Thrombectomy device

Abstract

The invention relates to a thrombectomy device having a substantially cylindrical structure (1) with a proximal end and a distal end and having a multiplicity of meshes (3, 4) composed of struts, with two connecting struts (5, 5') arranged in the proximal meshes at the proximal end of the cylindrical structure (1) and extending in a proximal direction, and a coupling element (11) arranged proximally relative to the cylindrical structure (1) and to which the connecting struts (5, 5') are connected, wherein the coupling element (11) is connected to an insertion wire, wherein the proximal mesh struts, the connecting struts (5, 5') and the coupling element (11) and, optionally, the reinforcing struts (9), arranged between the proximal meshes, form a closed annular structure (6).and the annular structure (6) comprises a ring marker (12) with a radiopaque material for identifying the spatial position of the annular structure (6). The invention allows visualization of the opening behavior of the thrombectomy device upon release from a catheter, and also the orientation of the device within the blood vessel.

Description

[0001] The invention relates to a thrombectomy device with improved marking of the proximal area. The thrombectomy device comprises a substantially cylindrical structure, the proximal end of which is connected to a coupling element via connecting struts. The thrombectomy device is particularly intended for removing thrombi in the cerebral vascular system.

[0002] Thromboembolic diseases such as myocardial infarction, pulmonary embolism, peripheral thrombosis, organ embolism, etc., are typically triggered by a thromboembolus (hereinafter referred to as a thrombus), a viscoelastic blood clot composed of platelets, fibrinogen, clotting factors, etc., which lodges in a blood vessel and partially or completely obstructs it. The occlusion of organ arteries leads to an interruption of the supply of oxygen and nutrients to the dependent tissue. The disruption of functional metabolism with loss of function is followed within a short time by the cessation of structural metabolism and the death of the affected tissue (infarction). The most frequently affected organs in humans are the heart and the brain. However, such changes also affect the arteries of the extremities and the pulmonary arteries. Venous thromboses and thromboembolic occlusions also occur frequently in the leg and pelvic veins.The clinical picture of a thrombotic occlusion of an intracranial sinus can lead to severe cerebral hemorrhages due to the disruption of venous drainage of the brain tissue.

[0003] Given the severity of the illnesses caused by thromboembolism and the frequency of these diseases, various techniques for dissolving or removing thrombi are known.

[0004] In addition to treatment with thrombolytic agents to dissolve the thrombus on the one hand and open surgical procedures to remove the thrombus on the other, microinvasive endovascular therapies are increasingly being used.

[0005] One of these known treatment methods involves the use of a so-called thrombectomy device. WO 2012 / 156069 A1 describes such a thrombectomy device with a cylindrical structure containing a multitude of meshes, similar to those found in vascular stents. The cylindrical structure, which is essentially a known stent structure, comprises two connecting struts that terminate in a coupling element. This coupling element is connected to a deliverer wire, allowing for precise placement of the thrombectomy device at the treatment site. The coupling element is located at the proximal end of the device and connects it to the distal end of the deliverer wire. US10292803 B2, US9669113 B1, KR 20200133754 A, US2015 / 289892 A, US2007 / 191924 A1, and EP2600795 B1 disclose prior art devices.

[0006] The known thrombectomy device has a slot that extends in a helical or spiral shape across the outer surface of the cylindrical, tubular structure. Such a thrombectomy device can be manufactured from a tube, particularly by laser cutting; however, alternative manufacturing methods are possible, for example, using interwoven filaments or wires.

[0007] The outer surface of the cylindrical structure remains open in the area of ​​the slot, allowing the diameter of the cylindrical structure to adapt to some extent to the diameter at the treatment site, the lumen of the vessel.

[0008] To spatially fix the cylindrical structure with a slot and simultaneously impart a degree of tension, a tensioning bracket or strut extends across the slot at the proximal end of the cylindrical structure. This creates a structure that is closed around its entire circumference, while the cylindrical structure exhibits a helical slot further distally. The tensioning bracket increases the radial force of the cylindrical structure in the proximal region and also serves to hold the opposing edges of the slot in position.

