US20170172581A1 - Aneursym occlusion system and method - Google Patents

Abstract

An aneurysm occlusion system includes a device positionable within a cerebral blood vessel covering a neck of an aneurysm on the blood vessel. The device includes an expandable tubular element having a lumen surrounded by a sidewall including a plurality of gaps. When expanded, the tubular element includes longitudinal standards arrayed helically in a proximal to distal direction. The standards support struts and the gaps are defined between adjacent struts and are sufficiently large to permit delivery of embolic coils or other embolic materials therethrough.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a divisional of U.S. patent application Ser. No. 13/906,714 (Attorney Docket No. 41507-714.201), filed May 31, 2013, now U.S. Pat. No. ______, which claims priority to U.S. Provisional Application No. 61/655,116 (Attorney Docket No. 41507-714.101), filed Jun. 4, 2012; U.S. patent application Ser. No. 13/906,714 (Attorney Docket No. 41507-714.201), filed May 31, 2013, now U.S. Pat. No. ______, is a continuation-in-part of U.S. patent application Ser. No. 13/312,816 (Attorney Docket No. 41507-713.201), filed Dec. 6, 2011; and is also a continuation-in-part of U.S. patent application Ser. No. 11/784,236 (Attorney Docket No. 41507-705.201), filed Apr. 6, 2007, which claims priority to U.S. Provisional Application Serial No. 60/790,160 (Attorney Docket No. 41507-705.101), filed Apr. 7, 2006, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates generally to the fields of systems and methods for treatment of aneurysm, including implanting one or more intravascular devices for occlusion of the aneurysm.
• An aneurysm is an abnormal ballooning of a region of a blood vessel wall due to weakening of the wall tissue. While aneurysms can occur in any artery of the body, a large percentage of aneurysm are found in the cerebral blood vessels. If left untreated, such aneurysms can rupture, leading to life threatening hemorrhaging in the brain which can result in death or severe deficit.
• Aneurysms that do not rupture can form blood clots which can break away from the aneurysm potentially causing a stroke. In some patients, aneurysm can put pressure on nerves or brain tissue, causing pain, abnormal sensations, and/or seizures.
• One current practice for treatment of an aneurysm includes surgical placement of an aneurysm clip across the aneurysm to prevent blood flow into the aneurysm. Naturally, this procedure requires highly invasive brain surgery and thus carries many risks.
• In a less invasive catheter-based technique for aneurysm treatment, filler material is carried through the vasculature to the site of the aneurysm and used to pack the aneurysm. Materials used for this purpose include platinum coils and cellulose acetate polymer to fill the aneurysm sac. While these techniques have had some success, questions remain concerning their long-term effectiveness, ease of use, as well as their potential for rupturing the aneurysm or triggering clot formation. In addition, there is some risk of post procedure migration of embolic material from the aneurysm into the parent blood vessel.
• According to another prior art aneurysm treatment, a mesh or braided stent-like device is positioned within a blood vessel such that it bridges the aneurysm, blocking flow of blood into the aneurysm. A problem encountered with devices of this type is that the sidewalls of the devices not only occlude blood flow into the aneurysm, but they will also block flow between the blood vessel and any side branch vessels that the stent happens to cover. SeeFIG. 1A, which shows a blood vessel V, aneurysm A, and side branch vessel B. In some prior art modifications to the stent-type devices, the devices include sidewalls that are not occlusive around the full circumference of the device. In implanting these devices, the physician must make certain that the occlusive portion of the device's circumference covers the aneurysm and not any of the side branch vessels.
• Returning to the aneurysm coil embolization solution mentioned above, a typical procedure is illustrated inFIGS. 2A-2D. A typical occlusion coil is a wire coil having an elongate primary shape with windings coiled around a longitudinal axis. It is constrained in an elongate configuration or primary shape within the catheter for delivery through the interior of the catheter. The catheter is introduced into the femoral artery and navigated through the vascular system under fluoroscopic visualization. The catheter distal end is positioned at the site of an aneurysm within the vasculature of the brain. (SeeFIG. 2A, illustrating catheter distal end D as it is being positioned at the site of aneurysm A.)
• With proper positioning of catheter distal end D confirmed, the coil is passed from the catheter into the aneurysm. The coil reverts to a three dimensional configuration after release from the distal end of the catheter into the interior of the aneurysm. Once released from the catheter, the coil assumes a secondary shape selected to optimize filling of the aneurysm cavity, and the catheter may be withdrawn from the vessel. (SeeFIGS. 2B-2C, illustrating the release of coil C into aneurysm A.) Multiple coils may be introduced into a single aneurysm cavity for optimal filling of the cavity. The deployed coils serve to block blood flow into the aneurysm and reinforce the aneurysm against rupture. The implants are intended to embolize the blood inside the aneurysm in order to diminish additional blood flow into the aneurysm. Eventually the embolization completely closes the aneurysm to further flow of blood into the aneurysm. For a more detailed description of embolic coils and related methods, see commonly owned U.S. patent application Ser. No. 12/498,752 and Ser. No. 12/695,035.
• In some cases, there is a significant risk of migration of the coils or other implants out of the aneurysm and into the parent vessel after delivery and deployment (or release or detachment) of the coils. This is especially a risk in the case of a “wide neck” aneurysm. (SeeFIG. 2D). Migration of a coil or coils into the circulatory system is undesirable and can lead to occlusion of the parent vessel, other vessels, as well as lead to other unintended effects.
• In such cases, it may be desirable to “bridge” the neck of the aneurysm with a device prior to the delivery of embolic implants. Such a bridge device may be a generally tubular structure that is positionable via catheter within the parent vessel, covering the neck of the aneurysm. Positioning of such a device is typically performed with the assistance of a guidewire and fluoroscopic visualization. The generally tubular aneurysm bridge is deployed across the neck of the aneurysm and allowed to expand into contact with the vessel walls. Embolic coils are then delivered into the aneurysm through voids in the “walls” of the tubular bridge.
• Shortcomings of prior art attempts to bridge the neck of an aneurysm prior to embolic coil delivery include difficulties with tracking and deployment of the device, problems resheathing and repositioning the device, entanglement between the coil delivery catheter and the bridge device, and problems with portions of the device “bulging” into the aneurysm. Therefore, there remains a need for smooth, kink-free tracking, deployment, repositioning, and reliable, uniform deployment. There also remains a need for a sufficiently flexible device having adequate column strength.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 schematically illustrates an aneurysm in a blood vessel and the corresponding blood flow.
• FIG. 2A-2D illustrate some of the steps of a method of implanting one or more embolic coils into an aneurysm in a blood vessel.
• FIGS. 3A-3E illustrate some of the steps of a method of implanting a device to bridge the neck of an aneurysm and then implanting one or more embolic coils into the aneurysm.
• FIG. 4A-4G illustrate some of the steps of an alternative method of implanting a device to bridge the neck of an aneurysm and then implanting one or more embolic coils into the aneurysm.
• FIG. 5 is a perspective view of a finished device according to the invention, in a deployed configuration that results when the device is not placed in a vessel prior to deployment, hereinafter referred to as a “deployed in air”.
• FIG. 6 illustrates a side view of a device according to the invention deployed within a curved, transparent model vessel.
• FIG. 7 illustrates a truncated side elevational view of a device according to the invention in a deployed in air configuration.
• FIGS. 7A-7C are cross-sectional end views of the embodiment ofFIG. 7 taken along section lines A, B, and C.
• FIG. 8 is a perspective proximal end view of a finished device according to the invention in a deployed in air configuration.
• FIG. 9 is a plan view of a cut pattern for manufacture of a device according to the invention. Although devices according to the invention are preferably cut from tubular structures, twisted and shape set,FIG. 8 illustrates the cut tube as though it were longitudinally cut and flattened into a sheet before twisting, so that the pattern features may be more easily viewed.
• FIG. 10 is a plan view of a cut pattern of an alternative embodiment according to the invention. Although the bridge devices are preferably tubular structures, cut from a tube, twisted and shape set,FIG. 9 illustrates the device as though it were longitudinally cut and flattened into a sheet before it is twisted, so that its features may be more easily viewed.
• FIG. 11 is a truncated plan view of an embodiment according to the invention. Although the bridge devices are preferably tubular structures,FIG. 11 illustrates the device as though, after shape setting to include a right hand twist, it were longitudinally cut and unrolled so that its features are more easily viewed.
• FIGS. 11A-11B are enlarged views of Details A and B ofFIG. 10.
• FIG. 12 is a side elevation, partial cross sectional view of the distal end of a pusher catheter according to the invention, shown within a vessel and with the proximal end an aneurysm bridge device according to the invention mounted thereon.
• FIG. 13 is a perspective view of a pusher tip according to the invention.
• FIG. 14 is a perspective view of an alternative embodiment of the pusher tip ofFIG. 11.
DETAILED DESCRIPTION OF THE DRAWINGS
• Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The aneurysm occlusion system disclosed herein boasts a variety of inventive features and components that warrant patent protection, both individually and in combination.
• InFIG. 3A, a system for bridging the neck of an aneurysm before delivering embolics to the aneurysm is illustrated during a step of a method according to the invention. (An alternative exemplary method is discussed below in relation to a description ofFIGS. 4A-4G.)FIG. 3A illustrates a system after the step of positioning the system in a vessel V having aneurysm A. The aneurysm bridge device and accompanying delivery system includeaneurysm bridge device1,sheath2 and pusher5. A guide wire (not pictured) may also be utilized in the step of positioning the system in a vessel. Aneurysm bridge device is a generally tubular device capable of being retained in a reduced profile delivery configuration. Theaneurysm bridge device1 is proportioned to be implanted within the cerebral vasculature including, but not limited to, the Internal Carotid Artery, External Carotid Artery, Vertebral Artery, Basilar Artery, Middle Cerebral Artery, Anterior Cerebral Artery, and the Posterior Cerebral Artery.
• Generally speaking,aneurysm bridge device1 is a tubular device havingcentral lumen6. It is retained in a reduced profile delivery configuration bysheath2, and it is capable of expanding into contact with the vessel walls when released or deployed to a larger diameter configuration.Preferred devices1 are expandable to an outer diameter in the range of 2.0 mm-6.0 mm. The user may be provided with a set of multiple aneurysm bridge devices of different diameters and different lengths so that the device with the most appropriate dimensions may be chosen for the procedure.
• Suitable materials fordevice1 include shape memory materials including superelastic Nitinol or shape memory polymers, or other materials such as stainless steel, composite materials, or combinations of metals and polymeric materials. In a preferred embodiment, theaneurysm bridge device1 may be formed by laser cutting features into a length of superelastic Nitinol tubing, then chemically processing and shape-setting the material one or more time using methods known to those skilled in the art. The device may then be chilled to below its shape memory transition temperature and loaded onto pusher5 and retained bysheath2.
• In the example of a method according to the invention illustrated beginning inFIG. 3A,proximal end3 ofaneurysm bridge device1 is disposed upon the distal end4 of pusher5 while being retained bysheath2.Sheath2 is an elongate tubular catheter preferably formed of a polymeric material such as Pebax nylon, urethane, PTFE, Polyimide, metals such as Stainless Steel, Platinum, etc., or other suitable material. A central lumen extends the length ofsheath2. The sheath is proportioned for passage through cerebral vasculature, and may have an outer diameter in the range of 1 mm-3 mm.
• Pusher5 is an elongate tubular member having optional lumen7. The pusher may be formed of suitable polymers, metals, and/or composite materials. Distal end or tip4 of pusher5, which is described in greater detail below in a description ofFIGS. 11-14, includesapertures8. When loaded onto distal tip4,device1 is threaded over pusher5, and positioned so thatbumps9 of itsproximal end3 are aligned with, or inserted into,apertures8.Bumps9 may alternatively be projections, tabs, posts, clips, or any structures, preferably male, that are suitable for engagingapertures8. Similarly,apertures8 may alternatively be pockets, holes, hollows, grooves, or any structures, preferably female, for receivingbumps9.Sheath2 retainsbumps9 in engagement withapertures8 as it retainsaneurysm bridge device1 in a reduced profile configuration.Device1 remains in the reduced profile configuration during tracking of the device under fluoroscopic visualization to a treatment site within the vasculature of a subject.
• After positioninganeurysm bridge1 across the opening of aneurysm A, the device is then deployed and either temporarily or permanently implanted in the vessel. As illustrated beginning withFIGS. 3B, in order to deployaneurysm bridge1,sheath2 is withdrawn proximally to permit thedevice1 to expand to its unconstrained configuration into contact with the inner walls of the parent vessel V. Whensheath2 is completely withdrawn from the length ofbridge device1,device1 expands to a deployed diameter, as illustrated inFIG. 3C. Also, whensheath2 is withdrawn from along the length ofdevice1, bumps9 are no longer retained inapertures8. Pusher5 may then be withdrawn from the vessel V. Alternatively, pusher5 may be left positioned in vessel V, and central lumen7 may be utilized as a conduit or passage in a subsequent step. Further, if the user wishes to repositiondevice1,sheath2 can be advanced distally in order to resheathdevice1. The steps of positioning and deployingdevice1 described above can then be repeated.
