Patent Publication Number: US-2005119615-A1

Title: Guidewire for crossing occlusions or stenoses

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
      The present application is a continuation-in-part of U.S. patent application Ser. No. 09/644,201, entitled “Guidewire for Crossing Occlusions or Stenoses,” (allowed), which claimed benefit under  37  C.F.R. § 1.78 to U.S. Provisional Patent Application No. 60/195,154, filed Apr. 6, 2000, entitled “Guidewire for Crossing Occlusions or Stenosis,” the complete disclosures of which are incorporated herein by reference.  
      The present application is also related to U.S. patent application Ser. No. 09/030,657, filed Feb. 25, 1998, and U.S. patent application Ser. No. 09/935,534, filed Aug. 22, 2001, now U.S. Pat. No. 6,746,422, entitled “Steerable Support System with External Ribs/Slots that Taper,” the complete disclosure of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention is generally related to medical devices, kits, and methods. More specifically, the present invention provides a guidewire system for crossing stenosis, partial occlusions, or total occlusions in a patient&#39;s body.  
      Cardiovascular disease frequently arises from the accumulation of atheromatous material on the inner walls of vascular lumens, particularly arterial lumens of the coronary and other vasculature, resulting in a condition known as atherosclerosis. Atheromatous and other vascular deposits restrict blood flow and can cause ischemia which, in acute cases, can result in myocardial infarction or a heart attack. Atheromatous deposits can have widely varying properties, with some deposits being relatively soft and others being fibrous and/or calcified. In the latter case, the deposits are frequently referred to as plaque. Atherosclerosis occurs naturally as a result of aging, but may also be aggravated by factors such as diet, hypertension, heredity, vascular injury, and the like.  
      Atherosclerosis can be treated in a variety of ways, including drugs, bypass surgery, and a variety of catheter-based approaches which rely on intravascular widening or removal of the atheromatous or other material occluding the blood vessel. Particular catheter-based interventions include angioplasty, atherectomy, laser ablation, stenting, and the like. For the most part, the catheters used for these interventions must be introduced over a guidewire, and the guidewire must be placed across the lesion prior to catheter placement. Initial guidewire placement, however, can be difficult or impossible in tortuous regions of the vasculature. Moreover, it can be equally difficult if the lesion is total or near total, i.e. the lesion occludes the blood vessel lumen to such an extent that the guidewire cannot be advanced across the lesion.  
      To overcome this difficulty, forward-cutting atherectomy catheters have been proposed. Such catheters usually can have a forwardly disposed blade (U.S. Pat. No. 4,926,858) or rotating burr (U.S. Pat. No. 4,445,509). While effective in some cases, these catheter systems, even when being advanced through the body lumen with a separate guidewire, have great difficulty in traversing through the small and tortuous body lumens of the patients and reaching the target site.  
      For these reasons, it is desired to provide devices, kits, and methods which can access small, tortuous regions of the vasculature and which can remove atheromatous, thrombotic, and other occluding materials from within blood vessels. In particular, it is desired to provide atherectomy systems which can pass through partial occlusions, total occlusions, stenosis, and be able to macerate blood clots or thrombotic material. It is further desirable that the atherectomy system have the ability to infuse and aspirate fluids before, during, or after crossing the lesion. At least some of these objectives will be met by the devices and methods of the present invention described hereinafter and in the claims.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention provides systems and methods for removing occlusive material and passing through occlusions, stenosis, thrombus, and other material in a body lumen. More particularly, the present invention can be used for passing through stenosis or occlusions in a neuro, cardio, and peripheral body lumens. Generally, the present invention includes an elongate member, such as a hollow guidewire, that is advanced through a body lumen and positioned adjacent the occlusion or stenosis. A tissue removal assembly is positioned at or near a distal tip of the hollow guidewire to create an opening in the occlusion. In exemplary embodiments, the tissue removal assembly comprises a drive shaft having a distal tip that is rotated and advanced from within an axial lumen of the hollow guidewire. Once the guidewire has reached the lesion, the guidewire with the exposed rotating drive shaft may be advanced into the lesion (or the guidewire may be in a fixed position and the drive shaft may be advanced) to create a path forward of the hollow guidewire to form a path in the occlusion or stenosis. To facilitate passing through the occlusion or stenosis, the distal end of the hollow guidewire can be steerable to provide better control of the creation of the path through the occlusion or stenosis. Optionally, the target site can be infused and/or aspirated before, during, and after creation of the path through the occlusion.  
      The hollow guidewire of the present invention has a flexibility, pushability and torqueability to be advanced through the tortuous blood vessel without the use of a separate guidewire or other guiding element. Additionally, the hollow guidewire may be sized to fit within an axial lumen of a conventional support or access catheter system. The catheter system can be delivered either concurrently with the advancement of the hollow guidewire or after the hollow guidewire or conventional guidewire has reached the target site. The position of the hollow guidewire and catheter system can be maintained and stabilized while the drive shaft is rotated and translated out of the axial lumen of the hollow guidewire. The distal tip of the drive shaft can be deflected, coiled, blunted, flattened, enlarged, twisted, basket shaped, or the like. In some embodiments, to increase the rate of removal of the occlusive material, the distal tip is sharpened or impregnated with an abrasive material such as diamond chips, diamond powder, glass, or the like.  
      The drive shaft can be a counter-wound guidewire construction or be composed of a composite structure comprising a fine wire around which a coil is wrapped. The counter-wound or composite constructions are more flexible than a single wire drive shaft and can provide a tighter bending radius while still retaining the torque transmitting ability so that it can still operate as a lesion penetration mechanism.  
      In a specific configuration, the drive shaft has spiral threads or external riflings extending along the shaft. The spirals typically extend from the proximal end of the shaft to a point proximal of the distal tip. As the drive shaft is rotated and axially advanced into the occlusive material (concurrently with the hollow guidewire body or with the hollow guidewire body substantially stationary), the distal tip creates a path through the occlusion and removes the material from the body. The spirals on the shaft act similar to an “Archimedes Screw” and transport the removed material proximally through the axial lumen of the hollow guidewire and prevents the loose atheromatous material from escaping into the blood stream.  
      Systems and kits of the present invention can include a support system or access system, such as a catheter having a body adapted for intraluminal introduction to the target blood vessel. The dimensions and other physical characteristics of the access system body will vary significantly depending on the body lumen which is to be accessed. In the exemplary case, the body of the support or access system is very flexible and is suitable for introduction over a conventional guidewire or the hollow guidewire of the present invention. The support or access system body can either be for “over-the-wire” introduction or for “rapid exchange,” where the guidewire lumen extends only through a distal portion of the access system body. Optionally, the support or access system can have at least one axial channels extending through the lumen to facilitate infusion and/or aspiration of material from the target site. Support or access system bodies will typically be composed of an organic polymer, such as polyvinylchloride, polyurethanes, polyesters, polytetrafluoroethylenes (PTFE), silicone rubbers, natural rubbers, or the like. Suitable bodies may be formed by extrusion, with one or more lumens that extend axially through the body. For example, the support or access system can be a support catheter, interventional catheter, balloon dilation catheter, atherectomy catheter, rotational catheter, extractional catheter, laser ablation catheter, guiding catheter, stenting catheter, ultrasound catheter, and the like.  
      In use, the access system can be delivered to the target site over a conventional guidewire. Once the access system has been positioned near the target site, the conventional guidewire can be removed and the elongate member (e.g., hollow guidewire) of the present invention can be advanced through an inner lumen of the access system to the target site. Alternatively, because the elongate member can have the flexibility, pushability, and torqueability to be advanced through the tortuous regions of the vasculature, it is possible to advance the elongate member through the vasculature to the target site without the use of the separate guidewire. In such embodiments, the access system can be advanced over the elongate member to the target site. Once the elongate member has been positioned at the target site, the drive shaft is rotated and advanced into the occlusive material or the entire elongate member may be advanced distally into the occlusion. The rotation of the distal tip creates a path forward of the elongate member. In some embodiments the path created by the distal tip has a path radius which is larger than the radius of the distal end of the elongate member. In other embodiments, the path created by the distal tip has a path radius which is the same size or smaller than the radius of the elongate member.  
      One exemplary hollow guidewire for crossing an occlusion or stenosis within a body lumen comprises an hollow guidewire body comprising a proximal opening, a distal opening, and an axial lumen extending from the proximal opening to the distal opening. A rotatable drive shaft is disposed within the axial lumen, wherein a distal tip of the rotatable drive shaft is adapted to extend distally through the distal opening in the guidewire body. At least one pull wire extends through the axial lumen and is coupled to a distal end portion of the guidewire body. The pull wire(s) comprise a curved surface that substantially corresponds to a shape of an inner surface of the axial lumen.  
      In one preferred configuration, the hollow guidewire body is composed of a single, laser edged hypotube. In one configuration, a proximal portion of the hollow guidewire comprises one or more sections that comprise a constant pitch. A distal portion of the hollow guidewire may have at least one section that ha a pitch that decreases in the distal direction so as to increase a flexibility in the distal direction along the distal portion of the guidewire body.  
      In other configurations, the hollow guidewire body optionally comprises a section that comprises no helical windings and has a solid wall. In other configurations, the distal portion may have a pitch that is constant, or the pitch may increase in the distal direction. In many embodiments, the hollow guidewire body will have at least one section that has a right-handed coils and at least one section that has left handed coils. In preferred configurations, the sections with the right handed coils alternate with the sections that have the left handed coils.  
      The dimensions of the hollow guidewires of the present invention will vary but the largest radial dimension (e.g., outer diameter) is typically between approximately 0.009 inches and 0.040 inches, preferably between approximately 0.035 inches and approximately 0.009 inches, more preferably between approximately 0.024 inches and 0.009 inches, and most preferably between approximately 0.013 and approximately 0.014 inches. A wall thickness of the hollow guidewires of the present invention is typically between approximately 0.001 inches and approximately 0.004 inches, but as with the other dimensions will vary depending on the desired characteristics of the hollow guidewire. The construction of the hollow guidewire will typically provide a 1:1 torqueability and the hollow guidewire will have the torqueability, pushability, and steerability to be advanced through the body lumen without the need of an additional guidewire or other guiding element.  
      A distal end portion of the hollow guidewire may comprise a plurality of openings or thinned portions that extend circumferentially or radially about at least a portion of the distal end portion of the guidewire body. A rib or other supporting structure will be disposed between each of the openings so as to provide structural support to the distal end portion. The plurality of openings or thinned portions may be used to increase the flexibility and/or bendability of the distal end portion, such that when the pull wires are actuated, the distal end portion is able to deflect without causing kinking in the distal end portion. The distal end portion may also include one or more radiopaque markers to assist in the fluoroscopic tracking of the hollow guidewire.  
      The hollow guidewires of the present invention may comprise only a single pull wire. In other embodiments, the hollow guidewire comprises two or more pull wires. The pull wires of the present invention may optionally be coated with Teflon® so as to reduce the friction coefficient of the surface and to reduce twisting of the pull wires. As noted above, the pull wires preferably comprise a curved surface that substantially corresponds to an inner surface of the axial lumen of the hollow guidewire. By providing a surface that substantially corresponds to a shape in the inner surface of the axial lumen, the pull wires are able to move radially outward away from the rotating drive shaft. The increased distance away from the center of the axial lumen provides a greater clearance between the pull wires and the rotating drive shaft, while maintaining a thickness and width of the pull wire.  
      The pull wires may take on a variety of cross-sectional shapes, but the pull wires typically typically have either a D-shape, crescent shape, or an oval shape. As can be appreciated, other embodiments of the pull wires may have a cross-section that is circular, substantially flattened, substantially rectangular, or the like.  
      In preferred embodiments, in addition to the curved surface that substantially corresponds to the inner surface of the axial lumen, the pull wires typically comprise a flat surface that is adapted to be adjacent the rotating drive shaft. Since the flat surface of the pull wire will provides only a single point of contact with the rotating drive shaft, there is a reduced friction between the pull wire and the drive shaft and there is a reduced chance that the rotating drive shaft gets tangled with the pull wire.  
      The rotatable drive shaft of the present invention may be axially movable and rotatable within the axial lumen of the hollow guidewire body. Optionally, the rotatable drive shaft may be coated with Teflon® or other materials to improve the rotation of the drive shaft within the axial lumen. The hollow guidewire may comprise a rotating mechanism, such as a rotary drive motor, to control the rotation of the drive shaft. The rotating mechanism can be coupled to the proximal end of the drive shaft to rotate the drive shaft. Optionally, an actuator may be used to control the axial movement of the drive shaft and/or the rotation of the drive shaft. Activation of the actuator moves the drive shaft proximally and distally within the axial lumen of the hollow guidewire. The hollow guidewire may comprise an additional actuator to control the steering or deflection of a distal portion of the hollow guidewire so as to assist in navigating the hollow guidewire through the body lumen.  
      The hollow guidewires of the present invention may comprise a removable housing coupled to the proximal portion of the hollow guidewire body. The removable housing may comprise a connector assembly that allows for infusion or aspiration, the actuator(s) (for controlling the rotation, axial movement of the drive shaft and/or steering of the distal end portion of the hollow guidewire body), a rotating member (e.g., drive motor), a control system, and/or a power supply. The removable housing allows for advancement of a catheter system over the hollow guidewire. Once the catheter or other elongate body is advanced over the hollow guidewire, the housing may be reattached so as to allow for actuation of the drive shaft.  
      In another aspect, the present invention provides a hollow guidewire that comprises a hypotube that comprises a proximal portion and a distal portion. At least a part of the distal portion of the hypotube comprise helical windings formed thereon so that the distal portion of the hypotube is more flexible than the proximal portion. While not described in detail herein, it should be appreciated that in other embodiments, the hollow guidewire may be comprised of a braided polymer, carbon, or other composite materials, and the hollow guidewires of the present invention are not limited to hypotubes.  
      In such configurations, the proximal portion of the hypotube will have a solid wall or helical windings that have a pitch that is larger than a pitch of the distal portion. Typically, a pitch of the helical windings on the distal portion decreases in the distal direction so that a flexibility of the distal end portion increases in the distal direction. Consequently, the proximal portion is the stiffest, an intermediate portion is less stiff, and the distal end is the most flexible. In other embodiments, the pitch may be constant throughout at least a portion of the distal portion, may increase in the distal direction, the pitch may vary throughout the distal portion, or the like.  
      The distal portion of the hypotube hollow guidewire may optionally comprise a plurality of ribs and openings or thinned portions that extend circumferentially about at least a portion of the distal end portion of the guidewire body. The distal portion may also comprise one or more radiopaque markers thereon.  
      Similar to the other embodiments, the hypotube hollow guidewire may comprise one or more pull wires. The pull wires preferably comprise a curved surface that substantially corresponds to an inner surface of the axial lumen of the hypotube hollow guidewire, but other conventional shaped pull wires that don&#39;t substantially correspond to the inner surface of the axial lumen may also be used. The pull wire may be coupled to a removable proximal housing that is coupled to the proximal portion of the hypotube hollow guidewire body. A removable housing may be coupled to the hollow guidewire and may comprise a connector assembly that allows for infusion or aspiration, one of more actuators (for controlling the rotation, axial movement of the drive shaft and/or steering of the distal end portion of the hypotube hollow guidewire body), a rotating member (e.g., drive motor), a control system, and/or a power supply.  
      In a further aspect, the present invention provides a steerable guidewire comprising a hollow guidewire body that comprises a proximal end, a distal end, and an axial lumen that extends to the distal end. At least a portion of a tissue removal assembly is positioned at or near the distal end of the guidewire body. At least one pull wire extends through the axial lumen of the hollow guidewire body and is coupled at or near the distal end of the hollow guidewire body. A proximal force on the pull wire steers the distal end of the hollow guidewire.  
      The tissue removal assembly may be fixedly or movably disposed at the distal end of the hollow guidewire body. If the tissue removal assembly is movable, the tissue removal assembly may be movable from a first, axially retraced position in which the tissue removal assembly is disposed within the axial lumen of the hollow guidewire body to a second position in which the tissue removal assembly is positioned beyond the distal end of the guidewire body.  
      The tissue removal assembly typically comprises a rotatable drive shaft that has a shaped distal tip. In other embodiments, however, the tissue removal assembly may comprise a laser, an RF electrode, a heating element (e.g., resistive element), an ultrasound transducer, or the like. A lead of the tissue removal assembly may extend from proximally through an axial lumen of the hollow guidewire body.  
      In one preferred configuration, the hollow guidewire body is composed of a single hypotube. The hollow guidewire body optionally comprises a helical coil or solid wall tubular proximal portion integrally formed with the distal end portion. The distal end portion may comprise helical windings formed thereon. A pitch between adjacent helical windings on the distal portion decreases in the distal direction so as to increase a flexibility in the distal direction along the distal portion of the guidewire body. In other embodiments, the distal portion may have one or more sections that have a pitch that is constant throughout the distal portion, a pitch that increases in the distal direction, or the like.  
      A distal end portion of the hollow guidewire may comprise a plurality support ribs and openings or thinned portions that extend circumferentially about at least a portion of the distal end portion of the guidewire body. The plurality of openings or thinned portions may be used to increase the flexibility and/or bendability of the distal end portion, such that when the pull wires are actuated, the distal end portion is able to deflect without kinking of the distal end portion. The distal end portion may also include one or more radiopaque markers to assist in the fluoroscopic tracking of the hollow guidewire.  
      Similar to the other embodiments, the hollow guidewire may comprise one or more pull wires. The pull wires preferably comprise a curved surface that substantially corresponds to an inner surface of the axial lumen of the hollow guidewire, but other conventional shaped pull wires that don&#39;t substantially correspond to the inner surface of the axial lumen may also be used. The pull wire may be coupled to a removable proximal housing that is coupled to the proximal portion of the hollow guidewire body. The removable housing may comprise a connector assembly that allows for infusion or aspiration, one of more actuators (for controlling the rotation, axial movement of the drive shaft and/or steering of the distal end portion of the hollow guidewire body), a rotating member (e.g., drive motor), a control system, and/or a power supply.  
      In yet another aspect, the present invention provides a hollow guidewire that comprises a proximal portion and a distal portion. At least a part of the distal portion comprises helical windings that have a pitch between adjacent windings that decreases in the distal direction so that a distal end of the hollow guidewire is more flexible than the proximal portion of the hollow guidewire.  
      In yet another aspect, the present invention provides a method of crossing an occlusion or stenosis within a body lumen. The method comprises positioning an hollow guidewire having a drive shaft in the body lumen. The drive shaft is rotated. The drive shaft is moved from a retracted configuration to an expanded configuration. In the expanded configuration, the drive shaft may be used to create a path that is at least as large as a largest radial dimension (e.g., diameter) of the distal end of the hollow guidewire The hollow guidewire body and/or the drive shaft may then advanced into the occlusion or stenosis to create the path in the occlusion or stenosis.  
      In another aspect, the present invention provides a method of crossing an occlusion or stenosis within a body lumen. The method comprises advancing a guidewire through the body lumen. An access or support system is moved over the guidewire to the occlusion or stenosis. The guidewire is removed from the body lumen and exchanged with a steerable hollow guidewire having tissue removal assembly. The tissue removal assembly may then be used to remove at least a portion of the occlusion. For example, in one configuration the tissue removal assembly comprises a rotatable drive shaft. The drive shaft is rotated within a lumen of the hollow guidewire and is at least partially exposed through a distal opening in the hollow guidewire. The hollow guidewire and/or the drive shaft may be advanced to create a path through the occlusion or stenosis.  
      In another aspect, the present invention provides a kit. The kit has any of the hollow guidewire described herein and instructions for use that provide any of the methods described herein. In one configuration, the hollow guidewire comprises a tissue removal assembly, such as a rotatable drive shaft. The rotatable drive shaft has a shaped distal tip that is removably received within the axial lumen of the hollow guidewire. The instructions for use in passing occlusions or stenosis in a body lumen comprise rotating the inner wire within the steerable hollow guidewire and advancing the hollow guidewire and drive shaft or only advancing the rotating drive shaft into the occlusive or stenotic material to create a path through the occlusive or stenotic material. A package is adapted to contain the hollow guidewire, rotatable wire, and the instructions for use. In some embodiments, the instructions can be printed directly on the package, while in other embodiments the instructions can be separate from the package.  
      These and other aspects of the invention will be further evident from the attached drawings and description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an elevational view of a system of the present invention;  
       FIG. 2  shows manual manipulation of a drive shaft of the present invention;  
       FIG. 3  shows a distal end of the elongate member and a distal tip of a drive shaft of the present invention;  
       FIG. 3A  is a cross sectional view of the device  FIG. 3 ;  
       FIG. 4  illustrates another embodiment of a hollow guidewire of the present invention.  
       FIG. 5A  is a cross-sectional view of a hollow guidewire that comprises a drive shaft and a flattened or rectangular pull wire.  
       FIG. 5B  is a cross sectional view of a hollow guidewire that comprises a drive shaft and a shaped pull wire.  
       FIG. 5C  is a cross-sectional view of an embodiment that comprises a plurality of spaced, shaped pull wires.  
       FIG. 6  illustrates another embodiment of a hollow guidewire that includes a plurality of openings or thinned portion in the distal end portion that correspond to the number of pull wires.  
       FIG. 7  illustrates one exemplary embodiment of a hollow guidewire that comprises left hand coil portions and right hand coil portions, and a coil disposed at the distal tip.  
       FIG. 7A  to  7 C are cross sectional views at A-A, B-B, and C-C of a distal portion of the hollow guidewire of  FIG. 7 , respectively.  
       FIGS. 8A and 8B  are helical coils that have a similar pitch but a different kerf.  
       FIG. 9  illustrates embodiment of a hollow guidewire that comprises a window formed in the distal portion of the hollow guidewire.  
       FIG. 9A  to  9 C are cross sectional views at A-A, B-B, and C-C of the distal portion of the hollow guidewire of  FIG. 9 , respectively.  
       FIG. 10  shows a diamond chip embedded distal tip of the drive shaft;  
       FIG. 11A  shows a deflected distal tip in a position forward of the distal end of the elongate member;  
       FIG. 11B  shows the flexible deflected distal tip in a fully retracted position within the axial lumen of the elongate member;  
       FIG. 11C  shows a deflected distal tip in a retracted position with the distal tip partially extending out of the elongate member;  
       FIG. 12A  shows a sharpened deflected distal tip extending out of the elongate member;  
       FIGS. 12B and 12C  show the cutting edges on the deflected distal tip of  FIG. 12A ;  
       FIG. 12D  shows the distal tip deflected off of the longitudinal axis of the drive shaft;  
       FIGS. 12E and 12F  is a partial cut away section of two counter-wound drive shafts of the present invention;  
       FIG. 12G  shows the relative flexibility between a conventional drive shaft and a counter-wound drive shaft of the present invention;  
       FIGS. 13A  to  13 C illustrate a method of forming the deflected distal tip using a fixture;  
       FIGS. 14A-14K  show a variety of tip configurations;  
       FIG. 14L  shows a distal tip having a flattened and twisted configuration;  
       FIGS. 14M-14P  show an exemplary method of manufacturing the distal tip of  FIG. 14L ;  
       FIG. 15  shows a drive shaft having spirals or external riflings which facilitate the proximal movement of the removed occlusive or stenotic material;  
       FIG. 16  shows a linkage assembly between the motor shaft and the drive shaft;  
       FIGS. 17A and 17B  show an alternative linkage assembly coupling the motor shaft and the drive shaft;  
       FIGS. 18-20  show a luer connection assembly which couples the elongate member to the housing;  
       FIG. 21  shows a system having an access system, a hollow guidewire with a deflectable distal end, and a drive shaft;  
       FIGS. 22A  to  22 E illustrate a method of the present invention;  
       FIGS. 23A  to  23 E illustrate another method of the present invention;  
       FIGS. 24A  to  24 B illustrate yet another method of the present invention; and  
       FIG. 25  shows a kit of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The systems, devices and methods according to the present invention will generally be adapted for the intraluminal treatment of a target site within a body lumen of a patient, usually in a coronary artery or peripheral blood vessel which is occluded or stenosed with atherosclerotic, stenotic, thrombotic, or other occlusive material. The systems, devices and methods, however, are also suitable for treating stenoses of the body lumens and other hyperplastic and neoplastic conditions in other body lumens, such as the ureter, the biliary duct, respiratory passages, the pancreatic duct, the lymphatic duct, and the like. Neoplastic cell growth will often occur as a result of a tumor surrounding and intruding into a body lumen. Removal of such material can thus be beneficial to maintain patency of the body lumen. While the remaining discussion is directed at passing through atheromatous or thrombotic occlusive material in a coronary artery, it will be appreciated that the systems and methods of the present invention can be used to remove and/or pass through a variety of occlusive, stenotic, or hyperplastic material in a variety of body lumens.  
      An apparatus  10  embodying features of the present invention is illustrated in  FIG. 1 . The apparatus  10  generally includes a housing  12  coupled to an elongate member  14  which has a proximal end  16 , a distal end  18 , and an axial lumen  20  therethrough. The apparatus may comprise a tissue removal assembly, such as a rotatable drive shaft  22 , for removing tissue and creating a path through the body lumen. The drive shaft  22  is movably received within the axial lumen  20  of the elongate member  14  and may be rotated and moved axially (as shown by arrows  23 ,  25 ). The distal tip  24  of the drive shaft  22  may have a shaped profile such that movement or positioning of the distal tip  24  beyond the distal end  18  of the elongate member and rotation of the drive shaft  22  may be used to create a cutting path forward of the distal end of the elongate member  14  for passing through the occlusive or stenotic material in the body lumen. In most configurations, wire leads  29  couple a drive motor  26  to a control system  27  and a power supply  28 . In some embodiments, the power supply  28  is covered with a plastic sheath cover (not shown) so as to maintain a sterile environment.  
      The drive motor  26  is attachable to a proximal end of the drive shaft  22  to move (i.e., rotate, translate, reciprocate, vibrate, or the like) the drive shaft  22  and shaped distal tip  24 . An actuator or input device  82  is attached to the housing  12  to actuate the movement (e.g., control the rotation and/or axial movement) of the drive shaft  22 . While not shown, an additional actuator or input device may be attached to housing  12  to control the deflection of a distal portion of the elongate member  14 . The proximal end  16  of elongate member  14  is coupled to the housing  12  through a connector assembly  30 . The connector assembly  30  limits the motion of the elongate member  14  while allowing the drive shaft  22  to rotate and translate within the elongate member  14 . Optionally, some embodiments of the connector assembly  30  includes an aspiration or infusion port (not shown) for facilitating fluid exchange (e.g., delivery or removal) at the target site through the axial lumen  20 .  
      As shown in  FIG. 2 , in order to macerate clots and to penetrate soft lesions, some drive shafts  22  of the present invention can be configured to be manually rotated. In such embodiments, the proximal end of the drive shaft  22  can be grasped between the fingers and manually turned to rotate the distal tip  24  (shown schematically as a box). The proximal end can be optionally fit with a knurled knob  21  or other mechanism which allows manual manipulation of the proximal end of the drive shaft  22 .  
      An exemplary embodiment of the elongate member  14  is best seen in FIGS.  3  to  9 C. The elongate member  14  is preferably a flexible, hollow guidewire that has the flexibility, pushability, and torqueability to allow a user to advance the hollow guidewire directly through a tortuous blood vessel to the target site. Because of the high columnar strength of the hollow guidewire  14  there is typically no need for a separate guidewire to advance the hollow guidewire  14  to the lesion at the target site.  
      In the exemplary embodiment illustrated in  FIG. 3 , the hollow guidewire has an helically wound elongated shaft which defines the axial lumen  20  that receives the drive shaft  22 . The axial lumen  20  may further be used for infusion or aspiration. The hollow guidewire  14  includes a proximal tube  32 , an intermediate coil  34 , and a distal coil tip  36 . In some embodiments the intermediate coil  34  is made of a stainless steel or nitinol coil, while the distal coil tip  36  is composed of a flexible, radiopaque coil, such as platinum-iridium. As shown in  FIG. 3 , the intermediate coil  34  may be threadedly engaged with the proximal tube  32  and threadedly engaged with the distal tip  36 . It will be appreciated, however, that the intermediate coil  34  can be connected to the proximal tube  32  and distal coil tip  36  by any conventional means, e.g. solder, adhesive, or the like. The proximal tube  32  of the hollow guidewire  14  can be coupled to a vacuum source or a fluid source (not shown) such that the target site can be aspirated or infused during the procedure, if desired.  
      Hollow guidewire  14  is typically sized to be inserted through coronary, neuro, or peripheral arteries and can have a variety of diameters. The largest radial dimension (e.g., outer diameter) of the hollow guidewire is typically between approximately 0.009 inches and 0.040 inches, preferably between approximately 0.009 inches and 0.035 inches, and more preferably between approximately 0.009 inches and 0.024 inches, and most preferably between about 0.013 inches and approximately 0.014 inches so as to ensure compatibility with existing interventional cardiology catheters and stent systems. The length of the hollow guidewire  14  may be varied to correspond to the distance between the percutaneous access site and the target site, but is typically about five feet in length. For example, for a target site within the heart that is being accessed through the femoral artery, the hollow guidewire will typically have a length of approximately 175 cm. It should be noted however, that other embodiments of the hollow guidewire  14  may have dimensions that are larger or smaller than the above described embodiments and the present invention is not limited to the above recited dimensions.  
      Referring now to  FIG. 3A , a cross section of the embodiment of  FIG. 3  is shown. An inner tube  38  and outer tube  40  are positioned around intermediate coil and distal coil tip  34 ,  36  to provide a flexible, structural support which prevents liquids from moving between the blood vessel and the axial lumen of the elongate member  14 . A reinforcing pull wire  42  can be positioned between the inner tube  38  and the coils  34 ,  36  to provide for deflection or steering of the distal end  18 . The reinforcing pull wire  42  can be formed of a material having sufficient strength so that a thin profile is possible. For example, the reinforcing wire can be an at least partially flattened strip of stainless steel that can retain its shape until it is re-shaped to a different configuration. In one configuration, the reinforcing pull wire  42  is soldered or otherwise connected to the distal end of coil tip  36  and the remainder of the reinforcing pull wire  42  extends proximally through axial lumen  20  to the housing  12 . Manipulation of an actuator or the proximal end of the reinforcing pull wire  42  that causes axial movement of the pull wire  42  allows the user to deflect or steer the distal end  18  without permanently impairing the inner structure of the hollow guidewire  14 . The steerable distal end  18  provides a user with greater intraluminal control of removing the occlusive or stenotic material from the blood vessel and also aids in navigating the hollow guidewire to the target site. In another configuration, the reinforcing pull wire is  42  can be soldered or otherwise connected to both the distal end and to the junction between coils  34 ,  36 . Therefore, if the coils  34 ,  36 , break, the attached reinforcing pull wire  42  can prevent the coils  34 ,  36  from detaching from the apparatus  10 . A more complete description of one hollow guidewire encompassed by the present invention can be found in commonly owned U.S. patent application Ser. No. 09/030,657, filed Feb. 25, 1998, the complete disclosure of which was previously incorporated by reference.  
       FIG. 4  illustrates another embodiment of a hollow guidewire  14  that is encompassed by the present invention. In the embodiment of  FIG. 4 , the hollow guidewire  14  is composed of a single hypotube  37 . A radiopaque marker  33  may be disposed on the distal portion  39  of the hypotube  37 , and typically at the distal tip. At least the distal portion  39  of the hypotube  37  may be laser edged to create a plurality of helical windings or spirals  43 . The helical windings  43  may have the same pitch through at least one section of the distal portion  39  (not shown) or the helical windings  43  may have a variable pitch through at least one section of distal portion  39 . As can be appreciated, the pitch between adjacent windings will affect the flexibility of hypotube  37 , and the pitch may be selected by the manufacturer depending on the desired characteristics of the hollow guidewire body  14 . Because of the flexible nature of the present invention, the manufacturer may provide different configurations of the hollow guidewire so as to enhance the performance (e.g., provide personalized levels of torque response, flexibility, and deflection) of the guidewire body for the specific procedure.  
      In one configuration, the pitch between the helical windings  43  decreases in the distal direction so as to be increasingly flexible in the distal direction. Consequently, the distal portion  39  of the hypotube  37  will have an increasing flexibility in the distal direction. Advantageously, because the distal portion  39  is integrally formed with the proximal portion  45 , there are no joints and there is an improved reliability and a reduced chance of disengagement between the distal portion  39  and the proximal portion  45 . It may be desirable to have sections of the guidewire body to have no helical cuts, or to have laser cuts that have a pitch that increases in the distal direction so as to provide less flexibility over a portion of the hollow guidewire. The less flexible portion may be at the proximal portion, an intermediate portion, at or near the distal end of the hollow guidewire, or any combination thereof. For example, in one configuration, a proximal portion  45  of the hypotube may optionally have a solid wall with no laser cuts or helical spirals, and the remainder of the hypotube may have a helical laser edging (which may or may not have a decreasing pitch in the distal direction).  
      The laser cuts may extend all the way from the proximal end to the distal tip or the laser cuts may extend through less than all of the hypotube. The laser cuts used to create the helical windings may extend completely through the wall of the hypotube or it may extend only partially through the hypotube wall so as to create thinner wall portions (e.g., grooves).  
      Because the embodiment of  FIG. 4  is composed of a single hypotube, there is a no need for the inner and outer support tubes  38 ,  40 . Consequently, the effective outer diameter of the hypotube may be reduced and the diameter or the inner axial lumen  20  will be effectively increased to accommodate a larger drive shaft or pull wire(s)  42 .  
      Similar to the embodiment of  FIG. 3  and  3 A, the guidewire  14  shown in  FIG. 4  may comprise one or more reinforcing or pull wires  42 . The pull wires  42  may comprise a plurality of different shapes, including, but not limited to, a rectangular wire, a flat wire, a crescent shape, a D-shape, an oval shape, or the like. As shown in  FIGS. 5A  to  5 C, because there is no inner support tube  38  to separate the pull wire(s)  42  from the drive shaft  22 , the pull wire(s)  42  may be in direct contact with the drive shaft  22 . Applicants have found that rotation of the drive shaft  22  may cause twisting in the pull wires, which increases the chance of the pull wire  42  breaking. To reduce the friction between the pull wire  42  and the drive shaft  22 , the pull wire  42  and/or the drive shaft  22  may be coated with Teflon® so that the drive shaft is able to rotate without causing substantial twisting of the pull wire  42 .  
      Optionally, the pull wire may also be shaped so as to better conform with an inner surface  47  of the hollow guidewire  14 . Substantially conforming a surface  49  of the pull wire  42  with the inner surface  47  of the hollow guidewire  14  increases the space between the rotating drive shaft  22  and the pull wire(s)  42  by allowing the pull wire  42  to be moved radially outward away from the drive shaft  22  and to contact the inner surface  47  at a tangential point. As shown in  FIG. 5B , the surface  49  may be curved so as to conform to the curved inner surface  47  of the hypotube  37 . The radius of curvature of the pull wire will typically be less than or equal to the radius of curvature of the inner surface  47  of hollow guidewire  14  so as to provide only one point of contact between the hollow guidewire and the pull wire  42 .  
      The additional space between the drive shaft and the pull wire reduces the contact between the drive shaft  22  and the pull wire  42  and further reduces the possibility of breaking of the pull wire  42 . For example, as shown in  FIGS. 5A and 5B , for pull wires  42  that have substantially the same thickness T and width W, the pull wire with a surface  49  that conforms to the inner surface  47  ( FIG. 5B ) provides greater clearance between the drive shaft  22  and the pull wire  42  than a flat or rectangular pull wire. Additionally, the D-shaped pull wire will typically contact the inner surface  47  at one point, which reduces the friction between the pull wire and the guidewire body.  
      Optionally, pull wire  42  may have a flattened surface  200  adjacent the drive shaft  22 . Applicants have found that having a flat surface facing the rotating drive shaft further reduces the binding and friction between the pull wire  42  and the drive shaft  22  because the rotating drive shaft would only contact the pull wire at a tangential point, therefore minimizing friction and a possibility of twisting between the pull wire and drive shaft. In alternative embodiments, however, surface  200  may be curved, if desired, but as noted, such embodiments tend to have an increased chance of tangling.  
      The pull wire  42  will generally have a thickness T of between about 0.002 inches and about 0.040 inches and width W between about 0.002 inches and 0.080 inches. As can be appreciated, the dimensions of pull wire  42  will depend on the dimension of the inner lumen and the largest radial dimension of the hollow guidewire  14 , and the only requirement is that the pull wire fit within the inner lumen of the hollow guidewire.  
      When the pull wire is moved proximally, the distal tip will deflect. To improve the deflection of the distal tip of the hollow guidewire, the hypotube may optionally comprise one or more set of circumferential openings or thinned portions  202  and support ribs  204  on the distal portion of the hypotube  37 , distal of the helical windings  43 . If the hollow guidewire only comprises ones pull wire  42 , the hollow guidewire  14  will typically only comprise one set of support ribs  204  and circumferential openings or thinned portions  202  ( FIG. 4 ). But if the hollow guidewire comprises a plurality of pull wires  42  ( FIG. 5C ) the hollow guidewire  14  may comprise a corresponding number of sets of support ribs  204  and openings or thinned portions  202  ( FIG. 6 ).  
      The radial slots, openings, and/or thinned portions  202  may be formed on the hypotube through laser edging that removes at least a portion of the material from the hypotube. The openings  202  will extend around less than the entire circumference of the hypotube, but if the laser merely creates thinner regions, it may be possible to have the thinner region extend completely around the hypotube. In preferred embodiments, however, the thinner portions and openings  202  typically extend between about 25% of the guidewire body (e.g., 90 degrees) and about 75% (e.g., 270 degrees) of the guidewire body.  
       FIGS. 7 and 9  (not to scale) illustrate two additional hollow guidewire bodies  14  that encompass some of the novel aspects of the present invention. In the illustrated embodiments, a proximal portion  45  of the hollow guidewire  14  comprises one or more sections of constant pitch helical windings. Each of the sections  206 ,  208  vary to some degree from an adjacent section—e.g., either a different pitch from the adjacent section or one section has a left handed pitch and the other section has a right handed pitch. The sections may have the same number of helical windings or different number of helical windings. In one configuration, the hollow guidewire body comprises a first section  206  that spans 0.600 inches and has fifteen helical windings that have a pitch of 0.040 inches. The second section  208  spans 1.380 inches and has sixty-nine helical windings that have a pitch of 0.020 inches between the windings.  
      The adjacent helical windings is separated by a kerf. As shown in  FIGS. 8A and 8B , the kerf typically corresponds to a width of the laser beam used to create the cuts. Applicants have found that a smaller kerf ( FIG. 8B ) provides improved floppiness/flexibility and torqueability of the hollow guidewire. The kerf on the hollow guidewire body  14  of the present invention typically ranges from 0.0005″- 0.004″ preferably between about 0.001″ and about 0.002,″ but may be larger or smaller as desired.  
      Optionally, as noted above, the hollow guidewire body  14  may also comprises a section third section  210  that is distal to sections  206 ,  208  that comprises a pitch that decreases in the distal direction (or increases in the distal direction). The taper may be liner or non-linear. In one configuration, the variable pitch section  210  spans 7.872 inches and has  598  variable pitches in which the proximal pitch of the section is 0.020328 inches and the distal most pitch is 0.006 inches. As can be appreciated, the hollow guidewire body  14  may comprise any number sections, and the sections may have any desired taper to the pitch.  
      The hollow guidewire body typically has one or more sections  212  that do not have any coils formed thereon (e.g., solid walled throughout). Typically, the sections that do not have any coils formed thereon  212  are transition areas between adjacent sections  206 ,  208 ,  210 . Such transition areas  212  typically have a length between about 0.001 inches and 0.007 inches, but could be larger or smaller, if desired.  
      For any of the embodiments described herein, the helical coils of the hollow guidewire body  14  may be “left-handed” or “right-handed”. In some preferred embodiments, however, the different sections  206 ,  208 ,  210  of helical coils will have at least one left-handed coil section and at least one right-handed coil section. Typically, the left handed coil sections and the right handed coil sections are alternating along a length of the hollow guidewire body  141 . As can be appreciated, when a right handed torque is applied to a coil that comprises all right-handed coils, the coils will torque without substantial “opening” of the coils. However, if a left-handed torque is applied to the same right-handed coils, the coils will tend to open and may affect the 1:1 torque transmission through the guidewire body  14 . While the smaller kerf has been found to improve torque transmission, Applicants have found that having at least one left-handed section and at least one right-handed section further compensates for the opening of the coils when a torquing force is applied to the proximal end of the guidewire body. Consequently, similar amounts of torque may be transmitted to a distal tip of the hollow guidewire body when applying either a left-handed or right-handed torque.  
      Optionally, the hollow guidewire may comprise an integrally formed coil  214  at the distal tip. The distal coil  214  may be configured to threadedly receive a radiopaque coil (not shown), such as a platinum coil. The radiopaque coil may be soldered, glued, or otherwise attached to the distal coil  214  so as to provide a radiopaque marker for fluoroscopic tracking of the hollow guidewire body  14 . The distal coil  214  may have any desired length and pitch, but in one exemplary configuration, the distal coil  214  is 0.027 inches long and has 5.75 helical windings that have a kerf of 0.0028 inches and a pitch of 0.005 inches.  