[0009] Where the term "proximal" is used in connection with the invention, it refers to the end of the device that points towards the person treating the patient when the device is inserted into the patient's body. The term "distal," on the other hand, refers to the end of the device that points away from the person treating the patient.

[0010] The proximal region of the known slotted thrombectomy device forms a closed, ring-shaped structure extending from the tensioning bracket, through the struts of the proximal meshes and the connecting struts, to the coupling element. Such a closed, ring-shaped structure can also be achieved at the proximal end without a slot; however, in this case, a tensioning bracket spanning the slot is not required. The ring-shaped structure is inclined or oblique to the longitudinal axis of the cylindrical structure; in other words, the (approximate) plane formed by the ring-shaped structure lies diagonally to the longitudinal axis of the cylindrical structure and extends from proximal to distal.

[0011] For the best possible functionality of the thrombectomy device, it is of utmost importance that the ring-shaped structure opens sufficiently wide at the treatment site and does not contract, or at least not disproportionately, during the withdrawal of the device.

[0012] Successful thrombus removal with the device is only possible with a sufficiently wide opening at the proximal end. Therefore, a device that allows the practitioner to assess the three-dimensional state of the proximal ring-shaped structure during the intervention would be desirable. Such an assessment is crucial for treatment success both during insertion and withdrawal of the thrombectomy device.

[0013] Radiopaque markers can be helpful in assessing the procedure during intervention. Such markers have long been used in the field of medical implants and devices, for example, stents and catheter balloons. These markers are typically placed at specific points and mark, for example, the proximal and distal ends of a stent or catheter, or specific areas of a stent or catheter such as the fenestration in the case of bifurcation implants.

[0014] However, the known markers are unsuitable for the necessary assessment of the opening behavior or the opening of the proximal ring-shaped structure of the thrombectomy device, as their placement at a single point provides insufficient information about the spatial state of the ring structure. Furthermore, known markers can negatively affect the functionality necessary for thrombus removal, namely the shear forces of the device.

[0015] Since the proximal section of the thrombectomy device plays a crucial role in the successful removal of the thrombus, precise information about the opening state of the ring structure during each step of the intervention is extremely important. Successful removal of the thrombus from the vessel depends significantly on the device, and especially the proximal ring structure, adhering optimally to the vessel wall, as this is the only way to effectively detach the thrombus from the vessel wall.

[0016] The object of the present invention is therefore to provide a thrombectomy device with a radiopaque marking, wherein the radiopaque marking enables the treating person to assess the three-dimensional condition, in particular of the proximal ring structure, during the intervention, without restricting the functionality of the device.

[0017] This problem is solved according to the invention by a thrombectomy device with a substantially cylindrical structure having a proximal and a distal end, which has a plurality of meshes which are composed of struts, wherein the thrombectomy device further comprises two connecting struts which are arranged on proximal meshes at the proximal end of the cylindrical structure and extend proximally, and a coupling element arranged proximally to the cylindrical structure, to which the connecting struts are connected, wherein the coupling element is connected to an insertion wire, wherein struts of the proximal meshes, the connecting struts and the coupling element as well as optionallyTension struts arranged between the proximal meshes form a closed, ring-shaped structure, and the ring-shaped structure includes a ring marker made of an X-ray-proof material to indicate the spatial location of the ring-shaped structure.

[0018] The thrombectomy device according to the invention comprises a substantially cylindrical structure with a proximal and a distal end, wherein the cylindrical structure is formed by a plurality of meshes. The cylindrical structure essentially corresponds to that of a typical stent; however, the thrombectomy device serves a different purpose.

[0019] The essentially cylindrical structure of the thrombectomy device has a plurality of openings distributed over its surface, which, according to the invention, are referred to as meshes. In other words, it is a grid or mesh structure composed of struts, resulting in a plurality of openings or meshes on the surface of the cylindrical base structure. Further areas of the thrombectomy device, in particular a proximal section adjoining the cylindrical structure, can also have a grid structure with openings composed of struts, wherein the diameter of the proximal section generally decreases in the proximal direction, meaning that the proximal section is not cylindrical.