• Voids in the walls of thetubular device1 permit the catheter-based delivery of embolic coils through the walls and into the aneurysm. (Alternatively, embolic coils may be implanted according to a method in which the coils are not delivered through the voids in the wall ofdevice1, as described in greater detail below.) As illustrated inFIG. 3D, delivery catheter D may be positioned within vessel V (and/or alternatively within pusher lumen7). Embolics including one or more embolic coils may then be delivered to the aneurysm, in much the same manner as described above in relation toFIGS. 2A-2C, except that they are delivered through the voids in the “walls” of thebridge1. The position of thedevice1 across the neck of the aneurysm prevents the unintended escape of embolic materials out of the aneurysm and into the parent vessel following the conclusion of the procedure (SeeFIG. 3E). The device remains in place in the parent vessel across the aneurysm neck during the delivery of coils, thereafter, and if desired, permanently.
• Turning now to an alternative method according to the invention,FIGS. 4A-4G illustrate exemplary steps according to the alternative method. In the steps illustrated inFIGS. 4A-4G, theaneurysm bridge1 described above in relation toFIGS. 3A-3E is again utilized, but according to a somewhat different method than that described in the foregoing paragraphs.FIG. 4A illustrates an early step according to the invention following the introduction of delivery catheter D into a vessel V having aneurysm A. One or more embolic coils, in the elongate configuration, is constrained by and carried within delivery catheter D. The distal end of delivery catheter D is positioned proximate aneurysm A.
• Following positioning of delivery catheter D proximate aneurysm A, theaneurysm bridge device1 and accompanying delivery system are introduced into the vessel V and positioned proximate aneurysm A, generally as illustrated inFIG. 4B. In addition toaneurysm bridge device1, the delivery system includessheath2 that was illustrated and discussed above.Sheath2 retainsaneurysm bridge device1 in a reduced profiled configuration.Device1 is capable of expanding into contact with the vessel walls, or released or deployed to a larger diameter configuration, whensheath2 is withdrawn.
• There are many similarities between the delivery system illustrated inFIG. 3B andFIG. 4B. However, the system illustrated inFIG. 4B includes alternative pusher14. Pusher14 may be formed of suitable polymers, metals, and/or composite materials. Pusher14 may include any of the materials and dimensions of pusher5 described above, but pusher14 does not include a central lumen. A guide wire (not pictured) may also be utilized in the step of positioning the system in a vessel.
• Prior to introduction into vessel V, theproximal end3 ofaneurysm bridge device1 is disposed upon the distal end of pusher14. Exemplary distal tips of pusher14 are described in greater detail below in a description ofFIGS. 11-14. Distal tip4 again includesapertures8. When loaded onto distal tip4,device1 is threaded over pusher14, and positioned so thatbumps9 of itsproximal end3 are aligned with, or inserted into,apertures8.Bumps9 may alternatively be projections, tabs, posts, clips, or any structures, preferably male, that are suitable for engagingapertures8. Similarly,apertures8 may alternatively be pockets, holes, hollows, grooves, or any structures, preferably female, for receivingbumps9.Sheath2 retainsbumps9 in engagement withapertures8 as it retainsaneurysm bridge device1 in a reduced profile configuration.Device1 remains in the reduced profile configuration during tracking of the device under fluoroscopic visualization to a treatment site within the vasculature of a subject.
• After positioninganeurysm bridge1 across the opening of aneurysm A, and proximate the distal end of delivery catheter D, the device is then deployed. As illustrated beginning withFIGS. 4C, in order to deployaneurysm bridge1,sheath2 is withdrawn proximally to permit thedevice1 to expand to its unconstrained configuration into contact with the inner walls of the parent vessel V. Whensheath2 is completely withdrawn from the length ofbridge device1,device1 expands to a deployed diameter, as illustrated inFIG. 4D. If the user wishes to repositiondevice1,sheath2 can be advanced distally in order to resheathdevice1. The steps of positioning and deployingdevice1 described above can then be repeated. Pusher5 may then be either withdrawn from the vessel V or may be left positioned in vessel V. As illustrated inFIGS. 4C and 4D, delivery catheter D remains in place proximate the aneurysm during the steps of the method described herein.
• As illustrated inFIG. 4E-4F, one or more embolic coils (or other embolic material) may then be delivered to the aneurysm, in much the same manner as described above, except that they are delivered directly into the aneurysm, instead of through the voids in the “walls” of thebridge1. The position of thedevice1 across the neck of the aneurysm prevents the unintended escape of embolic materials out of the aneurysm and into the parent vessel following the conclusion of the procedure (SeeFIG. 4G). The device remains in place in the parent vessel across the aneurysm neck during the delivery of coils, thereafter, and if desired, permanently.
