Medical implant and method for preparing the same

Abstract

The present invention relates to a medical implant and a preparation method thereof. The medical implant is used to block a target cavity and includes a spring coil. The spring coil has a proximal portion that is at least partially biodegradable and a distal portion that is at least partially non-biodegradable. The distal portion is connected to the distal end of the proximal portion, thereby solving the space-occupying effect of the spring coil remaining in the body for a long time and improving the softness of the spring coil, so that the spring coil can better balance compliance and support.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a medical implant for blocking a body cavity and a preparation method thereof. Background Art

[0002] Intracranial aneurysms are mostly abnormal protrusions that occur on the walls of intracranial arteries. They are one of the important causes of subarachnoid hemorrhage and have high mortality and disability rates. In recent years, with the advancement of imaging and materials science, the rapid development of interventional treatment of intracranial aneurysms has been promoted. The most common means of interventional treatment of intracranial aneurysms is to use coils to embolize intracranial aneurysms; on the one hand, it can effectively change the direction of blood flow and reduce the pressure on the aneurysm wall; on the other hand, it can induce thrombosis and promote endothelialization at the neck of the aneurysm, thereby achieving the treatment of intracranial aneurysms. This process has received increasing attention and attention due to its advantages over surgical operations such as less trauma, less risk, and fewer complications.

[0003] At present, the coils used for interventional treatment of intracranial aneurysms are mostly made of metal. However, for large aneurysms, the use of traditional metal coils to embolize aneurysms still has certain limitations: after filling the aneurysm cavity, the coils will exist permanently in the aneurysm cavity, which may produce a space-occupying effect, causing compression on surrounding nerves and tissues, resulting in many adverse effects. On the other hand, after the aneurysm is successfully embolized, in order to ensure good wall adhesion and embolization density, the coils need to have both appropriate support and compliance. This poses a challenge to the configuration of the coils, especially the shape and size of the first loop / first ring (that is, the ring that first enters the aneurysm cavity), as well as the softness and distribution of the entire ring. Summary of the Invention

[0004] In order to solve one or more of the above-mentioned technical problems, the purpose of the present invention is to provide a medical implant and a preparation method thereof, which can partially degrade, effectively alleviate the space-occupying effect of compressing surrounding tissues and nerves caused by permanent retention in the body, and can also ensure good operability.

[0005] To achieve the above objectives, the present invention provides a medical implant for blocking a target cavity, comprising a spring coil having an at least partially biodegradable proximal portion and an at least partially non-biodegradable distal portion, wherein the distal portion is connected to the distal end of the proximal portion.

[0006] Optionally, the spring coil includes a first spring coil and a second spring coil fixedly connected, the first spring coil is made of a biodegradable material, the second spring coil is made of a non-biodegradable material, the second spring coil is at least partially arranged outside the first spring coil, the distal part includes at least a part of the second spring coil, and the proximal part includes the first spring coil.

[0007] Optionally, a portion of the second spring coil is arranged outside the first spring coil, and another portion is arranged inside the first spring coil, so that the second spring coil partially overlaps with the first spring coil in the axial direction; or, the entire second spring coil is arranged outside the first spring coil, so that the second spring coil does not overlap with the first spring coil in the axial direction.

[0008] Optionally, when the second spring coil partially overlaps with the first spring coil in the axial direction, an outer diameter of the portion of the second spring coil disposed outside the first spring coil is greater than or equal to an outer diameter of the other portion of the second spring coil disposed inside the first spring coil.

[0009] Optionally, the outer diameter of the portion of the second spring coil disposed outside the first spring coil is greater than or equal to the outer diameter of the first spring coil, and the outer diameter of the portion of the second spring coil disposed outside the first spring coil does not exceed 1.2 times the outer diameter of the first spring coil; or, the outer diameter of the portion of the second spring coil disposed outside the first spring coil is less than or equal to the outer diameter of the first spring coil, and the outer diameter of the first spring coil does not exceed 2 times the outer diameter of the portion of the second spring coil disposed outside the first spring coil.

[0010] Optionally, when the second spring coil partially overlaps with the first spring coil in the axial direction, the spring coil further includes a third spring coil, and the first spring coil, the second spring coil and the third spring coil are fixedly connected;

[0011] The third spring coil is sleeved on the portion of the second spring coil disposed outside the first spring coil, and a length of the third spring coil is less than or equal to a length of the portion of the second spring coil disposed outside the first spring coil.

[0012] Optionally, the outer diameter of the third spring coil is greater than or equal to the outer diameter of the first spring coil, and the outer diameter of the third spring coil does not exceed 1.2 times the outer diameter of the first spring coil; or, the outer diameter of the third spring coil is less than or equal to the outer diameter of the first spring coil, and the outer diameter of the first spring coil does not exceed 1.2 times the outer diameter of the third spring coil.

[0013] Optionally, at least one of the third spring coil and the second spring coil is configured to be able to be developed under X-ray, and / or the third spring coil is made of a shape memory alloy material.

[0014] Optionally, the first spring coil and the second spring coil are fixed by gluing, and / or the first spring coil and the second spring coil are further fixedly connected by an anti-untwisting structure.

[0015] Optionally, the first spring coil, the second spring coil and the third spring coil are fixed by glue; and / or, the first spring coil, the second spring coil and the third spring coil are further fixedly connected by an anti-untwisting structure.

[0016] Optionally, when the second spring coil partially overlaps with the first spring coil in the axial direction, the outer diameter of the other portion of the second spring coil disposed inside the first spring coil is less than or equal to 0.9 times the inner diameter of the first spring coil; or,

[0017] When the second spring coil and the first spring coil do not completely overlap in the axial direction, the outer diameter of the second spring coil is greater than or equal to the outer diameter of the first spring coil, and the outer diameter of the second spring coil does not exceed 1.2 times the outer diameter of the first spring coil; alternatively, the outer diameter of the second spring coil is less than or equal to the outer diameter of the first spring coil, and the outer diameter of the first spring coil does not exceed 1.2 times the outer diameter of the second spring coil.

[0018] Optionally, the second spring coil is made of a radiopaque material.

[0019] Optionally, the length of the distal portion is 1 cm to 100 cm.

[0020] Optionally, the length of the distal portion is 1 cm to 20 cm.

[0021] Optionally, the distal portion is further configured to be able to be visualized under X-rays, and / or the proximal portion is configured to be able to be visualized under X-rays.

[0022] Optionally, the proximal portion is made of a biodegradable material, or the proximal portion consists of a biodegradable outer layer and a non-biodegradable inner layer, the outer layer being arranged around the inner layer.

[0023] Optionally, the distal portion is made of a non-biodegradable material, or the distal portion consists of a non-biodegradable outer layer and a non-biodegradable inner layer, the outer layer being arranged around the inner layer.

[0024] Optionally, the distal portion in a free state has an annular or arcuate shape.