      Similar to the embodiments illustrated in  FIGS. 4 and 6 , the embodiments of  FIGS. 7 and 9  may comprise a plurality of openings  202  and support ribs  204  to improve the bendability/deflectability of the distal portion of the guidewire body  14 . A support rib  204  will typically be disposed between each opening  202 . The openings  202  may take on a variety of different forms and may extend over any desired length of the distal portion. Each rib  204  along the distal portion may have a constant thickness in the axial direction or the ribs  204  may have a variable thickness along the axial length of the hollow guidewire body  14  (e.g., an axial thickness of a proximal most rib may be thicker or thinner than an axial thickness of a distal most rib). Moreover, each rib may extend completely around a circumference of the hollow guidewire body  14  or only around a portion of the hollow guidewire body. As shown in  FIGS. 7A  to  7 C and  9 A to  9 C, the support ribs  204  typically will extend between 100% (e.g., 360 degrees) and about 25% (e.g., 90 degrees) around the circumference of the hollow guidewire body  14 . The thinned portions  202  ( FIGS. 7C and 9C ) will typically extend between about 25% (90 degrees) and about 75% (e.g., 270 degrees) of the hollow guidewire body  14 .  
      For the embodiments of  FIG. 9 , if the ribs  204  extend around less than 100% of the circumference of the hollow guidewire, the pull wire (not shown) may be exposed through A window  216  created by the ribs  204  and openings  202 . In such embodiments, a flexible tubing  218  may be placed over the ribs  204  and openings  202  so as to protect the pull wire (shown in dotted lines in  FIGS. 9A  to  9 C). The flexible material may be comprised of a polymeric material, including, but not limited to polyethylene, Teflon®, or the like.  
       FIGS. 10-15  show various embodiments of the drive shaft  22  of the present invention. In most embodiments, the drive shaft  22  is a wire, a counter-wound multiple strand wire, or a plurality of braided wires having a body and a shaped distal tip  24 . The proximal end of the drive shaft  22  can be removably coupled to a rotatable motor shaft  48  ( FIGS. 16 and 17 A) or manually manipulated ( FIG. 2 ). The body of the drive shaft  22  extends through the elongate member  14  so that the distal tip  24  of the drive shaft is positioned near the distal end of the elongate member  14 . The detachable connection to the motor shaft  48  allows the drive shaft  22  and elongate member  14  to be detached from the motor shaft  48  and connector assembly  30  so that an access or support system can be placed over the elongate member  14  and advanced through the body lumen.  
      As shown in  FIG. 10  and  11 A- 11 C, the distal tip can be shaped or deflected from the longitudinal axis  50  to extend beyond the radius of the elongate member  14  such that rotation of the drive shaft  22  creates a path radius  52  that is as at least as large as the radius  54  of the distal end of the elongate member  14 . In other embodiments, the distal tip  24  will be deflected and shaped so as to create a path radius  52  which is the same or smaller than the radius of the distal end of the elongate member  14  ( FIGS. 14B-14G ). For example, in one exemplary configuration shown in  FIG. 11C , a portion of the distal tip  24  extends beyond the distal end  18  of the elongate member when in the fully retracted position. When the drive shaft  22  is advanced out of the elongate member  14 , the flexible distal tip  24  maintains a deflected shape ( FIG. 11A ). In alternative configurations, it is contemplated that the deflection at the distal tip  24  can straighten somewhat under the force from the walls of the elongate member  14  when the drive shaft  22  is retracted into the elongate member  14  ( FIG. 11B ). Thus, in the axially retracted configuration, the drive shaft  22  will have a profile that is smaller than the radius of the distal tip of the elongate member. When the drive shaft is advanced out of the distal end of the elongate member, the drive shaft will expand to an axially extended configuration in which the distal tip of the drive shaft  22  will have a profile that is larger than the axially retracted configuration, and in some embodiments will have a larger profile than the distal end of the elongate member  14 .  
      Referring again to  FIG. 10 , in some configurations a layer of abrasive material  56  can be attached and distributed over at least a portion of the distal tip  24  of the drive shaft  22  so that the abrasive material  56  engages the stenotic or occlusive material as the drive shaft  22  is advanced into the occlusion or stenosis. The abrasive material  56  can be diamond powder, diamond chips, fused silica, titanium nitride, tungsten carbide, aluminum oxide, boron carbide, or other conventional abrasive particles.  
      Alternatively, as shown in  FIGS. 12A-12D , the distal tip  24  of the drive shaft  22  can be sharpened to facilitate passing through the occlusion or stenosis. A distal edge of the tip  24  can be sharpened so as to define a cutting edge  58  which rotatably contacts the occlusive or stenotic material. In an exemplary embodiment illustrated in  FIGS. 12B-12C , a tip of the drive shaft can be sharpened to create a plurality of cutting edges  58 . Furthermore, as shown in  FIG. 12D  and as described above, the distal tip  24  can be deflected from its longitudinal axis  50  to create the cutting path radius  52  of the drive shaft  24  that is smaller, larger, or the same length as the radius of the elongate member  14 .  
      The drive shaft  22  can be composed of a shape retaining material, a rigid material, a flexible material, or can be composed of a plurality of materials. For example in some configurations, the drive shaft  22  can be comprised of nitinol, stainless steel, platinum-iridium, or the like. The distal tip  24  of the drive shaft  22  can have an enlarged tip, a preformed curve, or a preformed deflection ( FIG. 11A ).  FIGS. 12E and 12F  show exemplary embodiments of a counter-wound and composite drive shafts of the present invention. The counter-wound drive shaft  22  shown in  FIG. 12E  is made of a 0.004 inch OD center wire  67  having a right-hand wound surrounding wire  69  coiled around the center wire  67 . The surrounding wire  69  can be soldered to the center wire at both ends of the center wire. In the embodiment of  FIG. 12F , multiple strand wires  51  can be wound around a central coil  71  to form the drive shaft  22 . The counter-wound drive shafts are significantly more flexible than a single wire guidewire and allows for a tighter bending radius over conventional guidewire.  FIG. 12G  illustrates the flexibility of both a 0.007 inch OD single wire stainless steel wire drive shaft  22   a  and a 0.007 inch OD counter-wound stainless steel drive shaft  22   b . As shown by  FIG. 12G , the counter-wound drive shaft has better flexibility, while still maintaining its torqueability, maneuverability, and columnar strength.  
      Additionally, in some embodiments, the distal portion of the drive shaft  22  is radiopaque so that a physician can track the position of the drive shaft  22  using fluoroscopy. The drive shaft  24  typically has a diameter between approximately 0.010 inches and 0.005 inches. It should be appreciated that the dimension of the drive shaft will be slightly less than the inner diameter of the hollow guidewire so as to allow rotation without significant heat generation. Consequently, the dimensions of the drive shaft will vary depending on the relative inner diameter of the elongate member  14  and the present invention is not limited to the above described dimensions of the drive shaft.  
      In one embodiment, the distal tip  24  of the drive shaft is created using a shaped fixture  64 . As shown in  FIGS. 13A and 13B , the distal tip  24  is positioned on the fixture  64  and bent to a desired angle  66 . The distal tip  24  can be bent to almost any angle  66  between 0° degrees and 90° degrees from the longitudinal axis  50 , but is preferably deflected between 0° degrees and 50° degrees. As shown in  FIG. 13C , a sharpened edge  58  can be created on the distal tip using a wafer dicing machine used in the production of silicon microchips (not shown). The angle of the sharpened edge  58  can be almost any angle, but the angle is typically between 0° degrees and 45° degrees, and is preferably between approximately 8° degrees and 18° degrees. Naturally, it will be appreciated that a variety of methods can be used to manufacture the distal tip of the drive shaft and that the present invention is not limited to drive shafts produced by the described method.  
