Patent Publication Number: US-11660216-B2

Title: Removable stent

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 62/680,175, filed Jun. 4, 2018, the entire disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to methods and apparatuses for various digestive ailments. More particularly, the disclosure relates to removable stents for extending through a valved region. 
     BACKGROUND 
     Implantable stents are devices that are placed in a tubular body structure, such as a blood vessel, esophagus, trachea, biliary tract, colon, intestine, stomach or body cavity, to provide support and to maintain the structure open. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods. Of the known medical devices, delivery systems, and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices and delivery/retrieval devices as well as alternative methods for manufacturing and using medical devices and delivery/retrieval devices. 
     SUMMARY 
     This disclosure is directed to several alternative designs, materials, methods of manufacturing medical device structures and associated uses thereof, such as stents for preventing leaks after an anastomosis surgery and/or treating various gastro-intestinal, digestive, or other ailments. 
     One illustrative embodiment is an implant including a first region, a second region and a third region. The first region has a proximal end region and a distal end region. The first region includes a flared proximal stent frame tapering radially inward in a distal direction. The second region has a proximal end region and a distal end region. The second region includes a flexible sleeve extending distally from the distal end region of the first region. The third region has a proximal end region and a distal end region. The third region includes a distal stent frame having an outer diameter less than an outer diameter of the flared proximal stent frame adjacent the proximal end region of the first region and extending distally from the distal end region of the second region. The flexible sleeve is configured to extend across a natural valve or sphincter and collapse upon itself in response to a radially applied force. 
     Additionally or alternatively, in another embodiment the implant includes a first retrieval suture configured to at least partially collapse the implant for removal from a body lumen. 
     Additionally or alternatively, in another embodiment the first retrieval suture is interwoven with the flared proximal stent frame and the distal stent frame. 
     Additionally or alternatively, in another embodiment the first retrieval suture includes a first suture loop interwoven with the flared proximal stent frame adjacent the proximal end region of the first region, a second suture loop interwoven with the distal stent adjacent the proximal end region of the third region, and a connecting suture portion extending between and coupled to the first and second suture loops. 
     Additionally or alternatively, in another embodiment a proximal force exerted on the first retrieval suture is configured to partially collapse the flared proximal stent frame adjacent the proximal end region of the first region. 
     Additionally or alternatively, in another embodiment once the outer diameter of the flared proximal stent frame adjacent the proximal end region of the first region is partially collapsed, the distal stent frame is configured to begin collapsing simultaneously with further collapsing of the proximal stent frame. 
     Additionally or alternatively, in another embodiment the connecting suture portion includes a slack portion which is configured to be drawn taut as the flared proximal stent frame is partially collapsed before the distal stent frame begins to collapse. 
     Additionally or alternatively, in another embodiment the first retrieval suture includes a first suture loop interwoven with the distal stent frame adjacent the distal end region of the third region, a second suture loop interwoven with the flared proximal stent frame adjacent the distal end region of the first region, and a connecting suture portion extending between and coupled to the first and second suture loops. 
     Additionally or alternatively, in another embodiment a distal force exerted on the first retrieval suture is configured to partially collapse the distal stent frame adjacent the distal end region of the third region. 
     Additionally or alternatively, in another embodiment the connecting suture portion includes a slack portion which is configured to be drawn taut as the distal stent frame is partially collapsed before the flared proximal stent frame begins to collapse. 
     Additionally or alternatively, in another embodiment the implant includes a second retrieval suture. 
     Additionally or alternatively, in another embodiment the second retrieval suture is interwoven with the flared proximal stent frame and the distal stent frame. 
     Additionally or alternatively, in another embodiment at least one of the first or second retrieval sutures is configured to at least partially collapse the flared proximal stent frame prior to collapsing the distal stent frame. 
     Additionally or alternatively, in another embodiment at least one of the first or second retrieval sutures is configured to at least partially collapse the distal stent frame prior to collapsing the flared proximal stent frame. 
     Additionally or alternatively, in another embodiment the flared proximal stent frame has an outer profile configured to conform to an outlet of a stomach. 
     Additionally or alternatively, in another embodiment the outer diameter of the flared proximal stent frame adjacent the proximal end region of the first region is in the range of about 25 millimeters (mm) to about 50 mm. 
     Additionally or alternatively, in another embodiment the outer diameter of the distal stent frame is in the range of about 15 millimeters (mm) to about 25 mm. 
     Another illustrative embodiment is an implant including an elongated tubular member. The elongated tubular member includes a proximal stent, a flexible sleeve, and a distal stent. 
     The proximal stent has a proximal end region and a distal end region. The proximal stent tapers from a first outer diameter adjacent the proximal end region to a second smaller outer diameter adjacent the distal end region. The flexible sleeve has a proximal end region and a distal end region. The flexible sleeve extends distally from the distal end region of the flared proximal stent. The distal stent has a proximal end region and a distal end region. The distal stent has an outer diameter less than the first outer diameter of the proximal stent and extends distally from the distal end region of the flexible sleeve. A first retrieval suture is interwoven with the proximal stent and the distal stent. The flexible sleeve is configured to extend across a natural valve or sphincter and collapse upon itself in response to an applied radial force. 
     Additionally or alternatively, in another embodiment the proximal stent is configured to be positioned at a gastric outlet of a stomach and the flexible sleeve is configured to be positioned across a pyloric sphincter. 
     Additionally or alternatively, in another embodiment the applied radial force is a natural action of the pyloric sphincter. 
     Additionally or alternatively, in another embodiment the first retrieval suture is configured to at least partially collapse the proximal stent prior to begin collapsing the distal stent. 
     Additionally or alternatively, in another embodiment the first retrieval suture is configured to at least partially collapse the distal stent prior to begin collapsing the proximal stent. 
     Another illustrative embodiment is a method of removing or repositioning an endoluminal implant. The method includes actuating an end of a retrieval suture in a first direction. The retrieval suture is interwoven within an end region of a first stent of an endoluminal implant and an end region of a second stent of the endoluminal implant. The first and second stents are separated and connected by a flexible polymeric sleeve. The end region of the first stent is configured to partially collapse before the end of the second stent begins to collapse. 
     Additionally or alternatively, in another embodiment the retrieval suture includes a first circumferential loop extending around the end region of the first stent, a second circumferential loop extending around the end of the second stent, and a connecting suture portion extending between the first circumferential loop and the second circumferential loop, wherein a slack portion of the connecting suture portion is drawn taut as the end region of the first stent is partially collapsed before the end of the second stent begins to collapse. 
     Additionally or alternatively, in another embodiment the first stent is connected to the second stent only by the flexible polymeric sleeve. 
     The above summary of exemplary embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
         FIG.  1    is a side view of an illustrative implant; 
         FIG.  2    is a side view of another illustrative implant; 
         FIG.  3    is a side view of another illustrative implant; 
         FIG.  4    is a side view of another illustrative implant; 
         FIG.  5    is a side view of another illustrative implant; 
         FIG.  6    is a side view of the illustrative implant of  FIG.  1    with a retrieval suture in a first configuration; 
         FIG.  7    is a side view of the illustrative implant of  FIG.  6    with the implant in a partially collapsed configuration; 
         FIG.  8    is a side view of the illustrative implant of  FIG.  6    with the implant in a fully collapsed configuration; 
         FIG.  9    is a side view of the illustrative implant of  FIG.  1    with a retrieval suture in a second configuration; 
         FIG.  10    is a side view of the illustrative implant of  FIG.  9    with the implant in a partially collapsed configuration; 
         FIG.  11    is a side view of the illustrative implant of  FIG.  9    with the implant in a fully collapsed configuration; 
         FIG.  12    is a side view of another illustrative implant a retrieval suture; 
         FIG.  13    is a side view of the illustrative implant of  FIG.  12    with the implant in a partially collapsed configuration; 
         FIG.  14    is a side view of the illustrative implant of  FIG.  12    with the implant in a fully collapsed configuration; 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
     DETAILED DESCRIPTION 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the terms “about” may be indicative as including numbers that are rounded to the nearest significant figure. 
     The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     Although some suitable dimensions, ranges, and/or values pertaining to various components, features and/or specifications are disclosed, one of the skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed. 
     As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     For purposes of this disclosure, “proximal” refers to the end closer to the device operator during use, and “distal” refers to the end further from the device operator during use. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary. 
     It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with one embodiment, it should be understood that such feature, structure, or characteristic may also be used connection with other embodiments whether or not explicitly described unless cleared stated to the contrary. 
     Gastric outlet obstruction (GOO) is the clinical and pathophysiological consequence of any disease process that produces a mechanical impediment to gastric emptying. The presence of GOO can be classified into disease conditions that affect the antrum and pylorus that lead to pyloric dysfunction or disease conditions of the proximal duodenum that restrict efferent flow. Clinical conditions such as peptic ulcer disease (PUD), pyloric stenosis, and gastric polyps represent etiologies for the former with pancreatic carcinoma, ampullary cancer, duodenal cancer, cholangiocarcinomas representing etiologies for the latter. In some instances, GOO may be directly treated through stenting the location using gastrointestinal (GI) self-expanding stents. However, placing a stent across the pyloric valve may leave the pylorus in a continually open position. However, this may result in gastric leakage into the duodenum. Alternative stent designs are desired to allow the immediate blockage to be opened while allowing for natural pyloric function to be retained. 