[0025] To achieve the above object, the present invention further provides a method for preparing a medical implant, the method comprising:

[0026] providing a spring coil;

[0027] The proximal portion of the spring coil is made of at least partially biodegradable material, and the distal portion of the spring coil is made of at least partially non-biodegradable material, wherein the distal portion is connected to the distal end of the proximal portion.

[0028] Optionally, the proximal portion is formed using a biodegradable first spring coil, and at least a portion of a non-biodegradable second spring coil is disposed outside the first spring coil to form the distal portion.

[0029] Optionally, the second spring coil partially overlaps with the first spring coil in the axial direction, or the second spring coil does not overlap with the first spring coil in the axial direction at all.

[0030] Optionally, when the second spring coil partially overlaps with the first spring coil in the axial direction, a non-biodegradable third spring coil is further sleeved on the second spring coil, and the third spring coil is located outside the first spring coil.

[0031] Optionally, the distal portion is made to be able to be visualized under X-rays, and / or the proximal portion is made to be able to be visualized under X-rays.

[0032] In the above-mentioned medical implant and preparation method thereof, since the proximal portion of the spring coil is at least partially biodegradable, the space-occupying effect of the spring coil, which compresses surrounding tissues and nerves, caused by its permanent retention in the body, is resolved. Furthermore, the softness of the spring coil is improved, making it more compliant and enabling it to better fill target cavities such as aneurysms, forming a denser filling. Furthermore, both support and compliance are taken into account, and the problem of the spring coil protruding into the aneurysm during the filling process is effectively resolved.

[0033] In the above-mentioned medical implant and preparation method thereof, the proximal and distal portions of the spring coil can be made using a first spring coil and a second spring coil that are formed separately, and a portion of the second spring coil can be arranged inside the first spring coil, which can improve the molding effect of the entire spring coil, making the molding more stable and the sealing effect better.

[0034] In the above-mentioned medical implant and preparation method thereof, when the second spring coil partially overlaps with the first spring coil in the axial direction, it is preferred to sleeve the third spring coil outside the second spring coil, or to configure the outer diameter of the portion of the second spring coil located outside the first spring coil to be larger. This can enhance the molding effect of the distal portion, thereby improving the molding performance of the entire spring coil, making the spring coil molding more stable and achieving a better sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The features, properties and advantages of the implementation method of the present invention and related embodiments will be described with reference to the following drawings, in which:

[0036] Figure 1 This is a schematic structural diagram of a medical implant provided according to a preferred embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic axial cross-sectional view of a medical implant provided according to a preferred embodiment 1 of the present invention;

[0038] Figure 3 and Figure 4 This is a schematic structural diagram of a medical implant provided according to a second preferred embodiment of the present invention;

[0039] Figure 5 This is a schematic axial cross-sectional view of a medical implant provided according to a third preferred embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0041] As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. As used in this specification, the term "or" is generally used in a manner that includes "and / or," unless the context clearly indicates otherwise. As used in this specification, the term "distal" generally refers to the end of a medical implant that first enters the body; "proximal," in contrast to "distal," refers to the end of the medical implant that is closest to the operator during operation. As used in this specification, the term "axial" generally refers to a direction parallel to the axis of the medical implant. As used in this specification, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature specified as "first," "second," etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0042] The present invention provides a medical implant and a method for its preparation. The medical implant can be used to embolize aneurysms, not limited to intracranial aneurysms, but also, for example, peripheral aneurysms. The medical implant can also be used for embolization of other sites, for example, to treat various vascular diseases, such as arteriovenous malformations and arteriovenous fistulas, and to treat certain tumors by embolizing the intervascular space or other soft tissue spaces. The medical implant can also be used to occlude fallopian tubes for sterilization and occlusive repair of cardiac defects, such as patent foramen ovale, patent vascular closure, and atrial septal defect. In these cases, the medical implant functions to substantially prevent blood from flowing into or through a cavity, lumen, vessel, or defect to achieve the therapeutic objective. Compared to the prior art, the medical implant provided by the present invention is partially degradable, reducing the space-occupying effect of the coil. Furthermore, the coil of the present invention exhibits improved flexibility, balancing support and compliance. Upon implantation, it can conform to the shape of the cavity to densely pack the cavity. Furthermore, it exhibits good tissue compatibility, promoting the growth of the vascular endothelium. It should be understood that the terms "biodegradable," "degradable," and "bioabsorbable" as used herein refer to materials that are capable of breaking down into harmless small molecules over a period of days, weeks, months, or even years. It should be understood that the term "not exceeding" as used herein refers to "less than or equal to."

[0043] The medical implant and the preparation method thereof of the present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0044] <Example 1>

[0045] Figure 1 and Figure 2 A medical implant 10 provided in accordance with a first preferred embodiment of the present invention is shown.

[0046] Please refer to Figure 1 This embodiment provides a medical implant 10 comprising a spring coil having a proximal portion 101 and a distal portion 102, the distal portion 102 being connected to the distal end of the proximal portion 101. The proximal portion 101 is configured to be at least partially biodegradable, while the distal portion 102 is configured to be at least partially non-biodegradable. The distal portion 102 first enters the target cavity to fill the cavity, while the proximal portion 101 continues to fill the target cavity under the guidance of the distal portion 102. After a certain period of time, at least a portion of the proximal portion 101 automatically degrades, conforming to the natural course of spring coil embolization for conditions such as aneurysms. This degradation also reduces the mass effect associated with existing non-degradable spring coils, resulting in improved safety. Preferably, the entire proximal portion 101 is biodegradable. Preferably, the entire distal portion 102 is non-biodegradable.

[0047] In this embodiment, the spring coil is preferably constructed from two separately formed spring coils. Specifically, the spring coil includes a first spring coil 11 and a second spring coil 12 that are fixedly connected. The first spring coil 11 is made of a biodegradable material. The first spring coil 11 is at least partially biodegradable, and preferably all of the first spring coil 11 is biodegradable. The second spring coil 12 is made of a non-biodegradable material. The distal portion 102 includes a portion of the second spring coil 12, and the proximal portion 101 includes the first spring coil 11.

[0048] refer to Figure 2 , and combined with Figure 1 The second spring coil 12 is partially disposed outside the first spring coil 11, that is, a portion of the second spring coil 12 is disposed outside the distal end of the first spring coil 11, and another portion of the second spring coil 12 is disposed inside the first spring coil 11, so that the second spring coil 12 and the first spring coil 11 partially overlap in the axial direction. The advantage of partially overlapping the two spring coils in the axial direction at the proximal end is that the entire spring coil is better formed, which can better pack the aneurysm and other sites, and achieve a better sealing effect.

