Soluble inferior vena cava filter

Abstract

The invention belongs to the technical field of medical instruments, and provides a soluble inferior vena cava filter. The soluble inferior vena cava filter comprises a filtering part and a restraint ring, the filtering part comprises an expansion part and contraction parts, the expansion part is located in the middle of the soluble inferior vena cava filter, and the contraction parts are located at the two ends of the soluble inferior vena cava filter; the filtering part is composed of degradable material wires, and the two ends of the filtering part are restrained in the restraining rings to form the contraction part. The soluble inferior vena cava filter can be completely degraded in vivo and does not need to be taken out through a secondary operation; the expansion part provides enough supporting force and stability, and the contraction part plays a role in filtering thrombus; the staged degradation design is adopted, the restraint ring is degraded firstly, the contraction part is expanded, then the expansion part is gradually degraded, the inferior vena cava cannot be blocked, and the risks of stress fracture and collapse or displacement of the supporting part are reduced; and a proper degradable material is selected, so that the filter has supporting force, stability and thrombus filtering effect.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a soluble inferior vena cava filter. Background Technology

[0002] Pulmonary embolism is a serious disease that endangers human life. Its main cause is the blockage of the pulmonary vascular system by a blood clot. The most effective way to prevent pulmonary embolism is to implant a vena cava filter. After vena cava filter implantation, the probability of recurrence of pulmonary embolism is significantly reduced to 2-5%.

[0003] Currently, common vena cava filters on the market are mainly divided into permanent, temporary, and retrievable filters. Permanent filters are suitable for situations requiring lifelong prevention of thromboembolism, but are prone to long-term complications such as filter displacement, breakage, and perforation. Temporary filters are generally implanted temporarily during the acute phase and can be removed when the risk of thrombus dislodgement decreases, but clinical management is complex and prone to infection risks. Retrievable filters are currently the most commonly used; they are implanted during the high-risk phase and removed after the risk decreases. However, in clinical practice, most retrievable filters are not successfully removed within the retrievable period, leading to long-term complications. The main reason why retrievable filters cannot be removed within the protection period is that the filter adheres to the vascular wall tissue; forced removal may cause complications such as vena cava tearing.

[0004] To mitigate the risks during removal, most vena cava filters employ an umbrella-shaped structure. After implantation, the filter makes point-to-surface contact with the vessel wall, reducing adhesion between the filter and the endothelial tissue by minimizing the contact area. However, the umbrella-shaped structure cannot provide sufficient support, leading to various displacements or even detachment, thus failing to achieve the desired effect. Changing the point-to-surface contact to a line-to-surface contact enhances the filter's stability on the vessel wall, but also exacerbates adhesion between the filter and the endothelial tissue, still presenting the problem of unsuccessful filter removal.

[0005] Soluble vena cava filters gradually degrade after fulfilling their function of preventing pulmonary embolism, effectively avoiding long-term complications and the risk of secondary surgical removal, and are expected to become the mainstream vena cava filter. Currently, most soluble vena cava filters are partially soluble, and they generally suffer from problems such as displacement, vascular wall inflammation, poor thrombus filtration, and insufficient support due to gradual degradation, which limits their application.

[0006] Therefore, providing a soluble inferior vena cava filter that combines support, stability, and thrombus filtration has broad application prospects in clinical medicine. Summary of the Invention

[0007] The purpose of this invention is to provide a soluble inferior vena cava filter to address the shortcomings of existing technologies.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a soluble inferior vena cava filter, comprising a filter element and a restraint ring; The filter element includes an expansion section and a contraction section, with the expansion section located in the middle of the soluble inferior vena cava filter and the contraction section located at both ends of the soluble inferior vena cava filter; The filter element is composed of biodegradable material filaments, and both ends of the filter element are constrained within a constraint ring to form the constricted portion.

[0009] Preferably, the degradable material filaments are uniformly distributed radially; The number of degradation material filaments is 16 to 30, and the diameter of the degradation material filaments is 50 to 150 μm.

[0010] Preferably, the degradable material filament is made of a first degradable material, and the constraint ring is made of a second degradable material.

[0011] Preferably, the degradation cycle of the first degradation material is longer than that of the second degradation material.

[0012] Preferably, the first degradation material is a composite degradation material containing calcium phosphate nanoparticles.

[0013] Preferably, the mass fraction of calcium phosphate nanoparticles in the first degradable material is 30-50%.

[0014] Preferably, the calcium phosphate nanoparticles have a particle size of 20~100 nm.

[0015] Preferably, the second degradation material is a composite degradation material containing magnesium alloy.

[0016] Preferably, the mass fraction of magnesium alloy in the second degradable material is 10-30%.

[0017] The beneficial effects of this invention are: 1) The soluble inferior vena cava filter of the present invention is an integrated biodegradable filter that can be completely degraded in the body, avoiding the long-term complications caused by permanent filters due to long-term retention in the body, avoiding the risks of temporary filters and recyclable filters that require secondary surgery to remove, and improving the patient's quality of life.

[0018] 2) In the soluble inferior vena cava filter of the present invention, the dilatation section provides sufficient support and stability, while the constriction section plays the role of filtering thrombi. During the treatment risk period, thrombi are intercepted by the constriction sections at both ends. The phased degradation design is adopted. After the treatment risk period ends, the constraint ring degrades first, causing the constriction section to expand and adhere tightly to the inside of the blood vessel to maintain normal blood flow. The dilatation section then gradually degrades, which will not cause the inferior vena cava to be blocked due to excessively large degradation fragments, and reduces the risk of stress fracture, collapse or displacement of the support part during the degradation process.

[0019] 3) This invention combines filter support, stability, and thrombus filtration effect by selecting suitable degradation materials; and achieves phased degradation of the filter by controlling the molecular weight of the polymer in the degradation materials. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the soluble inferior vena cava filter of the present invention, wherein 1 is a filtering component, 2 is an expansion part, 3 is a contraction part, and 4 is a constraint ring. Detailed Implementation

[0021] This invention provides a soluble inferior vena cava filter, comprising a filter element and a restraint ring; The filter element includes an expansion section and a contraction section, with the expansion section located in the middle of the soluble inferior vena cava filter and the contraction section located at both ends of the soluble inferior vena cava filter; The filter element is composed of biodegradable material filaments, and both ends of the filter element are constrained within a constraint ring to form the constricted portion.

[0022] In this invention, the degradable material filaments are preferably uniformly distributed radially; The number of the degradable material filaments is preferably 16 to 30, more preferably 20 to 26, and even more preferably 22 to 24; the diameter of the degradable material filaments is preferably 50 to 150 μm, more preferably 70 to 130 μm, and even more preferably 90 to 110 μm.

[0023] In this invention, the degradable material filament is preferably made of a first degradable material, and the constraint ring is preferably made of a second degradable material.

[0024] In this invention, the degradation cycle of the first degradation material is preferably longer than that of the second degradation material.

[0025] In this invention, the degradation cycle of the first degradation material is preferably 6 to 12 months, and more preferably 7 to 10 months; The degradation cycle of the second degradation material is preferably 2 to 4 months, and more preferably 3 months.

[0026] In this invention, the first degradation material is preferably a composite degradation material containing calcium phosphate nanoparticles. The incorporation of calcium phosphate nanoparticles improves the mechanical strength of the degradation material, giving the first degradation material sufficient support and stability.

[0027] In this invention, the mass fraction of calcium phosphate nanoparticles in the first degradable material is preferably 30-50%, more preferably 35-45%, and even more preferably 40%.

[0028] In this invention, the particle size of the calcium phosphate nanoparticles is preferably 20-100 nm, more preferably 40-80 nm, and even more preferably 60 nm. Setting the particle size of the calcium phosphate nanoparticles within a suitable range avoids surface defects caused by large-sized particles and prevents the calcium phosphate nanoparticles from diffusing through the intercellular spaces of vascular endothelial cells due to excessively small particle size.

[0029] In this invention, the first degradation material is preferably a composite degradation material of calcium phosphate nanoparticles and a first polymer; The first polymer preferably comprises one or more of polycaprolactone, polydioxanone, and polyglycolic acid.

[0030] In this invention, the molecular weight of the first polymer is preferably 200,000 to 300,000, more preferably 220,000 to 270,000, and even more preferably 250,000.

[0031] In this invention, the first degradation material is preferably prepared by mechanical blending.

[0032] In this invention, the second degradation material is preferably a composite degradation material containing magnesium alloy.

[0033] In this invention, the mass fraction of magnesium alloy in the second degradable material is preferably 10-30%, more preferably 15-25%, and even more preferably 20%.

[0034] In this invention, the magnesium alloy preferably comprises magnesium alloy WE43 or magnesium alloy AZ31.

[0035] In this invention, the second degradation material is preferably a composite degradation material of magnesium alloy and second polymer; The second polymer preferably comprises polylactic acid and / or polyhydroxy fatty acid esters.

[0036] In this invention, the molecular weight of the second polymer is preferably 30,000 to 80,000, and more preferably 50,000.

[0037] In this invention, by adjusting the molecular weights of the first polymer and the second polymer, the degradation rates of the first degradation material and the second degradation material are controlled, thereby making the degradation cycle of the first degradation material longer than that of the second degradation material, thus achieving staged degradation.

[0038] In this invention, the second degradation material is preferably prepared by mechanical blending.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] The magnesium alloy used in the embodiments and comparative examples of this invention is WE43 magnesium alloy.

[0041] Example 1

[0042] A soluble inferior vena cava filter comprises a filter element and a constriction ring. The filter element includes an expansion section and a contraction section. The expansion section is located in the middle of the soluble inferior vena cava filter, and the contraction sections are located at both ends of the filter. The filter element consists of 24 biodegradable material filaments with a diameter of 150 μm, which are uniformly distributed radially. The two ends of the biodegradable material filaments are confined within the constriction ring to form the contraction sections.

[0043] The degradable material filament is made from a first degradable material, which is a composite degradable material of calcium phosphate nanoparticles and polycaprolactone (polycaprolactone has a molecular weight of 300,000). The calcium phosphate nanoparticles have a particle size of 60 nm and a mass fraction of 30%. The first degradable material is prepared by co-extrusion of calcium phosphate nanoparticles and polycaprolactone at 80°C, and the degradation cycle reaches 10 months.

[0044] The constraint ring is made of a second degradation material, which is a composite degradation material of magnesium alloy and polylactic acid (polylactic acid with a molecular weight of 50,000), wherein the mass fraction of magnesium alloy is 20%. The second degradation material is obtained by co-extrusion of magnesium alloy and polylactic acid at 190°C, and the degradation cycle reaches 3 months.

[0045] Example 2

[0046] The particle size of the calcium phosphate nanoparticles in Example 1 was modified to 20 nm, and the mass fraction was modified to 40%, while other aspects remained the same as in Example 1.

[0047] Example 3

[0048] The mass fraction of magnesium alloy in Example 1 was modified to 30%, the molecular weight of polylactic acid was modified to 80,000, and the rest were the same as in Example 1.

[0049] Example 4

[0050] A soluble inferior vena cava filter comprises a filter element and a constriction ring. The filter element includes an expansion section and a contraction section. The expansion section is located in the middle of the soluble inferior vena cava filter, and the contraction sections are located at both ends of the filter. The filter element consists of 16 biodegradable material filaments with a diameter of 90 μm, which are uniformly distributed radially. The two ends of the biodegradable material filaments are confined within the constriction ring to form the contraction sections.

[0051] The degradable material filaments are made from a first degradable material, which is a composite degradable material of calcium phosphate nanoparticles and polyglycolic acid (polyglycolic acid has a molecular weight of 200,000). The calcium phosphate nanoparticles have a particle size of 20 nm and a mass fraction of 40%. The first degradable material is prepared by co-extrusion of calcium phosphate nanoparticles and polyglycolic acid at 250°C, and the degradation cycle reaches 6 months.

[0052] The constraint ring is made of a second degradation material, which is a composite degradation material of magnesium alloy and polyhydroxyalkanoate (polyhydroxyalkanoate has a molecular weight of 80,000), wherein the mass fraction of magnesium alloy is 30%. The second degradation material is obtained by co-extrusion of magnesium alloy and polyhydroxyalkanoate at 220°C, and the degradation cycle reaches 4 months.

[0053] Example 5

[0054] A soluble inferior vena cava filter comprises a filter element and a constriction ring. The filter element includes an expansion section and a contraction section. The expansion section is located in the middle of the soluble inferior vena cava filter, and the contraction sections are located at both ends of the filter. The filter element consists of 30 biodegradable material filaments with a diameter of 50 μm, which are uniformly distributed radially. The two ends of the biodegradable material filaments are confined within the constriction ring to form the contraction sections.

[0055] The degradable material filaments are made from a first degradable material, which is a composite degradable material of calcium phosphate nanoparticles and poly(p-dioxanone) (poly(p-dioxanone) has a molecular weight of 250,000). The calcium phosphate nanoparticles have a particle size of 100 nm and a mass fraction of 50%. The first degradable material is prepared by co-extrusion of calcium phosphate nanoparticles and poly(p-dioxanone) at 140°C, and the degradation period reaches 7 months.

[0056] The constraint ring is made of a second degradation material, which is a composite degradation material of magnesium alloy and polylactic acid (polylactic acid with a molecular weight of 30,000), wherein the mass fraction of magnesium alloy is 10%. The second degradation material is obtained by co-extrusion of magnesium alloy and polylactic acid at 190°C, and the degradation cycle reaches 2 months.

[0057] Comparative Example 1

[0058] The calcium phosphate nanoparticles in Example 1 are omitted, and the molecular weight of polycaprolactone is modified to 400,000. Otherwise, it is the same as in Example 1.

[0059] Comparative Example 2

[0060] The magnesium alloy in Example 1 is omitted, the molecular weight of polylactic acid is modified to 120,000, and everything else is the same as in Example 1.

[0061] Comparative Example 3

[0062] The mass fraction of calcium phosphate nanoparticles in Example 1 was modified to 65%, and the particle size of the calcium phosphate nanoparticles was modified to 10 nm, while other aspects remained the same as in Example 1.

[0063] Comparative Example 4

[0064] The mass fraction of magnesium alloy in Example 1 was modified to 40%, and the rest was the same as in Example 1.

[0065] At 37°C, the soluble inferior vena cava filters of Examples 1-5 and Comparative Examples 1-4 were immersed in physiological saline for 24 hours, and the dilatation portion was observed to see if it broke. After immersion, the radial support force of the filter was measured according to ISO 25539-1:2017, and the test results are shown in Table 1.

[0066] A thrombus was simulated using a porcine blood clot with a diameter of 3-5 mm and a length of 10 mm, and the inferior vena cava was simulated using a transparent silicone tube with a diameter of 25 mm. A soluble inferior vena cava filter was implanted into the transparent silicone tube, and the blood flow velocity was controlled at 20 cm / s. The thrombus capture efficiency of the soluble inferior vena cava filter was calculated. The results are shown in Table 1.

[0067] Table 1. Radial support force and thrombus capture efficiency of soluble inferior vena cava filters.

[0068] As shown in Table 1, the soluble inferior vena cava filters of Examples 1-5 can maintain good thrombus capture efficiency while having high support and stability; while the radial support of Comparative Examples 1-4 is lower.

[0069] As can be seen from the above embodiments, the present invention provides a soluble inferior vena cava filter that combines high support, high stability and excellent thrombus capture efficiency; by controlling the molecular weight of the degradable polymer, the soluble inferior vena cava filter can achieve phased degradation; and by doping different polymers with calcium phosphate nanoparticles and magnesium alloys, the filter is endowed with sufficient support and stability.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A soluble inferior vena cava filter, characterized in that, Includes filter components and constraint rings; The filter element includes an expansion section and a contraction section, with the expansion section located in the middle of the soluble inferior vena cava filter and the contraction section located at both ends of the soluble inferior vena cava filter; The filter element is composed of biodegradable material filaments, and both ends of the filter element are constrained within a constraint ring to form the constricted portion.

2. The soluble inferior vena cava filter according to claim 1, characterized in that, The degradation material filaments are uniformly distributed radially. The number of degradation material filaments is 16 to 30, and the diameter of the degradation material filaments is 50 to 150 μm.

3. The soluble inferior vena cava filter according to claim 1 or 2, characterized in that, The degradable material filament is made of a first degradable material, and the constraint ring is made of a second degradable material.

4. The soluble inferior vena cava filter according to claim 3, characterized in that, The degradation cycle of the first degradation material is longer than that of the second degradation material.

5. The soluble inferior vena cava filter according to claim 4, characterized in that, The first degradation material is a composite degradation material containing calcium phosphate nanoparticles.

6. The soluble inferior vena cava filter according to claim 5, characterized in that, The mass fraction of calcium phosphate nanoparticles in the first degradation material is 30-50%.

7. The soluble inferior vena cava filter according to claim 5 or 6, characterized in that, The particle size of the calcium phosphate nanoparticles is 20~100nm.

8. The soluble inferior vena cava filter according to claim 7, characterized in that, The second degradation material is a composite degradation material containing magnesium alloy.

9. The soluble inferior vena cava filter according to claim 8, characterized in that, The mass fraction of magnesium alloy in the second degradation material is 10-30%.

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