       FIG.  1    illustrates a side view of an illustrative endoluminal implant  10  including a plurality of regions, including, a first or proximal region  12 , a second or intermediate region  14 , a third or intermediate region  16 , and a fourth or distal region  18 . While the illustrative implant  10  is shown and described as having four regions  12 ,  14 ,  16 ,  18 , it is contemplated the implant  10  may include any number of regions desired, such as, but not limited to, one, two, three, four, or more. Further, the regions  12 ,  14 ,  16 ,  18  may be any combination of structures and materials desired. In some cases, the implant  10  may include features (e.g., anti-migration flares, fixation spikes, sutures, etc.) to prevent distal/proximal displacement and/or migration of the implant  10 , once the implant  10  is positioned and expanded in the body lumen. The implant  10  may include a lumen  48  extending entirely through the length of the implant  10 , such as from a proximal end  24  of the first region  12  to a distal end  46  of the fourth region  18 . In some cases, the first region  12  may take the form of a stent  20  including an elongated tubular stent frame  22  defining a lumen. The stent  20  may be may be entirely, substantially, or partially covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent  20 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction through interstices of the stent  20  into the lumen. It is contemplated that leaving an outer rim or a portion of the surface uncovered, an area of hyperplasia can be generated which would create a seal. The stent  20  may include regions of differing diameters. For example, the stent  20  may include a flared (e.g., enlarged relative to other portions of the stent  20 ) proximal end region  24  tapering radially inward to a distal end region. While not explicitly shown, the stent  20  may include regions of constant diameter or increasing diameters (e.g., in the distal direction), if so desired. The stent frame  22  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  10  at the desired location in a body lumen. 
     In some cases, the third region  16  may take the form of a stent  28  including an elongated tubular stent frame  30  defining a lumen. The stent  28  may be may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent  28 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction through interstices of the stent  28  into the lumen. The stent  28  may have a uniform outer diameter from its proximal end region  32  to its distal end region  34 . However, the stent  28  may include regions of differing diameters if so desired. The stent frame  30  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  10  at the desired location in a body lumen. While not explicitly shown, in some embodiments, the distal stent  28  may extend distally to a distal end of the implant  10 . Some additional but non-limiting alternative configurations are shown and described with respect to  FIGS.  2 - 5   . 
     The stent frames  22 ,  30  may have a woven structure, fabricated from a number of filaments. In some embodiments, the stent frames  22 ,  30  may be knitted with one filament, as is found, for example, in the ULTRAFLEX™ stents, made and distributed by Boston Scientific Corp. In other embodiments, the stent frames  22 ,  30  may be braided with several filaments, as is found, for example, in the WALLFLEX®, WALLSTENT®, and POLYFLEX® stents, made and distributed by Boston Scientific Corp. In yet another embodiment, the stent frames  22 ,  30  may be of a knotted type, such the PRECISION COLONIC™ stents made by Boston Scientific Corp. In still another embodiment, the stent frames  22 ,  30  may be laser cut, such as the EPIC™ stents made by Boston Scientific Corp. It is contemplated that the stent frames  22 ,  30  may be formed having the same structure as one another or having a different structure from one another. 
     It is contemplated that the stent frames  22 ,  30  can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stents  20 ,  28  to be expanded into shape when accurately positioned within the body. The material of the stent frames  22 ,  30  may be the same or different, as desired. In some instances, the material may be selected to enable the stents  20 ,  28  to be removed with relative ease as well. For example, the stent frames  22 ,  30  can be formed from alloys such as, but not limited to, nitinol and ELGILOY®. Depending the on material selected for construction, the stents  20 ,  28  may be self-expanding (i.e., configured to automatically radially expand when unconstrained). In some embodiments, fibers may be used to make the stent frames  22 ,  30 , which may be composite fibers, for example, having an outer shell made of nitinol having a platinum core. It is further contemplated the stent frames  22 ,  30  may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some embodiments, the stents  20 ,  28  may be self-expanding while in other embodiments, the stents  20 ,  28  may be expanded by an expansion device (such as, but not limited to a balloon inserted within a lumen  48  of the implant  10 ). As used herein the term “self-expanding” refers to the tendency of the stent to return to a preprogrammed diameter when unrestrained from an external biasing force (for example, but not limited to a delivery catheter or sheath). 
     One or both of the stents  20 ,  28  may include a one-way valve, such as an elastomeric slit valve or duck bill valve, positioned within the lumen  48  thereof to prevent retrograde flow of fluid or other material, such as gastrointestinal fluids. 
     In some cases, the second portion  14  may take the form of a proximal flexible sleeve  36  and the fourth portion  18  may take the form of a distal flexible sleeve  42 . The proximal sleeve  36  may extend between the distal end of the proximal stent  20  and the proximal end of the distal stent  28 . For example, the proximal sleeve  36  may be connected, affixed, or secured to the distal end region  26  of the first or proximal stent  20  adjacent to a proximal end region  38  of the sleeve  36 . The proximal sleeve  36  may also be connected, affixed, or secured to the proximal end region  32  of the second or distal stent  28  adjacent to a distal end region  40  of the proximal sleeve  36 . In some cases, the proximal sleeve  36  may overlap a portion or all of the proximal stent  20  and/or a portion or all of the distal stent  28 . In some instances, the proximal sleeve  36  may be devoid of any structural components tending to hold the lumen  48  through the sleeve  36  open, thus allowing the sleeve  36  to collapse inward upon itself when subjected to the force of the pyloric valve closing off the lumen  48 . The distal sleeve  42  may be connected, affixed, or secured to the distal end region  44  of the second or distal stent  28  adjacent to a proximal end region  44  of the sleeve  42  and extend distally to a distal end region  46 . In some cases, the distal sleeve  42  may overlap a portion or all of the distal stent  28 . It is contemplated that the sleeve  36 ,  42  may be formed as individual flexible membranes or as a single unitary structure, as desired. In some embodiments, the sleeves  36 ,  42  may extend partially, substantially, or all of the length of the implant  10  and cover all other portions (exterior surface and/or interior surface) of the implant  10 , including the stents  20 ,  28 . Said differently, while the regions  12 ,  14 ,  16 ,  18  have been described as a stent  20 ,  28  or a sleeve  36 ,  42 , each region may include one or both of a frame structure and flexible sleeve structure. The sleeves  36 ,  42  may be secured to one or both of the stents  20 ,  28  by an adhesive or other methods known in the art, including by not limited to thermal methods, mechanical methods, etc. 
     The sleeves  36 ,  42  may each have an elongated, tubular shape defining a lumen. The lumen of the stents  20 ,  28  and the flexible sleeves  36 ,  42  may be fluidly connected to form the lumen  48  of the implant  10 . It is contemplated that one or more of the regions  12 ,  14 ,  16 ,  18  of the implant  10  may include more than one lumen, as desired. The sleeves  36 ,  42  may be a thin flexible membrane that readily collapses on itself. For example one or both of the sleeves may be configured to collapse upon itself under the applied radial force exerted by a natural valve or sphincter when the implant  10  is deployed in a body lumen having a natural valve or sphinctor. However, one or both of the sleeves  36 ,  42  may be provided with a radial support to hold it in the expanded configuration. Some examples and discussion of illustrative supports may be found in Patent Application No. 62/419,707, filed on Nov. 9, 2016, titled DEPLOYABLE SLEEVES AND RELATED METHODS, the disclosure of which is incorporated herein by reference. 
     The sleeves  36 ,  42  may include one or more of the following polymer materials: polyethylene, polypropylene, polystyrene, polyester, biosorbable plastics (e.g., polylactic acid), polycarbonate, polyvinyl chloride, polyacrylate, acrylate, polysulfone, polyetheretherketone, thermoplastic elastomers, thermoset elastomers (e.g., silicone), poly-p-xylylene (parylene), flouropolymers (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDFHFP)), bioplastics (e.g., cellulose acetate). The sleeves  36 ,  42  may additionally or alternatively include one or more of: polyurethane and its copolymers, ethylene vinyl-acetate, polyethylene terephthalate (PET), polyolefins, cellulosics, polyamides, acrylonitrile butadiene styrene copolymers, styrene isoprene butadiene (SIBS) block copolymers, acrylics, poly(glycolide-lactide) copolymer, Tecothane, PEBAX, poly(γ-caprolactone), poly(γ-hydroxybutyrate), polydioxanone, poly(γ-ethyl glutamate), polyiminocarbonates, poly(ortho ester), and/or polyanhydrides. Blends of the above polymers may also be employed, such as, but not limited to ChronoFlex®, manufactured by AdvanSource Biomaterials, based in Wilmington, Mass., a family of biodurable aromatic polycarbonate based thermoplastic urethanes. 
     In further detail, the implant  10  may be generally cylindrical in shape, although this is not required, substantially flexible, and sized appropriately for a convenient accommodation within the digestive tract. It is contemplated that various shapes, sizes and designs of the implant may be constructed depending on the size and geometry of the cavities where the implant  10  has to be placed. In various examples, the implant  10  may have a length between 3-12 inches, 3-6 inches, 0.5-20 feet (0.15-6.1 meters), between 3-5 feet (0.9-1.5 meters), or about 2-4 feet (0.6-1.2 meters). However, the implant  10  may have a length of less than 0.5 feet (0.15 meters) or greater than 20 feet (6.1 meters) in some instances. 