[0020] At the proximal end of the cylindrical structure, two connecting struts are arranged on (usually separate) meshes. The connecting struts terminate in a coupling element to which an insertion wire for device placement is attached. A proximal marker may be provided in the region of the coupling element. A distal marker may be provided at the distal end of the device. The proximal and distal markers may comprise known radiopaque materials, as will be described below.

[0021] A release point may be provided at the coupling element or in the area of ​​the introducer wire to allow for detachment of the cylindrical structure if necessary. However, since a thrombectomy device is intended to be removed from the blood vessel system to remove the thrombus, a release point is not strictly necessary; rather, it serves only to facilitate detachment in the event that the thrombectomy device cannot be withdrawn. The release point may, for example, be an electrolytically corrosive system that allows the cylindrical structure to be detached from an introducer wire. Other release mechanisms are known to those skilled in the art, such as mechanical, thermal, or chemical mechanisms.

[0022] Optionally, a slot can extend helically across the cylindrical surface. In this case, a tension strut, which can also be called a tension bracket, spans the slot at the proximal end of the cylindrical structure.

[0023] At least some of the struts of the proximal meshes, the connecting struts, and the coupling element together form a closed ring structure. The ring-shaped structure is thus formed by the corresponding struts of the proximal meshes, the connecting struts, and the coupling element.

[0024] If the thrombectomy device has a slot, the tension strut or struts spanning the slot at the proximal end of the cylindrical structure are also part of the ring-shaped structure; i.e., the tension strut, some struts of the proximal meshes, the connecting struts, and the coupling element together form the closed ring-shaped structure.

[0025] According to the invention, this ring-shaped structure comprises at least one ring marker, which is provided on the ring-shaped structure in such a way that the marker can indicate the spatial position or extent of the ring-shaped structure during the intervention and thus allow the user to assess the opening state of the ring-shaped structure. To distinguish the marker of the ring-shaped structure from other distal and proximal markers, the ring marker is hereinafter referred to as the "ring marker." Since the ring-shaped structure normally extends diagonally through the lumen of the blood vessel, the ring marker also allows the treating physician to visualize the orientation of the thrombectomy device about its longitudinal axis.

[0026] In a preferred embodiment, the ring marker comprises a radiopaque material, for example gold, platinum, palladium, tantalum, or corresponding combinations based on precious metals or possible alloys and combinations such as platinum-iridium. These radiopaque materials can also be used for other markers of the thrombectomy device.

[0027] Preferably, the ring marker is wire-shaped. Furthermore, preferably, the ring marker is provided in one piece, i.e., it comprises a continuous wire.

[0028] The wire itself can comprise a plurality of individual strands that are, for example, twisted, braided, wound, or otherwise connected. According to the invention, the wire can therefore also be a stranded wire. A ring marker made of a continuous wire is understood, according to the invention, to be such that the wire or the ring marker is not interrupted along its length.

[0029] Preferably, the wire-shaped ring marker is wound around the struts that form the ring-shaped structure. Alternatively, the ring marker can also be provided only on one side of the ring-shaped structure, for example on the inside or the outside, or it can wind around the ring-shaped structure in only one or a few turns.

[0030] Ideally, the ring marker encircles the ring-shaped structure along its entire length, i.e., starting, for example, from the coupling element or from a proximal marker, via the first connecting strut and the struts of the proximal meshes to the tension strut, if present, and then back via the struts of the proximal meshes and the second connecting strut to the coupling element or to the proximal marker.

[0031] The ends of the ring marker are preferably fixed in the proximal marker or the coupling element.

[0032] In alternative embodiments, the arrangement of the ring marker can also be limited to only one or more sub-areas of the ring-shaped structure, for example, to the tension strut and / or the connecting struts and / or the struts of the proximal meshes. Even in this case, however, the ring marker should mark the ring-shaped structure sufficiently to allow its unfolding and orientation to be derived as a whole from visualization using appropriate imaging techniques.

[0033] Accordingly, it is also conceivable that the ring marker is composed of a plurality of individual ring marker elements.

[0034] Besides the shape of a wire, the ring marker and ring marker elements can also take on other shapes and, for example, be spiral-shaped, tubular or sleeve-shaped.

