Patent Publication Number: US-2022211525-A1

Title: External steerable fiber for use in endoluminal deployment of expandable devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/668,500, entitled EXTERNAL STEERABLE FIBER FOR USE IN ENDOLUMINAL DEPLOYMENT OF EXPANDABLE DEVICES, filed Aug. 3, 2017, which is a continuation of U.S. application Ser. No. 13/658,597, entitled EXTERNAL STEERABLE FIBER FOR USE IN ENDOLUMINAL DEPLOYMENT OF EXPANDABLE DEVICES, filed Oct. 23, 2012, now U.S. Pat. No. 9,782,282, issued Oct. 10, 2017, which claims priority to U.S. Provisional Application Ser. No. 61/559,408, entitled EXTERNABLE STEERABLE FIBER FOR USE IN ENDOLUMINAL DEPLOYMENT OF EXPANDABLE DEVICES, filed Nov. 14, 2011, which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates generally to endoluminal devices and, more specifically, to steering expandable endoluminal devices within the vasculature of a patient. 
     Discussion of the Related Art 
     Endoluminal therapies typically involve the insertion of a delivery catheter to transport an implantable prosthetic device into the vasculature through a small, often percutaneous, access site in a remote vessel. Once access to the vasculature is achieved, the delivery catheter is used to mediate endoluminal delivery and subsequent deployment of the device via one of several techniques. In this fashion, the device can be remotely implanted to achieve a therapeutic outcome. In contrast to conventional surgical therapies, endoluminal treatments are distinguished by their “minimally invasive” nature. 
     Expandable endoluminal devices can be comprised of a graft or a stent component with or without a graft covering over the stent interstices. They can be designed to expand when a restraint is removed or to be balloon-expanded from their delivery diameter, through a range of intermediary diameters, up to a maximal, pre-determined functional diameter. The endoluminal delivery and deployment of expandable endoluminal devices pose several unique problems. For example, the endoluminal device itself must be constrained in a suitable introductory size (or delivery diameter) to allow insertion into the vasculature and mounted onto a delivery device such as a catheter shaft. In such configurations, the endoluminal devices can be difficult to navigate through vasculature that has significant bending or curvature. 
     Therefore, it is desirable to provide systems for endoluminal delivery of expandable endoluminal devices to vascular treatment sites, particularly along tortuous vasculature, such as along the aortic arch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure, wherein: 
         FIG. 1  illustrates a side view of a catheter assembly having an expandable implant; 
         FIGS. 2A and 2B  illustrate perspective views of catheter assemblies having expandable implants; 
         FIGS. 3A-3B and 3C-3D  illustrate cross-sectional and perspective views, respectively, of catheter assemblies having expandable implants; 
         FIGS. 4A-4D  illustrate various profile views of a distal end of an expandable implant; 
         FIGS. 5A-5D  illustrate perspective views of a catheter assembly having an expandable implant; 
         FIG. 6  illustrates a perspective view of an expandable implant; 
         FIGS. 7A-7H  illustrate cross-sectional views of an expandable implant and sleeve with steering fibers; 
         FIG. 8  illustrates a cross-sectional view of catheter assembly having an expandable implant; and 
         FIG. 9  illustrates a side view of a catheter assembly having an expandable implant. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and apparatuses configured to perform the intended functions. Stated differently, other methods and apparatuses can be incorporated herein to perform the intended functions. It should also be noted that the accompanying drawing figures referred to herein are not all drawn to scale, but can be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting. 
     Throughout this specification and in the claims, the term “distal” refers to a location that is, or a portion of an endoluminal device (such as a stent-graft) that when implanted is, further downstream with respect to blood flow than another portion of the device. Similarly, the term “distally” refers to the direction of blood flow or further downstream in the direction of blood flow. 
     The term “proximal” refers to a location that is, or a portion of an endoluminal device that when implanted is, further upstream with respect to blood flow than another portion of the device. Similarly, the term “proximally” refers to the direction opposite to the direction of blood flow or upstream from the direction of blood flow. 
     With further regard to the terms proximal and distal, and because the present disclosure is not limited to peripheral and/or central approaches, this disclosure should not be narrowly construed with respect to these terms. Rather, the devices and methods described herein can be altered and/or adjusted relative to the anatomy of a patient. 