      As mentioned above, the distal tip  24  can take various shapes. One embodiment having a deflected distal tip  24  is shown in  FIG. 14A . In an exemplary configuration, the deflected tip is offset at an angle such that rotation of the drive wire  22  defines a profile or path that is at least as large as the outer diameter of the distal end of the elongate member  14 . As shown in  FIGS. 14B and 14C , in other embodiments, the tip can be deflected at other angles and may have a length that creates a path that is smaller or the same diameter as the distal end of the elongate member. The deflected distal tip can extend radially any feasible length beyond the perimeter or diameter of the elongate member  14 . It should be understood that the invention is not limited to a single deflected tip. For example, the drive shaft can comprise a plurality of deflected tips. Alternatively, the drive shaft may have a distal tip  24  that is twizzle shaped, spring shaped, twisted metal shaped ( FIG. 14D ), ball shaped ( FIG. 14E ), a discontinuous surface ( FIG. 14F ), or the like. Alternatively, the drive shaft may comprise a plurality of filaments ( FIG. 14G ), rigid or flexible brush elements, a plurality of coils, or the like.  
      The distal tip of the drive shaft can be configured optimally for the type of occlusion or stenosis to be penetrated. Some lesions are made up substantially of clot or thrombotic material that is soft and gelatinous.  FIGS. 14H and 14K  shows distal tip embodiments which may be used to macerate a soft clot, thrombotic material, or stenosis.  FIG. 14H  shows a distal tip  24  having a basket like construction which is made up of a plurality of strands  59  that are connected at their ends  61 ,  63 . In another embodiment illustrated in  FIG. 141 , the distal tip  24  can be composed of a plurality of strands  59  that are unconnected at their distal ends  63 . Additionally, the distal ends  63  of the strands  59  can be turned inward so that the distal ends  63  do not penetrate the body lumen when rotated.  FIG. 14J  shows a corkscrew spiral distal tip having a blunt distal end  63 .  FIG. 14K  shows a distal tip having a loop configuration.  
      In another exemplary embodiment shown in  FIG. 14L , the distal tip  24  of the drive shaft  22  can be flattened and twisted to create a screw like tip that can create a path through the occlusion. The flattened and twisted distal tip  24  can have a same width, a smaller width or a larger width than the drive shaft  24 . For example, in one configuration for a drive shaft having an outer diameter of 0.007 inches, the distal tip  24  can be flattened to have a width between approximately 0.015 inches and 0.016 inches, or more. It should be appreciated, however, that the distal tip can be manufactured to a variety of sizes.  
       FIGS. 14M-814P  show one method of manufacturing the flattened and distal tip of the present invention. The round drive shaft  22  ( FIG. 14M ) is taken and the distal end is flattened ( FIG. 14N ). The distal end can be sharpened ( FIG. 14O ) and twisted two or two and a half turns ( FIG. 14P ). If a different amount of twists are desired, the distal tip can be manufactured to create more (or less) turns.  
      In use, the distal tip  24  is rotated and advanced distally from a retracted position to an extended position into the soft material in the target lesion. If slow speed rotation is desired the user can rotate the drive shaft slowly by hand by grasping a knurled knob attached to the proximal end of the drive shaft ( FIG. 2 ). If high speed rotation is desired, the proximal end of the drive shaft  22  can be attached to the drive motor  26 . As the expanded wire basket tip is rotated, the tip macerates the soft clot and separates the clot from the wall of the body lumen. If a large diameter hollow guidewire working channel is used to deliver the drive shaft to the target area, the macerated clot can be aspirated through the guidewire working channel. Alternatively or additionally, a fluid, such as thrombolytic agents, can be delivered through the working channel to dissolve the clot to prevent “distal trash” and blockage of the vasculature with debris from the macerated clot.  
      As shown in  FIGS. 15 and 21  in some embodiments the drive shaft  22  can optionally have spiral threads or external riflings  64  which extend along the body  44 . As the drive shaft  22  is rotated and axially advanced into the atheromatous material, the distal tip  24  creates a path and removes the atheromatous material from the blood vessel. The rotating spirals  64  act similar to an “Archimedes Screw” and transport the removed material proximally through the axial lumen of the elongate member  14  and prevent the loose atheromatous material from blocking the axial lumen of the elongate member  14  or from escaping into the blood stream.  
      In use, drive shaft  24  is rotated and advanced to create a path distal of the elongate member  14  to create a path through the occlusion. The drive shaft  24  can be advanced and rotated simultaneously, rotated first and then advanced, or advanced first and then rotated. The drive shaft  22  is typically ramped up from a static position (i.e. 0 rpm) to about 5,000 rpm, 20,000 rpm with a motor. It should be noted, however, that the speed of rotation can be varied (higher or lower) depending on the capacity of the motor, the dimensions of the drive shaft and the elongate member, the type of occlusion to be bypassed, and the like. For example, if desired, the drive shaft can be manually rotated or reciprocated at a lower speed to macerate soft clots or to pass through lesions.  
      The distal tip of the drive shaft  22  can extend almost any length beyond the distal portion of the hollow guidewire. In most embodiments, however, the distal tip typically extends about 5 centimeters, more preferably from 0.05 centimeters to 5 centimeters, and most preferably between 0.05 centimeter and 2 centimeters beyond the distal portion of the hollow guidewire.  
      Referring now to  FIGS. 16, 17A , and  17 B, the motor shaft  48  and the proximal end  46  of the drive shaft  22  are coupled together with a detachable linkage assembly  70 . In one embodiment shown in  FIG. 16 , linkage assembly  70  has a first flange  72  attached to the motor shaft  48 . The first flange can be snap fit, snug fit, or permanently attached to the drive shaft  48 . A second flange  74  can be permanently or removably coupled to the proximal end  46  of the drive shaft  22  so that the first flange  72  of the motor shaft  48  can threadedly engage the second flange  74 . In some embodiments, the proximal end of the drive shaft  46  can be enlarged so as to improve the engagement with the second flange  74 . An o-ring  76  is preferably disposed within a cavity in the first flange  72  to hold the first flange  72  and second flange  74  in fixed position relative to each other.  
      As shown generally in  FIGS. 1 and 17 B, the motor  26  can be removably coupled to the housing  12 . To detach the motor  26  and power supply  28  from the drive shaft  22 , the user can unlock the luer assembly  30  so as to release the elongate member  14  from the housing  12 . The drive shaft  22  and elongate member  14  are then both free to move axially. The motor  26  can be moved proximally out of the housing  12  and the proximal end  46  of the drive shaft  22  can be detached from the motor shaft  48 . After the motor  26 , housing  12 , and luer assembly  30  have been uncoupled from the elongate member  14  and drive shaft  22 , a support or access system (not shown) can be advanced over the free proximal end of the elongate member  14 . Thereafter, the luer assembly and motor shaft  48  can be recoupled to the elongate member  14 .  
      In the embodiment shown in  FIGS. 17A and 17B , the-linkage assembly  70  includes a connecting shaft  78  that can be snugly fit over the motor shaft  48 . The connecting shaft  78  preferably tapers from a diameter slightly larger than the motor shaft  48  to a diameter of that of the approximately the proximal end  46  of the drive shaft  22 . In the embodiment shown, the connecting shaft  78  is coupled to the drive shaft through shrinkable tubing  80 . Because the connecting shaft  78  is snug fit over the motor shaft, (and is not threadedly attached to the drive shaft) the size of the connecting shaft  78  can be smaller than the linkage assembly  70 . While the exemplary embodiments of the connection assembly between the drive shaft and motor shaft have been described, it will be appreciated that drive shaft and motor shaft can be attached through any other conventional means. For example, the motor shaft  48  can be coupled to the drive shaft  22  through adhesive, welding, a snap fit assembly, or the like.  
      As shown in  FIG. 17B , the drive shaft  22  extends proximally through the housing  12  and is coupled to the motor shaft  48 . An actuator  82  can be activated to advance and retract the drive shaft  22 . In some embodiments, the motor is press fit into the actuator housing  12 . The drive shaft  22  is attached to the motor shaft  26  via o-rings such that the drive shaft  22  can be moved axially through axial movement of the actuator  82 .  
      In most embodiments, actuation of the drive motor  26  and power supply  28  (e.g. rotation of the drive shaft) will be controlled independent from advancement of the drive shaft  22 . However, while the actuator  82  is shown separate from the control system  27  and power supply  28  ( FIG. 1 ), it will be appreciated that actuator  82  and control system  27  can be part of a single, consolidated console attached to the housing  12  or separate from the housing  12 . For example, it is contemplated that that the drive shaft  22  can be rotated and advanced simultaneously by activation of a single actuator (not shown).  
      A connection assembly  30  is positioned on a proximal end of the housing to couple the elongate member  14  and the drive shaft  22  to the housing  12 . In a preferred embodiment shown in  FIGS. 18-20 , the connection assembly  30  is a detachable luer which allows the drive shaft  22  to be moved (e.g. rotated, reciprocated, translated) while the elongate member is maintained in a substantially static position.  FIG. 18  best illustrates an exemplary luer connection assembly  30  which couples the elongate member  14  and the housing  12 . The luer has a gland  86  which is rotatably connected to a fitting  88  and a tubular portion  90 . Rotation of the gland  86  rotates and torques the elongate member  14  while the elongate member  14  is advanced through the blood vessel. Fitting  88  is threaded into the gland  86  such that a distal end of the fitting engages an o-ring  92  and a surface wall  94  of the gland. The longitudinal axis  96  of the fitting  88  and gland  86  are aligned so as to be able to receive the axial lumen of the elongate member  14 . As the fitting  88  engages the o-ring  92 , the o-ring is compressed radially inward to squeeze and maintain the position of the elongate member  14 . Accordingly, as illustrated in  FIG. 19 , when the drive shaft  22  is rotated within the elongate member  14 , the o-ring  92  is able to substantially maintain the position and orientation of the elongate member  14 . Tubular portion  90  attached to the proximal end of the fitting  88  threadedly engages the housing  12  and enables the luer connection assembly  30  to be removed from the housing  12  ( FIG. 20 ). A more complete description of the connection assembly  30  can be found in commonly owned U.S. patent application Ser. No. 09/030,657, filed Feb. 25, 1998, the complete disclosure of which was previously incorporated by reference. It should be appreciated that the present invention is not limited to the specific luer assembly described. Any luer assembly can be used to connect the elongate member  14  to the housing  12 . For example, a Y-luer assembly (not shown) can be used with the system of the present invention to infuse or aspirate of fluids through the lumen of the hollow guidewire  14 .  
      As shown in  FIG. 21 , systems of the present invention can further include an access or support system  98 . The access or support system  98  can be an intravascular catheter such as a hollow guidewire support device, support catheter, balloon dilation catheter, atherectomy catheters, rotational catheters, extractional catheters, conventional guiding catheters, an ultrasound catheter, a stenting catheter, or the like. In an exemplary configuration shown in  FIG. 21 , the system includes an infusion or aspiration catheter which has at least one axial channel  100 , and preferably a plurality of axial channels  100  which extends through the catheter lumen  102  to the distal end of the catheter. The elongate member  14  and drive shaft  22  can be positioned and advanced through the lumen  102  of the catheter. The axial channel  20  of the elongate member  14  and/or the axial channels  100  of the catheter  98  can also be used to aspirate the target site or infuse therapeutic, diagnostic material, rinsing materials, dyes, or the like.  
      The access or support system can be guided by the elongate member to the target site in a variety of ways. For example, as illustrated in  FIGS. 22A  to  22 E, a conventional guidewire  104  can be advanced through the blood vessel BV from the access site ( FIG. 22A ). Once the guidewire  104  has reached the target site, the support or access system  98  can be advanced over the guidewire  104  ( FIG. 22B ). Alternatively, the guidewire  104  and support or access system  98  can be simultaneously advanced through the body lumen (not shown). Once the support or access system  98  has reached the target site, the conventional guidewire  104  can be removed and the hollow guidewire  14  having the drive shaft  22  can be introduced through the lumen  102  of the access system  98  ( FIG. 22C ). Even if the distal tip  24  of the drive shaft  22  is not fully retracted into the axial lumen  20 , the lumen  102  of the support or access system protects the blood vessel BV from damage from the exposed distal tip  22 . In most methods, the support or access system is positioned or stabilized with balloons, wires, or other stabilization devices  106  to provide a more controlled removal of the occlusive or stenotic material OM. Once the hollow guidewire  14  and drive shaft  22  have reached the target site, the drive shaft can be rotated and advanced into the occlusive or stenotic material OM to create a path ( FIGS. 22D and 22E ).  
      In another method of the present invention, the hollow guidewire  14  can be used to guide the support or access system to the target site without the use of a separate guide wire. The hollow guidewire  14  provides the flexibility, maneuverability, torqueability (usually 1:1), and columnar strength necessary for accurately advancing through the tortuous vasculature and positioning the distal end of the support or access system at the target site. The steerable distal portion can be deflected and steered through the tortuous regions of the vasculature to get to the target site. As shown in  FIG. 23A , the hollow guidewire is advanced through the tortuous blood vessel to the target site. Due to the small size of the guidewire  14  relative to the blood vessel, even if the distal tip  24  of the drive shaft  22  extends partially out of the hollow guidewire  14 , any potential damage to the blood vessel BV will be minimal.  
      Once the hollow guidewire reaches the target site within the blood vessel, the motor shaft  48 , luer assembly  30 , and housing  12  can be detached from the proximal end  46  of the drive shaft  22  so that the support or access system can be placed over the hollow guidewire. After the motor has been detached, the support or access system can be advanced over the guidewire and through the body lumen to the target site ( FIG. 23B ). To reattach the drive motor  26  to the drive shaft  22 , the hollow guidewire  14  and drive shaft  22  are inserted through the luer assembly  30 . The luer assembly  30  is tightened to lock the position of the hollow guidewire  14 . The drive shaft  22  will extend proximally through the housing  12  where it can be recoupled to the motor shaft using the above described linkage assemblies  70  or other conventional linkage assemblies. Once at the target site, the position of the support or access system  98  can be stabilized by a balloon, wires, or other stabilizing devices  106 , and the drive shaft  22  can be rotated and advanced into the occlusive or stenotic material OM ( FIGS. 23C and 23D ). The rotation of the drive shaft creates a path forward of the distal end  18  of the hollow guidewire  14 . As noted above, the path can have the same diameter, smaller diameter, or larger diameter than the distal end of the hollow guidewire. Before, during, or after the rotation of the drive shaft, the user can steer or deflect the distal end  18  of the hollow guidewire  14  to guide the hollow guidewire to the desired location within the blood vessel. For example, as shown in  FIG. 23E , once a portion of the occlusion or stenosis has been removed, the distal end  18  of the hollow guidewire  14  can be guided to angle the distal end so that the drive shaft is extended into a different portion of the occlusive or stenotic material OM.  
      While the apparatus of the present invention is sufficient to create a path through the occlusion OM without the use of a support or access system, the apparatus  10  of the present invention can be used in conjunction with other atherectomy devices to facilitate improved removal or enlargement of the path through the occlusion. For example as shown in the above figures, the hollow guidewire  14  and the atherectomy device  108  can be advanced through the body lumen and positioned adjacent the occlusion OM. The drive shaft  22  is rotated and advanced to make an initial path through the occlusion ( FIG. 24A ). The hollow guidewire  14  is then moved through the path in the occlusion and the atherectomy device  108  can then be advanced over the hollow guidewire  14  into the path in the occlusion OM to remove the remaining occlusion with cutting blades  110 , or the like ( FIG. 24B ). While  FIG. 24B  shows cutting blades  110  to remove the occlusive material OM, it will be appreciated that other removal devices and techniques can be used. Some examples include balloon dilation catheters, other atherectomy catheters, rotational catheters, extractional catheters, laser ablation catheters, stenting catheters, and the like.  
      In another aspect, the invention provides medical kits. As shown in  FIG. 25 , the medical kit generally includes a system  10 , instructions for use (IFU)  120  which describe any of the above described methods, and a package  130 . The IFU can be separate from the package or they can be printed on the package. The kits can also optionally include any combination of a second guidewire, a motor, a power supply, a plastic sheath cover, connection assemblies, support or access systems, or the like.  
      While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. For example, while the above description focuses on a rotatable drive shaft to remove material from the body lumen, the hollow guidewires of the present invention may incorporate other tissue removal assemblies. The tissue removal assembles may be fixedly positioned at the distal tip of the hollow guidewire or movable between a first position (e.g., retracted position) and a second position (e.g., deployed position). The tissue removal assembly may take on the form of a laser, LED, RF electrode or other heating element, an ultrasound transducer or the like. Thus, instead of a drive shaft, the above tissue removal assemblies may have a lead extend through the axial lumen to the tissue removal assembly that is fixedly or movably positioned at or near the distal end of the hollow guidewire. Moreover, while not explicitly illustrated, a person of ordinary skill in the art will recognize that aspects of one configuration of the hollow guidewire body may be used with other configurations of the hollow guidewire body. For example, while the guidewire body of  FIG. 2  does not show thinned portions  202  near the distal end or varying pitch coils on its proximal portion, such a configuration would be encompassed by the present invention. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.