Abstract:
Devices are provided for isolating an aneurysm from the blood vessel, particularly berry aneurysms within the cerebral vasculature. Embodiments of such devices have improved manufacturability, deliverability find isolation of the aneurysm. Delivery systems are also provided for such devices and other devices which may benefit from orientation adjustment during delivery.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The term aneurysm refers to any localized widening or outpouching of an artery, a vein, or the heart. All aneurysms are potentially dangerous since the wall of the dilated portion of the involved vessel can become weakened, and may possibly rupture. 
         [0002]    A common type of aneurysm, is a brain aneurysm. Brain aneurysms are widened areas of arteries or veins within the brain itself. These may be caused by head injury, an inherited (congenital) malformation of the vessels, high blood pressure, or atherosclerosis. A common type of brain aneurysm is known as a berry aneurysm. Berry aneurysms are small, berry-shaped outpouchings of the main arteries that supply the brain and are particularly dangerous since they are susceptible to rupture, leading to often fatal bleeding within the brain. Brain aneurysms can occur at any age but are more common in adults than in children. 
         [0003]    A variety of devices have been developed to cover such aneurysms, including stentlike devices having a one-sided covering or patch to cover the opening of the aneurysm along the blood vessel. However, such devices are often difficult to construct and deploy. In particular, these one-sided coverings need to be correctly oriented and deployed so as to cover the aneurysm opening. This is challenging in that the vascular anatomy preceding most aneurysms is very tortuous and long and therefore difficult to control and transmit torque for precise delivery. Therefore, improved devices for treatment of aneurysms are desired along with improved delivery devices and methods. At least some of these objectives will be met by the present invention. 
       SUMMARY OF THE INVENTION 
       [0004]    The description, objects and advantages of the present invention will become apparent from the detailed description to follow, together with the accompanying drawings. 
         [0005]    Disclosed herein are vascular prosthesis for use in covering aneurysms or to provide other support within the vasculature. The disclosure also includes delivery systems for deploying such devices. In one variation the prosthesis comprise a body member having a first axis, the body member being axially extendable and compressible along the first axis, where the body member is coiled about a second axis to form a coiled prosthesis shape having a lumen extending therethrough to allow fluid flow, the coiled prosthesis shape having a plurality of adjacent helical turns separated by a gap, where the coiled prosthesis is radially adjustable relative to the second axis by adjusting the gap between the helical turns and the coiled prosthesis is also radially compliant relative to the second axis by extension and compression of the body member along the first axis. 
         [0006]    In an additional variation, the body member of the prosthesis may comprise a super elastic material having a pattern that allows for expansion and compression along an axis of the body member. In additional variations, the body member can include a braided or woven tubular structure. 
         [0007]    An additional variation of the prosthesis includes a plurality of wire members being wound about an axis to form a coil shape, the coil shape having a lumen extending therethrough to allow fluid flow, where the plurality of wire members include at least a first and a second wire members, the first wire member having a first end, a second end, and a mid-portion therebetween being wound about the axis, the second wire member having a first end, a second end, and a mid portion therebetween being wound about the axis, and where the first, ends of the first and second wire member are coupled together and the mid-portions of the first and second wire members are uncoupled. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]      FIGS. 1A to 3B  illustrate variations of a coiled vascular prosthesis having undulations of the body member used to form the prosthesis. 
           [0009]      FIG. 4A  illustrates a stretched prosthesis that is fabricated by a heat-set flattened braided tube being wrapped in helical or coiled pattern. 
           [0010]      FIG. 4B-4C  illustrate a variation of a braided tube used to fabricate the prosthesis of  FIG. 4A . 
           [0011]      FIG. 4D  shows the prosthesis of  FIG. 4A  when in a relaxed state and showing the overlapping of the turns of the braided tube. 
           [0012]      FIG. 4E  shows the prosthesis of  FIG. 4D  when the prosthesis is in a curved or bent configuration such that the overlapping of the turns decreases at the bend. 
           [0013]      FIGS. 6A-6D  illustrates another embodiment of a delivery system and covering device. 
           [0014]      FIG. 7  illustrates the covering device of  FIGS. 6A-6D  positioned within a bifurcated blood vessel. 
           [0015]      FIGS. 8A-8C  illustrates a covering device comprised of a shape memory material having a coiled shape. 
           [0016]      FIG. 9  illustrates a delivery system for used in delivering the covering device of  FIGS. 8A-8C . 
           [0017]      FIG. 10  illustrates an example of a covering device as in  FIGS. 8A-8C  positioned within a blood vessel so as to isolate an aneurysm. 
           [0018]      FIGS. 11A-11B  illustrates an example of a covering device as in  FIGS. 8A-8C  having a covering. 
           [0019]      FIGS. 12A-12C  illustrate a dual coil system. 
           [0020]      FIGS. 12D-12E  illustrates additional variations of the dual coil system comprising a plurality of coiled wires that are joined at the ends of the device but diverge towards a center of the device. 
           [0021]      FIGS. 13A-13B ,  14 ,  15  illustrate an embodiment of a covering device comprising a stent having a coil shape and a covering. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]      FIG. 1A  illustrates a first variation of a coiled vascular prosthesis  200 . As shown, the coiled prosthesis  200  comprises a body member  202  that is coiled about an axis  204 .  FIG. 1B  shows the body member  202  prior to being coiled into a shape of a coiled prosthesis. As this variation illustrates, the body member  202  includes a series of undulations or a sinusoidal shape  212 . Accordingly, the body portion is able to expand or contract along an axis of the body portion  206 . Because of this feature, the coiled prosthetic shape  200  exhibits an improved compliance as compared to a simple coil when set within the vasculature. 
         [0023]    For instance, because of its coiled arrangement, the coiled prosthetic shape  200  can increase from a small diameter configuration (e.g., by being wound tightly about a catheter, guidewire, or mandrel) for delivery to a location within the vasculature. Ultimately the coiled prosthesis  200  is deployed and assumes a larger profile. Upon deployment, the coiled prosthesis expands, or is expanded, at the target site. In such a configuration, the gap between the turns  208  increase or decrease as the coiled prosthesis  200  expands or reduces in diameter. However, because the body member  206  is able to expand or contract longitudinally relative to its axis  206 , the coiled prosthesis  200  includes another degree of compliance. For example, the undulations of the body portion  202  can expand or contract, when the body portion  202  is wrapped in the coiled prosthetic shape without significantly affecting the gap between adjacent turns  208  of the prosthesis. In such a case, the spacing  214  between the undulations  212  (undulation gaps  214 ) increase or decrease on respective expansion or contraction longitudinally relative to its axis  206 . 
         [0024]    The prosthesis may be non-resilient, e.g., malleable, thus requiring the application of an internal force to expand it at the target site. Such an expansive force can be provided by a balloon catheter. Alternatively, the prosthesis can be self-expanding. Such self-expanding structures are provided by a temperature-sensitive superelastic material, such as Nitinol, which naturally assumes a radially expanded condition once an appropriate temperature (e.g., body temperature) has been reached. Another type of self-expanding structure uses resilient, material, such as a stainless steel, titanium, or superelastic alloy, and forming the body segment so that it possesses its desired, radially-expanded diameter when it is unconstrained, e.g., released from radially constraining forces a sheath. To remain anchored in the body lumen, the prosthesis will remain partially constrained by the lumen. The self-expanding prosthesis can be delivered in its radially constrained configuration, e.g. by placing the prosthesis within a delivery sheath or tube and retracting the sheath at the target site. Such general aspects of construction and delivery modalities are well-known in the art and do not comprise part of the present invention. 
         [0025]      FIG. 1C  shows a graft material or other covering  216  about the coiled prosthesis  200 . Naturally, the covering  216  should allow for expansion and contraction of the prosthesis  200  as noted above. The covering  216  can be placed about a portion of or the entire prosthesis  200 . 
         [0026]      FIG. 1D  shows another variation of the covering  216  placed about the body member  202  rather than the entire coiled shaped prosthesis  200 . Again, the covering can be placed on a portion or on the entire body member  202  depending on the desired application. In addition, a single device can have a combination of the configurations shown in  FIGS. 1C and 1D . 
         [0027]    The grafts or coverings  116  for use with the present devices can be porous PTFE or ePTFE. In those cases where the graft material  116  is sealed to the body member or coiled prosthesis by a variety, the sealing may occur for example, by using an adhesive or by placing a suitable heat seal material, such as FEP (fluorinated ethylene propylene) or other thermoplastic materials, between layers of the material  116  that sandwich the body member  202  or prosthesis  200 . In which case, application of heat and pressure completes the seal. In addition, a direct bond of the material to itself, via a process known as sintering, may be employed. Other methods for sealing the material could also be used. Coiled stent graft  122  includes a number of spaced apart turns  128  defining a generally helical gap  130  therebetween. 