     Throughout this specification and in the claims, the term “leading” refers to a relative location on a device which is closer to the end of the device that is inserted into and progressed through the vasculature of a patient. The term “trailing” refers to a relative location on a device which is closer to the end of the device that is located outside of the vasculature of a patient. 
     In various embodiments, a catheter assembly is disclosed which utilizes one or more flexible sleeves that (i) releasably constrain an expandable implant, such as an expandable endoluminal stent graft, in a dimension suitable for endoluminal delivery of the implant to a treatment site, such as a vascular member in a patient&#39;s body; and (ii) further constrain the implant to an outer peripheral dimension that is larger than the dimension suitable for endoluminal delivery but smaller than an unconstrained or fully deployed outer peripheral dimension, thereby facilitating selective axial and/or rotational positioning of the implant at the treatment site prior to full deployment and expansion of the implant. 
     Various embodiments of the present disclosure comprise a catheter assembly configured to deliver an expandable implant to a treatment area of the vasculature of a patient. In accordance with embodiments of the disclosure, the catheter assembly includes at least one steering line. The steering line (or lines) allows for selective bending of the expandable implant within the vasculature. 
     With initial reference to  FIG. 1 , a catheter assembly  100  in accordance with the present disclosure comprises a catheter shaft  102 , a main lumen  103  and an expandable implant  106 . Expandable implant  106  can comprise any endoluminal device suitable for delivery to the treatment area of a vasculature. Such devices can include, for example, stents, grafts, and stent grafts. 
     In various embodiments, expandable implant  106  comprises a stent graft. Conventional stent grafts are designed to dilate from their delivery diameter, through a range of intermediary diameters, up to a maximal, pre-determined functional diameter, and generally comprise one or more stent components with one or more graft members displaced over and/or under the stent. 
     In various embodiments, expandable implant  106  comprises one or more stent components made of nitinol and a graft member made of ePTFE. However, and as discussed below, any suitable combination of stent component(s) and graft member(s) is within the scope of the present disclosure. 
     For example, stent components can have various configurations such as, for example, rings, cut tubes, wound wires (or ribbons) or flat patterned sheets rolled into a tubular form. Stent components can be formed from metallic, polymeric or natural materials and can comprise conventional medical grade materials such as nylon, polyacrylamide, polycarbonate, polyethylene, polyformaldehyde, polymethylmethacrylate, polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene, polyvinylchloride, polyurethane, elastomeric organosilicon polymers; metals such as stainless steels, cobalt-chromium alloys and nitinol and biologically derived materials such as bovine arteries/veins, pericardium and collagen. Stent components can also comprise bioresorbable materials such as poly(amino acids), poly(anhydrides), poly(caprolactones), poly(lactic/glycolic acid) polymers, poly(hydroxybutyrates) and poly(orthoesters). Any expandable stent component configuration which can be delivered by a catheter is in accordance with the present disclosure. 
     Moreover, potential materials for graft members include, for example, expanded polytetrafluoroethylene (ePTFE), polyester, polyurethane, fluoropolymers, such as perfouorelastomers and the like, polytetrafluoroethylene, silicones, urethanes, ultra high molecular weight polyethylene, aramid fibers, and combinations thereof. Other embodiments for a graft member material can include high strength polymer fibers such as ultra high molecular weight polyethylene fibers (e.g., Spectra®, Dyneema Purity®, etc.) or aramid fibers (e.g., Technora®, etc.). The graft member can include a bioactive agent. In one embodiment, an ePTFE graft includes a carbon component along a blood contacting surface thereof. Any graft member which can be delivered by a catheter is in accordance with the present disclosure. 
     In various embodiments, a stent component and/or graft member can comprise a therapeutic coating. In these embodiments, the interior or exterior of the stent component and/or graft member can be coated with, for example, a CD34 antigen. Additionally, any number of drugs or therapeutic agents can be used to coat the graft member, including, for example heparin, sirolimus, paclitaxel, everolimus, ABT-578, mycophenolic acid, tacrolimus, estradiol, oxygen free radical scavenger, biolimus A9, anti-CD34 antibodies, PDGF receptor blockers, MMP-1 receptor blockers, VEGF, G-CSF, HMG-CoA reductase inhibitors, stimulators of iNOS and eNOS, ACE inhibitors, ARBs, doxycycline, and thalidomide, among others. 
     In various embodiments, expandable implant  106  can comprise a radially collapsed configuration suitable for delivery to the treatment area of the vasculature of a patient. Expandable implant  106  can be constrained in a radially collapsed configuration and mounted onto a delivery device such as catheter shaft  102 . The diameter of the expandable implant  106  in the collapsed configuration is small enough for the implant to be delivered through the vasculature to the treatment area. In various embodiments, the diameter of the collapsed configuration is small enough to minimize the crossing profile of catheter assembly  100  and reduce or prevent tissue damage to the patient. In the collapsed configuration, the expandable implant  106  can be guided by catheter shaft  102  through the vasculature. 
     In various embodiments, expandable implant  106  can comprise a radially expanded configuration suitable for implanting the device in the treatment area of a patient&#39;s vasculature. In the expanded configuration, the diameter of expandable implant  106  can be approximately the same as the vessel to be repaired. In other embodiments, the diameter of expandable implant  106  in the expanded configuration can be slightly larger than the vessel to be treated to provide a traction fit within the vessel. 
     In various embodiments, expandable implant  106  can comprise a self-expandable device, such as a self-expandable stent graft. Such devices dilate from a radially collapsed configuration to a radially expanded configuration when unrestrained. In other embodiments, expandable implant  106  can comprise a device that is expanded with the assistance of a secondary device such as, for example, a balloon. In yet other embodiments, catheter assembly  100  can comprise a plurality of expandable implants  106 . The use of a catheter assembly with any number of expandable implants is within the scope of the present disclosure. 
     Various medical devices in accordance with the disclosure comprise a sleeve or multiple sleeves. The sleeve or sleeves can constrain an expandable implant device in a collapsed configuration for endoluminal delivery of the implant to a treatment portion of the vasculature of a patient. For the purposes of the disclosure, the term “constrain” can mean (i) to limit the expansion, either through self-expansion or assisted by a device, of the diameter of an expandable implant or (ii) to cover or surround but not otherwise restrain an expandable implant (e.g., for storage or biocompatibility reasons and/or to provide protection to the expandable implant and/or the vasculature). For example, catheter assembly  100  comprises sleeve  104 . Sleeve  104  surrounds and constrains expandable implant  106  to a reduced diameter. 
     After delivery of the expandable implant to the treatment portion of the vasculature of the patient, the sleeve or sleeves can be unconstrained in order to allow the expandable implant to expand to its functional diameter and achieve the desired therapeutic outcome. In various embodiments, the sleeve or sleeves can remain implanted while not interfering with the expandable implant. In other embodiments, the sleeve or sleeves can be removed from the body of the patient after successful deployment of the expandable implant. 
     In various embodiments, an expandable implant is constrained by a single sleeve which circumferentially surrounds the expandable implant. For example, with reference to  FIG. 2B , catheter assembly  200  comprises a sleeve  204 . In various embodiments, sleeve  204  circumferentially surrounds expandable implant  206  and constrains it in a collapsed configuration, in which the diameter is less than the diameter of the unconstrained implant. For example, sleeve  204  can constrain expandable implant  206  in a collapsed configuration for delivery within the vasculature. 
     In other embodiments, an expandable implant is constrained by a plurality of sleeves which circumferentially surround the expandable implant. The plurality of sleeves can comprise at least two sleeves which circumferentially surround each other. 
     In various embodiments, sleeves can be tubular and serve to constrain an expandable implant. In such configurations, sleeves are formed from a sheet of one or more materials wrapped or folded about the expandable implant. While the illustrative embodiments herein are described as comprising one or more tubular sleeves, sleeves of any non-tubular shape that corresponds to an underlying expandable implant or that are otherwise appropriately shaped for a given application are also within the scope of the present disclosure. 
     In various embodiments, sleeves are formed by wrapping or folding the sheet of material(s) such that two parallel edges of the sheet are substantially aligned. Said alignment can or can not be parallel to or coaxial with the catheter shaft of a catheter assembly. In various embodiments, the edges of the sheet of material(s) do not contact each other. 
     In various embodiments, the edges of the sheet of material(s) do contact each other and are coupled with a coupling member (as described below) an adhesive, or the like. In various other embodiments, the edges of the sheet of material(s) are aligned so that the edges of the same side of the sheet or sheets (e.g., the front/first major surface or back/second major surface of the sheet) are in contact with each other. In still other embodiments, the edges of opposite sides of the sheet of material(s) are in contact with each other, such that the edges overlap each other, such that a portion of one side of the sheet is in contact with a portion of the other side. Said another way, the front of the sheet can overlap the rear of the sheet, or vice versa. 
     In various embodiments, sleeves comprise materials similar to those used to form a graft member. For example, a precursor flexible sheet used to make the sleeve can be formed from a flattened, thin wall ePTFE tube. The thin wall tube can incorporate “rip-stops” in the form of longitudinal high strength fibers attached or embedded into the sheet or tube wall. 
     The sheet of material(s) used to form the sleeve(s) can comprise a series of openings, such that the openings extend from one edge of the sheet to the other. In such configurations, a coupling member can be woven or stitched through the series of openings in the sheet of material(s), securing each of the two edges together and forming a tube. For example, in  FIG. 1 , coupling member  124  secures the edges of sleeve  104  such that sleeve  104  maintains expandable implant  106  in a reduced diameter. 
     In various embodiments, the coupling member can comprise a woven fiber. In other embodiments, the coupling member can comprise a monofilament fiber. Any type of string, cord, thread, fiber, or wire which is capable of maintaining a sleeve in a tubular shape is within the scope of the present disclosure. 
     In various embodiments, a single coupling member can be used to constrain the diameter of one or more sleeves. In other embodiments, multiple coupling members can be used to constrain the diameter of one or more sleeves. 
     In various embodiments, once a suitable expandable implant is in a collapsed configuration, the expandable implant can be deployed within the vasculature of a patient. An expandable implant in a collapsed configuration can be introduced to a vasculature and directed by a catheter assembly to a treatment area of the vasculature. Once in position in the treatment area of the vasculature, the expandable implant can be expanded to an expanded configuration. 
     In various embodiments, when the expandable implant is in position within the vasculature, the coupling member or members can be disengaged from the sleeve or sleeves from outside of the body of the patient, which allows the sleeve(s) to open and the expandable implant to expand. As discussed above, the expandable implant can be self-expanding, or the implant can be expanded by a device, such as a balloon. 
     The coupling member or members can be disengaged from the sleeve or sleeves by a mechanical mechanism operated from outside of the body of the patient. For example, the member or members can be disengaged by applying sufficient tension to the member or members. In another example, a dial or rotational element can be attached to the coupling member or members outside of the body. Rotation of the dial or rotational element can provide sufficient tension to, displace and disengage the coupling member or members. 
     In other configurations, coupling member or members can be disengaged by non-mechanical mechanisms, such as, for example, dissolution, by providing ultrasonic energy. In such configurations, sufficient ultrasonic energy is provided to coupling member or members to disengage them from the sleeve or sleeves. 
     In various embodiments, disengaging a single coupling member which closes a single sleeve from the sleeve allows the expandable device to be expanded. For example, with reference to  FIG. 2A , catheter assembly  200  can be used to deliver an implant expandable implant  206  to a treatment area of a vasculature. Expandable implant  206  has a collapsed diameter for delivery, and sleeve  204  circumferentially surrounds expandable implant  206  and is held closed by coupling member  224 . As described in more detail below, bending of expandable implant  206  can be controlled prior to full expansion (e.g., at an intermediate diameter) to help facilitate delivery to the desired position. Once expandable implant  206  is in position relative to the treatment area, coupling member  224  is disengaged from sleeve  204  and sleeve  204  is released, allowing expandable implant  206  to expand to a larger diameter. 
     As mentioned above, in various embodiments of the present disclosure, an expandable implant can further comprise an intermediate configuration. In the intermediate configuration, the diameter of the expandable implant is constrained in a diameter smaller than the expanded configuration and larger than the collapsed configuration. For example, the diameter of the expandable device in the intermediate configuration can be about 50% of the diameter of the expandable device in the expanded configuration. However, any diameter of the intermediate configuration which is less than the diameter of the expanded configuration and larger than the collapsed configuration is within the scope of the invention. 
     In such embodiments, the expandable implant can be expanded from the collapsed configuration to the intermediate configuration once the implant has been delivered near the treatment area of the vasculature of a patient. The intermediate configuration can, among other things, assist in properly orienting and locating the expandable implant within the treatment area of the vasculature. 
     In various embodiments, an expandable implant can be concentrically surrounded by two sleeves having different diameters. In such configurations, a primary sleeve constrains the expandable implant in the collapsed configuration. Once the collapsed configuration sleeve is opened, a secondary sleeve constrains the expandable implant in the intermediate configuration. As discussed above, the expandable implant can be self-expanding, or the implant can be expanded by a device, such as a balloon. 
     For example, with reference to  FIG. 2A , a catheter assembly  200  comprises an expandable implant  206  and sleeve  204 . Secondary sleeve  204  constrains expandable implant  206  to an intermediate configuration. Secondary sleeve  204  is held in position around expandable implant  206  by secondary coupling member  224 . 
     Catheter assembly  200  further comprises primary sleeve  208 , which constrains expandable implant  206  in a collapsed configuration for delivery to the vasculature of a patient. Primary sleeve  208  is held in position around expandable implant  206  by primary coupling member  234 . 
     Once expandable implant  206  is sufficiently close to the treatment area of the vasculature, primary coupling member  234  is disengaged from primary sleeve  208 , which releases primary sleeve  208  and allows expanded implant  206  to expand to a larger diameter. 
     With reference to  FIG. 2B , after primary sleeve  208  has been expanded, secondary sleeve  204  constrains the expandable implant  206  in the intermediate configuration. In the intermediate configuration, as mentioned above and as described in more detail below, expandable implant  206  can be oriented and adjusted (e.g., by bending and torsional rotation) to a desired location within the treatment area of the vasculature. 
     In other embodiments of the present disclosure, a single sleeve can be used to constrain the expandable implant in both a collapsed configuration and an intermediate configuration. For example, with reference to  FIGS. 3A-3D , catheter assembly  300  comprises an expandable implant  306 , a monosleeve  304 , a primary coupling member  334 , and a secondary coupling member  324 . 
     Monosleeve  304  further comprises a plurality of secondary holes  332 . In this configuration, secondary coupling member  324  is stitched or woven through secondary holes  332 , constricting monosleeve  304  and expandable implant  306  to the diameter of an intermediate configuration. In the intermediate configuration, the diameter of expandable implant  306  is less than the expanded diameter and larger than the diameter of the collapsed configuration. In the intermediate configuration, as described in more detail below, expandable implant  306  can be oriented and adjusted (e.g., by bending and torsional rotation) to a desired location within the treatment area of the vasculature. 
     Monosleeve  304  further comprises a plurality of primary holes  330 . In this configuration, primary coupling member  334  is stitched or woven through primary holes  330 , constricting monosleeve  304  and expandable implant  306  to the diameter of the collapsed configuration. The diameter of the collapsed configuration is selected to allow for delivery of the expandable implant  306  to the treatment area of the vasculature of a patient. 
     Once expandable implant  306  has been delivered to a region near the treatment area of the vasculature, primary coupling member  334  can be disengaged from monosleeve  304 , allowing expandable implant  306  to be expanded to the intermediate configuration. Expandable implant  306  can be oriented and adjusted (e.g., by bending and torsionally rotating) to a desired location within the treatment area of the vasculature. After final positioning, secondary coupling member  324  can be disengaged from monosleeve  304 , and expandable implant  306  can be expanded to the expanded configuration. 
     Although a number of specific configurations of constraining members (for example, primary and secondary members) and sleeves (for example, primary and secondary sleeves) have been discussed, the use of any number and/or configuration of constraining members and any number of sleeves is within the scope of the present disclosure. 
     In various embodiments, the catheter assembly further comprises a steering line. In such configurations, tension can be applied to the steering line to displace the steering line and bend the expandable implant. In various embodiments, the degree of bending of the expandable device relative to the catheter assembly is proportional to the amount of displacement of the steering line. Bending the expandable implant can, among other things, allow the implant to conform to curvatures in the vasculature of a patient. It can also assist in travelling through curved regions of vasculature. 
     For example, with reference to  FIGS. 2A-2B , steering line  220  passes from the outside of the body of a patient, through catheter shaft  202 , and is releasably coupled to expandable implant  206 . In such configurations, steering line  220  can be threaded through expandable implant  206  such that tension applied to steering line  220  from outside of the body of the patient causes expandable implant  206  to bend in a desired manner. 
     As a further example, with reference to  FIG. 6 , an expandable implant  606  is illustrated. Steering line  620  is threaded along the surface of expandable implant  606 . 
     In various embodiments, steering line  220  can comprise metallic, polymeric or natural materials and can comprise conventional medical grade materials such as nylon, polyacrylamide, polycarbonate, polyethylene, polyformaldehyde, polymethylmethacrylate, polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene, polyvinylchloride, polyurethane, elastomeric organosilicon polymers; metals such as stainless steels, cobalt-chromium alloys and nitinol. Further, steering line  220  can also be formed from high strength polymer fibers such as ultra high molecular weight polyethylene fibers (e.g., Spectra®, Dyneema Purity®, etc.) or aramid fibers (e.g., Technora®, etc.). However, any material that can be used to bend and/or steer an expandable implant is within the scope of the present disclosure. 
     With reference to  FIGS. 7A-H , cross-sectional views of various expandable implant configurations are illustrated. In various embodiments, an expandable implant can comprise a stent  705  and a graft member  707 , which are surrounded by sleeve  704 . In such configurations, a steering line  720  can be threaded through stent  705 , graft member  707 , and/or sleeve  704  in a variety of different patterns. Such patterns can, among other benefits, facilitate the bending of the expandable implant by applying tension to (and corresponding displacement of) steering line  720  from outside of the body. Further, such patterns can reduce or prevent steering line  720  from damaging tissue within the vasculature of the patient by limiting or preventing “bowstringing.” Bowstringing occurs when a string or thread travels in a direct line between two points on the inside of a curve in an expandable graft. This can cause the string or thread to come into contact with and potentially damage tissue in the vasculature. Bowstringing and its effects on tissue can also be reduced and/or minimized by sleeve  704  as sleeve  704  surrounds steering line  720  during bending and prior to full expansion of the expandable implant. 
     As illustrated in  FIGS. 7B-7H , steering line  720  can be woven through any combination of stent  705 , graft member  707 , and sleeve  704 . In each figure described below, a segment of a pattern is described. A steering line can be woven between a stent, graft member, and sleeve in any combination of these patterns. Alternatively, the steering line can interact with an expandable implant and one or more sleeves in any manner which allows steering line  720  to bend the expandable implant in a desired manner. 
     In  FIG. 7B , steering line  720  is threaded between the inner wall of sleeve  704  and stent  705 . In  FIG. 7C , steering line  720  passes between a first apex  751  of stent  705  and the outer wall of graft member  707 , passes between second apex  752  and the inner wall of sleeve  704 , extends into and through the wall of graft member  707 , reenters graft member  707 , passes between a third apex  753  of stent  705  and the inner wall of sleeve  704 , and passes between a fourth apex  754  and the inner wall of sleeve  704 . In  FIG. 7D , steering line  720  passes between first apex  751  and the outer wall of graft member  707 , then between second apex  752  and the inner wall of sleeve  704 . 
     In  FIG. 7E , steering line  720  passes between first apex  751  and the outer wall of graft member  707 , extends through the outer wall of graft member  707 , reenters graft member  707 , and passes between third apex  753  and the outer wall of graft member  707 . In  FIG. 7F , steering line  720  passes between the outside wall of graft member  707  and stent  705 . 
     In  FIG. 7G , steering line  720  passes from the inner wall of graft member  707 , through to the outer wall of graft member  707  between first apex  751  and second apex  752 , back through to the outer wall of graft member  707 , and back through to the inner wall of graft member  707  between third apex  753  and fourth apex  754 . In  FIG. 7H , steering line  720  is disposed against the inner wall of graft member  707 . As discussed previously,  FIGS. 7B-7G  illustrate example patterns in which a steering line can interact with an expandable implant. Any way in which a steering line interacts with an expandable implant to facilitate bending of the implant is within the scope of the present disclosure. 
     In various embodiments, a catheter assembly can comprise more than one steering line. For example, with reference to  FIG. 9 , catheter assembly  900  comprises two steering lines  920 . As described in relation to  FIGS. 7A-7G , steering lines  920  can be woven through the surface of expandable implant  906 . In various embodiments, steering lines  920  can exit catheter shaft  902  and engage expandable implant  906  near the proximal end of expandable implant  906 . In such configurations, steering lines  920  can travel across and remain substantially in contact with the surface of expandable implant  906  from the proximal end to the distal end. Steering lines  920  can then disengage the surface of expandable implant  906  and become secured to catheter assembly  900 . However, multiple steering lines  920  can interface with any portion of expandable implant  906 , including the proximal end, the distal end, and any portion between the two ends. 
     In various embodiments, steering lines  920  traverse and interact with the surface of expandable implant  906  in a pattern which facilitates controllable bending of expandable implant  906 . For example, as illustrated in  FIG. 9 , steering lines  920  can traverse the surface of expandable implant  906  such that, across a significant portion of expandable implant  906 , both steering lines  920  are parallel to and in close proximity with each other. Such a configuration allows the tension applied to steering lines  920  to work together to form a bend or curvature in the same segment of expandable implant  906 . Any configuration of steering lines  920  and surface of expandable implant  906  which allows for selective and controllable bending of expandable implant  906  is within the scope of the present disclosure. 
     In various embodiments, steering lines can traverse a path across and/or through the surface of expandable implant that is at least partially parallel to and substantially covered by one or more sleeves. 
     In various embodiments, the catheter assembly can further comprise a lock wire. In such embodiments, the lock wire can secure a steering line or lines to the catheter assembly. For example, with reference to  FIG. 8 , catheter assembly  800  comprises a catheter shaft  802 , expandable implant  806 , two steering lines  820 , and a lock wire  880 . Lock wire  880  passes from outside of the body of the patient, through catheter shaft  802 . Lock wire  880  exits a side port of the catheter shaft  802 , engages steering lines  820 , then reenters catheter shaft  802  and continues to catheter tip  818 . In such a configuration, lock wire  880  releasably couples steering lines  820  to catheter assembly  800 . Any manner in which lock wire  880  can interact with steering line or lines  820  to maintain a releasable coupling between steering line or lines  820  and catheter assembly  800  is within the scope of the present disclosure. 
     In various embodiments, each steering line can further comprise an end loop. For example, with reference to  FIG. 9 , each steering line  920  comprises an end loop  922 . Lock wire  980  can pass through each end loop  922 , securing each steering line  920  to catheter assembly  900 . Any method of securing steering line or lines  920  to catheter assembly  900  is within the scope of the invention. 
     In various embodiments, lock wire  980  can be formed from metallic, polymeric or natural materials and can comprise conventional medical grade materials such as nylon, polyacrylamide, polycarbonate, polyethylene, polyformaldehyde, polymethylmethacrylate, polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene, polyvinylchloride, polyurethane, elastomeric organosilicon polymers; metals such as stainless steels, cobalt-chromium alloys and nitinol. Further, lock wire  980  can also be formed from high strength polymer fibers such as ultra high molecular weight polyethylene fibers (e.g., Spectra®, Dyneema Purity®, etc.) or aramid fibers (e.g., Technora®, etc.). Any material that can provide sufficient engagement with and secure steering line  920  to catheter assembly  900  is within the scope of the present disclosure. 
     In various embodiments, a catheter assembly used to deliver an expandable implant comprises a catheter shaft, an expandable implant, one or more sleeves, one or more steering lines, and a lock wire. In such configurations, the expandable implant is capable of bending, through tension applied to the one or more steering lines and corresponding displacement, to conform to curvature in the vasculature of a patient. 
     For example, with reference to  FIGS. 5A-D , a catheter assembly  500  comprising an expandable implant  506  is illustrated. Catheter assembly  500  further comprises two steering lines  520 , a lock wire  580 , a primary coupling member  524 , and a secondary coupling member  534 . Primary coupling member  524  is releasably coupled to primary sleeve  504 . Secondary coupling member  534  is releasably coupled to secondary sleeve  508 . 
     Catheter assembly  500  is inserted into the vasculature of a patient, and expandable implant  506  is advanced to a treatment area of the vasculature. Upon arriving at a location close to the treatment area, primary coupling member  524  can be disengaged from primary sleeve  504 , allowing expandable implant  506  to be expanded to an intermediate configuration. In various embodiments, sleeve  504  can be removed from the vasculature once primary coupling member  524  has been disengaged. 
     With reference to  FIG. 5B , upon expansion to an intermediate configuration, tension can be applied to steering lines  520 , causing expandable implant  506  to bend in a desired manner. For example, expandable implant  506  can bend in a direction aligned with the location of steering lines  520 . Once expandable implant  506  has been sufficiently bent, consistent tension is applied to steering lines  520  to maintain the degree of bending. 
     In various embodiments, tension can be applied to steering lines  520  by pulling the lines from the outside of the body of the patient. In other embodiments, steering lines  520  can be connected to a one more dials or other mechanisms for applying the tension at the trailing end of catheter shaft  502 . In this configuration, the dial can be used to apply a desired tension, as well as maintain the correct amount of tension once a desired angle of bending of expandable implant  506  has been achieved. Various embodiments can also comprise an indicator, scale, gradient, or the like which demonstrates the amount of tension or displacement of the steering line, and/or the amount of bending in expandable implant  506 . In various embodiments, the catheter assembly can comprise one more additional markings (e.g., on a handle) that allow a user to determine the orientation of the steering line with respect to the vasculature. 
     After a sufficient degree of bending has been achieved in expandable implant  506 , the implant can be rotated for final positioning in the treatment area of the vasculature. In various exemplary embodiments, lock wire  580  is engaged with steering lines  520  such that torsional rotation of the catheter shaft causes expandable implant  506  to rotate within the vasculature. However, any configuration of catheter assembly  500  which allows for rotation of expandable implant  506  is within the scope of the present disclosure. 
     In various embodiments, an expandable implant can further comprise one or more radiopaque markers. In one embodiment, one or more radiopaque markers form a band around the distal end of the expandable implant. In other embodiments, one or more radiopaque markers can be embedded in a sleeve, such as a primary sleeve or a secondary sleeve. Further, one or more radiopaque markers can be embedded in a catheter shaft. In these configurations, the radiopaque markers can assist in deployment of an expandable implant by providing increased visibility when observing the expandable implant with a radiographic device, such as an x-ray machine. Any arrangement of radiopaque markers which assists in deployment of an expandable implant is within the scope of the present disclosure. 
     In various embodiments, radiopaque markers can assist in orienting the expandable implant by providing a profile view of the distal or proximal end of the expandable implant. For example, with reference to  FIG. 4 , a number of potential profiles  491 - 495  of the distal and/or proximal end of an expandable implant  406  are illustrated. In such configurations, radiopaque markers located in the distal and/or proximal end of expandable implant  406  provide a profile view of the end of expandable implant  406  when viewed by a radiographic device. Such profile views can be used to properly orient expandable implant  406  by assisting a user in determining the degree of rotation and/or orientation of a bend in expandable implant  406 . 
     For example, profile  491  represents a distal end of an expandable implant  406  having an orientation substantially orthogonal to a radiographic image capture device, such as an x-ray camera. Profile  492  represents a distal end of an expandable implant having an orientation less orthogonal than profile  491 . Profile  493  represents a distal end of an expandable implant  406  having an orientation less orthogonal than profile  492 . Finally, profile  494  represents a distal end of an expandable implant  406  having an orientation parallel to a radiographic image capture device. 
     After expandable implant  506  has been properly oriented and located within the treatment area of the patient, secondary coupling member  534  can be disengaged from secondary sleeve  508 . Once secondary coupling member  534  is disengaged from secondary sleeve  508 , expandable implant  506  can be expanded to a final position and diameter within the treatment area. In various exemplary embodiments, secondary sleeve  508  is removed from the vasculature. In other exemplary embodiments, secondary sleeve  508  remains in position circumferentially surrounding a portion of expandable implant  506 . 
     With reference to  FIG. 5C , after expandable implant  506  is in position and expanded within the vasculature, lock wire  580  can be disengaged from catheter assembly  500 . In various embodiments, lock wire  580  is disengaged by applying sufficient tension from outside of the body of the patient. After lock wire is disengaged, steering lines  520  can be released from coupling with catheter shaft  502  and can be removed from expandable implant  506  and catheter assembly  500 . 
     As illustrated in  FIG. 5D , after primary and secondary coupling members  524  and  534 , steering lines  520 , and lock wire  580  are removed from catheter assembly  500 , catheter assembly  500  is fully disengaged from expandable implant  506 , and can be removed from the vasculature of the patient. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents. 
     Likewise, numerous characteristics and advantages have been set forth in the preceding description, including various alternatives together with details of the structure and function of the devices and/or methods. The disclosure is intended as illustrative only and as such is not intended to be exhaustive. It will be evident to those skilled in the art that various modifications can be made, especially in matters of structure, materials, elements, components, shape, size and arrangement of parts including combinations within the principles of the disclosure, to the full extent indicated by the broad, general meaning of the terms in which the appended claims are expressed. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein.