Patent Publication Number: US-2023149021-A1

Title: Retrieval of material from corporeal lumens

Description:
TECHNICAL FIELD 
     The present technology relates generally to devices and methods for removing obstructions from body lumens. Some embodiments of the present technology relate to devices and methods for removing clot material from blood vessels. 
     BACKGROUND 
     Many medical procedures use medical device(s) to remove an obstruction (such as clot material) from a body lumen, vessel, or other organ. An inherent risk in such procedures is that mobilizing or otherwise disturbing the obstruction can potentially create further harm if the obstruction or a fragment thereof dislodges from the retrieval device. If all or a portion of the obstruction breaks free from the device and flows downstream, it is highly likely that the free material will become trapped in smaller and more tortuous anatomy. In many cases, the physician will no longer be able to use the same retrieval device to again remove the obstruction because the device may be too large and/or immobile to move the device to the site of the new obstruction. 
     Procedures for treating ischemic stroke by restoring flow within the cerebral vasculature are subject to the above concerns. The brain relies on its arteries and veins to supply oxygenated blood from the heart and lungs and to remove carbon dioxide and cellular waste from brain tissue. Blockages that interfere with this blood supply eventually cause the brain tissue to stop functioning. If the disruption in blood occurs for a sufficient amount of time, the continued lack of nutrients and oxygen causes irreversible cell death. Accordingly, it is desirable to provide immediate medical treatment of an ischemic stroke. 
     To access the cerebral vasculature, a physician typically advances a catheter from a remote part of the body (typically a leg) through the abdominal vasculature and into the cerebral region of the vasculature. Guidewires are used during the procedure to facilitate navigation of a catheter (and/or associated treatment device) to portion of the blood vessel proximate the targeted thrombus. For example, the physician may navigate the vasculature to the treatment site with the guidewire, then advance one or more catheters or other devices over the guidewire to the site. Guidewires may also be used to facilitate exchanging of devices. For instance, a physician may replace the original catheter with another catheter, or a separate device having different properties or better suited for the intended procedure (e.g. better condition, more navigable, better supporting, etc.). 
     Once within the cerebral vasculature, the physician deploys a device for retrieval of the obstruction causing the blockage. Concerns about dislodged obstructions or the migration of dislodged fragments increases the duration of the procedure at a time when restoration of blood flow is paramount. Furthermore, a physician might be unaware of one or more fragments that dislodge from the initial obstruction and cause blockage of smaller more distal vessels. 
     Many physicians currently perform thrombectomies (i.e. clot removal) with stents to resolve ischemic stroke. Typically, the physician deploys a stent into the clot in an attempt to push the clot to the side of the vessel and re-establish blood flow. Tissue plasminogen activator (“tPA”) is often injected into the bloodstream through an intravenous line to break down a clot. However, it takes time for the tPA to reach the clot because the tPA must travel through the vasculature and only begins to break up the clot once it reaches the clot material. tPA is also often administered to supplement the effectiveness of the stent. Yet, if attempts at clot dissolution are ineffective or incomplete, the physician can attempt to remove the stent while it is expanded against or enmeshed within the clot. In doing so, the physician must effectively drag the clot through the vasculature, in a proximal direction, into a guide catheter located within vessels in the patient&#39;s neck (typically the carotid artery). While this procedure has been shown to be effective in the clinic and easy for the physician to perform, there remain some distinct disadvantages to using this approach. 
     For example, one disadvantage is that the stent may not sufficiently retain the clot as it pulls the clot to the catheter. In such a case, some or all of the clot might remain in the vasculature. Another risk is that, as the stent mobilizes the clot from the original blockage site, the clot might not adhere to the stent as the stent is withdrawn toward the catheter. This is a particular risk when passing through bifurcations and tortuous anatomy. Furthermore, blood flow can carry the clot (or fragments of the clot) into a branching vessel at a bifurcation. If the clot is successfully brought to the end of the guide catheter in the carotid artery, yet another risk is that the clot may be “stripped” or “sheared” from the stent as the stent enters the guide catheter. 
     In view of the above, there remains a need for improved devices and methods that can remove occlusions from body lumens and/or vessels. 
     SUMMARY 
     The present technology relates generally to devices and methods for removing obstructions from body lumens. Aspects of the present technology include a treatment system for removing clot material from blood vessels. In some embodiments, the treatment system comprises a treatment device and one or more catheters. The treatment device may include an elongated member and an expandable distal element coupled to a distal region of the elongated member. The distal element may provide several functions throughout the procedure to facilitate clot retrieval. For example, deployment of the distal element within a blood vessel can anchor a distal region of the treatment device at the deployed location. Such anchoring may be beneficial for navigating the tortuous vasculature (such as the cerebral vasculature) to the site of the thrombus, and may also help align, straighten, or stabilize one or more delivery system components associated with the treatment device, such as a microcatheter or aspiration catheter. In addition, the distal elements of the present technology may be utilized in conjunction with an aspiration catheter to push clot material towards the aspiration catheter, and also as a distal embolic filter. 
     The present technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the present technology are described below for convenience. These are provided as examples and do not limit the present technology. 
     Several embodiments of the present technology comprise a treatment device including an elongated member having a proximal portion and a distal portion configured to be positioned within a blood vessel at a treatment site at or near a thrombus. The treatment device can further include a distal element having a proximal end portion and a distal end portion. The proximal end portion can be coupled to the distal portion of the elongated member via a connection assembly. The distal element can comprise a plurality of woven filaments defining a non-expandable extension portion at the proximal end portion and an expandable body portion distal of the extension portion. Along the extension portion, the filaments can extend in a direction substantially parallel with a longitudinal axis of the elongated member. The body portion can comprise (a) a first portion along which the filaments taper proximally and extend substantially linearly, and (b) a second portion along which the filaments are interwoven and wrap around all or a portion of the circumference of the distal element. The distal element can further comprise a cover disposed on the filaments along all or a portion of a length of the distal element. The distal element can have a constrained state for delivery to the treatment site and an expanded state in which at least a portion of the body is configured to expand into contact with the blood vessel wall at the treatment site and anchor and/or stabilize the elongated member within the blood vessel. 
     Several embodiments of the present technology comprise a treatment device including an elongated member having a proximal portion and a distal portion configured to be positioned within a blood vessel at a treatment site at or near a thrombus. The elongated member can have a proximal portion and a distal portion configured to be positioned within a blood vessel at a treatment site at or near a thrombus. The treatment device may further comprise a distal element having a proximal end portion and a distal end portion, the proximal end portion being coupled to the distal portion of the elongated member via a connection assembly. The distal element may comprise a plurality of woven filaments that define an elongated three-dimensional body when the distal element is in an expanded state. The body can comprise (a) a first portion having a cross-sectional dimension that increases distally and along which the filaments extend substantially linearly, and (b) a second portion along which the filaments are interwoven and wrap around all or a portion of the circumference of the distal element. The distal element may also comprise a cover disposed on the filaments along all or a portion of a length of the body of the distal element. The distal element can have a constrained state for delivery to the treatment site and the expanded state in which at least a portion of the body is configured to expand into contact with the blood vessel wall at the treatment site and anchor and/or stabilize the elongated member within the blood vessel. 
     In any of the foregoing embodiments, the treatment device may include a delivery electrode configured to be electrically coupled to a first electrical terminal of a current generator and a return electrode configured to be electrically coupled to a second electrical terminal of the current generator. The distal element can comprise the delivery electrode, the return electrode, or both. In some embodiments, the elongated member and/or connection assembly may comprise the delivery electrode, the return electrode, or both. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present technology can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present disclosure. 
         FIG.  1    shows a perspective view of a treatment system for retrieving material from a body lumen, in accordance with one or more embodiments of the present technology. 
         FIG.  2 A  shows a schematic side view of a portion of the treatment system shown in  FIG.  1   . 
         FIG.  2 B  shows a cross-sectional view of the treatment device taken along line  2 B- 2 B in  FIG.  2 A . 
         FIG.  2 C  shows a cross-sectional view of another embodiment of the treatment device. 
         FIGS.  3 - 8 A  illustrate side views of treatment devices in accordance with aspects of the present technology. 
         FIG.  8 B  is an isolated view of a portion of the elongated member shown in  FIG.  8 A . 
         FIG.  9    shows a cross-sectional view of the treatment device of  FIG.  8 A  taken along line  9 - 9 . 
         FIGS.  10 A- 10 E  illustrate a method of removing clot material from a blood vessel lumen in accordance with one or more embodiments of the present technology. 
         FIG.  11    shows a perspective view of a treatment system for retrieving material from a body lumen, in accordance with one or more embodiments of the present technology. 
         FIGS.  12 - 17    illustrate schematic side views of treatment systems in accordance with embodiments of the present technology. 
         FIGS.  18 A- 18 D  illustrate a method of removing clot material from a blood vessel lumen, in accordance with one or more embodiments of the present technology. 
         FIG.  19 A  shows a perspective view of an electrically enhanced treatment system for retrieving material from a body lumen, in accordance with one or more embodiments of the present technology. 
         FIGS.  19 B and  19 C  are schematic views of different embodiments of the current generator illustrated in  FIG.  19 A . 
         FIG.  20 A  is a side schematic view of a portion of the treatment system of  FIG.  19 A . 
         FIG.  20 B  is a side schematic cross-sectional view of a portion of the treatment system shown in  FIG.  20 A . 
         FIG.  20 C  is a side schematic cross-sectional view of a portion of another embodiment of a treatment system. 
         FIG.  21    shows a perspective view of an electrically enhanced treatment system for retrieving material from a body lumen, in accordance with one or more embodiments of the present technology. 
         FIG.  22    is a side schematic view of a portion of the treatment system shown in  FIG.  21   . 
         FIGS.  23 A- 23 E  illustrate sample waveforms for electrically enhanced removal of material from vessel lumens in accordance with one or more embodiments of the present disclosure. 
         FIGS.  24 A- 25 B  illustrate embodiments of distal elements in accordance with aspects of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     The present technology provides devices, systems, and methods for removing clot and/or other material from a blood vessel lumen. Although many of the embodiments are described below with respect to devices, systems, and methods for treating a cerebral or intracranial embolism, other applications and other embodiments in addition to those described herein are within the scope of the technology. For example, the treatment systems and methods of the present technology may be used to remove emboli from body lumens other than blood vessels (e.g., the digestive tract, etc.) and/or may be used to remove emboli from blood vessels outside of the brain (e.g., pulmonary, abdominal, cervical, or thoracic blood vessels, or peripheral blood vessels including those within the legs or arms, etc.). In addition, the treatment systems and methods of the present technology may be used to remove luminal obstructions other than clot material (e.g., plaque, resected tissue, foreign material, etc.). 
     Example treatment systems comprising a distal element and associated methods of use are described below with reference to  FIGS.  1 - 10 E . Example treatment systems including a distal element and an interventional element and associated methods of use are described below with respect to  FIGS.  11 - 18 D . Example electrically-enhanced treatment systems are described below with respect to  FIGS.  19 A- 23 E . Additional example distal elements for use with any of the treatment systems of the present technology are described with respect to  FIGS.  24 A- 25 B . 
     I. OVERVIEW OF TREATMENT SYSTEMS OF THE PRESENT TECHNOLOGY 
       FIG.  1    shows a treatment system  10  according to one or more embodiments of the present technology. As shown in  FIG.  1   , the treatment system  10  has a proximal portion  10   a  configured to be extracorporeally positioned during treatment and a distal portion  10   b  configured to be intravascularly positioned within a blood vessel (such as an intracranial blood vessel) at a treatment site at or proximate a thrombus. The treatment system  10  may include a handle  16  at the proximal portion  10   a , and a treatment device  100  and a plurality of elongated shafts or members extending between the proximal and distal portions  10   a  and  10   b . For example, in some embodiments, such as that shown in  FIG.  1   , the treatment system  10  may include one, some, or all of: a first catheter  200  (such as a guide catheter or balloon guide catheter), a second catheter  210  (such as a distal access catheter or aspiration catheter) configured to be slidably disposed within a lumen of the first catheter  200 , and a third catheter  220  (such as a microcatheter) configured to be slidably disposed within a lumen of the second catheter  210 . In some embodiments, the first catheter  200  is coupled to the handle  16 , which provides proximal access to the second catheter  210 , the third catheter  220 , and/or the treatment device  100 . The treatment device  100  may be configured to be slidably disposed within a lumen of the first catheter  200 , the second catheter  210 , and/or the third catheter  220 . 
     As shown in  FIG.  1   , the treatment device  100  has a proximal portion  100   a , a distal portion  100   b , an elongated member  120  extending from the proximal portion  100   a  to the distal portion  100   b , and an expandable distal element  140  coupled to a distal portion of the elongated member  120 . The distal element  140  may comprise an expandable body of woven filaments having a low-profile or constrained state while positioned within a catheter for delivery to a deployment location and an expanded state in which at least a portion of the body is configured to be in apposition with the blood vessel wall. The distal element  140  is configured to expand into contact with the blood vessel wall at desired locations along the intravascular path to the treatment site as well as at the treatment site to anchor and/or stabilize the elongated member  120  and/or any portion of the treatment device  100  and/or treatment system  10  at the desired location. As detailed below, the distal element  140  may also be configured to facilitate removal of the thrombus from the treatment site. 
     In some embodiments, the treatment system  10  includes a suction source  25  (e.g., a syringe, a pump, etc.) configured to be fluidly coupled (e.g., via a connector  23 ) to a proximal portion of one or more of the first catheter  200 , the second catheter  210 , and/or the third catheter  220  to apply negative pressure therethrough. In some embodiments, the treatment system  10  includes a fluid source  27  (e.g., a fluid reservoir, a syringe, pump, etc.) configured to be fluidly coupled (e.g., via the connector  23 ) to a proximal portion of one or more of the first catheter  200 , the second catheter  210 , and/or the third catheter  220  to supply fluid (e.g., saline, contrast agents, a drug such as a thrombolytic agent, etc.) to the treatment site. 
     According to some embodiments, for example as shown in  FIG.  1   , each of the first, second, and third catheters  200 ,  210 , and  220  can be formed as a generally tubular member extending along and about a central axis and terminating in a respective distal end. The first catheter  200  can be sized and configured to slidably receive both the second catheter  210  and the third catheter  220  therethrough. In some embodiments, the first catheter  200  is a balloon-guide catheter having an inflatable balloon or other expandable member that can be used to anchor the first catheter  200  with respect to a surrounding vessel, and/or arrest the flow of blood at the location of the balloon. 
     The second catheter  210  can be sized and configured to slidably receive the third catheter  220  therethrough. The second catheter  210  can be coupled at a proximal portion to a suction source  25  such as a pump or syringe in order to supply negative pressure to a treatment site. In some embodiments, the second catheter  210  may have a working length of about 100 cm to about 140 cm, for example about 105 cm, about 120 cm, or about 132 cm. The second catheter  210  may have an inner diameter of about 0.068 inches (0.172 cm), or about 0.071 inches (0.180 cm). 
     According to some embodiments, the third catheter  220  is generally constructed to track over a conventional guidewire in the cervical anatomy and into the cerebral vessels associated with the brain and may also be chosen according to several standard designs that are generally available. Accordingly, the third catheter  220  can have a length that is at least 125 cm long, and more particularly may be between about 125 cm and about 175 cm long. In some embodiments, the third catheter  220  may have an inner diameter of about 0.015 inches (0.0381 cm), 0.017 inches (0.043 cm), about 0.021 inches (0.053 cm), or about 0.027 inches (0.069 cm). Other designs and dimensions are contemplated. 
     As described in more detail below with respect to  FIGS.  10 A- 10 E , in operation the first catheter  200  can first be advanced through a vessel and a balloon can be expanded to anchor the first catheter  200  in place and/or arrest blood flow from areas proximal of the balloon. Next, the second catheter  210  can be advanced through the first catheter  200  until its distal end extends distally beyond the distal end of the first catheter  200 . The second catheter  210  can be positioned such that its distal end is close to or adjacent a treatment site (e.g., a site of a blood clot within the vessel). The third catheter  220  may then be advanced through the second catheter  210  until its distal end extends distally beyond the distal end of the second catheter  210 . 
     According to some embodiments, the bodies of the catheters  200 ,  210 , and  220  can be made from various thermoplastics, e.g., polytetrafluoroethylene (PTFE or TEFLON®), fluorinated ethylene propylene (FEP), high-density polyethylene (HDPE), polyether ether ketone (PEEK), etc., which can optionally be lined on the inner surface of the catheters or an adjacent surface with a hydrophilic material such as polyvinylpyrrolidone (PVP) or some other plastic coating. Additionally, either surface can be coated with various combinations of different materials, depending upon the desired results. Any one or more of the catheters  200 ,  210 ,  220  may incorporate a reinforcement structure in its construction, e.g. layered between an inner lubricious liner and an outer polymeric jacket. Such a reinforcement structure can be metallic and/or polymeric, and comprise a tubular braid, a coil, a hypotube (e.g. a spiral-cut or slotted-cut hypotube), or combinations of the foregoing. Suitable metals for constructing the reinforcement structure include without limitation stainless steel, nitinol, and cobalt-chromium. 
     II. EXAMPLE TREATMENT DEVICES AND METHODS OF USE 
       FIG.  2 A  is a side schematic view of some embodiments of the treatment device  100  shown in  FIG.  1   . As shown in  FIG.  2 A , the treatment device  100  may comprise an elongated member  120  (such as a wire or guidewire) and an expandable distal element  140  coupled to a distal portion of the elongated member  120  via a connection assembly  130 . In the embodiment shown in  FIG.  2 A , the elongated member  120  extends distally from the connection assembly  130  through the entire length of the distal element  140  and projects distally beyond the distal element  140 . In some embodiments, the elongated member  120  may terminate at the connection assembly  130  and does not extend into the interior cavity and/or is not coextensive with any portion of the distal element  140 . In some embodiments, the elongated member  120  terminates at a location along the length of the distal element  140  but does not extend distally beyond the distal element  140 . 
     The elongated member  120  can be movable within the catheter and/or microcatheter to position the distal element  140  at a desired location. The elongated member  120  can be sufficiently flexible to allow manipulation, e.g., advancement and/or retraction, of the treatment device  100  through tortuous passages. Tortuous passages can include, for example, catheter lumens, microcatheter lumens, blood vessels, urinary tracts, biliary tracts, and airways. The elongated member  120  can be formed of any material and in any dimensions suitable for the task(s) for which the system is to be employed. In some embodiments, the elongated member  120  can comprise a solid metal wire. In some embodiments, the elongated member  120  may comprise any other suitable form of shaft such as an elongated tubular shaft, as discussed below with reference to  FIG.  7   . 
     In some embodiments, the elongated member  120  can comprise stainless steel, nitinol, or other metal or alloy. In some embodiments, the elongated member  120  can be surrounded over some or all of its length by a coating, such as, for example, polytetrafluoroethylene. A distal portion or tip  120   b  of the elongated member  120  can have a curved shape, for example as illustrated in  FIG.  2 A , such that the distal portion  120   b  of the elongated member  120  can be used to guide advancement of the distal end of the elongated member  120 . The elongated member  120  may have a diameter that is generally constant along its length, or the elongated member  120  may have a diameter that tapers radially inwardly, along at least a portion of its length, as it extends in a distal direction. In some embodiments, the elongated member  120  has a diameter of 0.008 inches (0.020 cm), 0.010 inches (0.254 cm), 0.014 inches (0.036 cm), 0.018 inches (0.046 cm), or more. 
     A proximal end of the distal element  140  may be coupled to the elongated member  120  via the connection assembly  130 . For example, as shown in the cross-sectional end view of the connection assembly  130  in  FIG.  2 B , the connection assembly  130  may comprise an outer band  132  positioned around the proximal end of the distal element  140 , and an inner band  131  positioned around the elongated member  120 . As such, the proximal end of the distal element  140  may be sandwiched between the outer band  132  and the inner band  131 , and the connection assembly  130  may be crimped down over the elongated member  120  to fix the connection assembly  130  to the elongated member  120  at a desired location. As shown in  FIG.  2 C , in some embodiments, the proximal end of the distal element  140  may be secured directly to the elongated member  120  by a single band  133 . 
     In some embodiments, for example as depicted in  FIGS.  3  and  4   , the treatment device  100  may include a stop on either side of the connection assembly  130  for limiting axial movement of the distal element  140  along the elongated member  120 . As shown in  FIG.  3   , in some examples of the technology, the treatment device  100  includes a first stop  134  fixed to the elongated member  120  proximal to the connection assembly  130  and a second stop  136  fixed to the elongated member  120  distal to the connection assembly  130 . The first and second stops  134 ,  136  may be any shape or size that prevents or inhibits movement of the connection assembly  130  along the elongated member  120 . Each of the first and/or second stops  134 ,  136  may be formed integrally with the elongated member  120  or as a separate component. The first and second stops  134 ,  136  may be positioned immediately adjacent the proximal and distal ends of the connection assembly  130  such that the connection assembly  130  cannot translate along the elongated member  120 . In such embodiments, the second stop  136  may be positioned just distal of the connection assembly  130  at a location that lies within an interior region of the distal element  140 . In such embodiments, although the connection assembly  130  and distal element  140  are substantially prevented from axial movement, the connection assembly  130  and distal element  140  are still free to rotate about the elongated member  120 , thereby allowing the physician to torque the elongated member  120  while the distal element  140  is in an expanded state. 
     In some embodiments, the first and second stops  134 ,  136  may be spaced apart from the corresponding adjacent ends of the connection assembly  130 , for example as shown in  FIG.  4   . In such embodiments, the connection assembly  130  is free to translate along a length of the elongated member  120  equivalent to the distance between the first and second stops  134 ,  136 . Accordingly, the connection assembly  130  and the distal element  140  are free to both rotate about and translate along the elongated member  120 . 
     In some embodiments, the treatment device  100  may include one or more flexible, helically wound coils wrapped around one or more portions of the elongated member  120 . The coils may be formed of a smaller diameter wire (such as a 0.003 inch wire). In some embodiments, the coil may be a gold-plated tungsten coil, a platinum coil, or other suitable radiopaque material to facilitate visualization via radiographic imaging. As shown in  FIG.  5 A , the treatment device  100  may include a proximal coil  150  extending along a length of the elongated member  120  proximal of the connection assembly  130  and/or distal element  140 . The proximal coil  150  may extend the entire length of the elongated member  120  that is proximal of the connection assembly  130 , or the proximal coil  150  may extend along only a portion of the length of the elongated member  120  that is proximal of the connection assembly  130  (for example, along a short length of the elongated member  120  just proximal of the connection assembly  130 ). In some embodiments, a distal end of the proximal coil  150  may abut or be joined with a proximal portion of the connection assembly  130  and/or distal element  140 . In other embodiments, a distal end of the proximal coil  150  is spaced apart from a proximal end of the connection assembly  130  and/or a proximal end of the distal element  140 . 
     As shown in  FIG.  5 B , the treatment device  100  may include a distal coil  160  extending along a length of the elongated member  120  distal of the connection assembly  130  and the distal coil  160  may extend distally therefrom, through some or all of the interior of the distal element  140 , and optionally distally beyond the distal element  140 . A proximal end of the distal coil  160  may abut or be joined to a distal end of the connection assembly  130 . In some embodiments, a proximal end of the distal coil  160  is spaced apart from a distal end of the connection assembly  130 , such that a portion of the elongated member  120  extends distally of the coil. The distal coil  160  can serve as a distal tip coil of the elongated member  120 , providing tip softness and navigability. In some such embodiments, a distalmost portion of the elongated member  120  can extend into an internal lumen of the distal coil  160 , to the distal end of the coil where the elongated member may be attached to the coil end via soldering or laser welding. 
     In some aspects of the technology, the treatment device  100  may include both a proximal coil  150  and a distal coil  160 , as depicted in  FIG.  6   . In any of the foregoing embodiments, the proximal coil  150 , the distal coil  160 , or both may be supplemented or replaced by a braid. 
       FIG.  7    shows a treatment device  100  in accordance with the present technology comprising an elongated shaft  170  and a distal element  140  carried by the elongated shaft  170 . The elongated shaft  170  may define a lumen that is configured to slidably receive the elongated member  120  therethrough. A distal end of the elongated shaft  170  may abut or be joined end-to-end with a proximal end of the connection assembly  130  and/or a proximal end of the distal element  140 . The distal element  140  may be positioned over the elongated member  120 . In the configuration of  FIG.  7   , the elongated member  120  can optionally be slidable within the elongated shaft  170  such that the member and the shaft can be moved independently relative to each other. For example, the shaft  170  may be advanceable over the elongated member  120 , which may function in a manner similar to a guidewire for enhanced navigability. Alternatively, the elongated member  120  may be retractable partially or completely into the elongated shaft  170 , should it be desired to shorten the distal extension of the device  100  when positioned in tortuous or narrow vasculature. 
     In some embodiments, for example as depicted in  FIG.  8 A , the treatment device  100  may include a grooved wire  180 , the distal element  140 , and the elongated member  120 . As shown in the isolated view of a portion of the grooved wire  180  in  FIG.  8 B , the grooved wire  180  may include a groove  182  that spirals (or extends in a straight, non-spiraling fashion) along the wire body and is configured to receive the elongated member  120  therealong. As shown in the cross-sectional view of  FIG.  9   , the elongated member  120  may be located within the groove  182 . The elongated member  120  can extend distally beyond the distal end of the grooved wire  180 , optionally through the distal element  140  and distally beyond it, to its distal end  120   b . The distal element  140  can be connected to the grooved wire  180  at or near the distal end of the grooved wire  180 . For example, the connection assembly  130  and/or distal element  140  itself may be coupled onto the outer diameter of the grooved wire  180 . Alternatively, the distal end of the grooved wire  180  may abut or be joined end-to-end with a proximal end of the connection assembly  130  and/or distal element  140 . 
       FIGS.  10 A- 10 E  illustrate a method of removing clot material CM from the lumen of a blood vessel V using a treatment system  10  as described above. As shown in  FIG.  10 A , the first catheter  200  can be advanced through the vasculature and positioned within the blood vessel such that a distal portion of the first catheter  200  is proximal of the clot material CM. As shown in  FIG.  10 B , the second catheter  210  may be advanced through the first catheter  200  until a distal portion of the second catheter  210  is at or proximal to the clot material CM. The first catheter  200  can be secured in place using a balloon  1001  or other expandable member configured to engage the vessel wall. Next, the third catheter  220  may be advanced through the second catheter  210  so that a distal portion of the third catheter  220  is positioned at or near the clot material CM. In some embodiments, the third catheter  220  may cross the clot material CM and be positioned such that a distal terminus  221  of the third catheter  220  is distal of the clot material CM. The distal element  140  may then be advanced through the third catheter  220  in a low-profile configuration until a distal terminus of the distal element  140  is at or adjacent the distal terminus of the third catheter  220 . 
     As shown in  FIG.  10 C , the third catheter  220  may be withdrawn proximally relative to the distal element  140  to release the distal element  140 , thereby allowing the distal element  140  to self-expand at least partially distal to the clot material CM. In some embodiments, the distal element  140  may be expanded distal of the clot material CM such that no portion of the distal element  140  is engaging the clot material CM while the distal element  140  is in the process of expanding toward the vessel wall. In some embodiments, the distal element  140  is configured to expand into contact with the wall of the vessel V, or the distal element  140  may expand to a diameter that is less than that of the blood vessel lumen such that the distal element  140  does not engage the entire circumference of the blood vessel wall. 
     As shown in  FIG.  10 D , aspiration may be applied to the treatment site via the second catheter  210 . For example, following deployment of the distal element  140 , the third catheter  220  can be retracted and removed from the lumen of the second catheter  210 . The treatment site can then be aspirated via the second catheter  210 , for example via a suction source such as a pump or syringe coupled to a proximal portion of the second catheter  210 . 
     In some embodiments, aspiration is applied while the distal element  140  is being retracted into the second catheter  210 . During retraction, the proximal face of the distal element  140  can engage with the clot material CM and urge it proximally towards the distal end of the second catheter  210 . Aspiration at this stage, and/or the presence of the distal element  140  distal of the clot material CM, can help secure the clot material CM within the second catheter  210  and prevent any dislodged portion of the clot material CM from escaping the second catheter  210  and being released back into the vessel V. 
     With reference to  FIG.  10 E , while the distal element  140  is engaged with the clot material CM, the clot material CM can be removed. For example, the distal element  140 , with the clot material CM gripped and/or pushed thereby, can be retracted proximally (for example, along with the second catheter  210  and, optionally, the third catheter  220 ). The second catheter  210 , distal element  140 , and associated clot material CM may then be withdrawn from the patient, optionally through one or more larger surrounding catheters, such as the first catheter  200 . 
     In  FIG.  10 E , the clot material CM has been moved to at least partially enter the second catheter  210 . In some embodiments, the clot material CM can substantially block the lumen of the second catheter  210 , thereby creating a “corking” effect that may be noticeable to a clinician supplying negative pressure to the second catheter  210 . Once the second catheter  210  is corked with the clot material CM, it becomes increasingly difficult to supply continued negative pressure to the second catheter  210 . This corking effect can indicate to a clinician that the clot material CM has been engaged by the second catheter  210  and that the clot material CM and second catheter  210  can be retracted through the vessel V and into the first catheter  200  or other surrounding catheter. 
     III. SELECT EMBODIMENTS OF TREATMENT SYSTEMS EMPLOYING INTERVENTIONAL ELEMENTS WITH THE DISTAL ELEMENTS DISCLOSED HEREIN 
       FIG.  11    illustrates a view of a treatment system  11  for retrieving material from a body lumen, according to one or more embodiments of the present technology. Several features of the treatment system  11  can be similar to the treatment system  10  shown in  FIG.  1    and described elsewhere herein. As shown in  FIG.  11   , the treatment system  11  includes a treatment device  101  having a proximal portion  101   a  configured to be extracorporeally positioned during treatment, and a distal portion  101   b  configured to be intravascularly positioned within a blood vessel (such as an intracranial blood vessel) at a treatment site at or proximate a thrombus. The treatment system  11  may include a handle  16  at the proximal portion  101   a , a distal element  140 , an interventional element  300 , and a plurality of elongated shafts or members extending between the proximal and distal portions  101   a  and  101   b . For example, in some embodiments, such as that shown in  FIG.  11   , the treatment system  11  may include one, some, or all of: a first catheter  200  (such as a guide catheter or balloon guide catheter), a second catheter  210  (such as a distal access catheter or aspiration catheter) configured to be slidably disposed within a lumen of the first catheter  200 , and a third catheter  220  (such as a microcatheter) configured to be slidably disposed within a lumen of the second catheter  210 . In some embodiments, the first catheter  200  is coupled to the handle  16 , which provides proximal access to the second catheter  210 , the third catheter  220 , the distal element  140  and/or the interventional element  300 . Each of the distal element  140  and the interventional element  300  may be configured to be slidably disposed within a lumen of the first catheter  200 , the second catheter  210 , and/or the third catheter  220 . Any of the embodiments or versions of the above-mentioned components that are described herein with reference to the treatment system  10  of  FIG.  1    can be employed in connection with the treatment system  11  as well. 
     In some embodiments, the treatment system  11  includes a suction source  25  (e.g., a syringe, a pump, etc.) configured to be fluidly coupled (e.g., via a connector  23 ) to a proximal portion of one or more of the first catheter  200 , the second catheter  210 , and/or the third catheter  220  to apply negative pressure therethrough. In some embodiments, the treatment system  11  includes a fluid source  27  (e.g., a fluid reservoir, a syringe, pump, etc.) configured to be fluidly coupled (e.g., via the connector  23 ) to a proximal portion of one or more of the first catheter  200 , the second catheter  210 , and/or the third catheter  220  to supply fluid (e.g., saline, contrast agents, a drug such as a thrombolytic agent, etc.) to the treatment site. 
     According to some embodiments, for example as shown in  FIG.  11   , each of the catheters  200 ,  210 , and  220  can be formed as a generally tubular member extending along and about a central axis and terminating in a respective distal end. According to some embodiments, the third catheter  220  is generally constructed to track over a conventional guidewire in the cervical anatomy and into the cerebral vessels associated with the brain and may also be chosen according to several standard designs that are generally available. Accordingly, the third catheter  2202  can have a length that is at least 125 cm long, and more particularly may be between about 125 cm and about 175 cm long. Other designs and dimensions are contemplated. 
     The second catheter  210  can be sized and configured to slidably receive the third catheter  220  therethrough. As noted above, the second catheter  210  can be coupled at a proximal portion to a suction source  25  such as a pump or syringe in order to supply negative pressure to a treatment site. The first catheter  200  can be sized and configured to slidably receive both the second catheter  210  and the third catheter  220  therethrough. In some embodiments, the first catheter  200  is a balloon-guide catheter having an inflatable balloon or other expandable member that can be used to anchor the first catheter  200  with respect to a surrounding vessel. As previously described in more detail with respect to  FIGS.  10 A- 10 E , in operation the first catheter  200  can first be advanced through a vessel and then a balloon can be expanded to anchor the first catheter  200  in place and/or arrest blood flow from areas proximal of the balloon. Next, the second catheter  210  can be advanced through the first catheter  200  until its distal end extends distally beyond the distal end of the first catheter  200 . The second catheter  210  can be positioned such that its distal end is adjacent a treatment site (e.g., a site of a blood clot within the vessel). The third catheter  220  may then be advanced through the second catheter  210  until its distal end extends distally beyond the distal end of the second catheter  210 . 
     According to some embodiments, the bodies of the catheters  200 ,  210 , and  220  can be made from various thermoplastics, e.g., polytetrafluoroethylene (PTFE or TEFLON®), fluorinated ethylene propylene (FEP), high-density polyethylene (HDPE), polyether ether ketone (PEEK), etc., which can optionally be lined on the inner surface of the catheters or an adjacent surface with a hydrophilic material such as polyvinylpyrrolidone (PVP) or some other plastic coating. Additionally, either surface can be coated with various combinations of different materials, depending upon the desired results. Any one or more of the catheters  200 ,  210 ,  220  may incorporate a reinforcement structure in its construction, e.g. layered between an inner lubricious liner and an outer polymeric jacket. Such a reinforcement structure can be metallic and/or polymeric, and comprise a tubular braid, a coil, a hypotube (e.g. a spiral-cut or slotted-cut hypotube), or combinations of the foregoing. Suitable metals for constructing the reinforcement structure include without limitation stainless steel, nitinol, and cobalt-chromium. 
       FIG.  12    is a side schematic view of an embodiment of a portion of the system  11  and treatment device  101  shown in  FIG.  11   . The system  11  and/or treatment device  101  includes the distal element  140 , the interventional element  300 , and the elongated member  120  extending from the body of the first catheter  200  and through at least a portion of the interventional element  300  and distal element  140 . As shown in  FIG.  12   , the distal element  140  is distal to the interventional element  300  and spaced apart from a distal end portion  120   b  (e.g., a distal tip or terminus) of the elongated member  120 . In some embodiments, the distal element  140  may be at the distal end portion  120   b  or distal terminus of the elongated member  120 . In lieu of the foregoing, the distal element  140  may in some embodiments be proximal of the interventional element  300 . 
     As shown in  FIG.  12   , the distal element  140  includes a proximal portion  140   a , a distal portion  140   b , and a connection assembly  130  disposed over the elongated member  120 . As described in more detail elsewhere herein, the distal element  140  (e.g., the proximal portion  140   a  of the distal element  140 ) can be slidably coupled, rotatably coupled, or fixedly coupled to the elongated member  120 , e.g., via the connection assembly  130 . In the embodiment shown in  FIG.  12   , the distal element  140  is fixedly coupled to the elongated member  120  via the connection assembly  130  such that the distal element  140  cannot longitudinally move relative to the elongated member  120 . In such embodiments, the distal element  140  may be rotatably and/or slidably coupled to the elongated member  120 . 
     The distal element  140  may comprise an expandable body of woven filaments having a low-profile or constrained state while positioned within a catheter for delivery to a deployment location and an expanded state in which at least a portion of the body is configured to be in apposition with the blood vessel wall. The distal element  140  is configured to expand into contact with the blood vessel wall at desired locations along the intravascular path to the treatment site as well as at the treatment site to anchor and/or stabilize the elongated member  120  and/or any portion of the treatment system  11  at the desired location. As previously described, the distal element  140  may also be configured to facilitate removal of the thrombus from the treatment site. Any of the distal elements  140  disclosed above with reference to  FIGS.  1 - 9  and  24 A- 25 B  may be utilized in the treatment devices  101  disclosed herein with respect to  FIGS.  11 - 17   . 
     As shown in  FIG.  12   , the interventional element  300  includes a proximal portion  300   a , a distal portion  300   b , and a connection assembly  302  at the proximal portion  300   a . As described in more detail below, the interventional element  300  (e.g., the proximal portion  300   a  of the interventional element  300 ) can be slidably coupled, rotatably coupled, or fixedly coupled to the elongated member  120 , e.g., via the connection assembly  302 . As shown in  FIG.  12   , the interventional element  300  is fixedly coupled to the elongated member  120  via the connection assembly  302  such that the interventional element  300  cannot longitudinally move relative to the elongated member  120 . In such embodiments, the interventional element  300  may be rotatably coupled to the elongated member  120 . 
     The interventional element  300  further includes an open cell framework or body of struts and cells extending distally from the connection assembly  302 . In some embodiments, the distal portion  300   b  of the interventional element  300  can be generally tubular (e.g., cylindrical), and the proximal portion  300   a  of the interventional element  300  can taper proximally to the connection assembly  302 . In some embodiments, the distal portion  300   b  (e.g., the distal terminus) coincides with the distal end portion  120   b  of the elongated member  120  or treatment device  101 . The interventional element  300  has a low-profile configuration (not shown) when constrained within the first catheter  200 , and an expanded configuration for securing and/or engaging clot material or other obstructions within a blood vessel lumen (e.g., a cerebral blood vessel lumen) and/or for restoring blood flow within the blood vessel. 
     In some embodiments the interventional element  300  is a mesh structure formed of a superelastic material (e.g., Nitinol) or other resilient or self-expanding material configured to self-expand when released from the delivery catheter. For example, in some embodiments the interventional element  300  may be a stent and/or stent retriever, such as Medtronic&#39;s Solitaire™ Revascularization Device, Stryker Neurovascular&#39;s Trevo® ProVue™ Stentriever, or other suitable devices. In other embodiments, the interventional element  300  may include a plurality of braided filaments. Examples of suitable interventional element  300  include any of those disclosed in U.S. Pat. No. 7,300,458, filed Nov. 5, 2007, U.S. Pat. No. 8,940,003, filed Nov. 22, 2010, U.S. Pat. No. 9,039,749, filed Oct. 1, 2010, U.S. Pat. No. 8,066,757, filed Dec. 28, 2010, and U.S. Pub. No. 2018/0325534, filed May 12, 2017, each of which is incorporated by reference herein in its entirety. 
       FIGS.  13 - 17    are side schematic views of embodiments of a portion of the system  11  and treatment device  101  shown in  FIG.  12   , in which the distal element  140  and/or interventional element  300  are movable relative to one another and/or the elongated member  120 . Unless stated otherwise, each of the distal element  140  and/or the interventional element  300  may be rotatably and/or slidably coupled to the elongated member  120  (or fixedly mounted without capability to rotate or slide) in any of the embodiments shown in  FIGS.  13 - 17   . As such, any rotation of the distal element  140  and/or the interventional element  300  that occurs during movement of the treatment device  101  through a catheter in tortuous vasculature is not transferred to the elongated member  120  (or only a reduced portion of such rotation is transferred to the elongated member). By reducing or preventing rotation or “winding up” of the elongated member  120 , the rotatably coupled feature can help reduce the force needed to move the treatment device  101  through a catheter, and any “whipping” effect that can occur as the distal element  140  and/or the interventional element  300  counter-rotates suddenly upon exiting the catheter. In addition, this capability allows the elongated member  120  to be rotated to facilitate pointing the distal end  120   b  of the elongated member  120  in the desired direction of advancement (e.g. at a vessel junction or curve), without need to correspondingly rotate the interventional element  300  and/or distal element  140  within the blood vessel or catheter. Without the ability to rotate the elongated member  120  relative to the element(s)  300 ,  140 , it would be necessary to rotate the entire system  11  to navigate it as desired, which can be physically difficult if the element(s)  300 ,  140  are compressed within a catheter or potentially injurious when they are expanded in a blood vessel. 
     In some embodiments of  FIGS.  13 - 17    in which one or both of the distal element  140  and/or interventional element  300  are not fixedly coupled to the elongated member  120  (e.g., are rotatably and/or slidably coupled to the elongated member  120 ), the system  11  and treatment device  101  can include a second elongated member  120 . In such embodiments, the distal element  140  and interventional element  300  may be disposed on separate elongated members  120  (e.g., respective first and second elongated members) such that movement of one of the distal element  140  or interventional element  300  via movement of the corresponding elongated member  120  is controlled separately from movement of the other of the distal element  140  and interventional element  300 . 
       FIG.  13    is a side schematic view of an embodiment of a portion of the system  11  and treatment device  101  in which the interventional element  300  is slidably coupled to the elongated member  120  via a slidable connection assembly  302  positioned on the elongated member  120 . At least one stop  304  is fixedly coupled to the elongated member  120  proximal of the interventional element  300  and/or connection assembly  302 . In such embodiments, the interventional element  300  can be longitudinally movable relative to the elongated member  120  and/or the distal element  140  between the stop  304  and the distal element  140 . The stop  304  may include any shape and/or size that prevents or inhibits movement of the interventional element  300  proximally thereof. In some embodiments, the stop  304  may be formed integrally with the elongated member  120  or as a separate component. The distal element  140  can be fixedly and/or slidably/rotatably coupled to the elongated member  120  via connection assembly  130 . 
     The system  11  and treatment device  101  of  FIG.  13    can optionally include a stop  306  (e.g., a second stop) fixedly coupled to the elongated member  120  between the interventional element  300  (e.g., the connection assembly  302  thereof) and the distal element  140 . In such embodiments, the interventional element  300  can be slidably/rotatably coupled to the elongated member  120 , e.g., via connection assembly  302 , and longitudinally movable relative to the elongated member  120  between the stops  304  and  306 . 
       FIG.  14    is a side schematic view of another embodiment of a portion of the system  11  and treatment device  101  in which the distal element  140  is slidably coupled to the elongated member  120  via a slidable connection assembly  130  positioned on the elongated member  120 . At least one stop  308  is fixedly coupled to the elongated member  120  distal of the distal element  140 . In such embodiments, the distal element  140  can be longitudinally movable relative to the elongated member  120  between the stop  308  and the interventional element  300 . The stop  308  may include any shape and/or size that inhibits movement of the distal element  140  distally thereof. In some embodiments, the stop  308  may be formed integrally with the elongated member  120  or as a separate component. The interventional element  300  can be fixedly and/or rotatably coupled to the elongated member  120 , e.g. via connection assembly  302 . 
     The system  11  and/or treatment device  101  of  FIG.  14    can optionally include a stop  310  (e.g., a second stop) fixedly coupled to the elongated member  120  between the interventional element  300  (e.g., the distal portion  300   b  of the interventional element  300 ) and the connection assembly  130  of the distal element  140 . In such embodiments, the distal element  140  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , and longitudinally movable relative to the elongated member  120  between the stops  308  and  310 . 
       FIG.  15    is a side schematic view of another embodiment of a portion of the system  11  and treatment device  101  in which the distal element  140  and the interventional element  300  are each slidably coupled to the elongated member  120  via their respective slidable connection assemblies  130 ,  302  positioned on the elongated member  120 . A stop  304  (e.g., a first stop) can be fixedly coupled to the elongated member  120  proximal of the interventional element  300 , a stop  308  (e.g., a second stop) can be fixedly coupled to the elongated member  120  distal of the distal element  140 , and a stop  310  (e.g., a third stop) fixedly coupled to the elongated member  120  between the interventional element  300  (e.g., the distal portion  300   b  of the interventional element  300 ) and the distal element  140 . In such embodiments, (a) the distal element  140  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , and longitudinally movable relative to the elongated member  120  between the stops  308  and  310 , and (b) the interventional element  300  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  302 , and longitudinally movable relative to the elongated member  120  between the stops  304  and  310 . 
       FIG.  16    is a side schematic view of another embodiment of a portion of the system  11  and treatment device  101  in which the distal element  140  is slidably coupled to the elongated member  120 . As shown in  FIG.  14   , the system  11  and/or treatment device  101  includes the interventional element  300  and distal element  140  disposed over the elongated member  120 , and a stop  308  fixedly coupled to the elongated member  120  distal of the distal element  140 , and a tube  312  disposed over the elongated member  120  and coupled to the interventional element  300  (e.g., the proximal portion  300   a  of the interventional element  300 ). In some embodiments, the elongated member  120  can move longitudinally within a lumen of the tube  312 . As such, the elongated member  120  and the distal element  140  can together be slidably moved with respect to the interventional element  300  and the tube  312 . In addition or alternatively, the distal element  140  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , such that the distal element  140  is longitudinally movable relative to the elongated member  120  at least between the stop  308  and the interventional element  300 . The tube  312  can extend to the proximal end or portion  100   a  of the treatment device  100  (and/or to the proximal end or portion  10   a  of the treatment system  10 ), e.g. to allow a user to manipulate both the tube  312  and the elongated member  120  independently of each other, from the proximal ends thereof. Accordingly, this configuration permits some slidability of the distal element  140  with respect to the elongated member  120 , and also permits the interventional element  300  and the distal element  140  to be slidably and/or rotatably moved independently of one another. In some instances, it can be useful to controllably vary the longitudinal distance between the distal portion  300   b  (e.g., the distal end) of the interventional element  300  and the proximal portion  140   a  (e.g., the proximal end) of the distal element  140 . For example, following deployment of the interventional element  300  into or adjacent a thrombus, the distal element  140  can be slidably retracted or advanced relative to the interventional element  300  and/or thrombus as desired by the clinician. Among other advantages, this capability also allows for adjustability of the system  100  in order to fit the vasculature which varies from one patient to another. 
     As shown in  FIG.  16   , in some embodiments, the system  11  and/or treatment device  101  can optionally include a stop  310  (e.g., a second stop) fixedly coupled to the elongated member  120  between the interventional element  300  (e.g., the distal portion  300   b  of the interventional element  300 ) and the distal element  140 . In such embodiments, the distal element  140  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , and longitudinally movable relative to the elongated member  120  between the stops  308  and  310 . 
       FIG.  17    is a side schematic view of another embodiment of a portion of the system  11  and treatment device  101 . As shown in  FIG.  17   , the system  11  and/or treatment device  101  includes the interventional element  300 , the distal element  140  (e.g., a first distal element) located distal of the interventional element  300 , and a distal element  141  (e.g., a second distal element) located proximal of the interventional element  300 . These components are slidably coupled to the elongated member  120  via their respective connection assemblies  302 ,  130 . The system  11  and treatment device  101  can further include a stop  308  (e.g., a first stop) fixedly coupled to the elongated member  120  distal of the distal element  140 , a stop  314  (e.g., a second stop) fixedly coupled to the elongated member  120  proximal of the distal element  141 , and a stop  310  (e.g., a third stop) fixedly coupled to the elongated member  120  between the distal element  140  and the interventional element  300  (e.g., the distal portion  300   b  of the interventional element  300 ). In such embodiments, one or more of the distal element  140 , distal element  141 , and interventional element  300  may be rotatably and/or slidably coupled to the elongated member  120 . For example, only the distal element  140 , only the interventional element  300 , only the distal element  141 , both the distal element  140  and the interventional element  300 , both the distal element  141  and the interventional element  300 , both the distal elements  140  and  141 , or all of the distal element  140 , interventional element  300 , and distal element  141  may be rotatably and/or slidably coupled to the elongated member. For example, as shown in  FIG.  17   : (a) the distal element  140  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , and longitudinally movable relative to the elongated member  120  between the stops  308  and  310 , (b) the interventional element  300  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  302 , and longitudinally movable relative to the elongated member  120  between the distal element  141  and stop  310 , and (c) the distal element  141  can be slidably coupled to the elongated member  120 , e.g., via connection assembly  130 , and longitudinally movable relative to the elongated member  120  between the stop  314  and the interventional element  300 . 
     In another embodiment of the system  11  and treatment device  101 , the distal element(s)  140  may be omitted and the interventional element  300  rotatably (or rotatably and slidably) mounted on the elongated member  120 . This embodiment would offer the advantage of being navigable (along with, and while positioned in a distal portion of, the third catheter  220 ) to the treatment area via the rotatable distal portion  120   b  of the elongated member  120  and the third catheter  220 . 
     The embodiments of the treatment device  101  shown in  FIGS.  13 - 17    offer useful advantages by allowing for relative movement of the active components of the device during a treatment procedure, which helps accommodate variations in vasculature from patient to patient. The physician is therefore provided some freedom to place the interventional element  300 , distal element(s)  140 , and/or any distal extension of the elongated member  120  to ensure they will be most effective and/or safely deployed, taking into consideration the vasculature of the specific patient being treated. Similarly, these embodiments can allow the physician to adjust the effective length of (e.g., shorten) any distal extension of the elongated member and avoid needlessly endangering the vasculature distal of the treatment site. 
       FIGS.  18 A- 18 D  illustrate a method of removing clot material CM from the lumen of a blood vessel V using the treatment system  11 , in accordance with embodiments of the present technology. Similar to the method described above with respect to  FIGS.  10 A and  10 B , the first catheter  200  can be advanced through the vasculature and positioned within the blood vessel V such that a distal portion of the first catheter  200  is proximal of the clot material CM (for example, as shown in  FIG.  10 A ). The second catheter  210  may be advanced through the first catheter  200  until a distal portion of the second catheter  210  is at or proximal to the clot material CM. In some embodiments, the first catheter  200  can be secured in place using a balloon  1001  or other expandable member configured to engage the vessel wall. Next, the third catheter  220  may be advanced through the second catheter  210  so that a distal portion of the third catheter  220  is positioned at or near the clot material CM. In some embodiments, the third catheter  220  may be positioned such that a distal terminus  221  of the third catheter  220  is distal of the clot material CM. As shown in  FIG.  18 A , the interventional element  300  and/or the distal element  140  may then be advanced through the third catheter  220  in a low-profile configuration until a distal terminus of the distal element  140  is at or adjacent the distal terminus of the third catheter  220 . In some embodiments, the interventional element  300  and distal element  140  may be delivered to the blood vessel V together via the same delivery or individually via separate deliveries. In such embodiments where the interventional element  300  and distal element  140  are delivered separately, the distal element is deployed, e.g., from the third catheter  220 , distal of the clot material CM via a first delivery, and then the interventional element  300  is deployed, e.g., from the third catheter  220 , distal of or in the clot material CM via a second delivery. 
     As shown in  FIG.  18 A , the third catheter  220  may be withdrawn proximally relative to the distal element  140  and the interventional element  300  to release both the distal element  140  and the interventional element  300 . This allows the distal element  140  to self-expand into apposition with the vessel wall distal of the clot material CM and interventional element  300 , and allows the interventional element  300  to self-expand within the clot material CM. As the interventional element  300  expands, the interventional element  300  engages and/or secures the surrounding clot material CM, and in some embodiments may restore or improve blood flow through the clot material CM by pushing open a blood flow path therethrough (which flow path can extend through the expanded distal member  140 ). In some embodiments, both the distal element  140  and the interventional element  300  may be expanded distal of the clot material CM such that no portion of the distal element  140  or the interventional element  300  is engaging the clot material CM while the distal element  140  and the interventional element  300  are in the process of expanding toward the vessel wall. In some embodiments, one or both of the distal element  140  and the interventional element  300  are configured to expand into contact with the wall of the vessel V, or the distal element  140 , and/or the interventional element  300  may expand to a diameter that is less than that of the blood vessel lumen such that the distal element  140  and/or the interventional element  300  do not engage the entire circumference of the blood vessel wall. 
     Once the interventional element  300  has been expanded into engagement with the clot material CM (and the distal element  140  has been expanded at a position distal to the clot material CM), the interventional element  300  may grip the clot material CM by virtue of its ability to mechanically interlock with the clot material CM. The distally positioned distal element  140  can block, collect, or otherwise engage with any portions of clot material CM that migrate downstream from the interventional element  300 , thereby reducing the risk of additional vessel blockages in distally-located areas of the brain that are more difficult to reach. 
     Referring now to  FIG.  18 B , in some embodiments, aspiration may be applied to the treatment site, e.g., via the second catheter  210 . For example, following deployment of the distal element  140  and the interventional element  300 , the third catheter  220  can be retracted and removed from the lumen of the second catheter  210 . The treatment site can then be aspirated via the second catheter  210 , for example via a suction source such as a pump or syringe coupled to a proximal portion of the second catheter  210 . In some embodiments, aspiration is applied while the interventional element  300  is retracted into the second catheter  210 . Aspiration at this stage can help secure the clot material CM within the second catheter  210  and prevent any dislodged portion of the clot material CM from escaping the second catheter  210  and being released back into the vessel V. In various embodiments, the treatment site can be aspirated continuously before, during, or after retraction of the interventional element  300  into the second catheter  210 . 
     With reference to  FIGS.  18 C and  18 D , while the interventional element  300  is engaged with the clot material CM, the clot material CM can be removed. For example, the interventional element  300 , with the clot material CM gripped thereby, and the distally positioned distal element  140  can be retracted proximally (e.g., along with the second catheter  210  and, optionally, the first catheter  200 , or into the second catheter  210 ). When the interventional element  300  and clot material CM are retracted into the second catheter  210 , the distal element  140  can help push the clot material CM into the second catheter  210  lumen and subsequently be drawn into the catheter, or left in the expanded configuration, distal of the catheter  210  as a filter/pusher ( FIG.  18 D ). The second catheter  210 , distal element  140 , interventional element  300 , and engaged clot material CM may then be withdrawn from the treatment site, optionally through one or more larger surrounding catheters. During this retraction, any portions of clot material CM that dislodge from the interventional element  300  can be caught by the distal element  140 , thereby preventing downstream migration of such clot material CM fragments. As shown in  FIG.  18 D , the retraction can optionally continue until the distal element  140  abuts the distal end of the second catheter  210  and is retracted into the lumen of the second catheter  210 . In some embodiments, the interventional element  300  and clot material CM form a removable, integrated thrombus-device mass. 
     In some embodiments, the distal element  140  may be used to expand other expandable devices, such as a flow diverter or a stent. In some embodiments, all or a portion of the distal element  140  may be covered with a polymer and used for flow arrest proximally. If the distal half of the distal element  140  was covered, it may be used for flow directed navigation like a sail. This could be helpful in navigating a tortuous arch or other bifurcations. 
     IV. EXAMPLE ELECTRICALLY ENHANCED TREATMENT DEVICES AND METHODS OF USE 
       FIG.  19 A  illustrates a view of an electrically enhanced treatment system  12  according to one or more embodiments of the present technology. Several features of the treatment system  12  can be similar to that of the treatment system  10  shown in  FIG.  1    and described above. For example, the catheters  200 ,  210 ,  220 , elongated member  120 , and distal element  140  can include some or all of the features described above with respect to  FIGS.  1 - 9 ,  10 - 18 E and  25 A- 26 B . As shown in  FIG.  19 A , the treatment system  12  can include a current generator  20  and a treatment device  102  having a proximal portion  102   a  configured to be coupled to the current generator  20  and a distal portion  102   b  configured to be intravascularly positioned within a blood vessel (such as an intracranial blood vessel) at a treatment site at or proximate a thrombus. The treatment device  102  includes a distal element  140  at the distal portion  102   b , a handle  16  at the proximal portion  102   a , and a plurality of coaxially disposed catheters  200 ,  210 , and  220  as described previously. The current generator  20  may be coupled to a proximal portion of one or more of the elongated member  120 , the third catheter  220 , the second catheter  210 , and/or the first catheter  200  to provide an electrically charged environment at the distal portion  102   b  of the treatment device  102 , as described in more detail below. Any of the embodiments or versions of the above-mentioned components that are described herein with reference to the treatment system  10  of  FIG.  1    or the treatment system  11  of  FIG.  11    can be employed in connection with the treatment system  12  as well. 
     As described previously herein, the distal element  140  may comprise an expandable body of woven filaments having a low-profile or constrained state while positioned within a catheter for delivery to a deployment location and an expanded state in which at least a portion of the body is configured to be in apposition with the blood vessel wall. The distal element  140  is configured to expand into contact with the blood vessel wall at desired locations along the intravascular path to the treatment site as well as at the treatment site to anchor and/or stabilize the elongated member  120  or any portion of the treatment system  12  at the desired location. As detailed elsewhere herein, the distal element  140  may also be configured to facilitate removal of the thrombus from the treatment site. 
     In some embodiments, the treatment system  12  includes a suction source  25  (e.g., a syringe, a pump, etc.) configured to be fluidly coupled (e.g., via a connector  23 ) to a proximal portion of one or more of the catheters  200 ,  210 ,  220  to apply negative pressure therethrough. In some embodiments, the treatment system  12  includes a fluid source  27  (e.g., a fluid reservoir, a syringe, pump, etc.) configured to be fluidly coupled (e.g., via the connector  23 ) to a proximal portion of one or more of the catheters  200 ,  210 ,  220  to supply fluid (e.g., saline, contrast agents, a drug such as a thrombolytic agent, etc.) to the treatment site. 
     According to some embodiments, the current generator  20  can be configured to output medically useful electric current.  FIGS.  19 B and  19 C  are schematic views of different embodiments of the current generator  20 . With reference to  FIG.  19 B , the current generator  20  can include a power source  1922 , a first terminal  1924 , a second terminal  1926 , and a controller  1928 . The controller  1928  includes a processor  1930  coupled to a memory  1932  that stores instructions (e.g., in the form of software, code or program instructions executable by the processor or controller) for causing the power source  1922  to deliver electric current according to certain parameters provided by the software, code, etc. The power source  1922  of the current generator  20  may include a direct current power supply, an alternating current power supply, and/or a power supply switchable between a direct current and an alternating current. The current generator  20  can include a suitable controller that can be used to control various parameters of the energy output by the power source or generator, such as intensity, amplitude, duration, frequency, duty cycle, and polarity. For example, the current generator  20  can provide a voltage of about 2 volts to about 28 volts and a current of about 0.5 mA to about 20 mA. 
       FIG.  19 C  illustrates another embodiment of the current generator  20 , in which the controller  1928  of  FIG.  19 B  is replaced with drive circuitry  1934 . In this embodiment, the current generator  20  can include hardwired circuit elements to provide the desired waveform delivery rather than a software-based generator of  FIG.  19 B . The drive circuitry  1934  can include, for example, analog circuit elements (e.g., resistors, diodes, switches, etc.) that are configured to cause the power source  1922  to deliver electric current via the first and second terminals  1924 ,  1926  according to the desired parameters. For example, the drive circuitry  1934  can be configured to cause the power source  1922  to deliver periodic waveforms via the first and second terminals  1924 ,  1926 . 
     As noted above, the current generator  20  may be coupled to a proximal portion of the elongated member  120 , and/or a proximal portion of one or more of the catheters  200 ,  210 ,  220  ( FIG.  19 A ) to provide an electric current to the distal element  140 . For example, in some embodiments, both terminals  1924 ,  1926  of the current generator  20  are coupled to the elongated member  120  such that the elongated member  120  functions as both a delivery electrode or conductive path (i.e., transmitting current from the current generator  20  to the treatment site) and a return electrode or conductive path (i.e., transmitting current from the treatment site to the current generator  20 ) (described in greater detail below with reference to  FIG.  20 B ). In other embodiments, the return electrode can be separate from the elongated member  120 . For example, the return electrode can be carried by one or more of the catheters  200 ,  210 ,  220 . In some embodiments, the return electrode can be provided via one or more optional external electrodes  1929  ( FIG.  19 A ), such as a needle puncturing the patient, or a grounding pad applied to the patient&#39;s skin. In some embodiments, the return electrode can be an insulated guide wire having an exposed, electrically conductive portion at its distal end. 
       FIG.  20 A  is a side schematic view of a portion of the system  12  and treatment device  102  shown in  FIG.  19 A . The system  12  can include multiple (e.g., two or more), distinct conductive paths or channels for passing electrical current along the system  12 . The distal element  140  can serve as one electrode (e.g., the delivery electrode) in electrical communication with a conductive path integrated into the elongated member  120 . Another of the conductive paths of the system  12  can be in electrical communication with another electrode (e.g., a return electrode). The various embodiments of the elongated member  120  can be sized for insertion into a bodily lumen, such as a blood vessel, and can be configured to deploy, push and pull a device such as the distal element  140  along the bodily lumen. 
     As noted above, the distal element  140  (or a portion thereof) can serve as the delivery electrode and be electrically coupled to a positive terminal of the current generator  20  ( FIG.  19 A ). As shown in  FIG.  20 B , in some embodiments, the elongated member  120  can include an elongate conductive shaft  2011  (e.g., a pushwire) extending along the length of the elongated member  120 . The shaft  2011  can be in electrical communication with the current generator  20  ( FIG.  19 A ) at its proximal end and with the distal element  140  at its distal end. The shaft  2011  can be insulated along at least a portion of its length, with exposed portions permitting electrical communication with the current generator  20  and the distal element  140 . 
     The return electrode(s) can assume a variety of configurations in different embodiments. For example, in some embodiments, the return electrode is an external electrode  29  ( FIG.  19 A ), such as a needle or grounding pad that is applied to a patient&#39;s skin. The needle or grounding pad can be coupled via one or more leads to the current generator  20  to complete the electrical circuit. In some embodiments, the return electrode is carried by a surrounding catheter (e.g., third catheter  220 , second catheter  210 , and/or first catheter  200 ), as described in more detail elsewhere herein. 
     According to some embodiments, for example as shown in  FIG.  20 A , the catheters  200 ,  210 ,  220  can each be formed as a generally tubular member extending along and about a central axis and terminating in a respective distal end  2001 ,  2002 , and  2003 . According to some embodiments, the first catheter  200  is generally constructed to track over a conventional guidewire in the cervical anatomy and into the cerebral vessels associated with the brain and may also be chosen according to several standard designs that are generally available. Accordingly, the first catheter  200  can have a length that is at least 125 cm long, and more particularly may be between about 125 cm and about 175 cm long. Other designs and dimensions are contemplated. 
     The second catheter  210  can be sized and configured to slidably extend through the first catheter  200 . As noted above, the second catheter  210  can be coupled at a proximal portion to a suction source  25  ( FIG.  19 A ) such as a pump or syringe in order to supply negative pressure to a treatment site. The third catheter  220  can be sized and configured to slidably extend through both the second catheter  210  and the first catheter  200 . In some embodiments, the first catheter  200  is a balloon-guide catheter having an inflatable balloon or other expandable member that can be used to anchor the first catheter  200  with respect to a surrounding vessel. As described in more detail below, in operation the first catheter  200  can first be advanced through a vessel and then a balloon can be expanded to anchor the first catheter  200  in place and/or arrest blood flow from areas proximal of the balloon. Next, the second catheter  210  can be advanced through the first catheter  200  until its distal end  2002  extends distally beyond the distal end  2003  of the first catheter  200 . The second catheter  210  can be positioned such that its distal end  2002  is adjacent a treatment site (e.g., a site of a blood clot within the vessel). The third catheter  220  may then be advanced through the second catheter  210  until its distal end  2001  extends distally beyond the distal end  2002  of the second catheter  210 . The distal element  140  may then be advanced through the third catheter  220  via the elongated member  120  for delivery to the treatment site. 
     According to some embodiments, an electrode  2004  is provided at a distal end region of the third catheter  220 . The electrode  2004  can form an annular ring that extends entirely circumferentially about the central axis of the third catheter  220 . Alternatively or in combination, the electrode  2004  can extend less than entirely circumferentially around the third catheter  220 . For example, the electrode  2004  may be entirely disposed on one radial side of the central axis. By further example, the electrode  2004  may provide a plurality of discrete, noncontiguous electrode sections about the central axis. Such sections of the electrode  2004  can be in electrical communication with a common conductive path so as to function collectively as a single electrode, or with multiple separate such paths to allow the sections to function independently if desired. The electrode  2004  can be a band, a wire, or a coil embedded in the wall of the third catheter  220 . According to some embodiments, the electrode  2004  can be longitudinally separated from the distal end  2001  of the third catheter  220  by a non-conductive portion of the third catheter  220 . Alternatively, a distal portion of the electrode  2004  can extend to the distal end  2001  of the third catheter  220 , such that the electrode  2004  forms a portion of the distal end  2001 . According to some embodiments, an inner surface of the electrode  2004  can be flush with an inner surface of the third catheter  220 . Alternatively or in combination, the inner surface of the electrode  2004  can extend more radially inwardly relative to the inner surface of the third catheter  220  (e.g., providing a “step”). Alternatively or in combination, the inner surface of the electrode  2004  can extend less radially inwardly relative to the inner surface of the third catheter  220  (e.g., be recessed into the body). According to some embodiments, the electrode  2004  can be surrounded radially by an outer section of the third catheter  220  to provide insulation from an external environment. In some embodiments, an outer surface of the electrode  2004  can be flush with an outer surface of the third catheter  220  and can provide an exposed, radially outwardly facing electrode surface. In such instances, a radially inner section of the third catheter  220  can provide insulation from the environment within the lumen of the third catheter  220 . 
     The electrode  2004  can include one or more rings, one or more coils or other suitable conductive structures, and can each form at least one surface (e.g., an inner surface or an outer surface) that is exposed and configured for electrical activity or conduction. The electrode  2004  can have a fixed inner diameter or size, or a radially expandable inner diameter or size. In some embodiments, the electrode  2004  is a deposited or “painted” electrode. The electrode can include platinum, platinum alloys (e.g., 92% platinum and 8% tungsten, 90% platinum and 10% iridium), gold, cobalt-chromium, stainless steel, nitinol, and combinations thereof, or any suitable conductive materials, metals or alloys. 
     In some embodiments, the electrode  2004  can be a separate expandable member coupled to an outer surface of the third catheter  220 , for example a braid, stent, or other conductive element coupled to an outer surface of the distal portion of the third catheter  220 . In some embodiments, the electrode  2004  can be part of a flow-arrest element such as an expandable braid coupled to an occlusion balloon. 
     According to some embodiments, the electrode  2004  can be electrically connected to the current generator  20  via a conductive lead  2005 . The conductive lead  2005  can extend proximally along or within the wall of the third catheter  220  to or beyond the proximal end of the third catheter  220 . The conductive lead  2005  can include more than one conductive path extending within the walls of the third catheter  220 . According to some embodiments, the conductive lead  2005  can form a helical coil along or within at least a portion of the third catheter  220 . Alternatively or in combination, the conductive lead  2005  can form a braided, woven, or lattice structure along or within at least a portion of the third catheter  220 . In some embodiments, the conductive lead  2005  can be a conductive element (e.g., a wire, coil, etc.) wrapped around an external surface of the third catheter  220 . In such instances, the conductive lead  2005  can be coated with an insulative material along at least a portion of its length. The insulative material can be, for example, Parylene, PTFE, or other suitable insulative material. 
     In some embodiments, the second catheter  210  and/or the first catheter  200  can be similarly equipped with corresponding electrodes instead of or in addition to the third catheter  220  or the elongated member  120 . For example, the second catheter  210  may include an electrode  2006  disposed at a distal end region of the second catheter  210 . The electrode  2006  can be electrically connected to the current generator  20  ( FIG.  19 A ) via a conductive lead  2007  which extends proximally along the second catheter  210 . The configuration of the electrode  2006  and the corresponding conductive lead  2007  can be similar to any of the variations described above with respect to the electrode  2004  and the conductive lead  2005  of the first catheter  200 . 
     In some embodiments, the first catheter  200  includes an electrode  2008  disposed at a distal end region of the first catheter  200 . The electrode  2008  can be electrically connected to the current generator  20  ( FIG.  19 A ) via a conductive lead  2009  which extends proximally along the first catheter  200 . The configuration of the electrode  2008  and the corresponding conductive lead  2009  can be similar to any of the variations described above with respect to the electrode  2004  and the conductive lead  2005  of the third catheter  220 . 
     In various embodiments, the system can include any combination of the electrodes  2004 ,  2006 , and  2008  described above. For example, the system may include the electrode  2004  and the corresponding conductive lead  2005  of the third catheter  220 , while the second catheter  210  and the first catheter  200  may be provided with no electrodes or conductive leads therein. In some embodiments, the system may only include the electrode  2006  of the second catheter  210 , while the first catheter  200  and the third catheter  220  may be provided with no electrodes or conductive leads therein. In some embodiments, the system may include only the electrode  2008  of the first catheter  200 , while the third catheter  220  and the second catheter  210  are provided with no electrodes or corresponding conductive leads therein. In some embodiments, any two of the catheters  200 ,  210 ,  220  can be provided with electrodes and corresponding leads, while the remaining catheter may have no electrode or conductive lead therein. 
     In the configuration illustrated in  FIG.  20 A , one or more of electrodes  2004 ,  2006 , or  2008  can be coupled to a negative terminal of the current generator  20 , while the distal element  140  can be coupled to the positive terminal of the current generator  20  via the elongated member  120 . As a result, when voltage is applied at the terminals and the distal element  140  placed in the presence of blood (or any other electrolytic medium), current flows from the distal element  140 , through the blood or other media, and to the return electrode. The return electrode may a conductive element carried by one or more of the catheters  200 ,  210 ,  220  as described above, or the elongated member  120 , or in some embodiments the return electrode can be an external electrode  29  ( FIG.  19 A ) such as needle or grounding pad. 
     In some embodiments, one or more catheters carrying an electrode can be used without an electrically coupled distal element  140 . In various embodiments, the distal element  140  may be omitted altogether, or the distal element  140  may be included but may not be electrically coupled to the current generator  20 . In such cases, a catheter-based electrode (e.g., the electrode  2004  carried by the third catheter  220 , the electrode  2006  carried by the second catheter  210 , or the electrode  2008  carried by the first catheter  200 ) can function as the delivery electrode, and a separate return electrode can be provided either in the form of another catheter-based electrode (either carried by the same catheter or carried by another catheter) or as an external electrode (e.g., a needle or grounding pad). In instances in which a single catheter carries two electrodes, one electrode may be provided on an exterior surface of the catheter while the other electrode may be provided on an inner surface of the catheter. For example, the second catheter  210  may include a delivery electrode in the form of a conductive band disposed on an inner surface of the catheter  210 , in addition to a return electrode in the form of a conductive band disposed on an outer surface of the catheter  210 . 
     As described in more detail in  FIG.  20 B , in some embodiments the return electrode can be integrated into the elongated member  120  of the treatment system  12 , such that the elongated member  120  carries two separate conductive paths along its length.  FIG.  20 B  is a side schematic cross-sectional view of a portion of the treatment system  12  shown in  FIG.  20 A , in accordance with embodiments of the present technology. As shown in  FIG.  20 B , the elongated member  120  includes an elongate conductive shaft  2011  and an elongate tubular member  2012  having a lumen through which the shaft  2011  extends. The shaft  2011  has a distal portion  2010 , and the tubular member  2012  has a distal portion  2018 . Both the shaft  2011  and the tubular member  2012  are electrically conductive along their respective lengths. In some embodiments, the positions of the shaft  2011  and the tubular member  2012  are fixed relative to one another. For example, in some embodiments the shaft  2011  is not slidable or rotatable with respect to the tubular member  2012  such that the elongated member  120  can be pushed or pulled without relative movement between the shaft  2011  and the tubular member  2012  and/or other individual components of the elongated member  120 . 
     In some embodiments, the shaft  2011  can be a solid pushwire, for example a wire made of Nitinol, stainless steel, or other metal or alloy. The shaft  2011  may be thinner than would otherwise be required due to the additional structural column strength provided by the surrounding tubular member  2012 . The tubular member  2012  can be a hollow conductive tube, hypotube, braid, coil, or other suitable member(s), or a combination of wire(s), tube(s), braid(s), coil(s), etc. In some embodiments, the tubular member  2012  can be a laser-cut hypotube having a spiral cut pattern (or other pattern of cut voids) formed in its sidewall along at least a portion of its length. The tubular member  2012  can be made of stainless steel (e.g., 304 SS), Nitinol, and/or other alloy. In at least some embodiments, the tubular member  2012  can have a laser cut pattern to achieve the desired mechanical characteristics (e.g., column strength, flexibility, kink-resistance, etc.). 
     The elongated member  120  can also include an adhesive or a mechanical coupler such as a crimped band or marker band  2020  disposed at the distal end of the elongated member  120 , and the marker band  2020  can optionally couple the distal end of the elongated member  120  to the distal element  140 . The marker band  2020  can be radiopaque, for example including platinum or other radiopaque material, thereby enabling visualization of the proximal end of the distal element  140  under fluoroscopy. In some embodiments, additional radiopaque markers can be disposed at various locations along the treatment system  12 , for example along the shaft  2011 , the tubular member  2012 , or the distal element  140  (e.g., at the distal end, or along the length, of the distal element  140 ). 
     In at least some embodiments, the elongated member  120  also includes a first insulating layer or material  2022  extending between the shaft  2011  and the surrounding tubular member  2012 . The first insulating material  2022  can be, for example, PTFE (polytetrafluoroethylene or TEFLON™) or any other suitable electrically insulating coating (e.g., polyimide, oxide, ETFE-based coatings, or any suitable dielectric polymer). In some embodiments, the first insulating material  2022  extends along substantially the entire length of the shaft  2011 . In some embodiments, the first insulating material  2022  separates and electrically insulates the shaft  2011  and the tubular member  2012  along the entire length of the tubular member  2012 . In some embodiments, the first insulating material  2022  does not cover the proximal-most portion of the shaft  2011 , providing an exposed region of the shaft to which the current generator  20  ( FIG.  19 A ) can be electrically coupled. In some embodiments, for example, the first insulating material  2022  terminates proximally at the proximal terminus of the shaft, and the current generator  20  ( FIG.  19 A ) can electrically couple to the shaft  2011  at its proximal terminus, for example using a coaxial connector. 
     The elongated member  120  can additionally include a second insulating layer or material  2024  surrounding the tubular member  2012  along at least a portion of its length. The second insulating material  2024  can be, for example, PTFE or any other suitable electrically insulative coating (e.g., polyimide, oxide, ETFE based coatings or any suitable dielectric polymer). In some embodiments, the distal portion  2018  of the tubular member  2012  is not covered by the second insulating material  2024 , leaving an exposed conductive surface at the distal portion  2018 . In some embodiments, the length of the exposed distal portion  2018  of the tubular member  2012  can be at least (or equal to) 1, 2, 3, 4, 5, 6, or more inches. In some embodiments, the length of the exposed distal portion  2018  of the tubular member  2012  can be between at least 1 and 10 inches, or between 2 inches and 8 inches, or between 3 and 7 inches, or between 4 and 6 inches, or about 5 inches. This exposed portion of the distal portion  2018  of the tubular member  2012  provides a return path for current supplied to the delivery electrode (e.g. the entirety or a portion of the distal element  140 ), as described in more detail below. In some embodiments, the second insulating material  2024  does not cover the proximal-most portion of the tubular member  2012 , providing an exposed region of the tubular member  2012  to which the current generator  20  ( FIG.  19 A ) can be electrically coupled. In some embodiments, the second insulating material  2024  proximally terminates at the proximal terminus of the tubular member  2012 , and the current generator  20  can electrically couple to the tubular member  2012  at its proximal terminus, for example using a coaxial connector. 
     In some embodiments, the elongated member  120  also includes a retraction marker in the proximal portion of the tubular member  2012 . The retraction marker can be a visible indicator to guide a clinician when proximally retracting an overlying catheter with respect to the elongated member  120 . For example, the retraction marker can be positioned such that when a proximal end of the overlying catheter is retracted to be positioned at or near the retraction marker, the distal portion  2018  of the tubular member  2012  is positioned distally beyond a distal end of the catheter. In this position, the exposed distal portion  2018  of the tubular member  2012  is exposed to the surrounding environment (e.g., blood, tissue, etc.), and can serve as a return electrode for the elongated member  120 . 
     The proximal end of the shaft  2011  can be electrically coupled to the positive terminal of the current generator  20 , and the proximal end of the tubular member  2012  can be electrically coupled to the negative terminal of the current generator  20 . During operation, the treatment system  12  provides an electrical circuit in which current flows from the positive terminal of the current generator  20 , distally through the shaft  2011 , the distal element  140 , and the surrounding media (e.g., blood, tissue, thrombus, etc.) before returning back to the exposed distal portion  2018  of the tubular member, proximally through the tubular member  2012 , and back to the negative terminal of the current generator  20  ( FIG.  19 A ). 
     As noted above, the current generator  20  ( FIG.  19 A ) can include a power source and either a processor coupled to a memory that stores instructions for causing the power source to deliver electric current according to certain parameters, or hardwired circuit elements configured to deliver electric current according to the desired parameters. The current generator  20  may be integrated into the elongated member  120  or may be removably coupled to the elongated member  120 , for example via clips, wires, plugs or other suitable connectors. Particular parameters of the energy provided by the current generator  20  are described in more detail elsewhere herein with respect to  FIGS.  23 A- 23 E . 
     In certain embodiments, the polarities of the current generator  20  can be switched, so that the negative terminal is electrically coupled to the shaft  2011  and the positive terminal is electrically coupled to the tubular member  2012 . This can be advantageous when, for example, attempting to attract predominantly positively charged material to the distal element  140 , or when attempting to break up a clot rather than grasp it with an interventional element. In some embodiments alternating current (AC) signals may be used rather than DC. In certain instances, AC signals may advantageously help break apart a thrombus or other material. 
     As depicted in  FIGS.  20 A and  20 C , the distal element  140  may comprise an attachment portion  2030  that extends only over a portion of the distal element  140  (or the attachment portion  2030  can exclude the distal element  2030  altogether). For example, the attachment portion  2030  may extend only over a proximal portion (e.g., a proximal face, a proximal half, a proximal third, proximal quarter, etc.) of the distal element  140 . The attachment portion  2030  of the distal element  140  may be configured to interlock, capture, interface with, and/or engage a thrombus. The portion of the distal element  140  outside the attachment portion  2030  may or may not contact thrombotic material in use, but is configured to perform a function that renders it ineffective or less effective than the attachment portion for interlocking, capturing, and/or engaging with a thrombus. In some embodiments, such as that shown in  FIG.  20 A , a distal terminus of the attachment portion is proximal of the distal terminus of the distal element  140  (i.e., the attachment portion is spaced apart from the distal terminus of the distal element  140 ), and a proximal terminus of the attachment portion  2030  is at or adjacent to the band  2020 . 
     In some embodiments, the “non-attachment portion” of the distal element  140  (e.g., the entire distal element  140  other than the attachment portion) can be coated with a non-conductive or insulative material (e.g., Parylene, PTFE, or other suitable non-conductive coating) such that the coated region is not in electrical contact with the surrounding media (e.g., blood). As a result, the current carried by the elongated member  120  to the distal element  140  is only exposed to the surrounding media along the attachment portion  2030  of the distal element  140 . This can advantageously concentrate the electrically enhanced attachment effect along the attachment portion  2030  of the distal element  140 , where it is most useful, and thereby combine both mechanical contact/interlocking and the electrical enhancement provided by the delivered electrical signal. In some embodiments, a distal portion  140   b  of the distal element  140  (e.g. distal of the attachment portion  2030 ) may likewise be coated with a non-conductive material (e.g., Parylene, PTFE, or other suitable non-conductive coating), leaving only a proximal region or the attachment portion  2030  of the distal element  140  having an exposed conductive surface. 
     In some embodiments, the distal element  140  may include a conductive material positioned on some or all of its outer surface. The conductive material, for example, can be gold and/or another suitable conductor that has a conductivity greater than (or a resistivity less than) that of the material comprising the distal element  140 . The conductive material may be applied to the distal element  140  via electrochemical deposition, sputtering, vapor deposition, dip-coating, and/or other suitable means. In various embodiments, the coating may be disposed only at the outwardly facing portion of the filaments  144 , only an inwardly facing portion of the filaments  144 , only on one of the side portions or on any combination of the surface portions. 
     In some embodiments, a conductive coating (e.g., disposed over the attachment portion  2030 ) or insulative coating (e.g., disposed over non-attachment portions of the distal element  140 ) can be provided with varying thickness or concentrations. For example, in some embodiments the conductive coating is provided according to a gradient, in which the concentration or thickness of conductive material is greatest near a central region (or a proximal region) of the attachment portion  2030 , and the concentration or thickness of conductive material gradually decreases towards the edges of the attachment portion  2030 . As electrical current tends to focus in more conductive portions of the distal element  140 , such gradients can increase charge density in desired regions of the distal element  140  (e.g., providing increased charge density in a central region (or a proximal region) of the attachment portion  2030 ). 
     In some aspects of the present technology, the conductive material is disposed only on the attachment portion  2030  of the distal element  140  while the distal portion  140   b  of the distal element  140  is exposed. Because the conductive material has a much lower resistance than the underlying material comprising the distal element  140 , current delivered to the distal element  140  concentrates along the attachment portion  2030 . In several of such embodiments, the conductive material may be disposed only on the outer portion of the strut surface along the attachment portion  2030 . In other embodiments, the conductive material may be disposed on all or a portion of the filament surface along all or a portion of the length of distal element  140 . 
     As illustrated in  FIG.  20 C , some or all of the attachment portion  2030  can be located on (or formed by) the elongated member  120 , e.g. in the form of a coil  2032  disposed at a position proximal to the marker band  2020 , and proximal to the distal element  140 . The coil  2032  can be electrically conductive, for example being made of metal (e.g., stainless steel (e.g., 304 SS), Nitinol, and/or other alloy) or other suitable conductive material. In some embodiments, the coil  2032  is a separate element mounted over the shaft  2011  of the elongated member  120 . In other embodiments, shaft  2011  itself can form a coiled shape to provide the coil  2032 . In some embodiments, rather than a helical coil  2032 , other shapes and structures can be provided in the same location, for example an undulating curve, a series of bent portions, a spiral-cut or slotted-cut tube, or other suitable shape or structure. The coil  2032  (or other suitable structure) can provide increased electrode surface area in this region. When current is applied to the shaft  2011 , the increased surface area provided by the coil  2032  can enhance the ability of the electrode to contact, engage and/or grip the clot material CM, thereby increasing electrostatic attachment. As a result, in some embodiments, the attachment portion  2030  extends proximally of the distal element  140  (and/or excludes the distal element  140 ) and can include the coil  2032  and a portion of the elongated member  120 . 
     In some embodiments, individual filaments  144  or groups of filaments  144  of the distal element  140  can be individually electrically addressable. For example, a first group of filaments  144  can be electrically addressable, for example being coupled to a first terminal of a power supply, while a second group of filaments  144  can be separately electrically addressable, for example being coupled to a second terminal of a power supply. Within the distal element  140 , the first and second groups of filaments  144  can have insulated and non-insulated portions such that an exposed, conductive portion of the first group is not in direct contact with exposed, conductive portions of the second group of filaments  144 . For example, the first group of filaments  144  can be coated with insulative material along the proximal portion  140   a  of the distal element  140  and exposed (or coated with conductive material) along the distal portion  140   b  of the distal element  140 . The second group of filaments  144  can have the opposite configuration, in which they are coated with insulative material along the distal portion  140   b  of the distal element  140  and exposed (or coated with conductive material) along the proximal portion  140   a  of the distal element  140 . In operation, when current is supplied and the distal element  140  is in the presence of electrolytic media, one group of filaments  144  can serve as the delivery electrode (e.g., having a positive electrical charge) and the other group of filaments can serve as the return electrode (e.g., having a negative electrical charge). In some embodiments, there may be three, four, five, six, or more separately electrically addressable filaments  144  or groups of filaments  144 . Such filaments  144  can extend proximally along the length of the elongated member  120 , for example extending along a distal portion of the elongated member  120  to provide separately addressable electrodes in that region. 
     In operation, delivery of electrical current to the distal element  140  can enhance retrieval of clot material. For example, referring back to  FIGS.  10 A- 10 E , the illustrated method can be electrically enhanced using a treatment system  12  as described above with respect to  FIGS.  19 A- 20 C , in which a current generator  20  is electrically coupled to one or more elements of the treatment system  12 . For example, the current generator  20  can be electrically coupled to the proximal end of the elongated member  120  and configured to deliver current to the distal element  140  (or to the attachment portion  2030  thereof, or to the attachment portion  2030  instead of the distal element  140 ) before or after the distal element  140  has been released from the third catheter  220  into the blood vessel and/or expanded into or adjacent to the clot material CM as shown in  FIG.  10 C . The distal element  140  can be left in place or manipulated within the vessel V for a desired time period while the electrical signal is being delivered. The positively charged distal element  140 /attachment portion  2030  can attract negatively charged constituents of the clot material CM, thereby enhancing the grip of the distal element  140  and/or attachment portion  2030  on the clot material CM. This allows the distal element  140  to be used to retrieve the clot material CM and push (and/or aspirate) it into the first or second catheter  200 / 210 , with reduced risk of losing grip on the thrombus or a piece thereof, which can migrate downstream and cause additional vessel blockages in areas of the brain that are more difficult to reach. 
     As shown in  FIG.  10 D , aspiration may be applied to the treatment site via the second catheter  210 . For example, following deployment of the distal element  140 , the first catheter  200  can be retracted and removed from the lumen of the second catheter  210 . The treatment site can then be aspirated via the second catheter  210 , for example via a suction source such as a pump or syringe coupled to a proximal portion of the second catheter  210 . In some embodiments, following expansion of the distal element  140 , the treatment site is aspirated concurrently with supplying electrical energy to the distal element  140  (or to the attachment portion  2030  thereof, or to the attachment portion  2030  instead of the distal element  140 ) via the current generator  20 . By combining aspiration with the application of electrical energy, any newly formed clots (e.g., any clots formed that are attributable at least in part to the application of electrical energy), or any clot pieces that are broken loose during the procedure, can be pulled into the second catheter  210 , thereby preventing any such clots from being released downstream of the treatment site. As a result, concurrent aspiration may permit the use of higher power or current levels delivered to the distal element  140  without risking deleterious effects of new clot formation. Additionally, aspiration can capture any gas bubbles formed along the distal element  140  or marker band  2020  ( FIG.  20 A ) during application of electrical energy to the distal element  140 , which can improve patient safety during the procedure. 
     In some embodiments, aspiration is applied while the distal element  140  is retracted into the second catheter  210 . During retraction, the proximal face of the distal element  140  can engage with the clot material CM and urge it proximally towards the distal end of the second catheter  210 . Aspiration at this stage can help secure the clot material CM within the second catheter  210  and prevent any dislodged portion of the clot material CM from escaping the second catheter  210  and being released back into the vessel V. In various embodiments, the treatment site can be aspirated continuously before, during, or after delivering electrical signals to the distal element  140  (and/or attachment portion  2030 ) as well as before, during, or after retraction of the distal element  140  into the second catheter  210 . 
     At least while the distal element  140  is deployed and engaging the thrombus CM, electric current may be delivered to the distal element  140  (and/or attachment portion  2030 ) to positively charge the distal element  140  or attachment portion  2030 , thereby enhancing clot adhesion to the distal element  140  or attachment portion  2030 . In some cases, electrically enhanced clot adhesion can be improved in the absence of blood flow. As such, it may be especially beneficial to arrest blood flow (e.g., via the balloon  1001  of the first catheter  200 , or a flow arrest element on the second catheter  210 ) while the distal element  140  or attachment portion  2030  is charged, and while withdrawing the distal element  140  and thrombus CM proximally. Instead of or in addition to such blood flow arrest, a flow of saline may be provided from the fluid source  27  toward the distal element  140  via the second catheter  210  and/or first catheter  200 . 
     With reference to  FIG.  10 E , while the distal element  140  is engaged with the clot material CM, the clot material CM can be removed. For example, the distal element  140 , with the clot material CM gripped or abutted thereby, can be retracted proximally (for example, into the second catheter  210  or along with the second catheter  210  and, optionally, the first catheter  200 ). The second catheter  210 , distal element  140 , and associated clot material CM may then be withdrawn from the patient, optionally through one or more larger surrounding catheters such as the first catheter  200 . During this retraction, the distal element  140  and/or attachment portion  2030  can grip the clot material CM electrically and/or electrostatically, e.g., via the application of current from a current generator as discussed herein. (As used herein with reference to gripping or retrieving thrombus or other vascular/luminal material, or to apparatus for this purpose, “electrical” and its derivatives will be understood to include “electrostatic” and its derivatives.) Accordingly, the distal element  140  and/or attachment portion  2030  can maintain an enhanced or electrically and/or electrostatically enhanced grip on the clot material CM during retraction. In other embodiments, the current generator  20  may cease delivery of electrical signals to the distal element  140  and/or attachment portion  2030  prior to retraction of the distal element  140  with respect to the vessel V. In some embodiments, the distal element  140  and clot material CM form a removable, integrated thrombus-device mass wherein the connection of the thrombus to the device is electrically enhanced, e.g. via the application of current as discussed herein. 
     In  FIG.  10 E , the clot material CM has been moved to at least partially enter the second catheter  210 . In some embodiments, the clot material CM can substantially block the lumen of the catheter  210 , thereby creating a “corking” effect that may be noticeable to a clinician supplying negative pressure to the catheter  210  as noted previously. In some embodiments, the current generator  20  can continue to supply electrical signals to the distal element  140  and the return electrode during retraction, while in other embodiments the current generator  20  can cease supplying electrical signals during retraction of the catheter  210  and the clot material CM. 
     In some instances, instead of or in addition to delivery of electrical current to the distal element  140  or attachment portion  2030 , electrical current can be delivered to an electrode carried by one or more of the catheters (e.g., the second catheter  210 ). For example, electrical signals can be supplied to the second catheter  210  via the current generator  20  to electrically charge a distal portion of the catheter  210 . For example, as described above with respect to  FIG.  20 A , in some embodiments the second catheter  210  can include an electrode disposed at its distal portion. The electrode can be any electrically conductive element, for example a conductive band extending around an inner or outer surface of the catheter  210 , a stent engaged with an inner surface of the second catheter  210 , etc. The first electrode can be electrically coupled to a conductive lead that extends proximally along the catheter  210  and is coupled at its proximal end to the positive terminal of current generator  20 . The conductive lead can be, for example, a wire, coil, or other conductive element carried by and/or coupled to the catheter  210 . In some embodiments, the conductive lead is embedded within a wall of the second catheter  210 . In other embodiments, the conductive lead is disposed along an external surface of the catheter  210  (e.g., helically wound around the outer surface of the catheter  210  along its length). The conductive lead can be covered with insulative material along a portion of its length, for example Parylene, PTFE, or other suitable insulative coating. 
     The negative terminal of the current generator  20  can be coupled to a return electrode to complete the electrical circuit with the first electrode disposed on the catheter  210 . In some embodiments, the return electrode can be an external electrode (e.g., a needle or a grounding pad coupled to the patient&#39;s skin). In other embodiments, the return electrode can be carried by a separate catheter. In some embodiments, the return electrode can be carried by the catheter  210  at a position spaced apart from the first electrode. For example, the first electrode can be a conductive element such as a band or ring disposed at a position spaced apart from the first electrode. In some embodiments, the first electrode may be exposed along a radially inner surface of the catheter  210 , while the return electrode may be exposed along a radially outer surface of the catheter  210 . In some embodiments, the return electrode can be a separate expandable member coupled to an outer surface of the catheter  210  (e.g., a balloon or other expandable member having a conductive element such as a metallic braid therein). 
     In some methods of the present technology, a guidewire (not shown) may be advanced to the treatment site and pushed through the clot material CM until a distal portion of the guidewire is distal of the clot material CM. The guidewire may be advanced through one or more of the catheters  200 ,  210 ,  220  and/or one or more of the catheters  200 ,  210 ,  220  may be advanced over the guidewire. The guidewire may be insulated along at least a portion of its length (e.g., with Parylene, PTFE, etc.), with exposed portions permitting electrical communication with the current generator  20  and the distal element  140 . For example, in some embodiments a distal portion of the guidewire may be exposed, and the guidewire may be positioned at the treatment site such that the exposed portion of the guidewire is distal of the clot material CM. A proximal end of the guidewire may be coupled to the current generator  20  such that the exposed portion of the guidewire functions as a return electrode. In some embodiments, the guidewire may be coupled to the positive terminal of the power source and the exposed portion functions as a delivery electrode. The guidewire may be used as a delivery or return electrode with any delivery or return electrode carried by any component of the treatment system (e.g., one or more of the first-third catheters  200 ,  210 ,  220 , the distal element  140 , etc.). 
       FIGS.  21 - 22    illustrate a treatment system  13  that includes a distal element  140 , an interventional element  300 , and a current generator  20  to provide an electrical charge to selected components of the system  13 . The distal element  140  (or an attachment portion  2030  thereof) and the interventional element  300  can serve as electrodes in operation of the system  13 , either of opposing polarity, with the interventional element  300  positively charged and the distal element  140  employed as a negatively charged return electrode (or vice versa), or of common polarity, with both the interventional element  300  and the distal element positively charged and some other component (e.g. the second catheter  210 , or any other suitable component) providing a negatively charged return electrode. Alternatively, the interventional element  300  can be electrically neutral or isolated from the rest of the treatment system  13 . Several features of the treatment system  13  can be similar to the treatment system  11  shown in  FIG.  11    and described above. For example, the catheters  200 ,  210 ,  220 , elongated member  120 , distal element  200 , and interventional element  300  can include some or all of the features described above with respect to  FIGS.  1 - 9 ,  10 A- 18 E and  25 A- 26 B . As shown in  FIG.  22   , both the distal element  140  and the interventional element  300  are coupled to a distal portion of the elongated member  120 . The elongated member  120  can be coupled to a current generator at its proximal end (not shown) as described previously with respect to  FIG.  20 A . The distal element  140  can be in electrical communication with the conductive shaft  2011  which is surrounded by the insulative material  2022  along its length. Any of the embodiments or versions of the above-mentioned components that are described herein with reference to the treatment system  10  of  FIG.  1   , the treatment system  11  of  FIG.  11   , or the treatment system  12  of  FIG.  19 A  can be used with the treatment system  13  as well. 
     With continued reference to  FIG.  22   , the conductive tubular member  2012  extends over the shaft  2011  and is itself covered with an insulative material  2024  along its length. As illustrated, the shaft  2011  extends distally beyond the distal end of the tubular member  2012 . In some embodiments the shaft  2011  is not slidable or rotatable with respect to the tubular member  2012  such that the elongated member  120  can be pushed or pulled without relative movement between the shaft  2011  and the tubular member  2012  and/or other individual components of the elongated member  120 . 
     The elongated member  120  can also include an adhesive or a mechanical coupler such as a crimped band or marker band  2020  disposed at the distal end of the elongated member  120  as described previously. Additionally, the elongated member  120  can include a second marker band  2034  (or other suitable mechanical coupler or adhesive) disposed at the distal end of the tubular member  2012 . The second band  2034  can couple the distal end of the tubular member  2012  with a proximal end of an interventional element  300  such that the interventional element  300  is in electrical communication with the second band  2034  and with the tubular member  2012 . 
     As described previously herein, the interventional element  300  can be generally tubular (e.g., cylindrical), and the proximal portion of the interventional element  300  can taper proximally to the proximal end, here coupled to the second band  2034 . In various embodiments, the interventional element  300  can take any number of forms, for example a removal device, a thrombectomy device, or other suitable medical device. For example, in some embodiments the interventional element  300  may be a stent and/or stent retriever, such as Medtronic&#39;s Solitaire™ Revascularization Device, Stryker Neurovascular&#39;s Trevo® ProVue™ Stentriever, or other suitable devices. In some embodiments, the interventional element  300  may be a coiled wire, a weave, and/or a braid formed of a plurality of braided filaments. In some embodiments, the interventional element  300  is a mesh structure (e.g., a braid, a stent, etc.) formed of a superelastic material (e.g., Nitinol) or other resilient or self-expanding material configured to self-expand when released from a surrounding catheter. The mesh structure may include a plurality of struts and open spaces between the struts. In some embodiments, the struts and spaces may be situated along the longitudinal direction of the interventional element  300 , the radial direction, or both. 
     As depicted in  FIG.  22   , the interventional element  300  may comprise a working length WL portion and a non-working length NWL portion. The portion of the interventional element  300  in the working length WL may be configured to interlock, capture, and/or engage a thrombus. The portion of the interventional element  300  in the non-working length NWL may contact thrombotic material in use, but is configured to perform a function that renders it ineffective or less effective than the working length WL portion for interlocking, capturing, and/or engaging with a thrombus. In some embodiments, such as that shown in  FIG.  22   , a distal terminus of the working length WL portion is proximal of the distal terminus of the interventional element  300  (i.e., the working length WL portion is spaced apart from the distal terminus of the interventional element  300 ), and the non-working length NWL portion is disposed between the working length WL and the band  2034  and/or the distal end of the tubular member  2012 . 
     In some embodiments where the interventional element  300  serves as an electrode, the non-working length NWL portion of the interventional element  300  can be coated with a non-conductive or insulative material (e.g., Parylene, PTFE, or other suitable non-conductive coating) such that the coated region is not in electrical contact with the surrounding media (e.g., blood). As a result, the current carried by the tubular member  2012  to the interventional element  300  is only exposed to the surrounding media along the working length WL portion of the interventional element  300 . This can advantageously concentrate the electrically enhanced attachment effect along the working length WL of the interventional element  300 , where it is most useful, and thereby combine both the mechanical interlocking provided by the working length WL and the electrical enhancement provided by the delivered electrical signal. In some embodiments, a distal region of the interventional element  300  (e.g. distal of the working length WL) may likewise be coated with a non-conductive material (e.g., Parylene, PTFE, or other suitable non-conductive coating), leaving only a central portion or the working length WL of the interventional element  300  having an exposed conductive surface. 
     In some embodiments, the interventional element  300  may include an additional conductive material positioned on some or all of its outer surface. The conductive material, for example, can be gold and/or another suitable conductor that has a conductivity greater than (or a resistivity less than) that of the material comprising the interventional element  300 . The conductive material may be applied to the interventional element  300  via electrochemical deposition, sputtering, vapor deposition, dip-coating, and/or other suitable means. In some embodiments, the conductive material may be disposed only on an outwardly facing surface, on an inwardly facing surface, on one or more of the side surfaces of the struts, or on any combination of surface portions. 
     In some embodiments, a first portion of the interventional element  300  is covered by a conductive material and a second portion of the interventional element  300  is covered by an insulative or dielectric material (e.g., Parylene). In some embodiments, the working length WL portion of the interventional element  300  may be covered by a conductive material while the non-working length NWL portion is covered by an insulative material. In some embodiments, a conductive material may be disposed on all or a portion of the strut surface along all or a portion of the length of the interventional element  300 , and the insulative material may be disposed on those portions of the strut surface and/or working length not covered by the conductive material. 
     The proximal end of the shaft  2011  can be electrically coupled to the negative terminal of the current generator  20 , and the proximal end of the tubular member  2012  can be electrically coupled to the positive terminal of the current generator  20 . During operation, the treatment system  13  provides an electrical circuit in which current flows from the positive terminal of the current generator  20 , distally through the tubular member  2012 , the interventional element  300 , and the surrounding media (e.g., blood, tissue, thrombus, etc.) before returning back to the distal element  140  and proximally along the tubular member  2012 , and back to the negative terminal of the current generator  20  ( FIG.  21   ). 
     In some embodiments, the distal element  140  and the interventional element  300  can be delivered using separate shafts, pushwires, or other elongated members. For example, the distal element  140  may be coupled to a distal portion of the elongated member  120 , while the interventional element  300  is coupled to a distal portion of a separate elongated member or shaft (e.g. a shaft having an internal lumen (such as the elongated shaft  170 ) in which the elongated member  120  is received). The two elongated members may be separately advanceable through a surrounding catheter, allowing the distal element  140  and the interventional element  300  to be moved rotationally and longitudinally with respect to one another. Each of the elongated members can be separately coupled to a terminal of the current generator  20 , thereby allowing the interventional element  300  to serve as a delivery electrode and the distal element  140  to serve as a return electrode, or vice versa. 
     In operation, delivery of electrical current to the interventional element  300  and the distal element  140  (and/or an attachment portion  2030  thereof) can enhance retrieval of clot material. For example, referring back to  FIGS.  18 A- 18 D , the illustrated method can be electrically enhanced using a treatment system as described above with respect to  FIG.  22   , in which a current generator  20  is electrically coupled to one or more elements of the treatment system  13 . For example, the current generator  20  can be electrically coupled to the proximal end of the elongated member  120  and configured to deliver current to the interventional element  300  and distal element  140  (and/or an attachment portion  2030  thereof) before or after the interventional element  300  and/or the distal element  140  has been released from the third catheter  220  into the blood vessel and/or expanded into or adjacent to the clot material CM as shown in  FIG.  18 A . The interventional element  300  and the distal element  140  can be left in place or manipulated within the vessel V for a desired time period while the electrical signal is being delivered. The positively charged interventional element  300  (and, where so employed, the positively charged distal element  140  as well) can attract negatively charged constituents of the clot material CM, thereby enhancing the grip of the interventional element  300  (and, when positively charged, the distal element  140 ) on the clot material CM. This allows the interventional element  300  (and possibly the distal element  140 ) to be used to retrieve the clot material CM with reduced risk of losing grip on the thrombus or a piece thereof, which can migrate downstream and cause additional vessel blockages in areas of the brain that are more difficult to reach. Additionally, the distal element  140  can serve as an additional filter (whose function is electrostatically enhanced when the distal element is positively charged) to stop any dislodged piece of thrombus or clot material CM from migrating downstream with respect to the interventional element  300 . 
     As shown in  FIG.  18 B , aspiration may be applied to the treatment site via the second catheter  210 . For example, following deployment of the interventional element  300  and the distal element  140 , the first catheter  200  can be retracted and removed from the lumen of the second catheter  210 . The treatment site can then be aspirated via the second catheter  210 , for example via a suction source such as a pump or syringe coupled to a proximal portion of the second catheter  210 . 
     In some embodiments, following expansion of the interventional element  300  and the distal element  140 , the treatment site is aspirated concurrently with supplying electrical energy to the interventional element  300  (and/or distal element  140 , either at the same or opposing polarity as the interventional element  300 ) via the current generator  20 . By combining aspiration with the application of electrical energy, any newly formed clots (e.g., any clots formed that are attributable at least in part to the application of electrical energy), or any clot pieces that are broken loose during the procedure, can be pulled into the second catheter  210 , thereby preventing any such clots from being released downstream of the treatment site. As a result, concurrent aspiration may permit the use of higher power or current levels delivered to the interventional element  300  without risking deleterious effects of new clot formation. Additionally, aspiration can capture any gas bubbles formed along the interventional element  300  or marker band  2034  ( FIG.  22   ) during application of electrical energy to the interventional element  300 , which can improve patient safety during the procedure. 
     In some embodiments, aspiration is applied while the interventional element  300  and the distal element  140  are retracted into the second catheter  210 . During retraction, the proximal face of the distal element  140  (and/or the engagement portion  2030 ) can engage with the clot material CM and urge it proximally towards the distal end of the second catheter  210 . Aspiration at this stage can help secure the clot material CM within the second catheter  210  and prevent any dislodged portion of the clot material CM from escaping the second catheter  210  and being released back into the vessel V. In various embodiments, the treatment site can be aspirated continuously before, during, or after delivering electrical signals to the interventional element  300  (and/or distal element  140 ) as well as before, during, or after retraction of the interventional element  300  into the second catheter  210 . 
     At least while the interventional element  300  is deployed and engaging the thrombus CM, electric current may be delivered to the interventional element  300  to positively charge the interventional element  300 , thereby enhancing clot adhesion to the interventional element  300 . In some cases, electrically enhanced clot adhesion can be improved in the absence of blood flow. As such, it may be especially beneficial to arrest blood flow (e.g., via the balloon  1001  of the first catheter  200  or a flow arrest element of the second catheter  210 ) while the interventional element  300  is charged, and while withdrawing the thrombus proximally. Instead of or in addition to such blood flow arrest, a flow of saline may be provided from the fluid source  27  toward the interventional element  300  via the second catheter  210  and/or first catheter  200 . 
     With reference to  FIGS.  18 C- 18 D , while the interventional element  300  and/or the distal element  140  are engaged with the clot material CM, the clot material CM can be removed. For example, the interventional element  300 , with the clot material CM gripped thereby, can be retracted proximally (for example, along with the second catheter  210  and, optionally, the first catheter  200 ). The second catheter  210 , distal element  140 , interventional element  300 , and associated clot material CM may then be withdrawn from the patient, optionally through one or more larger surrounding catheters. During this retraction, the interventional element  300  can grip the clot material CM electrically and/or electrostatically, e.g., via the application of current from the current generator. Accordingly, the interventional element  300  can maintain an enhanced or electrically and/or electrostatically enhanced grip on the clot material CM during retraction. In other embodiments, the current generator  20  may cease delivery of electrical signals to the interventional element  300  prior to retraction of the interventional element  300  with respect to the vessel V. In some embodiments, the interventional element  300  and clot material CM form a removable, integrated thrombus-device mass wherein the connection of the thrombus to the device is electrically enhanced, e.g. via the application of current as discussed herein. 
     In  FIGS.  18 C- 18 D , the clot material CM has been moved to at least partially enter the second catheter  210 . In some embodiments, the clot material CM can substantially block the lumen of the second catheter  210 , thereby creating a “corking” effect that may be noticeable to a clinician supplying negative pressure to the second catheter  210  as noted previously. In some embodiments, the current generator  20  can continue to supply electrical signals to the interventional element  300  and the distal element  140  during retraction, while in other embodiments the current generator  20  can cease supplying electrical signals during retraction of the catheter  210  and the clot material CM. 
     V. SELECT EMBODIMENTS OF WAVEFORMS FOR ELECTRICALLY ENHANCED RETRIEVAL 
       FIGS.  23 A- 23 E  show various electrical waveforms for use with the treatment systems of the present technology. Although the waveforms and other power delivery parameters disclosed herein can be used with the devices and methods described above with respect to  FIGS.  19 A- 22   , the waveforms and other parameters are also applicable to other device configurations and techniques. For example, the return electrode can be provided along the catheter wall, as a separate conductive member extending within the catheter lumen, as a needle electrode provided elsewhere in the body, etc. In each of these device configurations, the power delivery parameters and waveforms can be beneficially employed to promote clot adhesion without damaging surrounding tissue. Additionally, although the waveforms and other power delivery parameters disclosed herein may be used for treating a cerebral or intracranial embolism, other applications and other embodiments in addition to those described herein are within the scope of the technology. For example, the waveforms and power delivery parameters disclosed herein may be used to electrically enhance removal of emboli from body lumens other than blood vessels (e.g., the digestive tract, etc.) and/or may be used to electrically enhance removal of emboli from blood vessels outside of the brain (e.g., pulmonary blood vessels, blood vessels within the legs, etc.). 
     While applying a continuous uniform direct current (DC) electrical signal (as shown in  FIG.  23 E ) to positively charge the interventional element and/or aspiration catheter can improve attachment to the thrombus, this can risk damage to surrounding tissue (e.g., ablation), and sustained current at a relatively high level may also be thrombogenic (i.e., may generate new clots). For achieving effective clot-grabbing without ablating tissue or generating substantial new clots at the treatment site, periodic waveforms have been found to be particularly useful. Without wishing to be bound by theory, the clot-adhesion effect appears to be most closely related to the peak current of the delivered electrical signal. Periodic waveforms can advantageously provide the desired peak current without delivering excessive total energy or total electrical charge. Periodic, non-square waveforms in particular are well suited to deliver a desired peak current while reducing the amount of overall delivered energy or charge as compared to either uniform applied current or square waveforms. 
       FIGS.  23 A- 23 D  illustrate various periodic waveforms that can be used with the devices and methods described above with respect to  FIGS.  19 A- 22   , as well as with other devices and techniques.  FIG.  23 E  illustrates a continuous uniform DC electrical signal which can also be used in some embodiments. Referring to  FIGS.  23 A- 23 D , electrical power can be delivered according to these waveforms as pulsed direct current.  FIGS.  23 A and  23 B  illustrate periodic square and triangular waveforms, respectively. These two waveforms have the same amplitude, but the triangular waveform is able to deliver the same peak current as the square waveform, with only half of the total charge delivered, and less total energy delivered.  FIG.  23 C  illustrates another pulsed-DC or periodic waveform which is a composite of a square waveform and a triangular waveform. This superposition of a triangular waveform and a square waveform shown in  FIG.  23 C  delivers additional efficacy compared to the triangular waveform of  FIG.  23 B  while nonetheless delivering less overall energy than the square waveform of  FIG.  23 A . This is because the delivered energy is proportional to the square of current and the brief high peak in the composite waveform of  FIG.  23 C  ensures that current is supplied without dispensing excessive energy.  FIG.  23 D  illustrates yet another non-square waveform, in this case a trapezoidal waveform in which “ramp-up” and “ramp-down” portions at the beginning and end of each pulse provide periods of reduced current compared to square waveforms. In other embodiments, different non-square waveforms can be used, including a superposition of a square waveform with any non-square waveform, depending on the desired power delivery characteristics. 
     The waveform shape (e.g., pulse width, duty cycle, amplitude) and length of time can each be selected to achieve desired power delivery parameters, such as overall electrical charge, total energy, and peak current delivered to the interventional element and/or catheter. In some embodiments, the overall electrical charge delivered to the distal element, interventional element and/or catheter can be between about 30-1200 mC, or between about 120-600 mC. According to some embodiments, the total electrical charge delivered to the distal element, interventional element and/or catheter may be less than 600 mC, less than 500 mC, less than 400 mC, less than 300 mC, less than 200 mC, or less than 100 mC. 
     In some embodiments, the total energy delivered to the distal element, interventional element, and/or aspiration catheter can be between about 0.75-24,000 mJ, or between about 120-24,000 mJ, or between about 120-5000 mJ. According to some embodiments, the total energy delivered to the distal element, interventional element, and/or aspiration catheter may be less than 24,000 mJ, less than 20,000 mJ, less than 15,000 mJ, less than 10,000 mJ, less than 5,000 mJ, less than 4,000 mJ, less than 3,000 mJ, less than 2000 mJ, less than 1,000 mJ, less than 900 mJ, less than 800 mJ, less than 700 mJ, less than 600 mJ, less than 500 mJ, less than 400 mJ, less than 300 mJ, or less than 200 mJ, or less than 120 mJ, or less than 60 mJ, or less than 48 mJ, or less than 30 mJ, or less than 12 mJ, or less than 6 mJ, or less than 1.5 mJ. 
     In some embodiments, the peak current delivered can be between about 0.5-20 mA, or between about 0.5-5 mA. According to some embodiments, the peak current delivered may be greater than 0.5 mA, greater than 1 mA, greater than 1.5 mA, greater than 2 mA, greater than 2.5 mA, or greater than 3 mA. 
     The duration of power delivery is another important parameter that can be controlled to achieve the desired clot-adhesion effects without damaging tissue at the treatment site or generating new clots. In at least some embodiments, the total energy delivery time can be no more than 1 minute, no more than 2 minutes, no more than 3 minutes, no more than 4 minutes, or no more than 5 minutes. According to some embodiments, the total energy delivery time may be less about 30 seconds, less than about 1 minute, less than about 90 seconds, or less than about 2 minutes. As used herein, the “total energy delivery time” refers to the time period during which the waveform is supplied to the interventional element and/or catheter (including those periods of time between pulses of current). 
     The duty cycle of the applied electrical signal can also be selected to achieve the desired clot-adhesion characteristics without ablating tissue or promoting new clot formation. In some embodiments, the duty cycle can be between about 5% about 99% or between about 5% to about 20%. According to some embodiments, the duty cycle may be about 10%, about 20%, about 30%, about 40%, or about 50%. In yet other embodiments, a constant current may be used, in which the duty cycle is 100%. For 100% duty cycle embodiments, a lower time or current may be used to avoid delivering excess total energy to the treatment site. 
     Table 1 presents a range of values for power delivery parameters of different waveforms. For each of the conditions set forth in Table 1, a resistance of 1 kohm and a frequency of 1 kHz (for the Square, Triangle, and Composite conditions) was used. The Constant conditions represent a continuous and steady current applied for the duration, i.e. 100% duty cycle. The Peak Current 1 column represents the peak current for the corresponding waveform. For the Composite conditions, the Peak Current 2 column indicates the peak current of the second portion of the waveform. For example, referring back to  FIG.  23 C , Peak Current 1 would correspond to the current at the top of the triangular portion of the waveform, while Peak Current 2 would correspond to the current at the top of the square portion of the waveform. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Total 
                 Total 
               
               
                   
                 Peak 
                 Peak 
                 Duty 
                 Duty 
                 Peak 
                 Pulse 
                 Total 
                 Total 
                 Energy 
                 Energy 
               
               
                   
                 Current 1 
                 Current 2 
                 Cycle 1 
                 Cycle 2 
                 Voltage 
                 Width 
                 Time 
                 Charge 
                 (@ R = 1000 
                 (@ R = 50 
               
               
                 Condition 
                 (mA) 
                 (mA) 
                 (%) 
                 (%) 
                 (V) 
                 (ms) 
                 (s) 
                 (mC) 
                 ohm) (mJ) 
                 ohm) (mJ) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Constant 1 
                 2 
                 0 
                 100 
                 0 
                 2 
                 n/a 
                 120 
                 240 
                 480 
                 24 
               
               
                 Constant 2 
                 2 
                 0 
                 100 
                 0 
                 2 
                 n/a 
                 60 
                 120 
                 240 
                 12 
               
               
                 Constant 3 
                 10 
                 0 
                 100 
                 0 
                 10 
                 n/a 
                 60 
                 600 
                 6000 
                 300 
               
               
                 Constant 4 
                 20 
                 0 
                 100 
                 0 
                 20 
                 n/a 
                 60 
                 1200 
                 24000 
                 1200 
               
               
                 Constant 5 
                 10 
                 0 
                 100 
                 0 
                 10 
                 n/a 
                 120 
                 1200 
                 12000 
                 600 
               
               
                 Constant 6 
                 1 
                 0 
                 100 
                 0 
                 1 
                 n/a 
                 120 
                 120 
                 120 
                 6 
               
               
                 Constant 7 
                 0.5 
                 0 
                 100 
                 0 
                 1 
                 n/a 
                 120 
                 60 
                 30 
                 1.5 
               
               
                 Constant 8 
                 0.5 
                 0 
                 100 
                 0 
                 1 
                 n/a 
                 60 
                 30 
                 15 
                 0.75 
               
               
                 Square 1 
                 10 
                 0 
                 10 
                 0 
                 10 
                 0.1 
                 120 
                 120 
                 1200 
                 60 
               
               
                 Square 2 
                 4 
                 0 
                 50 
                 0 
                 4 
                 0.5 
                 120 
                 240 
                 960 
                 48 
               
               
                 Square 3 
                 20 
                 0 
                 10 
                 0 
                 20 
                 0.1 
                 120 
                 240 
                 4800 
                 240 
               
               
                 Square 4 
                 20 
                 0 
                 10 
                 0 
                 20 
                 0.1 
                 60 
                 120 
                 2400 
                 120 
               
               
                 Square 5 
                 10 
                 0 
                 10 
                 0 
                 10 
                 0.1 
                 60 
                 60 
                 600 
                 30 
               
               
                 Triangle 1 
                 10 
                 0 
                 10 
                 0 
                 10 
                 0.1 
                 120 
                 60 
                 1200 
                 60 
               
               
                 Triangle 2 
                 20 
                 0 
                 10 
                 0 
                 20 
                 0.1 
                 120 
                 120 
                 4800 
                 240 
               
               
                 Composite 1 
                 20 
                 1 
                 10 
                 20 
                 20 
                 0.3 
                 120 
                 144 
                 4824 
                 264 
               
               
                 Composite 2 
                 10 
                 2 
                 10 
                 20 
                 10 
                 0.3 
                 120 
                 108 
                 1296 
                 156 
               
               
                   
               
            
           
         
       
     