         [0028]      FIG. 2A  illustrates another variation of coiled prosthesis  200  formed from a body member  202  as illustrated in  FIG. 2B . In this variation, the body member  202  comprises undulations  212  to form a “zig-zag” pattern. As with the above variations, the body member  202  is expandable and compressible with respect to an axis of the body member  206  to provide the coiled prosthetic shape  200  with an additional degree of compliance apart from increasing or decreasing the gap  210  between turns  208  of the prosthesis  200 . Clearly, the edges shown in the prosthesis of  FIG. 2A  can be made atraumatic by covering or coating with a graft material or polymer. Alternatively, all or some of the edges can be made rounded to reduce unwanted trauma to the vasculature. 
         [0029]      FIG. 3A  shows another variation of a coiled prosthesis  200  formed from the body member  202  illustrated in  FIG. 3B  and having a closed or crossed cell configuration. As shown, the body member  202  includes a series of undulations  212  that define a cell  218 . As with the variations shown above, the body member  202  can expand and compress with respect to an axis of the body member  206  to provide the coiled prosthetic shape  200  with an added degree of compliance. As with other variations, the edges shown in the prosthesis of  FIG. 3A  can be made atraumatic by covering or coating with a graft material or polymer. Alternatively, all or some of the edges can be made rounded to reduce, unwanted trauma to the vasculature. In addition, the ends of the prosthesis  200  can have legs  240  to reduce the possibility of undesired trauma caused by the end of the prosthesis in a vessel. 
         [0030]    The body members  202  shown above may be fabricated from a shape memory alloy (e.g., a super-elastic alloy) where the body member  202  is cut or formed to form the desired pattern either in sheet material that, is subsequently heat set into a spiral, or originally cut from tubular stock as shown in  FIG. 2A . The same holds true for the implant in  FIGS. 3A and 3B . The variations shown in  FIG. 1  can also be so constructed. In such case, the highly rounded profile can be obtained by aggressive electro-polish (EP). Otherwise, it can be constructed using bent or heat-set wire stock. 
         [0031]      FIG. 4A  illustrates another variation of a coiled vascular prosthesis  230  formed from a braided or woven tubular body member  232 .  FIG. 4A  shows the coiled vascular prosthesis  230  as being extended for purposes of illustration. To form the prosthesis  230 , a braided or woven tube  232  is helically wound about an axis  234 . It may be first flattened e.g., by heat setting, or just simply be wound flat on an appropriately shaped mandrel.  FIG. 4B  shows a variation of a tube  232  that is ultimately forms the body member of the device shown in  FIG. 4A . As shown, the tube  232  is formed about its own axis  236 .  FIG. 4C  shows flattening of the tube of  FIG. 4B . After flattening of the tube, it may then be helically configured. However, the tube  232  may be formed with an elliptical or other cross section without being fully compressed. The individual wires forming the tube  232  can be shape memory or super elastic wires.  FIG. 4A  shows the end of the prosthesis as being capped  242 . For example, the ends of the wires can be wound by a single filament or wire. 
         [0032]    As shown in  FIG. 4D , the tube  232  of  FIG. 4C  may be wrapped about an axis  234  such that adjacent turns  236  of the tube  232  overlap one another at joining edges  238 . One benefit of this overlapping of adjacent turns is shown in  FIG. 4E . Here, when the prosthesis is bent, the turns  236  spread apart on a side of the device that is opposite to the bend. The spreading of the turns  236  decreases the overlap  238  so that the adjacent turns  236  eventually abut one another. Such a feature is useful when the prosthesis is placed within curved vasculature where the adjacent spread/flatten out rather than group together. While not shown, the prosthesis may also be configured so adjacent turns of the coil merely abut or are in close proximity to one another. Such an arrangement can offer an improved tissue interface. 
