Abstract:
Thrombectomy and other treatments are achieved using a catheter having a positioning cage and a macerator within the positioning cage. The catheter is introduced to a target body lumen, typically a blood vessel, and a positioning cage deployed at a treatment site. The macerator is then operated to disrupt thrombus, clot, or other occlusive materials at the treatment site, and the catheter is used to collect and remove the disruptive materials from the body lumen. In particular examples, the macerator may be radially expansible and optionally rotated and/or axially translated within the positioning cage to effect disruption of the occlusive material.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This present application is a continuation of application Ser. No. 10/162,276, filed Jun. 3, 2002 now U.S. Pat. No. 6,600,014, which was a continuation of application Ser. No. 09/454,517 filed Dec. 6, 1999 now U.S. Pat. No. 6,454,775, the full disclosures of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to medical devices and methods. More particularly, the present invention relates to devices and methods for disrupting, collecting, and removing occlusive material from blood vessels and other body lumens. 
   Thrombosis and atherosclerosis are common ailments which occur in humans and which result from the deposition of thrombus and clot on the walls of blood vessels. When hardened, such deposits are commonly referred to as plaque. Such deposits are most common in the peripheral blood vessels that feed the limbs of the human body and the coronary arteries which feed the heart. Stasis, incompetent valves, and trauma in the venous circulation cause thrombosis, particularly occurring as a deep vein thrombosis in the peripheral vasculature. When such deposits build-up in localized regions of the blood vessel, they can restrict blood flow and cause a serious health risk. 
   In addition to forming in the natural vasculature, thrombosis is a serious problem in “artificial” blood vessels, particularly in peripheral femoral-popliteal and coronary bypass grafts and dialysis access grafts and fistulas. The creation of such artificial blood vessels requires anastomotic attachment at at least one, and usually at at least two, locations in the vasculature. Such sites of an anastomotic attachment are particularly susceptible to thrombus formation due to narrowing caused by intimal hyperplasia, and thrombus formation at these sites is a frequent cause of failure of the implanted graft or fistula. The arterio-venous grafts and fistulas which are used for dialysis access are significantly compromised by thrombosis at the sites of anastomotic attachment and elsewhere. Thrombosis often occurs to such an extent that the graft needs to be replaced within a few years or, in the worst cases, a few months. 
   A variety of methods have been developed for treating thrombosis and atherosclerosis in the coronary and peripheral vasculature as well as in implanted grafts and fistulas. Such techniques include surgical procedures, such as coronary artery bypass grafting, and minimally invasive procedures, such as angioplasty, atherectomy, transmyocardial revasculaturization, and the like. Of particular interest of the present invention, a variety of techniques generally described as “thrombectomy” have been developed. Thrombectomy generally refers to procedures for the removal of relatively soft thrombus and clot from the vasculature. Removal is usually achieved by mechanically disrupting the clot, optionally with the introduction of thrombolytic agents. The disrupted thrombus or clot is then withdrawn through a catheter, typically with a vacuum or mechanical transport device. 
   Thrombectomy generally differs from angioplasty and atherectomy in the type of occlusive material which is being treated and in the desire to avoid damage to the blood vessel wall. The material removed in most thrombectomy procedures is relatively soft, such as the clot formed in deep vein thrombosis, and is usually not hardened plaque of the type treated by angioplasty in the coronary vasculature. Moreover, it is usually an objective of thrombectomy procedures to have minimum or no deleterious interaction with the blood vessel wall. Ideally, the clot will be disrupted and pulled away from the blood vessel wall with no harmful effect on the wall itself. 
   While successful thrombectomy procedures have been achieved, most have required comprise between complete removal of the thrombosis and minimum injury to the blood vessel wall. While more aggressive thrombectomy procedures employing rotating blades can be very effective at thrombus removal, they present a significant risk of injury to the blood vessel wall. Alternatively, those which rely primarily on vacuum extraction together with minimum disruption of the thrombus, often fail to achieve sufficient thrombus removal. 
   For these reasons, it would be desirable to provide improved apparatus, systems, methods, and kits for performing thrombectomy procedures. It is particularly desirable that the present invention provide thrombectomy procedures which are both capable of effective thrombus and clot removal while minimizing the risk of injury to the blood vessel wall. The methods and procedures of the present invention should be suitable for treatment of both arteries and veins within the peripheral, coronary, and cerebral vasculature. Even more particularly, the present invention should provide for the treatment of native and synthetic grafts which are subject to thrombosis and clotting, such as arterio-venous grafts and fistulas, bypass grafts, and the like. In addition to treatment of the vasculature, the methods, systems, devices, and kits of the present invention should also be useful for treating other body lumens which are subject to occlusion and blockage due to the presence of occlusive materials within the lumen. At least some of these objectives will be met by the inventions described hereinafter. 
   2. Description of the Background Art 
   U.S. Pat. No. 5,904,698, describes a catheter having an expansible mesh with a blade or electrode for shearing obstructive material which penetrates the mesh when the mesh is expanded in a blood vessel. Other catheters having expansible meshes, cages, and/or shearing elements are described in U.S. Pat. Nos. 5,972,019; 5,954,737; 5,795,322; 5,766,191; 5,556,408; 5,501,408; 5,330,484; 5,116,352; and 5,410,093; and WO 96/01591. Catheters with helical blades and/or Archimedes screws for disrupting and/or transporting clot and thrombus are described in U.S. Pat. Nos. 5,947,985; 5,695,501; 5,681,335; 5,569,277; 5,569,275; 5,334,211; and 5,226,909. Catheters having expansible filters at their distal ends are described in U.S. Pat. No. 4,926,858 and PCT publications WO 99/44542 and WO 99/44510. Other catheters of interest for performing thrombectomy and other procedures are described in U.S. Pat. Nos. 5,928,186; 5,695,507; 5,423,799; 5,419,774; 4,762,130; 4,646,736; and 4,621,636. Techniques for performing thrombectomy are described in Sharafudin and Hicks (1997)  JVIR  8: 911-921 and Schmitz-Rode and Günthar (1991)  Radiology  180: 135-137. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides apparatus, systems, methods, and kits for removing occlusive material from body lumens. While the present invention is particularly suitable for the removal of thrombus and clot from the vasculature, it will also find use in other body lumens, such as the ureter, urethra, fallopian tubes, bile duct, intestines, and the like. The present invention is advantageous in a number of respects. In particular, the present invention provides for effective removal of the occlusive material from the body lumen. Such removal is effective in both achieving a high degree of removal and minimizing the amount of material which is released into the body lumen. This is a particular advantage in treatment of the vasculature where the release of emboli can be a serious risk to the patient. The present invention achieves such effective removal with minimum risk of injury to the luminal wall. As described in detail below, the present invention employs a macerator for breaking up or “disrupting” the thrombus, clot, or other occlusive material, where the macerator is carefully positioned to minimize or prevent contact with and reduce or eliminate the potential for injury to the luminal wall. 
   In a first aspect, apparatus according to the present invention comprises a catheter for removing the occlusive material from the body lumen. The catheter comprises a catheter body having a proximal end, a distal end, and a lumen therethrough. A radially expansible positioning cage is disposed on the catheter body near its distal end, and a macerator is disposed within the expansible positioning cage. The macerator is configured to disrupt occlusive material within the cage when the cage is expanded against the luminal wall. The macerator is typically a rotating element, such as a helical or other shaped wire which engages and disrupts the occlusive material. Usually, the disrupted material will also be drawn into the catheter body lumen. Alternatively, the disrupted thrombus can be captured in whole or in part by a second catheter usually introduced downstream from the first catheter with the macerator. The second catheter may also comprise a macerator and, in some instances, the two catheters can be similar or identical. In all cases, the disrupted thrombus may be removed through the catheter lumen by aspiration using an external vacuum source and/or a mechanical pump. As a further alternative, a portion of the expansible cage can be provided with a mesh or other filter membrane to permit blood or other luminal flow past the catheter while entrapping the disrupted clot. When the expansible cage is collapsed, the captured clot will be contained, permitting its withdrawal together with the catheter. Often, the “filtering” cage can be used in combination with an aspiration lumen within the catheter itself and/or a second catheter for capturing the disrupted thrombus. Optionally, thrombolytic agents can also be introduced through the catheter to help disrupt the thrombus and clot, and a vacuum and/or mechanical extraction system can be used to help transport the disrupted clot, thrombus, or other occlusive material through the catheter and out of the patient&#39;s body. 
   The radially expansible positioning cage can take a variety of forms, and will usually be configured to position and maintain the distal end of the catheter body away from the luminal wall, preferably at or near the center region of the body lumen being treated. Usually, the cage will be expansible from an initial width (usually diameter) in the range from 1 mm to 4 mm to an expanded width (diameter) from 2 mm to 40 mm. In some instances, the radially expansible cage will have a resilient but generally uncontrolled diameter, i.e., it will be self-expanding. That is, the cage will simply expand within the body lumen to engage the luminal wall and press against the wall with whatever spring force remains in its structure. In such cases, the cage will usually be initially constrained, e.g., by positioning within an outer tube or sheath, and thereafter released from constraint so that it expands within the body lumen to both anchor and center the catheter therein. Alternatively, and usually preferably, the radially expansible cage will have a selectively adjustable diameter. That is, the size or outer diameter of the cage will be controlled by the user so that the cage can be expanded and deployed against the luminal wall with a desired anchoring force. A variety of specific mechanisms for achieving such controlled expansibility are available, with exemplary systems described below. 
   The radially expansible positioning cage may have a variety of specific configurations. Most commonly, it will consist of a plurality of wires or filaments arranged in axial, helical, or other circumferentially spaced-apart geometries which provide the desired radial positioning forces while retaining sufficiently large gaps or apertures to permit intrusion of the clot or thrombus. As an alternative to wires, the cage could also employ ribbons, perforated plate structures, and will usually be formed from an elastic material, more usually from a metal having spring memory, such as stainless steel, nitinol, or the like. Alternatively, the cage could be formed from a material which expands and responds to electrical or other stimulus. For example, certain bi-metal structures could be electrically heated to effect expansion. Alternatively, heating at a certain heat memory alloys could also permit selective expansion and contraction of the cage. Other specific designs will also be available. 
   The macerator may also have a variety of configurations, that will generally be configured to engage and optionally penetrate the occlusive material within the body lumen. Usually, the macerator will have a distal portion which engages the clot and thrombus and which is expansible from an initial width (usually diameter) in the range from 1 mm to 4 mm to an expanded width (diameter) in the range from 2 mm to 35 mm. In the case of thrombus and clot, the macerator will usually be able to penetrate into the mass of thrombus or clot to engage and entangle the fibrin strands therein. By thus “capturing” the thrombus or clot, the macerator can then draw the material away from the luminal wall and break up the material sufficiently so that it may be withdrawn, for example, through the lumen of the catheter, optionally, but not necessarily with mechanical and/or vacuum assistance. 
   The macerator will usually be radially expansible so that, after the catheter has been centered, the macerator may be deployed and expanded to engage the occlusive material without engaging the luminal wall. While it is possible that the macerator would have a fixed width or diameter (i.e., would be released from constraint to assume its full, unconstrained dimension), the macerator will more usually be capable of being selectively expanded (i.e., the user will be able to selectively expand and collapse the macerator to achieve a desired width or diameter). Most preferably, both the cage and the macerator will be selectively expansible, where the expansion of each can be effected separately from the expansion of the other. That is, in the most preferred embodiments of the present invention, the catheter will have both a positioning cage and a macerator which can each be independently adjusted in their radial width or diameter. 
   Further preferably, the macerator will be rotatable and/or axially movable to assist in breaking up the occlusive material within the cage and drawing the material into the catheter body. In such cases, the catheter will usually further comprise a drive unit attached or attachable to a proximal end of the catheter body. The drive unit will usually be coupled through a drive cable or shaft to the macerator. 
   In the most preferred configurations, the macerator will comprise an expansible shaped wire which can be deployed within the positioning cage. The shaped wire may have a generally uniform diameter, but will more usually be non-uniform in diameter, thus being a spiral or other particular geometry. The width of the shaped wire may be adjusted in a variety of ways. For example, two spaced-apart points on the wire may be axially translated relative to each other in order to open or close the helix or other geometry. Alternatively, or additionally, the two spaced-apart points on the shaped wire may be rotated relative to each other in order to achieve expansion and contraction of the wire. Several specific shaped wire macerator designs are presented hereinafter. 
   In a second aspect, apparatus of the present invention comprises the macerator assemblies. For example, a first embodiment of the macerator comprises a tubular shaft having a proximal end, a distal end, and at least one lumen therethrough. A wire having a distal section and a helical shank is disposed within the tubular shaft so that a distal section of the wire is attached to an exterior location near the distal end of the shaft. The distal section of the wire will be shaped or shapeable so that it can be radially expanded from the tubular shaft to provide a clot disruption structure. In the simplest embodiments, the wire may be expanded to form a simple arc-shaped profile which can be rotated to generate an ovoid path within the clot. Alternatively, the distal section of the wire could have a more complex geometry, such as a helical coil having one, two, three, or more turns on the distal shaft after it is expanded. Other geometries will also be possible. A proximal end of the shank is slidably received in the lumen of the shaft so that the distal section can be radially expanded and contracted by axially translating the shank relative to the shaft. Optionally, the tubular shaft will include only the single lumen which will extend the entire length of the shaft. In that case, the wire will pass into the lumen through a port in the side of the shaft. Preferably, the single internal lumen will have a diameter which is sufficiently large to accommodate both the wire and a separate guidewire, at least over the portions of the shaft where both would be present. In such cases, the internal diameter will usually be at least 0.25 mm, often at least 0.5 mm, preferably at least 1 mm, and sometimes 1.5 mm or larger. Also in such cases, the capture wire will have a diameter in the range from 0.05 mm to 1.5 mm, usually from 0.5 mm to 1.3 mm, at least over that portion of the capture wire which is within the lumen with the guidewire. 
   In an alternative embodiment, the tubular shaft may include at least two lumens, where the wire is received in a proximal portion of one lumen and the other lumen is configured to receive a guidewire. Usually, the capture wire lumen will terminate proximally of the distal end of the tubular shaft, but the lumen which receives the guidewire will extend the entire length of the shaft. 
   A second embodiment of the macerator of the present invention comprises a tubular shaft assembly including an outer tube having a proximal end, a distal end, and a lumen therethrough. An inner tube having a proximal end, a distal end, and a lumen therethrough is rotatably and/or slidably received in the lumen of the outer tube, and a wire coil has one end attached to the proximal end of the inner tube and another end attached to the proximal end of the outer tube. Thus, the wire coil can be radially expanded and collapsed by rotating and/or axially translating the inner tube relative to the outer tube. 
   Both of the macerators just described will find use in combination with any of the catheter systems described earlier in this application. 
   In another aspect of the present invention, methods for removing occlusive material from a body lumen comprise positioning a macerator so that it is spaced inwardly from (usually centered within) a surrounding wall of the body lumen. The macerator is rotated and/or axially translated to disrupt and optionally capture clot without significant shearing. The disrupted clot may then be withdrawn through a catheter within the body lumen, usually the catheter used to deploy the macerator, or otherwise captured. In the preferred embodiments, the width of the macerator will be adjusted, and the macerator is in the form of a helical wire. In the case of helical wire macerators, width adjustment can be achieved by rotating and/or axially translating spaced-apart points on the wire to achieve a desired helical diameter. Usually, positioning the macerator is achieved by expanding a positioning cage within the body lumen, where the macerator is located within the positioning cage. In such cases, the methods will usually further comprise translating and/or rotating the macerator within the positioning cage. 
   The present invention still further comprises kits, including a catheter having a macerator near its distal end. The kits will further include instructions for use according to any of the methods set forth above. In addition to the catheter and instructions for use, the kits will usually further comprise packaging, such as a box, pouch, tray, tube, bag, or the like, which holds the catheter and the instructions for use. Usually, the catheter will be maintained sterilely within the package, and the instructions for use will be printed on a separate package insert or piece of paper. Alternatively, the instructions for use may be printed in whole or in part on a portion of the packaging itself. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a clot disruption catheter system constructed in accordance with the principles of the present invention. 
       FIG. 2A  is a detailed view of the distal end of the clot disruption catheter system of  FIG. 1 , with portions broken away. 
       FIG. 2B  is a detailed view of a portion of the proximal end of the clot disruption catheter system of  FIG. 1 , with portions broken away. 
       FIG. 2C  is a detailed view of a first embodiment of an expansible positioning cage that can be used as part of the clot disruption catheter system of  FIG. 1 , or any of the other embodiments of the present invention. 
       FIG. 2D  is a detailed view of an alternative expansible positioning cage that can be used with any of the embodiments of the present invention. 
       FIG. 3A  is a side view of a portion of the catheter system of  FIG. 1  showing the expansible positioning cage and macerator in their deployed configuration. 
       FIG. 3B  is similar to  FIG. 3A , except that the positioning cage and macerator are shown in their non-deployed configuration. 
       FIG. 4  is a perspective view of a distal portion of a second embodiment of a clot disruption catheter constructed in accordance with the principles of the present invention. 
       FIG. 5A  is a side view of the distal end of the catheter of  FIG. 4 , shown in section with the positioning cage and macerator in a non-deployed configuration. 
       FIG. 5B  is similar to  FIG. 5A , except that the centering cage and macerator are shown in a deployed configuration. 
       FIGS. 6A and 6B  illustrate a distal portion of a third embodiment of the clot disruption catheter of the present invention shown in the deployed and non-deployed configurations, respectively. 
       FIGS. 7A and 7B  illustrate the distal portion of a fourth embodiment of a clot disruption catheter constructed in accordance with the principles of the present invention. 
       FIGS. 8A-8C  illustrate a macerator having a helical wire and methods for its deployment. 
       FIG. 9  illustrates a method according to the present invention employing the catheters of FIG.  1  and  FIGS. 7A and 7B  in combination. 
       FIGS. 10A and 10B  illustrate a modified clot disruption catheter having a filtering structure over a portion of the expansible cage and methods for its use. 
