Abstract:
A stent device for introduction into a bifurcation aneurysm, comprising a radially expandable elongated wire mesh tube having a proximal end and a distal end. The distal end is expandable into a cone shaped portion of a larger diameter than the proximal end. A web of material is arranged across said distal end of said stent device for sealing an aneurysm at a neck portion thereof.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to medical devices such as stents for treating aneurysms particularly bifurcation aneurysms. This non-provisional patent application is based upon Provisional Patent Application Ser. No. 60/755,639, filed Dec. 31, 2005, and upon Provisional Patent Application Ser. No. 60/753,764 filed Dec. 23, 2005, each of which are incorporated herein by reference.  
         [0003]     2. Prior Art  
         [0004]     Current treatment of bifurcation aneurysms currently utilize balloons and a stent. However, such balloons may at least temporarily occlude blood flow through the vessels in which they are placed. Those balloons also need to be deflated and removed at the end of a vessel remodeling session. Such balloons may also rupture an aneurysm and/or a vessel when that balloon is inflated. Utilizing a stent with the balloon in a bifurcation aneurysm does not protect both of its efferent vessels. Such balloon vessel remodeling also requires two experienced surgeons and two catheters simultaneously, in a single vessel at the same time.  
         [0005]     It is an object of the present invention to overcome the disadvantages of the prior art.  
         [0006]     It is a further object of the present invention to provide a bifurcation aneurysm treatment which will allow proper blood flow during the treatment procedure, and to prevent reflux of any embolic agent placed within the aneurysm.  
         [0007]     It is a further object of the present invention to provide a novel apparatus and method for the treating and sealing of a bifurcation aneurysm.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     The present invention relates to an elongated aneurysm treating stent device having an open proximal end and a closed distal end. The stent device in its deliverable form is cylindrically shaped and is preferably constructed from a pattern of woven metallic fibers. The proximal end of the stent device may have a plurality of radial opaque markers thereon. An elongated electrolytic tethering wire is arranged at several circumferential locations on the proximal end of the stent device. The tethering wires join a common electrolytic tethering wire which extends through a delivery catheter. The tethering wires are attached to the proximal end of the stent device that remain as electrolytic junctions. Those electrolytic junctions are arranged so as to be severed once the stent device has been put in place within an aneurysm. The webbed design of the stent device is woven so as to have larger openings between the web fibers towards the distal end of the stent device.  
         [0009]     Further, upon expansion of the distal end into its waffle cone configuration further facilitates the larger openings of that expanded stent at its distal end.  
         [0010]     In one preferred embodiment of the present invention, a web of foraminous or non-foraminous material is disposed across the distal end of the cone-shapable stent, so as to provide a sealing-like web across the neck of an aneurysm at a bifurcation. That web may in one embodiment, be perforable so as to permit the passage of a microwire therethrough as will be explained hereinbelow.  
         [0011]     The stent in its unexpanded form, may have a distalmost web of sheet material thereon, or alternatively, a continuous woven pattern of cell openings, distal of the body of the stent itself. The openings or cell size of the distal web portion in its preferred format, are smaller than the cell or opening portions in the main body portion of the stent.  
         [0012]     In a further preferred embodiment of the present invention, a plurality of anchoring struts are flayed outwardly generally spaced adjacent the distalmost portion of the stent. Those anchoring struts, somewhat J-shaped have their respective distal ends extending somewhat radially outwardly to a diameter somewhat less than the expanded diameter of the distalmost portion of those distalmost stent cells.  
         [0013]     Those outwardly extending anchoring struts are arranged so as to engage the innermost edge of the peripheral lip of the neck of the aneurysm, at the bifurcation. Such circumferential array of anchoring struts thus prevents advancement and/or displacement of the distal end of the stent from going too far within the aneurysm itself. The waffle-shaped cone thereon nests within the circumference of the aneurysm adjacent its neck and provides a sealing web thereacross.  
