size or node distance of the film A is at least 30 μm smaller than the pore size or node distance of the film B, thereby endowing the film with a differential endothelialization function.

[0018] In a preferred embodiment, the proximal support frame, the lumbar support frame and the distal support frame are fixedly connected to each other in sequence by a plurality of the support rods to form a three-dimensional network structure, the coated stent is rotationally symmetrical along the central axis m of the lumbar support frame, and the film body covers the entire surface of the coated stent, wherein the surface includes the inner and outer surfaces of the support frame and the blank part of the three-dimensional network structure, the film body is a flexible sheet, and the thickness of the film body is between 1μm-200μm. The coated stent is provided with a sheathing tolerance structure, and the sheathing tolerance structure is used to compensate for the length difference between the film body and the support frame on the central axis of the sheath tube when the coated stent is sheathed. The sheathing tolerance structure includes a curling structure or a pleated structure or a splitting structure arranged on the film B, and the curling structure or the pleated structure makes the film body have an elongation of 20% to 50%. The splitting structure is located in the blank part of the three-dimensional network structure, so that the film bodies located on both sides of the splitting structure are physically separated. In a natural unconstrained state, the film bodies on both sides of the splitting structure can touch or overlap. During the loading and sheathing process, the film bodies on both sides of the splitting structure are separated from each other.

[0019] In a preferred embodiment, a buffer structure is provided on the edge of the support rod of the proximal support frame and / or the distal support frame of the coated stent, and the buffer structure is on the same plane as the edge area of ​​the support rod of the distal support frame and / or the proximal support frame, and the buffer structure is completely covered in the film body, so as to reduce the damage of the edge of the support rod to the tissue and avoid delamination or peeling between the distal end of the support rod and the film body, and the film B is provided with a spacing structure, which is located in the gap area between the buffer structure and the support rod skeleton, and the spacing structure ensures that the distal end part of the buffer structure can be elastically deformed relative to the edge of the support frame.

[0020] In one embodiment, a buffer structure is provided on the edge of the support rod of the distal end support frame of the coated stent, and the buffer structure and the support frame are an integrated structure formed by laser engraving and heat setting the same shape memory alloy tube; the buffer structure is composed of an even number of buffer rods, and every two adjacent buffer rods are fixedly connected at the distal end and converge at the connection part of the buffer structure; an adaptive structure is provided in the proximal area of ​​the buffer rod; the adaptive structure has anatomical morphological adaptability, radially outward from the edge of the distal end support frame, and then bends in the proximal direction to obliquely cross the edge of the distal end support frame and extend toward the center of the support frame, and the bending angle θ satisfies: 90°≤θ≤175°, or radially outward from the edge of the distal end support frame, and then bends on the plane α to extend in a direction away from the support frame, and the bending angle θ satisfies: 10°≤θ≤135°.

[0021] In a preferred embodiment, the coated stent also includes a reinforcement structure; the reinforcement structure is composed of a plurality of reinforcement rods; the reinforcement rods are fixedly connected to the support rods on the proximal support frame and / or the distal support frame, and are used to enhance the contact force of the edge area of ​​the proximal support frame and / or the distal support frame on the atrial septal tissue, further preventing the support frame from shaking or falling during or after the release.

[0022] In a preferred embodiment, the stent graft further comprises an anchoring structure; the anchoring structure can undergo reversible elastic deformation, has morphological adaptability, and achieves non-destructive anchoring with the target tissue; the anchoring structure comprises: an anchoring structure free portion and an anchoring structure connecting portion;

[0023] The anchoring structure connecting portion is used to fixedly connect the support rod and the anchoring structure; the free portion of the anchoring structure protrudes from the outer surface of the support rod in a natural unconstrained state; the aspect ratio of the free portion of the anchoring structure is between 2 and 50.

[0024] In a preferred embodiment, the length of each support rod is not greater than 20 mm, and the angle between adjacent support rods is not greater than 120°. The stent graft is in the shape of a hollow tube or a hollow dumbbell as a whole, and is defined as follows: the distance between the distal end surface of the stent graft and the distal end surface of the film A is L1, and the distance between the proximal end surface of the stent graft and the proximal end surface of the film A is L2, and L1 and L2 satisfy the following mathematical relationship: 0<L1≤10mm, 0<L2≤10mm;

[0025] Alternatively, the coated stent is in a flat I-shape as a whole, and there is a section α on the edge area of ​​the distal end support frame, and the section α is perpendicular to the central axis m of the coated stent. There is a section β on the edge area of ​​the proximal end support frame, and the section β is perpendicular to the central axis m of the coated stent. The number of grid layers of the mesh structure is 2-4 layers, and the definition is: the maximum outer diameter of the distal end support frame is D1, the inner diameter of the lumbar support frame is D2, the maximum outer diameter of the proximal end support frame is D3, the maximum diameter of the distal end support frame area covered by the film A is D4, and the maximum diameter of the proximal end support frame area covered by the film A is D5, wherein D1, D2, D3, D4 and D5 satisfy the following mathematical relationships: 15mm≤D1≤35mm, 3mm≤D2≤15mm, 15mm≤D3≤35mm, D2<D4≤D1-2mm, D2<D5≤D3-2mm.

[0026] In a preferred embodiment, the material of the film A, the film B, and the film C includes one or more of polyparaxylene, titanium nitride, mucopolysaccharide sulfate, ceramic, polyethylene terephthalate, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, polyurethane, and heparin, and the film A, the film B, and the film C are made of the same material.

[0027] Compared with the prior art, the present invention has the following outstanding advantages:

[0028] 1. The coated stent provided by the present invention has a support frame surface covered or wrapped with a thin film body, the film body includes film A and film B, film A is a non-porous structure or a microporous structure, the pore size or node distance of film A does not exceed 60μm, film A at least covers the inner surface of all support rods of the lumbar support frame, film B is a microporous structure, film B at least covers the outer surface of all support rods of the edge area of ​​the proximal support frame and / or the distal support frame, the pore size or node distance of film A is at least 30μm smaller than the pore size or node distance of film B, which means that the film body has a differential endothelialization function design, so that the edge of the proximal support frame and the edge of the distal support frame can play a role in promoting endothelialization, so as to enhance the long-term fixation of the support frame at the target position; and the rest of the coated stent as an implant, especially the lumbar support frame, can effectively prevent endothelialization, so that the lumen size of the lumbar support frame can be maintained for a long time, so as to achieve the purpose of long-term shunting effectiveness.

[0029] 2. The design of the coverage area of ​​the film A that satisfies the mathematical relationship of D2<D4≤D1-2, D2<D5≤D3-2 can maximize the coverage area of ​​the film A that prevents endothelialization, further ensure the effectiveness of the lumbar support frame in preventing endothelialization, and enhance the effect of long-term shunting.

[0030] 3. The coated stent provided by the present invention is provided with a sheathing tolerance structure, which may be a curling structure, a pleated structure or a segmented structure. This sheathing tolerance structure is used to compensate for the length difference between the film body and the support frame on the central axis of the sheath tube when the coated stent is sheathed, so that after being released to the target position, the surface of the support frame can be completely covered with the film body (the film body and the support rod in all areas are fixedly connected), and the loading and sheathing process of the coated stent is not affected, and it is therefore suitable for implantation via a percutaneous minimally invasive interventional approach.

