Absorbable stent

Abstract

The utility model particularly relates to an absorbable stent which comprises a first stent body and a second stent body, the first stent body is of a tubular structure and comprises a plurality of metal wires which are woven in a staggered mode, and the metal wires comprise one or two of molybdenum wires and molybdenum alloy wires. The second stent is arranged on the peripheral surface of the first stent, and the second stent comprises absorbable polymer filaments. The absorbable stent disclosed by the utility model has good structural performance, realizes that the whole body of the stent is visible in the pushing and releasing process, and is beneficial to avoiding the defects that the continuous external expansion force causes damage to the endovascular intima, the inflammation of the endovascular intima is possibly induced, restenosis is caused by excessive hyperplasia and the like, and the absorbable stent is suitable for being used in the medical field. Therefore, the problem that an existing absorbable intravascular stent is poor in using effect can be effectively solved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of medical apparatus and instruments, and particularly relates to an absorbable stent. BACKGROUND

[0002] Intracranial aneurysm is an abnormal bulge on the intracranial arterial wall and is the primary cause of subarachnoid hemorrhage. In cerebrovascular accidents, it ranks third only next to cerebral thrombosis and hypertensive cerebral hemorrhage. Aneurysm rupture and hemorrhage can damage brain tissue and related complications, and severe cases can lead to ischemic necrosis of brain tissue, coma and hemiplegia. Among them, there are many causes of aneurysm, such as congenital defects of the arterial wall, postnatal degeneration, and craniocerebral trauma, which can all cause intracranial aneurysm. The current treatment of intracranial aneurysm mainly includes: simple spring embolization treatment, balloon-assisted spring coil treatment, stent-assisted spring coil treatment, and absorbable stent treatment.

[0003] Among them, stent-assisted spring coil treatment is the mainstream aneurysm treatment method in clinical practice. With the assistance of the stent, previously intractable or unembolizable intracranial wide-necked and small aneurysms can achieve good treatment results, increasing the embolization rate and preventing aneurysm recurrence. The stent's wall adhesion performance in the blood vessel is an important characteristic among many stent properties, and it plays a crucial role in the clinical effect during and after surgery. During the operation, the doctor needs to observe the release of the stent with the help of X-rays to ensure that the stent is accurately implanted at the lesion site. In the long-term implantation process after surgery, follow-up is needed to ensure that the stent has good wall adhesion performance and does not shift to cause new thrombosis.

[0004] Vascular stents can be divided into permanent stents and absorbable stents according to the length of time they remain in the blood vessel. Permanent stents are made of non-degradable materials, including bare stents and drug-eluting stents, such as 316L stainless steel, platinum-chromium alloy, nickel-titanium alloy, cobalt-chromium alloy, tantalum, and titanium. The stent can keep the narrow blood vessel open and provide a lasting mechanical support, but the stent expansion process can cause endothelial damage, inducing inflammation and excessive proliferation of the intima, leading to restenosis. Permanent stents also have late and very late thrombosis, bleeding complications, mismatched flexibility, and the permanent presence of metal in the body increases the incidence of long-term restenosis.

[0005] After the absorbable stent is implanted in the blood vessel, it provides sufficient support to the blood vessel in the early stage, and releases drugs to treat the diseased blood vessel. After the treatment is completed, the vascular stent is gradually absorbed, thereby preventing restenosis. According to the different materials, there are currently two types of absorbable vascular stents. One type is made of high molecular polymer materials, such as polylactic acid, polycaprolactone, and polyiodinated tyrosine alkyl carbonate. The other type is made of metal materials, such as magnesium-based, iron-based, and zinc-based alloys.

[0006] At present, the polymer-made stent has the following technical problems: compared with the metal-made stent, the strength is small, and the radial support force is not sufficient; even if the thickness of the stent strut is increased to obtain the same radial support force as the metal stent, the restenosis rate will increase, and the delivery to the affected part will be lost, so it is not practical. In the case of a large stent strut, it is difficult to apply it to a blood vessel with a diameter of 3 mm or less, and it lacks universality, and at the same time, it is pointed out that due to excessive expansion, damage occurs on the blood vessel wall, thereby becoming a cause of restenosis or stent thrombosis.

[0007] For the structure of the metal stent, it is divided into laser cutting stent and braided stent. Among them, the laser engraved stent has a wider stent mesh and slightly worse wall adhesion, and there is a possibility of spring ring escape during the operation, and the metal coverage of the stent is low, which increases the risk of surgery and the recurrence rate after surgery; the braided stent, due to its large support force, good wall adhesion, small mesh and high metal coverage, can better adhere to the artery wall and prevent spring ring escape, reducing the difficulty of surgery and reducing the long-term recurrence rate. At the same time, the braided stent has a large support force and good flexibility, which can pass through or reach a more distant blood vessel location.