         [0014]     In delivery of such a stent within a bifurcation aneurysm, a microwire is directed through a parent vessel and into the aneurysm. A microcatheter is fed over the microwire and the microwire after several steps, is subsequently removed. The microcatheter is however temporarily left within the aneurysm at the bifurcation. The waffle cone stent is loaded through the microcatheter and is advanced over the microwire and into the aneurysm through the parent vessel. An electrolytic tethering wire is attached to the proximal most end of the waffle cone stent. The delivery catheter surrounding the waffle cone stent may then be removed proximally so as to expose the waffle cone stent device to/against the walls of the parent vessel. The distalmost end of the waffle cone stent is thus permitted to expand immediately within the neck of the aneurysm. The anchoring struts expand outwardly along with the distalmost portion of the waffle cone stent, so as to nest within the neck of the aneurysm. The microcatheter, still within the waffle cone stent, is utilized to feed an elongated embolitic member for delivery within the aneurysm itself. Such a microcatheter or embolitic material may pierce the web, or pass through one of the small cell openings in the distally located web of the waffle cone shaped stent. The result would be an embolitic member fully engulfing the aneurysm while its microcatheter delivery system is removed therefrom. The waffle cones stent with its anchoring structs expanded, would remain therewithin the aneurysm as well. The expanded cell structure of the distal end portion of the waffle cone stent would permit blood to flow through the parent vessel and across the arms of those adjoining vessels at the bifurcation.  
         [0015]     The invention thus comprises a stent device for introduction into and for treatment of a bifurcation aneurysm, comprising a radially expandable elongated wire mesh tube having a proximal end and a distal end, the distal end being expandable into a cone shaped portion of a larger diameter than the proximal end, and a web of material arranged across the distal end of the stent device for sealing an aneurysm at a neck portion thereof. The web may be foraminous. The web may be non-foraminous (no openings). The stent device may include an arrangement of struts at or near the distal end of the stent device. The struts preferably have an aneurysm neck-portion-engaging distal end. The web may have openings therethrough which are smaller than wall openings in the proximal end of the stent device. The web may be comprised of a foldable film of polymer. The web may be radiopaque. The web is preferably nestable across a neck portion of an aneurysm to seal embolytic material therein. The web is pierceable by a microcatheter.  
         [0016]     The invention also includes a method of treating a bifurcation aneurysm comprising one or more of the following steps which are: introducing a microwire into the aneurysm, introducing a waffle-cone-shapable microcatheter into the aneurysm over the microwire, expanding a distal end of the microcatheter into a tapered waffle-cone shape within the bifurcation aneurysm, and pivoting outwardly an annular array of anchoring struts from a circumferential array thereof spaced proximately adjacent the distal end of the catheter so as to anchor the distal end of the microcatheter within the aneurysm. The method may include arranging a pierceable web across the distal end of the microcatheter, introducing an embolitic agent through the catheter and the web on the distal end of the catheter, distally beyond the anchoring struts and into the aneurysm. The pierceable web may be foraminous. The pierceable web may be made of a non-foraminous film, to provide a sealed distal end to permit an unencumbered aneurysm-entering distal motion of the catheter. The struts preferably have an outer end of “ski-tip” shape, to facilitate anchoring the catheter within a neck portion of the aneurysm. The method may include forming the ski-tip end of the struts to extend separate and apart from the distalmost end of the microcatheter.  
         [0017]     The invention also comprises a stent device for introduction into and for treatment of a bifurcation aneurysm, comprising: a radially expandable elongated wire mesh tube having a proximal end and a distal end, the distal end being expandable into a cone-shapeable portion of a larger diameter than its proximal end. The stent has foraminous wall portions with openings therein of a first opening size. A pierceable web of material is arranged across the distal end of the stent device for sealing an aneurysm at a neck portion thereof, the web having foraminous portions with openings therein of a second opening size. The second opening size being smaller than the openings of the first opening size. The stent device preferably as a circumferential array of radially outwardly splayable anchoring struts, the circumferential array of struts being disposed proximately adjacent a zig-zag distalmost wire wall portion of the cone-shapeable portion of the stent device. The anchoring struts have a distalmost tip portion which is preferably free of attachment to the zig-zag distalmost wire wall portion of the stent device, to permit their radial extension about the neck of an aneurysm.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which:  
         [0019]      FIG. 1  is a side view of a waffle cone stent within the parent vessel;  
         [0020]      FIG. 1A  is a view of the top of the stent shown in  FIG. 1 ;  
         [0021]      FIG. 2  is a side elevational view of a further embodiment of the stent, in an unexpanded form;  
         [0022]      FIG. 3  is a side elevational view of the waffle cone stent with a distal web arranged thereon;  
         [0023]      FIG. 4  is a side elevational view of the stent shown in  FIG. 3 , arranged within an aneurysm;  
         [0024]      FIG. 5  is a view of a micro catheter and micro wire delivery system for a stent;  
         [0025]      FIG. 6  is a view of the micro wire of the delivery system remaining in the aneurysm;  
         [0026]      FIG. 7  is a view of the delivery catheter and micro wire with a stent arranged therein.  
         [0027]      FIG. 8  is a view of a micro wire and micro catheter delivery arrangement;  
         [0028]      FIG. 9  is a view of a waffle cone stent in its pre-expanded configuration, delivered within an aneurysm;  
         [0029]      FIG. 10  is a view of an expanded waffle cone stent with a micro wire therethrough arranged within the aneurysm;  
         [0030]      FIG. 11  is a view of the expanded waffle cone stent in the neck of an aneurysm shown in the delivery of an embolytic member therewithin; and  
         [0031]      FIG. 12  is a view of the waffle cone stent expanded within the neck of an aneurysm, showing an embolytic member expanding and filling the aneurysm itself.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     The present invention comprises an elongated aneurysm treating stent device  20  having an open proximal end  22  and a closed distal end  24 , as shown in  FIG. 1 . The stent device  20  in its deliverable form is cylindrically shaped and is preferably constructed from a pattern of woven metallic fibers  26 , as is represented in  FIG. 2 . The proximal end  22  of the stent device  20  may have a plurality of radial opaque markers  28  thereon. An elongated electrolytic tethering wire arrangement  30  is secured at several circumferential locations on the proximal end  22  of the stent device  20 , as may be seen in  FIGS. 1 and 7 . The distal end of the tethering wire arrangement  30  comprises a plurality of short wires  32  which join a proximalmost common electrolytic tethering wire  33  which extends through a delivery catheter  34 . The tethering wires  32  are attached to the proximal end  22  of the stent device  20  that remain as electrolytic junctions  36 , as shown in  FIG. 1 . Those electrolytic junctions  36  are arranged so as to be severed by an electrical or mechanical severance means, not shown for clarity, once the stent device  20  has been put in place in or nesting adjacent an aneurysm  40 , as is represented in  FIGS. 1 and 4 . The webbed design of the stent device  20  is fabricated/woven so as to have larger openings or cells  42  between the web fibers towards the distal end  24  of the stent device  20 , than at its proximal end  22 , as represented in the embodiments shown in  FIGS. 1, 3 ,  4 ,  10 ,  11  and  12 . Further, upon expansion of the distal end  24  into its waffle cone configuration further facilitates the larger openings of that expanded stent  20  at its distal end  24 , as represented in  FIG. 4 .  
         [0033]     In one preferred embodiment of the present invention, a web or film of foraminous or perforable non-foraminous material  44  is disposed across the distal end  24  of the cone-shapable stent  20 , as represented in  FIG. 1A , so as to provide a sealing-like web across the neck  42  of an aneurysm  40  at a vessel bifurcation as represented in  FIGS. 1 , and  4 . That web  44  may in one embodiment, be perforable so as to permit the “piercing” passage of a microwire  50  therethrough as will be further explained hereinbelow.  
