Abstract:
The present invention relates to methods and systems for performing intralumenal procedures including revascularization and removal of foreign objects from a body lumen. More particularly the present invention relates to systems utilizing thrombectomy devices and methods of performing medical procedures to remove thrombus, emboli, foreign objects and or re-establish the intravascular flow of blood.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Prov. Ser. No. 61/501,691 filed Jun. 27, 2011 and U.S. Prov. Ser. No. 61/501,729 filed Jun. 27, 2011, all of which are hereby incorporated by reference herein in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The field of intralumenal therapy for the treatment of vascular disease states has for many years focused on the use of many different types of therapeutic devices. While it is currently unforeseeable that one particular device will be suitable to treat all types of vascular disease states it may however be possible to reduce the number of devices used for some disease states while at the same time improve patient outcomes at a reduced cost. To identify potential opportunities to improve the efficiency and efficacy of the devices and procedures it is important for one to understand the state of the art relative to some of the more common disease states. 
         [0003]    One cerebrovascular disease state is ischemia resulting from reduced or blocked arterial blood flow. The arterial blockage may be due to thrombus, plaque, foreign objects or a combination thereof. Generally, soft thrombus created elsewhere in the body (for example due to atrial fibrillation) that lodges in the distal cerebrovasculature may be disrupted or dissolved using mechanical devices and or thrombolytic drugs. While guidewires are typically used to disrupt the thrombus, some sophisticated thrombectomy devices have been proposed. For instance U.S. Pat. No. 4,762,130 to Fogarty et al., entitled, “Catheter with Corkscrew-Like Balloon”, U.S. Pat. No. 4,998,919 of Schepp-Pesh et al., entitled, “Thrombectomy Apparatus”, U.S. Pat. No. 5,417,703 to Brown et al., entitled “Thrombectomy Devices and Methods of Using Same”, and U.S. Pat. No. 6,663,650 to Sepetka et al., entitiled, “Systems, Methods and Devices for Removing Obstructions from a Blood Vessel” discloses devices such as catheter based corkscrew balloons, baskets or filter wires and helical coiled retrievers. Commercial and prototype versions of these devices have shown only marginal improvements over guidewires due to an inability to adequately grasp the thrombus or to gain vascular access distal to the thrombus (i.e. distal advancement of the device pushes the thrombus distally). 
         [0004]    Plaque buildup within the lumen of the vessel, known as atherosclerotic disease, is not generally responsive to thrombolytics or mechanical disruption using guidewires. The approach to the treatment of neurovascular atherosclerotic disease has been to use modified technology developed for the treatment of cardiovascular atherosclerotic disease, such as balloons and stents, to expand the vessel at the site of the lesion to re-establish blood flow. For instance, U.S. Pat. No. 4,768,507 to Fischell et al., entitled, “Intravascular Stent and Percutaneous Insertion Catheter System for the Dilation of an Arterial Stenosis and the Prevention of Arterial Restenosis” discloses a system used for placing a coil spring stent into a vessel for the purposes of enhancing luminal dilation, preventing arterial restenosis and preventing vessel blockage resulting from intimal dissection following balloon and other methods of angioplasty. The coil spring stent is placed into spiral grooves on an insertion catheter. A back groove of the insertion catheter contains the most proximal coil of the coil spring stent which is prevented from springing radially outward by a flange. The coil spring stent is deployed when an outer cylinder is moved proximally allowing the stent to expand. Other stent systems include those disclosed in U.S. Pat. No. 4,512,338 to Balko, et al., entitled, “Process for Restoring Patency to Body Vessels”, U.S. Pat. No. 5,354,309 to Schnepp Pesch et al., entitled, “Apparatus for Widening a Body Cavity” and U.S. Pat. No. 6,833,003 to Jones et al., entitled, “Expandable Stent and Delivery System”. While the aforementioned devices may have the ability to access the cerebrovasculature, they lack sufficient structural coverage of the lesion to achieve the desired patency of the vessel without the use of a balloon device. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with one aspect of the present invention there is provided a medical device system for restoring patency of a body lumen in a mammal. The thrombectomy system includes a thrombectomy catheter having a proximal hub assembly and a distal end, a longitudinally extending balloon extending distal to the catheter distal end, an expandable retrieval assembly positioned distal to the balloon and an inflation source member coupled to the proximal hub. The proximal end of the extendable balloon member is coupled to the distal end of the catheter and the expandable retrieval assembly is coupled to the distal end of the balloon member. An elongate tether member is positioned within the catheter lumen and preferably coupled to the balloon member distal end and proximal end of the retrieval assembly. The tether member extends proximally through the thrombectomy catheter lumen and proximal to the proximal end of the hub assembly. The expandable retrieval assembly comprises a capture member that generally takes the form of a “closed ended” framework resembling a basket where the distal end is closed with struts or otherwise designed to retain thrombus. The proximal end of the framework is “open” and has a diameter commensurate with the inner diameter of the target vessel for receiving a thrombus. The capture member of the retrieval assembly is formed of a resilient material and has a biased expanded configuration such that the capture member may be constrained to a smaller diameter when positioned in the catheter lumen for delivery and when deployed from the catheter lumen and unconstrained, return to an expanded configuration. For delivery to a desired target site, the longitudinally extending balloon is everted and positioned within the lumen of the thrombectomy catheter such that the distal end of the balloon is proximal to the distal end of the catheter. The retrieval assembly is compressed and positioned within the balloon within the catheter lumen. The balloon member of the delivery catheter is typically formed of a thin walled polymeric tube in which the distal end of the tube has been sealed and the proximal end of the balloon member is coupled to the distal end of the catheter such that the lumen of the catheter is in fluid communication with the interior surface of the balloon. The balloon member is preferably formed of a high strength non-compliant polymeric material such as nylon, polyester and others, however, metallic materials such as thin-film nitinol or other alloys may also be suitable. The inflation source member is coupled to the proximal end of the catheter and used to apply fluid pressure to the lumen of catheter at a level sufficient to cause the balloon member to extend longitudinally from the catheter lumen, thus deploying the retrieval assembly. The preferred fluids include liquids such as saline although gases such as carbon dioxide gas may be suitable for some system configurations. The amount of fluid pressure required to inflate the balloon member is in part related to the increased friction force between the balloon member inner surface and the interior wall of the catheter lumen due to the outward force applied by the constrained collapsed retrieval assembly. The inflation source member preferably takes the form of a syringe (threaded or non-threaded), however other inflation sources such as a pressurized fluid source having a valve assembly or a controllable fluid delivery pump are also suitable. 
         [0006]    In accordance with another aspect of the present invention there is provided a thrombectomy system retrieval assembly comprising biocompatible resilient materials. Suitable resilient materials include metal alloys such as nitinol, titanium, stainless steel and cobalt chromium and any alloys thereof Additional suitable materials include polymers such as polyimides, polyamides, fluoropolymers, polyetheretherketone (PEEK) and shape memory polymers. These materials may be formed into desired shapes by a variety of methods which are appropriate to the materials be in utilized such as laser cutting, injection molding, welding, electrochemical machining, machining, photo-etching and casting. 
         [0007]    In accordance with yet another aspect of the present invention there is provided an expandable retrieval assembly that includes a mesh coupled to a capture member framework. Alternatively the retrieval assembly may be formed as an expandable framework and include a mesh covering. 
         [0008]    In accordance with still another aspect of the present invention there is provided an expandable retrieval assembly that includes a capture member that takes the form of a coil having multiple winds or turns. The coil may have a conical or tapering shape. The coil may also include a plurality of side extension members extending outwardly from a coil wind in a plane generally defined by adjacent winds or turns. The side extension members extending from one turn of the coil may overlap an adjacent turn or overlap the side extension members of an adjacent turn. 
         [0009]    In accordance with another aspect of the present invention there is provided an expandable retrieval assembly having a generally helical backbone and side extension members which may take various configurations comprising any of the following: side extension members on each side of the backbone which are uniformly spaced along the length of the backbone; side extension members on each side of the backbone which are not uniformly spaced along the length of the backbone; side extension members having a curved shape; side extension members having a straight shape; side extension members extending from the backbone in an angled direction; side extension members having different lengths; side extension members having apertures; side extension members having radio-opaque markers; backbones having apertures; backbones having radio-opaque marker(s). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a partial cross-sectional view of a thrombectomy system according to an embodiment of the present invention. 
