Cross-superposed vena cava filter screen

Abstract

The invention relates to the field of medical apparatus and instruments, and discloses a crossed and superposed vena cava filter screen, which comprises two crossed filter screens, and each filter screen comprises a connecting piece and more than three groups of interception units circumferentially fixed on the connecting piece at intervals; each intercepting unit comprises two arc-shaped structural rods, the connecting ends of the two arc-shaped structural rods are fixed to the connecting piece, the fixed ends of the two arc-shaped structural rods are fixed to each other, and anchoring structures extending outwards are arranged at the fixed ends. From the connecting end to the fixed end, the distance between the two arc-shaped structural rods is increased and then decreased; and the two arc-shaped structure rods of each group of interception units of one filter screen penetrate through the two adjacent groups of interception units of the other filter screen respectively. The device is long in window period, good in stability, easy to capture and recover and suitable for superior vena cava.

Description

Technical Field

[0001] The present invention relates to an overlapping vena cava filter, belonging to the field of medical devices. Background Art

[0002] The inferior vena cava filter is the only important device for preventing and blocking fatal pulmonary embolism. With the increasing number of cases of lower extremity venous thrombosis found in hospitals, the application scenarios of the filter are becoming more and more extensive. However, the currently widely used retrievable inferior vena cava filters are mainly divided into two types: spindle-shaped and claw-shaped. Each has its own characteristics: The spindle-shaped filter has the advantages of high stability, not easy to deform, and good centering, but the disadvantage is that the window period is short (2-3 weeks), and its barb design makes the retrieval route single, and it can basically only be retrieved from the femoral vein approach. The claw-shaped filter has the advantage of a long window period (3-6 months), but the disadvantages are poor stability, easy to tilt, and the retrieval hooks adhere to the wall, resulting in increased difficulty in capturing during retrieval, not easy to retrieve, and its design only allows retrieval from the jugular vein approach, also having the problem of a single retrieval route.

[0003] With the progress of the times, the development of medical technology and the in-depth understanding of diseases, more and more patients need to use indwelling infusion or chemotherapy, such as cancer patients, patients with severe infections, critically ill patients in the ICU, large surgery patients, dialysis patients, etc., who need to insert PICC, PORT, CVC, dialysis catheters, etc.; and often these patients are the high-risk groups of venous thrombosis and pulmonary embolism. For patients with indwelling catheters inserted from the upper extremities and jugular veins, thrombosis often occurs at the indwelling catheter site, and a superior vena cava filter needs to be inserted to prevent and block fatal pulmonary embolism. At present, there is no truly suitable and dedicated filter for the superior vena cava, and often the inferior vena cava filter is used instead. Among them, many patients cannot insert the filter due to the wide and short superior vena cava or the insufficient length of the pusher rod, losing the chance of saving their lives.

[0004] Currently, existing filter meshes are difficult to simultaneously meet the usage requirements such as "long window period, good stability, easy capture and recovery, and applicable to the superior vena cava". In the prior art, although the prior art (publication number: CN107714237A) discloses a vena cava filter, which realizes the balance and centering in the blood vessel through the first balance part provided on the first balance rod for point contact with the inner wall of the vena cava and the second balance part provided on the second balance rod for point contact with the inner wall of the vena cava, and realizes grasping the blood vessel wall after release through the fixing part provided on the first fixing support rod or / and the second fixing support rod for fixing with the inner wall of the vena cava; that is, a filter with an ideal structure is provided in this patent, which combines the advantages of a cage-shaped (spindle-shaped) filter and an umbrella-shaped filter and overcomes the defects of the two filters. However, compared with the present application, this patent still has the following defects: (1) The length of this filter is similar to or unchanged from the length of the traditional cage-shaped (spindle-shaped) filter, and it cannot adapt to the characteristic of the short length of the superior vena cava blood vessel (generally, a filter such as a spindle shape cannot be inserted into the superior vena cava due to its too long length); (2) The structure is relatively complex. Summary of the Invention

