Abstract:
The present invention relates to an aneurysm stent having a base and connector. The base has a vessel facing side and an aneurysm facing side, and is shaped to cover an aneurysm sufficiently. The connector is coupled to the aneurysm facing side of the base such that when deployed the connector is adapted to extend partially into the aneurysm to anchor the base about the aneurysm and inhibit flow into the aneurysm.

Description:
[0001]    The present invention claims the benefit of U.S. Provisional Application Serial No. 60/404,422, filed Aug. 19, 2002, titled CEREBRAL ANEURYSM COIL STENT, incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to the surgical repair of aneurysms and, more particularly, to a patch that provides a seal between the arterial wall and a neck of the aneurysm to inhibit flow in the aneurysm.  
         BACKGROUND OF THE INVENTION  
         [0003]    An aneurysm is a blood-filled dilation of a blood vessel. Major concerns with aneurysms revolve around rupturing of the arterial wall causing internal bleeding and clots breaking away from the aneurysm causing strokes.  
           [0004]    There exist two generally approved methods of treating aneurysms. The first method of treatment includes surgical treatment. The second method of treatment includes endovascular treatment. Surgical removal of the aneurysm is sometimes not possible, leaving endovascular treatment as the only available option. Even when not the only option, endovascular treatment often is preferred because of the reduced risks and complications.  
           [0005]    Conventionally, endovascular treatment of an aneurysm involves “packing” the aneurysm such that an endovascular occlusion is formed. Packing the aneurysm with coils, such as Guglielmi Detachable Coils (or GDCs), helps form an occlusion. While using GDCs is conventional, the aneurysm can be packed with numerous devices, such as, for example, other types of coils, balloons, glues, polymers, clotting agents, liners, or the like.  
           [0006]    Endovascular treatment, while considered less risky than surgical treatment, has drawbacks. One drawback of endovascular treatment of the aneurysm includes the potential to over pack the aneurysm. Over packing the aneurysm can cause the material to enter the parent blood vessel, potentially inhibiting blood flow or generate undesirable pressure in the aneurysm. Also, some aneurysms have a wide connection to the blood vessel, a.k.a. wide neck aneurysms. Wide neck aneurysms have the additional risk that the occluded material will break free of the aneurysm and enter the parent blood vessel, potentially causing blockage of the parent blood vessel. Finally, clotting agents and polymers used to form occlusions in the aneurysm can seep to the parent blood vessel causing complications. Balloons and liners are intuitively pleasing as a solution, but have the potential for an inexact fit causing complications. For example, a balloon may be over inflated causing unwanted pressure or under inflated causing seepage in the aneurysm.  
           [0007]    While the packing methods described above inhibit blood flow to the aneurysm, the aneurysm neck typically is open to the parent blood vessel. Thus, blood continues to flow to the aneurysm. To reduce the blood flow, several devices have been developed to cover the neck area of the aneurysm.  
           [0008]    U.S. Pat. No. 6,454,780, issued Sep. 24, 2002, to Wallace, titled Aneurysm Neck Obstruction Device, shows a device designed to cover or block the neck of the aneurysm. FIG. 1 shows the Wallace device  10  in some detail. The device  10  is placed inside aneurysm  50  using a catheter  46  and deployment tool  44 . When inside the aneurysm  50 , device  10  has walls  12  that expand or unfold to contact the inside of the aneurysm  50  and block neck  51 . But the device resides internal to aneurysm  50  allowing blood flow shown by arrow A in the parent vessel  52  to push up against the walls  12 . The upward pressure of the blood vessel on the wall  12  may allow blood from the parent vessel to seep in aneurysm  50 . Also, because the wall is internal to the aneurysm  50 , the neck  12  has the potential to expand. Other types of internal devices include liners and other neck bridges.  