     In one illustrative example, the implant  10  may be sized to be positioned within the outlet of the stomach, extend across the pylorus and into the duodenum to treat, for example, gastric outlet obstruction. In such an example, the proximal stent  20  may be sized to prevent the implant  10  from migrating distally through the stomach outlet. For example, the proximal end region  24  of the proximal stent  20  may have an outer diameter  50  in the range of about 25 millimeters (mm) to about 50 mm. It is contemplated that the shape of the proximal stent  20  may be formed to match or generally conform to the shape of the stomach exit. The proximal sleeve  36  may be configured to extend across the pylorus and may have a length  54  in the range of about 6 mm to about 15 mm. The distal stent  28  and the distal sleeve  42  may be sized to be positioned within the duodenal bulb and duodenum, respectively, and may have an outer diameter  52  in the range of about 15 mm to about 25 mm. The distal stent  28  and the distal sleeve  42  may together have a length  56  in the range of about 60 mm to about 150 mm. When the distal stent  28  extends distally to a distal end of the implant  10 , the distal stent  28  may have a length  56  in the range of about 60 mm to about 150 mm. This is just an example. It is contemplated that the proximal sleeve  36  and/or the distal sleeve  42  may be positioned across other valved or sphincter regions with the proximal and/or distal stents  20 ,  28  sized and shaped for the adjacent anatomy. 
     Once implanted in a patient, the stents  20 ,  28  may exert a radially outward force to help secure the implant  10  to the body lumen. The implant  10  may be positioned in the antrum-pyloric-duodenum, esophagus, the gastro-esophageal junction (GEJ) region (e.g., at or near the cardia with the sleeve  24  extending into the esophagus), or at or near the pylorus with the sleeve  24  extending through the stomach or other portions of the gastro-intestinal system. In one example, the implant  10  may be positioned such that the proximal stent  20  is positioned at the stomach outlet with the proximal sleeve  36  bridging the pylorus. The flared structure of the proximal stent  20  may use the stomach to anchor the implant  10  and act as an anti-migration mechanism for the implant  10 . For example, the large outer diameter  50  of the proximal end  24  of the proximal stent  20  may engage the stomach outlet to prevent or limit movement of the implant  10 . The distal stent  28  may be placed within the duodenal bulb and the distal sleeve  42  may extend into the duodenum. The proximal sleeve  36  may be coupled to both the proximal stent  20  and the distal stent  28  such that a relative position of each section is fixed. 
     In some instances, the function of the pyloric valve may not have been impacted or degraded by the disease state which has caused the gastric outlet obstruction. In such an instance, it may be desirable to open the obstruction while still allowing for normal function of the pyloric valve. As described above, the proximal sleeve  36  may be formed from a flexible material. In other words, the proximal sleeve  36  may be free from any structure configured to exert a radially outward force on the surrounding tissue and may collapse upon itself under the applied radial force exerted by the natural valve or sphincter. This may allow the pyloric valve to function in a natural manner (e.g., to open and close). The distal stent  28  may be positioned adjacent to the gastric outlet obstruction. The stent frame  30  of the distal stent  28  may be constructed with sufficient radial force (e.g., to exert a sufficient radially outward force) to open the obstruction caused by the disease state. 
       FIG.  2    illustrates a side view of another illustrative implant  100  including a plurality of regions, including, a first or proximal region  102 , a second or intermediate region  104 , and a third or distal region  106 . The illustrative implant  100  may be similar in form and function to the implant  10  described above. While the illustrative implant  100  is shown and described as having three regions  102 ,  104 ,  106 , it is contemplated the implant  100  may include any number of regions desired, such as, but not limited to, one, two, three, four, or more. Further, the regions  102 ,  104 ,  106  may be any combination of structures and materials desired. In some cases, the implant  100  may include features (e.g., anti-migration flares, fixation spikes, sutures, etc.) to prevent distal/proximal displacement and/or migration of the implant  100 , once the implant  100  is positioned and expanded in the body lumen. The implant  100  may include a lumen  108  extending from a proximal end  114  of the first region  102  to a distal end  124  of the third region  106 . 
     In some cases, the first region  102  may take the form of a stent  110  including an elongated tubular stent frame  112  defining a lumen which may be similar in form and function to the proximal stent  20  described above. The stent  110  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  112 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  110  may include regions of differing diameters. For example, the stent  110  may include a flared (e.g., enlarged relative to other portions of the stent  110 ) proximal end region  114  tapering radially inward in a distal direction to a distal end region  116 . While not explicitly shown, the stent  110  may include regions of constant diameter or increasing diameters (e.g., increasing in the distal direction), if so desired. The stent frame  112  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  100  at the desired location in a body lumen. 
     In some cases, the third region  106  may take the form of a stent  118  including an elongated tubular stent frame  120  defining a lumen which may be similar in form and function to the distal stent  28  described above. The stent  118  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  120 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  118  may have a uniform outer diameter from its proximal end region  122  to its distal end region  124 . However, the stent  118  may include regions of differing diameters if so desired. The stent frame  120  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  100  at the desired location in a body lumen. While not explicitly shown, in some embodiments, the distal stent  118  may extend distally to a distal end to of the implant  100 . 
     In some cases, the second portion  104  may take the form of a flexible sleeve  126 . The sleeve  126  may extend between the distal end of the proximal stent  110  and the proximal end of the distal stent  118 . For example, the sleeve  126  may be connected, affixed, or secured to the distal end region  116  of the first or proximal stent  110  adjacent to a proximal end region  128  of the sleeve  126 . The sleeve  126  may also be connected, affixed, or secured to the proximal end region  122  of the second or distal stent  118  adjacent to a distal end region  130  of the sleeve  126 . In some cases, the sleeve  126  may overlap a portion or all of the proximal stent  110  and/or a portion or all of the distal stent  118 . Said differently, the sleeve  126  may extend from the proximal end region  114  of the proximal stent  110  to the distal end region  124  of the distal stent  118  such that the implant  100  is fully covered. Alternatively, and/or additionally, one or both of the proximal stent  110  and the distal stent  118  may be covered with a material or structure different from the sleeve  126  to provide a fully covered implant  100 . The sleeve  126  may be secured to one or both of the stents  110 ,  118  by an adhesive or other methods known in the art, including by not limited to thermal methods, mechanical methods, etc. 
     The sleeve  126  may have an elongated, tubular shape defining a lumen which may be similar in form or function to the sleeves  36 ,  42  described above. The lumen of the stents  110 ,  118  and the flexible sleeve  126  may be fluidly connected to form the lumen  108  of the implant  100 . It is contemplated that one or more of the regions  102 ,  104 ,  106  of the implant  100  may include more than one lumen, as desired. The sleeve  126  may be a thin flexible membrane that readily collapses on itself. However, in some instances, the sleeve  126  may be provided with a radial support. 
     The sleeve  126  may include one or more longitudinally extending slots  132  extending through a thickness of the sleeve  126 . The removal of material to form the slots  132  may allow for a connecting element to remain between the proximal stent  110  and the distal stent  118  while increasing the deformability and/or moveability of the sleeve  126 . Thus, when the sleeve  126  is positioned across a valve or sphincter, such as, but not limited to the pyloric valve, the reduced amount of material placed across the valve region may further allow for normal valve function. The sleeve  126  may include any number of longitudinally extending slots  132  desired, such as, but not limited to one, two, three, four, or more. The slots  132  may be positioned uniformly about a circumference of the sleeve  126  (e.g., having a uniform distance between adjacent slots  132 ) or eccentrically about a circumference of the sleeve  126  (e.g., having an unequal distant between adjacent slots  132 ). While the slots  132  have been described as extending longitudinally (e.g., along a longitudinal axis of the implant  100 ), it is contemplated that the slots  132  may extend along non-parallel angles relative to the longitudinal axis of the implant  100 . For example, the slots  132  may extend in a helical manner about a circumference of the sleeve  126 . 
     In one illustrative example, the implant  100  may be sized to be positioned within the outlet of the stomach, extend across the pylorus and into the duodenum to treat, for example, gastric outlet obstruction. In such an example, the proximal stent  110  may be sized to prevent implant  100  from migrating distally through the stomach outlet. For example, the proximal end region  114  of the proximal stent  110  may have an outer diameter  134  in the range of about 25 millimeters (mm) to about 50 mm. It is contemplated that the shape of the proximal stent  110  may be formed to match or generally conform to the shape of the stomach exit. The sleeve  126  may be configured to extend across the pylorus and may have a length  136  in the range of about 6 mm to about 15 mm. The distal stent  118  may be sized to be positioned within the duodenal bulb and duodenum, respectively, and may have an outer diameter  138  in the range of about 15 mm to about 25 mm. The distal stent  118  may have a length  140  in the range of about 60 mm to about 150 mm. This is just an example. It is contemplated that the sleeve  126  may be positioned across other valved or sphincter regions with the proximal and/or distal stents  110 ,  118  sized and shaped for the adjacent anatomy. 
     Once implanted in a patient, the stents  110 ,  118  may exert a radially outward force to help secure the implant  100  to the body lumen. The implant  100  may be positioned in the esophagus, the gastro-esophageal junction (GEJ) region, or at or near the pylorus with the sleeve  114  extending through the stomach or other portions of the gastro-intestinal system. In one example, the implant  100  may be positioned such that the proximal stent  110  is positioned at the stomach outlet with the sleeve  126  bridging the pylorus. The flared structure of the proximal stent  110  may use the stomach to anchor the implant  100  and act as an anti-migration mechanism for the implant  100 . For example, the large outer diameter  134  of the proximal end  114  of the proximal stent  110  may engage the stomach outlet to prevent or limit movement of the implant  100 . The distal stent  118  may be placed within the duodenal bulb and may extend into the duodenum. The sleeve  126  may be coupled to both the proximal stent  110  and the distal stent  118  such that a relative position of each section is fixed. 
     In some instances, the function of the pyloric valve may not have been impacted or degraded by the disease state which has caused the gastric outlet obstruction. In such an instance, it may be desirable to open the obstruction while still allowing for normal function of the pyloric valve. As described above, the sleeve  126  may be formed from a flexible material which may be made more flexible or pliable through the addition of slots  132 . In other words, the sleeve  126 , and thus the length of the intermediate region  104  between the proximal stent  110  and the distal stent  118 , may be free from any structure configured to exert a radially outward force on the surrounding tissue. This may allow the pyloric valve to function in a natural manner (e.g., to open and close). The distal stent  118  may be positioned adjacent to the gastric outlet obstruction. The stent frame  120  of the distal stent  118  may be constructed with sufficient radial force (e.g., to exert a sufficient radially outward force) to open the obstruction caused by the disease state. 
       FIG.  3    illustrates a side view of another illustrative implant  150  including a plurality of regions, including, a first region  152 , a second region  154 , and a third region  156 . The illustrative implant  150  may be similar in form and function to the implant  10  described above. While the illustrative implant  150  is shown and described as having three regions  152 ,  154 ,  156 , it is contemplated the implant  150  may include any number of regions desired, such as, but not limited to, one, two, three, four, or more. Further, the regions  152 ,  154 ,  156  may be any combination of structures and materials desired. In some cases, the implant  150  may include features (e.g., anti-migration flares, fixation spikes, sutures, etc.) to prevent distal/proximal displacement and/or migration of the implant  150 , once the implant  150  is positioned and expanded in the body lumen. The implant  150  may include a lumen  158  extending from a proximal end  164  of the first region  152  to a distal end  174  of the third region  156 . 
     In some cases, the first region  152  may take the form of a stent  160  including an elongated tubular stent frame  162  defining a lumen which may be similar in form and function to the proximal stent  20  described above. The stent  160  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  162 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  160  may include regions of differing diameters. For example, the stent  160  may include a flared (e.g., enlarged relative to other portions of the stent  160 ) proximal end region  164  tapering radially inward in a distal direction to a distal end region  166 . While not explicitly shown, the stent  160  may include regions of constant diameter or increasing diameters (e.g., increasing in the distal direction), if so desired. The stent frame  162  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  150  at the desired location in a body lumen. 
     In some cases, the third region  156  may take the form of a stent  168  including an elongated tubular stent frame  170  defining a lumen which may be similar in form and function to the distal stent  28  described above. The stent  168  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). For example, a partial covering could be used to cause hyperplasia for fixation or, for example, for biliary, or other, access. The covering may be disposed on an inner surface and/or outer surface of the stent frame  170 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  168  may have a uniform outer diameter from its proximal end region  172  to its distal end region  174 . However, the stent  168  may include regions of differing diameters if so desired. The stent frame  170  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  150  at the desired location in a body lumen. While not explicitly shown, in some embodiments, the distal stent  168  may extend distally to a distal end of the implant  150 . 
     In some cases, the second portion  154  may take the form of a flexible sleeve  176 . The sleeve  176  may extend between the distal end of the proximal stent  160  and the proximal end of the distal stent  168 . For example, the sleeve  176  may be connected, affixed, or secured to the distal end region  166  of the first or proximal stent  160  adjacent to a proximal end region  178  of the sleeve  176 . The sleeve  176  may also be connected, affixed, or secured adjacent or distal to the proximal end region  172  of the second or distal stent  168  adjacent to a distal end region  180  of the sleeve  176 . In some cases, the sleeve  176  may overlap a portion or all of the proximal stent  160  and/or a portion of the distal stent  168 . Said differently, the sleeve  176  may extend from the proximal end region  164  of the proximal stent  160  to a location proximal to the distal end region  174  of the distal stent  168  such that the implant  150  is not fully covered. For example, at least a portion of the distal stent  168  may be a bare stent. This may allow for tissue ingrowth to further secure the implant  150 . In some instances, all or a portion of the proximal stent  160  may be bare. Alternatively, and/or additionally, one or both of the proximal stent  160  and the distal stent  168  may be covered with a material or structure different from the sleeve  176  to provide a partially covered implant  150 . The sleeve  176  may be secured to one or both of the stents  160 ,  168  by an adhesive or other methods known in the art, including by not limited to thermal methods, mechanical methods, etc. 
     The sleeve  176  may have an elongated, tubular shape defining a lumen which may be similar in form or function to the sleeves  36 ,  42  described above. The lumen of the stents  160 ,  168  and the flexible sleeve  176  may be fluidly connected to form the lumen  158  of the implant  150 . It is contemplated that one or more of the regions  152 ,  154 ,  156  of the implant  150  may include more than one lumen, as desired. The sleeve  176  may be a thin flexible membrane that readily collapses on itself. However, in some instances, the sleeve  176  may be provided with a radial support. 
     The sleeve  176  may include one or more apertures  182  extending through a thickness of the sleeve  176 . For example, the sleeve  176  may have a mesh-like structure. The removal of material to form the apertures  182  may allow for a connecting element to remain between the proximal stent  160  and the distal stent  168  while increasing the deformability and/or moveability of the sleeve  176 . Thus, when the sleeve  176  is positioned across a valve or sphincter, such as, but not limited to the pyloric valve, the reduced amount of material placed across the valve region may further allow for normal valve function. The sleeve  176  may include any number of apertures  182  desired, such as, but not limited to one, two, three, ten, twenty, fifty, or more. The apertures  182  may be positioned uniformly about a circumference and/or length of the sleeve  176  (e.g., having a uniform distance between adjacent apertures  182 ) or eccentrically about a circumference and/or length of the sleeve  176  (e.g., having an unequal distant between adjacent apertures  182 ). 
     In one illustrative example, the implant  150  may be sized to be positioned within the outlet of the stomach, extend across the pylorus and into the duodenum to treat, for example, gastric outlet obstruction. In such an example, the proximal stent  160  may be sized to prevent implant  150  from migrating distally through the stomach outlet. For example, the proximal end region  164  of the proximal stent  160  may have an outer diameter  184  in the range of about 25 millimeters (mm) to about 50 mm. It is contemplated that the shape of the proximal stent  160  may be formed to match or generally conform to the shape of the stomach exit. The sleeve  176  may be configured to extend across the pylorus and may have a length  186  in the range of about 6 mm to about 15 mm. The distal stent  168  may be sized to be positioned within the duodenal bulb and duodenum, respectively, and may have an outer diameter  188  in the range of about 15 mm to about 25 mm. The distal stent  168  may have a length  190  in the range of about 60 mm to about 150 mm. This is just an example. It is contemplated that the sleeve  176  may be positioned across other valved or sphincter regions with the proximal and/or distal stents  160 ,  168  sized and shaped for the adjacent anatomy. 
     Once implanted in a patient, the stents  160 ,  168  may exert a radially outward force to help secure the implant  150  to the body lumen. The implant  150  may be positioned in the esophagus, the gastro-esophageal junction (GEJ) region, or at or near the pylorus with the sleeve  164  extending through the stomach or other portions of the gastro-intestinal system. In one example, the implant  150  may be positioned such that the proximal stent  160  is positioned at the stomach outlet with the sleeve  176  bridging the pylorus. The flared structure of the proximal stent  160  may use the stomach to anchor the implant  150  and act as an anti-migration mechanism for the implant  150 . For example, the large outer diameter  184  of the proximal end  164  of the proximal stent  160  may engage the stomach outlet to prevent or limit movement of the implant  150 . The distal stent  168  may be placed within the duodenal bulb and may extend into the duodenum. The sleeve  176  may be coupled to both the proximal stent  160  and the distal stent  168  such that a relative position of each section is fixed. 
     In some instances, the function of the pyloric valve may not have been impacted or degraded by the disease state which has caused the gastric outlet obstruction. In such an instance, it may be desirable to open the obstruction while still allowing for normal function of the pyloric valve. As described above, the sleeve  176  may be formed from a flexible material which may be made more flexible or pliable through the addition of apertures  182 . In other words, the sleeve  176 , and thus the length of the intermediate region  154  between the proximal stent  160  and the distal stent  168 , may be free from any structure configured to exert a radially outward force on the surrounding tissue. This may allow the pyloric valve to function in a natural manner (e.g., to open and close). The distal stent  168  may be positioned adjacent to the gastric outlet obstruction. The stent frame  170  of the distal stent  168  may be constructed with sufficient radial force (e.g., to exert a sufficient radially outward force) to open the obstruction caused by the disease state. 
       FIG.  4    illustrates a side view of another illustrative implant  200  including a plurality of regions, including, a first region  202 , a second region  204 , and a third region  206 . The illustrative implant  200  may be similar in form and function to the implant  10  described above. While the illustrative implant  200  is shown and described as having three regions  202 ,  204 ,  206 , it is contemplated the implant  200  may include any number of regions desired, such as, but not limited to, one, two, three, four, or more. Further, the regions  202 ,  204 ,  206  may be any combination of structures and materials desired. In some cases, the implant  200  may include features (e.g., anti-migration flares, fixation spikes, sutures, etc.) to prevent distal/proximal displacement and/or migration of the implant  200 , once the implant  200  is positioned and expanded in the body lumen. The implant  200  may include a lumen  208  extending from a proximal end  214  of the first region  202  to a distal end  224  of the third region  206 . 
     In some cases, the first region  202  may take the form of a stent  210  including an elongated tubular stent frame  212  defining a lumen which may be similar in form and function to the proximal stent  20  described above. The stent  210  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  212 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  210  may include regions of differing diameters. For example, the stent  210  may include a flared (e.g., enlarged relative to other portions of the stent  210 ) proximal end region  214  tapering radially inward in a distal direction to a distal end region  216 . While not explicitly shown, the stent  210  may include regions of constant diameter or increasing diameters (e.g., increasing in the distal direction), if so desired. The stent frame  212  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  200  at the desired location in a body lumen. 
     In some cases, the third region  206  may take the form of a stent  218  including an elongated tubular stent frame  220  defining a lumen which may be similar in form and function to the distal stent  28  described above. The stent  218  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  220 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  218  may have a uniform outer diameter from its proximal end region  222  to a location proximal to its distal end region  224 . In some instances, the distal end region  224  may include a flared region  226  (e.g., increasing in diameter or having an enlarged diameter relative to other portions of the stent  218 ). In some embodiments, the flared region  226  may include a transition region  228  which may be abrupt or step-wise or flared or sloped, as desired to a relatively constant enlarged diameter. In other embodiments, the flared region may slope or flare along its entire length (e.g., a continuously changing outer diameter). The stent frame  220  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  200  at the desired location in a body lumen. While not explicitly shown, in some embodiments, the distal stent  218  may extend distally to a distal end of the implant  200 . 
     In some cases, the second portion  204  may take the form of a flexible sleeve  230 . The sleeve  230  may extend between the distal end of the proximal stent  210  and the proximal end of the distal stent  218 . For example, the sleeve  230  may be connected, affixed, or secured to the distal end region  216  of the first or proximal stent  210  adjacent to a proximal end region  232  of the sleeve  230 . The sleeve  230  may also be connected, affixed, or secured adjacent or distal to the proximal end region  222  of the second or distal stent  218  adjacent to a distal end region  234  of the sleeve  230 . In some cases, the sleeve  230  may overlap a portion or all of the proximal stent  210  and/or a portion of the distal stent  218 . Said differently, the sleeve  230  may extend from the proximal end region  214  of the proximal stent  210  to the distal end region  224  of the distal stent  218  such that the implant  200  is fully covered. Alternatively, and/or additionally, one or both of the proximal stent  210  and the distal stent  218  may be covered with a material or structure different from the sleeve  230  to provide a partially covered implant  200 . The sleeve  230  may be secured to one or both of the stents  210 ,  218  by an adhesive or other methods known in the art, including by not limited to thermal methods, mechanical methods, etc. 
     The sleeve  230  may have an elongated, tubular shape defining a lumen which may be similar in form or function to the sleeves  36 ,  42  described above. The lumen of the stents  210 ,  218  and the flexible sleeve  230  may be fluidly connected to form the lumen  208  of the implant  200 . It is contemplated that one or more of the regions  202 ,  204 ,  206  of the implant  200  may include more than one lumen, as desired. The sleeve  230  may be a thin flexible membrane that readily collapses on itself. However, in some instances, the sleeve  230  may be provided with a radial support. 
     In one illustrative example, the implant  200  may be sized to be positioned within the outlet of the stomach, extend across the pylorus and into the duodenum to treat, for example, gastric outlet obstruction. In such an example, the proximal stent  210  may be sized to prevent implant  200  from migrating distally through the stomach outlet. For example, the proximal end region  214  of the proximal stent  210  may have an outer diameter  236  in the range of about 25 millimeters (mm) to about 50 mm. It is contemplated that the shape of the proximal stent  210  may be formed to match or generally conform to the shape of the stomach exit. The sleeve  230  may be configured to extend across the pylorus and may have a length  238  in the range of about 6 mm to about 15 mm. The distal stent  218  may be sized to be positioned within the duodenal bulb and duodenum, respectively, and may have an outer diameter  240  in the range of about 15 mm to about 25 mm. The distal stent  218  may have a length  242  in the range of about 60 mm to about 200 mm. This is just an example. It is contemplated that the sleeve  230  may be positioned across other valved or sphincter regions with the proximal and/or distal stents  210 ,  218  sized and shaped for the adjacent anatomy. 
     Once implanted in a patient, the stents  210 ,  218  may exert a radially outward force to help secure the implant  200  to the body lumen. The implant  200  may be positioned in the esophagus, the gastro-esophageal junction (GEJ) region, or at or near the pylorus with the sleeve  214  extending through the stomach or other portions of the gastro-intestinal system. In one example, the implant  200  may be positioned such that the proximal stent  210  is positioned at the stomach outlet with the sleeve  230  bridging the pylorus. The flared structure of the proximal stent  210  may use the stomach to anchor the implant  200  and act as an anti-migration mechanism for the implant  200 . For example, the large outer diameter  236  of the proximal end  214  of the proximal stent  210  may engage the stomach outlet to prevent or limit movement of the implant  200 . The distal stent  218  may be placed within the duodenal bulb and may extend into the duodenum. The sleeve  230  may be coupled to both the proximal stent  210  and the distal stent  218  such that a relative position of each section is fixed. 
     In some instances, the function of the pyloric valve may not have been impacted or degraded by the disease state which has caused the gastric outlet obstruction. In such an instance, it may be desirable to open the obstruction while still allowing for normal function of the pyloric valve. In other words, the sleeve  230 , and thus the length of the intermediate region  204  between the proximal stent  210  and the distal stent  218 , may be free from any structure configured to exert a radially outward force on the surrounding tissue. This may allow the pyloric valve to function in a natural manner (e.g., to open and close). The distal stent  218  may be positioned adjacent to the gastric outlet obstruction. The stent frame  220  of the distal stent  218  may be constructed with sufficient radial force (e.g., to exert a sufficient radially outward force) to open the obstruction caused by the disease state. 
       FIG.  5    illustrates a side view of another illustrative implant  250  including a plurality of regions, including, a first region  252 , a second region  254 , and a third region  256 . The illustrative implant  250  may be similar in form and function to the implant  10  described above. While the illustrative implant  250  is shown and described as having three regions  252 ,  254 ,  256 , it is contemplated the implant  250  may include any number of regions desired, such as, but not limited to, one, two, three, four, or more. Further, the regions  252 ,  254 ,  256  may be any combination of structures and materials desired. In some cases, the implant  250  may include features (e.g., anti-migration flares, fixation spikes, sutures, etc.) to prevent distal/proximal displacement and/or migration of the implant  250 , once the implant  250  is positioned and expanded in the body lumen. The implant  250  may include a lumen  258  extending from a proximal end  264  of the first region  252  to a distal end  224  of the third region  256 . 
     In some cases, the first region  252  may take the form of a stent  260  including an elongated tubular stent frame  262  defining a lumen which may be similar in form and function to the proximal stent  20  described above. The stent  260  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  262 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  260  may include regions of differing diameters. For example, the stent  260  may include a flared (e.g., enlarged relative to other portions of the stent  260 ) proximal end region  264  tapering radially inward in a distal direction to a distal end region  266 . While not explicitly shown, the stent  260  may include regions of constant diameter or increasing diameters (e.g., increasing in the distal direction), if so desired. The stent frame  262  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  250  at the desired location in a body lumen. 
     In some cases, the third region  256  may take the form of a stent  268  including an elongated tubular stent frame  270  defining a lumen which may be similar in form and function to the distal stent  28  described above. In some embodiments, the distal stent frame  270  may be formed using a different technique from the proximal stent frame  262 . For example, the distal stent frame  270  may be knitted while the proximal stent frame  262  may be braided. This is just an example. Other combinations of stent frames may be used, as desired. The stent  268  may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the stent frame  270 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. The stent  268  may have a uniform outer diameter from its proximal end region  272  to its distal end region  274 . However, the stent  268  may include regions of differing diameters if so desired. The stent frame  270  may be expandable between a radially collapsed delivery configuration and a radially expanded deployed configuration. The expanded configuration may secure the implant  250  at the desired location in a body lumen. While not explicitly shown, in some embodiments, the distal stent  268  may extend distally to a distal end of the implant  250 . 
     In some cases, the second portion  254  may take the form of a flexible sleeve  276 . The sleeve  276  may extend between the distal end of the proximal stent  260  and the proximal end of the distal stent  268 . For example, the sleeve  276  may be connected, affixed, or secured to the distal end region  266  of the first or proximal stent  260  adjacent to a proximal end region  278  of the sleeve  276 . The sleeve  276  may also be connected, affixed, or secured adjacent or distal to the proximal end region  222  of the second or distal stent  268  adjacent to a distal end region  280  of the sleeve  276 . In some cases, the sleeve  276  may overlap a portion or all of the proximal stent  260  and/or a portion of the distal stent  268 . Said differently, the sleeve  276  may extend from the proximal end region  264  of the proximal stent  260  to the distal end region  224  of the distal stent  268  such that the implant  250  is fully covered. Alternatively, and/or additionally, one or both of the proximal stent  260  and the distal stent  268  may be covered with a material or structure different from the sleeve  276  to provide a partially covered implant  250 . The sleeve  276  may be secured to one or both of the stents  260 ,  268  by an adhesive or other methods known in the art, including by not limited to thermal methods, mechanical methods, etc. 
     The sleeve  276  may have an elongated, tubular shape defining a lumen which may be similar in form or function to the sleeves  36 ,  42  described above. The lumen of the stents  260 ,  268  and the flexible sleeve  276  may be fluidly connected to form the lumen  258  of the implant  250 . It is contemplated that one or more of the regions  252 ,  254 ,  256  of the implant  250  may include more than one lumen, as desired. The sleeve  276  may be a thin flexible membrane that readily collapses on itself. However, in some instances, the sleeve  276  may be provided with a radial support. 
     In one illustrative example, the implant  250  may be sized to be positioned within the outlet of the stomach, extend across the pylorus and into the duodenum to treat, for example, gastric outlet obstruction. In such an example, the proximal stent  260  may be sized to prevent implant  250  from migrating distally through the stomach outlet. For example, the proximal end region  264  of the proximal stent  260  may have an outer diameter  282  in the range of about 25 millimeters (mm) to about 50 mm. It is contemplated that the shape of the proximal stent  260  may be formed to match or generally conform to the shape of the stomach exit. The sleeve  276  may be configured to extend across the pylorus and may have a length  284  in the range of about 6 mm to about 15 mm. The distal stent  268  may be sized to be positioned within the duodenal bulb and duodenum, respectively, and may have an outer diameter  286  in the range of about 15 mm to about 25 mm. The distal stent  268  may have a length  288  in the range of about 60 mm to about 250 mm. This is just an example. It is contemplated that the sleeve  276  may be positioned across other valved or sphincter regions with the proximal and/or distal stents  260 ,  268  sized and shaped for the adjacent anatomy. 
     Once implanted in a patient, the stents  260 ,  268  may exert a radially outward force to help secure the implant  250  to the body lumen. The implant  250  may be positioned in the esophagus, the gastro-esophageal junction (GEJ) region, or at or near the pylorus with the sleeve  264  extending through the stomach or other portions of the gastro-intestinal system. In one example, the implant  250  may be positioned such that the proximal stent  260  is positioned at the stomach outlet with the sleeve  276  bridging the pylorus. The flared structure of the proximal stent  260  may use the stomach to anchor the implant  250  and act as an anti-migration mechanism for the implant  250 . For example, the large outer diameter  282  of the proximal end  264  of the proximal stent  260  may engage the stomach outlet to prevent or limit movement of the implant  250 . The distal stent  268  may be placed within the duodenal bulb and may extend into the duodenum. The sleeve  276  may be coupled to both the proximal stent  260  and the distal stent  268  such that a relative position of each section is fixed. 
     In some instances, the function of the pyloric valve may not have been impacted or degraded by the disease state which has caused the gastric outlet obstruction. In such an instance, it may be desirable to open the obstruction while still allowing for normal function of the pyloric valve. In other words, the sleeve  276 , and thus the length of the intermediate region  254  between the proximal stent  260  and the distal stent  268 , may be free from any structure configured to exert a radially outward force on the surrounding tissue. This may allow the pyloric valve to function in a natural manner (e.g., to open and close). The distal stent  268  may be positioned adjacent to the gastric outlet obstruction. The stent frame  270  of the distal stent  268  may be constructed with sufficient radial force (e.g., to exert a sufficient radially outward force) to open the obstruction caused by the disease state. 
       FIG.  6    illustrates a side view of the illustrative implant  10  of  FIG.  1    including a retrieval suture  60 . Some implants, such as, but not limited to the implant  10  shown in  FIG.  6    may be designed or intended to be removable or repositionable. In some cases, a suture, such as, but not limited to, the suture  60  illustrated may be used to collapse a portion of the implant (in some instances, the suture may be woven through the scaffolding adjacent a proximal end of the implant) to reduce the profile of an implant. As described above, the implant  10  may be positioned across a valve location (e.g., the pyloric valve) such that the proximal stent  20  is proximal to the valve and the distal stent  28  is distal to the valve. As the stent frame  22  of the proximal stent  20  is not directly coupled with the stent frame  30  of the distal stent  28 , a suture woven through the proximal end region  24  of the proximal stent  20  may not necessarily reduce the profile of both the proximal stent  20  and the distal stent  28 . It is contemplated that in order to remove or reposition the implant  10  both the profile of the proximal stent  20  and the distal stent  28  may need to be reduced in order to move the implant  10 . For example, the distal stent  28  may have a deployed diameter that is larger than the pyloric valve (or other natural valve) to prevent or reduce proximal migration. As such, to move the implant  10  a profile of the distal stent  28  may need to be reduced from its deployed configuration. 
     In order to collapse both the proximal stent  20  and the distal stent  28 , the suture  60  may include a plurality of components or regions each configured to perform a function. A first region of the suture  60  may be a retrieval suture loop  62  which may be configured to be grasped by forceps or another tool during a clinical procedure for stent removal or repositioning. The retrieval suture loop  62  may extend proximally from the proximal end region  24  of the proximal stent  20  to allow the retrieval suture loop  62  to be easily grasped and pulled in a proximal direction. However, this is not required. In some instances, it may be desirable to position the retrieval suture loop  62  near the distal stent  28 . It is contemplated that the suture  60  may be arranged in a number of different patterns such that various portions of the proximal stent  20  and/or the distal stent  28  are collapsed in a desired order. For example, in some instances, it may be desirable to collapse the proximal end region  32  of the distal stent  28  prior to collapsing the proximal stent  20 . 
     A second region of the suture  60  may include a first suture loop  64  which is interwoven to the proximal end region  24  of the proximal stent  20 . The first suture loop  64  may extend around the entire circumference of the proximal end region  24  of the proximal stent  20 . The first suture loop  64  may be configured to reduce a profile of the proximal stent  20  from its deployed configuration. A third region of the suture  60  may include a second suture loop  66  which is interwoven through the proximal end region  32  of the distal stent  28 . The second suture loop  66  may extend around the entire circumference of the proximal end region  32  of the distal stent  28 . The second suture loop  66  may be configured to reduce the profile of the distal stent  28  from its deployed configuration. A fourth region of the suture  60  may include a connecting suture portion  68  that extends between and couples the first suture loop  64  and the second suture loop  66 . The connecting suture portion  68  may be configured to couple the first suture loop  64  and the second suture loop  66  such that actuation of the retrieval suture loop  62  is translated to both the first suture loop  64  and the second suture loop  66 . It is noted that in some instances, the suture  60  may not include a portion, such as the retrieval suture loop  62 , extending proximally from the first suture loop  64 , and thus surgical personnel may grasp the first suture loop  64  directly to initiate retrieval of the implant  10 . 
     The suture  60  may be formed from a length of material having a first end  70  and a second end  72 . The length of material may be one long continuous unitary structure or a plurality of structures coupled together, as desired. To assemble the suture  60  with the implant  10 , the first end  70  may be interwoven through the stent frame  22  adjacent the proximal end region  24  of the proximal stent  20  until it extends about the circumference or substantially all of the circumference of the proximal stent  20 . In some instances the suture  60  may be tied, knotted or otherwise secured to itself at the juncture of the circumferential portion of the first suture loop  64  and the connecting suture portion  68 . The first end  70  of the suture  60  may then be advanced distally through or alongside the proximal stent  20  and the proximal sleeve  36  until it reaches the proximal end region  32  of the distal stent  28 , thus forming the connecting suture portion  68 . It is contemplated that the connecting suture portion  68  may extend along an outer surface of the proximal stent  20  and proximal sleeve  36  or along an inner surface (e.g., within the lumen  48 ) of the proximal stent  20  and the proximal sleeve  36 , as desired. The first end  70  of the suture  60  may then be interwoven through the stent frame  30  adjacent to the proximal end region  32  of the distal stent  28  until extends about the circumference or substantially all of the circumference of the distal stent  28 . The first end  70  of the suture  60  may then be knotted, tied, or otherwise secured to itself or the distal stent  28 . The second end  72  of the suture  60  may be looped or knotted to form the retrieval suture loop  62 . 
     To collapse the implant  10  the retrieval suture loop  62 , or the first suture loop  64  in the absence of the retrieval suture loop  62 , may be pulled or otherwise actuated in a proximal direction. As the retrieval suture loop  62 , or the first suture loop  64  in the absence of the retrieval suture loop  62 , is pulled in the proximal direction, the first suture loop  64  begins to constrain or reduce the diameter of the proximal stent  20  as shown in  FIG.  7   , which illustrates a side view of the illustrative implant  10  during suture  60  actuation. It is contemplated that the length of the connecting suture portion  68  may be predetermined and selected based on both the difference in diameter of the proximal end region  24  of the proximal stent and the proximal end region  32  of the distal stent  28  and the distance between the proximal end region  24  of the first proximal stent  20  and the proximal end region  32  of the distal stent  28 . The length of the connecting suture portion  68  may be greater than the distance between the first suture loop  64  and the second suture loop  66  in the deployed, expanded configuration, providing the connecting suture portion  68  slack. Thus, the length of the connecting suture portion  68  may be selected such that the first suture loop  64  is pulled to constrain the proximal end region  24  of the proximal stent  20  a first amount before the slack is taken up and the connecting suture portion  68  is pulled taut. Thereafter, further pulling on the retrieval suture loop  62 , or the first suture loop  64  in the absence of the retrieval suture loop  62 , causes the connecting suture portion  68  to apply a pulling force on the second suture loop  66  to begin constraining the distal stent  28 . For example, the length may be selected such that when the diameter of the proximal end region  24  of the proximal stent  20  is partially constrained or reduced in diameter a first amount, the second suture loop  66  begins to constrain or reduce the diameter of the distal stent  28  adjacent the proximal end  32  thereof. The length may be selected such that when the diameter of the proximal end region  24  of the proximal stent  20  is constrained or reduced to approximately the same diameter as the distal end region  32  of the distal stent the second suture loop  66  begins to constrain a reduced diameter of the distal stent  28  adjacent the proximal end  32  thereof. In other words, the connecting suture portion  68  may include some slack or extra length that prevents the proximal actuation of the retrieval suture loop  62  from actuating the second suture loop  66  until after the first suture loop  64  has been at least partially constrained. Continued proximal actuation of the retrieval suture loop  62  once the proximal end region  24  of the proximal stent  20  has been partially constrained (e.g., is approximately equal in diameter to the proximal end region  32  of the distal stent  28 ) will cause both the proximal stent  20  and the distal stent  28  to reduce in diameter or constrain at approximately the same rate at the same time, as shown in  FIG.  8   , which illustrates a side view of the illustrative implant  10  with the implant  10  in a fully constrained configuration. This may allow for a smooth and easy repositioning or removal. However, in some embodiments, the length of the connecting suture portion  68  may be selected such that the proximal end regions  24 ,  32  of the proximal and distal stents  20 ,  28  are configured to collapse the reducing profile at approximately the same time.  FIG.  9    illustrates a side view of the illustrative implant  10  of  FIG.  1    including an alternative retrieval suture  80 . In order to collapse both the proximal stent  20  and the distal stent  28 , the suture  80  may include a plurality of components or regions each configured to perform a function. A first region of the suture  80  may be a retrieval suture loop  82  which may be configured to be grasped by forceps or another tool during a clinical procedure for stent removal or repositioning. A second region of the suture  80  may include a first suture loop  84  which is interwoven within the distal end region  34  of the distal stent  28 . The first suture loop  84  may be configured to reduce a profile of the distal stent  28  from its deployed configuration. A third region of the suture  80  may include a second suture loop  86  which is interwoven through the distal end region  26  of the proximal stent  20 . The second suture loop  86  may be configured to reduce the profile of the proximal stent  20  from its deployed configuration. A fourth region of the suture  80  may include a connecting suture portion  88  that extends between and couples the first suture loop  84  and the second suture loop  86 . The connecting suture portion  88  may be configured to couple the first suture loop  84  and the second suture loop  86  such that actuation of the retrieval suture loop  82  is translated to both the first suture loop  84  and the second suture loop  86 . 
     The suture  80  may be formed from a length of material having a first end  90  and a second end  72 . The length of material may be one long continuous unitary structure or a plurality of structures coupled together, as desired. To assemble the suture  80  with the implant  10 , the first end  90  may be interwoven through the stent frame  30  adjacent the distal end region  34  of the distal stent  28  until it extends about the circumference or substantially all of the circumference of the distal stent  28 . In some instances the suture  80  may be tied, knotted or otherwise secured to itself at the juncture of the circumferential portion of the first suture loop  84  and the connecting suture portion  88 . The first end  90  of the suture  80  may then be advanced proximally through the distal stent  28  and the proximal sleeve  36  until it reaches the distal end region  26  of the proximal stent  20 , thus forming the connecting suture portion  88 . It is contemplated that the connecting suture portion  88  may extend along an outer surface of the distal stent  28  and proximal sleeve  36  or along an inner surface (e.g., within the lumen  48 ) of the distal stent  28  and the proximal sleeve  36 , as desired. The first end  90  of the suture  80  may then be interwoven through the stent frame  22  adjacent to the distal end region  26  of the proximal stent  20  until extends about the circumference or substantially all of the circumference of the proximal stent  20 . The first end  90  of the suture  80  may then be knotted, tied, or otherwise secured to itself or the proximal stent  20 . The second end  92  of the suture  80  may be looped or knotted to form the retrieval suture loop  82 . 
     To collapse the implant  10  the retrieval suture loop  82  may be pushed or otherwise actuated in a distal direction. It is contemplated the device may be advanced through the lumen  48  to execute the distal force required to actuate the retrieval suture loop  82  in a distal direction. As the retrieval suture loop  82  is pushed in the distal direction, the first suture loop  84  begins to constrain or reduce the diameter of the distal stent  28  as shown in  FIG.  10   , which illustrates a side view of the illustrative implant  10  during suture  80  actuation. It is contemplated that the length of the connecting suture portion  88  may be predetermined and selected based on both the difference in diameter of the distal end region  34  of the distal stent  28  and the distal end region  26  of the proximal stent  20  and the distance between the distal end region  34  of the distal stent  28  and the distal end region  26  of the proximal stent  20 . The length of the connecting suture portion  88  may be greater than the distance between the first suture loop  84  and the second suture loop  86  in the deployed, expanded configuration, providing the connecting suture portion  88  slack. Thus, the length of the connecting suture portion  88  may be selected such that the first suture loop  84  is pulled to constrain the distal end region  34  of the distal stent  28  a first amount before the slack is taken up and the connecting suture portion  88  is pulled taut. Thereafter, further pulling on the retrieval suture loop  82  causes the connecting suture portion  88  to apply a pulling force on the second suture loop  86  to begin constraining the proximal stent  20 . For example, the length may be selected such that when the diameter of the distal end region  34  of the distal stent  28  is partially constrained or reduced in diameter a first amount, the second suture loop  86  begins to constrain or reduce the diameter of the proximal stent  20  adjacent the distal end  26  thereof. The length may be selected such that the distal stent  28  is reduced in profile or diameter, at least in part, prior to reducing a diameter or profile of the distal end region  26  of the proximal stent  20 . In other words, the connecting suture portion  88  may include some slack or extra length that prevents the distal actuation of the retrieval suture loop  82  from actuating the second suture loop  66  until after first suture loop  84  has been at least partially constrained. Continued distal actuation of the retrieval suture loop  82  after any slack in the connecting suture portion  88  has been consumed through distal actuation will cause both the proximal stent  20  and the distal stent  28  to reduce in diameter or constrain at approximately the same rate at the same time, as shown in  FIG.  11   , which illustrates a side view of the illustrative implant  10  with the implant  10  in a fully constrained configuration. This may allow for a smooth and easy repositioning or removal in a distal direction. However, in some embodiments, the length of the connecting suture portion  88  may be selected such that the distal end regions  26 ,  34  of the proximal and distal stents  20 ,  28  are configured to collapse the reducing profile at approximately the same time. 
     While not explicitly shown, it is contemplated that the implant  10  may be provided with two or more sutures or suture patterns that allow the clinician to select which stent  20 ,  28  (and/or region of the stent  20 ,  28 ) is collapsed first. For example, the implant  10  may include both the suture configuration  60  illustrated in  FIGS.  6 - 8    and the suture configuration  80  illustrated in  FIGS.  9 - 11   . 
       FIG.  12    illustrates a side view of another illustrative implant  300 .  FIG.  302    illustrates a side view of another illustrative implant  300 , such as, but not limited to, a stent. In some instances, the stent  300  may be formed from an elongated tubular stent frame  302 . While the stent  300  is described as generally tubular, it is contemplated that the stent  300  may take any cross-sectional shape desired. The stent  300  may have a first, or proximal end  304 , a second, or distal end  306 , and an intermediate region  308  disposed between the first end  304  and the second end  306 . The stent  300  may include a lumen  310  extending from a first opening adjacent the first end  304  to a second opening adjacent to the second end  306  to allow for the passage of food, fluids, etc. 
     The stent  300  may be expandable from a first radially collapsed configuration (not explicitly shown) to a second radially expanded configuration. In some cases, the stent  300  may be deployed to a configuration between the collapsed configuration and a fully expanded configuration. The stent  300  may be structured to extend across a stricture and to apply a radially outward pressure to the stricture in a lumen to open the lumen and allow for the passage of foods, fluids, air, etc. 
     The stent frame  302  may have a woven structure, fabricated from a number of filaments. In some embodiments, the stent frames  22 ,  30  may be braided with one filament. In other embodiments, the stent frame  302  may be braided with several filaments, as is found, for example, in the WALLFLEX®, WALLSTENT®, and POLYFLEX® stents, made and distributed by Boston Scientific Corp. In another embodiment, the stent frame  302  may be knitted, such as the ULTRAFLEX™ stents made by Boston Scientific Corp. In yet another embodiment, the stent frame  302  may be of a knotted type, such the PRECISION COLONIC™ stents made by Boston Scientific Corp. In still another embodiment, the stent frame  302  may be laser cut, such as the EPIC™ stents made by Boston Scientific Corp. 
     It is contemplated that the stent  300  can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stent  300  to be expanded into shape when accurately positioned within the body. In some instances, the material may be selected to enable the stent  300  to be removed with relative ease as well. For example, the stent  300  can be formed from alloys such as, but not limited to, Nitinol and ELGILOY®. Depending on the material selected for construction, the stent  300  may be self-expanding (i.e., configured to automatically radially expand when unconstrained). In some embodiments, fibers may be used to make the stent  300 , which may be composite fibers, for example, having an outer shell made of Nitinol having a platinum core. It is further contemplated the stent  300  may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some embodiments, the stent  300  may be self-expanding while in other embodiments, the stent  300  may be expand by an expansion device (such as, but not limited to a balloon inserted within the lumen  310  of the stent  300 ). As used herein the term “self-expanding” refers to the tendency of the stent to return to a preprogrammed diameter when unrestrained from an external biasing force (for example, but not limited to a delivery catheter or sheath). The stent  300  may include a one-way valve, such as an elastomeric slit valve or duck bill valve, positioned within the lumen  310  thereof to prevent retrograde flow of gastrointestinal fluids. 
     In some instances, in the radially expanded configuration, the stent  300  may include a first end region  312  proximate the proximal end  304  and a second end region  314  proximate the second end  306 . In some embodiments, the first end region  312  and the second end region  314  may include retention features or anti-migration flared regions (not explicitly shown at the second end region  314 ) having enlarged diameters relative to the intermediate portion  308 . The anti-migration flared regions, which may be positioned adjacent to the first end  304  and the second end  306  of the stent  300 , may be configured to engage an interior portion of the walls of the esophagus, stomach or other body lumen. In some embodiments, the retention features, or flared regions may have a larger diameter than the cylindrical intermediate region  308  of the stent  300  to prevent the stent  300  from migrating once placed in the esophagus, stomach, or other body lumen. It is contemplated that a transition from the cross-sectional area of the intermediate region  308  to the retention features or flared regions may be gradual, sloped, or occur in an abrupt step-wise manner, as desired. In other embodiments, the stent  300  may have a uniform diameter from the proximal end  304  to the distal end  306 . 
     It is contemplated that the stent  300  can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stent  300  to be expanded into shape when accurately positioned within the body. In some instances, the material may be selected to enable the stent  300  to be removed with relative ease as well. For example, the stent  300  can be formed from alloys such as, but not limited to, Nitinol and ELGILOY®. Depending on the material selected for construction, the stent  300  may be self-expanding or require an external force to expand the stent  300 . In some embodiments, composite filaments may be used to make the stent  300 , which may include, for example, an outer shell or cladding made of Nitinol and a core formed of platinum or other radiopaque material. It is further contemplated the stent  300  may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some instances, the filaments of the stent  300 , or portions thereof, may be bioabsorbable or biodegradable, while in other instances the filaments of the stent  300 , or portions thereof, may be biostable. 
     The implant  300  may be may be entirely, substantially or partially, covered with a polymeric covering, such as a coating (not explicitly shown). The covering may be disposed on an inner surface and/or outer surface of the implant  300 , as desired. When so provided a polymeric covering may reduce or eliminate tissue ingrowth and/or reduce food impaction. 
     The implant  300  may further include a retrieval suture  320 . The suture  320  may include a retrieval suture loop  322  which may be configured to be grasped by forceps or other tool during a clinical procedure for stent removal and or repositioning. The suture  320  may be interwoven with the stent frame  302  at intervals along a length of the implant  300  to create a plurality of suture loops  324   a ,  324   b ,  324   c ,  324   d ,  324   e ,  324   f ,  324   g  (collectively,  324 ). Each of the suture loops  324  may extend entirely around the circumference of the stent frame  302 . It is contemplated that the suture loops  324  may be positioned at regular or even intervals throughout the overall length of the implant  300 . However, in other embodiments, the suture loops  324  may be positioned at eccentric or uneven intervals along the length of the implant  300 , as desired. Adjacent suture loops  324  may be connected with a longitudinal length of the suture  320  extending therebetween. For example, adjacent suture loops  324  may be connected with the suture connection links  326   a ,  326   b ,  326   c ,  326   d ,  326   e ,  326   f  (collectively,  326 ) such that actuation of the retrieval suture loop  322  is translated to each of the individual suture loops  324  via the longitudinally extending suture connection links  326  between each successive suture loop  324  along the length of the implant  300 . 
     To collapse the implant  300 , the retrieval suture loop  322 , or the first suture loop  134   a  in the absence of the retrieval suture loop  322 , may be pulled or otherwise actuated in a proximal direction. It is contemplated that the direction of actuation (e.g., proximal or distal) required to actuate the suture  320  may be dependent on the direction in which the suture  320  is interwoven with the stent frame  302 . As the retrieval suture loop  322 , or the first suture loop  134   a  in the absence of the retrieval suture loop  322 , is actuated, the suture loops  324  begin to constrain or reduce the diameter of the implant  300 , as shown in  FIG.  13   , which illustrates a side view of the illustrative implant  300  during suture  320  actuation. In some instances, the connection links  326  may have a length such that the suture loops  324  simultaneously (or approximately simultaneously) constrain the implant  300  along its length. However, this is not required. In some instances, the connection links  326  may have a length such that the suture loops  324  are sequentially actuated. For example, the next sequential suture loop  324  may not be actuated until the slack is removed from the preceding longitudinally extending suture connection link  326  and the suture connection link  326  is drawn taut to apply a force to the next suture loop  324 . Continued actuation of the retrieval suture loop  322  may cause the implant  300  to be further reduced diameter, as shown at  FIG.  14   , which illustrates a side view of the illustrative implant  300  with the implant  300  in a fully constrained configuration. It is contemplated that simultaneous constrainment of the suture loops  324  may reduce the delay time between the actuation of the retrieval suture loop  322  and movement of the implant  300  during repositioning or removal. This may allow the implant  300  to be repositioned and/or removed with minimal impact on a vessel wall. 
     The materials that can be used for the various components of the implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  (and variations, systems or components thereof disclosed herein) and the various elements thereof disclosed herein may include those commonly associated with medical devices. For simplicity purposes, the following discussion makes reference to the implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  (and variations, systems or components disclosed herein). However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other elements, members, components, or devices disclosed herein. 
     The implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material. Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material. 
     As alluded to herein, within the family of commercially available nickel-titanium or nitinol alloys, is a category designated “linear elastic” or “non-super-elastic” which, although may be similar in chemistry to conventional shape memory and super elastic varieties, may exhibit distinct and useful mechanical properties. Linear elastic and/or non-super-elastic nitinol may be distinguished from super elastic nitinol in that the linear elastic and/or non-super-elastic nitinol does not display a substantial “superelastic plateau” or “flag region” in its stress/strain curve like super elastic nitinol does. Instead, in the linear elastic and/or non-super-elastic nitinol, as recoverable strain increases, the stress continues to increase in a substantially linear, or a somewhat, but not necessarily entirely linear relationship until plastic deformation begins or at least in a relationship that is more linear that the super elastic plateau and/or flag region that may be seen with super elastic nitinol. Thus, for the purposes of this disclosure linear elastic and/or non-super-elastic nitinol may also be termed “substantially” linear elastic and/or non-super-elastic nitinol. 
     In some cases, linear elastic and/or non-super-elastic nitinol may also be distinguishable from super elastic nitinol in that linear elastic and/or non-super-elastic nitinol may accept up to about 2-5% strain while remaining substantially elastic (e.g., before plastically deforming) whereas super elastic nitinol may accept up to about 8% strain before plastically deforming. Both of these materials can be distinguished from other linear elastic materials such as stainless steel (that can also can be distinguished based on its composition), which may accept only about 0.2 to 0.44 percent strain before plastically deforming. 
     In some embodiments, the linear elastic and/or non-super-elastic nickel-titanium alloy is an alloy that does not show any martensite/austenite phase changes that are detectable by differential scanning calorimetry (DSC) and dynamic metal thermal analysis (DMTA) analysis over a large temperature range. For example, in some embodiments, there may be no martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about −60 degrees Celsius (° C.) to about 120° C. in the linear elastic and/or non-super-elastic nickel-titanium alloy. The mechanical bending properties of such material may therefore be generally inert to the effect of temperature over this very broad range of temperature. In some embodiments, the mechanical bending properties of the linear elastic and/or non-super-elastic nickel-titanium alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature, for example, in that they do not display a super-elastic plateau and/or flag region. In other words, across a broad temperature range, the linear elastic and/or non-super-elastic nickel-titanium alloy maintains its linear elastic and/or non-super-elastic characteristics and/or properties. 
     In some embodiments, the linear elastic and/or non-super-elastic nickel-titanium alloy may be in the range of about 50 to about 60 weight percent nickel, with the remainder being essentially titanium. In some embodiments, the composition is in the range of about 54 to about 57 weight percent nickel. One example of a suitable nickel-titanium alloy is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Some examples of nickel titanium alloys are disclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which are incorporated herein by reference. Other suitable materials may include ULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available from Toyota). In some other embodiments, a superelastic alloy, for example a superelastic nitinol can be used to achieve desired properties. 
     In at least some embodiments, portions or all of implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are generally understood to be materials which are opaque to RF energy in the wavelength range spanning x-ray to gamma-ray (at thicknesses of &lt;0.005″). These materials are capable of producing a relatively dark image on a fluoroscopy screen relative to the light image that non-radiopaque materials such as tissue produce. This relatively bright image aids the user of implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  to achieve the same result. 
     In some embodiments, a degree of Magnetic Resonance Imaging (MM) compatibility is imparted into implants  10 ,  100 ,  150 ,  200 ,  250 ,  300 . For example, implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (i.e., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an Mill image. The implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  or portions thereof, may also be made from a material that the MM machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, and the like, and others. 
     Some examples of suitable polymers for implants  10 ,  100 ,  150 ,  200 ,  250 ,  300  may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. 
     Those skilled in the art will appreciate that the different embodiments of the implant described here, their mode of operation, etc., are merely representative of the environment in which the present disclosure operates. Accordingly, a variety of alternatively shaped collaborating components may also be used as a substitutive for the purpose of engaging, steering and locating the stent at a desired target site, thus, not limiting the scope of the present disclosure. Further, the disclosed implants may be adequately stretchable, extendable, and retractable, allowing for its flexible deployment. More particularly, the configurations described here may be applicable for other medical applications as well, and accordingly, a variety of other medical devices may be used in combination with the implant. Those medical devices may include biopsy forceps, scissors, lithotripters, dilators, other cautery tools, and the like. 
     Further, while the implant is generally described along with an exemplary rigid and flexible region(s), a variety of other configurations and arrangements may also be contemplated and conceived as well. In addition, the operations, devices, and components, described herein may be equally applicable for other purposes where a component is required to be positioned in places where a leakage needs to be avoided or other treatments are desired. Embodiments of the present disclosure are thus applicable to medical and/or non-medical environments. Further, certain aspects of the aforementioned embodiments may be selectively used in collaboration, or removed, during practice, without departing from the scope of the disclosed embodiments. 
     Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present disclosure as described in the appended claims.