[0031] 4. A buffer structure is provided on the edge of the support rod of the proximal support frame and / or the distal support frame of the coated stent provided by the present invention. The buffer structure is located in the edge area of ​​the support rod of the distal support frame and / or the proximal support frame and is completely covered in a thin film body, and is used to reduce the damage to the tissue caused by the edge of the support rod and to avoid delamination or peeling between the distal end of the support rod and the thin film body. A spacing structure is provided in the gap area between the buffer structure and the support rod skeleton to ensure that the distal end of the buffer structure can be elastically deformed relative to the edge of the support frame. The buffer structure and the spacing structure cooperate to enable the buffer structure to play the established function of reducing the damage to the tissue caused by the edge of the support rod.

[0032] 5. The edges of the proximal support frame and / or the distal support frame of the coated stent provided by the present invention are provided with a reinforcement structure composed of multiple reinforcement rods, and the reinforcement rods are fixedly connected to the edges on the distal support frame and are completely covered in the film body. This design not only avoids the film body from wrinkling or collapsing after the coated stent is loaded and sheathed multiple times, thereby accelerating the endothelialization of the coated stent and enhancing the long-term fixation safety, but also can enhance the adhesion force of the edge area of ​​the distal support frame on the target tissue, thereby preventing the support frame from shaking or falling during or after the release process.

[0033] 6. The coated stent provided by the present invention includes an anchoring structure, which includes a free portion of the anchoring structure and a connecting portion of the anchoring structure. The connecting portion of the anchoring structure is used to fixedly connect the support rod and the anchoring structure. The free portion of the anchoring structure protrudes from the outer surface of the support rod in a natural and unconstrained state. The aspect ratio of the free portion of the anchoring structure is between 2 and 50. The anchoring structure can undergo reversible elastic deformation and has morphological adaptability, thereby achieving damage-free anchoring with the target tissue.

[0034] 7. The buffer structure of the coated stent provided by the present invention is provided with an adaptive structure, which is located in the connection area between the buffer rod and the support rod on the distal end support frame, and the adaptive structure extends radially outward from the edge of the distal end support frame, and then bends obliquely across the edge of the distal end support frame toward the proximal direction and extends toward the center of the support frame. The adaptive structure has the following advantages: a) The adaptive structure extends radially outward from the edge of the distal end support frame, and then bends obliquely across the edge of the distal end support frame toward the proximal defense line, so that the adaptive structure has a larger curved arc, so that the entire adaptive structure tends to be flat, so that it is maximally attached to the outer surface of the distal end support frame. Therefore, the buffer structure and the support frame are fixedly connected as an adaptive structure in a relatively large curved arc shape and a relatively gentle turning shape. The adaptive structure and the edge of the support rod on the distal support frame, as well as the buffer rod, will contact the target tissue, which greatly increases the contact area and minimizes the stimulation and damage of the support frame to the target tissue, avoiding the edge of the support rod on the distal support frame in the prior art. The sharp and sharp shape contacts the tissue, which causes stimulation and inflammatory response to the tissue, as well as physical damage to the tissue due to mechanisms such as stress concentration; b) The adaptive structure as described above also has the characteristic of being attached to the outer surface of the distal support frame, which is not obtrusive relative to the distal support frame, reduces the space occupied at the target position, and greatly reduces the impact on hemodynamics. At the same time, the probability of thrombosis on the support frame is reduced.c) Compared with all the support rods in the edge area of ​​the distal end support frame, the adaptive structure has a much smaller cross-sectional area and a much higher elastic deformability, wherein the cross-sectional area of ​​the adaptive structure does not exceed half of the cross-sectional area of ​​all the support rods. ① Not only does the adaptive structure have a certain degree of radial expansion and contraction adjustment function, so it can adapt to a smaller surface area, which greatly expands the applicable population of the coated stent in the present invention, especially the Asian population and the minor population; of course, the impact on the adjacent tissues of the target position can also be minimized or controlled; ② It also enables the adaptive structure to have a certain degree of elastic deformability in the axial direction, which can adapt to the uneven tissues that may exist in the target area, significantly increase tissue conformity, and reduce the stimulation and damage of the support frame to the target tissue, so it has a wide range of anatomical morphological adaptability; d) As a buffer structure of the adaptive structure, due to the adaptive The adaptive structure is located at the distal end of the distal end support frame, and is curved in the proximal direction, obliquely crossing the edge of the distal end support frame and extending toward the center of the support frame. In the process of gradually unfolding the distal end support frame from the release sheath, or in the process of pulling the distal end support frame that has been fully stretched from the release sheath back to fit against the target tissue, when the coated stent may slip due to improper operation of the operator, the adaptive structure can always be stuck on one side of the target tissue and thus form a self-locking structure. This self-locking structure can prevent the coated stent from further sliding. This also means that the adaptive structure and part or all of the distal end support frame are always located on one side of the target position, so that the coated stent will not completely slide into the body, thereby avoiding adverse events. Therefore, it is convenient for the operator to make a secondary adjustment to the position of the coated stent through subsequent observation of images, ultimately ensuring that the coated stent operation can be carried out smoothly and be safely implanted in the target position. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1a This is a schematic diagram of a first embodiment of the present invention in which the coated stent is a hollow tubular structure, the film A only covers the inner surface of the lumbar support frame, and the film B only covers the outer surfaces of the proximal end support frame and the distal end support frame;

[0036] Figure 1b for Figure 1a A cross-sectional view of the mid-lumbar support frame;

[0037] Figure 2 This is a schematic diagram of the first embodiment of the present invention, in which the stent graft is a hollow tubular structure, and the film body covers the entire inner and outer surfaces of the stent graft;

[0038] Figure 3 This is a schematic diagram of a stent graft in a dumbbell-shaped structure in Embodiment 1 of the present invention, in which a thin film body covers the entire stent graft;

[0039] Figures 4a to 4c is a schematic diagram of the sheathing tolerance structure, where: Figure 4aIt is a curled structure; Figure 4b It is a folded structure; Figure 4c For segmentation structure;

[0040] Figure 5a It is a schematic diagram of a cross section of the entire stent graft when the film body is in a flexible sheet shape in the second embodiment of the present invention;

[0041] Figure 5b for Figure 5a A top view of

[0042] Figure 6 This is a schematic diagram of the thin film body in the second embodiment of the present invention being in the form of a flexible strip, wrapping the entire stent graft in a winding manner;

[0043] Figure 7 This is a schematic diagram of the film body in the second embodiment of the present invention being a biocompatible film D or coating covering the entire stent graft;

[0044] Figures 8a to 8f Schematic diagram of various buffer structures of the present invention, wherein Figure 8a An "S" shaped buffer structure is shown. Figure 8b A "matchstick" shaped buffer structure is shown, Figure 8c A "J" shaped buffer structure is shown. Figure 8d shows the buffer structure for the wrapped head, Figure 8e It shows that the buffer structure is an adaptive structure. Figure 8f The buffer structure is shown as another adaptive structure;

[0045] Figure 9a This is an implementation of the reinforcing rod in the present invention;

[0046] Figure 9b This is a schematic diagram of a first implementation of the second embodiment of the present invention, in which a reinforcement structure is provided;

[0047] Fig.10 It is a schematic diagram showing that an anchoring structure is provided on the distal end support frame of the stent graft in the present invention;

[0048] Fig.11 It is a schematic diagram showing that the distal end support frame and the proximal end support frame of the stent graft in the present invention are both provided with anchoring structures;

[0049] Fig.12a is a microstructure (SEM) image of film A in the present invention;

[0050] Figure 12b is a microstructure (SEM) image of film B in the present invention;

[0051] Fig.13This is a photo of the anatomical observation of the coated stent provided by the present invention 6 months after implantation in the target tissue.

