Abstract:
A removable vascular filter system for capture and retrieval of emboli while allowing continuous perfusion of blood, comprising a porous filter membrane and a filter membrane support structure. This system is useful for any percutaneous angioplasty, stenting, thrombolysis or tissue ablation procedure. The system may minimize the incidence of stroke, myocardial infarction or other clinical complications that may be associated with these procedures.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This patent application is a continuation of pending U.S. patent application Ser. No. 10/045,296, filed Nov. 7, 2001, which is a continuation-in-part of pending U.S. patent application Ser. No. 09/249,377, filed Feb. 12, 1999. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    I. Field of the Invention  
           [0003]    The present invention relates to the treatment of vascular disease by either percutaneous angioplasty and stenting or surgery. More particularly, the present invention relates to a system that reduces macro- and micro-embolization during the treatment of vascular disease.  
           [0004]    II. Discussion of the Related Art  
           [0005]    A variety of surgical and non-surgical angioplasty procedures have been developed for removing obstructions from blood vessels. Balloon angioplasty utilizes a balloon-tipped catheter which may be inserted within a stenosed region of the blood vessel. By inflation of the balloon, the stenosed region is dilated. Stenting involves the permanent implantation of a metallic scaffold in the area of the obstruction, following balloon dilatation. The stent is often delivered on an angioplasty balloon, and is deployed when the balloon is inflated. Another alternative is the local delivery of medication via an infusion catheter. Other techniques, such as atherectomy, have also been proposed. In atherectomy, a rotating blade is used to shave plaque from an arterial wall. Finally, other techniques, such as tissue ablation, are sometimes performed to address electrical anomalies in heart rhythm. Surgery involves either removing the plaque from the artery or attaching a graft to the artery so as to bypass the obstructing plaque.  
           [0006]    One problem common to all of these techniques is the accidental release of portions of the plaque or thrombus, resulting in emboli which can lodge elsewhere in the vascular system. Such emboli may be dangerous to the patient, and may cause severe impairment of the distal circulatory bed. Depending upon the vessel being treated, this may result in a stroke or myocardial infarction or limb ischemia.  
           [0007]    Vascular filters or embolism traps for implantation into the vena cava of a patient are well known, being illustrated by, for example, U.S. Pat. Nos. 4,727,873 and 4,688,533. Additionally, there is a substantial amount of medical literature describing various designs of vascular filters and reporting the results of the clinical and experimented use thereof. See, for example, the article by Eichelter &amp; Schenk entitled “Prophylaxis of Pulmonary Embolism,” Archives of Surgery, Vol. 97, August 1968, pp. 348 et seq. See, also, the article by Greenfiled, et al., entitled “A New Intracaval Filter Permitting Continued Flow and Resolution of Emboli”, Surgery, Vol. 73, No. 4, pp. 599-606 (1973).  
           [0008]    Vascular filters are used, often during a postoperative period, when there is a perceived risk of a patient encountering a pulmonary embolus resulting from clots generated at the surgical site. Typically, the filter is mounted in the vena cava to catch large emboli passing from the surgical site to the lungs.  
           [0009]    The vascular filters of the prior art are usually permanently implanted in the venous system of the patient, so that even after the need for the filter has abated, the filter remains in place for the lifetime of the patient, absent surgical removal. U.S. Pat. No. 3,952,747 describes a stainless steel filtering device which is permanently implanted transvenously within the inferior vena cava. The filtering device is intended to treat recurrent pulmonary embolism. U.S. Pat. No. 4,873,978 describes a catheter device comprising a catheter body having a strainer mounted at its distal end. The strainer is shiftable between an opened configuration where it extends substantially across the blood vessel to entrap passing emboli, and a closed configuration where it retains the captured emboli during removal of the catheter. A mechanism actuable at the proximate end of the catheter body allows selective opening and closing of the strainer. Typically, the strainer is a collapsible cone having an apex attached to a wire running from the distal end to the proximate end of the catheter body.  