           [0009]    Devices to block the neck of the aneurysm external to the aneurysm exist also. These devices use the pressure of the blood vessel to help seat the block against the parent vessel wall and shield the neck from the blood vessel. One such device is shown in U.S. Pat. No. 6,309,367, issued Oct. 30, 2001, to Boock, titled Aneurysm Shield. The Boock device is shown in FIG. 2. The Boock device  30  has a cylindrical shaft  32  that covers the neck  37  of the aneurysm  38  and is anchored by anchor rings  34  and  36 . While device  30  resides external to the aneurysm it has multiple parts that could break free or deteriorate that reside in the parent vessel. While the Boock device  30  seemingly works for its intended purpose in theory, its relatively large size and surface area makes its impractical to actually use. In the brain, for example, multiple blood vessels may branch off from the location of an aneurysm. Attempting to use the Boock device would block blood flow to one or more of the branch vessels as well as the aneurysm, which makes the Boock device useful in only limited situations, if any.  
           [0010]    Thus, it would be desirous to develop and improve internal and external aneurysm stents.  
         SUMMARY OF THE INVENTION  
         [0011]    To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, apparatuses to inhibit the flow of blood to an aneurysm comprise a base and connector. The base has a vessel facing side and an aneurysm facing side, and is shaped to cover an aneurysm sufficiently. The connector is coupled to the aneurysm facing side of the base such that when deployed the connector is adapted to extend partially into the aneurysm to anchor the base about the aneurysm and inhibit flow into the aneurysm.  
           [0012]    The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0013]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention, and together with the description, serve to explain the principles thereof. Like items in the drawings are referred to using the same numerical reference.  
         [0014]    [0014]FIG. 1 shows a prior art aneurysm device;  
         [0015]    [0015]FIG. 2 shows a prior art aneurysm device;  
         [0016]    [0016]FIG. 3 shows a perspective view of an aneurysm stent deployed in a blood vessel illustrative of the present invention;  
         [0017]    [0017]FIG. 4 shows a cross section of a blood vessel with an aneurysm prior to deployment of the aneurysm stent illustrated in FIG. 3;  
         [0018]    [0018]FIG. 5 shows a cross section of the aneurysm stent just prior to deployment;  
         [0019]    [0019]FIG. 6 shows a cross section of the aneurysm stent mostly deployed about the aneurysm;  
         [0020]    [0020]FIG. 7 shows a cross section of the aneurysm stent deployed;  
         [0021]    [0021]FIG. 8 shows a cross section of a portion of a stent consistent with the present invention;  
         [0022]    [0022]FIGS. 9A and 9B show a stent consistent with the present invention; and  
         [0023]    [0023]FIGS. 10A and 10B show a cross-section of a stent consistent with the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0024]    Some embodiments of the present invention are described with reference to FIGS.  3  to  10 B. FIG. 3 shows an aneurysm stent  300  consistent with an embodiment of the present invention deployed. Stent  300  is deployed in a parent blood vessel  302 , which is shown as an artery but could be a vein a capillary, or the like, about aneurysm  304 . A blood flow path from vessel  302  to aneurysm  304  is provided by an aneurysm neck  306 . Neck  306  is shown as a narrow neck, but could be a wide neck. Aneurysm  304  is shown packed with conventional GDCs  308 . While shown as packed with conventional coils, aneurysm  304  could be packed with any type of packing agent, such as, for example, other types of coils, balloons, glues, polymers, clotting agents, liners, or the like. In fact, aneurysm  304  does not need to be packed at all as stent  300  blocks blood flow to aneurysm  304 . The attachment of stent  300  to cover neck  306  will depend, in part, on the type of material used to pack aneurysm  304 , if any.  
         [0025]    With reference to FIG. 3, which illustrates aneurysm  304  packed with conventional GDCs  308 , stent  300  includes a base  310 , a base connection point  312 , and a connector  314 . Base  310  has opposed sides, a vessel side and a wall side (not specifically labeled). The vessel side can be covered with a graft material or other biocompatible material. The vessel side may be coated with a material to stimulate cell growth and encourage formation of a pseudointima. The wall side could be covered with an adhesive to assist in seating stent  300  about neck  306  by forming a seal between base  310  and vessel  302 . Base connection point  312  couples base  310  to connector  314 . Base connection point  312  does not need to exist as a separate component, but is identified for convenience to distinguish between base  310  and connector  314 . Base connection point  312  could, as a matter of design choice, be a fitting to connect base  310  and connector  314  if desired. Connector  314  can be a conventional coil material attached to base  312  that extends to GDCs  308 . When deployed, connector  314  assumes its coiled shape and engages GDCs  308  to assist in keeping stent  300  seated about neck  306 . Connector  314  could physically curl around or hook into GDCs  308  for anchoring, but connector  314  could simply pack in aneurysm  304  similar to a conventional GDC. Connector  314  could simply anchor stent  300  in place, but could also contract and pull base  310  snug against vessel  302  to firmly seat base  310  about aneurysm neck  306  further inhibiting blood flow to aneurysm  304 . While only one base connection point  312  and one connector  314  is shown in FIG. 3, multiple connections and connectors are possible. Also, the connections do not necessarily have to be in the center of the stent, but could be offset. It is believed greater stability will be obtained by symmetrical placement of connectors and connection points, but asymmetrical placement is possible. Multiple connectors could be attached to a single connection point as well.  
         [0026]    Referring now to FIGS.  4 - 7 , a method of deploying the stent  300  will be described. Referring first to FIG. 4, parent vessel  302  is shown with aneurysm  304  and neck  306  existing off the main body of vessel  302 . Unlike FIG. 3, a second vessel  402  resides about neck  306  forming a junction  404 . While the present invention will be explained in connection with deploying stent  300  about junction  404 , stent  300  could be similarly deployed at locations with more or less junctions. First, aneurysm  304  is packed using, for example, conventional GDCs  308  in a conventional manner. Without going in much detail, GDCs  308  are placed by first directing a catheter  406  to the site of aneurysm  304 . GDCs  308  are passed through catheter  406  and packed in aneurysm  304  in a conventional manner. Once GDCs  308  are placed, stent  300  is passed through the same or a different catheter  406  using a guide wire  502  (FIG. 5). Stent  300  includes base  310  and connector  314 . As can be seen, base  310  is compacted to pass through catheter  406 . Also, connector  314  enters the packed GDCs  308 .  
         [0027]    Referring now to FIG. 5, stent  300  has exited catheter  406  and guide wire  502  can be seen attached to stent  300 . Base  310  is approaching neck  306  and connector  314  has extended in GDCs  308  packed in aneurysm  304 . As shown, base  310  can be made of a self-expanding material that begins expanding on exiting catheter  406 . Alternatively, base  310  can be made of a material that requires activation or other manipulation to expand.  
         [0028]    Referring now to FIG. 6, stent  300  is shown in the appropriate position and guide wire  502  has been withdrawn. Base  310  has expanded sufficiently to mostly block neck  306  and connector  314  has begun curling, packing, embedding or otherwise anchoring in aneurysm. For example, connector  314  can be placed about GDCs  308  as conventional packing material, connector  314  can curl and engage GDCs  308 , or the like. While one connector  314  is shown, it would be possible to have two of more connectors  314 . As described in more detail below, a number of other devices and techniques can be used to anchor stent  300  about the neck.  
         [0029]    Referring now to FIG. 7, stent  300  is shown with base  310  and connector coils  314  fully deployed. In this case, base  310  is flush with the wall of vessel  302 , wraps around junction  404  and is flush with the wall of vessel  402 . Connectors  314  are engaged with GDCs  308  and, optionally, connectors  314  contract in a manner that pulls base  310  in toward GDCs  308  providing a snug seating between base  310  and vessel  302 .  