[0052] Among them, 1 is a coated stent, 2 is a support frame, 5 is a film body, 6 is a target tissue, 7 is a sheath tolerance structure, 20 is a distal support frame, 21 is a lumbar support frame, 22 is a proximal support frame, 23 is a buffer structure, 24 is a reinforcing structure, 25 is an anchoring structure, 201 is a slot, 210 is a support rod, 211 is an inner cavity of the lumbar support frame, 212 is a connecting hole, 213 is a series coil, 230 is a buffer structure connecting part, 231 is a buffer structure free part, 232 is a buffer rod, 233 is a spacing structure, 240 is a reinforcing rod, 251 is an anchor structure free part, 252 is an anchor structure connecting part, 30000 is an adaptive structure, 50 is a film A, 51 is a film B, 52 is a film C, 70 is a curling structure, 71 is a pleated structure, and 72 is a segmentation structure. DETAILED DESCRIPTION

[0053] The technical solution proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In particular, due to the different contents to be highlighted in each drawing, different proportions are often used.

[0054] In order to more clearly describe a stent graft provided by the present invention, the terms "distal end" and "proximal end" are defined herein, and the above terms are conventional terms in the field of interventional medical devices. Specifically, "proximal end" refers to the end close to the operator during the operation, especially when the stent graft is loaded in the delivery system, and "distal end" refers to the end away from the operator during the operation, especially when the stent graft is loaded in the delivery system.

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and a number of specific embodiments.

[0056] Embodiment 1:

[0057] The novel coated stent provided by the present invention comprises a support frame 2 and a thin film body 5, wherein the support frame 2 is a wavy or mesh structure surrounded by a plurality of elastic support rods, and the support frame 2 comprises a proximal end support frame 22, a lumbar support frame 21 and a distal end support frame 20 from near to far, and the lumbar support frame 21 is in the shape of a hollow tube as a whole. The surface of the support frame 2 is covered or wrapped with a film body 5, and the film body 5 includes the film A50 and the film B51. The film A50 is a non-porous structure or a microporous structure, and the film B51 is a microporous structure. The pore size or node distance of the film A50 does not exceed 60μm, and the film A50 at least covers the inner surfaces of all support rods 210 of the lumbar support frame 21, wherein the inner surfaces are all surfaces of the support rods 210 in contact with the fluid; the pore size or node distance of the film B51 is greater than the pore size or node distance of the film A50, and the film B51 at least covers the outer surfaces of the edges of all support rods 210 of the proximal support frame 22 and / or the distal support frame 20, wherein the outer surfaces are all surfaces of the support rods 210 in contact with the target tissue 6. Since the support frame 2 is usually made of metal material, when it is directly implanted in the body, it will directly contact with the blood, so it lacks biocompatibility and has the risk of thrombosis on the surface of the metal stent to a certain extent. For this reason, the surface of the support frame 2 needs to be covered with the film body 5. After many tests and studies, we have concluded that when the pore size or internode distance of the film body 5 exceeds 60μm, cells in the human body, including various cells in the blood, may pass through the film body 5 and crawl and grow on the surface of the film body 5. Therefore, the surface of the lumbar support frame 21 in the present invention is designed to be covered with the film A51, and the pore size or internode distance of the film A51 does not exceed 60μm. The film A51 at least covers the inner surface of all support rods 210 of the lumbar support frame 21 to effectively prevent endothelialization, so that the lumen size of the lumbar support frame 21 can be maintained for a long time, so as to achieve the purpose of long-term shunting effectiveness.

[0058] The support frame 2 of the coated stent 1 of the present invention and the film body 5 covering the support frame 2 have multiple implementation modes. As a simple method, the coated stent 1 is a hollow tube or a hollow dumbbell as a whole, the length of each support rod of the support frame 2 is not more than 20 mm, the angle between adjacent support rods 210 is not more than 120°, the film A50 or the film B51 only covers the inner surface of the lumbar support frame 21, the distance between the distal end surface of the coated stent 1 and the distal end surface of the film A50 is L1, and the distance between the proximal end surface of the coated stent 1 and the proximal end surface of the film A50 is L2, as shown in FIG. Figure 1a , Figure 1bAs shown, L1 and L2 should be as small as possible, for example, L1 and L2 should satisfy the following mathematical relationship as much as possible: 0<L1≤10mm, 0<L2≤10mm; this design has the following advantages; a) the film A50 prevents the inner surface of the lumbar support frame 21 from endothelialization, so that the inner cavity size of the lumbar support frame 21 can be maintained for a long time to achieve the purpose of long-term shunting effectiveness; b) the edge area of ​​all support rods 210 of the proximal support frame 22 and the outer surface of the edge area of ​​all support rods 210 of the distal support frame 20 are covered with the film B, and the film B51 is a microporous structure, and the pore size or node distance of the film B51 is larger than the pore size or node distance of the film A50, but the pore size or node distance of the film B51 does not exceed 200μm, so that the edge area of ​​the support frame 2 can promote endothelialization, thereby realizing the fixed connection between the proximal and distal ends of the coated stent 1 and the target tissue 6, so as to enhance the long-term fixation of the support frame 2 at the target position.

[0059] In another embodiment, the proximal support frame 22, the lumbar support frame 21 and the distal support frame 20 are fixedly connected to each other in sequence by a plurality of support rods 210 to form a three-dimensional network structure, the stent graft 1 is rotationally symmetrical along the central axis m of the lumbar support frame 21, and the film body 5 covers the entire surface of the stent graft 1. The film body 5 is a flexible sheet, and the film body 5 includes the film A50 and the film B51. The film A50 is a non-porous structure or a microporous structure, such as Fig.12a As shown, the film A50 covers the inner and outer surfaces of all the support rods 210 of the waist support frame 21. The film B51 is a microporous structure, such as Figure 12b As shown, the pore size or node distance of the film B51 does not exceed 200 μm, and the film B51 at least covers the surface of all the support rods 210 in the edge area of ​​the proximal support frame 22 and / or the distal support frame 20, as shown in FIG. Figure 2 , Figure 3 As shown. Preferably, the pore size or node distance of the film A50 is at least 30 μm smaller than the pore size or node distance of the film B51, giving the film body 5 a significant differential endothelialization function. More preferably, the film B51 at least covers the edge of the support rod 210 of the proximal support frame 22 and / or the distal support frame 20, so that the edge of the proximal support frame 22 and the edge of the distal support frame 20 can play a role in promoting endothelialization, so as to enhance the long-term fixation of the support frame 2 at the target position; the film A50 on the lumbar support frame 21 can effectively prevent endothelialization, so that the lumen size of the lumbar support frame 21 can be maintained for a long time, so as to achieve the purpose of long-term shunting effectiveness.

