Abstract:
A system for therapy within a gastrointestinal system includes anchoring or attachment functionality embodied in a low-profile implant technology and removable therapy components, which can be reversibly attached to these low-profile implants to accomplish various therapies. This design allows the physician to tailor the therapy to the patient&#39;s needs. The system has the potential to create conduits for diversion and/or restriction of food and organ secretions and to facilitate the treatment of metabolic disorders such as obesity and T2DM.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 13/494,956, filed Jun. 12, 2012, entitled “Gastrointestinal Prostheses,” which is a continuation of U.S. application Ser. No. 12/752,697, filed Apr. 1, 2010, entitled “Modular Gastrointestinal Prostheses,” now patented as U.S. Pat. No. 8,211,186, which claims the benefit under 35 U.S.C. §119 of U.S. Provisional Application 61/211,853, filed on Apr. 3, 2009, entitled “Modular Systems for Intra-Luminal Therapies within Hollow Body Organs,” which are incorporated herein by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     This invention relates to prosthetic implants placed within the gastrointestinal system, including the stomach, the esophagus and the intestines. In particular, it relates to implant systems having components implantable and removable using 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) are surgical procedures to 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 neurohormonal 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, as the entire implant is subject to tissue in-growth after implantation. Moreover, stents with active fixation means, such as barbs that penetrate in to 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. 
     SUMMARY 
     According to various embodiments, the present invention is an intra-luminal implant system for treating metabolic disorders such as obesity and diabetes, which provides far more flexible therapy alternatives than single devices to treat these disorders. These implant systems include components that can be selectively added or removed to mimic a variety of bariatric surgical procedures with a single basic construct. The fundamental building blocks of the system include anchoring implants that are placed within the GI system or some instances around particular organs. These low-profile implants are designed for long-term performance with minimal interference with normal physiological processes. Features of these anchoring implants allow them to act as docking stations for therapy implants designed for achieving certain metabolic modification goals. By using a combination of anchoring implants with corresponding tubular elements, it is possible to design therapies with particular metabolic modification goals or those that mimic currently practiced bariatric surgical procedures. This allows the physician to customize the therapy to the patient at the time of the initial procedure but also allows the flexibility to alter the therapy during the life-time of the patient by replacing individual components. 
     According to some embodiments, the invention includes a anchoring implant portion (docking element) including an expandable structure (e.g., a low profile stent or ring or fabric/elastomeric cuff) anchored within the esophagus, the gastro-esophageal junction, the pyloric junction, the duodenum or the jejunum and may have sleeve or graft extensions. The stents may be balloon expandable or self-expanding and anchor against the tissue with radial force. The rings could be made of self-expanding Nitinol and anchor to the tissue by entrapment of the tissue within the ring elements or by radial force. The cuffs could be either sutured or stapled or permanently or reversibly attached by other mechanical means to the tissue. The anchoring implant includes or is adapted to receive (e.g., endoscopically) features that enable docking functionality. The docking functionality of the stent, ring or cuff, for example, could take the form of magnetic elements, hooks, mating mechanical elements or structures (such as the stent braid or mesh) that are integral to the framework of the stent, ring or cuff or the sleeve or graft extension. The system also could be such that the docking functionality is not integral to the stent, ring or cuff but is introduced later by attaching other elements such as magnets, hooks, mating mechanical elements etc to the framework of the stent, ring, cuff or to the sleeve/graft extension of the above implants. Therapeutic implants, such as tubular sleeves or stent grafts are adapted to be reversibly attached to the anchoring implants. These therapeutic implants will have corresponding features (e.g., magnets, hooks, mechanical elements) to enable docking to the anchoring implants, so that the therapeutic implants can be reversibly attached to the anchoring implants. In some embodiments, the tubular implants will not be in contact with tissue to minimize or prevent tissue in-growth and facilitate easy removal with endoscopic instrumentation after long-term implantation. 
     According to various embodiments, the anchoring or docking implants comprise stents or covered stents (stent grafts) that promote tissue in-growth without penetrating into the tissue. Such stents may include, for example, a self-expanding laser cut stent with non-penetrating struts that engage the wall of the GI tract or a self-expanding stent braided with a Dacron type fabric covering of the right porosity would promote tissue in-growth and aid fixation. 
     According to various embodiments, the anchoring or docking implants comprise a double braided stent (e.g., having a spacing between the braids of 0.5 to 5.0 mm). This embodiment is optimized such that the outer braid could be securely anchored within tissue, but the tissue would not grow into the inner braid, which can then be used to anchor the replaceable implant. 
     According to various embodiments, the anchoring or docking implants are specifically designed to be constrained at certain anatomic locations. Such designs, for example, may include a double-flange shaped or dumbbell-shaped implants placed at the pyloric junction or barrel shaped stents placed within the duodenal bulb. 
     According to various embodiments, the replaceable therapeutic implants that dock to the anchoring implants take the form of long tubes that can selectively channel the flow of food and secretions from organs (e.g., the stomach, gall bladder, intestines and pancreas) to various destinations within the digestive tract. This diversion and bypass of food and organ secretions (e.g., insulin and incretin from the pancreas and bile from the gall bladder) could then be controlled by adjusting the design features of the system where the implants are placed within the GI tract. The implants could also include restrictive stoma type elements or anti-reflux valves. To divert food and secretions from the first part of the intestine, for example, an anchoring implant can be placed within the duodenal bulb or at the pyloric junction. Then, a thin tube about 1-2 feet in length with a funnel shaped proximal end and a rigid ring shaped distal end can be introduced into the proximal duodenum and docked to the permanent implant. It would be possible to later remove this by endoscopic means by simple undocking it from the anchoring implant. To restrict passage of food, a restrictive element such as one created by a tapered stepped tube or a stent or a stent graft can become the docking element and be reversibly attached to the docking station. 
     According to various embodiments, the docking means may include engaging/disengaging mechanical shape memory and super-elastic elements, attractive/repulsive and levitating magnetic mechanisms, loop-hoop fastener technologies etc. The systems may be deployed with functional docking components or those components would be attached to the permanent implants under endoscopic visual guidance. The docking means is designed so that the therapeutic implants can be easily deployed and securely affixed to the anchoring implants. According to various embodiment, the engaging elements of the docking system are arranged so that they do not impinge on the surrounding tissue, nor would be later covered with tissue layers. This facilitates disengaging the tubular sleeve elements from the stent with simple magnetic instruments or grasper type endoscopic instruments or funnel shaped retrieval basket catheters or using a draw-string type mechanism. 
     According to some embodiments, the anchoring element is integrated with a therapy component. 
     According to various embodiments, the present invention is a method of treating gastro-esophageal reflux disease (GERD) including placing a low-profile implant within the stomach, the esophagus, the intestine or at internal junctions of these organs or around these organs, and securely attaching to the implant other gastro-intestinal implants that permit bypass of food and organ secretions from one site within the gastro-intestinal tract to other sites within the gastro-intestinal tract. 
     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 cross sectional view of a portion of the digestive tract in the body. A docking element is implanted in the duodenal bulb and a tubular implant (sleeve) is attached to the docking element and extended into the duodenum to the ligament of treitz. 
         FIG. 2  is a cross sectional view of a portion of the digestive tract in the body. An endoscope is inserted into the mouth, passing through the esophagus in to the stomach and the end of the scope is pointed to allow viewing of the pylorus. 
         FIG. 3  is a drawing of a typical endoscope used for diagnostic and therapeutic procedures in the gastro intestinal (GI) tract. 
         FIG. 4A  is a drawing of 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. 4B  is a drawing of 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. 5  is a sectional view of a portion of the digestive tract in the body. An endoscope is inserted into the GI tract up to the pylorus. A sizing balloon is 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. 6A  is a drawing of a stent that can used as a docking element. 
         FIG. 6B  is a drawing of a stent that can used as a docking element that has a polymer covering on the inside and outside. 
         FIG. 7  is a tubular implant that can be used to bypass the stomach, duodenum or other intestinal lumen. 
         FIG. 8  is a drawing of a delivery catheter for the docking element and tubular implant. 
         FIG. 9A  is a cross sectional view of a portion of the digestive tract in the body. A delivery catheter with a docking element and tubular implant loaded onto the catheter are loaded onto an endoscope. The endoscope is then advanced through the esophagus, stomach and into the duodenal bulb. 
         FIG. 9B  is a cross sectional view of a portion of the digestive tract in the body. A delivery catheter with a docking element and tubular implant loaded onto are loaded onto an endoscope. The endoscope is then advanced through the esophagus, stomach and into the duodenal bulb. The outer sheath of the delivery catheter is retracted to partially deploy the docking element into the duodenal bulb. 
         FIG. 10  is a drawing showing the docking element fully deployed into the duodenal bulb. The delivery catheter and endoscope has been has been removed to show clarity 
         FIG. 11  is a drawing showing the endoscope and delivery catheter advanced through the docking element into the duodenum up to the ligament of treitz. 
         FIG. 12  is a drawing showing the endoscope and delivery catheter advanced through the docking element into the duodenum up to the ligament of treitz. The outer sheath of the delivery catheter is retracted to partially expose the tubular implant. 
         FIG. 13  is a drawing showing the endoscope and delivery catheter advanced through the docking element into the duodenum up 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. 14  is a continuation of  FIG. 13  where the outer sheath is retracted further to unsheath the tubular implant up to the duodenal bulb. 
         FIG. 15  is a continuation of  FIG. 14  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. 16  is a drawing of an alternative device and method for deploying the proximal end of the tubular element. 
         FIG. 17A  is a cross sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at the gastro-esophageal junction. The docking element serves as an anti-reflux valve. 
         FIG. 17B  is a cross sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at gastro-esophageal junction. The docking element serves as a restrictive stoma. 
         FIG. 18  is a cross sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at gastro-esophageal junction. The docking element serves as an anti-reflux valve. 
         FIG. 19A  is a stented sleeve with a stent used to hold open the sleeve. The sleeve located from the duodenal bulb to the ligament of treitz. 
         FIG. 19B  is a stented sleeve with a stent used to hold open the sleeve. The sleeve located from the pylorus to the ligament of treitz. 
         FIG. 20  is a stented sleeve with a stent used to hold open the sleeve. The sleeve is located from the stomach antrum to the ligament of treitz. 
         FIG. 21A  is a sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at the gastro-esophageal junction. A docking element and tubular implant is implanted in the duodenum also. 
         FIG. 21B  is a sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at the gastro-esophageal junction. A docking element and tubular sleeve is implanted in the duodenum also. A third implant element bypasses the stomach. 
         FIG. 22A  is a sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at the gastro-esophageal junction. A second docking element and tubular implant is implanted from the esophageal implant to the ligament of treitz. 
         FIG. 22B  is a sectional view of a portion of the digestive tract in the body. A docking element is implanted in the esophagus at gastro-esophageal junction. A docking element and tubular implant is implanted from the esophageal implant to the duodenal bulb. 
         FIG. 23A  is a sectional view of a portion of the digestive tract in the body. A docking element and tubular implant is implanted in the esophagus at the gastro-esophageal junction. The modular implant has an anti-reflux valve. A second docking station and tubular implant is placed in the duodenal bulb and extends to the ligament of treitz. A third docking station and tubular implant connects the esophageal implant and the duodenal implant. 
         FIG. 23B  is a sectional view of a portion of the digestive tract in the body. A docking element and tubular implant is implanted in the esophagus at the gastro-esophageal junction. The modular implant has an-anti reflux valve. A second docking station and tubular implant is placed in the pylorus and extends to the ligament of treitz. A third docking station and tubular implant connects the esophageal implant and the duodenal implant at the pylorus. 
         FIG. 24  is a sectional view of a portion of the digestive tract in the body. A docking element and tubular implant is implanted in the esophagus at gastro-esophageal junction. The modular implant has an-anti reflux valve. A second docking station and tubular implant is placed in the pyloric antrum and extends to the ligament of treitz. A third docking station and tubular implant connects the esophageal implant and the duodenal implant at the pyloric antrum. 
         FIG. 25  is a drawing of a delivery catheter with a docking element loaded onto it. 
         FIG. 26  is a drawing of a delivery catheter with the endoscope inserted through inner diameter of the delivery catheter. 
         FIG. 27  is a drawing of a delivery catheter which is designed to be inserted through the working channel of the endoscope. 
         FIG. 28  is a drawing of a delivery catheter with a docking element and tubular implant loaded onto it. 
         FIGS. 29-35  show a variety of stents that can be used as a docking element. 
         FIG. 36A  is a drawing of a stent that can be used as a docking element. 
         FIG. 36B  is a drawing of a stent that can be used as a docking element. 
         FIGS. 37-39  show docking elements. 
         FIG. 40A  is an expandable ring that can attached to a sleeve to form a tubular implant. 
         FIG. 40B  is an expandable ring that can attached to a sleeve to form a tubular implant. 
         FIG. 40C  is an expandable ring that can attached to a sleeve to form a tubular implant. 
         FIG. 41  is a tubular implant that uses an expandable ring as in  FIG. 40A ,  40 B or  40 C as an anchoring means. 
         FIG. 42  is a tubular implant that uses an expandable ring as in  FIG. 40A ,  40 B or  40 C as an anchoring means. The tubular implant is placed and secured within a docking element. 
         FIG. 43  is a tubular implant that uses an expandable ring as in  FIG. 40A ,  40 B or  40 C as an anchoring means. The tubular implant is expanded and secured within the docking element. 
         FIG. 44  is a drawing of a docking element which uses hook and loop to secure the tubular implant to docking element. 
         FIG. 45A  is a drawing of a tubular implant that has magnets in the wall to allow attachment to another tubular implant or to a docking element. 
         FIG. 45B  is a drawing of a tubular implant that has magnets in the wall to allow attachment to another tubular implant or to a docking element, it has a female receptacle to allow attachment to a docking element or other tubular implant. 
         FIGS. 46A and 46B  show tubular implants. 
         FIGS. 47A and 47B  show tubular implants in which the sleeve has longitudinal or circumferential pleats, respectively. 
         FIGS. 48A and 48B  show tubular implants or sleeves with a magnetic attachment means. 
         FIG. 49  is a drawing of a tubular implant or sleeve with barbs to attach to attach to tissue or to a docking element. 
         FIG. 50A  is a drawing of a tubular implant or sleeve with pockets to insert magnets to allow attachment to a docking element or to another tubular implant. 
         FIG. 50B  is a drawing of a tubular implant or sleeve with hooks to attach docking element or another tubular implant. 
         FIG. 51A  is a conical or tapered shaped docking element or tubular implant. 
         FIG. 51B  is a docking element or tubular implant with a stepped diameter. 
         FIG. 52  is a tubular implant that has hook and loop (velcro) attachment means to attach to a docking element or another tubular implant. 
         FIG. 53A  is an over the wire balloon catheter for delivering and expanding balloon expandable stents for a docking element. 
         FIG. 53B  is a rapid exchange balloon catheter for delivering and expanding balloon expandable stents for a docking element. 
         FIG. 54  shows a docking element design with a single-braided or laser-cut design placed at the pyloric junction. 
         FIG. 55  shows another docking element designed where the stomach side of docking element is more disk-like. 
         FIGS. 56 and 57  show docking elements of  FIG. 55  and  FIG. 56  covered with fabric or polymer sheets in areas where they contact tissue. 
         FIG. 58  shows a different design of the docking element placed within the pylorus, where two metallic elements (one on the stomach side and one on the duodenal side) are connected by a flexible sleeve element 
         FIG. 59  depicts the docking element of  FIG. 58  where the flexible sleeve element has expanded with the opening of the pyloric valve. 
         FIG. 60  depicts another docking element design incorporating a flexible sleeve element. 
         FIG. 61  depicts a tubular implant which can be reversibly attached to various compatible docking elements described elsewhere such as those shown in  FIG. 54  through  FIG. 58 . 
         FIG. 62  shows delivery of the tubular implant of  FIG. 61  close to the docking element of  FIG. 54 . 
         FIG. 63  depicts the docking element and the tubular element mated together upon release from the delivery catheter 
         FIG. 64  shows where the tubular element is now attached to the docking element of  FIG. 58   
         FIG. 65  shows a situation where the tubular element is attached to the docking element of  FIG. 58  on the stomach portion of the docking element. 
         FIGS. 66-78  show schematic views of various stages of an implantation method according to embodiments of the invention. 
     
    
    
     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 an embodiment of the invention implanted in 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 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. The small intestine is comprised of three sections. The duodenum  112 , jejunum  113  and 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 in  FIG. 1 , a docking or anchoring element  110  is implanted in the duodenal bulb  107  and a tubular or therapy implant  111  is attached to the docking element and extended into the duodenum  112  to the ligament of treitz  109 . In this embodiment, magnets  135  on the docking element  110  and magnets  136  on the tubular implant  111  are magnetically attracted to each other and thereby secure the docking element  110  to the therapy implant  111 . According to various exemplary embodiments, the anchoring element  110  includes an expandable structure (e.g., a stent or ring) adapted for anchoring within the duodenal bulb and has a diameter of between about 20 and about 40 mm in its unrestrained expanded configuration. In these embodiments, the magnets  135  on the docking or anchoring element  110  serve as a docking feature for releasably coupling with the magnets  136  of the tubular implant  111 . 
       FIG. 2  is a schematic view of a portion of the digestive tract in a human body. An endoscope  114  has been inserted through the mouth  100 , esophagus  101 , the gastro-esophageal junction  102  and into the stomach  103 . The endoscope  114  further extends into the pyloric antrum  104  to allow visualization of the pylorus  106 . 
       FIG. 3  is a drawing of an endoscope  114 . Endoscopes  114  are commonly 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, for example, having a diameter in the 2 to 4 mm diameter range. It may, for example having a working channel having a diameter in the 2.6 to 3.2 mm range. The outside diameter of the endoscopes are typically in the 8 to 12 mm diameter range depending on whether the endoscope is for diagnostic or therapeutic purposes. 
       FIG. 4A  is a partial sectional view of 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: a proximal hub  122 , a catheter shaft  124 , a distal balloon component  125 , radiopaque marker bands  126 , a distal tip  127 , a guide wire lumen  128 , and an inflation lumen  129 . The distal balloon component  125  can be made, for example, from silicone, silicone polyurethane copolymers, latex, nylon 12, PET (Polyethylene terphalate) Pebax (polyether block amide), polyurethane, polyethelene, polyester elastomer or other suitable polymer. The distal balloon component  125  can be molded into any desired shape, including for example a cylindrical shape, a dog bone shape, or a conical shape. The distal balloon component  125  can be made compliant or noncompliant. The distal balloon component  125  can be bonded to the catheter shaft  124  with glue, heat bonding, solvent bonding, laser welding or any 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 (shown at the top portion of  FIG. 4A ) is a cross section 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  121  can be filled with a radiopaque dye to allow visualization and measurement of the size of the anatomy with a fluoroscope. In the embodiment of  FIG. 4A , 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 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. 4B  is a partial sectional view of 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: a proximal luer  131 , a catheter shaft  124 , a distal balloon component  125 , radiopaque marker bands  126 , a distal tip  127 , a guide wire lumen  128 , and an inflation lumen  129 . The materials of construction will be similar to that of the sizing balloon  121  of  FIG. 4A . The guide wire lumen  128  does not travel the full length of the catheter, it starts at the distal tip  127  and exist out the side of the catheter at distance shorter that that the shorter that the overall catheter length. A guide wire  132  is inserted into the balloon catheter to illustrate the guidewire path through the sizing balloon  134 . As shown in  FIG. 4B , the sizing balloon catheter shaft changes section along its length from a single lumen at section B-B  133  to a dual lumen at section A-A at  124 . 
       FIG. 5  is a schematic view of a portion of the digestive tract in the body. An endoscope  114  is 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 contrast agent. The diameter of the duodenal bulb  107  is measured with a fluoroscope. 
       FIG. 6A  shows various views of a stent that can used as a docking or anchoring element. The stents of this invention can be comprised, for example, of any 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 alloys—MP35N, Elgiloy, L605, Biodur® Carpenter CCM alloy, Titanium and titanium alloys, Ti-6Al-4V/ELI and Ti-6Al-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 the following absorbable metals: Pure Iron and magnesium alloys. The stent may also be comprised of the following plastics: Polyetheretherketone (PEEK), polycarbonate, polyolefin&#39;s, polyethylene&#39;s, 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(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 polymeres: Poly (PGA), Polylactide (PLA), Poly(-caprolactone), Poly(dioxanone) Poly(lactide-coglycolide). Stent  137  stent according to various embodiments 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 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. In some embodiments, the magnets are encapsulated in another metal (e.g., titanium) or polymer to improve corrosion resistance and biocompatibility. 
       FIG. 6B  shows various views of a stent that can used as a docking or anchoring element. 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), Goretex 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, II, III, IV, V, VI-Bovine, porcine, ovine, placental tissue or placental veins or arteries and small intestinal sub-mucosa. 
       FIG. 7  is a tubular therapy implant that can be used to bypass the stomach  103 , duodenum  112  or other intestinal lumens (e.g., a portion or all of the jejunum). 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. According to other embodiments, the magnets  140  may be attached to the outside of the tube  148 . According to various embodiments, the magnets  140  are disposed about a circumference of the tube  148  such that the location of the magnets correspond to locations of corresponding magnets located on the anchoring or docking element. The tubular implants of this invention may be comprised, for example, of the following materials: silicone, polyether block amides (PEBAX), polyurethanes, silicone polyurethane copolymers, Nylon, polyethylene terphalate (PET), Goretex ePTFE, Kevlar, Spectra, Dyneena, polyvinyl chloride (PVC), polyethylene, polyester elastomers or other suitable materials. The thin wall tube length  149  may range from 1 inch in length up to 5 feet in length. The thickness of the thin walled tube will typically be in the range of 0.0001 inches to 0.10 inches. The diameter of the tubular implant will range from typically 25 to 35 mm, but may also range anywhere from 5 mm to 70 mm in diameter. 
     Exemplary tubular elements for performing intra-luminal gastrointestinal therapies, e.g., treating metabolic disorders, which may be used with the system of present invention include, for example, those elements disclosed in any of U.S. Pat. Nos. 4,134,405; 4,314,405; 4,315,509; 4,641,653; 4,763,653; and 5,306,300, each of which is hereby incorporated by reference in its entirety. 
       FIG. 8  is a schematic view of a delivery catheter for a delivering a self expanding docking or anchoring element  110  and tubular or therapy implant  111 , according to various embodiments of the invention. The delivery catheter is constructed with a central lumen  150  sufficiently large to allow the catheter to loaded be 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  155  (between the outer handle  153  and inner handle  154 ) is relatively small. The tubular implant  111  is then compressed around the inner catheter, and the outer sheath is partially closed by advancing the outer sheath handle  153  away from the inner sheath handle  154 . When the tubular implant is completely (or sufficiently) covered by the outer sheath or catheter  151 , the loading process is complete for the tubular implant. The delivery catheter also has a space on the inner catheter  151  for the docking or anchoring implant  110  to be loaded. As shown in  FIG. 8 , the anchoring implant  110  is compressed around the distal portion of the inner catheter  152 . The outer sheath handle  153  is then advanced distally until it completely (or sufficiently) covers and retains the anchoring implant. In one embodiment, the tubular or therapy implant  111  is compressed over the inner catheter and the outer catheter is placed over the outside (left to right in  FIG. 8 ) of the tubular implant  111 . 
     As further shown in  FIG. 8 , according to exemplary embodiments, a stent retainer  159  is attached to the inner catheter. The stent retainer  159  acts to prevent the stent (e.g., the anchoring or docking implant  110 ) from releasing from the delivery catheter prematurely during deployment. The stent retainer is fastened to the inner catheter. The stent retainer  159  can be made from metal or plastic and can be made radiopaque by making from it from a radiopaque 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 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, the reinforcement is preferably either a braid of wire or a coil of wire. The wire cross section can be either round or rectangular. The preferred material for the wire is 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 is preferably reflowed into the reinforcement layer by melting the material and flowing it into the spaces in between the braided wire or the coil wires. 
       FIGS. 9A-16  shows a series of steps in the implantation of the apparatus herein disclosed, according to an exemplary embodiment.  FIG. 9A  is a schematic view of a portion of the digestive tract in the body. A delivery catheter with a docking element  110  and tubular implant  111  loaded onto the catheter are loaded over the outside of an endoscope. The endoscope is then advanced through the esophagus, stomach, such that a distal portion is located in the pylorus or the duodenal bulb.  FIG. 9B  is a schematic view of a portion of the digestive tract in the body. As shown, a delivery catheter with a docking element  110  and tubular implant  111  loaded onto the catheter are loaded onto an endoscope. The endoscope is then advanced through the esophagus, stomach and into the duodenal bulb. The outer sheath or catheter  151  is then retracted by moving outer handle  153  towards inner handle  154  to deploy the docking or anchoring element  110 .  FIG. 10  is a schematic view of a portion of the digestive tract in the body. The drawing shows the docking element  110  fully deployed into the duodenal bulb  107 . The delivery catheter and endoscope have been has been removed to show clarity. 
       FIG. 11  is a schematic view showing the delivery catheter (of  FIG. 9 ), wherein the docking element is fully deployed, further advanced into the duodenum  112  until the distal end of the delivery catheter is disposed at or near the ligament of treitz  109 . Next, as shown in  FIG. 12 , the outer sheath  151  of the delivery catheter is retracted slightly (e.g., 1-3 centimeters) to expose the distal portion of the tubular implant  111 . Also, the tubular implant  111  is advanced forward slightly (e.g., 1-5 centimeters), such that a sufficient amount of the distal end of the tubular implant  111  is disposed beyond the distal most portion of both the inner sheath  152  and the outer sheath  151 . In some embodiments, this is accomplished by use of a third intermediate sleeve to apply a distal force to the tubular implant  111 . In other embodiments, after deploying the anchoring element, the physician removes the endoscope from the patient, loads the tubular implant with a sufficient amount extending distally, then advances the endoscope to the appropriate locations and deploys the tubular implant  111 . 
     Then, in  FIG. 13 , a sizing balloon  121  has been inserted through the working channel  119  on endoscope  114 . The sizing balloon  121  is advanced slightly (e.g., 1-2 inches) 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 to generate sufficient radial force to hold the tubular implant  111  in place in the duodenum  112  near the ligament of treitz  109 . 
     Next, as shown in  FIG. 14 , the outer sheath  151  is retracted further to expose much or most (e.g., all but 1-3 centimeters) of the tubular implant  111 . The outer sheath  151  end is now located at or near the pylorus  106 . Then, a shown in  FIG. 15 , 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 at a location near the proximal end of the tubular implant  111 . The sizing balloon  121  is then reinflated to force or urge the proximal end of the tubular implant  111  into contact with the docking element  110 , such that 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 . The endoscope  114  is then removed and the procedure is complete. 
       FIG. 16  shows an alternative embodiment for securing the proximal end of the tubular implant  111  to the docking element  110 . As shown, according to various embodiments, a Nitinol conical and 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  are configured to have an elastic memory in the open state. When the outer sheath  151  is full retracted the conical forceps open and in turn urge open the proximal end of the tubular implant  111  to seat the magnets on the tubular implant  111  to the magnets on the docking station  110 . 
     At some point during or after implantation of the docking element  110  or the tubular implant  111 , the physician may wish to remove one or both components. Either or both components may be readily removed using any of a number of techniques generally known in the art. One such technique for removing or extracting the stent or stent-like portion of the docking element  110  or the tubular implant  111  involves use of a retrieval hook and a collapsing sheath or overtube. One such exemplary system is disclosed in EP 1 832 250, which is hereby incorporated by reference in its entirety. Other removal or extraction systems are disclosed, for example in each of U.S. Publication 2005/0080480, U.S. Pat. No. 5,474,563, and U.S. Pat. No. 5,749,921, each of which is hereby incorporated by reference in its entirety. 
       FIG. 17A  is a schematic view of a portion of the digestive tract in the body. A docking element  160  is implanted in the esophagus at gastro-esophageal junction  102 . The docking element serves as an anti-reflux valve when the tube  161  is compressed flat by pressure in the stomach  103 .  FIG. 17B  is a schematic view of a portion of the digestive tract in the body. A docking element  162  is implanted in the esophagus at gastro-esophageal junction  102 . The docking element  162  has a neck or narrow portion having an inside diameter less than the diameter of the native gastro-esophageal junction. Due to this reduced diameter, the docking element  162  serves as a restrictive stoma.  FIG. 18  is a schematic view of a portion of the digestive tract in the body. A docking element  164  is implanted in the esophagus at gastro-esophageal junction  102 . A tubular implant  165  is attached to the docking element  164 . The tubular implant can have bi-leaflet reflux valve  166 , a tri-leaflet reflux valve  167 , a quad-leaflet reflux valve  168 , a penta-leaflet reflux valve  169 , a six-leaflet reflux valve  170  or seven-leaflet reflux valve. 
       FIG. 19A  is a schematic view showing an alternative embodiment of the invention, wherein a docking element is not used but a stented sleeve  171  is used. A stent is used to hold open the sleeve and anchor it. The sleeve extends from a proximal end in or near the duodenal bulb  107  to a distal end at or near the ligament of treitz  109 . Those of skill in the art will understand that, in the stented-sleeve construct above, the stent and the sleeve could be mechanically pre-attached, such as by sutures or other chemical and mechanical bonding in which case the expansion of the stent results in anchoring of the stented sleeve structure on to the tissue. On the other hand, the stent could also reside freely within the sleeve at its end and when expanded could press the sleeve against the tissue to anchor it. All the stents and delivery catheters herein disclosed may also be used to deliver and anchor a stented sleeve or deliver a stent within a sleeve to anchor it on to surrounding tissue. 
       FIG. 19B  is an alternative embodiment of the invention wherein a docking element is not used but a stented sleeve  172  is used. A stent is used to hold open the sleeve and anchor it. As shown, in this embodiment, the sleeve extends from a proximal end at or near the pylorus  106  to a distal end at or near the ligament of treitz  109 . Those of skill in the art will understand that in the stented-sleeve construct above the stent and the sleeve could be mechanically pre-attached, such as by sutures or other chemical and mechanical bonding in which case the expansion of the stent results in anchoring of the stented sleeve structure on to the tissue. On the other hand the stent could also reside freely within the sleeve at its end and when expanded could press the sleeve against the tissue to anchor it. All the stents and delivery catheters herein disclosed may also be used to deliver and anchor a stented sleeve or deliver a stent within a sleeve to anchor it on to surrounding tissue. 
       FIG. 20  is an alternative embodiment of the invention wherein a docking element is not used but a stented sleeve  172  is used. A stent is used to hold open the sleeve and anchor it. As shown, in this embodiment, the sleeve extends from a proximal end in the pyloric antrum  104  to a distal end at or near the ligament of treitz  109 . Those of skill in the art will understand that in the stented-sleeve construct above the stent and the sleeve could be mechanically pre-attached, such as by sutures or other chemical and mechanical bonding in which case the expansion of the stent results in anchoring of the stented sleeve structure on to the tissue. On the other hand the stent could also reside freely within the sleeve at its end and when expanded could press the sleeve against the tissue to anchor it. All of the stents and delivery catheters herein disclosed may also be used to deliver and anchor a stented sleeve or deliver a stent within a sleeve to anchor it on to surrounding tissue. 
       FIG. 21A  shows an embodiment of the invention wherein a first docking (or anchoring) element  174  or a stented sleeve is implanted in the gastro-esophageal junction  102  and a second docking (or anchoring) element  175  or stented sleeve is implanted in the duodenal bulb  107 .  FIG. 21B  shows an embodiment of the invention wherein a first docking element  174  or a stented sleeve is implanted in the gastro-esophageal junction  102 , a second docking element  175  or stented sleeve in the duodenal bulb  107 , and a third docking element and tubular implant  176  is implanted to bypass the stomach from  174  to  175 . 
       FIG. 22A  is an alternative embodiment of the invention wherein a first docking element  178  is implanted in the gastro-esophageal junction  102 , a second docking element  177  and tubular implant is implanted extending from the docking element  178  to a distal end at or near the ligament of treitz.  FIG. 22B  is an alternative embodiment of the invention wherein a first docking element  178  is implanted in the gastro-esophageal junction  102 , a second docking element  179  and tubular implant is implanted from the  178  docking element to the duodenal bulb  107 . 
       FIG. 23A  is an alternative embodiment of the invention wherein a first docking element  180 , having an anti-reflux valve, is implanted in the gastro-esophageal junction  102 , a second docking element  181  and tubular implant is implanted from the duodenal bulb  107  to a location at or near the ligament of treitz. A third docking element  182  and tubular implant is implanted from the docking element  180  to the docking element  181 .  FIG. 23B  is an alternative embodiment of the invention wherein a first docking element  180  with an anti-reflux valve is implanted in the gastro-esophageal junction  102 , a second docking element  183  and tubular implant is implanted from a the pylorus  106  to the ligament of treitz. A third docking element  184  and tubular implant is implanted from the  183  docking to the  184  docking element. 
       FIG. 24  is an alternative embodiment of the invention wherein a first docking element  185  with an anti-reflex valve is implanted in the gastro-esophageal junction  102 , a second docking element  186  and tubular implant is implanted from the pyloric antrum  104  to the ligament of treitz. A third docking element and tubular implant  187  is implanted from the docking element  185  to the docking element  186 . As shown, the implant  187  includes a stent or stent-like anchoring element, which is adapted for delivery in a compressed configuration and to engage the first docking element  185  in an expanded configuration. 
       FIG. 25  is a schematic view of a delivery catheter for a self expanding docking element  110 , according to embodiments of the invention. As shown in  FIG. 25 , the catheter is preloaded with the docking element but not the tubular implant. The delivery catheter is constructed with a central lumen  150  sufficiently large to allow the catheter to loaded be over the outside diameter of an endoscope. 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  155  is sufficiently small. Once the tubular implant is loaded over the inner catheter, the outer sheath is partially closed by advancing the outer sheath handle away from the inner sheath handle  154 . The outer sheath  151  is then advanced further until the tubular implant is completely (or sufficiently) covered by the outer sheath. 
     The delivery catheter also has a space on the inner catheter for the implant  110  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 is fastened to the inner catheter. The stent retainer  159  can be made from metal or plastic and can be made radiopaque by making from it from a radiopaque 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 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, the reinforcement is preferably either a braid of wire or a coil of wire. The wire cross section can be either round or rectangular. The preferred material for the wire is 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 is preferably reflowed into the reinforcement layer by melting the material and flowing it into the spaces in between the braided wire or the coil wires. 
       FIG. 26  is a schematic view showing the delivery catheter for the apparatus disclosed loaded over an endoscope.  FIG. 27  is a schematic view of an alternative delivery catheter for a self expanding docking element  110 , tubular implant  111  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 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 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, the reinforcement is preferably either a braid of wire or a coil of wire. The wire cross section can be either round or rectangular. The preferred material for the wire is 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 is preferably 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. 28  is a schematic view of an alternative embodiment drawing of a delivery catheter for a self expanding docking element  110  and tubular implant  111 . As shown in  FIG. 28 , 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 loaded be 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  155  is a sufficiently small. The outer sheath is then partially closed by advancing the outer sheath handle away from the inner sheath handle  154 . The outer sheath  151  is then further advanced until the tubular implant is completely (or sufficiently) covered by the outer sheath. The delivery catheter also has a space on the inner catheter for the modular implant  110  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 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 radioopaque 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 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, the reinforcement is preferably either a braid of wire or a coil of wire. The wire cross section can be either round or rectangular. The preferred material for the wire is 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 is preferably 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. 29  is a drawing of a stent that can used as a docking element. Stent  137  stent is preferably 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  139 . 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, for example, 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. 30  is a drawing of a stent that can be used as a docking or anchoring element  110 . The stent can be laser cut from metal tubing or from a flat sheet of metal. The stent can also be braided or woven from round or flat wire. As shown in  FIG. 30 , the stent has a double-layer mesh construction and it can a have separation between the two layers to allow other mechanical elements attached to mating tubular implant to mechanically interlock with the stent without exerting any anchoring force against the tissue. 
     In the picture shown, the stent has a narrowed diameter in the midpoint of the length this will provide for the stent to anchor more securely in anatomical locations such as the pylorus  106 . According to other embodiments, the stent has a cylindrical or other shape of double layer construction like a dumbbell shape. The mesh of the stent may be left open or it may be covered with a suitable material previously disclosed in this application. Magnets or other mechanical means for attachment of a tubular implant may be incorporated as 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. While the preferred embodiment of the above stent is a double-layer mesh construction, other single or multi-layer constructs which create hollow space within the structure to permit interlocking with other tubular implants could also be used. The space between the two mesh layers of the stent also help prevent or minimize tissue in-growth reaching the second (i.e., inner) layer of the stent and likewise from reaching an tubular or therapy implant coupled to the inner layer of the stent. Preventing or minimizing such tissue in-growth facilitates safe and easy removal (or replacement) of any such tubular or therapy implant. 
       FIG. 31A  is a drawing of a stent that can be used as a docking or anchoring element. The stent can be braided from round or flat wire. As depicted in  FIG. 31A , 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, as 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. 31B  is a drawing of a stent that can be used as a docking element. The stent can be braided from round or flat wire. As depicted in  FIG. 31B , the stent is in the expanded state. The stent may include magnets  140  attached to the stent. The magnets may be on the inside diameter, outside diameter, both the inside or outside diameter or incorporated into the wall. The magnets 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, as previously disclosed in this application. 
       FIG. 32A  is a drawing of a stent that can be used as a docking or anchoring element. The stent may be laser cut from round metal tubing or from a flat sheet of metal. The central portion of the stents 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. 32B  is a drawing of a stent that can be used as a docking element. The stent may be laser cut from round metal tubing or from a flat sheet of metal. The central portion of the stents diameter may be shaped to an hour glass shape to provide increased resistance to stent migration. As shown in  FIG. 32B , 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 for the sheath is full y retracted. Radiopaque markers  191  can be attached to the end of the stent to increase the radiopacity of the stent. A metal insert may be pressed or 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 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. 
       FIG. 33A  is a drawing of a stent that can be used as a docking element. Stent is preferably 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. 33B  is a drawing of a stent that can be used as a docking element. Stent is preferably 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. 34A  is a drawing of a coil stent that can be used as a docking element. Stent is preferably made from round or flat wire. The stent is preferably self expanding, but may be made to be balloon expandable. The stent also may be laser cut into a coil from tubing. The preferred material for the stent is 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.  FIG. 34B  is a drawing of a coil stent that can be used as a docking element. The stent is preferably made from round or flat wire. The stent is preferably self expanding, but may be made to be balloon expandable. The stent also may be laser cut into a coil from tubing. The preferred material for the stent is 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. The stent has magnets  140  and the coil of the stent. The magnets can be used as an attachment means to a tubular implant. 
       FIG. 35  is a drawing of a coil stent that can be used as a docking element. The stent is preferably made from wire or sheet Nitinol metal. Several stents in series adjacent to each other can be used to form the docking element. 
       FIG. 36A  is a drawing of a stent that can be used as a docking element. Stent is preferably laser cut from round metal tubing or from a flat sheet of metal. The stent is shaped to a conical shape to provide increased resistance to stent migration and to more closely fit the anatomy. 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. 36B  is a drawing of a stent that can be used as a docking element. Stent is preferably laser cut from round metal tubing or from a flat sheet of metal. The stent is shaped to a have a stepped diameter to provide increased resistance to stent migration and to more closely fit the anatomy. 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. 37  shows schematic views of a docking element. The docking element is composed of three primary components: A stent  194 , a sleeve material  193  and magnets  140 . The stent can be self expanding or balloon expandable. The sleeve can be any suitable material, as was previously disclosed in this application. The magnets may be attached to the sleeve by adhesive or mechanical fasteners such as rivets, screws, suture or mechanical interlocking. 
       FIG. 38  shows schematic views of a docking element. The docking element is composed of four primary components: A stent  194 , a sleeve material  193 , radio-opaque markers  196  and pockets  195 . The stent can be self expanding or balloon expandable. The sleeve can be made from any suitable material, as was previously disclosed in this application. The pockets  195  are like small sleeves that are created in the sleeve material  194 . The pockets  195  may be made by sewing or by the use of a mechanical fastener. The pockets  195  form receptacles to hold magnets or other fasteners that will be delivered to the pocket, such that the docking element may be assembled in-situ. This design allows much larger magnetic or mechanical fastening elements to be incorporated into the docking element. A guide wire may be inserted into the pockets and the magnets or fasteners can be advanced over the guide wire into the pocket under endoscopic guidance. The sleeve may have holes  197  cut into it to allow some fluid transfer through the docking element if desired. 
       FIG. 39  is a drawing of a docking element. The docking element is composed of four primary components: A stent  194 , a sleeve material  193 , radio-opaque markers  196  and hooks  198 . The stent can be self expanding or balloon expandable. The sleeve can be made from any suitable material as was previously disclosed in this application. The hooks  198  are made from metal or plastic and are attached by adhesive, mechanical means or integrated into the sleeve material. The hooks serve as a docking feature for coupling with a corresponding feature on a tubular implant. The sleeve may have holes  197  in it to allow some fluid transfer through the docking element if desired. 
       FIGS. 40A-40C  show expandable rings that can be attached to a sleeve to form a tubular implant  111 . The rings can be made of metal or plastic and can be self expanding or balloon expandable. In various embodiments, the rings are made of Nitinol. The expandable rings serve as coupling feature that operate to releasably couple the tubular implant  111  to a docking feature on the docking or anchoring element  110 . 
       FIG. 41  is a drawing of a tubular implant. The implant is composed of sleeve material  193 , expandable ring  199 , and a radiopaque marker  196 . The sleeve can be any suitable material as was previously disclosed in this application and the expandable ring can be of any suitable design as disclosed in  FIGS. 40A-40C . Holes  197  can be cut into the sleeve to allow drainage through the sleeve. The expandable ring can be fastened to the sleeve by mechanical fasteners such as suture, wire, clips, or by adhesive or other suitable means.  FIG. 42  is drawing of a tubular implant with expandable ring  199  and sleeve material  193  placed expanded and anchored to a docking or anchoring element (such as, for example, the anchoring element shown in  FIG. 30 ).  FIG. 43  is drawing of a tubular implant with expandable ring  199  and sleeve material  193  placed expanded and anchored to a docking element. The docking element is a modification to  FIG. 30 . The docking element has the two layers of braid or material, but is it cylindrical without the hour glass shape of  FIG. 30 . In both  FIGS. 42 and 43  the coupling feature of the tubular implant is configured to releasably couple to the inner portion of the stent (i.e., the docking feature) of the docking or anchoring element. 
       FIG. 44  shows a docking element composed of three primary components: A stent  194 , a sleeve material  193  and hook and loop fastener (velcro)  200  or  201 . The stent can be self expanding or balloon expandable. The hook and loop fastener may be sewn or glued onto the sleeve material. The tubular implant that fastens to the docking element of this construction must have the hook fastener if the docking station has the loop fastener or vice-versa. 
       FIG. 45A  is a drawing of a tubular implant. The tubular implant is designed to attach to another tubular implant or to a docking station by a magnetic attachment means. The tubular implant has magnets  140  embedded in the wall. Alternatively, the magnets could be located on either or both of the inner and outer walls. The magnets provide for an end-to-end connection method between components.  FIG. 45B  shows a tubular implant with a complementary end or female component to match with the male component of  FIG. 45A . 
       FIG. 46A  shows a basic sleeve that is to be used as a component of a docking station, tubular implant, or for extending a tubular implant. The sleeve has radio-opaque markers  196  and may have holes in the sleeve  197  to allow some fluid flow thru the sleeve if required.  FIG. 46B  shows a basic sleeve that is to be used as a component of a docking station, tubular implant, or for extending a tubular implant. 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. 
       FIG. 47A  shows a basic sleeve that is to be used as a component of a docking station, tubular implant, or for extending a tubular implant. 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 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 may be over the entire length or only a portion of the diameter or length.  FIG. 47B  shows a basic sleeve that is to be used as a component of a docking station, tubular implant, or for extending a tubular implant. The sleeve also has pleats around the circumference  203 . The circumferential pleats will allow the tubular implant or sleeve to bend easier without kinking. 
       FIG. 48A  shows a tubular implant designed to attach to another tubular implant or to a docking station by a magnetic attachment means. The tubular implant has magnets  140  on the outside diameter.  FIG. 48B  shows a tubular implant designed to attach to another tubular implant or to a docking station by a magnetic attachment means. The tubular implant has magnets  140  in the wall thickness. 
       FIG. 49  shows a tubular implant that is constructed with a sleeve  193  material, and set of barbed hooks  204 . Hook  204  has 2 barbs per hook, hook  205  has one barb per hook, hook  206  has no barbs, hook  207  and  208  have different bend angles. The modular implant can attach to a docking element or directly to the anatomy or to another sleeve. 
       FIG. 50A  shows a basic sleeve with pockets  195 . The basic sleeve may be used as part of a docking station or tubular implant.  FIG. 50B  shows a basic sleeve with hooks  198 . The sleeve may be used as part of a docking station or tubular implant.  FIG. 51A  is a basic sleeve with a conical diameter. The sleeve may be used as part of a docking station or tubular implant.  FIG. 51B  is a basic sleeve with a stepped diameter. The simple sleeve may be used as part of a docking station or tubular implant.  FIG. 52  is a basic sleeve with hook and loop fastener (Velcro) on the outside diameter. The sleeve may be used as part of a docking station or tubular implant. 
       FIG. 53A  is a balloon catheter for delivery of stents for docking elements or stented sleeves. The catheter is an over the wire design.  FIG. 53B  is a balloon catheter for delivery of stents for docking elements or stented sleeves. The catheter is of rapid exchange design. 
       FIG. 54  shows an enlarged view of the gastro-intestinal anatomy of the junction between the stomach and the duodenum, including the pyloric antrum  104 , the pylorus  106 , and the duodenal bulb  107 . A soft, braided docking or anchoring element  209  is placed at the pyloric junction (i.e., extending across the pylorus). As shown in  FIG. 54 , the docking element is a variant of the element shown in  FIG. 42  using a single braid. As shown, the docking element  209  is shaped such that it does not exert radial forces on the stomach wall or the duodenal wall for anchoring. It is retained within the pyloric junction due to its shape, which has an outer diameter larger than the maximum outer diameter of the pyloric orifice. As shown in  FIG. 54 , the docking element  209  includes a proximal portion (i.e., the portion located in the pyloric antrum  106 ), a distal portion (i.e., the portion located in the duodenal bulb  107 , and a neck portion adapted to extend through the pylorus  106 . According to various embodiments, the proximal and distal portion are shaped such that each has an unconstrained diameter of between about 15 and about 25 millimeters, and the neck portion has an unconstrained diameter of between about 5 and about 15 millimeters. In some embodiments, the ratio of the diameter of the proximal portion to the diameter of the neck portion is between about 1.2 and about 5. According to various embodiments, the neck portion is formed with an unconstrained diameter smaller than a maximum diameter of the native pylorus, such that the neck portion operates to restrict flow from the stomach into the duodenum (i.e., to function as a restrictive stoma). In other embodiments, the neck portion is formed with an unconstrained diameter larger than a maximum diameter of the native pylorus, such that the neck portion does not restrict flow from the stomach into the duodenum (i.e., through the pylorus). 
       FIG. 55  shows another docking or anchoring element  210  having an alternate shape. In this instance, the proximal portion of the anchoring element  210  (i.e., the portion located on the pyloric antrum side) is more disk-like and serve as a pronounced anchoring/retaining flange for the device. In some embodiments, the anchoring element  210  has a maximum or unconstrained diameter slightly larger than an internal diameter of the pyloric antrum, such that the docking element  210  exerts a slight radial force on the wall of the pyloric antrum. In other embodiments, the unconstrained shape is such that the anchoring element  210  does not exert a radial force on the wall of the pyloric antrum. To minimize or prevent abrasive injury to tissue and tissue in-growth, and to provide for ease of replacement exemplary embodiments of the docking elements  209  and  210  could be covered with flexible woven fabric or nonwoven, extruded polymeric material used in synthetic medical grafts such as polyurethane, silicone, ePTFE, etc.  FIGS. 56 and 57  show exemplary covered embodiments where the docking element includes a covering  211 . 
     According to various embodiments, one or both of the proximal portion and the distal portion of the anchoring element are sized or shaped such that at least a portion of the anchoring element has an unconstrained diameter larger than the diameter of the corresponding anatomical organ (e.g., the pyloric antrum or the duodenal bulb), such that when implanted the anchoring element exerts a radial force upon the wall of the organ. 
       FIG. 58  shows a different design of the docking element, where the docking element  213  now consists of separate proximal (i.e., stomach side) and distal (i.e., duodenal side) metallic braided elements connected by a flexible sleeve (tubular) element  212 . The flexible element  212  could be constructed of materials such as silicone, polyurethane, ePTFE, etc., which are resistant to stomach acid, enzymes and intestinal juices. The flexible element  212  is provides minimal interference to the opening and closing of the pyloric valve.  FIG. 58  depicts the sleeve element in a somewhat compressed state (hence the drawing showing wrinkles to the sleeve  212 .  FIG. 59  depicts the same docking element  213  where the pylorus  106  is now fully open and the sleeve element  212  is an expanded state.  FIG. 60  depicts another docking element  214  where the flexible sleeve element  212  is attached to other docking structures such as the docking element  210  shown in  FIG. 55 . According to various embodiments, the flexible element  212  has an outer diameter substantially similar to the maximum diameter of the native pylorus. The flexible element  212 , for example, may have a diameter of between about 5 and about 15 millimeters. According to other embodiments, the diameter of the flexible element  212  is set somewhat smaller than the maximum diameter of the pylorus, such that the flexible element  212  acts to restrict flow from the stomach into the duodenum. According to various embodiments, the neck portion is attached to the proximal and distal stent portions by a sewing technique. 
       FIG. 61  depicts a tubular implant  215 , which is a variant of the tubular implant of  FIG. 41 . Here, the flexible sleeve portion is more stepped in shape, such as is shown in the tubular implant in  FIG. 51B . The stepped portion of the tubular implant can serve the purpose of acting like a restrictive element for food passage, depending on the choice of dimensions of the inlet and outlet. The tubular element also has ring-like anchoring or coupling features  199  attached to its proximal end similar to the tubular element of  FIG. 41 . 
       FIG. 62  depicts the ring like anchoring elements  199  of the tubular implant  215  of  FIG. 61  constrained in a delivery catheter  216  as it is being withdrawn close to the docking element.  FIG. 63  depicts the docking element and the tubular implant  215  mated together upon release from the delivery catheter. By withdrawing the delivery catheter while the tubular element is anchored in place, the ring like anchoring elements are released from the delivery catheter and expand to their unconstrained set shape and diameter. Upon such expansion, the fingers or protrusions of the coupling feature  199  engage the distal portion of the docking element. In these embodiments, the distal portion of the docking element is sized and shaped such that the protrusion of the coupling feature may extend through the openings (i.e., docking features) in the proximal portion, such that the coupling feature  199  of the tubular implant engages the docking or anchoring element. In addition to providing an anchoring function by resisting forces directed toward the pylorus or stomach, the distal portion of the docking element  209  further provides some amount of structural support to the tubular implant  215 , which help resist kinking, binding or twisting of the tubular implant. 
       FIG. 64  shows the tubular implant  215  attached to the docking element  213  using the same steps as outlined in  FIGS. 62 and 63 .  FIG. 65  shows a variant of the same concept where the tubular element  215  is now attached to the stomach side of the docking element  213 . Here, the delivery catheter will have to withdrawn through the pylorus before activating the release of the ring element. 
     While each of  FIGS. 63-65  show a modular system in which a tubular implant is removably or releasably coupled with a docking or anchoring element, according to other embodiments, the tubular implant is structurally integrated with the docking or anchoring element (e.g., such as is shown in  FIGS. 19-20 ). The tubular implant and docking element may be integrated using a variety of techniques, including for example adhesive bonding, mechanical fastening, sewing, and overmolding. Likewise, according to some embodiments, portions of the system are modular while other portions are integrally formed. For example, according to exemplary embodiments, the anchoring element and tubular implant located within the duodenum are integrally formed and the docking element and tubular implant located at the gastro-esophageal junction and within the stomach are modular. 
       FIGS. 66-78  show schematic views of various stages of an implantation method according to embodiments of the invention.  FIG. 66  shows the initial stage of a minimally invasive method of implanting any of the various embodiments disclosed herein. As shown, the physician has advanced (e.g., endoscopically) a delivery system  300  to the pyloric antrum  104 . The delivery system  300 , according to some embodiments, includes an endoscope for visualization and a dual catheter system for securing the prostheses in a collapsed configuration. According to some embodiments, the delivery system  300  includes each of the components shown in and described with reference to  FIG. 8 . 
     As shown in  FIG. 67 , the physician has successfully guided the delivery system  300  through the pylorus  106 , such that a tip of the delivery system is located within the duodenal bulb  107 . Next, as shown in  FIG. 68 , the physician has actuated the delivery system  300  (e.g., by retracting an outer sheath or catheter), so as to release a distal portion of the docking or anchoring element  110  in the duodenal bulb. As shown, the physician advances the delivery system  300  a sufficient distance to allow the distal portion to fully expand within the duodenal bulb  107  and a neck portion of the anchoring element  110  to expand within the opening of the pylorus  106 . Then, as shown in  FIG. 69 , the delivery system  300  is further actuated to effect release of a proximal portion of the anchoring element  110  with the pyloric antrum  104 . As shown, at this stage, the anchoring element  110  is fully disengaged from the delivery system. As shown in  FIG. 70 , the anchoring element is implanted across the pylorus  106 , such that the proximal portion of the anchoring element engages the proximal surface of the pylorus and the distal portion engages the distal surface of the pylorus. 
     Next, as shown in  FIG. 71 , the delivery system  300 , which holds the tubular or therapy element  111  in a collapsed configuration, is advanced across the pylorus  106  into the duodenal bulb  107 . The delivery system  300 , as shown in  FIG. 72 , is then advanced further down the duodenum (and, as desired, the jejunum), until the tip reaches the desired distal most implant location. Then, as shown in  FIG. 73 , the physician actuates the delivery system  300  (e.g., by retracting an outer catheter), to release a distal portion of the therapy element  111  with the duodenum (or jejunum). Next, as shown in  FIGS. 74-76 , the delivery system is further retracted such that the therapy element  111  is further released from the delivery system  300 . As shown in  FIGS. 77-78 , the therapy element  111  is fully released from the delivery system  300  and has engaged the docking element  110 . 
     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.