[0008] The metal materials for absorbable vascular stents mainly include magnesium alloy materials, pure iron materials and zinc alloy materials. Magnesium alloy materials have good biocompatibility, but the mechanical properties of magnesium alloy materials are poor, and the corrosion rate is too fast. The maximum elongation of the magnesium alloy stent is low, so it brings great challenges to the structural design of the magnesium alloy stent, and it is difficult to ensure the good mechanical properties of the stent. At the same time, because the corrosion rate of the magnesium alloy stent is too fast, it must be controlled by a complex material manufacturing process to control its absorption rate by the human body. Iron is an essential element for the human body, and pure iron has good biocompatibility and mechanical properties. Compared with polymer stents or magnesium alloy stents of the same wall thickness, iron stents can provide sufficient radial support to the diseased blood vessels at the lesion site. However, iron-based stents have the disadvantage of surrounding vascular calcification, and the degradation rate after implantation is too slow (2-3 years), so the iron stent with ordinary structural design will be absorbed by the human body for a long time, which will constrain the diameter of the blood vessel during this process. The degradation rate of zinc-based alloy is moderate, but the mechanical properties are poor, and the poor corrosion mode and cytotoxicity of zinc alloy limit the application of this material in degradable materials.

[0009] Therefore, the existing absorbable vascular stents have the following problems and shortcomings:

[0010] 1. The above metal vascular stents are not degradable and have the risk of long-term vascular proliferation, thrombosis and restenosis;

[0011] 2. The performance of the above degradable metal stent materials is not balanced, and it is difficult to achieve good therapeutic purposes and clinical benefits;

[0012] 3. The above-mentioned biodegradable polymer stents are inferior to metal stents in terms of size, support strength and other structural performance, and their clinical benefits are not significant.

[0013] 4. The imaging effect of the above-mentioned vascular stents under X-ray is limited. Most of them add imaging points at both ends to achieve visualization. The operator cannot directly observe the overall condition of the stent, and different imaging materials can cause slit corrosion. Utility Model Content

[0014] The purpose of this invention is to at least solve the problem of poor performance of existing absorbable vascular stents. This purpose is achieved through the following technical solution:

[0015] This utility model proposes an absorbable stent, comprising:

[0016] The first support is a tubular structure and includes multiple interwoven metal wires, the metal wires being one or both of molybdenum wires and molybdenum alloy wires.

[0017] The second support is disposed on the outer peripheral surface of the first support, and the second support includes highly absorbable molecular filaments.

[0018] The absorbable stent of this invention includes a first stent and a second stent. By setting the first stent to be made of woven metal wire, on the one hand, the absorbable stent is fully visible during the pushing and releasing process, which helps to solve the problem that existing stents cannot achieve full visualization; on the other hand, the woven structure can change the mesh size by pushing and pulling, thus providing the operator with more flexible choices and thus providing better wall adhesion; moreover, setting the metal wire to molybdenum can provide sufficient support to the blood vessel in the early stage of treatment, providing good support for coil embolization, and can be uniformly and controllably degraded after treatment, and its degradation products are harmless to the human body.

[0019] Meanwhile, by placing the second stent on the outer peripheral surface of the first stent, the absorbable stent becomes a double-layer structure, effectively increasing the mesh density and enhancing the coverage effect of the absorbable stent. This provides better protection for aneurysm embolization, helps prevent coil herniation, and reduces thrombus and plaque detachment and prolapse. Furthermore, the inclusion of absorbable polymer filaments in the second stent allows for different degradation times compared to the first stent. The degradation of the second stent reduces its overall thickness, thus promoting endothelialization. Additionally, the degradation of the second stent leaves only the inner stent layer, helping to prevent displacement of the first and second stents due to intimal hyperplasia, thereby reducing the likelihood of stent separation.

[0020] Therefore, by arranging the first support and the second support, the absorbable support has good structural performance (support), the support can be visually observed during the pushing and releasing process, and the continuous outward expansion force can be prevented from damaging the vascular intima, thereby possibly inducing inflammation and excessive proliferation of the vascular intima to cause restenosis and other defects, and the use effect of the existing absorbable vascular support can be effectively improved.

[0021] In addition, the absorbable support according to the present application can further have the following additional technical features.

[0022] In some embodiments of the present application, the number of high molecular filaments is multiple, and the multiple absorbable high molecular filaments are interlaced and woven to form the second support, the second support is sleeved on the first support, and the absorbable high molecular filaments at both ends of the second support are respectively connected with the adjacent metal wires.

[0023] In some embodiments of the present application, the weft density of the first support ranges from 60 to 75, and the weft density of the second support ranges from 30 to 40.

[0024] In some embodiments of the present application, the absorbable support further comprises a connecting piece, the connecting piece is arranged in a ring shape along the circumference of the first support, and the connecting piece is used to connect the first support and the second support.

