An adaptive vena cava filter

Abstract

The application discloses a self-adaptive vena cava filter, which comprises a supporting assembly and a filter structure connected to the supporting assembly; the supporting assembly comprises a first supporting part and a second supporting part capable of moving close to or away from each other on the same axis; the first supporting part and the second supporting part are connected through an elastic part, and the elastic part is a tensile spring; the filter structure comprises a plurality of construction rods which are uniformly distributed around the axis of the supporting assembly and are in a spiral shape, one end of the construction rod is fixedly connected to the first supporting part, and the other end of the construction rod is fixedly connected to the second supporting part. The application is suitable for use in the superior vena cava and has the characteristics of good stability and easy capture and recovery.

Description

Technical Field

[0001] This invention relates to an adaptive vena cava filter, belonging to the field of medical device technology. Background Technology

[0002] With advancements in medical technology and a deeper understanding of diseases, an increasing number of patients require catheter-based infusions or chemotherapy, such as those with cancer, severe infections, ICU patients, major surgical patients, and dialysis patients. These patients often require PICC lines, PORTs, CVCs, dialysis catheters, etc., and are frequently at high risk for venous thrombosis and pulmonary embolism. In patients with catheters inserted into the upper limbs or jugular veins, thrombosis often occurs at the insertion site, necessitating the placement of a superior vena cava filter to prevent and stop fatal pulmonary embolism. Currently, there is no truly suitable and dedicated superior vena cava filter; inferior vena cava filters are often used as a substitute. However, many patients cannot have their filters inserted due to the width and length of their superior vena cava or the insufficient length of the pusher, thus losing their chance of survival.

[0003] Inferior vena cava (IVC) filters are the only essential device for preventing and stopping fatal pulmonary embolism. Currently, widely used retrievable IVC filters are mainly divided into two types: spindle-shaped IVC filters and claw-shaped IVC filters. Each has its own characteristics. The advantages of spindle-shaped IVC filters are high stability, resistance to deformation, and good centering; the disadvantages are a short window period and a single retrieval route due to their barbed design, which is primarily limited to the femoral vein approach. Claw-shaped IVC filters (see invention patent publication number CN102470028B) have the advantage of a long window period, but the disadvantages are poor stability, a tendency to tilt, and the retrieval hook adhering to the wall, increasing the difficulty of capture during retrieval. Furthermore, their design limits retrieval to the jugular vein approach, also resulting in a single retrieval route. Summary of the Invention

[0004] The present invention aims to address the above-mentioned technical problems by providing an adaptive vena cava filter that has a long window period, good stability, is easy to capture and retrieve, and is suitable for use in the superior vena cava.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An adaptive vein filter includes a support assembly and a filter structure connected to the support assembly; the support assembly includes a first support member and a second support member capable of moving closer to or further away from each other on the same axis; the first support member and the second support member are connected by an elastic element, which is a tension spring; the filter structure includes a plurality of spiral structural rods evenly distributed around the axis of the support assembly, one end of each structural rod being fixedly connected to the first support member, and the other end of each structural rod being fixedly connected to the second support member.

[0007] Therefore, when the first and second supports in the support assembly move away from each other, several structural rods gradually move towards the axis of the support assembly. When the first and second supports reach their maximum distance, the entire venous filter is in a contracted state, and the overall diameter of the filtration structure is at its minimum. The elastic element ensures that the first and second supports always tend to move closer to each other. When the first and second supports move closer, several structural rods are compressed and bent to form the filtration structure, and the entire venous filter is in a released state. The middle part of the structural rods supports the blood vessel wall, and the venous filter can effectively filter thrombi. The structural rods are made of shape memory alloy.

[0008] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows:

[0009] When the venous filter is in the released state, the structural rod has an arched first connecting section and a second connecting section, with a third connecting section between the first and second connecting sections. That is, when the structural rod is projected onto a plane parallel to the axis of the support assembly, the projection of the first connecting section is arched, and the projection of the second connecting section is an inverted arch. This design has the advantage that the filtering structure is formed as a concave structure at the top of the first support and the bottom of the second support, making the entire filtering structure relatively flat, which is highly advantageous for the wide and short superior vena cava. The released state refers to the natural state in which the venous filter is released into the blood vessel, unlike the restricted and confined contracted state of the venous filter within the placement catheter (retrieval sheath).

[0010] Furthermore, both the first and second support members have connecting posts at their outer ends, and these connecting posts are provided with external threads. The external threads are provided to facilitate adjustment of the release position of the venous filter.

[0011] Furthermore, a hook is provided at the outer end of the connecting column. With hooks at both ends of the vein filter, the filter can be released and retrieved via either the jugular vein or the femoral vein, thus expanding the applicability of the vein filter.

[0012] Furthermore, the vein filter also includes a guide cylinder; both the first support member and the second support member are cylindrical structures with one open end, including a cylinder body and an end plate; the cylinder bodies of the first support member and the second support member are slidably sleeved on the guide cylinder. Furthermore, a connecting post is provided on the outer surface of the end plate, and the connecting post is provided with external threads.

[0013] Furthermore, both the first and second support members are provided with a first limiting member, which is located at the end of the first or second support member away from the end plate; the two ends of the guide cylinder are provided with second limiting members corresponding to the first limiting members, and the second limiting members protrude from the outer surface of the guide cylinder. Preferably, the first limiting member is a ring disposed on the inner surface of the cylinder; the second limiting member is a ring disposed on the outer surface of the guide cylinder.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1) The vena cava filter of the present invention comprises several spiral structural rods, which are combined to form a multi-loop overlapping structure, resulting in a higher interception rate than traditional filters.

[0016] 2) The vena cava filter of the present invention adopts a barbless design, which does not directly damage the blood vessel wall, has less contact surface with the vessel wall, and has a longer window period (the time that can be placed in the blood vessel);

[0017] 3) The vena cava filter of the present invention is equipped with hooks at both ends and eliminates the barbed structure in the existing vena cava filter. It can release and retrieve the vena cava filter through two paths: the jugular vein (above the superior vena cava) or the femoral vein (below the inferior vena cava), which improves the applicability of the vena cava filter and also extends the window period.

[0018] 4) The hooks 5 of the vena cava filter of the present invention are all located in the apple-shaped concave structure, the hooks 5 are not easy to stick to the wall, and the hooks 5 are easy to grab when retrieving.

[0019] 5) The vena cava filter of the present invention can control the release degree of the filter structure through the limiting member, so that the structural rod stops when it reaches a certain release degree, avoiding rupture of the blood vessel wall and avoiding excessive bending of the metal rod, which would lead to metal fatigue over a long period of time, thus helping to improve the reliability of the vena cava filter.

[0020] 6) When the superior vena cava filter of the present invention is in the released state, the structural rod 4 is flat and the entire vena cava filter is apple-shaped, which is very advantageous for adapting to the situation where the superior vena cava is wide (large diameter) and short in length. Attached Figure Description

[0021] Figure 1 This is a three-dimensional schematic diagram of the vein filter of the present invention;

[0022] Figure 2 This is a top view of the vein filter of the present invention;

[0023] Figure 3 This is a cross-sectional view of the vein filter of the present invention in the released state;

[0024] Figure 4This is a schematic diagram of the first support component;

[0025] Figure 5 This is a cross-sectional view of the venous filter of the present invention in a contracted state;

[0026] Figure 6 yes Figure 5 Enlarged view of region A in the image;

[0027] Figure 7 This is a schematic diagram of a single structural rod.

[0028] In the figure: 1-Support component; 2-Filter structure; 11-First support member; 12-Second support member; 3-Elastic member; 4-Construction rod; 41-First connecting section; 42-Second connecting section; 43-Third connecting section; 5-Hook; 6-Guide cylinder; 61-Second limiting member; 7-Connecting column; 71-External thread; 1.1-Cylinder body; 1.2-End plate; 1.3-First limiting member. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0030] like Figures 1-7 As shown, the vena cava filter of this embodiment includes a support assembly 1 and a filter structure 2 connected to the support assembly 1. The support assembly 1 includes a first support member 11 and a second support member 12 that can move closer or further apart on the same axis. The first support member 11 and the second support member 12 are connected by an elastic member 3. The filter structure 2 includes a plurality of spiral structural rods 4 that are evenly distributed around the axis of the support assembly 1. One end of the structural rod 4 is connected and fixed to the first support member 11, and the other end of the structural rod 4 is connected and fixed to the second support member 12. The elastic member 3 is disposed inside the first support member 11 and the second support member 12.

[0031] The material and manufacturing method of the structural rod 4 adopt conventional techniques in the field of venous filter technology. The structural rod 4 is made of slender wire with good elasticity. The slender wire is preferably metallic (e.g., corrosion-resistant hairspring alloy), and more preferably a superelastic shape memory alloy (e.g., nickel-titanium alloy). The wire is connected to the first support member 11 and the second support member 12 by appropriate connection techniques (e.g., welding, laser welding, or plasma welding) or by bonding. "Wire" refers to any slender component with a narrow cross-section, including rods, bars, tubes, wires, sheets, etc.

[0032] like Figure 1 , Figure 2 , Figure 3 , Figure 7 As shown, the venous filter is in the released state (expanded state) at this time. In this embodiment, the elastic element 3 is a tension spring, which makes the first support 11 and the second support 12 always tend to move closer to each other. When the first support 11 and the second support 12 move closer to each other to their closest stroke, the bending deformation of several structural rods 4 reaches its maximum (minimum radius of curvature) and forms a filter structure 2 with an apple-like shape. The outer diameter of the entire filter structure 2 reaches its maximum and is supported on the blood vessel wall, effectively filtering and blocking thrombi. The entire structure of the spiral structural rod 4 can play the role of filtering thrombi. The outwardly protruding middle part of the structural rod 4 is used to contact and support the blood vessel wall. Preferably, when the filter structure 2 is in the released state, the structural rod 4 includes an arched first connecting section 41 and a second connecting section 42 arranged opposite to each other, with a third connecting section 43 between the first connecting section 41 and the second connecting section 42. That is, when the structural rod 4 is projected in a plane parallel to the axis of the support assembly, the projection of the first connecting section 41 is arched, and the projection of the second connecting section 42 is an inverted arch, as shown. Figure 7 As shown. The advantages of this design are: the filter structure 2 is formed as a recessed structure at the top of the first support 11 and the bottom of the second support 12. The first connecting sections 41 of several structural rods 4 form the arched top of the filter structure 2, and the second connecting sections 42 of several structural rods 4 form the bottom of the filter structure; when the filter structure 2 is in the released state, both the top of the first support 11 and the bottom of the second support 12 form a recessed structure. The entire filter structure 2 is relatively flat, which is very advantageous for the wide and short superior vena cava. At the same time, the connecting column 7 and the hook 5 mentioned below are both located within the apple-shaped recessed structure, making it less likely for the hook 5 to stick to the wall and easier to catch during retrieval.

[0033] The spiral shape of the structural rod 4 extends from top to bottom, from the first support member 11 to the second support member 12. Preferably, as shown... Figure 2 As shown, a complete structural rod 4 extends spirally downwards from the 0-degree angle position of the first support member 11 to the 180-degree position at the bottom of the second support member 12. That is, the end of the structural rod 4 connecting to the first support member 11 is roughly parallel to the end of the structural rod 4 connecting to the second support member 12. Observing along the axis of the support assembly 1 (the direction of blood flow), adjacent structural rods 4 overlap, making the distribution of structural rods 4 in the entire filter structure 2 more uniform and dense, which is beneficial to improving the filtration effect.

[0034] like Figure 5As shown, the venous filter is in a contracted state (in the state of the filter placement catheter); the first support member 11 and the second support member 12 in the support assembly 1 are far apart from each other, and several structural rods 4 wrapped around the support assembly 1 will move closer to the axis of the support assembly 1.

[0035] Furthermore, the vein filter also includes a guide cylinder 6; the first support member 11 and the second support member 12 are both cylindrical structures with one open end. Each of the first support member 11 and the second support member 12 includes a cylinder body 1.1 and an end plate 1.2. The cylinder bodies 1.1 of the first support member 11 and the second support member 12 are slidably sleeved on the guide cylinder 6. The first support member 11 and the second support member 12 can slide along the guide cylinder 6 under the action of the elastic member 3, which penetrates the guide cylinder 6. To prevent the first support member 11 and the second support member 12 from rotating relative to the guide cylinder 6, a sliding guide structure (not shown) is provided on the guide cylinder 6. The sliding guide structure can be a guide rail and / or a guide groove that cooperates with the first support member 11 or the second support member 12.

[0036] Both the first support member 11 and the second support member 12 have connecting posts 7 at their outer ends. The connecting posts 7 are fixedly mounted on the outer surface of the end plate 1.2, and have external threads 71. The outer ends of the connecting posts 7 also have hooks 5. The external threads 71 ​​on the connecting posts 7 facilitate accurate release of the venous filter. When the venous filter is inside the placement catheter (not shown), the push rod (not shown) inside the placement catheter is threadedly connected to the connecting post 7. The push rod pushes the venous filter into the blood vessel for release. If the position after release is unsatisfactory, the push rod can be used to pull the venous filter back into the placement catheter for re-release until the venous filter is released to a satisfactory position. Then, the push rod is rotated to disconnect the threaded connection between the push rod and the connecting post 7. In this embodiment, the venous filter has hooks 5 at both ends, eliminating the barbed structure found in existing venous filters. The venous filter can be released and retrieved via either the jugular vein or the femoral vein, improving the applicability of the venous filter and extending the window period.

[0037] To prevent excessive stretching and contraction of the first support member 11 and the second support member 12 from damaging the structural rod 4, both the first support member 11 and the second support member 12 are provided with a first limiting member 1.3, which is located at the end of the first support member 11 or the second support member 12 away from the end plate 1.2; the guide cylinder 6 is provided with second limiting members 61 at both ends, which protrude from the outer surface of the guide cylinder 6. Preferably, the first limiting member 1.3 is a ring provided on the inner surface of the cylinder body 1.1; the second limiting member 61 is a ring provided on the outer surface of the guide cylinder 6.

[0038] like Figure 5The venous filter is located inside the placement catheter (not shown, also known as the recovery sheath). Under the constraint of the placement catheter, the structural rod 4 causes the first support member 11 and the second support member 12 to tend to move towards the end of the guide cylinder 6, overcoming the elastic force of the elastic member 3. This tends to increase the distance between the first support member 11 and the second support member 12. However, if the distance between the first support member 11 and the second support member 12 is too large, it can easily damage the structural rod 4, affecting the structural stability of the venous filter. When the first support member 11 and the second support member 12 move away from each other until the first limiting member 1.3 and the second limiting member 61 abut against each other, the distance between the first support member 11 and the second support member 12 reaches its maximum, and the overall diameter of the filter structure 2 reaches its minimum. Therefore, the extreme position of the stretching of the structural rod 4 can be controlled by designing and adjusting the position and size of the first limiting member 1.3 and the second limiting member 61, preventing the filter structure 2 from disintegrating.

[0039] When the filter is released into the blood vessel, the first support member 11 and the second support member 12 slide along the guide cylinder 6 under the elastic force of the elastic member 3. The distance between them continuously decreases, and the overall diameter of the filter structure 2 continuously increases. To prevent the blood vessel wall from being ruptured by the filter structure 2, the dimensions of the first support member 11, the second support member 12, and the guide cylinder 6 can be designed. In the first case, such as... Figure 3 , Figure 5 As shown, the length L of the guide cylinder 6 satisfies the following relationship with the length L1 of the first support member 11 and the length L2 of the second support member 12: L ≥ L1 + L2. In this case, when the end plates 1.2 of the first support member 11 and the second support member 12 abut against the ends of the guide cylinder 6, the distance between the first support member 11 and the second support member 12 is minimal, and the overall diameter of the filter structure 2 reaches its maximum. In the second case (not shown), the length L of the guide cylinder 6 satisfies the following relationship with the following relationship: L < L1 + L2. In this case, when the first support member 11 and the second support member 12 abut against each other, the distance between the first support member 11 and the second support member 12 is zero, and the overall diameter of the filter structure 2 reaches its maximum. Therefore, a filter of appropriate size can be selected according to the user's blood vessel size to avoid damaging the blood vessels. It should be noted that when the venous filter is released into the blood vessel, the distance between the first support member 11 and the second support member 12 does not necessarily reach the limit position. The filter structure 2 adapts to the blood vessel wall, and when the binding force provided by the blood vessel wall is equal to the elastic force of the elastic member, the diameter of the filter structure 2 will not expand further, but will just adapt to the size of the blood vessel.

[0040] The working principle of the adaptive vein filter in this embodiment is as follows.

[0041] Release process of the venous filter: When the venous filter is placed in the catheter, the push rod (not shown) inside the catheter is threadedly connected to the connecting post 7. The push rod pushes the venous filter into the blood vessel for release. If the position after release is not satisfactory, the push rod can be used to pull the venous filter back into the catheter for release again. This process continues until the venous filter is released to a satisfactory position. Then, the push rod is rotated to disconnect the threaded connection between the push rod and the connecting post 7. Once the venous filter is released into the blood vessel, the first support member 11 and the second support member 12 move closer together under the pull of the elastic member 3. Several structural rods 4 are compressed and undergo elastic deformation, forming an apple-shaped filter structure 2. The entire venous filter is in the released state, and the filter structure 2 adheres to the blood vessel wall, maintaining relative fixation to the blood vessel, thereby filtering blood clots.

[0042] The retrieval process of the venous filter: After the thrombus in the blood vessel is removed by relevant measures, the venous filter needs to be removed from the blood vessel; using the lever in the placement catheter (retrieval sheath) to hook hook 5, the venous filter is pulled into the placement catheter. The structural lever 4 tends to straighten under the constraint of the placement catheter opening. During the straightening process of the structural lever 4, it will overcome the elastic force of the elastic element 3 until the entire venous filter is pulled into the placement catheter, so that the venous filter is in a contracted state (e.g., Figure 4 (As shown in the diagram), the entire placement catheter, along with the venous filter, is pulled out of the blood vessel, completing the venous filter retrieval.

[0043] It should be noted that: an independent guide cylinder 6 is provided in the above embodiment. However, those skilled in the art will understand that the guide cylinder 6 in the above embodiment can also be removed, or the guide cylinder 6 and the first support member 11 (or the second support member 12) can be fixed together, and the purpose of the present invention can still be achieved, as long as the elastic member 3 can be used to control the distance between the first support member 11 and the second support member 12.

[0044] The embodiments of the present invention have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention is not limited to the specific embodiments described above; these embodiments are merely illustrative and not limiting. Those skilled in the art, under the guidance of the present invention, can make many modifications without departing from the spirit and scope of the claims, and all such modifications fall within the scope of protection of the present invention.

Claims

1. An adaptive vena cava filter, comprising a support assembly (1) and a filter structure (2) connected to the support assembly (1); the support assembly (1) includes a first support member (11) and a second support member (12) capable of moving closer or further apart on the same axis; the first support member (11) and the second support member (12) are connected by an elastic member (3), the elastic member (3) being a tension spring, the elastic member causing the first support member (11) and the second support member (12) to tend to move closer together; the filter structure (2) includes a plurality of spiral structural rods (4) evenly distributed around the axis of the support assembly (1), one end of the structural rod (4) being fixedly connected to the first support member (11), and the other end of the structural rod (4) being fixedly connected to the second support member (12); When the vein filter is in the released state, the structural rod (4) has an arched first connecting section (41) and a second connecting section (42), and a third connecting section (43) between the first connecting section (41) and the second connecting section (42). The filter structure is formed as a recessed structure at the top of the first support member (11) and the bottom of the second support member (12), so that the entire filter structure is flat. The vein filter also includes a guide cylinder (6); the first support member (11) and the second support member (12) are both cylindrical structures with one end open, including a cylinder body (1.1) and an end plate (1.2); the cylinder body (1.1) of the first support member (11) and the second support member (12) are respectively slidably sleeved on the guide cylinder (6); the elastic member (3) passes through the guide cylinder (6). The first support member (11) and the second support member (12) are both provided with a first limiting member (1.3). The first limiting member (1.3) is located at the end of the first support member (11) or the second support member (12) away from the end plate (1.2). The two ends of the guide cylinder (6) are provided with a second limiting member (61) corresponding to the first limiting member (1.3). The second limiting member (61) protrudes from the outer surface of the guide cylinder (6).

2. The adaptive vena cava filter according to claim 1, characterized in that, The structural rod (4) extends spirally from the 0-degree position of the first support member (11) to the 180-degree position of the second support member (12).

3. The adaptive vena cava filter according to claim 1, characterized in that, The first support member (11) and the second support member (12) are both provided with connecting posts (7) at their outer ends, and the connecting posts (7) are provided with external threads (71).

4. The adaptive vena cava filter according to claim 3, characterized in that, The outer end of the connecting column (7) is also provided with a hook (5).

5. The adaptive vena cava filter according to claim 1, characterized in that, The first limiting member (1.3) is a ring disposed on the inner surface of the cylinder (1.1); the second limiting member (61) is a ring disposed on the outer surface of the guide cylinder (6).

6. The adaptive vena cava filter according to claim 1, characterized in that, The structural rod (4) is made of shape memory alloy.

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