[0060] The materials of the film A50 and the film B51 include one or more of polyparaxylene, titanium nitride, mucopolysaccharide sulfate, ceramic, polyethylene terephthalate, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, polyurethane, and heparin. Through molding processes such as gluing, heat welding, coating, and foaming, the film A50 can form a microporous structure or a non-porous structure, and the film B51 forms a microporous structure. If the film A50 and the film B51 are made of the same material, the film A50 and the film B51 can become an integrated seamless connection structure. The above design has the following advantages: a) The surface of the support frame 2 adopts a film body 5 with different pore sizes, that is, the film body 5 is given a differential endothelialization function design, especially for taking into account the clinical use effect of the differential endothelialization function, which can make The edge of the proximal support frame 22 and the edge area of ​​the distal support frame 20 play a role in promoting endothelialization to enhance the long-term fixation of the support frame 2 at the target position, while the rest of the coated stent 1 as an implant, especially the lumbar support frame 21, can effectively prevent endothelialization, so that the lumen of the lumbar support frame 21 can remain unobstructed for a long time to achieve the purpose of long-term shunting; b) the film A50 and the film B51 can become an integrated seamless connection structure, so that the connection area of ​​the film A50 and the film B51 is a smooth transition to avoid thrombus formation and affect the retraction and release sheath; of course, in order to minimize the influence of the retraction and release sheath as much as possible, the thickness of the film A50 and the film B51 should be as thin as possible, for example, 1-200μm.

[0061] In this embodiment, the coated stent 1 is provided with a sheathing tolerance structure 7, and the sheathing tolerance structure 7 has a certain reversible deformation, which can compensate for the length difference between the film body 5 and the support frame 2 on the central axis of the sheath tube when the coated stent 1 is sheathed, so that the surface of the support frame 2 can cover the film body 5 (the film body 5 and the support rod 210 in all areas are fixedly connected), and does not affect the loading and sheathing process of the coated stent 1, thereby meeting the requirements of the implantation technique of percutaneous puncture (such as through blood vessels, such as femoral vein) minimally invasive interventional approach.

[0062] In one embodiment, the sheathing tolerance structure 7 is a curling structure 70 and / or a pleated structure 71, and the curling structure 70 and / or the pleated structure 71 are arranged on the film B51. Figure 4a , Figure 4b As shown, the film body 5 has an elastic deformation (elongation) of 20% to 50%, which can compensate for the length difference between the film body 5 and the support frame 2 on the central axis of the sheath tube when the coated stent 1 is sheathed.

[0063] In another embodiment, the sheathing tolerance structure 7 is a segmentation structure 72, and the segmentation structure 72 is located on the film B51. Figure 4c As shown, and corresponding to the blank part (non-support rod area) located in the three-dimensional mesh structure, the arrangement of the segmentation structure 72 enables the thin film bodies 5 on both sides of the segmentation structure 72 to be physically separated. When the coated stent 1 is placed at the target position, in a natural and unconstrained state, the edges of the thin film bodies 5 on both sides of the segmentation structure 72 can touch or overlap, without affecting the preset differential endothelialization function of the thin film bodies 5; during the loading and sheathing process of the coated stent 1, the thin film bodies 5 on both sides of the segmentation structure 72, especially the adjacent edges, are separated from each other, which can compensate for the length difference between the thin film body 5 and the support frame 2 on the central axis, thereby not affecting the loading and sheathing process of the coated stent 1, and satisfying the implantation of the percutaneous puncture minimally invasive interventional approach.

[0064] Embodiment 2:

[0065] Based on the first embodiment, the second embodiment differs from the first embodiment in that the stent graft 1 is in a flat I-shape as a whole, and the entire surface of the support frame 2 is covered or wrapped with a thin film 5 .

[0066] On this basis, as a special implementation example, the coated stent 1 is an elastic atrial septal puncture stent (i.e., an atrial shunt) that can be placed at the atrial septum. Specifically, the support frame 2 is a wavy or mesh structure with multiple elastic support rods 210 fixedly connected, the number of layers of the wavy or mesh structure is 2-4 layers, the length of each support rod 210 is not more than 20 mm, and the angle between adjacent support rods 210 is not more than 120°. This design can realize the function of the sheathing tolerance structure 7 set on the film body 5 of the coated stent 1 to a certain extent - compensating for the length difference between the film body 5 and the support frame 2 on the central axis of the sheath tube when the coated stent 1 is sheathed, thereby ensuring that the coated stent 1 is smoothly loaded and sheathed, thereby meeting the implantation surgery of the minimally invasive interventional approach.

[0067] The support frame 2 includes, from near to far, a proximal support frame 22 that fits with the atrial septum surface in the right atrial cavity, a distal support frame 20 that fits with the atrial septum surface in the left atrial cavity, and a waist support frame 21 that is disposed between the proximal support frame 22 and the distal support frame 20 and fixedly connects the proximal support frame 22 and the distal support frame 20. There is a section α on the edge area of ​​the proximal support frame 22, and the section α is perpendicular to the central axis m of the support frame 2. There is a section β on the edge area of ​​the distal support frame 20, and the section β is perpendicular to the central axis m of the support frame 2. This design can enhance the fit of the edge areas of the distal support frame 20 and the proximal support frame 22 with the target tissue 6, and reduce the stimulation or damage of the edge areas of the distal support frame 20 and the proximal support frame 22 to the target tissue 6. The waist support frame 21 is in the shape of a hollow tube as a whole. The inner cavity of the waist support frame 21 enables fluid communication between the left atrium and the right atrium, thereby achieving flow shunt between the left atrium and the right atrium.

[0068] The entire surface of the support frame 2 is covered or wrapped with a film body 5, and the film body 5 includes a film A50 and a film B51. The film A50 is a non-porous structure, and the film A50 at least covers the surface of all the support rods 210 of the waist support frame 21; the film B51 is a microporous structure, and the film B51 at least covers the surface of all the support rods 210 in the edge area of ​​the proximal support frame 22 and / or the distal support frame 20. The pore size or node distance of the film A50 and the film B51 does not exceed 60μm, because too large a pore size or node distance will affect the contact area of ​​the support frame 2 itself with the target tissue 6 or blood, and affect its biocompatibility to a certain extent.

[0069] Preferably, the aperture or node distance of the film A50 is at least 30 μm smaller than the aperture or node distance of the film B51. More preferably, the film B51 covers at least the edge of the support rod 210 of the proximal support frame 22 and / or the distal support frame 20. This is because the support frame 2 is usually made of shape memory alloys, such as nickel-titanium alloys and other metal materials. When directly implanted in the body, it not only increases the area of ​​contact with blood, but also affects the biocompatibility of the product to a certain extent. At the same time, it increases the risk of thrombus formation on the surface of the metal stent; after many studies, we found that the design of covering the surface of the support frame 2 with the film body 5 can quickly and effectively solve this problem. Further studies have found that when the aperture or internode distance of the film body 5 exceeds 30 μm, various cells in the blood can easily pass through the film body 5, crawl on the surface of the film body 5 and accelerate endothelialization. Therefore, the surface of the waist support frame 21 of the present invention is designed to be covered with the film A50, and the internode distance of the film A50 should not exceed 30 μm, so as to ensure that the lumen size of the waist support frame 21 is maintained for a long time, thereby achieving a long-term permanent shunting effect. The surface or edge area of ​​all support rods 210 of the proximal support frame 22 and / or the distal support frame 20 needs to be covered or wrapped with the film B51 to promote endothelialization of the covered or wrapped area, thereby enhancing the long-term fixation of the support frame 2 at the target position.

[0070] In the first embodiment, the film body 5 is a flexible sheet, the film A50 and the film B51 are made of the same polymer material, the material includes polyethylene terephthalate, polytetrafluoroethylene, expanded polytetrafluoroethylene, polyurethane, silicone, and through bonding, heat bonding, coating, foaming and other molding processes, the film A50 forms a microporous structure, the pore size or node distance of the microporous structure is 10μm, and the pore size or node distance of the film B51 is 45μm. The support frame 2 is an integrated structure formed by laser engraving and heat setting of the same shape memory alloy tube. The edges of the distal end support frame 20 and the proximal end support frame 22 are both circular, wherein the maximum diameter of the distal end support frame 20 is D1, and the diameter of the proximal end support frame 22 is D3. The inner cavity diameter of the lumbar support frame 21 is D2, the axial height of the lumbar support frame 21 is 1mm-15mm, the diameter of the maximum area covered by the film A50 on the distal end support frame 20 is D4, and the diameter of the maximum area covered by the film A50 on the proximal end support frame 22 is D5, wherein D1, D2, D3, D4 and D5 preferably satisfy the following mathematical relationship: 15mm≤D1≤35mm, 3mm≤D2≤15mm, 15mm≤D3≤35mm, D2<D4≤D1-2, D2<D5≤D3-2, and the film B51 covers the remaining area of ​​the distal end support frame 20 and the remaining area of ​​the proximal end support frame 22, wherein the film A50 and the film B51 are an integrated seamless connection structure, such as Figure 5a , 5bAs shown. The above design has the following advantages: a) The surface of the support frame 2 adopts a film body 5 with different pore sizes, that is, the film body 5 is given a differential endothelialization functional design, especially in order to take into account the clinical use effect of differential endothelialization, the above mathematical relationship, especially D2<D4≤D1-2, D2<D5≤D3-2, can make the edge of the proximal support frame 22 and the edge area of ​​the distal support frame 20 play a role in promoting endothelialization, so as to enhance the long-term fixation of the support frame 2 at the target position of the atrial septum, while the rest of the coated stent 2 as an implant, especially In particular, the lumbar support frame 21 can effectively prevent endothelialization, so that the lumen of the lumbar support frame 21 can remain unobstructed for a long time, so as to achieve the purpose of long-term shunting; further, in order to fully ensure the effectiveness of the lumbar support frame 21 in preventing endothelialization, it is advisable to maximize the coverage area of ​​the film A50 that prevents endothelialization, so it should further satisfy the mathematical relationship: D2+2≤D4, and D2+2≤D5; b) the film body 5 is completely in contact with the support frame 2, and no wrinkles or bulges will appear during the sheathing and releasing process of the support frame 2, so it does not affect the loading and sheathing process. Furthermore, when the film body 5 is made of polymer materials including polytetrafluoroethylene, expanded polytetrafluoroethylene, polyurethane, and silicone, it can greatly reduce the friction resistance of the support frame 2 when it is retracted into or released from the sheath of the delivery system 31, thereby improving the smoothness of operation, enhancing the operator's operating experience during the operation, and also helping to achieve the controlled release of the coated stent 1 during the operation, and the capture and recovery after complete release; c) The film A50 and the film B51 are an integrated seamless connection structure, and the connection area has a smooth transition to avoid thrombus formation and affect the release of the sheath. For the support frame 2 with a differential endothelialization function design given to the film body 5, we implanted it into the target tissue of the atrial septum of the pig for 6 months ( Fig.13 ), no thrombus was observed on the surface of the support frame 2, but a large amount of new endothelial tissue was formed on the proximal support frame 22 covered with the film B51, especially in the edge area. At the same time, the lumen of the lumbar support frame 21 remained unobstructed, and the lumen size was exactly the same as the inner lumen diameter D2 of the lumbar support frame 21 before implantation. Therefore, after the coated stent 1 was implanted into the target tissue 6, the size of the lumen channel of the lumbar support frame 21 was effectively maintained for a long time without stenosis or even blockage. Compared with similar products on the market, the effectiveness of long-term shunting is better.

[0071] In the second embodiment, the film body is a film C52, which is in the form of a flexible strip and is made of the same material and has the same pore size as the film B51; the film C52 is wrapped around the support rod 210 of the support frame 2 in a winding manner and completely covers the support frame 2. Figure 6As shown. In this embodiment, the film body 5 is wound around and wrapped with a single flexible round wire or flat wire all the support rods 210 of the support frame 2. The advantage of this winding method using a single flexible round wire or flat wire is that the number of knots between the film body 5 and the support frame 2 is minimized, the number of knots is reduced, and the increase in the retraction and release resistance of the entire stent graft 2 due to too many knots is avoided. To a certain extent, the manufacturing process is also simplified, and the production efficiency is improved.

[0072] Preferably, a connection hole 212 is provided at the edge node of the support rod 210, and the film C52 can pass through the connection hole 212 and wrap around the support rod 210 in a winding manner, and completely cover the support frame 2. This design has the following advantages: a) The connection hole 212 can fix the film C52, enhance the effectiveness and firmness of the connection, ensure that the film body 5 maintains a predetermined winding form on the support frame 2, and avoid the film C52 from slipping on the support rod 210 during the process of entering and exiting the sheath; b) The film C52 completely covers the support frame 2, reducing the surface area of ​​the metal in the coated stent 1 that is in direct contact with the blood, and also reducing the risk of complications such as thrombosis on the surface of the coated stent 1; c) The film C52 preferably uses a material with a lower friction coefficient than the support frame 2, such as expanded polytetrafluoroethylene, which can not only reduce the friction resistance of the coated stent 1 entering and exiting the delivery system 31 during installation or release, but also improve the operating feel and ensure the controllability of installation and release.

[0073] In a third embodiment, the film body 5 can be made of a biocompatible film D53, such as polyparaxylene, titanium nitride, mucopolysaccharide sulfate and other biocompatible materials, and can be coated or magnetron sputtered to cover the stent graft 2. Figure 7 As shown. The film D53 has a thickness of 1-100 μm, which can effectively enhance the adhesion of the film D53 to the surface of the metal material, and can modify the surface of the metal material implanted in the human body for a long time to improve its corrosion resistance and biocompatibility. In addition, this embodiment has the following advantages: a) the film D53 can prevent the endothelialization of the inner surface of the lumen of the lumbar support frame 21, so that the lumen of the lumbar support frame 21 remains unobstructed for a long time; b) reduce the risk of thrombosis on the surface of the coated stent.

[0074] In this embodiment, a buffer structure 23 is provided on the edge of the support rod 210 of the proximal support frame 22 and / or the distal support frame 20 of the coated stent 2. The buffer structure 23 and the edge area of ​​the support rod 210 of the distal support frame 20 or the proximal support frame 22 are on the same plane, and the buffer structure 23 is completely covered in the film B51, so as to reduce the damage of the edge of the support rod 210 to the tissue and avoid stratification or peeling between the distal end of the support rod 210 and the film body 5.

[0075] In one embodiment, the buffer structure 23 includes a buffer structure free portion 231 and a buffer structure connecting portion 230, so that the buffer structure 23 undergoes elastic deformation. The buffer structure 23 and the support rod 210 of the distal end support frame 20 are an integrated structure formed by laser engraving and heat setting of a shape memory alloy, that is, the distal end of the buffer structure connecting portion 230 is located on the edge of the support rod 210 on the distal end support frame 20, the proximal end of the buffer structure free portion 231 is connected to the proximal end of the buffer structure connecting portion 230, and the distal end of the buffer structure free portion 231 is in a free state.