[0035] In further embodiments, the additional placement of markers along the cylindrical structure, for example in the central region, is provided. These markers can also be continuous or composed of marker elements and can be, for example, wire-shaped, spiral-shaped, tubular, or sleeve-shaped.

[0036] The cross-section of the wire-shaped ring marker and the other markers is preferably round, but embodiments with an oval or angular wire are also conceivable.

[0037] Preferably the wire has a diameter of 0.01 to 0.5 mm or an edge length of 0.01 to 0.5 mm.

[0038] The ring marker or ring marker elements, as well as the marker or marker elements, are attached using known methods, in particular by welding (for example by a laser), crimping, clamping or gluing.

[0039] In addition to the markers mentioned above, a further development of the invention envisions the additional marking of at least parts of the cylindrical structure, for example, the proximal, distal, or middle region, by coating it with radiopaque materials. The materials suitable for such a coating essentially correspond to the materials, alloys, and combinations previously identified as suitable for the other markers. A gold coating, for example, is possible.

[0040] A thrombectomy device according to the invention can be designed in various ways. The underlying concept of attaching a ring marker along the proximal ring-shaped structure can easily be transferred to similar devices.

[0041] The tension strut can be attached to the cylindrical structure afterwards, but the tension strut can also be part of the structure itself and, for example, be cut from a tube together with it.

[0042] The proximal brace, in the form of a tension strut, improves the radial force distribution of the cylindrical structure in the proximal region. In particular, the brace reduces the thinning of the cylindrical structure and the tensile stress that occurs during insertion into the catheter. Simultaneously, it achieves an additional peeling effect, similar to that exerted by the mesh and edges of the cylindrical structure.

[0043] Of particular importance, however, is the improvement in clamping force in the proximal region, which enables optimal adaptation of the cylindrical structure to the vessel lumen. At the same time, the areas of the cylindrical structure separated by the slot are prevented from shifting relative to each other.

[0044] To allow for easy insertion of the cylindrical structure with the tensioning strut into the catheter, the curvature of the tensioning strut is designed so that its maximum point faces the distal end of the cylindrical structure. This means that the arc of the tensioning strut is closed distally, while proximally, together with the connecting struts and struts of the proximal meshes, it forms a ring-shaped structure that converges in the coupling element.

[0045] Alternatively, the tension strut spans the slot of the cylindrical structure in a wave-like pattern, such that the tension strut follows the edge of the mesh structure on one side of the slot and continues it to the other side. According to one embodiment, the cylindrical structure according to the invention can be closed at its distal end by a mesh structure, so that thrombotic material collects therein as in a collection basket.

[0046] The mesh structure of the cylindrical device can be braided, i.e., consisting of individual wires or wire bundles as struts, but is preferably a cut structure, in which the mesh is cut from a tube of suitable diameter using a laser. The material is usually a metal, but can also be a plastic. It must possess sufficient elasticity to allow contraction to the diameter of a standard catheter and, conversely, expansion to the desired and predetermined diameter upon release from the catheter. Additionally, it is advantageous to subject the mesh structure to electropolishing to make it smoother and more rounded, and thus less traumatic. This also reduces the risk of adhesion of germs or other contaminants.The struts or wires can have a round, oval, square, rectangular, or trapezoidal cross-section, with rounded edges being advantageous in the case of a square, rectangular, or trapezoidal cross-section. The use of flat webs / wires in the form of thin strips, particularly metal strips, is also possible.

[0047] Besides iron alloys (stainless steel, spring steel) and cobalt-chromium alloys, shape memory alloys are particularly suitable as materials for the struts, such as binary nickel-titanium alloys (Nitinol) and ternary nickel-titanium-chromium alloys (chromium-doped alloys). Nitinol, in particular, is known for its use in self-expanding structures in the neurovascular system.

[0048] Suitable thrombectomy devices may have additional tensioning bars in the central and distal regions beyond the proximal tensioning bar. However, when using shape-memory materials with sufficient pre-tension, any tensioning bars may be omitted.

[0049] The thrombectomy device is deployed by means of a catheter, which guides it to the target site. There, it is released either within the thrombus itself, next to it, or distal to it. The device expands within the vessel and adapts to the vessel lumen. Either during expansion or retraction, the thrombus material becomes trapped in the mesh structure and is drawn into the catheter as the device is withdrawn. Any thrombus fragments adhering to the vessel wall are removed by the shearing action of the mesh and the edges along the slot. The thrombus is then drawn into the catheter and removed from the body.

[0050] By using an additional catheter, especially an aspiration catheter, any detached particles of the thrombus can be aspirated to minimize the risk of further embolisms caused by these particles.

[0051] During thrombus extraction, a helical slit across the vessel wall offers the distinct advantage that, under tension, the edges of the cylindrical structure along the slit migrate tangentially along the circumference of the vessel wall. This enhances the shear effect. Simultaneously, the helical slit improves (or reduces) the bending stiffness, allowing for better adaptation to curved vessels. This facilitates both the placement and extraction of thrombi from complex vascular structures.

[0052] As already stated, the cylindrical structure according to the invention is preferably cut from a cylindrical tube using a laser. This allows the individual meshes to be given a specific cross-section, for example, square, rectangular, or trapezoidal. In the rectangular and trapezoidal embodiments, either the narrow side or the long side of the cross-section can be located on the outer surface. It is preferred that the narrow side of both the rectangle and, in particular, the trapezoid faces the vessel wall, which facilitates easier penetration of the thrombus into the mesh structure and allows for the effective displacement of the thrombus mass during the expansion of the cylindrical structure.

[0053] The connecting struts, located at the proximal end of the cylindrical structure, lead from proximal meshes adjacent to the slot to a coupling element where they are joined. They are part of the cylindrical structure and therefore usually consist of the same material.

[0054] The invention is explained in more detail with reference to the figures. It should be noted that the figures show preferred embodiments of the invention; however, the invention is not limited to these. The scope of protection of the invention is defined by the claims. The figures show: Figure 1 shows a spatial representation of the known cylindrical structure; Figure 2 shows a spatial representation of the preferred embodiment of the device according to the invention.

[0055] Figure 1Figure 1 shows a spatial representation of a variant of the known cylindrical structure 1 with preferably differently designed meshes 3, 4 and the connecting struts 5 and 5'. The meshes 3, 4 give the overall structure stability and flexibility.

[0056] A slot 7 runs through the cylindrical structure 1, which is bridged at the proximal end of the cylindrical structure 1 by the tension strut 9. The slot 7 is bounded by the edges 10 and 10' of the mesh structure. The slot 7 preferably runs obliquely to the longitudinal axis of the cylindrical structure 1, which is represented in the spatial representation as a helical course along the lateral surface.

[0057] The struts of the cylindrical structure 1 located on the back side are shown in light color. Visible is the slot 7 running under the tensioning arch 9 at the proximal end of the cylindrical structure 1, which winds around the lateral surface of the cylindrical structure 1 to the right. The slot 7 ends distally on the underside of the cylindrical structure 1, thus describing a rotation of approximately 180°.

[0058] The connecting struts 5, 5' are joined together in a single coupling element 11, via which a connection exists to the insertion wire, which is only indicated here.

[0059] In the area of ​​the coupling element 11, a proximal marker 13 is provided, which indicates the proximal end of the cylindrical structure 1.

[0060] The slot 7 is bridged by the tension strut 9. The tension strut 9 attaches to the meshes 3, which are located at the edges 10, 10' of the mesh construct, and its arc points towards the distal side of the cylindrical structure 1. This allows the cylindrical structure 1 to be easily inserted into a catheter.

[0061] In a preferred embodiment, the tension strut 9 can follow the contour of the side surface or edge 10 of the mesh structure with its wave-like shape and continue this to the opposite edge 10'. Alternatively, the tension strut 9 can also have a simply curved, i.e., non-wave-shaped, contour.

[0062] The connecting struts 5, 5' with the adjoining mesh edges and the tension strut 9 together form a kind of loop, similar to the opening of a catch basket, which facilitates the insertion of the thrombectomy device into a catheter and is also suitable for shearing off thrombi or thrombus remnants adhering to vessel walls.

