Absorbable coil and absorbable coil system

Abstract

The application discloses an absorbable spring and an absorbable spring system, and relates to the technical field of medical devices, which comprises a linear body with a first shape spiral outer diameter, the linear body comprises a first winding spring and a second winding spring, the wire of the first winding spring is a platinum-tungsten alloy, the wire of the second winding spring is a degradable high-molecular polymer, the diameter of the wire of the first winding spring is 0.02-0.15 mm, and the diameter of the wire of the second winding spring is 0.06-0.3 mm; the second winding spring is consistent with the first winding spring in rotation direction; the interval between two adjacent turns of the second winding spring is 1%-10% of the wire diameter; the linear body is further wound into a spherical or spiral second shape spring ring; when the second shape spring ring is subjected to a 20% deformation variable, the deformation pressure is not greater than 0.6 N. The design balances the stability and flexibility of the second shape structure of the absorbable spring, and effectively reduces the space-occupying effect of the metal spring ring and reduces the artifacts.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an absorbable coil and an absorbable coil system. Background Technology

[0002] Coil embolization is a minimally invasive endovascular interventional technique. Initially used primarily for the interventional treatment of intracranial aneurysms, its application has gradually expanded to the clinical diagnosis and treatment of various peripheral vascular diseases with the development of interventional medical devices and clinical procedures. This procedure involves percutaneous puncture to establish a pathway, precisely delivering and placing embolic coils within the target vessel using a microcatheter. The coils induce in-situ thrombus formation in the target area, occluding the abnormal vascular lesion and ultimately achieving hemostasis and closure of malformed vessels. Currently, in the field of peripheral vascular intervention, coil embolization is widely used in clinical scenarios such as embolization of peripheral arteriovenous malformations, emergency closure of traumatic or pathological vascular bleeding, and occlusion of peripheral aneurysmal lesions.

[0003] Currently, the mainstream embolization products in clinical practice are mainly non-degradable metal coils. For large-volume peripheral vascular lesions, multiple metal coils are usually implanted in batches to achieve dense occlusion of the aneurysm or abnormal vessel. On the one hand, a large number of permanent metal implants remain in the body, significantly increasing the patient's foreign body load; on the other hand, the permanently retained metal foreign bodies occupying the vascular lumen for a long time are prone to continuous compression of surrounding soft tissues and adjacent nerves (space occupancy effect, also known as compression effect, local space occupancy effect, or spatial space occupancy effect; refers to the phenomenon in medical imaging where a lesion in a certain part of the body occupies the space of normal physiological structures, pushing and displacing adjacent structures, or compressing or blocking physiological cavities), increasing the risk of long-term complications such as local pain and tissue inflammation. In addition, when traditional coils are pushed and released at a single point via a catheter, there are common problems such as local accumulation of coils and gaps in the edges of the aneurysm cavity, making it difficult to achieve uniform and dense packing, which further affects the long-term efficacy of embolization. Furthermore, the embolization site often experiences recurrence of other diseases, and surgical diagnosis such as MRI or CT is often required during patient diagnosis or follow-up. The coils previously packed at the embolization site are mainly made of metals such as platinum and tungsten, and the artifacts caused by this seriously affect the operator's further diagnosis of the disease.

[0004] In existing technologies, biodegradable and absorbable materials are being used to replace parts of the main body of metal coils. However, the structural stability challenges of absorbable coils focus on the nonlinear decay of mechanical properties during degradation: mechanical decay and structural integrity face a "window period" challenge; structural integrity decreases over time, and its clinical safety is highly dependent on the dynamic balance between the material degradation rate and the hemodynamic environment. Furthermore, cracking behavior may cause clinical problems: premature failure of mechanical support; cracking, especially macroscopic fracture, can lead to loosening and compression of the overall coil structure, resulting in loss of aneurysm filling and support, increasing the risk of recanalization or recurrence.

[0005] To address the numerous clinical challenges associated with existing permanent metal coils, including high foreign body load, significant long-term complication risk, uneven packing leading to accumulation and gaps, and clinical artifacts, we propose an absorbable coil and absorbable coil system to overcome the inherent defects of existing products and optimize the interventional embolization effect for peripheral vascular lesions. Summary of the Invention

[0006] The purpose of this invention is to provide an absorbable coil and an absorbable coil system to solve the problems existing in the prior art. It can effectively reduce the final occupancy effect of the coil, reduce artifacts, and reduce the long-term recanalization rate. When the embolization reaches a steady state, and even for a short period of time after the embolization reaches a steady state, the absorbable coil still maintains good structural stability. The initial support force of the secondary morphology, together with the mild degradation of the biodegradable material, reduces the inflammatory response in the tumor cyst.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides an absorbable spring coil, comprising a linear body with a primary spiral outer diameter. The linear body includes a first coil and a second coil, the second coil being coaxially sleeved around the first coil and fixed relative to it. The wire of the first coil is a platinum-tungsten alloy, and the wire of the second coil is a biodegradable polymer. The diameter of the first coil wire is 0.02~0.15mm, and the diameter of the second coil wire is 0.06~0.3mm. The second coil has the same helix direction as the first coil. The spacing between two adjacent turns of the second coil is 1%~10% of the wire diameter. The linear body is further wound into a secondary spring coil in the shape of a sphere or a spiral. When the secondary spring coil is subjected to a force and undergoes a 20% deformation, its deformation pressure is no greater than 0.6N.

[0008] On the other hand, the present invention provides an absorbable spring coil, comprising a linear body with a primary spiral outer diameter, the linear body including a first winding spring and a second winding spring, the second winding spring being coaxially sleeved outside the first winding spring and the two being fixed relative to each other, the wire of the first winding spring being a platinum-tungsten alloy, the wire of the second winding spring being a polymer including poly(p-dioxanone), the diameter of the first winding spring wire being 0.02~0.15mm, the diameter of the second winding spring wire being 0.06~0.3mm; the second winding spring having the same helix direction as the first winding spring; the spacing between two adjacent turns of the second winding spring being 1%~10% of the wire diameter; the linear body is further wound into a spherical or spiral secondary spring coil; wherein, when the secondary spring coil is subjected to a force and undergoes a 20% deformation, its deformation pressure is not greater than 0.6N.

[0009] In one embodiment, the second spring wire has a non-crack period and a crack period, wherein the second spring wire in the crack period has a morphology in which cracks appear on one surface before the other surface; or, the second spring wire in the crack period simultaneously has a non-crack surface region and a crack surface region. Further, a single crack forms an angle with the length direction of the second spring wire, and multiple cracks are distributed along the length direction of the second spring wire. Further, during the crack period, the crack surface region of the second spring wire is closer to the first spring than the non-crack surface region.

[0010] In one embodiment, the outer diameter of the first coiled spring is 0.1~0.4mm, the outer diameter of the first-stage spiral is 0.2~1.2mm, and the radial gap between the first coiled spring and the second coiled spring is 0.01~0.3mm.

[0011] In one embodiment, the non-crack period of the second spring wire is less than 120 days.

[0012] In one embodiment, the linear body further includes an additional spacer structure and an anti-unwinding wire; the anti-unwinding wire is disposed inside the first coiled spring and its two ends are respectively fixed to the two ends of the first coiled spring, and the additional spacer structure is fixed to the linear body.

[0013] In one embodiment, the additional spacer structure is a fiber hair, which is fixed to the first coiled spring and its free end is exposed on the outside of the linear body; the fiber hair is evenly distributed along the axial direction of the linear body, and the axial distance between two adjacent fiber hairs is 4-8 mm.

[0014] In one embodiment, the additional occupant structure is a hydrogel coating, which is disposed on the linear body or on the linear body and the anti-unwinding filament.

[0015] In one embodiment, the anti-unwinding filament is made of polypropylene. Further, the diameter of the polypropylene anti-unwinding filament is 0.025~0.05 mm. The present invention also provides an absorbable spring coil system, including a delivery conduit and the above-mentioned absorbable spring coil, wherein the ratio of the outer diameter of the primary spiral to the inner diameter of the delivery conduit is 0.65-0.95.

[0016] In one embodiment, the device further includes a delivery wire and an interlocking mechanism, the interlocking mechanism comprising a first fastener and a second fastener, the first fastener being fixed to the distal end of the delivery wire and the second fastener being fixed to the proximal end of the absorbable spring coil, the first fastener and the second fastener being engaged with each other.

[0017] In one embodiment, an axial pull-out unlocking wire is provided in the first fastener and the second fastener. The axial pull-out unlocking wire is disposed in the inner cavity of the delivery wire. The delivery wire and the interlocking mechanism are both movably disposed in the delivery conduit and can move along the axial direction of the delivery conduit.

[0018] In one embodiment, when a pushing force is applied proximally to the delivery wire to push the absorbable spring coil located within the delivery conduit distally, the pushing resistance is less than or equal to 2N.

[0019] The present invention achieves the following technical effects compared to the prior art: 1. The wire and structural parameters of the absorbable spring coil are comprehensively designed and optimized to balance the stability and flexibility of the secondary structure of the absorbable spring coil. 2. The spacing between two adjacent turns of the second coiled spring is configured to be 1% to 10% of the wire diameter to improve the insufficient pushing performance of the linear body in the delivery conduit caused by the consistent direction of rotation; 3. By aligning the rotation direction of the second coiled spring with that of the first coiled spring, torque coupling between the first and second coiled springs is suppressed, reducing the axial stiffness of the linear body and improving its conformability. 4. A second spring of polydioxanone wire is coaxially sleeved outside the first spring of the platinum-tungsten alloy wire to form a locally degradable and absorbable spring coil of the linear body, which can effectively reduce the occupancy effect of the metal spring coil and reduce artifacts; as the implantation time increases, the second spring is gradually degraded and absorbed, reducing the amount of metal remaining in the body. 5. The wire and structural parameters are comprehensively designed and optimized (the diameter of the platinum-tungsten alloy wire is 0.02~0.15mm, the diameter of the polydioxanone wire is 0.06~0.3mm, the spacing between two adjacent turns of the second coil is configured as 1%~10% of the wire diameter, the deformation pressure of the secondary-shaped spring coil with 20% deformation is not greater than 0.6N, and the direction of rotation is consistent). On the one hand, the structural stability (which can absorb the secondary shape of the spring coil) and the flexibility (which adapts to the shape of the lesion) are balanced. On the other hand, the mild degradation of the polydioxanone wire, together with the small-diameter platinum-tungsten alloy support skeleton that maintains long-term structural integrity, can reduce the inflammatory response in the tumor cyst.

