Abstract:
Embolic protection filter assembly and method of using the same. In some embodiments, the present invention comprises an embolic protection filter slidably disposed over an elongate shaft.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to devices for filtering debris from a body lumen. More particularly, the present invention pertains to devices for filtering embolic debris that is generated by intravascular intervention.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    Heart and vascular disease are majors problem in the United States and throughout the world. Conditions such as atherosclerosis result in blood vessels becoming blocked or narrowed. This blockage can result in lack of oxygenation of the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action.  
           [0003]    Occluded, stenotic, or narrowed blood vessels may be treated with a number of relatively non-invasive medical procedures including percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA), and atherectomy. Angioplasty techniques typically involve the use of a balloon catheter. The balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a stenotic lesion. The balloon is then inflated and the restriction of the vessel is opened. During an atherectomy procedure, the stenotic lesion may be mechanically cut away from the blood vessel wall using an atherectomy catheter.  
           [0004]    During angioplasty and atherectomy procedures, embolic debris can be separated from the wall of the blood vessel. If this debris enters the circulatory system, it could block other vascular regions including the neural and pulmonary vasculature. During angioplasty procedures, stenotic debris may also break loose due to manipulation of the blood vessel. Because of this debris, a number of devices, termed embolic protection devices, have been developed to filter out this debris.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The present invention relates to embolic protection filters. In some embodiments, the present invention includes an embolic protection filter assembly. The assembly may include a filter coupled to an elongate shaft. The filter may include a number of features. For example, the filter may also include or otherwise be coupled with a distal tip. In some embodiments, the filter (together with the distal the tip) may be slidable over the shaft.  
           [0006]    The filter may be delivered to an appropriate location (e.g., adjacent a lesion within a blood vessel) with a delivery catheter. In some embodiments, the filter may be self-expanding so that retracting the delivery catheter from the filter results in the filter expanding. An aspiration tube or other suitable aspiration means may be used to aspirate embolic debris from the filter at any time during the filtering procedure. Upon completing of the intervention, a retrieval catheter or other suitable means may be used to retrieve the filter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a partial cross-sectional view of an embodiment of an embolic protection filter assembly;  
         [0008]    [0008]FIG. 2 is a partial cross-sectional view of an embodiment of an embolic protection filter assembly, wherein the filter is collapsed within a delivery catheter;  
         [0009]    [0009]FIG. 3 is a perspective view of an embodiment of a support member for use with an embolic protection filter assembly;  
         [0010]    [0010]FIG. 4 is a partial cross-sectional view of an alternate embodiment of an embolic protection filter assembly;  
         [0011]    [0011]FIG. 5 is a partial cross-sectional view of an embolic protection filter assembly including an aspiration tube;  
         [0012]    [0012]FIG. 6 is a partial cross-sectional view of an embolic protection filter assembly including an alternative aspiration tube;  
         [0013]    [0013]FIG. 7 is a partial cross-sectional view of an embolic protection filter assembly wherein an aspiration tube is advanced over the filter, prolapsing the filter;  
         [0014]    [0014]FIG. 8 is a partial cross-sectional view of an embolic protection filter assembly wherein the filter includes a strut;  
         [0015]    [0015]FIG. 9 is a partial cross-sectional view of another example embolic protection filter assembly that includes a strut;  
         [0016]    [0016]FIG. 10 is a partial cross-sectional view of an embolic protection filter assembly partially collapsed;  
         [0017]    [0017]FIG. 11 is a partial cross-sectional view of an embolic protection filter assembly partially collapsed;  
         [0018]    [0018]FIG. 12 is a partial cross-sectional view of an embolic protection filter assembly wherein the filter includes more than one strut;  
         [0019]    [0019]FIG. 13 is a partial cross-sectional view of another example embolic protection filter assembly;  
         [0020]    [0020]FIG. 14 is a partial cross-sectional view of an embolic protection filter assembly collapsed;  
         [0021]    [0021]FIG. 15 is a partial cross-sectional view of an embolic protection filter assembly collapsed and disposed within a retrieval sheath;  
         [0022]    [0022]FIG. 16 is a partial cross-sectional view of an embolic protection filter assembly;  
         [0023]    [0023]FIG. 17 is a partial cross-sectional view of another example embolic protection filter assembly;  
         [0024]    [0024]FIG. 18 is a partial cross-sectional view of an embolic protection filter assembly collapsed;  
         [0025]    [0025]FIG. 19 is a partial cross-sectional view of an embolic protection filter assembly wherein the filter includes pull cord for collapsing the filter;  
         [0026]    [0026]FIG. 20 is a partial cross-sectional view of an embolic protection filter assembly wherein the pull cord is actuated and the filter is partially collapsed; and  
         [0027]    [0027]FIG. 21 is a partial cross-sectional view of an embolic protection filter assembly wherein an alternative pull cord is actuated and the filter is partially collapsed. 
     
    
     DETAILED DESCRIPTION  
       [0028]    The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings illustrate example embodiments of the claimed invention.  
         [0029]    [0029]FIG. 1 is a partial cross-sectional view of an embodiment of an embolic protection filter assembly  10 . Assembly  10  includes an embolic protection filter  12  coupled to an elongate shaft  14 . Filter  12  includes an expandable support member  18 . Support member  18  may be adapted and configured to shift filter  12  between a first generally collapsed configuration and a second generally expanded configuration to define an open filler month.  
         [0030]    Filter  12  may be comprised of a polyurethane nylon sheet, silicone filter or other suitable material. In some embodiments, the filter material may be injection molded over support member  18 . The filter material includes at least one opening that may be, for example, formed by laser techniques. The holes or openings are sized to allow blood flow therethrough but restrict flow of debris or emboli floating in the body lumen or cavity. As stated above, filter  12  is adapted to shift between a collapsed configuration and an expanded configuration. In general, the collapsed configuration is appropriate for advancing filter  12  through the vasculature and the expanded configuration is appropriate for collecting debris from the vasculature.  
         [0031]    Filter  12  may include distal portion  20  and an enlarged proximal portion  22 . Distal portion  20  may be generally tapered. Additionally, filter  12  may include a tapered tip or nose cone  24 . Proximal portion may be enlarged so as to increase the filtering capacity of filter  12 . Filtering capacity is defined as the amount of embolic material that filter  12  can capture before becoming saturated. This feature may allow multiple embodiments of filter  12  to be constructed that have different filtering capacities.  
         [0032]    As stated above, filter  12  may include or otherwise be coupled with tip  24 . Tip  24  generally includes a tapered distal region  26  and a proximal region  28  that is coupled to or directly connected to filter  12 . Distal region  26  is configured so that when filter  12  is disposed within a delivery catheter  30 , the tapered distal region  26  extends from a distal end  32  of delivery catheter  30  to provide it with an atraumatic tip (please see FIG. 2). It can be appreciated that catheter  30  may comprise any number of catheters (diagnostic, therapeutic, or guide) as well as other medical devices and should not be limited to a “delivery” catheter.  
         [0033]    In some embodiments, tip  24  is generally tubular and adapted to be slidable over shaft  14 . According to this embodiment, filter  12  is connected to tip  24  so that filter  12  can be advanced or “slid” over shaft  14 . A number of methods may be used to advance filter  12  over shaft  14 . For example, filter  12  may be disposed within delivery catheter  30  and advanced (along with delivery catheter  30 ) over shaft  14 . In this embodiment, filter  12  may have a greater coefficient of friction with delivery catheter  30  than with shaft  14  so that both filter  12  and delivery catheter  30  can be advanced over shaft  14  without filter  12  significantly shifting its position within catheter  30 . Alternatively, a pusher or other appropriate physical means may be used to advance filter  12  and tip  24  over shaft  14 .  
         [0034]    Upon reaching a desired location along shaft  14 , it is important to be able to remove delivery catheter  30  so that filter  12  may be delivered (i.e., expanded to essentially appose the blood vessel). In some embodiments, assembly  10  may include a distal stop  34  coupled to shaft  14 . Distal stop  34  is sized so that tip  24  may be passed over a portion of stop  34  and then be friction fit thereto. To allow delivery catheter  34  to be removed, it may be beneficial for the coefficient of friction between tip  24  and stop  34  to be greater than that between tip  24  and delivery catheter  30 . Thus, tip  24  can fit tightly enough with stop  34  so that catheter  30  can be retracted without significantly altering the position of filter  12 .  
         [0035]    Additionally, shaft  14  may include a proximal stop  35 . Proximal stop  35  is generally tapered (e.g., becomes larger in the distal direction) and allows assembly  10  to pass over (in the distal direction) but limit the ability of assembly  10  to pass back over in the proximal direction. Proximal stop  35  may be used in conjunction with distal stop  34  to define a specific target region along shaft  14  where filter  12  can be disposed. Moreover, proximal stop  35  may also be useful for holding filter  12  in position when retracting catheter  30 .  
         [0036]    The feature of tip  24  being generally tubular allows filter assembly  10  be used with essentially any shaft  14 . For example shaft  14  may comprise a guidewire, catheter (e.g., a guide, diagnostic, or therapeutic catheter), or other similar medical device. Thus, tip  24  can make assembly  10  very flexible in terms of its utility with a number of differing devices and interventions.  
         [0037]    [0037]FIG. 2 is a partial cross-sectional view of assembly  10 , wherein filter  12  is collapsed within delivery catheter  30 . The configuration shown in FIG. 2 is appropriate for advancing assembly  10  through the vasculature (or other body lumen). As can be seen, assembly  10  can be coupled to delivery catheter  30  such that filter  12  assumes the collapsed configuration within catheter  30  (e.g., by back-loading filter  12  into catheter  30 ). Also, tip  24  can be configured such that distal region  26  extends from distal end  32  of catheter  30 , thus providing an atraumatic tip to assembly  10 .  
         [0038]    In use, filter  12  (as well as tip  24  and catheter  30 ) can be advanced over shaft  14  to an area of interest. In some embodiments, filter  12  is advanced distally until tip  24  becomes friction fit or otherwise coupled to stop  34  as described above. Once assembly  10  is advanced to the desired location, catheter  30  can be withdrawn proximally from filter  12  and tip  24 . Withdrawing catheter  30  allows filter  12  to shift to the expanded configuration (e.g., by allowing support member  18  to self-expand).  
         [0039]    [0039]FIG. 3 is a perspective view of an embodiment of support member  18 , apart from filter  12 . Support member  18  may comprise a ring or loop. In some embodiments, it may be useful to incorporate the property of super-elasticity into support member  18 . For example, support member  18  may be comprised of a shape-memory and/or super-elastic alloy such as nickel-titanium alloy. The super-elasticity and/or shape memory properties can be used to bias support member into the (second) expanded configuration. Thus, support member  18  will cause filter  12  to self-expand when becoming unconfined by, for example, catheter  30 .  
         [0040]    A coil or wire  36  may be disposed about support member  18 . In some embodiments, wire  36  may be comprised of or include a coating or plating of radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of assembly  10  (and filter  12 ) in determining its location. Radiopaque materials can include, but not limited to, gold, platinum, palladium, tantalum, tungsten alloy, plastic material loaded with a radiopaque filler, etc.  
         [0041]    [0041]FIG. 4 is a partial cross-sectional view of an alternate embodiment of embolic protection filter assembly  110 . Assembly  110  is essentially the same in form and function as assembly  10  except that filter  112  includes a narrow proximal portion  138  in addition to distal portion  120  and enlarged proximal portion  122 . Because embolic debris can tend to accumulate near distal portion  120 , it may be desirable to increase the filtering capacity of distal portion  120 . Narrow proximal portion  138  accomplishes this by providing additional surface area to distal portion  120 . Thus, narrow proximal portion  138  may be described as being an extension of distal portion  120 . In some embodiments, narrow proximal portion  138  extends proximally of portion  122 . It can be appreciated that the length of narrow proximal portion  138  can be altered to suit multiple embodiments without departing from the scope of the invention.  
         [0042]    Narrow proximal portion  138  may also include a support member (not shown) that functions essentially the same as support member  18 . According to this embodiment, narrow proximal portion  138  can be adapted to shift between expanded and collapsed configurations. Alternatively, narrow proximal portion  138  may include an expanding frame or be otherwise self-expanding.  
         [0043]    For several reasons, it may be desirable to aspirate captured embolic debris from filter  12  during an intervention. For example, filter  12  may become saturated with debris and begin to occlude blood flow through a blood vessel. FIG. 5 is a partial cross-sectional view of embolic protection filter assembly  10  further comprising an aspiration tube  40 . Aspiration tube  40  includes an aspiration lumen  42  and a distal end  44 . Aspiration tube  40  may advanced, for example through catheter  30 , to a location near filter  12 . Application of a vacuum to aspiration tube  40  allows debris to be aspirated from filter  12  through lumen  42 .  
         [0044]    Aspiration tube  40  may be used by advancing it within catheter  30  (e.g., through a lumen within catheter  30 ) until distal end  44  is at least partially disposed adjacent filter  12 . In some embodiments, distal end  44  extends within a substantial portion of filter  12  so that embolic debris can be aspirated from a significant portion thereof.  
         [0045]    [0045]FIG. 5 also illustrates that catheter  30  may include a port  46  adapted to allow single-operator-exchanges of medical devices over shaft  14 . This feature may be essentially the same as other analogous single-operator-exchange medical devices.  
         [0046]    [0046]FIG. 6 is a partial cross-sectional view of embolic protection filter assembly  10  further comprising an alternative aspiration tube  48 . Tube  48  is essentially the same in form and function as tube  40  and includes an aspiration lumen  50  and a distal end  52 . In some embodiments, tube  48  is delivery catheter  30  or can be used in place of catheter  30 . Alternatively, tube  48  can be advanced over shaft  14  independently of delivery catheter  30 .  
         [0047]    After an intervention is complete, assembly  10  can be retrieved from the vasculature. FIG. 7 illustrates an embodiment suitable for retrieval wherein a tube  52  is advanced over filter  12 , prolapsing filter  12 . Tube  52  may comprise a retrieval catheter, an aspiration tube (e.g., tube  40  or  48 ), delivery catheter  30 , or any other suitable tube.  
         [0048]    Tube  52  can be advanced over shaft  14  in the distal direction until encountering filter  12 . Tube  52  can then be further advanced so as to prolapse filter  12 . When prolapsed, filter  12  generally becomes disposed over proximal portion  28  of tip  24 . Tube  52  can then be advanced over filter  12 . Prolapsing filter  12  places filter  12  in a collapsed configuration suitable for removal from the vasculature. Because filter  12  may contain embolic debris and because prolapsing filter  12  may cause the debris to disassociate from filter  12 , it may be beneficial to apply a vacuum to tube  52  in order to aspirate debris from filter  12  before, during, and after prolapsing filter  12 .  
         [0049]    [0049]FIG. 8 is a partial cross-sectional view of embolic protection filter assembly  210 . Assembly  210  is essentially the same in form and function as assembly  10 , except that filter  212  includes a strut  256  extending between proximal portion  222  and shaft  14 . Filter  212  is essentially the same as filter  12  and includes distal portion  220 . Strut  256  may allow a catheter or other retrieval device (e.g., catheter  30 ) to at least partially collapse filter  212  so that it may be disposed within the retrieval catheter. For example, when distal end  32  of catheter  30  is moved in the distal direction distal end  32  may engage strut  256 . The result of this engagement is filter  212  tending to shift to the collapsed configuration.  
         [0050]    [0050]FIG. 9 is a partial cross-sectional view of another example embolic protection filter assembly  710  that illustrates that strut  756 , in addition to being coupled to shaft  14 , could also be coupled to tip  724 . Assembly  710  is essentially the same in form and function as assembly  210  except that proximal portion  728  of tip  724  extends proximally of filter  712  and strut  756  is coupled to proximal portion  728 .  
         [0051]    [0051]FIG. 10 is a partial cross-sectional view of embolic protection filter assembly  710  partially collapsed for retrieval from a body lumen. As sheath  30  is advanced over shaft  14 , it engages strut  756 . This engagement causes strut  756  to shift in position and begin to shift filter  712  from the expanded configuration toward the collapsed configuration. Further advancement of sheath  30  results in further collapsing of filter  712  as shown in FIG. 11 and, eventually, the substantial (and/or complete) containment of filter  712  within sheath  30  (see, for example, FIG. 7).  
         [0052]    Similar to FIGS.  8 - 11 , FIG. 12 illustrates embolic protection filter assembly  310  having more than one strut  356  extending between filter  312  and shaft  14 . Filter  312  is essentially the same as filter  12  and includes distal portion  320  and proximal portion  322 . Struts  356  function essentially the same as struts  256  and, thus, may be used to collapse and/or retrieve filter  312 . It can be appreciated that struts  356  could also be coupled to other parts of assembly  310 .  
         [0053]    [0053]FIG. 13 is a partial cross-sectional view of another example embolic protection filter assembly  810 . Assembly  810  is essentially the same in form and function as other assemblies described herein except that it includes an expandable tip  824 . Expandable tip  824  is configured so that at least a portion thereof can shift between a generally collapsed configuration (as best seen in FIG. 13) and a generally expanded configuration (as best seen in FIGS. 14 and 15). When tip  824  is expanded, filter  812  may become at least partially collapsed and disposed therein. Thus, expandable tip  824  may be used to aid retrieval of filter  812 .  
         [0054]    [0054]FIG. 14 is a partial cross-sectional view of embolic protection filter assembly  810  with tip  824  in a generally expanded configuration and with filter  812  disposed within tip  824 . In order for filter  812  to become disposed within tip  824 , sheath  30 , for example, may be advanced over shaft  14  to a position adjacent filter  812 . Sheath  30  can then be further advanced distally so that it contacts and exerts a force upon filter  812  that is sufficient to slide filter  812  into tip  824 . It can be appreciated that other devices may be used to shift filter  812  so that it becomes disposed within tip  824 . For example, a pusher tube may be advanced over shaft  14  or within sheath  30  may be used. Additionally, filter  812  may included a reinforced pushing surface that is configured to provide structural support at the point of contact between sheath  30  and filter  812 . This surface may be defined by a larger or stronger portion of filter  812 , a subassembly disposed adjacent filter  812 , a part of the filter frame, and the like.  
         [0055]    To assist the shifting of filter  812  between the expanded configuration and the collapsed configuration, tip  824  may include a longitudinal portion  866  and a slidable subassembly  868 . Subassembly  868  is connected to filter  812  and may comprise a tube slidably disposed about longitudinal portion  866 . According to this embodiment, as filter  812  is shifted distally, subassembly  868  shifts distally along longitudinal portion  866  and filter  812  becomes disposed within tip  824 .  
         [0056]    As filter  812  becomes at least partially disposed within tip  824 , sheath  30  may be advanced distally toward tip  824  so that a proximal bent portion  870  thereof becomes disposed within sheath  30  as shown in FIG. 15. In this configuration, filter  812  can be removed from the body lumen by retracting shaft  14  and sheath  30 .  
         [0057]    [0057]FIG. 16 is a partial cross-section view of embolic protection filter assembly  610 . Assembly  610  is essentially the same in form and function as assembly  10  except that shaft  614  is tubular and includes one or more aspiration holes  664 . In at least some embodiments, shaft  614  has an outside diameter that is comparable to typical guidewires. For example, the outside diameter may be about 0.016 inches or less. Generally, when filter  12  is in a position relative to shaft  614  that is appropriate for filtering embolic debris, holes  664  are located near or within filter  12  so that captured embolic debris may be aspirated through shaft  612 .  
         [0058]    [0058]FIG. 17 is a partial cross-sectional view of another example embolic protection filter assembly  910  that is essentially the same in form and function as assembly  610 , except that it includes an expandable tip  924  that functions essentially the same as tip  824 . Similar to what is described above, shaft  914  is tubular and includes one or more aspiration holes  964  that can be used to aspirate embolic debris from filter  912  when a vacuum source is connected to the proximal end of shaft  914 .  
         [0059]    Retrieval of filter  912  may include distally advancing sheath  30  (or another suitable structure) along shaft  914  and exerting force upon filter  912  so that filter  912  becomes at least partially disposed within tip  924  as shown in FIG. 18. The mechanism for shifting filter  912  is essentially the same as what is described above and shown in FIGS.  13 - 15 . For example, tip  924  may include longitudinal portion  966  and subassembly  968  and subassembly may slide distally along longitudinal portion  966 .  
         [0060]    [0060]FIG. 19 is a partial cross-sectional view of embolic protection filter assembly  410 . Assembly  410  and filter  412  are essentially the same in form and function as assembly  10  and filter  12 , respectively, except that filter  412  includes an engageable ring  458 . Engagable ring  458  may be, for example, formed at one end of support member  18  or be connected to a wire or cord disposed about proximal portion  422 . Actuating or “pulling” ring  458  results in the circumference of proximal portion  422  becoming smaller. Thus, ring  458  can be used to at least partially collapse filter  412  for retrieval.  
         [0061]    In some embodiments, ring  458  may be actuated by a pull cord  460 . Pull cord  460  may extend distally through catheter  30  and extend out of distal end  32  thereof. To engage ring  458 , pull cord may include a distal hook  462  adapted and configured to engage ring  458 . According to this embodiment, pull cord  462  can be advanced out of distal end  32  of catheter  30 , become engaged with ring  458 , and be pulled proximally to collapse filter  412 . FIG. 20 illustrates assembly  410  with pull cord  462  engaged with ring  458  and pulled proximally to partially collapse filter  412 .  
         [0062]    [0062]FIG. 21 is a partial cross-sectional view of embolic protection filter assembly  510  having an alternative pull cord  556 . Assembly  510  and filter  512  are essentially the same as assembly  10  and filter  12 , respectively. Pull cord  556  is connected to proximal portion  522  of filter  512  such that pull cord  556  can be pulled in the proximal direction to collapse filter  512 . In some embodiments, pull cord  556  may comprise an extension or be connected to support member  18 . Alternatively, pull cord  556  may be generally disposed about proximal portion  522  so that pulling pull cord  556  tightens or shortens the circumference of proximal portion  522  (and generally the circumference of filter  512 ) so that filter  512  may be retrieved by catheter  30 .  
         [0063]    It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.