Abstract:
A medical device for breaking up and aspirating material, especially intravenous clots, having a catheter, a barrel, and a sheath is disclosed. The catheter has a lumen through which material is aspirated. The barrel has a first and second end connected by a plurality of blades that are self-biased to extend outward. The sheath provides a selective radial constraint such that the blades are constrained when the sheath covers the barrel and unconstrained when the sheath is retracted.

Description:
RELATED APPLICATIONS 
       [0001]    The present patent document is a continuation of application Ser. No. 14/211,295, filed Mar. 14, 2014, which claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 61/794,423, filed Mar. 15, 2013. All of the foregoing applications are hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    Embodiments of the present invention relate to methods and apparatuses for breaking up clots in blood vessels and collecting the broken up clot, and more particularly to a catheter designed to break up and collect a clot. 
       BACKGROUND 
       [0003]    Deep vein thrombosis (DVT) is a condition in which blood clots form in the large veins of the lower portions of the body. If a blood clot breaks free, it may travel to other parts of the body and cause significant damage. For instance, if a blood clot were to travel to the heart and lungs through the inferior vena cava a pulmonary embolization could result. A pulmonary embolization may be fatal if the clot interferes with the pumping of blood by the heart. If the clot passes through the heart, it may lodge in the pulmonary arteries inhibiting the oxygenation of blood. 
         [0004]    Current methods of treating DVT include administering Heparin, an anticoagulant, to prevent further clots from forming and performing intravenous procedures using an aspiration catheter to collect the clot. In some instances a clot busting device may be used in combination with the aspiration catheter to break up the clot into smaller pieces that can be aspirated. The clot busting device is typically delivered through a lumen of the aspiration catheter and occupies at least a portion of the cross sectional area of the lumen. Because the clot buster reduces the cross sectional area of the lumen, the clots must be broken up to a smaller size than when an aspiration catheter is used alone, or the clot buster must be removed from the lumen to aspirate larger clot pieces. However, it is dangerous to break up the clot without simultaneous aspirating the clot pieces, as the clot pieces may travel before being aspirated, causing the very event the surgery is designed to prevent. 
         [0005]    It would be beneficial to have a device and methods for breaking up a clot while simultaneously aspirating the clot pieces without reducing the efficacy of the aspiration catheter. 
       SUMMARY 
       [0006]    Embodiments of the invention include a catheter assembly comprising a barrel, an elongated tubular body, and a sheath. The barrel is formed from a shape memory material and has a first end with an outside diameter, and a second end spaced apart from the first end. A longitudinal axis extends from the first end to the second end and a plurality of longitudinal blades extend proximate the first end to proximate the second end. A film is disposed on a portion of the plurality of blades. The barrel is biased to an expanded state in which a portion of each of the longitudinal blades extends beyond the outside diameter of the first end. The elongated tubular body has a lumen disposed therein and a distal end is coupled to the first end of the barrel. The sheath is disposed about the barrel and is adapted to translate axially from a first position about the barrel to a second position about the elongated tubular body. At the first position the sheath constrains the barrel in a compacted configuration in which the plurality of longitudinal blades does not extend beyond the first outside diameter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    To further clarify the above and other advantages and features of the one or more present inventions, reference to specific embodiments thereof are illustrated in the appended drawings. The drawings depict only typical embodiments and are therefore not to be considered limiting. One or more embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0008]      FIG. 1  depicts a distal end of an embodiment of a clot buster catheter. 
           [0009]      FIG. 1 b    depicts a distal end of another embodiment of a clot buster catheter. 
           [0010]      FIG. 2  depicts a clot buster in a compacted configuration. 
           [0011]      FIG. 3  depicts an alternative embodiment of a clot buster. 
           [0012]      FIG. 4  depicts an alternative embodiment of a clot buster. 
           [0013]      FIG. 5  depicts an alternative embodiment of a clot buster. 
           [0014]      FIG. 6  depicts a blood vessel having a clot. 