           [0011]      FIG. 2A  is an enlarged partial cross-sectional view of the distal end of the thrombectomy system according to an embodiment of the present invention. 
           [0012]      FIG. 2B  is an enlarged partial cross-sectional view of the distal end of an alternate thrombectomy system according to another embodiment of the present invention. 
           [0013]      FIG. 3A  is a partial cross sectional view of a deployed thrombectomy system according to an embodiment of the present invention. 
           [0014]      FIG. 3B  is a partial cross sectional view of a deployed thrombectomy system according to another embodiment of the present invention. 
           [0015]      FIG. 3C  is a partial cross sectional view of a deployed thrombectomy system according to yet another embodiment of the present invention. 
           [0016]      FIG. 3D  is a partial cross sectional view of a deployed thrombectomy system according to still yet another embodiment of the present invention. 
           [0017]      FIGS. 4A through 4F  partial cross-sectional views illustrating a method of delivering and deploying a thrombectomy system within a vessel at a target site according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Methods and systems for capturing and removing an embolus or thrombus from an area of the body are herein described. While the terms “thrombectomy” and “thrombus” generally refer to removal of a specific type of embolus, the usage herein should be considered more broadly to include the removal additional types of emboli such as plaque, solid tissue fragments, clots and foreign objects that may block or restrict the normal flow of blood within the vasculature. In other nonvascular lumens within the body, the term “embolus” is herein construed more broadly, to include obstructions of a lumen such as “stones” lodged in a duct.  FIG. 1  illustrates a thrombectomy system  10  according to an embodiment of the present invention. Thrombectomy system  10  includes an elongate catheter  20  having a distal end  22 , a proximal end  24  and a lumen  28  extending therethrough. Coupled to distal end  22  of catheter  20  is balloon member  30 . Balloon member  30  has a delivery configuration in which it is everted and positioned within lumen  28  of catheter  20  at distal end  22 . Thrombectomy system  10  also includes collapsible retrieval assembly  40  having flexible mesh  41  for engaging thrombus within a vessel. Retrieval assembly  40  has a delivery configuration in which it is collapsed and positioned within lumen  28  of catheter  20  at distal end  22 . Proximal end  24  of catheter  20  is coupled to hub member  42  which includes inflation port  44  and a sealable valve  46 . An elongate flexible tether member  48  coupled to balloon member  30  is slidably positioned within lumen  28  and extends through valve  46 . 
         [0019]    A partial cross sectional view of distal end  22  of catheter  20  is shown in  FIG. 2A . While not shown, the construction of catheter  20  may utilize known catheter technologies that incorporate braiding and or coiling using metallic or non-metallic reinforcing filamentous materials to provide high strength while maintaining catheter flexibility. The incorporation of lubricious hydrophilic and or hydrophobic materials on the inner and or outer surface of the catheter is considered to be within the scope of known catheter construction techniques and suitable for use in a thrombectomy system according to embodiments of the present invention. Retaining member  52  is used to affix proximal end  54  of balloon member  30  to catheter distal end  22 . The inner diameter of balloon member proximal end  54  is slightly larger than the outer diameter of catheter distal end  22  thereby allowing distal end  22  to be inserted within proximal end  54 . Retaining member  52  is shown as a flexible filament (preferably polymeric) wound around proximal end  54  and catheter distal end  22  securing balloon member  30  to catheter  20 . Balloon member proximal end  54  and distal end  22  may be secured using other means such as heat fusing, multifilament winds, ultrasonic welding and or gluing to insure a good bond and seal. The distal end  56  of balloon member  30  is completed sealed using any of the aforementioned techniques and positioned everted within catheter lumen  28  proximal to proximal end  54 . Retrieval assembly  40  is positioned within everted balloon member such that retrieval assembly distal end  58  is proximal to catheter distal end  22 . Retrieval assembly  40  also includes proximal end  60 . Proximal end  60  of retrieval assembly  40  includes collapsible loop frame  61  coupled to mesh  41  and is coupled to distal end  56  of balloon member  30  at joint assembly  62 . Joint assembly  62  also couples retrieval assembly  40  to flexible tether member  48 . 
         [0020]      FIG. 2B  illustrates an alternate embodiment of the present invention showing thrombectomy system  110 . Thrombectomy system  110  includes an elongate catheter  120  having delivery portion  122  and guidewire portion  124 . Guidewire portion  124  having through lumen  126  extends proximally to the proximal end of catheter  120 . Alternatively guidewire portion  124  and lumen  126  may extend proximally only a portion of the length of catheter  120  and have a configuration suitable for use as a “rapid exchange” system allowing the system  110  to reach a target site over a guidewire that has already been positioned at the target site. Delivery portion  122  includes lumen  128  extending from the proximal end to the distal end of catheter  120 . Balloon member  130  is everted and positioned within lumen  128  of catheter delivery portion  122 . Positioned within everted balloon member  130  in a collapsed configuration is retrieval assembly  140 . Securing member  152 , shown as a wound filament, affixes balloon member proximal end  154  to the distal end of delivery portion  122 . Balloon member proximal end  154  and the distal end of delivery portion  122  may be secured using other means such as heat fusing, ultrasonic welding, multifilament winds and or gluing to insure a good bond and seal. The distal end  156  of balloon member  130  is completed sealed using any of the aforementioned techniques and positioned everted within catheter lumen  128  proximal to proximal end  154 . Retrieval assembly  140  positioned adjacent distal end  156  of everted balloon member  130  includes distal portion  158  and proximal portion  160 . 
         [0021]      FIG. 3A  shows an enlarged partial cross sectional view of the distal portion of thrombectomy system  10 . Balloon member  30  is shown in an inflated configuration longitudinally extending distal to catheter distal end  22 . In this configuration, balloon member distal end  56  is positioned distal to balloon member proximal end  54 . The diameter of balloon member  30  may range from about 0.25 to about 1.5 times the diameter of catheter  20  and have a preferred range from about 0.5 to 1.2 times the diameter of catheter  20 . Balloon members are preferably formed from an elongate thin walled noncompliant material. Suitable polymeric materials include nylon or polyester tubes having a wall thickness from 0.0001 inches to 0.010 inches with a preferred range of about 0.0005 inches to 0.005 inches. Other suitable materials include metallic thin film alloys such as nitinol having a wall thickness in the range of about 0.0001 inches to about 0.001 inches. Balloon members typically have a length that is substantially longer than the collapsed retrieval assemblies and range from about 40 mm to about 500 mm with a preferred range of about 50 mm to 400 mm. Retrieval assembly  40  is shown in a deployed configuration where distal end  58  is positioned distal to balloon member proximal end  54  and loop frame  61  of proximal end  60  is expanded. Typically, the expanded diameter of loop frame  61  is slightly larger than the inner diameter of the vessel at a target site. This diameter allows coupled mesh  41  at proximal end  60  to be adjacent or in contact with the inner wall of the vessel at a target site. Mesh  41  is formed of flexible material and may take commonly known configurations such as woven and nonwoven fabrics, braids, perforated materials, webs and nets. 