         [0033]      FIGS. 6A-6D  illustrate an embodiment of a delivery system and covering device for use with prosthesis described herein. Referring to  FIG. 6A , the delivery system  130  comprises a delivery catheter  132  and the covering device comprises a stent  136 . In this illustration, the stent  136  is in a collapsed coiled shape, however any suitable shape, such as those described above or any other coiled shape, may be used. During delivery, the stent  136  is collapsed onto a distal portion of the delivery catheter  132  to allow for advancement of the catheter  132  through a blood vessel V to an aneurysm A. Referring to  FIG. 6B , the stent  136  is then partially expanded and a lumen  338  is advanced from the delivery catheter  132  towards the aneurysm A. Alternatively, the lumen  138  could be in fixed position and simply utilized at the time of need. Referring to  FIG. 6C , a sheet or disc is then extended from the lumen  13   8  so as to isolate the aneurysm A forming the covering  18 . The covering  18  is supported by the partially expanded stent  136 . The covering device  24  may be rotated by any of the mechanisms described herein to desirably position, the covering  18  over the aneurysm A. Note that the stent  136  can be partially expanded in an incremental fashion a number of times to facilitate proper placement; in this manner the stent can be expanded to bring the covering  18  close enough to the aneurysm to allow for proper evaluation of position, yet still allow rotational movement to optimize positioning. Once, desirably positioned, the stent  136  may be fully expanded within the blood vessel V which holds the covering  18  is place, as illustrated in  FIG. 6D . The delivery system  130  may also be used to deliver such a stent  136  to an aneurysm A at a bifurcated blood vessel V, as illustrated in  FIG. 7 . 
         [0034]    Most currently available conventional stents, whether neurological, cardiac, or peripheral in application, transform from a collapsed state for delivery to an expanded state for application. In most, or possibly all, cases, the collapsed state is a slightly diminished version of the expanded state but is not substantially different in shape or form. For example, the collapsed state is slightly smaller in outer diameter than the expanded state but perhaps not substantially different in other aspects. In addition, the collapsed state is limited in how small it can be (i.e. outer diameter cannot be smaller than a certain percentage of the expanded state outer diameter), and thus the ability to deliver stents in the collapse state to small vessels, such as neurological vessels, is limited. Therefore, the present invention provides a covering device  24  which has a different shape when in its collapsed state, allowing for a smaller cross-sectional diameter. 
         [0035]    An example of such a covering device  24  is illustrated in  FIGS. 8A-8C . Here, the covering device  24  comprises a shape memory material, such as nitinol, and has a coiled shape when, in an expanded state but a substantially straight or slightly curved shape when in a collapsed or unexpended state.  FIG. 8A  illustrates a delivery catheter  140  having an inner lumen  142  wherein the covering device  24  is loaded within the lumen  142  in a collapsed state. As shown, the covering device  24  has a substantially straight or slightly curved shape.  FIG. 8B  illustrates deployment of the covering device  24  into a blood vessel V. As the device  24  is released from the lumen  142 , the coil expands to fill the vessel V.  FIG. 8C  illustrates the device  24  deployed from the catheter  140  and fully expanded. Such deployment may be achieved by “pushing” the device  24  out of the lumen  142  with the use of, for example, a push tool or mandrel, or the catheter  140  may be retracted to expose the device  24  thereby deploying the device  24 . 
         [0036]    Since the embodiment of the covering device  24  illustrated in  FIGS. 8A-8C  has a coiled shape, the device  24  may have a tendency to rotate as it is deployed from the lumen  142 . Such rotation, particularly against an inner surface of the blood vessel V, may not be desired. Therefore, in some embodiments, the delivery catheter  140  has a rotating distal section  150 , as illustrated in  FIG. 9 . Such a rotating distal section  150  may be actively rotatable or passively rotatable. Thus, as the device  24  contacts the wall of the blood vessel V, the distal section  150  can passively rotate, allowing the device  24  to remain rotationally stable (i.e. non-rotating). Alternatively, the distal section  150  can actively rotate as the device  24  is delivered to keep the device  24  from rotating. 
         [0037]      FIG. 10  illustrates an example of a covering device  24 , such as illustrated in  FIGS. 8A-8C  positioned within a blood vessel V so as to isolate an aneurysm A. As shown, the spacing of the coils of the device  24  are adjusted manually during delivery so that the coils are denser over the aneurysm A. Such spacing may be visualized during delivery with the use of fluoroscopy. Therefore, blood flowing through the blood vessel V is isolated from, the aneurysm A by the densely spaced coils of the device  24  in the area of the aneurysm A. 
         [0038]      FIGS. 11A-11B  illustrate an example of a covering device  24  as in  FIGS. 8A-8C  having a covering  18 . In this embodiment, the covering  18  has the form of a strip or partially circumferential element, as shown.  FIG. 11A  shows the device  24  compressed within a delivery catheter  140  wherein the covering  18  is held by the delivery catheter  140 . Note that covering  18  could be located on the inside or on the outside of catheter  140  prior to deployment. The covering  18  is then removed from the delivery catheter  140  by the device  24  during deployment of the device  24 . The distal end of device  24  is attached to the covering  18 , such that when device  24  is extended from the catheter  140  for delivery, the covering  18  is extended and deployed also. Referring to  FIG. 11B , the device  24  is thus positioned within the blood vessel V so that the covering  18  isolates the aneurysm A from the blood vessel V. 