           [0010]    Permanent implantation may be deemed medially undesirable, but it has been done because vascular filters are implanted in patients primarily in response to potentially life threatening situations. Accordingly, the potential disadvantages of permanent implantations of a vascular filter are often accepted.  
           [0011]    Notwithstanding the usefulness of the above-described methods, a need still exists for an apparatus and method for preventing embolization associated with conventional surgery and interventional procedures. In particular, it would be desirable to provide a device which could be located within the vascular system to collect and retrieve portions of plaque and thrombus which have dislodged during the surgery or angioplasty procedure.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention provides a vascular filter system useful in the surgical or interventional treatment of vascular disease. Macro- and micro-embolization may occur during percutaneous procedures such as angioplasty, which potentially increases the risk of a minor or major stroke. The system of the present invention for reducing macro- and micro-embolization is very useful in helping to prevent the risk of stroke. However, this system would also be useful in any percutaneous angioplasty, stenting, thrombolysis or tissue ablation procedure, or surgical procedure where embolization is a risk. The vascular filter system of the present invention may decrease embolism while allowing brain, or other distal tissue, perfusion. The filters may be incorporated into a guidewire which is used for the entire procedure from crossing a lesion to deploying a stent.  
           [0013]    An objective of the present invention is to provide a vascular filter system for reducing macro- and micro-embolization. Another objective of the present invention is to provide a vascular filter system which is readily removable from the vascular system, or elsewhere, of a patient when the filter is no longer needed. It is a further objective of the present invention to provide a vascular filter system having a configuration which does not require hooks to penetrate and grip the blood vessel walls, so that the implantation results in less blood vessel injury. It is yet a further objective of the present invention to provide a vascular filter system of very low profile which is part of a guidewire and may be used in small vessels. It is yet a further objective of the invention to provide a vascular filter system for angioplasty, stenting, thrombolysis and/or electrophysiologic or other ablative procedures.  
           [0014]    In one exemplary embodiment the filter comprises a thin membrane attached to the guidewire and supported by fine metal spines. Attachment of the filter membrane to the guidewire allows expansion of the filter membrane with a firm fit inside the artery. The attachment also allows for collapse of the filter membrane at the end of the procedure so it fits tightly against the guidewire and can be withdrawn through the guide catheter. In another exemplary embodiment, the filter membrane rests upon or is attached to a basket-like structure, at least one end of which is attached to the guidewire. The filter membrane has a pore size such that blood flow is not impeded when the filter membrane is expanded but micro- and macro-emboli are blocked. Expansion of the filter membrane is aided by the forward flow of blood against the filter. The filter design results in a very low profile so that the initial crossing of the lesion is minimally traumatic. Also, the small diameter and small profile facilitate use of the device in small or larger arteries with minimal or no obstruction of blood flow.  
           [0015]    In another exemplary embodiment of the present invention, a dilatation balloon delivery system incorporating a vascular filter may be useful to capture thrombus or emboli generated during a cardiovascular procedure. The dilatation balloon delivery system comprises a balloon catheter having proximal and distal ends, the proximal end comprising a hub having ports. The distal end comprises an inflatable balloon having a distal end, where a guidewire lumen extends from the distal end of the balloon to one of the ports in the hub. The guidewire also extends distally to a vascular filter system. A sheath is arranged concentric to the balloon catheter, where the distal end of the sheath covers the inflatable balloon and the guidewire filter. The sheath proximal end extends to a point distal to the hub. The dilatation balloon delivery system may be an over-the-wire system, as described, or a rapid exchange system.  
           [0016]    In another exemplary embodiment of the present invention, a stent delivery system incorporating a vascular filter may be useful to capture thrombus or emboli generated during a cardiovascular procedure. The stent delivery system comprises a balloon catheter having proximal and distal ends, the proximal end comprising a hub having ports. The distal end comprises an inflatable balloon having a distal end, where a guidewire lumen extends from the distal end of the balloon to one of the ports in the hub. The guidewire lumen also extends proximally to a vascular filter system. An expandable stent is positioned annularly around the balloon. A sheath is arranged concentric to the balloon catheter, where the distal end of the sheath covers the inflatable balloon, the stent, and the guidewire filter. The sheath proximal end extends to a point distal to the hub. The stent delivery system may be an over-the-wire system, as described, or a rapid exchange system.  
           [0017]    In another exemplary embodiment of the present invention, the vascular filter is attached to a guidewire having an infusion catheter with infusion holes for controlled delivery and distribution of medication to the area of surgical intervention. The sheath over the guidewire may control the area of distribution of the medication by controlling the number of the revealed infusion holes in the infusion catheter. A locking mechanism on the proximal end of the apparatus may assure that the sheath does not reveal a larger than necessary area of the angioplasty, i.e., thrombus, to be exposed to the infusion holes.  
           [0018]    In another exemplary embodiment of the present invention, a vascular filter system may be used to capture thrombus or emboli generated during electrophysiology or another ablative procedure. A guidewire-based collapsible filter basket can be advanced through the femoral artery to a position adjacent the left ventricle. The basket faces the ventricle, and then the basket is collapsed and withdrawn proximally. Alternately, a guiding catheter has a distally-extending filter membrane that may be collapsed, for example, by sliding an outer sheath distally.  
           [0019]    An advantage of the present invention is that it provides the benefits of filtration and capture of embolic particulates, temporarily, during a variety of clinical procedures.  
           [0020]    Given the following enabling description of the drawings, the apparatus should become evident to a person of ordinary skill in the art. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which the reference characters refer to like parts throughout, and in which:  
         [0022]    [0022]FIG. 1 illustrates a lateral, partial cross-sectional view of one exemplary embodiment of the present invention with the filter membrane in an open position.  
         [0023]    [0023]FIG. 2 illustrates a lateral, partial cross-sectional view of the exemplary embodiment of the present invention in FIG. 1 with the sheath closed.  
         [0024]    [0024]FIG. 3 illustrates a schematic representation of a portion of a filter membrane in accordance with the present invention.  
         [0025]    [0025]FIG. 4 illustrates a lateral view of a core wire in accordance with the present invention.  
         [0026]    [0026]FIG. 5 illustrates a cross-sectional view across section line  5 - 5  of a portion of the core wire of FIG. 4.  
         [0027]    [0027]FIG. 6 illustrates a lateral, cross-sectional view of an alternate basket structure for the exemplary embodiment of FIG. 1.  
         [0028]    [0028]FIG. 7 illustrates a lateral, partial cross-sectional view of another exemplary embodiment of the present invention.  
         [0029]    [0029]FIG. 8 illustrates a lateral, partial cross-sectional view of a further exemplary embodiment of the present invention.  
         [0030]    [0030]FIG. 9 illustrates a schematic, partial cross-sectional view of another exemplary embodiment of the present invention where the distal section of the filter basket is inverted.  
         [0031]    [0031]FIG. 10 illustrates a schematic, partial cross-sectional view of the exemplary embodiment shown in FIG. 9 where the filter basket is collapsed.  
         [0032]    [0032]FIG. 11 illustrates a lateral, partial cross-sectional view of one exemplary embodiment of the invention with the filter membrane in an open position and guidewire having infusion holes.  
         [0033]    [0033]FIG. 12 illustrates a schematic, partial cross-sectional view, with an enlarged section (FIG. 12A), of an exemplary embodiment of the present invention wherein a dilatation delivery system comprises a vascular filter  
         [0034]    [0034]FIG. 13 illustrates a schematic, partial cross-sectional view, with an enlarged section (FIG. 13A), of an exemplary embodiment of the present invention wherein a stent delivery system comprises a vascular filter.  
         [0035]    [0035]FIG. 14 illustrates a schematic, partial cross-sectional view, with an enlarged section (FIG. 14A), of an electrophysiology filter system according to the present invention.  
         [0036]    [0036]FIG. 15 illustrates a schematic, partial cross-sectional view of a filter apparatus in accordance with the present invention.  
         [0037]    [0037]FIG. 16 illustrates a schematic, partial cross-sectional view, with an enlarged section (FIG. 16A), of a guide catheter filter system according to the present invention.  
         [0038]    [0038]FIG. 17 illustrates a partial view of an ablation catheter in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    The present invention relates to a vascular filter system for use in percutaneous angioplasty and stenting and provides for the prevention of distal embolism during endovascular procedures. Further, the filter system of the present invention allows for distal perfusion while preventing embolization.  
         [0040]    The system comprises a thin, perforated filter membrane which is capable of blocking emboli and which is attached to the distal end of a guidewire. In one exemplary embodiment of the invention, a thin, flexible, perforated membrane is supported by four or more supports that form a distally extending basket. At least one end of the basket is attached to the guidewire, and the other, slidable end may be moved to cause the membrane to open or close.  
         [0041]    The present invention can perhaps be better appreciated by reference to the drawings. FIG. 1 illustrates a lateral, cross-sectional view of a distal end of a guidewire  160  with a filter membrane  170  attached thereto. FIG. 1 illustrates guidewire  160  with a shapeable soft “floppy” tip  162  at its extreme distal end which provides flexibility and maneuverability to guidewire  160 . The filter membrane in FIG. 1 is illustrated in an open position.  
         [0042]    Guidewire  160  comprises a core wire  164 , which extends into floppy tip  162 , and a sheath  166 . Filter membrane  170  is supported by a basket  169  comprising two or more filter basket wires  168 , having distal ends  172  and proximal ends  174 . The distal ends  172  of basket wires  168  are fixedly attached by distal radiopaque marker or crimp band  176  to core wire  164 , and the proximal ends  174  of basket wires  168  are attached to proximal radiopaque marker or crimp band  178 , which is slidable over core wire  164 , optionally with a polymeric, such as polyimide, or metallic sleeve between core wire  164  and proximal ends  174 . Preferably, proximal marker  178  is fixedly attached to core wire  164 , and distal marker  176 , with a polymeric or metallic sleeve, is slidable over core wire  164 .  
         [0043]    The flow of blood in FIG. 1 is toward the distal end of guidewire  160 . As such, the force of the flow of blood pushes on deployed filter membrane  170  and helps to maintain filter membrane  170  in the deployed position.  
         [0044]    A sheath member  180  is attached to the distal end of sheath  166 , sheath member  180  having a lumen  182  with a diameter and length sufficient to receive or slide over proximal marker  178 . Sheath  166  and sheath member  180  may be either separate pieces bonded together or a continuous, integral structure. Sheath  166  and sheath member  180  are each made from low friction polymeric material, preferably polytetrafluoroethylene, polyethylene, nylon, or polyurethane.  
         [0045]    Filter membrane  170  may comprise a number of different non-metallic permeable membranes having sufficient porosity to facilitate blood flow but having sufficiently small openings to capture emboli. Filter membrane  170  is preferably affixed at least at its distal portion  184  to core wire  164  and/or basket wire distal ends  172  and, optionally, to basket wires  168 . The remainder of filter membrane  170  may be unattached or, preferably, attached to basket wires  168 , such as by a suitable adhesive. Preferably basket wires  168  are encapsulated in membrane  170 .  
         [0046]    Basket  169  may be somewhat cylindrical in its middle with tapered, conical, proximal and distal portions. Alternately, basket  169  may be slightly spherical, optionally with a flat, cylindrical middle portion. Preferably basket  169  is from about five to about forty mm in length and from about two to about thirty mm, or from about two to about twenty mm, in diameter at its widest.  
         [0047]    The proximal end of the sheath  166  is attached to control handle or guidewire torquer  186 . Control handle  186  has an opening  188  for core wire  164  so that sheath  166  can move slidably over core wire  164 . For example, when sheath  166  is moved distally toward basket wires  168 , filter membrane  170  collapses. Also, there may be instances where sheath  166  will be removed proximally so that other catheters or cardiovascular appliances can be introduced over core wire  164 . Control handle  186 , which functions as a torque device, also primarily functions to lock sheath  166  to core wire  164  during insertion.  
         [0048]    There are a number of known, commercially available guidewire torquers that may be modified to function as control handle  186 . Modification includes, but is not limited to, providing a slightly larger central lumen.  
         [0049]    In FIG. 2 sheath  166  and sheath member  180  are shown advanced distally so that basket wires  168  and filter member  170  are collapsed against core wire  164 . The distal end  192  of sheath member  180  may optionally be slightly tapered to provide a better profile for insertion.  
         [0050]    In an exemplary embodiment of the present invention, as shown in FIG. 3, filter membrane  170  comprises a polymeric material such as polyurethane or silicone elastomer that has laser-drilled holes  190 . Alternately, the filter membrane  170  may comprise fabric or non-fabric meshes, such as those used in known hemodialysis filters or heart-lung bypass machine filters. Suitable materials include polymers or physiologically acceptable metals or alloys.  
         [0051]    Such holes  190 , a pattern for which can be seen in FIG. 3, are preferably only on the conical portion of filter membrane  170 . The holes  190  could be from about twenty to about three hundred microns in diameter. The vertical row separation of holes  190  may be from about 1.2 to 1.4 times the hole diameter and the center-to-center diameter of holes  190  may be from about 1.4 to 1.6 times the hole diameter, or in an exemplary embodiment the vertical and horizontal spacing of the holes is such that the center-to-center spacing of the holes is from about 1.2 to 2.0 times the hole diameter. Preferably the open area of the holes represents from about ten to fifty percent, more preferably from about ten to forty percent of the filter surface. Alternatively, the hole size may be variable. The mesh should have pores of a size sufficient to block and capture any micro- and macro-emboli which may flow downstream from the site where the stenosis is being treated, but large enough such that blood flow is not impeded. The mesh used in the filter device of the invention may have a pore size of from about twenty to about three hundred microns, preferably from about fifty to about one hundred fifty microns. Moreover, the size of filter membrane  170  is such as to allow a firm fit between filter membrane  170  and an artery wall (not shown). The diameter of filter membrane  170  will be directly related to the artery being treated, with typical diameters ranging from about two mm to about forty mm, most preferably from about two mm to about twenty mm.  
         [0052]    Basket wires  168 , illustrated in FIGS. 1 and 2, may comprise a suitable, physiologically acceptable metal. Stainless steel or nitinol are preferred, although titanium or other metal alloys could be used.  
         [0053]    Core wire  164  can be seen better in FIG. 4, where the proximal and middle portions  200  and  202  are substantially uniform in diameter, and then the distal portion  204  tapers to an end point  206 . In fact, distal portion  204  could taper uniformly or, more preferably, non-uniformly, as shown in FIG. 4. Typically core wire  164  is from about two hundred fifty to three hundred cm in length, with an initial diameter of from about 0.009 to 0.038 inches, preferably from about 0.014 to 0.018 inches. Distal section  204  is typically from about eight to ten cm. With a diameter that tapers to from about 0.001 to 0.005inches, core wire  164  may optionally have a thin polymeric coating  207  for friction reduction. Preferably end point  206  is a solid, squat cylinder, as shown in FIGS. 4 and 5.  
         [0054]    Floppy tip  162 , as illustrated in FIG. 1, preferably comprises a radiopaque helical spring  210  that is fixedly attached, e.g., by welding, brazing, or soldering, to end point  206  and, optionally, attachment point  208 . Optionally spring coil  210  may have a polymeric or lubricious coating  212 .  
         [0055]    [0055]FIG. 6 represents an alternate design of the vascular filter system wherein where basket wires  220  are substantially helical in shape. Filter member  222  covers or encompasses the distal portion of basket wires  220 , and the proximal and distal portions of basket wires  220  are secured by proximal radiopaque marker or crimp band  224  and distal radiopaque marker or crimp band  226 , respectively. Markers  224  and  226  are fixed or slidable on core wire  228  as described above. Preferably there are from four to eight basket wires  220 , each with a rotation of from about forty-five degrees to three hundred sixty degrees.  
         [0056]    Additional exemplary embodiments of the present invention can be seen in FIGS. 7 and 8. The schematic representation in FIG. 7 depicts a filter membrane  280  supported by strut wires  282 . The distal ends  284  of strut wires  282  are attached to the distal portion of a tubular member  286 . A movable core wire  290  extends through a lumen  292  in tubular member  286  to a distal floppy section  294 , where a helical spring coil  296  surrounds the distal portion  298  of core wire  290  and is attached to end point  300 . There is an attachment point  302  of weld or solder at the proximal portion of spring coil  296  where the distal portion  304  of sheath member  306  is also attached to core wire  290 . The lumen  308  of sheath member  306  is large enough so that as core wire  290  is pulled proximally, or tubular member  286  is advanced distally, the distal ends  284  of strut wires  282  move into lumen  308  and collapse filter membrane  280 .  
         [0057]    Moveable core wire  250  of the structure shown in FIG. 8 comprises a floppy tip  252  where a helical spring coil  254  encompasses the distal portion  256  of core wire  250 . A basket wire structure component of two or more basket wires  258  supports a filter membrane  260  on the distal portion  262  of the basket structure. Distal ends  264  of the basket wires  258  are encompassed by a radiopaque marker or crimp band  266  that is attached to core wire  250  and/or spring coil  254 . The proximal ends  268  of basket wires  258  are attached to the distal portion of a sheath  270  that surrounds core wire  250 . Sheath  270  moves slidably over core wire  250  so that when sheath  270  is pulled proximally into core wire  250 , filter membrane  250  collapses.  
         [0058]    In FIG. 9, a basket  320  comprising from four to eight strut wires  322  is secured by a distal fixed grommet  324  and a proximal slidable grommet  326 . Grommet  326  is slidable over core wire  328 . Filter membrane  330  is attached to or arranged upon basket  320 , with the proximal section  332  of the membrane  330  being open to flow, represented by arrows  334 . The distal portion  336  of membrane  330  forms a conical shape  340  that extends proximally. The filter could be deployed by, for example, a sheath or a tube fixed to the proximal slidable crimp band  326 . This design is optimized for perfusion and emboli collection. For example, as more emboli is collected, it tends to collect in outer, non-filter areas, leaving the pores open for perfusion.  
         [0059]    Membrane  330  preferably has holes only in distal section  336 / 340 , which holes are arranged as described above. It is believed that under normal, substantially laminar flow conditions debris or emboli  342  will tend to collect in annular recesses  344 .  
         [0060]    To close and capture emboli, as shown in FIG. 10, slidable grommet  326  is moved proximally to collapse basket  320  and membrane  330 . This can be accomplished with, for example, sheath  350  or a fixed tubular member or other apparatus that is preferably slidable over the core wire.  
         [0061]    In another exemplary embodiment of the present invention, shown in FIG. 11, a guidewire or rigid infusion tubing  360  extends over a core wire  362  that extends to a floppy tip  364 , and a filter membrane  366  is supported by a filter basket  368 . Tubing  360  extends proximally to hub  372 . Core wire  362  extends through a lumen in tubing  360  and proximal to hub  372 . Hub  372  has a Luer fitting  374 . Filter membrane  366  supported by filter basket  368  comprises two or more filter basket wires  376 , having distal ends  378  and proximal ends  380  attached to core wire  362  and operating in a manner described above in conjunction with the description of FIGS.  1 - 3 .  
         [0062]    The rigid infusion tubing  360  may have infusion holes  370  for delivering and distributing medication therethrough as well as through the infusion tubing end  382  to an afflicted target area of a procedure such as a peripheral thrombolysis.  
         [0063]    A sheath  390  is connected to the sheath member  392  at its distal end and, optionally with a distal sheath marker  394 , and to a locking hub  405  of a locking mechanism  404  at its proximal end. The sheath locking mechanism comprises a locking hub  405  and a latch  406  which is allowed to slide independently over the infusion tubing  360 . Sheath  390  may be moved distally and proximally along the infusion tubing  360  and locked in place to prevent any further movement along the infusion tubing  360 . By sliding sheath  390  distally and proximally along the infusion tubing  360 , a specific number of the infusion holes  370  may be covered or opened. This covering and uncovering of infusion holes  370  thereby controls the distribution and the amount of medication along the specific area of operation, i.e., the location of the exposed infusion holes  370  relative to a thrombus  396  (or atheroma, stenosis, embolism, plaque, etc.). Infusion holes  370  may be covered and opened alternatively by distally and proximally sliding either only the infusion tubing  360  along core wire  362 , distally and proximally sliding only sheath  390  along the infusion tubing  360 , or manipulating both the infusion tubing  360  along the core wire  362  and the sheath  390  along the infusion tubing  360  simultaneously.  
         [0064]    Sheath  390 , sheath member  392  and locking hub  405  may be either separate pieces bonded together or a continuous, integral structure. Latch  406  is a separate piece of tubing of the same diameter as sheath  390  slidable distally and proximally along the infusion tubing  360 . However, in counterdistinction of sheath  390 , latch  406  has a tight fit over the infusion tubing  360 , enabling sheath  390  to be secured in a secured position when locking mechanism  404  is engaged or locked.  
         [0065]    The wires, membrane, and other materials of this exemplary embodiment are consistent with those described above.  
         [0066]    In another exemplary embodiment of the invention shown in FIG. 12 and FIG. 12A, a dilatation balloon delivery system  561  comprises a deployment sheath  562  and a hub  564 . A balloon shaft  566  extends from hub  564  to the distal section  568  of deployment sheath  562 , where the distal portion of balloon shaft  566  comprises an inflatable dilatation balloon  571 . The interior  572  of balloon  571  is in fluid communication with inflation lumen  574  in balloon shaft  566  and an inflation port  576  in hub  564 . Balloon shaft  566  also comprises a guidewire lumen  578  in fluid communication with a guidewire port  580  in hub  564  and extending through balloon  571  to a vascular filter or emboli capture device  582 , as described above. The ends of a filter basket  584  are secured in a fixed grommet  586  and a slidable grommet  588 .  
         [0067]    During insertion of the dilatation balloon delivery system according to the present invention, deployment sheath  562  is advanced through a patient&#39;s vascular system to a desired location. During this stage of the procedure balloon  571  is collapsed, and vascular filter  582  is somewhat compressed. After balloon  571  is in position, deployment sheath  562  is pulled in the proximal direction, and then balloon  571  is expanded to dilate a vessel. Vascular filter  582  expands as grommet  588  slides in the proximal direction.  
         [0068]    Once the dilatation balloon  571  is collapsed, sheath  562  may be advanced distally to collapse vascular filter  582 . After vascular filter  582  is collapsed, sheath  562 , collapsed balloon  571 , and collapsed vascular filter  582  may be withdrawn together in the proximal direction.  
         [0069]    In another exemplary embodiment of the invention shown in FIG. 13 and FIG. 13A, a stent delivery system  560  comprises a deployment sheath  562  and a hub  564 . A balloon shaft  566  extends from hub  564  to the distal section  568  of deployment sheath  562 , where the distal portion of inflatable balloon catheter shaft  566  comprises an expandable balloon  570 . The interior  572  of balloon  570  is in fluid communication with an inflation lumen  574  in balloon catheter shaft  566  and an inflation port  576  in hub  564 . Balloon shaft  566  also comprises a guidewire lumen  578  in fluid communication with a guidewire port  580  in hub  564  and extending through balloon  570  to a vascular filter or emboli capture device  582 , as described above. The ends of a filter basket  584  are secured in a fixed grommet  586  and a slidable grommet  588 . An expandable stent  590  is positioned annularly adjacent to balloon  570 .  
         [0070]    During insertion of the stent delivery system according to the present invention, deployment sheath  562  is advanced through a patient&#39;s vascular system to a desired location. During this stage of the procedure balloon  570  is either collapsed or expanded only so far as to hold stent  586  in position, and vascular filter  582  is somewhat compressed. After stent  590  is in position, deployment sheath  562  is pulled in the proximal direction, and then balloon  570  is expanded to secure stent  590  in position. Vascular filter  582  expands as grommet  588  slides in the proximal direction.  