       FIG. 11  illustrates a kit constructed in accordance with the principles of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , a first embodiment of a clot disruption system  10  constructed in accordance with the principles of the present invention will be described. The clot disruption system  10  includes a clot disruption catheter  12  and a motor drive unit  14 . The catheter  12  has a distal section  16  which comprises the expansible cage and macerator components of the catheter, as described in greater detail in connection with  FIGS. 2A and 2B . A proximal hub  18  is secured to the proximal end of the catheter  12  and removably connectable to the motor drive unit  14 . The motor drive unit  14  will be configured to transmit rotational and/or axial translational forces through a tubular shaft  22  ( FIGS. 2A and 2B ) to manipulate the macerator. A slidable ring  24  is shown schematically on the motor drive unit  14  and is intended, for example, to permit axial translation of the macerator. Such axial translation, however, is not essential and is only an optional feature of the present invention. 
   The distal section  16  of the clot disruption catheter  12  is best illustrated in FIG.  2 A. The distal section  16  comprises a radially expansible cage  26  which may have any of the forms and structures described above. In particular, cage  26  may comprise a plurality of helical wires or other elements  26 A, as illustrated in FIG.  2 C. Alternatively, the cage may comprise a plurality of straight, axially aligned wires or other elements  26 B, as shown in FIG.  2 D. In the catheter  12 , the expansible cage  26  will be self-expanding, i.e., it will assume its radially expanded configuration absent any constraining forces. The cage  26  is shown in its expanded configuration in each of  FIGS. 1 ,  2 A,  2 C, and  2 D. The distal tips of the cage elements are attached to a nose cone  28  which may be fixed or floating relative to the main portion of the catheter body  12 , as described in more detail below. 
   The body of clot disruption catheter  12  will have a lumen  30  extending from hub  18  to the distal section  16 , and the tubular shaft  22  will be disposed within the lumen  30 . A distal end  32  of the tubular shaft  22  will be connected to the nose cone  28 , and the shaft will preferably have an inner lumen  34  which terminates in a series of infusion ports  36  (which may be circular, as illustrated or may be elongate slits or may have a variety of other geometries) disposed between the distal end of the body of catheter  12  and the nose cone  28 . The lumen  34  and infusion ports  36  will be useful, for example, for delivering thrombolytic and other agents used in connection with clot disruption. The lumen will also receive a guidewire  20  to facilitate positioning within a blood vessel or other body lumen. 
   Macerator  40  is disposed on the tubular shaft  22  within the expansible cage  26 . The macerator  40  is illustrated as a helical wire or filament, but could comprise any of the structures described previously. Helical wire  42  is formed from spring material, typically a spring stainless steel or shape memory alloy, and is fixedly attached to the shaft  22  at both ends. First attachment point  44  is visible in  FIG. 2A , while the second attachment point is hidden behind the shaft. With this configuration of wire  42 , it will be appreciated that the macerator  40  is self-expanding. Radial compression forces will cause the element  42  to collapse radially inwardly against the exterior of shaft  22 . 
   Macerator  40  comprising helical wire  42  is intended to operate by rotation of the shaft  22 . When the shaft  22  is rotating, the helix will trace a generally ovoid shell within the expansible cage  26 , thus engaging and disrupting occlusive material which is within the cage. In particular, when treating clot within blood vessels, the helical wire  42  will disrupt the clot and engage and entangle materials within the clot, particularly fibrin fibers which make up a substantial portion of the clot material. By breaking up and engaging the clot in this fashion, the clot is pulled away from the blood vessel wall rather than sheared from the wall as in many prior thrombectomy and atherectomy procedures. In particular, the combination of the expansible positioning cage  26  and the macerator which is spaced radially inward from the shell defined by the cage, clot removal and disruption can be performed with minimum risk of injury to the blood vessel wall. 
   The expansible cage  26  and macerator  40  will usually be radially collapsed to facilitate introduction and withdrawal of the catheter  12  to and from a target site within the vasculature or other body lumen. The necessary radial constraint can be provided in a number of ways. For example, a tether or filament could be wrapped around both the cage  26  and the macerator  40 , with the constraint being removed when the device reaches the target site. Alternatively, the cage  26  and/or the macerator  40  could be composed of a heat memory material, permitting deployment by use of an induced temperature change, e.g., by passing an electrical current through the structures or by infusing a heated or cooled fluid past the structures. Preferably, however, a radial constraint will be provided by a sheath  46  which can be axially advanced to radially collapse both the cage  26  and macerator  40 . 
   Optionally, the catheter  12  may further comprise a mechanical pump to assist in the removal of disrupted clot and other debris which is produced by operation of the macerator. Conveniently, the mechanical pump may comprise a helical rotor  48  which is disposed over the outer surface of the tubular shaft  22 , as illustrated in both  FIGS. 2A and 2B . Preferably, although not necessarily, the helical rotor  48  will extend from the proximal side of the macerator (helical wire  42 ) all the way into the interior of the hub  18 . In this way, disrupted clot on other fluid materials can be pumped proximally by the rotor  48  (which acts as an “Archimedes screw”) as the macerator and tubular shaft are rotated. 
   Referring now to  FIGS. 3A and 3B , the catheter  12  is shown with the distal section  16  in its radially expanded configuration in FIG.  3 A. In particular, sheath  46  is proximally withdrawn to permit both the cage  26  and macerator  40  to radially expand to their maximum diameters. Of course, if the catheter  12  were present in a blood vessel or other body lumen, the radial expansion of the cage  26  would be limited by contact with the luminal wall. In order to facilitate introduction or withdrawal of the catheter  12  from the target body lumen, the distal section  16  can be radially collapsed by distally advancing the sheath  46 , as shown in FIG.  3 B. 
   Referring now to  FIG. 2B , the construction of proximal hub  18  will be described. A rotating hemostatic fitting  50  is provided at the proximal end of catheter  12  and mates with the distal end of hub body  52 . Tubular shaft  22  passes from the lumen  30  of catheter  12  into the interior  54  of hub body  52 . A rotating hemostatic seal structure  56  is also provided within the interior  54  and divides the interior into a first isolated region  58  and a second isolated region  60 . The first isolated region  58  has connector branch  62  which permits aspiration of fluids and materials through the lumen  30  of catheter  12 . A second connector branch  64  opens to the second isolated region  60  and permits infusion of therapeutic agents, such as thrombolytic agents, into the lumen  34  of the tubular shaft  22  through ports  68 . A rotating seal  70  is provided at the proximal end of the hub and a hemostatic valve  72  is provided on the proximal end of tubular shaft  22  to permit introduction of a guidewire. The connector  72  will also be suitable for coupling to the motor drive unit  14  to permit rotation of shaft  22  which in turn rotates the macerator  40 . Note that the hub  18  illustrated in  FIG. 2B  is not suitable for axial translation of the shaft  22  relative to the catheter  12 . 
   Referring now to  FIGS. 4 ,  5 A and  5 B, a second exemplary clot disruption catheter  100  will be described. The catheter  100  includes a catheter body  102  and a tubular shaft  104  which is rotatably and axially slidably received in a lumen of the catheter body. The catheter  100  has a distal section  106  including a radially expansible cage  108  and a macerator  110  in the form of an arcuate wire. In contrast to catheter  12  of the first embodiment, both the expansible cage  108  and macerator  110  will be selectively and controllably expansible in the clot disruption catheter  100 . 
   Referring in particular to  FIGS. 5A and 5B , the tubular shaft  104  extends through lumen  103  of the catheter body  102  and terminates in a nose cone  112 . A bearing structure  114  receives the tubular shaft  104  and permits both rotation and axial translation thereof relative to the catheter body  102 . While the bearing  114  could be positioned directly on the distal tip of the catheter body  102 , that would block lumen  103  and prevent collection of disrupted clot or other occlusive material therein. Thus, it is desirable to mount the bearing structure  114  distal to the distal end of catheter body  102 , e.g., on spacer rods  116 , to provide an opening or gap which permits aspiration of disrupted clot or other material through the lumen  103 . The distal end of tubular shaft  104  is mounted in a second bearing structure  118  located in the nose cone  12 . Bearing structure  118  permits rotation but not axial translation of the shaft  104 . Thus, when the shaft  104  is drawn proximally in the direction of arrow  120  (FIG.  5 B), the distance between the nose cone  12  and the bearing structure  114  is reduced. This causes the elements of cage  108  to axially shorten and radially expand. While the elements of cage  108  are shown as axial wires or filaments, it will be appreciated that they could be helical or have any one of a variety of other configuration which would permit radial expansion upon axial contraction. Similarly, the macerator wire  110  is fixedly attached to the tubular shaft  104  at an attachment point  122 . The other end of the macerator wire  110  is connected at attachment point  124  to the portion of bearing structure  114  which rotates together with the tubular shaft  104 . In this way, the macerator is both axially shortened so that it radially expands and is able to rotate when the tubular shaft  104  is rotated, e.g., in the direction of arrow  126 . 
   Optionally, the clot disruption catheter  100 , or any of the other clot disruption catheters described herein, may include a mechanical pump component to assist in extraction of clot or other disrupted materials through the lumen of the catheter. As best seen in FIGS.  5 A and  5 B, the mechanical pump may comprise a simple helical screw, such as a helically wound wire or other element  130 . Such a helical screw pump is commonly referred to as an “Archimedes” screw pump and operates by creating a vortical flow as the screw pump is rotated. While in some instances use of the screw pump may be sufficient in itself to remove materials, the screw pump will most often be used in combination with vacuum aspiration to remove materials through the lumen of the catheters. 
   Thus far, clot disruption catheter embodiments have been shown where both the expansible positioning cage and the macerator are self-expanding and where expansion of the cage and macerator are mechanically coupled together, i.e., neither the cage nor the macerator may be expanded or contracted independent of the other. The present invention contemplates other embodiments where either or both of the expansible cage and the macerator may be independently expanded and where the other may optionally be self-expanding. For example, as shown in  FIGS. 6A and 6B , a clot disruption catheter  200  comprises a catheter body  202  having a tubular shaft  204  and a lumen  203  thereof. The shaft  204  has a macerator  210  in the form of a helical wire which is fixedly attached at point  212  and slidably attached at point  214 . In contrast with the previous embodiments, the tubular shaft  204  is not connected to nose cone  216 , but instead floats on a rod  218  which extends proximally from the nose cone. A contraction sleeve  220  is slidably received over the wires which form cage  208  in such a way that proximal movement of the sleeve  220  (relative to the position shown in  FIG. 6A ) will cause the cage to radially collapse, i.e., as shown in FIG.  6 B. Proximal translation of the sleeve  220  can be effected by proximally drawing tubular shaft  204  so that constraining bearings  222  on the shaft draw the sleeve  220  in the proximal direction together with the shaft. Thus, selective expansion and contraction of the cage  208  can be effected by axial movement of the tubular shaft  204  relative to the catheter body  202 . Structural integrity of the catheter will be maintained by presence of the rod  218  within the distal end of the lumen  240  within the tubular shaft  204 . 
   Proximal motion of the sleeve  220 , however, does not directly collapse the macerator  210 . Instead, the macerator  210  is collapsed by a combination of forces. First, the proximal attachment point  212  is drawn into lumen  203  of the catheter body  202 , thus constraining the macerator and causing its partial collapse. The remainder of the macerator will be collapsed by the force of the cage structure  208  as it is drawn inwardly by the sleeve  220 . The floating attachment point  214  will move over the outer surface of the tubular shaft  204  to accommodate the radial collapse. Thus, the embodiment of  FIGS. 6A and 6B  illustrates the selective radial expansion and contraction of the positioning cage  208  and the self-expansion of the macerator  210  in response to expansion and contraction of the cage. 
   A fourth exemplary clot disruption catheter  300  is illustrated in  FIGS. 7A and 7B . The clot disruption catheter  300  comprises catheter body  302  having an expansible cage  304  at its distal end. In contrast to previous embodiments, the expansible cage  304  is in the form of a conical “funnel” which may be formed from impervious materials (which will not permit the bypass of blood or other luminal flows) or from “filtering” materials which will permit blood or other bypass flows. Preferably, the funnel will be formed from pervious materials, such as wire meshes, perforate membranes, woven fabrics, non-woven fabrics, fibers, braids, and may be composed of polymers, metals, ceramics, or composites thereof. The filters will have a pore size selected to permit blood flow (including blood proteins) but capture disrupted clot and other embolic debris. Useful pore sizes will be in the range from 20 μm to 3 mm. 
   The funnel will usually be formed from a flexible filter material and supported on a plurality of rods  306  which can be actively or passively deflected in order to open or close the conical cage. Most simply, the rod members  206  will be resilient and have a shape memory which opens the cage structure in the absence of radial constraint. Thus, catheter  300  may be conveniently delivered through a sheath, in a manner analogous to that described in connection with FIG.  1 . The clot disruption catheter  310  further includes a macerator assembly  310 , best observed in FIG.  7 B. The macerator comprises a tubular shaft  312 , such as a highly flexible coil shaft adapted to transmit rotational torque. Tubular shaft  312  will include an internal lumen to permit introduction over a guidewire  314 . A helical macerator wire  316  has a distal end  318  attached to the distal end of shaft  312 . A proximal portion  320  of the macerator  316  extends through a tube  322  attached to the side of the tubular member  312 . In this way, the helical portion of macerator  316 , which has a helical memory shape, can be expanded and contracted by axially translating the proximal portion  320 . Although illustrated passing through a separate tubular member  22 , the proximal portion  320  could pass through the same lumen of the tubular shaft  316  as does the guidewire  314 . It will be appreciated that the macerator structure  316  could be employed with any of the previous embodiments where it is desired to provide for selective expansion and contraction of the macerator. 
   An alternative embodiment of a macerator  400  mounted at the distal end of the tubular shaft  402  is illustrated in  FIGS. 8A-8C . A macerator  400  comprises a helical wire  404  having a distal end secured to the distal tip of a rod  406 . The rod  406  is slidably and/or rotatably positioned within a lumen of the tubular shaft  402 . Thus, by rotating the tubular shaft  402  relative to the rod  406 , as shown in  FIG. 8B , the helical portion of macerator  404  can be wound down (or wound away from) the rod  406 . Alternatively, by axially translating the tubular body  402  relative to the rod  406 , the macerator  404  can also be collapsed, as shown in FIG.  8 C. It will be appreciated that these macerator embodiments can be utilized in any of the previously described embodiments of the clot disruption catheters of the present invention. 
   Referring now to  FIG. 9 , use of clot disruption catheter  100  and clot disruption catheter  300  for performing a procedure in accordance with the principles of the present invention will be described. The catheters  100  and  300  are introduced to a region within the patient&#39;s venous system, e.g., at the junction between the iliac veins IV and the inferior vena cava IVC. Blood flow is in the direction from bottom to top, and catheter  100  is introduced into the iliac vein IV in an antegrade direction, i.e., in the direction of blood flow. Catheter  300  is introduced into the inferior vena cava IVC in a retrograde direction, i.e., against the flow of blood. Filtering cage  304  is expanded so that the distal end of the “funnel” engages and generally seals around the interior wall of the inferior vena cava. Positioning cage  26  on catheter  100  is advanced into a region of clot C within the iliac vein IV and the macerator (not shown) is activated in order to disrupt the clot. Optionally, aspiration (and/or mechanical pumping) will be applied through port  62  in order to draw a portion of the disrupted clot out of the patient&#39;s vasculature. Further optionally, a thrombolytic agent may be introduced through port  64 . Pieces of the disrupted clot DC, however, may be released into the blood flow so that they pass from the iliac vein IV into the inferior vena cava. By positioning the funnel-like cage  304  of catheter  300  within the inferior vena cava, however, the disrupted clot may be captured and, optionally, further disrupted using the macerator assembly within catheter  300 . This material may then be aspirated through port  62 , optionally being transported using a mechanical pump as elsewhere described herein. 
   As just described, blood or other luminal filtering can be used advantageously in connection with the devices and methods of the present invention. While a funnel-like cage was described as part of catheter  300 , the other cage structures described herein can also be provided with a filtering membrane, mesh, or other porous structure as illustrated in  FIGS. 10A and 10B . In  FIG. 10A , a clot disruption catheter  500 , which may have any of the specific structures described previously (except for that of catheter  300 ), has an expansible positioning cage  502  at its distal end. A filtering membrane or mesh  504  is formed over the proximal half of the cage  502 . The catheter  500  will be particularly useful for treating clot C in a blood vessel B in a retrograde direction, i.e., where the catheter is introduced in a direction against that of blood flow, as shown by arrows  510 . The disrupted clot material captured within the filter  504  may be aspirated through the catheter and/or captured within the mesh as the mesh is collapsed. 
   Catheter  600  ( FIG. 10B ) is similar to catheter  500  and includes an expansible cage  602  having a membrane or mesh filter element  604  thereon. The filter element  604  is disposed over the distal half or portion of the expansible cage  602 , rather than the proximal half. Thus, the catheter  600  is particularly useful for treating clot or thrombus using an antegrade approach, i.e., where the catheter is introduced in the direction of blood flow as shown by arrows  610 . In particular, the catheter  600  may be introduced to a blood vessel BV in a conventional manner and pass through a region of clot C so that the expansible cage  604  lies beyond the clot. The catheter may then be drawn proximally so that the internal macerator can disrupt the clot. The disrupted clot will then be collected within the filter  604 , and can withdrawn from the blood vessel by collapsing the filter together with the cage. 
   Turning now to  FIG. 11 , the present invention further comprises kits which include at least a catheter, which is shown to be catheter  100  but can be any other catheter capable of disrupting clot in accordance with the methods of the present invention. The kit will further include instructions for use IFU setting forth any of the methods described above. Optionally, the kit may further comprise a motor drive unit  14  or other kit components, such as a guidewire, a thrombolytic agent, or the like. Usually, the kit components will be packaged together in a pouch P or other conventional medical device packaging, such as a box, tray, tube, or the like. Usually, at least the catheter component will be sterilized and maintained sterilely within the package. Optionally, the motor drive unit may not be included with the kits, but may instead be provided as a reusable system component. In that case, usually, the catheter will be disposable. 
   While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.