           [0015]      FIG. 7  depicts the blood vessel of  FIG. 6  having a clot buster catheter having a clot buster in a compacted configuration proximate the clot. 
           [0016]      FIG. 8  depicts the blood vessel of  FIG. 6  having a clot buster catheter with an expanded clot buster proximate the clot. 
           [0017]      FIG. 9  depicts the blood vessel of  FIG. 6  having a clot buster breaking up the clot. 
       
    
    
       [0018]    The drawings are not necessarily to scale. 
       DETAILED DESCRIPTION 
       [0019]    As used herein, “at least one,” “one or more,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
         [0020]    Various embodiments of the present inventions are set forth in the attached figures and in the Detailed Description as provided herein and as embodied by the claims. It should be understood, however, that this Detailed Description does not contain all of the aspects and embodiments of the one or more present inventions, is not meant to be limiting or restrictive in any manner, and that the invention(s) as disclosed herein is/are and will be understood by those of ordinary skill in the art to encompass obvious improvements and modifications thereto. 
         [0021]    Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
         [0022]      FIG. 1  illustrates a distal end  102  of an embodiment of a catheter assembly  100  adapted for clot busting and clot aspiration. The catheter assembly  100  has a clot buster  108  disposed proximate the distal end  102 , and a tubular body  106  extending from a proximal end (not shown) to the clot buster  108 . A lumen  104  extends from the proximal end to the clot buster  108  and provides fluid communication between the proximal end and the clot buster  108 . A tip  116  is disposed at the distal end  102  of the catheter assembly  100  and may be formed of a soft material, similar to a traditional catheter tip. 
         [0023]    The tubular body  106  is of construction similar to a traditional sheath or catheter tubing. The tubular body  106  may be formed of a material and have a wall thickness sufficient to withstand a vacuum applied to the lumen  104  and sufficient to transmit rotational and axial force from the proximal end of the tubular body  106  to the clot buster  108 . 
         [0024]    The clot buster  108  has a double conical shape with a first cone  110  and a second cone  112  joined at a base  114 . The base  114  is typically located at a point midway between a first cone apex  118  and a second cone apex  120 . The tubular body  106  is joined to the clot buster  108  near the first cone apex  118  and the tip  116  is joined to the clot buster  108  near the second cone apex. As shown in  FIG. 1 , the cones  110 ,  112  need not be precise cones and may only generally resemble cones. The clot buster  108  may be formed out of a single piece of material that has been shaped to the double cone shape, or it may be formed of a plurality of pieces joined together to form the double cone shape. 
         [0025]    The clot buster  108  is ideally formed out of a rigid material that has shape memory. For example, the clot buster  108  may be formed of Nitinol tubing, but other materials are possible, such as thermoplastics. The clot buster  108  of  FIG. 1  is shown in an expanded form, in which a plurality of struts  122  extends radially outward from the axis of the catheter assembly  100 .  FIG. 2  illustrates the clot buster  108  in an unexpanded state. In  FIG. 2 , the clot buster  108  is a hollow cylinder  200  having a plurality of longitudinal cuts  124  dividing the surface of the cylinder  200  into a plurality of struts  122 . The longitudinal cuts  124  do not extend to the face  202  of the cylinder  200  such that the surface of the cylinder  200  near a face  202  forms a complete circle. 
         [0026]    The cylinder  200  may be expanded radially, moving each face  202  of the cylinder  200  towards one another. The struts  122  buckle extending outward at their midpoint. The cylinder  200  is then shape set so that the cylinder  200  is self-biased to the configuration shown in  FIG. 1 . For example, a cylinder may be expanded radially as described and then heat treated to remember the shape using known techniques. 