         [0039]      FIGS. 12A-12C  illustrate another embodiment of a covering device  24  of the present invention. In this embodiment, the covering device  24  comprises a dual coil system having a first coil  170  wound in a first direction and a second coil  172  wound in a second direction which is opposite to the first, direction, as illustrated in  FIG. 12A . The coils  170 ,  172  may he loaded into a delivery catheter  174 , as illustrated in  FIG. 12B . The coils  170 ,  172  may then be deployed into a blood vessel forming a covering device  24 , as illustrated in  FIG. 12C . This covering device  24  may isolate an aneurysm A in a manner such as illustrated in  FIG. 33  or may utilize a covering such as in  FIG. 12B . The coils  170 ,  172  may or may not be connected to one another at the distal end of each coil. 
         [0040]      FIG. 12D-12E  illustrate another vascular prosthesis  250  comprised of a plurality of wires  252 ,  254  that are wound about an axis  262  to form a coil shape. It is noted that any number of wires can be incorporated into the design but two wires are illustrated for exemplary purposes only. 
         [0041]    As shown, the first and second wires  252 , 254  are coiled to form the device but one wire is helically wound about the second wire at ends  256  and  258 . In alternate variations, the wires may be joined by any commonly known fastening mode. However, the wires diverge or decouple towards a center of the device  250 . In some variations, a section  260  of the device  250  can be fabricated to have a high surface area or density (by high surface area or high density area it is meant that there will be smaller gaps between adjacent turns of the wire or wires). This way, the central section may serve to isolate an aneurysm, while the side sections may help anchor the implant without obstructing adjacent blood vessels. 
         [0042]      FIG. 12D  shows the plurality of coiled wires being wound in a single or similar direction such that the coils or turns are parallel. In contrast,  FIG. 12E  shows a plurality of wires wrapped to form a coiled prosthesis  250  but where the wires  252  and  254  are wound in opposite or different rotational directions such that the coils or turns are crossed. In this manner, better coverage maybe possible when implanting the prosthesis around a bend in the neuron-vasculature. Again, the wires  250  and  254  are joined together at the ends  256  and  258  of the device  250  and diverge or decouple towards a mid portion of the device. As with  FIG. 12D , the variation of  FIG. 12E  can include a high density of wires or turns towards a center section of the device  250 . 
         [0043]    In one variation, the joining of the coils are sufficiently long such that the double-coil (or the portion where the coils diverge) are located only across the aneurysm neck while any perforators are better protected. The outer intertwined coil approach may also serve this purpose or merely act to efficiently connect the plurality of wires/filaments. 
         [0044]      FIGS. 13A-13B ,  FIG. 14  and  FIG. 15  illustrate another embodiment of a covering device  24  of the present invention. In this embodiment the covering device  24  comprises a stent  180 , having a coil shape, and a covering  18 .  FIGS. 13A-13C  illustrate a cross-section of one of the turns of the coil shaped stent  180 . The covering  18  comprises a mesh, fabric or polymeric material that has a springiness or memory so that the covering  18  may collapse around the stent  180 , as illustrated in  FIG. 13A , and expand when released, as illustrated in  FIG. 13B . If the covering  18  is comprised of a polymeric material, the covering  18  may be heated and shaped to impart a memory effect, such as using techniques similar to those used in forming conventional folded angioplasty balloons. Alternatively, the covering  18  may be comprised of a material that has springiness or memory provided, by one or more thin shaped memory wires  182 , such as nitinol, that is set or fused with the covering  18 , as illustrated in  FIG. 14 .  FIG. 15  illustrates the covering device  24  deployed within a blood vessel V. As shown, the covering  18  extends between the turns of the coil forming a continuously covered stent  180 . However, the turns of the coil may be manually spaced during delivery, similar to  FIG. 10 , so that the covering  18  is continuous over an aneurysm A and open near feeder vessels. Additionally, the covering  18  could be semi porous. Manually overlapping adjacent sections of covering  18  as the stent  180  is deployed could result in a final covering with different porosities, with areas of single covering being more porous and areas of overlapping covering being less porous. 
         [0045]    Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that various alternatives, modifications and equivalents may be used and the above description should not be taken as limiting in scope of the invention which is defined by the appended.