     As seen in Table 1, the periodic waveforms (Square, Triangle, and Composite conditions) achieve higher peak currents with lower overall charge delivered than the corresponding Constant conditions. For example, in condition Constant 4, a peak current of 20 mA corresponds to a total energy delivered of 24,000 mJ, while condition Square 3 delivers a peak current of 20 mA with a total energy of only 4,800 mJ. Conditions Triangle 2 and Composite 1 similarly deliver lower total energy while maintaining a peak current of 20 mA. Since clot-adhesion appears to be driven by peak current, these periodic waveforms can therefore offer improved clot adhesion while reducing the risk of damaging tissue at the treatment site or promoting new clot formation. Table 1 also indicates that the Triangle and Composite conditions achieve higher peak currents with lower overall charge delivered than the corresponding Square conditions. For example, condition Square 3 has a peak current of 20 mA and a total charge delivered of 240 mC, while condition Triangle 2 has a peak current of 20 mA but a total charge delivered of only 120 mC, and condition Composite 1 has a peak current of 20 mA and a total charge delivered of only 144 mC. As such, these non-square waveforms provide additional benefits by delivering desirable peak current while reducing the overall charge delivered to the treatment site. 
     Although Table 1 represents a series of waveforms with a single frequency (1 kHz), in some embodiments the frequency of the pulsed-DC waveforms can be controlled to achieve the desired effects. For example, in some embodiments the frequency of the waveform can be between 1 Hz and 1 MHz, between 1 Hz and 1 kHz, or between 500 Hz to 1 kHz. 
     VI. SELECT EMBODIMENTS OF DISTAL ELEMENTS OF THE PRESENT TECHNOLOGY 
       FIGS.  24 A-D  illustrate several views of a distal element  140  in accordance with the present technology. As shown in  FIGS.  24 A-D , the distal element  140  can include an elongated body  142  formed from a plurality of woven filaments  144 . The distal element  140  can move between an expanded, relaxed state, as illustrated in  FIG.  24 A , and a delivery state where the distal element is collapsed into a low-profile configuration (shown) and constrained within a delivery catheter. In an expanded, unconstrained state, the plurality of filaments  144  define and surround an interior cavity. The distal element  140  can have an elongated shape such that a length of the distal element  140  is greater than a maximum expanded diameter of the distal element  140 . In some embodiments, the length of the distal element  140  is at least 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 times greater than the diameter of the distal element. The body  142  can be heat set in an expanded state so that the body  142  resiliently assumes the expanded state when no countervailing force is present. 
     As shown in  FIG.  24 A , the body  142  can have a first portion  145  and a second portion  147  having different shapes and filament configurations that impart unique structural and functional characteristics to the first and second portions  145 ,  147 . For example, the first portion  145  can be configured to provide column strength, improve opening performance, and encourage the second portion  147  to remain in an expanded state once expanded. The first portion  145  can extend between the connection assembly  130  and the second portion  147 , and can have a cross-sectional dimension that increases distally. The second portion  147  can extend between the first portion  145  and the distal end portion  140   b  of the distal element  140 . In some embodiments, the pore size and shape along the first portion  145  is different than a pore size and shape along the second portion  147 . For example, the pore size along the first portion  145  can be greater than the pore size along the second portion  147 . In other embodiments, the pore size along the first portion  145  is less than the pore size along the second portion  147 . The filaments  144  along the first portion  145  can extend generally substantially linearly in a distal direction, while the filaments  144  along the second portion  147  can wrap around all or a portion of the circumference of the body  142 . Pairs  149  of filaments (a few of which are labeled in  FIG.  24 B ) can extend distally together along the first portion  145  without crossing over another pair  149 . Along the second portion  147 , the pairs  149  of filaments can cross over and/or under one another, as described in greater detail below. In some embodiments, less than all of the filaments  144  (including none of the filaments  144 ) are arranged in pairs. In such embodiments, the filaments  144  along the first portion  145  (whether individual filaments or pairs) can extend distally together without crossing over another individual filament and/or pair. Along the second portion  147 , pairs and/or individual filaments can cross over and/or under another individual filament and/or pair, as described in greater detail below. 
     The distal element  140  has a proximal portion  140   a  configured to be coupled to a delivery system (such as any of the delivery systems disclosed herein) and a closed distal portion  140   b . The filaments  144  can be a plurality of wires that extend between the proximal portion  140   a  and the distal portion  140   b  of the distal element  140 . In some embodiments, each of the filaments  144  have a first end portion positioned at the proximal portion  140   a  of the distal element  140  and a second end portion also positioned at the proximal portion  140   a  of the distal element  140 . Each of the filaments  144  may extend from its corresponding first end portion distally along the body  142  towards the distal portion  140   b  and then return by extending proximally along the body  142  to its corresponding second end portion at the proximal portion  140   a.    
     The first and second end portions of the filaments  144  can come together at the proximal portion  140   a  of the distal element  140  and be held together by a connection assembly  130  (discussed above) and/or a proximal coil  150  (discussed above). The proximal termini of the filaments can be disposed within the connection assembly  130  or, as shown in  FIG.  24 B  where the connection assembly  130  and proximal coil  150  have been removed, the first and second end portions of the filaments  144  can extend proximally beyond the connection assembly  130  to form an extension portion  143 . The extension portion  143  can advantageously increase the column strength of the distal element  140  and improve pushability of the device. Along the extension portion  143 , the filaments  144  can extend substantially parallel to a longitudinal axis of the proximal coil  150 , elongated member  120  (not shown), and/or treatment device. In some embodiments, the filaments  144  are bunched together to an extent that the filaments  144  contact one another along the extension portion  143  (i.e., no appreciable pathway or lumen exists along the extension portion  143 ). In any case, the filaments  144  are circumferentially distributed around the longitudinal axis so as to define a lumen through the extension portion  143 . The extension portion  143  can have a length of at least 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. 
     As shown in  FIGS.  24 A and  24 B , the connection assembly  130  and/or proximal coil  150  can extend over and radially surround the extension portion  143 . In some embodiments, a distal end of the proximal coil  150  may abut or be joined with a proximal portion of the connection assembly  130  and/or the proximal termini of the filaments  144 . In other embodiments, a distal end of the proximal coil  150  is spaced apart from a proximal end of the connection assembly  130  and/or the proximal termini of the filaments. In various embodiments, the elongated member  120  and/or distal coil  160  can be received within the extension portion  143 . 
     Distal to the extension portion  143 , the filaments  144  can expand radially outwardly to form the body  142  of the distal element  140 . In some embodiments, the filaments  144  are arranged in a lattice-like structure. For example, the filaments  144  can be woven so that the filaments  144  cross over and/or under themselves and/or other filaments  144  forming the body  142 . In at least one embodiment, during weaving of the distal element  140 , the filaments can be braided using a 1-over-2-under-2 pattern. In other embodiments, however, other methods of weaving can be followed, without departing from the scope of the disclosure. Such other weaving methods can include a 1-over-1-under-1 pattern and 2-over-2-under-2 pattern. In some embodiments, each individual filament  144  is woven to form a spiral or helical shape having a particular pitch. The pitch of the individual filaments  144  can vary from filament  144  to filament  144 . In various embodiments, the pitch of the filaments  144  are substantially the same. After the filaments  144  have been woven, the filaments  144  can be heat set to a desired shape, such as, for example, by placing the distal element filaments  144  in contact with a molding surface of a molding element which defines a desired shape of all or a portion of the body  142 . 
     The distal element  140  may be formed of by any desired number of filaments  144 . For example, the distal element  140  can be formed from 4, 6, 8, 10, 12, 24, 36, 48, 60, 72, or 84 filaments  144 . In some embodiments, the distal element  140  comprises a single filament. The distal element  140  may be formed of a range of filament sizes, such as filaments having a diameter of from about 0.0004 inches to about 0.0020 inches, or of from about 0.0009 inches to about 0.0012 inches. In some embodiments, each of the filaments  144  has a diameter of about 0.0004 inches, about 0.0005 inches, about 0.0006 inches, about 0.0007 inches, about 0.0008 inches, about 0.0009 inches, about 0.001 inches, about 0.0011 inches, about 0.0012 inches, about 0.0013 inches, about 0.0014 inches, about 0.0015 inches, about 0.0016 inches, about 0.0017 inches, about 0.0018 inches, about 0.0019 inches, or about 0.0020 inches. In some embodiments, all of the filaments  144  of the body  142  can have the same cross-sectional dimension. For example, in some embodiments, all of the filaments  144  have a diameter of about 0.001 inches. In some embodiments, some of the filaments  144  may have different cross-sectional dimensions. For example, some of the filaments  144  may have a slightly thicker diameter to impart additional strength to the woven structure. 
     The filaments  144  can be formed of known flexible materials including shape memory materials (e.g., nitinol), cobalt chromium, platinum, stainless steel, other metals, other metal alloys, or a combination thereof. In some embodiments, the filaments  144  can be wire having a round, ovoid, square, rectangular, or other shape in cross-section. Further, the filaments  144  can be configured such that the distal element  140  is self-expanding. For example, in some embodiments, at least a portion of the body  142  will tend to resiliently assume an expanded configuration in the absence of a countervailing force. In some embodiments, the body  142  can be fabricated from a first group of filaments formed from platinum or platinum alloy (e.g., platinum/8% tungsten) and with a second group of filaments formed from cobalt-nickel or cobalt-chromium alloy (e.g., 35N LT™ available from Fort Wayne Metals of Fort Wayne, Ind., USA). In various embodiments, the filaments  144  comprise metal and/or polymer wires. One, some, or all of the filaments  144  forming the body  142  may be formed of a drawn-filled tube wire comprising a core material surrounded by an outer material. The core material may be a radiopaque material, such as platinum, and the outer material may be a shape memory alloy, such as nitinol, chromium cobalt (“CrCo”) alloys, stainless steel alloys, etc. 
     The distal element  140  can include one or more pores  146 . The pores  146  can be defined by the space in between adjacent filaments  144 . As shown in  FIGS.  24 A- 24 D , the wave pattern can be configured such that the pores  146  are formed in various shapes and sizes, with some pores  146  being larger, smaller, and or differently shaped than other pores  146 . In some embodiments, the pores  146  can have a size sufficient to allow fluid such as blood, saline or contrast agent to pass therethrough when the distal element  140  is in an expanded state. In some embodiments, the distal element  140  can exhibit a porosity configured to reduce hemodynamic flow through the distal element  140  to a desired extent. For example, the sizes of the pores  146  can be controlled by adjusting the numbers of filaments  144  forming the body  142  and/or adjusting the pick and pitch of the weave. 
     As previously mentioned, at one end of the distal element  140  (for example, the proximal end  140   a , the distal end  140   b ), the distal element  140  can couple to the elongated member  120 , elongated shaft  170 , and/or distal coil  160 . Additionally, or alternatively, the elongated member  120 , elongated shaft  170 , and/or distal coil  160  can extend through the distal element  140  by extending through the extension portion  143  and through the body  142 . 
     In some embodiments, the distal element  140  is configured to receive at least one elongated member therethrough. The elongated member can terminate at and/or near the distal end portion  140   b  of the distal element  140 , or may extend distally beyond the distal terminus of the distal element  140  (for example, as shown in  FIG.  2 A ). The distal element  140  can be axially and/or rotationally fixed to the elongated member, or may be configured to move axially and/or rotate relative to the elongated member. The pore size of one or more of the pores  146  of the distal element  140  at the closed distal end portion  140   b  can be sized to receive the elongated member  120 , elongated shaft  170 , and/or distal coil  160  therethrough. Accordingly, the distal element  140  can be unattached to (and slidable over) the elongated member  120 , elongated shaft  170 , and/or distal coil  160  at the end opposite the extension portion  143 . Furthermore, under radially compressive forces, this distal pore enables the distal portion  140   b  of the distal element  140  to slide and/or move along the elongated member, thereby allowing the distal element  140  to radially compress and lengthen with a minimum of resistance. This facilitates a distal element  140  which is self-expanding but also sufficiently soft and compressible to avoid injuring delicate vessels (such as the neurovasculature). The distal element  140  can therefore be sufficiently self-expanding to effectively move or capture thrombus, without posing a risk of injuring the surrounding vessel. In some embodiments, expansion of the distal element  140  causes the pore  146  closest to the elongated member (e.g., the pore  146  receiving the elongated member therethrough) to move along the elongated member  120  as the distal element  140  expands. In some embodiments the distal element  140  comprises the distal-most element of the treatment device and does not have any delivery component (like an elongated member) extending therethrough. According to some embodiments, the distal end portion  140   b  of the distal element  140  is slidably and/or rotatably coupled to the elongated member. In several embodiments, the distal end portion  140   b  of the distal element  140  is fixedly coupled to the elongated member. 
     The distal elements  140  of the present technology may comprise a range of sizes. For example, the distal elements  140  of the present technology may have a maximum cross-sectional dimension of at least 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, or 8.00 mm. In some embodiments, the distal element  140  can be coated or surface-treated with one or more compounds, such as, for example, antithrombotic agents. 
       FIGS.  25 A-B  illustrate several views of a distal element  140  having a cover  148  in accordance with the present technology. The filaments  144  can have an inner surface (e.g., the surface of the filaments  144  facing radially inwardly, towards the interior cavity), an outer surface (e.g., the surface of the filaments  144  at an exterior of the distal element  140 ), and an intermediate surface comprising the surface between the inner and outer surfaces. The intermediate surfaces, for example, can generally face another intermediate surface. As illustrated in  FIGS.  25 A-B , in some embodiments, the cover  148  is disposed at the inner surfaces of the filaments  144  along all or a portion of the length of the body  142 . The cover  148  can bulge radially outwardly within the pores (i.e., towards an exterior of the distal element  140 ) such that the cover  148  is disposed at the intermediate surfaces of the filaments  144  as well as the inner surfaces, while leaving all or a portion of the outer surfaces exposed. Such a configuration can be especially beneficial for the electrically-enhanced embodiments of the distal element  140 , as the outer surfaces would remain electrically conductive. 
     According to several embodiments, the cover  148  is disposed at the outer surfaces of the filaments  144  along all or a portion of the length of the body  142 . In several of such embodiments, the cover  148  can bulge radially inwardly within the pores (i.e., towards the interior cavity) such that the cover  148  is disposed at the intermediate surfaces of the filaments  144  as well as the outer surfaces. In some embodiments, the cover  148  is disposed along only the inner surfaces, only the outer surfaces, or only the intermediate surfaces. In several embodiments, the cover  148  is disposed along all of the non-crossing surfaces of the filaments  144 . 
     In some embodiments, the cover  148  extends across the entire length of the distal element  140 . In various embodiments, the cover  148  extends across a portion of the distal element. For example, in some embodiments the cover  148  does not extend over the rounded distal end portion  140   b  of the distal element  140 . The cover  148  can comprise a polymer. 
     The cover  148  can advantageously reinforce the filaments  144  in an expanded state by providing a radially outward force that supplements the superelastic properties of the shape set filaments  144 . Accordingly, the cover  148  can ensure the distal element  140  resiliently assumes an expanded state when no countervailing force is present. Non-covered braids and/or weaves in the prior art often have difficulty expanding to or maintaining their heat set shape when pushed from a delivery catheter. This is especially true in large blood vessels (e.g., having a diameter of 4 mm or greater). In some examples, the cover  148  can be used to limit or prevent fluid flow through all or a portion of the distal element  140 . For example, when the cover  148  is disposed with the distal element  140 , the cover  148  can block fluid from flowing through the pores  146  and thereby restrict or prevent fluid from flowing through the distal element  140 . 
     IV. CONCLUSION 
     This disclosure is not intended to be exhaustive or to limit the present technology to the precise forms disclosed herein. Although specific embodiments are disclosed herein for illustrative purposes, various equivalent modifications are possible without deviating from the present technology, as those of ordinary skill in the relevant art will recognize. In some cases, well-known structures and functions have not been shown and/or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Although steps of methods may be presented herein in a particular order, in alternative embodiments the steps may have another suitable order. Similarly, certain aspects of the present technology disclosed in the context of particular embodiments can be combined or eliminated in other embodiments. Furthermore, while advantages associated with certain embodiments may have been disclosed in the context of those embodiments, other embodiments can also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages or other advantages disclosed herein to fall within the scope of the present technology. Accordingly, this disclosure and associated technology can encompass other embodiments not expressly shown and/or described herein. 
     Throughout this disclosure, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise. Similarly, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the terms “comprising” and the like are used throughout this disclosure to mean including at least the recited feature(s) such that any greater number of the same feature(s) and/or one or more additional types of features are not precluded. Directional terms, such as “upper,” “lower,” “front,” “back,” “vertical,” and “horizontal,” may be used herein to express and clarify the relationship between various elements. It should be understood that such terms do not denote absolute orientation. Reference herein to “one embodiment,” “an embodiment,” or similar formulations means that a particular feature, structure, operation, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present technology. Thus, the appearances of such phrases or formulations herein are not necessarily all referring to the same embodiment. Furthermore, various particular features, structures, operations, or characteristics may be combined in any suitable manner in one or more embodiments.