[0020] 6. The ratio of the outer diameter of the absorbable spring coil linear body to the inner diameter of the delivery conduit is optimized to a range of 0.65-0.95, so that it works in conjunction with the spacing parameter between two adjacent turns of the second coiled spring to improve the insufficient pushing performance of the linear body in the delivery conduit. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the absorbable spring coil in an embodiment of the present invention; Figure 2 This is a schematic diagram of the linear main body of the absorbable spring coil in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first and second coiled springs of the linear body in an embodiment of the present invention; Figure 4 This is a partially enlarged schematic diagram of the first and second coiled springs in an embodiment of the present invention; Figure 5 This is a schematic diagram of an absorbable spring coil with a spiral two-stage configuration in an embodiment of the present invention; Figure 6 for Figure 5 A front view schematic diagram of the first winding of the absorbable spring coil; Figure 7 This is a schematic diagram of an absorbable spring coil with a spherical secondary shape in an embodiment of the present invention; Figure 8 for Figure 7 A front view schematic diagram of the first winding of the absorbable spring coil; Figure 9This is a physical image of an absorbable spring coil with a secondary configuration of multiple spherical coils connected in series, as described in an embodiment of the present invention. Figure 10 This is a schematic diagram of an absorbable spring coil system with a delivery conduit in an embodiment of the present invention; Figure 11 This is a schematic diagram of the absorbable spring coil being released in an embodiment of the present invention. Figure 12 This is a schematic diagram of another interlocking mechanism (with an S-shaped contact surface) in an embodiment of the present invention; Figure 13 This is an apparent electron microscope image of the second spring of the PPDO wire on day 30 of the in vitro degradation test in this embodiment of the invention; Figure 14 This is an apparent electron microscope image of the second spring of the PPDO wire on day 67 of the in vitro degradation test in this embodiment of the invention. Figure 1 ; Figure 15 This is an apparent electron microscope image of the second spring of the PPDO wire on day 67 of the in vitro degradation test in this embodiment of the invention. Figure 2 ; Figure 16 This is an apparent electron microscope image of the second spring of the PPDO wire on day 128 of the in vitro degradation test in this embodiment of the invention. Figure 1 ; Figure 17 This is an apparent electron microscope image of the second spring of the PPDO wire on day 128 of the in vitro degradation test in this embodiment of the invention. Figure 2 ; Figure 18 This is an apparent electron microscope image of the second spring of the PPDO wire on day 128 of the in vitro degradation test in this embodiment of the invention. Figure 3 ; Figure 19 The images show the preoperative angiography, post-embolization effects, and coil removal status of the experimental group (absorbable spring) of this invention. Figure 20 The images show the preoperative angiography, post-embolization effect, and coil removal status in the control group (all-metal coils) of this invention. Figure 21 This is a comparison diagram of the thromboembolic effect of the spring coil in the experimental group and the control group of this invention; Figure 22 for Figure 9 Immediate postoperative imaging of an aneurysm with a PPDO absorbable spring in an animal experiment. Figure 23 for Figure 22 Image taken 90 days after an animal experiment; Figure 24 This is a schematic diagram of a method for measuring the deformation pressure of a spring coil.

[0023] In the diagram: 1-First coiled spring, 2-Second coiled spring, 21-Non-cracked surface area, 22-Cracked surface area, 23-Crack array, 231-Transverse crack, 232-Longitudinal crack, 24-Inner side of coiled spring, 25-Outer side of coiled spring, 3-Anti-unwinding wire, 4-Fiber hair, 5-Conveying conduit, 6-Delivery wire, 7-Interlocking mechanism, 71-First fastener, 72-Second fastener, 8-Axial pull-out unlocking wire, 91-Support block, 92-Force sensor, 100-Linear body, 200-Helical secondary absorbable spring coil, 210-First coil, 220-Second coil, 230-Third coil, 300-Spherical secondary absorbable spring coil, 310-First coil, 320-Second coil. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide an absorbable coil and an absorbable coil system to solve the problems existing in the prior art. It can effectively reduce the final occupancy effect of the coil, reduce artifacts, and reduce the long-term recanalization rate. When the embolization reaches a steady state, and even for a short period of time after the embolization reaches a steady state, the absorbable coil still maintains good structural stability. The initial support force of the secondary morphology, together with the mild degradation of the biodegradable material, reduces the inflammatory response in the tumor cyst.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1 like Figures 1-8As shown, an absorbable spring coil includes a linear body 100 with a helical outer diameter of primary shape; the linear body 100 includes a first coiled spring 1 and a second coiled spring 2; the second coiled spring 2 is coaxially sleeved outside the first coiled spring 1 and the two are fixed relative to each other; the wire of the first coiled spring 1 is a platinum-tungsten alloy; the wire of the second coiled spring 2 is a biodegradable polymer, preferably polyglycolic acid (PGA), polylactic acid (PLA), poly-L-lactic acid (PLLA), lactide-co-glycolic acid (PLGA), polycaprolactone (PCL), poly-DL-lactic acid (PDLLA), or polytrimethylene carbonate (PTMC). The spring consists of one or a combination of poly(p-dioxanone) and poly(p-dioxanone) (PPDO); the diameter of the first spring wire is 0.02~0.15mm, and the diameter of the second spring wire is 0.06~0.3mm; the second spring 2 has the same helix direction as the first spring 1; the spacing W between two adjacent turns of the second spring 2 is 1%~10% of the wire diameter; the linear body is further wound into a spherical or helical secondary-shaped spring coil; wherein, when the secondary-shaped spring coil undergoes a 20% deformation under the applied force, its deformation pressure is not greater than 0.6N. It is understood that the local stress field of the composite spring skeleton (based on a non-degradable support skeleton wrapped with a degradable filling material) is more complex than that of a single-material spring (skeleton); when the secondary-shaped structure is under load (e.g., Figure 21When the spring coil (with a thrombus) is loaded, its ability to maintain the stability of the spatial structure is easily affected by the degradation of the biodegradable filling material, making it impossible to maintain the initial shape of the spring coil implanted in the tumor cyst for a long time, resulting in unexpected spatial structure collapse (or shrinkage). Therefore, one can solve the aforementioned problem (i.e., the inability to maintain the initial shape of the spring coil implanted in the tumor cyst for a long time) by optimizing (increasing) the proportion of non-degradable support skeleton material in the linear body 100; or one can improve the axial stiffness of the linear body 100 by reversing the rotation directions of the first and second coils (the torsional tendency of one coil will...). Partially resisting the torsional tendency of the other coil leads to a significant increase in the equivalent axial stiffness of the assembly, greater than the simple sum of the individual stiffnesses of the two coils; ultimately, the assembly behaves like a "harder" one, thus solving the aforementioned problem (i.e., the inability to maintain the initial shape of the spring coil implanted in the tumor cyst for a long time). However, both methods have corresponding drawbacks: the former reduces the proportion of biodegradable material, which contradicts the design intent of the absorbable spring coil; the latter makes the secondary form of the absorbable spring coil overall stiff, which is not conducive to adapting to the cavity shape / morphology of the lesion tumor cyst, causing long-term stimulation of the tumor cyst wall and increasing the probability of inflammatory reactions within the tumor cyst. This invention deploys the second coil in the same direction as the first coil, and further optimizes the spacing parameter W between adjacent turns of the second coil and the radial gap parameter H between the first and second coils; this design achieves a balance between structural stability (of the secondary form of the absorbable spring coil) and flexibility (adaptation to the shape of the lesion) without reducing the proportion of biodegradable material. Compared to all-metal coils, this design, with its locally biodegradable linear body 100, effectively reduces the space-occupying effect of metal coils, minimizes artifacts, reduces the amount of metal remaining in the body, and achieves a better embolization volume for the same size in the long term; in the short term, it has a better ability to form thrombi within the tumor cyst, such as... Figures 19 to 21 As shown, in animal experiments, absorbable springs ( Figure 19 The thrombus-inducing effect within the tumor cyst is better than that of all-metal coils. Figure 20 The thrombus formation within the tumor cyst is more effective. Figure 21 As shown, the number of thrombi on the absorbable spring on the left side of the figure is significantly higher than that on the all-metal spring coil on the right side of the figure.

[0028] The second coil 2 is made of biodegradable material. In the initial stage after the coil is implanted, the second coil 2, together with the first coil 1 and the additional space-occupying structure, provides an immediate space-occupying effect, improving the embolization effect and meeting clinical embolization needs. As the implantation time increases, the second coil 2 is gradually degraded and absorbed, reducing the amount of metal remaining in the body and reducing the final space-occupying effect of the coil, thereby reducing the compression of the implant on surrounding nerves and tissues and reducing the risk of long-term complications. The spacing between two adjacent turns of the second coil 2 is 1% to 10% of the wire diameter, preferably 5%, which also ensures that the coil is evenly distributed after being pushed. The second coil 2 and the first coil 1 have the same rotation direction and are coupled in the same direction. After being pushed to the vascular lesion site, they can better adapt to the shape of the lesion and improve the embolization effect.

[0029] Methods for measuring deformation pressure, such as Figure 24 As shown, the measurement principle is as follows: A spring coil (a spiral two-stage absorbent spring coil 200 or a spherical two-stage absorbent spring coil 300) is compressed, and a force sensor 92 is used to measure the compressive force after the spring coil moves a certain distance. A support block 91 is used to limit the spring coil from retracting after being subjected to pressure, and the force sensor 92 is used to compress the spring coil and record the compressive force value. Measurement steps: Place one side of the spring coil tightly against the support block 91, move the force sensor 92 until the probe just touches the other side of the spring coil, continue to move the force sensor 92 until the moving distance reaches 20% of the spring coil diameter d2 (or d3), and record the peak force during the entire process, which is the deformation pressure.

[0030] In one embodiment, the outer diameter of the first coiled spring is 0.1~0.4mm, the outer diameter D of the first-stage spiral is 0.2~1.2mm, and the radial gap H between the first coiled spring and the second coiled spring is 0.01~0.3mm.

[0031] In one embodiment, the absorbable spring coil provided by the present invention is used for tamping aneurysms, arteriovenous malformations, and arteriovenous fistulas of peripheral blood vessels.

[0032] Example 2 like Figures 1-9 as well as Figures 13-18 As shown, this embodiment provides a polydioxanone absorbable spring coil, comprising a linear body 100 having a primary helical outer diameter D; as Figure 3As shown, the linear body 100 includes a first coiled spring 1 and a second coiled spring 2. The second coiled spring 2 is coaxially sleeved outside (on the side) of the first coiled spring 1 and the two are fixed relative to each other (for example, the distal ends of the two are fixed together on the same spherical end member, and the proximal ends of the two are fixed together on the same second fastener 72). The wire of the first coiled spring 1 is a platinum-tungsten alloy. The second coiled spring 2 is a wire including a polymer core material, which can be poly(p-dioxanone) (PPDO). Poly(p-dioxanone) is also known as poly(oxycarbonylmethyleneoxyethylene). The diameter of the first spring 1 is in the range of 0.02~0.15 mm, preferably one of 0.08 mm, 0.1 mm, or 0.12 mm; the diameter of the second spring 2 is in the range of 0.06~0.3 mm, preferably one of 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.24 mm, or 0.26 mm. The outer side of the polymer core can also be coated with a gelatinizable polymer coating; the polymer coating can be a modified cellulose coating, a natural collagen fiber coating, a sodium alginate coating, or a synthetic acrylamide coating, etc. Both the first spring 1 and the second spring 2 are formed by spirally winding the wire into a cylindrical coil and then undergoing heat setting to fix the cylindrical coil shape; wherein, the heat setting temperature of the second spring 2 is in the range of 75℃~100℃. When preparing the linear body 100 of the absorbable spring coil, the second winding spring 2 has the same helix direction as the first winding spring 1, and the spacing W between two adjacent turns of the second winding spring 2 is 1% to 10% of the wire diameter. When the linear body 100 is further wound into a spherical secondary absorbable spring coil 300 or a helical secondary absorbable spring coil 200, the heat setting temperature range of the first winding spring 1 is 520℃ to 730℃. When the spherical secondary absorbable spring coil 300 or the helical secondary absorbable spring coil 200 undergoes a 20% deformation under applied force, its deformation pressure is no greater than 0.6N. This design comprehensively optimizes the wire and structural parameters of the spring coils (spherical secondary absorbable spring coil 300 or spiral secondary absorbable spring coil 200). On one hand, it balances structural stability (of the absorbable secondary form) with flexibility (adapting to lesion shape). On the other hand, the synergistic effect of the poly(p-dioxanone) wire (offering mild degradation compared to PLGA wire) and the small-diameter platinum-tungsten alloy support framework (maintaining long-term structural integrity) reduces intratumoral inflammatory response. Regarding maintaining long-term secondary structural integrity, such as... Figure 22 and Figure 23 As shown: Compared with the initial morphology of the PPDO absorbable coils in the immediate images of the implanted animal aneurysm, there was no significant change in the secondary morphology / structure of the PPDO absorbable coils 90 days after implantation in the animal aneurysm (the filling structure collapsed or the support space was compressed and collapsed).

[0033] In one embodiment, the second spring (polydioxanone) wire has a non-crack period (e.g. Figures 13-15 (as shown) and cracking stage (as shown) Figures 16-18 As shown), the second spring wire in the cracking stage has an asymmetrical morphology where cracks appear on one side of the surface before the other side (e.g., Figure 16 The second spring wire has a non-cracked surface region 21 and a cracked surface region 22 on its surface. That is, during the cracking stage, the second spring wire simultaneously has both a non-cracked surface region 21 and a cracked surface region 22, which are asymmetrically distributed circumferentially. Furthermore, a single crack (transverse crack 231) forms an angle with the length direction of the second spring wire, and multiple cracks are distributed along the length direction of the second spring wire (i.e., forming a crack array 23). Further, during the cracking stage, the cracked surface region of the second spring wire is closer to the first spring than the non-cracked surface region; that is, the crack array 23 is on the inner side 24 of the spring, rather than on the outer side 25. It is understood that the monomer components of the polymer and the heat-setting temperature can both cause asymmetric cracking morphology as described above. This crack development pattern, which proceeds from the inside (inner side 24 of the coiled spring) to the outside (outer side 25 of the coiled spring), is beneficial for maintaining the integrity of the secondary morphological structure in the long term, preventing premature failure of the mechanical support, and enabling the absorbable spring coil to maintain the integrity of the secondary morphological structure during the period when the embolism reaches a steady state (even within 90 days after the embolism reaches a steady state).

[0034] In one embodiment, the outer diameter of the first coiled spring is 0.1~0.4mm, preferably 0.3mm; the outer diameter of the primary coil is 0.2~1.2mm; the radial gap H between the first and second coiled springs is 0.01~0.3mm, preferably one of 0.02mm, 0.04mm, 0.06mm, 0.08mm, 0.1mm, 0.15mm, 0.2mm, or 0.25mm. It is understood that optimizing the radial gap H parameter can effectively improve the problem of decreased pushing performance of the spring coil in the delivery tube caused by changes in the spacing between adjacent turns of the second coiled spring, and also increase the cavity filling effect of the secondary coiled spring; for the same length, fewer spring coils are used, yet a better plugging density is obtained.

[0035] In one embodiment, the non-crack period of the second spring wire is less than 120 days.

[0036] In one embodiment, the linear body 100 further includes an additional spacer structure 4 and an anti-unwinding wire 3; the anti-unwinding wire 3 is disposed inside the first coiled spring and its two ends are respectively fixed to the two ends of the first coiled spring, and the additional spacer structure 4 is fixed to the linear body. Further, the additional spacer structure 4 is a fiber hair, the fiber hair is fixed to the first coiled spring 1 and its free end is exposed on the outside of the linear body 100; the fiber hair is evenly distributed along the axial direction of the linear body 100, and the axial distance between two adjacent fiber hairs is 4-8 mm.

[0037] In one embodiment, the added spacer structure is either fiber hair 4 or a hydrogel coating. When the added spacer structure is fiber hair 4, the fiber hair 4 is fixed (wound or bonded) to the first coiled spring 1, and the fiber hair 4 protrudes from the gap of the second coiled spring 2, with its free end exposed on the outside of the double-layer spring coil. The fiber hair 4 is made of nylon, polyethylene terephthalate, polypropylene, or polyamide, and can also be animal-derived such as silk protein, collagen, etc., or modified cellulose, bacterial cellulose, alginate, soy protein, alcohol protein, etc., or biodegradable polyurethane, biodegradable polyester, polydioxanone, polyethylene glycol, etc. The fiber hair 4 is evenly distributed along the axial direction of the double-layer spring coil, and the axial distance between two adjacent fiber hairs 4 is 4-8 mm. When the added spacer structure is a hydrogel coating, the hydrogel coating is disposed on the double-layer spring coil, or on the double-layer spring coil and the anti-unwinding fiber 3. The hydrogel coating can be animal-derived, such as silk protein, collagen, and hyaluronic acid; it can also be modified cellulose, pectin, and alginate; or it can be a biodegradable polyester, polydioxanone, or polyethylene glycol structure that swells upon contact with water. The hydrogel coating will swell upon contact with blood or other bodily fluid solvents. Its expansion volume is less than 10% (i.e., the increased volume is less than 10% of the original volume) before 30 minutes, preferably 5%; after complete expansion, the volume is 100%~500% (i.e., the total volume after complete expansion is 100%-500% of the original volume), preferably 200%~400%. Different shaped spring coils exhibit different overall expansion rates after hydrogel expansion, such as 3D shaped spring coils (e.g.,...). Figure 7 and Figure 9 (As shown) Spring coils with an expansion rate of 100%~500% and a 2D shape (such as...) Figure 5 (As shown) The expansion rate is between 50% and 200%. Specifically, in this embodiment, the added occupant structure is fibrous hair 4. Fiber hair 4 helps to increase the occupant effect and is also conducive to the formation of thrombi and cell adhesion growth.

[0038] In one embodiment, the added occupant structure is a hydrogel coating, which is disposed on the linear body 100, or on the linear body 100 and the anti-unwinding filament 3.

[0039] In one embodiment, the anti-unwinding filament 3 is made of polypropylene. Further, the diameter of the polypropylene anti-unwinding filament is 0.025~0.05 mm. Example 3 like Figures 10-12 As shown, this embodiment provides an absorbable coil system, including a delivery catheter 5 and the absorbable coil described in Embodiment 1 or Embodiment 2. The ratio of the outer diameter D of the second coil 2 to the inner diameter D1 of the delivery catheter 5 is 0.65-0.95. By setting the ratio of the outer diameter D of the second coil 2 to the inner diameter D1 of the delivery catheter 5 to 0.65-0.95, the coil can be more stably pushed to the vascular lesion site during delivery. It is understandable that these structural optimizations (e.g., aligning the second coil of the absorbable spring coil with the first coil) and parameters (e.g., further optimizing the spacing parameter W between adjacent turns of the second coil), based on the design objectives of balancing structural stability and flexibility, may introduce new problems to the original system. For example, the absorbable spring coil and the delivery catheter may become incompatible, resulting in decreased delivery performance. However, by setting the ratio of the outer diameter D of the second coil 2 to the inner diameter D1 of the delivery catheter 5 to 0.65-0.95, the spring coil can be more stably delivered to the vascular lesion site during delivery. The matching gap between the second coil 2 and the delivery catheter 5 has a significant impact on delivery: a smaller gap results in less buckling of the linear body 100 and better force transmission; a larger outer diameter D of the second coil 2 makes the linear body 100 softer and more prone to stacking within the delivery catheter 5. Furthermore, the radial gap parameter H between the first and second coils also affects delivery performance.

[0040] It also includes a delivery wire 6 and an interlocking mechanism 7. The interlocking mechanism 7 includes a first fastener 71 and a second fastener 72. The first fastener 71 is fixed to the distal end of the delivery wire 6, and the second fastener 72 is fixed to the proximal end of the double-layer spring coil. The first fastener 71 and the second fastener 72 are interlocked with each other. An axial pull-out unlocking wire 8 is inserted through the first fastener 71 and the second fastener 72. The axial pull-out unlocking wire 8 is disposed in the inner cavity of the delivery wire 6. Both the delivery wire 6 and the interlocking mechanism 7 are movably disposed within the delivery catheter 5 and can move axially along the delivery catheter 5. The delivery wire 6 and the spring coil are axially interlocked by the interlocking mechanism 7. The delivery wire 6 pushes the spring coil through the delivery catheter 5 to the location of the vascular lesion. After the spring coil is removed from the delivery catheter 5, the axial pull-out unlocking wire 8 is pulled outward to release the radial restriction between the first fastener 71 and the second fastener 72. The second fastener 72 radially disengages from the first fastener 71, thereby releasing the spring coil.

[0041] In one embodiment, the present invention provides a peripherally absorbable spring coil system, the system comprising a spring coil with a linear body 100 made of PDO (polydioxanone) biodegradable filament and platinum-tungsten alloy wire; the spring coil is mechanically connected to a delivery wire 6 component assembly; this component is located in a guide sheath (e.g. Figure 10 The delivery catheter (5) is inserted; the coil can embolize blood vessels after being released from the system; the coil includes synthetic fibers for better clotting; the secondary shape of the coil can be divided into two-dimensional structures (e.g., Figure 5 Medium-helical secondary form absorbable spring coil 200) or three-dimensional structure (e.g. Figure 7 A spherical secondary absorbable spring coil 300 is formed. The spring coil and the delivery wire 6 are mechanically connected by an interlocking mechanism 7 to achieve a detachable connection. A platinum-tungsten alloy wire is spirally wound into a slender cylindrical platinum-tungsten spring body, and a biodegradable wire is spirally wound into a hollow slender cylindrical biodegradable spring body. The biodegradable spring body is sleeved on the platinum-tungsten spring body (or the biodegradable spring body is coaxially fitted on the platinum-tungsten spring body) to form a linear body 100. The spiral direction of the biodegradable spring body and the platinum-tungsten spring body of the linear body 100 is consistent. The radial fit gap H between the biodegradable spring body and the platinum-tungsten spring body is 0.01~0.3mm. The outer diameter of the platinum-tungsten spring body is 0.1~0.4mm, and the outer diameter D of the linear body 100 is 0.2~1.2mm. The diameter of the platinum-tungsten alloy wire is 0.02~0.15mm, and the diameter of the biodegradable wire is 0.06~0.3mm.

[0042] In one embodiment, the interlocking mechanism 7 in the peripheral absorbable spring coil system includes a first fastener 71 and a second fastener 72; both the first fastener 71 and the second fastener 72 include through holes disposed on the axis; the axially pull-out unlocking screw 8 can movably pass through the through holes of the first fastener 71 and the second fastener 72 to realize the locked state and the unlocked state of the interlocking mechanism 7.

[0043] In one embodiment, the heat setting temperature range for the biodegradable spring body in the peripheral absorbable spring coil system is 75°C to 100°C.

[0044] In one embodiment, the ratio of the outer diameter D of the linear body 100 in the peripheral absorbable spring coil system to the inner diameter D1 of the guide sheath is 0.65-0.95, preferably 0.7, 0.75, 0.8 or 0.85.

[0045] Taking the commonly used 0.035" coil as an example, the catheter used was a Cordis 5F angiography catheter (0.035" or 0.038" lumen). The outer diameter of the primary coil (outer diameter D of the linear body 100), the appearance before and after push, and the fatigue and push performance after repeated use were tested. The test process is shown in Table 1.

[0046] Table 1 Test Table for Absorbable Spring Coil Push

[0047] In one embodiment, when a pushing force is applied proximally to the delivery wire to push the absorbable spring coil located in the delivery conduit distally, the pushing resistance is less than or equal to 2N. The method for measuring the pushing resistance is as follows: Principle: The pushing resistance of the absorbable spring coil within the matching delivery conduit (or guide tube) is measured using a force measuring device; Fixture: A figure-eight shaped fixture; Measurement steps: First, manually push the absorbable spring coil within the delivery conduit until the head of the spring coil extends approximately 5mm beyond the distal end of the delivery conduit. Then, retract the spring coil 30cm. Clamp the delivery wire using a thrust clamp, with the clamping part 4-5cm from the proximal end of the delivery conduit. Connect the proximal end of the clamp to the force measuring device. Set a speed of 50-500mm / min, then push the spring coil system forward approximately 3cm. Test and record the maximum force during the pushing process as the pushing force.

[0048] The following is a comparative experiment of the absorbable spring coil using the present invention and a conventional metal spring coil.

[0049] The experimental group used the absorbable spring coils of this invention for vascular implantation, such as... Figure 19 As shown in the figure, the left, middle and right sides are the preoperative angiography, the effect after implantation and embolization, and the state of the coil removal, respectively. After embolization with the absorbable coil of the present invention, the blood vessel is completely blocked and no blood flow passes through. The embolization effect of the coil is obvious.

[0050] The control group underwent vascular implantation using conventional metal coils, such as Figure 20 As shown, the left, middle, and right images represent the preoperative angiography, the effect after embolization, and the state after coil removal, respectively. Using conventional metal coils for embolization completely blocked the vessel, preventing blood flow, but the thromboembolic effect was worse compared to the experimental group. Figure 21 As shown, the left image shows the thrombotic effect of an absorbable spring coil, and the right image shows the thrombotic effect of a conventional metal spring coil.

[0051] The (peripheral) absorbable coil provided by this invention has the following clinical advantages: 1. Reducing Clinical Artifacts: In clinical CT / MRI and other medical imaging techniques, the presence of metal implants creates virtual images, typically appearing as radial streaks. This phenomenon can mask actual lesions or produce false positives, hindering diagnosis. Traditional coils are composed of platinum-iridium or other precious metal compositions, which can affect diagnostic results in CT / MRI imaging. Absorbable coils, with a polymer content exceeding 60%, significantly reduce metal usage while achieving the same embolization effect. With the same amount of material, the metal component is reduced by 60%, greatly reducing artifacts in CT / MRI imaging. Compared to traditional platinum-tungsten coils, less metal is used while maintaining the same embolization density. Compared to the 100% metal content of traditional coils, the metal content of the (peripheral) absorbable coil provided by this invention accounts for only 16% (or even lower) of the total implant volume, resulting in fewer artifacts in clinical practice and thus facilitating diagnosis.

[0052] 2. Reduce unexpected space-occupying effects: After coil embolization of lesions, since it is basically a metal structure, it will remain permanently in the relevant lesion location. The permanently existing metal mass may cause physical compression to surrounding tissues (such as nerves); or due to its space-occupying effect, it may affect subsequent treatment.

[0053] 3. Absorbability: The (peripheral) absorbable spring coil provided by this invention has an absorbable volume ratio that is 6 times that of the non-absorbable platinum-tungsten coil, and PDO is gentler on the human body than PLGA.

[0054] 4. Better embolization volume for the same size: The (peripheral) absorbable spring coil provided by this invention, compared with the traditional peripheral detachable fiber-fiber spring coil embolization system products, has a primary coil size that is 0.17mm larger (0.79 vs 0.62). Relatively speaking, for the same length, less spring coil is used, and the embolization density is more advantageous.

[0055] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An absorbable spring coil, comprising a linear body with a first-order helical outer diameter, characterized in that: The linear body includes a first spring and a second spring. The second spring is coaxially sleeved outside the first spring and the two are fixed relative to each other. The wire of the first spring is a platinum-tungsten alloy, and the wire of the second spring is a polymer including poly(p-dioxanone). The diameter of the wire of the first spring is 0.02~0.15mm, and the diameter of the wire of the second spring is 0.06~0.3mm. The second spring has the same helix direction as the first spring. The spacing between two adjacent turns of the second spring is 1%~10% of the wire diameter. The linear body is further wound into a spherical or helical secondary spring coil. When the secondary spring coil is subjected to a force and undergoes a 20% deformation, its deformation pressure is not greater than 0.6N.

2. The absorbable spring coil according to claim 1, characterized in that: The second spring wire has a non-crack period and a crack period. The second spring wire in the crack period has a shape in which cracks appear on one side of the surface before the other side; or, the second spring wire in the crack period has both a non-crack surface area and a crack surface area.

3. The absorbable spring coil according to claim 2, characterized in that: A single crack forms an angle with the length direction of the second spring wire, and multiple cracks are distributed along the length direction of the second spring wire.

4. The absorbable spring coil according to claim 3, characterized in that: During the cracking stage, the cracked surface area of ​​the second spring wire is closer to the first spring than the non-cracked surface area.

5. The absorbable spring coil according to claim 1, characterized in that: The outer diameter of the first coiled spring is 0.1~0.4mm, the outer diameter of the first-stage spiral is 0.2~1.2mm, and the radial gap between the first coiled spring and the second coiled spring is 0.01~0.3mm.

6. The absorbable spring coil according to claim 4, characterized in that: The non-crack period of the second spring wire is less than 120 days.

7. The absorbable spring coil according to claim 1, characterized in that: The linear body also includes an additional spacer structure and an anti-unwinding wire; the anti-unwinding wire is disposed inside the first coiled spring and its two ends are respectively fixed to the two ends of the first coiled spring, and the additional spacer structure is fixed on the linear body.

8. The absorbable spring coil according to claim 7, characterized in that: The added spacer structure is a fiber hair, which is fixed to the first coiled spring and its free end is exposed on the outside of the linear body; the fiber hair is evenly distributed along the axial direction of the linear body, and the axial distance between two adjacent fiber hairs is 4-8mm.

9. The absorbable spring coil according to claim 7, characterized in that: The added occupant structure is a hydrogel coating, which is disposed on the linear body or on the linear body and the anti-unwinding filament.

10. The absorbable spring coil according to claim 7, characterized in that: The anti-unwinding yarn is made of polypropylene.

11. An absorbable spring coil, comprising a linear body having a helical outer diameter of primary shape, characterized in that: The linear body includes a first spring and a second spring. The second spring is coaxially sleeved outside the first spring and the two are fixed relative to each other. The wire of the first spring is a platinum-tungsten alloy, and the wire of the second spring is a biodegradable polymer. The diameter of the wire of the first spring is 0.02~0.15mm, and the diameter of the wire of the second spring is 0.06~0.3mm. The second spring has the same helix direction as the first spring. The spacing between two adjacent turns of the second spring is 1%~10% of the wire diameter. The linear body is further wound into a spherical or helical secondary spring coil. When the secondary spring coil is subjected to a force and undergoes a 20% deformation, its deformation pressure is not greater than 0.6N.

12. An absorbable spring coil system, characterized in that, It includes a delivery conduit and an absorbable spring coil as described in any one of claims 1 to 11, wherein the ratio of the outer diameter of the primary spiral to the inner diameter of the delivery conduit is 0.65-0.

95.

13. The absorbable spring coil system according to claim 12, characterized in that: It also includes a delivery wire and an interlocking mechanism, the interlocking mechanism including a first fastener and a second fastener, the first fastener being fixed to the distal end of the delivery wire and the second fastener being fixed to the proximal end of the absorbable spring coil, the first fastener and the second fastener being interlocked with each other.

14. The absorbable spring coil system according to claim 13, characterized in that: The first fastener and the second fastener are provided with an axial pull-out unlocking wire, which is disposed in the inner cavity of the delivery wire. The delivery wire and the interlocking mechanism are both movably disposed in the delivery conduit and can move along the axial direction of the delivery conduit.

15. The absorbable spring coil system according to claim 13, characterized in that: When a pushing force is applied to the proximal side of the delivery wire to push the absorbable spring coil located in the delivery conduit distally, the pushing resistance is less than or equal to 2N.

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