A coil spring for reducing the risk of damage to the outer wall of an aneurysm and a method of manufacturing the same

Abstract

This invention provides a spring coil and its preparation method for reducing the risk of damage to the outer wall of a hemangioma. The invention features a novel structural design compared to conventional spring coils. The core characteristic of this structure is that the outer layer is a spring coil body with a secondary structure and a sparse primary structure; that is, the primary coil has a wide spacing between the coil wires, and the interior of the primary coil consists of expandable hydrogel hollow filaments. The sparse structure reduces the excessive pressure on the outer wall of the hemangioma during insertion, preventing rupture. The hollow hydrogel filament structure buffers the pressure exerted on the outer wall of the hemangioma after insertion, avoiding rupture that could worsen the patient's condition or even lead to death.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and in particular to a spring coil for reducing the risk of damage to the outer wall of a hemangioma and its preparation method. Background Technology

[0002] An aneurysm differs from a tumor in the conventional sense. It is caused by the destruction of the elastic and smooth muscle layers of the arterial wall, leading to localized weakening of the arterial wall and the formation of a sac-like protrusion. Aneurysms can occur anywhere in the arterial system, including the cerebral circulation and the peripheral arterial system. Intracranial aneurysms are the most serious type, with an incidence of approximately 2%-5% in the general population, as rupture can lead to subarachnoid hemorrhage, a potentially fatal condition. Currently, the main treatment options for aneurysms are open surgery and endovascular interventional therapy. Open surgery requires opening the cavity encapsulating the aneurysm, such as through craniotomy or thoracotomy, causing significant damage to the patient and resulting in a long recovery period. In contrast, endovascular interventional therapy for aneurysms, with its minimally invasive, safe, and effective advantages, has become the preferred clinical treatment option.

[0003] Currently, the embolic material used in endovascular interventional treatment of aneurysms is primarily coils. Coil placement is a crucial step, but its complexity and risks cannot be ignored. During deployment, the coils, due to their physical properties and the fragility of the aneurysm wall, are highly susceptible to compression of the aneurysm's outer wall. For example, the aneurysm wall is very fragile, and excessive tension applied to the coils and microcatheters may lead to intraoperative rupture. Improper handling of this compression can even cause aneurysm rupture, increasing surgical risks. Furthermore, the hemodynamic changes after coil implantation significantly impact both the aneurysm wall and the coils. The impact of blood flow can still be transmitted to the aneurysm wall through the gaps between the coils, causing aneurysm regeneration, enlargement, and even the formation of daughter aneurysms. In addition, continuous blood flow impact can also cause coil deformation and displacement, leading to aneurysm recurrence. These hemodynamic changes necessitate precise coil placement to minimize further compression and damage to the vessel wall. Currently, mainstream coil research focuses primarily on improving aneurysm filling rates, with little attention paid to coil implantation and its impact on the aneurysm during the implantation process. Traditional hydrogel coils are a combination of dense metal coils and solid hydrogel filaments. During the insertion process, inaccurate control of the pushing force may cause damage to the aneurysm wall, leading to surgical failure. In addition, the densely packed structure after insertion can directly transmit blood pressure to the aneurysm wall, which poses a significant risk to patients with hypertension. Summary of the Invention

[0004] To address the aforementioned problems, the primary objective of this invention is to provide a spring coil that reduces the risk of damage to the outer wall of a hemangioma. The core feature of this spring coil structure is that the outer layer is a spring coil body with a secondary structure and a sparse primary structure; that is, the primary coil has a wide spacing between the coil wires, and the interior of the primary coil consists of expandable hydrogel hollow filaments. The sparse primary structure reduces the excessive pressure exerted on the outer wall of the hemangioma during insertion, which could lead to rupture. The hollow hydrogel filament structure buffers the spring coil after insertion into the hemangioma, preventing pressure from high blood pressure on the outer wall of the hemangioma from causing rupture, which could worsen the patient's condition or even lead to death.

[0005] The second objective of this invention is to provide a method for preparing a spring coil that reduces the risk of damage to the outer wall of a hemangioma.

