Obstacle Removal System

Abstract

An obstruction removal system is provided for capturing and removing obstructions, such as blood clots, from the vasculature. The obstruction removal system may include one or more engagement members connected to an elongate member, for example, at a distal end of the elongate member. The engagement members may have an asymmetric body shape, such as a "teardrop" shape, and / or an asymmetric cell configuration between their proximal and distal portions. The engagement members may be comprised of multiple struts. One or more radiopaque markers may be connected to at least one strut having a "dogbone" shape. A mesh structure may be disposed on the interior or exterior of the engagement members to function as a filter. A support wire may be disposed internally to assist in maintaining the engagement members open. When multiple engagement members are used, each engagement member may be a different size.

Description

[Technical field]

[0001] (Related Applications) This application claims priority to U.S. Provisional Application Serial No. 63 / 227669, entitled Obstacle Removal System, filed on July 30, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Described herein are devices for capturing and removing obstructions, such as blood clots or other material, from the vasculature, as well as systems and methods relating to such devices and for delivering the devices to target areas within the vasculature.

[0003] The accumulation of blood clots in the vascular system leads to the formation of blood clots, which restrict the blood supply to downstream areas of the vascular system. Blood clots in the neurovasculature can lead to stroke.

[0004] There is a need for an obstruction removal device that maximizes mechanical capture of thrombus while limiting the risk of endothelial denudation caused by high friction between the device and the vessel wall, while reducing the likelihood of fragmented masses remaining in the vasculature. [Brief description of the drawings]

[0005] These and other aspects, features and advantages of possible embodiments of the present invention will be apparent or obvious from the following description of the embodiments of the invention.

[0006] [Figure 1] FIG. 1 is a side view of an engaging member according to an exemplary embodiment.

[0007] [Diagram 2] FIG. 2 is a side view of an engagement member according to an exemplary embodiment.

[0008] [Figure 3A]FIG. 3A is a side view of multiple interlocking engagement members according to an exemplary embodiment.

[0009] [Figure 3B] FIG. 3B is a side view of multiple interlocking engagement members according to an exemplary embodiment.

[0010] [Figure 4] FIG. 4 is a top view of a strut pattern for an engagement member according to an exemplary embodiment.

[0011] [Diagram 5] FIG. 4 is a top view of a strut pattern for an engagement member according to an exemplary embodiment.

[0012] [Figure 6] FIG. 6 is a close-up view of a structure for holding radiopaque markers according to an exemplary embodiment.

[0013] [Figure 7] FIG. 7 is a close-up view of a structure for retaining radiopaque markers according to an exemplary embodiment.

[0014] [Figure 8] FIG. 8 is a close-up view of a radiopaque marker according to an exemplary embodiment.

[0015] [Figure 9] FIG. 9 is a close-up view of a radiopaque marker according to an exemplary embodiment.

[0016] [Figure 10] FIG. 10 is a close-up view of a radiopaque marker according to an exemplary embodiment.

[0017] [Figure 11] FIG. 11 is a close-up view of a radiopaque marker on a distal end of an engagement member according to an exemplary embodiment.

[0018] [Figure 12] FIG. 12 is a side view of a process for making the radiopaque marker of FIG. 11 according to an exemplary embodiment.

[0019] [Figure 13] FIG. 13 is a side view of a process for making the radiopaque marker of FIG. 11 according to an exemplary embodiment.

[0020] [Figure 14] FIG. 14 is a side view of a process for making the radiopaque marker of FIG. 11 according to an exemplary embodiment.

[0021] [Figure 15] FIG. 15 is a side view of a process for making the radiopaque marker of FIG. 11 according to an exemplary embodiment.

[0022] [Figure 16] FIG. 16 is a side view of an engagement member having a mesh structure therein according to an exemplary embodiment.

[0023] [Figure 17] FIG. 17 is a side view of an engagement member having a mesh structure therein according to an exemplary embodiment.

[0024] [Figure 18] FIG. 18 is a side view of an engagement member having a mesh structure between multiple engagement members, according to an exemplary embodiment.

[0025] [Figure 19] FIG. 19 is a side view of an engagement member having a mesh structure engagement member behind it, according to an exemplary embodiment.

[0026] [Figure 20] FIG. 20 is a side view of a mesh structure according to an exemplary embodiment.

[0027] [Figure 21] FIG. 21 is a side view of a mesh structure according to an exemplary embodiment.

[0028] [Figure 22] FIG. 22 is a side view of a mesh structure according to an exemplary embodiment.

[0029] [Diagram 23] FIG. 23 is a side view of an engaging member having a support wire therein according to an exemplary embodiment.

[0030] [Figure 24] FIG. 24 is a side view of an engaging member having a support wire therein according to an exemplary embodiment.

[0031] [Figure 25A] FIG. 25A is a side view of a first step for making an engagement member according to an exemplary embodiment.

[0032] [Figure 25A] FIG. 25A is a side view of a second step for making an engagement member according to an exemplary embodiment.

[0033] [Figure 25A] FIG. 25A is a side view of a third step for making an engagement member according to an exemplary embodiment. Summary of the Invention

[0034] Described herein is an obstruction removal device that facilitates maximum mechanical capture of thrombus while limiting the risk of endothelial denudation caused by high friction between the device and the vessel wall, while reducing the likelihood of fragmented masses remaining in the vasculature.

[0035] In one embodiment, the obstruction removal device may include an elongate member coupled at or near a distal end of one or more engagement members that may have a collapsed configuration when sheathed and / or constrained within the delivery device and an expanded configuration when unsheathed and / or unconstrained.