         [0034]     The stent device  20 , in its generally unexpanded form, as represented in  FIG. 2  may have a non-unitary distalmost web of sheet material  48  thereon, or alternatively, a unitary continuously woven/fabricated pattern  52  of cell openings  54 , distal of the generally cylindrically-shaped, main body portion  56  of the stent device  20  itself. The distal openings or cells  54  of the distal web  48  portion or the continued woven portion  52 , in a preferred format, are smaller than the cell or opening portions  57  in the main body portion  56  of the stent device  20 .  
         [0035]     In a further preferred embodiment of the present invention represented in  FIG. 3 , a plurality of somewhat “ski tip” shaped displaceable anchoring struts  60  are flayed generally radially outwardly, spaced proximally adjacent the distalmost “zig-zag” configuration (in this embodiment) of distal end wires  62  or portion of the stent device  20 , as is represented in  FIG. 3 . Those anchoring struts  60 , somewhat J-shaped have their respective distal ends  63  extending somewhat radially outwardly to a diameter somewhat less than the expanded diameter of the distalmost end wires  62  of those distalmost stent cells  66 .  
         [0036]     Those outwardly extending anchoring struts  60  are arranged so as to engage the innermost edge of the inwardly directed peripheral lip of the neck  42  of the aneurysm  40 , at the bifurcation, as is represented in  FIG. 4 . Such circumferential array of anchoring struts  62  thus prevents advancement and/or displacement of the distal end  24  of the stent device  20  from going too far within the aneurysm  40  itself. The “waffle-shaped cone” of the distal end of the stent device  20  thus is arranged to nest within the circumference of the aneurysm  40  adjacent its neck  42 . The stent device  20  with its distalmost screen tent provides a sealing web  44  thereacross, as is represented in  FIGS. 3 and 4 .  
         [0037]     The delivery of such a stent device  20  within a bifurcation aneurysm  40 , is represented in  FIGS. 5 through 9 , wherein a microwire  70  is directed through the parent vessel  72  and into the aneurysm  40 . The microcatheter  34  is fed over the microwire  70 , as is represented in  FIG. 5 . The microwire  70  after several steps, is however, ultimately removed. The microcatheter  34  is however temporarily left within the aneurysm  40  at the bifurcation  71 , as represented in  FIG. 7 . The waffle cone stent is loaded through the microcatheter  34  and is advanced over the microwire  70  and into the aneurysm  40  through the parent vessel  72 . The electrolytic tethering wire arrangement  30  is attached to the proximalmost end  22  of the waffle cone stent  20 , as represented in  FIG. 7 . The delivery catheter  34  surrounding the waffle cone stent device  20  may then be removed proximally, as suggested by the representation in  FIG. 8 , so as to expose the waffle cone stent device  20  to/against the walls of the parent vessel  72 , as represented in  FIG. 9 . The distalmost end  24  of the waffle cone stent device  20  is thus permitted to expand immediately within the neck  42  of the aneurysm  40 , as represented in  FIG. 10 . The anchoring struts  60  expand radially outwardly along with the distalmost portion of the waffle cone stent device  20 , as represented in  FIGS. 4 and 11 , so as to nest within the neck  42  of the aneurysm  40 , as represented in  FIGS. 4, 10 ,  11  and  12 . A microcatheter  84 , represented in  FIG. 11 , may be introduced over the microwire  70  within the waffle cone stent device  20 , and is utilized to feed an elongated embolytic member  80  for delivery into the aneurysm  40  itself, as is represented in  FIGS. 11 and 12 . Such a microcatheter or embolytic material may in one embodiment, pierce the web or film  44 , or pass through one of the small cell openings  90  in the distally located web  44  of the waffle cone shaped stent device  20 , initially represented in  FIG. 1A . The result would be an embolytic member fully engulfing the aneurysm  40  while its microcatheter delivery system  34  is removed therefrom. The waffle cones stent device  20  with its anchoring structs expanded  60 , would remain secured within the aneurysm  40  as well. The expanded open cell structure of the distal end portion  24  of the waffle cone stent device  20  would permit blood to flow through the parent vessel and across the arms  77  of those adjoining vessels at the bifurcation.