[0076] The buffer structure 23 is a "J" or "S" or "match" shaped structure as a whole. Figures 8a to 8c As shown, the buffer structure 23 is on the same plane as the edge area of ​​the support rod 210 of the distal support frame 20 or the proximal support frame 22; preferably, the rod width of the buffer structure 23 should be 1 / 3 to 3 / 4 of the rod width of the support rod 210 on the distal support frame 20, and the overall cross-sectional area of ​​the buffer structure 23 does not exceed 3 / 4 of the edge cross-sectional area of ​​the support rod 210 on the distal support frame 20, so that the buffer structure 23 has a certain flexibility. In addition, the buffer structure 23 also has the following advantages: a) simple process and high preparation efficiency; b) can increase the flexibility of the edge of the distal support frame 20 to avoid damaging the target tissue of the atrial septum.

[0077] In a second embodiment, the buffer structure 23 is a wrapping head covering and / or wrapping the edge of the support rod 210 on the distal end support frame 20 and / or the proximal end support frame 22, such as Figure 8dAs shown. The wrapping head is flexible or elastic, and the wrapping head is made of polymer materials such as polyurethane, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, etc. Preferably, a slot structure 201 is provided on the edge of the support rod 210 of the distal support frame 20 and / or the support rod 210 of the proximal support frame 22, and the slot structure 201 can prevent the wrapping head from sliding relative to the edge of the support rod 210 of the distal support frame 20 and / or the support rod 210 of the proximal support frame 22, thereby affecting the buffering effect. The buffering structure 23 in this embodiment can also increase the edge flexibility of the support rod 210 on the distal support frame 20 and / or the support rod 210 on the proximal support frame 22, thereby avoiding damage to the target tissue of the atrial septum.

[0078] In the third embodiment, the buffer structure 23 is composed of a plurality of buffer rods 232, and the number of the buffer rods 232 is an even number. The proximal ends of each two adjacent buffer rods 232 are connected to the edge of the support rod 210 on the distal support frame 20, and each two adjacent buffer rods 232 are fixedly connected at the distal end and converge at a buffer connection member; the buffer connection member is a boss structure, and the boss structure can prevent the film C52 wrapped around the buffer rod 232 from slipping relative to the buffer rod 232 under the action of external force.

[0079] The proximal region of the buffer rod 232 is provided with an adaptive structure 30000, such as Figure 8e As shown. The adaptive structure 30000 has anatomical morphological adaptability; the adaptive structure 30000 is radially outward from the edge of the distal end support frame 20, and then extends in a curved shape on the plane α in a direction away from the support frame 2, and the bending angle θ of the adaptive structure 30000 satisfies: 10°≤θ≤135°; wherein the bending angle θ is defined as the angle formed between the radial outward direction of the edge surface of the distal end support frame 20 and the inward direction of the tangent of the proximal end of the buffer rod 232. In a natural unconstrained state, the buffer structure 23 is radially outward, has anatomical morphological adaptability, and can be attached to the target tissue 6 without damage, thereby avoiding or reducing damage to the target tissue of the atrial septum.

[0080] Preferably, the buffer structure 23 and the support frame 2 are an integrated structure formed by laser engraving and heat setting from the same shape memory alloy tube, and the width of the buffer rod 232 is 1 / 3 to 2 / 3 of the width of the support rod 210 on the distal end support frame 20. The adaptive structure 30000 extends radially outward from the edge of the distal end support frame 20, and then extends in a curved shape in the proximal direction across the edge of the distal end support frame 20 and toward the center of the support frame 2, and the distal end of the adaptive structure 30000 is located outside the area covered by the lumbar support frame 21, such as Figure 8f This design has the following advantages:

[0081] a) The buffer structure 23 and the edge of the support rod 210 on the distal support frame 20 will contact the target tissue 6, which greatly increases the contact area, minimizes the stimulation and damage of the support frame 2 to the target tissue 6, and avoids the edge of the support rod 210 on the distal support frame 20 in the prior art from contacting the tissue in a relatively sharp and sharp form, thereby causing stimulation and inflammatory response to the tissue, as well as physical damage to the tissue due to mechanisms such as stress concentration;

[0082] b) The buffer structure 23 as described above is located in the area covered by the distal support frame 20, and has no effect on the diameter of the distal support frame 20; in addition, it is attached to the outer surface of the distal support frame 20, and is not obtrusive relative to the distal support frame 20, thereby reducing the space occupied in the left atrium and greatly reducing the impact on hemodynamics. At the same time, the probability of thrombosis on the support frame 2 is reduced;

[0083] c) Compared with all the support rods 210 in the edge area of ​​the distal end support frame 20, the buffer structure 23 has a much smaller cross-sectional area and a much higher elastic deformability, wherein the cross-sectional area of ​​the buffer structure 23 does not exceed half of the cross-sectional area of ​​all the support rods 210. ① The buffer structure 23 not only has a certain degree of radial expansion and contraction adjustment function, so it can adapt to a smaller atrial septum surface area, especially the area on the left atrial surface of the atrial septum, which greatly expands the applicable population of the stent graft, especially the Asian population, and the minor population; of course, the influence on the adjacent tissues of the atrial septum, such as the mitral valve and the pulmonary vein, can also be minimized or controlled; ② The buffer structure 23 also has a certain degree of elastic deformability in the axial direction, which can adapt to the uneven tissue that may exist in the left atrial side area of ​​the atrial septum, significantly increase tissue adhesion, and reduce the stimulation and damage of the stent graft 1 to the target tissue 6, so it has a wide range of anatomical morphological adaptability;

[0084] d) In the prior art, during the process of gradually deploying the distal end support frame 20 from the release sheath, or during the process of pulling the distal end support frame 20 that has been fully deployed from the release sheath back to the left atrial side of the atrial septum tissue, due to improper operation by the operator, the delivery system is mistakenly withdrawn, causing the coated stent 2, especially the distal end support frame 20, to slide from the left atrial cavity through the puncture hole on the atrial septum tissue into the right atrial cavity. In the present invention, the buffer structure 23 is provided on the distal end support frame 20, and is particularly used as the buffer structure 23 of the adaptive structure 30000. Since the adaptive structure 30000 is located at the distal end of the distal end support frame 20, and is curved and obliquely crosses the edge of the distal end support frame 20 in the proximal direction and extends toward the center of the support frame 2, during the process of gradually unfolding the distal end support frame 20 from the release sheath, or during the process of pulling the distal end support frame 20 that has been fully stretched from the release sheath back to the left atrial side of the atrial septum tissue, when the coated stent 2 may slip due to improper operation by the operator When the implant is performed, the adaptive structure 30000 can always be stuck on the left atrial side of the target tissue of the atrial septum, thereby forming a self-locking structure. This self-locking structure can prevent the coated stent 2 from further sliding down, which also means that the adaptive structure 30000 and part or all of the distal end support frame 20 are always located in the left atrial cavity, and the coated stent 2 will not completely slide into the right atrial cavity, thereby avoiding the above-mentioned disadvantages; therefore, it is convenient for the operator to make a secondary adjustment to the position of the coated stent 2 through subsequent observation of the image, and finally ensure that the atrial septal puncture surgery can be carried out smoothly and the coated stent 2 can be safely implanted in the target position.

[0085] Furthermore, when the film body 5 is of the first embodiment, for the above-mentioned first buffer structure 23, a spacing structure 233 should be provided in the gap area between the buffer structure 23 and the edge of the support rod 232 skeleton, and the spacing structure 233 is located on the film B51. Preferably, the spacing structure 233 is in the shape of a slit, dividing the film B51 into two parts that can move relative to each other, thereby avoiding that the buffer structure connection part 230, the buffer structure free part 231 and the gap between the buffer structure connection part 230 and the buffer structure free part 231 are all covered by the film B51, so that the buffer structure free part 231 is no longer in a constrained state, thereby ensuring that the distal part of the buffer structure 23, that is, the buffer structure free part 231, can undergo elastic deformation relative to the edge of the support frame 2, and the buffer structure 23 and the spacing structure 233 cooperate to enable the buffer structure 23 to play the established function of reducing the damage to the tissue by the edge of the support rod 210.