         [0071]    Once stent  590  is in position, sheath  562  may be advanced distally to collapse vascular filter  582 . After vascular filter  582  is collapsed, sheath  562  and vascular filter  582  can be withdrawn together in the proximal direction.  
         [0072]    In a variation of the exemplary embodiment of the invention shown in FIG. 13 and FIG. 13A, stent  590  could be a self-expanding stent that is releasably positioned on a delivery catheter. See, for example, U.S. Pat. Nos. 5,246,445 and 5,372,600. The stent delivery catheter would comprise a lumen for release wires, etc., as well as a lumen for a guidewire lumen in connection with a vascular filter system.  
         [0073]    In another exemplary embodiment of the invention shown in FIG. 14 and FIG. 14A, vascular filter system comprises a guidewire  660  with a core wire  662  extending distally into floppy tip  664 . Vascular filter  666  comprises a filter membrane  668  positioned in a distally facing manner on filter basket  670  comprised of six to eight struts or wires  672 . The distal  674  and proximal  676  ends of basket wires  672  are held by proximal grommet  678  and distal sliding grommet  680 . Optionally, filter basket  670  has radiopaque markers  682 . A sheath  688  with expanded distal sheath section  690  is arranged concentrically around guidewire  660 .  
         [0074]    Consistent with the invention the vascular filter system will be inserted through a guide catheter in a patient&#39;s femoral artery and then advanced through the aorta to a position adjacent the patient&#39;s left ventricle. During electrophysiology or another ablation procedure in the left ventricle, any emboli or thrombus produced will be captured in filter membrane  668 . When the procedure is complete, sheath  688  and filter basket  670  are moved relative to one another so that the distal section  690  of sheath  688  causes filter basket  670  to collapse, whereupon filter basket  670  and captured material are withdrawn with the sheath.  
         [0075]    In another exemplary embodiment of the vascular filter system, the apparatus of FIG. 9 could be modified, as shown in FIG. 15. A basket  700  comprised of from four to eight strut wires  702  is secured by a proximal fixed grommet  704  and a distal slidable grommet  706 . Grommet  706  is slidable over core wire  708 . Filter membrane  710  is attached to or arranged upon basket  712 , with the proximal section  714  of the membrane  710  being open to flow, represented by arrow  716 . The proximal portion  714  of membrane  710  forms a conical shape that extends distally. The filter may be deployed by, for example, a sheath, a tube, or a wire fixed to the distal slidable crimp band  706 .  
         [0076]    Membrane  710  preferably has holes only in proximal section  714 , which holes are arranged as described above. It is believed that under normal, substantially laminar flow conditions debris or emboli  718  will tend to collect in annular recesses  720 .  
         [0077]    [0077]FIG. 16 and FIG. 16A depict a guide catheter  430  comprising a catheter shaft  432  having a distal end  434 . A filter membrane  436  having a flexible support or structure is arranged, distally facing, on said distal end  434 . The proximal portion of filter membrane  436  is secured at band  438 . A sheath  440  is arranged concentrically around guide catheter shaft  432  so that when sheath  440  is advanced distally, filter membrane  436  collapses. It is contemplated that other means may be devised for collapsing filter membrane  436 , such as a wire. Guide catheter  430  will preferably have a lumen  442  capable of receiving another device, such as an ablation catheter (not shown).  
         [0078]    In accordance with the present invention, the distal portion of the guide catheter will be advanced through the femoral artery into the left ventricle.  
         [0079]    In another exemplary embodiment of the invention, as shown in FIG. 17, an ablation catheter  750  may have a filter membrane  752  arranged proximal to the distal end of catheter  750  by means discussed above, such as a sheath concentric to the catheter or a wire, or other means.  
         [0080]    The preceding specific exemplary embodiments are illustrative of the practice of the invention. It is to be understood, however, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the spirit of the invention or the scope of the appended claims.