[0006] The technical solution adopted in this invention is as follows:

[0007] A spring coil for reducing the risk of damage to the outer wall of a hemangioma, characterized in that it comprises a spring coil body and hollow hydrogel filaments; the spring coil body has a secondary coil structure; the two ends of the hollow hydrogel filaments are fixed to the two ends of the primary coil of the spring coil body and are disposed inside the structure of the primary coil;

[0008] The diameter of the coil wires in the spring coil body is 0.005mm to 0.1mm; the diameter of the primary coil is 0.2mm to 0.5mm, and the coil wire spacing is 0.05mm to 0.4mm; the diameter of the secondary coil is 0.5mm to 6mm, and the length is 3cm to 50cm; the inner diameter of the hollow hydrogel filament is 30μm to 200μm, the outer diameter is 100μm to 400μm, and the length is 3cm to 50cm.

[0009] Preferably, the spring coil body is made of one or more of platinum-tungsten alloy, nickel-titanium alloy, and platinum; the hollow hydrogel filament is loaded with a drug or growth factor, wherein the drug or growth factor is one or more of vascular endothelial growth factor, endothelial cell growth factor, rapamycin, stromal cell-derived factor-1α, and thrombin.

[0010] The present invention provides a method for preparing a spring coil to reduce the risk of damage to the outer wall of a hemangioma, characterized by comprising the following steps:

[0011] S1. After the spring coil wire is wound and twisted through the first mandrel mold, it is heat-treated and shaped to obtain a primary coil; after annealing, the primary coil is wound and twisted through the second mandrel mold, and heat-treated and shaped to obtain a spring coil body with a secondary coil structure.

[0012] S2. Weld a metal guide wire to one end of the spring coil body, and insert the metal guide wire into a conduit with a diameter slightly larger than that of the primary coil. Under the traction of the metal guide wire, the spring coil body is stretched into the shape of the primary coil inside the conduit. Under a microscope, use tweezers to insert the hollow hydrogel wire into the interior of the primary coil, and use acrylic adhesive to fix the hollow hydrogel wire to both ends of the primary coil. Then push the primary coil out of the conduit to restore the secondary coil structure.

[0013] Preferably, in S1, the first mandrel mold is a stainless steel bar with a diameter of 0.05mm to 1mm, the second mandrel mold is a stainless steel bar with a diameter of 0.5mm to 6mm, and the heat treatment setting temperature is 100℃ to 1000℃ for 10min to 300min.

[0014] Preferably, in S2, the hollow hydrogel filaments are prepared by the following method:

[0015] (1) Dissolve acrylamide and sodium acrylate in water to prepare solution A; dissolve amine crosslinking agent, drug or growth factor in water to prepare solution B;

[0016] (2) Mix solutions A and B, stir well, add photoinitiator to obtain precursor solution C;

[0017] (3) Inject solution C into the double-layered polymerization tube and place it under a UV lamp to carry out photopolymerization reaction;

[0018] (4) After drying the double-layer tube polymer tube in a vacuum drying oven, take out the inner tube with attached hydrogel filaments, immerse it in water for purification, and demold the hydrogel filaments from the inner tube and air dry to obtain hollow hydrogel filaments.

[0019] Preferably, in step (2), the precursor solution C contains acrylamide at a mass concentration of 5% to 50%, sodium acrylate at a mass concentration of 5% to 20%, initiator at a mass concentration of 0.1% to 5%, and amine crosslinking agent at a mass concentration of 0.09% to 2%.

[0020] Preferably, in step (3), the photopolymerization reaction time is 3 min to 15 min; in step (4), the drying temperature is 60℃ to 80℃, the time is 6 to 8 h; the purification time is 24 h to 36 h, the ratio of purified water volume to hollow hydrogel filament length is 8-20 ml / cm; and the air-drying time is 5 h to 10 h.

[0021] Preferably, the photoinitiator is one or more of the following: lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and a derivative of bisphenylphosphine oxide (BAPO); the amine crosslinking agent is N,N-methyleneacrylamide.

[0022] Preferably, the double-layered polymer tube includes an outer tube and an inner tube; the inner tube passes through a small hole at one end of the outer tube and can move freely inside the outer tube or be removed, and the other end of the outer tube is an opening into which a reaction solution can be injected; the inner diameter of the outer tube is 0.3 mm to 1 mm, and the outer diameter of the inner tube is 0.1 mm to 0.4 mm.

[0023] Preferably, the outer tube is made of at least one of polyethylene, polypropylene, polytetrafluoroethylene, and polyurethane; and the inner tube is made of at least one of stainless steel, iron, copper, and tungsten.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The sparse structure design of the primary coil of the spring coil of the present invention reduces the squeezing effect on the outer wall of the hemangioma during the pushing process, thereby reducing the risk of damage to the outer wall.

[0026] 2. The hollow hydrogel filaments inside the primary coil of the spring coil of this invention provide a buffering mechanism, which can buffer the pressure of blood pressure on the outer wall of the aneurysm after the spring coil is placed in the aneurysm. The hollow structure design also allows it to better adapt to changes in hemodynamics, reducing deformation or displacement of the spring coil caused by blood flow impact. Through simulated blood flow impact experiments, the force sensing effect of the spring coil of this invention and the conventional spring coil on the outer wall after placement in an aneurysm model was compared and analyzed. The results show that the spring coil of this invention can significantly reduce the compression effect of blood flow on the aneurysm wall. In addition, under simulated hemodynamic conditions, the morphological stability of the two spring coils after placement was evaluated, and it was found that the spring coil of this invention exhibits excellent shape retention ability and is not easily deformed or displaced even under blood flow impact. These findings confirm the superior performance of the spring coil of this invention in protecting the aneurysm wall from damage and maintaining embolism stability.

[0027] 3. The hollow hydrogel filaments inside the primary coil of the spring coil of the present invention can expand rapidly when exposed to blood, which can provide support for the spring coil body while increasing the volume filling degree, and can prevent the spring coil body from being compacted by blood flow.

[0028] 4. Due to the sparse primary structure of the spring coil of the present invention, the hollow hydrogel filaments are not confined to the group when expanding, resulting in a larger expansion volume. At the same time, the larger diameter hollow hydrogel filaments can play an anti-unwinding role.

[0029] 5. The hollow structure of the spring coil of the present invention is loaded with drugs or growth factors that can promote the proliferation and migration of endothelial cells, which is beneficial to the proliferation and migration of endothelial cells in the aneurysm and rapid endothelialization at the aneurysm wall and neck. Attached Figure Description

[0030] Figure 1 The spring coil prepared according to the present invention.

[0031] Figure 2 This is a diagram showing the loading of hollow hydrogel filaments onto a spring coil according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the double-layer polymer tube structure used in this invention.

[0033] Figure 4 This is a schematic diagram of the spring coil structure obtained by the present invention.

[0034] In the diagram, 1-outer tube, 2-inner tube, 3-small hole, 4-opening, 5-hollow hydrogel filament, 6-first-stage coil, 7-second-stage coil. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] Example 1

[0037] In this embodiment, the coil substrate for reducing the risk of damage to the outer wall of the aneurysm is a platinum-tungsten alloy. Platinum-tungsten alloys have good biocompatibility and excellent compliance, which is crucial for maintaining the shape and adapting the coil within the aneurysm. This ensures the coil's stability within the aneurysm and prevents excessive pressure on the vessel wall. Furthermore, platinum-tungsten alloys can be precisely dimensionally customized, and the coil can be manufactured using precision processes such as winding, heat setting, and annealing. The hollow hydrogel filaments are based on acrylamide-sodium acrylate as a polymer hydrogel filament.

[0038] The specific preparation steps of the hollow hydrogel filaments in this embodiment are as follows:

[0039] (1) A certain mass of acrylamide and sodium acrylate are dissolved in deionized water to prepare solution A; a certain mass of N,N-methyleneacrylamide, drug or growth factor are dissolved in deionized water and mixed evenly to prepare solution B; the drug or growth factor used in this embodiment is vascular endothelial growth factor (VEGF).

[0040] (2) Mix solutions A and B, stir evenly, and then add lithium phenyl (2,4,6-trimethylbenzoyl) phosphate to prepare hydrogel precursor solution C; the mass concentration of acrylamide in precursor solution C is 9%; the mass concentration of sodium acrylate is 6%; the mass concentration of N,N-methyleneacrylamide is 0.18%; and the mass concentration of lithium phenyl (2,4,6-trimethylbenzoyl) phosphate is 0.15%.

[0041] (3) Preparation of hollow hydrogel filaments: The double-layered polymer tube structure used in this invention is as follows: Figure 3 As shown, the device includes an outer tube 1 and an inner tube 2. One end of the outer tube 1 has a small hole 3 for the inner tube to pass through, and the other end has an opening 4. After the inner tube 2 is passed through the small hole 3 at one end of the outer tube 1, solution C is injected into the outer tube of the double-layered tube polymerization tube through the opening 4 using a syringe. Then, it is placed under a UV lamp for photopolymerization reaction for 5 minutes. The double-layered tube polymerization tube is placed in a vacuum drying oven and dried at 60°C for 8 hours to remove water from the hydrogel, obtaining dry hydrogel filaments. The inner tube is removed from the outer tube, and the outer layer of the inner tube is covered with hydrogel. It is then soaked in deionized water for purification for 24 hours, with the ratio of purified water volume to hollow hydrogel filament length being 8 ml / cm, to remove unreacted monomers and demold the hydrogel filaments from the inner tube. The purified hollow hydrogel filaments are then air-dried at room temperature for 6 hours to obtain dry hollow hydrogel filaments.

[0042] In this embodiment, the outer tube of the double-layer polymer tube is made of polytetrafluoroethylene, and the inner tube is made of stainless steel. The inner diameter of the outer tube of the double-layer polymer tube is 0.3 mm, and the outer diameter of the inner tube is 0.1 mm. For ease of operation, the length of the inner tube is 1.5 to 2 times that of the outer tube.

[0043] The preparation steps of the spring coil are as follows:

[0044] S1: Non-degradable platinum-tungsten alloy filaments are wound and twisted using a mandrel 1 mold. The diameter of the platinum-tungsten alloy filaments is 0.01 mm. The mandrel 1 is a stainless steel rod with a diameter of 0.3 mm. The coil spacing is controlled at 0.08 mm. Then, the mandrel 1 and the filaments are placed in a heat treatment furnace with precise temperature control at 800°C for 45 min to obtain a primary coil. After annealing at room temperature, the primary coils are wound and twisted again using a mandrel 2 mold. The mandrel 2 is a stainless steel rod with a diameter of 4 mm. Then, the mandrel 2 and the filaments are heat-set at 750°C for 60 min to prepare a bare spring coil.

[0045] S2: During the secondary coil winding and shaping process, considering that high temperatures may damage the structure of the hollow hydrogel filaments, the hollow hydrogel filaments should be inserted only after the secondary coil shaping is complete. First, a metal guide wire is welded to one side of the bare metal spring coil. Then, the guide wire is inserted into a conduit with a diameter slightly larger than that of the primary coil. By pulling back, the spring coil is straightened into the primary coil shape within the conduit. With the aid of a microscope, tweezers are used to slowly insert the hollow hydrogel filament into the primary coil of the metal spring coil. Finally, acrylate adhesive is used to fix the hollow hydrogel filament to both ends of the primary coil of the spring coil, ensuring a firm bond. Because the secondary structure of the spring coil is heat-set to a 2D shape, it is straight within the conduit due to external force. After loading the hollow hydrogel filament, it can be slowly pushed out of the conduit to restore the 2D secondary structure.

[0046] Figure 1 The spring coil prepared according to the present invention clearly shows that the hydrogel filaments are located inside the primary coil of the spring coil.

[0047] Figure 2 This is a schematic diagram illustrating the process of straightening and conveying hydrogel filaments of the secondary structure of the spring coil via a conduit in step S2 of the present invention. Due to its inherent softness and flexibility, even a small force is sufficient to cause changes in the secondary structure of the spring coil. However, as can be seen from the diagram, the hollow hydrogel filaments of the present invention, due to their small diameter and structural characteristics, do not affect the secondary structure of the spring even when embedded in the primary structure of the spring coil.