         [0027]    In some embodiments the clot buster may be formed in shapes other than the described double cone. For example,  FIG. 3  through  FIG. 5  illustrate alternative clot buster shapes. In  FIG. 3 , the clot buster  300  has blades  302  that have been shape set to have a dimple  304  disposed near a cone base  306 . In  FIG. 4 , a clot buster  400  has blades  402  that have a more pronounced curve on the distal portion  408  as compared to the proximal portion. The distal portion  408  of the clot buster  400  has blades  402  that extend longitudinally before making at abrupt change at location  404  where the blades  402  extend outward, nearly perpendicular to the axis of the clot buster  400 . Other angles are possible and the blades  402  do not need to extend perpendicularly to the axis. 
         [0028]    In  FIG. 5 , a clot buster  500  is shown in which the blades  502  are formed into different shapes. A first blade  504  is formed to have a zigzag  508  at a distal portion  512 . A second blade  506  is formed to curve outward at the distal portion  512 . Other combinations of blades are possible and are not limited by this disclosure. In some embodiments a clot buster may have every other blade removed from the base of the cone to the distal section of the clot buster. 
         [0029]    Returning to  FIG. 1 , the first cone  110  section of the blades  122  has a coating applied to it that forms a web  124  between adjacent blades  122 . When the clot buster  108  is expanded, as shown in  FIG. 1 , the web  124  forms a funnel  126  with an enlarged portion near the base  114  of the first cone  110  and a neck near the apex  118  of the first cone  118 . The coating may be applied to the interior surface of the blades  122 , to the exterior surface of the blades  122 , or may be applied to both surfaces of the blades  122 . In some embodiments, the coating may encapsulate the blades  122 . The coating may be formed of an elastic polymer, allowing the coating to expand when the blades  122  are extended. 
         [0030]    In the clot buster  108 B embodied in  FIG. 1 b   , a first cone  110 B section of the blades  122 B does not have any coating applied. Instead, a coating is applied to a second cone section  112 B forming a web  124 B between adjacent blades  122 B in the second cone  112 B section. When the clot buster  108 B is expanded, as shown in  FIG. 1B , the web  124 B forms a basket  150 B with an enlarged open portion  152 B near the base  114  of the second cone  112 B. In contrast to the embodiment of  FIG. 1 , the web  124 B does not funnel material into the aspiration catheter, but may instead serve to catch clot particles that may flow distally from the clot buster  108 B. 
         [0031]      FIG. 6  illustrates a blood vessel  600  having a clot  602  formed on the wall  604  of the vessel  600 . The clot  602  causes a restriction in the cross sectional area of the blood vessel  600  resulting in reduced blood flow and may potentially break free, traveling through the blood vessel  600  until it lodges in a vessel of reduced cross sectional area. A clot busting catheter may be guided to the clot  602  using commonly known techniques. In one embodiment, a surgeon may advance a wireguide to the clot  602  and a dilator catheter may then be advanced over the wire guide to the clot  602 . A sheath may then be advanced over the dilator catheter to the clot  602 . Once the sheath is in place, the dilator catheter may be removed, leaving the sheath. The clot busting catheter may then be easily advanced within the sheath. 
         [0032]    In some embodiments a guidewire may be left in place and a clot busting catheter may be advanced over the guidewire. This may be done in within an in place sheath, or may be done independent of the sheath. In such embodiments, the clot buster catheter may have a lumen or other guide within the tubular body through which the guidewire extends. The tip of the clot buster may have a passage allowing the guidewire to pass through the tip. 
         [0033]      FIG. 7  illustrates the blood vessel  600  of  FIG. 6 , but with a clot busting catheter  700  disposed within the vessel  600  proximate the clot  602 . The clot busting catheter  700  has been guided to the clot  602  with a clot buster  704  in an unexpanded state, such that it can be easily guided to the clot  602 . An introducer sheath  702  is disposed about the clot buster  704 , constraining the clot buster  704  to its unexpanded state. The introducer sheath  702  is retractable, such that a surgeon may selectively retract the introducer sheath  702  freeing the clot buster  704  from the constraint posed by the introducer sheath  702 . In some embodiments the introducer sheath  702  extends the length of the clot busting catheter  700  and may be guided to the clot  602  without the clot buster  704 . The clot buster  704  may then be guided through the introducer sheath  702  to the site of the clot  602  in an unexpanded state. In such embodiments, when the clot buster  704  is advanced to the clot  602 , the clot buster  704  may be extended from the sheath  702 , freeing the clot buster  704  from the radial constraint of the sheath  702 . 
