Patent Publication Number: US-2013238083-A1

Title: Systems and methods for aneurysm treatment and vessel occlusion

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of: 
     pending U.S. patent application Ser. No. 12/582,052, filed Oct. 20, 2009, which carries Applicants&#39; docket no. DUG-2, and is entitled SYSTEMS AND METHODS FOR ANEURYSM TREATMENT AND VESSEL OCCLUSION, which claims the benefit of: 
     U.S. Provisional Patent Application No. 61/106,670, filed Oct. 20, 2008, which carries Applicants&#39; docket no. DUG-2 PROV, and is entitled DEVICES AND METHODS FOR ANEURYSM TREATMENT; and 
     U.S. Provisional Patent Application No. 61/172,856, filed Apr. 27, 2009, which carries Applicants&#39; docket no. DUG-4 PROV, and is entitled DEVICES AND METHODS FOR ANEURYSM TREATMENT. 
     The above-identified documents are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The invention relates to endovascular medicine, and more particularly, to systems and methods for aneurysm treatment and selective vessel occlusion. 
       2 . The Relevant Technology 
     Cerebrovascular disease encompasses a broad spectrum of disorders, including intracranial aneurysms. Unruptured intracranial aneurysms have a prevalence of approximately 3.6 to 6% in the U.S. population and have an estimated annual rate of rupture between 10-28 per 100,000. Most individuals with aneurysms remain asymptomatic. Multiple risk factors for the development of intracranial aneurysms include: smoking, hypertension, positive family history and cocaine use. A number of inherited disorders have also been associated with the development of intracranial aneurysms. Ruptured intracranial aneurysms are the most common cause of non-traumatic subarachnoid hemorrhage (SAH). SAH secondary to aneurysm rupture is a potentially lethal event and carries a 50% morbidity-mortality rate. 
     An aneurysm is an abnormal localized dilation of a vessel. Aneurysms most frequently occur at sites of arterial bifurcation and are most commonly found in the brain. Pathologically, aneurysms have an absent or fragmented internal elastic membrane. Intracranial aneurysms are classified as saccular, fusiform, dissecting or false. Approximately 90% of intracranial aneurysms are saccular and are described by size, contour, orientation, location and neck size. Select unruptured and all ruptured intracranial aneurysms require either surgical or endovascular intervention. 
     Surgical intervention had long been the gold standard of care for the management of intracranial aneurysms and involves the placement of a clip across the aneurysm neck. A recent meta-analysis reviewing the risks of surgical repair found an overall mortality rate of 2.6 percent and a permanent morbidity rate of 10.9 percent. Endovascular treatment of intracranial aneurysms has developed over the last two decades. The procedure most commonly involves the insertion of a “coil” of wire into the aneurysm. The coil is delivered to the aneurysm through catheters, which are placed and guided through arteries. The Guglielmi Detachable Coil (GDC) pioneered the field of endovascular treatment of intracranial aneurysms and involved electrolytic detachable platinum coils that were placed directly into the fundus of the aneurysm via a microcatheter and detached from a stainless-steel micro-guidewire by an electrical current. Studies suggest that endovascular treatment may be associated with less procedural morbidity and mortality than conventional surgical techniques as well as reduced recovery time and earlier return to normal functioning. 
     Although endovascular techniques have created a paradigm shift in the management of intracranial aneurysms, the technique still has many limitations. This is particularly evident in the treatment of wide-necked, dissecting and fusiform aneurysms. Until recently, wide-necked aneurysms (defined as an aneurysm with a neck width &gt;4 mm and/or a fundus/neck ratio &lt;2) were not considered amenable to endovascular coiling for fear that a coil may prolapse into the parent vessel, leading to altered flow dynamics and stroke. More recently, expandable stents have been placed in the parent vessel—acting as a scaffold across the neck of the aneurysm, to prevent coil prolapse. For wide neck aneurysms, this has held promise in preventing coil migration. The introduction of the flexible intracranial stent (Neuroform; Boston Scientific) improved the management of these complex intracranial aneurysms, but was associated stent migration/misplacement and difficulties in coil delivery. In this system, the coils are inserted into the aneurysm dome via the fenestrations in the stent. The limitation with this design is that the fenestrations still allow blood to enter the aneurysm. Thus this strategy depends on the delivery of coils to occlude the dome. The introduction of the coils through the fenestrations in the stent can be associated with dislodgement/migration of the stent during the coiling. More recently, to avoid this problem, intracranial balloons have been used in conjunction with coils and stents. In this technique, the balloon is first inserted into the parent vessel, distal to the aneurysm. Once in place, the balloon is inflated, occluding distal blood flow. During this temporary occlusion, the coils are then inserted and are placed in the dome of the aneurysm. During this process, the balloon is intermittently inflated and deflated—in an attempt to prevent distal ischemia. Finally, once the coiling of the aneurysm is complete, a stent is placed across the neck of the aneurysm to prevent coil prolapse. The balloon is then deflated and distal blood flow resumed. 
     More recently, further advances have been made for the endovascular treatment of intracranial aneurysms using flow-diversion principles instead of space-occupying principles such as endovascular coiling. One of these devices, the JOSTENT (Abbott), is comprised of an expandable PTFE barrier between two stainless steel stents. Accordingly, it does not have fenestrations and has been used to extensively in cardiac endovascular procedures. This stent is placed in the parent vessel such that it directly occludes the neck of the aneurysm and prevents flow into the aneurysm. Unfortunately, this has had limited applications in the cranial vasculature, as its design is inflexible and difficult to position. In addition, its geometry poses a risk for occlusion of perforating vessels that may be in the vicinity of the aneurysm neck. Another flow-diversion device, the Pipeline Embolization Device (eV3), has been successful in decreasing blood flow into the aneurysm, while maintaining the patency of surrounding branch vessels. The Pipeline is a self-expanding cylindrical braided mesh construct that has decreased porosity size along the entire length of the stent which occludes the neck of the aneurysm. The cells of the mesh are sufficient to embolize the aneurysm while maintaining patency of the parent artery and minimizing disruption to flow into perforating vessels near the aneurysm. 