[0049] The first spring coil 11 can usually be completely degraded within 0.5 to 5 years (in vitro). The present application does not impose any particular restrictions on the material used to prepare the first spring coil 11. The material of the first spring coil 11 can be, for example, a synthetic polymer material, such as at least one of polycaprolactone, polyglycolide, polylactide, glycolipid copolymer, polydioxanone, polyurethane, polypeptide and hyaluronic acid. The material of the first spring coil 11 can also be, for example, a natural macromolecular material, such as at least one of chitosan and cellulose. The material of the first spring coil 11 can also be a degradable metal material, such as iron and its alloys, zinc and its alloys, magnesium and its alloys, etc. More preferably, the material of the first spring coil 11 is glycolipid copolymer, or magnesium and its alloys.

[0050] The second spring coil 12 is made of a non-degradable material, such as a non-degradable metal or polymer. More preferably, the second spring coil 12 is made of a radiopaque material, making it developable under X-rays. In embodiments of the present invention, the material of the second spring coil 12 includes a radiopaque material, which is not particularly limited. Examples include platinum and its alloys, gold and its alloys, tungsten and its alloys, and the like. The second spring coil 12 can also be made of a non-degradable polymer, such as at least one of polypropylene, polyethylene, and ethylene-propylene copolymer. More preferably, a radiopaque material is added to the polymer. It should be understood that making the second spring coil 12 developable is not limited to integrally forming the second spring coil 12 by mixing materials. Other suitable preparation methods can also be used to achieve developability. For example, a non-degradable polymer can be impregnated with a radiopaque material to form a radiopaque coating. Furthermore, the second spring coil 12 can be made of a shape memory alloy, which provides excellent elasticity and allows for better shape recovery. More preferably, the second spring coil 12 is made of a DFT material. DFT material is a composite metal material with developability and good elasticity. It can include an inner layer structure and an outer layer structure. The materials of the inner layer structure and the outer layer structure are different, and the two can be extruded into one piece.

[0051] In this embodiment, in a relaxed state (i.e., in a free state, not constrained by any external force), the distal portion 102 of the spring coil generally has a two-dimensional (2D) or three-dimensional (3D) configuration. The present application does not impose any specific restrictions on the shape of the distal portion 102 of the spring coil, as long as the distal portion 102 can be rotationally molded in the target cavity. Optionally, in a relaxed state, the distal portion 102 can be a 2D configuration such as a spiral, an 8-shaped, an S-shaped, or a five-ring (i.e., comprising a plurality of circular rings connected in sequence). Alternatively, in a relaxed state, the distal portion 102 can also be a 3D configuration such as a tetrahedron, a pentahedron, a hexahedron, or an octahedron. Generally, the farthest end of the distal portion 102 can be constructed as a ring or an arc, preferably a ring or an arc. The arc is preferably an arc of not less than 1 / 2. The distal portion 102 preferably forms a ring or arc shape of about 1.5 turns, and more preferably forms a ring or arc shape of 1 to 2 turns, which is conducive to the forming embolization of the spring coil in the tumor and is not easy to protrude from the tumor. The optional length of the distal portion 102 is 1 cm to 20 cm to form a ring shape of 1 turn.

[0052] In actual use, the medical implant 10 has a compressed state and an expanded state. When in the expanded state, the medical implant 10 has a predetermined shape, such as a spiral or polyhedron, wound from the distal end to the proximal end. When in the compressed state, the medical implant 10 can be conveniently delivered from within a blood vessel to a target cavity (such as an aneurysm) via a sheath. In the compressed state, the medical implant 10 can be compressed into a linear shape. When the medical implant 10 is released from the sheath, it can return to its original shape. The distal portion 102 first enters the target cavity, such as an aneurysm, and is rotated to form, thereby guiding the first spring coil 11 to rotate along the second spring coil 12 to achieve occlusion of the target cavity. Furthermore, a portion of the second spring coil 12 is disposed within the first spring coil 11, which improves the coil forming effect and makes the forming more stable. Furthermore, disposing a portion of the second spring coil 12 within the first spring coil 11 also allows the proximal portion 101 of the spring coil to be visualized under X-rays, facilitating the location of the proximal portion 101. In addition, it should be understood that while the first spring coil 11 is used to solve the space-occupying effect, the softness of the spring coil is also improved, making the spring coil more compliant, taking into account both support and compliance, and being able to better fill cavities such as aneurysms, forming a denser filling, with good operability and not easily penetrating into the tumor-bearing artery.

[0053] The first spring coil 11 and the second spring coil 12 are both formed by spirally winding a wire, and there may be a gap or almost no gap between adjacent spirals of each coil. The first spring coil 11 and the second spring coil 12 may have the same or different pitches.

[0054] The length of the second spring coil 12 is preferably greater than that of the first spring coil 11. Optionally, the difference between the lengths of the second spring coil 12 and the first spring coil 11 is 1 cm to 100 cm. Preferably, the excess length of the second spring coil 12 over the first spring coil 11 is disposed at the distal end of the entire medical implant 10 to form the distal portion 102. In a preferred embodiment, the difference between the lengths of the second spring coil 12 and the first spring coil 11 is 1 cm to 20 cm. This length difference forms a ring, facilitating better positioning and shaping, and preventing protrusion into the parent vessel.

[0055] The present application does not impose any restrictions on the outer diameter and inner diameter of the first spring coil 11 and the second spring coil 12. Generally, they can be set according to the diameter of the blood vessel to be implanted. Optionally, the outer diameter of the first spring coil 11 is 0.005 inches to 0.02 inches, and the outer diameter of the second spring coil 12 is 0.004 inches to 0.016 inches. The present application does not impose any restrictions on the cross-sectional shape of the first wire material used to wind the first spring coil 11. Generally, the cross-sectional shape of the first wire material is circular, and the diameter of the first wire material can be 0.001 inches to 0.006 inches. The cross-sectional shape of the second wire material used to wind the second spring coil 12 is also not limited. Preferably, the cross-sectional shape of the second wire material is circular, and the diameter of the second wire material can be 0.0005 inches to 0.003 inches.

[0056] In this embodiment, the first spring coil 11 and the second spring coil 12 have overlapping portions in the axial direction, that is, the second spring coil 12 is partially arranged in the inner cavity of the first spring coil 11, so that the molding effect of the entire spring coil is good, and the outer diameter of the portion of the second spring coil 12 located in the first spring coil 11 is preferably less than or equal to 0.9 times the inner diameter of the first spring coil 11, so that the two achieve a better matching effect and a better molding effect.

[0057] In some embodiments, the second spring coils 12 have the same outer diameter, that is, the outer diameter of the portion of the second spring coil 12 located outside the first spring coil 11 is the same as the outer diameter of the portion of the second spring coil 12 located inside the first spring coil 11. In other embodiments, the second spring coils 12 have different outer diameters, that is, the outer diameter of the portion of the second spring coil 12 located outside the first spring coil 11 is different from the outer diameter of the portion of the second spring coil 12 located inside the first spring coil 11. Typically, the outer diameter of the portion of the second spring coil 12 located outside the first spring coil 11 is larger than the outer diameter of the portion of the second spring coil 12 located inside the first spring coil 11, thereby increasing the outer diameter of the distal portion 102 to improve the spring coil forming effect. Furthermore, the outer diameter of the portion of the second spring coil 12 disposed outside the first spring coil 11 is greater than or equal to the outer diameter of the first spring coil 11. Preferably, the outer diameter of the portion of the second spring coil 12 disposed outside the first spring coil 11 does not exceed 1.2 times the outer diameter of the first spring coil 11. Alternatively, the outer diameter of the portion of the second spring coil 12 disposed outside the first spring coil 11 is less than or equal to the outer diameter of the first spring coil 11, and the outer diameter of the first spring coil 11 does not exceed 2 times the outer diameter of the portion of the second spring coil 12 disposed outside the first spring coil 11.

[0058] Please refer to Figure 2 The first spring coil 11 and the second spring coil 12 are preferably bonded and fixed by glue 13, such as light-curing glue, to simplify the process, reduce the difficulty of connection, and achieve a stable connection. In actual operation, glue 13 can be injected into the distal end of the first spring coil 11 and cured under ultraviolet light. The material of glue 13 can be a degradable material or a non-degradable material. Of course, in other embodiments, the first spring coil 11 and the second spring coil 12 can also be bonded and fixed without glue 13.

[0059] In a preferred embodiment of the present invention, the first spring coil 11 and the second spring coil 12 are further fixedly connected by an anti-untwisting structure 14. The anti-untwisting structure 14 can be in the form of a wire, hose, coil, or other structure. One end of the anti-untwisting structure 14 is fixedly connected to the first spring coil 11, and the other end is fixedly connected to the second spring coil 12. In this embodiment, the anti-untwisting structure 14 has a head 15, which is fixedly connected to the distal end of the second spring coil 12, such as by welding or gluing. The body of the anti-untwisting structure 14 is connected to the head 15 and then inserted into the second spring coil 12. The body of the anti-untwisting structure 14 then extends further out of the second spring coil 12 and is fixedly connected to the first spring coil 11, such as by wrapping and fixing it with a knot. The head 15 is positioned and fixed at the distal end of the second spring coil 12 and preferably has a smooth surface, such as a circular arc surface, to form an atraumatic head. The anti-untwisting structure 14 can also be wrapped and fixedly connected to the first spring coil 11 at the distal end of the first spring coil 11 by wrapping and fixing it with a knot, for example. It should be understood that the anti-untwisting structure 14 can prevent the spring coil from being straightened under external forces, achieving an anti-untwisting effect, and enhancing the reliability and stability of the connection between the spring coils. The material of the anti-untwisting structure 14 can be a non-degradable polymer material, such as polypropylene, polyethylene, etc., or a degradable polymer material. The material of the anti-untwisting structure 14 can be the same as or different from the material of the first spring coil 11. Therefore, the anti-untwisting structure 14 can further strengthen the connection strength between the first spring coil 11 and the second spring coil 12, making the connection between the two more stable.

[0060] <Example 2>

[0061] Figure 3 and Figure 4 A medical implant 20 provided in a second preferred embodiment of the present invention is shown.

[0062] Please refer to Figure 3 and Figure 4 This embodiment provides a medical implant 20 comprising a spring coil having a proximal portion 201 and a distal portion 202, the distal portion 202 being connected to the distal end of the proximal portion 201. The proximal portion 201 is configured to be at least partially biodegradable, while the distal portion 202 is configured to be at least partially non-biodegradable. The distal portion 202 first enters the target cavity to fill the cavity, while the proximal portion 201 continues to fill the target cavity under the guidance of the distal portion 202. The proximal portion 201 automatically degrades after a certain period of time, conforming to the natural course of spring coil embolization for conditions such as aneurysms. This degradation also reduces the mass effect associated with existing non-degradable spring coils, resulting in improved safety. Preferably, the entire proximal portion 201 is biodegradable. Preferably, the entire distal portion 202 is non-biodegradable.

[0063] In this embodiment, the spring coil is preferably constructed of two spring coils that are separately formed. Specifically, the spring coil includes a first spring coil 21 and a second spring coil 22 that are fixedly connected. The first spring coil 21 is made of a biodegradable material. The first spring coil 21 is at least partially biodegradable. Preferably, the entire first spring coil 21 is biodegradable, and the second spring coil 22 is made of a non-biodegradable material. The distal portion 202 includes the entire second spring coil 12, and the proximal portion 201 includes the first spring coil 21, that is, the entire second spring coil 22 is arranged outside the first spring coil 21, that is, the entire second spring coil 12 is arranged outside the distal end of the first spring coil 11, so that the second spring coil 22 and the first spring coil 21 do not overlap at all in the axial direction.

[0064] The first spring coil 21 can usually be completely degraded within 0.5 to 5 years (in vitro). The present application does not impose any particular restrictions on the material used to prepare the first spring coil 21. The material of the first spring coil 21 can be, for example, a synthetic polymer material, such as at least one of polycaprolactone, polyglycolide, polylactide, glycolipid copolymer, polydioxanone, polyurethane, polypeptide and hyaluronic acid. The material of the first spring coil 11 can also be, for example, a natural macromolecular material, such as at least one of chitosan and cellulose. The material of the first spring coil 21 can also be a degradable metal material, such as iron and its alloys, zinc and its alloys, magnesium and its alloys, etc. More preferably, the material of the first spring coil 21 is glycolipid copolymer, or magnesium and its alloys.

[0065] The second spring coil 22 is made of a non-degradable material, such as a non-degradable metal or polymer. More preferably, the second spring coil 22 is made of a radiopaque material, making it developable under X-rays. In embodiments of the present invention, the material of the second spring coil 22 includes a radiopaque material, which is not particularly limited and may include, for example, platinum and its alloys, gold and its alloys, tungsten and its alloys, etc. The second spring coil 22 may also be made of a non-degradable polymer material, such as at least one of polypropylene, polyethylene, and ethylene-propylene copolymer, more preferably, a radiopaque material is added to the polymer material. It should be understood that making the second spring coil 22 developable is not limited to integrally forming the second spring coil 22 by mixing materials; other suitable preparation methods may also be used to achieve developability. For example, a non-degradable polymer material may be impregnated with a radiopaque material to form a radiopaque coating. Furthermore, the second spring coil 22 may be made of a shape memory alloy material, which provides excellent elasticity and allows for better shape recovery. More preferably, the second spring coil 22 is made of a DFT material.