         [0034]    In  FIG. 8  the introducer sheath  702  has been retracted proximally allowing the clot buster  704  to expand radially into its self-biased, expanded state. In other embodiments the clot buster  704  may be extended past the distal end of the introducer sheath  702  allowing the clot buster  704  to expand into its self-biased, expanded state. The clot buster  704  may be chosen such that a maximum outside diameter  800  of the expanded clot buster  704  is similar to an inside diameter  802  of the vessel proximate the clot  602 . A distal tip  804  of the clot busting catheter  700  is guided to pass through the clot  602 . In some embodiments, the distal tip  804  may serve as a dilator, expanding the clot  602  to enable to clot buster  704  to contact the clot  602 . 
         [0035]      FIG. 9  illustrates the clot buster  704  breaking up the clot  602  into clot pieces  902 . The clot  602  may be broken into clot pieces  902  by moving the clot buster  704  axially as shown by arrow  904  such that open blades  906  engage the clot  602 , and by spinning the clot buster  704  as shown by arrow  908  such that edges of the open blades  906  contact the clots  602 . In some embodiments, the clot buster  704  may both be moved axially and spun to break up the clot  602 . 
         [0036]    A vacuum, indicated by arrow  910 , is applied to a lumen  914  of the clot buster catheter  700  reducing the pressure in the lumen  914 . Fluid, such as blood, proximate the clot buster  704  flows towards the reduced pressure and into the lumen  914  as indicated by arrows  912 , carrying the clot pieces  902  along with it. Like the embodiment of  FIG. 1 , a coating  914  covers the proximal blades  906  to form a funnel  916 . The funnel  916  channels the flow of fluid and clot pieces  902  into a neck  918  of the funnel  916  and into the lumen  914 . 
         [0037]    In embodiments having a guidewire, the clot buster  704  may spin about the guidewire or may move axially along the guidewire. Thus, the clot buster  704  may be moved proximally leaving the guidewire in place. The clot buster  704  may then be returned to the site of the clot  602  by advancing the clot buster  704  over the guidewire. 
         [0038]    When the surgeon is finished breaking up the clot  602  and aspirating the pieces, the clot buster  704  may be retrieved in the reverse order that the clot buster  704  was deployed. The clot buster catheter  700  may be moved in a proximal direction away from the clot  602 . The surgeon then advances the sheath  702  back over the clot buster  704 , or retracts the clot buster  704  within the sheath  702 . The sheath  702  once again provides a radial constraint to the clot buster  704 , compressing the clot buster  704  into the unexpanded shape shown in  FIG. 700 . The clot buster catheter  700  may then be removed from the vessel. 
         [0039]    In other embodiments, the coating may be applied to the distal portion of the blades and the proximal portion of the blades may be uncoated. In this embodiment the clot buster is used similar to the embodiment described previously, with the exception that the surgeon will advance the clot buster beyond the clot prior to retracting the sheath. Once deployed, the surgeon pulls the clot buster through the clot breaking up the clot into pieces. A vacuum is applied to the lumen and clot pieces and fluid is aspirated through the lumen. Clot pieces that are not aspirated are caught in the funnel. When the clot buster is retracted, the funnel envelops the clot pieces as the sheath compresses the clot buster. The clot buster catheter may then be removed by the surgeon. 
         [0040]    Embodiments of the invention have been primarily described in relation to the double cone configuration of the clot buster, but the described methods may be used with other shapes of the clot buster, such as those shown in  FIGS. 3, 4, and 5 . It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.