[0025] The number of connecting pieces is multiple, and multiple connecting pieces are arranged at intervals along the axial direction of the first support.

[0026] In some embodiments of the present application, the wire diameter of the metal wire ranges from 0.02 mm to 0.05 mm.

[0027] In some embodiments of the present application, the number of absorbable high molecular filaments is one, and the absorbable high molecular filament is spirally wound on the outer side of the first support and forms the second support.

[0028] In some embodiments of the present application, along the axial direction of the first support, the second support comprises a first section, a second section and a third section arranged in sequence, the pitch of the first section and the third section is equal, and the pitch of the second section is smaller than the pitch of the first section.

[0029] In some embodiments of the present application, the number of absorbable high molecular filaments is multiple, the high molecular filaments are arranged in a wave-shaped ring structure, and multiple wave-shaped ring structures are arranged at intervals along the axial direction of the first support.

[0030] In some embodiments of this utility model, the absorbable support further includes two connectors, which are connected to the first support.

[0031] Along the axial direction of the first bracket, two connectors are respectively disposed at both ends of the first bracket, and a plurality of wave-shaped annular structures are disposed between the two connectors.

[0032] In some embodiments of this utility model, the second stent is provided with an anti-intimal hyperplasia coating, and / or, the second stent is provided with an antithrombotic coating. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 A schematic diagram of the structure of an absorbable stent according to an embodiment of the present invention is shown.

[0035] Figure 2 for Figure 1 A magnified schematic diagram of a portion of the absorbable stent shown;

[0036] Figure 3 for Figure 1 A schematic diagram of the absorbable stent shown from another perspective;

[0037] Figure 4 A schematic diagram of another structure of the absorbable stent according to an embodiment of the present invention is shown.

[0038] Figure 5 A schematic diagram of a third structure of an absorbable stent according to an embodiment of the present invention is shown.

[0039] The markings in the attached diagram are as follows:

[0040] 100. Absorbable stent; 200. Blood vessel;

[0041] 10. First support; 11. First metal wire; 12. Second metal wire;

[0042] 20. Second scaffold; 21. First polymer filament; 22. Second polymer filament; 23. Third polymer filament;

[0043] 201. Section 1; 202. Section 2; 203. Section 3;

[0044] 30. Connector. DETAILED DESCRIPTION

[0045] Example embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. While example embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the present disclosure to those skilled in the art.

[0046] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and the like are to be construed to be inclusive (i.e., to include both instances of open- ended terms and instances of terms limiting to members with which a step can be associated), unless explicitly indicated otherwise. The steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described, unless specifically identified as an order dependent step, process or operation. It is also to be understood that additional or alternative steps can be employed.

[0047] Although the terms first, second, third, and the like can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first", "second", and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0048] For the purposes of this description, spatially relative terms such as "inner", "outer", "beneath", "below", "lower", "above", "upper", and the like can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device is inverted or rotated by 90 degrees, an element described as "below" or "beneath" another element or feature would then be oriented "above" or "over" the other element or feature. Thus, the example term "below" can encompass both an orientation of above and below. The devices can be otherwise oriented (rotated 90 degrees or otherwise) and the spatially relative descriptors used herein interpreted accordingly.

[0049] For the purposes of this description, the terms "proximal" and "distal" are defined as terms commonly used in the field of interventional medicine. Specifically, "distal" refers to the end of the device that is farthest from the operator during a procedure, and "proximal" refers to the end of the device that is closest to the operator during a procedure. "Axial" refers to the lengthwise direction of the device, and "radial" refers to a direction perpendicular to the axial direction.

[0050] Molybdenum (Mo) is an essential element in most living organisms and one of the trace elements required by the human body. The United States Pharmacopoeia allows the oral and parenteral intake of pharmaceutical products to have molybdenum impurity levels of 3 mg / d and 1.5 mg / d, respectively; molybdenum can maintain myocardial energy metabolism, prevent Keshan disease, and maintain arterial elasticity to prevent cardiovascular diseases, etc. Molybdenum has high mechanical strength, its elastic modulus is higher than that of 316L stainless steel and L605 alloy steel, its yield strength is also higher than that of 316L stainless steel, and its density is higher than that of 316L stainless steel and L605 alloy steel, so it is more suitable for making metal stents. Pure molybdenum exhibits uniform degradation behavior in a simulated physiological solution (C-SBF Ca, pH = 7.4) with a corrosion rate of about 10 μm / year, which meets the requirement of degradation rate < 20 μm / year for vascular stents; pure molybdenum has good biocompatibility, and the molybdenum ions generated by the degradation of the pure molybdenum stent do not trigger the apoptosis or necrosis of human endothelial cells or smooth muscle cells, and can be implanted into the blood vessel wall; molybdenum has no magnetism, is suitable for magnetic resonance imaging (MRI), and has great advantages in clinical implants; more and more suggestions are that when the alloy stent wall thickness is less than 100 μm, the degradation mode after endothelialization of the stent is uniform degradation. Molybdenum can meet this cross-sectional requirement while ensuring support force and flexibility.

