Abstract:
An endoscopic stent for implantation in a patient after sleeve gastrectomy or biliopancreatic diversion with duodenal switch or biliopancreatic diversion with duodenal switch comprising a stent portion, the stent portion comprising a proximal end portion, the proximal end portion defined by a length of about 50 mm to about 200 mm, an enlarged middle portion, a middle portion having an enlarged diameter relative to the proximal end portion and the distal end portion and defined by a length of about 20 mm to about 80 mm, and a distal end portion and a polymeric sleeve portion engaged to and extending distally from the distal end portion of the stent.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/017,595 filed Jun. 26, 2014, the content of which is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates valve devices and methods for the prevention of bile reflux for bariatric stents. 
     Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. Body mass index (BMI), a measurement which compares weight and height, defines people as overweight (pre-obese) when their BMI is between 25 kg/m 2  and 30 kg/m 2 , and obese when it is greater than 30 kg/m 2 . Obesity is most commonly caused by a combination of excessive dietary calories, lack of physical activity, and genetic susceptibility. On average, obesity reduces life expectancy by six to seven years. Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, breathing difficulties during sleep, certain types of cancer, and osteoarthritis. Obesity is the second leading preventable cause of death worldwide, with increasing prevalence in adults and children, and authorities view it as one of the most serious public health problems of the 21st century. The WHO estimated in 2005 that at least 400 million adults (9.8%) worldwide were obese. According to a CDC report, 34% of adults and 17% of children in the United States were obese in 2007-2008. Obesity has been estimated to cause up to 365,000 deaths per year in the United States. 
     Bariatric (or weight loss) surgeries are surgical treatments for treating severe obesity (BMI greater than 40 kg/m 2  or BMI greater than 35 kg/m 2 ) with a comorbidity. The most common bariatric surgery is Roux-en-Y Gastric Bypass (RYGBP) ( FIG. 1 ), in which a small gastric pouch and an alimentary limb (Roux limb) are created and anastomosed to one another and to the patient&#39;s jejunum, bypassing part of the small intestine. Other bariatric surgeries, as shown in  FIG. 2 , may involve removal of a portion of the stomach (sleeve gastrectomy or biliopancreatic diversion with duodenal switch or biliopancreatic diversion with duodenal switch). In biliopancreatic diversion with duodenal switch, about 80 percent of the stomach is removed, forming a thin sleeve-like stomach. The valve that releases food to the small intestine remains (pylorus) along with a limited portion of the small intestine that normally connects to the stomach (duodenum). The surgery bypasses the majority of the intestine by connecting the end portion of the intestine to the duodenum near the stomach (biliopancreatic diversion). This weight-loss surgery is effective but has more risks, such as malnutrition and vitamin deficiencies, and requires close monitoring. It is generally used for people who have a body mass index greater than 50 kg/m 2 . About 150,000 patients undergo bariatric surgery each year. Long-term studies show the procedures cause significant long-term loss of weight, recovery from diabetes, improvement in cardiovascular risk factors, and a reduction in mortality of 23% to 40%. 
     It is reported that post-operative leaks occur in about 2% to 3% of bariatric surgery cases, but the real number may be higher due to underreporting. For RYGBP, leaks mostly occur along the stapling line of the gastric pouch and at the gastrojejunal anastomosis. However, leaks can also occur along the Z line between the esophagus and the stomach. Leaks are one of the most dreaded complications after bariatric surgery and are associated with increased morbidity and mortality. Leaks can be treated with several modalities, including site drainage with parenteral nutrition and bowel rest, various endoscopic methods (esophageal stents, clips, glue, sutures), and a second bariatric surgery. These treatment modalities all have drawbacks. 
     Esophageal stents have been successfully used to treat leaks after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. These stents are prone to migration, however, because their shape is not adapted to the modified stomach geometry after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. Two stents are often employed because existing stents are simply too short for a successful treatment. 
     For sleeve gastrectomy or biliopancreatic diversion with duodenal switch, most of the leaks occur in the upper part (the proximal third) of the sleeve. This occurs because the upper part is less accessible during surgery and more difficult to staple. 
     In a majority of cases where leakage occurs, there is a stricture in the incisura region of the stomach that creates an increase in pressure in the upper part of the sleeve.  FIG. 3  is included as a representation of the stomach geometry prior to sleeve gastrectomy or biliopancreatic diversion with duodenal switch and  FIG. 4  is included as a representation of the stomach geometry after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. 
     SUMMARY 
     In one aspect, the present disclosure relates to an endoscopic stent for implantation in a patient after sleeve gastrectomy or biliopancreatic diversion with duodenal switch or biliopancreatic diversion with duodenal switch comprising a stent portion, the stent portion comprising a proximal end portion and defined by a length of about 50 mm to about 200 mm, preferably about 120 mm to about 180 mm with a diameter of about 10 mm to about 30 mm, the proximal end portion defined by a length of about 100 mm to about 200 mm, an enlarged middle portion, the enlarged middle portion having an increased diameter of about 5 mm to about 60 mm and having a length of about 20 mm to about 80 mm, preferably about 30 mm to about 60 mm that is greater than the diameter of the proximal end portion and the distal end portion having a length of about 30 mm to about 300 mm, preferably 30 mm to about 100 mm, more preferably about 40 mm to about 80 mm and a diameter of about 5 mm to about 30 mm, and a distal end portion and a polymeric sleeve portion engaged to the distal end portion of the stent portion and extending distally therefrom. 
     The endoscopic stent may have the distal end portion defined by a length of 0 mm to about 100 mm, and preferably about 50 mm to about 100 mm. 
     The endoscopic stent may have the proximal end of the proximal end portion comprising a flare, the distal end of the distal end portion comprises a fare, or both. 
     The endoscopic stent wherein the sleeve portion is defined by a length of about 200 mm to about 350 mm. 
     The endoscopic stent may have a polymeric sleeve portion that is elastomeric. 
     The endoscopic stent may have a polymeric sleeve that comprises silicone. The endoscopic stent may be braided, woven or laser cut. 
     The endoscopic stent may have the stent portion comprising nickel-titanium alloy, cobalt-chromium-nickel alloy, cobalt-chromium alloy, or stainless steel. 
     The endoscopic stent may have the stent portion comprising a cover. 
     The endoscopic sleeve portion may have the enlarged central portion of the stent portion uniformly shaped. In another aspect, the present disclosure relates to an endoscopic stent for implantation in a patient after sleeve gastrectomy or biliopancreatic diversion with duodenal switch comprising a stent portion, the stent portion comprising a proximal end portion, the proximal end portion defined by a length of about 100 mm to about 200 mm, an enlarged middle portion, a middle portion having an enlarged diameter with an increase in the diameter of about 5 mm to about 40 mm relative to the proximal end portion and the distal end portion and defined by a length of about 40 mm to about 80 mm, and a distal end portion, the distal end portion defined by a length of about 50 mm to about 100 mm, and wherein at least a portion of the distal end portion of the stent comprises a device that is configured to open and close. 
     The endoscopic stent may have the proximal end portion, the distal end portion, or both, comprising a flare, the flare comprising an increased diameter of about 2 mm to about 10 mm relative to the proximal end portion and the distal end portion. 
     The endoscopic stent may have the device being a one-way valve disposed within the distal end portion between the enlarged middle portion and a distal end of the endoscopic stent. 
     The endoscopic stent may have the one-way valve comprising a single cusp or multiple cusps. 
     The endoscopic stent may have the one-way valve being tricuspid. 
     The endoscopic stent may be woven, braided or laser cut. 
     The endoscopic stent may have the device being an elastomeric band disposed on an outer surface of the distal end portion at a distal end of the enlarged middle portion. 
     The endoscopic stent may have the distal end portion of the endoscopic stent comprising a continuous wall configuration. 
     The endoscopic stent may have at least a portion of the distal end portion comprising reduced radial strength. 
     In another aspect, the present disclosure relates to an endoscopic stent for implantation in a patient after sleeve gastrectomy or biliopancreatic diversion with duodenal switch comprising a stent portion, the stent portion comprising a flared proximal end portion, an enlarged middle portion and a distal end portion, the stent configured so that the flared proximal end portion is in a distal portion of the esophagus and the enlarged middle portion is disposed within a central portion of the stomach and a polymeric sleeve portion engaged to the distal end portion of the stent portion of the stent portion and extending distally therefrom. 
     The endoscopic stent may have the distal end of the distal end portion flared. 
     The endoscopic stent may have distal end portion defined by a length of slightly greater than 0 mm to about 100 mm and the polymeric sleeve portion is defined by a length of about 200 mm to about 350 mm. 
     In another aspect, the present disclosure relates to a method of making an endoscopic stent, the stent comprising a stent portion and a sleeve portion comprising the steps of providing a mandrel defined by a length of about 150 mm to about 700 mm, preferably about 250 mm to about 700 mm, braiding the stent portion on the mandrel, the stent portion comprising a proximal end portion, the proximal end portion defined by a length of about 50 mm to about 200 mm, preferably about 100 mm to about 200 mm, an enlarged middle portion, a middle portion having an enlarged diameter and defined by a length of about 20 mm to about 80 mm, preferably about 40 mm to about 80 mm, and a distal end portion, coating the stent portion to provide a covering and coating a portion of the mandrel extending beyond the stent portion to provide the sleeve portion of the stent, the sleeve portion defined by a length of about 50 mm to about 350 mm, preferably about 100 mm to about 350 mm, and most preferably about 200 mm to about 350 mm, the sleeve is an extension of the stent coating. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of portions of an alimentary canal after a Roux-en-Y procedure. 
         FIG. 2  is a schematic view of portions of an alimentary canal after a biliopancreatic diversion with duodenal switch procedure. 
         FIG. 3  is a schematic view of the geometry of the stomach prior to sleeve gastrectomy or biliopancreatic diversion with duodenal switch. 
         FIG. 4  is a schematic view of the modified geometry of the stomach after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. 
         FIG. 5  is a partial view of one embodiment of a stent according to the disclosure for use after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. 
         FIG. 6  illustrates a stent which is similar to the embodiment shown in  FIG. 5 . 
         FIG. 7  is a schematic view illustrating a stent similar to that shown in  FIG. 5  wherein the stent is shown extending through the stomach, the pylorus and into the duodenum. 
         FIG. 8  illustrates another embodiment of a stent, according to the disclosure. 
         FIG. 9  is a schematic view illustrating a stent similar to that shown in  FIG. 8  wherein the distal end of the stent stops in the stomach before the pylorus. 
         FIG. 10  illustrates another embodiment of a stent having a one way valve disposed therein. 
         FIG. 11  illustrates one embodiment of a valve that may be used in accordance with the stent shown in  FIG. 10 . 
         FIG. 12  illustrates an alternative embodiment of a stent, according to the disclosure. 
         FIG. 13  illustrates another alternative embodiment of a stent, according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     While embodiments of the present disclosure may take many forms, there are described in detail herein specific embodiments of the present disclosure. This description is an exemplification of the principles of the present disclosure and is not intended to limit the disclosure to the particular embodiments illustrated. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure. Those skilled in the art will recognize that the dimensions and materials discussed herein are merely exemplary and are not intended to limit the scope of the present disclosure. 
     In some embodiments, the present disclosure relates generally to a stent having a bulge or enlarged middle portion where the bulge is designed to adapt to the antrum pouch created during sleeve gastrectomy or biliopancreatic diversion with duodenal switch (SG) surgery. The role of the bulge is to prevent downwards and/or upwards stent migration and close/insulate any leaks that may occur. The present disclosure is discussed in more detail with respect to the figures below. 
     In some embodiments, the stent includes a sleeve that extends past the distal end of the stent into the duodenum and past the common bile duct to prevent reflux. 
     Turning now to the figures,  FIG. 5  is a partial side view of one embodiment of a stent according to the disclosure. Stent  20  includes a flared proximal end portion  22 , an enlarged middle portion  24  and a distal end portion  26  connected to a polymeric sleeve  28 . Sleeve  28  is partially illustrated in  FIG. 5 . 
     While the enlarged middle portion  24  is shown in  FIG. 5  as having a symmetrical ovular shape, the shape may also be non-symmetrical as well. This stent is designed to pass from the esophagus, through the stomach, and into the duodenum. Sleeve  28  extends distally past the distal end of the distal end portion  26  of the stent  20  and past the common bile duct. 
     Sleeve  28  is suitably formed of a material that allows it to collapse upon itself. This, in combination with the extension of the sleeve  28  beyond the common bile duct, allows the bile to fun down the outside of the sleeve and continue into the small intestine rather than splashing back into the stomach. 
     Sleeve  28  is suitably formed of a polymer material, and can also be formed of an elastomeric polymeric material. 
     Examples of polymers include Teflon, PTFE, FEP, polyethylene and polypropylene. 
     Examples of elastomeric polymers include, but are not limited to, silicone, polyurethane and polyether-block-amide to mention only a few. 
       FIG. 6  is a side view of a stent  20  similar to that shown in  FIG. 5 , with the relative length of sleeve  28  to stent  20 . 
       FIG. 7  illustrates a stent  20  similar to those shown in  FIGS. 5 and 6  wherein stent  20  is illustrated passing from the esophagus, through the stomach and into the duodenum. The sleeve  28  of stent  20  extends distally past the distal end or the distal end portion  26  past the common bile duct into the duodenum. Proximal end portion  22  of stent  20  is in the esophagus, the enlarged middle portion  24  is located in the antrum of stomach and distal end portion  26  along with sleeve  28  is located in the duodenum. 
       FIG. 8  is a side view of an alternative embodiment of a stent  20  wherein the distal end portion  26  of stent  20  is relatively short, or just slightly greater than 0 mm and ends almost at the distal end of the enlarged central portion  24  of stent  20 . In this embodiment, the stent/sleeve is configured such that the sleeve  28  of the stent terminates in the stomach rather extending into the duodenum as illustrated in the embodiment shown in  FIG. 7 . Again, as in the embodiment shown in  FIG. 7  above, sleeve  20  extends beyond the common bile duct. 
     Again, sleeve  20  is configured to collapse and close upon itself to prevent bile reflux. In this embodiment, however, the pyloric valve is still able to close to further aid in the prevention of bile reflux. 
       FIG. 9  illustrates stent similar to that shown in  FIG. 8  wherein stent  20  is shown passing from the esophagus, through the stomach, and ending in the pylorus. The enlarged central portion and the distal end  26  thereof, thus terminates in the stomach. The sleeve  28  of stent  20  passes through the pylorus  16  of the stomach and into the duodenum  5 . In this embodiment, only the sleeve  28  is located in the duodenum. 
       FIG. 10  is a side view of an alternative embodiment of a stent  20  wherein the sleeve  28  is eliminated. In this embodiment a valve  30  is positioned in the distal end portion  26  of the stent between the enlarged central portion  24  and the distal end of stent  20 . 
     In one embodiment, the stent includes a one-way flow valve. 
     In some embodiments, the one-way flow valve may comprise one cuspid or multiple cuspids. 
     In one embodiment, the stent includes a tricuspid one-way valve as shown in  FIG. 11 . 
     Positioning of a one way valve in the distal end portion  26  of stent  20  aids in the prevention or significant reduction of bile reflux. The valve  30  is positioned within the distal end portion  26  of stent so as to reside at approximately the same location as the pyloric sphincter. 
     In some embodiments, stent  20  is in the formed of a braided or woven structure. Valve  30  may be coupled to the braided or woven construction. 
       FIGS. 12 and 13  illustrate alternative embodiments wherein at least a portion of the distal end portion  26  which will be disposed in the pyloric sphincter comprises a collapsible stent portion. The collapsible portion can be created in a variety of ways such as by reducing the radial strength of the stent in at least a portion of the end portion  26  or the entire portion, or by placing a collapsible sleeve or band around at least a portion of the distal end portion  26 . 
       FIG. 12  is a side view illustrating an alternative embodiment of a stent  20  wherein the valve  30  has been replaced with an elastomeric band  32 . Band  32  may be formed of any suitable elastomeric material. Examples include, but are not limited to, silicone, polyurethane and poly-ether-block amide. 
     Elastomeric band  32  is located in the distal end portion at the distal end of the enlarged middle portion  24  of stent  20 . 
     Elastomeric band  32  applies an inward pressure such that stent  20  closes upon itself in the region of elastomeric band  32 . 
     When the stomach muscles contract, the bolus of food will be pushed out of the stomach bulge, past the elastomeric band, and into the duodenum. This causes the elastomeric band to expand. Once the bolus of food has passed, the elastomeric band returns to it&#39;s at rest state wherein the stent  20  in the region of elastomeric band  32  is again closed, preventing or significantly reducing bile reflux. 
     The distal end portion  26  of stent  20  can be formed of a braided or woven construction as the rest of stent  20 , but can be suitably formed of a continuous wall construction in this embodiment, as opposed to a braided or woven configuration. 
       FIG. 13  is an alternative embodiment wherein the distal end portion  26  of stent  20  extends through the pyloric sphincter. At this location, the radial force of stent  20  is lower than the enlarged middle portion  24  of stent  20  and the proximal end portion  22  of stent  20  to allow closure of the sphincter. The radial force can be reduced in a variety of different was such as reducing the wire diameter, lowering the braid angle, reducing the number of wires, etc.  FIG. 13  illustrates a reduction in braid angle in the distal end portion  26  of stent  20 . The radial force may also be reduced only on a segment of the distal end portion  26  of stent  20  such as that portion closest to the enlarged middle portion  24  of stent  20 . 
     In any of the embodiments disclosed above, stent  20  may be formed from any suitable stent material. Examples include, but are not limited to, nickel-titanium alloy (nitinol), cobalt-chromium-nickel alloy (elgiloy), cobalt-chromium alloy, or stainless steel. 
     In any of the embodiments disclosed above, the entirety of the stent, or any portions thereof, may be formed of a braided or woven construction. 
     In any of the embodiments disclosed above, the stent, or any portions thereof, may be a laser cut stent. 
     In any of the embodiments disclosed above, the entirety of stent  20  may include any appropriate cover, or any portion or portions thereof. The covering may be formed of any suitable material. Examples include, but are not limited to, polyesters, polypropylenes, polyethylenes, polyurethanes, polynaphthalenes, polytetrafluoroethylenes, expanded polytetrafluoroethylene, silicone, copolymers thereof and mixtures or combinations thereof. In some implementations, the polymeric cover is silicone. 
     A description of some embodiments of a stent delivery catheter, stylet for use therein and methods of using the same is contained in one or more of the following statements: