A thrombectomy stent comprising a developing unit

Abstract

The present invention relates to a thrombectomy stent comprising a developing unit, including a cylindrical proximal portion and one or more radiopaque segments. The cylindrical proximal portion forms a stent frame having an outer grid of a number of interconnected segments on the outside. The number of interconnected segments on the outside are configured to apply a radial force to the inner wall of the blood vessel. The radiopaque segments are formed by a number of radiopaque wires extending along the length of the stent frame from the stent frame to the central axis of the thrombectomy device. The radiopaque segments converge at the tip along the central axis.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Patent Application 17,132,405, filed on December 23, 2020. Field of the Invention

[0003] The present invention generally relates to the field of catheter-based removal of unwanted substances from cerebrovascular structures, and more particularly to a thrombectomy stent having additional radiopaque segments on the lumen of the device to enhance visualization in vivo as well as thrombus retention and removal from cerebrovascular structures. Background of the Invention

[0004] Thrombectomy stent technology has historically been used to remove thrombi (i.e., blood clots) from the neurovascular system (i.e., blood vessels in the brain) during a treatment for stroke called neurothrombectomy. Thrombi cause vascular occlusion, which limits blood flow and significantly reduces the oxygen and nutrients delivered to surrounding tissues. Due to the presence of the thrombus, among other negative scenarios, the tissue distal to the thrombus undergoes necrosis (i.e., cell death), which can ultimately lead to brain injury or death. Thrombectomy stent technology aims to capture the thrombus and remove it from the affected blood vessel, thereby restoring normal flow between blood vessels and preventing further necrosis of the tissue.

[0005] Conventional methods require expanding a metal device into the thrombus to secure itself and then removing the device and the thrombus in a back-and-forth motion. In a clinical setting, visualization devices are crucial because visibility (also known as radiopacity of the device) ensures that the clinician deploys the device in the correct location to capture the thrombus. Since multiple attempts must be made to capture the thrombus, or in more severe cases, the thrombus may not be fully captured and may fragment, improper visualization can increase the surgical time and vascular injury. In that case, the fragmented thrombus may continue to travel distally through the blood vessel until another thrombus appears further downstream, further endangering the patient's safety.

[0006] Conventional stent devices are classically made of nitinol, which is not inherently radiopaque to an acceptable degree for the present application. Known methods of improving visibility include coating a tantalum layer on a nitinol alloy, and / or adding radiopaque (i.e., visible) marker bands throughout the device. While these methods improve the visibility of the device in vivo, no method improves the functionality of the device. In addition, both of these methods increase the manufacturing time and complexity while introducing potential additional failure modes into the device design.

[0007] A thrombectomy device is disclosed in the prior art 1, with reference patent number US 8,632,584. The prior art 1 discloses a longitudinally open tube with interconnected wires or filaments forming a reticular structure, and the reticular structure is designed to capture thrombi in small intracranial blood vessels. However, the device disclosed in the prior art 1 lacks any additional measures to improve radiopacity or any additional measures to improve in-vivo thrombus capture, resulting in a surgical environment that may be very difficult.

[0008] A thrombectomy device is disclosed in the prior art 2, with reference patent number US 10,842,498. The prior art 2 discloses a longitudinal tube with interconnected wires forming a reticular structure, similar to that disclosed in the prior art 1. The prior art 2 discloses a thrombectomy device with segments protruding additionally from the reticular structure, thus increasing the possibility of thrombus proliferation and capture. Most of the mesh body remains inside the device, while the protruding segments extend outward towards the blood vessel, creating an opportunity for thrombus fragmentation leading to secondary embolism. Although the device can theoretically increase additional means for improving thrombus capture, this is limited because the entire device cannot be opened to its full diameter.

[0009] Therefore, there is a need for a thrombectomy device that provides superior thrombus binding for removing thrombi from the vasculature and incorporates imaging elements of the device in a manner that contributes to the overall function of the device without sacrificing other functional components. Summary of the Invention

[0010] At least through various embodiments of the present invention, the above-discussed needs are addressed in the art and the technical solutions are achieved. Some embodiments of the present invention relate to a thrombectomy device, which includes a cylindrical proximal portion and a plurality of radiopaque wires. The cylindrical proximal portion forms a stent frame with an outer lattice having a plurality of external interconnected segments, and the plurality of external interconnected segments are configured to apply a radial force to the inner wall of the blood vessel. The radiopaque wires form radiopaque line segments, and the plurality of radiopaque wires extend from the stent frame along the length direction of the stent frame to the central axis of the thrombectomy device. The radiopaque line segments converge together along the central axis at the tip.

[0011] In some embodiments of the present invention, the radiopaque line segments are formed at the distal end of the stent frame. In some embodiments of the present invention, the radiopaque line segments are convex along the length direction of the stent frame.

[0012] In some embodiments of the present invention, the thrombectomy device includes a plurality of radiopaque line segments. At least one of the plurality of radiopaque line segments is formed at the distal end of the stent frame, and the remaining radiopaque line segments of the plurality of radiopaque line segments are evenly distributed along the length direction of the stent frame.

[0013] In some embodiments of the present invention, a plurality of external interconnecting segments are arranged to include an opening when the stent frame of the thrombectomy device is deployed in the open position, and the radiopaque segments are arranged to include an opening when the device is deployed in the open position. In some embodiments of the present invention, a plurality of external interconnecting segments are arranged to be fully connected without any opening when the stent frame of the thrombectomy device is deployed in the closed position, and the radiopaque segments are arranged to be fully connected without any opening when the thrombectomy device is deployed in the closed position.

[0014] In some embodiments of the present invention, the opening in the stent frame has a smaller cross-section than the opening in the radiopaque segments.

[0015] In some embodiments of the present invention, the stent frame is formed of laser-cut nitinol tubing, and the radiopaque segments are formed of radiopaque wire. In some embodiments of the present invention, the radiopaque segments reinforce the stent frame to enhance thrombus retention and retrieval as well as radial support force.

[0016] In some embodiments of the present invention, the stent frame is configured to capture thrombus in a blood vessel, and the radiopaque segments are configured to improve visibility under radiographic imaging and enhance thrombus retention during device deployment and retrieval.

[0017] In some embodiments of the present invention, the radiopaque segments are formed by extending a plurality of radiopaque wires along the length direction of the stent frame from the stent frame to the central axis of the thrombectomy device to enhance device radial support force, thrombus retention, and in vivo visibility.

[0018] In some embodiments of the present invention, the radiopaque segments are attached to the stent frame using a radiopaque material by one of a soldering process, a welding process, or a brazing process.

[0019] In some embodiments of the present invention, the plurality of radiopaque wires forming the radiopaque segments have superelasticity.

[0020] In some embodiments of the present invention, the radiopaque segments are formed of nitinol tubing with a radiopaque core (i.e., platinum), and the radiopaque core forms a solid radiopaque wire. In some embodiments of the present invention, a plurality of radiopaque wires are combined into a single point, where they are wound and joined to form a tip. In this configuration, each radiopaque wire can be attached to the stent frame to form a radiopaque segment. Optionally, the radiopaque segment can be formed of a single wire that is separated and attached to multiple points on the stent frame.

[0021] In some embodiments of the present invention, the tip formed by the radiopaque segments has complementary radiopaque properties to further enhance in vivo visibility.

[0022] In some embodiments of the present invention, the thrombectomy device further includes a microcatheter, which is designed to deliver the thrombectomy device and retrieve the thrombectomy device from the blood vessel in the closed position.

[0023] In some embodiments of the present invention, a plurality of external interconnecting segments are arranged to be fully connected without any openings when the stent frame of the thrombectomy device is deployed in the closed position, and the radiopaque segments are arranged to be fully connected without any openings when the device is deployed in the closed position.

[0024] In some embodiments of the present invention, the distal end of the device tapers to a single point, where all the remaining interconnecting segments merge together.

[0025] In some embodiments of the present invention, the stent frame is a nitinol tube that is laser cut to form the stent frame.

[0026] In some embodiments of the present invention, the sizes of the openings formed in the radiopaque segments are designed such that they increase the contact surface area with the thrombus, thereby further enhancing thrombus fusion and capture during device delivery and retrieval.

[0027] In some embodiments of the present invention, the stent frame is configured to capture thrombi in the blood vessel, and the inner stent frame is configured to further prevent thrombus migration and assist in capturing thrombi in the blood vessel.

[0028] These and other embodiments of the present invention will be discussed in more detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] It should be understood that the drawings are used to illustrate aspects of various embodiments and include elements that are not drawn to scale. Note that like reference characters in different drawings indicate the same object.

[0030] Figure 1 A side view of a thrombectomy device according to an embodiment of the present invention is shown.

[0031] Figure 2 A side view of another thrombectomy device according to an embodiment of the present invention is shown.

[0032] Figure 3 An end view of the distal end of a thrombectomy device according to an embodiment of the present invention is shown.

[0033] Figure 4Shows a representative image of a blood vessel occluded by a thrombus, where the thrombus occludes the blood vessel and prevents blood flow to the distal end of the blood vessel.

[0034] Figure 5 Shows according to one embodiment of the present invention Figure 4 The occluded blood vessel in the first step of the processing procedure, where a microcatheter is inserted into the proximal end of the thrombus until it is outside the distal end of the thrombus.

[0035] Figure 6 Shows according to one embodiment of the present invention Figure 4 The occluded blood vessel in the second step of the processing procedure, where a thrombectomy device advances in the microcatheter and traverses the thrombus and the surrounding area.

[0036] Figure 7 Shows Figure 6 The occluded blood vessel in the second step of the processing procedure, where an embolic protection device is located at the distal end of the thrombectomy device.

[0037] Figure 8 Shows according to one embodiment of the present invention Figure 4 A representative image of the blood vessel, where the thrombectomy device and the thrombus are subsequently removed after the processing procedure is completed. Detailed Description

[0038] In the description herein, certain specific details are set forth in order to provide a thorough understanding of the various embodiments of the present invention. However, those skilled in the art will understand that the present invention may be practiced on a broader level without one or more of these details. In other instances, well-known structures have not been shown or described in detail to avoid unnecessarily obscuring the description of the various embodiments of the present invention.

[0039] Any reference in the entire specification to "one embodiment", "an embodiment", "an exemplary embodiment" or "an illustrative embodiment" means that the specific features, structures or characteristics described in connection with the embodiment are included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment", "in an embodiment", "in an exemplary embodiment" or "in the illustrative embodiment" etc. in this specification do not all refer to the same embodiment. In addition, the described specific functions, structures or features of different embodiments may be combined in any suitable manner to form one or more other embodiments.

[0040] Unless specifically and explicitly described otherwise or required by the context otherwise, the word "or" is used in a non-exclusive sense in the present invention. In addition, unless specifically and explicitly described otherwise or required by the context otherwise, the word "group" means one or more. For example, the phrase "a group of objects" refers to one or more of the objects.

[0041] In the following description, the phrase "at least" is only occasionally used or may be used herein to emphasize the possibility that there may be other elements in addition to those explicitly listed. However, unless specifically and explicitly described otherwise (such as by using the term "only") or required by the context otherwise, the use of the phrase "at least" herein still includes the possibility that there may be other elements in addition to those explicitly listed. For example, the phrase "comprising at least A" includes the possibility of A and one or more other additional elements in addition to A. In the same way, the phrase "comprising A" includes A and the possibility of one or more other additional elements in addition to A. However, the phrase "only comprising A" only includes A. Similarly, the phrase "at least configured to A" includes the possibility of a configuration for performing A and one or more other additional actions in addition to A. In the same way, the phrase "configured to A" includes the configuration for performing A and the possibility of one or more other additional actions in addition to A. However, the phrase "only configured to A" refers to a configuration that only performs A.

[0042] The words "device", the word "machine", the word "system" and the word "device system" all mean including one or more physical devices or sub-devices (e.g., device parts), whether such devices or sub-devices are located in the same housing or different housings, and the one or more physical devices or sub-devices interact to perform one or more functions. However, it can be explicitly stated according to various embodiments that the device, machine or device system is entirely located in the same housing to exclude embodiments where the corresponding device, machine or device system spans different housings. In some embodiments, the word "device" can be equivalently referred to as "device system".

[0043] Figure 1-2Illustrated is a thrombectomy device (“thrombectomy stent”) according to some embodiments of the present invention. The thrombectomy device includes a stent frame 100 having two radiopaque line segments 101 terminating at a tip 102. In some embodiments, the stent frame 100 is formed of a laser-cut nitinol tube, and the radiopaque line segments 101 are composed of a number of nitinol wires with a radiopaque core (e.g., platinum). In some embodiments, the stent frame 100 is formed of a lattice network of interconnected non-rigid or rigid metal segments designed to open relative to the vessel wall with sufficient radial force to pass through a blood clot without damaging the surrounding blood vessel. In some embodiments of the present invention, the stent frame 100 is opened such that the metal segments are not fully connected radially to facilitate binding of the metal segments to the blood clot. In some embodiments of the present invention, the stent frame 100 is closed such that the metal segments are fully connected radially to enhance device stability. In some embodiments of the present invention, as Figure 1 shown, the stent frame 100 can be made in various lengths 103 to accommodate different anatomical requirements. In some embodiments of the present invention, the lattice network of the stent frame 100 can be made in a larger or smaller diameter to accommodate different anatomical requirements. In some embodiments of the present invention, the number of radiopaque line segments 101 can be increased or decreased to match the various lengths 103 of the stent frame 100.

[0044] In some embodiments of the present invention, the stent frame 100 is made using laser cutting of nitinol tubing. Compared to wire braiding, laser-cut tubing improves manufacturability (e.g., speed or ease of use). Additionally, compared to wire braiding, laser-cut tubing reduces the overall thickness of the device, which in turn reduces the overall device profile. Reducing the device profile corresponds to reducing the difficulty of crossing the target blood clot and the difficulty of retrieval based on clot retrieval, as well as improving possible target locations in the vasculature.

[0045] In some embodiments of the present invention, the radiopaque line segments 101 serve as a second stent frame designed to further capture blood clots and prevent distal movement of blood clots during deployment and retrieval. Figure 3The device at the deployment location is shown, where the radiopaque segment 101 extends into the stent frame 100, thereby generating an internal grid orthogonal to the grid of the stent frame 100. In some embodiments of the present invention, the radiopaque segment 101 is convex. The radiopaque segment 101 is designed in such a way as to enhance the stent frame 100 to improve the radial support force. Improving the radial support force without thickening the stent frame 100 can improve the crimped stent profile, thereby further improving the device delivery ability and ease of use. In some embodiments of the present invention, the radiopaque segment 101 is designed in such a way as to further increase the contact surface area between the thrombectomy device and the thrombus, thereby providing multiple internal attachment points to prevent the distal movement of the thrombus during the operation. In some embodiments of the present invention, the radiopaque segment 101 is designed in such a way that this segment serves as a radiopaque marker to improve the visibility of in-vivo surgery.

[0046] In some embodiments of the present invention, the radiopaque segment 101 is made of a number of radiopaque superelastic wires, and the number of radiopaque superelastic wires is attached to multiple positions on the outer stent frame 100. Using a welding process, a soldering process or a brazing process, the superelastic wires can be attached to the outer stent frame 100. In some embodiments of the present invention, a radiopaque material can be used to solder or attach the superelastic wires to the outer stent frame 100.

[0047] Contrary to current visualization techniques that are limited to non-functional use other than radiopacity, the incorporation of radiopaque superelastic wires enables the device to be superelastic and visible in vivo, while serving as a functional component of the device. The radiopaque segment 101 integrated in this way provides the advantage of radiopacity while not hindering the device with more difficult manufacturing techniques or increasing the overall crimped profile of the device.