     The modern era of aneurysm treatment began with Hunterian ligation of the parent vessel. With increasing sophistication of surgical and endovascular management techniques, the indications for vessel occlusion for management of complex aneurysms are limited. A number of strategies have been devised for arterial occlusion including the Selverstone clamp, a device that allowed for gradual occlusion of the vessel. The rationale for gradual occlusion of the vessel was to promote the capacity for collateral circulation of the circle of Willis, in the hope of preventing post-occlusion cerebral infarction. This device could be reopened at the first sign of cerebral ischemia secondary to insufficient collateral circulation. A number of subsequent devices all incorporated an external mechanism that allowed the surgeon to gradually decrease the caliber of the vessel until ultimately achieving complete occlusion. In complex vascular disorders, deemed untreatable by both direct surgical or endovascular techniques, a test occlusion by balloon is performed by endovascular techniques. Unfortunately this does not provide a gradual occlusion of the vessel and does not allow for the gradual development of collateral circulation. At present, no endovascular technique allows for the gradual occlusion of a vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. 
         FIG. 1  is a stylized perspective side view of a representative wide-necked aneurysm of a parent blood vessel; 
         FIG. 2A  is a partial cross-sectional side view of the aneurysm of  FIG. 1  with a stent in the parent vessel and a barrier across the aneurysm neck; 
         FIG. 2B  is a side view of the stent and barrier of  FIG. 2A  with the barrier in a curved configuration; 
         FIG. 3A  is a top view of the barrier of  FIG. 2A ; 
         FIG. 3B  is a cross-sectional side view of the barrier of  FIG. 3A , taken along line B-B; 
         FIG. 4  is a partial cross-sectional side view of the aneurysm, stent and barrier of  FIG. 2A  and a vaso-occlusive coil in the aneurysm; 
         FIG. 5A  is a partial cross-sectional side view of the aneurysm, stent and barrier of  FIG. 2A  and a vaso-occlusive elliptical balloon in the aneurysm; 
         FIG. 5B  is a partial cross-sectional side view of the aneurysm, stent and barrier of  FIG. 2A  and a vaso-occlusive conical balloon in the aneurysm; 
         FIG. 6A  is a top view of a sleeve with a cutout window; 
         FIG. 6B  is a side view of the sleeve of  FIG. 6A ; 
         FIG. 6C  is a top view of a stent with a cutout window; 
         FIG. 7A  is a partial cross-sectional view of an aneurysm with the sleeve of  FIG. 6A  inside the stent of  FIG. 6C , the sleeve and stent juxtaposed to provide an open window and open stent cells, and a vaso-occlusive coil; 
         FIG. 7B  is a partial cross-sectional view of the aneurysm, sleeve, stent and coil of  FIG. 7A , with the sleeve rotated relative to the coil to provide a closed window and occluded stent cells; 
         FIG. 7C  is a cross-sectional view of the sleeve and stent of  FIG. 7A  taken at line C-C, showing an angle of the open window; 
         FIG. 8A  is a side view of a stent with fenestrations; 
         FIG. 8B  is a side view of a sleeve with fenestrations; 
         FIG. 8C  is a side view of a sleeve with fenestration zones; 
         FIG. 8D  is a side view of a sleeve with fine fenestrations; 
         FIG. 8E  is a side view of a sleeve with two zones of round fenestrations and one zone of vent-like fenestrations; 
         FIG. 8F  is a side view of a sleeve with two zones of round fenestrations and one zone of finer round fenestrations; 
         FIG. 9A  is a side view of the sleeve of  FIG. 8C  inside the stent of  FIG. 8A , the sleeve and stent juxtaposed to provide open stent cells in a central zone and occluded stent cells in two flanking zones; 
         FIG. 9B  is a side view of the sleeve and stent of  FIG. 9A , the sleeve and stent juxtaposed to provide occluded stent cells in the central zone and occluded stent cells in the two flanking zones; 
         FIG. 10A  is a partial cross-sectional view of the aneurysm, coil, sleeve and stent with cutout windows of  FIG. 7A , and a microcatheter depositing an expandable molly anchor barrier into the aneurysm; 
         FIG. 10B  is a partial cross-sectional view of the aneurysm, coil, sleeve, stent and molly anchor barrier of  FIG. 10A , with the barrier expanded across the neck of the aneurysm; 
         FIG. 10C  is a cross-sectional view of the molly anchor barrier of  FIG. 10B ; 
         FIG. 11  is a partial cross-sectional view of an aneurysm with a coil in the aneurysm and a sleeve inside a stent in the vessel adjacent the aneurysm, the stent having a barrier formed on the stent; 
         FIG. 12A  is a side view of the sleeve of  FIG. 8E ; 
         FIG. 12B  is a perspective cross-sectional view of the sleeve of  FIG. 12A , taken at line B-B; 
         FIG. 12C  is an end cross-sectional view of the sleeve of  FIG. 12A , taken at line B-B, showing inner flaps of the vents; 
         FIG. 13A  is a perspective view of a stent comprising a window having pivotable flaps which are selectively actuable to open or close; 
         FIG. 13B  is a cross-sectional view of the stent of  FIG. 17A  taken at line B-B, the stent in a compact configuration; 
         FIG. 13C  is a cross-sectional view of the stent of  FIG. 17A  taken at line B-B, the stent in an expanded configuration; 
         FIG. 14A  is a detail view of the window of  FIG. 17A , with the flaps in an open position; 
         FIG. 14B  is a detail view of the window of  FIG. 17A , with the flaps in a closed position; 
         FIG. 15A  is a side view of a intra-luminal occlusion device comprising a stent, a sheath and a drawstring; 
         FIG. 15B  is a cross-sectional side view of the intra-luminal occlusion device of  FIG. 15A , with a sheath orifice in an open configuration; 
         FIG. 15C  is a cross-sectional side view of the intra-luminal occlusion device of  FIG. 15A , with a sheath orifice in an partially open configuration; 
         FIG. 15D  is a cross-sectional side view of the intra-luminal occlusion device of  FIG. 15A , with a sheath orifice in a closed configuration; 
         FIG. 16  is a side view of an alternate embodiment of an intra-luminal occlusion device with a sheath orifice in a partially open configuration; 
         FIG. 17A  is a partial cross-sectional view of an aneurysm with two stents in the vessel adjacent the aneurysm, and a half-pipe connection mesh bridging the aneurysm and connecting the two stents; 
         FIG. 17B  is a partial cross-sectional view of an aneurysm with two stents in the vessel adjacent the aneurysm, and a cylindrical connection mesh bridging the aneurysm and connecting the two stents; and 
         FIG. 18  is a partial cross-sectional view of a basilar tip aneurysm, with two stents in adjacent branching vessels and a connection mesh bridging the aneurysm and connecting the two stents, and a third stent in a main vessel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to systems and methods for providing aneurysm treatment, and selective vessel occlusion. Those of skill in the art will recognize that the following description is merely illustrative of the principles of the invention, which may be applied in various ways to provide many different alternative embodiments. This description is made for the purpose of illustrating the general principles of this invention and is not meant to limit the inventive concepts in the appended claims. 
     Complex intracranial aneurysm treatment requires techniques for management of wide neck aneurysms, and for gradual occlusion of the parent vessel. Systems and methods disclosed herein provide a stent with an opening that could ultimately be open or closed, allowing the radiologist/surgeon to deploy coils or other various agents in a controlled and reliable manner. A number of these methods can incorporate an “open-closed window” technique. In at least one approach, the stent contains an opening, or aperture, that would allow the deployment of coils or other devices into the dome of the aneurysm (“open window”). Once occlusion of the aneurysm had been completed, the aperture would be closed—preventing dislodgement or prolapse of the coils (“closed window”). A mechanical means of controlling the aperture of a lumen within the body of a stent could be applied to all existing and future stents and could also be adapted to provide a means of gradual occlusion of a vessel. 
     In another approach, a stent comprises a plurality of apertures or cells, and an inner sleeve disposed within the stent similarly comprises a plurality of apertures or cells. By changing the juxtaposition of the sleeve relative to the stent by rotation and/or translation, allowing the stent cells to overlay the sleeve cells, the permeability of the stent can be varied. 
     Previously, wide neck aneurysms have been typically deemed “uncoilable” and instead required an open surgical approach. One approach disclosed herein utilizes a sleeve either inside or outside of the stent. The sleeve may have several wide openings in it as well as a closed (no openings) component. The sleeve may have a preconfigured curvature allowing it to bridge across the lumen of the vessel. To gain access to the aneurysm, the open segment of the sleeve may be positioned such that access to the neck of the aneurysm is provided. The opening in the sleeve may span across the lumen of the vessel, allowing for normal blood flow during the coiling of the aneurysm. The closed segment of sleeve may be positioned on the contralateral side of the vessel, thus leaving perforating vessels perfused. Once the coiling of the vessel is completed, the sleeve may then be retracted such that the “closed” segment is positioned at the neck of the aneurysm. By now closing access to the neck of the aneurysm, prolapse of coils or other agents may be prevented. This may also eliminate any further significant blood flow into the aneurysm. Alternatively, the closed segment of the sleeve may be positioned in such a manner as to occlude blood flow through the blood vessel during the coiling. Once coiling is complete, the sleeve could then be retracted to a “closed” position, occluding the opening (window) in the stent and preventing any further significant blood flow into the aneurysm. 
     Referring to  FIG. 1 , a stylized perspective view of a representative wide-necked aneurysm is shown. Parent vessel  2  defines a vessel lumen  4  having a substantially cylindrical lumen wall  6 . An aneurysm  8  protrudes from the lumen wall  6 , comprising an aneurysm sac  10  which joins the wall at an aneurysm neck  12 . A branching vessel  14  branches from the parent vessel near the aneurysm. 
     Referring to  FIG. 2A , a cutaway view of parent vessel  2  and aneurysm  8  is shown, with a stent  20  in the vessel lumen  4  and a barrier  30  implanted to extend across the aneurysm neck  12 , forming an aneurysm treatment system. The stent  20  may be a fenestrated stent known in the art, and comprises a first end  22 , a second end  24 , and a stent wall  26  which defines a stent lumen  28 . The stent wall comprises plurality of fenestrations, or cells  29 , allowing flexibility of the stent, and allowing blood flow through the stent wall. The stent may be made to have anti-thrombogenic properties on the inner surface and thrombogenic properties on the exterior surface. Barrier  30  includes a first, or outer side  32  which may be also be coated or treated with a thrombogenic treatment, and a second, or inner side  34  which may be coated or treated with an anti-thrombogenic treatment. In some embodiments, an opening  36  may communicate with the first and second sides  32 ,  34 . The opening  36  may engage with an instrument for implantation, deployment and/or expansion of the barrier. 
