Patent Publication Number: US-11045215-B2

Title: Vascular device visibility

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     The present application is a continuation of U.S. application Ser. No. 15/043,466, filed Feb. 12, 2016, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Blood vessels can become occluded by emboli, e.g., thrombi. For example, intracranial arteries can become occluded by thromboembolisms. Disruption of blood flow by the occlusion can prevent oxygen and nutrients from being delivered to tissues downstream of the occlusion. Deprivation of oxygen and nutrients to tissue distal to an occlusion can impair proper function of the tissue, and may result in cellular death. Cellular death increases with duration of the occlusion. 
     SUMMARY OF THE DISCLOSURE 
     Markers can be used to assist an operator in determining the location and/or orientation of a medical device within a blood vessel. Some aspects of the subject technology relate to attachment of a marker to a thrombectomy or other medical device. Some aspects of the subject technology relate to the positioning of one or more markers on a thrombectomy device. Some aspects of the subject technology relate to the use of markers in methods for removing thrombus from a blood vessel. 
     The subject technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the subject technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the subject technology. It is noted that any of the dependent clauses may be combined in any combination, and placed into a respective independent clause, e.g., clause 1, 12, 16, or 24. The other clauses can be presented in a similar manner. 
     1. A medical device comprising:
         an elongate manipulation member; and   a thrombectomy device connected to the elongate manipulation member, the thrombectomy device having a first configuration and a second configuration, the thrombectomy device being expandable from the first configuration to the second configuration; the thrombectomy device comprising a plurality of arcuate marker-mounting projections each attached to a portion of the thrombectomy device configured to contact a thrombus and arranged such that any laterally aligned arcuate marker-mounting projections are disposed laterally farther from each other when the thrombectomy device is in the second configuration than they are when the thrombectomy device is in the first configuration.       

     2. The medical device of clause 1, wherein each of the arcuate marker-mounting projections comprises a concave surface. 
     3. The medical device of clause 2, wherein the concave surface faces away from the portion of the thrombectomy device configured to contact the thrombus to which the arcuate marker-mounting projection is attached. 
     4. The medical device of clause 2, wherein each of the arcuate marker-mounting projections comprises a convex surface opposite the concave surface. 
     5. The medical device of clause 4, wherein the convex surface is parallel to the concave surface. 
     6. The medical device of clause 1, wherein the thrombectomy device comprises a plurality of struts forming a plurality of cells, and each of the arcuate marker-mounting projections extends from one of the struts. 
     7. The medical device of clause 6, wherein each of the arcuate marker-mounting projections is separated from all of the other arcuate marker-mounting projections by at least one strut length. 
     8. The medical device of clause 1, further comprising a plurality of markers, each marker being attached to only one of the arcuate marker-mounting projections. 
     9. The medical device of clause 1, wherein at least one of the marker-mounting projections is disposed at a proximal end of a working length of the thrombectomy device. 
     10. The medical device of clause 9, wherein the least one of the marker-mounting projection is within 5 millimeters of the proximal end of the working length. 
     11. The medical device of clause 1, wherein a group of marker-mounting projections is disposed at a proximal end of a working length of the thrombectomy device. 
     12. A medical device comprising:
         an elongate manipulation member;   a thrombectomy device connected to the elongate manipulation member; an arcuate marker-mounting projection extending from a portion of the   thrombectomy device configured to contact a thrombus; and   a marker coupled to, and extending around, the arcuate marker-mounting projection with the marker and the arcuate marker-mounting projection contacting each other at three discrete locations.       

     13. The medical device of clause 12, wherein the marker and the marker-mounting projection contact each other at one location on a convex side of the arcuate marker-mounting projection, and the marker and the arcuate marker-mounting projection contact each other at two locations on a concave side of the marker-mounting projection. 
     14. The medical device of clause 13, wherein the one contact location on the convex side is between the two contact locations on the concave side. 
     15. The medical device of clause 13, wherein the convex side of the arcuate marker-mounting projection and the concave side of the marker-mounting projection are parallel. 
     16. A method for engaging a thrombus, the method comprising:
         (a) advancing a thrombectomy device, using an elongate manipulation member, to a location radially adjacent to a thrombus in a blood vessel, the thrombectomy device comprising a working length and a non-working length, the non-working length disposed between and separating the working length and a connection between the thrombectomy device and the elongate manipulation member, the working length having a proximal end and a distal end with a proximal marker disposed at the proximal end, and a distal marker, discrete from the proximal marker, disposed at the distal end;   (b) positioning the thrombectomy device relative to the thrombus such that the proximal marker is proximal to or longitudinally aligned with a proximal end of the thrombus and the distal marker is distal to or longitudinally aligned with a distal end of the thrombus; and   (c), after (b), expanding the thrombectomy device into the thrombus.       

     17. The method of clause 16, wherein a plurality of proximal markers are disposed at the proximal end of the working length and a plurality of distal markers are disposed at the distal end of the working length, and wherein positioning the thrombectomy device relative to the thrombus comprises positioning all of the proximal markers proximal to or longitudinally aligned with a proximal end of the thrombus and all of the distal markers distal to or longitudinally aligned with a distal end of the thrombus. 
     18. The method of clause 17, wherein a plurality of intermediate markers is attached to the thrombectomy device between the plurality of proximal markers and the plurality of distal markers, the method further comprising determining whether a maximum marker separation of the plurality of intermediate markers is less than a maximum marker separation of either the plurality of proximal markers or the plurality of distal markers. 
     19. The method of clause 18 wherein, when the maximum marker separation of the plurality of intermediate markers is not less than the maximum marker separation of either the plurality of proximal markers or the plurality of distal markers, the method further comprises:
         collapsing the thrombectomy device;   repositioning the thrombectomy device relative to the thrombus such that the proximal marker is proximal to or longitudinally aligned with a proximal end of the thrombus and the distal marker is distal to or longitudinally aligned with a distal end of the thrombus; and   re-expanding the thrombectomy device into the thrombus.       

     20. The method of clause 18 further comprising determining a state of expansion of the working length by observing the proximal, intermediate and distal pluralities of markers. 
     21. The method of clause 16, wherein the proximal marker is located within 5 millimeters of the proximal end of the working length. 
     22. The method of clause 21, wherein the thrombectomy device includes a plurality of cells, and wherein the proximal marker grouping is located within one cell-length of the proximal end of the working length. 
     23. The method of clause 21, wherein the thrombectomy device includes a generally cylindrical structure having a roll-up configuration. 
     24. A method for engaging a thrombus, the method comprising: 
     advancing a thrombectomy device, using an elongate manipulation member, to a location radially adjacent to a thrombus in a blood vessel, the thrombectomy device comprising a working length having a proximal end and a distal end with a proximal marker disposed at the proximal end; 
     positioning the thrombectomy device relative to the thrombus such that the proximal marker is proximal to or longitudinally aligned with a proximal end of the thrombus; and 
     (c), after (b), expanding the thrombectomy device into the thrombus. 
     25. The method of clause 24, wherein the thrombectomy device further comprises a non-working length, the non-working length disposed between and separating the working length and a connection between the thrombectomy device and the elongate manipulation member, the proximal marker being located distal of the connection. 
     26. The method of clause 24, further comprising imaging the proximal end of the working length distinctly from the connection with the proximal marker. 
     27. The method of clause 24, wherein the thrombectomy device further comprises a distal marker, discrete from the proximal marker, disposed at the distal end of the working length. 
     28. The method of clause 27, further comprising positioning the thrombectomy device such that the distal marker is distal to or longitudinally aligned with a distal end of the thrombus. 
     29. The method of clause 27, wherein the thrombectomy device has a body comprising a plurality of struts, and the distal and proximal markers are more radiopaque than the body. 
     30. The method of clause 24, wherein a plurality of proximal markers are disposed at the proximal end of the working length, and wherein positioning the thrombectomy device relative to the thrombus comprises positioning all of the proximal markers proximal to or longitudinally aligned with a proximal end of the thrombus. 
     31. The method of clause 30, wherein a plurality of intermediate markers is attached to the thrombectomy device distal of the plurality of proximal markers, the method further comprising determining whether a maximum marker separation of the plurality of intermediate markers is less than a maximum marker separation of the plurality of proximal markers. 
     32. The method of clause 31, wherein, when the maximum marker separation of the plurality of intermediate markers is not less than the maximum marker separation of the plurality of proximal markers, the method further comprises:
         collapsing the thrombectomy device;   repositioning the thrombectomy device relative to the thrombus such that the proximal marker is proximal to or longitudinally aligned with a proximal end of the thrombus; and   re-expanding the thrombectomy device into the thrombus.       

     Additional features and advantages of the subject technology will be set forth in the description below, and in part will be apparent from the description, or may be learned by practice of the subject technology. The advantages of the subject technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplifying and explanatory and are intended to provide further explanation of the subject technology as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide further understanding of the subject technology and are incorporated in and constitute a part of this description, illustrate aspects of the subject technology and, together with the specification, serve to explain principles of the subject technology. 
         FIG. 1  illustrates a medical device including a thrombectomy device, according to an embodiment. 
         FIG. 2  is a schematic illustration of overlap configurations of the thrombectomy device of  FIG. 1 . 
         FIG. 3  illustrates an exemplifying thrombectomy device in an unrolled state. 
         FIG. 4  illustrates another exemplifying thrombectomy device in an unrolled state. 
         FIG. 5  is an enlarged view of a marker-mounting projection of the thrombectomy device shown in the area  5 - 5  of  FIG. 4 . 
         FIG. 6  illustrates the marker-mounting projection of  FIG. 5  together with a marker. 
         FIG. 7  is a schematic representation of a fluoroscopic image of an arrangement of markers when a thrombectomy device to which they are attached is in an unexpanded state. 
         FIG. 8  is a schematic representation of a fluoroscopic image of the markers of  FIG. 7  when the thrombectomy device to which they are attached is in a fully expanded state. 
         FIG. 9  is a schematic representation of a fluoroscopic image of the markers of  FIG. 7  when the thrombectomy device to which they are attached is partially expanded within a vessel and in contact with a thrombus. 
         FIGS. 10-13  are cross-sectional views of a blood vessel and illustrate a processes of advancing and positioning a medical device, according to some embodiments. 
         FIGS. 14-16  are cross-sectional views of the blood vessel shown in  FIGS. 10-13 , and illustrate various clot positions and thrombectomy device configurations, according to some embodiments. 
         FIGS. 17-20  are cross-sectional views of a blood vessel and illustrate uses of a medical device according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE SUBJECT TECHNOLOGY 
     The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. However, the subject technology may be practiced without these specific details. In some instances, well-known structures and components are shown schematically to avoid obscuring the concepts of the subject technology. 
       FIG. 1  depicts an exemplifying medical device  100  according to some embodiments of the subject technology. As illustrated in  FIG. 1 , the medical device  100  can comprise a vascular device or thrombectomy device  102  and a manipulation member  104 .  FIG. 1  also illustrates markers  150  attached to the thrombectomy device  102 . A proximal end portion of the thrombectomy device  102  and a distal end portion of the manipulation member  104  can be joined at a connection  106 . The manipulation member  104  can extend through a catheter  107  such that an operator can manipulate the thrombectomy device  102 , positioned within and/or distal to a distal end of the catheter  107 , using the manipulation member  104  at a location proximal to a proximal end of the catheter  107 . 
     The manipulation member  104  can be an elongate manipulation member. The manipulation member  104  can have a length sufficient to extend from a location outside the patient&#39;s body through the vasculature to a treatment site within the patient&#39;s body. For example, the manipulation member can have a length of at least 100 cm, at least 130 cm, or at least 150 cm. The manipulation member  104  can be monolithic or formed of multiple joined components. In some embodiments, the manipulation member  104  can comprise a combination of wire(s), coil(s), and/or tube(s). 
     The thrombectomy device  102  and the manipulation member  104  can be attached together at the connection  106 . In some embodiments, the thrombectomy device  102  and the manipulation member  104  can be substantially permanently attached together at the connection  106 . That is, the thrombectomy device  102  and the manipulation member  104  can be attached together in a manner such that, under the expected use conditions of the medical device  100 , the endovascular device and the manipulation member would not become separated, whether deliberately or unintentionally, from one another without damage to or destruction of at least a portion of the connection  106 . In some embodiments, the thrombectomy device  102  and the manipulation member  104  can be permanently or releasably attached together at the connection  106 . 
     In some embodiments, the connection  106  can comprise a marker. The marker of the connection can comprise a radiopaque material such as platinum, iridium, tantalum, gold, alloys thereof or bismuth and tungsten-doped polymers, among other materials. The connection marker can be more radiopaque than a body of the vascular or thrombectomy device  102 . The connection marker can be visible under fluoroscopy, CAT scans, X-Rays, Mill, ultrasound technology or other types of imaging. The connection marker can include an interior channel, an interior recess or another mounting feature. Further, the connection marker can comprise a band or substantially cylindrical shape with an open or closed circumference, a coil, or other form. 
     It optionally may be advantageous to have a connection mechanism that permits intentional release of the thrombectomy device  102 . For example, during a blood flow restoration procedure, it may prove difficult and/or dangerous to fully retrieve a thrombus due to a complicated vasculature or the risk of damaging a lumen wall. Leaving the thrombectomy device  102  inside the patient may prove to be the only option available to a surgeon or other medical personnel, or it may be a goal of the procedure, such as when the thrombectomy device  102  is deployed across an aneurysm (e.g., as an aneurysm bridge to retain coils or other materials in an aneurysm). In other circumstances the thrombectomy device  102  may include drug-eluting capabilities, and/or may be coated with a particular type of drug that facilitates thrombus dissolution. It may be advantageous in such circumstances to release the thrombectomy device  102  and allow the thrombectomy device  102  to anchor the thrombus against the lumen wall while the thrombus is dissolved by the drug. In some embodiments, the medical device  100  can comprise a portion, located proximally or distally of the connection  106 , that is configured for selective detachment of the thrombectomy device  102  from the manipulation member  104 . For example, such a portion can comprise an electrolytically severable or mechanically detachable segment of the manipulation member. In some embodiments, the medical device  100  can be devoid of any feature that would permit selective detachment of the thrombectomy device  102  from the manipulation member  104 . 
     As illustrated in  FIGS. 1 and 2 , the thrombectomy device  102  can have a tubular or generally cylindrical shape in the absence of external forces in some embodiments. However, in some embodiments, the thrombectomy device can have a shape that is neither tubular nor cylindrical. In some embodiments, the thrombectomy device can have open proximal and distal ends, for example as illustrated in  FIGS. 1 and 2 , while in other embodiments, the thrombectomy device can have closed proximal and/or distal ends. In some embodiments, the thrombectomy device can comprise a series of structures (e.g., a longitudinal series of structures) each having proximal and distal ends that are open or closed. In some embodiments, the thrombectomy device can comprise a tubular or cylindrical structure disposed within, around, or radially overlapping such a series of structures or one or more other tubular or cylindrical structure(s). The thrombectomy device  102  can be self-expanding, e.g. by super-elasticity or shape memory, or expandable in response to forces applied on the expandable member, e.g. by a balloon. 
     As shown in  FIGS. 1 and 2 , the thrombectomy device  102  in some embodiments can be curled, rolled, or otherwise formed such that a first edge  124  and a second edge  126  overlap one another, or form a gap between each other, when the thrombectomy device  102  is in a volume-reduced form. In a volume-reduced form, or an unexpanded form, the thrombectomy device  102  illustrated in  FIGS. 1 and 2  can overlap itself to facilitate introduction of the thrombectomy device  102  into and through the catheter  107 .  FIG. 2  is a schematic illustration of overlap configurations (e.g., various amounts of overlap) of the thrombectomy device of  FIG. 1 .  FIG. 2  illustrates various amounts of overlap of the thrombectomy device  102 , forming zones of overlap  128 . The thrombectomy device  102  can assume various diameters  41 ,  42 , etc., depending on the degree of the overlap (e.g. represented by angle α 1 , α 2 , etc.). The extent of any overlap of a frame  108  of the vascular or thrombectomy device can depend upon a degree of the frame&#39;s expansion. Expansion within a vessel can be limited, at least in part, by the vessel&#39;s size, and the amount and the properties of any thrombus present. For example, a greater overlap of the edges  124 ,  126  can occur in narrower vessels, whereas in wider vessels the overlap can be smaller, or even an “underlap” may occur, in which case the edges  124  and  126  are separated by an open gap or space within the vessel. Advantageously, the presence of an overlap or “roll-up” configuration allows the thrombectomy device to be expanded or compressed in diameter with little or no change in length (e.g. foreshortening during expansion), in comparison to a similar device that lacks the overlap or roll-up configuration. This is because the expansion or compression can result from a decrease or increase in degree of overlap (see  FIG. 2 ) rather than wholly from deformation of the struts  114  and cells  116  ( FIG. 3 ), which deformation can decrease or increase the length of the device when transitioning to the expanded or compressed state. 
     In some embodiments, the thrombectomy device  102  is circumferentially continuous (e.g., forming a circumferentially continuous tubular or cylindrical shape), lacking first and second edges  124 ,  126  and having no overlap or gap in a volume-reduced form and expanded form. Regardless of whether the thrombectomy device is circumferentially continuous, the thrombectomy device  102  can have a central longitudinal axis both while in a volume-reduced form and when fully or partially expanded. In some embodiments, the thrombectomy device  102  can be self-expandable, and can expand toward a fully expanded configuration upon release from the catheter  107 . Upon expansion, the thrombectomy device  102  can expand towards an inner wall of a vessel, towards an occlusive or partially-occlusive thrombus, clot or embolus within a vessel, or both. 
     The thrombectomy device  102  can be oversized relative to the interior of a vessel in which it is to be used, or the thrombectomy device  102  can occupy a larger volume when allowed to expand outside a vessel than when allowed to expand inside a vessel. In other words, the vessel may prevent a complete expansion of some or all of the thrombectomy device  102 . 
     Upon thrombectomy device  102  expansion into an expanded configuration, portions of the thrombectomy device can to penetrate into a thrombus, capture a thrombus, or both. In some embodiments, the thrombectomy device  102  can capture the thrombus with an exterior, or radial exterior, of the expanded thrombectomy device  102 . Additionally or alternatively, in some embodiments, the thrombectomy device  102  may contact, interlock, capture or engage with a portion of the thrombus with an interior, or radial interior, of the expanded thrombectomy device  102 . 
     The thrombectomy device can comprise a working length and a non-working length. The portion of the thrombectomy device  102  in the working length is configured to interlock, capture or engage a thrombus. The portion of the thrombectomy device in the non-working length may contact thrombotic material in use, but is configured to perform a function that renders it ineffective or less effective other than the working length for interlocking, capturing or engaging with a thrombus. In some embodiments, the non-working length is disposed between the working length and the connection  106  to the manipulation member  104 . 
     In some embodiments, the working length of the thrombectomy device  102  can comprise a repeating pattern of structural features. For example, a working portion of the thrombectomy device  102  illustrated in  FIGS. 1 and 2  comprises a matrix of cells. Nonetheless, in some embodiments the repeating pattern of structural features can have other forms. 
       FIG. 3  illustrates an exemplifying the vascular device or thrombectomy device  102  in a flat configuration to facilitate understanding of various features present in some thrombectomy devices according to various embodiments. The thrombectomy device  102  illustrated in  FIG. 3  includes a working length  144  and a non-working length  145 . As illustrated in  FIG. 3 , for example, the non-working length  145  is disposed between the working length  144  and the connection  106  to the manipulation member  104 . 
     As illustrated in  FIG. 3 , in some embodiments, the thrombectomy device can comprise a frame or body  108  having a plurality of struts  114  and a plurality of cells  116 , forming a mesh. Groups of longitudinally and serially interconnected struts  114  can form undulating members  118  that extend in a generally longitudinal direction. The struts  114  can be connected to each other by joints  120 . While the struts are shown having a particular undulating or sinuous configurations, in some embodiments the struts can have other configurations. The frame of the thrombectomy device can have a generally tubular or generally cylindrical shape in some embodiments, while in others the frame can have a shape that is neither tubular nor cylindrical. 
     The working length  144  of the thrombectomy device illustrated in  FIG. 3  comprises some of the cells  116 . In embodiments wherein the thrombectomy device  102  comprises cells, the cells  116  in the working length and the portion of the thrombectomy device that form them can be sized and shaped such that they penetrate into a thrombus, capture a thrombus, or both upon expansion of the working length into a thrombus. In some embodiments, the portion of the thrombectomy device  102  in the working length can capture the thrombus with the individual cells  116  and/or with an exterior, or radial exterior, of the expanded thrombectomy device  102 . Additionally or alternatively, in some embodiments, the portion of the thrombectomy device  102  in the working length may contact, interlock, capture or engage with a portion of the thrombus with individual cells  116  and/or an interior, or radial interior, of the expanded thrombectomy device  102 . 
     As illustrated in  FIG. 3 , for example, the non-working length can comprise a tapered proximal portion  122  of the thrombectomy device  102 . The proximal portion  122  of the thrombectomy device  102  can be tapered toward a proximal end  110  of the thrombectomy device  102 . In some embodiments, the taper of the proximal, non-working portion  122  can advantageously facilitate retraction and repositioning of the medical device  100  and thrombectomy device  102 . For example, in some embodiments, the non-working length  145  facilitates a retraction of the thrombectomy device  102  into the catheter  107 . 
     In some embodiments, the tapered proximal, non-working portion  122  can be additionally or alternatively designed to generally not contact the vessel wall during a blood flow restoration procedure, and to generally not interfere with the flow of blood within a vessel. 
     The taper of proximal portion  122  can be at various angles relative to the manipulation member  104  or the longitudinal axis of the thrombectomy device  102 . For example, in some embodiments, the taper can have an angle of approximately 45 degrees relative to the manipulation member, though other angles are also possible, and within the scope of the present disclosure. 
     The thrombectomy device  102  can comprise a first edge  124  and a second edge  126 . The first edge  124  and second edge  126  can be formed, for example, from cutting a sheet or a tube. While the first and second edges are shown as having an undulating, or sinuous configuration, in some embodiments the first and second edges can have a straight, or linear configuration, or other configuration. In some embodiments, the edges  124 ,  126  can be curved, straight, or a combination thereof along the tapered proximal portion  122 . 
     Each cell  116  of the thrombectomy device  102  can have a maximum length (labeled “L” in  FIG. 3 ), as measured along a longitudinal axis of the thrombectomy device  102 , and a maximum width W, as measured along a direction generally perpendicular to the length (labeled “W” in  FIG. 3 ).  FIG. 3  illustrates an embodiment of the thrombectomy device  102  having a pattern  130  of cells  116  of substantially uniform dimensions and struts  114  of substantially uniform dimensions. Nonetheless, in some embodiments, cell size and dimensions can vary along the length and wide of the frame  108 , as can the individual filament thicknesses and widths. 
       FIG. 3  also illustrates a plurality of marker-mounting projections  148 . Each marker-mounting projection  148  can be attached to a portion of the thrombectomy device  102  that may contact thrombus during use of the thrombectomy device. In some embodiments, the marker-mounting projections  148  can be attached to portions of the thrombectomy device  102  in the working length  144 , for example as illustrated in  FIG. 3 . In embodiments wherein the thrombectomy device comprises struts  114 , the marker-mounting projection(s)  148  can be attached to a strut  114 . The marker-mounting projection  148  can be disposed within a cell  116 , if present, or on another surface of the thrombectomy device  102 . In some embodiments, a plurality of marker-mounting projections  148  can be attached respectively to a plurality of struts  114 . In some embodiments, some or all of the marker-mounting projections  148  can each be attached to and/or at only a single strut  114 . In some embodiments, the marker-mounting projection  148  can be attached to and/or at a joint  120 . In some embodiments, the marker-mounting projections  148  can be separated from all other marker-mounting projections  148  by a distance, for example at least 2 mm or at least 3 mm, in a fully expanded configuration of the thrombectomy device  102 . In some embodiments, the marker-mounting projections  148  can be separated from all other marker-mounting projections  148  by one cell width or one strut length (e.g., an entire length of a strut separates the adjacent marker-mounting projections). 
     One or more marker-mounting projections  148  can be located at some or all of a proximal end  146  of the working length  144 , a distal end  147  of the working length  144 , or an intermediate area  149  of the working length  144  between the proximal end  146  and the distal end  147 . The working length  144  can extend continuously or intermittently between the proximal end  146  and the distal end  147 . 
     In some embodiments, the proximal end of the working length can be at a proximalmost location where the thrombectomy device forms a complete circumference. In some embodiments, the proximal end of the working length can be at a proximalmost location where the thrombectomy device has its greatest transverse dimension in a fully expanded state. In some embodiments, the proximal end of the working length can be at a proximalmost location where the thrombectomy device has a peak, crown, or crest in transverse dimension in a fully expanded state. 
     In some embodiments, the distal end of the working length can be at a distalmost location where the thrombectomy device forms a complete circumference. In some embodiments, the distal end of the working length can be at a distalmost location where the thrombectomy device has its greatest transverse dimension in a fully expanded state. In some embodiments, the distal end of the working length can be at a distalmost location where the thrombectomy device has a peak, crown, or crest in transverse dimension in a fully expanded state. 
     In some embodiments, a marker-mounting projection  148  located at the proximal end  146  can be disposed within 5 mm, within 4 mm, within 3 mm, within 2 mm, or within 1 mm, proximally or distally, of the proximal end  146 . In some embodiments, a marker-mounting projection  148  located at the proximal end  146  can be disposed within the length of one cell or one strut, proximally or distally, of the proximal end  146 . 
     In some embodiments, a marker-mounting projection  148  located at the distal end  147  can be disposed within 5 mm, within 4 mm, within 3 mm, within 2 mm, or within 1 mm, proximally or distally, of the distal end  147 . In some embodiments, a marker-mounting projection  148  located at the distal end  147  can be disposed within the length of one cell or one strut, proximally or distally, of the distal end  147 . 
     A plurality or group of marker-mounting projections  148  can be located at some or all of the proximal end  146 , the distal end  147 , or the intermediate area  149 . In some embodiments, the plurality or group of marker-mounting projections  148  at each of these locations (if present) have a common pattern. For example, the projections  148  in the plurality or group at the proximal end  146  can have the same arrangement relative to each other as do the projections  148  in the plurality or group at the distal end  147 . The projections  148  in the plurality or group at intermediate area  149  (if present) can have the same arrangement relative to each other as do the projections  148  in the plurality or group at each of the proximal end  146  and the distal end  147 , for example as illustrated in  FIG. 3 . In some embodiments, the marker-mounting projections  148  of such a plurality or group of marker-mounting projections  148  can be disposed farther from each other when the thrombectomy device  102  is in an expanded configuration that they are when the thrombectomy device  102  is in an unexpanded or less expanded configuration. 
     In some embodiments, the vascular or thrombectomy device  102  can comprise one or more distally extending tips extending from a distal end of the thrombectomy device. For example, the device illustrated in  FIG. 3  is shown comprising four elongate, distally extending tips  154  extending from a distal end of the thrombectomy device  102 . In some embodiments wherein the thrombectomy device comprises struts, these distal tips  154  can extend from a distalmost row of struts, for example as illustrated in  FIG. 3 . In some embodiments, one or more markers  150  can be attached to the distal tips  154 , if present. In some embodiments wherein one or more markers  150  are attached to the distal tips, the marker(s)  150  on the distal tips  154  can be positioned at the distal end  147  of the working length  144 , for example as illustrated in  FIG. 3 .  FIG. 4  illustrates another exemplifying the thrombectomy device  102  in a flat configuration to facilitate understanding of various features present in some thrombectomy devices according to various embodiments.  FIG. 4  shows sets of marker-mounting projections  148  arranged or laterally aligned such that they lie along straight lines R 1 , R 2 , R 3  that are parallel to a longitudinal axis of the thrombectomy device  102  in the absence of external forces on the thrombectomy device. However, when external forces are applied, the lines R 1 , R 2 , R 3  through one or more of the sets of marker-mounting projections may not be straight and/or may not be parallel to the longitudinal axis of the thrombectomy device. 
     In some embodiments, the markers in a laterally aligned set or longitudinally grouped set can be separate and/or spaced from each other and from the markers in other sets and/or groups. 
       FIGS. 5 and 6  are enlarged views of a marker-mounting projection  148  shown in the area  5 - 5  of  FIG. 4 . In some embodiments, the marker-mounting projection  148  has an arcuate, bowed or curved shape, and such a shape can span an entirety of the length of the marker-mounting projection  148  that receives a marker  150 . In some embodiments, the marker-mounting projection  148  can be cantilevered from the portion of the thrombectomy device to which it is attached (e.g., from a strut  114 , if present). 
     As illustrated in  FIGS. 5 and 6 , the marker-mounting projection  148  can include a concave surface  160  and a convex surface  162 . However, some marker-mounting projections can have a concave surface  160  or a convex surface  162  (either without the other), or neither. In some embodiments, the concave surface  160  faces away from a portion of the thrombectomy device  102  to which to is attached (e.g., from a strut  114 , if present). In some embodiments, the convex surface  162  is arranged opposite from the concave surface  160 , facing toward a portion of the thrombectomy device  102  to which to is attached (e.g., toward a strut  114 , if present), or both. 
     In some embodiments, the concave surface  160  and the convex surface  162  are parallel to each other over some or all of the length of the marker-mounting projection  148  that receives a marker  150 . The marker-mounting projection  148  can comprise a constant cross-sectional area along its length and/or a constant width along the length of the marker-mounting projection  148  that receives a marker  150 . In some embodiments, the concave surface  160 , the convex surface  162 , or both includes a constant curvature or radius along the length of the marker-mounting projection  148  that receives a marker  150 . In some embodiments, the marker-mounting projection  148  includes a rounded distal end  163 . 
       FIG. 6  illustrates a marker  150  on the marker-mounting projection  148 . The marker  150  can comprise a radiopaque material such as platinum, iridium, tantalum, gold, alloys thereof or bismuth and tungsten-doped polymers, among other materials. The marker  150  can be more radiopaque than a body of the vascular or thrombectomy device  102 . The marker  150  can be visible under fluoroscopy, CAT scans, X-Rays, Mill, ultrasound technology or other types of imaging. The marker  150  can include an interior channel, an interior recess or another mounting feature. Further, the marker  150  can comprise a band or substantially cylindrical shape with an open or closed circumference, a coil, or another form that mounts around a marker-mounting projection  148 . 
     The marker  150  can directly attach to the marker-mounting projection  148  through direct contact between the marker  150  and the marker-mounting projection  148 . In some embodiments, adhesives, welding, soldering, friction or mechanical fastening (e.g., crimping) directly attach the marker  150  to marker-mounting projection  148 . In some embodiments, the marker  150  extends completely around the marker-mounting projection  148  when the marker  150  is mounted, or directly attached, to the marker-mounting projection  148 . In another embodiment, the marker  150  extends partially (e.g., at least three quarters of the perimeter) around the marker-mounting projection  148  when the marker  150  is mounted, or directly attached, to the marker-mounting projection. 
     The marker-mounting projection  148  can extend generally parallel to a segment of the thrombectomy device (e.g., a strut) adjacent to the marker  150 , for example as illustrated in  FIG. 5 , or such that a marker when mounted to the marker-mounting projection  148  is parallel to a segment of the thrombectomy device (e.g., a strut) adjacent to the marker  150 , for example as illustrated in  FIG. 6 . 
     The marker  150  and the marker-mounting projection  148  can contact each other at three discrete locations when the marker  150  is directly attached to the marker mounting projection  148 . In some embodiments, the marker  150  and the marker-mounting projection  148  contact each other at more or fewer than three locations when the marker  150  is directly attached to the marker mounting projection  148 . In other embodiments, the marker  150  and the marker-mounting projection  148  contact each other at two locations on the concave surface  160  and at one location on the convex surface  162  when the marker  150  is directly attached to the marker-mounting projection  148 . In one embodiment, the contact location of the marker  150  and the convex surface  162  is located between the contact locations of the marker  150  and the concave surface  160 . 
     In some embodiments, an arcuate marker-mounting projection can have greater marker retention strength, better withstand electropolishing, or both compared to marker-mounting projection having a straight configuration. 
       FIGS. 7-9  are schematic representations of fluoroscopic images of an arrangement of markers when a thrombectomy device to which they are attached is in various states.  FIG. 7  illustrates an arrangement of markers  150  when the thrombectomy device  102  is in an unexpanded state within a catheter  107  (see  FIG. 1 ). As shown in  FIG. 7 , the markers  150  in a proximal marker group  151 , which can be located at the working length proximal end  146  and mounted on marker-mounting projections  148 , markers  150  in a distal marker group  152 , which can be located at the working length distal end  147  and mounted on marker-mounting projections  148 , and markers  150  in an intermediate marker group  153 , which can be located at the working length intermediate area  149  and mounted on marker-mounting projections  148 , can be in close lateral proximity to the other markers  150  in the respective marker group. In some embodiments, a portion of a length of the thrombectomy device  102  between the proximal marker group  151  and the distal marker group  152 , or between the working length proximal  146  and distal  147  ends, has no marker  150 . 
       FIG. 8  illustrates the markers of  FIG. 7  when the thrombectomy device  102  is in a fully expanded state. As shown in  FIG. 8 , the markers  150  in the proximal marker group  151 , the markers  150  in the distal marker group  152 , and the markers  150  in the intermediate marker group  153  can be located farther laterally from the other markers  150  in a respective marker group in this state than they are when the thrombectomy device  102  is in an unexpanded state.  FIG. 8  also shows the markers having substantially the same pattern and/or spacing relative to each other in each of the proximal marker group  151 , the distal marker group  152 , and the intermediate marker group  153 . 
       FIG. 9  illustrates the markers of  FIG. 7  when the thrombectomy device  102  is in a partially expanded state within a vessel and in contact with a thrombus. As shown in  FIG. 9 , markers  150  in the intermediate marker group  153  are not spaced as far from each other laterally as are the markers  150  in the proximal marker group  151  from each other or the markers  150  in the distal marker group  152  are from each other. Such an arrangement can occur when the thrombectomy device  102  is in an expanded state in the presence of a thrombus  165  that inhibits or prevents expansion of a region of the thrombectomy device. 
     Methods for engaging and removing a thrombus  165  will now be discussed with reference to  FIGS. 10-20 . Referring to  FIG. 10 , the medical device  100  may be inserted into an anatomical vessel  172  by first inserting a guide wire  174  into the anatomical vessel  172 . The illustrated anatomical vessel is an intracranial blood vessel. In some embodiments, the medical device is introduced into a segment of cerebral blood vessel distal to the carotid siphon. The inserted medical device  100  can be any embodiment of the medical device  100  disclosed herein, including any of the thrombectomy devices  102 , elongate members  104 , or connections  106 . The guide wire  174  can be advanced through a guide catheter  164  (see  FIG. 18 ), which optionally includes a balloon near the guide catheter&#39;s distal end, and/or a catheter  107  to the treatment site, adjacent the thrombus  165 . Referring to  FIG. 11 , the guide wire  174  is advanced distally through the thrombus  165 . Once the guide wire  174  is in position, the catheter  107  is advanced over the guide wire  174 , through a distal end of the guide catheter, toward the thrombus  165  in the anatomical vessel  172 . Referring to  FIG. 12 , the catheter  107  is advanced distally through the thrombus  165 . The guide wire  174  is then withdrawn proximally. 
     Referring to  FIG. 13 , the medical device  100  is advanced through the catheter  107 . The medical device  100  is advanced through the catheter  107  by the manipulation member  104  coupled to the thrombectomy device  102  (e.g., at the proximal end of the thrombectomy device). The catheter  107  prevents expansion of the thrombectomy device  102  and thus maintains the thrombectomy device  102  in a compressed, volume-reduced configuration as the thrombectomy device  102  is advanced to the treatment site. The thrombectomy device  102  is advanced or otherwise moved to position (i) the proximal marker or marker group  151  proximal to a proximal end  170  of the thrombus  165 , and (ii) the distal marker or marker group  152  distal to a distal end  171  of the thrombus  165 . If an intermediate marker or marker group  153  is present, the thrombectomy device  102  is advanced or otherwise moved to position the intermediate marker or marker group  153  between the proximal and distal ends of (e.g., within) the thrombus. 
     Turning to  FIG. 14 , the catheter  107  is then withdrawn proximally relative to the thrombectomy device  102  to expose the thrombectomy device  102 . If the thrombectomy device  102  is self-expanding, retraction of the catheter  107  can permit the thrombectomy device  102  to expand to an expanded state.  FIG. 14  illustrates the markers  150  of the proximal marker group  151  and the distal marker group  152  as more expanded than are the markers  150  of the intermediate  153  marker group, which appear in a less expanded distribution. Such an arrangement can result when the thrombectomy device  102  is expanded while all markers  150  of the proximal marker group  151  are located proximal to the thrombus  165 , or to a proximal end of the thrombus  170 , and all markers  150  of the distal marker group  152  are located distal to the thrombus  165 , or to a distal end of the thrombus  171 . When such a marker  150  arrangement is observed, an operator may check, by injecting contrast solution through the catheter  107  or guide catheter  164 , for perfusion of the distal vasculature through the thrombus  165  via a flow channel (if any) opened in the thrombus  165  by the expansion of the thrombectomy device  102 , allow the thrombectomy device  102  to continue expanding into the thrombus  165  and/or proceed to withdraw the thrombectomy device  102 , as illustrated in  FIG. 17 . 
       FIG. 15  illustrates another configuration of the thrombectomy device  102 , wherein the markers  150  of the distal marker group  152  are more expanded than are the markers  150  of the proximal marker group  151  or the marker group intermediate  153 , which each appear in a less expanded state. Such an arrangement can result when the thrombectomy device  102  is expanded while all markers in the proximal marker group  151  and the intermediate marker group  153  are located radially adjacent to the thrombus  165  within the blood vessel and all markers in the distal marker group  152  are located distal to the thrombus  165  or a distal end  171  of the thrombus. When such a marker  150  arrangement is observed, an operator may check for perfusion of the distal vasculature through the thrombus  165 , allow the thrombectomy device  102  to continue expanding into the thrombus  165  and/or proceed to withdraw the thrombectomy device  102 , as illustrated in  FIG. 17 . 
       FIG. 16  illustrates another configuration of the thrombectomy device  102 , wherein the markers  150  of the proximal marker group  151  are more expanded than are the markers  150  of the distal marker group  152  or intermediate marker group  153 , which appear in less expanded state. Such an arrangement can result when the thrombectomy device  102  is expanded while the markers in the distal marker group  152  are not located distal to the thrombus  165  or a distal end  171  of the thrombus or when the thrombus migrates distally during or after expansion of the thrombectomy device  102 . 
     When a marker  150  arrangement as illustrated in  FIG. 16  is observed or determined, or when a maximum marker  150  separation of the intermediate marker group  153  is observed as greater than a maximum marker  150  separation of either the proximal marker group  151  or distal marker group  152 , an operator may elect to collapse the thrombectomy device  102  into less unexpanded state, for example by advancing the catheter  107  over the thrombectomy device  102 . The operator can then again position the thrombectomy device  102  relative to the thrombus and expand the thrombectomy device as described above. 
     With the proximal marker or marker group  151  located at the working length proximal end  146 , the operator can more accurately and/or confidently position the thrombectomy device relative to a thrombus prior to expansion, thereby facilitating utilization of the working length of the thrombectomy device. In some embodiments, positioning the thrombectomy device  102  with reference to the proximal marker or marker group  151  located at the working length proximal end  146  can facilitate or promote a successful removal of the thrombus or clot  165 , by achieving a more secure contact, interlock or engagement between the thrombectomy device  102  and the thrombus or clot  165 . Further, a comparison of the relative extent of marker group expansion can provide information to an operator that assists in determining whether and how (e.g., which direction) to reposition the thrombectomy device  102 . 
     Accordingly, during a revascularization procedure, the user can use the proximal marker group  151  and/or the distal marker group  152  to properly locate the thrombectomy device  102  longitudinally relative to the thrombus  165  before expanding the device  102  into the thrombus. At appropriate time(s) in the procedure, the user can establish the location of the thrombus on an image of the treatment location (such as a fluoroscopic image or other suitable image as disclosed herein) by injecting contrast media into the target vessel  172  and observing the effect of the thrombus on the flow of the contrast media in the vessel. Once the catheter  107  is positioned in the thrombus  165  as shown in  FIG. 12 , the user can advance the thrombectomy device  102  toward the distal end of the catheter and observe in the image of the treatment location the position of the proximal marker group  151  and/or the distal marker group  152  relative to the thrombus  165  (e.g. relative to the proximal end  170  and/or the distal end  171  thereof). This can be done while the thrombectomy device  102  is still in the catheter to enable adjustment of the position of the thrombectomy device  102  prior to expansion;  FIG. 7  depicts an example of a fluoroscopic image that the user might observe with the proximal marker group  151  and the distal marker group  152  clearly visible due to their radiopacity. The user can also observe from such an image that the entire device  102  is still in the catheter  107  due to the closely “packed” state of the marker groups  151 ,  152 ,  153  (and as well that the distal end of device  102  is near the distal tip of the catheter  107  as may be facilitated by a catheter tip marker  173  (see  FIGS. 7-9 ). With the location of the proximal end of the working length  144  indicated in the image by the proximal marker group  151  (and, optionally, the distal end of the working length  144  indicated in the image by the distal marker group  152 ), the user can determine whether the proximal end of the working length  144  is positioned proximal of or longitudinally aligned with the proximal end  170  of the thrombus (and, optionally, whether the distal end of the working length  144  is positioned distal of or longitudinally aligned with the distal end  171  of the thrombus). Based on this observation, the user can either confirm that the working length  144  of the device  102  is aligned with (or spans the entirety of) the length of the thrombus  165 ; if either or both is the case the user can leave the device in its current longitudinal position relative to the thrombus; if not, the user can adjust the longitudinal position of the device  102  until it is correctly positioned relative to the thrombus  165  as described above. Once the user has confirmed the correct positioning of the device  102  in this manner, the user can proceed to expand the device  102  into the thrombus  165 , e.g. as described elsewhere herein, and remove some or all of the thrombus from the vessel  172 . Advantageously, as mentioned above, when the thrombectomy device  102  is of an overlap or roll-up configuration, relatively little or no change in the length of the device  102  will occur during expansion, and accordingly the positions of the markers relative to the thrombus (and to each other) will not change significantly or at all as the device expands. This in turn facilitates accurate placement of the expanded device  102  in and relative to the thrombus  165 . 
     Referring to  FIGS. 17 and 18 , once the user is satisfied that the device  102  has been properly located longitudinally relative to the thrombus  165  and expanded into it, the thrombectomy device  102  can be withdrawn proximally, along with the thrombus  165 . As illustrated in  FIG. 18 , the thrombectomy device  102  can be withdrawn proximally, along with the thrombus  165 , into the guide catheter  164 . 
     Referring to  FIGS. 18 and 19 , in embodiments wherein the guide catheter  164  comprises a balloon  168 , the balloon optionally can be inflated to occlude flow during retraction of the thrombus  165  toward the guide catheter. Referring to  FIG. 18 , the thrombectomy device  102  is withdrawn proximally to the guide catheter  164 . The guide catheter  164  causes the frame  108  to collapse, with the thrombus  165  engaged therein. The thrombus  165  is thus retrieved and removed from the anatomical vessel  172 . Referring to  FIG. 20 , if retrieval of the thrombectomy device  102  is determined to be undesirable, e.g., to avoid damaging the vessel  172 , and the thrombectomy device  102  is detachably or releasably connected to the manipulation member  104 , the thrombectomy device  102  can be detached from the manipulation member  104  and can remain in the vessel  172 . 
     Additionally, while the thrombectomy device  102  described above has been described in the context of use during a thrombectomy or blood flow restoration procedure, the thrombectomy device  102  can also, or alternatively, be used as an implantable member (e.g. stent). For example, the thrombectomy device  102  can be released through the connection  106  at a stenosis, aneurysm, or other appropriate location in a vessel. The thrombectomy device  102  can expand and engage a vessel wall so as to hold the vessel wall open and/or act as an occluding member. While the filament thicknesses, widths, cell sizes, and forces described above can be optimized for an thrombectomy device  102  for flow restoration, these values can also be optimized for a thrombectomy device  102  for use as an implantable member. In some embodiments the same values can be used for both flow restoration and use as an implantable member. 
     Also, while use of the thrombectomy device  102  described above with use of a catheter  107 , the catheter  107  can be omitted in some embodiments. 
     The foregoing description is provided to enable a person skilled in the art to practice the various configurations described herein. While the subject technology has been particularly described with reference to the various figures and configurations, it should be understood that these are for illustration purposes only and should not be taken as limiting the scope of the subject technology. 
     There may be many other ways to implement the subject technology. Various functions and elements described herein may be partitioned differently from those shown without departing from the scope of the subject technology. Various modifications to these configurations will be readily apparent to those skilled in the art, and generic principles defined herein may be applied to other configurations. Thus, many changes and modifications may be made to the subject technology, by one having ordinary skill in the art, without departing from the scope of the subject technology. 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplifying approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Some of the steps may be performed simultaneously. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     A phrase such as “an aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. An aspect may provide one or more examples of the disclosure. A phrase such as “an aspect” may refer to one or more aspects and vice versa. A phrase such as “an embodiment” does not imply that such embodiment is essential to the subject technology or that such embodiment applies to all configurations of the subject technology. A disclosure relating to an embodiment may apply to all embodiments, or one or more embodiments. An embodiment may provide one or more examples of the disclosure. A phrase such “an embodiment” may refer to one or more embodiments and vice versa. A phrase such as “a configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A configuration may provide one or more examples of the disclosure. A phrase such as “a configuration” may refer to one or more configurations and vice versa. 
     Furthermore, to the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. 
     All structural and functional equivalents to the elements of the various configurations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the subject technology. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description. 
     While certain aspects and embodiments of the subject technology have been described, these have been presented by way of example only, and are not intended to limit the scope of the subject technology. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms without departing from the spirit thereof. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the subject technology.