[0048] In some embodiments of the present invention, the number of radiopaque segments 101 can be increased or decreased to further improve the overall crimped profile or radiopaque properties of the device. There must be at least one (1) radiopaque segment 101 at the distal end of the thrombectomy device. In some embodiments of the present invention, any subsequent radiopaque segments 101 are equally spaced (evenly distributed) along the length of the stent frame 100. In some embodiments of the present invention, each radiopaque segment 101 converges at the solid tip 102.

[0049] In some embodiments of the present invention, the radiopaque segment 101 can be formed from a single radiopaque superelastic wire, such that the tip 102 is a single solid wire, and a number of radiopaque wires are separated from the single initial wire to be attached to the stent frame 100 at multiple positions.

[0050] In some embodiments of the present invention, the radiopaque segment 101 may be formed by a plurality of individual radiopaque wires, each of the plurality of individual radiopaque wires being attached to the stent frame 100 and extending from the stent frame 100 along the length of the stent frame 100 to the central axis of the thrombectomy device, thus converging at a tip 102 aligned with the central axis of the thrombectomy device. In some embodiments of the present invention, the tip 102 is formed by crimping and joining a plurality of individual radiopaque wires to form a complete radiopaque segment. In some embodiments of the present invention, the tip 102 may comprise a radiopaque material (e.g., tantalum) to further enhance the radiopacity of the thrombectomy device.

[0051] As Figure 1-3 shown, in some embodiments of the present invention, the lattice of the stent frame 100 and the radiopaque segment 101 are rigid because the lattice is completely interconnected and forms a funnel shape to a single point, i.e., the distal tip 102. In some embodiments of the present invention, the window (opening) size (distance between metal segments) of the lattice of the radiopaque segment 101 is larger than the window (opening) size of the lattice of the stent frame 100 to ensure that the device can be deployed to its intended diameter without unnecessary additional resistance.

[0052] In some embodiments of the present invention, the cross-sectional area of each window (opening) of the lattice network of the thrombectomy device is preferably between 0.5 mm 2 and 2 mm 2 . In some embodiments of the present invention, the radiopaque segment 101 is convex to increase the contact surface area, thereby enhancing the capture and retrieval of thrombus, and increasing the cross-sectional area visible during radiographic imaging.

[0053] Figures 4-8 A cross-sectional view of a blood vessel during the process of using the thrombectomy device is shown. Figure 4 A representative image of a blood vessel 106 blocked by a thrombus 105 according to an embodiment of the present invention is shown. The thrombus 105 blocks the blood vessel 106, thereby preventing blood 104 from flowing to the distal end of the blood vessel.

[0054] In some embodiments of the present invention, the thrombectomy device is designed to treat a thrombus 105 in a blood vessel 106, where the thrombus 105 obstructs the flow of blood 104 to the distal end of the blood vessel 106. As Figure 5 shown, in the first step of the treatment process, the distal end of the microcatheter 107 is inserted into the affected blood vessel 106 through the thrombus 105. Figure 6Shows blood vessel 106 in the second step of the treatment process. In some embodiments of the present invention, the thrombectomy device advances in the microcatheter 107 such that the stent frame 100 is simultaneously located proximal and distal to the thrombus 105, and both the distal radiopaque segment 101 and the distal tip 102 are located distal to the thrombus 105.

[0055] In some embodiments of the present invention, as Figure 7 shown, the thrombectomy device may include an embolic protection device 108 on the distal end to reduce the risk and impact of secondary embolization.

[0056] In some embodiments of the present invention, the thrombectomy device is designed such that it self-expands after removal of the delivery sheath (microcatheter 107). The stent frame 100 is designed to open to the full vessel diameter, wherein different embodiments of the thrombectomy device can expand to a range of diameters and lengths to accommodate the needs of the patient. The radiopaque segment 101 is designed to open to a diameter that varies between the maximum diameter acquired by the stent frame 100 and the initial starting crimp diameter. In some embodiments of the present invention, the stent frame 100 exerts sufficient radial force to penetrate and integrate into the thrombus 105 without damaging the blood vessel 106.