[0048] Figure 4 This is a schematic diagram of the spring coil structure obtained by the present invention. The hollow hydrogel filament 5 is located in the primary coil 6 of the spring coil and together they form the secondary coil 7.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A spring coil for reducing the risk of damage to the outer wall of a hemangioma, characterized in that, It includes a spring coil body and hollow hydrogel filaments; the spring coil body has a two-stage coil structure; the two ends of the hollow hydrogel filaments are fixed to the two ends of the first-stage coil of the spring coil body and are disposed inside the structure of the first-stage coil; The diameter of the coil wire in the spring coil body is 0.005mm~0.1mm; the diameter of the primary coil is 0.2mm~0.5mm, and the coil wire spacing is 0.05mm~0.4mm; the diameter of the secondary coil is 0.5mm~6mm, and the length is 3cm~50cm. The hollow hydrogel filaments have an inner diameter of 30μm~200μm, an outer diameter of 100μm~400μm, and a length of 3cm~50cm; The preparation of the spring coil includes the following steps: S1. After the spring coil wire is wound and twisted through the first mandrel mold, it is heat-treated and shaped to obtain a primary coil; after annealing, the primary coil is wound and twisted through the second mandrel mold, and heat-treated and shaped to obtain a spring coil body with a secondary coil structure. S2. Weld a metal guide wire to one end of the spring coil body, insert the metal guide wire into a conduit with a diameter slightly larger than that of the primary coil, and stretch the spring coil body into the shape of the primary coil under the traction of the metal guide wire; under a microscope, use tweezers to insert the hollow hydrogel wire into the interior of the primary coil, fix the hollow hydrogel wire to both ends of the primary coil with acrylic adhesive, and then push the primary coil out of the conduit to restore the secondary coil structure; In S2, the hollow hydrogel filaments are prepared by the following method: (1) Dissolve acrylamide and sodium acrylate in water to prepare solution A; dissolve amine crosslinking agent, drug or growth factor in water to prepare solution B; (2) Mix solutions A and B, stir well, add photoinitiator to obtain precursor solution C; (3) Inject solution C into the double-layered polymerization tube and place it under a UV lamp to carry out the photopolymerization reaction; (4) After drying the double-layer tube polymer tube in a vacuum drying oven, take out the inner tube with attached hydrogel filaments, immerse it in water for purification, and demold the hydrogel filaments from the inner tube and air dry to obtain hollow hydrogel filaments.

2. The spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 1, characterized in that, The spring coil is made of one or more of platinum-tungsten alloy, nickel-titanium alloy, and platinum; the hollow hydrogel filament is loaded with a drug or growth factor, which is one or more of vascular endothelial growth factor, endothelial cell growth factor, rapamycin, stromal cell-derived factor-1α, and thrombin.

3. The spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 1, characterized in that, In S1, the first mandrel mold is a stainless steel bar with a diameter of 0.05mm to 1mm, the second mandrel mold is a stainless steel bar with a diameter of 0.5mm to 6mm, and the heat treatment setting temperature is 100℃ to 1000℃ for 10 min to 300 min.

4. The spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 1, characterized in that, In step (2), the mass concentration of acrylamide in the precursor solution C is 5%~50%, the mass concentration of sodium acrylate is 5%~20%, the mass concentration of the initiator is 0.1%-5%, and the mass concentration of the amine crosslinking agent is 0.09%-2%.

5. A spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 4, characterized in that, In step (3), the photopolymerization reaction time is 3 min to 15 min; in step (4), the drying temperature is 60℃ to 80℃ and the time is 6 to 8 h; the purification time is 24 h to 36 h, the ratio of purified water volume to hollow hydrogel filament length is 8-20 ml / cm; and the air drying time is 5 h to 10 h.

6. The spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 5 is characterized in that the photoinitiator is one or more of the following: lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and a derivative of bisphenylphosphine oxide (BAPO); and the amine crosslinking agent is N,N-methyleneacrylamide.

7. A spring coil for reducing the risk of damage to the outer wall of a hemangioma according to any one of claims 1, characterized in that, The double-layered polymer tube includes an outer tube and an inner tube; the inner tube passes through a small hole at one end of the outer tube and can move freely inside the outer tube or be removed, while the other end of the outer tube is open and can be injected with the reaction liquid; the inner diameter of the outer tube is 0.3mm~1mm, and the outer diameter of the inner tube is 0.1mm~0.4mm.

8. A spring coil for reducing the risk of damage to the outer wall of a hemangioma according to claim 7, characterized in that, The outer tube is made of at least one of polyethylene, polypropylene, polytetrafluoroethylene, and polyurethane; the inner tube is made of at least one of stainless steel, iron, copper, and tungsten.

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