[0005] The present invention aims to provide a cross-overlapped vena cava filter mesh, which can adapt to the characteristic of the short length of the superior vena cava blood vessel and has the advantages of simple structure, good stability, extended window period, two-way placement and retrieval, and easy recovery.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A cross-overlapped vena cava filter mesh includes two cross-overlapped filter meshes. Each filter mesh includes a connecting member and three or more groups of intercepting units circumferentially and spacedly fixed to the connecting member; each group of intercepting units includes two arc-shaped structural rods. The connecting ends of the two arc-shaped structural rods are both fixed to the connecting member, and the fixed ends of the two arc-shaped structural rods are fixed to each other. An anchoring structure extending outward is provided on the fixed ends; from the connecting end to the fixed end, the distance between the two arc-shaped structural rods first becomes smaller and then larger, and then becomes smaller again; the two arc-shaped structural rods of each group of intercepting units of one filter mesh respectively penetrate through two adjacent groups of intercepting units of the other filter mesh.

[0008] Further, a recovery structure is provided on the connecting member.

[0009] Further, a hollow hole is provided on the connecting member.

[0010] Further, the recovery structure is a recovery hook, and the recovery hook is provided around the hollow hole.

[0011] Further, the intercepting unit is made of an elastic material or a material with shape memory properties.

[0012] Further, the intercepting unit is made of nitinol.

[0013] Further, the anchoring structure is a hook or a barb.

[0014] Further, the two filter meshes are coaxially arranged.

[0015] Further, the intercepting units on the connecting member are arranged in a circumferential array.

[0016] Further, the surfaces of the connecting member and the intercepting units are both coated with an anti-thrombosis coating.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. By intersecting and constructing the two filter meshes, the overall axial length of the filter mesh is short, which has obvious advantages for the release scenarios of the superior vena cava and the release between the hepatic vein and the renal vein of the inferior vena cava.

[0019] 2. Compared with the existing filter meshes, the filter mesh of the present invention has fewer anchoring structures. For example, when setting 12 structural rods, there are only 6 fixing hooks, which is much less than the 12 fixing hooks of the traditional spindle-shaped filter mesh, facilitating the extension of the retrieval and placement window period of the filter mesh.

[0020] 3. In the use state, the fixed ends (anchoring structures) of the two filter meshes are respectively located in the two end planes of the entire cross-overlapping inferior vena cava filter mesh, which is beneficial to the centering stability of the entire cross-overlapping inferior vena cava filter mesh.

[0021] 4. The cross-overlapping inferior vena cava filter mesh of the present invention can be retrieved and placed bidirectionally, greatly improving the flexibility of use.

[0022] 5. Through the hollow design of the connecting member and in cooperation with the guide wire, the probability of the cross-overlapping inferior vena cava filter mesh of the present invention being stably centered during release is greatly improved.

[0023] 6. The present invention not only simultaneously has the characteristics of a long window period of the traditional claw-shaped filter mesh (less contact points between the filter mesh and the blood vessel wall of the vena cava) and strong stability of the spindle-shaped filter mesh (the filter mesh has a symmetrical structure, and the anchoring points with the blood vessel wall are distributed in two planes perpendicular to the blood vessel axis), but also shortens the overall axial length of the filter mesh, and can better adapt to the retrieval and placement of the superior vena cava. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic three-dimensional structure diagram of the present invention during release;

[0025] Figure 2 is a schematic top view structure diagram of the present invention during release;

[0026] Figure 3 is a schematic cross-sectional structure diagram of a single filter mesh of the present invention;

[0027] Figure 4 Schematic diagram of the position of the guide wire when the present invention is released;

[0028] Figure 5 Schematic structural diagram when the present invention is retrieved.

[0029] In the figure

[0030] 1. Filter net; 2. Connecting piece; 3. Retrieving hook; 4. Intercepting unit; 5. Arc-shaped structural rod; 6. Anchoring structure; 7. Hollow hole; 8. Guide wire; 9. Limiting structure. Specific implementation mode

[0031] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. For the convenience of description, words such as "upper", "lower", "left", and "right" hereinafter only indicate the same directions as the upper, lower, left, and right directions of the drawings themselves, and do not limit the structure.

[0032] Embodiment 1

[0033] As Figures 1 to 5 shown, a cross-overlapping vena cava filter has the characteristics of stable centering, extended window period, two-way placement and retrieval, high interception rate, easy retrieval, simple structure, etc., and can be used in scenarios with limited release space such as the superior vena cava; the filter includes two coaxially and cross-overlapping filter nets 1, each filter net 1 includes a connecting piece 2 and a retrieval structure fixed at one end of the connecting piece 2, and three or more groups of intercepting units 4 circumferentially and spacedly fixed at the other end of the connecting piece 2. The intercepting units 4 on each connecting piece 2 are circumferentially and evenly spaced or arranged in a circumferential array. The intercepting unit 4 is made of an elastic material or a material with shape memory properties such as nitinol; each group of intercepting units 4 includes two arc-shaped structural rods 5, and the connecting ends of the two arc-shaped structural rods 5 are both fixed to the connecting piece 2, and the fixed ends of the two arc-shaped structural rods 5 are fixed to each other; the fixed end is provided with an outwardly extending anchoring structure 6, and the anchoring structure 6 can adopt structures such as hooks and thorns to facilitate fixing the arc-shaped structural rod 5 to the blood vessel wall; from the connecting end to the fixed end, the distance between the two arc-shaped structural rods 5 changes from small to large and then from large to small; the two arc-shaped structural rods 5 of each group of intercepting units 4 of one filter net 1 respectively penetrate through the adjacent two groups of intercepting units 4 of the other filter net 1.

[0034] It should be noted that: penetrating the interception unit 4 refers to the gap between the two arc-shaped structural rods 5 passing through the interception unit 4. The two arc-shaped structural rods 5 of each group of interception units 4 form a willow-leaf-shaped structure, and each filter 1 is in a free state (not constrained by external forces), along the axial direction of the connecting member 2, the distance between the arc-shaped structural rod 5 and the axis of the connecting member 2 gradually increases, the distance between the connecting end of the arc-shaped structural rod 5 (the end connected to the connecting member 2) and the axis of the connecting member 2 is the smallest, and the distance between the fixed end of the arc-shaped structural rod 5 (the end away from the connecting member 2) and the axis of the connecting member 2 is the largest, that is, the filter 1 presents a flower shape.

[0035] One end of the two arc-shaped structural rods 5 of each group of interception units 4 on a filter screen 1 is respectively fixed to the connector 2 on the filter screen 1, and the other ends are respectively fixed to each other after passing through the adjacent interception units 4 on another filter screen 1. The connector 2 is a hollow structure, that is, a hollow hole 7 for the guide wire 8 to pass through is provided on the connector 2. The recovery structure is a recovery hook 3, which is fixed to the end of the connector 2 and arranged around the hollow hole 7. The recovery hook 3 is symmetrically arranged with respect to the central axis of the connector 2 or the hollow hole 7; the recovery hook 3 is convenient for being hooked and grabbed by the pull rod when the entire filter screen is recovered; the recovery structure can also be designed as any other structure that can facilitate the grabbing of the connector 2. The willow-shaped structure can be formed as follows: a portion of each arc-shaped structural rod 5 close to the connector 2 extends or bends in a direction away from the axis of the connector 2, and a portion of each arc-shaped structural rod 5 away from the connector 2 bends in a direction close to the axis of the connector 2.

[0036] In this embodiment, the material and preparation method of the arc-shaped structural rod 5 are all made of conventional technical means in the field of venous filter technology. The arc-shaped structural rod 5 has good elasticity and is made of superelastic shape memory alloy (such as nickel-titanium alloy); the two ends of an arc-shaped structural rod 5 are fixed to the connector 2 and another arc-shaped structural rod 5 by appropriate connection technology (such as welding, laser welding or plasma welding) or by bonding; the two arc-shaped structural rods 5 can also be fixed head to tail as a whole (in a wide body willow leaf structure), and then fixed to the connector 2; the arc-shaped structural rod 5 can be any slender member with a narrow cross section, including rods, bars, tubes, wires, sheets, etc.

[0037] In this embodiment, the anchoring structure 6 can be a straight structure. When the interception units 4 of the two filter screens 1 are opened to the maximum angle, the straight anchoring structure 6 vertically penetrates into the blood vessel wall; the straight structure facilitates the filter screen to grasp the blood vessel wall when the interception unit 4 is opened. The anchoring structure 6 can also be designed as a hook-shaped structure with a certain curvature, but the curvature must ensure that the anchoring structure 6 can penetrate into the blood vessel wall when the interception unit 4 is opened after the filter screen is released.

[0038] In this embodiment, if Figure 1 and Figure 2As shown, each connecting piece 2 is provided with three groups of intercepting units 4, that is, one group of intercepting units 4 is evenly distributed every 120°. At this time, the whole filter screen has 12 arc-shaped structural rods 5 (6 for each filter net 1) and 6 anchoring structures 6 (3 for each filter net 1). The two filter nets 1 can be divided into filter net A 1 and filter net B 1; the 6 arc-shaped structural rods 5 on filter net A 1 can be divided into A1 arc-shaped structural rod 5, A2 arc-shaped structural rod 5, A3 arc-shaped structural rod 5, A4 arc-shaped structural rod 5, A5 arc-shaped structural rod 5, and A6 arc-shaped structural rod 5. The 6 arc-shaped structural rods 5 on filter net B 1 can be divided into B1 arc-shaped structural rod 5, B2 arc-shaped structural rod 5, B3 arc-shaped structural rod 5, B4 arc-shaped structural rod 5, B5 arc-shaped structural rod 5, and B6 arc-shaped structural rod 5. The overall structure of the filter screen is a claw-shaped structure that corresponds and is the same up and down, and each arc-shaped structural rod 5 intersects with each other; in filter net A 1, A1 arc-shaped structural rod 5 and A2 arc-shaped structural rod 5 form a group of intercepting units 4, presenting a wide-body willow-leaf-shaped structure. The head and the end are connected as a whole, and are outward and downward like a claw-shaped filter screen. A transverse anchoring structure 6 is arranged at the end to fix the filter screen to the blood vessel wall (such as Figure 3 shown); similarly, A3 and A4, A5 and A6 also respectively form a group of intercepting units 4. Filter net B 1 has the same structure as filter net A 1 but in the opposite direction; in filter net B 1, B1 and B2, B3 and B4, B5 and B6 also respectively form a group of intercepting units 4 with a willow-leaf-shaped structure; B1 arc-shaped structural rod 5 passes through A1 and A2, B2 passes through A5 and A6. Similarly, B3 passes through A5 and A6, B4 passes through A3 and A4, B5 passes through A3 and A4, and B6 passes through A1 and A2. After being released, the whole filter screen uses the outward elastic force of the shape of the arc-shaped structural rod 5 itself to open, presenting a flower shape.

[0039] The working principle of the overlapping vena cava filter in this embodiment is as follows:

[0040] When releasing: When the whole filter screen is placed in the catheter (retrieval sheath), the guide wire 8 with the limiting structure 9 is passed through filter net A 1 and filter net B 1. The guide wire 8 itself serves the purpose of stabilizing and centering. The limiting structure 9 ensures that filter net A 1 and filter net B 1 will not separate too much when pushing the filter screen to be released. When the filter screen is completely released into the blood vessel, several intercepting units 4 of filter net A 1 and filter net B 1 are respectively opened by their own outward elastic force, and the anchoring structures 6 are inserted into the blood vessel wall. After the filter screen is fixed in the blood vessel, it plays a role in filtering blood clots; as Figure 2 shown, the area between the dotted line C1 circle and the dotted line C2 circle is the main area for intercepting blood clots.

[0041] During retrieval: The retrieval hook 3 can be grasped from either the jugular vein or the femoral vein. When grasping the B filter net 1, the pull rod in the catheter (retrieval sheath) hooks the retrieval hook 3, and the B filter net 1 is pulled into the catheter. While the retrieval sheath narrows the B filter net 1, due to the cross - structure design of the A filter net 1 and the B filter net 1, the A filter net 1 can also be narrowed simultaneously to facilitate retrieval. Especially when most of the B filter net 1 is slightly tightened after entering the sheath, the anchoring structure 6 at the end of the arc - shaped structural rod 5 of the A filter net 1 automatically detaches from the vein wall and all the arc - shaped structural rods 5 are narrowed (as Figure 5 shown). Until the entire venous filter is pulled into the catheter, and after the venous filter is in a contracted state, the entire catheter together with the venous filter is withdrawn from the blood vessel to complete the retrieval of the venous filter. During retrieval, the retrieval hooks 3 of the A filter net 1 and the B filter net 1 can also be hooked simultaneously in both directions. After all 12 arc - shaped structural rods 5 of the entire filter net are pulled to the narrowed state, then pull the A filter net 1 or the B filter net 1 unidirectionally until the entire filter net is pulled into the catheter and then withdrawn from the blood vessel together.

[0042] In this embodiment, as Figure 4 shown, when the guide wire 8 with the limiting structure 9 passes through the hollow holes 7 of the connectors 2 of the two filter nets 1 successively, the limiting structure 9 abuts against one end of the connector 2 that has passed through first; during release, the limiting structure 9 can not only prevent the two filter nets 1 from separating too far apart, thus further ensuring the complete form of the entire filter net after release, but also play a role in promoting the release of the entire filter net. The limiting structure 9 can be designed as a rotationally symmetric structure centered on the guide wire 8, so as to ensure the uniformity of the thrust exerted by the limiting structure 9 on the filter net during release, and can cooperate with the guide wire 8 to further ensure the complete form of the entire filter net after release.

[0043] In this embodiment, the surfaces of the connector 2 and the interception unit 4 can be coated with an anti - thrombosis coating, such as heparin (or its derivatives), urokinase or PPack (D - phenylalanyl - L - prolyl - L - arginine chloromethyl ketone) to prevent thrombosis formation or any other adverse reactions at the insertion site.

[0044] The beneficial effects of this embodiment are as follows:

[0045] 1. By crossing the two filter nets 1 with each other, the overall axial length of the filter net is shorter, which has obvious advantages for the release scenarios in the superior vena cava and between the hepatic vein and the renal vein in the inferior vena cava.

[0046] 2. Through the hollow design of the connector 2 and the cooperation with the guide wire 8, the probability of the filter net being stably centered during release is greatly improved.

[0047] 3. Compared with the existing filter mesh, the filter mesh of the present invention has fewer anchoring structures 6. For example, by setting 12 arc-shaped structural rods 5, there are only 6 fixing hooks, far fewer than the 12 fixing hooks of the traditional spindle-shaped filter mesh, which is beneficial to extending the taking and placing window period of the filter mesh.

[0048] 4. By constructing the two filter meshes 1 in a two-way superimposed manner, the cross-overlapping inferior vena cava filter of the present invention can be taken and placed in two directions, and the filter mesh can be smoothly retrieved from any direction, greatly improving the flexibility of use.

[0049] 5. The interception net composed of the evenly distributed arc-shaped structural rods 5 (more than 12) of the two filter meshes 1 has an arc-shaped structural rod 5 every 30°, and it is denser towards the center, meeting the thrombus interception requirements and having a high interception rate.

[0050] 6. In the use state, the fixed ends (anchoring structures 6) of the two filter meshes 1 are respectively located in the two end planes of the entire cross-overlapping inferior vena cava filter, which is beneficial to the centering stability of the entire cross-overlapping inferior vena cava filter.

[0051] 7. The present invention not only simultaneously has the characteristics of a long window period of the traditional claw-shaped filter mesh (less contact points between the filter mesh and the inferior vena cava blood vessel wall) and a strong stability of the spindle-shaped filter mesh (the filter mesh has a symmetrical structure, and the anchoring points with the blood vessel wall are distributed in two planes perpendicular to the blood vessel axis), but also shortens the overall axial length of the filter mesh, enabling it to better adapt to the taking and placing of the superior vena cava.

[0052] Embodiment Two

[0053] This embodiment provides a method for using a cross-overlapping inferior vena cava filter. The cross-overlapping inferior vena cava filter is pre-installed in a retrieval sheath, and the method for use includes the following steps:

[0054] When the cross-overlapping inferior vena cava filter is to be released from the retrieval sheath into the blood vessel,

[0055] Thread the guide wire 8 (with a limiting structure 9) through the hollow holes 7 of the connecting members 2 of the two filter meshes 1 in sequence;

[0056] Push the connecting member 2 of one of the filter meshes 1 (by using the limiting structure 9 on the guide wire 8) so that the two filter meshes 1 move from the retrieval sheath to the blood vessel;

[0057] When the two filter meshes 1 enter the blood vessel one after another, several interception units 4 of the two filter meshes 1 are respectively opened by their own outward elastic force and the anchoring structure 6 is inserted into the blood vessel wall. After the filter mesh is fixed in the blood vessel, the release process is completed;

[0058] When the cross-overlapping inferior vena cava filter is to be retrieved from the blood vessel into the retrieval sheath,

[0059] Pull the retrieval structure (retrieval hook 3) of one of the filter meshes 1 (or both filter meshes 1 simultaneously), so that a plurality of interception units 4 of the pulled filter mesh 1 contract and the anchoring structure 6 withdraws from the blood vessel wall; when a plurality of interception units 4 of a certain pulled filter mesh 1 contract, they will drive a plurality of interception units 4 of the other filter mesh 1 to automatically contract and the anchoring structure 6 to automatically withdraw from the blood vessel wall; after the filter meshes are all pulled into the retrieval sheath, the retrieval process is completed.

[0060] The beneficial effects of this embodiment are as follows: By adopting the above method, the release and retrieval of the cross-overlapped vena cava filter can be easily completed, two-way placement and retrieval can be carried out, and the stability is good, which is applicable to scenarios with limited release space such as the superior vena cava.

[0061] The content clarified in the above embodiments should be understood that these embodiments are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. After reading the present invention, various equivalent forms of modification of this embodiment by those skilled in the art all fall within the scope defined by the appended claims of the present invention.

Claims

1. An overlapping vena cava filter, characterized in that, It includes two mutually intersecting filter meshes (1), and each filter mesh (1) includes a connecting member (2) and more than three groups of intercepting units (4) circumferentially and fixedly arranged on the connecting member (2); each group of intercepting units (4) includes two arc-shaped structural rods (5), the connecting ends of the two arc-shaped structural rods (5) are both fixed to the connecting member (2), the fixed ends of the two arc-shaped structural rods (5) are fixed to each other, and an anchoring structure (6) extending outwards is arranged on the fixed ends; from the connecting end to the fixed end, the distance between the two arc-shaped structural rods (5) first becomes smaller and then larger and then smaller again; the two arc-shaped structural rods (5) of each group of intercepting units (4) of one filter mesh (1) respectively penetrate through two adjacent groups of intercepting units (4) of the other filter mesh (1).

2. The overlapping vena cava filter according to claim 1, wherein A recycling structure is arranged on the connecting member (2).

3. The overlapping vena cava filter according to claim 2, wherein, A hollow hole (7) is arranged on the connecting member (2).

4. The overlapping vena cava filter according to claim 3, characterized in that The recycling structure is a recycling hook (3), and the recycling hook (3) is arranged around the hollow hole (7).

5. The overlapping vena cava filter according to claim 1, characterized in that The intercepting unit (4) is made of an elastic material or a material with shape memory properties.

6. The overlapping vena cava filter according to claim 5, characterized in that, The intercepting unit (4) is made of nitinol.

7. The overlapping vena cava filter according to claim 1, wherein The anchoring structure (6) is a hook or a thorn.

8. The overlapping vena cava filter according to any one of claims 1 to 7, characterized in that The two filter meshes (1) are coaxially arranged.

9. The overlapping vena cava filter according to claim 8, wherein, The intercepting units (4) on the connecting member (2) are arranged in a circumferential array.

10. The overlapping vena cava filter according to claim 8, wherein The surfaces of the connecting member (2) and the intercepting unit (4) are both coated with an anti-thrombosis coating.

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