Abstract:
A medical catheter that has a medial section having twin lumens, each enclosing a separately controllable wire control unit, proximal to said medial section, permitting a user to control said wires; and a fossa distal to said medial section, enclosing an expandable device that may be deployed to have a distal, clot fragment guard section and a proximal clot disrupting section and which is orientation controllable by said wires.

Description:
BACKGROUND 
       [0001]    Until the middle part of the twentieth century, there was very little that medical professionals could do to intervene when a patient suffered a stroke. Gradually, a range of medicinal therapies have been developed, but direct physical intervention after the event is still fairly rare. The difficulty of reaching the event site is part of the reason. The blood vessels of the brain are formed in tortuous pathways that are very difficult to navigate. The alternative effort of reaching the event site through surrounding tissue is complicated by the sensitive and critical nature of brain tissue. 
         [0002]    Nevertheless, it is known to use a stent positioned at the end of a catheter to capture a clot or a portion of a clot and pull it through blood vessels out of the body. One problem with this method is that clot fragments can become dislodged during the procedure and travel in the direction of blood flow to some more interior portion of the brain, where a secondary stroke or strokes may occur. Also, it is difficult to impossible to steer the stent and it appears that access past the carotid artery has not been achieved, using this method. 
         [0003]    Typically, to maneuver a clot-capture stent into a blood vessel of the brain requires a number of steps. First, an incision is made into the femoral artery and a sheath is introduced, extending approximately to the aorta. A first guide catheter is inserted through the sheath and extended up into the carotid artery. A second guide catheter is coaxially introduced through the first guide catheter and extended up into the target aneurysm. Both guide catheters are introduced using a guide wire having a steerable tip of either stainless steel or nitinol. Then, a microcatheter introducer is inserted through the guide catheter, to the clot, and the stent is placed at or into the clot. Heretofore, however, once reaching the clot there has been no effective method for positioning a device that requires precise positioning. A device that would require a definite orientation, as it is withdrawn from the body, presents particular challenges in positioning during implantation. 
         [0004]    Another difficulty in delivering a complex device to a clot site is the lack of space to pack such a device in a lumen at the end of a microcatheter. Any such device must fold into a cylinder having an internal diameter on the order of 1 mm and a length of about 10 mm. 
       SUMMARY  
       [0005]    The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
         [0006]    In a first, separate aspect, the present invention is a medical catheter that has a medial section having twin lumens, each enclosing a separately controllable wire control unit, proximal to the medial section, permitting a user to control the wires; and a fossa distal to the medial section, enclosing an expandable device that may be deployed to have a distal, clot fragment guard section and a proximal clot disrupting section and which is orientation controllable by the wires. 
         [0007]    In a second separate aspect, the present invention is a medical procedure for treating a blood clot in an artery, which utilizes a medical catheter, having a distal end of the catheter, defining a fossa that encloses an expandable device that may be deployed to have a distal, clot fragment guard section and a proximal clot disrupting section and which is orientation controllable by the wires; and a control unit connected to the expandable device by a medial section, and permitting user deployment and position control of the expandable device, transmitted through the medial section. The method begins with the introduction of the distal end of the catheter into the artery and the guidance of the distal end into the clot, deploying the expandable device from the fossa so that the clot fragment guard section is upstream from the clot and the clot disrupting section is in the clot. Then, the control unit is manipulated to control the clot disrupting section, to disrupt the clot. Finally, the control unit is used to dynamically position the deployed expandable device as it is removed from the artery, with clot fragments in the clot fragment guard section, whereby the clot fragments are removed from the patient. 
         [0008]    In a third separate aspect, the present invention is a clot treatment device that includes a nitinol frame, having a compressed state, wherein the treatment device can fit within a cylinder of less than 1.5 mm internal diameter and 15 mm length and an expanded state, and that has a proximal portion and a distal portion along a longitudinal dimension. Also, the distal portion supports a reinforced, perforated silicone barrier, having a dimension transverse to the longitudinal dimension. 
         [0009]    In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
           [0011]      FIG. 1A  is a perspective view of the angular artery, blocked by a clot, with the catheter assembly of the present invention threaded through the arterial system to the clot and the treatment device of the present invention deployed at the clot. 
           [0012]      FIG. 1B  is a perspective view of the angular artery, blocked by a clot, with the catheter assembly of the present invention threaded through the arterial system to the clot and the treatment device of the present invention at a further stage of treating said clot. 
           [0013]      FIG. 1C  is a perspective view of the angular artery, blocked by a clot, with the catheter assembly of the present invention threaded through the arterial system to the clot and the treatment device of the present invention removing clot fragments. 
           [0014]      FIG. 2  shows the clot treatment device of  FIG. 1A , in its undeployed state inside the tube of the catheter assembly of the present invention. 
           [0015]      FIG. 3  shows the tube of the catheter assembly of the present invention, with the clot treatment device deployed out of it. 
           [0016]      FIG. 4A  shows a cross sectional view of the catheter tube of  FIG. 3 , in cross-section and the view-line  4 A- 4 A. 
           [0017]      FIG. 4B  shows a cross sectional view of the catheter tube of  FIG. 3 , in cross-section and the view-line  4 B- 4 B. 
           [0018]      FIG. 4C  shows a cross sectional view of the catheter tube of  FIG. 3 , in cross-section and the view-line  4 C- 4 C. 
           [0019]      FIG. 5  shows a perspective view of the full assembly, including the control assembly and showing the clot disruption device in deployed state. 
           [0020]      FIG. 6  shows the control assembly of the catheter assembly of the present invention, in a neutral state. 
           [0021]      FIG. 7  shows the distal end of the catheter assembly of the present invention, with the clot treatment device deployed in a neutral position. 
           [0022]      FIG. 8  shows the control assembly of the catheter assembly of the present invention, in a state adapted to bend the clot treatment device in a first direction. 
           [0023]      FIG. 9  shows the distal end of the catheter assembly of the present invention, with the clot treatment device deployed in a first direction. 
           [0024]      FIG. 10  shows the control assembly of the catheter assembly of the present invention, in a state adapted to bend the clot treatment device in a second direction. 
           [0025]      FIG. 11  shows the distal end of the catheter assembly of the present invention, with the clot treatment device deployed in a second direction. 
           [0026]      FIG. 12  shows an isometric view of the clot treatment device of  FIG. 1 , in an unfinished state, during construction. 
           [0027]      FIG. 13  shows an isometric view of the clot treatment device of  FIG. 12 , in a further state of being constructed. 
           [0028]      FIG. 14  shows an isometric view of the clot treatment device of  FIG. 13 , in a finished state. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Definition: Upstream, as it is used in this application means further displaced in the direction of blood flow. 
         [0030]    Referring to  FIGS. 1A-1C , in a first preferred method, a blood vessel  10  (most typically an artery), that has been blocked by a clot  12 , is addressed by a catheter assembly  14  that houses a clot disruption and removal device  16 , which can be deployed as shown. The distal end of assembly  14  is introduced into the clot  12 , and the device  16  is deployed into the clot  12 , thereby penetrating through the clot and expanding out of the distal or upstream side of the clot. A proximal portion  20  of device  16  acts to disrupt the clot, whereas an upstream or distal portion  22  of device  16  opens into an umbrella structure to catch any clot fragments created by the clot disruption. Assembly  14  includes a control unit  24  that may be used to control device  16 , and as will be explained further below, can be used to rotate device  16 , thereby further disrupting clot  12 . Control unit  24  can also be used to change the pitch of device  16 , by the relative advancement of a first wire-handle  26  and a second wire-handle  28 . Referring to  FIGS. 1B and 1C , this quality is used after fragments have lodged in distal umbrella  22 , to change the orientation of device  16 , including umbrella  22 , in order to be guided around a bend  30 , out of vessel  10  in expanded form, while retaining the clot fragments. 
         [0031]    Referring to  FIGS. 2-4C , assembly  14 , distal to control unit  24 , includes a flexible tube  38 , which defines a proximal lumen  40 , a medial split lumen  42 , and a distal unitary and expanded lumen or fossa  44 , which houses device  16  prior to deployment. A first wire  46  and a second wire  48 , are attached to the first wire-handle  26  and a second wire-handle  28 , respectively, and pass through lumens  40 ,  42  and  44 . The tube  38  has an exterior diameter of about 1.5 mm, and a hydrophilic exterior surface, to aid in progressing toward a blood vessel destination. 
         [0032]    Referring now to  FIG. 5 , tube  38  is threaded through an end cap  60 , and passes into a transparent chamber  62 , where wires  46  and  48  emerge from tube  38 , pass through a slider  64  and are separately anchored in handles  26  and  28 , respectively. The travel extent of slider  64  is limited by a stop pin  66  and a slot  68 . 
         [0033]    The double lumen section  42  shown in  FIGS. 2 and 3  permits for the control of the shape and orientation of device  16  after it has been pushed out of fossa  44 . As shown in  FIGS. 6 through 11 , after clot removal device  16  is pushed out of fossa  44 , it bends toward wire handle  26 , when handle  26  is retracted, and toward handle  28 , when handle  28  is retracted. Device  16  can be rotated by rotating control unit  24 . This freedom in positioning is most important during the retraction process, when as shown in  FIGS. 1A through 1C , device  16  must be maneuvered around curves, such as bend  30 , while in deployed, expanded form. 
         [0034]    Referring to  FIGS. 12 through 14 , clot disruption and capture device  16  includes a wire frame  72 , which is made of nitinol, or some other shape-memory material. Prior to use, device  16  is maintained at a temperature below human body temperature, thereby causing wire frame  72  to assume the shape shown in  FIG. 14 , when first pushed out of fossa  44 . In another preferred embodiment, however, the natural spring force of the nitinol causes device  16  to expand when it is pushed out of fossa  44 , and it retains this shape during positioning and use. Frame  72  defines a set of eyeholes  74 , through which is threaded expanded poly tetrafluoroethylene (ePTFE) fibers  76 , although in an alternative preferred embodiment a different thread material is used. A silicone barrier  78  is supported by frame  72  and fibers  76 . In one preferred embodiment, silicone barrier is perforated to permit blood to flow through, while catching clot fragments. Silicone barrier  78  may be applied to frame  72  and fibers  76  and then cured in situ, or it may be cured in two sheets which are adhered (preferably with a silicone adhesive) together about fibers  76 . Another feature of device  16  are a set of radio-opaque dots  80 , placed to help a surgeon position device  16 , during clot treatment. 
         [0035]    Wires  46  and  48  are made of stainless steel alloy 304, which may also be referred to as alloy 18-8. This material is coated with poly tetrafluoroethylene. The nitinol alloy that frame  72  ( FIG. 3 ) is made of is 54.5% to 57% nickel, with the remainder titanium, which forms a super-elastic alloy. The introducer tube  38  is made of high density polyethylene, coated at the distal tip with a hydrophilic coating. Finally, the silicone  78  of the device  16  is silicone MED 4820 or MED-6640, which is a high tear strength liquid silicone elastomer, having a Shore A durometer reading of 20-40. A MED6-161 Silicone Primer is used to attach silicone  78  to Nitinol frame  72 . 
         [0036]    While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.