[0063] Together with the coupling element 11, the connecting struts 5, 5', the adjoining mesh edges and the tension strut 9 form a ring-shaped structure.

[0064] The distal end of the cylindrical structure can also be closed with a mesh structure.

[0065] Figure 2Figure 1 shows the device according to the invention with a ring marker 12 along the proximal annular structure 6. In the preferred embodiment shown, the ring marker 12 comprises a wire-shaped, radiopaque material that wraps around the annular structure 6 in a loop-like fashion over its entire circumference. Preferably, the wire-shaped ring marker 12 is provided in one piece, i.e., it comprises only a single continuous wire.

[0066] The wire itself can comprise a plurality of individual strands that are, for example, twisted, braided, wound, or otherwise connected. According to the invention, a wire-shaped ring marker 12 made of a continuous wire is therefore a ring marker 12 that is uninterrupted along its length, i.e., that is a single piece.

[0067] The ends of the ring marker 12 are fixed in or on the proximal marker 13.

[0068] Additional proximal markers 13 and distal markers 2 may be provided.

[0069] In the illustrations, the same reference symbols represent the same facts. Reference symbol list

[0070] 1 Cylindrical structure 2 Distal marker 3, 4 Meshes 5, 5' Connecting struts 6 Ring-shaped structure 7 Slot 9 Tension strut 10 Edges of the meshes 11 Coupling element 12 Ring marker 13 Proximal marker distal proximal

Claims

1. Thrombectomy device comprising an essentially cylindrical structure (1) having a proximal end and a distal end and comprising a plurality of meshes (3, 4) composed of struts, including - two connecting struts (5, 5') arranged at proximal meshes at the proximal end of the cylindrical structure (1) and extending in the proximal direction, and - a coupling member (11) arranged proximally of the cylindrical structure (1), with connecting struts (5, 5') being attached to said member, and said coupling member (11) being connected to an insertion wire, wherein struts of the proximal meshes, the connecting struts (5, 5') and the coupling member (11) as well as bracing struts (9) possibly arranged between the proximal meshes form a closed, annular structure (6), characterized in that the annular structure (6) comprises a ring marker (12) with a radiopaque material for visualizing the spatial position of the annular structure (6), and the ring marker (12) is wire-shaped or sleeve-shaped and is wound or laid around the struts forming the annular shaped structure (6).

2. Thrombectomy device according to Claim 1, characterized by a slit (7) extending in a helical fashion over the circumferential surface of the cylindrical structure (1), with a bracing strut (9) spanning the slit (7) at the proximal end of the cylindrical structure (1).

3. Thrombectomy device according to Claim 1 or 2, characterized in that the ring marker (12) encompasses the annular structure (6) at least partially along its length.

4. Thrombectomy device according to Claim 3, characterized in that the ring marker (12) encompasses the annular structure (6) along its entire length.

5. Thrombectomy device according to Claim 1, characterized in that the wire-shaped ring marker (12) is of one-piece design.

6. Thrombectomy device according to any one of Claims 1 to 5, characterized by a proximal marker (13) in the region of the coupling member (11).

7. Thrombectomy device according to any one of Claims 1 to 6, characterized in that the ends of the wire-shaped ring marker (12) are secured in or to the proximal marker (13) or coupling member (11).

8. Thrombectomy device according to any one of Claims 1 to 7, characterized in that the bracing strut (9) forms a camber, with the maximum of the camber pointing toward the distal end of the cylindrical structure (1).

9. Thrombectomy device according to any one of Claims 1 to 8, characterized by further distal and / or proximal markers made of a radiopaque material.

10. Thrombectomy device according to any one of Claims 1 to 9, characterized in that the radiopaque material is selected from gold, tantalum, platinum, palladium or an alloy based on precious metals or a combination of these materials such as platinum-iridium.

11. Thrombectomy device according to any one of Claims 1 to 10, characterized in that further markers are provided along the cylindrical structure (1), and these markers may be provided in wire form, spiral form, tubular form, or sleeve form.

12. Thrombectomy device according to any one of Claims 1 to 11, characterized in that an additional marking of at least parts of the cylindrical structure (1) is provided by coating with radiopaque materials.

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