         [0022]      FIGS. 3B through 3D  are partial cross sectional views of thrombectomy systems according to alternate embodiments of the present invention that illustrate an inflated extended balloon member and different configurations of deployed retrieval assemblies.  FIG. 3B  shows an enlarged partial cross sectional view of the distal portion of thrombectomy system  220 . Balloon member  230  is shown in an inflated configuration longitudinally extending distal to catheter distal end  222 . In this configuration, balloon member distal end  234  is positioned distal to balloon member proximal end  232 . The diameter of balloon member  230  may range from about 0.25 to about 1.5 times the diameter of catheter  221  and have a preferred range from about 0.5 to 1.2 times the diameter of catheter  221 . Retrieval assembly  240  is shown in a deployed configuration where distal end  244  is positioned distal to balloon member proximal end  238  and loop frame  246  of proximal end  242  is expanded. Joint assembly  248  couples retrieval assembly  240  to flexible tether member  228  and balloon member distal end  234 . Retrieval assembly  240  also includes a plurality of frame members, represented by frame member  245  that are coupled to loop frame  246  and extend towards distal end  244 . The frame members are generally spaced apart about loop frame  246  and converge distally forming a “cage like” structure adapted to receive and retain emboli and or thrombus. Typically, the expanded diameter of loop frame  246  is slightly larger than the inner diameter of the vessel at a target site. This diameter allows the coupled frame members at proximal end  242  to be adjacent or in contact with the inner wall of the vessel at a target site. While the frame members, including representative frame member  245  are shown having a generally straight shape extending from loop frame  246  to distal end  244 , it should be understood that the frame members may have alternative shapes including helixes, zigzag, arcuate, sinusoids and combinations thereof Located at distal end  244  is an atraumatic marker tip  250 . Marker tip  250  preferably takes the form of a beaded flexible coil however other forms may e suitable such as flexible filaments or tubes that incorporate radiopaque elements. 
         [0023]      FIG. 3C  shows an enlarged partial cross sectional view of the distal portion of thrombectomy system  320 . Balloon member  330  is shown in an inflated configuration longitudinally extending distal to catheter distal end  322 . In this configuration, balloon member distal end  334  is positioned distal to balloon member proximal end  332 . The diameter of balloon member  330  may range from about 0.25 to about 1.5 times the diameter of catheter  321  and have a preferred range from about 0.5 to 1.2 times the diameter of catheter  321 . Retrieval assembly  340  includes an elongate flexible resilient backbone  341  that takes the form of a spiral having multiple adjacent winds preferably tapering distally from proximal end  342 . Representative wind  344  of elongated backbone  341  is shown having a plurality of side extension members represented by side extension members  346  and  347 . Representative side extension members  346  and  347  are only fixedly connected to backbone  341  and generally extend from opposite sides of backbone  341  at wind  344  spanning at least a portion of the gap between adjacent winds of backbone  341  as the winds taper towards distal end  350 . Side extension members on one wind of backbone  341  may be adjacent to or overlap the side extension members on an adjacent wind of backbone  341 . For illustrative purposes, side extension members  346  and  347  are shown having a straight shape and positioned at an angle relative to backbone  341 , however multiple shapes and configurations including sinusoids, zigzags, varying widths, arcuate, open loops and combinations are also contemplated. Retrieval assembly  340  is shown in a deployed configuration coupled at joint assembly  348  to balloon member distal end  334  and flexible tether member  328 , where distal end  350  is positioned distal to balloon member proximal end  332  and expanded proximal end  342 . Typically, the expanded diameter of proximal end  342  is slightly larger than the inner diameter of the vessel at a target site. This diameter allows side extension members coupled to backbone  341  at proximal end  342  to be adjacent or in contact with the inner wall of the vessel at a target site. 
         [0024]      FIG. 3D  shows an enlarged partial cross sectional view of the distal portion of thrombectomy system  360 . Balloon member  370  is shown in an inflated configuration longitudinally extending distal to catheter distal end  362 . In this configuration, balloon member distal end  374  is positioned distal to balloon member proximal end  372 . The diameter of balloon member  370  may range from about 0.25 to about 1.5 times the diameter of catheter  361  and have a preferred range from about 0.5 to 1.2 times the diameter of catheter  361 . Retrieval assembly  380  is coupled to balloon member distal end  374  and elongate flexible tether member  368  at joint assembly  382 . Retrieval assembly  380  is shown in a deployed configuration and includes a plurality of arcuate or generally “U” shaped capture arm members represented by arm members  384  and  386 . The capture arm members have a first end that is coupled to joint assembly  382  and a second end that is free. The second ends of the capture arm members are spaced apart from each other and distributed radially about the central axis of joint assembly  382 . The second end of capture arm members may include rounded atraumatic tips such as tip portions  385  and  387  of representative capture arm members  384  and  386 . Tip portions may include markers for visibility under fluoroscopy, magnetic resonance or other imaging modalities. Typically, the expanded diameter of retrieval assembly  380  is slightly larger than the inner diameter of the vessel at a target site. This diameter allows the capture arm members to be adjacent to or in contact with the inner wall of the vessel at a target site. To further enable the secure capture of emboli or thrombus, flexible filaments such as filaments  388  and  389  may be coupled to and span adjacent capture arm members forming a web like configuration. A plurality of flexible filaments may take commonly known configurations such as woven and nonwoven fabrics, braids and nets. 
         [0025]    Preferably, the retrieval assemblies of embodiments of the present invention comprise a biocompatible resilient material. Suitable resilient materials for loop frames, frame members, backbones, side extension members and arcuate members include metal alloys such as nitinol, titanium, stainless steel. Additional suitable materials include polymers such as polyimides, polyamides, fluoropolymers, polyetheretherketone(PEEK) and shape memory polymers. These materials may be formed into desired shapes by a variety of methods which are appropriate to the materials be in utilized such as laser cutting, thermal heat treating, vacuum deposition, electro -deposition, vapor deposition, chemical etching, photo etching, electro etching, stamping, injection molding, casting or any combination thereof. In addition, the biased resiliency of these materials allow a retrieval assembly with a normally expanded configuration to have a collapsed, small diameter configuration when constrained within a delivery catheter suitable for delivery to a target site and upon being deployed at a target site return to its expanded configuration. 
         [0026]      FIGS. 4A through 4F  illustrate a method of deploying a retrieval assembly at a target site within a body lumen according to one embodiment of the present invention. The thrombectomy system  10  is positioned within a vessel  400 . Catheter distal end  22  including extendable balloon member  30  are positioned at a target site adjacent to thrombus  410 . An inflation source member (not shown) is coupled to the proximal end of the catheter  20  and used to apply fluid pressure to the lumen of catheter. The inflation source member preferably takes the form of a syringe (threaded or non-threaded), however other inflation sources such as a pressurized fluid source having a valve assembly or a controllable fluid delivery pump are also suitable. The preferred fluids include liquids such as saline and radiopaque contrasts solutions however gases such as carbon dioxide gas may be suitable for some system configurations. As the applied fluid pressure increases to a sufficient level, balloon member  30  begins to extend longitudinally from the catheter lumen. As balloon member  30  extends longitudinally from catheter  20 , leading edge  415  of the balloon member  30  may encounter thrombus  410 . While shown as large particle, thrombus  410  may have a varied composition that could comprise organized clot, tissue, plaque soft clot or even foreign objects. Dependant somewhat upon the size and composition of thrombus  410  balloon member  30  may extend longitudinally through a soft and compliant thrombus or between the inner vessel wall and a more rigid thrombus. Leading edge  415  of balloon member  30  is well suited to extend longitudinally between the more rigid thrombus and the vessel wall without perforating the vessel. With continued application of fluid pressure, balloon member  30  continues to extend longitudinally until retrieval assembly  40  is deployed and positioned distal to thrombus  410 . Once retrieval assembly  40  is appropriately deployed, application of additional fluid pressure is unnecessary. In the deployed configuration, proximal end  60  of retrieval assembly  40  is expanded to preferably contact the inner wall of vessel  400 . As shown in  FIG. 4E , thrombectomy system  10  including tether member  48  is pulled proximally causing proximal end  60  of retrieval assembly  40  to engage the distal side of thrombus  410 . Tether member  48  ensures that sufficient retraction force is applied directly to retrieval assembly  40  to capture thrombus  410 . Thrombectomy system  10  with captured thrombus  410  may then be removed from the body. Alternatively, balloon member  30  may be deflated and thrombectomy system  10  with captured thrombus  410  pulled proximally within larger catheter  420  having lumen  430 . Suction may then be applied to lumen  430  thus aiding retention of thrombus  410  during removal or to fragment and remove thrombus  410  from retrieval assembly  40 . 
         [0027]    Novel devices, systems and methods have been disclosed to perform vascular reconstruction and revascularization procedures within a mammal. Although preferred embodiments of the invention have been described, it should be understood that various modifications including the substitution of elements or components which perform substantially the same function in the same way to achieve substantially the same result may be made by those skilled in the art without departing from the scope of the claims which follow.