[0036] In one exemplary embodiment, only one engaging member may be directly or indirectly connected to the elongate member, such as to the distal end of the elongate member. In another exemplary embodiment, multiple engaging members (e.g., two, three, four, five, six, seven or more engaging members) may be directly or indirectly coupled to the elongate member. In an embodiment having multiple engaging members, only one of the engaging members or more than one of the engaging members may be coupled to the elongate member.

[0037] In one exemplary embodiment, one or more engagement members may be disposed on and connected to the wire or distal portion of the elongate member, and in some exemplary embodiments, the proximal and distal ends of each engagement member may be connected to one another via a connecting link such that each engagement member is rotatable relative to the other.

[0038] In one exemplary embodiment, one or more of the plurality of engagement members may have different widths or diameters, hi one exemplary embodiment, the width or diameter of each engagement member may decrease between the proximal and distal ends of the obstruction removal system.

[0039] In one exemplary embodiment, the one or more engagement members may each have a plurality of struts that define a plurality of cells or openings when the one or more engagement members are expanded from a radially compressed configuration to a radially expanded configuration. The one or more engagement members may be formed from Nitinol or a similar material and may be laser cut from a tube or panel to achieve a desired contour shape.

[0040] In one exemplary embodiment, one or more of the engagement members may have an asymmetric body shape and / or an asymmetric cell configuration between the proximal and distal ends of the engagement members. One or more of the engagement members may have a generally "teardrop" shape, with its distal end expanding radially to a relatively large diameter and then tapering over the remaining proximal length to the proximal end of the engagement member.

[0041] In exemplary embodiments where each engagement member is comprised of multiple struts, the struts may be generally tapered to reduce in width towards the center of the engagement member, and thus the proximal struts may taper to be thicker near the center to provide increased longitudinal stiffness without increasing radial or compliance forces when tensioned.

[0042] In one exemplary embodiment, one or more of the engagement members may include one or more radiopaque markers disposed about at least a portion of one or more struts. One or more of the plurality of struts may include one or more structural features or shapes that aid in holding the radiopaque marker in place, such as a "dogbone" strut shape having a central portion, a first protruding portion extending distally from the central portion, and a second protruding portion extending proximally from the central portion. The corners of the central portion may include ridges, bumps, or other protrusions that act as stops to prevent the radiopaque marker from slipping off the strut.

[0043] In one exemplary embodiment, a mesh structure may be disposed within the engagement member or externally adjacent to the engagement member and acts as a filter to capture embolic particles. The mesh structure may be comprised of a single braided wire or multiple braided wires.

[0044] In one exemplary embodiment, the engagement member may include one or more support wires that may support the engagement member in its expanded configuration.

[0045] In one exemplary embodiment, the thrombus-capturing engagement portion includes a plurality of open cells and has a radially compressed configuration and a radially expanded configuration, the radially expanded configuration forming a longitudinally asymmetric shape having a distal region of larger diameter than the intermediate and proximal regions.

[0046] A method of removing an obstruction may include advancing one or more engagement members from a delivery catheter and engaging the one or more engagement members with the obstruction.

[0047] A method of manufacturing an obstruction removal system may include forming one or more engagement members and coupling at least one of the one or more engagement members to an elongate member.

[0048] Another method of manufacturing an obstruction removal system may include providing an engagement member comprised of a plurality of struts and applying a radiopaque material to or around one or more of the plurality of struts.

[0049] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. The terms used in the detailed description of the embodiments shown in the accompanying drawings are not intended to limit the present invention. In the drawings, like numbers refer to like elements. Although different embodiments are described, the features of each embodiment can be used interchangeably with other described embodiments. In other words, any of the features of each embodiment can be mixed and combined with each other, and the embodiments should not necessarily be strictly construed as including only the features shown or described.

[0050] For purposes of the terminology described below, the terms clot, thrombus, embolism, and obstruction can be used interchangeably. Although obstruction removal devices are described, the devices can also be used to capture clots, thrombus, embolisms, foreign bodies, obstructions, or other materials. Engagement members on the devices can engage clots, thrombus, embolisms, foreign bodies, obstructions, or other materials.

[0051] As used herein, when referring to a value, the use of the term "about" or "around" may be understood to mean within plus or minus 5% of the stated value.

[0052] The present invention may comprise an obstruction removal system that includes one or more engagement structures, such as one or more engagement members. An engagement structure, such as an engagement member, is generally considered to be an expandable structure having a plurality of openings, cells, or spaces sized to allow a blood clot or similar structure to engage and / or enter the structure when in an expanded position.

[0053] At least one of the engagement members may be connected, directly or indirectly, to the elongate member. There may be only one engagement member coupled to the elongate member (e.g., at the distal end of the elongate member) or multiple engagement members may be coupled to the elongate member.

[0054] When multiple engagement members are utilized, adjacent engagement members may be interconnected via connecting links such that each engagement member is rotatable relative to the other engagement members, such that freedom of movement can be provided to enhance the clot retrieval process.

[0055] Each engagement member may include a plurality of struts that define a plurality of cells or openings when the engagement member is in an expanded, radially enlarged configuration. The engagement members may have an asymmetric body shape and an asymmetric cell configuration between the proximal and distal ends of the engagement member. Thus, a first portion of the engagement member may have a different size and / or cell size / layout than a second portion of the engagement member (e.g., a distal half of the engagement member may have a different size and / or cell size / layout than a proximal half of the engagement member).

[0056] When multiple engagement members are utilized, one or more of the engagement members may have a different size than the remaining one or more engagement members. Thus, the present invention may include multiple engagement members each having a different size (e.g., width or diameter). The size of each engagement member may decrease between the proximal and distal ends of the obstruction removal system. Pairs of similarly sized engagement members may be grouped together, with each subsequent pair having a different size than the previous pair.

[0057] The cells or openings of the engagement member may have a lower porosity (i.e., smaller cell size) at the distal portion of the engagement member and a higher overall porosity (i.e., larger cell size) at the intermediate portion of the engagement member. The higher overall porosity of the intermediate portion may aid in the passage of clots into and removal from the engagement member. A lower porosity at the distal portion of the engagement member may prevent the clot from migrating through the engagement member, resulting in a failed retrieval.

[0058] The struts themselves may have different widths. The struts may be generally tapered, decreasing in width towards the middle of the engagement member (i.e., the struts may decrease in width from a first width at the proximal portion of the engagement member towards the middle). Thus, the struts near the middle may be thicker to provide increased stiffness when under tension. The distal struts may taper in an opposite direction to the taper of the proximal struts.

[0059] One or more of the engagement members may include one or more radiopaque markers. Each radiopaque marker may consist of a wire wrapped around the strut, a wire coil, a wrapped ribbon, a sheet folded around the strut, a hypotube disposed around the strut, a bead, etc. The radiopaque markers may be attached to the struts by a variety of methods including, but not limited to, adhesives, welding, melting, etc.

[0060] The struts may include structural features or shapes useful for retaining a radiopaque marker on the strut. One or more struts may include a "dogbone" shape having regions of increased width at their proximal and distal ends relative to adjacent regions of the strut. Protrusions on either end of the center of the strut may prevent the radiopaque marker from sliding off proximally or distally.

[0061] The obstruction removal system may include a mesh structure that can act as a filter to capture embolic fragments to prevent loss during the clot retrieval process. The mesh structure may be at least partially within the engagement member or may be external to and adjacent to the engagement member. The mesh structure may be comprised of a single braided wire or multiple braided wires of various shapes.

[0062] The obstruction removal system may include one or more structures within the engagement members that help aid expansion and prevent collapse in the one or more engagement members, particularly when passing through tortuous vessels. The one or more structures may include one or more support wires disposed within the one or more engagement members. The one or more support wires may be heat set into a wide variety of shapes, including a helix shape or multiple concentric ring shapes.

[0063] Specific examples of the embodiments are further described below. However, it should be understood that any features in the embodiments can be mixed and combined with each other in any combination. Therefore, the present invention should not be limited to only these embodiments, and a wider range of combinations are possible.

[0064] 1-2 show an engagement member 100 that may be used in various embodiments of the obstacle removal device 101. The systems and methods shown and / or described herein may be used with a variety of obstacle removal devices 101, and the exemplary embodiments shown in the figures should not be construed as limiting in scope. The systems and methods shown and / or described herein may be used in combination with obstacle removal devices 101 shown and / or described in, for example, but not limited to, U.S. Pat. Nos. 10,729,455, 10,722,254, 10,709,466, 9,833,252, 9,770,251, 9,211,132, and U.S. Patent Publication No. 2019 / 0046210, all of which are incorporated herein by reference in their entirety.

[0065] In one exemplary embodiment shown in the figures, obstruction removal device 101 may include one or more distal engagement members 100 capable of engaging thrombus or similar material that may accumulate within the vasculature. Engagement members 100 may be deployed adjacent to the thrombus or embolus and then retracted proximally to capture the thrombus or embolus within engagement members 100. Engagement members 100 may then be retracted further proximally into delivery device 105 and removed from the patient.

[0066] The systems and methods shown and / or described herein can be utilized with a variety of delivery devices 105, and the exemplary embodiment shown in the figures should not be construed as limiting in scope. By way of non-limiting example, exemplary embodiments of the delivery device 105 can include a variety of tubular medical delivery devices, including, but not limited to, a catheter, sheath, or tubular jacket having a continuous passageway that allows passage of the obstruction removal device 101.

[0067] As shown in FIG. 1, an exemplary embodiment of the obstruction removal device 101 may include an elongated member 103 coupled at or near the distal end of one or more engagement members 100. In some embodiments, the elongated member 103 may be a solid member. In other embodiments, the elongated member 103 may be tubular. For example, the elongated member 103 may include a lumen extending through at least a portion of its length. In some embodiments, the elongated member 103 may have a continuous lumen through it, thereby functioning like a catheter (e.g., it may be used as a conduit for subsequently deployed items). The elongated member 103 may be considered a pusher since it may be used to position the obstruction removal device 101 itself. An overlying delivery device 105 may be positioned over the elongated member 103 to allow both the elongated member 103 and the one or more engagement members 100 to be advanced from and / or retracted into the delivery device 105.

[0068] Each engaging member 100 can have a collapsed configuration when sheathed within the delivery device 105 and an expanded configuration as shown in FIGS. 1-2 when unsheathed. Each engaging member 100 can be self-collapsible and self-expandable based on whether an external force is applied to constrain it (as when sheathed in the delivery device 105) or there is no constraining force (as when unsheathed). Each engaging member 100 can be constructed of a shape memory material (e.g., Nitinol) and can be heat set to impart an expandable shape memory, which allows the engaging member 100 to assume an expanded shape when released from the delivery device 105.

[0069] In one example, only one engagement member 100 may be disposed on and connected (directly or indirectly) to the distal end of the elongate member 103. In another example, multiple engagement members 100 may be disposed on the distal end of the elongate member 103, as shown in Figure 3A (note that in Figure 3A, the elongate member 103 itself is not shown, but the elongate member 103 may be connected to at least the most proximal engagement member 100, and in some embodiments may be connected to multiple engagement members 100).

[0070] The multiple engagement members 100 may all be disposed on and connected to a wire or distal portion of the elongate member 103. Alternatively, the proximal and distal ends of each engagement member 100 may be connected to one another via a connecting link (e.g., a shaft or pin having a flared end disposed within each engagement member 100). One advantage to the latter configuration is that each engagement member 100 may be able to rotate independently relative to the other engagement members 100. This independent rotation may improve the clot retrieval procedure since each engagement member 100 has some freedom of movement.

[0071] In some exemplary embodiments, the connecting links allow some sliding movement for each engagement member 100 (e.g., a shaft or pin with a flared end that is slightly longer than the retaining structure), thereby further improving the independence of movement of each engagement member 100. U.S. Patent No. 9,211,132, which is incorporated herein by reference in its entirety, provides further information regarding such connecting structures.

[0072] One or more engagement members 100 may each have a plurality of struts 102 that define a plurality of cells or openings 104A-104D when the engagement members 100 are expanded from a radially compressed configuration to a radially expanded configuration. The engagement members 100 may be formed from Nitinol or a similar material and may be laser cut from a tube or panel to achieve a desired contoured shape. Other materials and other cutting and / or machining processes would be within the scope of the present invention.

[0073] In one embodiment, the engagement member 100 may be configured to have an asymmetric body shape and an asymmetric (i.e., longitudinally asymmetric) cell configuration between the proximal and distal portions of the engagement member 100. In other words, a first portion of the engagement member 100 may not have the same size or cell size / layout as a second portion of the engagement member 100. In one exemplary embodiment, the distal half of the engagement member 100 may have a different size or cell size / layout than the proximal half of the engagement member 100. In another exemplary embodiment, the distal quarter length of the engagement member 100 may have a different size or cell size / layout than the proximal three-quarter length of the engagement member 100. Various other configurations may be utilized in different embodiments to suit different applications.

[0074] 3A-3B show a plurality of engaging members 100 connected to one another. FIG. 3A shows an exemplary embodiment having four engaging members 100. FIG. 3B shows an exemplary embodiment having six engaging members 100. It should be understood that the number of engaging members 100 shown in the various exemplary embodiments shown in the figures is not meant to be limiting in scope, as more or fewer engaging members 100 may be utilized in different embodiments to suit different applications. As an example, some exemplary embodiments may have less than three engaging members 100, five engaging members 100, or more than six engaging members 100.

[0075] In the illustrated exemplary embodiment, the engaging members 100 are arranged in a linear fashion and each engaging member 100 is shown in a deployed configuration. It should be understood that during delivery and / or deployment, the engaging members 100 may not be arranged in a linear fashion, such as through tortuous blood vessels.

[0076] FIG. 3A illustrates an exemplary embodiment in which the engagement members 100 are each substantially the same size. However, in some embodiments, one or more of the engagement members 100 may be larger or smaller than one or more of the remaining engagement members 100. FIG. 3B illustrates an exemplary embodiment in which the width or diameter of the engagement members 100 decreases between the proximal and distal ends. In some embodiments, the reverse configuration may be utilized in which the width or diameter of the engagement members 100 increases between the proximal and distal ends. Thus, the proximal engagement members 100 may be larger in width or diameter than the distal engagement members 100, and the middle engagement member 100 between the proximal and distal engagement members 100 may be larger in width or diameter than the distal engagement members 100 and smaller in width or diameter than the proximal engagement members 100.

[0077] 3B, it can be seen that the plurality of engaging members 100 may include pairs of engaging members 100 having substantially similar widths or diameters. In the exemplary embodiment shown, the distal pair of engaging members 100 has a larger width or diameter than the central pair of engaging members 100, which has a larger width or diameter than the proximal pair of engaging members 100. In different embodiments, various other configurations of increasing or decreasing widths or diameters may be utilized. For example, in some embodiments, the widths or diameters of the engaging members 100 may decrease and then increase, or vice versa.

[0078] The body shape and cells of engagement member 100 in a radially expanded configuration are best seen in Figures 1 and 2, with engagement member 100 shown in a flattened configuration (i.e., as if engagement member 100 had been radially compressed, cut open, and laid flat) in Figure 4 and in Figure 5, which shows a slightly modified design. Figures 4-5 can be thought of as the shape formed during the manufacturing process of engagement member 100 (e.g., a laser cut sheet) and prior to any manufacturing steps taken to radially expand that shape.

[0079] As can be seen in these figures, the body shape of the engagement member 100 may have a generally "teardrop" shape, with its distal end 113 expanding radially to a relatively large diameter and then tapering over the remaining proximal length to the proximal end 111 of the engagement member 100. In one embodiment, the struts 102 of the engagement member 100 expand radially to a maximum distal diameter over the first quarter of the length from the distal end of the engagement member 100 and then taper in diameter over the remaining three-quarters of the proximal length. The desired expanded shape can be achieved, for example, by shape setting or heat setting the engagement member over a mandrel that forces it into the desired shape and diameter upon expansion.

[0080] In one exemplary embodiment, the engagement member 100 may have a length of about 3 mm when expanded, reach a maximum radial diameter of about 2 mm along a length of about 1 mm proximally from its distal end, and have a tapered shape with a decreasing radial diameter in the proximal direction. In another exemplary embodiment, the engagement member 100 may have a length of about 6 mm when expanded, reach a maximum radial diameter of about 3 mm along a length of about 2 mm, and have a tapered shape with a decreasing radial diameter in the proximal direction. Thus, it should be understood that from some embodiments, the maximum diameter of the engagement member 100 is equal to about 25% to 75% of the length. In one exemplary embodiment, the maximum radial diameter of the engagement member 100 may be equal to about 66% of the length of the engagement member 100. In another exemplary embodiment, the maximum diameter of the engagement member may be equal to about 50% of the length of the engagement member 100.

[0081] As also shown, the cells 104C that define the open space of the engagement member 100 may be configured to have a generally low porosity (i.e., smaller cell size) at the distal portion of the engagement member 100 and a generally high porosity (i.e., larger cell size) at the intermediate portion. In some embodiments, the generally high porosity of the cells 104C may also be present at the proximal portion. The generally high porosity at the intermediate portion may facilitate the incorporation of blood clots into the engagement member 100.

[0082] By reducing the porosity in the distal section, clots may be less likely to migrate through the engagement member 100 and more likely to be successfully retrieved. Additionally, this cell and strut pattern may allow for more flexibility in the middle section of the engagement member 100, allowing it to better bend around curves in the vessel while being less likely to kink or adversely affect its ability to capture and release clots in the distal section.

[0083] A larger proximal porosity (i.e., larger proximal cells) provides a smaller strut area along the proximal portion of the device, making it less resistant to collapse as the engaging member 100 is retracted. Additionally, a generally tapered shape (e.g., increasing overall diameter from the proximal to distal end of the engaging member 100) may allow for smoother expansion and collapse of the engaging member 100 upon delivery and / or deployment from the delivery device 105, thereby aiding in the clot retrieval procedure.

[0084] The above-mentioned porosity can be adjusted by increasing or decreasing the number and / or size of each cell. In the pattern of FIG. 1-FIG. 3 as an example, the engagement member 100 may have a length of about 3 mm. The first plurality of cells 104A (e.g., four cells) at the distal end of the engagement member 100 has a cell size / diameter of about 0.5 mm. The second plurality of cells 104B (e.g., four cells) adjacent to the proximal side of the first plurality of cells 104A has a cell size / diameter of about 0.9 mm. The third plurality of cells 104C (e.g., four cells) adjacent to the proximal side of the second plurality of cells 104B has a cell size / diameter of about 2 mm. The fourth plurality of cells 104D (e.g., four cells) adjacent to the proximal side of the second plurality of cells 104C has a cell size / diameter of about 1.5 mm.

[0085] The size / diameter values ​​described herein are merely exemplary and should not be construed as limiting in scope. As described above and shown in the figures, it can be seen that the first (distal-most) plurality of cells 104A may have a size / diameter smaller than that of the second plurality of cells 104B, which may have a size / diameter smaller than that of the third plurality of cells 104C, which may have a size / diameter larger than that of the fourth plurality of cells 104D. Thus, it can be seen that from the distal end of the engagement member 100, the size / diameter of the cells 104A, 104B, 104C, 104D may be larger first and then smaller again at the proximal end.

[0086] Stated alternatively as a function of length, such as in one exemplary embodiment described above, the size / diameter of the first (distal-most) plurality of cells 104A may be equal to approximately 17% of the length of the engagement member 100, the size / diameter of the second plurality of cells 104B may be equal to approximately 30% of the length of the engagement member 100, the size / diameter of the third plurality of cells 104C may be equal to approximately 66% of the length of the engagement member 100, and the size / diameter of the fourth plurality of cells 104D may be equal to approximately 50% of the length of the engagement member 100.

[0087] In relative terms, in one exemplary embodiment, the first (distal-most) plurality of cells 104A may be approximately 55% of the size / diameter of the second plurality of cells 104B, which may be approximately 45% of the size / diameter of the third plurality of cells 104C, which may be approximately 133% of the size / diameter of the fourth plurality of cells 104D.

[0088] As another example, in the pattern of Figures 1-3, the engagement member 100 may have a length of about 6 mm. A first plurality of cells 104A (e.g., four cells) at the distal end of the engagement member 100 has a cell size / diameter of about 10 mm. A second plurality of cells 104B (e.g., four cells) proximally adjacent to the first plurality of cells 104A has a cell size / diameter of about 15 mm. A third plurality of cells 104C (e.g., four cells) proximally adjacent to the second plurality of cells 104B has a cell size / diameter of about 70 mm. A fourth plurality of cells 104D (e.g., four cells) proximally adjacent to the third plurality of cells 104C has a cell size / diameter of about 20 mm.

[0089] Stated alternatively as a function of length, such as in one exemplary embodiment described above, the size / diameter of the first (distal-most) plurality of cells 104A may be equal to approximately 166% of the length of the engagement member 100, the size / diameter of the second plurality of cells 104B may be equal to approximately 250% of the length of the engagement member 100, the size / diameter of the third plurality of cells 104C may be equal to approximately 1166% of the length of the engagement member 100, and the size / diameter of the fourth plurality of cells 104D may be equal to approximately 333% of the length of the engagement member 100.

[0090] Additionally, the porosity and performance characteristics of the engagement member 100 can be adjusted by increasing or decreasing the width of each strut 102 portion. The struts may be generally tapered, for example, decreasing in width toward the center of the engagement member 100. Specifically, the struts 102 may decrease in width from a first width at a proximal portion of the engagement member 100 forming cell 104D to a distal portion of the engagement member 100 forming cell 104C. Similarly, the struts 102 may decrease in width from a first width at a distal portion of the engagement member 100 forming cell 104A to a proximal portion of the engagement member 100 forming cell 104C.

[0091] In other words, the proximal struts may be thicker as the struts 102 approach the maximum outer diameter of the engagement member 100 and may taper toward the center of the hypotube to provide increased longitudinal stiffness without increasing radial or compliance forces when tensioned. The most distal struts 102 may return to a closed tube and form a pattern that tapers in the opposite direction to the proximal struts. The reduced stiffness at this location allows the struts 102 to bend inward from the distal closed portion and the engagement member 100 to occupy more intraluminal space since it is no longer entirely against the vessel wall. The large central opening allows clots to be absorbed into the engagement member 100 and captured by the distal end 113. The flexible proximal struts 102 may be held open in a parachute shape when tensioned due to the radial and longitudinal stiffness imbalance between the proximal and distal ends 111 and 113.

[0092] 1-2, the engagement member 100 may include one or more radiopaque markers 106. These markers 106 may be comprised of a radiopaque material disposed about a portion of one or more struts 102. Various types of radiopaque materials known in the art may be utilized. For example and without limitation, the radiopaque material may be comprised of tungsten, platinum-iridium, which is 90% platinum and the remainder iridium, gold, or similar materials.

[0093] The radiopaque material may be a wire as shown in Figures 1-2 wrapped around the strut 102, a wire coil, a wound ribbon, a sheet folded around the strut, or a hypotube disposed around the strut 102. Figures 9-10 show an exemplary embodiment of a marker 106A disposed around the strut 102. If desired, any of these forms of radiopaque markers 106, 106A may be further attached via adhesive, welding, or melting to form a bead. In another example, the radiopaque material may be comprised of a solid member that has been cut open (e.g., a horizontal cut is made in the material like a clamshell) and the member may be attached over the strut 102 and the opening closed by adhesive or welding to secure the radiopaque material to the strut 102.

[0094] Non-wire markers, such as sheets or hypotubes, may be designed with the least amount of material possible to reduce the amount of bending of the struts 102 within the catheter. Markers made from thin sheet material can be wrapped around the struts with one layer of marker on the outside of the hypotube and two or more layers on the inside of the hypotube, allowing the size of the marker to be increased without bending the struts too far away from the catheter liner, which could cause shortening or plastic deformation of the struts.

[0095] The struts 102 may also include one or more structural features or shapes that are useful for holding the radiopaque markers 106 in place. One example of such a structural feature is the "dogbone" strut shape 104E shown in Figures 4 and 5. The shape 104E forms an area of ​​increased width relative to adjacent areas at the proximal and distal ends of the strut 102. The expanded shape 104E may also have a greater width at the proximal and distal ends relative to the middle section. This may be in the form of a generally rectangular shape with a protrusion 104F such as a "bump" of expanded width at both ends, or a tapered hourglass shape with expanded ends. The expanded proximal and distal ends allow radiopaque material such as a radiopaque wire to be wrapped around the middle section and prevent it from slipping proximally or distally out of the shape 104E.

[0096] Figure 6 is a close-up view of an exemplary embodiment of the strut shape 104E shown in Figures 4-5. As shown in Figure 6, the strut shape 104E may be comprised of a central portion, a distal protrusion extending distally from the distal side of the central portion, and a proximal protrusion extending proximally from the proximal side of the central portion. The width of both the distal and proximal protrusions may be less than the width of the central portion to which they extend. As shown in Figure 6, the corners of the central portion may include protrusions 104F, such as ridges, bumps, or the like, that act as stops to prevent the markers 106 from sliding off the strut shape 104E.

[0097] An additional advantage of increasing the width of the strut shape 104E is that it may appear as a relatively large marker area in visualization techniques without requiring a relatively large amount of radiopaque material. In other words, the radiopaque material may be maintained as a thin layer over a larger surface area and may be well visualized, without requiring additional radiopaque material that would increase the compressed size or other performance characteristics of the device. In one example, the strut shape 104E may be about 0.2 mm in length, about 0.005 mm in mid-width, and about 0.007 mm in end width.

[0098] 4-5, the strut features 104E may be radially offset from one another such that the markers 106 do not contact one another when the engagement member 100 is in a radially compressed configuration. For example, two features 104E may be longitudinally offset from one another (e.g., the bottom two struts in FIG. 4) or may be located between two radially adjacent struts without such a feature 104E (e.g., the top three struts in FIG. 4).

[0099] 7-8 show another example configuration in which the diameter of region 104G of strut 102 may be smaller than the diameter of adjacent proximal and distal portions of strut 102. A radiopaque material, such as a radiopaque wire, may be wrapped around reduced diameter region 104G, thereby maintaining the profile of radiopaque marker 106 relatively small.

[0100] In the case of a single engagement member 100 or a distal engagement member 100 connected to multiple proximal engagement members 100, the distal end may include a radiopaque marker 110 as shown in Figure 11. The distal end may also be constructed from a radiopaque material such as, but not limited to, platinum.

[0101] 12-15 show an example of a process for making an exemplary embodiment of a radiopaque marker 110. First, a metal wire 110A (e.g., stainless steel) may be made having an extension or ball 110B on one end, as shown in FIG. 12. For example, the wire may have a length of about 0.040 inches to about 0.045 inches, an outer diameter of about 0.004 inches, and an outer diameter of the extension 110B of about 0.0011 inches. The wire 110A may be fed through a distal opening in the engagement member 100 such that the extension 110B is located proximally within the engagement member 100, as shown in FIG.

[0102] As shown in Figure 14, a hollow cylinder or marker tube 110C is fed over the wire 110A. The marker tube 110C may be constructed of a radiopaque material such as, but not limited to, an alloy of 90% platinum and 10% iridium, and in one example may have an outer diameter of about 0.015 inches, a length of 0.11 inches, a wall thickness of 0.003 inches, and an inner diameter of about 0.006 inches. A UV adhesive fillet may be applied on the distal surface of the extension 110B and the marker band 110C to form a smooth surface.

[0103] Finally, as shown in FIG. 15, the distal tip of the wire 110A may be welded to form a second distal enlargement 110D distal to the marker tube 110C to maintain the marker tube 110C in position at the distal end of the engagement member 100.

[0104] Once the Nitinol marker band is welded to the distal end of the stentriever, the Nitinol wire can have 0.005" to less than 0.015" of slack, allowing for smooth tracking and attachment of the marker within the microcatheter. The marker tube 110C and distal extension 110D can be further coated with UV adhesive if desired, which helps create a smooth surface.

[0105] The obstruction removal device 101 may also be configured with a mesh structure 120, which may be configured within the engagement member 100 as shown in Figures 16-17, or adjacent to the exterior of the engagement member 100 as shown in Figures 18-19. The mesh structure 120 may aid in the retention of embolic particles by acting as an additional filter that traps such embolic particles, minimizing the likelihood that these particles will be lost during the clot retrieval procedure.

[0106] The mesh structure 120 can be constructed of a single braid or multiple braids, such as Nitinol wire or a stretch-filled tube with an outer layer of Nitinol and an inner core of radiopaque material. The mesh structure 120 can be shape-set to expand into a desired three-dimensional shape, such as a sphere, a tapered ellipse, a disk, a cylinder, or a variety of other shapes. The mesh structure 120 can be a completely enclosed shape (e.g., a sphere) or can have openings that form a concave, cup, or similar shape. In such concave shapes, it may be desirable to position the concave openings distally to facilitate trapping emboli.

[0107] 16 illustrates an example embodiment of an engagement member 100 having an expandable three-dimensional mesh structure 120 therein. The distal and proximal ends of the mesh structure 120 may be internally coupled to the distal and proximal ends of the engagement member 100 such that both structures 100, 120 expand together. Thus, the mesh structure 120 may aid in the expansion of the engagement member 100 and aid in resistance to collapse.

[0108] Although the embodiment of mesh structure 120 in FIG. 16 is illustrated as having a longitudinally symmetric shape (e.g., an oval shape tapered at both ends), mesh structure 120 may alternatively have a longitudinally asymmetric shape similar to engagement member 100 shown in FIG.

[0109] 17 illustrates another exemplary embodiment in which the mesh structure 120 is disposed only partially within the engagement member 100, specifically only in the distal portion or half. However, in some embodiments, the mesh structure 120 may alternatively be disposed only in the proximal portion or half.

[0110] 17, the mesh structure 120 may expand into a generally rounded cylindrical shape, although a variety of different shapes are possible. Distal placement of the mesh structure 120 allows for more effective capture of emboli while leaving the intermediate and proximal portions of the engagement member 100 free for emboli to easily enter the interior of the engagement member 100.

[0111] 18-19 show an exemplary embodiment in which mesh structure 120 may be disposed externally relative to engagement member 100. By way of example, mesh structure 120 may be disposed proximal to engagement member 100 and, if desired, distal to another engagement member 100. The distal end of mesh structure 120 may be coupled to the proximal end of engagement member 100, and, if desired, the two structures may be rotatable relative to one another.

[0112] Additionally, mesh structure 120 may have a uniform pore size / porosity along its length or may have different pore sizes after expansion. For example, the distal end may have smaller pore sizes as shown in FIG. 20, and the middle portion may have smaller pore sizes than the proximal or distal ends as shown in FIG. 21.

[0113] As one example, different void sizes can be achieved by using different braid patterns along the mesh structure 120. For example, in the embodiment of Figures 20-21, the braid patterns can be switched to increase areas of different PPI ("Picks per inch"), or as shown in Figure 22, portions of the mesh structure 120 can be co-knitted to reduce voids in different areas (e.g., the middle of the figure).

[0114] In another example, the mesh structure 120 may be partially shape set to achieve different porosities with the same or different braid patterns, such as to create regions that expand or contract more longitudinally when the mesh structure 120 is expanded.

[0115] In another example, portions of the mesh structure can be removed or trimmed to reduce porosity in desired areas, which is particularly useful when creating a concave or cup-shaped mesh structure 120.

[0116] Engagement member 100 may also include one or more support structures within its structure to improve expansion and help resist collapse, especially around highly curved portions of a vessel, and may be supported by any of mesh structures 120, as previously described.

[0117] As shown in FIGS. 23-24, the engagement member 100 may include one or more support wires 130. Such one or more support wires 130 may be utilized in place of or in addition to the mesh structure 120. The one or more support wires 130 may be heat set into an expanded three-dimensional shape that is equal to or larger than the inner diameter of the engagement member 100, thereby forcing the engagement member 100 radially outward. The shape of the one or more support wires 130 when expanded may vary in different embodiments and should not be construed as limited by the exemplary embodiment shown in the figures. In one exemplary embodiment, the one or more support wires 130 may be expanded in a helical or coiled shape.

[0118] The one or more supporting wires 130 may form a variety of different shapes. For example, the wires 130 may form a generally helical shape, as shown in Figures 23-24. Alternatively, the one or more supporting wires 130 may form one or more discrete circular shapes oriented perpendicular to the axis of the engagement member 100.

[0119] 25A-25C illustrate an exemplary method of forming an engagement member 100. As illustrated, one or more fasteners 140 may be used. First, an initial shape is formed from a tubular member, such as a wire braid or hypotube. One or more fasteners 140 may then be placed inside the initial tubular shape to form the asymmetric shape described and illustrated herein. As an example, fasteners 140 may be placed within either end of the tubular member to form a taper before heat setting into the final expanded shape as shown in FIGS. 25A and 25B.

[0120] Figure 25C illustrates the use of two separate fasteners 140A, 140B, with the first fastener 140A having a smaller diameter or width than the second fastener 140B. The use of multiple fasteners 140A, 140B may be desirable in situations where a single fastener 140 will not fit within the tubular member. In the embodiment shown in Figure 25C, the first fastener 140A may comprise a spacer plunger and the second fastener 140B may comprise an extension plate.

[0121] Terms:

[0122] Embodiments are described in the following numbered clauses:

[0123] Item 1. A method for removing an obstruction may include advancing one or more engagement members from a delivery catheter. Each of the one or more engagement members is comprised of a plurality of struts forming a plurality of open cells. The one or more engagement members have a radially compressed configuration and a radially expanded configuration. The radially expanded configuration forms a longitudinally asymmetric shape having a distal region of a larger diameter than an intermediate region and a proximal region. The method further includes engaging the obstruction with the one or more engagement members.

[0124] Item 2. A method of manufacturing an obstruction removal system may include forming one or more engagement members. Each of the one or more engagement members includes a plurality of struts and a plurality of open cells. The one or more engagement members have a radially expanded configuration and a radially compressed configuration. The radially expanded configuration forms a longitudinally asymmetric shape having a distal region of greater diameter than an intermediate region and a proximal region. Further, the method includes coupling at least one of the one or more engagement members to an elongate member.

[0125] Item 3. A method of manufacturing an obstruction removal system may include providing an engagement member comprising a plurality of struts forming a plurality of open cells, at least one of the struts having an expanded width region forming a dogbone shape, and applying a radiopaque material to a central portion of the dogbone shape.

[0126] Item 4. A method of manufacturing an obstruction removal system may include providing an engagement member comprising a plurality of struts forming a plurality of open cells, at least one of the struts having a region of reduced width, and applying a radiopaque material around the region of reduced width.

[0127] Item 5. A method of manufacturing an obstruction removal system may include providing an engagement member comprising a plurality of struts forming a plurality of open cells, advancing a wire through a distal end of the engagement member, placing a radiopaque tube on the wire, and forming an enlarged portion at the distal end of the wire.

[0128] Item 6. A method of manufacturing an obstacle removal system may include providing an engagement member comprising a plurality of struts forming a plurality of open cells, and connecting a mesh structure to the obstacle removal system or positioning the mesh structure proximate to the obstacle removal system.

[0129] Clause 7. The method of clause 6, wherein the mesh structure is at least partially connected within the engagement member.

[0130] Item 8. The method of item 6, wherein the mesh structure is disposed on the exterior of the engagement member.

[0131] Item 9. A method of manufacturing an obstacle removal system may include providing an engagement member comprising a plurality of struts forming a plurality of open cells, and further connecting a support wire within the obstacle removal system configured to expand against an interior of the engagement member.

[0132] It should be noted that any of the embodiments, features, or details herein may be used in combination with one another. In other words, although certain features have been described individually, it is contemplated that any combination of these features may be combined with one another. Thus, this specification includes embodiments having any combination of the features described herein.

[0133] Although the present invention has been described with respect to specific embodiments and applications, those skilled in the art may, in light of this teaching, generate additional embodiments and modifications without departing from the spirit or beyond the scope of the claimed invention. It is therefore to be understood that the drawings and descriptions herein are presented by way of example to facilitate understanding of the present invention and should not be construed as limiting its scope.

Claims

1. An obstacle removal system, comprising: an elongated member; and an engagement member formed as an integral continuum and having a plurality of open cells, wherein the engagement member has a radially compressed configuration and a radially expanded configuration, and the radially expanded configuration forms a longitudinally asymmetric shape having a distal region with a diameter larger than that of an intermediate region and a proximal region. An obstacle removal system characterized by this.

2. The obstacle removal system according to claim 1, wherein the plurality of open cells have a porosity lower than that of the intermediate region in the distal region.

3. The obstacle removal system according to claim 1, wherein the engagement member is composed of a plurality of struts.

4. The obstacle removal system according to claim 3, wherein the plurality of struts are tapered to a reduced width from the proximal region or the distal region of the engagement member.

5. The obstacle removal system according to claim 3, wherein at least one of the plurality of struts includes a region with a reduced width, and further includes a radiopaque material disposed on or around the region with the reduced width.

6. The obstacle removal system according to claim 3, wherein at least one of the plurality of struts includes a central portion, a proximal protrusion extending outward from a proximal end of the central portion, and a distal protrusion extending outward from a distal end of the intermediate region, and the central portion is narrower in width than the proximal protrusion and the distal protrusion.

7. The obstacle removal system according to claim 6, further comprising a radiopaque material disposed on or around the intermediate region in at least one of the plurality of struts.

8. The obstacle removal system according to claim 1, wherein the engagement member includes a radiopaque distal tip.

9. The obstacle removal system according to claim 8, wherein the radiopaque distal tip includes a wire disposed around the distal end of the engagement member.

10. The obstacle removal system according to claim 1, further comprising a mesh structure connected to the engagement member.

11. The obstacle removal system according to claim 10, wherein the mesh structure is disposed within the engagement member.

12. The obstacle removal system according to claim 10, wherein the mesh structure is disposed adjacent to the outside of the engagement member. **Claim 13** The obstacle removal system according to claim 1, further comprising a support wire disposed within the engagement member. **Claim 14** The obstacle removal system according to claim 1, further comprising a second engagement member disposed distally to the engagement member, wherein the width of the second engagement member is smaller than the width of the engagement member. **Claim 15** The obstacle removal system according to claim 14, further comprising a third engagement member disposed distally to the second engagement member, wherein the width of the third engagement member is smaller than the width of the second engagement member.

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