     The barrier  30  may serve as a shield or blanket to slow or prevent blood flow into the aneurysm, providing an environment for spontaneous thrombosis of the aneurysm and/or provide support at the aneurysm neck to prevent prolapse of coils or other intra-saccular aneurysm implants into the parent vessel. Barrier  30  may be delivered before, in tandem with, or after placement of the stent. The barrier  30  may be rolled, coiled up, folded, deflated, compressed, or otherwise retracted to form a compact configuration, and it may be deployed or expanded to form an expanded configuration. The barrier may be delivered to the aneurysm through the stent wall  26  in the compact configuration, then unrolled, uncoiled, unfolded, inflated, uncompressed or otherwise expanded to form the expanded configuration like that seen in  FIG. 2A . The barrier may extend substantially across the aneurysm neck, in which the barrier blocks the opening between the aneurysm and the vessel to minimize or entirely prevent bloodflow between the aneurysm and the vessel, yet does not touch the neck, in order to prevent rupture of the aneurysm. The barrier may also be delivered alongside the stent, passing between the stent wall  26  and the vessel lumen wall. A microcatheter may deliver the barrier to the aneurysm before delivery of the stent, or through or alongside the stent after delivery of the stent. In some embodiments, the barrier is formed as a patch on a portion of the stent wall  26 . 
       FIG. 2B  depicts the barrier  30  and the stent  20 , with the barrier in a curved configuration. This configuration may allow the barrier to more completely shield the aneurysm neck to prevent blood flow from the vessel into the aneurysm. 
       FIG. 3A  depicts a top view of barrier  30 , and  FIG. 3B  is an enlarged cross-sectional lateral view taken along section line B. Barrier  30  may be a single, solid member, or may have an interior space  38  formed between the first and second sides  32 ,  34 . When the barrier is expanded or inflated, a volume of the interior space may increase; when the barrier is retracted or deflated, the volume may decrease. The barrier may expand or contract laterally, increasing or decreasing in radius r relative to a longitudinal axis  39 , which may also be referred to as radial expansion. It may also expand or contract axially, increasing or decreasing in height h. In some embodiments, radial expansion of the barrier may be greater than axial expansion. Barrier  30  may be comprised of materials including nylon, polypropylene, polyester, polyurethane, polyvinyl chloride, Teflon, ePTFE, PTFE, polyethylene, polypropylene, silicone, PEEK, and/or hydrogel, among others. These materials may take the form of a fabric, or fiber mesh in which the fibers are woven, knitted, coiled, braided or otherwise intermeshed together. A mesh barrier may have an interior space formed between the outer strands of the mesh. In an alternative embodiment, the barrier may comprise beads, in which each individual bead is larger in diameter than the maximum width of a stent cell  29 , preventing passage of the beads through the stent cells. Such beads may comprise hydrogel, and swell to enlarge when deposited in the aneurysm sac and exposed to fluid. The barrier may be symmetrical axially and radially as shown in  FIGS. 3A and 3B , or it may be asymmetrical in any direction. 
     An intra-saccular vaso-occlusive member may be included in the aneurysm treatment system. Referring to  FIG. 4 , a vaso-occlusive member comprising a coil  40  is shown implanted in the aneurysm sac; the barrier  30  prevents the coil  40  from penetrating the stent  20  and/or escaping the aneurysm through the aneurysm neck  12 . The coil  40  may comprise one or a plurality of coil members, and may be a coil known in the art. Implantation of the coil may occur prior to, with, or after implantation of the barrier. A coil introduction instrument comprising a microcatheter carrying the coil may be advanced through the stent lumen  24 , through the stent wall  26  and through the barrier opening  36 , and the coil deposited from the microcatheter into the aneurysm sac  10 . Alternatively, the microcatheter may be advanced alongside the stent and through the aneurysm neck  12 , and the coil deposited into the aneurysm sac. The coil introduction instrument may further comprise a shield located proximal to the microcatheter tip, the shield positionable to bridge the aneurysm neck as the coil is introduced into the aneurysm, preventing migration of the coil out of the aneurysm sac. 
     In some embodiments, a vaso-occlusive member may comprise a gel and/or foam scaffold which is injected into the aneurysm under low pressure, after placement of a barrier in the aneurysm neck. A microcatheter tip is inserted through an opening such as barrier opening  36 , and the gel or foam is injected into the aneurysm sac. Following insertion, the material may solidify and bind together. 
     In another embodiment, the vaso-occlusive member may comprise a soft textile coil impregnated with a clotting agent. This type of coil may be implanted through the wall of a stent, but without a barrier. After implantation of the coil, blood is allowed to flow into the aneurysm through the stent, and the clotting agent on the coil is activated by the blood to bind the coil to itself, using blood as the binding agent. 
     Referring to  FIGS. 5A and 5B , a vaso-occlusive member comprising a balloon may be implanted in the aneurysm. A vaso-occlusive balloon may comprise an elastomeric sheath comprising silicone, polyurethane, or hydrogel, among other material. The balloon may comprise an elliptical shape as depicted, a round shape, a conical shape, or a ring or donut shape with a central opening, among others.  FIG. 5A  depicts a round balloon  50  comprising an elastomeric sheath  52 , while  5 B depicts a nosecone balloon  54  comprising an elastomeric sheath  54  with a plurality of zones. A nipple or other port may be included for balloon inflation and/or deflation. The elastomeric sheath may comprise a compliant material with a uniform level of compliance or elasticity. In other embodiments, the elastomeric sheath may comprise zones with varying levels of compliance or elasticity, such that the balloon inflates to a greater extent in some zones than in others. For example, the balloon may inflate to a greater extent radially than axially, in order to more effectively obscure the neck of the aneurysm. The balloon may also be pre-shaped to inflate to a specific predetermined shape, such as those previously listed. 
     It is appreciated that the vaso-occlusive balloon may be implanted with or without a barrier such as barrier  30 , and it may be implanted before, with, or after the barrier. The balloon may be implanted using the methods disclosed previously for implantation of a coil. A microcatheter may be actuated to implant the balloon into the aneurysm through or alongside the stent, and a microcatheter may also deliver fluid into the balloon to inflate the balloon. The barrier opening  36  may allow passage of the microcatheter to the balloon. Suitable fluids for inflation may include air, saline solution, hydrogel, silicone, polyvinyl acetate (PVA), and curable adhesives, among others. 
     Another approach to occluding an aneurysm comprises a first stent, and a second stent or sleeve which may be deployed inside or outside the stent. The stent and sleeve may be rotated and/or axially translated relative to one another to provide an open or closed window to the aneurysm, and to provide varying degrees of blood flow through the stent and sleeve walls.  FIGS. 6A and 6B  depict a sleeve  60  comprising a first end  62 , a second end  64 , and a stent wall  66  which defines a sleeve lumen  67 . The sleeve wall comprises plurality of fenestrations, or sleeve cells  69 , allowing flexibility of the sleeve, and allowing blood flow through the sleeve wall. A sleeve window  68  is located in the sleeve wall. Depicted in  FIG. 6C , stent  70  comprises a first end  72 , a second end  74 , and a stent wall  76  which defines a stent lumen  77 . The stent wall comprises plurality of fenestrations, or stent cells  79 , allowing flexibility of the stent, and allowing blood flow through the stent wall. A stent window  78  is located in the stent wall. As seen in  FIGS. 6A-6C , window  68  may be smaller than window  78 ; in other embodiments, window  68  may be larger than window  78 , or they may be the same size. When sleeve  60  is disposed within stent  70 , sleeve  60  and/or stent  70  may be rotated and/or translated relative to one another to allow windows  68 ,  78  to line up to allow passage of blood, vaso-occlusive members or other bodies through the windows. Similarly, the sleeve cells  69  and stent cells  79  may be partially or fully lined up to allow maximal blood flow through the sleeve and stent walls  66 ,  76 , or partially or completely occlude blood flow through the sleeve and stent walls. Sleeve  60  may also be disposed outside of stent  70 . The sleeve and stent windows  68 ,  78  may be rectangular as depicted in  FIGS. 6A-6C , or they may be round, oval, or any other shape. 
       FIGS. 7A and 7B  depict stent  70  and sleeve  60  placed in a vessel adjacent aneurysm  8 . In  FIG. 7A , sleeve  60  and stent  70  are juxtaposed so that window  68  and  78  are lined up, creating an unimpeded opening between the aneurysm  8  and the lumen of the sleeve. Coil  40 , or other intra-saccular materials as desired, may be implanted in the aneurysm when the sleeve and stent are in this “open” configuration.  FIG. 7B  depicts sleeve  60  and stent  70  in a “closed” configuration, in which sleeve  60  has been rotated so that sleeve window  68  is no longer lined up with stent window  78 . In the “closed” position, coil  40  cannot pass out through the windows, and blood flow may be impeded.  FIG. 7C  is an end cross-sectional view of the sleeve and stent in the “open” configuration of  FIG. 7A . 
     The window dimensions may vary in length and width. Preferably, the window widths may range from 10° to 180° of the circumference of the respective sleeve or stent. More preferably, the window width ranges from 30° to 60° of the circumference of the respective sleeve or stent. In an exemplary embodiment, the window width is 45° of the circumference of the respective sleeve or stent. In the embodiment depicted in  FIG. 7C , both stent  70  and sleeve  60  have a window width which is subtended by angle a of approximately 40°. 
     In another embodiment of the invention, blood flow to an aneurysm may be decreased or entirely occluded by a device comprising an outer stent and an inner stent or sleeve, placed in the vessel adjacent the aneurysm. The outer stent may have fenestrations or cells of regular size and distribution, while the inner sleeve may have fenestrations or cells of differing sizes which may be distributed regularly or within zones. When the inner sleeve is disposed in the outer stent and rotated and/or translated relative to the outer sleeve, the overlay of the outer stent relative to the inner sleeve can increase or decrease effective outer stent cell sizes to change the permeability of the stent wall to blood flow. Changing the effective outer stent cell size may increase, decrease or occlude flow to the aneurysm. 
     Referring to  FIGS. 8A through 8F , several embodiments of outer stent and inner sleeve configurations are shown.  FIG. 8A  depicts flexible stent  70 , comprising quadrilateral fenestrations  72 .  FIG. 8B  depicts sleeve  80 , comprising substantially round fenestrations  82 . When sleeve  80  is disposed in stent  70 , the sleeve fenestrations  82  may line up with the stent fenestrations  72  similar to  FIG. 7A , in which each sleeve fenestration is lined up with a stent fenestration to create relatively unimpeded openings. Sleeve  80  may be rotated relative to stent  70  so that the fenestrations no longer line up in an open fashion, similar to  FIG. 7B . In this configuration, blood flow would be impeded in comparison to the configuration in  FIG. 7A . 
       FIG. 8C  depicts sleeve  90 , which has sleeve fenestrations  92  distributed in three zones. Two first zones  94  have fenestrations distributed in circumferential rows, while in second zone  96 , the rows of fenestrations are offset from those in zones  94 . Zones  94  and  96  are circumferential; however it is appreciated that in other embodiments the zones could be arranged longitudinally along the length of the sleeve. 
       FIG. 8D  depicts sleeve  100  having fenestrations  102 . Sleeve fenestrations  102  are relatively smaller than those in the other sleeve embodiments. When sleeve  100  disposed in stent  70 , together they may create a device with relatively less blood flow permeability than that of the other embodiments depicted. 
       FIG. 8E  depicts a sleeve  110  having first zones  114  comprising round fenestrations  112 , and second zone  116  has slot-like or vertical vents  118 . Each vent comprises a flap which may be open when there is no blood or fluid flow through the lumen of the sleeve, and closed by fluid pressure when blood flows through the lumen. 
       FIG. 8F  depicts a sleeve  120  having two zones  124  with large fenestrations  122 , while zone  126  has relatively finer fenestrations  128 . 
     Any of the sleeves disclosed in  FIGS. 8B-8F  may be combined with stent  70  or another stent to form aneurysm treatment devices with varying permeability to fluids. As described, the sleeve and/or stent may be rotated and/or translated relative to one another to create open, partially open, or closed cells. Additionally, a stent may comprise any of the cell or fenestration configurations and distributions disclosed herein. Other methods of affecting cell size or opening can include fluid pressure, or using radio frequency (RF) or ultrasonic energy to change cell sizes in specifically zoned portions of a stent and/or sleeve in situ. For example, an ultrasonic energy delivery device may comprise a guidewire through which ultrasound is passed. In another embodiment, a stent and sleeve combination may have an integrally formed zone of compliance that is activated by axially stretching or compressing the stent and sleeve. In other embodiments, the stent and sleeve may be coupled or fused together during manufacture. The stents and sleeves disclosed herein may be implanted with or without a vaso-occlusive member such as a coil or balloon, and with or without a barrier member. 
     Referring to  FIGS. 9A and 9B , occlusion device  130  comprises outer stent  70  and inner sleeve  90 . Three zones are distributed circumferentially about the device; two zones  134  adjacent first and second ends of the device, and zone  136  substantially centrally located. The occlusion device  130  comprises an open configuration as seen in  FIG. 9A , in which the sleeve  90  and stent  70  are juxtaposed to form open fenestrations  135  in the central zone  136 . End zones  134  comprise closed fenestrations  137 . In  FIG. 9B  the sleeve  90  has been rotated relative to the stent  70  to create a closed configuration, in which central zone comprises closed fenestrations  137 . When implanted in a vessel so that an aneurysm is adjacent central zone  136 , blood flow to the aneurysm may be allowed when the device is in the open configuration depicted in  FIG. 9A , and blood flow may be occluded when the device is in the closed configuration depicted in  FIG. 9B . Of course, the sleeve  90  may be partially rotated relative to the stent  70  to cause partial occlusion. Also, if desired, a coil  40  or other vaso-occlusive member may be implanted in the aneurysm sac before or after placement of occlusion device  130 . 
     An aneurysm treatment comprising a barrier and a vaso-occlusive device may be implanted in conjunction with an outer stent and inner sleeve device such as those disclosed in  FIGS. 6-9 . Referring to  FIG. 10A , a longitudinal cross-section of a vessel  2  with an aneurysm  8  is shown. Outer stent  70  and inner sleeve  60  have been introduced into the vessel and juxtaposed so that windows  68 ,  78  are aligned to create an opening into the aneurysm. A microcatheter  142  is inserted into the inner sleeve lumen and a microcatheter tip  142  protrudes through the open windows  68 ,  78 . A coil  40  has been introduced into the aneurysm, and an expandable barrier  150  comprising a molly anchor is projecting out of the microcatheter tip. In  FIG. 10B , the expandable barrier  150  has been deposited into the aneurysm neck and is expanded. Inner sleeve  60  has been translated relative to outer stent  70  to close the opening into the aneurysm. In  FIG. 10C , a cross-sectional view of the expandable barrier  150  shows a central stem  152 , an upper or outer side  154 , and a lower or inner side  156 . Outer side  154  is coupled to stem  152  and stem  152  is slidable relative to inner side  156 . Thus, expandable barrier  150  can collapse and deploy like an umbrella. In  FIG. 10A , expandable barrier  150  is in a retracted or compact configuration, and in an expanded configuration in  FIG. 10B . In some embodiments, coil  40  may be coupled to expandable barrier  150  to be deployed with the barrier; or they may be implanted separately. In another embodiment, the molly anchor barrier may be implanted without a coil. 
     The molly anchor type barrier may comprise wire including Nitinol, wire mesh, an elastomeric sheath, fabric, or other materials previously listed. In addition, the molly anchor barrier may comprise hydrogel, so that it enlarges in size once implanted and exposed to fluid. In other embodiments, a coil may be formed integrally with, or connected to, a mesh or fabric skirt. Following insertion of the coil into the aneurysm, the attached skirt is deposited into the aneurysm neck and unrolls or unfolds to form a barrier to occlude the aneurysm neck, and prevent escape or migration of the coil into the vessel. 
     Referring to  FIG. 11 , an alternative embodiment of an occlusion device comprises an inner sleeve, a coil, and a barrier formed on an outer stent and implanted into a vessel to occlude blood flow into an aneurysm. Stent  160  comprises a flexible, expandable stent with a barrier patch  162  formed on a portion of the stent wall. Stent  160  may be placed in the vessel with inner sleeve  60  positioned in the stent lumen. The sleeve  60  and stent  160  may be juxtaposed relative to one another so that the patch  162  is not occluding the aneurysm neck, and coil  40  is deposited by a microcatheter through the open cells of sleeve  60  and stent  160 . After deposition of the coil into the aneurysm, stent  160  may be rotated relative to the coil until the patch  162  covers the aneurysm neck. Alternatively, the coil may be inserted along the outer surface of the stent; or, the stent may be installed after deposition of the coil in the aneurysm sac. The patch  162  may be entirely occlusive to blood flow, or have a greater degree of permeability. The patch  162  may comprise materials including nylon, polypropylene, polyester, polyurethane, polyvinyl chloride, Teflon, ePTFE, PTFE, polyethylene, polypropylene, silicone, PEEK, and/or hydrogel, among others. The patch may be made to have anti-thrombogenic properties on the inner surface and thrombogenic properties on the exterior surface. In an alternative embodiment, stent  160  having a barrier patch  162 , and a coil or other intra-saccular device may be deployed without inner sleeve  60 . 
       FIGS. 12A-12C  shows sleeve  110  in greater detail. Sleeve  110  comprises at least one zone  116  which has a plurality of slot-like fenestrations  118  arrayed transverse to the longitudinal axis of the sleeve. Adjacent each fenestration  118  on an inner side  117  of the sleeve wall is a flap  119 . When no pressure is applied through the lumen of the sleeve, the flaps  119  project radially inward, so that the vent-like fenestrations  118  are open. When fluid pressure is applied through the lumen, the pressure closes the flaps  119  so that they are substantially parallel to the inner side of the sleeve, covering and closing the fenestrations  118 . If a sleeve  110  is placed in a vessel so that second zone  116  is adjacent an aneurysm neck and blood is allowed to flow through the sleeve, the flaps  119  will be held closed by the blood flow, preventing flow into the aneurysm. If the second zone  116  overlaps any branching vessels, perpendicular flow should open the flaps to minimize disruption of flow to those vessels. The round fenestrations  112  in zones  114  may also allow blood flow to adjacent branching vessels in those zones. The flaps  119  may comprise a polyurethane film or equivalent. Sleeve  110  may be used by itself, formed into a stent such as stent  70 , or used with a stent such as stent  70 . Zone  116  may be circumferential as in  FIGS. 12A-12C , or may occupy a round, rectangular or other shaped portion of the sleeve. 
       FIGS. 13A-C  and  14 A-B illustrate an embodiment of a flexible, expandable stent comprising a window portion which may be selectively actuated to partially or totally occlude blood flow through the window portion. Stent  260  comprises a first end  262 , a second end  264 , and a stent wall  266  which defines a lumen  268 . A portion of the stent wall comprises a window portion  270  defined by a first end  272 , a second end  274 , and first  276  and second  278  sides. As the stent is flexible and expandable, the window is expandable from a compact configuration as seen in  FIG. 13B  to an expanded configuration as seen in  FIGS. 13A and 13C . In the compact configuration, the first and second sides are relatively close together and may touch or overlap, while in the expanded configuration they are spaced apart from one another. Extending across the window from the first side  276  to the second side  278  are a plurality of flaps  280  interposed with a plurality of vent openings  282 . Each flap  280  may comprise a first flap segment  284  and a second flap segment  286 , coupled together by a hinge or pivot  288 . In other embodiments, each flap may comprise a unitary piece, similar to flap  119  in  FIG. 12B . Because flaps  280  comprise a pivot, the first and second flap segments may pivot relative to one another about the pivot to increase or decrease the width of the window portion. 
       FIGS. 14A and 14B  illustrate the window portion in more detail. Referring to  FIG. 14A , in an open window configuration, the flaps are substantially orthogonal to the stent wall seen in  FIG. 17C ). Each flap segment  288  has a first edge  290  and a second edge  292 , which may define a top and bottom of the flap. An actuating mechanism comprising a tether  294  may be connected to each flap segment  284 ,  286 . The tethers may be collectively actuated to pivot the flap segments about their first edges, moving the second edges along the direction of the arrows, to transform the window from the open window configuration seen in  FIG. 14A  and  FIG. 13C , to a closed window configuration seen in  FIG. 14B , and vice versa. In the closed window configuration, the flaps have been pivoted approximately 90° so that the first edge of one flap is adjacent to or overlies the first edge of the immediately adjacent flap, effectively closing the interposing vent  282 . The tethers may be connected to one another such that actuating a single tether or actuating mechanism pivots all the flaps, similar to opening and closing the slats on a venetian blind by pulling a single cord, or collapsing a row of standing dominoes by touching one domino. 
     Referring again to  FIG. 13A , stent  260  may be implanted in a vessel adjacent an aneurysm, with window  270  adjacent the aneurysm neck. Window  270  may be opened to allow introduction of a coil or other vaso-occlusive device into the aneurysm, then closed, to prevent migration of the coil and prevent blood flow into the aneurysm. The window  270  may further comprise a locking mechanism or fastening that retains the window in the closed configuration. The window may be sized and shaped to occupy only the portion of the stent wall that is adjacent the aneurysm neck, and the remainder of the stent wall may allow unimpeded blood flow. Thus, any branching vessels near the aneurysm will not be occluded when the window is closed. 
     Devices for intra-luminal occlusion of blood flow are illustrated in  FIGS. 15A-15D  and  16 . Flow occlusion device  180  comprises a stent portion  182 , expandable occlusion sheath  184 , and an actuating portion which comprises a cable or drawstring  186 . Stent portion  182  may comprise a flexible, expandable stent, having a first end  188 , a second end  190  and a stent wall  192  defining a stent lumen  194 . Attached to the first end  188  is the expandable occlusion sheath  184 . Sheath  184  may comprise a tubular portion of flexible, compliant material which may comprise nylon, polyester, polyurethane, polyvinyl chloride, Teflon, ePTFE, PTFE, polyethylene, polypropylene, silicone, PEEK, and/or hydrogel, among others. The sheath may comprise mesh in which fibers are knitted, woven, braided, or otherwise intermeshed together. The sheath  184  comprises a first end  196 , a second end  198 , and a sheath lumen  200  defined by a sheath wall  202 . A sheath orifice  204  is defined by the second end  198 . The first end  196  of the sheath is attached to the first end  188  of the stent, and in the open configuration illustrated in  FIG. 15B , the sheath lines a portion of the stent lumen  194  adjacent the first end  188  of the stent, with the second end  198  of the sheath oriented toward the second end  190  of the stent  182 . The second end  198  of the sheath slidingly engages the drawstring  186 , which extends through the stent lumen  194 , such that a first end  187  of the drawstring  186  lies outside the second end  190  of the stent  182 . 
     As the drawstring first end  187  is pulled axially relative to the stent, the second end  198  of the sheath is drawn closed, gradually closing the sheath orifice  204 . The sheath orifice  204  may be substantially circular in shape; as the second end  198  of the sheath is drawn closed, the diameter of the sheath orifice decreases. 
     To effect partial or complete occlusion of a blood vessel, flow occlusion device  180  may be implanted in the vessel at a desired location. As long as the sheath orifice remains open, as in  FIG. 15B , blood may flow freely through the vessel. Partial occlusion of the vessel may be accomplished by pulling the drawstring  186  to draw the sheath second end  198  partially closed, thus decreasing the size of the sheath orifice  204 , as seen in  FIG. 15C . If complete occlusion of the vessel is desired, drawstring  186  may be pulled to drawn the sheath second end entirely closed, thus closing the sheath orifice  204 . When the sheath orifice  204  is partially or completely closed, flow pressure may cause the sheath may inflate or swell like a fluid filled parachute or balloon, as seen in  FIG. 15D . The flow occlusion device  180  may also be self-opening via a self-expanding ring in the sheath second end  198 , which may be comprised of Nitinol, stainless steel, or any other previously mentioned materials, such that the sheath orifice  204  is increased in size in response to a relaxation of tension on the drawstring  186 . It is anticipated that the drawstring  186  would extend through the proximal vasculature and out of the body through a vascular port to a tie-off location or dial. This functionality allows the clinician to apply tension or remove tension over a period of time to adjustably control flow through the flow occlusion device  180  and perhaps allow collateral circulation to take develop in response to the vessel occlusion. 
     In an alternate embodiment of a flow occlusion device, the sheath  184  and the drawstring  186  are not be positioned to extend back through the stent lumen  194  toward the stent second end  190 , but instead extend axially away from the first end  188  of the stent in the opposite direction. See  FIG. 16 , which illustrates flow occlusion device  210  in a mostly closed configuration. 
     In another alternate embodiment of a flow occlusion device, the occlusion sheath may be replaced with a plurality of sheets, membranous scales or plate-like members, connected to an actuating member. The actuation member may be actuated to close the plate-like members around the orifice, functioning similar to the iris of a camera lens to gradually close the orifice, occluding blood flow. 
     Referring to  FIGS. 17-18 , devices for aneurysm treatment comprising stent portions coupled with connection mesh portions are shown. In  FIG. 17A , aneurysm treatment device  220  comprises a first stent segment  222  having a first end  224  and second end  226 , second stent segment  228  having a first end  230  and second end  232 , and connection mesh  234  having a first mesh end  236  and a second mesh end  238 . The connection mesh  234  is coupled to the first end  224  of the first stent segment  222 , and the second end  232  of the second stent segment  228 . The connection mesh is sized and shaped to form a half-pipe or half-cylinder between the two substantially cylindrical stent segments; and sized to completely bridge the neck of wide-necked aneurysm  8 , the cutaway portion of which is indicated by a dashed line. The connection mesh is shown as attached to the stent segments at their ends; however in other embodiments the connection mesh could overlap portions of one or both stent segments. A coil  40  or other vaso-occlusive member may be introduced into the aneurysm prior to or after placement of the device  220 , or the device may be used alone. 
     The connection mesh may comprise a portion of woven, knitted, braided, or otherwise intermeshed fibers. The fibers may comprise nylon, Nitinol, Dacron, polyester, polyurethane, polyvinyl chloride, Teflon, ePTFE, PTFE, polyethylene, polypropylene, silicone, PEEK, and/or hydrogel, among others. As seen in  FIG. 17A , the mesh may form a half-cylinder of 180°, or it may subtend an angle ranging from 30° to a full cylinder of 360°, as shown in  FIG. 17B  illustrating an aneurysm treatment device  240  comprising connection mesh  242 . 
     Referring to  FIG. 18 , an aneurysm treatment device  250  may be placed to bridge the neck of a Y-junction vascular aneurysm, such as a basilar tip aneurysm  16 . Device  250  comprises a first stent segment  252  and second stent segment  254 , connected by connection mesh  256 . Connection mesh  256  may be sized and shaped as a half-pipe or other partial cylinder, to prevent blood flow from entering the aneurysm and deflect blood flow through stent segments  252  and  254 , as illustrated by arrows in  FIG. 18 . Optionally, a third stent segment  258  may be placed in the main vessel to reinforce it or encourage flow to divert into stent segments  252  and  254  and away from aneurysm  16 . A baffle may also be formed into the connection mesh  256  to further divert blood flow into the branching vessels and away from the aneurysm  16 . 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, above are described various alternative examples of systems for providing aneurysm treatment or vessel occlusion. It is appreciated that various features of the above-described examples can be mixed and matched to form a variety of other alternatives. For example, a barrier member or stent may be implanted with or without a vaso-occlusive coil or balloon. Variations in fenestration or cell opening sizes, shapes and distribution may occur on inner sleeves and/or outer stents. Sleeves and stents can be juxtaposed in positional relationship or integrated into one component. As such, the described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.