• Details of an aneurysm bridge device according to the invention are illustrated inFIG. 5.Aneurysm bridge10 is illustrated in a deployed “in air” configuration.Aneurysm bridge10 is a more or less tubular device capable of being retained in a constrained form or shape prior to deployment, and then expanded (or permitted to expand) into contact with the walls of a vessel when deployed. Consequently, it may be positioned and delivered using a variety of methods similar to those summarized above in conjunction with the description ofFIGS. 3A-4G. As described in detail below,aneurysm bridge10 has many advantages over prior art devices for improved delivery, deployment, retraction, repositioning, and redeployment .
• Aneurysm bridge10 may be constructed from any number of compositions having suitable biocompatibility and strength characteristics. In the embodiment illustrated inFIG. 5,aneurysm bridge10 is constructed from Nitinol® with “shape memory” or superelastic characteristics to optimize self expansion of the device upon deployment.Aneurysm bridge10 is constructed by cutting features into a Nitinol tube. For example, a tube of 3.5 mm outer diameter and 0.005 inch thickness may be cut in a predetermined pattern of bands, struts, and/or connectors. Examples of suitable patterns are illustrated below inFIGS. 9 and 10, though variations on the patterns are within the scope of the invention. After the features are cut into the tube, the tube is twisted and shape set. It has been found that a helical arrangement resulting from the twist helps the deployed device conform to the vessel walls, and it also improves the ability of the device to resist kinking.
• An aneurysm bridge according to the invention may be dimensioned in any number of suitable sizes and lengths, depending upon the location of the aneurysm, variances in patient anatomy, and the size and shape of the aneurysm.Aneurysm bridge10 ofFIG. 5 in its expanded configuration is approximately 2.0-6.0 mm at its maximum outer diameter, and between 10-45 mm in length.Aneurysm bridge10 can be described while viewingFIG. 5 from left to right, with itsproximal end15 on the left side of the figure, itsdistal end18 on the right, and acentral region11 disposed therebetween. As described in greater detail below in conjunction with a description ofFIGS. 7-7C, generallytubular aneurysm bridge10 has a generally ovular shaped cross section at itsproximal end15 and itsdistal end18 when it is deployed in air. It is however generally circular in cross section throughout most of itscentral region11. Whenbridge10 is deployed in a vessel, it generally takes the shape and cross section of the vessel.
• InFIG. 5, twostandards20 and22 can be seen extending in a helical fashion fromproximal end15 todistal end18, more or less the entire length oftubular element10, though alternative embodiments may have a greater number of standards. The helical array ofaneurysm bridge10 may be imparted to a cut tube by graspingstandards20 and22 and applying a circumferential twist. (The extent of circumferential twist can be characterized in terms of the resulting angle ofstandards20 and22 to the longitudinal axis ofdevice10, and is illustrated inFIG. 7 below).Standards20 and22 have a width in the range of 0.0020-0.0050 inch, preferably between 0.0030-0.0045 inch, and impart axial and columnar strength uponaneurysm bridge10. The standards may also be used to provide axial force to the device if it is necessary to reposition the device after partial deployment within the vessel as discussed above.Standards20 and22 may further be equipped with features to facilitate loading of thefinished device10 into a sheath.
• Standard22 defines a portion of firsthelical spine25. Firsthelical spine25 extends in a helical fashion along the length ofaneurysm bridge10 fromproximal end15 todistal end18 as a result of the circumferential twist applied tostandards20 and22. Similarly, standard22 defines a portion of secondhelical spine27. Secondhelical spine27 extends in a helical fashion fromproximal end15 todistal end18 ofaneurysm bridge10. Firsthelical spine25 and secondhelical spine27 impart columnar strength and uniform, reduced size gap spacing along the length of thedevice10. The specific features that define firsthelical spine25 and secondhelical spine27 will be described in detail in relation toFIGS. 8 and 9, in which the features are more easily viewed.
• Among the advantages of the invention herein are its superior, kink-resistant, reversible trackability and reversible deployability within tortuous vasculature. In order to illustrate the superior tracking and reliable deployment of the system,device10 is shown deployed within atransparent vessel model30 inFIG. 6.Transparent model vessel30 has a curved configuration andmodel aneurysm34 located on the “outer” side ofcurve36.Device10 was tracked throughcurve36 and across the neck ofaneurysm34.Aneurysm bridge10 was permitted to expand radially outwardly to closely meet the walls of the vessel model. And despite the curved configuration of the vessel model, aneurysm bridge device readily deploys to contact the walls of the lumen. Moreover, when deployed in a curved vessel, the features ofdevice10, (which are described more specifically below in conjunction with a discussion ofFIG. 9) are disposed in a uniform, orderly configuration. No portion ofaneurysm bridge device10 bulges or protrudes intoaneurysm34. Consequently,aneurysm bridge device10 can be repositioned and redeployed readily if needed, or withdrawn completely from the vessel. Andaneurysm bridge device10 provides orderly gaps between struts or bands through which occlusion coils (not pictured) may be both delivered toaneurysm34 and prevented from escape therefrom.
• FIG. 7 illustrates other aspects ofaneurysm bridge10 from a truncated side elevational view. Firstly, the twist angle mentioned above in relation toFIG. 5 is more easily viewed inFIG. 7. Twist angle a is illustrated as the angle between standard20 and longitudinal axis x ofdevice10. Twist angle a is between 15° and 40°, and preferably between 20° and 35°, in either a clockwise or a counterclockwise direction. A particular twist angle may be imparted ondevice10 after pattern features illustrated inFIGS. 9 and 10 below are cut into a Nitinol tube.
• FIGS. 7A-7C illustrate cross sectional shapes of device10 (when it is deployed in air), along lines A, B and C ofFIG. 7 above.FIG. 7A illustrates the cross section ofproximal end15 at Detail A. Atproximal end15 ofaneurysm bridge10, standard20 is generallyopposite standard22.FIG. 7B illustrates the cross section ofcentral region11 at Detail B. AndFIG. 7C illustrates the cross section ofaneurysm bridge10 at detail C. Atdistal end18,standards20 and22 intersect one another along a wall ofaneurysm bridge10.Apexes24 are disposed opposite one another, at the narrowest portions of the oval.Central lumen28, which extends the length oftubular element10, is consequently ovular in cross section at the proximal and distal ends ofaneurysm bridge10, and circular in cross section in the central region of the device.
• FIG. 8 illustratesaneurysm bridge10 from a perspective view ofproximal end15, revealingcentral lumen28. (For clarity, the portion ofbridge10 on the “back side” oflumen28 is illustrated merely by dotted helical lines.)Distal end18 is essentially facing away from the viewer inFIG. 8.Bridge10 is again shown deployed in air, andproximal end15 has a generally ovular cross section. Atproximal end15, the proximal-most ends ofstandards20 and22 lie essentially opposite one another, along the narrowest portions of the oval.
• FIG. 9 illustrates an example of a cut pattern used to make a device according to the invention. Although an aneurysm bridge according to the invention is a generally tubular device shape set into a twisted configuration,FIG. 9 illustrates the device as though, before being shape set into a twist, it has been cut along its length and laid flat so that its features may be more easily viewed. Cut pattern50 has a proximal end52 and a distal end53. Cut pattern50 also has standards55 and57. Standard55 and standard57 have a similar set of features arrayed in a repeating pattern. For ease of reference, these features will be described especially in relation to standard55, though standard57 is also oriented to bands, struts or connectors having generally the same features. Extending laterally or diagonally from standard55 is a plurality of bands60. Bands60 have strut widths in the range of 0.00050-0.00150 inch, and preferably between 0.00060-0.00120 inch. Bands60 in turn extend to define S-connectors65. Standard55, bands60 and S-connectors65 define a first spine68. Second spine69 is defined by the corresponding features in conjunction with standard57. In the cut pattern50, spines68 and69 are generally straight. In a finished device, however, a circumferential twist will be shape set into the device, placing spines68 and69 in a helical configuration.
• Connected to the other ends of S-connectors65 are bands referred to as V-struts70. Each V-strut70 includes a short leg71, a long leg72, and an apex73 therebetween. Apexes73 are disposed pointing toward distal end53. Though other geometries are possible within the scope of the invention, the resulting lattice of first spine68, V-struts70, second spine69 and V-struts74 will define the skeletal “walls” of the generally tubular aneurysm bridge and the shape and size of voids within the walls.
• The function of S-connectors65 can be described as limiting the expansion between bands60. The expansion limiting function can most easily be viewed inFIG. 6.Aneurysm bridge10, deployed incurved model vessel30, hasbands12 and S-connectors13. The tighter spacing betweenbands12 is illustrated in comparison to the wider spacing of V-struts19. S-connectors13 tighten the gaps in the walls of the device, effectively reducing the size ofgaps26 by roughly half, thereby providing a barrier to coils that may be implanted intoaneurysm34. S-connectors13 also preventbands12 and V-struts19 from “poking” or protruding intoaneurysm34, an important advantage if the device must be repositioned, especially when the aneurysm is disposed in a curved vessel, as in the example ofFIG. 6. The closely spaced and generally uniform array imparted by S-connectors13 is imparted along the length of first helical spine25 (and secondhelical spine27, which is not visible inFIG. 5), and consequently along the length ofaneurysm bridge10.
• The function of V-struts19 can be characterized as maximizing the flexibility of thedevice10. The flexibility imparted by V-struts19 is very important for accommodating the flexure of the device both prior to deployment and over the life of the device. Prior to deployment of the device, most of the stress imparted on the device occurs during crimping down and loading the device into a sheath, and then tracking the crimped device through tortuous vasculature while crimped down and sheathed. Following deployment of the device within the vessel, most of the stress imparted on the device is a result of the ongoing, long term expansion and contraction due to pulsation of the vessel. In both configurations, the majority of the stress on the device is absorbed by the V-struts19. It is desirable for the device to be able to flex at the “V”; otherwise the stress may break the device, or deform the device beyond its ability to recover, or otherwise cause the device to fail.
• The specific structures ofbands12, S-connectors13 and V-struts19 ofFIGS. 5-8 are similar to the corresponding features ofFIGS. 9 and 10, but can be most easily viewed inFIG. 10.FIG. 10 illustrates an alternative embodiment according to the invention. Similar toFIG. 9, it illustrates a cut pattern of a generally tubular device as though it were cut along the length of the tube before the tube has been shape set, and laid flat so that the features of the pattern may be more easily viewed. Cut pattern90 hasproximal end92, distal end93, andstandards95 and97. Cut pattern90 has a lesser number ofbands100 than does cut pattern50 described above. Cut pattern90 has a correspondingly fewer number of S-connectors105 and V-struts110. Cut pattern90 accordingly will form a shorter length device than cut pattern50.
• An important similarity between the embodiment ofFIG. 10 and other embodiments is that S-connectors105 perform the same gap-limiting function without sacrificing needed flexibility. In order to perform this function, S-connectors105 are disposed betweenbands100 and V-struts110, and specifically very nearapexes112 of V-struts110. V-struts110 consequently have a short leg114 and a long leg116. S-connectors110 thereby maintain close spacing betweenbands100, while permitting flexure ofapexes112. Because most of the stress during flexure of the device made from cut pattern90 is absorbed byapexes112, it is important that the S-connector not completely prevent flexure ofapexes112. The positioning of S-connectors illustrated inFIG. 9 help definefirst spine94 and second spine96, yet permit flexure of V-struts110.Apexes112 additionally point in the direction of distal end93, facilitating resheathing of the device if needed.
• FIG. 11 illustrates a truncated view of a cut pattern to which a right hand twist has been applied. Cutpattern130 is illustrated as though a twisted tubular aneurysm bridge according to the invention were cut along its axis and unrolled to better display its features. More easily viewed inFIG. 11A, Detail A, taken from a distal portion ofcut pattern130 ofFIG. 11, reveals the structure ofbands150, S-connectors155, and V-struts160. Also visible inFIG. 11A ismarker165, which is disposed on the distal end ofstandard170. Thedistal extension175 of standard170 is between 0.0200-0.110 inch, and preferably between 0.0300 and 0.1050 inch in length.
• FIG. 11B is an enlarged view of Detail B, taken from a proximal region ofFIG. 11, to better illustrate some of its features. Again S-connectors155 are visible, as are V-struts160, and standard170. Affixed near the proximal end of standard170 is bump180 (shown from a top view of bump180). As mentioned above,bump180 is useful in loading a finished device on the distal end of a pusher prior to retaining the device with a sheath (seeFIGS. 3A-3C).
• See alsoFIG. 12, showing an enlarged schematic illustration of adevice200 according to the invention mounted on a pusher and retained by a sheath.Proximal end201 ofaneurysm bridge200 is shown mounted on the distal end of apusher202.Bumps205 are seen in engagement withapertures210.Sheath215 retainsaneurysm bridge200 in its reduced profile delivery configuration, and consequently keepsbumps205 in engagement withapertures210 until either proximal withdrawal ofsheath215, or untilpusher202 pushes the device out of the end ofsheath215.
• FIG. 13 is a perspective view of apusher tip300 that is not affixed to the distal end of a pusher.Pusher tip300 has a central lumen305, and three apertures310. A greater or lesser number of apertures are within the scope of the invention. Similar to the apertures described in relation toFIGS. 10-11 above, apertures310 permit the engagement of bumps on the proximal end of an aneurysm bridge device.Legs315 andeyelets317 permit the attachment ofpusher tip300 onto the distal end of a pusher.
• FIG. 13 is a perspective view of an alternative embodiment of a pusher tip according to the invention.Pusher tip400 hascentral lumen405 and twoapertures410 which can accommodate bumps on the proximal end of an aneurysm bridge device, to enhance retention of the device on the distal end of a pusher until deployment of the device at a desired time.Legs415 andeyelets417 enhance attachment ofpusher tip400 on the distal end of a pusher.
• It should be recognized that a number of variations of the above-identified embodiments will be obvious to one of ordinary skill in the art in view of the foregoing description. Accordingly, the invention is not to be limited to those specific embodiments and methods of the present invention illustrated and described herein. Rather, the scope of the invention is to be defined by the claims and their equivalents.

Claims (18)

What is claimed is:

1. A system for treatment of intracranial aneurysm comprising:

a device for bridging the neck of an aneurysm of a cerebral vessel, said device comprising a tubular element including a plurality of standards, a plurality of bands connected to the standards, a longitudinal axis, a reduced-profile delivery configuration and a deployed configuration, wherein said standards are oriented at an angle to said longitudinal axis when said tubular element is in said deployed configuration so that the standards and the bands together define a plurality of helical spines;

an introducer for introducing said tubular element into a vessel; and

a delivery device for delivering embolic material into the aneurysm.

2. The system according toclaim 1 wherein said angle is between 15° and 45°.

3. The system ofclaim 1 wherein the bands further comprise one or more V-struts, wherein each V-strut comprises a first leg, a second leg that is longer than said first leg, and an apex between said legs.

4. The system ofclaim 1 wherein said standards comprise a width of between 0.0020 inch and 0.0050 inch.

5. The system ofclaim 1 wherein said bands further comprise one or more V-struts, wherein each V-strut comprises a first leg, a second leg, and an apex between said legs, said first leg further comprising an S-shaped connector disposed near, but not on, said apex.

6. The system ofclaim 1 wherein said tubular element comprises shape memory material and said system further comprises a sheath, whereby said tubular element is retained in said low profile delivery configuration, wherein withdrawal of said sheath permits said tubular element to convert to its deployed configuration.

7. The system ofclaim 6 wherein said tubular element can be returned to its delivery configuration within said sheath.

8. The system ofclaim 1 wherein said system further comprises a sheath, and said tubular element can be withdrawn into said sheath via said introducer.

9. The system ofclaim 1 the introducer further comprising a tip comprising a central lumen, one or more legs, and at least one aperture.

10. The system according toclaim 9 wherein said first and second standards further comprises at least one bump configured to engage the at least one aperture.

11. A method of manufacture of an intravascular device, said method comprising the steps of:

providing a tube comprising one or more shape memory materials, a longitudinal axis, a proximal end and a distal end;

cutting the tube according to a predetermined pattern, wherein the predetermined pattern defines at least two parallel elongate standards, bands, and gaps between said bands;

applying a circumferential twist to the cut tube to orient the elongate elements at an angle to said longitudinal axis; and

applying a shape memory set to the twisted cut tube.

12. The method according toclaim 11 wherein said shape memory material is nitinol.

13. The method according toclaim 11 wherein said predetermined pattern defines only two parallel elongate standards.

14. The method according toclaim 11 wherein said predetermined pattern further defines a plurality of V-shaped bands having at least one end connected to an elongate standard.

15. The method according toclaim 14 wherein said V-shaped bands comprise apexes and S-shaped connectors, wherein said S-connectors are disposed near, but not upon, said apexes.

16. The method according toclaim 11 wherein the step of applying a circumferential twist to the cut tube is performed so that at least one of the elongate standards crisscrosses a second elongate standard at the distal end.

17. The method according toclaim 11 wherein said angle is between 15° and 45°.

18. A method of treating an aneurysm located in a blood vessel of a subject, the method comprising the steps of:

introducing an elongate tubular delivery device into the blood vessel and proximate the aneurysm, the delivery device suitable for delivery of embolic material;

introducing a tubular element for bridging the neck of the aneurysm, the tubular element being radially expandable from a compressed position to an expanded position, having a proximal end, a distal end, a longitudinal axis, at least two elongate standards and a plurality of bands attached thereto, the bands having gaps therebetween and further comprising a first leg, a second leg that is longer than said first leg, and an apex between said first leg and said second leg, the elongate standards arranged helically about the longitudinal axis from the proximal end to the distal end when the tubular element is in the expanded position, the elongate standards and bands together forming a first helical spine and a second helical spine;

bridging a neck of the aneurysm with the tubular element;

permitting the expandable tubular element to expand;

delivering one or more embolic materials to the aneurysm; and

withdrawing the tubular delivery device.

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