Patent Publication Number: US-2023157853-A1

Title: Stents and methods for managing passage of material through a body lumen

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of the earlier filing date of U.S. patent application Ser. No. 16/925,701, filed on Jul. 10, 2020, which claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/873,241, filed on Jul. 12, 2019, and which applications are incorporated herein by reference in their entireties for all purposes. 
    
    
     FIELD 
     The present disclosure relates to medical stents and, more particularly, to stents and methods for managing passage of material through a body lumen. 
     BACKGROUND 
     Sphincter muscles in the human anatomy perform an important role of sealing and preventing leaks from organs and vessels. Examples of sphincters in the body include a lower esophageal sphincter (LES) and internal/external anal sphincters (IAS/EAS). Complications that effect sphincter function can cause discomfort and embarrassment, thus impairing a patient&#39;s quality of life. 
     One example of sphincter dysfunction, fecal incontinence, is recognized as the inability to control bowel movements, causing unexpected rectum leakage of stool. A challenge for people with this condition is the lack of notification of the imminent bowel movement. Due to the lack of a natural, physical urge or alert to the bowel movement, some people with the condition resort to wearing absorbent undergarments. However, this solution fails to prevent unintentional stool leakage before it occurs. 
     Urinary incontinence is a dysfunction that may occur, for example, during and/or after pregnancy. This unintentional leaking of urine may present a level of discomfort for patients, which may lead to self-esteem and self-confidence issues. 
     Gastroesophageal reflux disease (GERD) is a dysfunction that occurs when the stomach contents can pass the LES, due to muscle weakness and/or inappropriate relaxation. GERD can also be a complication from surgical procedures that effect the sphincter muscle, e.g., peroral endoscopic myotomy (POEM) and Heller myotomy procedures to treat achalasia. 
     SUMMARY 
     The present disclosure in its various embodiments relates generally to stents and methods for managing sphincter dysfunction. In one or more embodiments, a medical stent may include a stent body defined by a hollow tubular elongate structure extending along a central axis, the stent body including a first portion and a second portion. The medical stent may further include a control region between the first and second portions, wherein in a first configuration the hollow tubular elongate structure of the control region is in a closed, twisted configuration, and wherein in a second configuration the hollow tubular elongate structure of the control region is in an open, expanded configuration. In some embodiments, the control region may be connected at a first end to the first portion and at a second end to the second portion. In some embodiments, the medical stent may further include a covering formed along the hollow tubular elongate structure. In some embodiments, the covering may be made from silicone. In some embodiments, in the first configuration, the second portion may be rotated more than 180 degrees relative to the first portion. In some embodiments, in the first configuration the hollow tubular elongate structure of the control region is rotated about the central axis by approximately 360 degrees. In some embodiments, the control region may include a first constriction point. In some embodiments, the control region may include a second constriction point adjacent the first constriction point, wherein the hollow tubular elongate structure at each of the first and second constriction points is substantially closed. In some embodiments, at the first constriction point, the hollow tubular elongate structure of the control region may be rotated in a first direction about the central axis by 180 degrees, and at the second constriction point, the hollow tubular elongate structure of the control region may be rotated in a second direction about the central axis by 180 degrees. In some embodiments, the stent body may further include a lumen anchoring flange extending from at least one of: the first portion, and the second portion. 
     In one or more embodiments, a self-expanding metal stent may include a stent body defined by a hollow tubular elongate structure extending along a central axis, the stent body including a first portion adjacent a second portion. The stent body may further include a lumen anchoring flange extending from at least one of: the first portion, and the second portion. The self-expanding metal stent may further include a control region between the first portion and the second portion, wherein in a first configuration the hollow tubular elongate structure of the control region is twisted about the central axis to form a barrier within the stent body, and wherein in a second configuration the hollow tubular elongate structure of the control region is untwisted to provide a passageway between the first portion and the second portion. In some embodiments, the first portion includes a first open end and the second portion includes a second open end. In some embodiments, the self-expanding metal stent may further include a covering formed along the hollow tubular elongate structure. In some embodiments, in the second configuration, the second portion is rotated at least 180 degrees relative to the first section. In some embodiments, the barrier is formed at a first constriction point in the control region. In some embodiments, the hollow tubular elongate structure may include a second constriction point in the control region, wherein the hollow tubular elongate structure at the first constriction point is rotated about the central axis in a first direction, and wherein the hollow tubular elongate structure at the second constriction point is rotated about the central axis in a second direction. 
     In one or more embodiments, a method may include inserting a stent body within a gastrointestinal tract of a patient, wherein the stent body comprises a hollow tubular elongate structure extending along a central axis, and wherein the stent body comprises a first portion adjacent a second portion. The method may further include providing a barrier between the first portion and the second portion by twisting, about the central axis, the hollow tubular elongate structure of a control region, wherein the barrier is operable to untwist in response to a force upon the hollow tubular elongate structure of the control region to provide a passageway between the first portion and the second portion. In some embodiments, the method may further include forming one or more constriction points in the hollow tubular elongate structure of the control region, and thermally treating the one or more constriction points. In some embodiments, the method may further include securing the stent body within the gastrointestinal tract using a lumen anchoring flange extending from at least one of: the first portion, and the second portion. In some embodiments, the method may further include forming a covering over the hollow tubular elongate structure. 
     Various one or more of the features summarized above may be interchanged, exchanged, combined or substituted with or for other features summarized above, for use in connection with the medical systems and methods summarized above, and with respect to the embodiments described in greater detail below and embodiments otherwise within the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting embodiments of the present disclosure are described by way of example with reference to the accompanying figures, which are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure. Furthermore, some of the figures include cross-sectional views in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines or features otherwise visible in a “true” cross-sectional view, for illustrative clarity. In the figures: 
         FIG.  1    is a side cross-sectional view of a stent according to embodiments of the present disclosure; 
         FIG.  2    is a side perspective view of a control region of the stent of  FIG.  1    according to embodiments of the present disclosure; 
         FIGS.  3 - 4    depict the stent of  FIG.  1    positioned within a gastrointestinal tract according to embodiments of the present disclosure; 
         FIG.  5    is a side cross-sectional view of a stent according to embodiments of the present disclosure; 
         FIG.  6    is a side perspective view of a control region of the stent of  FIG.  5    according to embodiments of the present disclosure; 
         FIG.  7    is a flow diagram of a method according to embodiments of the present disclosure; and 
         FIG.  8    is a side perspective view of a stent according to embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is not limited to the particular embodiments described herein. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting beyond the scope of the appended claims. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. 
     Embodiments herein are directed to self-expanding stents implantable within a patient&#39;s body, the stent functioning as a one-way valve for the controlled passage of material through a gastrointestinal (GI) tract of the patient. For example, the stent is configured to allow passage of stool or other material in one direction once enough pressure has built up to cause the stent to change from a closed, twisted configuration to an open, expanded configuration. In some embodiments, the stent includes a hollow tubular elongate structure extending along a central axis, the hollow tubular elongate structure including a first portion and a second portion. A control region is disposed between the first and second portions, wherein the control region may twist and untwist to regulate delivery of the stool through an interior of the stent. 
     As will be described in greater detail herein, the stent may be placed in the GI tract of a patient, such as in a descending colon, to control unintentional flow of loose stool through the rectum and anus. The patient may receive a prompt, via abdominal sensation, as back pressure from the stent increases, thus allowing the patient a period of time before the stent opens. The control region of the stent may then untwist, allowing the normal flow of stool therethrough. In some embodiments, the stent is flexible, generally conforming to the profile of the stool. As a result, the control region of the stent may expand only by an amount corresponding to dimensions of the stool, thus allowing the stool to pass through the stent in a controlled manner. Once the stool has passed through the stent, the control region may return to the closed, twisted configuration. 
     Although described primarily herein as an approach for treating fecal incontinence, embodiments herein are not limited in this context. For example, the stents and methods of the present disclosure can be used treat gastroesophageal reflux disease (GERD) and/or urinary incontinence, among other types of sphincter dysfunction. 
     Turning now to  FIG.  1   , a stent  100  according to embodiments of the disclosure will be described in greater detail. As shown, the stent  100  may be a self-expanding metal stent (SEMS) positionable within a GI tract of a patient. The stent  100  may have a stent body  102  defined by a hollow tubular elongate structure  104  extending along a central axis  106 , between a first end  110  and a second end  112 . In some embodiments, each of the first end  110  and the second end  112  may be open ends to allow stool within the GI tract to enter and exit through the stent  100  in a controlled manner. As shown, the stent body  102  may include a first portion  115  and a second portion  116  connected to one another at a control region  118 . In some embodiments, the hollow tubular elongate structure  104  may be formed of a hollow tubular elongate structure, although other embodiments may be formed at least partially of plastic, composite, metal, or combinations thereof. As will be described in greater detail below, the control region  118  may operate between a first configuration in which the hollow tubular elongate structure  104  of the control region  118  is in a closed, twisted form, and a second configuration in which the hollow tubular elongate structure  104  of the control region  118  is in an open, expanded form. 
     In some embodiments, the stent  100  may have a constant or non-constant diameter along the central axis  106 . For example, as shown, the first portion  115  and the second portion  116  may narrow towards the control region  118 . In some embodiments, a maximum diameter of the first portion  115  may be the same or different than a maximum diameter of the second portion  116 . Furthermore, in various embodiments, a length of the first portion  115 , as measured from the control region  118  to the first end  110 , may be the same or different than a length of the second portion  116 , as measured from the control region  118  to the second end  112 . Embodiments herein are not limited in this context. 
     In some embodiments, the hollow tubular elongate structure  104  of the stent body  102  may include a plurality of frame members  120  surrounding an interior of the stent  100 . As shown, the plurality of frame members  120  may be connected to one another to define a plurality of open cells  124  in the stent body  102 . However, embodiments herein are not limited to any particular number of frame members  120  and/or configuration of the plurality of frame members  120  and the plurality of open cells  124 . In embodiments, the stent body  102  may be formed of one or more wires in a predetermined weave pattern, thereby defining a plurality of interstices, or apertures in the weave pattern. 
     The plurality of frame members  120  may be made of an elastic material, such as shape-memory wire, stainless steel, nitinol, cobalt alloys, and/or other materials. Although non-limiting, the hollow tubular elongate structure  104  may be laser cut, woven, braided, bent, twisted, knotted, molded, tied, and/or wrapped from one or several filaments into a desired configuration. In some embodiments, the control region  118  may be twisted and then thermally treated to “heat-set” the hollow tubular elongate structure  104  into the configuration shown. In some embodiments, a thickness of one or more of the plurality of frame members  120  may vary as well. For example, a wire diameter in the control region  118  may vary relative other wire diameters of the hollow tubular elongate structure  104  in the first and/or second portions  115 ,  116  to alter a pressure threshold at which the hollow tubular elongate structure  104  of the control region  118  changes between the open and closed configurations. 
     The stent  100  may further include a covering  126  over at least a portion of the hollow tubular elongate structure  104 . In non-limiting embodiments, the covering  126  may include one or more polymeric coatings, such as polytetrafluoroethylene (PTFE), expanded PTFE (ePTFE), polyurethane, fluorinated ethylene propylene (FEP), silicone, polyurethane-acrylate, silicone-acrylate, urethane-silicone, and the like. Combinations of these polymers may also be used. Furthermore, different portions of the hollow tubular elongate structure  104  may also be coated with different polymers. Still furthermore, depending on the application, one or more sections of the covering  126  may be, for example, slightly porous, highly porous, or non-porous. 
     The covering  126  may be formed along inner and/or outer surfaces of the hollow tubular elongate structure  104 . As shown, the covering  126  may extend across each of the plurality of open cells  124  in the stent body  102 . In some embodiments, the covering  126  may be formed over just one or more portions of the stent body  102 . For example, to allow for tissue ingrowth with the stent  100 , the covering  126  may not be formed over a lumen anchoring flange  128  extending from the first end  110  and/or the second end  112 . The lumen anchoring flange  128  may be a section of the hollow tubular elongate structure  104  provided to prevent migration of the stent  100  within the GI tract, while still allowing the stent  100  to be later removed. In various embodiments, the covering  126  may be applied to the hollow tubular elongate structure  104  before and/or after the control region  118  is thermally treated. It is understood that the lumen anchoring flange  128  may be included on one of the first and second ends  110 ,  112  of the stent body  102 , or on both of the first and second ends  110 ,  112 . In some embodiments, the stent body  102  may not include any lumen anchoring flange  128 . 
     Turning now to  FIG.  2   , the control region  118  of the stent  100  according to embodiments of the present disclosure will be described in greater detail. As shown, the control region  118  may include one or more constriction points  130  of the hollow tubular elongate structure  104 . At the constriction point  130 , the hollow tubular elongate structure  104  may be twisted about the central axis  106  to form a barrier  132  between the first and second portions  115 ,  116 . In some embodiments, the second portion  116  may be rotated about the central axis  106 , for example, by approximately 360 degrees. In other embodiments, the second portion  116  may be rotated about the central axis  106  by 90, 180, 270-720 degrees, etc. The barrier  132  may prevent matter (e.g., stool) from being delivered from an interior of the first portion  115  to an interior of the second portion  116 . In some embodiments, the hollow tubular elongate structure  104  of the control region  118  may be twisted and then heat-set to establish the twisted configuration of the barrier  132 . 
     The hollow tubular elongate structure  104  at the constriction point  130  may remain closed until a threshold pressure at the constriction point  130  causes the hollow tubular elongate structure  104  to untwist and expand radially away from the central axis  106 . It will be appreciated that various properties of the hollow tubular elongate structure  104  may be varied to increase or decrease the threshold pressure necessary to open the hollow tubular elongate structure  104  at the constriction point  130 . For example, a thickness of the plurality of frame members  120  in the control region  118  may be greater than a thickness of the plurality of frame members  120  of the first portion  115  and/or the second portion  116 . Alternatively, or additionally, an amount of twist or rotation at the constriction point  130  may be altered. Furthermore, a stiffness of the hollow tubular elongate structure  104  at the constriction point  130  may be greater or lesser than a stiffness of the first portion  115  and/or the second portion  116 . Thermal properties of the heat-set process may also be modified to alter performance of the hollow tubular elongate structure  104  at the constriction point  130 . 
     Turning now to  FIGS.  3 - 4   , operation of the stent  100  will be described in greater detail. As shown, the stent  100  may be inserted into a GI tract  140  of a patient, for example, between a descending colon  141  and a sigmoid colon  142  of a large intestine. The stent  100  may be delivered and deployed using any variety of deployment devices. For example, the stent  100  may be delivered using a coaxial delivery system including an inner and outer member assembly. The stent  100  may be constrained within an outer tube of the outer member assembly, and then deployed by pulling the outer e-tube back to expose and release the stent  100 . In a deployed configuration, the first and second portions  115 ,  116  may expand to contact the inner surface of the body lumen, e.g., the GI tract. 
     As shown in  FIG.  3   , the stent  100  may include the barrier  132  at the constriction point  130 , between the first portion  115  and the second portion  116 . Stool  144  delivered from the descending colon  141  may enter the first portion  115  through the first end  110  of the stent  100 , which is open. Because the barrier  132  is closed, the stool  144  is prevented from continuing into the second portion  116 . Once enough of the stool  144  has built up within the first portion  115 , the patient may receive a prompt, via abdominal sensation, indicating an imminent passage of the stool  144 . During this initial period of time, the control region  118  of the stent  100  may remain in the closed configuration shown in  FIG.  3    to provide the patient with an opportunity to reach a bathroom. 
     As shown in  FIG.  4   , the control region  118  of the stent  100  may then untwist and expand in response to a force (e.g., pressure as a result of the stool  144 ) upon the hollow tubular elongate structure  104  of the control region  118 , thus providing a passageway  145  between the first portion  115  and the second portion  116 . The first end  110  of the stent  100  may be fixed in place within the GI tract  140 . In some embodiments, untwisting in the control region  118  may cause the second portion  116  to rotate (e.g., about the central axis  106  of  FIG.  1   ), for example, more than 180 degrees relative to the first portion  115 . In other embodiments, the second portion  116  may rotate approximately 360 degrees relative to the first portion  115  when in the second, open configuration. The stool  144  may then be permitted to travel through the hollow tubular elongate body down into the second portion  116  and out the open second end  112  of the stent  100  for expulsion through a rectum  146  and anus  148  of the GI tract  140 . In some embodiments, the control region  118  may generally conform to the profile of the stool  144 , opening only an amount to allow the stool  144  to pass therethrough, in a controlled manner. Once the stool  144  exits the second end  112  of the stent  100 , which is open, the second portion  116  and the control region  118  may again twist, returning to the first, closed configuration. 
     Turning now to  FIGS.  5 - 6   , a stent  200  according to embodiments of the disclosure will be described in greater detail. As shown, the stent  200  includes many of the features previously described in relation to the stent  100  of  FIGS.  1 - 4   . Accordingly, just certain aspects of the stent  200  will hereinafter be described for the sake of brevity. 
     As shown, the stent  200  may have a stent body  202  defined by a hollow tubular elongate structure  204  extending along a central axis  206 , between a first end  210  and a second end  212 . In some embodiments, the first end  210  and the second end  212  may be open. As shown, the stent body  202  may include a first portion  215  and a second portion  216  connected to one another at a control region  218 . The stent body  202  may further include a first lumen anchoring flange  228  extending from the first end  210  and a second lumen anchoring flange  229  extending from the second end  212 . The first and second lumen anchoring flanges  228 ,  229  may be provided to prevent migration of the stent  200  within a GI tract, while still allowing the stent  200  to be later removed. For example, the first and second lumen anchoring flanges may be uncovered to allow for tissue ingrowth therewith. As will be described in greater detail below, the control region  218  may operate between a first configuration in which the hollow tubular elongate structure  204  of the control region  218  is in a closed, twisted form, and a second configuration in which the hollow tubular elongate structure  204  of the control region  218  is in an open, untwisted form. 
     As shown, the hollow tubular elongate structure  204  of the stent body  202  may include a plurality of frame members  220  surrounding an interior of the stent  200 . The plurality of frame members  220  may be made of an elastic material, such as shape-memory wire, stainless steel, Nitinol, cobalt alloys, and/or other materials. Although non-limiting, the hollow tubular elongate structure  204  may be laser cut, woven, braided, bent, twisted, knotted, molded, tied, and/or wrapped from one or several filaments into a desired configuration. In some embodiments, the control region  218  may be twisted and then thermally treated to heat-set the hollow tubular elongate structure  204  into the configuration shown. In some embodiments, a thickness of one or more of the plurality of frame members  220  may vary. For example, a wire diameter of one or more of the plurality of frame members  220  in the control region  218  may vary relative to other wire diameters of the hollow tubular elongate structure  204  to modify the pressure at which the hollow tubular elongate structure  204  of the control region  218  changes between the open and closed configurations. 
     As shown, the stent  200  may include a covering  226  (e.g., silicone) over the hollow tubular elongate structure  204 . The covering  226  may be formed along inner and/or outer surfaces of the hollow tubular elongate structure. In some embodiments, the covering  226  may be formed over just one or more portions of the stent body  202 . For example, to allow for tissue ingrowth with the stent  200 , the covering  226  may not be formed over the first lumen anchoring flange  228  and the second lumen anchoring flange  229 . In various embodiments, the covering  226  may be applied to the hollow tubular elongate structure  204  before and/or after the control region  218  is thermally treated. 
     Turning now to  FIG.  6   , the control region  218  of the stent  200  according to embodiments of the present disclosure will be described in greater detail. As shown, the control region  218  may include multiple constriction points  230 A- 230 B along the hollow tubular elongate structure  204 . At each constriction point  230 A- 230 B, the hollow tubular elongate structure  204  may be twisted about the central axis  206  to form respective barriers  232 A- 232 B. The barriers  232 A- 232 B may prevent matter (e.g., stool) from being delivered from an interior of the first portion  215  to an interior of the second portion  216 . In some embodiments, the hollow tubular elongate structure  204  of the control region  218  is twisted and then heat-set to a desired shape to form the barriers  232 A- 232 B at each respective constriction point  230 A- 230 B. 
     The double twist configuration provided by the multiple constriction points  230 A- 230 B in the control region  218  allows all untwisting/rotation to occur in the control region  218 . Rotation of the first or second portion  215 ,  216 , e.g., at the first or second end  210 ,  212 , may be eliminated or reduced, thus allowing for the second lumen anchoring flange  229  ( FIG.  5   ) to be secured in place within a GI tract of the patient. The first lumen anchoring flange  228  ( FIG.  5   ) may also be secured in place within the GI tract of the patient. In some embodiments, the stent  200  can be heat-set with a twist (e.g., 180-360 degrees) in a first direction about the central axis  206  to form construction point  230 A, followed by another 180-degree twist (e.g., 180-360 degrees) in an opposite direction about the central axis  206  to form constriction point  230 B. 
     During operation, stool may enter the first portion  215  of the stent  200  through the first end  210 . Because the barriers  232  are closed, the stool is initially prevented from continuing into the second portion  216 . Said differently, the hollow tubular elongate structure  204  at the constriction points  230 A- 230 B may remain in a closed configuration until a threshold pressure in the control region  218  causes the barriers  232 A- 232 B of the hollow tubular elongate structure  204  to untwist and open. It will be appreciated that various properties of the hollow tubular elongate structure  204  and/or the thermal treatment may be varied to increase or decrease the threshold pressure required to open the hollow tubular elongate structure  204  at the constriction points  230 A- 230 B. Once enough stool has built up within the first portion  215 , the patient may receive a prompt, via abdominal sensation, indicating an imminent passage of the stool. During this time, the control region  218  of the stent  200  may remain in the closed configuration shown. 
     The control region  218  of the stent  200  may then untwist and expand in response to a force upon the hollow tubular elongate structure  204  of the control region  218 , thus providing a passageway between the first portion  215  and the second portion  216 . For example, the hollow tubular elongate structure  204  at both constriction points  230 A- 230 B may untwist, in opposite directions, permitting the stool to travel through the hollow tubular elongate body and down into the second portion  216  and out the second end  212  of the stent  200 . In some embodiments, the control region  218  may generally conform to the profile of the stool, opening only an adequate amount to allow the stool to pass therethrough in a controlled manner. Once the stool exits the stent  200 , the control region  218  may return to the first, closed configuration wherein the hollow tubular elongate structure  204  at both constriction points  230 A- 230 B is twisted about the central axis  206 . 
       FIG.  7    is a flow diagram of a method  300  according to embodiments of the present disclosure. At block  301 , the method  300  may include inserting a stent body within a gastrointestinal tract of a patient, wherein the stent body includes a hollow tubular elongate structure extending along a central axis, and wherein the hollow tubular elongate structure includes a first portion adjacent a second portion. In some embodiments, the stent body is inserted within a colon of the patient. In some embodiments, the stent body is secured within the GI tract using a lumen anchoring flange extending from at least one of the first portion and the second portion. In some embodiments, mucosal abrasion of the insertion site within the GI tract is used to encourage tissue ingrowth in the anchoring flange or another region or rim of the stent body (preferably at an end of the stent body) to mitigate migration of the stent body. In some embodiments, a covering is formed over the hollow tubular elongate structure of the stent body. In some embodiments, the covering is not provided over the anchoring flange (or other region or rim of the stent intended for mitigating migration of the stent body). 
     At block  303 , the method  300  may include providing a barrier between the first portion and the second portion by twisting, about the central axis, the hollow tubular elongate structure of a control region. In some embodiments, the barrier is operable to untwist in response to a force upon the hollow tubular elongate structure of the control region to provide a passageway between the first portion and the second portion. The force may be provided from a buildup of stool against the barrier. In some embodiments, providing a barrier includes forming one or more constriction points in the hollow tubular elongate structure of the control region, and thermally treating the one or more constriction points. 
     At block  305 , the method  300  includes receiving the force upon the hollow tubular elongate structure of the control region to cause the barrier to untwist and open. In some embodiments, various properties of the hollow tubular elongate structure in the control region may be varied to increase or decrease a threshold pressure necessary to open the barrier. In some embodiments, a thickness of one or more frame members in the control region may be greater than a thickness of one or more frame members of the first portion and/or the second portion. In some embodiments, an amount of twist or rotation of the barrier may be altered. Furthermore, a stiffness of the hollow tubular elongate structure in the control region may be greater or lesser than a stiffness of the hollow tubular elongate structure of first portion and/or the second portion. Still furthermore, in some embodiments, thermal properties of a heat-set process to form the barrier may be modified to alter performance of the hollow tubular elongate structure of the barrier. 
     Turning now to  FIG.  8   , a stent  400  according to embodiments of the disclosure will be described in greater detail. As shown, the stent  400  includes many of the features previously described in relation to the stents  100  and  200  described above. Accordingly, just certain aspects of the stent  400  will hereinafter be described for the sake of brevity. 
     As shown, the stent  400  may have a stent body  402  defined by a hollow tubular elongate structure  404  extending between a first end  410  and a second end  412 . In some embodiments, the first end  410  and the second end  412  may be open to allow stool to enter and exit the stent body  402 . As shown, the stent body  402  may include a first portion  415  and a second portion  416  connected to one another at a control region  418 . In this embodiment, the stent body  402  may be bent such that the first portion  415  may generally extend within a sigmoid colon of a patient&#39;s GI tract, while the second portion  416  may be positioned within the patient&#39;s rectum. As shown, the first end  410  and the second end  412  are capable of being proximately positioned such that the first portion  415  and the second portion  416  extend generally parallel to one another. When inserted within the patent, however, the first and second portions  415 ,  416  may extend generally perpendicular to or colinear with each other. 
     As shown, the hollow tubular elongate structure  404  of the stent body  402  may include a plurality of frame members  420  surrounding an interior of the stent  400 . In some embodiments, the control region  418  may be twisted and then thermally treated to heat-set the hollow tubular elongate structure  404 . In some embodiments, the stent  400  may include a covering (not shown), such as a layer of silicone, formed over the hollow tubular elongate structure  404 . 
     Similar to embodiments described above, the control region  418  may operate between a first configuration in which the hollow tubular elongate structure  404  of the control region  418  is in a closed, twisted form, and a second configuration in which the hollow tubular elongate structure  404  of the control region  418  is in an open, expanded form. In the first configuration, a barrier  432  may be formed at a constriction point  430 . In the second configuration, stool may pass through the stent  400 , exiting through the second end  412 . 
     In sum, embodiments herein provide a coated stent including a twisted, shape memory control region operable to control the movement of feces and stop the flow of loose stools through to the rectum and anus. Patient discomfort and quality of life can therefore be improved using the stents and methods disclosed herein. 
     As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used herein, specify the presence of stated features, regions, steps elements and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and/or groups thereof. 
     Furthermore, the terms “substantial” or “substantially,” as well as the terms “approximate” or “approximately,” can be used interchangeably in some embodiments, and can be described using any relative measures acceptable by one of skill. For example, these terms can serve as a comparison to a reference parameter, to indicate a deviation that will still provide the intended function. Although non-limiting, the deviation from the reference parameter can be, for example, in an amount of less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, and so on. 
     The phrases “at least one”, “one or more”, and “and/or”, as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
     All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of this disclosure. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. 
     Furthermore, identification references (e.g., primary, secondary, first, second, third, fourth, etc.) are not intended to connote importance or priority, but are used to distinguish one feature from another. The drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary. 
     Although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combinations of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description. Thus, the scope of various embodiments includes any other applications in which the above compositions, structures, and methods are used. 
     Still furthermore, although the illustrative method  300  is described above as a series of acts or events, the present disclosure is not limited by the illustrated ordering of such acts or events unless specifically stated. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein, in accordance with the disclosure. In addition, not all illustrated acts or events may be required to implement a methodology in accordance with the present disclosure. 
     Although the subject matter has been described in language specific to structural components, features, and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific components, features, and/or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.