Patent Publication Number: US-2011054504-A1

Title: Recanalization device with expandable cage

Description:
RELATED APPLICATION DATA 
     The present application claims the benefit under 35 U.S.C. §119 to U.S. provisional patent application Ser. No. 61/238,344, filed Aug. 31, 2009. The foregoing application is hereby incorporated by reference into the present application in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure is directed to a medical device for treatment of a body vessel. More particularly, the disclosure is directed to a vascular recanalization device having an expandable cage for re-establishing blood flow through a vessel lumen. 
     BACKGROUND 
     Acute ischemic stroke is a fast onset disease with the potential for devastating long-term neurological effects, or even death. Treatment of patients which might yield a significant beneficial effect should be done rapidly in order to re-establish blood flow to the affected region of the brain before unrecoverable damage has occurred. One such method is the placement of a stent-like device across an embolic blockage in order to rapidly re-establish blood flow. However, permanent placement of a stent may be undesirable in at least some instances. 
     There is an ongoing need, therefore, to provide alternative configurations of vascular recanalization devices for temporary placement in a vessel lumen to rapidly re-establish blood flow through the vessel lumen. 
     SUMMARY 
     The disclosure is directed to several alternative designs, materials and methods of manufacturing and using medical device structures and assemblies. 
     Accordingly, one illustrative embodiment is a medical device including an elongate wire and an expandable cage coupled to the elongate wire such that the expandable cage is longitudinally slidable along a length of the elongate wire between a first position and a second position. The medical device further includes a central stop secured to the elongate wire intermediate the proximal end and the distal end of the expandable cage. The proximal end of the expandable cage is prevented from sliding distally beyond the central stop, and the distal end of the expandable cage is prevented from sliding proximally beyond the central stop. 
     Another illustrative embodiment is a vascular recanalization device for re-establishing blood flow through a vessel lumen. The vascular recanalization device includes an elongate wire and an expandable cage slidably coupled to the elongate wire. The expandable cage includes a proximal collar slidably disposed on the elongate wire and a distal collar slidably disposed on the elongate wire. A central stop is secured to the elongate wire intermediate the proximal collar and the distal collar. A proximal stop is located proximal of the proximal collar of the expandable cage, and a distal stop is located distal of the distal collar of the expandable cage. The proximal collar is slidable along the elongate wire between the proximal stop and the central stop, and the distal collar is slidable along the elongate wire between the central stop and the distal stop. 
     Yet another illustrative embodiment is a method of treating a vessel lumen. The method includes providing a medical device including an elongate wire, an expandable cage slidably coupled to the elongate wire, the expandable cage including a proximal collar slidably disposed on the elongate wire and a distal collar slidably disposed on the elongate wire, and a central stop secured to the elongate wire intermediate the proximal collar and the distal collar. The elongate wire is pushed distally, whereby the central stop abuts the distal collar of the expandable cage and is spaced away from the proximal collar, and the elongate wire is pulled proximally, whereby the central stop abuts the proximal collar of the expandable cage and is spaced away from the distal collar. 
     The above summary of some example embodiments is not intended to describe each disclosed embodiment or every implementation of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
         FIG. 1  is a plan view of an exemplary vascular recanalization device; 
         FIG. 1A  is a cross-sectional view taken along line  1 A- 1 A of  FIG. 1 ; 
         FIGS. 2A-2C  illustrate an exemplary mode of operating the vascular recanalization device of  FIG. 1 ; 
         FIG. 3  is a plan view of another exemplary vascular recanalization device; 
         FIGS. 4A-4C  illustrate an exemplary mode of operating the vascular recanalization device of  FIG. 3 ; 
         FIG. 5  is a plan view of yet another exemplary vascular recanalization device; 
         FIGS. 6A-6F  illustrate an exemplary mode of operating the vascular recanalization device of  FIG. 5 ; and 
         FIGS. 7-10  illustrate various exemplary embodiments of an expandable mesh which may be used in the expandable cage of the vascular recanalization devices shown in  FIGS. 1 ,  3  and  5 . 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
     DETAILED DESCRIPTION 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may be indicative as including numbers that are rounded to the nearest significant figure. 
     The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     Although some suitable dimensions, ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed. 
     As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     As used herein the terms “pull”, “pulling”, and “pulled” are intended to refer to applying a force to a leading end portion of an object in order to move the object in a direction generally toward the leading end portion of the object. 
     As used herein the terms “push”, “pushing”, and “pushed” are intended to refer to applying a force to a trailing end portion of an object in order to move the object in a direction generally away from the trailing end portion of the object. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary. 
     Referring to  FIG. 1 , there is shown a vascular recanalization device  10  which may be temporarily placed in a blocked vessel to re-establish blood flow through the vessel. The vascular recanalization device  10  may include an elongate wire  12  having a proximal end  14  and a distal end  16 . In operation, the distal end  16  of the elongate wire  12  may be advanced through the vasculature of a patient while the proximal end  14  remains exterior of the patient to be manipulated by the medical personnel during a medical procedure. 
     The distal end  16  of the elongate wire  12  may include a distal tip, such as a distal coil tip  18  attached to the elongate wire  12 . For example, the distal coil tip  18  may include a wire filament helically wound into a coil. The coil may be disposed over a distal portion of the elongate wire  12  and secured to the elongate wire  12 , such as by welding, soldering, brazing, or adhesive bonding in some instances. In other embodiments, the distal tip of the elongate wire  12  may have a different configuration, if desired. 
     The elongate wire  12  may include a proximal region  50  (e.g., a proximal constant diameter region) having a first diameter, a distal region  52  (e.g., a distal constant diameter region) having a second diameter less than the first diameter, and a transition region  54  which varies in diameter from the first diameter of the proximal region  50  to the second diameter of the distal region  52 . For instance, the transition region  54  may be tapered from the first diameter to the second diameter. The transition region  54  may include one or more tapers and/or step-wise transitions. As shown in  FIG. 1 , the transition region  54  may include a constant diameter portion  56  distal of the proximal region  50  and a tapered portion  58  extending between the constant diameter portion  56  and the distal region  52 . The constant diameter portion  56  may have a third diameter less than the first diameter of the proximal region  50 . The tapered portion  58  may have a variable diameter which varies from the third diameter of the constant diameter portion  56  of the transition region  54  to the second diameter of the distal region  52 . However, in other embodiments, the transition region  54  may include a continuous taper from the first diameter of the proximal region  50  to the second diameter at the distal region  52 , or two or more tapered sections separated by one or more constant diameter sections, for example. 
     The vascular recanalization device  10  may include a flexible tubular member  20 , such as a coiled member or a slotted hypotube, disposed over the elongate wire  12  throughout at least a portion of the transition region  54 . The flexible tubular member  20  may help provide a gradual transition in flexibility from the proximal region  50  to the distal region  52  of the elongate wire  12 , and thus may help prevent kinking of the elongate wire  12 . As shown in  FIG. 1 , a proximal portion of the flexible tubular member  20  may be disposed over and/or secured to the constant diameter portion  56  of the transition region  54  such that the proximal end of the flexible tubular member  20  is adjacent the distal end of the proximal region  50  of the elongate wire  12 . The flexible tubular member  20  may also include a distal portion which extends over the tapered portion  58  of the transition region  54 . It is noted that in embodiments in which the flexible tubular member  20  has a constant diameter, the distal portion of the flexible tubular member  20  may be spaced away from the tapered portion  58 , providing an annular gap between the tapered portion  58  of the elongate wire  12  and the flexible tubular member  20 . In some embodiments, the outer diameter of the flexible tubular member  20  may be substantially equal to the first diameter of the proximal region  50  of the elongate wire  12  to effect a smooth transition between the proximal region  50  and the flexible tubular member  20 . In some embodiments, the distal end of the flexible tubular member  20  may be secured to the elongate wire  12 . 
     The vascular recanalization device  10  may also include an expandable cage  22  coupled to the elongate wire  12 . For instance, the expandable cage  22  may be slidably coupled to the distal region  52  of the elongate wire  12  to allow longitudinal translation of the elongate wire  12  relative to the expandable cage  22  while the expandable cage  22  remains stationary. In some embodiments the expandable cage  22  may be slidably coupled to the elongate wire  12  such that the proximal end  24  of the expandable cage  22  is slidably coupled to the elongate wire  12  and/or the distal end  26  of the expandable cage  22  is slidably coupled to the elongate wire  12 . In some embodiments, no portion of the expandable cage  22  is fixedly secured to the elongate wire  12  or any other component of the vascular recanalization device  10 . 
     In some embodiments, as shown in  FIG. 1 , the expandable cage  22  may include a proximal collar  28  proximate the proximal end  24  of the expandable cage  22 , a distal collar  30  proximate the distal end  26  of the expandable cage  22 , and an expandable mesh  32  extending between the proximal collar  28  and the distal collar  30  and secured to both the proximal collar  28  and the distal collar  30 . The expandable mesh  32  may be formed of any desired structure, including but not limited to those illustrative structures shown in  FIGS. 7-10 , herein. For instance the expandable mesh  32  may include a plurality of interconnected filaments  48  forming an annular framework having interstitial openings between adjacent filaments  48 . In some instances the filaments  48  may be individual helically wound, braided or woven strands, or the filaments  48  may be portions of a workpiece remaining subsequent removal of material from the workpiece to form the interstitial openings. For example, the filaments  48  may be portions of a flat sheet or a tubular member remaining after removal of material from the flat sheet or tubular member. 
     The proximal collar  28  and/or the distal collar  30  may be slidably and rotatably disposed on the distal region  52  of the elongate wire  12 .  FIG. 1A , which is a cross-sectional view taken along line  1 A- 1 A of  FIG. 1 , illustrates one possible configuration of the proximal collar  28  of the expandable cage  22 . It is noted that the distal collar  30  may have a similar structure to that of the proximal collar  28 , thus discussion of the structure of the proximal collar  28  may apply equally to that of the distal collar  30 . 
     The collar  28 ,  30  may include an inner tubular portion  44  and an outer tubular portion  46  extending circumferentially around the elongate wire  12  and slidable thereon. For example, the inner tubular portion  44  may have an inner diameter slightly larger than the outer diameter of the distal region  52  of the elongate wire  12  to allow sliding and rotational movement of the collar  28 ,  30  over the elongate wire  12 . One or more, or a plurality of filaments  48  of the expandable mesh  32  may extend into and/or through the collar  28 ,  30  between the inner tubular portion  44  and the outer tubular portion  46  such that the filaments  48  may be secured to the collar  28 ,  30 . In other embodiments, the expandable mesh  32  may be secured to the proximal and distal collars  28 ,  30  in another manner, if desired. 
     The vascular recanalization device  10  may further include a central stop  34  secured to the elongate wire  12  at a location intermediate the proximal end  24  and the distal end  26  of the expandable cage  22 . For example, the central stop  34  may be secured to the elongate wire  12  intermediate the proximal collar  28  and the distal collar  30  of the expandable cage  22 . The expandable mesh  32  may circumferentially surround and be spaced away from the central stop  34 . In some embodiments, the central stop  34  may be a helical coil member or other tubular member disposed around the elongate wire  12 , or the central stop  34  may be one or more projections formed around or secured to the elongate wire  12 . 
     The central stop  34  may be provided to prevent the expandable cage  22  from sliding distally on the elongate wire  12  distally of the central stop  34  and may be provided to prevent the expandable cage  22  from sliding proximally on the elongate wire  12  proximally of the central stop  34 . For instance, the central stop  34  may prevent the proximal end  24  of the expandable cage  22  from sliding distal of the central stop  34  and the central stop  34  may prevent the distal end  26  of the expandable cage  22  from sliding proximal of the central stop  34 . Thus, in the illustrative example of the vascular recanalization device  10  shown in  FIG. 1 , the central stop  34  may prevent the proximal collar  28  from sliding distal of the central stop  34 , and the central stop  34  may prevent the distal collar  30  from sliding proximal of the central stop  34 . 
     The vascular recanalization device  10  may also include a proximal stop  36  located proximally of the central stop  34  and a distal stop  38  located distally of the central stop  34 . In some embodiments, the proximal stop  36  may be the distal end of the flexible tubular member  20 , or the proximal stop  36  may be another component of the vascular recanalization device  10 . In some embodiments, the distal stop  38  may be the proximal end of the distal coil tip  18 , or the distal stop  38  may be another component of the vascular recanalization device  10 . 
     The proximal collar  28 , and thus the proximal end  24  of the expandable cage  22 , may be longitudinally slidable along the elongate wire  12  between the proximal stop  36  and the central stop  34 , and the distal collar  30 , and thus the distal end  26  of the expandable cage  22 , may be longitudinally slidable along the elongate wire  12  between the central stop  34  and the distal stop  38 . The longitudinal distance of travel of the proximal collar  28  between the proximal stop  36  and the central stop  34  may be two, three, four, five, eight or ten times or more of the length of the proximal collar  28 , in some instances. In some embodiments the proximal collar  28  may have 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, or 10 mm or more of travel between the proximal stop  36  and the central stop  34 . The longitudinal distance of travel of the distal collar  30  between the distal stop  38  and the central stop  34  may be two, three, four, five, eight or ten times or more of the length of the distal collar  30 , in some instances. In some embodiments the distal collar  30  may have 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, or 10 mm or more of travel between the distal stop  38  and the central stop  34 . 
       FIGS. 2A-2C  illustrate an exemplary mode of operating the vascular recanalization device  10  of  FIG. 1  during a medical procedure to re-establish blood flow through a vessel lumen. As shown in  FIG. 2A , the vascular recanalization device  10  may be advanced distally through the lumen  62  of an elongate tubular member  60  of a medical device, such as a medical catheter (e.g., a microcatheter), during a medical procedure. For instance, the medical personnel may push the elongate wire  12  distally to advance the vascular recanalization device  10  through the elongate tubular member  60  located in a lumen of a vessel V. 
     While positioned in the lumen  62  of the elongate tubular member  60  the expandable cage  22  may assume a collapsed configuration in which the expandable cage  22  has a reduced diameter relative to an expanded configuration which the expandable cage  22  may be expanded to upon exiting the elongate tubular member  60 . In some embodiments, the elongate tubular member  60  may constrain the expandable cage  22  to the collapsed configuration while positioned in the lumen  62  of the elongate tubular member  60 . In the collapsed configuration, the expandable cage  22  may have a collapsed cage length measured from the proximal collar  28  to the distal collar  30 . Furthermore, in the expanded configuration, shown in  FIG. 2B , the expandable cage  22  may have an expanded cage length measured from the proximal collar  28  to the distal collar  30 . The collapsed cage length may be greater than the expanded cage length. 
     As shown in  FIG. 2A , the distance between the proximal stop  36  and the distal end of the central stop  34  may be equal to or greater than the collapsed cage length in order to allow the expandable cage  22  to be fully collapsed and elongated to the collapsed configuration while being advanced distally through the elongate tubular member  60 . Furthermore, as shown in  FIG. 2C , the distance between the proximal end of the central stop  34  and the distal stop  38  may be equal to or greater than the collapsed cage length in order to allow the expandable cage  22  to be fully collapsed and elongated to the collapsed configuration while being withdrawn proximally through the elongate tubular member  60 . 
     As the elongate wire  12  is being pushed distally by the medical personnel, the central stop  34  moves distally relative to the expandable cage  22  until the distal end of the central stop  34  abuts the distal collar  30  of the expandable cage  22 . Thus, the central stop  34  exerts a force on the distal collar  30 , in which the exerted force has a directional component in a distal direction parallel to the longitudinal axis of the elongate wire  12 , effectively resulting in the expandable cage  22  being pulled distally through the elongate tubular member  60  via the distal collar  30  by pushing the elongate wire  12  distally. 
     Effectively pulling the expandable cage  22  through the elongate tubular member  60  has the effect of reducing the force necessary to move the expandable cage  22  through the elongate tubular member  60  relative to situations in which the expandable cage  22  would be pushed through the elongate tubular member  60 . Pulling the expandable cage  22  distally from the distal collar  30  will tend to cause the expandable cage  22  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  22  and the inner surface of the elongate tubular member  60 , whereas pushing the expandable cage  22  distally from the proximal collar  28  would tend to cause the expandable cage  22  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  22  and the inner surface of the elongate tubular member  60 . 
     The vascular recanalization device  10  may be advanced distally until the expandable cage  22  is deployed from the distal end of the elongate tubular member  60  to deliver the expandable cage  22  to a target location within the vessel V. As shown in  FIG. 2B , once deployed from the elongate tubular member  60 , the expandable cage  22  may be expanded to the expanded configuration in which the expandable cage  22  is expanded in diameter and shortened in length. In some embodiments, the expandable cage  22  may be self-expanding in which the expandable cage  22  automatically expands upon being deployed from the elongate tubular member  60 . In other embodiments, the expandable cage  22  may be manually, selectively and/or controllably expanded, such as by the manipulation of a component of the vascular recanalization device  10 , application of a stimulus, and/or activation/deactivation of an energy source, for example. In the expanded configuration, the expandable cage  22  may exert a radially outward force on the vessel V to open a blockage and re-establish blood flow through the vessel V. The openness of the interstitial openings between filaments  48  of the expandable mesh  32  allows blood to flow through the expandable cage  22 . Furthermore, in some embodiments, the expandable mesh  32  may be configured to capture embolic material while deployed in the vessel V. 
     When the expandable cage  22  is in its expanded configuration and deployed in the vessel V, the elongate wire  12  may be longitudinally translated through the expandable cage  22  and/or rotated while the expandable cage  22  stays stationary and engaged against the vessel V, allowing the expandable cage  22  to float on the distal region  52  of the elongate wire  12 . Thus, longitudinal movement of the elongate wire  12  up to a threshold amount, whether inadvertent or intentional, will not cause the expandable cage  22  to move. 
     For instance, in the expanded configuration, the elongate wire  12  is free to move longitudinally between a first position in which the central stop  34  abuts the distal collar  30  and is spaced away from the proximal collar  28  and a second position in which the central stop  34  abuts the proximal collar  28  and is spaced away from the distal collar  30 . Thus, the elongate wire  12  is free to move longitudinally a distance equal to the distance between the proximal collar  28  and the distal collar  30  minus the length of the central stop  34 . This distance may be considered the float length of the expandable cage  22  on the elongate wire  12 . In some embodiments, the float length may be 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, 10 mm or more, 15 mm or more, 20 mm or more, or 30 mm or more, for example. 
     The length of the central stop  34  may be any desired length. In some embodiments, the length of the central stop  34  may be 5% or less, 10% or less, 15% or less, 20% or less, 25% or less, 50% or less, 75% or less, 80% or less, 85% or less, 90% or less, or 95% or less of the distance between the proximal collar  28  and the distal collar  30  when the expandable cage  22  is in the expanded configuration. In some embodiments, the length of the central stop  34  may be 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 50% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more of the distance between the proximal collar  28  and the distal collar  30  when the expandable cage  22  is in the expanded configuration. In some embodiments, the central stop  34  may have a length of about 1 mm, about 2 mm, about 3 mm, about 4 mm, or about 5 mm, for example. 
     As shown in  FIG. 2C , the vascular recanalization device  10  may be withdrawn proximally through the lumen  62  of an elongate tubular member  60  of a medical device, such as a medical catheter (e.g., a microcatheter), at the completion of the medical procedure. For instance, the medical personnel may pull the elongate wire  12  proximally to withdraw the vascular recanalization device  10  through the elongate tubular member  60 . 
     As the elongate wire  12  is being pulled proximally by the medical personnel, the central stop  34  moves proximally relative to the expandable cage  22  until the proximal end of the central stop  34  abuts the proximal collar  28  of the expandable cage  22 . Thus, the central stop  34  exerts a force on the proximal collar  28 , in which the exerted force has a directional component in a proximal direction parallel to the longitudinal axis of the elongate wire  12 , effectively resulting in the expandable cage  22  being pulled proximally through the elongate tubular member  60  via the proximal collar  28  by pulling the elongate wire  12  proximally. 
     Effectively pulling the expandable cage  22  through the elongate tubular member  60  has the effect of reducing the force necessary to move the expandable cage  22  through the elongate tubular member  60  relative to situations in which the expandable cage  22  would be pushed through the elongate tubular member  60 . Pulling the expandable cage  22  proximally from the proximal collar  28  will tend to cause the expandable cage  22  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  22  and the inner surface of the elongate tubular member  60 , whereas pushing the expandable cage  22  proximally from the distal collar  30  would tend to cause the expandable cage  22  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  22  and the inner surface of the elongate tubular member  60 . 
     A second exemplary embodiment of a vascular recanalization device  110  is depicted in  FIG. 3 . The vascular recanalization device  110  is similar in many respects to the vascular recanalization device  10  of  FIG. 1 , with some variations. For example, the vascular recanalization device  110  may include an elongate wire  112  having a proximal end  114  and a distal end  116 . The distal end  116  of the elongate wire  112  may include a distal tip, such as a distal coil tip  118  attached to the elongate wire  112 , or other desired tip configuration. 
     The vascular recanalization device  110  may also include an expandable cage  122  coupled to the elongate wire  112 . The expandable cage  122  may be similar to the expandable cage  22  discussed above regarding the vascular recanalization device  10  of  FIG. 1 . For instance, the expandable cage  122  may include a proximal collar  128 , a distal collar  130  and an expandable mesh  132  similar in configuration and function to the proximal collar  28 , distal collar  30  and expendable mesh  32 , respectively, discussed above. 
     The expandable cage  122  may be slidably coupled to the elongate wire  112  to allow longitudinal translation of the elongate wire  112  relative to the expandable cage  122  while the expandable cage  122  remains stationary. In some embodiments the expandable cage  122  may be slidably coupled to the elongate wire  112  such that the proximal end  124  of the expandable cage  122  is slidably coupled to the elongate wire  112  and/or the distal end  126  of the expandable cage  122  is slidably coupled to the elongate wire  112 . In some embodiments, no portion of the expandable cage  122  is fixedly secured to the elongate wire  112  or any other component of the vascular recanalization device  110 . 
     As discussed above, the expandable cage  122  may include a proximal collar  128  proximate the proximal end  124  of the expandable cage  122  and a distal collar  130  proximate the distal end  126  of the expandable cage  122 . The proximal collar  128  and/or the distal collar  130  may be slidably and rotatably disposed on the elongate wire  112 . 
     The vascular recanalization device  110  may further include a central stop  134  secured to the elongate wire  112  at a location intermediate the proximal end  124  and the distal end  126  of the expandable cage  122 . For example, the central stop  134  may be secured to the elongate wire  112  intermediate the proximal collar  128  and the distal collar  130  of the expandable cage  122 . The expandable mesh  132  may circumferentially surround and be spaced away from the central stop  134 . In some embodiments, the central stop  134  may be a helical coil member or other tubular member disposed around the elongate wire  112 , or the central stop  134  may be one or more projections formed around or secured to the elongate wire  112 . 
     The central stop  134  may be provided to prevent the expandable cage  122  from sliding distally on the elongate wire  112  distally of the central stop  134  and may be provided to prevent the expandable cage  122  from sliding proximally on the elongate wire  112  proximally of the central stop  134 . For instance, the central stop  134  may prevent the proximal end  124  of the expandable cage  122  from sliding distal of the central stop  134  and the central stop  134  may prevent the distal end  126  of the expandable cage  122  from sliding proximal of the central stop  134 . Thus, in the illustrative example of the vascular recanalization device  110  shown in  FIG. 3 , the central stop  134  may prevent the proximal collar  128  from sliding distal of the central stop  134 , and the central stop  134  may prevent the distal collar  130  from sliding proximal of the central stop  134 . 
     The vascular recanalization device  110  may also include a proximal stop  136  located proximally of the central stop  134  and a distal stop  138  located distally of the central stop  134 . In some embodiments, the proximal stop  136  may be the distal end of the flexible tubular member  120  secured to the elongate wire  112  which may be similar to the flexible tubular member  20  of the vascular recanalization device  10 , or the proximal stop  136  may be another component of the vascular recanalization device  110 . In some embodiments, the distal stop  138  may be the proximal end of the distal coil tip  118 , or the distal stop  138  may be another component of the vascular recanalization device  110 . 
     The proximal collar  128 , and thus the proximal end  124  of the expandable cage  122 , may be longitudinally slidable along the elongate wire  112  between the proximal stop  136  and the central stop  134 , and the distal collar  130 , and thus the distal end  126  of the expandable cage  122 , may be longitudinally slidable along the elongate wire  112  between the central stop  134  and the distal stop  138 . Some possible distances in which the proximal collar  128  and the distal collar  130  may slide along the elongate wire  112  are disclosed above regarding the vascular recanalization device  10 . 
       FIGS. 4A-4C  illustrate an exemplary mode of operating the vascular recanalization device  110  of  FIG. 3  during a medical procedure to re-establish blood flow through a vessel lumen. As shown in  FIG. 4A , the vascular recanalization device  110  may be advanced distally through the lumen  162  of an elongate tubular member  160  of a medical device, such as a medical catheter (e.g., a microcatheter), during a medical procedure. For instance, the medical personnel may push the elongate wire  112  distally to advance the vascular recanalization device  110  through the elongate tubular member  160  located in a lumen of a vessel V. 
     While positioned in the lumen  162  of the elongate tubular member  160  the expandable cage  122  may assume a collapsed configuration in which the expandable cage  122  has a reduced diameter relative to an expanded configuration which the expandable cage  122  may be expanded to upon exiting the elongate tubular member  160 . In some embodiments, the elongate tubular member  160  may constrain the expandable cage  122  to the collapsed configuration while positioned in the lumen  162  of the elongate tubular member  160 . In the collapsed configuration, the expandable cage  122  may have a collapsed cage length measured from the proximal collar  128  to the distal collar  130 . Furthermore, in the expanded configuration, shown in  FIG. 4B , the expandable cage  122  may have an expanded cage length measured from the proximal collar  128  to the distal collar  130 . The collapsed cage length may be greater than the expanded cage length. 
     As shown in  FIG. 4A , the distance between the proximal stop  136  and the distal end of the central stop  134  may be equal to or greater than the collapsed cage length in order to allow the expandable cage  122  to be fully collapsed and elongated to the collapsed configuration while being advanced distally through the elongate tubular member  160 . Furthermore, as shown in  FIG. 4C , the distance between the proximal end of the central stop  134  and the distal stop  138  may be equal to or greater than the collapsed cage length in order to allow the expandable cage  122  to be fully collapsed and elongated to the collapsed configuration while being withdrawn proximally through the elongate tubular member  160 . 
     As the elongate wire  112  is being pushed distally by the medical personnel, the central stop  134  moves distally relative to the expandable cage  122  until the distal end of the central stop  134  abuts the distal collar  130  of the expandable cage  122 . Thus, the central stop  134  exerts a force on the distal collar  130 , in which the exerted force has a directional component in a distal direction parallel to the longitudinal axis of the elongate wire  112 , effectively resulting in the expandable cage  122  being pulled distally through the elongate tubular member  160  via the distal collar  130  by pushing the elongate wire  112  distally. 
     Effectively pulling the expandable cage  122  through the elongate tubular member  160  has the effect of reducing the force necessary to move the expandable cage  122  through the elongate tubular member  160  relative to situations in which the expandable cage  122  would be pushed through the elongate tubular member  160 . Pulling the expandable cage  122  distally from the distal collar  130  will tend to cause the expandable cage  122  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  122  and the inner surface of the elongate tubular member  160 , whereas pushing the expandable cage  122  distally from the proximal collar  128  would tend to cause the expandable cage  122  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  122  and the inner surface of the elongate tubular member  160 . 
     The vascular recanalization device  110  may be advanced distally until the expandable cage  122  is deployed from the distal end of the elongate tubular member  160  to deliver the expandable cage  122  to a target location within the vessel V. As shown in  FIG. 4B , once deployed from the elongate tubular member  160 , the expandable cage  122  may be expanded to the expanded configuration in which the expandable cage  122  is expanded in diameter and shortened in length. In some embodiments, the expandable cage  122  may be self-expanding in which the expandable cage  122  automatically expands upon being deployed from the elongate tubular member  160 . In other embodiments, the expandable cage  122  may be manually, selectively and/or controllably expanded, such as by the manipulation of a component of the vascular recanalization device  110 , application of a stimulus, and/or activation/deactivation of an energy source, for example. In the expanded configuration, the expandable cage  122  may exert a radially outward force on the vessel V to open a blockage and re-establish blood flow through the vessel V. The openness of the interstitial openings between filaments of the expandable mesh  132  allows blood to flow through the expandable cage  122 . Furthermore, in some embodiments, the expandable mesh  132  may be configured to capture embolic material while deployed in the vessel V. 
     When the expandable cage  122  is in its expanded configuration and deployed in the vessel V, expandable cage  122  may be shortened in length such that the central stop  134  abuts both the proximal collar  128  and the distal collar  130 , simultaneously. Thus, the central stop  134  may prevent further shortening and/or radial expansion of the expandable cage  122  beyond a threshold amount. 
     As shown in  FIG. 4C , the vascular recanalization device  110  may be withdrawn proximally through the lumen  162  of an elongate tubular member  160  of a medical device, such as a medical catheter (e.g., a microcatheter), at the completion of the medical procedure. For instance, the medical personnel may pull the elongate wire  112  proximally to withdraw the vascular recanalization device  110  through the elongate tubular member  160 . 
     As the elongate wire  112  is being pulled proximally by the medical personnel, the central stop  134  moves proximally relative to the expandable cage  122  until the proximal end of the central stop  134  abuts the proximal collar  128  of the expandable cage  122 . Thus, the central stop  134  exerts a force on the proximal collar  128 , in which the exerted force has a directional component in a proximal direction parallel to the longitudinal axis of the elongate wire  112 , effectively resulting in the expandable cage  122  being pulled proximally through the elongate tubular member  160  via the proximal collar  128  by pulling the elongate wire  112  proximally. 
     Effectively pulling the expandable cage  122  through the elongate tubular member  160  has the effect of reducing the force necessary to move the expandable cage  122  through the elongate tubular member  160  relative to situations in which the expandable cage  122  would be pushed through the elongate tubular member  160 . Pulling the expandable cage  122  proximally from the proximal collar  128  will tend to cause the expandable cage  122  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  122  and the inner surface of the elongate tubular member  160 , whereas pushing the expandable cage  122  proximally from the distal collar  130  would tend to cause the expandable cage  122  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  122  and the inner surface of the elongate tubular member  160 . 
     A third illustrative embodiment of a vascular recanalization device  210  is depicted in  FIG. 5 . The vascular recanalization device  210  may include an elongate wire  212  having a proximal end  214  and a distal end  216 . In operation, the distal end  216  of the elongate wire  212  may be advanced through the vasculature of a patient while the proximal end  214  remains exterior of the patient to be manipulated by the medical personnel during a medical procedure. 
     The distal end  216  of the elongate wire  212  may include a distal tip, such as a distal coil tip  218  attached to the elongate wire  212 . For example, the distal coil tip  218  may include a wire filament helically wound into a coil. The coil may be disposed over a distal portion of the elongate wire  212  and secured to the elongate wire  212 , such as by welding, soldering, brazing, or adhesive bonding in some instances. In other embodiments, the distal tip of the elongate wire  212  may have a different configuration, if desired. 
     The vascular recanalization device  210  may also include an expandable cage  222  coupled to the elongate wire  212 . The expandable cage  222  may be similar to the expandable cage  22  discussed above regarding the vascular recanalization device  10  of 
       FIG. 1 . For instance, the expandable cage  222  may include a proximal collar  228 , a distal collar  230  and an expandable mesh  232  similar in configuration and function to the proximal collar  28 , distal collar  30  and expendable mesh  32 , respectively, discussed above. 
     The expandable cage  222  may be slidably coupled to the elongate wire  212  to allow longitudinal translation of the elongate wire  212  relative to the expandable cage  222  while the expandable cage  222  remains stationary. In some embodiments the expandable cage  222  may be slidably coupled to the elongate wire  212  such that the proximal end  224  of the expandable cage  222  is slidably coupled to the elongate wire  212  and/or the distal end  226  of the expandable cage  222  is slidably coupled to the elongate wire  212 . In some embodiments, no portion of the expandable cage  222  is fixedly secured to the elongate wire  212  or any other component of the vascular recanalization device  210 . 
     As discussed above, the expandable cage  222  may include a proximal collar  228  proximate the proximal end  224  of the expandable cage  222  and a distal collar  230  proximate the distal end  226  of the expandable cage  222 . The proximal collar  228  and/or the distal collar  230  may be slidably and rotatably disposed on the elongate wire  212 . 
     The vascular recanalization device  210  may also include an elongate tubular member  270  disposed over the elongate wire  212  such that the elongate wire  212  is longitudinally movable through the elongate tubular member  270 . The elongate tubular member  270  may have any desired length such that a proximal end  272  of the elongate tubular member  270  may be located exterior of a patient during a medical procedure while a distal end  274  of the elongate tubular member  270  may be located within the vessel of the patient and proximal of the expandable cage  222  during the medical procedure. In some embodiments, the elongate tubular member  270  may be disconnected from the expandable cage  222  such that the expandable cage  222  is longitudinally moveable relative to the elongate wire  212  while the elongate tubular member  270  remains stationary. In the embodiment illustrated in  FIG. 5 , however, the proximal end  224  of the expandable cage  222  is attached to the distal end  274  of the elongate tubular member  270 . For instance, the elongate tubular member  270  may be attached to the proximal collar  228  of the expandable cage  222 . In some embodiments, the proximal collar  228  may be, at least in part, formed of a portion of the elongate tubular member  270 . 