[0057] In some embodiments of the present invention, after self-expanding and integrating into the thrombus 105, the thrombectomy device can be retracted into the microcatheter 107 and refolded to its original compressed configuration, wherein the thrombus 105 is contained within the structure. As Figure 8 shown, after removing the device through the microcatheter 107, blood 104 resumes flowing into the blood vessel 106, thereby allowing key nutrients to be delivered to areas distal to the treatment site. In some embodiments of the present invention, the thrombectomy device is attached to a push wire, which is used to advance the thrombectomy device in the microcatheter 107 to the target position.

[0058] It should be understood that the present invention is not limited to the embodiments discussed above, which are provided for illustrative purposes only. Subsets or combinations of the various above-described embodiments further provide embodiments of the present invention.

[0059] Based on the above detailed description, these and other changes can be made to the present invention and still fall within the scope of the present invention. Generally, in the following claims, the terms used should not be construed as limiting the present invention to the specific embodiments disclosed in the specification. Therefore, the present invention is not defined by the disclosure, but rather the scope of the present invention is fully determined by the following claims.

Claims

1. A thrombectomy device, comprising: A cylindrical proximal portion forming a stent frame, the stent frame having an outer grid of a plurality of interconnected segments on the outside, and not having an elongated central member longitudinally extending along the central axis of the stent frame, the plurality of interconnected segments on the outside being configured to apply a radial force to the inner wall of the blood vessel; A plurality of radiopaque wires, the plurality of radiopaque wires extending from the stent frame along the length direction of the stent frame to the central axis of the thrombectomy device, the radiopaque wire segments converging along the central axis to form a single, independent tip, and the openings in the stent frame having a smaller cross-section than the openings in the radiopaque wire segments; The openings in the radiopaque wire segments are window openings of the grid of the radiopaque wire segments; the size of the window openings of the grid of the radiopaque wire segments is the distance between the metal segments of the windows of the grid of the radiopaque wire segments; Wherein, the plurality of interconnected segments on the outside are arranged such that when the stent frame of the thrombectomy device is deployed in the closed position, they are completely connected without any openings, and wherein, the radiopaque wire segments are arranged such that when the thrombectomy device is deployed in the closed position, they are completely connected without any openings; Wherein, the radiopaque wire segments have a convex shape extending along the length direction of the stent frame; The radiopaque wire segments are made of radiopaque superelastic wires.

2. The thrombectomy device according to claim 1, wherein The radiopaque wire segments are formed at the distal end of the stent frame.

3. The thrombectomy device according to claim 1, further comprising a plurality of radiopaque wire segments, wherein, At least one of the plurality of radiopaque wire segments is formed at the distal end of the stent frame, and Wherein, the remaining radiopaque wire segments of the plurality of radiopaque wire segments are uniformly distributed along the length direction of the stent frame.

4. The thrombectomy device according to claim 1, wherein, The plurality of interconnected segments on the outside are arranged such that when the stent frame of the thrombectomy device is deployed in the open position, it includes openings, and Wherein, the radiopaque wire segments are arranged such that when the thrombectomy device is deployed in the open position, it includes openings.

5. The thrombectomy device according to claim 1, wherein, The stent frame is formed by a laser-cut nitinol pipe fitting, and the radiopaque wire segments are formed by radiopaque wires.

6. The thrombectomy device according to claim 1, wherein, The radiopaque wire segments strengthen the stent frame to enhance thrombus retention and retrieval as well as radial support force.

7. The thrombectomy device according to claim 1, further comprising a microcatheter, the microcatheter being designed to deliver and retrieve the thrombectomy device from the blood vessel at the closed position.

8. The thrombectomy device according to claim 1, Wherein, The stent frame is configured to capture thrombus in the blood vessel, and Wherein, the radiopaque wire segments are configured to improve visibility under fluoroscopy and enhance thrombus retention during device deployment and retrieval.

9. The thrombectomy device according to claim 1 further includes an embolic protection device connected to the distal end of the stent frame.

10. The thrombectomy device according to claim 1, wherein the radio-opaque segment is attached to the stent frame by one of soldering process, welding process or brazing process using radio-opaque material.

Images