[0086] Embodiment three:

[0087] Based on Example 2, Example 3 differs from Example 2 in that: a reinforcing structure 24 is provided at the edge of the proximal support frame 22 and / or the distal support frame 20 of the coated stent 1, and the reinforcing structure 24 may be composed of one or more reinforcing rods 240, and the reinforcing structure 24 is fixedly connected to the edge of the support frame 2 and completely covered in the film body 5, so as to avoid wrinkling or collapse of the film body 5 after the coated stent 1 is sheathed and unsheathed multiple times, thereby accelerating the endothelialization of the coated stent 1 and enhancing the long-term fixation safety, and can also enhance the abutment force of the edge area of ​​the distal support frame 20 on the target tissue 6 to prevent the support frame 2 from shaking or falling during or after the release process.

[0088] In one embodiment, the reinforcement structure 24 is composed of a plurality of reinforcement rods 240, and the reinforcement rods 240 and the support frame 2 are an integrated structure formed by laser engraving and heat setting the same shape memory alloy tube. Figure 9a As shown. This design has the following advantages: a) the process is simple and the manufacturing is convenient; b) the reinforcing structure 24 can improve the roundness of the edge of the proximal support frame 22 and / or the distal support frame 20 of the coated stent 1; c) after the coated stent 1 is retracted and released multiple times, the film B51 covering the edge area of ​​the distal support frame 20 and / or the edge area of ​​the proximal support frame 22 is prevented from wrinkling or collapsing, so that the film B51 together with the support rod 210 of the distal support frame 20 and / or the support rod 210 of the proximal support frame 22 are fully in contact with the atrial septal tissue, thereby accelerating the endothelialization of the proximal support frame 22 and improving the long-term fixation safety of the coated stent 1.

[0089] Further preferably, the rod length of the reinforcing rod 240 satisfies: L3+L4=L5+L6, and the distal node of the reinforcing structure 24 is radially connected with the node of the support rod 210 on the distal end support frame 20 to form a connecting rod structure to enhance the smoothness of the coated stent 1 being retracted into the sheath tube.

[0090] In another embodiment, the reinforcing structure 24 and the support frame 2 are a combined structure, and the reinforcing structure 24 is made of the same shape memory alloy wire as the reinforcing rod 240, and the shape memory alloy wire sequentially passes through all the through holes at the edge nodes of the support rod 210 on the distal end support frame 20 to form a non-closed annular wavy structure, and the two ends of the shape memory alloy wire respectively pass through the two side walls of the last through hole, and after being fixedly connected with the corresponding side walls, extend toward the center along the corresponding support rod 210 in a curved shape. Preferably, a flexible sheet-like film C52 is wrapped around the area where the reinforcing rod 240 and the support rod 210 contact, and this design can not only enhance the fit between the two ends of the reinforcing rod 240 and the support rod 210, and avoid the two ends of the reinforcing rod 240 from warping and piercing the film body 5 on the support frame 2; but also enhance the fit between the two ends of the reinforcing rod 240 and the support rod 210 and the film body 5, so that the reinforcing rod 240 can be completely covered in the film body 5.

[0091] Preferably, the reinforcing rod 240 is fixedly connected to the side wall of each through hole, and no relative sliding occurs between the reinforcing rod 240 and the through hole. Figure 9b As shown, this design can strengthen the fixing effect of the reinforcing rod 240 and the edge of the support frame 2, and prevent the reinforcing rod 240 from slipping relative to the support frame 2 and the film body 5 after the coated stent 1 is retracted and released multiple times, thereby preventing the reinforcing rod 240 from wearing or scratching the film body 5.

[0092] Embodiment 4:

[0093] Based on Example 2, Example 4 differs from Example 2 in that: the coated stent 1 also includes an anchoring structure 25, which can undergo reversible elastic deformation, has morphological adaptability, and achieves damage-free anchoring with the target tissue; the anchoring structure 25 includes an anchoring structure free portion 251 and an anchoring structure connecting portion 252, and the anchoring structure connecting portion 252 is located on the support rod 210, and is used to fixedly connect the support rod 210 and the anchoring structure 25; the anchoring structure free portion 251 protrudes from the outer surface of the support rod 210 in a natural unconstrained state; the aspect ratio of the anchoring structure free portion 251 is between 2 and 50.

[0094] The anchoring structure 25 can undergo reversible elastic deformation, has morphological adaptability, and can achieve non-destructive anchoring with the target tissue.

[0095] In one embodiment, an anchoring structure 25 is provided on the support rod 210 on the inner side (inner side: the side in contact with the target tissue) of the distal end support frame 20, and the anchoring structure 25 and the support frame 2 are an integrated structure formed by laser engraving and heat setting of the same shape memory alloy tube, such as Fig.10 The anchoring structure 25 comprises an anchoring structure free portion 251 and an anchoring structure connecting portion 252, wherein the connecting portion 252 is located on the support rod, the anchoring structure free portion 251 protrudes from the outer surface of the support rod 210, and the length-to-width ratio of the anchoring structure free portion 251 is 2 to 50. The anchoring structure 25 has the following characteristics:

[0096] a) It can undergo reversible elastic deformation, has morphological adaptability, and can achieve non-damage anchoring with the target tissue;

[0097] b) After the stent graft 1 is pressed and gripped, the direction of the anchoring structure 25 is consistent with the direction of sheathing, and no resistance or very little resistance is generated during the sheathing process, which does not affect the sheathing process of the stent graft 1;

[0098] c) During the release of the coated stent 1, the anchoring structure 25 on the distal support frame 20 can be anchored in the target tissue on the distal side under the action of the withdrawal force, thereby achieving an anchoring effect, so that the coated stent 1 can be safely released to the target position to avoid incomplete release and ejection to other positions such as the left atrium or aorta.

[0099] After the sheath is placed at the target position, the proximal support frame 22 is slowly pushed out of the sheath and gradually unfolded. The sheath handle is slowly withdrawn proximally, and the unfolded distal support frame 20 is slowly placed on the left atrial side of the atrial septum and fits with the target tissue. Under the action of the withdrawal force, the anchoring structure 25 is hooked and elastically fixed on the atrial septum tissue on the left atrial side, which plays an anchoring effect. On the one hand, it enables the coated stent 1 to be safely released to the target position of the atrial septum to avoid incomplete release and ejection to other places such as the left atrium or the aorta; on the other hand, it can reduce the impact of the coated stent 1 on the target tissue. In addition, because the anchoring structure 25 is thin and small, the trauma caused to the target tissue of the atrial septum is small.

[0100] In one embodiment, the inner side of the support rod 210 on the distal end support frame 20 and the inner side of the support rod on the proximal end support frame are both provided with an anchoring structure 25 ( Fig.11 As shown in FIG. 1 , the direction of the anchoring structure 25 is consistent with the direction of the sheath tube. This design has the following advantages:

[0101] a) When the anchoring structure 25 is retracted into the sheath, it is consistent with the direction in which the coated stent 1 is retracted into the sheath. If the lumen size of the sheath is appropriate, the friction resistance will not be increased to affect the sheath retraction process of the support frame 2;

[0102] b) The deployment process of the proximal support frame 22 is slow, continuous and controllable; during this process, the proximal support frame 22 is fully stretched and fits to the target tissue, and the anchoring structure 25 can be anchored to the target tissue on the right atrial side of the atrial septum under the action of the rebound force of the proximal support frame 22, so as to enhance the fixation effect of the coated stent 1 at the target tissue and avoid shaking or falling out of the target tissue when it is not fully released.

