Abstract:
Components may be used separately or in combination to create anchoring systems for intra-luminal implants for the treatment of metabolic disorders such as obesity and diabetes. Various systems include an external component adapted for deployment around a portion of the gastrointestinal tract (e.g., the duodenum) and an internal component adapted for implantation within the gastrointestinal tract. Various systems use anchors that are based on mechanical interference, elasticity, spring force, shape memory transformation, magnetic attraction, repulsion and/or levitation. Various embodiments rely on longitudinal anchoring of the implants with minimal force against tissue.

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) to U.S. provisional patent application 61/270,588, filed Jul. 10, 2009, entitled “Systems for Anchoring Intra-Luminal Implants within Hollow Body Organs,” which is incorporated herein by reference in its entirety. This application is related to U.S. patent application Ser. No. 12/752,697, filed Apr. 1, 2010, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention generally relates to implants placed within gastrointestinal systems, including the esophagus, the stomach and the intestines. In particular, it relates to implant systems having components implantable and removable using laparoscopic and endoscopic techniques for treatment of obesity, diabetes, reflux, and other gastrointestinal conditions. 
     BACKGROUND 
     Bariatric surgery procedures, such as sleeve gastrectomy, the Rouen-Y gastric bypass (RYGB) and the bileo-pancreatic diversion (BPD), modify food intake and/or absorption within the gastrointestinal system to effect weight loss in obese patients. These procedures affect metabolic processes within the gastrointestinal system by either short-circuiting certain natural pathways or creating different interaction between the consumed food, the digestive tract, its secretions and the neuro-hormonal system regulating food intake and metabolism. In the last few years, there has been a growing clinical consensus that obese diabetic patients who undergo bariatric surgery see a remarkable resolution of their Type-2 Diabetes Mellitus (T2DM) soon after the procedure. The remarkable resolution of diabetes after RYGB and BPD typically occurs too fast to be accounted for by weight loss alone, suggesting that there may be a direct impact on glucose homeostasis. The mechanism of this resolution of T2DM is not well understood, and it is quite likely that multiple mechanisms are involved. 
     One of the drawbacks of bariatric surgical procedures is that they require fairly invasive surgery with potentially serious complications and long patient recovery periods. In recent years, there is an increasing amount of ongoing effort to develop minimally invasive procedures to mimic the effects of bariatric surgery using minimally invasive procedures. One such procedure involves the use of gastrointestinal implants that modify transport and absorption of food and organ secretions. For example, U.S. Pat. No. 7,476,256 describes an implant having a tubular sleeve with an anchor having barbs. While these implants may be delivered endoscopically, the implants offer the physician limited flexibility and are not readily removable or replaceable, since the entire implant is subject to tissue in-growth after implantation. Moreover, stents with active fixation means, such as barbs that penetrate into the surrounding tissue, may potentially cause tissue necrosis and erosion of the implants through the tissue, which can lead to serious complications, such as systemic infection. Also, due to the intermittent peristaltic motion within the digestive tract, implants such as stents have a tendency to migrate. 
     SUMMARY 
     According to various embodiments, the present invention is a gastrointestinal implant system for treating metabolic disorders, such as diabetes and obesity. The system includes a tubular implant adapted for placement within at least a portion of the duodenum, the tubular implant having a securing feature and an external band configured for implantation around at least one of a pylorus, and a duodenum, the external band having a coupling feature for removably engaging and coupling with the securing feature of the internal tubular implant without penetrating the duodenum or pylorus, such that the therapeutic implant resists migration within the gastrointestinal tract, wherein the external band has an inner diameter generally equal to a corresponding outer diameter of the duodenum or pylorus, and the securing feature and coupling feature are configured such that the tubular implant is releasably coupled to the external band to facilitate removal of the tubular implant. 
     According to various embodiments, the present invention is a modular gastrointestinal implant system for treating metabolic conditions, such as diabetes and obesity. The system includes an external implant configured for affixing around at least a portion of a duodenum or pylorus, the external implant having a docking feature, and a therapeutic implant adapted for placement within a gastrointestinal tract, the therapeutic implant having a securing feature adapted to removably couple with the docking feature without penetrating the gastrointestinal tract, such that the therapeutic implant resists migration within the gastrointestinal tract, wherein the external band has a diameter generally equal to the diameter of the duodenum or pylorus. 
     According to other exemplary embodiments, the present invention is a method of treating metabolic conditions, such as diabetes and obesity. The method includes placing an external implant around at least a portion of the duodenum, the external implant having a docking feature and the external implant having an inner diameter generally equal to an outer diameter of the corresponding portion of the esophagus, implanting, using a minimally-invasive technique, an internal tubular implant having a securing feature to a location within the duodenum corresponding to the location of the external implant, and causing the securing feature to removably couple with the docking feature without penetrating the duodenum. 
     According to various disclosed embodiments, systems for anchoring intra-luminal implants within hollow body organs (e.g., the gastrointestinal organs) include an external fixation mechanism that can be delivered to an external surface of the organ (e.g., by laparoscopic techniques) and an intra-luminal implant configured to engage with the external fixation means, without the need for excessive radial force on the organ and without penetrating the tissue. According to various embodiments, the fixation mechanisms operate using techniques such as shape modification of the organ to capture the implant longitudinally or magnetic attraction, repulsion or levitation of the implant. Various embodiments of the present invention are useful for treating metabolic conditions, including for example, diabetes and obesity. 
     The present invention according to various embodiments is a modular system for creating internal bypass of food and organ secretions within the gastrointestinal tract that includes low-profile implants that are affixed around the stomach, the esophagus, the intestine or externally around junctions of these organs, and gastrointestinal implants that permit internal by-pass of food and organ secretions from one site within the gastrointestinal tract to other sites within the gastrointestinal tract that have complementary design features to the external implant that enables secure placement within the gastrointestinal tract. 
     The present invention according to various embodiments is a modular system for creating a completely reversible internal bypass of food and organ secretions within the gastrointestinal tract that includes low-profile implants that are affixed around the stomach, the esophagus, the intestine or externally around junctions of these organs and which enable secure attachment of other implants within the gastrointestinal tract, and gastrointestinal implants that permit internal by-pass of food and organ secretions from one site within the gastrointestinal tract to other sites within the gastrointestinal tract that have complementary design features to the external implant that enables secure placement within the gastrointestinal tract. 
     The present invention according to various embodiments is a modular system for treating gastro-esophageal reflux disease (GERD) that includes low-profile implants that are affixed around the stomach, the esophagus, the intestine or externally around junctions of these organs and which enable secure attachment of other implants within the gastrointestinal tract, and an internal tubular implant of a design that normally permits only one-way passage of food from the esophagus to the stomach and that can be secured within the gastrointestinal tract by the external low-profile implant. 
     The present invention according to various embodiments is a method for creating a reversible treatment for metabolic disorders, such as diabetes and obesity, and for the treatment of gastro-esophageal reflux disease (GERD), including placing low-profile implants that can be affixed around the stomach, the esophagus, the intestine or externally around junctions of these organs and which enable secure attachment of other implants within the gastrointestinal tract, and placing other gastrointestinal implants that permit internal by-pass of food and organ secretions from one site within the gastrointestinal tract to other sites within the gastrointestinal tract, which do not directly anchor to the tissue but are securely held by the external implant so that the procedure can be reversed easily. 
     The present invention according to various embodiments is a method of treating metabolic disorders, such as obesity and diabetes, by placing a permanently band like structure around the esophagus, the stomach, the intestine or externally around junctions of these organs, and endoscopically placing a long tubular sleeve within the GI tract with expandable elements at its ends, those expandable elements having design functionality that enables it to be reversibly secured in position by the external band. 
     The present invention according to various embodiments is a method for creating a gastrointestinal bypass, the method including delivering a band like structure at appropriate locations around the gastrointestinal tract, such as the esophagus, the stomach, the duodenal bulb, the pyloric junction, the gastro-esophageal junction, etc.; and delivering a tubular sleeve with expandable ring shaped elements at its ends, those rings having outward indentations that enable it to be reversibly secured in position by the external band. 
     According to various embodiments, as a second mode of anchoring, stabilizing, or preventing migration, the external band is coupled to an anatomical feature (e.g., a ligament) external to the tissue of the esophagus, stomach, pylorus, or intestine. In some embodiments, the external band is intertwined with, interlocked with or threaded between the anatomical feature and the tissue. According to one exemplary embodiment, the external band is coupled to the hepatoduodenal ligament. This second mode of anchoring enables the use of external bands that do not rely on excessive compressive force to keep the implant in place, since excessive compressive forces can cause tissue necrosis and erosion. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a portion of the digestive tract in the body showing an external band implanted around the outside diameter of the duodenal bulb and a tubular implant (sleeve) implanted on the inside surface of the duodenal bulb and anchored magnetically through the duodenal bulb tissue to the external band. The tubular implant extends into the duodenum to the ligament of Treitz. 
         FIGS. 2-7  show various embodiments of an external band that may be used as an external anchoring device to secure an internal tubular implant. 
         FIG. 8  shows a tubular implant that can be used to bypass the stomach, duodenum or other intestinal lumen. 
         FIG. 9  is a schematic view showing a trocar and cannula operable to access the implant location of the duodenal bulb using laparoscopic techniques. 
         FIG. 10  is a schematic view showing a cannula inserted to access the implant location of the duodenal bulb, and an external band implanted around the duodenal bulb. 
         FIG. 11  shows an exemplary endoscope used for diagnostic and therapeutic procedures in the gastrointestinal (GI) tract. 
         FIG. 12  is a sectional view of a portion of the digestive tract in the body, with an endoscope passing through the esophagus into the stomach, and the end of the scope is positioned to allow viewing of the pylorus. 
         FIG. 13A  shows an over-the-wire sizing balloon that can be used to measure the diameter of the pylorus, duodenal bulb, esophagus, pyloric antrum or other lumen in the GI tract. 
         FIG. 13B  shows a monorail sizing balloon that can be used to measure the diameter of the pylorus, duodenal bulb, esophagus, pyloric antrum or other lumen in the GI tract. 
         FIG. 14  is a sectional view of a portion of the digestive tract in the body, with an endoscope inserted into the GI tract up to the pylorus and a sizing balloon inserted through the working channel and into the area of the duodenal bulb. The balloon is inflated to measure the diameter of the duodenal bulb. 
         FIG. 15  shows the endoscope and delivery catheter advanced through the external anchoring device into the duodenum to the ligament of Treitz. 
         FIG. 16  shows the endoscope and delivery catheter advanced through the external anchoring device into the duodenum to the ligament of Treitz. The outer sheath of the delivery catheter is retracted to partially expose the tubular implant. 
         FIG. 17  shows the endoscope and delivery catheter advanced through the external anchoring device into the duodenum to the ligament of Treitz. The outer sheath of the delivery catheter is retracted to partially expose the tubular implant. A balloon catheter is inserted through the working channel of the endoscope to the area of the partially exposed tubular implant. The balloon is inflated to temporarily secure the tubular implant to the duodenum. 
         FIG. 18  shows the system of  FIG. 17 , where the outer sheath is retracted further to unsheath the tubular implant up to the duodenal bulb. 
         FIG. 19  shows the system of  FIG. 18 , where the endoscope has been withdrawn to the duodenal bulb. The balloon on the balloon catheter is then deflated and the balloon catheter is withdrawn to the duodenal bulb. The balloon is then re-inflated to open up and secure the proximal end of the tubular implant to the inside diameter of the docking element. 
         FIG. 20  shows an alternative device and method for deploying the proximal end of the tubular element. 
         FIG. 21  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the stomach a couple of inches below the gastro-esophageal junction. The external anchoring device can serve as a restrictive means and can form a pouch-like restrictive segment at the top of the stomach. An internal tubular implant is implanted from the external anchoring device at the stomach to the ligament of Treitz. 
         FIG. 22  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the esophagus at gastro-esophageal junction. An internal tubular implant is implanted from the external anchoring device at the gastro-esophageal junction to the ligament of Treitz. 
         FIG. 23  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the pylorus. An internal tubular implant is implanted from the external anchoring device at the pylorus to the ligament of Treitz. 
         FIG. 24  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the stomach antrum. An internal tubular implant is implanted from the external anchoring device at the stomach antrum to the ligament of Treitz. 
         FIG. 25  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the duodenal bulb. An internal tubular implant is implanted from the duodenal bulb to the ligament of Treitz. 
         FIG. 26  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the duodenal bulb. An internal tubular implant is implanted from the duodenal bulb to the ligament of Treitz. The internal tubular implant uses a stent which has magnets integrated into it which attract to the magnets on the external band. 
         FIG. 27  is a sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the duodenal bulb. An internal tubular implant is implanted from the duodenal bulb to the ligament of Treitz. The internal tubular implant uses a stent which has magnets integrated into it. The magnets on the external band and magnets on the internal band repel each other and limit movement or dislodgement of the internal tubular implant. 
         FIGS. 28-31  show sectional views of various embodiments of an external anchoring device implanted around the duodenal bulb. An internal tubular implant is implanted from the duodenal bulb to the ligament of Treitz. The internal tubular implant one of more expandable rings or stents to anchor the device inside of the duodenal bulb. 
         FIGS. 32-33  show tubular implants or sleeves including one or more magnets for attachment. 
         FIGS. 34-39  show various embodiments of an internal tubular implant sleeve. 
         FIG. 40  shows a stent which may be used as an anchoring device for internal tubular implant. The stent may incorporate magnets that attract or repel portions of the external band. The stent device may also anchor the sleeve of the internal tubular implant by mechanical means. 
         FIGS. 41A-48  show various embodiments of a stent that may be used as an anchoring device for an internal tubular implant. 
         FIG. 49  shows a delivery device for an internal tubular implant that is designed to go over the outside of an endoscope. The delivery device is loaded over the outside of an endoscope. 
         FIGS. 50-51  show various embodiments of a delivery device for an internal tubular implant. 
         FIG. 52  shows a cross-sectional view of a portion of the digestive tract in the body. An external anchoring device is implanted around the esophagus at the gastro-esophageal junction. An internal tubular implant is implanted at the gastro-esophageal junction. The internal tubular implant can serve the function of an anti-reflux valve or a restrictive stoma. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic, sectional view of a portion of a human digestive tract. As a person ingests food, the food enters the mouth  100 , is chewed, and then proceeds down the esophagus  101  to the lower esophageal sphincter at the gastro-esophageal junction  102  and into the stomach  103 . The food mixes with enzymes in the mouth  100  and in the stomach  103 . The stomach  103  converts the food to a semi-fluid substance called chyme. The chyme enters the pyloric antrum  104  and exits the stomach  103  through the pylorus  106  and pyloric orifice  105 . The small intestine is about 21 feet long in adults and is comprised of three sections: the duodenum  112 , the jejunum  113  and the ileum (not shown). The duodenum  112  is the first portion of the small intestine and is typically 10-12 inches long. The duodenum  112  is comprised of four sections: the superior, descending, horizontal and ascending. The duodenum  112  ends at the ligament of Treitz  109 . The papilla of Vater  108  is the duct that delivers bile and pancreatic enzymes to the duodenum  112 . The duodenal bulb  107  is the portion of the duodenum which is closest to the stomach  103 . 
     As shown, an external band  110  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band and extended into the duodenum  112  (e.g., to the ligament of Treitz  109 ). Magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  magnetically interact with (e.g., attraction, repulsion, or levitation) each other and secure the internal tubular implant to the  111  to the external band implant  110  in a removable or reversible configuration. The external band  110  and the internal implant  111  anchor by coupling with each other using any of a variety of techniques including, for example, anchoring means that are based on mechanical interference, elasticity, spring force, shape memory transformation, magnetic attraction, repulsion and/or levitation. 
     According to some embodiments, the internal implant  111  is configured such that it exerts little or no radial force against an internal surface of the gastrointestinal tract. Likewise, according to various embodiments, the external band is sized and shaped such that, in its final implant configuration, it exerts little or no radial force against an external surface of the gastrointestinal tract. For example, in certain embodiments, the external band has an implanted inner diameter generally equal to an outer diameter of the desired mounting location of the gastrointestinal tract. More specifically, in some such embodiments, the implanted inner diameter of the external band is within ten percent of the corresponding outer diameter of the implant location of the gastrointestinal tract. In other such embodiments, the implanted inner diameter of the external band is within five percent of the corresponding outer diameter of the implant location of the gastrointestinal tract. In other such embodiments, the implanted inner diameter of the external band is within two percent of the corresponding outer diameter of the implant location of the gastrointestinal tract. 
     According to various embodiments, as a second mode of anchoring, stabilizing, or preventing migration, the external band  110  is coupled to an anatomical feature (e.g., a ligament) external to the tissue of the esophagus, stomach, pylorus, or intestine. In some embodiments, the external band  110  is intertwined with or threaded between the anatomical feature and the tissue. According to one exemplary embodiment, the external band  110  is coupled to the hepatoduodenal ligament. This second mode of anchoring enables the use of external bands that do not rely on excessive compressive force to keep the implant in place, since excessive compressive forces can cause tissue necrosis and erosion. 
       FIG. 2  shows an external band that may be used to provide for an external anchoring device to secure the internal tubular implant. The band  250 , according to various embodiments, is made from one or more elastomers (e.g., silicone, polyurethane, and ePTFE), metals or fabrics (e.g., Dacron or a combination of polymers and textile materials). The band can be made flexible with varying degrees of longitudinal elasticity. According to various embodiments, the external band includes magnets  135  located on the inside surface, outside surface, or embedded in the middle of the band. Suitable materials for the magnets include, for example: neodymium-iron-boron [Nd—Fe—B], samarium-cobalt [Sm—Co], alnico, and hard ferrite [ceramic] or other suitable material. The magnets may be plated with gold or platinum or other material to make them radio-opaque or to improve corrosion resistance. The magnets may be encapsulated within a metal casing such as titanium or stainless steel to improve the corrosion resistance and the biocompatibility. As shown in  FIG. 2 , the magnets  135  are shaped as bars, which may have a length generally similar to the width of the band  250 . According to various embodiments, the band is placed around the intended implant location (e.g., the duodenal bulb, esophagus, or stomach). The band, according to various embodiments, is wrapped around the implant location like a belt. As shown, for example, in  FIG. 2 , one end of the band  250  has a loop  252  and the other end has a button  251 . The band is enclosed around the duodenal bulb or other implant location, the loop  252  is snapped over the button  251  to secure the band closed. The magnetic poles of the magnet are aligned such that the all the north poles are aligned to the inside or outside of the band. The magnets on the inside tubular implant are assembled to the device, so the poles are the opposite magnetic polarity, and the outside band and the inside tubular implanted will attract to each other when one device is sleeved inside the other. 
       FIG. 3  shows an alternative embodiment of an external band implant  110  in which the magnet  253  shape is changed to be a round disk. The round disk will provide for a band which is easier to longitudinally fold as in  254 . This fold will make it easier to insert the band in through a trocar when minimally invasive surgery techniques are used to implant the band. 
       FIG. 4  shows an alternative embodiment of an external band implant  110  with the magnet  135  shaped as in  FIG. 2 . The band has a magnetic clasp for securing the band  254 . 
       FIG. 5  shows an alternative embodiment of the external band implant  110  with the magnet  135  shaped as in  FIG. 2 . As shown in  FIG. 5 , the band has a mechanical clasp for securing the band  255 . 
       FIG. 6  shows another alternative embodiment of an external band implant  110 . The two ends of the band are secured by overlapping the band and the magnets on the inner layer of the band and the outer layer of the band are attracted to each other to hold and secure the band. The band is adjustable in size by changing the length of the overlap  256 . 
       FIG. 7  shows another alternative embodiment of an external band implant  110 . The band is secured with the same means as in  FIG. 2 . The band has been modified to have two layers. The inner layer  250  is similar to FIG.  2 ., but there is now also an outer band  258 . The two bands  250  and  258  form an annular space  259  in between the two bands. This annular space can be filled with air, saline or other suitable material to cause the band to inflate balloon like with the main expansion inward to reduce the inside diameter of the band. The fluid in the device can be adjusted by inserting a needle through the septum  257 . Additional fluid may be added or removed through the septum to change the sizing of the band. 
       FIG. 8  shows an internal tubular implant that can be used to bypass the stomach  103 , duodenum  112  or other intestinal lumen. The top portion of  FIG. 8  is a sectional view along the line A-A The tubular implant is made of a thin wall tube  148  and a series of magnets  140  attached to the inside of the thin wall tube. The tubular implants, according to various embodiments, are made from one or more of the following materials: silicone, polyether block amides (PEBAX), polyurethanes, silicone polyurethane copolymers, Nylon, polyethylene terphalate (PET), ePTFE, Kevlar, Spectra, Dyneena, polyvinyl chloride (PVC), polyethylene, polyester elastomers or other suitable materials. The thin wall tube length, according to various embodiments, may range from about 1 inch in length up to about 5 feet in length. The thickness of the thin walled tube will typically be in the range of from about 0.0001 inch thick up to about 0.10 inch thick. The diameter of the tubular implant will typically range from about 25 mm to about 35 mm, with a maximum range anticipated of from about 5 mm to about 70 mm in diameter. 
       FIG. 9  shows a cross-sectional view of a portion of the digestive tract in the body with a trocar  260  and cannula  261  inserted to access the implant location of the duodenal bulb using laparoscopic techniques. An alternative access route is to use natural orifice surgery via the esophagus, stomach or vagina. 
       FIG. 10  shows a cross-sectional view of a portion of the digestive tract in the body with the trocar removed and cannula  261  inserted to access the implant location of the duodenal bulb using laparoscopic techniques. As shown, the external band  110  has been implanted around the duodenal bulb. 
       FIG. 11  shows an endoscope  114 . Endoscopes  114  are used for diagnostic and therapeutic procedures in the gastrointestinal (GI) tract. The typical endoscope  114  is steerable by turning two rotary dials  115  to cause deflection of the working end  116  of the endoscope. The working end of the endoscope  116  or distal end, typically contains two fiber bundles for lighting  117 , a fiber bundle for imaging  118  (viewing) and a working channel  119 . The working channel  119  can also be accessed on the proximal end of the endoscope. The light fiber bundles and the image fiber bundles are plugged into a console at the plug in connector  120 . The typical endoscope has a working channel in the 2.6 mm to 3.2 mm diameter range. The outside diameter of the endoscopes are typically in the 8 mm to 12 mm diameter range, depending on whether the endoscope is for diagnostic or therapeutic purposes. 
       FIG. 12  is a cross-sectional view of a portion of the digestive tract in a human body. An endoscope  114  has been inserted through: the mouth  100 , esophagus  101 , stomach  103  and pyloric antrum to allow visualization of the pylorus  106 . 
       FIG. 13A  shows an over the wire sizing balloon  121  that is used to measure the diameter of the pylorus  106 , duodenal bulb  107 , esophagus  102 , pyloric antrum  104  or other lumen in the GI tract. The sizing balloon is composed of the following elements: proximal hub  122 , catheter shaft  124 , distal balloon component  125 , radiopaque marker bands  126 , distal tip  127 , guide wire lumen  128 , inflation lumen  129 . Distal balloon component  125  can be made from silicone, silicone polyurethane copolymers, latex, nylon 12, PET (Polyethylene terphalate) Pebax (polyether block amide), polyurethane, polyethylene, polyester elastomer or other suitable polymer. The distal balloon component  125  can be molded into a cylindrical shape, into a dog bone or a conical shape. The distal balloon component  125  can be made compliant or non-compliant. The distal balloon component  125  can be bonded to the catheter shaft  124  with glue, heat bonding, solvent bonding, laser welding or suitable means. The catheter shaft can be made from silicone, silicone polyurethane copolymers, latex, nylon 12, PET (Polyethylene terphalate) Pebax (polyether block amide), polyurethane, polyethylene, polyester elastomer or other suitable polymer. 
     Section A-A in  FIG. 13A  shows a sectional view of the catheter shaft  124 . The catheter shaft  124  is shown as a dual lumen extrusion with a guide wire lumen  128  and an inflation lumen  129 . The catheter shaft  124  can also be formed from two coaxial single lumen round tubes in place of the dual lumen tubing. The balloon is inflated by attaching a syringe (not shown) to luer fitting side port  130 . The sizing balloon accommodates a guidewire through the guidewire lumen from the distal tip  127  through the proximal hub  122 . The sizing balloon can be filled with a radiopaque dye to allow visualization and measurement of the size of the anatomy with a fluoroscope. The sizing balloon  121  has two or more radiopaque marker bands  126  located on the catheter shaft to allow visualization of the catheter shaft and balloon position. The marker bands  126  also serve as a fixed known distance reference point that can be measured to provide a means to calibrate and determine the balloon diameter with the use of the fluoroscope. The marker bands can be made from tantalum, gold, platinum, platinum iridium alloys or other suitable material. 
       FIG. 13B  shows a rapid exchange sizing balloon  134  that is used to measure the diameter of the pylorus  106 , duodenal bulb  107 , esophagus  102 , pyloric antrum  104  or other lumen in the GI tract. The sizing balloon is composed of the following elements: proximal luer  131 , catheter shaft  124 , distal balloon component  125 , radiopaque marker bands  126 , distal tip  127 , guide wire lumen  128 , inflation lumen  129 . The materials of construction will be similar to that of  FIG. 4A . The guidewire lumen  128  does not travel the full length of the catheter, it starts at the distal tip  127  and exits out the side of the catheter at a distance shorter than the overall catheter length. Guidewire  132  is inserted into the balloon catheter to illustrate the guidewire path through the sizing balloon. The sizing balloon catheter shaft changes the section along its length from a single lumen at section B-B  133  to a dual lumen at section A-A at  124 . 
       FIG. 14  shows an endoscope  114  inserted into the GI tract up to the pylorus  106 . A sizing balloon  121  is inserted through the working channel  119  of the endoscope and into the area of the duodenal bulb  107 . The sizing balloon  121  is inflated with a contrast agent. The diameter of the duodenal bulb  107  is measured with a fluoroscope. 
       FIG. 15  shows a sectional view of a portion of the digestive tract in the body. An internal tubular implant is loaded onto the delivery catheter. The delivery catheter, according to various embodiments, is advanced into the duodenum  112  until the distal end of the delivery catheter is at the ligament of Treitz  109 . While in many embodiments, the end of the delivery catheter is positioned at the ligament of Treitz  109 , according to other embodiments, the end of the delivery catheter is located proximal or distal to the ligament of Treitz  109 . For example, the distal end of the delivery catheter may be located in the jejunum  113 . The internal tubular implant is deployed from the delivery catheter by pulling handle  153  towards  154 . 
     Next, as shown in  FIG. 16 , the outer sheath  151  on the delivery catheter is retracted a couple of inches to expose the tubular implant  111 . 
     Next, as shown in  FIG. 17 , a sizing balloon  121  is inserted through the working channel  119  on endoscope  114 . The sizing balloon  121  is advanced about one inch beyond the distal end of the endoscope  114  but still inside of the tubular implant  111 . The sizing balloon  121  is then inflated with saline or contrast agent. The inflated sizing balloon  121  will hold the tubular implant  111  in place in the duodenum  112  or jejunum  113  (e.g., near the ligament of Treitz  109 ). 
     Then, as shown in  FIG. 18 , the outer sheath  151  is retracted further to expose all but a couple of centimeters of the tubular implant  111 . The outer sheath  151  end is now near the pylorus  106 . 
     Then, as shown in  FIG. 19 , the distal end of the endoscope  114  has been pulled back to the pyloric orifice  105  and the sizing balloon  121  has been deflated and repositioned and reinflated to seat the proximal end of the internal tubular implant  111  to be in contact with the outer band  110 . The magnets  140  on the tubular sleeve are now in contact with the magnets  140  on the docking element. The magnetic attraction between the magnets  140  secures the tubular implant  111  to the docking element  110 . 
       FIG. 20  is an alternative embodiment showing a means to seat the proximal end of the internal tubular implant  111  to the outer band  110 . A nitinol conical/tubular shaped forceps  160  are attached to the inner catheter near the proximal end of where the tubal implant is loaded on the delivery catheter. The nitinol forceps  160  have an elastic memory in the open state. When the outer sheath  151  is fully retracted, the conical forceps open and, in turn, open the proximal end of the tubular implant  111  and seats the magnets  140  on the tubular implant  111  to the magnets  140  on the outer band  111 . 
       FIG. 21  shows a sectional view of a portion of the digestive tract in a human body. As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically attracted to each other and secure the internal tubular implant to the  111  to the external band implant  110 . As shown, the external band  110  is secured to the tubular implant  111  at or near the gastro-esophageal junction. The external band  110  around the stomach creates a small pouch like area at the top of the stomach and causes a restrictive component to food flow into the digestive system. An external band  110  is implanted around the upper portion of the stomach and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or jejunum  113  (e.g., at or near the ligament of Treitz  109 ). 
       FIG. 22  shows a sectional view of a portion of the digestive tract in a human body. As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically attracted to each other and secure the internal tubular implant to the  111  to the external band implant  110 . As shown, the external band  110  is secured to the tubular implant  111  at or near the gastro-esophageal junction. An external band  110  is implanted around the esophagus and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or the jejunum  113  (e.g., at or near the ligament of Treitz  109 ). 
       FIG. 23  shows a sectional view of a portion of the digestive tract in a human body. As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically attracted to each other and secure the internal tubular implant  111  to the external band implant  110 . As shown, the external band  110  is secured to the tubular implant  111  at or near the gastrointestinal junction (e.g., across the pylorus) and the internal tubular implant  111  extends into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). 
       FIG. 24  shows a sectional view of a portion of the digestive tract in a human body. As shown, the external band  110  is implanted around the stomach antrum and an internal tubular implant  111  is attached to the external band  110  and is extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically attracted to each other and secure the internal tubular implant  111  to the external band implant  110 . 
       FIG. 25  shows a sectional view of a portion of the digestive tract in a human body. An external band  110  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). Magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically repelled from each other and secure the internal tubular implant  111  to the external band implant  110 . 
       FIG. 26  is a sectional view of a portion of the digestive tract in a human body. An external band  110  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically attracted and secure the internal tubular implant  111  to the external band implant  110 . In this embodiment, the internal tubular implant  111  includes and is coupled to a stent  263  (with magnets attached). 
       FIG. 27  is a sectional view of a portion of the digestive tract in a human body. An external band  110  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically repelled and secure the internal tubular implant  111  to the external band implant  110 . Stent  263  (with magnets attached) is attached to internal tubular implant  111 . In some embodiments, the stent  263  has an expanded outer diameter of generally equal to an inner diameter of the corresponding implant location of the gastrointestinal tract. According to some embodiments, the expanded outer diameter of the stent is within about ten percent, about five percent, or about two percent of the inner diameter of the corresponding implant location of the gastrointestinal tract. 
       FIGS. 28-31  show various embodiments of an external band  264  and an internal implant  111  configured for removably or reversibly coupling with each other. As shown, in each of these embodiments, the internal implant includes a portion including a feature or a structure adapted to mechanically couple with a corresponding (e.g., mating) feature or structure of the external band  264 . In each case, the coupling is accomplished through or across a gastrointestinal organ or tissue (e.g., across the duodenum, the pylorus, or the gastric antrum), but without penetrating such tissue. In some embodiments, the external band  264  and the internal implant  111  are not in direct mechanical contact, but instead engage or couple with each other with intervening gastrointestinal tissue. 
       FIG. 28  is a sectional view of a portion of the digestive tract in a human body. An external band  264  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  264  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, diameter interference between at least a portion of the external band  264  and internal implant  110  limit longitudinal movement without exerting substantial radial force on the gastrointestinal tract. As shown, the tubular implant  111  includes an expandable ring or stent  265 , which is attached to the tube portion of the tubular implant  111  and operates to secure the internal tubular implant  111  to the external band  264 . 
       FIG. 29  is a sectional view of a portion of the digestive tract in a human body. An external band  264  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is coupled to the external band and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, diameter interference with the external band  264  and internal implant  111  secure the implant  110  within the gastrointestinal system and limit longitudinal movement without exerting too much radial force. The tubular implant  111  includes an attached expandable ring or stent  265 . 
       FIG. 30  is a sectional view of a portion of the digestive tract in a human body. An external band  264  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  264  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, diameter interference with the external band  264  and internal implant  111  limit longitudinal movement without exerting too much radial force. Expandable ring/stent  265  is attached to internal tubular implant  111 . According to exemplary embodiments, the external band  264  (of  FIGS. 28-30 ) includes a portion or portions having a final, implanted inner diameter smaller than an outer diameter of a corresponding securing portion (e.g., the ring or stent  265 ) of the internal implant, such that, upon implantation, the external band  264  mates with, couples with, or otherwise interacts with the internal tubular implant  111  to prevent or resist longitudinal movement or migration of the tubular implant. Likewise, according to various embodiments, the ring of stent  265  has an expanded outer diameter of generally equal to an inner diameter of the corresponding implant location of the gastrointestinal tract. According to some embodiments, the expanded outer diameter of the stent is within about ten percent, about five percent, or about two percent of the inner diameter of the corresponding implant location of the gastrointestinal tract. 
       FIG. 31  is a sectional view of a portion of the digestive tract in a human body. An external band  110  is implanted around the duodenal bulb  107  and an internal tubular implant  111  is attached to the external band  110  and extended into the duodenum  112  or the jejunum  113  (e.g., to the ligament of Treitz  109 ). As shown, magnets  135  on the external band  110  and magnets  136  on the internal tubular implant  111  are magnetically repelled from each other and secure the internal tubular implant to the  111  to the external band implant  110 . In various embodiments, the internal implant  111  also includes magnets  266 , which are attracted to corresponding magnets on the external band  110 . 
       FIGS. 32-33  show various embodiments of an internal tubular implant. The top portion of  FIG. 33  is a sectional view along the line A-A The tubular implant is designed to attach to another tubular implant or to an external band by a magnetic attachment means. In the embodiment of  FIG. 32 , the tubular implant has magnets  140  on the outside diameter. In the embodiment of  FIG. 33 , the tubular implant has magnets  140  in the wall thickness. In various embodiments, the magnets  140  are adapted for coupling the tubular implant to an external band, a docking element or another internal implant. 
       FIGS. 34-36  shows various embodiments of a simple sleeve used as a component of an internal tubular implant, or for extending a tubular implant. The top portion of  FIG. 34  and  FIG. 35  is a sectional view along the line A-A In the embodiment of  FIG. 34 , the sleeve has radio-opaque markers  196  and may have holes in the sleeve  197  to allow some fluid flow through the sleeve, if required. In the embodiment of  FIG. 35 , the sleeve has magnetic particles or ferromagnetic material  140  incorporated into the sleeve to allow attachment of the sleeve to a magnetic docking station or tubular implant. In the embodiment of  FIG. 36 , the sleeve has magnetic particles or ferromagnetic material  140  incorporated into the sleeve to allow attachment of the sleeve to a magnetic docking station or tubular implant. The top portion of  FIG. 36  is a sectional view along the line A-A and B-B In various embodiments, the sleeve also has longitudinal pleats  202  in the surface to allow it to collapse in diameter more uniformly and may help to reduce the loaded profile. The longitudinal pleats maybe be over the entire length or just apportion of the diameter or length. In the embodiment of  FIG. 37 , the sleeve has pleats around the circumference  203 . These circumferential pleats will allow the tubular implant or sleeve to bend easier without kinking. The top portion of  FIG. 37  is a sectional view along the line A-A 
       FIG. 38  is a simple sleeve with a conical diameter. The top portion of  FIG. 38  is a sectional view along the line A-A The simple sleeve may be used as part of a docking station or tubular implant. 
       FIG. 39  is a simple sleeve with a stepped diameter. The top portion of  FIG. 39  is a sectional view along the line A-A The simple sleeve may be used as part of a docking station or tubular implant. 
       FIG. 40  is a stent that can be used to couple with an external band  110 . The top portion of  FIG. 40  is a sectional view along the line A-A The stent may incorporate magnets to allow magnetic attract or repulsion to an external band. As shown, magnets  136  are associated with the stent and are configured to interact with magnets  135  associated with the external band  110 . According to various embodiments, the stent is integrated with or otherwise adapted to couple with an internal implant. For example, the stent may serve as a docking element for a sleeve portion of the tubular implant. 
       FIG. 41A  shows a stent that can be used with or as a part of an internal implant. The stent can be braided from round or flat wire. The drawing of the stent is in the expanded state. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. 
       FIG. 41B  shows a stent that can be used as a part of the internal implant. The stent can be braided from round or flat wire. The drawing of the stent is in the expanded state. The stent may include magnets  140  attached to the stent. The magnets  140  may be on the inside diameter, outside diameter, both the inside or outside diameter or incorporated into the wall. The magnets  140  can be used as a means to attach a tubular implant, such as  111 . The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. 
       FIG. 42A  shows a stent that can be used as part of an internal implant. In various embodiments, the stent is laser cut from round metal tubing or from a flat sheet of metal. The central portion of the stent&#39;s diameter may be set to a smaller diameter to provide increased resistance to stent migration. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. 
       FIG. 42B  shows a stent that can be used as a part of an internal implant. According to various embodiments, the stent is laser cut from round metal tubing or from a flat sheet of metal. The central portion of the stent&#39;s diameter may be shaped into an hour glass shape to provide increased resistance to stent migration. The stent has hoops  190  at the end of the stent. The hoops may be used to interlock with a stent retainer  159  on the inner catheter  152  to prevent premature deployment before the sheath is fully retracted. Radiopaque markers  191  can be attached to the end of the stent to increase the radio-opacity of the stent. A metal insert may be pressed/swaged into the hoops  190 . The insert may be made from a high atomic density material, such as tantalum, gold, platinum or iridium. The insert may take the form of a disk or sphere and may be plastically deformed to fill the hoop cavity. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. According to various embodiments, the stent of  FIG. 42A  or  42 B includes a narrow central portion adapted to generally fit within an align with the pylorus. 
       FIGS. 43A and 43B  show embodiments of a stent that can be used as a part of an internal implant docking element. According to various embodiments, the stent is laser cut from round metal tubing or from a flat sheet of metal. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. 
       FIG. 44A  shows a coil stent that can be used as a part of an internal implant. According to various embodiments, the stent is made from round or flat wire. The stent may be self expanding or balloon expandable. The stent also may be laser cut into a coil from tubing. According to various embodiments, the stent is made from nitinol. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. The stent has a hoop  192  at each end of the coil. The stent can be wound down onto a catheter by inserting a pin into the hoops on each end of the stent and rotating the pins in opposite directions to cause the stent to wind down onto the catheter. In the embodiment of  FIG. 44B , the stent has magnets  140  on the coil of the stent. The magnets can be used as an attachment means to a tubular implant. 
       FIG. 45  shows a coil stent that can be used as a part of an internal implant. According to various embodiments, the stent is made from wire or sheet nitinol metal. Several stents in series adjacent to each other can be used to form the docking element. 
       FIG. 46A  shows a stent that can be used as a part of an internal implant. According to various embodiments, the stent is laser cut from round metal tubing or from a flat sheet of metal. The stent may be balloon expanded or self expanding. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. As shown in  FIG. 46A , the stent is shaped to a conical shape to provide increased resistance to stent migration and to more closely fit the anatomy. As shown in  FIG. 46B , the stent is shaped to a have a stepped diameter to provide increased resistance to stent migration and to more closely fit the anatomy. 
       FIG. 47A  shows a stent that can used as a part of an internal implant. The stents of this invention can be comprised of one or more of the following materials: Nickel titanium alloys (Nitinol), Stainless steel alloys: 304, 316L, BioDur® 108 Alloy, Pyromet Alloy® CTX-909, Pyromet® Alloy CTX-3, Pyromet® Alloy 31, Pyromet® Alloy CTX-1, 21Cr-6Ni-9Mn Stainless, 21Cr-6Ni-9Mn Stainless, Pyromet Alloy 350, 18Cr-2Ni-12Mn Stainless, Custom 630 (17Cr-4Ni) Stainless, Custom 465® Stainless, Custom 455® Stainless, Custom 450® Stainless, Carpenter 13-8 Stainless, Type 440C Stainless, Cobalt chromium alloysMP35N, Elgiloy, L605, Biodur® Carpenter CCM alloy, titanium and titanium alloys, Ti-6A14V/ELI and Ti-6A1-7Nb, Ti-15Mo tantalum, tungsten and tungsten alloys, pure platinum, platinum-Iridium alloys, platinum-nickel alloys, niobium, iridium, Conichrome, gold and gold alloys. The stent may also be comprised of one or more of the following absorbable metals: pure iron and magnesium alloys. The stent may also be comprised of the following plastics: polyetheretherketone (PEEK), polycarbonate, polyolefins, polyethylenes, polyether block amides (PEBAX), nylon 6, 6-6, 12, polypropylene, polyesters, polyurethanes, polytetrafluoroethylene (PTFE) poly(phenylene sulfide) (PPS), poly(butylene terephthalate) PBT, polysulfone, polyamide, polyimide, poly(p-phenylene oxide) PPO, acrylonitrile butadiene styrene (ABS), polystyrene, poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), ethylene vinyl acetate, styrene acrylonitrile resin, polybutylene. The stent may also be comprised of the following absorbable polymers: polyglycolic acid (PGA), polylactide (PLA), poly(e-caprolactone), poly(dioxanone) poly(lactide-coglycolide). 
     According to various embodiments, the stent  137  stent is laser cut from a round tubing or from a flat sheet of metal. The flat representation of the stent circumference is shown in item  138 . The flat representation of an expanded stent is shown in item  139 . The end view of the stent is shown  141 . Magnets  140  are attached to the stent on the outside diameter. The magnets  140  may be attached to the stent by use of a mechanical fastener, glue, suture, welding, snap fit or other suitable means. The stent can be either balloon expandable or self expanding. The magnets may be located in middle of the stent or at the ends of the stent. Suitable materials for the magnets include: neodymium-iron-boron [Nd—Fe—B], samarium-cobalt [Sm—Co], alnico, and hard ferrite [ceramic] or other suitable material. 
       FIG. 47B  shows a stent that can used as a part of an internal implant. Stent  142  may be laser cut from a round tubing or from a flat sheet of metal. The flat representation of the stent circumference is shown in item  143 . The flat representation of an expanded stent is shown in item  144 . The end view of the stent is shown  145 . Permanent magnets  140  are attached to the stent on the outside diameter. This stent is a covered stent. The stent covering is not shown on items  142 ,  143  or  144 . The covering are shown on the end view which shows stent  145 . Stent may have an outside covering  146 , inside covering  147  or both. Suitable materials for the covering include, but are not limited to: silicone, polyether block amides (PEBAX), polyurethanes, silicone polyurethane copolymers, nylon 12, polyethylene terphalate (PET), ePTFE, Kevlar, Spectra, Dyneena, polyvinyl chloride (PVC), polyethylene or polyester elastomers. The coverings may be dip coated onto the stent or they may be made as a separate tube and then attached to the stent by adhesives or mechanical fasteners, such as suture, rivets, or by thermal bonding of the material to the stent or another layer. The covering may also have drugs incorporated into the polymer to provide for a therapeutic benefit. The covering  146  or  147  may also be of biologic origin. Suitable biologic materials include, but are not limited to: Amnion, Collagen Type I, H, HI, IV, V, VI—Bovine, porcine, ovine, placental tissue or placental veins or arteries and small intestinal sub-mucosa. 
       FIG. 48  shows a stent that can used as a part of an internal implant. Stent may be laser cut from a round metal tubing or from a flat sheet of metal. The flat representation of the stent circumference is shown in item  138 . The flat representation of an expanded stent is shown in item  137 . The end view of the stent is shown  141 . Magnets  140  are attached to the stent on the inside diameter. The magnets may be attached to the stent by use of a mechanical fastener, glue, suture, welding, snap fit or other suitable means. The stent can be either balloon expandable or self expanding. The magnets may be located in middle of the stent or at the ends of the stent. Suitable materials for the magnets include: neodymium-iron-boron [Nd—Fe—B], samarium-cobalt [Sm—Co], alnico, and hard ferrite (ceramic) or other suitable material. The stent may be balloon expanded or self expanding 
       FIG. 49  shows the delivery catheter for the apparatus disclosed loaded over an endoscope. 
       FIG. 50  shows an alternative embodiment drawing of a delivery catheter for a self expanding internal tubular implant. The tubular implant is located distal to the docking element. The delivery catheter could also be used for delivery of a stented sleeve construct where the sleeve and stent are integrated together into one implant. The delivery catheter is constructed with a central lumen  150  large enough to allow the catheter to be loaded over the outside diameter of the endoscope  114 . The delivery catheter consists of an outer catheter  151  and an inner catheter  152 . 
     To load the tubular implant onto the delivery catheter the outer sheath handle  153  is retracted towards the inner catheter handle  154  until distance is a small as possible. The outer sheath is then partially closed by advancing the outer sheath handle  153  away from the inner sheath handle  154 . Continue advancing the outer sheath  151 , when the tubular implant is completely covered by the outer sheath  151 , the loading process is complete for the tubular implant. The delivery catheter also has a space on the inner catheter for the modular implant to be loaded. Attached to the inner catheter is a stent retainer  159 . The purpose of the stent retainer  159  is to prevent the stent from releasing from the delivery catheter prematurely during deployment. The stent retainer  159  is fastened to the inner catheter. The stent retainer  159  can be made from metal or plastic and can be made radio-opaque by making it from a radio-opaque material such as tantalum. The stent retainer  159  has a complementary shape that holds the tips on the stent and does not allow the stent to move distally or forward until the outer sheath  151  is fully retracted to the stent retainer  159 . The catheter has a side port  156  which allows the space between the inner and outer sheaths to be flushed with saline. The outer sheath  151  and inner sheath  152  may be made from a simple single layer polymer extrusion, such as from polyethylene or PTFE. The outer sheath  151  may also be constructed in the following manner. The sheath inner diameter surface is constructed of a thin wall PTFE liner  157 . A layer of reinforcement  158  is placed over the PTFE liner  157 . According to various embodiments, the reinforcement is either a braid of wire or a coil of wire. The wire cross-section can be either round or rectangular. In some embodiments, the wire is made from a metal such as 316, 304 stainless steel, Nitinol, or other suitable material. The wire diameters are typically in the 0.0005 inch to 0.010 inch diameter range. The outer jacket material may be reflowed into the reinforcement layer by melting the material and flowing the melted polymer into the spaces in between the braided wire or the coiled wires. 
       FIG. 51  shows an alternative embodiment of a delivery catheter for a self expanding internal tubular implant or for both  110  and  111  on the same catheter. The delivery catheter is constructed with a smaller outside diameter to allow the catheter to be inserted through the working channel of the endoscope  114 . The delivery catheter consists of an outer catheter  151  and an inner catheter  152 . Attached to the inner catheter is a stent retainer  159 . The purpose of the stent retainer  159  is to prevent the stent from releasing from the delivery catheter prematurely during deployment. The stent retainer  159  is fastened to the inner catheter. The stent retainer  159  can be made from metal or plastic and can be made radio-opaque by making from it from a radio-opaque material such as tantalum. The stent retainer has a complementary shape that holds the tips on the stent and does not allow the stent to move distally or forward until the outer sheath  151  is fully retracted to the stent retainer  159 . The catheter has a side port  156  which allows the space between the inner and outer sheaths to be flushed with saline. The outer sheath  151  and inner sheath  152  may be made from made from a simple single layer polymer extrusion such as from polyethylene or PTFE. The outer sheath  151  may also be constructed in the following manner. The sheath inner diameter surface is constructed of a thin wall PTFE liner  157 . A layer of reinforcement  158  is placed over the PTFE liner  157 , the reinforcement may be either a braid of wire or a coil of wire. The wire cross-section can be either round or rectangular. According to various embodiments, the wire is made from a metal such as 316 or 304 stainless steel or Nitinol or other suitable material. The wire diameters are typically in the 0.0005 inch to 0.010 inch diameter range. The outer jacket material may be reflowed into the reinforcement layer by melting the material and flowing it into the spaces in between the braided wire or the coil wires. The outside diameter of this catheter will range typically from 1 mm to 4 mm. The catheter can be constructed to be an over the wire catheter or a rapid exchange catheter. For a rapid exchange design, the guidewire will enter the central lumen of the distal end of the catheter and exit at point  188 . For an over the wire catheter design, the guidewire will enter the central lumen of the distal end of the catheter and exit at point  189 . 
       FIG. 52  is a cross-sectional view of a portion of the digestive tract in the body. An external band is implanted in the esophagus at gastro-esophageal junction  102 . An internal tubular implant is attached to the external band. The tubular implant can have bi-leaflet anti-reflux valve  166 , a tri-leaflet anti-reflux valve  167 , a quad-leaflet anti-reflux valve  168 , a penta-leaflet anti-reflux valve  169 , a six-leaflet anti-reflux valve  170  or seven-leaflet anti-reflux valve  171 . The implant can also be a stoma. 
     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.