[0051] As Figures 1-5The utility model provides a kind of absorbable support 100, can be used for conveying system, and release in blood vessel 200, the absorbable support 100 includes first support 10 and second support 20, wherein, first support 10 is tubular structure, first support 10 includes multiple mutually interlaced braided wires, wire includes one or two of molybdenum wire and molybdenum alloy wire.Second support 20 is arranged on the outer circumferential surface of first support 10, and second support 20 includes absorbable high molecular wire, and high molecular wire can be one or two of polylactic acid and polylactic acid analogue.

[0052] Specifically, by setting first support 10 as braided by wire, on the one hand, the absorbable support 100 realizes whole-body visibility during pushing and releasing, which helps to solve the problem that existing stents cannot realize full visualization;On the other hand, the mesh size can be changed by pushing and pulling through the braided structure, so as to provide more flexible selection for the operator, so as to provide better wall adhesion;And the wire is set as molybdenum, which can provide sufficient support to the blood vessel 200 in the early stage of treatment, and provide good support for spring coil embolization, and can be uniformly and controllably degraded after treatment, and the degradation product is harmless to human body.

[0053] Meanwhile, by setting second support 20 on the outer circumferential surface of first support 10, the absorbable support 100 is a double-layer structure, effectively increasing the density of the mesh, strengthening the coverage effect of the absorbable support 100, thereby providing better protection for aneurysm embolization, helping to avoid spring coil herniation, reduce thrombus and plaque shedding and prolapse.And second support 20 includes absorbable high molecular wire, so setting, on the one hand, makes the degradation time of second support 20 different from that of first support 10, and the overall thickness of the stent is reduced after the degradation of second support 20, thereby facilitating the endothelialization process;On the other hand, only the inner stent is left after the degradation of second support 20, which helps to avoid the problem of displacement of first support 10 and second support 20 due to intimal hyperplasia of absorbable support 100, thereby reducing the possibility of separation of absorbable support 100.

[0054] The absorbable support 100 is provided with first support 10 and second support 20, so that the absorbable support 100 has good structural performance (support), realizes whole-body visibility of the stent during pushing and releasing, and also helps to avoid damage to the intima of blood vessel 200 caused by continuous external expansion force, thereby possibly inducing inflammation and excessive proliferation of the intima of blood vessel 200, leading to restenosis and other defects, thereby effectively solving the problem of poor use effect of existing absorbable blood vessel 200 stent.

[0055] It is important to understand that the absorbable stent 100 exists in two states during use: a compressed state and a deployed state. The compressed state refers to the state of the absorbable stent 100 when it is in the delivery system. The deployed state refers to the state of the absorbable stent 100 after it is released from the blood vessel 200 and expands from the compressed state.

[0056] like Figure 1 and Figure 2 As shown, the first support 10 is configured as a tubular structure, comprising multiple metal wires woven together to form the tubular structure. In this embodiment, the multiple metal wires include multiple first metal wires 11 and multiple second metal wires 12. Adjacent first metal wires 11 are arranged in parallel, and adjacent second metal wires 12 are arranged in parallel, with the first metal wires 11 and second metal wires 12 intersecting. Optionally, the cross-section of the metal wires is circular or flat, and the metal wires include one or both of molybdenum wires and molybdenum alloy wires. Using molybdenum as the raw material for the first support 10 allows the absorbable support 100 to be fully radiopaque under X-rays, meaning the absorbable support 100 is fully visible during both pushing (compressed state) and releasing (unfolded state), helping to solve the problem of existing support systems not being fully radiopaque. Moreover, using molybdenum as the matrix of the first stent 10 can reduce the cross-sectional wall thickness while ensuring support. On the other hand, the absorbable stent 100 provides sufficient support to the blood vessel 200 in the early stage of treatment, thereby providing good support for coil embolization. Thirdly, the diseased blood vessel 200 is treated, and after the treatment is completed, the first stent 10 will be gradually absorbed, thereby preventing the occurrence of long-term restenosis and reducing the possibility of thrombus formation in the blood vessel 200.

[0057] It is important to further understand that the wire diameter ranges from 0.02 mm to 0.05 mm. By limiting the wire diameter, the first stent 10 can be woven with extremely fine molybdenum wires, achieving a low cross-sectional thickness while ensuring support. The thin-walled design facilitates rapid intimalization of the first stent 10 after implantation, thereby reducing the risk of postoperative thrombosis and making stent thrombosis prevention more unique and efficient. Moreover, the first stent 10 can be uniformly and controllably degraded after treatment, and its degradation products are harmless to the human body, helping to avoid continuous outward expansion force damaging the intima of the blood vessel 200, which could potentially induce inflammation and excessive proliferation of the intima leading to restenosis and other defects. In this embodiment, the number of wires ranges from 24 to 96, preferably with an optimal number of wires of 36 / 48 / 64, where the number of wires is the quantity of metal wires and the wire diameter is the diameter of the metal wire.

[0058] It should be noted that in the present embodiment, the first stent 10 is woven by a weaving machine and assembled into the absorbable stent 100 by cutting a section to cooperate with the second stent 20. Among them, the first stent 10 can be woven into a closed loop structure first, and then cut according to needs. In this way, the operator can increase the metal coverage of the tumor neck opening by using the lantern technique during use, or achieve better protection effect when the bifurcation part. Among them, the lantern technique is to change the shape of the stent by pushing and squeezing, like a lantern, it can be better fitted to the tumor neck or blood vessel 200, while further reducing the mesh size and increasing the metal coverage of the tumor neck, so as to achieve the purpose of treatment.

[0059] As shown in Figure 1 , Figure 3 , Figure 4 and Figure 5 , the second stent 20 is arranged on the outer circumferential surface of the first stent 10, and the second stent 20 is connected with the first stent 10, wherein the second stent 20 includes one or more absorbable polymer filaments. The absorbable polymer filaments include one or both of polylactic acid and polylactic acid analogs. Preferably, the first stent 10 and the second stent 20 are segmented sutured by polylactic acid filaments, and are fixedly connected by using a molybdenum ring. The arrangement of the second stent 20 makes the absorbable stent 100 have a double-layer structure. At this time, the absorbable stent 100 can have higher mesh density, smaller pore size, and denser grid than single-layer stents without bringing greater chronic external expansion force, which helps to reduce acute plaque prolapse, obtain greater coverage at the tumor neck opening, play a role in guiding blood flow, and be more conducive to the treatment of the tumor and the reconstruction of the tumor-bearing artery. At the same time, the double-layer structure is more conducive to the endothelial cell coverage than the single-layer structure, which is beneficial to the endothelialization process of the absorbable stent 100 (after the absorbable stent 100 is implanted into the blood vessel 200, the rapid coverage of the endothelial cells can stop the intimal reaction proliferation, reduce the risk of restenosis and the possibility of thrombosis).

[0060] Meanwhile, the outer layer (the second stent 20) of the absorbable stent 100 is degraded first during the degradation process, and the second stent 20 can be completely degraded in about half a year. On the one hand, the degradation of the outer layer reduces the overall thickness of the absorbable stent 100 (compared to the single metal absorbable stent 100, the wall thickness is reduced by about 50% after half a year), and the thin wall is beneficial to the process of endothelialization; on the other hand, only the first stent 10 remains after the degradation of the outer layer, thereby avoiding the possibility of displacement of the first stent 10 and the second stent 20 due to intimal hyperplasia, and further causing the separation of the absorbable stent 100. The inner layer (the first stent 10) of the absorbable stent 100 can be completely degraded in about two years. Among them, compared with the degradation process of a single metal (under the same metal coverage or mesh density), the degradation process of the two materials reduces the daily intake of trace elements of metal. The overall absorbable absorbable stent 100 can eliminate the continuous stimulation of the stent to the blood vessel 200 compared with the permanent metal stent, and relieve the restriction of the stent on the diastolic and systolic function of the blood vessel 200, and at the same time, it helps to avoid the risk of metal stent fracture and secondary stenosis.

[0061] Further, the number of absorbable polymer filaments is a plurality, and the plurality of absorbable polymer filaments are interlaced and woven to form the second stent 20, and the second stent 20 is sleeved on the first stent 10, and the polymer filaments at both ends of the second stent 20 are respectively connected with the adjacent metal filaments.

[0062] Specifically, by covering the second stent 20 on the outer side of the first stent 10 through weaving, both the mesh density and the minimum outward force of the stent can be guaranteed. At the same time, the filaments are stitched between the two layers in sections, so that the two layers of stents are tightly combined, avoiding the separation between the layers, thereby reducing the probability of intimal hyperplasia and restenosis. Moreover, the first stent 10 is a metal woven layer, and the second layer is a PLA woven layer, i.e. a polymer woven layer, which has higher mesh density, smaller pore size and denser grid compared with the traditional stent. In this way, plaque prolapse can be reduced, and greater metal coverage can be obtained at the tumor neck, which can guide blood flow and be more beneficial to the treatment of the tumor and the reconstruction of the tumor-bearing artery.

[0063] It needs to be understood that in the present embodiment, the weaving manner of the second stent 20 is the same as that of the first stent 10, and accordingly, the second stent 20 comprises a plurality of absorbable polymer filaments, which comprise a plurality of first polymer filaments 21 and a plurality of second polymer filaments 22. Among them, the first polymer filaments 21 are parallel to the first metal filaments 11, and the second polymer filaments 22 are parallel to the second metal filaments 12. At the same time, the second stent 20 is sleeved on the first stent 10, the inner side surface of the second stent 20 is connected with the outer side surface of the first stent 10, and accordingly, the polymer filaments at both ends of the second stent 20 are connected with the metal filaments at both ends of the adjacent first stent 10 one by one. Covering the second stent 20 with PLA can not only ensure the mesh density, but also reduce the minimum outward force of the stent.

[0064] It needs to be pointed out that the first stent 10 and the second stent 20 are stitched by segmented threading, which can make the stent combination of the first stent 10 and the second stent 20 more compact, and help to avoid the phenomenon of layer separation, thereby reducing the probability of intimal hyperplasia and restenosis. At the same time, it can make the connection with the delivery system reliable and the delivery smooth, and the stent will not slip when adjusting.

[0065] In addition, the first stent 10 and the second stent 20 are both provided in a woven structure, which can change the mesh size by pushing and pulling, thereby providing more flexible selection for the operator, and providing better wall adhesion. Moreover, cooperating with the metal filaments of the first stent 10, the absorbable stent 100 can be visualized after being opened, and can be adjusted and recovered, which is more convenient for the operator to evaluate and control. In addition, the second stent 20 is a woven stent, which is beneficial to the suturing of the end of the second stent 20 and the first stent 10.

[0066] It needs to be further understood that the weft density of the first stent 10 is in the range of 60 to 75, and the weft density of the second stent 20 is in the range of 30 to 40.

[0067] Specifically, by limiting the weft density of the first stent 10 and the second stent 20, the density of the mesh can be effectively increased, thereby strengthening the covering effect of the stent. At the same time, by limiting the weft density of the second stent 20, it is helpful to avoid the influence of the second stent 20 on the bending performance of the absorbable stent 100 due to being too bulky. In addition, since the weft densities of the first stent 10 and the second stent 20 are different, the first stent 10 and the second stent 20 are arranged in a staggered manner, which is beneficial to the coverage of endothelial cells and is beneficial to the endothelialization process of the absorbable stent 100.

[0068] It should be understood that the PPI of the first stent 10 ranges from 60 to 75, wherein the PPI (Pics per Inch) is the weft density, i.e. the number of weft yarns per unit length in the warp direction of the fabric, which can also be referred to as the fabric density. Alternatively, the optimal PPI of the first stent 10 ranges from 58 to 70. Meanwhile, the PPI of the second stent 20 ranges from 30 to 40. Alternatively, the number of the first metal wires 11 and the second metal wires 12 is half of the number of the first polymer wires 21 and the second polymer wires 22, which can increase the mesh density and ensure the bending performance of the absorbable stent 100.

[0069] It should be noted that the first metal wires 11 and the second metal wires 12 (the first polymer wires 21 and the second polymer wires 22) intersect to form a weaving angle, and the greater the weaving angle, the greater the PPI under the same number of weaving strands. Meanwhile, when the weaving angle is the same, the more the number of weaving strands, the greater the PPI.

[0070] Further, the absorbable stent 100 further comprises a plurality of connecting members 30 arranged in a ring shape along the circumference of the first stent 10, and the plurality of connecting members 30 are arranged in an axial direction of the first stent 10, and the connecting members 30 are used to connect the first stent 10 and the second stent 20.

[0071] Specifically, the connecting members 30 can be used to connect the first stent 10 and the second stent 20 together, so that the first stent 10 cannot slide relative to the second stent 20 when the absorbable stent 100 is pushed in the microcatheter, thereby avoiding the unloading and interlayer effect of the absorbable stent 100. By arranging the plurality of connecting members 30 in the axial direction of the first stent 10, the connection effect of the first stent 10 and the second stent 20 can be ensured, and the use effect of the absorbable stent 100 can be further improved.

[0072] It should be understood that when the second stent 20 is sleeved on the outside of the first stent 10, the connecting members 30 are needed for connection and fixation. In the embodiment, the connecting members 30 comprise polylactic acid wires and fasteners, wherein the fasteners are molybdenum tubes or other intermediate connecting materials (such as glue). After the second stent 20 is sleeved on the outside of the first stent 10, the polylactic acid wires are used for segmented suturing, and the molybdenum tubes or other intermediate connecting materials (such as glue) are used for fastening.

[0073] In the embodiment, at the end and the middle section of the absorbable stent 100, each metal wire and each polymer has an included angle, so that the polylactic acid thread stitches the first metal wire 11 and the second polymer thread 22, and the second metal wire 12 and the first polymer thread 21. In addition, the intersection points of the second stent 20 and the intersection points of the first stent 10 are connected one by one, specifically, the polylactic acid thread is used to stitch the intersection points of the first metal wire 11 and the second metal wire 12, and the intersection points of the first polymer thread 21 and the second polymer thread 22. The specific arrangement of the connecting piece 30 can be selected according to the length of the absorbable stent 100. The arrangement of the connecting piece 30 can improve the connection effect of the first stent 10 and the second stent 20, thereby helping to avoid the unloading and interlayer effect of the absorbable stent 100.

[0074] It should be pointed out that the outer side of the two ends of the absorbable stent 100 is stitched back by the polylactic acid thread and fixedly connected with the molybdenum ring and the absorbable stent 100, which helps to solve the problem of incomplete opening or poor opening of the distal end and the proximal end of the absorbable stent 100.

[0075] In actual use, the absorbable stent 100 is implanted in the blood vessel 200 and covers the tumor cavity. During implantation, because the first polymer thread 21 and the second polymer thread 22 at the two ends of the second stent 20 are connected one by one with the first metal wire 11 and the second metal wire 12 of the first stent 10 by the polylactic acid thread, the corresponding first polymer thread 21 and the second polymer thread 22 at the end of the absorbable stent 100 and the first metal wire 11 and the second metal wire 12 are mutually restrained. During the compression and expansion of the absorbable stent 100, even if the first stent 10 and the second stent 20 are affected by external forces to different degrees, they will not spread out, thereby avoiding the poor opening of the distal end and the proximal end of the absorbable stent 100 during release and the bending of the braided wire at the end due to friction with the microcatheter during transportation.

[0076] In addition, during the manufacture of the absorbable stent 100, first, the second stent 20 is sleeved on the outside of the first stent 10 after heat treatment and cleaning, and then the two ends and the middle part of the absorbable stent 100 are stitched by the polylactic acid thread (or fixedly connected by an intermediate connecting material such as glue), so that the first stent 10 and the second stent 20 are tightly connected, and then the assembly is cleaned. The diameter of the second stent 20 is slightly smaller than the diameter of the first stent 10 to increase the tightness of the combination. The slightly smaller means that the diameter of the second stent 20 is 95%-99% of the diameter of the first stent 10. In the embodiment, the diameter of the second stent 20 can be set to 95%, 96%, 97%, 98% or 99% of the diameter of the first stent 10.

[0077] Further, the second stent 20 is provided with an anti-intimal hyperplasia coating, and / or the second stent 20 is provided with an anti-thrombus coating.

[0078] Specifically, by providing the anti-intimal hyperplasia coating and the anti-thrombus coating, the use safety of the absorbable stent 100 is further improved, and complications or other diseases caused by the stent are reduced.

[0079] It should be understood that the second stent 20 is provided with an anti-intimal hyperplasia coating, wherein the anti-intimal hyperplasia coating is not shown in the figure. In the embodiment, the anti-intimal hyperplasia coating is paclitaxel or a composition thereof. After the absorbable stent 100 is implanted, the anti-intimal hyperplasia coating is combined with water molecules, thereby preventing proteins from combining with the metal of the absorbable stent 100 to inhibit intimal hyperplasia and avoid vascular stenosis. In particular, the anti-intimal hyperplasia coating is provided on the outer side of the second stent 20, which can better contact the tissue of the wall of the blood vessel 200 and better play the role of the anti-intimal hyperplasia coating. At the same time, the second stent 10 is provided with an anti-thrombus coating (not shown in the figure), which is optionally heparin or phosphocholine, which helps to prevent thrombosis on the absorbable stent 100. The provision of the anti-intimal hyperplasia coating and the anti-thrombus coating helps to further improve the therapeutic effect of the absorbable stent 100 and improve the life safety of the patient.

[0080] In some other embodiments of the present application, the number of high molecular filaments is one, and the high molecular filament is spirally wound on the outer side of the first stent 10 to form the second stent 20.

[0081] Specifically, by providing one high molecular filament and spirally winding it on the outer side of the first stent 10, the density of the mesh can also be increased, the coverage effect of the absorbable stent 100 is strengthened, and the degradation can also be guaranteed. At the same time, arranging the second stent 20 in a winding manner helps to further improve the connection effect of the second stent 20 and the first stent 10, thereby avoiding the problem of displacement of the first stent 10 and the second stent 20.

[0082] It should be understood that, as shown in Figure 4 for ease of description, the absorbable high molecular filament is referred to as a third high molecular filament 23. In the actual manufacturing process, the first stent 10 needs to be heat treated first, then cut to a certain length and cleaned. The absorbable high molecular filament is made into the second stent 20 in a winding manner on the outside of the first stent 10. Optionally, a plurality of suture points are uniformly distributed along the axial direction of the first stent 10, thereby realizing further close combination of the second stent 20 and the first stent 10.

[0083] At this time, when winding the polylactic acid filaments, the first support 10 can be stretched appropriately, thereby utilizing the outward expansion force of the first support 10 after winding to tightly connect the first support 10 and the second support 20. Optionally, along the axial direction of the first support 10, that is, the radial direction of the spring of the second support 20, several stitching points between the port of the first support 10 and the second support 20 are fixed, which helps to ensure that the absorbable support 100 can be opened smoothly at the port and is not prone to filament breakage.

[0084] It is important to further understand that the pitch can be evenly distributed along the axial direction of the first stent 10, or it can be loosely wound at both ends and tightly wound in the middle section of the first stent 10. In this case, the second stent 20 includes a first section 201, a second section 202, and a third section 203 arranged sequentially. The pitches of the first section 201 and the third section 203 are equal, while the pitch of the second section 202 is smaller than the pitch of the first section 201. This arrangement can provide better support and blood flow guidance at the aneurysm neck.

[0085] In other embodiments of this application, there are multiple polymer filaments, which are configured as wavy ring structures, and the multiple wavy ring structures are spaced apart along the axial direction of the first support 10. In this case, the second support 20 can be fixed to the first support 10 by perforation and sewing through polylactic acid filaments to achieve a double-layer support structure. Of course, this double-layer support can also achieve the above-mentioned effects.

[0086] It should be understood that the waveform ring structure is a waveform structure arranged in a ring around the circumference of the first support 10. The shape of the waveform can be set to a sine wave, half-wave, triangular wave, square wave, sawtooth wave, mixed wave, etc. For example... Figure 5 As shown, in this embodiment, the wave-shaped annular structure adopts a sawtooth wave structure, i.e., a Z-shape. During the manufacturing process, after the first support 10 is heat-treated and cleaned, multiple wave-shaped annular structures are sewn onto the first support 10 using polylactic acid filaments to form the second support 20, thereby realizing the double-layer structure of the absorbable support 100.

[0087] It is necessary to further understand that, along the axial direction of the first support 10, a corrugated annular structure is provided in the middle section of the first support 10, wherein adjacent corrugated annular structures are spaced at a suitable interval of two to three mesh lengths. Simultaneously, two connectors 30 are respectively provided at both ends of the first support 10. In this case, the connector 30 is a single polylactic acid filament. The polylactic acid filament is used to suture the ports of the first support 10, thereby achieving smooth opening and preventing the filaments from folding at the ports of the absorbable support 100.

[0088] It should be noted that the mesh refers to the number of holes per inch of screen. 50 mesh means that there are 50 holes per inch. The length of the mesh refers to the distance between two or three holes of adjacent wave-shaped ring structures. The actual distance can be set according to actual needs, and will not be described in detail here.

[0089] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An absorbable stent, characterized in that, The absorbable stent comprises: a first stent in a tubular structure, the first stent comprising a plurality of metal wires interlaced with each other, the metal wires being one or both of molybdenum wires or molybdenum alloy wires; a second stent arranged on the outer circumferential surface of the first stent, the second stent comprising absorbable polymer wires.

2. The absorbable stent of claim 1, wherein, The number of the absorbable polymer wires is a plurality, and the plurality of absorbable polymer wires are interlaced with each other and form the second stent, the second stent being sleeved on the first stent, and the absorbable polymer wires at both ends of the second stent being respectively connected with adjacent metal wires.

3. The absorbable stent of claim 2, wherein, The weft density of the first stent ranges between 60 and 75, and the weft density of the second stent ranges between 30 and 40.

4. The absorbable stent of claim 2, wherein, The absorbable stent further comprises a connecting piece arranged in a ring shape along the circumference of the first stent, the connecting piece being used to connect the first stent and the second stent. The number of the connecting pieces is a plurality, and the plurality of connecting pieces are arranged at intervals along the axial direction of the first stent.

5. The absorbable stent of claim 1, wherein, The wire diameter of the metal wires ranges between 0.02 mm and 0.05 mm.

6. The absorbable stent of claim 1, wherein, The number of the absorbable polymer wires is one, and the polymer wire is spirally wound on the outer side surface of the first stent and forms the second stent.

7. The absorbable stent of claim 6, wherein, Along the axial direction of the first stent, the second stent comprises a first section, a second section and a third section arranged in sequence, the pitch of the first section and the third section being equal, and the pitch of the second section being smaller than the pitch of the first section.

8. The absorbable stent of claim 1, wherein, The number of the absorbable polymer wires is a plurality, and the absorbable polymer wires are arranged in a wave-shaped ring structure, and the plurality of wave-shaped ring structures are arranged at intervals along the axial direction of the first stent.

9. The absorbable stent of claim 8, wherein, The absorbable stent further comprises two connecting pieces arranged in connection with the first stent. Along the axial direction of the first stent, the two connecting pieces are arranged at both ends of the first stent respectively, and the plurality of wave-shaped ring structures are arranged between the two connecting pieces.

10. The absorbable stent of any one of claims 1-9, wherein, The second stent is provided with an anti-intimal hyperplasia coating, and / or the second stent is provided with an anti-thrombus coating.

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