         [0030]    The stent  300  could be made of many materials. Some material includes conventional graft material. Alternatively, stent  300  could be made of one or more shaped memory alloys (SMAs) or a combination of graft material and SMAs. SMAs are a group of materials that demonstrate an ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Generally, these materials can be plastically deformed and, upon exposure to thermal manipulation, will return to the pre-deformation shape. Some SMA material is considered to be two-way shaped memory alloys because they will return to the deformed shape upon proper thermal activation. SMAs include Ag—Cd alloys, Cu—Al—Ni alloys, Cu—Sn alloys, Cu—Zn alloys, Cu—Zn—Si alloys, Cu—Zn—Sn alloys, Cu—Zn—Al alloys, In—Ti alloys, Ni—Al alloys, Ni—Ti alloys, Fe—Pt alloys, Mn—Cu alloys, Fe—Mn—Si alloys, and the like. As shown by FIGS.  4 - 7 , SMAs would work well for stent  300  because, for example, connectors  314  could be shaped with a predefined curl that will engage GDCs  308 . The SMA could be deformed at a predefined temperature to a straight, or substantially straight, shape to allow for connectors  314  to penetrate packed GDCs  308  in aneurysm  302 . Thermal manipulation would cause connector coils  314  to assume the original curled shape that will anchor stent  300  about aneurysm  302  and may provide a force tending to pull base  310  in towards aneurysm  302  further seating stent  300  about aneurysm  302 . Similarly, base  310  could be made of SMA. In this case, base  310  could be originally shaped to approximate the shape of the vessel(s) around aneurysm neck  304  to allow for as close a fit as possible. This would also allow use of stent  300  in areas having many vessels branching around the aneurysm.  
         [0031]    As shown in FIGS.  3 - 7 , base  310  is shown having a circular or semicircular shape. In particular, FIG. 3 illustrates base  310  as a coil of material that expands on deployment. The shape of base  310 , however, is largely a function of material, design choice, and the aneurysm location. Thus, stent  300  could take many shapes including triangular, rectangular, square, elliptical, conical, spherical, circular, cylindrical, or the like  
         [0032]    The present invention has been described with the aneurysm packed with conventional GDC coils, as described above, the aneurysm could be packed with alternative material. For example, if the aneurysm was packed with a polymer or clotting agent, the connector or anchor could be a simple post connected to the stent and embedded in the occlusion. Base  310  connected to the post would be held in place by the occlusion. Further seating force could be supplied by using a material that contracts on activation, such as SMAs. If the aneurysm was packed with a liner or balloon, a connection post could be provided on the balloon or liner to allow attaching the stent to the balloon or liner. For example, a balloon inserted in aneurysm  302  could have a flanged lower post (similar to some helium balloons) that connector coil  314  could wrap around. In this case, if, for example, connector coil  314  was made out of SMAs, thermal activation could cause coil  314  to tighten around the post attached to the balloon and contract. The contraction would be resisted by the flange on the post tending to pull base  310  in towards aneurysm  302  to assist in seating base  310  about aneurysm  302 . Alternatively to a post, the stent could have prongs that extend along the inside walls of the aneurysm such that the expanded balloon or liner would press the prongs against the wall of the aneurysm and seat the stent. Referring to FIG. 8, base  310  could be designed with a clamp  802  around an edge  804  of base  310 . As shown, clamp  802  could have opposed surfaces  806  such that when deployed, surfaces  806  move together and grip vessel  302  at neck  306 . A ridge  808  could be provided to assist in the grip. Clamp  802  would be particularly useful if aneurysm  304  was not packed with anything.  
         [0033]    Referring to FIGS. 9A and 9B, another stent  900  consistent with the present invention is shown. Stent  900  includes a base  910  and a connector  920 . Un deployed, connector  920  is a tightly wrapped coil of material. On deployment, connector  920  unwinds into a bulbous or volumous area sufficiently to anchor the stent  900 . Generally, connector  920  would expand to completely fill aneurysm space, but at a minimum the expansion should be sufficient to prevent connector  920  from pulling out of the aneurysm. As can be appreciated, stent  900  could be used to treat the aneurysm without packing material. But if packing material were used to treat the aneurysm, connector  920  would not need to expand as much.  
         [0034]    [0034]FIGS. 10A and 10B show another stent  1000  consistent with the present invention. FIG. 10A shows a front plan view of a stent  1000  that includes a base  1010  and expanded connectors  1020  and  1030 . While stent  1000  is shown with two orthogonal rings as connectors  1020  and  1030 , more rings could be used. Further the rings could be cross-linked or individual rings. FIG. 10B shows a side plan view of stent  1000  also with expanded connectors  1020  and  1030 . As can be seen, connectors  1020  and  1030 , which are shown in the deployed state, expand to form rings that act similar to the corkscrew anchor above. Also, while shown as rings any shape is possible, such as diamond, circular, square, triangular, elliptical, helical, or the like.  
         [0035]    While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention.