Degradable vena cava filter with auxetic structure

Abstract

The present application provides a degradable vena cava filter with an expansion structure, which relates to the field of cardiovascular medical devices, and includes a stent segment, which includes a plurality of expansion components connected in sequence along the circumferential direction, each expansion component is provided with an anchor hook, and the anchor hook is embedded in the blood vessel wall for positioning the filter; when the plurality of expansion components are stretched, the plurality of expansion components expand outward in a direction away from the axis. By providing a plurality of expansion components, when the expansion components are stretched due to blood flow impact, the plurality of expansion components can respectively expand outward in the radial direction and drive the corresponding anchor hooks to expand outward, so that the stent segment fits more closely to the blood vessel wall, improves the anchoring ability of the anchor hook on the blood vessel wall, and reduces the displacement problem of the degradable vena cava filter with an expansion structure during use.

Description

Technical Field

[0001] The present application relates to the field of cardiovascular medical devices, and in particular to a degradable vena cava filter with a tensile structure. Background Art

[0002] Pulmonary embolism (PE) refers to a pathological and clinical state in which a blood clot is retained in the pulmonary artery and blocks blood flow to other parts of the lungs. It is the third most common cardiovascular disease after coronary heart disease and stroke. According to statistics, 90% of PE patients have blood clots from deep vein thrombosis (DVT).

[0003] At present, the main treatments for pulmonary embolism include systemic anticoagulation, local thrombolysis and thrombectomy. However, for patients with contraindications to anticoagulation or bleeding complications during anticoagulation, as well as thrombophilia and repeated PE, an inferior vena cava filter (IVCF) needs to be implanted to prevent pulmonary embolism caused by the detachment of DVT emboli. The earliest permanent IVCF has a high complication rate due to long-term retention in the body and requires patients to take medication for life. Currently, recyclable IVCF is more commonly used, but part of the filter will be covered by the vascular endothelium 2 weeks after the IVCF is implanted, resulting in a short recovery window, difficult recovery, and high complication rate. In recent years, degradable materials have been widely used in clinical practice, and degradability has also become a future development trend. Degradable IVCF gradually degrades after completing the task of preventing pulmonary embolism, which can avoid long-term complications and the risk of secondary surgery for removal, reduce the burden on patients, and improve prognosis.

[0004] The current filter displacement problem is a major pain point of traditional biodegradable IVCF. Since the materials of traditional biodegradable IVCF will continue to degrade with use, and the blood flow impact will cause the filter to be stretched and contracted, the filter's anchoring ability will continue to decrease, causing displacement during use, which needs to be improved. Summary of the invention

[0005] In view of this, the embodiments of the present specification provide a degradable vena cava filter with a tensile structure, which reduces the problem of displacement of the filter during use.

[0006] The present invention provides the following technical solutions: a degradable vena cava filter with a tensile expansion structure, comprising a stent segment;

[0007] The stent segment includes a plurality of expansion components connected in sequence along the circumferential direction, each expansion component is provided with an anchor hook, and the anchor hook is embedded in the blood vessel wall for filter positioning;

[0008] When the tensile expansion component is stretched, it expands outward and drives the anchor hook to expand outward.

[0009] Through the above technical solution, multiple expansion components are set, and when the expansion components are stretched due to blood flow impact, the multiple expansion components can expand radially in a direction away from the axis line, fit more closely to the blood vessel wall, improve the anchoring ability of the anchor hook on the blood vessel wall, and reduce the displacement problem of the entire filter during use.

[0010] Preferably, each expansion assembly is composed of a plurality of expansion units arranged in an array, and the anchor hook is fixed on the expansion unit.

[0011] Through the above technical solution, each expansion assembly is arranged to be composed of a plurality of expansion units, and then the overall shape of the expansion assembly can be changed by adjusting the configuration of the expansion unit, thereby improving the adaptability to different blood vessel walls.

[0012] Preferably, it further comprises a filter screen segment, the filter screen segment comprises a restraining ring and a filter screen, the outer diameter of the restraining ring is smaller than the diameter of the support segment, and the filter screen is arranged between the support segment and the restraining ring;

[0013] The filter screen is formed by a plurality of filter threads interwoven with each other, and each filter thread is respectively connected to a support segment and a restraining ring.

[0014] Preferably, each expansion assembly is provided with a limiting ring at one end close to the constraint ring, and the plurality of filter wires correspond to the plurality of limiting rings one by one, each filter wire passes through the corresponding limiting ring, and each filter wire is connected to the bracket segment through the corresponding limiting ring.

[0015] Through the above technical solution, a limiting ring is set so that the filter wire is connected to the limiting ring one-to-one, reducing the offset of the filter wire relative to the bracket section of the limiting ring, thereby reducing the rotational displacement of the filter segment and improving the structural stability of the filter segment.

[0016] Preferably, the material of the stent segment is a degradable metal material, the material of the restraint ring and the filter wire are both biodegradable polymers, and the thickness of the restraint ring is smaller than the diameter of the filter wire.

[0017] Through the above technical solution, since the degradation rate of the degradable metal material is lower than that of the biodegradable polymer, the degradation rate of the stent segment will be lower than that of the constraint ring and the filter. Furthermore, after the stent segment is implanted in the body, it undergoes endothelialization and is wrapped, which reduces the contact area with the blood and further slows down the degradation rate. Therefore, the degradation of the stent segment will be later than that of the filter segment, so the overall stability can be effectively guaranteed to avoid the displacement of the overall structure and the detachment of thrombus.

[0018] On the other hand, since the thickness of the restraint ring is smaller than the diameter of the filter wire, when the captured thrombus has passed the critical period after thrombolysis or thrombectomy, the restraint ring will be degraded earlier than the filter wire, causing the filter to disperse and restore blood flow.

[0019] Preferably, each anchor hook is arranged obliquely along the axial direction of the bracket segment toward one end close to the filter segment.

[0020] Through the above technical solution, the anchoring hook can be more stably anchored on the blood vessel wall along the blood flow, further enhancing the overall anchoring ability and reducing displacement.

[0021] Preferably, the tip of each anchoring hook is a rounded structure.

[0022] Through the above technical solution, the tip of the anchoring hook is arranged to have a rounded structure, which can reduce the damage of the tip of the anchoring hook to the blood vessel wall.

[0023] Preferably, a connecting assembly is provided between every two adjacent tensile expansion assemblies, and any two adjacent tensile expansion assemblies are connected via the connecting assembly.

[0024] Preferably, the configuration of the auxetic unit is a concave auxetic structure.

[0025] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0026] 1. The present invention arranges anchor hooks on the expansion components. When the stent segment is impacted by blood flow, several expansion components can expand outward in a direction away from the axis, so that the anchor hooks fit more closely with the blood vessel wall, thereby improving the anchoring ability of the stent segment and reducing the displacement problem of the entire filter during use;

[0027] 2. The present invention provides a plurality of expansion components, so that after the blood flow impacts the stent segment, the plurality of expansion components expand outwards respectively, so that each expansion component fits more closely with the blood vessel wall, increases the contact area between each expansion component and the blood vessel wall, and reduces the occurrence of overall filter tilting;

[0028] 3. The stent segment and filter screen segment of the filter in the present invention are made of different degradable materials respectively. The filter screen segment degrades first and the stent segment degrades later, thus achieving step-by-step degradation and controlling the degradation rate. This can not only prevent pulmonary embolism, but also avoid premature detachment of blood clots and complications of long-term implantation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1It is a schematic diagram of the overall structure of the first embodiment;

[0031] Figure 2 This is a schematic diagram of the overall structure of the filter used to display the filter in Example 1;

[0032] Figure 3 This is a schematic diagram of the overall structure of the restraint ring in the first embodiment;

[0033] Figure 4 It is a structural schematic diagram of the expansion unit of the second embodiment;

[0034] Figure 5 It is a structural schematic diagram of the expansion unit of Example 3;

[0035] Figure 6 It is a partial structural schematic diagram of a stent segment of Example 4;

[0036] Figure 7 It is a partial structural schematic diagram of the stent segment of Example 5.

[0037] Reference numerals:

[0038] 1. Bracket segment;

[0039] 101. Auxetic component; 1011. Auxetic unit;

[0040] 102. connection component; 1021. connection unit;

[0041] 103. Anchor hook;

[0042] 104, limit ring;

[0043] 105. Connecting rod;

[0044] 2. Filter section;

[0045] 201, filter screen; 2011, filter wire;

[0046] 202. Constraint ring. DETAILED DESCRIPTION

[0047] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0048] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0049] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0050] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0051] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0052] The inventors have discovered that the conventional biodegradable inferior vena cava filter will stretch and contract as the blood flow continues to impact it, causing the anchor hook to detach from the blood vessel wall and causing the filter to shift.

[0053] Based on this, the present specification proposes a degradable vena cava filter with a tensile expansion structure: Figure 1As shown, the stent segment 1 includes a plurality of expansion components 101, and the expansion components 101 are provided with anchor hooks 103. After being impacted by blood flow, the expansion components 101 are stretched and expanded outward, and the anchor hooks 103 are driven to expand outward, so that the anchor hooks 103 and the expansion components 101 are more closely attached to the blood vessel wall, thereby enhancing the overall anchoring ability and reducing filter displacement.

[0054] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0055] Embodiment 1

[0056] Reference Figure 1 and Figure 2 , including a support segment 1 and a filter segment 2. The support segment 1 is annular, and includes a plurality of expansion components 101 and a plurality of connection components 102. The plurality of expansion components 101 and the plurality of connection components 102 are distributed at intervals along the circumferential direction and are fixedly connected in sequence.

[0057] Each expansion assembly 101 is composed of a plurality of expansion units 1011 arranged in sequence along the axial direction, and the configuration of each expansion unit 1011 is a concave expansion structure.

[0058] Each connection assembly 102 is composed of a plurality of connection units 1021 arranged in sequence along the axial direction, and the configuration of each connection unit 1021 is an inwardly concave tensile expansion structure.

[0059] A plurality of anchor hooks 103 are fixed at intervals along the axial direction on the plurality of expansion units 1011 in each expansion assembly 101, and each anchor hook 103 is arranged on the side of the expansion unit 1011 away from the axis of the stent segment 1, and the anchor hook 103 is inclined along the axis of the stent segment 1 toward the end close to the filter segment 2, and the angle between each anchor hook 103 and the axis of the stent segment 1 is 45 degrees. The tip of the anchor hook 103 is a rounded structure, so that when the anchor hook 103 is embedded in the blood vessel wall, the damage to the blood vessel wall can be effectively reduced.

[0060] During actual use, after the filter segment 2 captures the thrombus, the stent segment 1 will be impacted by the blood flow, and the stent segment 1 will be stretched when impacted by the blood flow. After stretching, the several tensile expansion components 101 will expand radially outward, and the anchor hooks 103 will move deeper into the blood vessel wall, more closely fitting the blood vessel wall, improving the overall anchoring ability and reducing the possibility of overall displacement. After the stent segment 1 is expanded outward as a whole, the stent segment 1 will fit more closely with the blood vessel wall, and with the assistance of the anchor hooks 103, the inclination of the stent segment 1 relative to the blood vessel wall can be effectively reduced, and the stability of the overall installation and fixation can be improved.

[0061] The filter segment 2 includes a constraint ring 202 and a filter 201. The constraint ring 202 and the filter 201 are coaxially arranged with the support segment 1. The outer diameter of the constraint ring 202 is smaller than the diameter of the support segment 1. The axial ends of the filter 201 are respectively connected to the support segment 1 and the constraint ring 202.

[0062] Reference Figure 2 and Figure 3 In this embodiment, a total of six groups of expansion assemblies 101 are provided. A semicircular ring-shaped limiting ring 104 is fixed on the expansion unit 1011 close to the filter screen 201 in each group of expansion assemblies 101, and the axis line of each limiting ring 104 is perpendicular to and intersects with the axis line of the filter screen 201.

[0063] In this embodiment, the filter screen 201 is formed by interweaving six filter threads 2011, and the six filter threads 2011 pass through the six limiting rings 104 one by one. The middle section of each filter thread 2011 is located on the corresponding limiting ring 104, and each filter thread 2011 is located on both sides of the corresponding limiting ring 104 and is interlaced and pressed and fixed. Therefore, in actual use, the displacement of the filter thread 2011 relative to the corresponding limiting ring 104 can be reduced, the structural stability of the filter screen 201 is improved, and the phenomenon of blood clots falling off caused by the rotation and displacement of the filter screen 201 is effectively reduced. The six filter threads 2011 pass through the six corresponding limiting rings 104 in the same way and then interweave to form a diamond grid. All endpoints of the six filter threads 2011 meet on the same plane and are fixed on the constraint ring 202. The mesh pores on the filter 201 gradually decrease from the stent segment 1 to the restraining ring 202, and the minimum pore size of the mesh on the filter 201 is 1 mm, and the inner diameter of the restraining ring 202 is 1 mm. In the actual process of capturing thrombi, the pores of the filter 201 close to one end of the restraining ring 202 can reduce the interception of thrombi with a diameter less than 1 mm, because even if a thrombus with a diameter less than 1 mm enters the lungs, it will not cause pulmonary embolism, so the blockage of the filter 201 can be effectively reduced, and the possibility of blood flow blockage caused by the blockage of the filter 201 can be reduced.

[0064] Reference Figure 1 and Figure 2 The stent segment 1 is made of a biodegradable metal material, specifically a magnesium alloy in this embodiment. The filter 2011 and the restraint ring 202 are made of biodegradable polymers, specifically PDO in this embodiment. The thickness of the restraint ring 202 is less than the diameter of the filter 2011.

[0065] In other embodiments, the stent segment 1 may also be manufactured by additive manufacturing technology.

[0066] The degradation process of the filter as a whole in this embodiment is as follows:

[0067] S1. After the filter is implanted in the body to capture thrombus and passes the critical period through thrombolysis or thrombectomy, the filter filament 2011 and the restraint ring 202 made of biodegradable polymer will degrade before the stent segment 1, and because the thickness of the restraint ring 202 is smaller than the diameter of the filter filament 2011, the restraint ring 202 will complete the degradation before the filter filament 2011. After the restraint ring 202 is completely degraded, the filter mesh 201 will disperse to restore smooth blood flow, and gradually degrade.

[0068] S2, the stent segment 1 is made of a degradable metal material, which plays a role in supporting the blood vessel wall on the one hand, and on the other hand, the degradation rate of the degradable metal material is lower than the degradation rate of the biodegradable polymer. After the stent segment 1 is implanted in the body, it undergoes endothelialization, the stent segment 1 is wrapped, the contact area with the blood is reduced, and the degradation rate is further reduced, thereby effectively ensuring that the degradation rate of the stent segment 1 is slower than the degradation rate of the filter 201, thereby ensuring the stability of the overall structure and reducing the occurrence of overall displacement and thrombus detachment.

[0069] Embodiment 2

[0070] The difference from the first embodiment is that, referring to Figure 4 The configuration of the expansion unit 1011 is a rotational expansion structure.

[0071] Embodiment 3

[0072] The difference from the first embodiment is that, referring to Figure 5 The configuration of the expansion unit 1011 is a symmetrical expansion structure.

[0073] Embodiment 4

[0074] The difference from the first embodiment is that, referring to Figure 6 The connecting unit 1021 is a traditional diamond-shaped non-tensile unit, and the bracket segment adopts a structure combining a non-tensile unit and a tensile unit, which improves the overall mechanical properties of the filter while maintaining the tensile effect.

[0075] Embodiment 5

[0076] The difference from the first embodiment is that, referring to Figure 7 The expansion unit 1011 is fixed with a connecting rod 105 , and the limiting ring 104 is opened at one end of the connecting rod 105 away from the expansion unit 1011 .

[0077] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the product embodiment described later, since it corresponds to the method, the description is relatively simple, and the relevant parts can be referred to the partial description of the system embodiment.

[0078] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A degradable vena cava filter with a tensile expansion structure, characterized in that: comprising a stent segment (1); The stent segment (1) comprises a plurality of expansion assemblies (101) and connection assemblies (102) connected in sequence along the circumferential direction, each expansion assembly (101) is composed of a plurality of expansion units (1011) arranged in sequence along the axial direction, and the configuration of each expansion unit (1011) is any one of an inward-concave expansion structure, a rotational expansion structure, and a symmetrical expansion structure; each connection assembly (102) is composed of a plurality of connection units (1021) arranged in sequence along the axial direction, and the configuration of each connection unit (1021) is any one of an inward-concave expansion structure and a diamond-shaped non-expandable unit; each expansion assembly (101) is provided with an anchor hook (103), and the anchor hook (103) is embedded in the blood vessel wall for filter positioning; The expansion component (101) can expand outwardly in the radial direction. When the expansion component (101) is pulled, it expands outward and drives the anchor hook (103) to expand outward.

2. The degradable vena cava filter with a tensile expansion structure according to claim 1, characterized in that: The anchor hook (103) is fixed on the auxetic unit (1011).

3. The degradable vena cava filter with a tensile structure according to claim 1, characterized in that: Also includes a filter section (2); The filter screen segment (2) comprises a restraining ring (202) and a filter screen (201); the outer diameter of the restraining ring (202) is smaller than the diameter of the support segment (1); and the filter screen (201) is arranged between the support segment (1) and the restraining ring (202); The filter screen (201) is formed by a plurality of filter threads (2011) interwoven with each other, and each filter thread (2011) is respectively connected to the support segment (1) and the restraint ring (202).

4. The degradable vena cava filter with a tensile expansion structure according to claim 3, characterized in that: Each of the expansion components (101) is provided with a limiting ring (104) at one end close to the constraint ring (202); the plurality of filter threads (2011) correspond one-to-one to the plurality of limiting rings (104); each of the filter threads (2011) passes through a corresponding limiting ring (104); and each of the filter threads (2011) is connected to the support segment (1) via a corresponding limiting ring (104).

5. The degradable vena cava filter with a tensile expansion structure according to claim 3, characterized in that: The material of the stent segment (1) is a degradable metal material, the materials of the restraint ring (202) and the filter (2011) are both biodegradable polymers, and the thickness of the restraint ring (202) is smaller than the diameter of the filter (2011).

6. The degradable vena cava filter with a tensile structure according to claim 3, characterized in that: Each anchor hook (103) is arranged obliquely along the axial direction of the support segment (1) toward an end close to the filter segment (2).

7. The degradable vena cava filter with a tensile expansion structure according to claim 1, characterized in that: The tip of each anchoring hook (103) is in a rounded structure.

8. The degradable vena cava filter with a tensile structure according to claim 1, characterized in that: Any two adjacent expansion assemblies (101) are connected via a connecting assembly (102).

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