[0066] Similarly, in this embodiment, in a relaxed state (i.e., in a free state, not constrained by any external force), the distal portion 202 generally has a two-dimensional (2D) or three-dimensional (3D) configuration. The present application does not impose any specific restrictions on the shape of the distal portion 202 of the spring coil, as long as the distal portion 202 can be rotationally molded in the target cavity. Optionally, in a relaxed state, the distal portion 202 can be a 2D configuration such as a spiral, an 8-shaped, an S-shaped, or a five-ring. Alternatively, in a relaxed state, the distal portion 202 can also be a 3D configuration such as a tetrahedron, a pentahedron, a hexahedron, or an octahedron. Generally, the farthest end of the distal portion 202 can be constructed as a ring or an arc, preferably a ring or an arc, wherein the arc is preferably an arc of not less than 1 / 2. The distal portion 202 preferably forms a ring or arc shape of about 1.5 turns, and more preferably forms a ring or arc shape of 1 to 2 turns, which is conducive to the forming embolization of the spring coil in the tumor and is not easy to protrude from the tumor. The optional length of the distal portion 202 is 1 cm to 20 cm to form a ring shape of 1 turn.

[0067] In actual use, the medical implant 20 has a compressed state and an expanded state. When the medical implant 20 is in the expanded state, the medical implant 20 has a predetermined shape, such as a spiral or a polyhedron, wound from the distal end to the proximal end. When the medical implant 20 is in the compressed state, it is convenient for delivery of the medical implant 20 from the blood vessel to the target cavity (such as an aneurysm) through the sheath. In the compressed state, the medical implant 20 can be compressed into a linear shape. When the medical implant 20 is released from the sheath, it can return to its original shape. The second spring coil 22 first enters the target cavity such as the aneurysm and rotates to form, thereby guiding the first spring coil 21 to rotate along the second spring coil 22 to achieve occlusion of the target cavity. It should also be understood that while the first spring coil 21 is used to address the space-occupying effect, it also improves the softness of the spring coil, making it more compliant, balancing support and compliance. This allows for better filling of cavities such as aneurysms, forming a denser packing, improving operability, and preventing it from protruding into the parent artery.

[0068] The first spring coil 21 and the second spring coil 22 are both helically wound from a wire material. Adjacent coils of each coil may have spacing or virtually no spacing. The first and second spring coils 21, 22 may have the same or different pitches. Preferably, the length of the second spring coil 22 is 1 cm to 100 cm, more preferably 1 cm to 20 cm, to facilitate better positioning and shaping, and to prevent it from protruding into the tumor-bearing vessel.

[0069] The present application does not impose any restrictions on the outer diameter and inner diameter of the first spring coil 21 and the second spring coil 22, and is generally set according to the diameter of the blood vessel to be implanted. The first spring coil 21 and the second spring coil 22 can have the same outer diameter or different outer diameters. The first spring coil 21 and the second spring coil 22 can also have the same inner diameter or different inner diameters. Optionally, the outer diameter of the second spring coil 22 is greater than or equal to the outer diameter of the first spring coil 21, preferably the outer diameter of the second spring coil 22 does not exceed 1.2 times the outer diameter of the first spring coil 21, or the outer diameter of the second spring coil 22 is less than or equal to the outer diameter of the first spring coil 21, and the outer diameter of the first spring coil 21 does not exceed 1.2 times the outer diameter of the second spring coil 22.

[0070] Optionally, the outer diameter of the first spring coil 21 and / or the outer diameter of the second spring coil 22 is 0.005 inch to 0.02 inch. The present application does not limit the cross-sectional shape of the first wire material used to wind the first spring coil 21. Generally, the cross-sectional shape of the first wire material is circular, and the diameter of the first wire material can be 0.001 inch to 0.006 inch. The cross-sectional shape of the second wire material used to wind the second spring coil 22 is also not limited. Preferably, the cross-sectional shape of the second wire material is circular, and the diameter of the second wire material can be 0.001 inch to 0.006.

[0071] The second spring coil 22 and the first spring coil 21 are preferably bonded together using glue 23, such as light-curing glue, to simplify the process, reduce the difficulty of connection, and achieve a stable connection. For example, the distal end of the first spring coil 21 and the proximal end of the second spring coil 22 are bonded together using light-curing glue, which is cured under ultraviolet light. The glue 23 can be made of a degradable material or a non-degradable material. Of course, in other embodiments, the first spring coil 21 and the second spring coil 22 can also be bonded together without glue 23.

[0072] In a preferred embodiment of the present invention, the first spring coil 21 and the second spring coil 22 can also be fixedly connected by an anti-unwinding structure 24. The anti-unwinding structure 24 is mainly in the form of a wire, a hose, a coil, etc. The anti-unwinding structure 24 is arranged inside the first spring coil 21 and the second spring coil 22. One end of the anti-unwinding structure 24 is fixedly connected to the first spring coil 21, such as being wound and fixed. The number of windings can be one circle, such as Figure 3 As shown, it can also be multiple circles, such as Figure 4 As shown, multiple turns include but are not limited to 2 turns. In addition, the other end of the anti-unwinding structure 24 is fixedly connected to the second spring coil 22, such as being wound and fixed, and the number of turns of the winding can be one turn, such as Figure 3 As shown, it can also be multiple circles, such as Figure 4As shown. The anti-untwisting structure 24 can prevent the spring coil from being straightened under the action of external force, thereby achieving the anti-untwisting effect and enhancing the reliability and stability of the connection between the spring coils. The material of the anti-untwisting structure 24 can be a non-degradable polymer material, such as polypropylene, polyethylene, etc., or a degradable polymer material. The material of the anti-untwisting structure 24 can be the same as or different from the material of the first spring coil 21. Therefore, the connection strength between the first spring coil 21 and the second spring coil 22 can be further strengthened by the anti-untwisting structure 24, making the connection between the two more stable. Furthermore, the diameter or outer diameter of the anti-untwisting structure 24 does not exceed 0.9 times the minimum inner diameter of the first spring coil 21 and the second spring coil 22.

[0073] <Example 3>

[0074] Figure 5 A medical implant 30 provided in a third preferred embodiment of the present invention is shown.

[0075] Please refer to Figure 5 This embodiment provides a medical implant 30 comprising a spring coil having a proximal portion 301 and a distal portion 302, the distal portion 302 being connected to the distal end of the proximal portion 301. The proximal portion 301 is configured to be at least partially biodegradable, while the distal portion 302 is configured to be at least partially non-biodegradable. The distal portion 302 first enters the target cavity to fill the cavity, while the proximal portion 301 continues to fill the target cavity under the guidance of the distal portion 302. The proximal portion 301 automatically degrades after a certain period of time, conforming to the natural course of spring coil embolization for conditions such as aneurysms. This degradation reduces the mass effect associated with existing non-degradable spring coils, resulting in improved safety. Preferably, the entire proximal portion 301 is biodegradable. Preferably, the entire distal portion 302 is non-biodegradable.

[0076] In this embodiment, the spring coil is preferably constructed of three spring coils that are separately formed. Specifically, the spring coil includes a first spring coil 31, a second spring coil 32, and a third spring coil 33 that are fixedly connected to each other. The first spring coil 31 is made of a biodegradable material. The first spring coil 31 is at least partially biodegradable. Preferably, the entire first spring coil 31 is biodegradable, and the second spring coil 32 and the third spring coil 33 are both made of non-biodegradable materials. The distal portion 302 includes a portion of the second spring coil 32 and the third spring coil 33, and the proximal portion 301 includes the first spring coil 31. As in Example 1, a portion of the second spring coil 32 is arranged outside the first spring coil 31, and another portion of the second spring coil 32 is arranged inside the first spring coil 31, so that the second spring coil 32 and the first spring coil 31 partially overlap in the axial direction.

[0077] The third spring coil 33 is sleeved over the portion of the second spring coil 32 disposed outside the first spring coil 31, and the third spring coil 33 is provided along at least a portion of the length of the portion of the second spring coil 32 disposed outside the first spring coil 31. That is, the length of the third spring coil 33 is less than or equal to the length of the portion of the second spring coil 32 disposed outside the first spring coil 31. The third spring coil 33 can enhance the molding effect of the entire medical implant. Preferably, the entire portion of the second spring coil 32 disposed outside the first spring coil 31 is enclosed by the third spring coil 33, resulting in a better molding effect. It should be understood that when the first and second spring coils 31 and 32 overlap axially, the outer diameters of the second spring coils 32 are typically designed to be the same to reduce processing difficulty. In this case, the outer diameter of the portion of the second spring coil 32 disposed outside the first spring coil 31 is smaller. Therefore, by providing the third spring coil 33 on the portion of the second spring coil 32 disposed outside the first spring coil 31, processing difficulty can be reduced while ensuring the molding effect of the spring coil.

[0078] The first spring coil 31 can generally be completely degraded (in vitro) within 0.5 to 5 years. The present application does not impose any particular restrictions on the material used to prepare the first spring coil 31. The material of the first spring coil 31 can be, for example, a synthetic polymer material, such as at least one of polycaprolactone, polyglycolide, polylactide, glycolipid copolymer, polydioxanone, polyurethane, polypeptide, and hyaluronic acid. The material of the first spring coil 31 can also be, for example, a natural macromolecular material, such as at least one of chitosan and cellulose. The material of the first spring coil 31 can also be a degradable metal material, such as iron and its alloys, zinc and its alloys, magnesium and its alloys, etc. More preferably, the material of the first spring coil 31 is glycolipid copolymer, or magnesium and its alloys.

[0079] The second spring coil 32 is made of a non-degradable material, such as a non-degradable metal or polymer. More preferably, it is made of a radiopaque material, making it developable under X-rays. In embodiments of the present invention, the material of the second spring coil 32 includes a radiopaque material, which is not particularly limited. Examples include platinum and its alloys, gold and its alloys, tungsten and its alloys, and the like. The second spring coil 32 can also be made of a non-degradable polymer, such as at least one of polypropylene, polyethylene, and ethylene-propylene copolymer. More preferably, a radiopaque material is added to the polymer. It should be understood that making the second spring coil 32 developable is not limited to integrally forming the second spring coil 32 by mixing materials. Other suitable methods can also be used to achieve developability, such as impregnating a non-degradable polymer with a radiopaque material to form a radiopaque coating. Furthermore, the second spring coil 32 can be made of a shape memory alloy, which provides excellent elasticity and allows for better shape recovery. More preferably, the second spring coil 32 is made of a DFT material.

[0080] In this embodiment, in a relaxed state (i.e., in a free state, not constrained by any external force), the distal portion 302 of the spring coil also has a two-dimensional (2D) or three-dimensional (3D) configuration. The present application does not impose any specific restrictions on the shape of the distal portion 302, as long as the distal portion 302 can be rotationally molded in the target cavity. Optionally, in a relaxed state, the distal portion 302 can be a 2D configuration such as a spiral, an 8-shaped, an S-shaped or a five-ring. Alternatively, in a relaxed state, the distal portion 302 can also be a 3D configuration such as a tetrahedron, a pentahedron, a hexahedron or an octahedron. Generally, the farthest end of the distal portion 302 is constructed as a ring or an arc, preferably a circular ring or a circular arc, wherein the circular arc is preferably an arc of not less than 1 / 2. The distal portion 302 preferably forms a ring or arc of about 1.5 turns, and more preferably forms a ring or arc of 1 to 2 turns, which is conducive to the forming embolization of the spring coil in the tumor and is not easy to protrude from the tumor. The optional length of the distal portion 302 is 1 cm to 20 cm to form a ring of 1 turn.

[0081] The material of the third spring coil 33 may be the same as or different from that of the second spring coil 32. The material of the third spring coil 33 preferably has a good shape memory effect, such as nickel-titanium alloy. The metal wire of this alloy is very soft and has excellent "elastic memory" ability, so it can be made into the desired shape and will return to its original shape after deformation. It should be noted that at least one of the third spring coil 33 and the second spring coil 32 can be developed under X-rays. The length of the third spring coil 33 can be 1 cm to 100 cm. Preferably, the length of the third spring coil 33 is 1 cm to 20 cm. The length of the portion of the second spring coil 32 arranged outside the first spring coil 31 is equal to the length of the third spring coil 33, or greater than the length of the third spring coil 33.

[0082] In actual use, the medical implant 30 has a compressed state and an expanded state. When the medical implant 30 is in the expanded state, the medical implant 30 has a predetermined shape, such as a spiral or a polyhedron, wound from the distal end to the proximal end. When the medical implant 30 is in the compressed state, it is convenient for delivery of the medical implant 30 from the blood vessel to the target cavity (such as a hemangioma) through the sheath. In the compressed state, the medical implant 30 can be compressed into a linear shape. When the medical implant 30 is released from the sheath, it can return to its original shape. The distal portion 302 first enters the target cavity such as the aneurysm and rotates to form, thereby guiding the first spring coil 31 to rotate along the second spring coil 32 and the third spring coil 33 to achieve occlusion of the target cavity. In addition, a portion of the second spring coil 32 is disposed inside the first spring coil 31, and the third spring coil 33 is sheathed outside the second spring coil 32, resulting in a better and more stable spring coil forming effect. Furthermore, placing a portion of the second spring coil 32 within the first spring coil 31 allows the proximal end portion 301 of the spring coil to be visualized under X-rays, facilitating the location of the proximal end portion 301. It should also be understood that while utilizing the first spring coil 31 to address the space-occupying effect, it also improves the coil's flexibility, resulting in greater compliance. This balance of support and compliance allows for better packing of cavities such as aneurysms, resulting in a denser packing, improved operability, and less likely to intrude into the parent artery.

[0083] The first spring coil 31, the second spring coil 32 and the third spring coil 33 are all formed by spirally winding a wire, and there may be a gap or almost no gap between adjacent spirals of each coil. The first spring coil 31, the second spring coil 32 and the third spring coil 33 may have the same or different pitches.

[0084] The length of the second spring coil 32 is preferably greater than that of the first spring coil 31. Optionally, the difference between the lengths of the second spring coil 32 and the first spring coil 31 is 1 cm to 100 cm. Preferably, the excess length of the second spring coil 32 over the first spring coil 31 is disposed at the distal end of the entire medical implant 30 to form the distal portion 302. In a preferred embodiment, the difference between the length of the second spring coil 32 and the length of the first spring coil 31 is 1 cm to 20 cm, which facilitates better positioning and shaping, and reduces the risk of protrusion into the parent vessel. Furthermore, the length of the third spring coil 33 is preferably the same as the length of the portion of the second spring coil 32 disposed outside the first spring coil 31.

[0085] The present application does not impose any restrictions on the outer diameter and inner diameter of the first spring coil 31 and the second spring coil 32, and they are generally set according to the diameter of the blood vessel to be implanted. For example, the outer diameter of the first spring coil 31 is 0.005 inches to 0.02 inches, and the outer diameter of the second spring coil 32 can be 0.004 inches to 0.016 inches. The present application does not impose any restrictions on the cross-sectional shape of the first wire material used to wind the first spring coil 31. Generally, the cross-sectional shape of the first wire material is circular, and the diameter of the first wire material can be 0.001 inches to 0.006 inches. The cross-sectional shape of the second wire material used to wind the second spring coil 32 is also not limited. Preferably, the cross-sectional shape of the second wire material is circular, and the diameter of the second wire material can be 0.0005 inches to 0.003 inches.

[0086] The first spring coil 31 and the third spring coil 33 may have the same outer diameter or different outer diameters, and may have the same inner diameter or different inner diameters. Optionally, the outer diameter of the third spring coil 33 is greater than or equal to the outer diameter of the first spring coil 31, and the outer diameter of the third spring coil 33 does not exceed 1.2 times the outer diameter of the first spring coil 31. Alternatively, the outer diameter of the third spring coil 33 is less than or equal to the outer diameter of the first spring coil 31, and the outer diameter of the first spring coil 31 does not exceed 1.2 times the outer diameter of the third spring coil 33. For example, the outer diameter of the third coil 33 may be 0.005 inch to 0.02 inch. The cross-sectional shape of the third wire material used to wind the third spring coil 33 is not limited. Generally, the cross-sectional shape of the third wire material is circular, and the diameter of the third wire material may be 0.001 inch to 0.006 inch.

[0087] Furthermore, the third spring coil 33 is configured to possess certain biological properties, such as promoting cell adhesion and growth. For example, increasing the surface roughness of the third spring coil 33 can facilitate cell adhesion and growth. The material of the third spring coil 33 can also be modified to load growth factors or certain drug molecules, such as by forming a coating on the outer surface of the third spring coil 33 that can carry a therapeutic substance.

[0088] Preferably, the second spring coil 32, the first spring coil 31, and the third spring coil 33 are bonded together using glue 34, such as light-curing glue, to simplify the process, reduce the difficulty of connection, and achieve a stable connection. The glue 34 can be made of a degradable material or a non-degradable material. Of course, in other embodiments, the first spring coil 31, the second spring coil 32, and the third spring coil 33 can also be bonded together without glue 34.

[0089] In a preferred embodiment of the present invention, the first spring coil 31, the second spring coil 32, and the third spring coil 33 are further fixedly connected by an anti-untwisting structure 35. The anti-untwisting structure 35 can be in the form of a thread, a hose, a coil, or other structures. One end of the anti-untwisting structure 35 is fixedly connected to the third spring coil 33, and the other end is fixedly connected to the second spring coil 32 and / or the first spring coil 31. In this embodiment, the anti-untwisting structure 35 has a head (not labeled) that is fixedly connected to the distal end of the third spring coil 33, such as by welding or gluing. The body of the anti-untwisting structure 35 is connected to the head and passes through the second spring coil 32 and is fixedly wrapped around it. The body of the anti-untwisting structure 35 can further pass through the second spring coil 32 and be fixedly wrapped around the first spring coil 31. The head of the anti-untwisting structure 35 is positioned and fixed at the distal end of the third spring coil 33 and can have a smooth surface, such as a circular surface, to form an atraumatic head. It should be understood that the anti-untwisting structure 35 can prevent the spring coils from being straightened under external forces, achieving an anti-untwisting effect and enhancing the reliability and stability of the connection between the spring coils. The material of the anti-untwisting structure 35 can be a non-degradable polymer material, such as polypropylene, polyethylene, etc., or a degradable polymer material. The material of the anti-untwisting structure 35 can be the same as or different from the material of the first spring coil 31. Therefore, the anti-untwisting structure 35 can further strengthen the connection strength between the three coils, making the connection more stable.

[0090] <Example 4>

[0091] This embodiment provides a method for preparing a medical implant to obtain the medical implant shown in any of the above embodiments.

[0092] The preparation method of the medical implant comprises:

[0093] providing a spring coil;

[0094] The proximal portion of the spring coil is made of at least partially biodegradable material, and the distal portion of the spring coil is made of at least partially non-biodegradable material, wherein the distal portion is connected to the distal end of the proximal portion.

[0095] Furthermore, the proximal portion is formed using a biodegradable first spring coil, and the distal portion is formed by at least partially positioning a non-biodegradable second spring coil outside the first spring coil. Furthermore, the second spring coil partially overlaps the first spring coil in the axial direction, or the second spring coil does not completely overlap the first spring coil in the axial direction. When the second spring coil partially overlaps the first spring coil in the axial direction, a non-biodegradable third spring coil is further positioned over the second spring coil, with the third spring coil positioned outside the first spring coil.

[0096] The preparation method may further include: making the distal portion capable of being visualized under X-ray, and / or making the proximal portion capable of being visualized under X-ray.

[0097] In summary, according to the technical solution provided by the embodiments of the present invention, after using the medical implant of the present invention, the degradable properties of the proximal portion can be utilized to effectively alleviate the space-occupying effect of compressing surrounding tissues and nerves caused by permanent retention in the body, and the softness of the spring coil can be improved, making the spring coil more compliant, and can better fill cavities such as aneurysms, forming a denser filling, while also taking into account both support and compliance.

[0098] It should be understood that the above is only a preferred embodiment of the present invention and is not a formal or substantial limitation of the present invention. For example, the present invention is not limited to fixing two or three spring coils together after split molding. In short, as long as the proximal portion of the spring coil can be degraded and the distal portion can be non-degradable, the glue bonding fixation and the anti-untwisting structure can be set selectively or simultaneously. In addition, according to the content disclosed in Example 2, it can be understood that the proximal portion can be made entirely of biodegradable materials, such as consisting of a single first spring coil. According to the content disclosed in Example 1 or Example 3, it can also be understood that the proximal portion can be a double-layer structure, that is, composed of an outer layer and an inner layer, wherein the outer layer of the proximal portion is at least partially biodegradable, and the inner layer of the proximal portion is non-biodegradable, such as the outer layer of the proximal portion is the first spring coil, and the inner layer of the proximal portion is the second spring coil. Secondly, according to the disclosure of Example 1 or Example 2, it can also be understood that the distal portion can be made entirely of non-biodegradable materials, such as being composed of a single second spring coil. According to the disclosure of Example 3, the distal portion can also be a double-layer structure, namely, composed of an outer layer and an inner layer, wherein both the outer and inner layers of the distal portion are non-biodegradable, such as the outer layer of the distal portion being the third spring coil and the inner layer being the second spring coil. Furthermore, although the innovation of the present invention originates from the field of aneurysm and embolization technology, those skilled in the art will understand that the present invention can also be applied to occlusion technologies in other locations.

[0099] It should also be understood that the above description is merely a preferred embodiment of the present invention and does not constitute any formal or substantial limitation to the present invention. Furthermore, although the innovation of the present invention originates from aneurysm occlusion, those skilled in the art will appreciate that the present invention can also be applied to the occlusion of different sites, such as atrial septal defect and patent foramen ovale, and the present invention does not impose any limitation thereto.

[0100] It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any equivalent changes, modifications, and evolutions made by those skilled in the art using the technical content disclosed above without departing from the spirit and scope of the present invention are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A medical implant for occluding a target cavity, wherein the medical implant has an expanded state in which the implant is wound from a distal end to a proximal end into a preset shape, and a compressed state in which the implant is delivered from an intravascular space to a target cavity, characterized in that: comprising a spring coil having an at least partially biodegradable proximal portion and an at least partially non-biodegradable distal portion, the distal portion being connected to a distal end of the proximal portion; The proximal portion is composed of an outer layer formed by a first spring coil and an inner layer formed by a second spring coil, and the outer layer of the proximal portion is arranged around the inner layer of the proximal portion; The distal portion is composed of an outer layer formed by a third spring coil and an inner layer formed by a second spring coil, the outer layer of the distal portion being arranged around the inner layer of the distal portion; The first spring coil is biodegradable as a whole, and the second spring coil and the third spring coil are not biodegradable as a whole.

2. The medical implant according to claim 1, wherein The first spring coil is made of a biodegradable material, and the second spring coil is made of a non-biodegradable material; a portion of the second spring coil is arranged outside the first spring coil to form the distal portion or the inner layer of the distal portion, and the other portion is arranged inside the first spring coil to form the inner layer of the proximal portion, so that the second spring coil partially overlaps with the first spring coil in the axial direction.

3. The medical implant according to claim 2, characterized in that When the second spring coil partially overlaps the first spring coil in the axial direction, an outer diameter of the portion of the second spring coil disposed outside the first spring coil is greater than or equal to an outer diameter of the other portion of the second spring coil disposed inside the first spring coil.

4. The medical implant according to claim 3, characterized in that An outer diameter of the portion of the second spring coil disposed outside the first spring coil is greater than or equal to an outer diameter of the first spring coil, and an outer diameter of the portion of the second spring coil disposed outside the first spring coil does not exceed 1.2 times the outer diameter of the first spring coil; or, an outer diameter of the portion of the second spring coil disposed outside the first spring coil is less than or equal to an outer diameter of the first spring coil, and an outer diameter of the first spring coil does not exceed 2 times the outer diameter of the portion of the second spring coil disposed outside the first spring coil.

5. The medical implant according to claim 2, wherein The first spring coil, the second spring coil and the third spring coil are fixedly connected; the third spring coil is made of a non-biodegradable material; and the length of the third spring coil is less than or equal to the length of the portion of the second spring coil disposed outside the first spring coil.

6. The medical implant according to claim 5, characterized in that The outer diameter of the third spring coil is greater than or equal to the outer diameter of the first spring coil, and the outer diameter of the third spring coil does not exceed 1.2 times the outer diameter of the first spring coil; or, the outer diameter of the third spring coil is less than or equal to the outer diameter of the first spring coil, and the outer diameter of the first spring coil does not exceed 1.2 times the outer diameter of the third spring coil.

7. The medical implant according to claim 5 or 6, characterized in that At least one of the third spring coil and the second spring coil is configured to be able to be visualized under X-ray, and / or the third spring coil is made of a shape memory alloy material.

8. The medical implant according to claim 1, wherein The first spring coil and the second spring coil are fixed by gluing; and / or the first spring coil and the second spring coil are fixedly connected by an anti-untwisting structure.

9. The medical implant according to claim 5, characterized in that The first spring coil, the second spring coil and the third spring coil are fixed by gluing; and / or the first spring coil, the second spring coil and the third spring coil are fixedly connected by an anti-untwisting structure.

10. The medical implant according to claim 2, wherein When the second spring coil partially overlaps the first spring coil in the axial direction, an outer diameter of the other portion of the second spring coil disposed inside the first spring coil is less than or equal to 0.9 times an inner diameter of the first spring coil.

11. The medical implant according to claim 1 or 2, characterized in that The second spring coil is made of a radiopaque material.

12. The medical implant according to claim 1 or 2, characterized in that The length of the distal portion is 1 cm to 100 cm.

13. The medical implant according to claim 12, characterized in that The length of the distal portion is 1 cm to 20 cm.

14. The medical implant according to claim 1 or 2, characterized in that The distal portion is further configured to be visible under X-rays, and / or the proximal portion is configured to be visible under X-rays.

15. The medical implant according to claim 1 or 2, characterized in that The distal end portion in a free state has an annular or arcuate shape.

16. A method for preparing a medical implant, wherein the medical implant is used to block a target cavity, characterized in that: The preparation method comprises: providing a spring coil; The proximal portion of the spring coil is made of at least partially biodegradable material, and the proximal portion is made to consist of an outer layer formed by a first spring coil and an inner layer formed by a second spring coil, wherein the outer layer of the proximal portion is arranged around the inner layer of the proximal portion; and The distal portion of the spring coil is made of at least partly non-biodegradable material, the distal portion is connected to the distal end of the proximal portion, and the distal portion is made into an outer layer formed by the third spring coil and an inner layer formed by the second spring coil, and the outer layer of the distal portion is arranged around the inner layer of the distal portion; The first spring coil is biodegradable as a whole, and the second spring coil and the third spring coil are not biodegradable as a whole.

17. The method for preparing a medical implant according to claim 16, wherein: The second spring coil partially overlaps with the first spring coil in the axial direction.

18. The method for preparing a medical implant according to claim 16, wherein: The first spring coil, the second spring coil and the third spring coil are fixed by gluing, and / or the first spring coil, the second spring coil and the third spring coil are further fixedly connected by an anti-untwisting structure.

19. The method for preparing a medical implant according to claim 16, wherein: The first spring coil and the second spring coil are fixed by gluing, and / or the first spring coil and the second spring coil are further fixedly connected by an anti-untwisting structure.

20. The method for preparing a medical implant according to any one of claims 16 to 19, characterized in that: The distal portion is made to be able to be visualized under X-ray, and / or the proximal portion is made to be able to be visualized under X-ray.

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