Abstract:
Vascular embolic filtering systems, as well as methods for using the same, are provided. In general, the subject invention includes a system comprised of a delivery and retrieval sheath adapted for delivering and retrieving multiple embolic filters, wherein the embolic filters are each operatively coupled to a distal region of a filter wire segment and are deployable within a target vessel.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 11/092,249 filed Mar. 29, 2005, which is a continuation of U.S. application Ser. No. 10/045,628 filed Oct. 19, 2001, now U.S. Pat. No. 6,887,257. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to systems and methods for filtering and removing matter from within the vasculature. More particularly, the invention is directed to the intravascular exchange of intravascular devices useful for capturing emboli generated during interventional procedures, and for thrombectomy and embolectomy procedures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vascular procedures to treat occlusive vascular diseases, such as angioplasty, atherectomy and stent placement, often cause blood clots to form and/or material to dislodge from inside the vessel walls and enter the bloodstream. The dislodged material (e.g., plaque), known as emboli, may be large enough to occlude smaller downstream vessels, potentially blocking blood flow to tissue. Additionally, the blood clots, known as thrombi, may be large enough or grow over time to form a blockage at the interventional site or at another downstream location should the thrombus become released into the bloodstream. 
         [0004]    There are numerous previously known interventional systems and methods that employ a filter mechanism designed to capture material liberated from vessel walls during the treatment or diagnosis of vascular disease. Many of the more recent devices employ radially expandable filters disposed at the distal end of a guide wire. These filters have various configurations, such as mesh or microporous membranes in the form of sleeves, parachutes or baskets attached to the guide wire or other delivery mechanism by means of struts, wires, ribs or frames. The meshes are frequently made of woven or braided fibers or wires made of stainless steel, nitinol, platinum alloy, polyester, nylon or porous plastics, for example. The microporous membranes are typically made of a polymer material such as polypropylene, polyurethane, polyester, polyethylene tetraphlalate, polytetrafluoroethylene or combinations thereof. 
         [0005]    Examples of procedures employing such filters include angioplasty, atherectomy, thrombectomy and stent placement. These procedures typically involve transluminally inserting and delivering within a vessel, a guide wire with an attached filter to a location distal to a lesion or treatment site, and deploying the filter. The interventional device is then delivered over the guide wire to the treatment site. During the treatment of a lesion within the patient&#39;s vessel, plaque is often liberated from the walls of the vessel creating emboli within the bloodstream. These emboli are then captured within the deployed filter, where they remain for the duration of the treatment procedure. 
         [0006]    Depending on the amount of plaque dislodged from the vessel wall, the embolic filter may become occluded with emboli during an interventional procedure, thus preventing blood from flowing through the filter. As a result, a pool forms proximal to the filter. When the filter becomes full or occluded with emboli and debris, the interventional procedure may need to be terminated so that the filter can be removed from the vasculature. As such, the duration of the interventional procedure is dependent upon the emboli-filling capacity of the deployed filter. 
         [0007]    Numerous approaches have been postulated to overcome the increased procedure times associated with the retrieval and subsequent exchange of emboli-laden filters from a patient&#39;s vasculature. For example, one such approach is to employ an aspiration device to aspirate emboli contained within a filter sac of a vascular filter, so as to eliminate the need to retrieve and exchange the filter when it becomes full of emboli. However, there are significant disadvantages associated with this approach, including increased procedural complexity, the need for additional components and the inability to completely aspirate emboli entrapped in the filter pores. 
         [0008]    In view of the description of the foregoing devices and methods, it is desirable to provide an improved embolic filter system. Additionally, it is desirable to have such systems that provide for the rapid exchange of embolic filters during the course of an interventional diagnostic or therapeutic procedure and/or in which a stent is deployed. Further, it is advantageous to have such systems capable of delivering multiple filters and/or interventional devices without losing guide wire access to the target site. In addition, it is desirable that there be a safe withdrawal of the deployed embolic filters from the vasculature. It is also desirable to first insert a guide wire distal the target region, and then subsequently replace the guide wire with a filter wire attached to a filter. Insertion of a guide wire first, and then subsequently replacing the guide wire with a filter and filter wire, enables the clinician to more accurately maneuver the embolic filter across the site of the lesion. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention pertains to embolic protection systems deployed in a body vessel or cavity for the collection of loosened and/or dislodged debris, such as embolic material dislodged during, or thrombi formed as a result of, an interventional procedure. The present invention is particularly helpful to protect the vasculature of a patient from dislodged emboli during interventional procedures such as angioplasty, atherectomy, thrombectomy, embolectomy, intravascular diagnostic and stent placement procedures by enabling rapid exchange of embolic filters during the course of the interventional procedure. 
         [0010]    Vascular embolic filter systems, as well as methods for using the same, are provided. In one particular embodiment, the subject invention includes a system comprised of an embolic filter assembly and a multiple lumen delivery and retrieval sheath, where the embolic filter assembly includes a guide wire with an embolic filter operatively coupled to the guide wire for capturing emboli created during interventional procedures within a target vessel. Features of the subject systems provide for the rapid exchange and deployment of embolic filters in a patient&#39;s vasculature. Rapid exchange of embolic filters during the course of a procedure decreases overall procedure times and minimizes the risks associated with occluded embolic filters. 
         [0011]    Specifically, the rapid exchange of embolic filters is accomplished by sequentially retrieving an occluded filter and deploying a second, unused or unoccluded filter through a single delivery and retrieval sheath having at least two lumens, without having to remove the occluded filter and/or the sheath prior to delivering and deploying the second filter. 
         [0012]    As such, a first embolic filter is deployed to a target site distal to a stenosis such that the first deployed embolic filter creates an opening or mouth through which emboli and debris can flow. Once a first embolic filter is deployed, an interventional device can be advanced to the site of the stenosis and the interventional procedure may commence. Once filled with emboli and debris, the interventional device is removed from the vessel. The multiple lumen delivery and retrieval sheath of the present invention is then advanced over the guide wire in order to retrieve the first embolic filter and to deliver and deploy a second embolic filter. The guide wire with the first embolic filter attached is pulled or retracted into the first lumen of the sheath, or alternatively the sheath is advanced over the guide wire and attached embolic filter, causing the filter opening or mouth to close or collapse. Such withdrawal prevents emboli collected during the procedure from escaping into the patient&#39;s blood. Once the first embolic filter is effectively withdrawn into a lumen of the delivery and retrieval sheath so as to prevent the escape of collected emboli, a second embolic filter can be deployed to the target site through a second lumen of the delivery and retrieval sheath. Again, when filled with emboli and debris, the second deployed embolic filter can also be retrieved by withdrawing it at least partially into a second lumen of the delivery and retrieval sheath in order to sufficiently close or collapse the filter mouth to prevent the escape of emboli from the embolic filter. Additional filters can also be rapidly advanced, deployed and retrieved as described above, in certain embodiments through additional lumens within the multiple lumen delivery and retrieval sheath. 
         [0013]    In another embodiment of the present invention, an interventional device such as an angioplasty catheter, embolectomy device, atherectomy device or the like is advanced to the procedure site through one of the lumens of the multiple lumen delivery and retrieval sheath of the present invention. In certain embodiments, embolic filter exchange and the interventional procedure can occur without the need to remove the sheath from the vasculature between exchanges, thus further reducing procedure times. 
         [0014]    In yet another embodiment of the present invention, a guide wire shaft defining a guide wire lumen is operatively coupled to a filter wire. The guide wire shaft, along with the filter wire, can be advanced along a guide wire to point distal a lesion. Once the guide wire shaft is in place, the guide wire can be removed, and a filter sheath containing a filter assembly disposed about the filter wire can be retracted to deploy an embolic filter within the vessel. Once occluded, the embolic filter can be again collapsed by sliding the filter sheath over the filter assembly, and then withdrawn from the vessel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates an embolic filter suitable for use with the present invention. 
           [0016]      FIG. 2  includes  FIGS. 2A &amp; 2B  which illustrate different embodiments of a delivery and retrieval sheath of the present invention; wherein: 
           [0017]      FIG. 2A  illustrates one embodiment of a delivery and retrieval sheath of the present invention having at least two lumens and having an embolic filter system disposed therein; and 
           [0018]      FIG. 2B  illustrates another embodiment of a delivery and retrieval sheath of the present invention having lumens of differing lengths; 
           [0019]      FIG. 3  includes  FIGS. 3A-F  which illustrate an embolic filter system of the present invention and a method for using same; wherein: 
           [0020]      FIG. 3A  illustrates the multiple lumen delivery and retrieval sheath of  FIG. 2A  with a first embolic filter of the present invention operatively coupled to a first guide wire and disposed in an undeployed, pre-delivery state within a first lumen of the sheath; 
           [0021]      FIG. 3B  illustrates the first embolic filter of  FIG. 3A , now fully deployed inside a vessel at a location distal to a stenotic lesion; 
           [0022]      FIG. 3C  illustrates the first embolic filter of  FIG. 3B , substantially filled with emboli, and the multiple lumen delivery and retrieval sheath of  FIG. 2A  advanced to retrieve the deployed first filter and to deploy a second filter disposed within a second lumen of the multiple lumen delivery and retrieval sheath; 
           [0023]      FIG. 3D  illustrates the retrieval of the first embolic filter into the first lumen of the multiple lumen delivery and retrieval sheath; 
           [0024]      FIG. 3E  illustrates the deployment of the second embolic filter into the vessel with the first embolic filter at least partially withdrawn into the first lumen of the multiple lumen delivery and retrieval sheath; and 
           [0025]      FIG. 3F  illustrates the second embolic filter fully deployed within the vessel at a location distal to the stenotic region. 
           [0026]      FIG. 4  includes  FIGS. 4A-4D  which illustrate a filter exchange system in accordance with an another embodiment of the present invention; wherein: 
           [0027]      FIG. 4A  illustrates a guide wire inserted into a vessel at a location distal to a stenotic region. 
           [0028]      FIG. 4B  illustrates a filter exchange system having a guide wire shaft, a guide wire lumen, a filter and a filter lumen advanced to a distal portion of the guide wire shown in  FIG. 4A ; 
           [0029]      FIG. 4C  illustrates the filter exchange system of  FIG. 4B , wherein the guide wire has been withdrawn; and 
           [0030]      FIG. 4D  illustrates the embolic filter in the filter exchange system of  FIG. 4B  in a fully deployed state at a location distal to the stenotic region. 
           [0031]      FIG. 5  includes  FIGS. 5A-5E  which illustrate a filter exchange system in accordance with yet another embodiment of the present invention; wherein: 
           [0032]      FIG. 5A  illustrates an exchange sheath disposed over a guide wire and having a filter assembly disposed within the sheath; 
           [0033]      FIG. 5B  illustrates the exchange sheath of  FIG. 5A  wherein the guide wire has been withdrawn; 
           [0034]      FIG. 5C  illustrates the filter assembly of  FIG. 5B  wherein the exchange sheath has been withdrawn; 
           [0035]      FIG. 5D  illustrates the advancement of an exchange sheath and guide wire over the filter assembly of  FIG. 5C ; 
           [0036]      FIG. 5E  illustrates the exchange sheath of  FIG. 5D  advanced over the filter assembly of  FIG. 5C . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]    Rapid Exchange Embolic Filter System 
         [0038]    Embolic Filter Assembly 
         [0039]    An embolic filter assembly of the present invention is comprised of an embolic filter operatively coupled to a guide wire. A number of embolic filters are known for providing distal protection against embolization in conjunction with a transluminal diagnostic or therapeutic procedure, such as angioplasty or embolectomy. These embolic filters are deployed distal to a vascular lesion, such as a stenosis, prior to undertaking the diagnostic or therapeutic procedure, and are designed to collect emboli liberated during the procedure to prevent them from entering the blood stream. Generally, embolic filters suitable for use with the present invention are characterized by having a blood permeable sac and a support hoop which forms an opening into the sac; however, other types of filters are also useable with the present invention. 
         [0040]    Referring now to  FIG. 1 , a schematic of an embolic filter assembly suitable for use with the present invention is shown deployed within vessel V distal a lesion. Embolic filter assembly  29  includes embolic filter  30  and guide wire  38 . Embolic filter  30  includes self-expanding support hoop  31 , preferably mounted on suspension strut  32 , which supports blood permeable sac  33 . As such, support hoop  31  forms a mouth or proximal opening of sac  33  while blood permeable sac  33  provides a closed, but permeable distal end  36 . Support hoop  31  is preferably formed of a super-elastic material, such as nitinol, and has a constrictable, preformed shape. Accordingly, support hoop  31  is collapsible to fit into a delivery and retrieval sheath, and then expandable to its preformed shape. Suspension strut  32  is attached to guide wire  38  at joint  34  by means of a solder bead or shrink tubing, for example. 
         [0041]    Blood permeable sac  33  is preferably made of a material having a multiplicity of pores. Suitable materials include, but are not limited to, biocompatible polymeric materials such as polyethylene, polyproylene, polyurethane, polyester, polyethylene tetraphlalate, nylon, polytetrafluoroethylene, or combinations thereof. These pores, in turn, permit red blood cells to pass through the sac substantially unhindered, while capturing and retaining larger emboli and debris that may be released during an interventional procedure. 
         [0042]    As described, blood permeable sac  33  is preferably comprised of a suspension strut  32  or other support means to hold support hoop  31  substantially concentric to guide wire  38 , thereby allowing guide wire  38  to bend and move laterally without lifting support hoop  31  from the wall. Accordingly, suspension strut  32  advantageously permits support hoop  31  to become concentrically displaced relative to guide wire  38  when embolic filter  30  is deployed in a curved vessel. 
         [0043]    Delivery and Retrieval Sheaths 
         [0044]    As indicated above, an embolic filter assembly, e.g., embolic filter  30  operatively coupled to guide wire  38 , is advanced to a target site within a vessel through a delivery and retrieval sheath. The delivery and retrieval sheath of the present invention, in turn, is used to advance, deliver, deploy and retrieve an embolic filter assembly to a target location within a vessel. In one embodiment of the present invention, the delivery and retrieval sheath includes two lumens for rapid delivery and retrieval of filter assemblies. In yet another embodiment of the present invention, the delivery and retrieval sheath includes three or more lumens for deployment and retrieval of additional filter assemblies, interventional therapeutic devices, diagnostic devices and/or stents. Each lumen has a proximal opening, and a distal opening. 
         [0045]    Referring to  FIGS. 2A-B , various embodiments of delivery and retrieval sheaths suitable for use with the present invention will now be described. Delivery and retrieval sheath  40 , shown in  FIG. 2A  includes a proximal end  48 , a distal end  49  and two lumens  50  and  52  having distal openings  42  and  44  respectively. Lumens  50  and  52  share a common wall  46 . In this particular embodiment, the distal ends of lumens  50  and  52  terminate at substantially the same point, i.e., the distal opening  42  of lumen  50  and distal opening  44  of lumen  52  are substantially even. Delivery and retrieval sheath  40  is shown with an embolic filter assembly therein, such as the embolic filter assembly  29  shown in  FIG. 1 . Accordingly, embolic filter  30  is in a folded or constricted or undeployed, pre-delivery state disposed within a first lumen  50  of delivery and retrieval sheath  40 . 
         [0046]      FIG. 2B  shows an alternative embodiment of the delivery and retrieval sheath of  FIG. 2A . In this particular embodiment, the distal end of lumen  50  terminates proximally of the distal end of lumen  52 , such that distal opening  42  of lumen  50  is proximal of distal opening  44  of lumen  52 . This particular embodiment advantageously minimizes the profile of sheath  40 . 
         [0047]    Methods 
         [0048]    Methods of using the embolic filter system of the present invention will now be described in the context of an interventional therapeutic procedure, such as angioplasty, atherectomy, thrombectomy, stent placement or interventional diagnostic procedure, to treat and/or diagnose a lesion within a body lumen. 
         [0049]      FIGS. 3A-3F  illustrate the rapid exchange of embolic filters using an embodiment of the present invention. In practicing the subject invention, a generic guide wire (not shown) is manipulated into position in vessel V using well known percutaneous techniques. Once the generic guide wire is positioned, a multiple lumen delivery and retrieval sheath, such as the multiple lumen delivery and retrieval sheath  40  of  FIG. 2A , may be tracked over the generic guide wire to guide the delivery and retrieval sheath within the vasculature, e.g., lumen  50  may be used to track over the generic guide wire. Once delivery and retrieval sheath  40  is maneuvered into a position within vessel V distal lesion  4 , the generic guide wire may be removed from the vasculature. In certain embodiments, positioning of the delivery and retrieval sheath  40  may be based on the position of a radiopaque marker or the like under fluoroscopy. 
         [0050]    As shown in  FIG. 3A , first embolic filter, such as embolic filter  30  of  FIG. 1 , is disposed within a lumen of delivery and retrieval sheath  40 , for example first lumen  52  of delivery and retrieval sheath  40 , and is operatively coupled to guide wire  38 .  FIG. 3A  shows embolic filter  30  in its constricted, undeployed, pre-delivery state within lumen  52 . Thus, delivery and retrieval sheath  40 , with embolic filter  30  disposed therein, is advanced through the vessel over a generic guide wire to a site distal to lesion  4 . Once delivery and retrieval sheath  40  is at the desired location distal lesion  4 , the generic guide wire can be removed from the vasculature. 
         [0051]    Once the delivery and retrieval sheath  40  is appropriately positioned, guide wire  38  is held stationary while delivery and retrieval sheath  40  is retracted proximally to deploy embolic filter  30 . Alternatively, delivery and retrieval sheath  40  may be held stationary while guide wire  38  is advanced distally. In either case, when embolic filter  30  is liberated from distal opening  42  of lumen  52  and is thus no longer confined to the delivery and retrieval sheath  40 , support hoop  31  is expanded, as illustrated in  FIG. 3B . Subsequent to filter deployment, delivery and retrieval sheath  40  is removed from the vasculature.  FIG. 3B  shows embolic filter  30  in its fully deployed state in vessel V, with support hoop  31  expanded to form an opening or mouth through which emboli and debris can flow into blood permeable sac  33 . 
         [0052]    After deployment of embolic filter  30  and subsequent removal of delivery and retrieval sheath  40 , other interventional instruments, such as angioplasty catheters, atherectomy devices or stent delivery systems may be advanced along guide wire  38  to a position proximal of embolic filter  30 . Thus, embolic filter  30  is positioned to trap emboli generated from the use of the interventional device on the lesion, e.g., pieces of plaque dislodged from the wall of vessel V by the interventional procedure. 
         [0053]    With respect to  FIGS. 3C-3E , the exchange of first embolic filter  30  for a second embolic filter is shown. Accordingly, when first embolic filter  30  becomes full of emboli E, it is removed from the vasculature to prevent injury to the patient. If it is desirous to proceed with the interventional procedure, the first embolic filter may be exchanged for a second embolic filter. As such, the interventional device (not shown) is first removed from the vasculature by tracking it proximally over guide wire  38 . Delivery and retrieval sheath  40  is again advanced over guide wire  38  to a site distal to lesion  4  and proximal to the now occluded first embolic filter  30 . As illustrated in  FIG. 3C , a second embolic filter assembly  64 , including second embolic filter  60 , support hoop  62  and suspension strut  66 , is operatively coupled to guide wire  70  in second lumen  50  of delivery sheath  40  with second embolic filter  60  in a contracted or undeployed, pre-delivery state. 
         [0054]    In  FIG. 3D , once delivery and retrieval sheath  40  containing second embolic filter assembly  64  is advanced to the vicinity of first embolic filter  30 , first embolic filter  30  is at least partially withdrawn proximally into first lumen  52  of delivery sheath  40 . Alternatively, delivery sheath  40  can be advanced distally, at least partially over first embolic filter  30 . In either case, the filter opening or mouth of first embolic filter  30  essentially closes or collapses such that emboli disposed in blood permeable sac  33  of first embolic filter  30  is effectively retained inside the sac  33 . 
         [0055]    Referring now to  FIG. 3E , once first embolic filter  30  is withdrawn at least partially into first lumen  52  to seal the contents therein, guide wire  70  is held stationary while delivery and retrieval sheath  40  with first embolic filter  30  are refracted proximally or, alternatively, delivery and retrieval sheath  40  with first embolic filter  30  may be held stationary while guide wire  70  is advanced distally. In either case, when second embolic filter  60  is liberated from distal opening  44  of second lumen  50  and is thus no longer confined to delivery and retrieval sheath  40 , support hoop  62  is expanded. Once second embolic filter  60  is deployed in vessel V, delivery and retrieval sheath  40  along with first embolic filter  30  are removed from the vasculature.  FIG. 3F  shows second embolic filter  60  in its fully deployed state in vessel V, with support hoop  62  expanded to form an opening or mouth through which emboli and debris can flow into blood permeable sac  64 . As such, an interventional device can be again guided to lesion  4  to continue the interventional procedure. 
         [0056]    In certain embodiments, more than two embolic filters may be advanced, deployed and retrieved through multiple lumen delivery and retrieval sheath  40 . As such, these additional embolic filters may be advanced, deployed and retrieved through additional lumens of a multiple lumen delivery and retrieval sheath. For example, a third embolic filter may be advanced, deployed and retrieved through a multiple lumen delivery and retrieval sheath defining three lumens. Alternatively, the additional filters may be advanced, deployed and retrieved through the same lumen as that which was used to advance, deploy and retrieve the first embolic filter. For example, a third embolic filter may be advanced, deployed and retrieved through first lumen  52  of multiple lumen delivery and retrieval sheaths  40  or  130  after the first embolic filter  30  has been withdrawn and removed therefrom. In either case, additional embolic filters may be advanced, deployed and removed as described above. 
         [0057]    Exchange Sheaths 
         [0058]      FIGS. 4A-4D  illustrate a filter exchange system in accordance with a particular embodiment of the present invention. As shown in  FIG. 4A , a guide wire  104  is inserted into vessel V and extends distally of a lesion  4 . Guide wire  102  has a proximal end  170 , a distal end  168 , and a distal tip region  104 . 
         [0059]    As illustrated in  FIG. 4B , a guide tip  150  defining a guide wire lumen  168  is advanced to a distal end  168  of guide wire  102 . Guide tip  150  has a tapered profile, with a larger diameter portion on proximal end  152 , and a smaller diameter portion on distal end  151 . Guide tip  150  can be made from, for example, a relatively soft atraumatic polymer or a radiopaque coil. A filter sheath  154  defines a filter lumen  172  containing a filter assembly  174  therein. Disposed in part within filter lumen  172  is a filter wire  138  having a proximal end and a distal end  156 . Distal end  156  of filter wire  138 , in turn, is attached to the proximal end of guide tip  150  at flange  176 . Filter wire  138  can be attached to guide tip  150  at flange  176  by, for example, molding tip  150  over flange  176 . Alternatively, filter wire  138  can be attached to guide wire shaft  150  by means of a shrink-fit, adhesive, interference fit or other means. 
         [0060]    In use, guide tip  150 , operatively coupled to filter sheath  154  and filter assembly  174 , can be advanced over guide wire  102  to a point within the vessel V distal lesion  4 . As shown in  FIG. 4B , embolic filter  133  is housed within filter lumen  172  in its un-deployed, collapsed state. Once filter assembly  174  is advanced distally of lesion  4  to a desired location within vessel V, guide wire  102  can be removed from guide tip  150 , as illustrated in  FIG. 4C . When filter assembly  174  is appropriately positioned, filter wire  138  is held stationary while filter sheath  154  is retracted proximally, allowing embolic filter  133  to deploy in the vessel. Alternatively, filter sheath  154  can be held stationary while filter wire  138  is advanced distally. In either case, when embolic filter  133  is removed from filter sheath  154  and thus no longer confined within filter lumen  172 , embolic filter  133  can be fully deployed. 
         [0061]      FIG. 4D  illustrates filter assembly  158  in a deployed state after the removal of filter sheath  154 . As shown in  FIG. 4D , filter assembly  158  having an embolic filter  133 , support hoop  136 , suspension strut  162  and filter sac  180  is shown fully deployed at a point distal lesion  4 . Suspension strut  162  is connected to support hoop  136  at its distal end, and to joint  140  at its proximal end. The proximal end of suspension strut  162  is attached to filter wire  138  by means of a solder bead or other attachment means. Alternatively, joint  140  can be a tube to allow rotation of guidewire  138 . When the therapeutic procedure is completed, filter  133  can be retracted back into filter sheath  154  or other retrieval catheter and removed from the vessel. Alternatively, filter assembly  158  can be retracted back into filter sheath  154 , or other retrieval catheter, by pulling filter guide wire  138  proximally until embolic filter  133  is encased in part with filter lumen  172 . Although the filter assembly shown in  FIGS. 4A-D  is similar to the filter assembly discussed infra in  FIG. 1 , other embolic filters can be employed by the filter exchange system of  FIGS. 4A-4D  without departing from the scope of the subject invention. 
         [0062]      FIG. 5A  is an alternative embodiment of an exchange sheath in accordance with the present invention. As illustrated in  FIG. 5A , filter assembly  30  is disposed along a filter guide wire  38  in an exchange sheath  100 . Sheath  100  has a proximal end (not shown) and a distal end. Exchange sheath  100  further includes a filter sheath  106  defining a filter lumen. Filter sheath  106  includes a shaft  108  and a larger diameter portion  110  at the distal end of shaft  108 . Larger diameter portion  110  at least in part contains filter  30  when filter guide wire  38  is disposed within the lumen of filter sheath  106 . 
         [0063]    Exchange sheath  100  also includes a guide wire sheath  112 . As shown in  FIG. 5A , guide wire sheath  112  can be substantially shorter than exchange sheath  100 . Guide wire sheath  112  includes a guide wire lumen therethrough. In one advantageous embodiment, guide wire lumen  112  is discontinuous, and includes a skived portion  114  adjacent the larger diameter portion  110  of filter sheath  106 . This can be done to reduce the profile of exchange sheath  100  at larger diameter portion  110 . Moreover, a guide wire  102  having a distal spring tip  104  can be disposed within the guide wire lumen of sheath  112 . Once the exchange sheath  100  containing collapsed and un-deployed embolic filter  30  is advanced along guide wire  102  to a portion of the vessel distal lesion  4 , guide wire  102  can be removed from the vessel. Alternatively, embolic filter  30  can be first advanced along filter wire  38  distally until it is fully deployed within the vessel, at which point guide wire  102  can be removed from the vessel. 
         [0064]      FIG. 5B  illustrates the exchange sheath  100  in  FIG. 5A  subsequent to removal of the guide wire  102  from vessel V, but prior to deployment of embolic filter  30 . As shown in  FIG. 5B , once filter containing region  110  and filter  30  have been advanced distally of the lesion, and once guide wire  102  is withdrawn from the vessel, embolic filter  30  can be deployed within the vessel by either holding the filter wire  38  static and sliding shaft  108  proximally, or alternatively, by holding shaft  108  static and sliding the filter wire  38  distally. Once filter assembly  29  is disposed in vessel V, as shown in  FIG. 5C , various devices such as angioplasty catheters or atherectomy catheters can be advanced over filter wire  38  to lesion  4 . 
         [0065]    During angioplasty, atherectomy or other procedures, emboli can break free from lesion  4  and drift into filter sac  33 . Emboli might eventually substantially fill filter sac  33 , in whole or in part occluding vessel V. Embolic filter  30  can then be removed from vessel V by first removing the angioplasty catheter, atherectomy catheter or other device. Then, as shown in  FIG. 5D , exchange sheath  100  and guide wire  102  can be advanced over filter wire  38 . Filter  30  can then at least in part be collapsed and withdrawn from vessel V by drawing said filter into filter sheath  106 , or advancing exchange sheath  100  including filter sheath  106  at least in part over embolic filter  30 . Once filter  30  is at least in part in exchange sheath  100 , filter assembly  29  and exchange sheath  100  can be removed proximally from vessel V over guide wire  102 . Guide wire  102  is then left in place across the lesion. Another filter assembly  29  can then be placed in vessel V by repeating the steps described above beginning with  FIG. 5A . 
         [0066]    Kits 
         [0067]    Also provided by the subject invention are kits for use in practicing the subject methods. A kit of the subject invention includes at least one embolic filter assembly and at least one multiple lumen delivery and retrieval sheath, as described above. Other kits may include one or more embolic filter assemblies without the accompanying multiple lumen delivery and retrieval sheath. Certain kits may include one or more vascular interventional systems, such as an angioplasty system, a stent placement system, an atherectomy system, an embolectomy system and a diagnostic system in addition to a subject embolic filter assembly and/or multiple lumen delivery and retrieval sheath. Finally, the subject kits preferably include instructions for using the subject device(s) and system(s) during an interventional procedure to protect the patient against emboli. These instructions may be present in one or more of the instructions for use included in the kits, packaging, label inserts or containers present in the kits, and the like. 
         [0068]    It is evident from the above description that the subject inventions provide a significant contribution to the field of embolic protection. It is recognized that departures from the described embodiments may be made which are within the scope of the invention, and that obvious modifications will occur to one skilled in the art upon reading this disclosure. Such departures and modifications that come within the meaning and range of equivalents of the disclosed concepts are intended to be included within the scope of the appended claims.