[0103] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A novel stent graft, comprising a support frame and a thin film body, wherein the support frame is a wavy or mesh structure surrounded by a plurality of elastic support rods, and the support frame comprises a proximal end support frame, a lumbar support frame and a distal end support frame from near to far, and the lumbar support frame is in a hollow tubular shape as a whole, characterized in that: The film body at least includes film A and film B, wherein film A is a microporous structure or a non-porous structure, the pore size or node distance of film A does not exceed 60 μm, and film A at least covers the inner surfaces of all support rods of the lumbar support frame, wherein the inner surfaces are all surfaces of the support rods in contact with the fluid; film B is a microporous structure, the pore size or node distance of film B is greater than the pore size or node distance of film A, and film B at least covers the outer surfaces of the edge areas of all support rods of the proximal support frame and / or the distal support frame, wherein the outer surfaces are all surfaces of the support rods in contact with the target tissue; The proximal support frame, the lumbar support frame and the distal support frame are fixedly connected to each other in sequence by a plurality of support rods to form a three-dimensional network structure. The coated stent is rotationally symmetrical along the central axis m of the lumbar support frame, and the film body covers the entire surface of the coated stent, wherein the surface includes the inner surface and the outer surface of the support frame and the blank part of the three-dimensional network structure. The film body is a flexible sheet, and the thickness of the film body is between 1μm-200μm; the coated stent is provided with a sheathing tolerance structure, and the sheathing tolerance structure is used to compensate for the length difference between the film body and the support frame on the central axis of the sheath tube when the coated stent is sheathed.

2. The stent graft according to claim 1, characterized in that: The film A is a non-porous structure, and the film A covers the inner and outer surfaces of all the support rods of the lumbar support frame; the film B is a microporous structure, and the pore size or node distance of the film B does not exceed 200μm. The film B covers the inner and outer surfaces of the edge part or all of all the support rods of the proximal support frame and / or the distal support frame, and the film A and the film B are an integrated seamless connection structure.

3. The stent graft according to claim 2, characterized in that: The pore size or node distance of the film A is at least 30 μm smaller than the pore size or node distance of the film B, giving the film body a differential endothelialization function.

4. The stent graft according to claim 3, characterized in that: The sheathing tolerance structure includes a curling structure, a pleated structure or a splitting structure arranged on the film B, and the curling structure or the pleated structure enables the film body to have an elongation rate of 20% to 50%. The splitting structure is located in the blank part of the three-dimensional network structure, so that the film bodies on both sides of the splitting structure are physically separated. In a natural unconstrained state, the film bodies on both sides of the splitting structure can touch or overlap. During the loading and sheathing process, the film bodies on both sides of the splitting structure are separated from each other.

5. The stent graft according to claim 4, characterized in that: A buffer structure is provided on the edge of the support rod of the proximal support frame and / or the distal support frame of the coated stent, and the buffer structure is on the same plane as the edge area of ​​the support rod of the distal support frame and / or the proximal support frame, and the buffer structure is completely covered in the film body, so as to reduce the damage of the edge of the support rod to the tissue and avoid delamination or peeling between the distal end of the support rod and the film body, and the film B is provided with a spacing structure, which is located in the gap area between the buffer structure and the support rod skeleton, and the spacing structure ensures that the distal end part of the buffer structure can be elastically deformed relative to the edge of the support frame.

6. The stent graft according to claim 4, characterized in that: A buffer structure is provided on the edge of the support rod of the distal end support frame of the coated stent, and the buffer structure and the support frame are an integrated structure formed by laser engraving and heat setting of the same shape memory alloy tube; the buffer structure is composed of an even number of buffer rods, and every two adjacent buffer rods are fixedly connected at the distal end and converge at the connection part of the buffer structure; an adaptive structure is provided in the proximal area of ​​the buffer rod; the adaptive structure has anatomical morphological adaptability, radially outward from the edge of the distal end support frame, and then bends in the proximal direction to obliquely cross the edge of the distal end support frame and extend toward the center of the support frame, and the bending angle θ satisfies: 90°≤θ≤175°, or radially outward from the edge of the distal end support frame, and then bends on the plane α to extend in a direction away from the support frame, and the bending angle θ satisfies: 10°≤θ≤135°.

7. The stent graft according to claim 1, characterized in that: The coated stent includes a reinforcement structure; the reinforcement structure is composed of a plurality of reinforcement rods; the reinforcement rods are fixedly connected to the support rods of the proximal support frame and / or the distal support frame, and are used to enhance the contact force of the edge area of ​​the proximal support frame and / or the distal support frame on the atrial septal tissue, and further prevent the support frame from shaking or falling during or after the release.

8. The stent graft according to claim 1, characterized in that: The stent graft further comprises an anchoring structure; the anchoring structure can undergo reversible elastic deformation, has morphological adaptability, and achieves non-destructive anchoring with the target tissue; the anchoring structure comprises: an anchoring structure free portion and an anchoring structure connecting portion; The anchoring structure connecting portion is used to fixedly connect the support rod and the anchoring structure; the free portion of the anchoring structure protrudes from the outer surface of the support rod in a natural unconstrained state; the aspect ratio of the free portion of the anchoring structure is between 2 and 50.

9. The stent graft according to any one of claims 1 to 8, characterized in that: The length of each support rod is not more than 20 mm, and the angle between adjacent support rods is not more than 120°; the stent graft is in the shape of a hollow tube or a hollow dumbbell as a whole, and is defined as follows: the distance between the distal end surface of the stent graft and the distal end surface of the film A is L1, and the distance between the proximal end surface of the stent graft and the proximal end surface of the film A is L2, and L1 and L2 satisfy the following mathematical relationship: 0<L1≤10mm, 0<L2≤10mm; Alternatively, the coated stent is in a flat I-shape as a whole, and there is a section α on the edge area of ​​the distal end support frame, and the section α is perpendicular to the central axis m of the coated stent. There is a section β on the edge area of ​​the proximal end support frame, and the section β is perpendicular to the central axis m of the coated stent. The number of grid layers of the mesh structure is 2-4 layers, and the definition is: the maximum outer diameter of the distal end support frame is D1, the inner diameter of the lumbar support frame is D2, the maximum outer diameter of the proximal end support frame is D3, the maximum diameter of the distal end support frame area covered by the film A is D4, and the maximum diameter of the proximal end support frame area covered by the film A is D5, wherein D1, D2, D3, D4 and D5 satisfy the following mathematical relationships: 15mm≤D1≤35mm, 3mm≤D2≤15mm, 15mm≤D3≤35mm, D2<D4≤D1-2mm, D2<D5≤D3-2mm.

10. The stent graft according to claim 9, characterized in that: The film body further comprises a film C, which is in the form of a flexible strip and is wrapped around the surface of the buffer structure and / or the reinforcement structure in a winding manner to completely wrap the entire buffer structure; The materials of the film A, the film B and the film C include one or more of polyparaxylene, titanium nitride, mucopolysaccharide sulfate, ceramic, polyethylene terephthalate, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, polyurethane, and heparin, and the film A, the film B and the film C are made of the same material.

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