     The vascular recanalization device  210  may further include a central stop  234  secured to the elongate wire  212  at a location intermediate the proximal end  224  and the distal end  226  of the expandable cage  222 . For example, the central stop  234  may be secured to the elongate wire  212  intermediate the proximal collar  228  and the distal collar  230  of the expandable cage  222 . The expandable mesh  232  may circumferentially surround and be spaced away from the central stop  234 . In some embodiments, the central stop  234  may be a helical coil member or other tubular member disposed around the elongate wire  212 , or the central stop  234  may be one or more projections formed around or secured to the elongate wire  212 . 
     The central stop  234  may be provided to prevent the expandable cage  222  from sliding distally on the elongate wire  212  distally of the central stop  234  and may be provided to prevent the expandable cage  222  from sliding proximally on the elongate wire  212  proximally of the central stop  234 . For instance, the central stop  234  may prevent the proximal end  224  of the expandable cage  222  from sliding distal of the central stop  234  and the central stop  234  may prevent the distal end  226  of the expandable cage  222  from sliding proximal of the central stop  234 . Thus, in the illustrative example of the vascular recanalization device  210  shown in  FIG. 5 , the central stop  234  may prevent the proximal collar  228  from sliding distal of the central stop  234 , and the central stop  234  may prevent the distal collar  230  from sliding proximal of the central stop  234 . 
     Furthermore, in some embodiments the central stop  234  may function to limit shortening of the expandable cage  222  beyond a threshold amount when the expandable cage  222  is deployed in a vessel lumen. For instance, in a fully expanded configuration, the central stop  234  may prevent further relative movement of the proximal collar  228  toward the distal collar  230  of the expandable cage  222 . 
     The vascular recanalization device  210  may also include a distal stop  238  located distally of the central stop  234 . In some embodiments, the distal stop  238  may be the proximal end of the distal coil tip  218 , or the distal stop  238  may be another component of the vascular recanalization device  210 . The distal collar  230 , and thus the distal end  226  of the expandable cage  222 , may be longitudinally slidable along the elongate wire  212  between the central stop  234  and the distal stop  238 . 
     In some embodiments, for example in embodiments in which the expandable cage  222  is not attached to the elongate tubular member  270 , the vascular recanalization device  210  may also include a proximal stop located proximally of the central stop  234 . In some embodiments, the proximal stop may be the distal end  274  of the elongate tubular member  270 , or the proximal stop may be another component of the vascular recanalization device  210 . In embodiments in which the proximal stop is the distal end  274  of the elongate tubular member  270 , the proximal stop may be longitudinally displaceable relative to the central stop  234 . In such embodiments, the proximal collar  228 , and thus the proximal end  224  of the expandable cage  222 , may be longitudinally slidable along the elongate wire  212  between the proximal stop and the central stop  234 . 
       FIGS. 6A-6F  illustrate an exemplary mode of operating the vascular recanalization device  210  of  FIG. 5  during a medical procedure to re-establish blood flow through a vessel lumen. As shown in  FIG. 6A , the vascular recanalization device  210  may be advanced distally through the lumen  262  of an elongate tubular member  260  of a medical device, such as a medical catheter (e.g., a microcatheter), during a medical procedure. For instance, the medical personnel may simultaneously push the elongate wire  212  and elongate tubular member  270  distally to advance the vascular recanalization device  210  through the elongate tubular member  260  located in a lumen of a vessel V. 
     While positioned in the lumen  262  of the elongate tubular member  260  the expandable cage  222  may assume a collapsed configuration in which the expandable cage  222  has a reduced diameter relative to an expanded configuration which the expandable cage  222  may be expanded to upon exiting the elongate tubular member  260 . In some embodiments, the elongate tubular member  260  may constrain the expandable cage  222  to the collapsed configuration while positioned in the lumen  262  of the elongate tubular member  260 . In the collapsed configuration, the expandable cage  222  may have a collapsed cage length measured from the proximal collar  228  to the distal collar  230 . Furthermore, in the expanded configuration, shown in  FIG. 6D , the expandable cage  222  may have an expanded cage length measured from the proximal collar  228  to the distal collar  230 . The collapsed cage length may be greater than the expanded cage length. 
     As shown in  FIG. 6A , the distance between the proximal collar  228  and the distal collar in the collapsed configuration may be maintained by controlling the distance between the distal end  274  of the elongate tubular member  270  and the distal end of the central stop  234 , effectively stretching the expandable cage  222  between the distal end  274  of the elongate tubular member  270  and the distal end of the central stop  234  secured to the elongate wire  212 . 
     As the vascular recanalization device  210  is being pushed distally by the medical personnel, the central stop  234  may abut the distal collar  230  of the expandable cage  222 . Thus, the central stop  234  exerts a force on the distal collar  230 , in which the exerted force has a directional component in a distal direction parallel to the longitudinal axis of the elongate wire  212 , effectively resulting in the expandable cage  222  being pulled distally through the elongate tubular member  260  via the distal collar  230  by pushing the elongate wire  212  distally. 
     Effectively pulling the expandable cage  222  through the elongate tubular member  260  has the effect of reducing the force necessary to move the expandable cage  222  through the elongate tubular member  260  relative to situations in which the expandable cage  222  would be pushed through the elongate tubular member  260 . Pulling the expandable cage  222  distally from the distal collar  230  will tend to cause the expandable cage  222  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  222  and the inner surface of the elongate tubular member  260 , whereas pushing the expandable cage  222  distally from the proximal collar  228  would tend to cause the expandable cage  222  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  222  and the inner surface of the elongate tubular member  260 . 
     The vascular recanalization device  210  may be advanced distally until the expandable cage  222  is deployed from the distal end of the elongate tubular member  260 , shown in  FIG. 6B , to deliver the expandable cage  222  to a target location within the vessel V. Once deployed from the elongate tubular member  260 , the expandable cage  222  may be expanded to the expanded configuration in which the expandable cage  222  is expanded in diameter and shortened in length. In some embodiments, the expandable cage  222  may be self-expanding in which the expandable cage  222  automatically expands upon being deployed from the elongate tubular member  260 . In other embodiments, the expandable cage  222  may be manually, selectively and/or controllably expanded, such as by the manipulation of a component of the vascular recanalization device  210 , application of a stimulus, and/or activation/deactivation of an energy source, for example. In some embodiments, the expandable cage  222  may be partially self-expanding in which the expandable cage  222  partially expands automatically followed by further manual, selective and/or controlled expansion to the expanded configuration. In the expanded configuration, the expandable cage  222  may exert a radially outward force on the vessel V to open a blockage and re-establish blood flow through the vessel V. The openness of the interstitial openings between filaments of the expandable mesh  232  allows blood to flow through the expandable cage  222 . Furthermore, in some embodiments, the expandable mesh  232  may be configured to capture embolic material while deployed in the vessel V. 
     As illustrated in  FIGS. 6C and 6D , once deployed from the elongate tubular member  260 , the expandable cage  222  may be manually expanded from a collapsed configuration shown in  FIG. 6B  to a fully expanded configuration shown in  FIG. 6D  by pulling the elongate wire  212  proximally relative to the elongate tubular member  270  of the vascular recanalization device  210  and/or by pushing the elongate tubular member  270  distally relative to the elongate wire  212  of the vascular recanalization device  210 . In some embodiments, the expandable cage  222  may automatically partially expand upon deployment from the elongate tubular member  260 , and may then be further expanded to a fully expanded configuration by pulling the elongate wire  212  proximally relative to the elongate tubular member  270  and/or pushing the elongate tubular member  270  distally relative to the elongate wire  212 . 
     When the expandable cage  222  is deployed in the vessel V, the elongate wire  212  may be longitudinally translated through the expandable cage  222  and/or rotated while the expandable cage  222  stays stationary, allowing the expandable cage  222  to float on the elongate wire  212  up to a threshold amount. Thus, the expandable cage  222  may float on the elongate wire  212  as the proximal collar  228  slides along the elongate wire  212  proximal of the central stop  234 , and the distal collar  230  slides along the elongate wire  212  between the central stop  234  and the distal stop  238 . 
     For instance, once deployed from the elongate tubular member  260 , the elongate wire  212  is free to move longitudinally between a first position in which the distal collar  230  abuts the central stop  234  and is spaced away from the distal stop  238  and a second position in which the distal collar  230  abuts the distal stop  238  and is spaced away from the central stop  234 . Thus, the elongate wire  212  is free to move longitudinally a distance equal to the distance between the central stop  234  and the distal stop  238  minus the length of the distal collar  230 . This distance may be considered the float length of the expandable cage  222  on the elongate wire  212 . In some embodiments, the float length may be 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, 10 mm or more, 15 mm or more, 20 mm or more, or 30 mm or more, for example. 
     The length of the central stop  234  may be any desired length. In some embodiments, the length of the central stop  234  may be 5% or less, 10% or less, 15% or less, 20% or less, 25% or less, 50% or less, 75% or less, 80% or less, 85% or less, 90% or less, or 95% or less of the distance between the proximal collar  228  and the distal collar  230  when the expandable cage  222  is in the collapsed configuration. In some embodiments, the length of the central stop  234  may be 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 50% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more of the distance between the proximal collar  228  and the distal collar  230  when the expandable cage  222  is in the collapsed configuration. In some embodiments, the central stop  234  may have a length of about 1 mm, about 2 mm, about 3 mm, about 4 mm, or about 5 mm, for example. 
     As the elongate wire  212  is pulled proximally and/or the elongate tubular member  270  is pushed distally, the distal stop  238  may abut the distal collar  230  of the expandable cage  222 , as shown in  FIG. 6C . Further proximal movement of the elongate wire  212  relative to the elongate tubular member  270  and/or distal movement of the elongate tubular member  270  relative to the elongate wire  212  will result in the expandable cage  222  shortening in length as the distal collar  230  is moved toward the proximal collar  228 . The distal collar  230  may be drawn toward the proximal collar  228  until the central stop  234  abuts the proximal collar  228 , sandwiching the proximal collar  228  between the distal end  274  of the elongate tubular member  270  and the central stop  234 , shown in  FIG. 6D . In this configuration, the expandable cage  222  is fully expanded to its expanded configuration in which the expandable cage  222  is expanded in diameter and shortened in length. In the expanded configuration, the expandable cage  222  may exert a radially outward force on the vessel V to open a blockage and re-establish blood flow through the vessel V. 
     In order to return the expandable cage  222  to its collapsed configuration for withdrawal from the vessel V, the proximal collar  228  may be moved away from the distal collar  230 , lengthening the expandable cage  222 . To this end, the elongate tubular member  270  may be moved proximally relative to the elongate wire  212  and/or the elongate wire  212  may be moved distally relative to the elongate tubular member  270 , as shown in  FIG. 6E . Relative movement between the elongate tubular member  270  and the elongate wire  212  results in stretching the expandable cage  222  between the distal end  274  of the elongate tubular member  270  and the distal end of the central stop  234 . 
     As shown in  FIG. 6F , the vascular recanalization device  210  may be withdrawn proximally through the lumen  262  of an elongate tubular member  260  of a medical device, such as a medical catheter (e.g., a microcatheter), at the completion of the medical procedure. For instance, the medical personnel may pull the elongate wire  212  and elongate tubular member  270  proximally to withdraw the vascular recanalization device  210  through the elongate tubular member  260 . Prior to withdrawing the expandable cage  222  into the elongate tubular member  260 , the central stop  234  may be moved away from the distal end  274  of the elongate tubular member  270  and/or the proximal collar  228  (e.g., by moving the elongate wire  212  distally relative to the elongate tubular member  270  and/or moving the elongate tubular member  270  proximally relative to the elongate wire  212 ) to allow the collars  228 ,  230  of the expandable cage  222  to move away from one another so the expandable cage  222  can be returned to a collapsed configuration. 
     Pulling the expandable cage  222  proximally into the elongate tubular member  260  may cause the expandable cage  222  to further elongate such that the distal collar  230  moves out of contact with the central stop  234 , as shown in  FIG. 6F . 
     As the vascular recanalization device  210  is being pulled proximally by the medical personnel, pulling of the elongate tubular member  270  proximally exerts a force on the proximal collar  228 , in which the exerted force has a directional component in a proximal direction parallel to the longitudinal axis of the elongate wire  212 , effectively resulting in the expandable cage  222  being pulled proximally through the elongate tubular member  260  via the proximal collar  228  by pulling the elongate tubular member  270  proximally. 
     Effectively pulling the expandable cage  222  through the elongate tubular member  260  has the effect of reducing the force necessary to move the expandable cage  222  through the elongate tubular member  260  relative to situations in which the expandable cage  222  would be pushed through the elongate tubular member  260 . Pulling the expandable cage  222  proximally from the proximal collar  228  will tend to cause the expandable cage  222  to lengthen and thus tend to decrease in diameter, reducing frictional forces between the expandable cage  222  and the inner surface of the elongate tubular member  260 , whereas pushing the expandable cage  222  proximally from the distal collar  230  would tend to cause the expandable cage  222  to shorten and thus tend to enlarge in diameter, increasing frictional forces between the expandable cage  222  and the inner surface of the elongate tubular member  260 . 
     In an alternative embodiment in which the distal end  274  of the elongate tubular member  270  is not attached to the proximal collar  228  of the expandable cage  222 , during advancement of the vascular recanalization device  210  distally through the elongate tubular member  260 , the proximal stop (e.g., the distal end  274  of the elongate tubular member  270 ) may be located proximal of the central stop  234  a distance which will allow the expandable cage  222  to be fully collapsed and elongated to the collapsed configuration while being advanced distally through the elongate tubular member  260 . In other words, the distance between the proximal stop and the distal end of the central stop  234  may be greater than the distance between the proximal collar  228  and the distal collar  230  in the collapsed configuration. Upon deployment of the expandable cage  222  in a vessel V, the proximal stop may be moved toward the distal stop  238  (e.g., by moving the elongate wire  212  proximally relative to the elongate tubular member  270  and/or moving the elongate tubular member  270  distally relative to the elongate wire  212 ). In moving the proximal stop toward the distal stop  238 , the proximal stop contacts the proximal collar  228  and the distal stop  238  contacts the distal collar  230 . Further movement draws the distal collar  230  toward the proximal collar  228 , shortening the length of the expandable cage  222  in order to expand the expandable cage  222  to its expanded configuration. In the expanded configuration, the expandable cage  222  may exert a radially outward force on the vessel V to open a blockage and re-establish blood flow through the vessel V. 
     When the expandable cage  222  is in its expanded configuration and deployed in the vessel V, the elongate wire  212  may be longitudinally translated through the expandable cage  222  and/or rotated while the expandable cage  222  stays stationary and engaged against the vessel V, allowing the expandable cage  222  to float on the elongate wire  212 . Thus, longitudinal movement of the elongate wire  212  up to a threshold amount, whether inadvertent or intentional, will not cause the expandable cage  222  to move. 
     For instance, in the expanded configuration, the elongate wire  212  is free to move longitudinally between a first position in which the central stop  234  abuts the distal collar  230  and is spaced away from the proximal collar  228  and a second position in which the central stop  234  abuts the proximal collar  228  and is spaced away from the distal collar  230 . Thus, the elongate wire  212  is free to move longitudinally a distance equal to the distance between the proximal collar  228  and the distal collar  230  minus the length of the central stop  234 . This distance may be considered the float length of the expandable cage  222  on the elongate wire  212 . In some embodiments, the float length may be 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, 10 mm or more, 15 mm or more, 20 mm or more, or 30 mm or more, for example. 
     The distal collar  230  may be drawn toward the proximal collar  228  up to a threshold amount until the central stop  234  abuts both the proximal collar  228  and the distal collar  230 , sandwiching the central stop  234  between the proximal collar  228  and the distal collar  230  and restricting the expandable cage  222  from floating on the elongate wire  212 . In some embodiments, the length of the central stop  234  may be chosen to control the extent of expansion of the expandable cage  222 . 
     In order to return the expandable cage  222  to its collapsed configuration for withdrawal from the vessel V, the proximal collar  228  may be moved away from the distal collar  230 , lengthening the expandable cage  222 . To this end, the elongate tubular member  270  may be moved proximally relative to the elongate wire  212  and/or the elongate wire  212  may be moved distally relative to the elongate tubular member  270  to increase the distance between the proximal stop and the distal stop  238 . The distance between the proximal stop and the distal stop  238  may be equal to or greater than the collapsed cage length in order to allow the expandable cage  222  to be fully collapsed and elongated to the collapsed configuration while being withdrawn proximally through the elongate tubular member  260 . 
     The vascular recanalization device  210  may then be withdrawn into the elongate tubular member  260 . For instance, when pulling the vascular recanalization device  210  proximally, the distal stop  238  may contact the distal collar  230  of the expandable cage  222 , pushing the expandable cage  222  into the elongate tubular member  260 . 
       FIGS. 7-10  illustrate various exemplary embodiments of an expandable mesh which may be used in the expandable cage of the vascular recanalization devices shown in  FIGS. 1 ,  3  and  5 . It is noted that the various embodiments shown in  FIGS. 7-10  are illustrated as if the tubular construct of the expandable mesh were cut longitudinally and then unrolled into a flattened configuration to better illustrate the mesh patterns. 
     A first exemplary embodiment of an expandable mesh  332 , shown in  FIG. 7 , includes a repeating pattern of interconnected filaments  348  defining interstitial openings  352  defined between adjacent filaments  348 . The pattern, as well as other patterns of an expandable mesh described herein, may be manufactured by interweaving or interconnecting a plurality of individual fibers to form a tubular construct, the pattern may be manufactured from removing portions of a tubular member, or the pattern may be manufactured from removing portions of a flat sheet and then rolled into a tubular construct, and then incorporated into the expandable cage  22 , for example. The expandable mesh  332  may include end filaments or extensions  350  extending from the main meshwork. The extensions  350  may be configured to be coupled to the collars  28 ,  30  of the expandable cage  22 . 
       FIG. 8  illustrates a second exemplary embodiment of an expandable mesh  432 . The expandable mesh  432  includes a repeating pattern of interconnected filaments  448  defining interstitial openings  452  defined between adjacent filaments  448 . The interstitial openings  452  may resemble a peanut shape, having two enlarged end regions spaced apart by a narrower central region. The pattern may include a pair of adjoining interstitial openings  452   a  extending in a first direction adjacent a pair of adjoining interstitial openings  452   b  extending in a second direction, generally orthogonal to the first direction. This arrangement of adjacent pairs of interstitial openings  452  may be repeated throughout the expandable mesh  432  pattern. The expandable mesh  432  may include end filaments or extensions  450  extending from the main meshwork, which may be configured to be coupled to the collars  28 ,  30  of the expandable cage  22 . 
       FIG. 9  illustrates another exemplary embodiment of an expandable mesh  532 , including a repeating pattern of interconnected filaments  548  defining interstitial openings  552  defined between adjacent filaments  548 . The expandable mesh  532  may include end filaments or extensions  550  extending from the main meshwork, which may be configured to be coupled to the collars  28 ,  30  of the expandable cage  22 . As shown in  FIG. 9 , the proximal end  562  of the expandable mesh  532  may be configured differently than the distal end  564  of the expandable mesh  532 . It can be appreciated that as the expandable mesh  532  is rolled into a tubular construct, the distal end  564  of the expandable mesh  532  may extend radially inward toward the central longitudinal axis of the expandable mesh  532 , forming a closed distal end, whereas the proximal end  562  of the expandable mesh  532  may create a proximal mouth or opening. Such a configuration may allow embolic material to flow into the proximal mouth and be trapped within the expandable mesh  532 . 
       FIG. 10  illustrates yet another exemplary embodiment of an expandable mesh  632  including a repeating pattern of interconnected filaments  648  defining interstitial openings  652  defined between adjacent filaments  648 . The expandable mesh  632  may include end filaments or extensions  650  extending from the main meshwork, which may be configured to be coupled to the collars  28 ,  30  of the expandable cage  22 . The pattern may include a longitudinal row of large interstitial openings  652   a  followed by a longitudinal row of small interstitial openings  652   b . Rows of large interstitial openings  652   a  and rows of small intersitical openings  652   b  may be alternatingly arranged around the circumference of the expandable mesh  632 . Similar to the embodiment of  FIG. 9 , when the expandable mesh  632  is rolled into a tubular construct, the distal end  664  of the expandable mesh  632  may extend radially inward toward the central longitudinal axis of the expandable mesh  632 , forming a closed distal end, whereas the proximal end  662  of the expandable mesh  632  may create a proximal mouth or opening. Such a configuration may allow embolic material to flow into the proximal mouth and be trapped within the expandable mesh  632 . 
     Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.